IgA Deposits Research Articles

#4488 OLD BIOPSY IS ALWAYS GOLD, REVISING MEMBRANOPROLIFERATIVE GN DIAGNOSIS IN A RENAL TRANSPLANT PATIENT

Abstract Background and Aims MPGN resulting from hepatitis C virus (HCV) infection typically shows granular deposition of immunoglobulin M (IgM), C3, and both kappa and lambda light chains. Immunoglobulin G (IgG) may or may not be present, and C1q is typically negative, the same pathology can be found in other viral infections. The recurrence rate post-transplantation is high, with 33% of immune-complex MPGN. Graft loss is even higher 65%, especially among patients with idiopathic MPGN. Treatment of a patient with significant proteinuria can be tricky, as no proven treatment is described yet, but plasmapheresis and induction with cyclophosphamide were described for heavy proteinuria >3.5 g/day. Method 79 year old female patient, known case of live unrelated renal transplantation in December 2013, primary renal disease is unknown. She had a history of equivocal hepatitis C virus antibodies, but Hepatitis C virus RNA was not detected. She is also known to have Type II Diabetes Mellitus and hypertension. The patient had baseline creatinine of 100-120 micromol/L. 24 hr urine protein was 0.8 g/Day but started rising quickly to reach a peak of 9.2 g/g seven months post-transplantation to nephrotic range proteinuria but her serum albumin level was always above 35 g/L. Serum protein electrophoresis showed no M band, a kappa/ Lambda ratio 1.21 within a normal range (0.260-1.65). Anti- nuclear antibody (ANA), P-ANCA, C-ANCA, and Double-stranded DNA all were negative. Complements were within normal range C3 1.39 g/L (0.79 -1.52), C4 0.44 g/L(0.17-0.57)m rheumatoid factor and Anti- citrullinated peptide antibodies were negative. Hepatitis b Virus surface antigen and core antibodies were not reactive, HIV screening was negative. Urine analysis showed RBCs but no RBC casts. Renal biopsy showed mild mesangial expansion and mild l increase in mesangial cells and matrix. Some glomeruli show increased lobulation with increase in mesangial cells and matrix with segmental endocapillary proliferation There is double contour of the glomerular basement membrane with scattered spikes and holes within the basement membrane seen best with silver stain. There is mild increase in the thickness of glomerular basement membrane. There is focal mild lymphocytic infiltration. Tubulitis is not seen in the examined material. One Focal area of mild interstitial fibrosis. Sampled blood vessels are unremarkable. The stain for C4d is negative. Immunofluorescence showed granular capillary wall immunoreactivity to IgM (+2), C4 (+1), C1q (+1), and Lambda light chain (+2). The glomeruli show no immunoreactivity to IgG, IgA, C3, Kappa and fibrin. The glomeruli show (+) staining for albumin. Tubular protein reabsorption droplets showed immunoreactivity for albumin, IgG, IgM, C3, kappa and lambda light chains. Electron microscopy showed many subendothelial, and mesangial electron-dense deposits. The patient was on maintenance immunosuppression medications inform of mycophenolic acid 720 mg, cyclosporine; 250mg BID, and Prednisolone 5 mg daily.Revisiting the new classification of membranoproliferative glomerulonephritis is challenging in this patient, since there is the dominance of IgM deposition by immunofluorescence and C4 but not C3 makes it challenging, the negative monoclonal band in serum electrophoresis and negative autoimmune workup excludes immune complex mediate MPGN, leave idiopathic MPGN a possibility, keeping in mind that hepatitis C virus infection was never confirmed. On the other hand, IF showed IgM with C4 subendothelial and mesangial dense deposits that excludes away the C4 glomerulopathy. Results Whether this is a recurrence of glomerular disease early on post-transplantation or denovo membranoproliferative disease, she responded well to the addition of losartan 100 mg daily, with a reduction of her urinary protein to less than 1 g/g. the patient never received treatment for the hepatitis C virus. Conclusion In our patient, it is difficult to conclude if the cause of MPGN is recurrence or denovo GN, especially with severe proteinuria that responded well to ACEi treatment. The pathological findings can be tricky.

#2533 PROGNOSTIC SIGNIFICANCE OF ARTERIOLAR C4D POSITIVITY AS A MARKER OF MICROANGIOPATHY IN ANCA-ASSOCIATED VASCULITIS

Abstract Background and Aims ANCA-associated vasculitis (AAV) represent a group of systemic autoimmune diseases characterized by necrotizing inflammation of small to medium-size blood vessels frequently associated with anti-neutrophil cytoplasmic antibody (ANCA) positivity. Another term they are commonly referred with is “paucimmune vasculitis”, reflecting the lack of immune complex deposition on histological samples, in contrast with other small vessel vasculitis, e.g. cryoglobulinemic vasculitis. The absence or the paucity of deposition of immunoglobulins and complement components was interpreted in the past as a lack of complement cascade involvement in the pathogenesis of AAV. Only in relatively recent times the possible role of complement in AAV was investigated. A few studies proved the relationship between C3 hypocomplementemia and worse renal outcome[1]. Moreover, the overactivation of the alternative complement pathway (ACP) in AAV could be responsible for thrombotic microangiopathy (TMA). A strong association between low serum C3 and histologic signs of thrombotic microangiopathy on renal biopsy was shown in patients with AAV, with a worse renal prognosis. Currently, there are no clear early histological markers of endothelial damage that allow to identify high-risk patients, other than the seldom not identified or misidentified presence of TMA. The association between renal arteriolar C4d deposition (as a vicariate of TMA) has been already described in several glomerulonephritis, including IgA nephropathy [2], but its prognostic meaning has not yet been explored [3]. Our study aims to explore the predictive role of arteriolar C4d in ANCA-associated GN. Method All patients with ANCA-associated GN who underwent a kidney biopsy between January 1990 and June 2021 at the Renal Unit of Parma University Hospital, Parma, Italy with at least 6 months follow-up data were included. All histology slides were retrieved and reviewed by experienced nephropathologists. Percent IFTA, percent global glomerulosclerosis, Brix score, the presence or absence of TMA, the positivity or negativity of C4d (immunohistochemical staining on paraffin-embedded formalin-fixed slides) were taken note of. C4d positivity was correlated with the presence of TMA and patients outcome (Fig. 1). Results We identified 58 patients who met our criteria. 14 patients were excluded because biopsy specimens were not available for histologic review. Clinical and laboratory baseline and follow-up data for the remaining 44 patients were thus collected. Conclusion C4d and TMA were independently associated (p = 0.003). A tendency towards association between C4d and death-censored ESRD was observed (Fig. 2), although not statistically significant (p = 0.434), likely due to the limited sample size. In order to test our hypothesis, validation on a larger cohort is currently underway.

