Immune Diseases

Question 1

What are the classes of molecules that are involved in inflammation?

Question 2

What are the three different types of inflammatory mediators?

Question 3

Define and list the lipid mediators with brief explanation of its role?

Question 4

Define and list the cytokines with brief explanation of its role?

Question 5

Define and list the chemokines with brief explanation of its role?

Question 6

Describe the process of inflammation and fever?

Answer 6

During inflammation:
Patients experience rubor, pain, a fever (IL-1 driven fever, local warmth driven by prostaglandins from mast cells) and swelling around the inflammation site.

Stages:
Vasodilation + increased permeability of blood vessels.
Widening of blood vessels vasodilations.

Question 7

What are the 4 phases of an inflammatory response?

Answer 7

The inflammatory responses has four phases: inflammatory inducers this can either be an infection or tissue damage. The sensors that detect them mast cells and macrophages. Inflammatory mediators induced by the sensors cytokines, chemokines, etc, and the target tissue that are affected by the inflammatory mediators.

Question 8

What happens when multipotential hematopoietc (Hemocytoblast) stem cells differentiate?

Answer 8

Hemocytoblast or stem cells in the bone marrow differentiate into common myeloid progenitor and common lymphoid progenitor cells.

1-Lymphoid progenitor cells will differentiate into Natural killer cells and small lymphocytes will differentiate into B and T lymphocytes then B lymphocytes will differentiate into Plasma cells.

2- Myeloid progenitor cells will differentiate into Megakaryocyte (form thrombocytes), Erythrocytes, Mast cells, Myeloblast (forms Esoinophil, Basophil, neutrophil and monocytes but monocytes further differentiate into macrophages.

These cells play a major role in immune and autoimmune diseases.

Question 9

What is autoimmunity?

Answer 9

An immune response against self autologous antigens.

Autoimmunity results from some failure of the host’s immune system to distinguish self from non-self.

Question 10

How do cells detect antigens?

Answer 10

Cells detect antigens, which are substances capable of triggering an immune response, through specialised receptors on their surface. The detection of antigens primarily involves cells of the immune system, such as B cells and T cells, equipped with specific receptors designed to recognise and bind to antigens.

1. B cells: B cells have B cell receptors (BCRs) on their surface that can recognise specific antigens. When an antigen matches the BCR on a B cell, it triggers a series of signalling events within the cell. This leads to the activation and proliferation of the B cell, which then differentiates into plasma cells that produce antibodies targeting the antigen.
2. T cells: T cells have T cell receptors (TCRs) that recognise specific antigens presented by specialised cells called antigen-presenting cells (APCs), such as dendritic cells, macrophages, or B cells. These antigens are typically presented on major histocompatibility complex (MHC) molecules. When the TCR on a T cell binds to the antigen-MHC complex, it activates the T cell, leading to the initiation of an immune response.
   Additionally, antigen-presenting cells play a crucial role in detecting antigens and presenting them to T cells. They engulf foreign antigens, process them internally, and display fragments of these antigens on their surface using MHC molecules. This process enables T cells to recognise the presented antigens and initiate an immune response against them.

Overall, the detection of antigens by cells involves specific receptor-ligand interactions between the antigen and the corresponding receptor on the immune cell surface. This recognition is crucial for initiating an immune response against pathogens, foreign substances, or abnormal cells in the body.

Question 11

What is self/non-self discrimination?

Answer 11

Adaptive immune system mounts specific targeted response to foreign antigens without harming self.

Immunogen- a substance capable of eliciting an immune response

Tolerogen- antigens that induce tolerance rather than immune reactivity.

The same compound can be an immunogen and tolerogen depending on how and where it is presented to the immune system.

Slide answer

Self/non-self discrimination in immunity is the ability of the immune system to differentiate between the body’s own cells (self) and foreign or potentially harmful substances (non-self).

The immune system’s primary role is to defend the body against invading pathogens such as bacteria, viruses, and other harmful entities. To accomplish this, it must be able to recognize and distinguish between harmful invaders (non-self) and the body’s own cells and tissues (self).

Cells of the immune system achieve self/non-self discrimination through various mechanisms, including the recognition of specific molecules called antigens. Antigens are typically present on the surface of cells and pathogens. The immune system is trained to recognize these antigens as either belonging to the body (self) or as foreign invaders (non-self).

When the immune system encounters non-self antigens, it triggers an immune response to neutralize or eliminate the foreign substances. However, it’s crucial for the immune system not to attack the body’s own cells, so mechanisms like tolerance and immune regulation prevent immune cells from targeting self-antigens under normal circumstances.

Disruptions in self/non-self discrimination can lead to autoimmune diseases, where the immune system mistakenly attacks the body’s own tissues, or immune deficiencies, where the body fails to adequately respond to foreign invaders.

Question 12

How do we achieve self tolerance?

Answer 12

Segregation of antigens-physical barriers and immune privileged sites like the eyes

Central tolerance: limits the DEVELOPMENT of auto reactive B and T cells.

Peripheral tolerance: regulates auto-reactive cells in the CIRCULATION

Question 13

Why do we have both Central and Peripheral tolerance?

Answer 13

Not all self antigens are expressed in central lymphoid organs where the negative selection occurs

There is a threshold affinity to self antigens before deletion is triggered- some weakly self reactive survive.

Question 14

Why do we need a threshold affinity to self antigens before deletion triggered

Answer 14

The threshold affinity to self-antigens before deletion serves as a critical mechanism in ensuring that T-cells are able to distinguish between the body’s own cells (self) and foreign or potentially harmful cells (non-self).

This threshold allows for the deletion of T-cells that bind too strongly to self-antigens. T-cells with extremely high affinity to self-antigens are more likely to recognize and attack the body’s own cells, leading to autoimmune diseases if left unchecked. By setting a threshold, the immune system eliminates T-cells with overly strong reactions to self-antigens, reducing the risk of immune cells targeting healthy tissues.

This process of negative selection ensures that the T-cell repertoire is more tolerant towards the body’s own antigens while still maintaining the ability to recognize and respond to foreign antigens effectively.

T cells do require a certain threshold of affinity for antigens to effectively carry out their functions. This affinity threshold ensures that T cells can recognize antigens presented by antigen-presenting cells (APCs) through their T cell receptors (TCRs) and MHC molecules.

The TCRs on T cells need to bind with a specific affinity to antigens presented by MHC molecules on APCs to trigger a proper immune response. If the affinity is too low, the T cell might not be activated efficiently. Conversely, if the affinity is too high, it might lead to potential autoimmunity by recognizing self-antigens too strongly, bypassing the immune system’s tolerance mechanisms.

This balance in affinity is crucial for T cells to respond adequately to pathogens while avoiding attacking the body’s own cells, contributing to an effective and regulated immune response.

Question 15

Central tolerance—T lymphocytes?

Answer 15

Immature T-lymphocytes in the thymus gets exposure to self antigens during their development.
T-cell gets exposed to self antigen via antigen presenting cells. APC exposes self antigens via MHC molecular/major histocompatibility complex. We also have the co-stimulatory receptor either CD4/8 we get different reaction from the cell either it reacts strongly, intermediate, weak or none.

Strong= Negative selection Apoptosis
Intermediate= Treg cells
Weak= Positive selection
None= Apoptosis

Question 16

Central tolerance—B lymphocytes?

Answer 16

Immature B lymphocytes in the bone marrow gets exposure to self antigens during development.
Self-antigen will bind to B-cell receptors as well as self-antigens on other cells. B cell will see the antibody Ig-g on cell will react towards self-antigen either with HIGH Avidity or LOW Avidity.

High Avidity= Receptor editing of B cell that will express a new light chain. If with new light chain this receptor will still bind to self-antigen with high avidity it will undergo apoptosis.

Low Avidity= reduced receptor expression and B-cell will become anergic

Question 17

Summaries Central Tolerance for both T-cells and B-cells

Answer 17

Immature T lymphocytes in thymus
- Immature lymphocyte which interacts strongly with self antigen displayed as peptide bound to a self MHC molecule => negative selection - cell undergoes apoptosis
- Some immature T cells that recognise self antigens with high affinity develop into regulatory T cells (TREGS) and enter peripheral tissues
Immature B lymphocytes in bone marrow

• Immature B lymphocyte that recognise self antigen with high avidity undergo receptor editing - reexpress genes to make new light chain of antibody so that no longer specific for self antigen
• If editing fails - negative selection - apoptosis
• If low avidity - antigen receptor expression is reduced and cells become anergic (functionally unresponsive)

Question 18

Peripheral Tolerance-T lymphocytes?

