MicroRNA-126 in dogs with immune complex-mediated glomerulonephritis.

BACKGROUND: Most proteinuric dogs with naturally occurring chronic kidney disease have amyloidosis (AMYL), glomerulosclerosis (GS), or immune complex-mediated glomerulonephritis (ICGN), each with different treatment and prognosis. A noninvasive and disease-specific biomarker is lacking. HYPOTHESIS: We hypothesized that the expression pattern of biofluid microRNA (miRNAs and miRs) would correlate with disease progression and categorization. ANIMALS: Archived serum and urine samples from 18 dogs with glomerular disease and 6 clinically healthy dogs; archived urine samples from 49 dogs with glomerular disease and 13 clinically healthy dogs. METHODS: Retrospective study. Archived biofluid samples from adult dogs with biopsy-confirmed glomerular disease submitted to the International Veterinary Renal Pathology Service between 2008 and 2016 were selected. Serum and urinary miRNAs were isolated and profiled using RNA sequencing. Urinary miR-126, miR-21, miR-182, and miR-486 were quantified using quantitative reverse transcription PCR. RESULTS: When comparing more advanced disease with earlier disease, no serum miRNAs were differentially expressed, but urinary miR-21 and miR-182 were 1.63 (95% CI: .86-3.1) and 1.45 (95% CI: .82-2.6) times higher in azotemic dogs, respectively (adjusted P < .05) and weakly correlated with tubulointerstitial fibrosis (miR-21: r = .32, P = .03; miR-182: r = .28, P = .05). Expression of urinary miR-126 was 10.5 (95% CI: 4.1-26.7), 28.9 (95% CI: 10.5-79.8), and 126.2 (95% CI: 44.7-356.3) times higher in dogs with ICGN compared with dogs with GS, AMYL, and healthy controls, respectively (P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: The miR-126 could help identify dogs that might benefit from immunosuppressive therapy in the absence of a biopsy. MiR-21 and miR-182 are potential markers of disease severity and fibrosis.

STING1 deficiency ameliorates immune-mediated crescentic glomerulonephritis in mice.

Rapidly progressive/crescentic glomerulonephritis (RPGN/CGN) involves the formation of glomerular crescents by maladaptive differentiation of parietal epithelial cells that leads to rapid loss of renal function. The molecular mechanisms of crescent formation are poorly understood. Therefore, new insights into molecular mechanisms could identify alternative therapeutic targets for RPGN/CGN. Analysis of kidney biopsies from patients with RPGN revealed increased interstitial, glomerular, and tubular expression of STING1, an accessory protein of the c-GAS-dependent DNA-sensing pathway, which was also observed in murine nephrotoxic nephritis induced by an anti-GBM antibody. STING1 was expressed by key cell types involved in RPGN and crescent formation such as glomerular parietal epithelial cells, and tubular cells as well as by inflammation accessory cells. In functional in vivo studies, Sting1-/- mice with nephrotoxic nephritis had lower kidney cytokine expression, milder kidney infiltration by innate and adaptive immune cells, and decreased disease severity. Pharmacological STING1 inhibition mirrored these findings. Direct STING1 agonism in parietal and tubular cells activated the NF-κB-dependent cytokine response and the interferon-induced genes (ISGs) program. These responses were also triggered in a STING1-dependent manner by the pro-inflammatory cytokine TWEAK. These results identify STING1 activation as a pathological mechanism in RPGN/CGN and TWEAK as an activator of STING1. Pharmacological strategies targeting STING1, or upstream regulators may therefore be potential alternatives to treat RPGN. © 2023 The Pathological Society of Great Britain and Ireland.

Misdiagnosed Branchio-Oto-Renal syndrome presenting as proteinuria and renal insufficiency with insidious signs since early childhood: a report of three cases.

BACKGROUND: Branchio-oto-renal (BOR) syndrome is an inherited multi-systemic disorder. Auricular and branchial signs are highly suggestive of BOR syndrome but often develop insidiously, leading to a remarkable misdiagnosis rate. Unlike severe morphological abnormalities of kidneys, knowledge of glomerular involvement in BOR syndrome were limited. CASE PRESENTATION: Three cases, aged 8 ~ 9 years, visited pediatric nephrology department mainly for proteinuria and renal insufficiency, with 24-h proteinuria of 23.8 ~ 68.9 mg/kg and estimated glomerular filtration rate of 8.9 ~ 36.0 mL/min/1.73m2. Moderate-to-severe albuminuria was detected in case 1, while mixed proteinuria was detected in case 2 and 3. Insidious auricular and branchial fistulas were noticed, all developing since early childhood but being neglected previously. EYA1 variants were confirmed by genetic testing in all cases. Delay in diagnosis was 8 ~ 9 years since extra-renal appearances, and 0 ~ 6 years since renal abnormalities. In case 1, therapy of glucocorticoid and immunosuppressive agents to accompanying immune-complex mediated glomerulonephritis was unsatisfying. CONCLUSIONS: BOR syndrome is a rare cause of proteinuria and abnormal kidney function and easily missed, thus requiring more awareness. Careful medical history taking and physical examination are essential to early diagnosis. Massive proteinuria was occasionally seen in BOR syndrome, which might be related to immune complex deposits. A novel pathogenic variant (NM_000503.6 (EYA1): c.1171delT p.Ser391fs*9) was firstly reported.

