Crescentic Glomerulonephritis Research Articles

Anti-GBM antibody in a patient with diabetic nephropathy; all that glitters is not gold.

We present the case of a 58-year-old male diabetic patient admitted to our department for a slight decrease in kidney function, with nephrotic range proteinuria, hematuria (16,000/ml) and positive anti-glomerular basement membrane antibodies. Kidney biopsy revealed diabetic nephropathy with no evidence of crescent formation or linear immunoglobulin deposits along the basement membrane. We discuss the various clinical settings involving positive anti-glomerular basement membrane in the absence of crescentic glomerulonephritis.

#1933 Urinary proteomics identifying the novel biomarker associated with crescentic glomerulonephritis

Abstract Background and Aims As a severe progressive acute renal injury, crescentic glomerulonephritis requires timely pathology diagnosis and treatment. New non-invasive biomarkers will be crucial when the renal biopsy is not available or unacceptable. Urinary proteomics, specifically data-independent acquisition (DIA) proteomics, might provide some potential indicators. Method Urine proteomics examination was on patients with crescentic glomerulonephritis(n = 15), chronic glomerulonephritis (n = 15), acute kidney injury (AKI) without glomerular crescentic(n = 10), and 15 healthy controls. The crescentic glomerulonephritis group is the patients with extensive glomerular crescents over 50%. We performed LC-MS/MS analysis to identify differentially expressed proteins (DEPs), Ingenuity Pathway Analysis (IPA), and the proteome map for significant pathways and crucial proteins among patients and controls. The signature proteins were validated using enzyme-linked immunosorbent assay (ELISA) analysis. Results A total of 55 population, males occupied 45.45%, with the average age being 53 ± 13 years old. A volcano plot among crescentic glomerulonephritis and control groups is in Fig. 1. IPA analysis showed that neutrophil degranulation and complement cascade were the top two pathways in crescentic glomerulonephritis but not in the healthy and nephritis groups. The activated neddylation pathway in patients with crescentic glomerulonephritis compared with AKI patients. After integrating the DEPs among three groups via the Venn plot, we observed eight DEPs significantly associated with the crescentic glomerulonephritis, among which Coagulation factor V (F5), Phospholipid transfer protein (PLTP), and Alcohol dehydrogenase 1C (ADH1C) were significant proteins. Biomarker analysis showed the area under the curve values for predicting crescentic glomerulonephritis were 0.867, 0.851, and 0.815, respectively (P < 0.001). Conclusion Urine proteomics holds promise in identifying the crescentic glomerulonephritis patient, thus providing a potential value as a noninvasive biomarker.

#2837 Novel therapeutic for crescentic glomerulonephritis through targeting CLDN1 in parietal epithelial cells

Abstract Background and Aims Crescentic glomerulonephritis (CrGN) is the final mode of kidney injury common to several immune-mediated kidney diseases. CrGN is characterized by extensive glomerular parietal epithelial cells (PECs) proliferation forming crescents. The destructive crescent is then progressively replaced by fibrosis. Currents therapies for CrGN do not directly target the deleterious response of resident kidney cells. In a pathological context, claudin-1 (CLDN1), a transmembrane protein involved in epithelial tight junctions, can be exposed outside the tight junctions and mediate pro-fibrotic pathways and extracellular matrix (ECM) remodelling. Lixudebart (formerly ALE.F02) is a first-in-class monoclonal antibody that specifically targets and blocks exposed CLDN1 in injured epithelial cells. A phase II clinical trial is under way for patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV) with rapidly progressive glomerulonephritis which induces kidney fibrosis (RENAL-F02, NCT06047171). CLDN1 is highly expressed by glomerular PECs. This study investigated the functional role of CLDN1 in CrGN and the potential benefit to target CLDN1 in CrGN. Method CLDN1 expression in renal tissues of CrGN patients was analyzed using kidney multicolor immunofluorescence staining and spatial transcriptomics. Correlation between CLDN1 expression and clinical endpoints (eGFR, proteinuria), disease biomarkers and crescent evolution were studied. A spatially resolved molecular roadmap from CLDN1+ crescentic glomeruli was conducted. Proof-of-concept studies using anti-CLDN1 mAb were performed in preclinical models of CrGN. Results In tissues (n = 150) of patients with AAV and IgAN, multicolor immunofluorescence revealed up-regulated CLDN1 expression by cellular and fibrocellular crescents. At the time of diagnostic kidney biopsy, glomerular CLDN-1 expression was correlated with podocyte loss (as measured with P57 staining) and fibronectin area. The extent of dual expression of CLDN1 and CD44 at the surface of active PECs was associated with poor renal outcome (eGFR < 30 ml/min) in AAV and IgAN patients with a median follow-up of 2.5 and 3.7 years respectively. Spatial transcriptomics analysis highlighted the association between CLDN1+ crescentic glomeruli and ECM genes. Treatment with anti-CLDN1 mAb reduced albuminuria, improved kidney function and decreased fibrosis biomarkers in nephrotoxic serum-induced CrGN in mice. Conclusion Our results suggest a functional role of CLDN1 in the pathogenesis of CrGN, providing preclinical proof-of-concept for anti-CLDN1 antibodies as a novel therapeutic approach in patients with CrGN.

