Watson Flashcards
Define immunity
Protection from infection or disease
What is autoimmunity
When the target is ones own tissues
Define inflammation
“Set alight” - part of immunity and stimulated by infection and other injury
What’s the point of the inflammatory response?
Natural response of tissue to injury- attacks and removes cause of injury, repair damaged tissue, beneficial, protective, self limiting
What are the two heat sources during inflammation?
Heat in individual tissues
Fever to eliminate infectious agents
What is arthritis
Autoimmune inflammation of joints
Why is there swelling but less redness in arthritis
Because you can’t see increased blood flow, the swelling is due to irreversible tissue remodelling
How do sensory Neurons contribute to the pain during inflammation
Release Neuropeptides which contribute to redness and swelling, substance P, calcitonin gene related peptide
What is substance P
Is a neuropeptide responsible for pain and leaks
What is calcitonin gene related peptide
Neuropeptide responsible for vasodilation and also stimulates mast cells further enhancing signal (+ve feedback)
Role of ATP?
Extra cellular mediator of inflammation
What are prostaglandins released for
Vasodilation
Name two Neuropeptides
Calcitonin gene related peptide
Substance P
What is rheumatoid arthritis
A chronic inflammatory joint disease
In rheumatoid arthritis what is the loss of cartilage and bone erosion mediated by?
Proteinases
Name the proteinase predominantly responsible for the loss of cartilage and bone erosion in RA
Matrix metalloproteinase (MMP)
What is matrix metalloproteinase secreted by?
Tissue cells- synovial fibroblasts and Chondrocytes
What are synovial fibroblasts
They are around the joints and secrete proteinases
Which stains with acidic dye:
Basophil
Eosinophil
Eosinophil
Name three PMN granulocytes
Neutrophils
Eosinophil
Basophils
Are macrophages short lived?
No bbe they live for months
Name 5 types of T cell
T helper (1+2) T cytotoxic Natural killer Th17 Regulatory T cell
What do B cells do?
Mature to become antibody secreting plasma cells
Name 3 mediators rapidly produced from membrane lipids
Eicosanoids (PGE2, PGI2)
Leukotrienes (LBT4)
PAF
Name two ways to increase plasma leakage
1) agents increase plasma leakage via action directly on the endothelium e.g histamine, bradykinin
2) neutrophil activators increase plasma leakage via a neutrophil dependent mechanism
Name 4 substances that increase plasma leakage via a neutrophil dependent mechanism
LTB4
fMLP
C5a
Interleukin-8
What is tritoqualine
Antihistamine- inhibits the enzyme histidine decarboxylase
Name the process of histamine synthesis
L-histidine
Histamine
Imidazolyl acetic acid
Name two enzymes involved in the process of histamine production
Histidine decarboxylase
Histaminase
Define infection
Catching, spreading- involves microbes colonising a host e.g man
What is the triple vascular response
1) local reddening
2) oedema- wheal
3) axon reflex - flare
How many histamine receptors are there?
4
What’s the role of the H1 receptors?
PLC linked- Ca2+elevation
Vasodilator via nitric oxide
Increased vascular permeability- oedema via endothelial contraction
What’s the H2 receptor responsible for
Adenylyl cyclase leading to cAMP elevation
Vasodilator
Potent stimulant of gastric acid secretion
What does the H4 receptor have a role in?
Chemotaxis
Hyper secretion of histamine results in what
Excess acid production and formation of duodenal and peptic ulcers
Is the H2 receptor Gs coupled?
Yeh
Is the H1 receptor Gs coupled
NO it’s Gq
Name a key H1 receptor antagonist
Chlorpheniramine (chlorphenamine- piriton)
Name two newer H1 antagonists that have lower lipophilicity
Astemizole
Loratidine
What are H1 receptor antagonist useful in?
Urticaria
Nasal congestion
Name 2 H2 receptor antagonists
Cimetidine
Ranitidine
Do H2 receptor antagonists interact with other drugs?
Yes especially cimetidine as they inhibit P450
What are eicosanoids derived from
C20 unsaturated fatty acid
What is arachidonic acid?
An essential fatty acid derived from red meat or indirectly via desaturation of linoleic acid
Name the steps and enzymes in the making of prostaglandin H2
Arachidonate -cyclooxygenase 2O2 Prostaglandin G2 -peroxidase 2H+ 2e- Prostaglandin H2
Name the enzyme that converts prostaglandin H2 to prostacyclin
Prostacyclin synthase
What’s the enzyme that converts prostaglandin H2 to thromboxanes
Thromboxane synthases
Name 4 physiological functions of PGs
1) initiation of labour (PGF2a and PGE2)
2) inhibition of gastric acid secretion, increased gastric mucus production (PGE2)
3) vascular PGI2 from endothelium, inhibition of platelet aggregation, vasodilator
4) vascular TXA2 from platelets, causes platelet aggregation, vasoconstrictor
Name 3 leukotrienes
LTB4
LTC4
LTD4
What enzyme converts arachidonate to leukotrienes
Lipoxygenases
Name 3 oxidation products of 20 carbon fatty acids
Arachidonic acid
Dishomo gamma-linoleic acid
Eicosapentanoic acid
Name 4 classical eicosanoids
Prostaglandins
Prostacyclins
Thromboxanes
Leukotrienes
Name 4 non classical eicosanoids
Lipoxins
Resolvins
Isoprostanes
Endocannabinoids
Do non classical eicosanoids have short or long half life?
