Week 2 Flashcards
Importance of cytokines
- Local signaling of inflammation: Part of inflammatory process
- for communication and recruitment
- General reason: drive immune response; Any immune response that occurs is due to cytokines
cytokines and access to tissues
- certain cytokines can increase vascular permeability which can allow for infiltration of immune cells
- Certain cells (macrophages) are already in tissue but other cells (ex. Neutrophils) have to travel through the blood and require cytokines in order to get to the site of inflammation
Immune privileged site
- do not normally have immune cells but cytokines can give immune cells access to the tissue
- examples: CNS, because of brain blood barrier; Eye, has barrier around it; Testicles
Inflammatory cytokines
-secreted by
- macrophages
- IL1beta, TNF alpha, IL6, CXCL8, IL-12
IL-1 beta and TNF alpha
induces blood vessels to become more permeable enabling effector cells to enter the infected tissue
IL-6
induces fat and muscle cells to metabolize which creates heat and raises temperature in the infected tissue
CXCL8
- recruits neutrophils from the blood and guides them to infected tissue
- very strong chemotractant; for monocyte and nk cell recruitment
IL-12
- recruits and activates NK cells that in turn secrete cytokines that strengthen the macrophages response to infection
- helps t cells to differentiate to T1 cells
1 role of innate immune system
Indiscriminate attack of foreign invaders which creates inflammation at site of infection which activates adaptive immune system
4 primary aspects of inflammation
- Heat
- Pain
- Redness
- Swelling
How do we get inflammation?
- cytokines
- able to create inflammation by causing vasodilation of endothelial cells which causes blood to trickle out which causes redness and warmth; also causes gaps between the cells which allows for release of fluid which causes edema; Edema causes compression of local nerves which causes pain
Inflammasome function
-amplify innate immune response by increasing IL-1 beta
IL-1RA and IL-1B
IL-1RA competitively inhibits IL-1 beta
TNF-alpha causes vasodilation and fluid leakage
- homozygous mutation means more susceptible for septic shock
- Will cause systemic edema, and lead to shock
What is sepsis
clinical syndrome that is caused by dysregulated inflammatory response to infection; pathogen must be involved
How does sepsis occur?
- Usually gram neg bacteria
- Immune system would be responding to LPS (PAMP); when it kicks up out of hand it causes systemic vasodilation which allows for infection to spread
- Binds to TLR 4
Where in body are cells binding to LPS with TLR 4
- Liver or spleen because they have macrophages (white pulp) in tissue; the tissue has blood vessels running through it and if bacteria is in the blood then the macrophages are able to recognize bacteria LPS with TLR 4 and begin to secrete a lot of TNF alpha/ IL-1 beta
- Lots of secretion of TNF alpha causes systemic edema which can lead to shock
What happens in shock
- TNF alpha secreted inappropriately causes increased vasodilation, causes a drop in BP (hypotension), heart will try to compensate by increasing rate (tachycardia), increased heart rate will cause increased lactate which leads to acidosis, acidosis will lead to tachypnea
- There will be decrease in perfusion to tissue
- Can cause DIC
DIC
- disseminated intravascular coagulation
- Will form clots all over body
- This will continue to cause decrease in perfusion to tissue (no oxygen to organs)
A patient admitted to the hospital with a dangerously high temperature and allergic to general analgesics could be given which of the following to alleviate the fever?
IL-6, TNF alpha, and IL-1 beta are all pyrogenic and anti meds could help reduce fever
Is fever always bad?
- No; benefits of fever
- Adaptive cells work better at higher temp (immune cells)
- TNF alpha does less damage to own tissue at higher temp
- Bacteria and viruses replicate less (slower) at higher temp
A patient with a bleeding disorder underwent thorough testing to identify the nature of her disease and discovered she had low levels of factor 1; which of the following treatments would increase her ability to clot?
- IL 6 would be used in patient with decrease in factor 1 because it activates the acute phase proteins that help to activate coagulation
- One of acute phase proteins is fibrinogen-factor 1 in clotting cascade
- Acts on hepatocytes to induce them to make acute phase proteins (look at picture to left)
What do RLR’s detect, and where?
-viral RNA in the cytoplasm of host cells
RLR pathway
- viral replication in cytoplasm produces uncapped RNA with a 5’ triphosphate
- RLR binds to viral RNA inducing association with MAVS and dimerization
- Dimerization initiates signaling pathways that activate IRF3 and NFkB
- IRF3 causes synthesis and secretion of type I interferon and NFk causes synthesis and secretion of inflammatory cytokines
Type I interferons
- have autocrine and paracrine effects
- binding of type I interferons leads to IFN-alpha and beta creating a response that:
- induces resistance to viral replication in all cells
- increase expression of ligands for receptors on NK cells
- activate NK cells to kill virus infected cells
Does interferon only help infected cell
- No; sends signals out to neighboring cells alerting them that there is virus in the area so that they can start to make proteins to protect themselves
What happens to NK cells when stimulated by interferon alpha and beta?
