Clinical and Histopathological Factors Influencing IgA Nephropathy Outcome

IgA nephropathy (IgAN) is the most frequent primary glomerulonephritis worldwide. Due to its heterogenicity, there is a need to establish robust biomarkers for IgAN, to support treatment decisions and evaluate the risk of progression to end-stage renal disease. Using both clinical and histopathological data, derived from renal biopsies, we aimed to find predictors of renal function deterioration and proteinuria reduction. Clinical and histopathological data of 80 patients with biopsy proven IgAN were analyzed. In a multivariate logarithmic regression model, the presence of endocapillary hypercellularity (E1) predicted a decline in estimated glomerular filtration rate (eGFR)of at least 50% with an odds ratio (OR) of 15.2, whereas serum albumin concentration had a negative influence on eGFR deterioration (OR 0.2). In the second multivariate model, the extent of interstitial fibrosis predicted the worsening of eGFR by 50% (OR 1.1) and serum albumin concentration had a protective impact (OR 0.1). In the univariate logarithmic regression, both the extent of interstitial fibrosis and the presence of endocapillary hypercellularity negatively correlated with the reduction in proteinuria below 1.0 g/24 h with an OR of 0.2 and 0.9, respectively. In our paper, we confirmed the utility of histopathological variables, especially endocapillary hypercellularity and interstitial fibrosis, and clinical parameters, particularly serum albumin concentration, in the prediction of both a decline in eGFR and a reduction in proteinuria in IgA nephropathy.

Comparative Long-Term Renal Allograft Outcomes of Recurrent Immunoglobulin A with Severe Activity in Kidney Transplant Recipients with and without Rituximab: An Observational Cohort Study

Recurrent IgA nephropathy (IgAN) remains an important cause of allograft loss in renal transplantation. Due to the limited efficacy of corticosteroid in the treatment of recurrent glomerulonephritis, rituximab was used in kidney transplant (KT) recipients with severe recurrent IgAN. A retrospective cohort study was conducted between January 2015 and December 2020. Accordingly, there were 64 KT recipients with biopsy-proven recurrent IgAN with similar baseline characteristics that were treated with the conventional standard therapy alone (controls, n = 43) or together with rituximab (cases, n = 21). All of the recipients had glomerular endocapillary hypercellularity and proteinuria (>1 g/d) with creatinine clearance (CrCl) > 30 mL/min/1.73 m2 and well-controlled blood pressure using renin–angiotensin–aldosterone blockers. The treatment outcomes were renal allograft survival rate, proteinuria, and post-treatment allograft pathology. During 3.8 years of follow-up, the rituximab-based regimen rapidly decreased proteinuria within 12 months after rituximab administration and maintained renal allograft function—the primary endpoint—for approximately 3 years. There were eight recipients in the case group (38%), and none in the control group reached a complete remission (proteinuria < 250 mg/d) at 12 months after treatment. Notably, renal allograft histopathology from patients with rituximab-based regimen showed the less severe endocapillary hypercellularity despite the remaining strong IgA deposition. In conclusion, adjunctive treatment with rituximab potentially demonstrated favorable outcomes for treatment of recurrent severe IgAN post-KT as demonstrated by proteinuria reduction and renal allograft function in our cohort. Further in-depth mechanistic studies with the longer follow-up periods are recommended.

Antiglomerular basement membrane (anti-GBM) disease with clinical and histological features that bridge the typical to atypical spectrum

We describe antiglomerular basement membrane (anti-GBM) disease with rapidly progressive glomerulonephritis and concurrent parainfluenza pneumonia. Circulating anti-GBM antibodies were barely detectable and disappeared rapidly following corticosteroids, cyclophosphamide and plasma exchange. Kidney biopsy demonstrated strong linear GBM staining for IgG and IgG4 and unusually prominent endocapillary hypercellularity, suggesting ‘atypical anti-GBM disease’, although glomerular necrosis and crescents were also seen. When kidney function deteriorated further, despite persistently absent circulating anti-GBM antibodies, a repeat kidney biopsy was performed, showing crescents in 100% of glomeruli with ongoing endocapillary hypercellularity and strong IgG and IgG4 GBM staining. This case highlights complexities in the diagnosis of anti-GBM disease, with clinical and histological features bridging the atypical to typical anti-GBM disease spectrum. We hypothesise that these findings might be explained by the presence of IgG4 (rather than traditional IgG1 or IgG3) autoantibodies. To our knowledge, this is also the first report of parainfluenza associated with anti-GBM disease.

