anti-GBM GN Research Articles

Production of Acetylcholine by Podocytes and its Protection from Kidney Injury in Glomerulonephritis.

One of the most important factors modulating endothelial health is acetylcholine, and while it is associated as a cholinergic neurotransmitter; it is also expressed by non-neuronal cells. However, its role in the kidney, which does not receive cholinergic innervation, remains unknown. To determine if acetylcholine is produced in the kidney, we used ChAT(BAC)-eGFP (ChAT mice) transgenic mice in which enhanced green fluorescent protein (eGFP) is expressed under the control of the endogenous choline acetyltransferase (ChAT) transcriptional regulatory elements. We then investigated the role of acetylcholine in kidney disease by inducing anti- glomerular basement membrane glomerulonephritis (anti-GBM GN) in ChAT transgenic mice. We demonstrate ChAT, the sole enzyme responsible for acetylcholine production, was expressed in glomerular podocytes and produced acetylcholine. We also show during anti-GBM GN in ChAT transgenic mice, ChAT expression was induced in the glomeruli, mainly in podocytes and protects mice from kidney injury with marked reduction of glomerular proliferation/fibrinoid necrosis (by 71%) crescent formation (by 98%), and tubular injury (by 78%). In contrast, specific knockout of podocyte ChAT worsened the severity of the disease. The mechanism of protection included reduction of inflammation, attenuation of angiogenic factors reduction, and increase of eNOS expression. In vitro and in vivo studies demonstrated available drugs like cholinesterase inhibitors and ChAT inducers increased the expression of podocyte-ChAT and acetylcholine production. These findings suggest de novo synthesis of acetylcholine by podocytes protected against inflammation and glomerular endothelium damage in anti-GBM glomerulonephritis.

USP25 attenuates anti-GBM nephritis in mice by negative feedback regulation of Th17 cell differentiation

Purpose This study aimed to elucidate the role of USP25 in a mouse model of anti-glomerular basement membrane glomerulonephritis (anti-GBM GN). Methods USP25-deficient anti-GBM GN mice were generated, and their nephritis progression was monitored. Naïve CD4+ T cells were isolated from spleen lymphocytes and stimulated to differentiate into Th1, Th2, and Th17 cells. This approach was used to investigate the impact of USP25 on CD4+ T lymphocyte differentiation in vitro. Furthermore, changes in USP25 expression were monitored during Th17 differentiation, both in vivo and in vitro. Results USP25−/− mice with anti-GBM GN exhibited accelerated renal function deterioration, increased infiltration of Th1 and Th17 cells, and elevated RORγt transcription. In vitro experiments demonstrated that USP25−/− CD4+ T lymphocytes had a higher proportion for Th17 cell differentiation and exhibited higher RORγt levels upon stimulation. Wild-type mice with anti-GBM GN showed higher USP25 levels compared to healthy mice, and a positive correlation was observed between USP25 levels and Th17 cell counts. Similar trends were observed in vitro. Conclusion USP25 plays a crucial role in mitigating renal histopathological and functional damage during anti-GBM GN in mice. This protective effect is primarily attributed to USP25’s ability to inhibit the differentiation of naïve CD4+ T cells into Th17 cells. The underlying mechanism may involve the downregulation of RORγt. Additionally, during increased inflammatory responses or Th17 cell differentiation, USP25 expression is activated, forming a negative feedback regulatory loop that attenuates immune activation.