Answer 18

1-Normal response to non-self antigen:
The T-cells become exposed to an antigen they become activated we have costimulation happening and this results in the formation of effector and memory T-cells.

2-Response to self-antigen:
T-cell gets exposed to self antigen
We have the Treg cells these regulatory T-cells make sure T-cell won’t become active this results in

Anergy: functional unresponsiveness, without the necessary costimulatory signals.

Suppression: block in activation by regulatory T-cells.

Deletion- apoptosis

Question 19

Peripheral tolerance B-lymphocytes

Answer 19

Include diagram

Normal response to non-self antigen:
When a non-self antigen is encountered, B-cells become activated and undergo clonal expansion. Helper T-cells release cytokines that aid in the activation of B-cells. This activation leads to the production of plasma cells, which in turn produce antibodies to target and neutralize the non-self antigen.

Response to self antigen:
Self antigen binding to B-cell receptor we don’t have any T-cell activation so we don’t have any helper T-cells releasing cytokines so the B-cell just becomes:

Anergic
Apoptosis
Inhibition of activity via Regulation by inhibitory receptors

Question 20

Peripheral tolerance summary:

Answer 20

Peripheral tolerance - summary
Mature T lymphocytes
• Anergy - without co-stimulation or cell death
• Sensitive to suppression by regulatory T cells
Mature B lymphocytes
• if recognises a self antigen without
T cell help is functionally
inactivated and becomes incapable of responding to that antigen (anergy), or dies by apoptosis, or its activation is suppressed by engagement of inhibitory receptors
* Therefore maintaining T cell tolerance enforces B cell tolerance to the same antigens *

Question 21

Multiply layers of Self tolerance:

Answer 21

1- central tolerance mechanism is deletion and editing and its site of action is in the thymus and bone marrow

2-Antigen segregation mechanism is Physical barrier to self-antigen access to lymphoid systems and site of action is in the
Peripheral organs (e.g. thyroid, pancreas

3-Peripheral anergy mechanism is Cellular inactivation by weak signalling without co-stimulus site of action Secondary lymphoid tissue

4-Regulatory cells mechanism is Suppression by cytokines, intercellular signals site of action Secondary lymphoid tissue

5-Cytokine deviation mechanism is Differentiation to Th2 cells, limiting inflammatory cytokines secretion.
Secondary lymphoid tissue And sites of inflammation

6-Clonal deletion mechanism is Apoptosis post-activation
Secondary lymphoid tissue
And sites of inflammation

Question 22

How does an Autoimmune disease develop?

Answer 22

Autoimmune and immune disease occur when both Central and peripheral tolerance fail. This could be due to genetic factors or wrong environment.

Slides 18:

Autoimmune diseases develop when multiple layers of self tolerance are dysfunctional.

Response to endogenous self antigen that leads to tissue damage.
Since antigen can’t be eliminated, response is sustained.

Results from a combination of GENETIC susceptibility, break down of natural tolerance mechanisms and environmental triggers.

1-AI:

Autoimmune diseases develop when the immune system mistakenly identifies the body’s own cells and tissues as foreign (non-self) and launches an immune response against them. The exact causes of autoimmune diseases are complex and not entirely understood, but several factors contribute to their development:

1. Genetic Predisposition: Certain genetic factors can increase the susceptibility to autoimmune diseases. People with a family history of autoimmune conditions are more likely to develop similar disorders.
2. Environmental Triggers: Environmental factors such as infections, exposure to certain toxins, drugs, or dietary factors might trigger or exacerbate autoimmune responses. Infections can sometimes cause the immune system to react in a way that leads to cross-reactivity against self-antigens.
3. Immune System Dysfunction: Abnormalities or dysregulation in the immune system, including failures in the mechanisms of self-tolerance (both central and peripheral tolerance), can contribute to autoimmune diseases. For instance, deficiencies in regulatory T cells (Tregs) or defects in the mechanisms that control autoreactive lymphocytes can lead to autoimmunity.
4. Tissue Damage and Inflammation: When the immune system targets and attacks the body’s own cells and tissues, it leads to inflammation and tissue damage. This ongoing inflammation and tissue destruction contribute to the symptoms and progression of autoimmune diseases.
5. Molecular Mimicry: Sometimes, antigens from infectious agents might resemble self-antigens. In the process of fighting the infection, the immune system might generate responses that cross-react with similar self-antigens, leading to an autoimmune reaction.

Autoimmune diseases are diverse and can affect various organs and systems in the body, such as the joints (rheumatoid arthritis), skin (psoriasis), thyroid (Hashimoto’s thyroiditis), pancreas (type 1 diabetes), and many others. Each autoimmune condition has its unique set of contributing factors and disease mechanisms.

The interplay between genetic predisposition, environmental triggers, and immune system dysregulation leads to the breakdown of self-tolerance, allowing the immune system to attack the body’s own cells and tissues, resulting in the development and progression of autoimmune diseases.

Question 23

Autoimmune diseases

Answer 23

Immune system is a complex organisation designed to destroy invaders presenting antigens that are non-self

Sufferers have high circulating levels of auto-antibodies

Autoimmune diseases more frequent in women then men, possibly due to oestrogen in females influences immune system to predispose to autoimmune diseases.

The presence of one autoimmune disease increases the chance of developing another simultaneous autoimmune disease.

Question 24

What is the Postulated mechanisms of autoimmunity?

Answer 24

Susceptibility genes and they might lead to self reactive lymphocytes being produced and at the same time if we have inflammation or an infection occurring that causes activation of tissue or antigen presenting cells and at the same time we get influx of self reactive lymphocytes into the tissues and that combined with the active APC in tissue causes activation of self reactive lymphocytes into the tissues causing tissue injury and autoimmune disease

Question 25

What are the genes associated with autoimmunity?

Answer 25

There is a strong genetic component in autoimmune disease
Genetic predisposition of autoimmune diseases we know this because of increased incidence in monozygotic then in dizygotic twins.

Most immune diseases are polygenic and affected individuals inherit multiple genetic polymorphisms that contribute to disease susceptibility.

Strong association of MHC class II genes with the disease,

Question 26

What are the challenges of relating genes to autoimmunity?

Answer 26

It is difficult to relate complex genotypes to phenotypic and functional abnormalities, to better understand pathogenesis.

Identifying disease associated polymorphism have small effects therefore little predictive value

because of small affects of any one gene, targeting these genes therapeutically is unlikely to have significant benefit.

Question 27

What role do infections play in autoimmunity?

Answer 27

Infections trigger autoimmune reactions!!!

Autoimmunity may develop after an infection is eradicated i.e. the autoimmune disease is precipitated by infection but is not directly caused by the infection.

Some autoimmune diseases are prevented by infection( type 1 diabetes, multiple sclerosis and mechanism is unknown similar protection is suggested for asthma. The hygiene hypothesis.

Question 28

What are the three mechanisms of autoimmunity

Answer 28

A- Self tolerance our resting tissue-APC and the chosen self antigen the T-cell is not remotely active and we have self tolerance.

B- Self antigen which is shown by the APC towards the T-cell but now a microbe has infected this APC and that leads to activation of APC so the express other co-stimulatory molecules towards the T-cell and if self reactive T-cells become fully activated and start to destroy and attack our tissues so we have an immune disease now.

C- Molecular mimicry we have an antigen that is presented by APC it is not a self antigen but it is a microbial antigen but it looks very similar to self antigen and a self reactive T-cell with this microbial antigen. We get activation of T-cells and we get an autoimmune disease.

Question 29

Mechanisms of autoimmune damage?

Answer 29

A- Circulating autoantibodies:

.Complement lysis as in haemolytic diseases
.Interaction with cell receptors as in myasthenia Gravis and thyrotoxicosis
.Toxic immune complexes as in systemic lupus erythematosus

. Antibody dependent cellular cytotoxicity possibly in organ specific autoimmune diseases.

. Penetration into living cells

B- T lymphocytes:
.CD4 cells polarised towards Th1 responses via cytokines as in Rheumatoid arthritis, multiple sclerosis, type 1 diabetes.

.CD8 cells activated to become cytotoxic T-cells and cause direct cytolysis

C- Non specific:
. Recruitment of inflammatory leukocytes into autoimmune lesions as in synovitis

Question 30

What are the common autoimmune diseases?

Answer 30

Systemic autoimmune diseases like RA rheumatoid arthritis

Organ specific autoimmune diseases
Myasthenia gravis
Grave disease
Autoimmune diabetes type 1

Question 31

What is organ-specific autoimmunity?