#6895 ANCA AND IGA NEPHROPATHY: ASSOCIATION OR PROGNOSTIC FACTOR

Abstract Background and Aims ImmunoglobulinA(IgA) nephropathy (IgAN), the most prevalent form of primary glomerulonephritis worldwide, is characterized by mesangial cell proliferation, matrix expansion, and mainly mesangial IgA deposition, often in conjunction with C3 and IgG and/or IgM. Its pathogenisis is enigmatic, It is reported that approximately 35-42% of IgAN patients have a history of macrohematuria before kidney biopsy. Its a benign pathology which somtimes could be associated with cresentic proliferation and more rarely by the presence of ANCA antibodies. Method We retrospectively analyzed the epidemiologic, clinical and histological data of 27 patients with Ig A nephropathy proven by biopsy and we compared 2 groups ANCA positive and ANCA negative patients. Results The present study involved 27 patients, 18 men and 9 women, the average age was 27.9 years 3 patients were ANCA positive compared to 24 ANCA negative ; (2 were MPO-ANCA and 1 PR3-ANCA). ANCA positive patients were older, with more severe initial renal function, lower hemoglobin, and a higher percentage of general symptoms than the ANCA negative ones Histologically, therewas a significantly higher percentage of fibrinoid necrosis in glomeruli in ANCA-positive IgAN patients ANCA-positive patients with IgA nephropathy had a higher percentage of crescentic glomeruli (54.5%) compared with ANCA-negative patients with crescentic IgA nephropathy (26%). The ANCA positive patients was all treated by solumedrol boli and oral corticotherapy and showed more severe prognosis, the 3 patients progressed to ESKD. 4 ANCA-negative patients were treated with oral corticotherapy, some from the other 20 patients have been put on renin angiotensin system bloquers treatment and thy shoxed a better renal prognosis. Conclusion IgAN patients with ANCA positivity showed more severe clinical and histological features when compared with ANCA-negative IgAN patients and lower renal prognosis. The ANCA antibodies should be screened in patients with severe forms of IgAN.

#6227 SPONTANEOUS REMISSION OF MEMBRANOUS VARIANT OF PGNMID WITH MONOCLONAL IGG2κ

Abstract Background and Aims The clinical significance of the morphological patterns of glomerular injury and of each IgG subclass in proliferative glomerulonephritis (GN) with monoclonal immunoglobulin deposits (PGNMID) is not well understood. Literature suggests that PGNMID with certain histological features such as membranous or mesangio-proliferative features or non-IgG3 subclass staining may be associated with a more favourable renal prognosis. We present a patient with membranous variant of PGNMID with monoclonal IgG2κ who had spontaneous remission without recurrence over a 2-year follow-up. Method Not applicable Results A 62-year-old Malay gentleman presented with new onset nephrotic range proteinuria, on a background of type 2 diabetes mellitus with diabetic duration of 5 years, hypertension and hyperlipidemia. He was mildly hypertensive (blood pressure 148/87) and non-edematous at presentation. Investigations revealed preserved kidney function [serum creatinine (sCr) 66µmol/L], bland urinalysis, and 24-hour urinary total protein (UTP) of 3.74g/day. Serum albumin (sAlb) was 35g/L. Serum complements were not low. Autoimmune markers inclusive of anti-double stranded DNA antibodies, anti-neutrophil cytoplasmic antibodies, and anti-phospholipase A2 receptor (PLA2R) antibodies were negative. Viral serologies were also unremarkable. No monoclonal band was detected on serum electrophoresis, while serum immunofixation was not performed. Kidneys were normal sized. Renal biopsy performed demonstrated 28 glomeruli, of which only 1 was globally sclerosed. Glomeruli capillary walls were diffusely thickened by vacuolations. Capillary loops were mostly single contoured although occasional focal double contouring was seen. Masson trichome stain revealed fuchsinophilic subepithelial immune deposits while periodic acid methenamine silver stain showed argyrophilic basement membrane spikes. Variable mesangial expansion and hypercellularity was observed, as well as mesangiolysis. Focal leukocyte margination was present, but significant endocapillary proliferation was not seen. There were no Kimmelstiel-Wilson lesions. Tubular atrophy with interstitial fibrosis was overall mild (10% of parenchymal area) and there were no tubulointerstitial infiltrates. Immunofluoresence showed granular staining of IgG (1-2+), C3 (2-3+) along glomerular capillary walls, as well as presence of kappa light chain restriction (κ 1-2+; λ negative in glomeruli). Immunostaining for PLA2R was negative. IgG subclass analysis performed in view of kappa restriction revealed isolated deposition of IgG2. Electron microscopy was not available. Overall findings were most consistent with membranous variant of PGNMID with monoclonal IgG2κ. Age-appropriate and symptom-directed malignancy screening did not reveal significant abnormalities. Given that the patient was minimally symptomatic, a trial of conservative therapy was initiated with optimized non-immunosuppressive anti-proteinuric therapy using renin-angiotensin-aldosterone and sodium-glucose co-transporter-2 inhibitors. Gradual spontaneous remission was observed without recurrence over 2 years of follow-up (sCr 77µmol/L; sAlb 40g/L; 24-hour UTP 0.22g/day). Conclusion Our case adds to the literature that a membranous variant of PGNMID with monoclonal IgG2κ may be associated with better renal outcomes. Despite the lack of proliferative changes, it is possible that membranous variants may share similar underlying disease mechanisms as the other proliferative variants. Large international registries to allow the correlation of morphological features and IgG subclasses with clinical outcomes are required to confirm our observation.

