We studied the clinical, histologic, and molecular features distinguishing DSA‐negative from DSA‐positive molecularly defined antibody‐mediated rejection (mABMR). We analyzed mABMR biopsies with ...available DSA assessments from the INTERCOMEX study: 148 DSA‐negative versus 248 DSA‐positive, compared with 864 no rejection (excluding TCMR and Mixed). DSA‐positivity varied with mABMR stage: early‐stage (EABMR) 56%; fully developed (FABMR) 70%; and late‐stage (LABMR) 58%. DSA‐negative patients with mABMR were usually sensitized, 60% being HLA antibody‐positive. Compared with DSA‐positive mABMR, DSA‐negative mABMR was more often C4d‐negative; earlier by 1.5 years (average 2.4 vs. 3.9 years); and had lower ABMR activity and earlier stage in molecular and histology features. However, the top ABMR‐associated transcripts were identical in DSA‐negative versus DSA‐positive mABMR, for example, NK‐associated (e.g., KLRD1 and GZMB) and IFNG‐inducible (e.g., PLA1A). Genome‐wide class comparison between DSA‐negative and DSA‐positive mABMR showed no significant differences in transcript expression except those related to lower intensity and earlier time of DSA‐negative ABMR. Three‐year graft loss in DSA‐negative mABMR was the same as DSA‐positive mABMR, even after adjusting for ABMR stage. Thus, compared with DSA‐positive mABMR, DSA‐negative mABMR is on average earlier, less active, and more often C4d‐negative but has similar graft loss, and genome‐wide analysis suggests that it involves the same mechanisms.
Summary Sentence
In 398 kidney transplant biopsies with molecular antibody‐mediated rejection, the 150 DSA‐negative cases are earlier, less intense, and mostly C4d‐negative, but use identical molecular mechanisms and have the same risk of graft loss as the 248 DSA‐positive cases.
In a population of kidney transplant indication biopsies with a molecular diagnosis of antibody‐mediated rejection, those without compared to those with donor‐specific antibody typically occur earlier, are less active, and are more often C4d‐negative but have similar graft loss risk and, according to genome‐wide analyses, involve the same mechanisms.
Summary
Polyomavirus associated nephropathy (PyVAN) continues to be a burden in renal transplantation leading to allograft insufficiency or graft failure. A presumptive diagnosis of PyVAN is made ...based on the presence of BK polyomavirus in patients’ plasma; however, kidney biopsy remains the gold standard to establish a definitive diagnosis. The Banff Working Group on PyVAN proposed a novel classification of definitive PyVAN based on polyomavirus replication/load level and the extent of interstitial fibrosis. The aim of our study was to test the newly defined classes of PyVAN using independent cohorts of 124 kidney transplant patients with PyVAN with respect to the initial presentation and outcome, and to compare our analysis to that previously reported. Detailed analysis of our cohort revealed that the proposed classification of PyVAN did not stratify or identify patients at increased risk of allograft failure. Specifically, while class 3 was associated with the worst prognosis, there was no significant difference between the outcomes in classes 1 and 2. We also found that the timing post‐transplantation and inflammation in areas of interstitial fibrosis and tubular atrophy might be additional factors contributing to an unfavorable allograft outcome in patients with PyVAN.
Our validation study of Banff classification of definitive polyomavirus‐associated nephropathy (PyVAN) failed to confirm its predictive value. The timing post‐transplantation and inflammation in areas of interstitial fibrosis and tubular atrophy might be additional factors contributing to an unfavorable allograft outcome in patients with PyVAN.