Answer 31

1- accounts off 5-10% of all diagnosed cases of diabetes.

2-autoantibodies against nicotinic acetylcholine receptor are made.

3-the antibodies mimic a ligand, which causes continual stimulation of the thyroid cells.

4-what initiates the disease is not known.

5- Viral Infections are involved in triggering this immune disease

6- Auto-antigens have have been implicated including glutamic acid decarboxylase GAD and insulin itself

7- Ion channel which functions as a receptor in muscle contraction receives input from motor neurons at the neuromuscular synapses and induce muscle contraction.

8-Autoantibodies are directed against the receptor for thyroid stimulating hormones TSH

9-Autoantibodies prevent binding of acetylcholine to the receptor and induce internalisation and degradation of receptor.

10-Cell mediated attack on the islet of langerhans in the endocrine pancreas results in the death of the insulin producing beta cells.

11- causes severe muscle weakness.

Question 32

What organs are immunologically privileged?

Answer 32

Testes, Uterus, Eye, Brain, hamster cheek pouch lol

Question 33

What are the conventional drugs?

Answer 33

Anti-inflammatory drugs like aspirin, ibuprofen. Corticosteroids ( can block TNF and IL-1 production)

Immunosuppressive drugs
Inhibition of lymphocytes proliferation
Ciclosporin A

Question 34

What are the conventional therapies used in the treatment of autoimmune disease?

Answer 34

Non-specific control of autoantibodies:
Infusion of intravenous immunoglobulin IV-IG; antibodies of multiple specificity from a group of healthy donors.
Plasmapheresis= removal of circulating antibodies but short term benefits only

Organ specific:
Insulin in diabetes
Acetylcholinesterase inhibitors in Myasthenia gravis.

Question 35

What happens when a foreign entity enters the cell?

Answer 35

Invasion of foreign entity that enters through epithelial cell layer. Foreign entity will be recognised by mast cells or macrophages in our skin and these cells will start to release different type of mediators, such as lipid mediators(prostaglandins, leukotrienes, platelet-activating factor), cytokines ( TNF, IL-1, IL-6) & chemokines ( CCL2,3,5,1 and CXCL 2&8)

Question 36

What happens when macrophages release cytokines like IL-1?

Answer 36

1-Macrophages ingests a gram negative bacterium via endocytosis

2- Bacterium is degraded in a vacuole, releasing endotoxins that induce the macrophage to produce interleukin IL-1

3- IL-1 is released by the macrophages into the blood stream through which it travels to the hypothalamus of the brain.

4- IL-1 induces the hypothalamus to produce prostaglandins which rest the body’s thermostat to a higher temperature causing fever.

Question 37

Why do we run a fever in response to bacterial infection?

Answer 37

Increased survival rates in ectothermal animals at febrile temperatures after infection with aeromonas hydrophila

Higher percentage of survival rate with increased temperatures
Running a fever is beneficial in keeping bacterial infection under control.
Fever kills the virus or the bacteria that causes the infection.
Fever makes it harder for foreign entity to survive due to temperature denaturing their proteins.
The heat augments the performance of the immune cells induces stress on pathogen and infected cell directly.
Fever slows down the ability of a virus or bacteria to multiply.

Question 38

What are the main symptoms of an inflammation?

Answer 38

Rubor-Redness
Dolour-Pain
Calor- heat, fever
Tumour-Swelling
Function Laesa- loss of function
These 5 symptoms are indicative of an inflammatory response on our body.

Question 39

What causes an inflammation?

Answer 39

Response to cellular insults by:
Infectious agents
Toxins
Physical stresses

Protective response- ultimate goal to remove initial cause of injury and consequences of injury-the necrotic cells and tissues.

Inflammation is a natural response of the immune system to protect the body from harmful stimuli, such as infections, injuries, or damaged cells. It is a complex process involving various cells, chemicals, and signaling pathways.

There are several factors that can cause inflammation:

1. Infection: When the body is invaded by pathogens such as bacteria, viruses, or fungi, the immune system responds by releasing chemicals that attract immune cells to the site of infection. These immune cells then release additional chemicals, such as cytokines, which promote inflammation and help fight off the infection.
2. Tissue injury: Physical trauma, such as cuts, burns, or fractures, can cause tissue damage. The damaged cells release chemicals that trigger an inflammatory response. This response helps to remove debris and initiate the healing process.
3. Autoimmune reactions: In autoimmune diseases, the immune system mistakenly attacks the body’s own cells and tissues. This attack leads to chronic inflammation as the immune system continuously tries to eliminate the perceived threat.
4. Allergic reactions: Allergens, such as pollen, dust mites, or certain foods, can trigger an immune response in individuals with allergies. This immune response can cause inflammation in various parts of the body, leading to symptoms such as itching, redness, and swelling.
5. Chronic conditions: Certain chronic conditions, such as rheumatoid arthritis, inflammatory bowel disease, or asthma, involve ongoing inflammation. In these conditions, the immune system is constantly activated, leading to persistent inflammation and tissue damage.
6. Environmental factors: Exposure to certain environmental factors, such as pollutants, toxins, or irritants, can cause inflammation. For example, inhaling cigarette smoke can lead to lung inflammation.

It’s important to note that while inflammation is a necessary response for the body’s defense and healing, chronic or excessive inflammation can be harmful. Prolonged inflammation can contribute to the development of various diseases, including cardiovascular diseases, diabetes, and certain types of cancer. Therefore, it is crucial to manage and treat inflammation appropriately to maintain overall health.

Question 40

What is the sequence of an inflammatory response?

Answer 40

1-Insult by trauma or pathogen causes ACUTE PHASE REACTION

2-Platelet adhesion, transient vasoconstriction of efferent vessels ( controls blood loss efferent conveying or conducting away from organ)

3-Cytokines induced vasodilation of afferent vessels increased heat/blood flow to the area)

4-Activation of complement, coagulation, fibrinolytic and kinin systems.

5- leukocytes adhesion

6-increased vascular permeability and extravasation of serum proteins exudates and leukocytes (neutrophils, macrophages, lymphocytes) with resultant tissue swelling

7-Phagocytosis of foreign material with pus formation

8-Wound healing and remodelling

Question 41

Role of cytokines in inflammatory response to cellular insult via pathogen or toxin?

Answer 41

1-Bacteria triggers macrophages to release cytokines. We have acute phase reactions where we release TNF-alpha, IL-1& IL-6.

2- Vasodilation and increased vascular permeability causes redness, heat and swelling. Cells push themselves out of endothelial cell layer into the tissue. This leads to inflammatory cell migration and thus release of inflammatory mediators which cause pain.

3- Inflammatory cells migrate into tissues releasing inflammatory mediators causing pain and they attract more cells. Natural Killer cells and Macrophages migrate into the tissue.

Question 42

What are the cellular and plasma derived components that are involved in the inflammatory response?

Answer 42

Cellular and plasma-derived components, eg:

1-Complement
2-acute phase proteins
3-interferons
4-Cytokines, Chemokines, Adhesion molecules etc
5-Prostaglandins and leukotrienes
6-Histamine
7-Kinins (bradykinin-pain)

Question 43

How do cells migrate into the endothelial cell layer?

Answer 43

Leukocytes and neutrophils are floating in the blood vessel at the site of inflammation, cytokines, and chemokines are released and these chemoattractants are displayed on the endothelial cell surface in the blood vessel.

Neutrophils float around and capture these chemoattractants they slow down and roll over the endothelial cell layer and finally they firmly adhere to cell layer then they can transmigrate through endothelial cel layer to site of inflammation and they can engulf bacteria and employ the resolution of inflammatory response

AI:

During an inflammatory response, cells migrate into the endothelial cell layer through a process called extravasation or diapedesis. This process involves several steps:

1. Activation of endothelial cells: In response to inflammatory signals, endothelial cells lining the blood vessels become activated. They express adhesion molecules on their surface, such as selectins and integrins.
2. Rolling: Activated endothelial cells express selectins that bind to selectin receptors on circulating leukocytes (white blood cells). This interaction causes the leukocytes to roll along the endothelial surface.
3. Adhesion: Chemokines released at the site of inflammation stimulate the leukocytes to upregulate their integrins, which allows them to firmly adhere to the endothelial cells.
4. Transmigration: The leukocytes then undergo transmigration or diapedesis, where they squeeze between the endothelial cells and migrate across the endothelial layer. This is facilitated by the degradation of the basement membrane and the rearrangement of endothelial cell junctions.
5. Migration within the tissue: Once the leukocytes have crossed the endothelial layer, they migrate through the tissue guided by chemotactic signals towards the site of inflammation.

