Renal Immunology Flashcards
Ischemic Acute kidney injury leads to what kind of acidosis?
metabolic acidosis
AKI causes ___.
Acute renal failure
What induces sterile renal inflammation?
Intrinsic DAMPs released by necrotic parenchymal kidney cells due to the ECM degradation
What is another name for DAMPs?
alarmins
What do alarmins represent?
Intracellular molecular structures such as HMGB1, Uric acid, HSP’s, S100 protein, Hyaluronans
What recognizes DAMPs?
TLR expressed on immune cells and they become activated and produce renal inflammation
What complement activation pathways have been linked to AKI?
All three paths
Why are kidneys uniquely susceptible to complement induced damage?
- Because the high filtration rate favors tissue deposition of immune complexes
What drives infiltration of neutrophils and monocytes in AKI?
C5a an C3a
What do neutrophils release in an AKI?
- Proteases which cause degradation of GBM
- Oxygen derived free radicals which cause cell damage
Monocytes differentiate into what type of macrophage and what do they release and infiltrate?
- Differneitate into M1 and infiltrate the glomeruli
- Release:
- ROS
- Cytokines/Chemokines
- Growth factors
- Eicosanoids
- NO
- All of these contribute to vascular injury and cell proliferation
In the early stage of AKI what mediates immune responses?
- Th17 and Th1 cells dominate in causing tissue injury
What macrophages are involved in AKI?
- M1 plays a key role in AKi
- M2 play a key role in tissue repair
In the late stage of AKI, what cell type dominates?
Th1
What induces Th17?
- IL1 IL6 and TGF-B prodducedby DC’s
Compare IL17 vs IL22
- 17 contributes to inflammation when its in greater ammounts than IL22
- IL22 controls homeostatsis when greater than IL 17
IL-17 indudces expression of CCL20 which leads to recruitement of what cells?
- Neutrophils
- Monocytes
- Th1 and Th17 cells
This recruitement leads to progression of immune mediated kidney damage
- Th1 secretes IFN-y inducing M1
Treg role in AKI?
- Prevent AKI progression and restrict inflammation and promote repair and regeneration
What is host vs graft disesase and the three categories?
- Caused by rejection of transplant by host’s immune system
- hyperacute rejection immediate and caused by an Ab
- acute rejection occurs days to weeks after and caused by T cells
- Chronic rejection seen months or years after transplant and is caused by vascular trauma, inflammatory products of T cells and Ab’s
What is graft vs host disease and the types?
- Reactions of donor immune cells to the host and it can be chronic or acute
Autograft?
- graft from the same person, move from one part of body to another
- skin graft, coronary bypass
Isograft?
- Graft between identical twins
Allografts?
- Graft betweeen nonidentical members of same species
Xenograft? Cons? How is it done?
- grafts exchanged btw species
- succeptible to rapid attack caused by Abs that will activate complement
- Human HLA genes are inserted into genes of donor animals and increase the chance of successful transplant
What is the outcome of a transplant determined by?
- Condition of allograft
- Donor host antigenic disparity
- Strength of anti donor response
- Applied immunosuppression
How does mechanical trauma and IRI impact the outcome of fa kidney transplant?
- A damaged graft will release DAMPs triggering
- clotting casacade generating fibrin
- fibrin aggregates to form clot
- fibrinopeptides increase vascular permeability and leukocyte accumulation
- kinin cascade produces bradykinin that cause vasodilatioin and sm mm contraction and increases vascular permeabiltiy
- Results in hyperacute rejection
What areas in the body are ABO matching not important?
- Cornea
- Heart valve
- Bone
- Tendon
- Tissues aren’t vascularized and have limited access for immune cells*
- ABO incompatibility also doesn’t impact stem cell transplant*
What Ab’s are present on Type A blood cells?
Anti B
What Abs are on group O?
Anti A and Anti B
What Ab’s are on those with AB blood?
none
How do you do blood typing?
- RBC’s + anti A or Anti B + complement system
- Celll lysis by MAC occurs
What is the microcytotoxicity test for preformed Abs?
