Effect of antinuclear antibody positivity on antineutrophil cytoplasmic antibody results by indirect immunofluorescence assay.

BACKGROUND: The indirect immunofluorescence assay (IIFA) utilizing antineutrophil cytoplasmic antibodies (ANCA) is widely used as a diagnostic test for autoimmune vasculitis. The presence of antinuclear antibodies (ANA) might lead to a misleading interpretation of ANCA. This study aims to explore the impact of the presence of ANA on the interpretation of ANCA. METHODS: This retrospective research examined samples negative for antiMPO and antiPR3 ANCA by IIFA and explored correlations between the ANA-IIFA results and the ANCA interpretation frequencies. Our analysis involved the use of suitable statistical methods, including Chi-square and kappa statistics. RESULTS: Up to 75.2% of the ANCA-IIFA-positive samples exhibited a positive p-ANCA pattern when using the ethanol-fixed substrate, with c-ANCA positivity at 24.8%. In the ANA-IIFA-positive samples, ~77.3% displayed p-ANCA patterns on ethanol-fixed substrates. A comparison between the ANA-IIFA titers and the p-ANCA results revealed that p-ANCA positivity was notably more common in samples with higher titers, and this correlation was found to be statistically significant. CONCLUSION: Positive ANA results by IIFA tests are linked to a higher incidence of p-ANCA interpretation, particularly in cases with higher titer patterns. This insight aids laboratories in establishing effective workflows to investigate potential p-ANCA interference.

Prevalence of a large panel of systemic autoantibodies in the Bavarian adult population.

Objective: Autoimmune diseases commonly feature the presence of specific humoral autoantibodies. However, the prevalence of a large panel of systemic autoantibodies has never been assessed in the general population. We, therefore, described the prevalence of about 50 humoral systemic autoantibodies in a sample of the general Bavarian adult population. Methods: Non-fasting venous serum samples from 331 participants were analyzed for 7 autoantibody screening tests (nuclear, cytoplasmic, and mitotic ANA, ANCA, cANCA and pANCA, anti-ENA autoantibodies) and 44 different monospecific humoral non-organ specific/systemic autoantibodies using indirect immunofluorescence tests, ELISAs, and line blots. In order to assess associations between sex, age, BMI, education level, smoking status and the presence of systemic autoantibodies, logistic regression analyses were conducted. Results: At least one screening test was positive in 29.9% of the participants, and 42.3% of the participants were seropositive for at least one monospecific autoantibody. The most frequently found monospecific autoantibodies were rheumatoid factor (35.6%), ß2-glycoprotein 1 IgM (4.8%), and cardiolipin IgG (1.8%). Only few associations between sex, age, BMI, education, smoking status and autoantibody frequencies were observed. Conclusion: Systemic autoantibodies are common in the general Bavarian population, and largely independent of sex, age, BMI, education, or smoking status. The study results may give orientation to clinicians about the occurrence of autoantibodies in the population, not (yet) associated with clinical symptoms.

Immunohistochemical analysis of myeloperoxidase expression in cutaneous leucocytoclastic vasculitis.

Myeloperoxidase (MPO) is a pro-oxidant enzyme mainly found in the azurophilic granules of neutrophils. It not only displays a key role in the intracellular microbial killing process but also contributes to the extracellular clearance of several pathogens. This study aimed to detect MPO in cutaneous leukocytoclastic vasculitis (LCV) using immunohistochemistry. We retrospectively collected 22 confirmed cases of skin LCV diagnosed in our pathology department over 11 years (2012-2023). Immunohistochemistry was performed using anti-myeloperoxidase antibody (Leica clone 59A5) on the LeicaBond MAX automated system, following manufacturer's instructions. Two pathologists assessed immunohistochemical staining, scoring intensity as weak (+), moderate (++), or strong (+++). Patients' mean age was 56.9 years, with a male-to-female ratio of 1.18. Pathologically, vasculitis involved small blood vessels in all cases. Immunohistochemical analysis showed granular positive MPO staining in 59.1% of cases. Staining intensity was weak in 46.15%, moderate in 46.15%, and strong in 7.69%. Staining was patchy in 84.62% and diffuse in 15.38% of cases. MPO expression, detected in 59.1% of cutaneous LCV tissues, exhibited a patchy and peri-vascular distribution. It holds potential as a diagnostic marker for patients with early or minor histological changes.