It’s important to note that the process of cell migration into the endothelial cell layer during an inflammatory response can be complex and involve various cell types and signaling molecules.

Question 44

What are the stages of inflammation?

Answer 44

1-Vasodilation
triggered by cell parts: histamine, kinin, prostaglandin, and leukotrienes

2-Migration and margination
Margination describes the binding of phagocytes to the blood vessel

*diapedsis emigration; phagocytes force themselves between the endothelium cells of the blood vessel and migrate into the tissue.

Question 45

What are the pro-inflammatory mediators?

Answer 45

Inflammation is driven by pro-inflammatory mediators are released and then inflammation starts.

1-Acute phase proteins
2-complement
3-kinins
Cytokines:
Pro-inflammatory TNF, IL-1,6
Chemokines CXCL-8, CCL2, CCL5
Growth factor M-CSF, GM-CSF
Adhesion molecules like VCAM-1, ICAM-1 help leukocyte to adhere to blood vessel and allow migration into the tissue
Matrix metalloproteinases-MMP-1,2,9
Clotting factors
Prostaglandins

Question 46

How do cytokines promote inflammation?

Answer 46

Cytokines activate immune and other cells in the local environment

Cytokines recruit immune cells to the environment to attack the offending pathogen/toxin

Growth factors stimulate immune and non-immune cell growth.
Acts as endogenous pyrogens, originate inside the body and is capable of inducing a fever by acting on the hypothalamic thermoregulatory centre.

Induce acute phase proteins in the liver.

AI:

Cytokines play a crucial role in promoting inflammation. They are small proteins released by immune cells that act as signaling molecules to regulate and coordinate immune responses. Here’s how cytokines promote inflammation:

1. Recruitment of immune cells: Cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukins (IL-1, IL-6), attract immune cells to the site of inflammation. They induce the expression of adhesion molecules on endothelial cells, allowing immune cells to adhere to the blood vessel walls and migrate into the inflamed tissue.
2. Activation of immune cells: Cytokines activate immune cells, such as macrophages and neutrophils, to enhance their function in fighting against pathogens. They stimulate phagocytosis, the process by which immune cells engulf and destroy foreign invaders, and increase the production of reactive oxygen species (ROS) to kill bacteria.
3. Vasodilation and increased vascular permeability: Cytokines, such as histamine and prostaglandins, cause vasodilation and increased vascular permeability. Vasodilation leads to the widening of blood vessels, allowing more blood to flow to the site of inflammation. Increased vascular permeability allows immune cells and fluid to leak out of blood vessels into the surrounding tissue, resulting in swelling and redness.
4. Activation of endothelial cells: Cytokines activate endothelial cells, which line the blood vessels, to express adhesion molecules. These adhesion molecules enable the adhesion and migration of immune cells from the bloodstream into the inflamed tissue.
5. Amplification of the immune response: Cytokines act as communication signals between immune cells, amplifying the immune response. They promote the production of more cytokines, leading to a positive feedback loop that further activates immune cells and sustains the inflammatory response.

Overall, cytokines play a crucial role in promoting inflammation by recruiting immune cells, activating them, increasing vascular permeability, and amplifying the immune response. This coordinated response helps to eliminate pathogens, remove damaged tissue, and initiate the healing process.

Question 47

List and state function of Acute phase proteins?

Answer 47

Fluctuate in response to tissue injury and infections
Usually made by hepatocytes
Synthesised in response to pro-inflammatory cytokines and include:

C-reactive proteins: opsonin, labelling pathogen to make it obvious for cells to opsonise them

Fibrinogen: coagulation factor
Serum amyloid A: cell recruitment and MMP inducer

Complement factors: Opsonin, lysis, clumping and chemotaxis

Haptoglobin and ferritin: bund haemoglobin or Fe iron

Question 48

What are pro-inflammatory cytokines?

Answer 48

1-IL-1: vasculature (inflammation), hypothalamus (fever), liver (induces APP)

2- Tumour necrosis factor alpha (TNFalpha): Vasculature (inflammation), liver (induction of APP), induction of cell death, neutrophil activation and cachexia (weakness and wasting of the body due to severe chronic illness)

3- IL-12: NK cells, promotes TH1 subset of T lymphocytes (pro-inflammatory)

4- IL-6: liver (induces APP), influences adaptive immunity (proliferation and antibody segregation by B cells)

5- interferon alpha and beta (IFNa/b):
Induces antiviral state, activates NK cells.

Many cytokines work synergistically and carry out numerous functions.

Numerous cell types respond to and/or secrete these cytokines.

AI:

Pro-inflammatory cytokines promote inflammation and contribute to the immune response against infections, tissue injury, and other challenges to the body’s homeostasis. They can trigger various inflammatory processes and recruit immune cells to the site of infection or injury. Examples of pro-inflammatory cytokines include:

1. Tumor Necrosis Factor-alpha (TNF-α): This cytokine plays a central role in initiating and amplifying inflammatory responses. It can lead to the activation of immune cells and promote inflammation in various tissues.
2. Interleukin-1 (IL-1): IL-1 is another key cytokine in promoting inflammation. It activates immune cells and stimulates the production of other pro-inflammatory molecules.
3. Interleukin-6 (IL-6): IL-6 is involved in the acute phase response to inflammation, and it plays a role in fever and immune cell activation.
4. Interleukin-8 (IL-8): IL-8 is a chemokine that attracts neutrophils, a type of white blood cell, to sites of infection or injury

Question 49

What are Chemokines?

Answer 49

More than 50 small molecular weight proteins that are chemotactic.

4 sub-families: CC, CXC, C, CXXXC which binds to G-protein coupled receptors (CCRs, CXCRs, XCR1, CX3CR1)

Act on different immune cell types
Interleukin 8 (CXCL8) attracts neutrophils
Monocytes chemotactic proteins 1 (MCP1/CCL2) attracts monocytes Eotaxin CCL11 attracts eosinophils

Redundancy and overlapping functions.

AI:

CC Chemokines (CCL2, CCL3, CCL5):
1. Structural Classification: CC chemokines have two adjacent cysteine (C) residues near their amino terminus.

2. Functions: They primarily play roles in the recruitment and activation of monocytes, macrophages, and other immune cells. For example:
   
   • CCL2 (also known as MCP-1): Attracts monocytes and directs them to sites of inflammation or infection.
   • CCL3 (also known as MIP-1α): Attracts and activates various immune cells, including macrophages, T cells, and dendritic cells.
   • CCL5 (also known as RANTES): Regulates the migration of T cells, eosinophils, and basophils.

CXC Chemokines (CXCL2, CXCL8):
1. Structural Classification: CXC chemokines have a single amino acid (X) separating their first two cysteine residues, which are also near the amino terminus.

2. Functions: They are involved in the recruitment of neutrophils and other immune cells to sites of inflammation. For example:
   
   • CXCL2 (also known as MIP-2): Attracts and activates neutrophils, leading to their migration to areas of inflammation.
   • CXCL8 (also known as IL-8): Acts as a major chemoattractant for neutrophils and other white blood cells during inflammation.

In summary, both CC and CXC chemokines are involved in immune cell recruitment and regulation of immune responses, but they have different specificities for attracting different types of immune cells. CC chemokines often play a role in monocyte and T cell recruitment, while CXC chemokines are particularly important for neutrophil recruitment during inflammation. The specific functions of each chemokine can vary depending on the context of the immune response and the type of infection or injury involved.

Chemokines are a diverse group of signaling molecules, and their classification as pro-inflammatory or anti-inflammatory can vary depending on their specific roles in different contexts and conditions.

Pro-Inflammatory Chemokines:
Pro-inflammatory chemokines typically attract immune cells to sites of infection, injury, or inflammation, promoting an inflammatory response. Examples of pro-inflammatory chemokines include:

1. CXCL8 (Interleukin-8): CXCL8 is a potent pro-inflammatory chemokine that attracts neutrophils, a type of white blood cell, to sites of infection or inflammation.
2. CXCL1 (Gro-alpha): CXCL1 is another chemokine that attracts neutrophils and promotes inflammation.
3. CCL2 (Monocyte Chemoattractant Protein-1 or MCP-1): CCL2 plays a role in recruiting monocytes, a type of white blood cell, to sites of inflammation.
4. CCL5 (RANTES): CCL5 can attract T cells and eosinophils to sites of inflammation and is involved in the immune response.
5. CXCL10 (Interferon-gamma-Inducible Protein-10 or IP-10): CXCL10 is associated with the recruitment of T cells, particularly during viral infections

Question 50

What is the role of adhesion molecules?