#3922 CLINICOPATHOLOGICAL CHARACTERISTICS OF LIGHT AND HEAVY CHAIN DEPOSITION DISEASE: A CASE SERIES FROM A SINGLE CENTER

Abstract Background and Aims Light and heavy chain deposition disease (LHCDD) is the rarest form of monoclonal immunoglobulin deposition disease (MIDD) characterized by the deposition of the monoclonal light chain and heavy chain. At present, the large-scale clinical research data of LHCDD is limited. We explore the clinical-pathologic characteristics and outcome of LHCDD in a single center of China, to obtain a better understanding of this disease. Method We reviewed 65291 native kidney biopsies from January 2008 to December 2022. Ten patients with biopsy-proven LHCDD diagnosed were studies retrospectively. Results 4 males and 6 females, with an average age of 52.5 ± 8.9 years were enrolled. The patients were presented with hypertension (80%), anemia (90%), elevated serum creatinine (70%), proteinuria (100%), nephrotic syndrome (30%) and microscopic hematuria (90%). Serum immunofixation electrophoresis showed that 8 (80%) patients were positive for monoclonal immunoglobulin (IgG-κ/IgG-λ/IgA-λ: 3/2/3). Serum free light chain (FLC) ratio was abnormal in 9 (90%) patients. Among them, 5 patients had an Elevated FLC ratio (κ:λ > 1.65), and an FLC ratio < 0.26 was observed in 4 patients. Two patients were diagnosed with multiple myeloma. Histologically, nodular mesangial sclerosis was identified in 9 (90%) patients. Immunofluorescence showed that 6 patientshad depositions of heavy chain IgG (γ1-κ/γ1-λ/γ2-κ/γ2-λ/γ3-κ:2/1/1/1/1), and 4 patients of heavy chain IgA (α-κ/α-λ:1/3). During a median of 28 months of follow-up (range, 6–104 months) in 9 patients, 8 patients received chemotherapy. Three (33%) patients had complete hematologic remission (CR), 2 (22%) had very good partial hematologic response (VGPR) or partial hematologic response (PR), and 4 (44%) had no response (NR). One (11%) had stable/improved renal function, 6 (67%) had worsening renal function, and 3 (33%) progressed to ESRD. All 9 patients survived. Conclusion In this case series of LHCDD in a single center in China, light and heavy chain deposition in renal tissues was most frequent with IgG-κ, followed by IgA-λ, IgG-λ and IgA-κ. More than half patients had hematologic response but poor renal prognosis.

#4220 NOT JUST AIN? OTHER IMMUNE-CHECKPOINT INHIBITOR LESIONS: A SINGLE INSTITUTION'S EXPERIENCE OVER 12 YEARS

Abstract Background and Aims Immune-checkpoint inhibitors (ICI) are antineoplastic therapies that unleash the immune-system and have revolutionized cancer outcomes. Though they are a drug class with great potential, their effects are not always limited to the malignant cells and can cause a spectrum of immune-related adverse events (irAEs). Roughly 5% of patients will experience acute kidney injury (AKI) with acute interstitial nephritis (AIN) being the predominant pathologic lesion. Glomerular and vascular lesions are thought to be rare and, as a result, not well-defined. We aim to document glomerular and vascular pathology in this context at our institution. Method We performed a retrospective review of internal native renal biopsies from 2010-2022 that had known ICI treatment. Standard processing of renal biopsies included light microscopy (LM), immunofluorescence (IF), and electron microscopy (EM). We reviewed the biopsies and pathology reports, as well as clinical data from patient electronic medical records. Results Our search yielded 32 kidney biopsies; of those, most had AIN (27/32), 8 cases had glomerular pathology, and 1 case had arterial endotheliitis. Of the cases with glomerular pathology, 4 had subacute glomerular thrombotic microangiopathy (TMA). Among the cases with TMA, 2 were also treated with vascular endothelial growth factor inhibitor (VEGFi),1 with gemcitabine, and 1 with BRAF-inhibitor therapy. Further, only one of these patients had complement testing, which did not reveal definitive deficiency. One patient had proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID), IgG-κ. One patient had IgA nephropathy (IgAN) and another had membranous nephropathy (MN). Most patients were biopsied for rising serum creatinine (SCr) (median: 1.6 mg/dL; range: 0.55-5.5); 1 had nephrotic-range proteinuria (median urine protein/creatinine ratio (UPCR): 0.3; range: 0.12-5.64). One, with thin basement membrane disease, had significant hematuria (>100 RBC/hpf). Five patients had irAEs in other organs. 7/9 patients died or entered hospice care (median: 14 months post-biopsy; range: 2-48 months) due to malignancy progression. Of the deceased patients, 2 were dialysis-dependent. Of the living patients, 1 has dialysis-independent chronic kidney disease (CKD). Conclusion Overall, glomerular and vascular pathology due to ICI-use appears rare though difficult to isolate since other drugs and neoplasia can cause similar lesions. In our cohort, TMA was the most common glomerular lesion, though direct causation due to ICI is difficult to prove. In all patients with TMA, we identified concurrent use of other known causative drugs. IgAN and MN have been reported in association with neoplasia. PGNMID has been reported in a variety of malignant and nonmalignant conditions, and ICI-use could be a triggering factor. In conclusion, the patterns of glomerular injury seen in our cohort may be secondary to other concurrent risk factors other than ICI use. Arterial endotheliitis appears to be a rare but significant secondary effect to ICI-use.