#2968 PROGNOSIS OF CRESCENTIC GLOMERULONEPHRITIS IN ADULTS

Abstract Background and Aims Crescentic glomerulonephritis (C-GN) is characterized by severe glomerular inflammation and injury that leads to crescent formation, rapid loss of kidney function and severe prognosis in absence of prompt immunosuppressive therapy. Depending on the histological findings, there are three main types of C-GN: anti-glomerular basement membrane antibody GN (anti-GBM GN), immune complex GN, and pauci-immune GN. This study aims to assess whether the kidney and vital outcome are different among the three histologic types of crescentic GN. Method This unicentric, retrospective study included seventy-six subjects [50% males, 55 (95%CI 52 to 60) years; eGFR 9.6 (95%CI 7.8-13.7) mL/min and proteinuria 1.9 (95%CI 1.5 to 2.6) g/g] that had undergone a kidney biopsy between 1st January 2008 and 31st December 2017 and had a histologic diagnosis of crescentic glomerulonephritis (crescent formation in more than 50% of the glomeruli). The subjects were followed for a mean of 47.6 (95%CI 33.5 to 61.6) months. Primary endpoints were the need of renal replacement therapy initiation (RRT) and all cause death. Kaplan-Meier method was used to evaluate kidney and patients’ survival and variables related to kidney and vital outcome were evaluated by multivariate Cox proportional hazard modelling. Patients were stratified in three groups according to the type of C-GN: pauci-immune GN (n=58 pts.), anti-GBM GN (n=9 pts.) and immune-complex GN (n=9 pts.). Results No demographic differences were found among the three groups. Except for a higher frequency of solid neoplasia in immune-complex GN group (2.7% vs 1.3% in pauci-immune GN vs. 0% in anti-GBM GN; P = .001), no other differences regarding the clinical or laboratory data were identified. Immunosuppressive treatment was very frequent, in more than 80% of subjects, regardless of the group, corticotherapy and cyclophosphamide being the most common immunosuppressive agents. During the follow-up period, 54% of subjects needed RRT and 19.2% died. The frequency of RRT initiation or death was not different among the three groups (P = .9 and P = .4). The univariate time-dependent analysis showed similar survival times among the analysed groups (log rank =0.9) (Figure 1). In the multivariate analysis, the only independent predictor of RRT was lower baseline eGFR (OR 0.49 (95%CI 0.31 to 0.78), P = .03). Time to death did not differ among groups (log rank P = .4) (Figure 2). The only independent predictor of death was higher Charlson comorbidity score (OR 56.8 (95%CI 6.3 to 512), p<0.001) in the Cox analysis. Conclusion In this cohort of subjects with crescentic glomerulonephritis, although limited by the low number of subjects, the kidney and vital prognosis seem to be similar indifferent of the histologic type of crescentic glomerulonephritis.

#5861 NEW-ONSET OR EXACERBATIONS OF GLOMERULONEPHRITIS FOLLOWING SARSCOV2 VACCINE: A REVIEW OF THE LITERATURE

Abstract Background and Aims Following vaccination against SarsCoV2 several cases of new-onset glomerulonephritis or exacerbations of glomerular diseases have been reported [1, 2]. No literature review has been published yet on the subject. Method We searched for single case or case series through the PubMed portal search and through the abstract search submitted to the EDTA and the American Society of Nephrology in 2021 and 2022 (last view on the 15th of December 2022). Results A total of 138 cases were analyzed, of which 127 complete for all the variables. The mean age was 52.6±20.75 years (min 12, max 99), M/F 67/63. The majority of patients received mRNA vaccine (BNT16b2 Pfizer (n = 70, 51%), mRNA-1273 Moderna (n = 42, 30.7%), followed by AZD1222 AstraZeneca (n = 10, 7.3%) and Ad26.COV2.S Johnson & Johnson (n = 4, 2.9%). A minority of cases were associate with Covaxin and Sinovac (Figure 1). Most cases were reported from the European continent (39.4%, n = 54), followed by North America (35.8%, n = 49) and Asia (21.9%, n = 30). A minority of cases were reported from Australia and Central/South America. The onset of glomerulonephritis occurred after a mean of 17.8 days±22.82 (min 1, max 89). In 37.4% of cases (n = 49), glomerulonephritis occurred after the first dose, in 61.8% after the second (n = 81), only 1 case after the third one. Regarding mRNA vaccine, in most cases, the disease occurred after the second dose (n = 78, 70.9% of cases, p<0.001). Gross hematuria as the initial symptom was significantly related to mRNA vaccination (27/27 cases). 30 cases (24.8%) showed nephrotic syndrome at onset. The most prevalent diagnosis was IgA nephropathy (n = 36, 26.3%), followed by vasculitis (n = 33, 24%), Minimal Change Disease (n = 26, 19%), and membranous nephropathy (n = 14, 10.2%) (Figure 2). Interesting, 6 cases (4.4%) of anti-GBM GN were reported. Compared to patients with glomerulonephritis, those with systemic vasculitis were older (59.84±19.43 vs 49.21±21.21 years), with a slightly shorter onset time (14.9±12.67 days, vs 16.6±24.14 days). Both vasculitis and glomerulonephritis generally occurred more frequently following mRNA vaccination. For vasculitis, ANCA-MPO was more frequent (n = 15, 45.45%), followed by ANCA PR3 (n = 10, 30.3%), and finally IgA vasculitis (n = 3,9%). Two cases (6.06%) were ANCA negative. New-onset glomerulonephritis accounted for 78.8% (n = 108), while relapses accounted for 21.2% (n = 29). There was no significant difference between the type of vaccine and de-novo or relapse glomerulonephritis. Patients were treated with steroid only (43.4%, n = 56), steroid and immunosuppressant (n = 21,16.3%), rituximab alone or in combination (n = 26, 20.15%), conservative therapy (24, 18.6%). 6 patients (4.4%) underwent dialysis, 2.9% (n = 4) received plasmapheresis. 80 patients (69%) responded effectively to therapy, achieving complete remission, 19% (n = 22) achieved partial remission, while 2.1% (n = 14) did not respond to therapy. Evolution towards ESKD occurred in 11 cases (8%). Conclusion New-onset glomerulonephritis or exacerbations of glomerular diseases that were in remission is a possible complication of SarsCov2 vaccination. Most patients received mRNA vaccine; more than half of the patient developed or worsened the GN after the second dose.