Small fiber neuropathy associated with ANCA positivity: a case series and brief literature review.

INTRODUCTION: Small fiber neuropathy [SFN] is a common peripheral neurologic disorder with a vast array of implicated etiologies. It has previously been proposed that some forms of immune-mediated small fiber neuropathy are driven by vasculitis, though antinuclear cytoplasmic antibodies [ANCA] antibodies have not commonly been reported in association with SFN, thus far. We present this case series to discuss the observation of a possible novel association between ANCA and SFN. METHODS: This is a retrospective case series of 6 patients with SFN and ANCA positivity, with and without systemic manifestations. Patients included were diagnosed with SFN by skin biopsy or autonomic function testing and were seropositive for ANCA by ELISA. RESULTS: Six patients are outlined, including 4 females and 2 males. Antigen specific antibodies were MPO alone in 4 cases, PR3 alone in 1 case and both MPO and PR3 in 1 case. Systemic vasculitis was noted in 2 patients. Five patients received immunosuppression. Three patients experienced partial improvement, while symptoms stabilized in 3 patients. DISCUSSION: This is the first series of patients with suspected immune-mediated SFN and ANCA antibody positivity, raising the possibility of ANCA mediated isolated SFN. This is in contradistinction to the more typical ANCA-mediated peripheral neuropathy manifestations of mononeuropathy multiplex or axonal sensorimotor neuropathy. We cannot unequivocally prove ANCA-associated vasculitis [AAV] causality in these cases; however, the stabilization in SFN symptomatology and associated improvement in ANCA antibody titer, after AAV treatment, may be indicative of an association.

Diagnostic significance of antineutrophil cytoplasmic antibody (ANCA) titres: a retrospective case-control study.

OBJECTIVES: To investigate the reliability of elevated titres of antineutrophil cytoplasmic antibody (ANCA) and to identify a cut-off titre in discriminating between ANCA-associated vasculitides (AAV) and its mimickers. METHODS: This retrospective observational single-centre study included patients over 18 years with positive myeloperoxidase (MPO)-ANCA and/or proteinase 3 (PR3)-ANCA immunoassays over an 8-year period (January 2010 to December 2018), via their electronic medical files. Patients were classified according to the 2022 ACR/EULAR criteria and alternative diagnoses categorised either as non-AAV autoimmune disorders (ANCA-AI) or disorders without autoimmune features (ANCA-O). Findings from the AAV group were compared with those of ANCA-AI and ANCA-O groups and followed by a multivariate logistic stepwise regression analysis of features associated with AAV. RESULTS: 288 ANCA-positive patients of which 49 had AAV were altogether included. There was no difference between patients between the ANCA-AI (n=99) and the ANCA-O (n=140) groups. The AUC for titres discriminating AAV from mimickers was 0.83 (95% CI, 0.79 to 0.87). The best threshold titre, irrespective of PR3-ANCA or MPO-ANCA, was 65 U/mL with a negative predictive value of 0.98 (95% CI, 0.95 to 1.00). On multivariate analysis, an ANCA titre ≥65 U/mL was independently associated with AAV with an OR of 34.21 (95% CI 9.08 to 129.81; p<0.001). Other risk factors were: pulmonary fibrosis (OR, 11.55 (95% CI, 3.87 to 34.47, p<0.001)), typical ear nose and throat involvement (OR, 5.67 (95% CI, 1.64 to 19.67); p=0.006) and proteinuria (OR, 6.56 (95% CI, 2.56 to 16.81; p<0.001)). CONCLUSION: High PR3/MPO-ANCA titres can help to discriminate between AAV and their mimickers in patients presenting with small-calibre vasculitides, with a threshold titre of 65 U/mL and above.

Digital Spatial Profiling of Glomerular Gene Expression in Pauci-Immune Focal Necrotizing Glomerulonephritis.