#3597 MONOCLONAL GAMMOPATHY AS A RISK FACTOR FOR ARTERIOVENOUS FISTULA PRIMARY FAILURE

Abstract Background and Aims Arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis (HD) in most patients. However, postoperative complications such as primary failure (PF) with a reported incidence between 20-60% remain a major problem. Patients diagnosed with monoclonal gammopathy (MG) are at increased risk of thrombotic events, either due to the disease itself or the chemotherapy used for its treatment. The aim of this study was to evaluate whether the presence of MG was associated with primary AVF failure. Method We performed a retrospective single-center case-control study including 103 patients observed in our vascular access consultation for planning their first HD access. Demographic and clinical data were collected, such as the presence of diabetes, hypertension, cardiovascular disease and MG. Distal AVF was the access of choice when possible. Primary failure was defined as incapacity to use AVF for HD because of failure to mature or thrombosis. Univariate analysis was performed, and a logistic regression was applied to access predictors of PF. A p-value inferior to 0,05 indicated statistical significance. Results In total 14 (13.6%) patients had MG (11 multiple myeloma, 1 light-chain deposition disease, 1 proliferative glomerulonephritis with monoclonal immunoglobulin deposits and 1 amyloid light-chain amyloidosis). Regarding the AVF location, 13 patients constructed a constructed a distal AVF and 1 patient a proximal AVF. When compared to the group of 89 patients who did not have MG, there were no significance differences in sex, age, prevalence of diabetes and cardiovascular disease neither in AVF construction site. Arterial hypertension was more frequent in the group of patients without MG (93.2% versus 64.3%, p = 0.007). PF occurred in 57.1% (8/14) of patients with MG and in 27% (24/89) of those without MG (p = 0.032). In logistic regression, the presence of MG was the only predictor of primary AVF failure (OR 4.39 95% CI: 1.23-15.75). Conclusion In our study, we found that a patient with monoclonal gammopathy has a 4-fold increased risk for primary AVF failure comparing to the general chronic kidney disease patients. Therefore, a careful evaluation must be made when planning for AVF placement in these patients, balancing individual life's expectancies and monoclonal gammopathy prognosis.

#6541 GLOMERULONEPHRITIS DIAGNOSIS BY MACHINE LEARNING ON PERIODIC ACID-SCHIFF (PAS) WHOLE SLIDE IMAGES

Abstract Background and Aims Machine learning (ML) holds great promise for improving diagnostics, prognostication and theranostics in nephropathology. So far, applications have not gone much further than segmentation of tissue compartments on whole slide images (WSIs) of paraffin sections. As a proof-of-concept study, we describe the development of a diagnostic classifier for glomerulephritis based on expert-annotated or automatically segmented glomerular transections from periodic-acid Schiff (PAS) paraffin sections only. Method A total of n = 350 biopsies from 5 institutions with 12 classes of glomerulonephritis IgA nephropathy (IgAN), membranous nephropathy (Membranous), anti-glomerular basement membrane antibody GN (ABMGN), infection-associated GN (IAGN), ANCA-associated GN (ANCA-GN), idiopathic membranoproliferative GN (MPGN), SLE GN class IV (SLE-GN-IV), cryglobulinemic GN (CryoGN), C3 GN (C3-GN), dense deposit disease (DDD), fibrillary GN (FibrillaryGN) and proliferative GN with monoclonal immunoglobulin deposits (PGNMID) were included in the study with their respective PAS sections. Glomerular transections were expert-annotated by a nephropathologist and automatically segmented with our own transformer-based segmentation model trained on 100 biopsies with thrombotic microangiopathies and a range of vascular, vasculitic and glomerular diseases closely resembling/mimicking thrombotic microangiopathies. For classification, we divided the cohort into 5 folds for internal cross-validation, performed sample size augmentation with various methods (including shifts in resolution/scale, AutoAugment and others) and trained our proprietary self-attention-based MILx architecture on an EfficientNet backbone with selection of glomerular crop batches by soft Markov chain Monte Carlo sampling in a semi-supervised fashion, with diagnostic class labels for each biopsy. We compared the performance of our proprietary architecture on both expert-annotated and automatically segmented glomerular crops with a recently published benchmark architecture (CLAM) for multiple-instance learning in histopathology. Results Automatic glomerular segmentation performance was excellent with mean AUC and sensitivity (mean average recall) over all classes at 0.904, with near perfect mean average specificity (0.994), as expected best for Membranous, worst for ABMGN. Classification performance of MILx with expert-annotated glomerular crops as inputs had a mean balanced accuracy of 0.84, with AUC metrics in descending order of 0.97 for Membranous, 0.89 for ABMGN, 0.88 for IgAN, 0.86 for Fibrillary, 0.83 for MPGN, 0.80 for ANCA-GN, 0.79 for DDD, 0.78 for PGNMID, 0.75 for IAGN, 0.73 for SLE-GN-IV and CryoGN, 0.67 for C3-GN. Performance with MILx was similar for automatically segmented glomerular crops as input. On this dataset, MILx outperformed CLAM with both entire WSIs as well as expert-annotated glomerular crops as inputs (mean balanced accuracy of 0.72) by a significant margin. Conclusion This proof-of-concept-study indicates that nephropathology-specific architectures like our MILx can be trained for complex tasks on relatively small biopsy cohorts. We should be able to deliver an end-to-end-pipeline for this diagnostic and other tasks based on training sets with case-labels provided by trusted institutions with only minimal expert labeling or annotation required. PAC and HQ contributed equally to this work.