Background/Aims: WNT4 protein is important for kidney development. Its expression was found to be altered in experimental models of chronic kidney disease (CKD). However, the expression of the WNT4 ...gene has yet not been studied in human renal biopsy samples from patients with broad spectrum of glomerular disease and at different stages of CKD. Thus, the aim of the study was to assess the WNT4 gene expression in renal biopsies of 98 patients using the real-time PCR technique. Materials: In order to assess the relative amounts of mRNA, in samples of patients with manifestation of different renal diseases and separately at different stages of CKD, by QPCR, total RNA was isolated from human kidney tissues collected during renal biopsies. Results of blood and urine samples assessment were used to calculate the correlations of biochemical parameters with WNT4 gene expression in both studied groups. Results: After pathomorphological evaluation, 49 patients were selected as presenting the most common cases in the studied group. Among the patients who developed focal segmental glomerulosclerosis (FSGS; n = 13), IgA nephropathy (IgAN; n = 10), IgAN with morphological presentation of focal segmental glomerulosclerosis (IgAN/FSGS; n = 8), membranous nephropathy (MN; n = 12), and lupus nephritis (LN; n = 6) were included in the analysis. We found that the level of WNT4 mRNA was higher in kidney specimens obtained from patients with MN as compared to those diagnosed with LN or IgAN. A correlation between WNT4 gene expression and serum albumin and cholesterol levels was observed in patients with FSGS, while WNT4 mRNA levels correlated with plasma sodium in patients diagnosed with LN. After consideration of 98 patients, based on the KDIGO classification of CKD, 20 patients were classified as CKD1 stage, 23 as stage 2, 13 as stage 3a, 11 as stage 3b, 13 as stage 4, and 18 as stage 5. WNT4 gene expression was lower in the CKD patients in stage 2 as compared to CKD 3a. Correlations of WNT4 mRNA level at different stages of CKD with indices of kidney function and lipid metabolism such as serum levels of HDL and LDL cholesterol, TG, urea, creatinine, sodium, and potassium were also found. Conclusions: Our results suggest that altered WNT4 gene expression in patients with different types of glomerular diseases and patients at different stages of CKD may play a role in kidney tissue disorganization as well as disease development and progression.
The Oxford Classification of IgA nephropathy does not account for glomerular crescents. However, studies that reported no independent predictive role of crescents on renal outcomes excluded ...individuals with severe renal insufficiency. In a large IgA nephropathy cohort pooled from four retrospective studies, we addressed crescents as a predictor of renal outcomes and determined whether the fraction of crescent-containing glomeruli associates with survival from either a ≥50% decline in eGFR or ESRD (combined event) adjusting for covariates used in the original Oxford study. The 3096 subjects studied had an initial mean±SD eGFR of 78±29 ml/min per 1.73 m
and median (interquartile range) proteinuria of 1.2 (0.7-2.3) g/d, and 36% of subjects had cellular or fibrocellular crescents. Overall, crescents predicted a higher risk of a combined event, although this remained significant only in patients not receiving immunosuppression. Having crescents in at least one sixth or one fourth of glomeruli associated with a hazard ratio (95% confidence interval) for a combined event of 1.63 (1.10 to 2.43) or 2.29 (1.35 to 3.91), respectively, in all individuals. Furthermore, having crescents in at least one fourth of glomeruli independently associated with a combined event in patients receiving and not receiving immunosuppression. We propose adding the following crescent scores to the Oxford Classification: C0 (no crescents); C1 (crescents in less than one fourth of glomeruli), identifying patients at increased risk of poor outcome without immunosuppression; and C2 (crescents in one fourth or more of glomeruli), identifying patients at even greater risk of progression, even with immunosuppression.
The Banff Classification of Allograft Pathology is an international consensus classification for the reporting of biopsies from solid organ transplants. Since its initial conception in 1991 for renal ...transplants, it has undergone review every 2 years, with attendant updated publications. The rapid expansion of knowledge in the field has led to numerous revisions of the classification. The resultant dispersal of relevant content makes it difficult for novices and experienced pathologists to faithfully apply the classification in routine diagnostic work and in clinical trials. This review shall provide a complete and simple illustrated reference guide of the Banff Classification of Kidney Allograft Pathology based on all publications including the 2017 update. It is intended as a concise desktop reference for pathologists and clinicians, providing definitions, Banff Lesion Scores and Banff Diagnostic Categories. An online website reference guide hosted by the Banff Foundation for Allograft Pathology (www.banfffoundation.org) is being developed, which will be updated with future refinement of the Banff Classification from 2019 onward.