- Recipient serum with Abs is added to the donors cells
- Add complement proteins and a dye that does NOT accumulate inside cells
- If the recipient has Ab’s for the donor classic complement path occurs and MAC forms
- Pores in the cell will allow the dye to accumulate inside the cell
- Mismatch because preexisting Abs are foun in the recipient
Microcytotoxicity for Class I HLA compatiblity?
- Take HLA-A3 Ag, donor cell WBC, and recipient WBC and add together
- Complement is added and classical activation occurs if a complex was formed
- Dye is aded
- If accumulated in both donor and recipient cells it means HLA-A3 is found in both and they match
- Test HLA-A7 repeat process to see if more match
Need multiple HLA matches not just one
Mixed lymphocyte response for Class II HLA?
- Isolate donor T cells and expose to radiation so they can’t proliferate, but can still sesrve as APC’s
- Add recipient T cell labelled thymidine
- If recipient T cell finds Ags on donor DC they will be activated and proliferate
- During cell division DAN is replicated and thymidine is incorporated into DNA
- more radioactivity=greater class II disparity btw donor and recipient
- replicated DNA with thymidine means donor and recipient don’t have class II compatiblity
What immune responses are seen with HVGD?
- CD4 CD8 respond against graft Ags
- systemic and local responses develop
- cytokines recruite and activate immmune cells
- Cytotocix reactions mediated by CD8 and NK cells and macrophages occurs
- allograft rejectionn occurs
What type of immunity mediates graft rejection?
Innate and adaptive
Why are adaptive immune responses against a graft much mroe vigorous and strong than response against a virus?
- High frequency of T cells that recognize that graft as non cells
- un immunized individual has <1/100,000 T cells that will respond with exposure to virus
- About 1:100 to 1:1,000 T cells respond to allogenic Ags
What is direct allorecognitioni?
- Recipient T cells arrive into the graft and recognize the MHC molecules on the donors APC’s in the graft
What is indirect allorecognition?
- Donor MHC molecules are taken up and processed and presented by the recipient APC’s for activation of the recipients T cells
In HVGD what do activated T cells release?
- IFN-y and TNF which will activate APCs further and endothelial cells and increase # leukocytes present
Effector mechanisms of graft rejection are from what cell and cytokines?
- Th2 releasing IL-4 and IL-5 humoral rejection mediated by ABs
- Th1 releasing IL-2 and iFN-y cell mediated rejection by CD8 t cells
What type of hypersensitivity mediates hyperacute HVGD?
II
What type of hypersensitivity mediates acute and chronic HVGD?
- Acute: IV
- Chronic: III and IV
What type of hypersensitivity mediates graft vs host disease?
IV
Mechanism of hyperacute rejection?
PReexisting abs and complemment
Acute rejection mechanism?
Primary activation of TH1 ccells and CTL’s
What is mechanism of chronic rejection?
- M2 macrophages and t cells
Why may a recipient have pre existing Abs?
- ABO incompatiblity
- sensitized to donor MHC by previous transplants
- blood transfusions
- pregnancy
What non immulological factors are important in chronic graft rejection?
- Ischemia reperfusion damage
- Failure of patient’s own kidney
- Nephrotoxicity from the drugs used for immunosuppression
chronic rejection doesn’t respond to immunosuppressive therapy
leading the response for chronic graft rejection are __ and __.
- CD4 and Macrophages
In graft vs host disease what antigens are the response generated towards?
- Minor H Ags bc HLA Ags are usually matched
What happens in acute GVHD?
- mediated by epithelial cell death in the skin liver and GI
- Rash, jaundice, diarrhea and GI hemorrhage
What happens in chronic GVHD?
- Mediated by fibrosis and atrophy of the affected organs
- may lead to complete dysfunction of the affected organ
How does GVHD occur?
- The donor APC’s will ltake up and present the recipients Ags in Class I and II MHC
- This causes activation of donor CD4 and 8 t cells