Inflammation & Autoimmune Disorders Flashcards
Acute inflammation is characterized by presence of ____ and _____ in tissue
It arises in response to ______ or _____ _____ with the goal to eliminate pathogen or clear debris. Also important to note is that it is an immediate response with LIMITED specificity — which is a hallmark of innate immunity.
Edema; neutrophils
Infection; tissue necrosis
Innate immunity is mediated by several factors. ______ are present on cell of innate immune system including macrophages and dendritic cells, and recognize and are activated by PAMPs
TLRs
Pathogen-associated molecular patterns (PAMPs) are commonly shared by microbes. _____ is an example of a PAMP on the outer membrane of gram-negative bacteria that is recognized by CD14 on macrophages
LPS
Activation of a TLR upon recognition of a PAMP results in upregulation of ______, which activates immune response genes and leads to production of multiple immune mediators.
NF-kB
T/F: TLRs are only present on cells of innate immunity
False — they are also present on cells of adaptive immunity in which case they mediate chronic inflammation
______ _____ is an immune mediator released from the phospholipid cell membrane by phospholipase A2.
It is then acted on by _______ or ________
Arachidonic acid
Cyclooxygenase; 5-lipooxygenase
Arachidonic acid is an immune mediator released from the phospholipid cell membrane by phospholipase A2. It is then acted on by cyclooxygenase or 5-lipooxygenase.
Cyclooxygenase produces ________.
Of these, ___________ (3) mediate vasodilation and inceased vascular permeability. ______ also mediates fever and pain
Prostaglandins
PGI2, PGD2, PGE2; PGE2
[NOTE vasodilation occurs at the level of the ARTERIOLE and the increased vascular permeability occurs at the level of the POST-CAPILLARY VENULE]
Remember EEEEEEE2 controls feeeeeeeever
Arachidonic acid is an immune mediator released from the phospholipid cell membrane by phospholipase A2. It is then acted on by cyclooxygenase or 5-lipooxygenase.
5-lipoxygenase produces _______.
Of these, _____ attracts and activates neutrophils and __________ (3) mediate vasoconstriction, bronchospasm, and increased vascular permeability
Leukotrienes
LTB4; LTC4, LTD4, LTE4
[increased vascular permeability is d/t contraction of pericytes]
Mast cells are an inflammatory mediator widely distributed throughout connective tissue of the body. What are the 3 ways in which mast cells are activated?
Tissue trauma
Complement proteins C3a and C5a
Cross-linking of cell-surface IgE by antigen
Immediate response of mast cell activation involves release of preformed ____ granules which mediate vasodilation of arterioles and increased vascular permeability. The delayed response involves production of _____ _____ metabolites, particularly ______
Histamine; arachidonic acid; leukotrienes
Complement are proinflammatory serum proteins that enhance inflammation. They circulate as inactive precursors. What are the 3 ways in which complement activation can occur?
Classical pathway — C1 binds to IgG or IgM that is bound to antigen
Alternative pathway — Microbial products directly activate complement
Mannose-binding lectin pathway — MBL binds mannose on microorganisms and activates complement
The result of complement activation by any of the 3 pathways is generation of C3 convertase, C5 convertase, and formation of MAC. Key products generated by complement include C3a and C5a, C3b, and the MAC.
What is the specific function shared by C3a and C5a?
C3a and C5a trigger mast cell degranulation
The result of complement activation by any of the 3 pathways is generation of C3 convertase, C5 convertase, and formation of MAC. Key products generated by complement include C3a and C5a, C3b, and the MAC.
C3a and C5a trigger mast cell degranulation. What is the other function of C5a?
Chemotactic for neutrophils
The result of complement activation by any of the 3 pathways is generation of C3 convertase, C5 convertase, and formation of MAC. Key products generated by complement include C3a and C5a, C3b, and the MAC.
What is the specific function of C3b?
Opsonin for phagocytosis
[opsonins basically tag things for destruction]
The result of complement activation by any of the 3 pathways is generation of C3 convertase, C5 convertase, and formation of MAC. Key products generated by complement include C3a and C5a, C3b, and the MAC.
What is the specific function of the MAC?
Lyses microbes by creating holes in the cell membrane
[MAC is formed by C5b joined with C6-9]
Inactive proinflammatory protein produced in the liver; activated upon exposure to subendothelial or tissue collagen
Hageman factor
[plays an important role in DIC]
Hageman factor activates coagulation and fibrinolytic systems (role in DIC), complement, and kinin system. What is the role of the kinin system?
Cleaves HMWK to bradykinin, which mediates vasodilation, increased vascular permeability, and pain
The cardinal signs of inflammation include redness (rubor), warmth (calor), swelling (tumor), pain (dolor), and fever. What is the physiology behind redness and warmth (including key mediators)?
Due to vasodilation which results in increased blood flow via relaxation of arteriolar smooth muscle
Key mediators are histamine, prostaglandins, and bradykinin
The cardinal signs of inflammation include redness (rubor), warmth (calor), swelling (tumor), pain (dolor), and fever. What is the physiology behind swelling (including key mediators)?
Due to leakage of fluid from postcapillary venules into interstitial space
Key mediators are histamine and tissue damage
The cardinal signs of inflammation include redness (rubor), warmth (calor), swelling (tumor), pain (dolor), and fever. What is the physiology behind pain (including key mediators)?