#417 Targeting parietal epithelial cell activation with mineralocorticoid receptor antagonism controls FSGS and crescentic glomerulonephritis

Abstract Background and Aims We have recently demonstrated that targeting specific pathways in parietal epithelial cells (PEC) can markedly alleviate experimental extracapillary glomerular injury [1]. Accumulating evidence has indicated the potential contributions of the mineralocorticoid receptor (MR) to the pathophysiology of chronic kidney disease. MR is expressed in endothelial cells, glomerular mesangial cells, podocytes, and distal tubular cells. Previous studies have shown that administering mineralocorticoid receptor antagonists has beneficial effects in various renal injury animal models, the role of the MR in extracapillary glomerulopathies is still elusive and mechanistically unclear. Methods To investigate the cell-specific role of the MR in PEC in the course of focal segmental glomerulosclerosis (FSGS) and crescentic glomerulonephritis (GN), we generated chimeric mice specifically lacking MR (Pec Cre Nr3c2lox/lox) in PECs using an inducible Cre recombinase system. Maladaptive FSGS was induced by combining a high-salt diet and deoxycorticosterone acetate (DOCA) with unilateral nephrectomy (DOCA-UniN). Crescentic glomerulonephritis (GN) was induced using the anti-glomerular basement membrane nephrotoxic serum (NTS) model. Results At baseline, Pec Cre Nr3c2wt/wt and Pec Cre Nr3c2lox/lox mice displayed no kidney morphology and function differences. When challenged by DOCA-UniN, PEC-selective Nr3c2 targeting significantly inhibited the expression of PEC activation markers Ki67, CD44, and FSGS lesions. Importantly, Pec Cre Nr3c2lox/lox mice showed less albuminuria and preserved renal function compared to Pec Cre Nr3c2 wt/wt counterparts. Likewise, Pec Cre Nr3c2lox/lox mice showed less albuminuria and preserved renal function in the NTS-induced CGN model. Crescents were also more numerous and organised in Pec Cre Nr3c2wt/wt mice than in Pec Cre Nr3c2lox/lox animals. Next, we examined whether pharmacological MR inhibition could alleviate the severity of crescentic GN. When Pec Cre Nr3c2wt/wt mice were orally given eplerenone for 14 days after the onset of the crescentic GN, they were significantly protected from renal injury and failure (decreased proteinuria, normal BUN and reduced number of crescent). Such global action was associated with less expression of the CD44 activation marker on PECs. Thus, genetic disruption of MR in PEC and pharmacological inhibition using eplerenone reduced glomerular expression of CD44 and crescent formation. Furthermore, kidney biopsies of individuals diagnosed with crescentic glomerulonephritis displayed increased expression of MR in PEC within FSGS and crescents. We next evaluated PEC migration under various conditions (DMSO, HB-EGF, Eplerenone, or HB-EGF+Eplerenone) for 24 hours. Eplerenone fully abrogated HB-EGF-induced PEC migration and Pcna, Snai1, and Vim mRNA expressions. Conclusion Altogether, these results indicate the critical role of MR in PEC activation during crescentic glomerulonephritis, along with the recently discovered CD9/EGFR/PDGFR [1] and CLDN1 pathways. This further supports the idea that the PEC phenotype switch is not a bystander event but plays a targetable critical active pathogenic role in FGSS and, more surprisingly, in crescentic GN. MR modulation using eplerenone may be a new therapeutic option for the management of such severe disease.

#1603 A potent protein inhibitor of HB-EGF protects kidneys from glomerular lesions in a pig model of crescentic glomerulonephritis

Abstract Background and Aims Crescentic glomerulonephritis (CGN) is a severe disease that rapidly destroys the glomerular architecture. CGN is due to immuno-inflammatory aggressions triggered by anti-neutrophil cytoplasmic autoantibody-associated vasculitides, anti-glomerular basement membrane (GBM) autoantibodies, or immune complexes deposition as occurs in systemic lupus erythematosus, IgA nephropathy or infections. Treatments are based on aggressive immunosuppression. Although required, immunosuppression doesn't directly target the deleterious glomerular response to inflammation and leads to significant morbidity. Moreover, most patients still develop chronic or end-stage kidney failure, indicating that complementary strategies are needed. We showed previously that local over-expression of the growth factor HB-EGF (Heparin-binding EGF-like growth factor) and subsequent activation of EGFR lead to dedifferentiation and proliferation of parietal epithelial cells and podocytes, leading to crescentic lesions that irreversibly obliterate the glomeruli. We aimed to evaluate the therapeutic potential of a protein inhibitor of HB-EGF in a pig model of CGN. Method We engineered a protein inhibitor of HB-EGF, DTR8, from the receptor-binding domain of diphtheria toxin, a highly selective natural ligand of HB-EGF. Twelve mutations improved solubility, led to pM affinity, and reduced immunogenicity and antigenicity. Pigs received decomplemented nephrotoxic serum (NTS) from sheep immunized against pig GBM to mimic anti-GBM antibodies disease responsible for one form of CGN. Ten pigs were treated with 0.3 mg/kg of DTR8 twice a day by intramuscular route for 20 days, and 12 pigs received vehicle only starting 6 hours after NTS. Animals were sacrificed on day 21, and blood, urine and kidneys were analyzed. Five animals that had received pre-immune sheep serum served as controls. Results Pigs developed a nephritic syndrome with high proteinuria, hypoalbuminemia, kidney failure with increased BUN and blood creatinine levels, anasarca and crescentic lesions typical of CGN along with de novo HB-EGF glomerular overexpression. The vehicle-treated group had only 24.8% of histologically normal glomeruli, while the DTR8-treated group had 57.3% of healthy glomeruli. DTR8 treatment significantly reduced the percentage of crescentic lesions (P = .0365) and preserved podocyte differentiation as assessed by the expression of nephrin that was markedly reduced in vehicle-treated animals but maintained close to normal in DTR8-treated animals (P = .0028). DTR8 administration reduced EGFR phosphorylation in glomerular cells (P = .0161), suggesting local inhibition of the HB-EGF/EGFR cascade. Lymphocyte infiltration was reduced (P = .2543). Notably, the treatment group also displayed a global reduction in interstitial fibrosis (P = .0313). Conclusion The therapeutic protein candidate DTR8 protects kidney glomeruli in a CGN model in pigs.