Answer 50

Adhesion molecules are transmembrane receptors that bind either or to other cells or extracellular matrix

4 classes:
1-IG super family VCWM-1, ICAM-1, LFA-2
Cadherins E,P,N cell-cell adhesion
Selectins E,P,L recognise carbohydrates
Integrins- 8 subfamilies, eg a4B1 ECM and cell-cell.

AI:

That’s correct! Adhesion molecules can be categorized into different classes based on their structure and function. Here’s a breakdown of the four classes you mentioned:

1. Immunoglobulin Superfamily (IgSF): This class includes adhesion molecules such as VCAM-1, ICAM-1, and LFA-2. IgSF molecules play a crucial role in cell-cell adhesion and immune responses. They have extracellular domains that contain immunoglobulin-like repeats, which are involved in binding to other cells or molecules.
2. Cadherins: Cadherins are adhesion molecules involved in cell-cell adhesion. They play a critical role in tissue formation and maintenance. Examples include E-cadherin, P-cadherin, and N-cadherin. Cadherins mediate calcium-dependent interactions between cells, contributing to the establishment and stability of cell-cell contacts.
3. Selectins: Selectins are adhesion molecules that recognize and bind to carbohydrates on the surface of other cells or molecules. There are three types of selectins: E-selectin, P-selectin, and L-selectin. Selectins play a crucial role in leukocyte trafficking and inflammation by facilitating the interaction between circulating leukocytes and the endothelial lining of blood vessels.
4. Integrins: Integrins are a diverse class of adhesion molecules composed of two non-covalently linked subunits, α and β. There are eight subfamilies of integrins, each with different α and β subunit combinations. Integrins are involved in both cell-cell adhesion and cell-extracellular matrix (ECM) adhesion. They mediate cell attachment to the ECM and facilitate cell migration and signaling.

These four classes of adhesion molecules play distinct roles in various physiological processes, including cell adhesion, immune responses, tissue morphogenesis, and wound healing. Their interactions and functions are critical for the proper functioning and development of tissues and organs.

Question 51

Endothelial cell adhesion molecules

Answer 51

Slide 49: diagram

Endothelial cells release MCP-1, IL-8, this attracts neutrophils and monocytes in the blood vessel but they need to get out of the blood vessel and get into tissue via endothelial cell layer so they bind to different adhesion molecules.

They roll across endothelial cell layer slowly, eventually adhere to ICAM and VCAM and transmigrate through endothelial cell layer via PECAM and CD99 that is how we get monocytes, neutrophil and WBC into tissue.

Question 52

Role of Metalloproteinases?

Answer 52

Metalloproteinases involved in inflammation.
Proteases whose catalytic function requires metal, usually zinc.

3 main families:
MMPs
ADAMS
ADAMTS
Redundancy in the families- many have similar functions

Matrix metalloproteinases:
Degrade and remodel extracellular matrix and create Chemokine gradients

ADAMs cleave cytokines and adhesion molecule receptors from cell surface

ADAMTs
Cleave receptors and degrade proteoglycans

AI:

Metalloproteinases are a group of proteolytic enzymes that require a metal ion, typically zinc, for their catalytic activity.

There are three main families of metalloproteinases associated with inflammation: MMPs, ADAMs, and ADAMTS.

1. Matrix Metalloproteinases (MMPs): MMPs are a family of enzymes that degrade components of the extracellular matrix (ECM), such as collagen, elastin, and proteoglycans. They are involved in tissue remodeling during normal physiological processes like wound healing and development. However, dysregulation of MMP activity is associated with chronic inflammation and tissue damage. MMPs have been implicated in diseases such as rheumatoid arthritis, atherosclerosis, and cancer.
2. A Disintegrin and Metalloproteinases (ADAMs): ADAMs are a family of transmembrane proteins with both proteolytic and cell adhesion functions. They are involved in cell adhesion, cell signaling, and proteolytic processing of membrane proteins. Some ADAMs, such as ADAM17 (also known as TNF-alpha converting enzyme or TACE), are responsible for the shedding of cell surface proteins, including cytokines, growth factors, and receptors. This shedding process can generate soluble forms of these proteins that contribute to inflammation.
3. A Disintegrin and Metalloproteinase with Thrombospondin Motifs (ADAMTS): ADAMTS enzymes are closely related to ADAMs, but they also contain additional thrombospondin type 1 motifs. ADAMTS enzymes have been primarily associated with the degradation and remodeling of the extracellular matrix components, including proteoglycans and aggrecan. They play essential roles in tissue development, wound healing, and the pathogenesis of inflammatory conditions such as arthritis.

Although there is some overlap in the functions of these metalloproteinase families, each family has distinct substrates and regulatory mechanisms. The redundancy within the families allows for compensation and ensures that the overall proteolytic activity required for tissue remodeling and inflammation is maintained. Dysregulation of metalloproteinases can lead to tissue damage, chronic inflammation, and the progression of various diseases.

Question 53

Extracellular matrix proteins ECM

Answer 53

Collagen type I, II, III fibrillar found in bone skin and cartilage
Collagen type IV- basement membrane
Laminin, elastin, proteogylcans, aggrecan, fibronectin, matrilin, nidogen.

Important in providing a layer over cells and allowing cells to interact with each other.

AI:

It seems like you’re mentioning different types of proteins found in our body. Let me provide some information about each of them:

1. Collagen Type I, II, III: Collagen is a protein that provides strength and structure to our body tissues. Type I collagen is the most abundant and is found in our bones, tendons, ligaments, and skin. Type II collagen is mainly found in cartilage, which helps cushion our joints. Type III collagen is commonly found alongside type I collagen, providing support to organs and blood vessels.
2. Collagen Type IV: Unlike the fibrillar collagens, type IV collagen is a non-fibrillar collagen that forms the structural framework of the basement membrane. The basement membrane is a thin layer that separates different tissues and organs, providing support and acting as a filter.
3. Laminin: Laminin is a protein that is an essential component of the extracellular matrix, which is the space between cells. Laminin helps cells attach to the extracellular matrix and plays a role in cell signaling and tissue development.
4. Elastin: Elastin is a protein that gives tissues elasticity and allows them to stretch and recoil. It is found in tissues that need to be flexible, such as skin, blood vessels, and lungs.
5. Proteoglycans: Proteoglycans are proteins that are heavily glycosylated, meaning they have many sugar molecules attached to them. They are important components of the extracellular matrix and provide structural support, hydration, and binding sites for other molecules.
6. Aggrecan: Aggrecan is a specific proteoglycan found mainly in cartilage. It helps to retain water within the cartilage, providing cushioning and shock absorption for our joints.
7. Fibronectin: Fibronectin is a glycoprotein that helps cells attach to the extracellular matrix and plays a role in cell adhesion, migration, and wound healing.
8. Matrilin: Matrilin is a protein that is involved in the formation and maintenance of cartilage tissues. It helps to organize collagen fibers and provides structural support to cartilage.
9. Nidogen: Nidogen, also known as entactin, is a protein found in the basement membrane. It helps to stabilize the structure of the basement membrane and promotes cell adhesion.

These proteins play important roles in maintaining the structure, function, and integrity of various tissues in our body. They are involved in processes such as cell attachment, tissue development, and providing mechanical support.

Question 54

Nf-kB

Answer 54

Family of transcription factors that regulate hundreds of
pro-inflammatory mediators, including:

Cytokines—TNF, IL-1,IL-6
Chemokines and their receptors—VCAM-1, ICAM-1, E and P-selectin, NCAM-1, MadCAM, CD44.

MMPs—MMP-3, MMP-9

Growth factors GM-CSF, M-CSF
Acute phase proteins-SAA

AI:

The family of transcription factors that regulate the expression of pro-inflammatory mediators, including the ones you mentioned, are called nuclear factor-kappa B (NF-κB) and activator protein 1 (AP-1). Let me provide more information about each of these pro-inflammatory mediators:

1. Cytokines:
   - Tumor Necrosis Factor (TNF): TNF is a cytokine that plays a crucial role in inflammation. It is involved in various immune responses and can promote the production of other cytokines.

• Interleukin-1 (IL-1): IL-1 is another pro-inflammatory cytokine that is involved in the regulation of immune responses and inflammation.
• Interleukin-6 (IL-6): IL-6 is a cytokine that is involved in the immune response, inflammation, and the regulation of other cytokines.