Laminin-521 is a Novel Target of Autoantibodies Associated with Lung Hemorrhage in Anti-GBM Disease.

Antiglomerular basement membrane (anti-GBM) disease is characterized by GN and often pulmonary hemorrhage, mediated by autoantibodies that typically recognize cryptic epitopes within α345(IV) collagen-a major component of the glomerular and alveolar basement membranes. Laminin-521 is another major GBM component and a proven target of pathogenic antibodies mediating GN in animal models. Whether laminin-521 is a target of autoimmunity in human anti-GBM disease is not yet known. A retrospective study of circulating autoantibodies from 101 patients with anti-GBM/Goodpasture's disease and 85 controls used a solid-phase immunoassay to measure IgG binding to human recombinant laminin-521 with native-like structure and activity. Circulating IgG autoantibodies binding to laminin-521 were found in about one third of patients with anti-GBM antibody GN, but were not detected in healthy controls or in patients with other glomerular diseases. Autoreactivity toward laminin-521 was significantly more common in patients with anti-GBM GN and lung hemorrhage, compared with those with kidney-limited disease (51.5% versus 23.5%, P=0.005). Antilaminin-521 autoantibodies were predominantly of IgG1 and IgG4 subclasses and significantly associated with lung hemorrhage (P=0.005), hemoptysis (P=0.008), and smoking (P=0.01), although not with proteinuria or serum creatinine at diagnosis. Besides α345(IV) collagen, laminin-521 is another major autoantigen targeted in anti-GBM disease. Autoantibodies to laminin-521 may have the potential to promote lung injury in anti-GBM disease by increasing the total amount of IgG bound to the alveolar basement membranes.

MO293NEUTROPHIL-TO-LYMPHOCYTE RATIO AND OUTCOME IN CRESCENTIC GLOMERULONEPHRITIS

Abstract Background and Aims Crescent formation is a nonspecific response to severe injury to the glomerular capillary wall, which may be seen with any form of inflammatory glomerulopathy. Despite improved therapeutic interventions, patients with crescentic glomerulonephritis (CGN) still have a severe kidney prognosis and high mortality. Since neutrophil-to-lymphocyte ratio (NLR) is an inflammatory marker linked to worse outcomes in patients with malignancies, chronic kidney disease, myocardial infarction, and other clinical settings, we aimed to assess if NLR can predict kidney outcome and mortality in subjects with CGN. Method Eighty-four adults with biopsy-proven CGN between 1st Jan. 2008 and 31st Dec. 2017 [age 56 (95%CI 53 to 59) years, 50% males, eGFR 9.3 (95%CI 7.8-12.7) mL/min] were retrospectively enrolled in this single-centre study. Subjects were followed for a median of 31 (95%CI 6 to 56) months, until 31st May 2018. Seven subjects with inadequate biopsy sample and insufficient data were excluded. Demographic (age, gender), clinical and laboratory data at the time of biopsy were obtained from medical records. Kaplan-Meier method was used to evaluate kidney and patient survival. Variables related to kidney outcome were evaluated in a multivariate Cox proportional hazard (CPH) model. According to median NLR value (4.3, 95%CI 3.5 to 5.2) subjects were clustered in low NLR group (≤4.3; n=38 pts.) and high NLR group (>4.3; n=38 pts.). The primary endpoints were time to renal replacement therapy (RRT) initiation and all-cause mortality. Results The most common CGN subtype was pauci-immune GN (76.3%; i.e. myeloperoxidase-ANCA vasculitis - 48.7%, PR3-ANCA vasculitis - 15.8% and ANCA-negative vasculitis - 11.8%) followed by. anti-GBM antibody and immune complex related GN, with similar frequencies (11.8% each). According to kidney biopsy (KB) findings, half of the subjects had fibro-cellular crescents (55.3%), while cellular and fibrous crescents were found in 35.5% and 9.2%, respectively. Almost all subjects received corticosteroids (97.4%) and 82.9% received cyclophosphamide. Baseline eGFR was lower in the high-NLR group (8.5 vs. 11.6 mL/min, p=0.04), but no other differences in laboratory findings at baseline between the two groups were found. In bivariate analysis, NLR was negatively associated with serum albumin (rs=-0.26, p=0.02). NLR was not associated with other inflammation markers, Charlson comorbidity score, nor with the type of crescents at KB. During the follow-up period 53.9% started RRT and 19.7% died. There were no differences regarding mortality between the two groups. The mean kidney survival time was 47.6 (95%CI 33.5, 61.7) months. Kidney survival at 12, 24, 48 and 60 months were 44, 41, 38, and 33% respectively. In univariate time-dependent analysis (Figure) patients with low-NLR (68.95%CI 48 to 88 months) had better kidney survival than those with high-NLR (25, 95%CI 13 to 38 months; log rank p=0.004). Moreover, the kidney survival advantage remained (OR 1.06, 95%CI 1.002 to 1.16) after adjusting for eGFR, proteinuria, C reactive protein, immunosuppressive treatment and CGN etiology. Lower eGFR-ul was also associated with poor kidney survival (OR 0.96, 95%CI 0.88 to 0.97). Conclusion In adults with biopsy-proven crescentic glomerulonephritis and advanced kidney function decline, a higher neutrophil-to-lymphocyte ratio seems to predict worse kidney survival, but not the risk of mortality.