#1800 Cascade filtration in severe pulmonary-kidney syndrome: an one-center experience

Abstract Background and Aims In some forms of rapidly progressive glomerulonephritis (RPGN), the effect of plasma exchange (PE) is not well understood. Cascade filtration (CF) differs from standard PE in that it uses a double filter system, where the first filter is used to separate plasma from whole blood and the second filter is used to filter high-molecular weight substances. In this study, we investigated the efficacy and safety of CF in patients with ANCA-associated vasculitis (AAV) and Goodpasture's syndrome (GPS). Method During one year we included 18 patients with RPGN whose received CF in the study. The eligibility criteria was eGFR ≤15 ml/min/1.73 m2 and/or diffuse alveolar hemorrhage (DAH), presence of antineutrophilic antibodies or anti-GBM-antibodies. CF was performed on a Plasauto Sigma using a Plasmaflo OP-05W plasma separator and a Cascadeflo EC-30W separator with a fresh frozen plasma or 25% albumin solution. All patients received immunosuppressive therapy with steroids and cyclophosphamide, one patient with AAV received rituximab due to anemia and thromobocytopenia. All data were obtained from one hospitalization with the median of 43 days. Results Eight patients with AAV and three patients with GPS met the eligibility criteria. The median age of the patients in the AAV group was 59.8 (48; 66) years, with a female to male ratio of 1:1. All patients had evidence of systemic disease: seven patients had lung damage, including DAH, two patients had arthralgia, one had purpura and one had severe sinonasal involvement. The median creatinine level was 588 µmol/l (382; 1352), dialysis was initiated in 6 patients, and the median Birmingham Vasculitis Activity Score (BVAS) was 17 (15; 20). After three procedures of CF, all patients showed positive changes on CT scan, and dialysis was stopped in three patients. The immunological response to CF was observed quite rapidly in seven patients, with decreasing ANCA titer after three exchanges and decreasing antibody levels after six exchanges in one patient. There was a significant decrease in inflammatory markers, median C-reactive protein at baseline 179 (147; 226) decreased to 23 (2.8; 30.9) mg/l (p = 0.041). The CF was well tolerated with no significant adverse events. One patient receiving rituximab died after 4 months due to a severe COVID 19 infection. Three patients with GPS, one male 23 years old and two females 56 and 60 years old, also received CF. Creatinine concentrations at baseline were 1285, 1299 and 661 µmol/l, BVAS scores were 18, 20 and 15, respectively. After three procedures of CF, there was an immunological response: decrease in antibody levels from 121 U/ml to 15 U/ml, from 88.2 to 18.4 U/ml, from > 200.0 to 85.4 U/ml, CRP from 252 to 0.7 mg/l, from 120 to 5 mg/l, from 81.9 to 12.58 mg/l. There were no deaths and all three patients remained on dialysis. Conclusion CF was an effective and well tolerated method of treating severe AAV and GPS in addition to immunosuppressive treatment. Possibly due to the different filtration principle and the absence of donor plasma, we did not observe any infection-related adverse events and a lower number of procedures of CF was required compared to standard plasma exchanges. Further larger studies are needed to evaluate the benefits and safety of CF in combination with immunosuppressive treatment in RPGN patients.

#187 Vasorin (VASN) commands podocyte quiescence and glomerular homeostasis. A novel FSGS mechanism?

Abstract Background and Aims Podocyte dysfunction and loss of quiescence contribute to focal segmental glomerulosclerosis (FSGS) and crescentic glomerulonephritis (CGN). Here, we characterized the role of Vasorin (VASN) in podocytes. Method We combined laser capture microdissection and deep RNA sequencing of human glomeruli, RNAscope-based in situ hybridization, immunostaining and mouse models with Vasn-driven fluorescent reporter, targeted Vasn gene deletion in podocytes and cultures of human podocytes. Results VASN mRNA is strongly expressed in healthy human and mouse glomeruli with a podocyte-specific pattern. Both global and podocyte-specific, constitutive or inducible gene deletion of Vasn in mice induced a nephrotic syndrome and kidney failure after day 14, with podocyte dedifferentiation and loss and severe FSGS lesions, indicating a fundamental and non-developmental role of VASN in podocyte homeostasis. Furthermore, we measured markedly decreased VASN expression in podocytes of patients with FSGS and ANCA-associated CGN but not with Minimal Change Disease (MCD) and Membranous Nephropathy (MN). We thus wondered whether VASN abundance could be a disease modifier for glomerulopathies. Mice with podocyte-specific partial heterozygous deletion of Vasn showed no evident baseline renal abnormalities. Still, they showed significantly more podocyte loss, albuminuria and kidney failure than wild-type mice when challenged by type 1 diabetes with glomerular hyperfiltration or CGN experimental models. Human podocytes transduced with lentiviral VASN-targeting shRNA (shVASN) displayed increased focal adhesion dynamics, resistance to oscillating mechanical stretches, enhanced migratory capacity and epithelial-mesenchymal transition (EMT) markers. Moreover, shVASN podocytes had a higher proliferative capacity, increased cell-cycle reentry and a relative S-phase slow-down. Likewise, transcriptomics analysis found the up-regulation of genes involved in cell metabolism, adhesion and EMT and the down-regulation of genes involved in the S to G2/M phase transition. In vivo, we confirmed that VASN deficiency increased podocyte proliferation in situ and urinary shedding. Conclusion These findings highlight the novel role of VASN as an essential master protein that maintains podocyte quiescence and homeostasis during health and kidney diseases while offering a potential new therapeutic target. VASN control mechanisms driving podocyte cell-cycle reentry and detachment and FSGS. Precise mechanisms of VASN functions in podocytes need further insights into VASN molecular partners.

#2889 Multiple renal tumors as an atypical clinical manifestation of granulomatosis with polyangiitis

