Immunological Aspects of the renal system Flashcards
what are some risk factors that can lead to AKI and CKD
- Age
- Race or ethnic group
- genetic factors
- Hypertension
- DM
- Metabolic syndrome
Why is an ischemic injury critical in kidney disease
since kidneys are the major filtering organ in the body they receive about 20% of the total cardiac output
the high renal oxygen demand is required due to large amount of ATP consumption of the necessary solute reabsorption
therefore an Ischemic acute kidney injury leading to metabolic acidosis and ATP depletion is one of the major causes of ARF
-abrupt decrease in kidney function
what are some causes of kidney hypoperfuusion and AKI
- Intravascular volume depletion and hypotension
- Decreased effective intravascular volume
- Hepatorenal syndrome
- Medications
- Sepsis
- Renal vascular disease
all lead to hypoxia leading to AKI
what is Sterile Inflammation and DAMPS
Sterile renal inflammation is induced by intrinsic Damage associated molecular patterns (DAMPs)
- released from dying parenchymal kidney cells
- generated during ECM degradation and remodeling
C reactive protein can bind DAMP to activate complemnt
Immune cells can recognize DAMPS via Toll like receptors to initiate an immune response
what are some DAMPS and what do they activate
Molecular patterns (alarmins) are endogenous intracellular molecular structures
-HMGB1 (nucleous protein) (recognized by RAGE) -Uric acid (recognized by NLRP3) -HSPs (exosomes) (recognized by scavenger receptor class A) -S100 protein (cytoplasm) -Hyaluronans in ECM
all these then activate NF-kB pathway leading to a release of inflammatory cytokines from dendritic cells
what are some Immune mediated mechanisms of AKI
activation of Dendritic cells, macrophages, and endothelial cells:
-Dendritic cells release IFN, CXCL2, IL-IB, and IL-12
- Macrophages release ROS, IL-1B, TNF, IL-6 and chemokines
- Endothelial cells release TNF, IL-6, chemokines and IFNa
leads to WBC recruitment: Neutrophils, Macrophages, lymphocytes, dendritic cell activation
-then leads to leukocyte activation, cytokine release, migration, tissue migration, released flow
what are Pro-inflammatory responses and the development of AKI via DC, Mo, and Tcells
DC: increase in Th1 and Th17 differentiation
-early stages of AKI immune responses mediated by Th17 cells dominate tissue injury
M0: will turn to M1 and increase TNF-a and IL-6
Tcell: increase CD4 Th1 response, increase IFN-y, IL-6 and decrease IL-4
-very prominate Th1 cells in late stage of AKI
what are some anti-inflammatory responses in response to AKI via DC, Mo, and Tcell
DC: nothing really
Mo: M2 play a key role in tissue repair and increase in arginase-1 and increase in IL-10 also increase clearance of early apototic cells
Tcells: decreases antigen specific T cell expansion
Effects of a M1 vs a M2 macrophage
M1: induced by PAMPs and DAMPs binding to TLR or PRR
- IFN-y are proinflammatory cytokines and promote differetiation of M1
- cytokines produced by M1 Mo perpetuate the acute phase of inflammation in kidney
- release IL-1, IL-12, IL-23 to increase inflammation
- ROS, NO, and lysosomal enzymes to cause killing
M2: induced by IL-4 and IL-13 produced by certain subsets of T cells
- important for tissue repair and renal fibrosis which are controlled by IL-10 and TGF-B
- release IL-10 and TGF-B to act as anti inflammatory effects
- proline, polyamines, and TGF-B to induce wound repair and fibrosis
- stimulation of pericyte accumulation and activation, myofibroblast differention, and production of ECM
Role of Th72 cells in AKI
accumulated Th17 cells secrete IL-17 that stimulates resident renal cells to produce inflammatory mediators like cytokines, chemokines and other mediators
IL-17 induces expression of chemokine CCL20 that leads to recruitment of neutrophils
Th17 facilitate infiltration of Monocytes, Th1 cells and Th17 cells directly by secretion of CCL20 and macrophage inflammatory protein -3 (MIP-3)
recruitment of other pro-inflammatory leukocyte subsets leads to progression of immune mediated kidney disease
How does Treg cells play a role in AKI
important for peripheral tolerance
will ihibit: Neutrophils, T and B lymphocytes via IL-10
activates tissue remodeling via TGF-B and increase tropic factors
How does Complement play a role in AKI
all three activation pathways are shown in KIdney diseases
The reason for the kidneys unique susceptabillity to complement induced damage is that filtration favors tissue deposition of immune complexes
- DAMPS lead to activation of complement that increases deposition of C3b and C5b and production of C3a and C5a (furthur activates complement and tissue resident cells, proinflammatory response)
- MAC C5b-9 leads to massive cell death and much collateral damage
- at the end of necrosis of kidney cells the Mo takes on M2 and control tissue repair and fibrosis
What is the Type II hypersensitivity in AKI terms
IgG or IgM
cell bound to antigen
- IgM or IgG antibody binds to cellular antigen leading to complement activation and cell lysis, this can happen because positvely charged Ags can be planted in the negatively charged glomerular basement membrane
- this leads to anti-glomerular basement membrane antibody mediated GN
what is the Type III hypersensitivity in AKI terms
IgG or IgM
soluble antigen
Antigen-antibody complexes deposited in tissues, complement activation leads to recruitment of inflammatory mediators
leads to post-streptocococcal glomerulonephritis, rheumatoid arthritis, and systematic lupus erythematosus
when do we use kidney transplantation and what is important for making it happen
is used for end stage renal disease
barrier to transplantation is the genetic incompatibility of donor to recipient
sucessful transplantation uses immunosuppressive drugs and also match the HLA to prevent rejection