Neutralization of IL-6 inhibits formation of autoreactive TH17 cells but does not prevent loss of renal function in experimental autoimmune glomerulonephritis

In anti-glomerular basement membrane glomerulonephritis (anti-GBM GN), antibodies and T cells directed against the Goodpasture antigen, the non-collagenous domain of the α3-chain of type IV collagen (α3(IV)NC1), provoke renal inflammation resulting in rapidly progressing crescentic GN. Interleukin 6 (IL-6) is a pleiotropic cytokine with both pro- and anti-inflammatory activities, and IL-6 blockade is successfully used for treatment of diseases associated with acute and chronic inflammation. However, the role of IL-6 in anti-GBM GN is unclear. Here, we use the mouse model of experimental autoimmune glomerulonephritis (EAG) to study the role of IL-6 in anti-GBM GN. DBA/1J mice were immunized with α3(IV)NC1 and developed fatal crescentic GN. Treatment of mice with neutralizing anti-IL-6 antibodies impaired the generation of α3(VI)NC1-specific TH1 and TH17 cells. However, despite lasting reduction of the TH17 cell response, antibody treatment did not prevent crescentic GN. Antibody treatment was also ineffective in a therapeutic setting with pre-existing autoantibodies and T cells. In conclusion, our results indicate that although the blockade of IL-6 impairs the development of autoimmunity against α3(VI)NC1, this treatment does not ameliorate crescentic GN both in a preemptive and a therapeutic approach.

Nephrotic syndrome due to minimal-change disease superimposed on anti-glomerular basement membrane antibody positive glomerulonephritis; a case report

BackgroundThe prognosis for renal function in anti-GBM glomerulonephritis (anti-GBM GN) is extremely poor, and when renal impairment progresses severely, it is difficult to expect improvement. In addition, it is also known that once the disease activity can be controlled by aggressive treatment, its recurrence is rare. We experienced an anti-GBM GN that improved from severe renal dysfunction and relapsed. A possible cause was the superimpose of nephrotic syndrome due to minimal change disease (MCD).Case presentationA 30-year-old man was admitted to our hospital because of general malaise, fever, oliguria and renal dysfunction. The patient’s laboratory data showed serum creatinine as high as 6.6 mg/dl, and severe inflammation (C-reactive protein 20.6 mg/dl). Anti-glomerular basement membrane antibody (anti-GBM Ab) was detected in his serum, which led to the diagnosis of anti-GBM GN. Treatment was initiated with high-dose glucocorticoid (GC) and plasma exchange therapy (PE), and the patient’s renal function and oliguria improved rapidly and he was discharged 40 days after admission. Renal biopsy findings showed cellular crescents associated with linear IgG depositions along the glomerular tufts compatible with anti-GBM GN, but only about one-third of the glomeruli was involved, suggesting that it still remains an early stage of the disease. However, 2 months after discharge, he had a relapse and was readmitted due to severe proteinuria with positive anti-GBM Ab. On the second admission, after high-dose GC and PE combined with intravenous cyclophosphamide, and remission was achieved. Despite the relatively minor renal biopsy findings, the patient showed rapid renal dysfunction and relatively rapid improvement with our treatment. Electron microscopy of the renal biopsy tissue showed significant foot process effacement on podocytes in the apparently normal glomeruli, without electron dense deposits.ConclusionOn the basis of clinical course and renal pathology, it is suggested that the present case was a rare complication of an early stage of anti-GBM GN and minimal change nephrotic syndrome. Although the simultaneous development of anti-GBM GN and MCD with anti-GBM antibody is unclear, it might have been precipitated by influenza infection or some unknown factor.