Abstract Background and Aims Granulomatosis with polyangiitis (GPA) is a systemic small- vessel vasculitis associated with antineutrophilic cytoplasmic antibody (ANCA), in which kidney involvement often occurs. In some cases the course of vasculitis with kidney involvement is atypical, what complicates the diagnostic process and makes appropriate treatment difficult. Finding nodular masses in the kidneys always causes an oncological concern, while in the differential diagnosis a systemic vasculitis is rarely taken into account, what may lead to an unnecessary nephrectomy. Method We present a case of granulomatosis with polyangiitis (GPA) who presented with multiple tumors in the kidneys and adrenal gland. Results 29-year-old man experienced a sudden disease onset, at the age of 18 years, when due to peripheral oedema, nephrotic grade proteinuria (13.7 g/24 h), hematuria and presence of renal failure markers (serum creatinine 3.4 mg/dL), he was admitted to hospital. A suggestion of a rapidly progressive glomerulonephritis (RPGN) was put forward and a renal biopsy was performed (in the histopathological examination of the kidney, pauci-immune crescentic necrotizing glomerulonephritis was revealed). A treatment with plasmaphereses, high glucocorticosteroid doses and cyclophosphamide pulses was instituted. Haemodialysis therapy was also applied temporarily. ANCA and anti-glomerular basement membrane (GBM) antibodies were determined to give negative results. As a result of the remission-inducing treatment, an improvement of the renal function was obtained (serum creatinine 1.6-1.9 mg/dL). In spite of the remission-maintaining treatment with mycophenolate mofetil (MMF) and oral prednisone, after 10 years again a dramatic renal function impairment occurred, with a necessity of institution of a long-term haemodialysis therapy. Furthermore, on abdominal ultrasound examination multiple focal lesions were found in both kidneys, which rendered a kidney transplantation procedure in the patient impossible. In order to extend the diagnostic procedures, a magnetic resonance imaging (MRI) of the abdominal cavity without contrast agent administration was carried out (in both kidneys disseminated focal lesions were described: non-homogeneous, with moderately enhanced signal on T2-weighted images in the central part, without signs of water diffusion restriction; in the left kidney, of 23 x 22 mm and 19 x 15 mm dimensions; in the right kidney, of 30 x 32 mm, 26 x 22 mm and 22 x 18 mm dimensions. The picture of the lesions was unspecific and atypical. In the differential diagnosis granulomas could not have been ruled out, while disseminated proliferative lesions were less likely. Besides that, in both kidneys cysts of up to 7 mm diameters were present. In the lateral limb of the left adrenal gland a focal lesion was visible, of 23 x 14 mm dimensions, of a structure identical to that of the foci in both kidneys). On high-resolution computed tomography (HRCT) of the chest at the same time, small ground glass areas were found in the lungs. On positron emission tomography/computed tomography (PET/CT) no changes were visualised, suggesting presence of a metabolically active proliferative process. Tests for ANCA, antinuclear antibodies (ANA), anti- double-stranded DNA (dsDNA) antibodies, anti- GBM antibodies were again performed and gave negative results. He was diagnosed with granulomatosis with polyangiitis without ANCA and treated with corticosteroid and intravenous rituximab (4x 787 mg). Three months later, follow-up showed reduced mass lesions in the kidney and adrenal gland by MRI. Conclusion The case highlights the atypical clinical presentation of vasculitis and the significance of considering this possibility in differential diagnosis when confronting mass lesions present in the kidney.

Glomerulonephritis as a paraneoplastic event from prostate cancer relapse

Abstract Objective We wish to investigate whether there is a known connection between prostate cancer and glomerulonephritis. Methods We present a case report of a patient whom we diagnosed with rapidly progressive glomerulonephritis as a result of prostate cancer relapse. Results In rare cases, prostate cancer is associated with crescentic glomerulonephritis. Conclusion Every patient with cryptic glomerulonephritis should be screened for cancer.

#1883 SUrvey of renal Biopsy database and Anti-cancer dRUg therapy in Japan (SUBARU-J study)

Abstract Background and Aims The frequency of consultations for renal complications associated with anti-cancer drug therapy has greatly increased in recent years, but the actual situations remain yet to be fully understood. We aimed to investigate the clinical outcomes of anti-cancer drug therapy-associated renal complications, using the Japan Renal Biopsy Registry (J-RBR), a nationwide registry system in Japan. Method This nationwide survey was performed in 449 cases with “drug-induced” checked in J-RBR database from 2018 to 2021. In total 449 subjects, top-ranked histopathological diagnoses were as follows, TIN (49.8%), TMA (14.5), MN (10.0), MCNS (6.5), FSGS (4.4), Vasculitis (2.2) and others (12.2). Regardless of the causative agent, TIN was the most common diagnosis. Though, it was followed by TMA or MN in anti-cancer drug (n = 139)- or non-anticancer drug (n = 190)-related cases, respectively. Because there was also TMA included as 2nd highest in causative-agent unidentified cases (n = 120), we employed total 259 subjects of anti-cancer drug-related and causative-agent unidentified for this survey. Our surveillance files investigating on renal pathology, medications and cancer prognosis were distributed. Of the 224 cases with a file uploaded, a total of 135 anti-cancer drug-related cases confirmed by the information were analyzed. Patients’ clinical data collected at pre- and post-biopsy as well as histopathological diagnoses were used for epidemiological and clinicopathological analyses. Mann-Whitney U test or chi-square test was used for continuous or categorical variables. Overall survival (OS) was estimated using Kaplan–Meier method and compared by log-rank test. Results In total 135 subjects, top-ranked histopathological diagnoses were as follows: tubulointerstitial nephritis (TIN; 64 cases), thrombotic microangiopathy (TMA; 48), focal segmental glomerulosclerosis (FSGS; 5), IgA nephropathy (IgAN; 4), acute tubular necrosis (ATN; 3), minimal change nephrotic syndrome (MCNS; 3), crescentic glomerulonephritis (CrGN; 2), membranoproliferative glomerulonephritis (MPGN; 2) and others (4). 80% of TIN and 75% of TMA, the most frequent diagnoses in our survey, were associated with immune-checkpoint inhibitors (ICI) and anti-angiogenic therapy (AAG), respectively. All IgAN, MCNS and CrGN cases were ICI-related. Proton pump inhibitors and antibiotics were used concomitantly in TIN (p = 0.054) and TMA (p < 0.001), respectively. Among cases with TIN, their OS in the subgroups of targeted therapy (Tx), and the combination with Tx and conventional cytotoxic agents (Combi) seemed to be worse than that of cytotoxic agents alone (CTx); it may be due to more cases in the Tx and Combi subgroups with treatment response category of progressive disease (by RECIST criteria). In contrast, among TMA cases, OS in each of the three subgroups of Tx, CTx, and Combi seemed to be overlapped, suggesting the prognostic impact of TMA on OS. The serum LDH level was higher in TMA associated with CTx (CTx-TMA) than that with others (Fig. 1: 393.2 vs. 225.1 U/L, p = 0.06). Of note, Kaplan-Meier curves for OS in TMA cases with increased LDH (>220 U/L) showed poor prognosis in CTx-TMA than in others-TMA (Fig. 2: p = 0.018). Conclusion Our nationwide survey using J-RBR registry database with renal biopsy data provides a snapshot of kidney complications associated with anti-cancer drug therapy. Higher LDH in CTx-TMA cases may be associated with systemic TMA, probably leading to the poor prognosis. To explore the detail of anti-cancer drug-associated TMA and other complications, further research employing more sample size is warranted in the future.