Coronavirus disease 2019-associated nephropathy in an African American patient: a case report and review of the literature.

BACKGROUND: Acute kidney injury is now recognized as a common complication of coronavirus disease 2019, affecting up to 46% of patients, with acute tubular injury as the most common etiology. Recently, we have seen an increase in cases of collapsing glomerulonephritis in patients with coronavirus disease 2019, also known as coronavirus disease 2019-associated nephropathy. It has been noted to be seen with a higher incidence in African American patients who are carriers of the APOL1 variant allele. CASE PRESENTATION: A 47-year-old African American male with a past medical history of asthma presented to the emergency department with complaints of intermittent chest pain, shortness of breath, and worsening confusion. On admission, he was found to be hemodynamically stable, but labs were significant for elevated creatinine and blood urea nitrogen, signifying acute kidney injury. He was admitted and taken for emergent dialysis. During his hospitalization, he was found to be positive for coronavirus disease 2019. Renal biopsy was done, which showed collapsing glomerulopathy, and the patient continues to require outpatient dialysis after discharge. CONCLUSION: Collapsing glomerulonephritis has emerged as a complication in patients with coronavirus disease 2019. This condition should be particularly suspected in African American patients who present with acute kidney injury, nephrotic-range proteinuria, and who are positive for coronavirus disease 2019. Current treatment options are limited to supportive treatment and renal replacement therapy. More clinical cases and trials are needed to better understand and improve therapeutic outcomes in these patients.

Differential expression profile of urinary exosomal microRNAs in patients with mesangial proliferative glomerulonephritis.

OBJECTIVE: To investigate the differential expression profile of urinary exosomal microRNA (miRNA) in patients with mesangial proliferative glomerulonephritis (MsPGN) and healthy controls and their potential role in the pathogenesis of MsPGN. METHODS: Urine specimens were collected from five MsPGN patients and five healthy controls, and differentially expressed miRNAs were screened using high-throughput sequencing technology. The sequenced urinary exosomal miRNAs were further investigated by quantitative real-time polymerase chain reaction (qRT-PCR) in a validation cohort (16 MsPGN patients and 16 healthy controls). Correlation and receiver operating characteristic (ROC) curve analyses were used to determine the association between clinical features and miRNA expression in MsPGN. Finally, fluorescence in situ hybridization was performed to detect miRNA expression in the renal tissues of MsPGN patients. RESULTS: Five differentially expressed miRNAs (miR-125b-2-3p, miR-205-5p, let-7b-3p, miR-1262, and miR-548o-3p) were identified by qRT-PCR. The expression of these miRNAs correlated with ACR, 24hUpro, mAlb, UA, and combined yielded a ROC curve area of 0.916 in discriminating MsPGN patients from the controls. In addition, the expression of miR-205-5p, let-7b-3p, miR-1262, and miR-548o-3p was elevated in the MsPGN patient group, and miR-125b-2-3p was decreased in the MsPGN patient group. CONCLUSIONS: Differential expression of urinary exosomal miRNAs may pose a risk of MsPGN and help distinguish MsPGN patients from controls. Certain miRNA expressions may be associated with disease progression, contributing to the epigenetic understanding of the pathophysiology of MsPGN.

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.

High-throughput data on circular RNA reveal novel insights into chronic glomerulonephritis.

BACKGROUND: Circular RNAs (circRNAs), a unique novel type of RNA, have been widely reported to be involved in physiologic and pathologic processes in humans. However, the exact molecular pathogenesis of circRNAs in chronic glomerulonephritis (CGN) is far from clear. OBJECTIVE: This paper aims to evaluate the specific expression profile of circRNAs in renal cortex tissues from Adriamycin-induced CGN rats. METHODS: CircRNAs were screened in renal cortex tissues from 3 CGN rats and 3 control rats by using high-throughput sequencing (HTS). Then, 4 circRNAs were selected randomly for verification by quantitative real-time polymerase chain reaction (qRT-PCR). In addition, the differentially expressed (DE) circRNAs were analyzed by bioinformatics methods. RESULTS: In total, 31 significantly DE circRNAs were identified, which revealed their potential roles in CGN; in particular, we found that 4 confirmed altered circRNAs (rno-circ-RNAs 689, 3217, 1327, and 5001) might play important roles in the development of CGN. CONCLUSION: This study reveals a cluster of circRNAs that are DE in Adriamycin-induced CGN rats, which brings us closer to understanding the pathogenic mechanisms and may provide new potential targets for clinical treatment.

