Immunological Aspects of the renal system Flashcards

1
Q

what are some risk factors that can lead to AKI and CKD

A
  • Age
  • Race or ethnic group
  • genetic factors
  • Hypertension
  • DM
  • Metabolic syndrome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why is an ischemic injury critical in kidney disease

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are some causes of kidney hypoperfuusion and AKI

A
  • Intravascular volume depletion and hypotension
  • Decreased effective intravascular volume
  • Hepatorenal syndrome
  • Medications
  • Sepsis
  • Renal vascular disease

all lead to hypoxia leading to AKI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is Sterile Inflammation and DAMPS

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are some DAMPS and what do they activate

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are some Immune mediated mechanisms of AKI

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are Pro-inflammatory responses and the development of AKI via DC, Mo, and Tcells

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are some anti-inflammatory responses in response to AKI via DC, Mo, and Tcell

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Effects of a M1 vs a M2 macrophage

A

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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Role of Th72 cells in AKI

A

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 well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does Treg cells play a role in AKI

A

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 well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does Complement play a role in AKI

A

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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the Type II hypersensitivity in AKI terms

A

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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the Type III hypersensitivity in AKI terms

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

when do we use kidney transplantation and what is important for making it happen

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the 4 different drafts and what one do we use the most

A

Autografts: exchanged from the same individual

Isografts: grafts exchanged between identical twins

Allografts: exchanged between the same species but are not identical

Xenografts: graft between different species

  • normally susceptible to rapid attack
  • insertion of human genes does increase the success rate
17
Q

what are the 4 key concepts of Transplantation

A

1) the condition of the allograft
2) Donor host antigenic disparity
3) strength of host anti-donor response
4) immunosuppresive regime

18
Q

why is damage of the allograft so bad for the success rate of a transplant

A

will release DAMPs that will lead to a biochemical cascade

  • clotting cascade generates fibrin and fibrinopeptides
  • fibrinopeptides increase local vascular permeabillity to then allow for accumulation of neutrophils and monocytes
  • kinin cascade produces bradykinin which is a vasodilater also increasing vasodilation

leads all to hyperacute allograft rejection

19
Q

when matching a donor and recipient what do we look for in the Blood group antigens

A

the donor and recipiet must not have counteracting Ags present and Abs present

if not can lead to rejection!

if have A antigens then have Anti B Abs

O has no antigens but both anti A/B

AB has no Abs to antigens

20
Q

when do we not have to worry about matching blood group antigens during transplantation

A

during non vascularized tissue transplants

Corneal transplantation

Heart valve transplantation

Bone and tendon grafts

ABO is also not a contradiction to stem cell transplantation

21
Q

How do we test for pre-existing non ABO abs

A

called Microcytotoxicity Test for preformed ABs

  • take donor cells and add to recipient serum with Abs
  • complement is then added to make MAC if there is preformed Abs Dye will go into cells
  • if not then no preformed Abs
22
Q

what is the significance of the HLA system and why its important to match them between donor and recipient

A

Since all cells have antigens presenting on them that the Immune system identifies if they are foreign or not, it is important that they match between donor and recipient

2 class system: Class I (present on all cells) and Class II (present on APC cells)

  • critical that the Class I matches
  • has 6 HLA class I alleles (3 maternal and 3 paternal) (same for class 2)
23
Q

How do we test for class I HLA compatibility

A

Complement-dependant Serology

gather lympocytes and then HLA antisera from planned immunization of volunteers or from multiparous women

antisera contain Abs to HLA ags

they will bind on surface of lymphocytes
-create the classical complement cascade and then will caused lymphocyte lysis

Microcytototoxity test for Class I HLA

  • add Antibodies to whatever HLA antigen
  • then add complement to both and see if dye enters the cells
  • if both do then there is a match
  • if not they dont match
24
Q

Testing for class II HLA compatibillity

A

not as important as class I

Mixed lymphocyte response:
give radiation to donor cells so wont proliferate but serve as APCs
-add recipent cells with radioactive thymidine
-if cells proliferate then they dont match
-if cells radioactivity dont add DNA and no proliferation then good for transplant

25
Q

what are the 5 immune events during Allograft rejection

A

1) APCs trigger CD4 and CD8 T cells
2) both a local and systemic immune response
3) cytokines recruit and activate immune cells
4) Development of specific T cells, NK cells, or Mo mediated cytotoxicity
5) Allograft rejection

26
Q

what are the two types of immune responses in transplantation

A

Host vs graft disease (kidney)

Graft vs host disease (bone marrow)

27
Q

Host vs Graft responses and what are the two types of Allorecognition

A

host immune system attacks donor tissue via an adaptive immune response

  • much more vigorous and strong then normal response
  • second graft from same donor gets rejected faster
  • can be humoral rejection Th2 (IL-4,5,10)
  • can be cellular rejection Th1 (IL-2 IFN-y)

Direct Allorecognition: T cells recognize intact Allogeneic MHC molecules on the surface of donor APCs in the graft

Indirect allorecognition: alloantigens are recognized in the context of recipents MHC class II molecules after they have been processed and presented by recipient APCs

28
Q

What are the 3 types of rejections

A

Hyperacute: Onset is immediate, performed antibodies directed against the donor tissue, caused by accidental ABO blood type incompatibility which is rare or sensitized to the donor via transplants, multiple blood transfusions or pregnancy, type II hypersensitivity

Acute: weeks to months, T cell mediated immune response directed against the foreign MHC. inflammation and leukocyte infiltration of graft vessels results. most common type. Type of hypersensitivity IV

Chronic: months to years, T cell mediated process resulting from the foreign MHC looking like a self MHC carrying an antigen. An indirect response. results in intimal thickening and fibrosis of graft vessels as well as graft atrophy. Type IV hypersensitivity.
-does not respond to immunosuppressive therapy

29
Q

Graft vs host disease and 2 types

A

Reaction of grafted mature T cells in the marrow that allo-ags of the host

directed against minor H ags because the HLA are usually matched

recipient is usually immunocomprimised because immune system is unable to reject the allogenic cells in the graft
-occurs in transplants that are of the small bowel, lung or liver which contain a number of T cells

Acute GVHD: epithelial cell death in the skin, liver and GI
-clinically rash, jaundice, diarrhea, and GI hemorrhage

Chronic GVHD, Fibrosis and atrophy of affected organ

  • dysfunction of organ
  • produce small airways

Donor T cells attack the recipients tissue

  • Type IV hypersensitivity
  • Fas-FasL binding of CD8 T cells to target cell to kill
  • Perforin/granzyme release on target cell to kill