Short half life
Thromboxanes are produced by what
Platelets
Prostaglandins act via what
Specific GPCRs on target cells
How many PGE2 receptors
There’s 4
EP1-EP4
What’s the receptor for prostacyclin (PGI2)
IP
Name the two PGD2 receptors
DP1 and DP2
DP2 also termed CRTH2
Where are EP2 and IP receptors found
Found on vascular smooth muscle - vasodilator a increase blood flow
What’s the thromboxane receptor
TP on platelets
What’s the PGF2 receptor
FP
If leukocytes are present are EP2 receptors anti or pro inflammatory
Anti-inflammatory
What fibres do prostaglandins sensitise
Peripheral C-fibres
How are prostaglandins involved in fever
Thermoregulatory set point regulated by production and action of PGE2 in the anterior hypothalamus
Cerebroventriclar injection of PGE2 leads to what?
Fever
How many isoforms of cyclo-oxygenase are there?
2- encoded by separate genes
How many COX enzymes are there
3
COX 1
COX 2
COX 3
What does the enzyme COX1 do
Constitutive housekeeping enzyme- products important in normal function of stomach, intestine, kidney and platelets
What’s the enzyme COX2 important in
Induced particularly in inflammatory cells exposed to inflammatory stimuli
Are COX1 and 2 homodimers
Yes
Where are COX1 and 2 found
On the inner membrane of endoplasmic reticulum
COX enzymes are made up of what two sites?
Peroxidase site
Cyclooxygenase site
What serine residue on COX2 is targeted by aspirin
S516
What serine residue on COX1 is targeted by aspirin
S530
NSAIDs selectivity for COX1 and COX2 can be studied pharmacologically as what?
‘Potency ratios’
- the IC50 values for blocking the two enzymes
Name a COX1 selective drug
Flurbiprofen; low dose aspirin
Name 3 COX2 selective drugs
Meloxicam
Celecoxib
Rofecoxib
Name 4 physiological functions of prostaglandins?
1) initiation of labour
2) inhibition of gastric acid secretion, increased gastric mucous production
3) inhibition of platelet aggregation and vasodilation
4) platelet aggregation and vasoconstriction
Why do you have a tendency to bleed using aspirin like drugs?
Due to blocking of housekeeping COX1 and thus reducing the cytoprotective effects of prostaglandins
Platelet COX1 inhibition is beneficial in what?
Thrombosis
Why are selective COX 2 inhibitors bad in thrombosis
Because they affect PGI2 more than TXA2
Name four actions of leukotrienes
Bronchoconstriction
Oedema
Chemotaxis
Present in inflammation
Name two leukotrienes involved in bronchoconstriction
LTC4 and LTD4
Name two leukotrienes involved in oedema independent of neutrophils
LTC4 and LTD4
Name a leukotriene involved in oedema neutrophil dependent
LTB4
Name a leukotriene involved in chemotaxis
LTB4
Name 4 anti leukotriene drugs
Glucocorticoids
Zileuton
Zafirlukast
Montelukast
Name 5 anti eicosanoid therapies
Glucocorticoids Zileuton Zafirlukast Montelukast NSAIDs
Name three ways in which glucocorticoids act on eicosanoids
Inhibit PLA2 transcription
Induce synthesis of endogenous PLA2 inhibitor lipocortin
Inhibit COX2 synthesis
What determines the directional control of leukocyte migration?
Tissue expression of adhesion molecules and chemical stimuli
Name 4 steps of leukocyte diapedesis
Circulating
Tethering/rolling
Firm adhesion
Transmigration
What are selectins important for?
Initial ‘tethering’ of leukocytes to vascular cells
Name the letters of three selectins and state what they’re expressed by:
L- leukocytes
P- platelets (endothelium)
E- endothelium
How is expression of endothelial E-selectin induced?
By cytokines or LPS and expression requires de novo protein synthesis which is slow take 2-6hrs
What are integrins
When the leukocytes roll along endothelial cell surfaces they activate integrins which are Luganda expressed on leukocyte surfaces
What type of protein are integrins?
Heterodimeric proteins
How many heterodimer integrins are formed for leukocytes
3
aL/B2
aM/B2
aX/B2
What’s LAD-2
Leukocyte adhesion deficiency
How is adhesion of leukocytes regulated
Basal expression of integrins
Leukocyte activation induces
1) conformational change- affinity
2) clustering of integrins- avidity
What does ICAM stand for and what are they
Intercellular adhesion molecules
Integrin Ligands
ICAM2
Intercellular adhesion molecule basally expressed on endothelium
ICAM1
Intercellular adhesion molecule induced by cytokines IL1 and TNF
Name an integrin that binds vascular cell adhesion molecule (VCAM)
a4B1 (VLA4) expressed on Eosinophils, monocytes, Tcells
What induces VCAM1
Cytokines
What is natalizumab?