#1851 Pregnancy outcomes in women with glomerular disease: Mansoura experience

Abstract Background and Aims Pregnancy is a “stress test” for the kidney, and may initiate, aggravate, or unmask a kidney disease. Pregnancy in women with glomerular disease remains challenging. Glomerular disease increases the risks of adverse pregnancy outcomes especially in case of reduced eGFR, proteinuria or uncontrolled hypertension. The heterogeneity of the diseases, severity and settings does not allow making precise outcome predictions. Few data are available from African countries. Aim of this study is to review the outcomes of 43 pregnant women with biopsy-proven glomerulonephritis followed-up in 2020-2022, in a new unit for obstetric nephrology set up in Mansoura, Egypt. Method We reviewed archived paper and electronic records for history, clinical data, and laboratory investigations as well as immunologic profile of all women with glomerular diseases followed up since the start of our activity. Outcomes included timing and mode of delivery, maternal and foetal mortality, neonatal ICU admission, low birth weight (<2.5 kg), and presence of congenital anomalies. In the postpartum period, data on maternal renal function was also analysed. Renal function impairment was defined as ≥150% increase in postpartum serum creatinine compared to antenatal baseline values. Results 43 patients were included. Lupus nephritis accounted for 52.4%, minimal change disease 16.7%, focal segmental glomerulosclerosis 14.3%, membranous nephropathy 7.1%, thrombotic microangiopathy, membranoproliferative, crescentic, and focal proliferative GN accounted for 2.4% (one case) each. Patients were referred in the 22 (4-37) weeks of pregnancy from regional urban and rural obstetric services. At referral 27 (62.8%) patients were in stage 1, 8 (18.6%) in stage 2, 7 (16.3%) in stage 3 and 1 (2.3%) in stages 4-5 CKD. Proteinuria at referral was 1000 (16-34.500 mg/d). Twenty-two (51.2%) women were hypertensive at referral. Obstetric outcomes were assessed in 36 pregnancies, which resulted in 30 live birth (78.9%); with one postnatal mortality, no miscarriage (<24 gestational weeks), in 4 (10.5%) intrauterine deaths and in 4 (10.5%) induced abortion. Of the living born babies, 2 (6.7%) were extremely preterm (<28 weeks), 8 (26.7%) early preterm (28-34 weeks) and 8 (26.7%) late preterm (34-37 weeks). Renal progression was assessed in 33 cases, occurring in 0% in patients with MCD, MN and membranoproliferative, 3 (17.6%) in LN, 2 (50%) FSGS, 100% of patients with focal proliferative, TMA and crescentic GN (one case for each). Out of 3 mothers who were in CKD stages 3b-5 at referral, one started dialysis. Conclusion Glomerulonephritis in pregnancy is probably referred late in our setting, and lupus nephropathy was the most frequent diagnosis. Preterm delivery and low birth weight are frequent in this population and the risk of maternal kidney function impairment is confirmed as higher in lupus nephropathy and when baseline kidney function impairment, proteinuria and hypertension are present.

#3108 Rituximab in adult-onset IgA vasculitis

Abstract Background and Aims Adult-onset IgA Vasculitis (IgAV) is poorly responsive to glucocorticoids (GC) and conventional immunosuppressive therapies, such as cyclophosphamide. Rituximab has been successfully used in a few cases and may represent a safer and potentially more effective option [1]. Crescentic IgA Nephropathy (cIgAN), a rare entity that shares features of renal vasculitis with IgAV, is also frequently refractory to cyclophosphamide, while response to rituximab is unknown. We investigated outcomes after rituximab in a multicentre European cohort of adult-onset IgAV and cIgAN. Method We screened clinical records of patients followed at 18 European consorted centres who were ≥18 years old at the onset of IgAV and received ≥1 rituximab dose. Furthermore, we identified patients with cIgAN (≥25% crescentic glomeruli and rapidly progressive glomerulonephritis), who were treated with rituximab. Remission was defined as Birmingham Vasculitis Activity Score (BVAS) <3 at month 6 after rituximab and renal response as stable or improved eGFR and ≥50% proteinuria reduction. Relapse was defined as an increase in BVAS requiring a change in immunosuppressive therapy. Outcomes of IgAV with severe nephritis (eGFR <60 mL/min) were compared with those of cIgAN. Results We included 61 patients with IgAV and 15 with cIgAN (Table). Rituximab was administered as initial therapy in 23/61 (38%) patients with IgAV and 13/15 with cIgAN (87%), while the remainder had refractory or relapsing disease. Active skin involvement was present in 49 patients (80%) and nephritis in 55 patients (90%) with IgAV at the time of starting rituximab. This was given alone in 13/61 (21%) or combined with GC in 48 (79%) patients with IgAV and in all those with cIgAN. Furthermore, cyclophosphamide was used in 15% of patients with IgAV and 40% of those with cIgAN. Remission at 6 months was achieved by 52 (85%) patients with IgAV and 12/13 (92%) of those treated with rituximab alone. A renal response was observed among 49/55 (89%) of those with nephritis. Patients with IgAV and severe nephritis had similar eGFR to those with cIgAN at the time of starting rituximab, but the latter had lower rate of remission and a higher frequency of kidney failure. A relapse occurred in 15/52 patients (29%) who achieved remission a median of 13 months (10-15) after rituximab. Eight patients resumed rituximab and achieved again remission. Conclusion Rituximab alone or in combination with GC and immunosuppressants appeared to achieve a high rate of remission in this cohort of adult-onset IgAV. Renal response among those with severe nephritis was also good, while this was worse among patients with cIgAN, suggesting substantial differences among these conditions despite similar histological appearances.

