Pathology of Kidney Allograft Dysfunction. B. Ivanyi, MD Department of Pathology, University of Szeged, Szeged, Hungary

Transcription

1 Pathology of Kidney Allograft Dysfunction B. Ivanyi, MD Department of Pathology, University of Szeged, Szeged, Hungary

2 The gold standard for exploration of the cause of an allograft dysfunction is to perform a renal allograft biopsy (Bx)

3 Evaluation of biopsies for cause in our department At least two cores Light microscopic stainings on serial sections (H&E, PAS, trichrome, methenamine silver) Immunofluorescence on frozen sections To detect rejection: C4d, HLA-DR To detect immune deposits: IgG, IgA, IgM, C3

4 Evaluation of biopsies for cause in our department Electron microscopy optional Fixation and embedding of samples in each case Examination of glomeruli if - LM of glomeruli is abnormal - IF reveals positivity - the patient has glomerular symptoms Examination of peritubular capillary (PTC) basement membrane if chronic rejection is suspected

5 Objective To review the pathology and diff. diagnosis of - rejection - CNI toxicity - post-transplantation glomerulonephritis - polyomavirus nephropathy

6 Acute T-cell-mediated rejection (TMR) Inflammatory response against HLA class II antigens expressed on endothelial cells tubular cells interstitial dendritic cells mesangial cells

7 Acute TMR Inflammatory response against HLA class II antigens expressed on endothelial cells tubular cells interstitial dendritic cells mesangial cells Effector mechanisms CD8 + CTL-mediated cytotoxicity +++ Delayed type hypersensitivity + Antibody-dependent cytotoxicity +

8 Manifestations Interstitium Tubules Tubulointerstitial rejection + Arteries Vascular rejection + Glomeruli Transplant glomerulitis

9 Tubulointerstitial rejection Interstitial oedema, lymphocytic infiltrates, and tubulitis

10 Tubulointerstitial rejection Infiltrates: predominance of CD8+ lymphocytes IF: tubular HLA-DR expression CD8+

11 Tubulitis on EM Intratubular CTLs injure tubular epithelial cells CTL CTL Apo CTL CTL Apo CTL

12 Subsiding tubulointerstitial rejection Nodular infiltrates (Tregs, CD4 +, CD8 +, CD68 + ) around newly formed lymphatics; scanty tubulitis; oedema Ø

13 Diff. dg. of tubulointerstitial rejection Acute pyelonephritis - neutrophils in infiltrates, neutrophilic casts Polyomavirus NP - nuclear inclusion bodies Drug-induced TIN - faint tubular HLA-DR staining PTLD - predominance of B-lymphocytes

14 Diff. dg. of tubulointerstitial rejection acute pyelonephritis

15 Vascular rejection Infiltration of the intima by lymphocytes + monocytes Involves the large arteries more frequently than the interlobular arteries

16 Differential diagnosis Intimal arteritis is pathognomic for acute TMR

17 Transplant glomerulitis Lymphocytes + monocytes in capillary loops Isolated glomerulitis: in 10% of cases with acute TMR

18 Differential diagnosis Recurrent or de novo proliferative GN (rejection: no immune deposits by IF)

19 Clinical correlation of acute TMR Most common cause of a graft dysfunction in the first 3 months after Tx Sudden asymptomatic rise in the serum creatinine level Bx confirms the diagnosis

20 Outcome Tubulointerstitial rejection responds well to pulse steroids Vascular rejection can be reversed with antilymphocyte antibodies If not: fibrous obliteration of arteries graft loss

21 Acute alloantibody-mediated rejection (ABMR) Donor-specific HLA class I or II antibodies Complement-mediated cytotoxic injury to the endothelial cells

22 Acute ABMR Donor-specific HLA class I or II antibodies Complement 4d degradation product binds to PTCs This stable molecule is detected by IF Complement-mediated cytotoxic injury to the endothelial cells

23 Evaluation of C4d in PTCs Immunofluorescence on frozen sections is more sensitive than immunohistochemistry on paraffin sections

24 Diagnostic criteria: serologic demonstration of DSAs, diffuse C4d+ along PTCs; evidence of tissue injury Evidence of tissue injury 1) ATN-like, minimal inflamm. 2) Peritubular capillaritis and/or thromboses 3) Transmural arteritis and/or arterial fibrinoid necrosis Racusen et al. AJT 3:1-7, 2003

25 EM Cytotoxic injury to PTC endothelial cells manifests in lysis

26 Differential diagnosis TMA secondary to CNI toxicity Recurrent HUS CMV or parvovirus B19 infection Anti-cardiolipin sy

27 Differential diagnosis TMA secondary to CNI toxicity Recurrent HUS CMV or parvovirus B19 infection Anti-cardiolipin sy Clue None of these displays C4d positivity along the PTCs

28 Clinical correlation Infrequent (2-8%) Most common in the first few weeks after Tx; oligoanuria develops within days Therapeutic efforts may reverse the rejection process Poor prognosis