Experimental Antiglomerular Basement Membrane GN Induced by a Peptide from Actinomyces.

Antiglomerular basement membrane (anti-GBM) disease is associated with HLA-DRB1*1501 (the major predisposing genetic factor in the disease), with α3127-148 as a nephritogenic T and B cell epitope. Although the cause of disease remains unclear, the association of infections with anti-GBM disease has been long suspected. To investigate whether microbes might activate autoreactive T and B lymphocytes via molecular mimicry in anti-GBM disease, we used bioinformatic tools, including BLAST, SYFPEITHI, and ABCpred, for peptide searching and epitope prediction. We used sera from patients with anti-GBM disease to assess peptides recognized by antibodies, and immunized WKY rats and a humanized mouse model (HLA-DR15 transgenic mice) with each of the peptide candidates to assess pathogenicity. On the basis of the critical motif, the bioinformatic approach identified 36 microbial peptides that mimic human α3127-148. Circulating antibodies in sera from patients with anti-GBM recognized nine of them. One peptide, B7, derived from Actinomyces species, induced proteinuria, linear IgG deposition on the GBM, and crescent formation when injected into WKY rats. The antibodies to B7 also targeted human and rat α3127-148. B7 induced T cell activation from human α3127-148-immunized rats. T cell responses to B7 were detected in rats immunized by Actinomyces lysate proteins or recombinant proteins. We confirmed B7's pathogenicity in HLA-DR15 transgenic mice that developed kidney injury similar to that observed in α3135-145-immunized mice. Sera from patients with anti-GBM disease recognized microbial peptides identified through a bioinformatic approach, and a peptide from Actinomyces induced experimental anti-GBM GN by T and B cell crossreactivity. These studies demonstrate that anti-GBM disease may be initiated by immunization with a microbial peptide.

Rituximab use in adult glomerulopathies and its rationale

Glomerulopathies are one of the leading causes of end-stage renal disease. In the last years, clinical research has made significant contributions to the understanding of such conditions. Recently, rituximab (RTX) has appeared as a reasonably safe treatment. The Kidney Disease: Improving Global Outcomes guidelines (KDIGO) recommended RTX only as initial treatment in antineutrophil cytoplasm antibody associated vasculitis (AAV) and in non-responders patients with lupus nephritis (LN), but these guidelines have not been updated since 2012. Nowadays, RTX seems to be at least as effective as other immunosuppressive regimens in idiopathic membranous nephropathy (IMN). In minimal-change disease, (MCD) this drug might allow a long-lasting remission period in steroid-dependent or frequently relapsing patients. Preliminary results support the use of RTX in patients with pure membranous LN and immunoglobulin-mediated membranoproliferative glomerulonephritis (MPGN), but not in patients with class III/IV LN or complement-mediated MPGN. No conclusion can be drawn in idiopathic focal segmental glomerulosclerosis (FSGS) and anti-glomerular basement membrane antibody glomerulonephritis (anti-GBM GN) because studies are small, heterogeneous, and scarce. Lastly, immunosuppression including RTX is not particularly useful in IgA nephropathy. This review presents the general background, outcomes, and safety for RTX treatment in different glomerulopathies. In this regard, we describe randomized controlled trials (RCTs) performed in adults, whenever possible. A literature search was performed using clinicaltrials.gov and PubMed.

A Modified Peptide Derived from Goodpasture Autoantigen Arrested and Attenuated Kidney Injuries in a Rat Model of Anti-GBM Glomerulonephritis.

In Goodpasture disease, the noncollagenous domain 1 of the α3 chain (α3NC1) of type IV collagen is the main target antigen of antibodies against glomerular basement membrane (GBM). We previously identified a nephritogenic epitope, P14 (α3127-148), that could induce crescentic nephritis in WKY rats, and defined its core motif. Designing a modified peptide, replacing critical pathogenic residues with nonpathogenic ones (on the basis of homologous regions in α1NC1 chain of type IV collagen, known to be nonpathogenic), might provide a therapeutic option for anti-GBM GN. We synthesized a modified peptide, replacing a single amino acid, and injected it into α3-P14-immunized rats from day 0 (the early-treatment group) or a later-treatment group (from days 17 to 21). A scrambled peptide administrated with the same protocol served as a control. The modified peptide, but not the scrambled peptide, attenuated anti-GBM GN in both treatment groups, and halted further crescent formation even after disease onset. Kidneys from the modified peptide-treated rats exhibited reductions in IgG deposits, complement activation, and infiltration by T cells and macrophages. Treatment also resulted in an anti-inflammatory cytokine profile versus a proinflammatory profile for animals not receiving the modified peptide; it also reduced α3-P14-specific T cell activation, modulated T cell differentiation by decreasing Th17 cells and enhancing the ratio of Treg/Th17 cells, and inhibited binding of α3-P14 to antibodies and MHC II molecules. A modified peptide involving alteration of a critical motif in a nephritogenic T cell epitope alleviated anti-GBM GN in a rat model. Our findings may provide insights into an immunotherapeutic approach for autoimmune kidney disorders such as Goodpasture disease.