A Case of Recurrent Atypical Anti-Glomerular Basement Membrane Nephritis Suspicion after Renal Transplantation

Atypical anti-glomerular basement membrane (GBM) nephritis is a rare variant of the classical anti-GBM antibody disease. Patients present with an undetectable anti-GBM antibody but show linear glomerular basement membrane staining for immunoglobulin. We present a 69-year-old man who underwent a living-donor kidney transplant. The aetiology of the renal failure was a focal segmental glomerulonephritis-like lesion resistant to immunosuppressive therapy. A renal graft biopsy revealed diffuse endocapillary hypercellularity, and mild mesangiolysis with linear GBM staining for IgG. The patient was diagnosed with atypical anti-GBM nephritis since the patient tested negative for circulating anti-GBM antibodies. Treatment involved intravenous methylprednisolone, plasma exchange, and rituximab administration. Protocol graft biopsy performed 1 year after the renal transplant showed a focal segmental glomerulonephritis-like lesion possibly progressing from endocapillary hypercellularity and mesangiolysis. These findings were similar to his native kidney biopsy findings. Although classical recurrent anti-GBM nephritis is rare when a renal transplant is performed after decreased disease activity, this case was considered as a case of recurrent atypical anti-GBM nephritis after renal transplant.

The association of microhematuria with mesangial hypercellularity, endocapillary hypercellularity, crescent score and renal outcomes in immunoglobulin A nephropathy

Background Microhematuria is common in immunoglobulin A nephropathy (IgAN). However, current prognostication is based on proteinuria and mesangial hypercellularity, endocapillary hypercellularity, segmental sclerosis, tubulointerstitial fibrosis and crescent (MEST-C) scores. Methods In this retrospective study, we evaluated whether MEST-C score components are associated with the presence of microhematuria at biopsy and whether the degree of microhematuria during follow-up is associated with change in estimated glomerular filtration rate (eGFR), after adjusting for clinical and histological parameters. We identified 125 patients with biopsy-proven IgAN and MEST-C scoring who were not on immunosuppressive therapy at biopsy. Microhematuria was defined as ≥3 red blood cells (RBCs)/high-power field (hpf). Results Of the 125 patients, 97 had microhematuria at baseline and were more likely to have M1, E1 and C ≥ 1 lesions (P &lt; 0.05 for all) compared with patients without microhematuria. Of the 125 patients, 72 had follow-up data available. An increase in the degree of microhematuria was significantly associated with an eGFR decline of −0.81 mL/min/1.73 m2 [95% confidence interval (CI) −1.44 to −0.19, P = 0.01], after adjusting for follow-up time, proteinuria and T score. Severe microhematuria (≥21 RBCs/hpf) was associated with an even larger decline in eGFR (−3.99 mL/min/1.73 m2; 95% CI −6.9411 to −1.0552, P = 0.008), after similar adjustments. Conclusion Degree of microhematuria during follow-up is an independent predictor of eGFR decline after adjusting for clinical and histological parameters. Therefore, monitoring the degree of microhematuria as well as proteinuria is important when evaluating patients with IgAN. Additional studies using improvement in microhematuria as a primary surrogate outcome are needed.

Histopathology Interstitial Severity Index Associated with Glomerular and Tubular Severity Index in Nephrotic Syndrome Patients

Introduction: Nephrotic syndrome is characterized by massive proteinuria due to leakage of glomerular basal membrane, and subsequent process in tubular and interstitial tissue. It should be elucidated whether the severity of histopathological lesions in compartments of kidney tissue play a role and whether lesion in those compartments associated one to another. Aim: The study aims to correlate severity histopathologic lesions among compartments in kidney tissue. Method: All patients with nephrotic syndrome were biopsied and the cores were stained with Hematoxylin-Eosin, PAS, Masson’s Trichrome to look at glomerular, tubular, interstitial and vascular involvements. Glomerular abnormalities including mesangial hypercellularity, endocapillary hypercellularity, membranous; tubular, interstitial, and vascular severities were scored according to type, activity, severity and distribution in histopathologic features. Results: This study included 46 patients consisted of 16 (34.8%) males and 30 (65.2%) females, aged 26 ± 10 years, SBP 121.7 ± 13.10 and DBP 78.21 ± 7.80 mmHg, diagnosed with 14 lupus and 32 non-lupus nephrotic syndrome. Histopathologic abnormalities showed glomerular index was 4.26 ± 2.34, tubular index was 3.09 ± 1.90, interstitial index was 3.02 ± 1.48, vascular index was 0-3, pathologic index was 10.56 ± 4.54. There was significant correlation of severity index between interstitial and glomerular lesions (R=0.49, P=0.001), and between interstitial and tubular lesions (R=0.45, P=0.002). However, there were no significant correlations of severity index between interstitial and vascular lesions, and glomerular and tubular lesions. Conclusion: There are significant correlations of severity index between interstitial with glomerular and tubular lesions. It may implicate that histopathological process in interstitial tissue plays a central role in the pathogenesis of proteinuria in nephrotic syndrome.