#2475 Glomerulonephritis associated with anti -TNF-α therapy

Abstract Background and Aims Biologic agents like tumor necrosis factor α inhibitors/ anti-TNF-α/, IL6 and CD80/26 are widely used in many rheumatologic diseases but these may also elicit effects on renal function. These drugs, as well as rheumatic diseases themselves, can cause autoimmune renal disorders. Though effective on the main inflammatory process the incidence of kidney injury associated with their administration is increasing. Various forms of glomerulopathies have been described in connection with biological therapy - proliferative lupus nephritis, oligo immune necrotizing crescentic glomerulonephritis, membranous glomerulonephritis, IgA nephropathy and others. Method We report the clinical and pathologic findings in two patients with Rheumatoid arthritis and Ankylosing spondylitis on biologic therapy with an anti-TNF-α agent. During the treatment they presented with nephritic syndrome requiring kidney histology. Results Case 1: The first patient is a 52-year-old man diagnosed with ankylosing spondylitis, HLA-B27 positive, 15 years before admission. Four years before admission treatment with Golimumab /anti-TNF-α/ has been initiated. During the follow-up period urine tests revealed proteinuria and hematuria, which required more detailed tests. The patient presented with clinical features of nephritic syndrome, marked lower extremity edema, hematuria, nephrotic range proteinuria, impaired hypertension control. Kidney biopsy revealed membranoproliferative glomerulonephritis. It was assumed that kidney injury was most likely associated with Golimumab therapy. Its administration was discontinued, and therapy was started with pulses of Methylprednisolone 500 mg i.v. in three consecutive days, Cyclophosphamide 500 mg i.v., repeated the second and third month, followed by low steroid doses 0,5 mg/kg with gradual tapering. Mycophenolate Mofetil 1500 mg was started from the third month. General condition and laboratory results improved considerably. The occurrence of stiffness and pain in the sacroiliac joints several months after stopping biologic treatment necessitated the inclusion of Sulfasalazine to the therapy. Initiation of therapy with another class of biologic agent, Anti-IL-17 monoclonal antibody, was discussed with the follow-up rheumatologists. Case 2: The second patient is a 66-year-old woman, with a history of hypertension and essential thrombocythemia, who was diagnosed with seropositive rheumatoid arthritis 3 years before admission, treated with Adalimumab /anti-TNF-α/. Follow-up examinations revealed low-grade proteinuria, hematuria and impaired renal function. Kidney biopsy revealed IgA nephropathy. Following the discontinuation of Adalimumab, the patient was treated with pulses of Methylprednisolone 500 mg i.v. in three consecutive days, Cyclophosphamide 500 mg i.v., repeated the second and third month, followed by low steroid doses 0,5 mg/kg with gradual tapering. Kidney function significantly improved at the third month of treatment and proteinuria was gradually reduced. Initiation of Rituximab /antiCD20/ treatment was discussed with rheumatologists. Conclusion Treatment with biological drugs can cause immune-mediated glomerular disorder/IGD/. These events are rare, and the causative effects of a specific drug is hard to establish. When a patient is suspected of having an IGD, kidney biopsy should be performed for the exact diagnosis. The drug should be discontinued, and the treatment for the new-onset renal disorder should be promptly started. A rechallenge test of the same or a similar drug should be avoided, whereas switching to a different therapy is a reasonable option.

#760 Monogenic lupus with ANCA associated vasculitis-phenotype and ANCA positivity due to DNASE1L3 mutations: case report and review of the literature

Abstract Background and Aims Monogenic systemic lupus erythematosus (SLE) accounts for 7-10% of cases of early-onset SLE. DNASE1L3 is an extracellular nuclease that digests chromatin released from apoptotic cells and its deficiency, enhance autoantibody production and type I interferon responses and cause different autosomal recessive phenotypes including SLE and hypocomplementemic urticarial vasculitis syndrome (HUVS) [1]. In some cases patients can have a mixed SLE-AAV phenotype. Kidney involvement in patients with DNASE1L3 mutations is poorly characterised. Method We present the case report of a 7-years-old boy with monogenic SLE due to DNASE1L3 mutations who developed severe glomerulonephritis leading to kidney failure. Results The patient had a history of urticaria and arthralgia and presented with fever, haemolytic anaemia, lymphadenopathy, hepato-splenomegaly, erythematous- macular and necrotic skin lesions, and interstitial lung disease. He also had acute kidney injury (serum creatinine 5.4 mg/dL), nephrotic- range proteinuria (3.9 g/24 h) and microhaematuria. Immunological tests revealed low C3 and C4, positive anti-nuclear antibody (ANA) and myeloperoxidase-antineutrophil cytoplasmic antibodies (MPO-ANCA), with negativity of anti-extractable nuclear antigen antibodies (anti-ENA) and anti-double stranded DNA (anti-dsDNA). Kidney biopsy showed pauci-immune (mesangial C3+ and IgG+) necrotising crescentic glomerulonephritis. The patient proved refractory to standard immunosuppression with cyclophosphamide and steroids. Two years later, due to renal function decline, a new kidney biopsy was performed and showed diffuse necrotising glomerulonephritis with endo- and extra-capillary proliferation; intense mesangial and subendothelial full-house deposits were evident on immunofluorescence. The patient did not respond to other lines of immunosuppression (mycophenolate mofetil, tacrolimus, azathioprine, rituximab), including the JAK inhibitor ruxolitinib. Kidney failure progressed to end stage at the age of 15 years, when the patient began haemodialysis. The kidney presentation, immunological profile and the first kidney biopsy led to diagnosis of AAV. However, the diagnosis was questioned due to the refractory course, the systemic clinical presentation and the second kidney histology (consistent with lupus nephritis). High interferon signature was detected and in the suspicion of a monogenic lupus nephritis Whole Exome Sequencing was performed and revealed homozygous DNASE1L3 variants (c.290_291delCA p.T97Ifs*2); thus, a final diagnosis of DNASE1L3 monogenic SLE was made. DNASE1L3 serum levels were normal but the DNAse enzymatic activity was low. Conclusion Renal involvement is one of the most frequent manifestations of DNASE1L3-related lupus; in the literature 32 cases of DNASE1L3-associated lupus nephritis are described. ANCA are positive in about 55% of these cases and are associated with a mixed lupus-AAV phenotype. All cases are characterized by resistance to common immunosuppressors and poor renal prognosis [2]. DNASE1L3 regulates neutrophil extracellular trap (NET) clearance and when this function is reduced the permanence of NETs induces endothelial damage and autoantibody formation. This pathogenic pathway is shared both by SLE and by AAV. There is no association between specific mutations and antibody positivity or clinical manifestations.