Discrepancy analysis comparing two diagnostic platforms offers potential insights into both without assuming either is always correct. Having optimized the Molecular Microscope Diagnostic System ...(MMDx) in renal transplant biopsies, we studied discrepancies within MMDx (reports and sign‐out comments) and between MMDx and histology. Interpathologist discrepancies have been documented previously and were not assessed. Discrepancy cases were classified as “clear” (eg, antibody‐mediated rejection ABMR vs T cell–mediated rejection TCMR), “boundary” (eg, ABMR vs possible ABMR), or “mixed” (eg, Mixed vs ABMR). MMDx report scores showed 99% correlations; sign‐out interpretations showed 7% variation between observers, all located around boundaries. Histology disagreed with MMDx in 37% of biopsies, including 315 clear discrepancies, all with implications for therapy. Discrepancies were distributed widely in all histology diagnoses but increased in some scenarios; for example, histology TCMR contained 14% MMDx ABMR and 20% MMDx no rejection. MMDx usually gave unambiguous diagnoses in cases with ambiguous histology, for example, borderline and transplant glomerulopathy. Histology lesions or features associated with more frequent discrepancies (eg, tubulitis, arteritis, and polyomavirus nephropathy) were not associated with increased MMDx uncertainty, indicating that MMDx can clarify biopsies with histologic ambiguity. The patterns of histology‐MMDx discrepancies highlight specific histology diagnoses in which MMDx assessment should be considered for guiding therapy.
In renal transplant biopsies for which standard‐of‐care histology results in an ambiguous or challenging diagnoses, molecular diagnostic system can provide unambiguous diagnoses in scenarios that are problematic by conventional criteria.
Background
Chemokines (chemotactic cytokines) are small proteins which are engaged in many pathophysiological processes, including inflammation and homeostasis. In recent years, application of ...chemokines in transplant medicine was intensively studied. The aim of this study was to determine the utility of urinary chemokines CCL2 (C‐C motif ligand 2) and CXCL10 (C‐X‐C motif chemokine ligand 10) in prognosis of 5‐year graft failure and mortality post 1‐year protocol biopsy in renal transplant recipients.
Methods
Forty patients who had a protocol biopsy 1 year after renal transplantation were included. Concentrations of CCL2 and CXCL10 in urine with reference to urine creatinine were measured. All patients were under the supervision of one transplant center. Long‐term outcomes within 5 years after 1‐year posttransplant biopsy were analyzed.
Results
Urinary CCL2:Cr at the time of biopsy was significantly increased in patients who died or had graft failure. CCL2:Cr was proven to be a significant predictor of 5‐year graft failure and mortality (odds ratio OR: 1.09, 95% confidence interval CI: 1.02–1.19, p = .02; OR: 1.08, 95% CI: 1.02–1.16, p = .04; respectively).
Conclusion
Chemokines are easily detected by current methods. In the era of personalized medicine, urinary CCL2:Cr can be considered as a factor providing complementary information regarding risk of graft failure or increased mortality.
Chemokines are easily, noninvasively detected in urine by enzyme‐linked immunosorbent assay, which could facilitate their application in clinical practice. In the era of personalized medicine, urinary CCL2:Cr can be considered as a factor providing complementary information regarding the risk of graft failure or increased mortality.
Molecular diagnosis of rejection is emerging in kidney, heart, and lung transplant biopsies and could offer insights for liver transplant biopsies. We measured gene expression by microarrays in 235 ...liver transplant biopsies from 10 centers. Unsupervised archetypal analysis based on expression of previously annotated rejection‐related transcripts identified 4 groups: normal “R1normal” (N = 129), T cell–mediated rejection (TCMR) “R2TCMR” (N = 37), early injury “R3injury” (N = 61), and fibrosis “R4late” (N = 8). Groups differed in median time posttransplant, for example, R3injury 99 days vs R4late 3117 days. R2TCMR biopsies expressed typical TCMR‐related transcripts, for example, intense IFNG‐induced effects. R3injury displayed increased expression of parenchymal injury transcripts (eg, hypoxia‐inducible factor EGLN1). R4late biopsies showed immunoglobulin transcripts and injury‐related transcripts. R2TCMR correlated with histologic rejection although with many discrepancies, and R4late with fibrosis. R2TCMR, R3injury, and R4late correlated with liver function abnormalities. Supervised classifiers trained on histologic rejection showed less agreement with histology than unsupervised R2TCMR scores. No confirmed cases of clinical antibody‐mediated rejection (ABMR) were present in the population, and strategies that previously revealed ABMR in kidney and heart transplants failed to reveal a liver ABMR phenotype. In conclusion, molecular analysis of liver transplant biopsies detects rejection, has the potential to resolve ambiguities, and could assist with immunosuppressive management.