#5788 MONOCLONAL GAMMOPATHY OF RENAL SIGNIFICANCE: A SINGLE CENTER EXPERIENCE

Abstract Background and Aims Monoclonal gammopathy of renal significance is an organ-threatening manifestation of paraproteinemia. It can be secondary to the clonal proliferation of either plasma cells or mature B-lymphocytes. The underlying clonal disorder does not meet the current hematologic criteria for immediate myeloma-specific therapy. With the advent of routine use of light chain detection by immunofluroscence technique in tissue biopsy, more cases of monoclonal gammopathy of renal significance are being diagnosed but there remains a therapeutic uncertainty. Data regarding the prognosis and outcomes of the various clinical manifestations of monoclonal gammopathy of renal significance is limited due to its rarity and under diagnosis. MGRS if left untreated can lead to end-stage renal disease and premature death. Method This is a retrospective study conducted at the Institute of Nephro-urology, Bangalore by retrieving the data from the digital medical records of our institute. Demographic and clinical details of the patients diagnosed with monoclonal gammopathy of renal significance from 1 st January 2018 to 31 st October 2022 were collected. Myeloma related light chain cast nephropathy was excluded from the study. Follow-up data were collected usingout patient data base, through telephone, and from the records at the cancer institute where the patient was referred post-diagnosis at our institute. The data collected was entered in excel and analyzed using SPSS software version 27.0. Results Fifty eight patients (n = 52) were diagnosed with the disease during the study period. MGRS contributed to 1.27% of all the renal biopsies conducted at our institute during the study period. The mean age of the study population was 52.1 with 95% CI [48.5 to 55.6] with a male: female ratio of 1.36:1 and 36.5% (n = 19) ofstudy cohort aged above 60 years. Among clinical presentations CKD (n = 23) was the main clinical presentation followed by AKI, Nephrotic syndrome, Nephritic syndrome and RPGN as the other presentations. Dialysis requirement was noted in 35% at initial presentation. Most common histiopathological presentation was Amyloidosis (n = 15) followed by Light chain deposition disease LCDD (n = 14), monoclonal non-amyloid deposition disease NADD (n = 6), Light chain proximal tubulopathy LCPT (n = 5), Proliferative glomerulonephritis with monoclonal immunoglobulin deposition disease PGNMIDD (n = 9) and others (n = 3). The patient survival at the time of analysis was 22.7% and death censored renal survival was 80%. Conclusion MGRS contributed to 1.27% of all the renal biopsies conducted at our institute during the study period. Because of its variable clincal presentation,one needs high degree of clinical suspicion for early diagnosis. MGRS unlike MGUS carries significant morbidity and mortality.

Galactose-deficient IgA1 is Involved in IgA Deposition in Renal Grafts Biopsied One Hour after Kidney Transplantation.

Objective Asymptomatic renal immunoglobulin A (IgA) deposition occurs in healthy subjects, but its etiologic role in disease is unclear. Galactose-deficient IgA1 (Gd-IgA1) is involved in the pathogenesis of IgA nephropathy. We investigated Gd-IgA1 deposition in transplanted kidneys that were considered healthy showing subclinical latent IgA deposition one hour after transplantation. Methods A total of 723 transplanted kidney specimens biopsied 1 h after kidney transplantation from 2009 to 2016 at Nagoya Red Cross Hospital were examined. A total of 81 cases of IgA deposition were extracted, and 41 were ultimately studied. Double immunofluorescence staining for Gd-IgA1 and IgA was conducted to investigate the role of Gd-IgA1 in subclinical IgA deposition. Results Light microscopy findings for the 41 cases indicated only minor glomerular abnormalities. Immunofluorescence analyses revealed that all cases were positive for IgA. C3, IgG, and IgM positivity rates were 78.0%, 7.3%, and 60.9%, respectively. All 41 cases were positive for Gd-IgA1, which merged with IgA deposition in immunofluorescence double staining. IgA disappeared in 26 of 40 cases (65.0%) 1 year after kidney transplantation. In contrast, IgA redeposition was observed in three cases. Conclusion Gd-IgA1 was demonstrated in all transplanted kidneys, with latent IgA deposition noted in otherwise healthy kidneys. Deposition of Gd-IgA1 might indicate the initial stage of IgA nephropathy; however, additional factors, such as IgG deposition, are required for the ultimate development of IgA nephropathy.

Localized Bullous Pemphigoid

A man in his 80s presented with a pruritic, focally ulcerated pink plaque with overlying blisters on the left lateral thigh (Figures 1 and 2). This had been the site of an excision 9 months earlier. Over time, pruritic vesicles and bullae developed at the surgical site. Punch biopsies showed a subepidermal bulla with extensive eosinophilic infiltrate on histopathology and linear deposition of C3 and immunoglobulin G (IgG) at the basement membrane zone on direct immunofluorescence, confirming the diagnosis of localized bullous pemphigoid (BP).Figure 2Close-up view of vesicles and bullae at the periphery.View Large Image Figure ViewerDownload Hi-res image Download (PPT) BP is a subepidermal autoimmune blistering disease caused by autoantibodies to hemidesmosome proteins BP180 (BP antigen 2) or BP230 (BP antigen 1). Classically, patients present with pruritic urticarial papules and plaques and tense vesicles and bullae. Diagnosis is made by examination of the tissue and direct immunofluorescence, which show a subepidermal accumulation of eosinophils and linear deposition of IgG and/or C3 in an n-serrated pattern along the basement membrane zone, respectively. Enzyme-linked immunosorbent assay (ELISA) for autoantibodies to the NC16a domain of BP180 and to BP230 is supportive, and anti-BP180-NC16a ELISA may aid in monitoring disease activity during treatment.1Schmidt E. Zillikens D. Pemphigoid diseases.Lancet. 2013; 381: 320-332https://doi.org/10.1016/S0140-6736(12)61140-4Abstract Full Text Full Text PDF PubMed Scopus (705) Google Scholar,2Feliciani C. Joly P. Jonkman M.F. et al.Management of bullous pemphigoid: the European Dermatology Forum consensus in collaboration with the European Academy of Dermatology and Venereology.Br J Dermatol. 2015; 172: 867-877https://doi.org/10.1111/bjd.13717Crossref PubMed Scopus (233) Google Scholar Most cases of BP are generalized. Rarely, it is localized, usually to sites of previous skin injury, surgery, radiation, or venous insufficiency.3Ständer S. Kasperkiewicz M. Thaçi D. et al.Prevalence and presumptive triggers of localized bullous pemphigoid.J Dermatol. 2021; 48: 1257-1261https://doi.org/10.1111/1346-8138.15912Crossref PubMed Scopus (4) Google Scholar Although the pathophysiology of localized BP is not well understood,4Danescu S. Chiorean R. Macovei V. Sitaru C. Baican A. Role of physical factors in the pathogenesis of bullous pemphigoid: case report series and a comprehensive review of the published work.J Dermatol. 2016; 43: 134-140https://doi.org/10.1111/1346-8138.13031Crossref PubMed Scopus (39) Google Scholar topical steroids are first-line therapy and are generally effective.2Feliciani C. Joly P. Jonkman M.F. et al.Management of bullous pemphigoid: the European Dermatology Forum consensus in collaboration with the European Academy of Dermatology and Venereology.Br J Dermatol. 2015; 172: 867-877https://doi.org/10.1111/bjd.13717Crossref PubMed Scopus (233) Google Scholar Our patient was treated with topical clobetasol 0.05% ointment twice daily for 3 weeks with excellent results, and subsequent use as needed to maintain clearance. The authors report no competing interests.