RETROSPECTIVE STUDY OF HISTOLOGICAL ANALYSIS AND ITS CORRELATION WITH CLINICAL PRESENTATION AND OUTCOME OF IGA NEPHROPATHY FROM A TERTIARY CENTRE OF GUWAHATI ASSAM.

Background: IgA nephropathy (IgAN) is one of the most common glomerular diseases with varied presentations. We aimed to study clinical presentation and outcome of IgAN and correlate with histopathology at the time of presentation. Methods: This is a retrospective study in which we analyzed kidney biopsy data, clinical manifestations and outcome of 137 patients with a diagnosis of primary IgAN from 2012 to 2016. Kidney biopsies were reviewed as per Oxford classification assessing mesangial hypercellularity, endocapillary hypercellularity, segmental sclerosis/adhesion, tubular atrophy/interstitial fibrosis. Correlation analysis was done for biopsy findings and clinical presentation/outcome. P score less than 0.05 was taken as significant. Results: Mean age for presentation was 27.35 years with 83 males and 54 females. Asymptomatic urinary abnormality was the most common clinical presentation (28.5%). Mean serum creatinine was 2.23 ± 2.06mg/dl with mean proteinuria of 1.49 ± 1.43g/day. Mesangial hypercellularity (M) and Endocapillary hypercellularity (E) lesions were significantly associated with proteinuria at the time of biopsy (p=0.02& 0.04 respectively). Segmental glomerulosclerosis (S) and tubular atrophy (T) were significantly associated with eGFR and mean arterial pressure at the time of biopsy. Mean time of follow up was 1.6 years. M1, E0, S1, T0 were the most common lesions. M, S and T lesions in biopsy were significantly associated with decrease in GFR at the end of follow up. Conclusion: In our study, most common presentation of IgAN was AUA with rarity of macroscopic hematuria. M, S and T lesions were associated with decreased GFR on follow up. Key words: IgA Nephropathy, Nephrotic Syndrome, Oxford MEST classification

Location of glomerular immune deposits, not codeposition of immunoglobulin G, influences definitive renal outcomes in immunoglobulin A nephropathy

ABSTRACT Background It has been suggested that the prognosis of immunoglobulin (IgA) nephropathy (IgAN) is adversely affected if there is codeposition of IgG in the glomeruli or if immune deposits are present in the glomerular capillary walls. We sought to understand how these variables affect clinical outcome. Methods A total of 80 IgAN biopsies were retrospectively divided into groups: (i) IgA without IgG deposition versus IgA + IgG and (ii) immune deposits restricted to the mesangium versus mesangium and peripheral capillary walls (PCWs). The association of these groups with the composite primary outcome of renal replacement therapy, renal transplant, death or doubling of serum creatinine (SCr) concentration was determined. The change in estimated glomerular filtration rate (eGFR) was also assessed. Covariates examined were age, sex, race, SCr and proteinuria level at biopsy and at follow-up, duration of follow-up, treatment, Oxford score and presence of crescents. Results IgG codeposition showed a trend toward endocapillary hypercellularity (P = 0.082); there were no other baseline differences between the IgA (n = 55) and IgA + IgG (n = 25) groups. At a median follow-up time of 29 months, the combined primary outcome was reached in 24 patients, 16 with IgA and 8 with IgA + IgG (P = 0.82). Patients with immune deposits in the PCWs (n = 21) presented with higher baseline proteinuria than those with deposits limited to the mesangium (n = 59; P = 0.025), were more likely to have crescents/segmental glomerular necrosis on biopsy (P = 0.047) and were more likely to reach the combined primary outcome (P = 0.026). Biopsies with crescents/segmental glomerular necrosis were associated with endocapillary hypercellularity (P < 0.001). Conclusions In this multicenter IgAN cohort, IgG co-deposition and the location of glomerular immune deposits in the PCWs were both associated with greater histologic activity on renal biopsy, but only the location of glomerular immune deposits in the PCWs was associated with a significantly increased risk for end-stage renal disease, transplant, death and/or doubling of SCr.