Bradykinin and PGE2 sensitize sensory nerve endings
The cardinal signs of inflammation include redness (rubor), warmth (calor), swelling (tumor), pain (dolor), and fever. What is the physiology behind fever (including key mediators)?
Pyrogens cause macrophages to release IL-1 and TNF
Increase COX activity in perivascular cells of hypothalamus
Increased PGE2 raises temperature set point
Step one of neutrophil arrival and activation is ______ which is characterized by vasodilation which slows blood flow in postcapillary venules and cells move to periphery of flow
Margination
Step one of neutrophil arrival and activation is margination. Step two is rolling, which requires selectin upregulation on endothelial cells. What are the 2 important selectins?
P-selectin is released from Weibel-Palade bodies (in endothelial cells); mediated by histamine
E-selectin is induced by TNF and IL-1
[Remember Weibel-Palade bodies contain P-selectin and vWF]
Step one of neutrophil arrival and activation is margination. Step two is rolling, which requires selectin upregulation on endothelial cells. Selectins bind __________ on leukocytes, an interaction which then results in rolling of leukocytes along the vessel wall
Sialyl Lewis X
Step one of neutrophil arrival and activation is margination. Step two is rolling, which requires selectin upregulation on endothelial cells. Step three is adhesion, which is an interaction resulting in firm adhesion to the vessel wall. This requires cell adhesion molecule upregulation on the endothelium by ____ and ____. In addition, integrins are upregulated on leukocytes by ____ and ____
TNF; IL-1
C5a; LTB4
Leukocyte adhesion deficiency is an _____ ____ inherited defect of _______
Autosomal recessive; integrins (CD18 subunit)
3 key clinical features of Leukocyte Adhesion Deficiency
Delayed separation of umbilical cord
Increased circulating neutrophils
Recurrent bacterial infections that LACK pus formation
Step one of neutrophil arrival and activation is margination. Step two is rolling, which requires selectin upregulation on endothelial cells. Step three is adhesion via integrins and cell adhesion molecules. Step four is transmigration and chemotaxis. During step four, leukocytes transmigrate across the endothelium of postcapillary venules and move toward chemical attractants. What are the 4 key chemoattractants for neutrophils?
LTB4
C5a
IL-8
Bacterial products
Step one of neutrophil arrival and activation is margination. Step two is rolling, which requires selectin upregulation on endothelial cells. Step three is adhesion. Step four is transmigration and chemotaxis. Step five is phagocytosis which involves consumption of pathogens or necrotic tissue. This process is enhanced by opsonins ____ and _____. The way by which phagocytosis occurs is that pseudopods from the leukocytes extend to form phagosomes. The phagosomes are internalized and merged with lysosomes to form phagolysosomes
IgG; C3b
Protein trafficking defect characterized by impaired phagolysosome formation; clinical features include increased risk of pyogenic infection, neutropenia, giant granules in leukocytes, defective primary hemostasis, albinism, and peripheral neuropathy
Chediak-Higashi syndrome
[can be thought of as a microtubule defect]
Inheritance of Chediak Higashi syndrome
Autosomal recessive
Destruction of phagocytosed material occurs by one of two mechanisms: oxygen-dependent or oxygen-independent. The oxygen-dependent mechanism is most effective. What is this mechanism?
HOCl generated by oxidative burst in phagolysosomes destroys phagocytosed microbes
[generation of HOCl occurs by the following: O2 is converted to O2* by NADPH oxidase — this is the oxidative burst! O2* is then converted to H2O2 by SOD. H2O2 is then converted to HOCl by MPO]
Disease characterized by poor O2-dependent killing due to NADPH oxidase defect
Chronic granulomatous disease
Inheritance of chronic granulomatous disease
X-linked or autosomal recessive
Key type of bacteria that those with chronic granulomatous disease are at risk for
Catalase-positive organisms! Most bacteria naturally produce a little bit of H2O2, so we can still generate HOCl using that, so CGD pts don’t have a problem with those. Catalase destroys H2O2, so catalase-producing organisms.
Important catalase-positive organisms to be aware of include: **Pseudomonas cepacia** S. aureus S. marcescens Nocardia Aspergillus
Test used to screen for chronic granulomatous disease
Nitroblue tetrazolium test
Turns blue if NADPH oxidase can convert O2 to O2*. Remains colorless if NADPH oxidase is defective
[allows you to differentiate from MPO deficiency, which would have a negative NBT test]
_____ deficiency results in defective conversion of H2O2 to HOCl*. These pts are typically asymptomatic, but are considered at increased risk for ____ infections
MPO; candida
The 2 ways in which organisms are killed after phagocytosis are O2-dependent killing and O2-independent killing (less effective). What is the mechanism of O2-independent killing?
Occurs via enzymes present in leukocyte secondary granules (e.g., lysozyme and major basic protein)
Neutrophils undergo _____ and disappear within 24 hours after resolution of inflammatory stimulus
Apoptosis
What cell type predominates after neutrophils (i.e., peaks 2-3 days after inflammation begins)?
Macrophages
[derived from monocytes in the blood; arrive via margination, rolling, adhesion, and transmigration sequence identical to neutrophils. They then ingest via phagocytosis and destroy phagocytosed material using enzymes (lysozyme!) in the secondary granules]