Evaluation of Autoantibody Binding to Cardiac Tissue in Multisystem Inflammatory Syndrome in Children and COVID-19 Vaccination–Induced Myocarditis

Cardiac dysfunction and myocarditis have emerged as serious complications of multisystem inflammatory syndrome in children (MIS-C) and vaccines against SARS-CoV-2. Understanding the role of autoantibodies in these conditions is essential for guiding MIS-C management and vaccination strategies in children. To investigate the presence of anticardiac autoantibodies in MIS-C or COVID-19 vaccine-induced myocarditis. This diagnostic study included children with acute MIS-C or acute vaccine myocarditis, adults with myocarditis or inflammatory cardiomyopathy, healthy children prior to the COVID-19 pandemic, and healthy COVID-19 vaccinated adults. Participants were recruited into research studies in the US, United Kingdom, and Austria starting January 2021. Immunoglobulin G (IgG), IgM, and IgA anticardiac autoantibodies were identified with immunofluorescence staining of left ventricular myocardial tissue from 2 human donors treated with sera from patients and controls. Secondary antibodies were fluorescein isothiocyanate-conjugated antihuman IgG, IgM, and IgA. Images were taken for detection of specific IgG, IgM, and IgA deposits and measurement of fluorescein isothiocyanate fluorescence intensity. Data were analyzed through March 10, 2023. IgG, IgM and IgA antibody binding to cardiac tissue. By cohort, there were a total of 10 children with MIS-C (median [IQR] age, 10 [13-14] years; 6 male), 10 with vaccine myocarditis (median age, 15 [14-16] years; 10 male), 8 adults with myocarditis or inflammatory cardiomyopathy (median age, 55 [46-63] years; 6 male), 10 healthy pediatric controls (median age, 8 [13-14] years; 5 male), and 10 healthy vaccinated adults (all older than 21 years, 5 male). No antibody binding above background was observed in human cardiac tissue treated with sera from pediatric patients with MIS-C or vaccine myocarditis. One of the 8 adult patients with myocarditis or cardiomyopathy had positive IgG staining with raised fluorescence intensity (median [IQR] intensity, 11 060 [10 223-11 858] AU). There were no significant differences in median fluorescence intensity in all other patient cohorts compared with controls for IgG (MIS-C, 6033 [5834-6756] AU; vaccine myocarditis, 6392 [5710-6836] AU; adult myocarditis or inflammatory cardiomyopathy, 5688 [5277-5990] AU; healthy pediatric controls, 6235 [5924-6708] AU; healthy vaccinated adults, 7000 [6423-7739] AU), IgM (MIS-C, 3354 [3110-4043] AU; vaccine myocarditis, 3843 [3288-4748] AU; healthy pediatric controls, 3436 [3313-4237] AU; healthy vaccinated adults, 3543 [2997-4607] AU) and IgA (MIS-C, 3559 [2788-4466] AU; vaccine myocarditis, 4389 [2393-4780] AU; healthy pediatric controls, 3436 [2425-4077] AU; healthy vaccinated adults, 4561 [3164-6309] AU). This etiological diagnostic study found no evidence of antibodies from MIS-C and COVID-19 vaccine myocarditis serum binding cardiac tissue, suggesting that the cardiac pathology in both conditions is unlikely to be driven by direct anticardiac antibody-mediated mechanisms.

Ocimum sanctum L water extract: In-situ green synthesis of zinc oxide nanoparticles for treatment of rheumatoid arthritis: Preclinical study

Background and objectiveRheumatoid arthritis is a chronic progressive autoimmune disorder, characterised by destruction of cartilage and under line bones. Though exact etiology of rheumatoid arthritis (RA) remains unknown. It is believed that alteration in control of cellular or molecular responses is involved in the chronic inflammation. Earlier in RA patients it was observed the circulating RA specific biomarkers and immunoglobulin deposits in the synovial joints. Zinc Oxide Nanoparticles (ZnO NPs) is used as an anti-inflammatory and anticancer agent, however there is nil/very less scientific data shows the anti-arthritic activity of green synthesis ZnO nanoparticles (Ocimum sanctum water extract in-situ synthesis of ZnO NPs having active compound Caffeic acid and Rosmerinic acid). Hence, the present activity was planned to assess the anti-arthritic activity of ZnO NPs in CIA rats. MethodsArthritis in rats were induced by subcutaneous injection of collagen type II (CII) (200 µl) at the base of tail on day 0 followed by booster dose on day 14. ZnO NPs were given (2 mg/kg b.wt./day) orally for 20 days. At the end of the study serum, joint homogenate was used to assess the level of biomarkers (RF, a-CCP, a-CII and CRP) and inflammatory mediators. In addition, m-RNA expression of various genes such as Nuclear factor-kB (NF-kB), inflammatory mediators like tumour necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2) etc. were assayed in joint tissue. Finally all these biochemical and molecular results were confirmed by microscopic study of joint tissue. ResultsZnO NPs, treated rats showed decrease in inflammation and clinical severity. This was related with decrease in the level of biomarkers (like RF, a-CCP and CRP), inflammatory mediators (TNF-α, COX-2) and activity of transcription factor NF-kB. All these findings were positively correlated with microscopic analysis of joint tissue that showed reduced inflammation and bone erosion in treated group. ConclusionThis study validates the anti-arthritic activity of ZnO NPs as it mitigates the arthritis related symptoms in CIA rats.