-drives the differentiation of NK cells into cytotoxic effector cells, which will kill virus-infected cells by inducing them to undergo apoptosis
Relationship between NK cells and macrophages
- macrophage activated by viral infection secretes inflammatory cytokines that recruit and stimulate more NK cells
- NK cell and macrophage form a conjugate pair with a synapse in which IL-12 and IL-15 activate the NK cell
- NK cells proliferate and differentiate into effector NK cells, causing them to secrete interferon gamma
- interferon gamma binds to macrophage and activates them to increase phagocytosis and secretion of inflammatory cytokines
SXS of SIRS
- fever/hpothermia
- elevated pulse
- tachypnea
- leukocytosis (WBC > 12,000) or leukopenia (WBC<4,000)
SIRS
- Systemic inflammatory response syndrome
- Inappropriate immune response of inability of the immune system to keep up with a unique pathogen
Causes of SIRS
○ Trauma: external force on body that causes injury; including burn
○ Infection: but can still have infection and not have SIRS
○ Pancreatitis not due to viral infection
-Bacteremia
Difference between SIRS , sepsis, and septic shock
- Sepsis: two sxs of SIRS sxs plus suspected infection
- Severe sepsis: sepsis + lactate above 2 or organ dysfunction
- Septic shock: severe sepsis + hypoperfusion despite adequate resuscitation or lactace above 4
Infection with signs of inflammation
○ Leukocytosis (WBC>12000)
○ Leukopenia (WBC<4000)
○ Normal WBC with 10% immature forms
○ Plamsa C-reactive protein w/ upwards of 2 standard deviations above the normal value
○ Plasma procalcitonin w/ upwards of 2 standard deviations above the normal value
○ Hypotension
Pathogenic sequence of events with septic shock
-infectious source causes inflammatory response–leads to coagulation response & cardiomyopathy, vasodilation, and increased vascular permeability which leads to hypotension and shock–coagulation response and shock leads to tissue hypoperfusion–causes cell death which leads to organ failure
Gram negative pleiomorphic rod with safety pin appearance
Gram negative organism Yersinia pestis (bubonic plague) which can develop into plague sepsis
Forms of plague in humans:
- Bubonic plague
- Septicemic plague
- Pneumonic plague:
Bubonic plague
- looks like incarcerated strangulated inguinal hernia, with severe pain, and fever.
- found in fleas on rodents
- Cats will eat mice, flea will jump onto cat, and then from cat spreads to human
- Found in Cali, four corners area,
Pneumonic plague
incredibly contagious, will probably die in 12 hours and everyone in room that you were in when started coughing is probably infected and will most likely die
Treatment of DIC
- treat underlying precipitating disorder: vol resuscitation, antibiotics, external cooling
- platelet transfusion for thrombocytopenia
- plasma for prolonged PT, PTT, or low fibrinogen
- fibrinogen concentrate for persistent low fibrinogen
- Vit K for prolonged PT
- tranexamic acid for trauma related DIC
What flu vaccine can you give to pregnant patient?
-trivalent inactivated influenza vaccine
what flu vaccine is contraindicated in pregnant patients?
-live attenuated influenza vaccine
what is major influenza viral PAMP?
cytoplasmic RNA
How does genetic material of influenza induce innate immune system?
- can be detected by the internal cell receptors (TLRs) that will trigger the production of cytokines
- RIG-1 and the inflammasome components and NOD-like receptor protein 3 induce that innate immune response which helps with production of interferons and IL-1 and other cytokines
- The innate immune response leads to proinflammatory cytokines signaling the induction of the adaptive immune response
resident alveolar cells contribute to the initiation of the adaptive immune response and T-cell activation in this infection
Conventional dendritic cells
Conventional dendritic cells
○ professional antigen presenting cells and resident in almost all tissues of the body
○ live in the lung tissue
-respond to various antigen and are professional antigen presenting cells that phagocytize it and carry it to the regional lymph nodes
-chemoattractants lead them back to the lymph node and they’re able to present the antigen in the context of MHC2 T-cells which have T-cell receptors
What does T-cell receptor resemble
-Fab portion of antibody
Diversity of T cell receptor
-germline DNA goes through recombination which rearranges the DNA–DNA is then transcribed, spliced, and translated creating a t-cell receptor protein–
T cell receptor
- has alpha chain (chromosome 14) and beta chain (chromosome 7) on variable region
- contains a constant region, transmembrane region, and cytoplasmic tail
- connected to a CD3 complex
CD3 complex
- made of
- function
- two epsilon polypeptide chains, a dimer of zeta polypeptide chains, 1 gamma, and 1 delta + TCR
- signal transduction once ligand binds to TCR
second class of T cells
alpha and beta chains are replaced with gamma and delta chains
diversity of TCR vs BCR before antigen encounter
-T-cells have more diversity
Are MHC’s identitical in one patient to another?
- what do they present? why?
- types?
- how many AA?
- No, there is a huge amount of variability with MHC
- they present different peptides and the presenting of different peptides leads to more effective immune responses than others
- two types of MHC molecule for recognizing intra- and extracellular antigens
- MHC I recognizes 8-10 AA
- MHC II recognizes 13-25 AA