SAT-014 Group 1 innate lymphoid cells and their inhibition by peroxisome proliferator-activated receptor alpha in experimental anti-glomerular basement membrane glomerulonephritis

Innate lymphoid cells (ILCs), a recently discovered group of immune cells, are classified into group 1, group 2 and group 3 ILCs based on their phenotypic and functional characteristics of Th1, Th2 and Th17, respectively. ILCs play an important role in the early effector cytokine-mediated response and do not express phenotypic markers of myeloid or dendritic cells. In Wistar Kyoto rats, CD8+ non-T lymphocytes (CD8+Lym) infiltrate into glomeruli with macrophages (Mφ) during the development of anti-glomerular basement membrane glomerulonephritis (anti-GBM GN).

Predicting Outcome in Patients with Anti-GBM Glomerulonephritis.

Large studies on long-term kidney outcome in patients with anti-glomerular basement membrane (anti-GBM) GN are lacking. This study aimed to identify clinical and histopathologic parameters that predict kidney outcome in these patients. This retrospective analysis included a total of 123 patients with anti-GBM GN between 1986 and 2015 from six centers worldwide. Their kidney biopsy samples were classified according to the histopathologic classification for ANCA-associated GN. Clinical data such as details of treatment were retrieved from clinical records. The primary outcome parameter was the occurrence of ESRD. Kidney survival was analyzed using the log-rank test and Cox regression analyses. The 5-year kidney survival rate was 34%, with an improved rate observed among patients diagnosed after 2007 (P=0.01). In patients with anti-GBM GN, histopathologic class and kidney survival were associated (P<0.001). Only one of 15 patients with a focal class biopsy sample (≥50% normal glomeruli) developed ESRD. Patients with a sclerotic class biopsy sample (≥50% globally sclerotic glomeruli) and patients with 100% cellular crescents did not recover from dialysis dependency at presentation. In multivariable analysis, dialysis dependency at presentation (hazard ratio [HR], 3.17; 95% confidence interval [95% CI], 1.59 to 6.32), percentage of normal glomeruli (HR, 0.97; 95% CI, 0.95 to 0.99), and extent of interstitial infiltrate (HR, 2.02; 95% CI, 1.17 to 3.50) were predictors of ESRD during follow-up. Dialysis dependency, low percentage of normal glomeruli, and large extent of interstitial infiltrate are associated with poor kidney outcome in anti-GBM GN. Kidney outcome has improved during recent years; the success rate doubled after 2007. This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2017_11_21_CJASNPodcast_18_1_v.mp3.

Aliskiren Regulates Neonatal Fc Receptor and IgG Metabolism with Attenuation of Anti-GBM Glomerulonephritis in Mice

Background: Renin, in addition to its activation of the renin-angiotensin system, binds to the (pro)renin receptor (PRR) and triggers inflammatory and fibrogenic signaling in tissue. In addition, aliskiren, a direct renin inhibitor, has been shown to affect IgG metabolism by altering PRR and neonatal Fc receptors (FcRns). Methods: We investigated the effect of aliskiren on proteinuria, glomerular extracellular matrix, expressions of fibronectin, transforming growth factor β1 (TGF-β1), PRR, FcRn and renal metabolism of IgG in a mice model of anti-glomerular basement membrane glomerulonephritis (anti-GBM GN). Results: IgG deposition and expressions of FcRn and PRR were enhanced at glomeruli and urinary IgG levels increased in anti-GBM GN. Aliskiren attenuated anti-GBM GN with reduction of proteinuria and cortical expressions of fibronectin and TGF-β1. In addition, aliskiren suppressed the renal cortical expressions of FcRn and PRR. Aliskiren also reduced the glomerular IgG depositions and the urinary IgG levels albeit with increased circulating serum IgG levels. Conclusion: These results suggest that suppression of FcRn and PRR and regulation of IgG metabolism may be related to the attenuation of anti-GBM GN by aliskiren.

Cln 3-requiring 9 is a negative regulator of Th17 pathway-driven inflammation in anti-glomerular basement membrane glomerulonephritis.