Pauci-immune focal necrotizing glomerulonephritis (piFNGN) involves asynchronous onset and progression of injurious lesions in biopsies. Pathologists can describe this heterogeneity within a biopsy, but translating the information into prognostic or expression analyses is challenging. Understanding the underlying molecular processes could improve treatment; however, bulk or single-cell transcriptomic analyses of dissociated tissue disregard the heterogeneity of glomerular injury. We characterize protein and mRNA expression of individual glomeruli in 20 biopsies from 18 patients with antineutrophil cytoplasmic antibody-associated piFNGN using the NanoString digital spatial profiling (DSP) platform. For this purpose, circular annotations of glomeruli were analyzed using protein, immuno-oncology RNA, and Cancer Transcriptome Atlas panels (n=120, 72, and 48 glomeruli, respectively). Histologic evaluation of glomerular patterns of injury was performed in adjacent serial sections. Expression data were processed by log2 transformation, quantile normalization, and batch adjustment. DSP revealed distinct but overlapping gene expression profiles relating to the morphological evolution of injurious lesions, including dynamic expression of various immune checkpoint regulators. Enrichment analysis indicated deregulated pathways that underline known and highlight novel potential mechanisms of disease. Moreover, by capturing individual glomeruli, DSP describes heterogeneity between and within biopsies. We demonstrate the benefit of spatial profiling for characterization of heterogeneous glomerular injury, indicating novel molecular correlates of glomerular injury in piFNGN.

[Evaluation of diagnostic efficacy of digital liquid chip method for detection of specific antineutrophil cytoplasmic antibodies].

To explore the clinical diagnostic efficacy of antineutrophil cytoplasmic antibody associated vasculitis (AAV) by comparing the consistency and coincidence rate of serum anti-myeloperoxidase (MPO) antibody and anti-protease 3 (PR3) antibody detected by digital liquid chip method (DLCM) and enzyme-linked immunosorbent assay (ELISA). To provide reference for the selection of detection methods of anti-MPO antibody and anti-PR3 antibody in clinical laboratory. This study is a cross-sectional study, a total of 307 cases of antineutrophil cytoplasmic antibodies were detected in the Department of Clinical Immunology, West China Hospital of Sichuan University from January to March 2021. The serum samples and related clinical information were collected. At the same time, the levels of anti-MPO antibody and anti-PR3 antibody in serum samples were detected by ELISA and DLCM, indirect immunofluorescence (IIF) was used to re-test the differential samples between the two methods. SPSS 26.0 was used to analyze the test results, Cohen's kappa coefficient analysis was used to compare the consistency of the two methods, and paired chi-square test was used to compare the sensitivity and specificity of the two methods to AAV. The results showed that the positive cases of anti-MPO antibody detected by ELISA and DLCM were 63 and 44, and the negative cases were 244 and 263; the positive cases of anti-PR3 antibody detected by ELISA and DLCM were 34 and 28, and the negative cases were 273 and 279. The results of anti-MPO antibody and anti-PR3 antibody detected by the two methods had good consistency and coincidence rate, in which the total coincidence rate of anti-MPO antibody was 92.51%, the positive coincidence rate was 66.67%, and the negative coincidence rate was 99.18%. The results of consistency analysis showed that kappa=0.741 had well consistency. The total coincidence rate of anti-PR3 antibody is 96.74%, the positive coincidence rate is 76.47%, and the negative coincidence rate is 99.27%. The consistency analysis results show that kappa=0.821 had strong consistency. The results of IIF re-test of differential samples showed that the coincidence rate between DLCM and IIF was higher. The results of comparative analysis of anti-MPO antibody and anti-PR3 antibody showed that the specificity of DLCM was better than that of ELISA, and its sensitivity was lower than that of ELISA. In conclusion, the results of anti-MPO antibody and anti-PR3 antibody detected by DLCM were consistent with those of ELISA. In the combined detection of anti-MPO antibody and anti-PR3 antibody, the specificity of DLCM is better than that of ELISA.

High levels of platelet-to-lymphocyte ratio may predict reduced risk of end stage of renal disease in Chinese patients with MPO-ANCA associated vasculitis. / 血小板/淋巴细胞比率比值升高可能预示中国MPO-ANCAç›¸å ³æ€§è¡€ç®¡ç‚Žæ‚£è€ è¿›å±•è‡³ç»ˆæœ«æœŸè‚¾ç— çš„é£Žé™©è¾ƒä½Ž.