2. Chemokines and their receptors:
   - VCAM-1, ICAM-1: These are adhesion molecules that are involved in the recruitment and adhesion of immune cells to the site of inflammation.
   - E and P-selectin: These are also adhesion molecules that facilitate the recruitment of immune cells to the site of inflammation.
   - NCAM-1: Neural Cell Adhesion Molecule-1 is involved in cell adhesion and migration in various tissues, including the immune system.
   - MadCAM: Mucosal addressin cell adhesion molecule is involved in the recruitment of immune cells to the mucosal tissues.
   - CD44: CD44 is a cell surface glycoprotein that plays a role in cell adhesion, migration, and inflammation.
3. Matrix Metalloproteinases (MMPs):
   - MMP-3 and MMP-9: These are enzymes that are involved in the breakdown of extracellular matrix components. They play a role in tissue remodeling and inflammation.
4. Growth factors:
   - Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) and Macrophage Colony-Stimulating Factor (M-CSF): These growth factors stimulate the production and differentiation of immune cells, particularly granulocytes and macrophages.
5. Acute phase proteins:
   - Serum Amyloid A (SAA): SAA is an acute phase protein that is produced in response to inflammation and tissue damage. It is involved in the regulation of the immune response and can promote inflammation.

NF-κB and AP-1 transcription factors play a crucial role in the regulation of these pro-inflammatory mediators. They are activated in response to various stimuli, such as infection, tissue damage, and inflammatory signals, leading to the production of these mediators. Their activation is tightly regulated to ensure a balanced immune response and to prevent excessive inflammation.

Question 55

How does Nf-kB get activated?

Answer 55

In a normal cell we have Nf-kB bound to another cell called IKB which is an inhibitor of Nf-kB but if we have a DNA damage or pro-inflammatory cytokines or viral or bacterial infection we get proteins activated inside the cell IKB-kinase will phosphorylate IKB it will be degraded broken down into smaller molecules releasing Nf-kB this results in its migration into nucleus, in the nucleus it binds into the promotor sequence and drive the transcription of pro inflammatory chemokine, cytokines, APPs, Nf-kB transcriptase DNA into RNA.

AI:

In a normal cell, NF-κB is bound to an inhibitor protein called IκB (inhibitor of NF-κB). This complex keeps NF-κB inactive in the cytoplasm.

However, when the cell experiences certain stimuli like DNA damage, pro-inflammatory cytokines, viral or bacterial infection, or other inflammatory signals, the IκB kinase (IKK) is activated. IKK phosphorylates IκB, marking it for degradation by the proteasome. This degradation releases NF-κB from its inhibitor, allowing it to migrate into the nucleus.

Once in the nucleus, NF-κB binds to specific DNA sequences called promoter sequences, which are located upstream of genes responsible for pro-inflammatory chemokines, cytokines, acute phase proteins (APPs), and other inflammatory mediators. This binding of NF-κB to the promoter sequences helps to recruit other transcriptional co-activators and initiate the transcription of these pro-inflammatory genes.

The transcription process converts the information in the DNA sequence into RNA molecules, which can then be translated into proteins. In the case of NF-κB, it acts as a transcription factor and drives the transcription of pro-inflammatory chemokines, cytokines, acute phase proteins, and other genes involved in the inflammatory response.

Overall, this process of NF-κB activation and translocation to the nucleus plays a crucial role in regulating the expression of pro-inflammatory mediators and orchestrating the immune response to various stimuli and infections.

Question 56

II-stage of inflammation

Answer 56

Phagocytes are attracted via chemokines and chemotaxis like TNF, IL-1, IL-8, MCP, LPS
These chemoattractants attract phagocytes to site of inflammation
So now we have the neutrophils, macrophages and they destroy the micro-organisms and any changed/mutated or dead cells

Final stage is Tissue repair: all dead and damaged cells are rebuild and the whole system goes back to basal.

Question 57

The inflammatory response overview

Answer 57

Phase I: chemokine, cytokines (TNF,IL-1) CAMs, MMPs, Prostaglandins are released and these molecules initiate inflammation.

Phase II: phagocytosis and apoptosis occurring when the cells are degrading infectious agents or foreign agents and over time they will underground apoptosis too

Finally we have resolution where everything returns to normal physiology.
The inflammatory response is like a balance in phase we have all pro inflammatory mediators are released like cytokines, chemokines, adhesion molecules, MMPs, complement.

Overtime it changes and we get a balanced effect in phase II when resolution occurs and retiring back to normal physiology, the anti-inflammatory mediators play a major role here to counteract the
pro-inflammatory mediators.

Question 58

What are the anti-inflammatory mediators?

Answer 58

Anti-inflammatory cytokines-IL10
Soluble adhesion molecules
TIMPs-inhibit MMPs
Plasmin activation system clot recedes
Opioid peptides counteract pain
Resolvins/Protectins— anti-inflammatory lipid mediators

AI:

1. Anti-inflammatory cytokines: Interleukin-10 (IL-10) is an example of an anti-inflammatory cytokine. It helps to suppress inflammation and reduce the immune response.
2. Soluble adhesion molecules: These molecules help to prevent excessive immune cell activation and migration, which can lead to inflammation. They function by blocking the adhesion of immune cells to blood vessel walls.
3. Tissue Inhibitors of Metalloproteinases (TIMPs): TIMPs are proteins that inhibit the activity of matrix metalloproteinases (MMPs). MMPs are enzymes that contribute to tissue degradation and inflammation. By inhibiting MMPs, TIMPs help to reduce inflammation and tissue damage.
4. Plasmin Activation System: The plasmin activation system plays a role in the breakdown of blood clots. When a clot forms during inflammation, the plasmin activation system helps to break down the clot and promote clot receding, which can reduce inflammation.
5. Opioid Peptides: Opioid peptides are natural pain-relieving substances produced by the body. They can counteract pain signals and have anti-inflammatory effects, reducing both pain and inflammation.
6. Resolvins/Protectins: Resolvins and protectins are types of specialized pro-resolving lipid mediators. They are produced during the resolution phase of inflammation and help to actively resolve inflammation, promoting tissue healing and reducing inflammation.

These anti-inflammatory mediators work together to regulate and dampen the inflammatory response in the body, promoting healing and tissue repair.

Question 59

Role of pro-inflammatory and anti-inflammatory mediators in phase I&II of the inflammatory response?

Answer 59

Phase I: pro-inflammatory mediators like cytokines (TNFa, IL-1&6), chemokine (CCL 1,2,3,5, CXCL 2,8), CAMs, MMPs, Lipid mediators)
play a role in initiating inflammatory response in response to toxin, pathogen or foreign antigen and physical stress this helps the body to fight and eliminate physical threat to body.

Phase II: anti-inflammatory mediators like cytokines (TGFb, IL-4,10), soluble receptors, TIMPs, Lipoxins/ resolvins play a role in resolution of inflammatory response to help cells return to normal physiological function.

Balance between both pro and anti-inflammatory mediators is essential to maintaining a healthy inflammatory responses, any distributions or imbalance may lead or immunodeficiency or autoimmune diseases.

Question 60

Define acute and chronic inflammation? What is the difference between acute and chronic inflammation?

Answer 60

Acute inflammation: necessary part of immune responses but if it’s excessive leads to organ failure and death.

Acute inflammation is when resolution occurs and cells go back to normal physiology

Chronic inflammation:
Inappropriate with tissue destruction and it leads to diseases like autoimmune, neurodegenerative and chronic age-related disorders.
Chronic inflammation occurs when resolution is absent and cells can’t go back to normal physiological state this results in an ongoing acute inflammation where cells keep releasing chemokine, cytokines, MMPs, CAMs and lipid mediators. This chronic inflammation leads to abscess formation, excess scarring and autoimmunity.
There are some anti-inflammatory therapies that can help in preventing and counteracting chronic inflammation.