T helper 17 (Th17) lymphocytes promote renal inflammation in anti-glomerular basement membrane glomerulonephritis (anti-GBM GN), and signal transducer and activator of transcription 3 (STAT3) mediates activation of Th17 lymphocytes by IL-6 and transforming growth factor-β (TGF-β). Cln 3-requiring 9 (Ctr9), a subunit of RNA polymerase-associated factor complex (PAFc), regulates the transcription of IL-6/STAT3-dependent genes. Here, we investigated the role of Ctr9 in regulating Th17-driven inflammation in anti-GBM GN. In mice, STAT3β or IL-17 knockout ameliorated anti-GBM autoantibody-induced renal injury. This phenomenon was associated with decreases in retinoic acid receptor-related orphan receptor γt (RORγt), IL-17, phosphorylated STAT3, and proinflammatory cytokines. Compared with wild-type mice, Ctr9 increased in both STAT3β(-/-) and IL-17(-/-) mice injected with anti-GBM IgG, showing a negative correlation with Th17-related transcripts. Small interfering RNA (siRNA)-mediated knockdown of Ctr9 in intrarenal lymphocytes further upregulated Th17-related transcripts, consistent with repression of Th17 differentiation by Ctr9. Interestingly, Ctr9 was also expressed in human and mouse mesangial cells and downregulated in response to anti-GBM IgG or to TGF-β plus IL-17. Ctr9 in mesangial cells was even more repressed in the presence of both anti-GBM IgG and Th17-activating cytokines. Consistent with these findings, renal biopsies obtained from patients with anti-GBM GN showed consistent downregulation of Ctr9 and upregulation of phosphorylated STAT3 and IL-17 in the glomerulus. We conclude that Ctr9 is a negative regulator of Th17 differentiation in anti-GBM GN and repressed by anti-GBM IgG and IL-17 in mesangial cells.

Pauci-Immune Crescentic Glomerulonephritis: An ANCA-Associated Vasculitis.

Rapidly progressive glomerulonephritis (RPGN) is a syndrome signified by a precipitous loss of renal function, with features of glomerulonephritis including dysmorphic erythrocyturia and glomerular proteinuria. RPGN is associated with extensive crescent formation, and, thus, the clinical term RPGN is often used interchangeably with the pathologic term crescentic glomerulonephritis (CGN). From an immunopathologic standpoint, primary RPGN is divided into pauci-immune GN (PICG), anti-GBM GN, and immune complex GN. PICG, the most common etiology of primary RPGN, refers to a necrotizing glomerulonephritis with few or no immune deposits by immunofluorescence (IF) or electron microscopy (EM). In most patients, pauci-immune CGN is a component of a systemic small vessel vasculitis such as granulomatosis with polyangiitis (GPA). Approximately 90% of patients with PICG have circulating ANCA antibodies, leading to the nomenclature ANCA-associated vasculitis (AAV). Recent research has identified several other antibodies associated with PICG, which is now understood to be a complex spectrum of disease with considerable overlap in terms of clinical phenotype and outcomes. In addition, several genetic and environmental factors have recently been implicated in the pathogenesis of this disorder. With new prognostic classifications, enhanced understanding of immunopathologic mechanisms, and novel treatment paradigms, clinical and experimental interest in PICG remains high.

Galectin-9 ameliorates anti-GBM glomerulonephritis by inhibiting Th1 and Th17 immune responses in mice

Antiglomerular basement membrane glomerulonephritis (anti-GBM GN) is a Th1- and Th17-predominant autoimmune disease. Galectin-9 (Gal-9), identified as the ligand of Tim-3, functions in diverse biological processes and leads to the apoptosis of CD4(+)Tim-3(+) T cells. It is still unclear how Gal-9 regulates the functions of Th1 and Th17 cells and prevents renal injury in anti-GBM GN. In this study, Gal-9 was administered to anti-GBM GN mice for 7 days. We found that Gal-9 retarded the increase of Scr, ameliorated renal tubular injury, and reduced the formation of crescents. The infiltration of Th1 and Th17 cells into the spleen and kidneys significantly decreased in Gal-9-treated nephritic mice. The reduced infiltration of Th1 and Th17 cells might be associated with the downregulation of CCL-20, CXCL-9, and CXCL-10 mRNAs in the kidney. In parallel, the blood levels of IFN-γ and IL-17A declined in Gal-9-treated nephritic mice at days 21 and 28. In addition, an enhanced Th2 cell-mediated immune response was observed in the kidneys of nephritic mice after a 7-day injection of Gal-9. In conclusion, the protective role of Gal-9 in anti-GBM GN is associated with the inhibition of Th1 and Th17 cell-mediated immune responses and enhanced Th2 immunity in the kidney.