Monoclonal antibody against a4 integrin, it inhibits T lymphocyte interactions with brain endothelium, best results in multiple sclerosis when combined with IFN-B
Chemoattractants are produced by what
Tissues and bacteria
What’s a chemokine
Chemotactic cytokine
Chemokines are produced in response to what?
IL1, TNF, bacteria
Name two classes of chemokine
CXC
CC
Which class of chemokine are neutrophil attractants?
CXC chemokines
In RA, activated tissue cells produce _________ which attract ____________ to the ___________
Chemotaxins (esp chemokines)
Leukocytes
Synovium
In RA, tissue cells and leukocytes are further activated and produce what 4 things
Cytokines
Chemoattractants
Proteases
Reactive oxygen & nitrogen species
What is cartilage?
Connective tissue made up of cells and extra cellular matrix
What is the role of cartilage
Provides smooth robust surface over the bone ends:
- low friction movement
- protects bone from mechanical wear
Cartilage is made up of what cells
Chondrocytes
Joint cartilage comprised mainly what two things?
Fibrous protein
Proteoglycan
What is bone?
Dense connective tissue made up of cells and matrix
- mineralised calcium phosphate matrix
- fibrous protein(collagen)
What is proteoglycan?
Part of cartilage structure: chondroitin sulphate (polysaccharide) linked to aggrecan (core protein), it’s charged (highly sulphated) and bind water
What do synovial fibroblasts secrete?
Lipid mediators (PGE2)
Cytokines
Enzymes
Matrix materials
What makes bone?
Osteoblasts
What’s osteoclasts?
Activated by cytokines, they break down bone
Proteoglycans are lost rapidly in RA which leads to what?
Shock absorption impaired- loss of joint function= pain
Proteoglycans have an open structure which makes them what?
Highly accessible and thus sensitive to breakdown by several proteinases
In RA which is lost more slowly: proteoglycans or collagen
Collagen but loss is irreversible
Is native collagen susceptible to breakdown by all enzymes that can degrade collagen?
NO native collagen only susceptible to collagenases but once it’s damaged other enzymes can degrade it
What does MMP stand for?
Matrix metalloproteinase
Name the three MMPs that are collagenases?
MMP-1 -8 -13
What MMP is gelatinase A
MMP 2
Is matrix metalloproteinase active at neutral pH?
YES
What do matrix metalloproteinases contain and require
Zn2+
What inhibit matrix metalloproteinases?
Tissue inhibitors of metalloproteinases (TIMPs)
How is matrix metalloproteinase activated?
Activated by removal of propeptide and hence the cysteine motif- activated by serine proteases
On matrix metalloproteinases what is the c terminus important for?
Substrate specificity and regulation
How do matrix metalloproteinases inhibitors work?
The active site Zn2+ is targeted by hydroxamate series: E.g marimastat
Name two types of MMP inhibitors
Peptidomimetics
Non-peptide hydroxamates
Name a type of peptidomimetics MMP inhihitor
Marimastat
Name a type of non-peptide hydroxamate MMP inhihitor
Prinomastat
Which type of MMP inhibitor has better selectivity for collagenases?
Non-peptide hydroxamates e.g prinomastat
Name 4 classes of proteolytic enzymes
Matrix metalloproteinases
Serine proteinases
Cysteine proteinases
Aspartate proteinases
Name 3 other approaches to inhibiting Matrix metalloproteinases?
Tetracycline derivatives
Antibody based therapeutics
Endogenous inhibitors of MMPs
Name 4 matrix proteins that serine and cysteine proteinases break down
Elastin
Laminin
Chondroitin sulfate
Proteoglycans
Serine protease inhibitors are also called what?
SERPINS
What are SERPINS readily inactivated by?
Oxidation
Name three adverse effects of matrix metalloproteinases
Musculoskeletal syndrome
Lack specificity
Role in homeostatic connective tissue turnover
What’s the process of reactive oxygen and nitrogen species formation?
NADPH –> O2- –> H2O2 –> OH. + HOCl-
Then nitrogen species formed from NOS derived NO combining with oxygen species
What is reactive oxygen and nitrogen species essential for?
Host defence
What does RONS activate?
Activation of inflammatory gene transcription
-NFkB
The shared epitope carried by rheumatoid arthritis patients is what?
A 5aa sequence motif in the third allelic hypervariable region of the HLA-DRBeta chain
What is rheumatoid factor
The first antibody associated with rheumatoid disease
What does ACPA stand for
Anti-citrullinated protein antigen
What’s citrulline?
A post translational modification of arginine, it’s up regulated in joints
Are anti-citrulline protein antibodies highly specific for RA?
Yeh they are and they’re found up to 14yrs before onset of symptoms in RA
What does HAQ stand for
Health assessment questionnaire
What does the HAQDI score?
How difficult patients can carry out activities