Immunoglobulin G deposition on proximal tubules and the tubular basement membrane in acute tubular injury complicated with focal segmental glomerulosclerosis (FSGS): A possible prediction tool for subclinical FSGS

Immunofluorescent deposition of immunoglobulin G (IgG) in the tubular basement membrane (TBM) has been evaluated in the diagnosis of various diseases; however, few studies have investigated the immunofluorescence of acute tubular injury (ATI). Herein, we attempted to clarify IgG expression in the proximal tubular epithelium and TBM in ATI due to various causes. Patients with ATI with nephrotic-range proteinuria, including focal segmental glomerulosclerosis (FSGS, n = 18) and minimal change nephrotic syndrome (MCNS, n = 8), ATI with ischemia (n = 6), and drug-induced ATI (n = 7), were enrolled. ATI was evaluated by light microscopy. CD15 and IgG double staining and IgG subclass staining were performed to evaluate immunoglobulin deposition in the proximal tubular epithelium and TBM. IgG deposition was identified in the proximal tubules only in the FSGS group. Furthermore, IgG deposition in the TBM was observed in the FSGS group showing severe ATI. IgG3 was predominantly deposited by the IgG subclass study. Our results indicate that IgG deposition in the proximal tubular epithelium and TBM suggests the leaking of IgG from the glomerular filtration barrier and its reabsorption by proximal tubules, which may predict disruption of the glomerular size barrier, including subclinical FSGS. FSGS with ATI should be included as a differential diagnosis when IgG deposition in TBM is observed.

Clinico-Pathogenic Similarities and Differences between Infection-Related Glomerulonephritis and C3 Glomerulopathy.

Recently, the comprehensive concept of "infection-related glomerulonephritis (IRGN)" has replaced that of postinfectious glomerulonephritis (PIGN) because of the diverse infection patterns, epidemiology, clinical features, and pathogenesis. In addition to evidence of infection, hypocomplementemia particularly depresses serum complement 3 (C3), with endocapillary proliferative and exudative GN developing into membranoproliferative glomerulonephritis (MPGN); also, C3-dominant or co-dominant glomerular immunofluorescence staining is central for diagnosing IRGN. Moreover, nephritis-associated plasmin receptor (NAPlr), originally isolated from the cytoplasmic fraction of group A Streptococci, is vital as an essential inducer of C3-dominant glomerular injury and is a key diagnostic biomarker for IRGN. Meanwhile, "C3 glomerulopathy (C3G)", also showing a histological pattern of MPGN due to acquired or genetic dysregulation of the complement alternative pathway (AP), mimics C3-dominant IRGN. Initially, C3G was characterized by intensive "isolated C3" deposition on glomeruli. However, updated definitions allow for glomerular deposition of other complement factors or immunoglobulins if C3 positivity is dominant and at least two orders of magnitude greater than any other immunoreactant, which makes it challenging to quickly distinguish pathomorphological findings between IRGN and C3G. As for NAPlr, it was demonstrated to induce complement AP activation directly in vitro, and it aggravates glomerular injury in the development of IRGN. A recent report identified anti-factor B autoantibodies as a contributing factor for complement AP activation in pediatric patients with PIGN. Moreover, C3G with glomerular NAPlr deposition without evidence of infection was reported. Taken together, the clinico-pathogenic features of IRGN overlap considerably with those of C3G. In this review, similarities and differences between the two diseases are highlighted.

Histopathologic features predictive of perivascular deposition of IgA on direct immunofluorescence in cases of leukocytoclastic vasculitis: A retrospective study of 112 specimens.

IgA vasculitis is a small-vessel vasculitis subtype with increased risk of systemic involvement. We aimed to investigate if any light-microscopic features can predict the presence of perivascular granular IgA deposits on direct immunofluorescence (DIF) microscopy. We performed a retrospective search of cutaneous pathology reports from our internal and consultation practice (January 1, 2010-October 5, 2021) with a diagnosis of leukocytoclastic vasculitis and accompanying DIF. A blinded dermatopathologist reviewed standard microscopy slides for predetermined histopathological features. Fifty-six biopsies (48 patients) and 56 biopsies (42 patients) met inclusion criteria for IgA+ and IgA-, respectively. The presence of eosinophils and mid and deep dermal inflammation were statistically more associated with IgA- (41/56 [73.2%] and 31/56 [55.4%], respectively) than IgA+ cases (28/56 [50.0%] and 14/56 [25.0%]; p = 0.049 and 0.006, respectively, chi-squared test). Other microscopic criteria recorded were not significantly different between the two groups (p > 0.05, chi-squared and Fisher's exact tests). In this retrospective study of 112 cases, we found that while the absence of eosinophils and absence of mid- and deep inflammation were correlated with increased likelihood of IgA perivascular deposition on DIF, no other histopathological features on light microscopy tested could reliably predict the presence of IgA perivascular deposition on DIF. Therefore, DIF remains a necessary component for the accurate diagnosis of cutaneous IgA vasculitis.

Povetacicept, an Enhanced Dual APRIL/BAFF Antagonist That Modulates B Lymphocytes and Pathogenic Autoantibodies for the Treatment of Lupus and Other B Cell-Related Autoimmune Diseases.

Dysregulated APRIL/BAFF signaling is implicated in the pathogenesis of multiple autoimmune diseases, including systemic lupus erythematosus and lupus nephritis. We undertook this study to develop and evaluate a high-affinity APRIL/BAFF antagonist to overcome the clinical limitations of existing B cell inhibitors. A variant of TACI-Fc generated by directed evolution showed enhanced binding for both APRIL and BAFF and was designated povetacicept (ALPN-303). Povetacicept was compared to wild-type (WT) TACI-Fc and related molecules in vitro and in vivo. Povetacicept inhibited APRIL and BAFF more effectively than all evaluated forms of WT TACI-Fc and selective APRIL and BAFF inhibitors in cell-based reporter assays and primary human B cell assays, mediating potent suppression of B cell proliferation, differentiation, and immunoglobulin (Ig) secretion. In mouse immunization models, povetacicept significantly reduced serum immunoglobulin titers and antibody-secreting cells more effectively than anti-CD20 monoclonal antibodies, WT TACI-Fc, or APRIL and BAFF inhibitors. In the NZB × NZW mouse lupus nephritis model, povetacicept significantly enhanced survival and suppressed proteinuria, anti-double-stranded DNA antibody titers, blood urea nitrogen, glomerulonephritis, and renal immunoglobulin deposition. In the bm12 mouse lupus model, povetacicept significantly reduced splenic plasmablasts, follicular helper T cells, and germinal center B cells. In non-human primates, povetacicept was well tolerated, exhibited high serum exposure, and significantly decreased serum IgM, IgA, and IgG levels after a single dose. Enhanced APRIL and BAFF inhibition by povetacicept led to greater inhibition of B cell populations critical for autoantibody production compared to WT TACI-Fc and CD20-, APRIL-, or BAFF-selective inhibitors. Potent, dual inhibition by povetacicept has the potential to significantly improve clinical outcomes in autoantibody-related autoimmune diseases.