29 Chronic ABMR

30 Diagnostic triad 1) Serologic demonstration of DSAs 2) Diffuse C4d+ in PTCs

31 Diagnostic triad 1) Serologic demonstration of DSAs 2) Diffuse C4d+ in PTCs 3) Histologic evidence of action of these antibodies, leading to chronic tissue injury: interstitial fibrosis and tubular atrophy and/or transplant arteriopathy and/or transplant glomerulopathy and/or transplant capillaropathy (PTC basement membrane lamination) Solez et al. AJT 7:1-9, 2006

32 Tx arteriopathy: new-onset intimal fibrosis Absence of elastosis

33 Consequence Chronic progressive ischemic injury to the graft

34 Tx glomerulopathy: double-contoured loops

35 EM: newly formed basement membrane layer(s) along the entire capillary circumference Ivanyi et al. Modern Pathol 14:1200, 2001

36 Consequences Proteinuria Focal glomerular obsolescence

37 Diff. dg.: recurrent or de novo MPGN Clue: no immunocomplexes on IF

38 Tx capillaropathy 5 or more BM layers

39 Consequence A progressive decrease in the number of PTCs

40 Ocurrence of lesions Transplant glomerulopathy most frequent Transplant capillaropathy Transplant arteriopathy less frequent

41 The cumulative occurrence of Tx glomerulopathy and Tx capillaropathy amounts to 90% The evaluation of the entire capillary bed provides a sensitive tool with which to recognize antibody-mediated tissue injury Wavamuno et al. AJT 7:2757, 2007

42 C4d-staining in chronic ABMR C4d is an insensitive marker or ABMR: less than half of the cases are negative! Sis et al. AJT 9:2312, 2009 Einecke et al. AJT 9:2520, 2009

43 Phenotypes of chronic ABMR Serology (Luminex technology), endothelial transcripts, and histopathology reveal C4d+ and C4d- chronic ABMR Taylor et al. Human Immunol 70: 563, 2010 Sis, Halloran. Curr Opin Organ Transplant 15: 42, 2010

44 Clinical correlation of chronic ABMR The most frequent cause of graft loss after 1 year Insidious, progressive decline in the GFR, frequently accompanied by proteinuria (often in the nephrotic range) and hypertension

45 Calcineurin inhibitor toxicity Cyclosporin and tacrolimus can cause acute or chronic nephrotoxicity; the lesions are identical Acute Toxic tubulopathy Vascular toxicity -Acute arteriolopathy -TMA Chronic Hyaline arteriolopathy Liptak P, Ivanyi B. Nature Clin Pract Nephrol 2:398, 2006

46 Toxic tubulopathy. Isometric vacuolization in the straight proximal tubules; interstitial edema is minimal or absent

47 The features of this tubulopathy cannot be distinguished from those of radiocontrast nephrotoxicity or osmotic nephrosis, Differential diagnosis conditions to be considered while making the diagnosis

48 Ischemia induces non-isometric vacuolization in tubules

49 Acute arteriolopathy: SMC injury; replacement of damaged myocytes by rounded plasma protein insudates

50 Clinical correlation Acute dysfunction The serum drug level is usually elevated Toxic tubulopathy is reversible Acute arteriolopathy may be irreversible

51 CsA-induced TMA. Fibrin thrombi in glomerular capillary loops Liptak P, Ivanyi B. Nat Clin Pract Nephrol 2: , 2006

52 Differential diagnosis Cannot be differentiated from other forms of TMA by morphology alone Pronounced arterial changes are not typical of CNI-induced TMA Acute humoral rejection (C4d+) Recurrent HUS

53 Clinical correlation Rare Resembles the HUS If the lesions are associated with extensive thrombosis, graft loss develops

54 Chronic toxicity: hyaline arteriolopathy The damaged SMCs are replaced by beaded hyaline deposits that bulge into the adventitia The insudates are positive for IgM and C3

55 Hyaline material (H) is present at sites where media SMCs have dropped out previously. E - swollen endothelial cells, A - apoptotic SMCs.

56 Hyaline arteriolopathy is associated with striped IF/TA

57 Clinical correlation Chronic toxicity occurs several months after Tx; the incidence increases with time A slow, insidious rise in the serum creatinine level The kidney damage is irreversible

58 Differential diagnosis 1) Hyalinosis in ageing, and hypertension Mainly subendothelial and rarely extends into the adventitia Necrosis of the SMCs is not observed Result of the zero Bx is of importance

59 Differential diagnosis 1) Hyalinosis in ageing, and hypertension 2) Diabetic nephropathy 4 changes should be observed simultaneously LM: arteriolar hyalinosis mesangial matrix expansion EM: diffuse thickening of the GBM IF: pseudolinear IgG staining along the glomerular, tubular and Bowman s capsule basement membranes Bhalla et al. Transplantation 75:66, 2003

60 Post-transplantation transplantation glomerulonephritis Exact prevalence of either recurrent or de novo GN is unknown because considerable number of recipients never undergo allograft biopsy