OBJECTIVES: Platelet-to-lymphocyte ratio (PLR) has recently been investigated as a new inflammatory marker in many inflammatory diseases, including systemic lupus erythematosus and immunoglobulin A vasculitis. However, there were very few reports regarding the clinical role of PLR in patients with anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis. This study was thus undertaken to investigate the relationship between inflammatory response and disease activity in Chinese patients with myeloperoxidase-anti-neutrophil cytoplasmic antibody (MPO-ANCA) associated vasculitis. Furthermore, we evaluated whether PLR predicts the progression of end stage of renal disease (ESRD) and all-cause mortality. METHODS: The clinical, laboratory and pathological data, and the outcomes of MPO-ANCA associated vasculitis patients were collected. The Spearman correlation coefficient was computed to examine the association between 2 continuous variables. Cox regression analysis was used to estimate the association between PLR and ESRD or all-cause mortality. RESULTS: A total of 190 consecutive patients with MPO-ANCA associated vasculitis were included in this study. Baseline PLR was positively correlated with CRP (r=0.333, P<0.001) and ESR (r=0.218, P=0.003). PLR had no obvious correlation with Birmingham Vasculitis Activity Score (BVAS). Patients having PLR≥330 exhibited better cumulative renal survival rates than those having PLR<330 (P=0.017). However, there was no significant difference in the cumulative patient survival rates between patients with PLR≥330 and those with PLR<330 at diagnosis (P>0.05). In multivariate analysis, PLR is associated with the decreased risk of ESRD (P=0.038, HR=0.518, 95% CI 0.278 to 0.963). We did not find an association between PLR with all-cause mortality using multivariate analysis (HR=1.081, 95% CI 0.591 to 1.976, P=0.801). CONCLUSIONS: PLR is positively correlated with CRP and ESR. Furthermore, PLR may independently predict the risk of ESRD.

Acute glomerulonephritis.

Glomerulonephritis is a heterogeneous group of disorders that present with a combination of haematuria, proteinuria, hypertension, and reduction in kidney function to a variable degree. Acute presentation with full blown nephritic syndrome or rapidly progressive glomerulonephritis is uncommon and is mainly restricted to patients with post-infectious glomerulonephritis, anti-neutrophil cytoplasmic antibodies-associated vasculitis, and anti-glomerular basement membrane disease. Most frequently, patients present with asymptomatic haematuria and proteinuria with or without reduced kidney function. All glomerulonephritis disorders can show periods of exacerbation, but disease flairs characteristically occur in patients with IgA nephropathy or C3 glomerulopathy. The gold standard for the diagnosis of a glomerulonephritis is a kidney biopsy, with a hallmark glomerular inflammation that translates into various histopathological patterns depending on the location and severity of the glomerular injury. Traditionally, glomerulonephritis was classified on the basis of the different histopathological patterns of injury. In the last few years, substantial progress has been made in unravelling the underlying causes and pathogenetic mechanisms of glomerulonephritis and a causal approach to the classification of glomerulonephritis is now favoured over a pattern-based approach. As such, glomerulonephritis can be broadly classified as immune-complex glomerulonephritis (including infection-related glomerulonephritis, IgA nephropathy, lupus nephritis, and cryoglobulinaemic glomerulonephritis), anti-neutrophil cytoplasmic antibodies-associated (pauci-immune) glomerulonephritis, anti-glomerular basement membrane glomerulonephritis, C3 glomerulopathy, and monoclonal immunoglobulin-associated glomerulonephritis. We provide an overview of the clinical presentation, pathology, and the current therapeutic approach of the main representative disorders in the spectrum of glomerulonephritis.

Assessment of Renal Risk Score and Histopathological Classification for Prediction of End-Stage Kidney Disease and Factors Associated With Change in eGFR After ANCA-Glomerulonephritis Diagnosis.