Decreased urinary calbindin 1 levels in proteinuric rats and humans with distal nephron segment injuries

Several proteins have been proposed as new urinary biomarkers of kidney injuries, but they are not always capable of identifying the kidney nephron segment that has been injured. Since calbindin 1 protein is exclusively localized in the kidney distal nephron segment, it is presumed that its expression is altered during distal nephron segment injuries, resulting in changes in its urinary excretion. Calbindin 1 expression in normal rat kidneys was compared with that in the kidneys of rats that had suffered distal nephron segment injuries (unilateral ureteral obstruction [UUO] or anti-glomerular basement membrane glomerulonephritis [anti-GBM GN]) using immunohistochemical examinations and real-time polymerase chain reaction. The urinary calbindin 1 protein concentration of normal rats was also compared with that of anti-GBM GN rats and of cisplatin nephropathy rats using Western blotting. We also compared the kidney and urinary calbindin 1 protein concentrations of normal human subjects with those of proteinuric patients [immunoglobulin (Ig)A nephropathy; IgAN] with distal nephron segment injuries. Calbindin 1 mRNA expression in the renal cortices and calbindin 1 protein expression in the kidney distal nephron segments were decreased in the UUO and anti-GBM GN rat kidneys. The urinary calbindin 1 protein levels of the anti-GBM GN rats were also markedly decreased, whereas those of the cisplatin nephropathy rats were slightly decreased. The human IgAN patients displayed decreased renal calbindin 1 protein expression in their dilated distal tubules, and some patients displayed decreased urinary calbindin 1 levels. Since it has been demonstrated that decreased urinary calbindin 1 levels are indicative of decreased calbindin 1 kidney expression due to distal nephron segment injuries, calbindin 1 might be a useful urinary biomarker for identifying distal nephron segment injuries.

A case of triple pathology: seronegative anti-glomerular basement membrane antibody-mediated glomerulonephritis and membranous nephropathy in a patient with underlying diabetic kidney disease.

In diabetic patients with acute kidney injury (AKI), kidney biopsy often reveals non-diabetic kidney pathology. This case describes a patient with known Type 1 diabetes who presented with AKI, nephrotic syndrome and haematuria. Combination pathology of seronegative anti-glomerular basement membrane antibody-mediated glomerulonephritis (anti-GBM GN), membranous nephropathy (MN) and diabetic nephropathy (DN) was demonstrated. Strong linear GBM IgG-staining on biopsy with crescentic GN and clinical AKI led to a diagnosis of anti-GBM GN, although serum antibodies were not detectable. Features of DN, Kimmelstiel–Wilson nodules and albumin staining were also present, along with features of MN, such as subepithelial deposits on electron microscopy. Despite treatment with immunosuppression and plasmapheresis, there was no recovery of kidney function. Coexisting anti-GBM GN and MN is well recognized, but the concurrent diagnosis with DN has not been described.

Serum-Starved Adipose-Derived Stromal Cells Ameliorate Crescentic GN by Promoting Immunoregulatory Macrophages

Mesenchymal stromal cells (MSCs) derived from adipose tissue have immunomodulatory effects, suggesting that they may have therapeutic potential for crescentic GN. Here, we systemically administered adipose-derived stromal cells (ASCs) in a rat model of anti-glomerular basement membrane (anti-GBM) disease and found that this treatment protected against renal injury and decreased proteinuria, crescent formation, and infiltration by glomerular leukocytes, including neutrophils, CD8(+) T cells, and CD68(+) macrophages. Interestingly, ASCs cultured under low-serum conditions (LASCs), but not bone marrow-derived MSCs (BM-MSCs), increased the number of immunoregulatory CD163(+) macrophages in diseased glomeruli. Macrophages cocultured with ASCs, but not with BM-MSCs, adopted an immunoregulatory phenotype. Notably, LASCs polarized macrophages into CD163(+) immunoregulatory cells associated with IL-10 production more efficiently than ASCs cultured under high-serum conditions. Pharmaceutical ablation of PGE2 production, blocking the EP4 receptor, or neutralizing IL-6 in the coculture medium all significantly reversed this LASC-induced conversion of macrophages. Furthermore, pretreating LASCs with aspirin or cyclooxygenase-2 inhibitors impaired the ability of LASCs to ameliorate nephritogenic IgG-mediated renal injury. Taken together, these results suggest that LASCs exert renoprotective effects in anti-GBM GN by promoting the phenotypic conversion of macrophages to immunoregulatory cells, suggesting that LASC transfer may represent a therapeutic strategy for crescentic GN.