In the INTERLIVER study of biopsies collected from liver transplant patients to develop a molecular diagnostic system, distinct phenotypes emerged for T cell–mediated rejection, early injury, and late fibrosis, but no distinct antibody‐mediated rejection classes were found. See Randhawa's editorial on page 1965.
In the industrialized world, hypertension affects approximately 30% of the general population. Hypertensive kidney disease is considered one of the consequences of long-term and poorly controlled ...hypertension. According to renal databases, it is a leading cause of end‑stage renal failure, second only to diabetic kidney disease. We challenge this dogma by emphasizing lack of specificity of both clinical and morphological presentations of hypertension‑related kidney disease and very low prevalence of hypertensive kidney disease that is diagnosed based on kidney biopsy findings in registries. In most cases of concomitant hypertension and chronic kidney disease (CKD), the sequence of events (ie, which came first, CKD or hypertension) cannot be established. Arterial hypertension plays a role in the pathogenesis of chronic vascular disease and may occasionally lead to arterionephrosclerosis, but its general significance in the evolution of CKD and prevalence among CKD patients appear to be highly overestimated. Studies of the morphology of kidney biopsies have indicated that arterionephrosclerosis, classically considered a morphological equivalent of the clinical term "hypertensive kidney disease"(previously referred to as "hypertensive nephropathy"), most commonly superimposes upon variable chronic renal diseases, even in the absence of elevated blood pressure. To date, no prospective controlled clinical trials have been conducted in primary hypertension patients with renal events as primary endpoints. Data from available clinical trials with renal events that serve as secondary endpoints suggest that lowering blood pressure below current targets may provide additional cardiovascular benefits but may be harmful to the kidneys.
Despite universal prophylaxis, late cytomegalovirus (CMV) infection occurs in a high proportion of kidney transplant recipients. We evaluated whether a specific viral T-cell response allows for the ...better identification of recipients who are at high risk of CMV infection after prophylaxis withdrawal.
We conducted a prospective study in 19 pretransplant anti-CMV seronegative kidney graft recipients R- (18 from seropositive donors D+ and one from a seronegative donor D-) and 67 seropositive recipients R(+) (59 from seropositive donors and eight from seronegative donors) who received antiviral prophylaxis with valganciclovir. The QuantiFERON-CMV (QF-CMV) assay was performed within the first and third months after transplantation. Blood samples were monitored for CMV DNAemia using a commercial quantitative nucleic acid amplification test (QNAT) that was calibrated to the World Health Organization International Standard.
Twenty-one of the 86 patients (24%) developed CMV viremia after prophylaxis withdrawal within 12 months posttransplantation. In the CMV R(+) group, the QF-CMV assay yielded reactive results (QF-CMV+) in 51 of 67 patients (76%) compared with 7 of 19 patients (37%) in the CMV R(-) group (p = 0.001). In the CMV R(+) group, infection occurred in seven of 16 recipients (44%) who were QF-CMV(-) and eight of 51 recipients (16%) who were QF-CMV(+). In the CMV R(-) group, infection evolved in five of 12 recipients (42%) who were QF-CMV(-) and one of 7 recipients (14%) who were QF-CMV(+). No difference was found in the incidence of CMV infection stratified according to the QF-CMV results with regard to the recipients' pretransplant CMV IgG serology (p = 0.985). Cytomegalovirus infection occurred in 15 of 36 patients (42%) with hypogammaglobulinemia (HGG) 90 days posttransplantation compared with two of 34 patients (6%) without HGG (p = 0.0004). Cytomegalovirus infection occurred in seven of 13 patients (54%) with lymphocytopenia compared with 14 of 70 patients (20%) without lymphocytopenia (p = 0.015). The multivariate analysis revealed that the nonreactive QuantiFERON-CMV assay was an independent risk factor for postprophylaxis CMV infection.
In kidney transplant recipients who received posttransplantation prophylaxis, negative QF-CMV results better defined the risk of CMV infection than initial CMV IgG status after prophylaxis withdrawal. Hypogammaglobulinemia and lymphocytopenia were risk factors for CMV infection.
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