Introduction: The "Renal Risk Score" (RRS) and the histopathological classification have been proposed to predict the risk of end-stage kidney disease (ESKD) in ANCA-associated glomerulonephritis (ANCA-GN). Besides, factors associated with kidney function recovery after ANCA-GN onset remain to be more extensively studied. In the present study, we analyzed the value of the RRS and of the histopathological classification for ESKD prediction. Next, we analyzed factors associated with eGFR change within the first 2 years following ANCA-GN diagnosis. Materials and Methods: We included patients from the Maine-Anjou ANCA-associated vasculitis registry with at least 6 months of follow-up. The values of ANCA-GN, histopathological classification, and RRS, and the factors associated with eGFR variations between ANCA-GN diagnosis and 2 years of follow-up were assessed. Results: The predictive values of the histopathological classification and RRS were analyzed in 123 patients. After a median follow-up of 42 months, 33.3% patients developed ESKD. The predictive value of RRS for ESKD was greater than that of the histopathological classification. Determinants of eGFR variation were assessed in 80/123 patients with complete eGFR measurement. The median eGFR increased from ANCA-GN diagnosis to month 6 and stabilized thereafter. The only factor associated with eGFR variation in our study was eGFR at ANCA-GN diagnosis, with higher eGFR at diagnosis being associated with eGFR loss (p<0.001). Conclusion: The RRS has a better predictive value for ESKD than the histopathological classification. The main determinant of eGFR variation at 2 years was eGFR at ANCA-GN diagnosis. Thus, this study suggests that eGFR recovery is poorly predicted by histological damage at ANCA-GN diagnosis.

Digital Spatial Profiling of Individual Glomeruli From Patients With Anti-Neutrophil Cytoplasmic Autoantibody-Associated Glomerulonephritis.

We previously showed that the rupture of Bowman's capsule (BC) promotes the progression of crescentic glomerulonephritis by enhancing the entry of CD8+ T cells into the glomeruli. In the present study, we utilized digital spatial profiling to simultaneously profile the altered abundances of the messenger RNA (mRNA) transcripts and proteins in the glomerular and periglomerular areas of four biopsy samples of anti-neutrophil cytoplasmic autoantibody-associated glomerulonephritis (ANCA-GN) and two biopsy specimens of minimal change disease (MCD) controls. The paraffin-embedded biopsy samples were stained with collagen IV, CD45, and SYTO 13 to distinguish the glomeruli with periglomerular infiltration but intact BC, with focal BC rupture, and with extensive rupture of BC and glomeruli without crescent formation and leukocytic infiltration in ANCA-GN. By assessing multiple discrete glomerular areas, we found that the transcript expression levels of the secreted phosphoprotein-1 and its receptor CD44 were upregulated significantly in the glomeruli with more severe ruptures of BC, and their expression levels correlated positively with the fibrotic markers. We also found that both alternative and classic complement pathways were activated in the glomeruli from patients with ANCA-GN. Furthermore, M1 macrophages were involved mostly in the early stage of BC rupture, while M2 macrophages were involved in the late stage and may contribute to the fibrosis process of the crescents. Finally, loss of glomerular cells in ANCA-GN was likely mediated by apoptosis. Our results show that digital spatial profiling allows the comparative analysis of the mRNA and protein profiles in individual glomeruli affected differently by the disease process and the identification of potential novel mechanisms in ANCA-GN.

Lymphopaenia at diagnosis of anti-neutrophil cytoplasmic antibody-vasculitis with renal involvement is correlated with severity and renal prognosis.

BACKGROUND: Lymphopaenia is commonly observed in autoimmune diseases, where it has been associated with disease activity or prognosis. However, in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) only a few small-scale studies have been targeted towards this issue. Research has not yet focused on AAV with renal involvement (AAV-RI). Thus the aim of this study was to analyse the association between lymphocyte counts and outcomes in a large cohort of AAV-RI patients. METHODS: We used the Maine-Anjou AAV registry that retrospectively gathers data on consecutive patients affected by AAV in four French nephrology centres, recorded since January 2000. We analysed clinical, biological and histological data at diagnosis of AAV-RI. Risk factors for end-stage kidney disease (ESKD) were analysed. Event-free survival was also assessed. RESULTS: Among the 145 patients included in the study, those with lymphopaenia at diagnosis had a lower renal function at baseline [estimated glomerular filtration rate (eGFR) 13 versus 26 mL/min; P = 0.002] and were more likely to require kidney replacement therapy (51% versus 25%; P = 0.003). Lymphopaenia was correlated with histological lesions and especially with the percentage of sclerotic glomeruli (P = 0.0027). ESKD-free survival was lower in lymphopaenic patients (P < 0.0001). In multivariate Cox analysis, lymphopaenia was an independent risk factor for ESKD [hazard ratio 4.47 (95% confidence interval 2.06-9.72), P < 0.001]. CONCLUSIONS: Lymphopaenia correlates with the severity of AAV glomerulonephritis at diagnosis and predicts poor renal outcome. In this view, lymphopaenia could be used as a simple and cost-effective biomarker to assess renal prognosis at AAV-RI diagnosis.

