Inflammation Flashcards
What are the three phases of Acute Inflammation?
Fluid
Neutrophils
Macrophages
What two reasons does Acute Inflammation arise?
- infection- to eliminate a pathogen
2. tissue necrosis- to clear necrotic debris
Acute Inflammation is defined as
an immediate response with limited specificity (innate immunity)
What are the 5 mediators of Acute Inflammation?
- Mast cells
- Hageman Factor (Factor XII)
- Toll-like receptors
- Arachidonic acid metabolites
- Complement
Toll-like receptors are activated by
pathogen-associated molecular patterns (PAMPS)
What co-receptor recognizes lipopolysaccharide on macrophages on the outer membrane of Gram Negative bacteria?
CD14
TLR activation results in up regulation of
NF-kB
What always follows Necrosis
Acute Inflammation
What enzyme releases arachidonic acid from the phospholipid cell membrane?
Phospholipase A2
Arachidonic acid is acted upon by what 2 enzymes?
- Cyclooxyrgenase
2. 5-lipoxygenase
Cyclooxyrgenase produces
prostaglandins
5-lipoxygenase produces
leukotrienes
What are the 3 prostaglandins?
PGI2
PGD2
PGE2
Prostaglandins mediate
vasodilation at the level of the arteriole and increased vascular permeability at the post capillary venule
What prostaglandin mediates pain and fever?
PGE2
PGE2 mediates what?
pain and fever
What are the 4 leukotrienes?
- LTB4
- LTC4
- LTD4
- LTE4
LTB4 attracts and activates
neutrophils
What are the 4 Key mediators that attract and activate neutrophils?
- LTB4
- IL8
- C5a
- Bacterial products
What three things activate Mast Cells?
- Complement proteins C3a, and C5a
- tissue trauma
- cross-linking of cell surface IgE by antigen
What 3 ways do activation of Complement occur?
- Classical pathway
- Alternative pathway
- Mannose-binding lectin MBL pathway
Classical Pathway
C1 binds IgG or IgM tha is bound to antigen
Alternative Pathway
Microbial products directly activate complement
Mannose-binding lectin pathway
MBL binds to mannose on microorganisms and activates complement
All pathways result in production of
C3 convertase which mediates C3–C3a and C3b, which in turn produces C5 converts which mediates C5–C5a and C5b.
C5b complexes with C6-C9 form
the membrane attack complex MAC
C3a and C5a are
anaphylatoxins- trigger mast cell degranulation= histamine mediated vasodilation and increased vascular permiability
C5a is
chemotactic for neutrophils
C3b is
opsonin for phagocytosis
MAC lyses
microbes by creating a hole in the cell membrane
Hageman factor is
an inactive pro inflammatory protein produced in the liver
Hageman factor is activated
upon exposure to sub endothelial or tissue collagen=activates coagulation and fibrinolytic systems, complement, and Kinin system
What are the 2 mediators of pain?
- PGE2
2. Bradykinin
What are the 4 cardinal signs of inflammation?
- Redness and warmth
- Swelling
- Pain
- Fever
Redness and warmth due to
vasodilation, which results in increased blood flow, occurs via relaxation of arteriolar smooth muscle; key mediators are histamine, prostaglandins, and bradykinin
Swelling due to
leakage of fluid from post capillary venules into the interstitial space
What are the key mediators of swelling?
- Histamine-causes endothelial cell contraction
2. tissue damage-causes endothelial cell disruption
Pain is due to
bradykinin and PGE2 sensitize sensory nerve endings
Fever is due to
pyrogens cause macrophages to release IL-1 and TNF which increased cyclooxyrgenase activity in perivascular cells of the hypothalamus AND
increased PGE2 raises temperature set point
What are the 6 steps of neutrophil arrival and function?
- Margination
- Rolling
- Adhesion
- Transmigration and Chemotaxis
- Phagocytosis
- Destruction of phagocytosed material
What are the outcomes of macrophages?
- resolution and healing-anti inflammatory cytokines are produced
- Continued acute inflammation-marked by continued pus formation
- Abscess
- Chronic inflammation by presenting antigen to activate CD4+ helper T cells
What are the anti inflammatory cytokines produced by macrophages?
IL-10 and TGF-B
What cytokines is produced by macrophages to recruit additional neutrophils?
IL-8
Chronic inflammation is characterized by
the presence of lymphocytes and plasma cells in tissue
What are the 5 stimuli to chronic inflammation?
- persistent infection
- infection with viruses, mycobacteria, parasites, and fungi
- autoimmune disease
- foreign material
- some cancers
CD4+ T cells bind to
MHC class II
CD8+ T cells bind to
MHC class I
CD4+ T cells are
Helper T cells
CD8+ T cells are
Cytotoxic T cells
The job of CD4+ T cells are to
Help CD8+ T cells and Help B cells