Question 61

Summary

Answer 61

Summary
• The inflammatory response plays a very important role in homeostasis
• Chronic inflammation and inflammatory diseases result when there is no resolution
• Inflammation is a major underlying component of most, if not all, diseases and syndromes
• NF-KB regulates many of the proteins involved in promoting inflammation
• Current anti-inflammatory strategies are not sufficient to treat disease and novel therapies are emerging

Question 62

Current and novel anti-inflammatory therapies

Answer 62

We have
Non-steroidal anti-inflammatory drugs NSAIDS
Steroids
Immunosuppressive agents

Novel therapies:
Anti-cytokine—TNF antibodies
Anti-adhesion molecules-Abs to integrins, ICAM-1
MMP inhibitors
Other small molecules

Question 63

DMARDs disease modifying
anti-rheumatic drugs

Answer 63

The drugs used in initial therapy are the disease modifying anti-rheumatic drugs especially methotrexate and NSAIDs.
NSAIDs only reduce the symptoms, DMARDs aim to halt or reverse underlying disease itself .
The term DMARD is a concept stretches to cover a heterologous group of agents with different chemical structures and mechanism of actions.
DMARDs include methotrexate, sulfasalazine, gold compounds, penicillamine, chloroquine and other anti-malarials abs various immunosuppressants.

Question 64

What is methotrexate?

Answer 64

Methotrexate is a folic acid antagonist with cytotoxic and immunosuppressant activity

It has been useful and reliable anti-rheumatoid action than other DMARDs, but treatment must be closely monitored because of bone marrow depression, causing a drop in white blood cell and platelets counts potentially fatal and liver cirrhosis

It is superior to most other DMARDs in terms of efficacy abs patient tolerance and is often given in conjunction with anti-cytokine drugs.
It’s mechanism of action is unrelated to its effect on folic acid which is routinely administered to prevent blood disorders but May well be connected to its ability to BLOCK ADENOSINE UPTAKE.

Folates are essential for the synthesis of purine nucleotides and thymidylate, which are essential for DNA synthesis and cell division.
Folates consist of 3 elements: a pteridine ring, p-aminobenzoic acid and glutamic acid and methotrexate is close in structure to folates.

Methotrexate can be administered orally, intramuscularly, intravenously and intrathecally.
It has low lipid solubility and thus does not readily cross blood brain barrier but it is taken up into cells by folate transport system and it is metabolised to polyglutamate derivatives which are retained in the cells for weeks or months even in the absence of extracellular drugs.

How does methotrexate exert its effect on thymidylate

It block the DHFR dihydrofolate reductase and therefore prevents nucleotide production.

Question 65

Ciclosporin

Answer 65

*Ciclosporin structure doesn’t obey lipinski rules but orally bioavailable as balance of hydrophilicity and hydrophobicity which makes it sufficient to cross gut membrane

*Main metabolism is through P450 leading to drug interactions.

*It’s a cyclic peptide of 11 amino acids residues with potent immunosuppressive activity but no effect on the acute inflammatory reactions.

*It’s unusual activity which unlike lost earlier immunosuppressants doesn’t entail cytotoxicity.

*Ciclosporin has numerous actions but those of relevance to immunosuppression are:

*Decreased clinal proliferation of T cells, primarily inhibiting IL-2 synthesis and possibly also by decreasing expression of IL-2 receptors.

*Reduced induction and clonal proliferation of cytotoxic T cells from CD8+ precursor T-cells

*Reduced function of the effector T cells responsible for the cell mediated responses (decreased delayed type hypersensitivity)

*Some reduction of T-cells dependent B-cell responses.

• Ciclosporin itself is poorly absorbed by mouth but can be given orally in a more readily absorbed formulation, or by intravenous infusions.

*After oral administration peak plasma concentrations are usually attained in about 3-4hrs the plasma half life is about 24hrs

• Ciclosporin accumulates in most tissues at concentrations three to four times that seen in the plasma.

*Some drugs remain in lymphomyeloid tissue and remains in fat depots for some time after administration has stopped

• The commonest and most serious unwanted effect of Ciclosporin is nephrotoxicity which is thought to be unconnected with calcineurin inhibition.

*It may be a limiting factor in the use of the drug in some patients.
Hepatotoxicity and hypertension can also occur.

*Ciclosporin has no depressant effects on the bone marrow

Question 66

Leflunomide

Answer 66

*Leflunomide used mainly to treat rheumatoid arthritis and occasionally to prevent transplant rejection.

*Leflunomide has a relatively specific inhibitory effect on activated T-cells. It is transformed to a metabolite that inhibits de novo synthesis of pyrimidines by inhibiting di hydro-orate dehydrogenase.

• It’s orally active and well absorbed from the GI tract. It has a long plasma half-life and the active metabolite undergoes enterohepatic circulation.

*Unwanted side effects include diarrhoea, alopecia, raised liver enzymes and a risk of hepatic failure.

*The long half life increases the risk of cumulative toxicity.

Question 67

DMARDs and immunosuppressive drugs

Answer 67

*Gold complexes like Sodium aurothiomalate indicated for progressive RA but it has many side-effects long latency of action.

*Antimalarial like chloroquine, hydroxychloroquine sulfate are used for moderate RA and SLE. Chloroquine used when other therapies fail and hydroxychloroquine are also useful for done skin disorders.

*Methotrexate moderate to severe RA, PS, JRA RA), psoriatic arthritis, and juvenile rheumatoid arthritis. A first choice drug also used in the Crohn’s disease and cancer treatment and is often used in conjunction with other drugs.
Immunomodulators:

*Azathioprine is indicated in RA, IBS and is used when other therapies fail. Also used in transplant rejection, IVS, and eczema.

*Ciclosporin severe RA, AD, PA used when other therapies fail in some skin diseases and transplant rejection.

*Cyclophosphamide severe RA used when other therapies fail

*Leflunomide moderate to severe RA and PA also used in psoriatic arthritis

*NSAIDs sulfasalazine RA,PA,JRA a first choice drug also used in UC

*Penicillin metabolite penicillamine severe RA but it has many side effects but long latency of reaction.

Question 68

What are anti-inflammatory drugs?

Answer 68

Drugs that inhibit the cyclo-oxygenase COX enzyme. This includes the non-steroidal anti-inflammatory drugs NSAIDs and the coxibs.

*Anti rheumatic drugs: the DMARDs together with immunosuppressants

*The glucocorticoids

*Anticytokines and other
bio-pharmaceutical agents

• Antihistamines used for the treatment of allergic inflammation

*Drugs specifically used to control gout

Question 69

NSAIDs

Answer 69

NSAIDs are sometimes called aspirin-like drugs or antipyretic analgesics and they provide symptomatic relief from fever, pain, swelling in chronic joint diseases as well as in acute inflammatory conditions.

Also useful to treat postoperative, dena and menstrual pain as well as headaches and migraines.

*NSAIDs work and act on the fatty acid cyclo-oxygenase the COX enzyme and this enzyme has two main isoforms in the body COX-1&2

*COX-1&2 are highly homologous enzymes but are regulated in different and tissue specific ways.

*They enzymatically combine arachidonic and some other unsaturated fatty acid substrates with molecular oxygen to form unstable intermediates, cyclic endoperoxides which can subsequently be transferred by other enzymes to different prostanoids.

*Lipoxygenases: these are several subtypes which often work sequentially to synthesis leukotrienes, lipoxins and other compounds.

• converted into various prostanoids, including prostaglandins, prostacyclin, and thromboxane.

*COX-1 is constitutively expressed in most tissues and plays a role in maintaining normal physiological functions, such as protecting the gastric mucosa and promoting platelet aggregation.

*COX-2, on the other hand, is induced in response to inflammation and is primarily responsible for the production of prostaglandins that mediate pain, fever, and inflammation.

NSAIDs work by inhibiting the activity of both COX-1 and COX-2 enzymes, thereby reducing the production of prostaglandins. This leads to the alleviation of pain, reduction of fever, and suppression of inflammatory responses.

It is important to note that while NSAIDs are effective in providing symptomatic relief, they do not address the underlying cause of the inflammation or joint disease. They are primarily used for short-term management of symptoms and should be taken under the guidance of a healthcare professional.

Additionally, it is crucial to be aware of the potential side effects of NSAIDs, such as gastrointestinal irritation, increased risk of bleeding, and adverse effects on kidney function. Long-term or high-dose use of NSAIDs can increase the risk of these side effects. Therefore, it is important to use NSAIDs judiciously and follow the recommended dosage and duration of treatment.

If you have any specific concerns or questions about NSAIDs, it is advisable to consult with your healthcare provider for personalized advice and guidance.

Question 70

How are inflammatory mediators produced?

Answer 70

When we get a stimulus from injury
Phospholipase A2 becomes activated and this transforms phospholipids into arachidonic acid

*Cycoloxygenase COX-1&2 transforms arachidonic acid into prostaglandins: PGD2, PGE2, PGF2a, PGI2 & TXA2.