High levels of platelet-to-lymphocyte ratio may predict reduced risk of end stage of renal disease in Chinese patients with MPO-ANCA associated vasculitis / 中南大学学报(医学版)

OBJECTIVES@#Platelet-to-lymphocyte ratio (PLR) has recently been investigated as a new inflammatory marker in many inflammatory diseases, including systemic lupus erythematosus and immunoglobulin A vasculitis. However, there were very few reports regarding the clinical role of PLR in patients with anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis. This study was thus undertaken to investigate the relationship between inflammatory response and disease activity in Chinese patients with myeloperoxidase-anti-neutrophil cytoplasmic antibody (MPO-ANCA) associated vasculitis. Furthermore, we evaluated whether PLR predicts the progression of end stage of renal disease (ESRD) and all-cause mortality.@*METHODS@#The clinical, laboratory and pathological data, and the outcomes of MPO-ANCA associated vasculitis patients were collected. The Spearman correlation coefficient was computed to examine the association between 2 continuous variables. Cox regression analysis was used to estimate the association between PLR and ESRD or all-cause mortality.@*RESULTS@#A total of 190 consecutive patients with MPO-ANCA associated vasculitis were included in this study. Baseline PLR was positively correlated with CRP (r=0.333, P<0.001) and ESR (r=0.218, P=0.003). PLR had no obvious correlation with Birmingham Vasculitis Activity Score (BVAS). Patients having PLR≥330 exhibited better cumulative renal survival rates than those having PLR<330 (P=0.017). However, there was no significant difference in the cumulative patient survival rates between patients with PLR≥330 and those with PLR<330 at diagnosis (P>0.05). In multivariate analysis, PLR is associated with the decreased risk of ESRD (P=0.038, HR=0.518, 95% CI 0.278 to 0.963). We did not find an association between PLR with all-cause mortality using multivariate analysis (HR=1.081, 95% CI 0.591 to 1.976, P=0.801).@*CONCLUSIONS@#PLR is positively correlated with CRP and ESR. Furthermore, PLR may independently predict the risk of ESRD.

Neutrophil fixation protocols suitable for substrates to detect anti-neutrophil cytoplasmic antibodies by indirect immunofluorescence.

Anti-neutrophil cytoplasmic antibodies (ANCAs) are autoantibodies that recognize neutrophil cytoplasmic antigens. The major ANCA antigens are myeloperoxidase and proteinase 3. Necrotizing small vessel vasculitis accompanied by ANCA production is called ANCA-associated vasculitis (AAV). In addition to AAV, ANCA is sometimes produced in patients with connective tissue diseases, such as systemic lupus erythematosus, and inflammatory bowel diseases. Indirect immunofluorescence (IIF) and enzyme immunoassay (EIA) have been used to detect ANCAs. Recently, the accuracy of EIA has improved and it has become the gold standard for ANCA detection. However, IIF does not lose its role in ANCA detection because EIA cannot detect ANCAs that recognize antigens other than those coated on the plate. For IIF, neutrophil substrates prepared with two different fixations, namely, ethanol fixation and formalin fixation, are used. There is a recommended protocol for ethanol fixation but not for formalin fixation. This study prepared neutrophil substrates according to the recommended protocol for ethanol fixation and protocols in the literature and original protocols for formalin fixation and then examined ANCA specificity and how storage period would influence the number of cells, antigen distribution, and antigenicity of the substrates. As a result, the number of cells and antigen distribution did not change after storage for up to 2 months regardless of fixation protocols, whereas a time-dependent decline in ANCA antigenicity and a fixation protocol-dependent difference in ANCA specificity were observed. How neutrophils are fixed on the glass slide needs to be checked upon evaluation of ANCAs by IIF.

Comprehensive Analysis of Sex Differences at Disease Manifestation in ANCA-Associated Glomerulonephritis.