61 Post-transplantation transplantation glomerulonephritis Exact prevalence of either recurrent or de novo GN is unknown because considerable number of recipients never undergo allograft biopsy The diagnosis requires - the routine application of IgG, IgA, IgM, C3, immunostainings - EM to locate the deposits

62 Our series : 618 dysfunctional biopsies were evaluated with LM + IF + EM Transplant glomerulopathy ,3% Post-Tx GN % Systemic disease affecting the glomeruli 8-1.1%

63 Literature analysis White people throughout in Europe develop post-tx GN relatively infrequently indicating that ethnic and geographic differences have an impact on the prevalence Post-Tx GN is the third most important cause of allograft loss at 10 ys after Tx Ivanyi B. Nature Clin Pract Nephrol 4:446, 2008

64 Literature analysis Membranous NP is the most common de novo disease; FSGS, IgAN, and MPGN recur frequently Recurrent or de novo GN often coexists with acute and/or chronic rejection and/or chronic CNI-toxicity, and contribute together to allograft loss Ivanyi B. Nature Clin Pract Nephrol 4:446, 2008

65 Predictors of post-transplantation transplantation GN Male gender, non-white ethnicity, younger age, and biopsy-proven GN in the native kidney Chailimpamontree et al. JASN 20:843, 2009

66 Polyomavirus nephropathy The BK polyomavirus exhibits tropism for the renal tubular epithelium, where it establishes latent infection Vigorous immunosuppression can lead to reactivation of the infection and the development of PVN The definitive diagnosis requires 2 biopsy scores including medulla Drachenberg et al. Hum Pathol 36:1245, 2005

67 Viral replication results in cytopathic changes (nuclear enlargement, inclusion body, tubular cell injury)

68 Marked replication lysis of tubular cells, denudation of TBMs and interstitial inflammation

69 Dg.: immunostaining with SV40 large T-cell antigen

70 EM: virions are 40 nm in diameter, and are arranged in a paracrystalloid structure

71 Differential diagnosis Other viral infections (adenovirus: nm; CMV: nm) Acute TMR (lack of nuclear inclusion bodies, intense tubular HLA-DR expression) Chronic rejection (lack of nuclear inclusion bodies, negative confirmatory tests) Liptak et al. Nature Clin Pract Nephrol 2:631, 2006

72 Histologic patterns and clinical stages of PVN Pattern A Viral replication No tubular cell lysis No denudation of TBMs Early stage No dysfunction Urinary decoy cells Favorable prognosis Hirsch et al. Transplantation 79:1277, 2005

73 Histologic patterns and clinical stages of PVN Pattern A Viral replication No tubular cell lysis No denudation of TBMs Pattern B Viral replication Marked tubular cell lysis Denudation of TBMs Early stage No dysfunction Urinary decoy cells Favorable prognosis Fully developed stage A gradually decreasing renal function Graft loss can exceed 50% Hirsch et al. Transplantation 79:1277, 2005

74 Histologic patterns and clinical stages of PVN Pattern A Viral replication No tubular cell lysis No denudation of TBMs Pattern B Viral replication Marked tubular cell lysis Denudation of TBMs Pattern C Viral replication IF/TA =ci3 and ct3 Early stage No dysfunction Urinary decoy cells Favorable prognosis Fully developed stage A gradually decreasing renal function Graft loss can exceed 50% Late/sclerosing stage A severe dysfunction Graft loss is likely Hirsch et al. Transplantation 79:1277, 2005

75 Summary The application of light microscopic stainings on serial sections an expanded IF panel (C4d,( HLA-DR, IgG, IgA, IgM, C3 tissue sampling for optional EM comparison with a time-zero biopsy DR, IgG, IgA, IgM, C3) enables the pathologist to achieve etiologic diagnoses

76 Biopsy features of acute T-cell-mediated rejection include a) interstitial inflammation (predominance of CD8 lymphocytes) b) tubulitis c) + lymphocytic arteritis

77 The current diagnostic criteria of chronic antibodymediated rejection include a)serologic demonstration of circulating DSAs b) complement 4d-positivity in peritubular capillaries c) morphologic evidence of chronic tissue injury, such as interstitial fibrosis/tubular atrophy and/or arterial intimal fibrosis and/or double contoured glomerular capillary loops and/or peritubular capillary basement membrane lamination

78 Clinical correlation of chronic rejection a) Major cause of graft loss after 1 years b) Insidious, progressive decline in the GFR c) Frequently accompanied by proteinuria and hypertension

79 The most frequent causes of kidney allograft loss at 10 years are a) death with a functioning graft b) chronic antibody-mediated rejection c) chronic calcineurin inhibitor toxicity d) post-transplantation glomerulonephritis

80 Features of chronic calcineurin inhibitor toxicity include a) striped fibrosis and tubular atrophy b) peripheral nodular hyaline deposits in arterioles (hyaline arteriolopathy)