*Lipoxygenases transforms arachidonic acid into leukotrienes like LTB4, LTC4, LTD4 & LTE4.

Question 71

What is the difference between COX-1 & COX-2?

Answer 71

*COX-1 is present in most cells as constitutive enzymes.
It produces prostanoids that act as homeostatic regulators (modulating vascular responses, regulating gastric acid secretion.

*COX-2 is not normally present CNS and renal tissue are important exceptions but is strongly induced by inflammatory stimuli and therefore believed to be more real ent as a target for anti-inflammatory drugs.

Both enzymes catalyse the incorporation of 2 molecules of oxygen O2 into 2 of the unsaturated double bonds in the arachidonic molecule, forming the highly unstable endoperoxides prostaglandins PGG2 and PGH2 which are rapidly transformed in a tissue specific manner by endoperoxides isomerise or synthase enzymes to different types of prostaglandins like PGE2, PGI2 prostacyclin, PGD2, PGF2a abs thromboxane TX(A2), which are the principal bio active end product if this reaction.

The mix of eicosanoids thus produced varies between cell types depending on the particular endoperoxide isomerases or synthases present.

Question 72

How are prostaglandins produced?

Answer 72

Arachidonic acid is transformed by COX-1 into PGE-2, PGI2, TXA2
And by COX-2 into PGE2 prostaglandin , PGI2 prostacyclin ,TXA2 thromboxane. COX-1 have a complete different function in the gI tract, kidney and thrombocyte and regulation of blood flow.

COX-2 is induced by inflammation so the prostaglandin PGE2, prostacyclin PGI2, TXA2 are important for inflammation, fever and pain.

Both of these enzymes COX-1&2 are inhibited by aspirin and ibuprofen.

Question 73

What are the actions of prostanoids?

Answer 73

The prostanoids can affect most tissues and exert a variety of effects.
PGD-2 causes a vasodilation in vascular beds, inhibits platelets aggregation, relaxation of gastrointestinal and uterine muscles, and modification of release of hypothalamic/pituitary hormones.
It has bronchoconstrictor effect through a secondary action on TP receptors.

It may activate chemoattractant receptors on some leukocytes.

PGF2a causes uterine contraction on humans
PGI2 causes vasodilation, inhibition of platelet aggregation, renin release, and natriuresis through effects on tubular reabsorption of Na+.

TXA2 causes vasoconstriction, platelet aggregation and bronchoconstriction.

PGE2 the predominant inflammatory prostanoid has the following effects:

At EP1 receptors it causes contraction of bronchial and gastrointestinal smooth muscles.

At EP2 receptors it causes bronchodilatation, vasodilation, stimulation of intestinal fluid secretion.

At EP3 receptors it causes contraction of intestinal smooth muscles, inhibition of gastric acid.

At EP4 receptors it causes similar effects to those of EP2 stimulation.

Question 74

Role of prostanoids in inflammatory response?

Answer 74

The inflammatory response is inevitably accompanied by the release of prostanoids.
PGE2 predominates although PGI2 is also important

Acute inflammation: PGE2 and PGI2 are generated by the local tissues and blood vessel while mast cells mainly release PGD2

Chronic inflammation: cells of the monocytes/macrophages series also release PGE2 and TXA2. Together the prostanoids exert a yin Yang effect in inflammation stimulating some responses and decreasing others.

The anti-inflammatory and analgesic effect of aspirin like drugs stem largely from their ability to block these actions.

Question 75

Facts about NSAIDs

Answer 75

NSAIDs differ in toxicity and degree of patient acceptability and tolerance, their pharmacological actions are similar with certain exceptions.
Aspirin has other different pharmacological actions and paracetamol is an interesting exception to the general NSAID stereotype.

Question 76

What are the therapeutic effects of COX inhibitors?

Answer 76

These drugs inhibit COX enzymes and therefore prevent prostanoid synthesis in inflammatory cells.
Inhibition of the COX-2 isoform is probably crucial for their therapeutic actions.

Therapeutic action includes:

*An anti-inflammatory action the decrease in PGE2 abs PGI2 reduces vasodilation and indirectly oedema. Accumulation of inflammatory cells is not directly reduced.

*an analgesic effect via decreased prostaglandin generation means less sensitisation of nociceptive nerve ending to inflammatory mediators such as bradykinin and
5-hydroxytryptamine.

*Relief of headache is probably a result of decreased prostaglandin-mediated vasodilation.

*An antipyretic effect: interleukin-1 releases prostaglandins in the CNS where the elevate hypothalamic set point for temperature control thus causing fever, NSAIDs prevent this.

• NSAIDs include Aspirin, Ibuprofen, Naproxen, Indometacin, Piroxicam and paracetamol.

Newer agents with more selective inhibition of COX-2 and thus fewer adverse effects Ik the GI include
Celecoxib and Etoricoxib.

Question 77

What are the side-effects of COX inhibitors?

Answer 77

*Unwanted side-effects stem from the inhibition of the constitutive housekeeping enzymes COX-1 isoform which are common, particularly in the elderly and include the following:

*Dyspepsia, nausea, vomiting, and other GI side-effects. gastric and intestinal damage may occur with chronic use with risk of haemorrhage, ulceration and perforation which can be life threatening. The cause is suppression of gastroprotective prostaglandins in the gastric mucosa.

*Adverse cardiovascular effects. These can occur with many NSAIDs and Coxibs and may be related to inhibition of COX-2 in the kidney or else where leading to hypertension.

*Skin reactions but mechanism is unknown.

*Reversible renal insufficiency. Occurs mainly in patients with compromised renal function when compensatory prostaglandin I2/E2 mediated vasodilation is inhibited.

*Bronchospasm seen in aspirin sensitive asthmatics. Uncommon with coxibs.

• Analgesic-associated nephropathy this occurs after long term high dose regimes of NSAIDs and is often irreversible.

*Liver disorders, bone marrow depression. Relatively uncommon.

Question 78

What are the clinical uses of NSAIDs?

Answer 78

NSAIDs are widely used but cause serious adverse effects especially GI, renal, pulmonary and cardiovascular effects related to their pharmacological actions and idiosyncratic effects. Elderly and patients with pre existing conditions at are high risk.

Main uses:

*Antithrombotic: Aspirin for patients that are at a high risk of arterial thrombosis e.g. following myocardial infarction.
Other NSAIDs that cause less profound inhibition of platelet thromboxane synthesis than aspirin, increase risk of thrombosis and should be avoided in high risk patients.

*Analgesia for headaches, dysmenorrhea, backache, bony metastases, postoperative pain.
Short term use: aspirin, paracetamol, ibuprofen.
Chronic pain: more potent, longer lasting drugs like naproxen, piroxicam often combined with a low potency opioid

Antinflammatory like ibuprofen and naproxen used for symptomatic relief in RA, gout, soft tissue disorders.

Antipyretic: paracetamol

Question 79

Aspirin

Answer 79

Aspirin (acetylsalicylic acid) is the oldest NSAID. It acts by irreversibly inactivating Cyclo-oxygenase COX-1&2.

*in addition of to it is anti-inflammatory actions, aspirin strongly inhibits platelet aggregation and its main clinical use now is in the therapy of CVD.

*Given orally and is rapidly absorbed; 75% is metabolised in the liver.

Unwanted side-effects:

With therapeutic dose: GI disturbances, often including some gastric bleeding usually slight and asymptomatic.

With higher doses: dizziness, deafness and tinnitus (salicylism); compensatory respiratory alkalosis may occur.

With toxic doses ( from self poisoning) uncompensated metabolic acidosis may occur particularly in children.

Aspirin has been linked with rare but serious post viral encephalitis arête syndrome in children and is not used for paediatric purposes not used in under 16.

If given concomitantly with warfarin, aspirin can cause a potentially hazardous increase in the risk of bleeding.

Question 80

Paracetamol

Answer 80

Paracetamol is a commonly used drug OTC.
It has a potent analgesic and antipyretic actions but much weaker anti-inflammatory effects than other NSAIDs.

It is cycling-oxygenase inhibitory actions seems to be mainly restricted to the CNS enzyme.

It is given orally and metabolised in the liver half life 2-4h.

Toxic doses cause nausea and vomiting thrn after 24-48h potentially fatal liver damage by saturating normal conjugating enzymes causing the drug to be converted by mixed function oxidases to N-acetyl-obenzoquinone imine.
If not activated by conjugation with glutathione, this compound reacts with cellular proteins causing tissue damage.

Agents that increase glutathione intravenous acetyl cysteine or oral methionine can prevent liver damage if given early.