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a small vessel vasculitis affecting multiple organ systems, including the kidney. Besides investigations focusing on renal outcomes, sex differences associated with distinct clinical and histopathological findings in ANCA glomerulonephritis (GN) have not been systematically investigated. Therefore, we here aimed to systematically analyze sex differences in patients with AAV and biopsy-proven ANCA GN. We provide a comprehensive analysis of 53 kidney biopsies with ANCA GN retrospectively included between 2015 and 2020 and identified specific sex differences in ANCA GN concerning laboratory parameters and systematic scoring of renal histopathology glomerular and tubulointerstitial lesions, and extrarenal manifestations of AAV. We did not observe any correlation between sex and short-term clinical AAV course or disease severity by comparing general AAV parameters. AAV manifestations in females occurred at an older age with more joint involvement. Regarding histopathological findings, we, again, observed no sex difference among ANCA GN classification, but a significant correlation between females and distinct histopathological findings with less tubulointerstitial inflammation and vasculitis of peritubular capillaries. Finally, we here identified fewer associations between clusters of clinical, laboratory parameters, and histopathological findings in females as compared to males. These findings are of great relevance and further improve our understanding of sex differences in the pathogenesis of ANCA GN. While future studies about specific sex differences and conclusions in these clusters are crucial, our observations further support that sex differences are relevant, affect distinct parameters, and influence clinical, laboratory parameters, and histopathological findings in AAV, particularly ANCA GN.

ANCA-Negative Churg-Strauss Syndrome Presenting as Bilateral Central Retinal Artery Occlusion: A Case Report

A 42-year-old man with undiagnosed Churg-Strauss syndrome (CSS) developed bilateral central retinal artery occlusion (CRAO). His medical history included bronchial asthma and irregular prednisolone usage but no atherosclerotic risk factors. At presentation, visual acuity (VA) was hand motion in the right eye and counting fingers in left eye. On fundoscopy, retinal whitening and a cherry red spot were observed in the right eye, while the fundus was normal in the left eye. After eyeball massage and systemic intraocular pressure lowering agents, his VA improved. On day 5 of treatment, he experienced right limb weakness and purpura on his right foot, and electromyography revealed mononeuritis multiplex. Laboratory tests indicated eosinophilia (52%). Based on the presence of hypereosinophilia, bronchial asthma, mononeuritis multiplex, vasculitis purpura, and sinusitis that was detected during etiological investigations, the patient was diagnosed as having CSS according to the American College of Rheumatology diagnostic criteria. Intravenous methylprednisolone 1 g/day was administrated for 3 consecutive days and 1 g cyclophosphamide was started and continued monthly for 6 months. Foot drop and vasculitic purpura improved after 7 days, but there was no further improvement in visual acuity. In conclusion, in the presence of bilateral CRAO and lack of atherosclerotic risk factors, CSS should be considered as a predisposing factor and investigations should be conducted accordingly.

Glomerular Immune Deposition in MPO-ANCA Associated Glomerulonephritis Is Associated With Poor Renal Survival.

Background: Rapidly progressive glomerulonephritis caused by antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is typically characterized as pauci-immune glomerulonephritis. However, immune complex (IC) deposition in the glomerulus has been reported in a growing number of studies. Here, we assess the presence of glomerular immune deposits alongside renal outcome in myeloperoxidase (MPO)-ANCA associated glomerulonephritis (MPO-ANCA GN). Methods: Clinical and histopathologic characteristics of 97 patients with MPO-ANCA GN classified by renal biopsy from January 2008 to December 2019 were extracted retrospectively from electronic medical records. The extent of immune deposits in the kidney (C3, C4, C1q, IgA, IgG, IgM) at diagnosis were analyzed by immunofluorescence (IF). Patients were followed up for a median period of 15 months. The response to treatment and outcomes of renal and histological lesion changes were also assessed. Results: In our study, 41% (40/97) of patients showed positive IF (≥2+) for at least one of the six immunoglobulin or complement components tested. Patients with IC deposits showed higher levels of serum creatinine (p=0.025), lower platelet counts (p=0.009), lower serum complement C3 (sC3) (≤790 ml/L) (p=0.013) and serum IgG (p=0.018) than patients with pauci-immune (PI) deposition at diagnosis. End-stage renal disease was negatively associated with eGFR (HR 0.885, 95% CI 0.837 to 0.935, p<0.0001), platelet count (HR 0.996, 95% CI 0.992 to 1.000, p=0.046) and serum globulin (HR 0.905, 95% CI 0.854 to 0.959, p=0.001). Patients with lower sC3 levels showed a worse renal outcome than the patients with normal sC3 at diagnosis (p=0.003). Analysis of the components of the renal deposits found that patients with IgG deposits exhibited a poorer renal outcome compared to patients that were IgG negative (p=0.028). Moreover, Bowman's capsule rupture occurred less frequently in patients with IgM deposition compared with IgM negative counterparts (p=0.028). Vascular lesions and granuloma-like lesions had been seen more frequently in cases with IgA deposition than those without IgA deposition (p=0.03 and 0.015, respectively). Conclusion: In conclusion, patients with immune complex deposits in the kidney showed less platelet count, lower sC3 and sIgG levels, and higher serum creatinine levels. Patients with low sC3 at initial and with continued low sC3 during the treatment displayed a trend toward poorer kidney survival. Moreover, the IC group showed a worse renal outcome than the PI group, further enforcing the present strategy of introducing complement targeted therapies in AAV.