#2727 Acute kidney in patients with ANCA associated vasculitis

Abstract Background and Aims Renal involvement in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is considered an emergency situation. Early diagnosis and treatment significantly improve prognosis. The aim of this study was to investigate the characteristics of acute kidney injury (AKI) in ANCA-associated vasculitis and assess its developmental aspects. Method Our study, conducted in the Internal Medicine Department A of Charles Nicole Hospital over a four-year period (January 2018-August 2022), was retrospective and descriptive. The diagnosis of ANCA vasculitis was made based on the ACR 1990 and/or EULAR 2012 criteria. The severity of AKI was categorized according to the KDIGO AKI classification. Results Seventeen patients were included, with a mean age of 51 ± 17.42 years and a sex ratio of 0.42. The primary clinical presentation of AKI was rapidly progressive glomerulonephritis (n=11), followed by acute nephritic syndrome (n=4). Pneumo-renal syndrome was observed in 4 patients. Proteinuria and hematuria were present in all 17 patients, with 4 being oligoanuric on dipstick. The mean creatinine level was 584 μmol/L, ranging from 125 to 1151 μmol/L. Thirteen patients had KDIGO stage 3 AKI on admission. The predominant histological lesion was extracapillary crescentic glomerulonephritis, based on the Berden classification (n=6). Hemodialysis was initiated immediately in 12 cases, and plasma exchange was performed in 10 cases. The average follow-up time was 24 months, ranging from 3 months to 4 years. Evolution was marked by partial remission in 7 cases, with a mean creatinine of 173 μmol/L. Progression to end-stage renal disease (ESRD) occurred in 10 cases. Relapses, presenting as pneumo-renal syndrome, were observed in 4 patients. Seven patients succumbed, with vasculitis being the cause of death in 3 cases. In univariate analysis, age >70 years was associated with progression to ESRD (p=0.03). No factor studied emerged as a prognostic factor for overall survival. Conclusion The presence and severity of AKI in ANCA-associated vasculitis are linked to a poorer prognosis, affecting both patient and renal survival.

Macrophage-derived macrophage migration inhibitory factor mediates renal injury in anti-glomerular basement membrane glomerulonephritis

Macrophages are a rich source of macrophage migration inhibitory factor (MIF). It is well established that macrophages and MIF play a pathogenic role in anti-glomerular basement membrane crescentic glomerulonephritis (anti-GBM CGN). However, whether macrophages mediate anti-GBM CGN via MIF-dependent mechanism remains unexplored, which was investigated in this study by specifically deleting MIF from macrophages in MIFf/f−lysM−cre mice. We found that compared to anti-GBM CGN induced in MIFf/f control mice, conditional ablation of MIF in macrophages significantly suppressed anti-GBM CGN by inhibiting glomerular crescent formation and reducing serum creatinine and proteinuria while improving creatine clearance. Mechanistically, selective MIF depletion in macrophages largely inhibited renal macrophage and T cell recruitment, promoted the polarization of macrophage from M1 towards M2 via the CD74/NF-κB/p38MAPK-dependent mechanism. Unexpectedly, selective depletion of macrophage MIF also significantly promoted Treg while inhibiting Th1 and Th17 immune responses. In summary, MIF produced by macrophages plays a pathogenic role in anti-GBM CGN. Targeting macrophage-derived MIF may represent a novel and promising therapeutic approach for the treatment of immune-mediated kidney diseases.

#1782 Clinicopathological study of renal limited pauci-immune vasculitis and its short-term outcome: a single centre observational study

Abstract Background and Aims Pauci immune crescentic glomerulonephritis, is a leading cause of RPGN. The majority of patients with PICGN have glomerular diseases as a part of a systemic small vessel vasculitis, a minority may present as renal-limited vasculitis. In north-east India, there are still no major studies in this group of patients. Therefore, our study involving north-east Indian population constitutes an effort to prospectively study the clinico-pathological feature of patients with PICGN and assess the short-term outcome. Method This single-centre, prospective, observational, study was conducted over 12 months at the Department of Nephrology, Gauhati Medical College. All renal biopsy-proven patients with pauci-immune renal vasculitis were included, excluding those with secondary vasculitis. Baseline characteristics and laboratory data were recorded, and disease activity was assessed using the Birmingham Vasculitis Activity Score. The ANCA tests were performed using a standardised essay for both indirect immunofluorescence assay and antigen-specific ELISA. The renal biopsy specimen obtained was evaluated by light microscopy and direct immunofluorescence. The sample size was calculated based on the prevalence of pauci-immune glomerulonephritis, and data were analysed using SPSS. Results The study involved 24 patients, predominantly females (70.83%), aged 14-65 years, presenting predominantly with pedal oedema and oliguria. Laboratory findings showed varying levels of haemoglobin, total count, platelet count, creatinine, and 24-hour urine protein. 50% of the patients were (MPO) positive, 33.3% were (PR3) positive while 16% were ANCA negative. Renal biopsy analysis showed a majority with mixed class according to the Berden classification. Treatment involved induction with Methylprednisolone and Cyclophosphamide, with dialysis administered to 58.3% of patients. At six months, 36.3% had a stable GFR, and 50% were on maintenance hemodialysis. Factors predicting renal loss included oliguria, dialysis at presentation, and fibrous/fibrocellular crescents. The best predictor of renal outcome was serum creatinine at presentation. Conclusion Pauci-immune CrGN is a severe disease affecting a wide age range. Early diagnosis and treatment initiation are crucial for better outcomes, including lower ESRD risk and relapse rates. Prognostic factors include baseline serum creatinine levels and fibrous crescents. Optimising treatment regimens may improves outcomes.