Current understanding of IgA antibodies in the pathogenesis of IgA nephropathy.

Immunoglobulin A (IgA) is the most abundant isotype of antibodies, provides a first line of defense at mucosal surfaces against pathogens, and thereby contributes to mucosal homeostasis. IgA is generally considered as a non-inflammatory antibody because of its main function, neutralizing pathogenic virus or bacteria. Meanwhile, IgA can induce IgA-mediated diseases, such as IgA nephropathy (IgAN) and IgA vasculitis. IgAN is characterized by the deposition of IgA and complement C3, often with IgG and/or IgM, in the glomerular mesangial region, followed by mesangial cell proliferation and excessive synthesis of extracellular matrix in glomeruli. Almost half a century has passed since the first report of patients with IgAN; it remains debatable about the mechanism how IgA antibodies selectively bind to mesangial region-a hallmark of IgAN-and cause glomerular injuries in IgAN. Previous lectin- and mass-spectrometry-based analysis have revealed that IgAN patients showed elevated serum level of undergalactosylated IgA1 in O-linked glycans of its hinge region, called galactose-deficient IgA1 (Gd-IgA1). Thereafter, numerous studies have confirmed that the glomerular IgA from IgAN patients are enriched with Gd-IgA1; thus, the first hit of the current pathogenesis of IgAN has been considered to increase circulating levels of Gd-IgA1. Recent studies, however, demonstrated that this aberrant glycosylation alone is not sufficient to disease onset and progression, suggesting that several additional factors are required for the selective deposition of IgA in the mesangial region and induce nephritis. Herein, we discuss the current understanding of the characteristics of pathogenic IgA and its mechanism of inducing inflammation in IgAN.

Utility of anti-immunoglobulin IgA, IgG, IgM, Kappa, Lambda - FITC (conjugate) cocktail in routine renal pathology practice

BackgroundImmunofluorescence studies on frozen sections are an essential component in the evaluation of renal biopsies. The basic panel in most centres constitutes IgG, IgA, IgM, C3c, C1q, Kappa and Lambda light chain antibody testing. The purpose of this panel is to detect immunoglobulin or complement deposits and further subclassify the disease based on the location, intensity and pattern of immunoglobulin and complement staining. However, there are a substantial proportion of nephropathies that do not show any obvious immune-deposits on immunofluorescence. We currently, do not have any evidence-based alternative immunofluorescence panel to rule out these conditions. This study aims to evaluate the utility of anti-immunoglobulin IgA, IgG, IgM, Kappa, Lambda - FITC cocktail immunofluorescence on renal biopsy frozen sections with emphasis on its role as a primary screening panel in conjunction with C3c and C1q.MethodsAnti-immunoglobulin IgA, IgG, IgM, Kappa, Lambda light chain - FITC cocktail immunofluorescence was performed on 593 consecutive native renal biopsies along with the routine panel comprising of the individual FITC labelled IgG, IgA, IgM, C3c, C1q, Kappa and Lambda light chain immunofluorescence stains.ResultsIn 235 (39.6%) cases immune deposits (immune-complex mediated and monoclonal gammopathy-related) were present and the rest 354 (59.7%) cases were negative for immunoglobulin or complement deposits. Overall, the sensitivity, specificity, positive predictive value and negative predictive values of anti-immunoglobulin IgA, IgG, IgM, Kappa and Lambda - FITC cocktail in distinguishing immune-complex/immunoglobulin-mediated glomerulopathies from non-immune complex/immunoglobulin-mediated glomerulopathies were 100% each.ConclusionAnti-immunoglobulin IgA, IgG, IgM, Kappa and Lambda - FITC cocktail when used in conjunction with C3c and C1q, can be an effective first line investigation in all native renal biopsies. Further, testing with the individual FITC labelled IgG, IgA, IgM, Kappa and Lambda light chain immunofluorescence can be performed, depending on the initial screening as described above. Overall, this algorithmic approach can save valuable resources.

Subclinical C1q Nephropathy Combined with Possible Donor-Derived IgA Deposition in a 1-Year Kidney Allograft Biopsy: A Case Report

Few previous studies have reported immune-complex nephropathy that has not been classified as a specific phenotype in kidney allografts. We report a case of a de novo subclinical "full-house" pattern of deposition in a pediatric transplantation recipient with possible donor-derived IgA deposition. A five-year-old boy underwent living kidney transplantation due to congenital kidney and urinary tract anomalies. A one-hour implantation biopsy revealed IgA deposition. A four-month protocol biopsy finding showed less intense IgA deposition, in contrast with the one-hour biopsy, and trace para-mesangial deposits. A one-year protocol biopsy demonstrated a full-house deposition pattern and massive electron-dense deposits with minor glomerular changes. At the time of the one-year biopsy, kidney function was stable, with no urinalysis abnormalities. No evidence of systemic lupus erythematosus was observed in clinical and serologic examinations. Mesangial IgG, IgM, C3, and C1q deposition was codominant, and IgA deposition was weaker. We diagnosed this case as C1q nephropathy combined with remaining donor-derived IgA deposition. Few studies have reported C1q nephropathy in kidney allograft; further accumulation of cases is required. To distinguish between donor-derived and de novo glomerular lesions, it is important to assess the serial histologic findings of immunofluorescence and electron microscopy. Here, we report a rare case of subclinical C1q nephropathy with possible donor-derived IgA nephropathy.