C3 glomerulonephritis associated with ANCA positivity: a case report.

BACKGROUND: C3 glomerulopathy (C3G) is a recent disease classification that is characterized by the presence of glomerular deposits (composed of C3) in the absence of significant amounts of immunoglobulin and comprises dense deposit disease and C3 glomerulonephritis (C3GN). Most C3GN manifests as membranoproliferative, mesangial proliferative glomerulonephritis patterns via light microscopy. Pure membranous nephropathy (MN)-like glomerular lesions are rare manifestations of C3GN. Anti-neutrophil cytoplasmic antibodies (ANCAs) are also seldomly reported to be positive in C3GN. Herein, we report the case of a C3GN patient presenting with an MN-like glomerular pattern with ANCA positivity. CASE PRESENTATION: A 68-year-old woman was admitted to a local hospital with elevated serum creatinine for two weeks. Laboratory tests showed a hemoglobin level of 85 g/L. Urinalysis was positive for 2 + protein and 360 RBCs/HPF. Blood biochemistry analysis revealed the following concentrations: albumin, 30.3 g/L; globulin, 46.2 g/L; blood urea nitrogen, 19.9 mmol/L; and serum creatinine, 234 µmol/L. The serum C3 level was 0.4950 g/L, and the serum C4 level was 0.1050 g/L. The direct Coombs test was positive. Serologic testing for ANCA revealed the presence of p-ANCA (1:10) by indirect immunofluorescence microscopy assay, as well as the presence of PR3 1.2 (normal range < 1) and MPO 3.5 (normal range < 1) by enzyme immunoassay. Renal biopsy sample pathology showed 2/6 cellular crescents and thickened glomerular basement membranes. Immunofluorescence testing revealed only diffuse, finely granular depositions of C3 along the glomerular capillary walls in frozen and paraffin-embedded tissue sections. Electron microscopy demonstrated the presence of subepithelial electron-dense deposits, similar to those that are observed in membranous nephropathy. Corticosteroid and cyclophosphamide were administered, with a subsequent improvement in renal function. CONCLUSIONS: We present the rare case of a patient with MN-like C3GN with ANCA positivity. C3GN with ANCA positivity may be represented by more crescents, severe renal dysfunction and more extrarenal manifestations. More cases are needed to elucidate the clinicopathologic features and optimal treatments of these patients.

Granulomatosis with polyangiitis presenting as pancreatic disease.

Granulomatosis with polyangiitis (GPA) is a rare necrotising small vessel vasculitis typically associated with oronasal, pulmonary and renal manifestations. Pancreatic disease is an exceedingly rare initial presentation and is associated with delayed diagnosis and rapid progression. We discuss a 66-year-old woman presenting with epigastric pain, elevated lipase and radiographic evidence of focal pancreatitis. She had no relevant medical history and no lithiasis seen on imaging. Pertinent findings include strawberry gingivitis, positive proteinase-antineutrophil cytoplasm antibody (98% specificity) and focal nodular parenchymal lung lesions on CT chest-all of which are consistent with a diagnosis of GPA. She was promptly started on high-dose steroids which resulted in significant clinical and biochemical improvement. Cyclophosphamide was added once biopsy confirmed the absence of malignancy. In order to optimise the clinical outcomes of GPA, physicians must keep a wide differential and high index of suspicion in the setting of unexplained pancreatitis with systemic features.