#2291 ANCA negative vasculitis—the unmet need within small vessel vasculitis

Abstract Background and Aims ANCA negative small vessel vasculitis with renal involvement has been described in a number of cohorts. Though comprehensive studies comparing these individuals to ANCA positive patients are lacking and they are routinely excluded from clinical trials. Whilst the numbers are smaller than those with ANCA positivity, they still make up a large proportion of small vessel vasculitidies (Fig. 1). The absence of detectable circulating ANCA is thought to indicate a distinct spectrum of the disease. There remains unanswered questions regarding the pathophysiology, diagnosis and management of patients with seronegative AAGN. We present data from Croatian referral center. Method Study included 106 AAV patients with biopsy proven renal involvement in the period from 2007-2017. Category variables were analysed with Fisher Exact test and continuous with Kruskal-Wallis test. Statistical difference was then analysed post hoc with Chi-square test. Kaplan Meyer survival analysis and multivariate Cox proportional hazard regression analysis were used to explore difference between clinical phenotypes and finding significant predictors regarding outcomes which were defined as combined outcome end-stage renal disease and death (ESRDD), ESRD alone, the death outcome alone and relapse rate. Results 106 AAV patients with renal involvement were included: 66 (61.1%) MPA, 20 (18.5%) GPA, 20 (18.5%) RLV. 14 (13%) were PR3-ANCA positive, 57 (52.8%) MPO ANCA positive, 5 (4.6%) PR3-ANCA+MPO-ANCA and 32 (29.6%) ANCA negative patients. ANCA negative patients were comparatively younger (p = 0.02) and presented with more renal limited vasculitis (RLV; p < 0.001), lower BVAS (p = 0.003) and lower CRP (p = 0.001). ANCA negative patients usually presented with nephrotic syndrome compared to positive ones which presented with rapid progressive nephritic syndrome or acute nephritic syndrome (p = 0.027). 24-hour proteinuria levels were higher in ANCA negative group (p = 0.003). Though statistical difference was not reached, there was tendency for ANCA negatives to receive less plasmapheresis (p = 0.074). Histologically there were no differences between ANCA positive and ANCA-negative patients. On sub analysis ANCA negatives versus individual seropositive groups, there was tendency that ANCA negatives and MPO-ANCA patients had lower percentage of glomerular crescents (p = 0.092) but more acute tubular damage (p = 0.087). There were no differences in clinical outcomes between the groups. Conclusion ANCA negative vasculitis form a large proportion of small vessel vasculitidies and present with different clinical laboratory and histological (renal) characteristics than ANCA positive ones. More often than not disease seems to be renal limited and patients tend to be younger. Due to the rarity of the disease, there remains unanswered questions regarding the pathophysiology, diagnosis and management of these patients. This study highlights noteworthy distinctions between the two groups. Whether these differences warrant adjustments in treatment algorithms or a reconsideration of the classification of small vessel vasculitis remains to be determined. Further investigation into the pathogenetic mechanisms of seronegative AAVs is essential.

Glomerular crescents are associated with the risk of type 2 diabetic kidney disease progression: a retrospective cohort study

BackgroundDiabetic kidney disease (DKD) stands as the predominant cause of chronic kidney disease and end-stage kidney disease. Its diverse range of manifestations complicates the treatment approach for patients. Although kidney biopsy is considered the gold standard for diagnosis, it lacks precision in predicting the progression of kidney dysfunction. Herein, we addressed whether the presence of glomerular crescents is linked to the outcomes in patients with biopsy-confirmed type 2 DKD.MethodsWe performed a retrospective evaluation, involving 327 patients diagnosed with biopsy-confirmed DKD in the context of type 2 diabetes, excluding cases with other glomerular diseases, from nine tertiary hospitals. Hazard ratios (HRs) were calculated using a Cox regression model to assess the risk of kidney disease progression, defined as either ≥ 50% decrease in estimated glomerular filtration rates or the development of end-stage kidney disease, based on the presence of glomerular crescents.ResultsOut of the 327 patients selected, ten patients had glomerular crescents observed in their biopsied tissues. Over the follow-up period (median of 19 months, with a maximum of 18 years), the crescent group exhibited a higher risk of kidney disease progression than the no crescent group, with an adjusted HR of 2.82 (1.32–6.06) (P = 0.008). The presence of heavy proteinuria was associated with an increased risk of developing glomerular crescents.ConclusionThe presence of glomerular crescents is indeed linked to the progression of type 2 DKD. Therefore, it is important to determine whether there is an additional immune-mediated glomerulonephritis requiring immunomodulation, and it may be prudent to monitor the histology and repeat a biopsy.

Kidney Failure in Pauci-immune Crescentic Glomerulonephritis: Rationale for Immunosuppression to Improve Kidney Outcome.

Pauci-immune crescentic glomerulonephritis is the hallmark finding in ANCA-associated vasculitis (AAV) when the kidneys are affected. The rationale for immunosuppression in AAV is based on the underlying autoimmune nature of the disease. Overall remission rates, kidney outcomes, and the burden of disease have greatly improved since the discovery of various immunosuppressive therapies, but relapses remain common, and a significant proportion of patients continue to progress to end-stage kidney disease. Here, we review the role of immunosuppressive therapies for the treatment of pauci-immune crescentic glomerulonephritis. Besides the recognized role of B and T cells in the pathogenies of AAV, the focus on the contribution of inflammatory cytokines, neutrophil extracellular traps (NETs), and the complement system allowed the discovery of new therapies. Specifically, the C5a receptor blocker (avacopan) has been approved as a glucocorticoid-sparing agent. Additionally, based on observational data, more clinicians are now using combination therapies during the induction phase. There is also an evolving understanding of the role of plasma exchange in removing ANCA antibodies. Furthermore, the recent development of risk score systems provides physicians with valuable prognostic information that can influence decisions on immunosuppression, although future validation from larger cohorts is needed. The over-activation of various immune pathways plays a significant role in the pathogenesis of pauci-immune crescentic glomerulonephritis in AAV. Immunosuppression is, therefore, an important strategy to halt disease progression and improve overall outcomes. Relapse prevention while minimizing adverse events of immunosuppression is a major long-term goal in AAV management.