Generation of Conditional KO Mice of CCN2 and Its Function in the Kidney.

CCN2 has been shown to be closely involved in the progression of renal fibrosis, indicating the potential of CCN2 inhibition as a therapeutic target. Although the examination of the renal disease phenotypes of adult CCN2 knockout mice has yielded valuable scientific insights, perinatal death has limited studies of CCN2 in vivo. Conditional knockout technology has become widely used to delete genes in the target cell populations or time points using cell-specific Cre recombinase-expressing mice. Therefore, several lines of CCN2-floxed mice have been developed to assess the functional role of CCN2 in adult mice.CCN2 levels are elevated in renal fibrosis and proliferative glomerulonephritis, making them suitable disease models for assessing the effects of CCN2 deletion on the kidney. Renal fibrosis is characterized by glomerulosclerosis and tubulointerstitial fibrosis and transforming growth factor-ß. CCN2 is increased in fibrosis and modulates a number of downstream signaling pathways involved in the fibrogenic properties of TGF-ß. Unilateral ureteral obstruction is one of the most widely used models of renal tubulointerstitial fibrosis. In addition, anti-glomerular basement membrane antibody glomerulonephritis has become the most widely used model for evaluating the effect of increased renal CCN2 expression. Herein, we describe the construction of CCN2-floxed mice and inducible systemic CCN2 conditional knockout mice and methods for the operation of unilateral ureteral obstruction and the induction of anti-glomerular basement membrane antibody glomerulonephritis.

Causal relationship between gut microbiota and kidney diseases: a two-sample Mendelian randomization study.

Background: The interplay between gut microbiome genera and inflammatory kidney-related diseases, such as nephrotic syndrome, glomerulonephritis, tubulo-interstitial nephritis, and chronic kidney disease, has been observed. However, the causal relationships between specific bacterial genera and these renal diseases have not been fully elucidated. Objective: To investigate the potential causal links between different genera of the gut microbiome and the susceptibility to various renal conditions utilizing two-sample Mendelian randomization (MR) analyses. Materials and methods: Genome-wide association study (GWAS) summary statistics of gut microbiota and inflammatory kidney-related diseases were obtained from published GWASs. Two-sample MR analyses were conducted using methods including inverse-variance weighted (IVW), MR Egger, and others to identify potential causal links between gut microbial genera and renal conditions. Sensitivity analyses, including Cochran's Q test and the MR-PRESSO global test, were performed to validate the robustness of the results and detect horizontal pleiotropy. In addition, a reverse MR analysis was conducted to assess reverse causation possibilities. Results: By synthesizing insights from both primary and sensitivity analyses, this study unveiled critical associations of 12 bacterial genera with nephrotic syndrome, 7 bacterial genera with membranous nephropathy, 3 bacterial genera with glomerulonephritis, 4 bacterial genera with acute tubulo-interstitial nephritis, 6 bacterial genera with chronic tubulo-interstitial nephritis, and 7 bacterial genera with chronic kidney disease. Various genera were pinpointed as having either positive or negative causal relationships with these renal conditions, as evidenced by specific ranges of IVW-OR values (all P< 0.05). The congruence of the sensitivity analyses bolstered the primary findings, displaying no marked heterogeneity or horizontal pleiotropy. Notably, the reverse MR analysis with nephritis as the exposure did not reveal any causal relationships, thereby strengthening the resilience and validity of the primary associations. Conclusion: This study explored the causal associations between several gut microbial genera and the risk of several inflammatory kidney-related diseases, uncovering several associations between specific gut microbial genera and nephrotic syndrome, membranous nephropathy, glomerulonephritis, tubulo-interstitial nephritis, and chronic kidney disease. These findings enhance our understanding of the complex interplay between the gut microbiome and kidney diseases, and they will be beneficial for early diagnosis and subsequent treatment.

Identification of Unique Genetic Biomarkers of Various Subtypes of Glomerulonephritis Using Machine Learning and Deep Learning.

(1) Objective: Identification of potential genetic biomarkers for various glomerulonephritis (GN) subtypes and discovering the molecular mechanisms of GN. (2) Methods: four microarray datasets of GN were downloaded from Gene Expression Omnibus (GEO) database and merged to obtain the gene expression profiles of eight GN subtypes. Then, differentially expressed immune-related genes (DIRGs) were identified to explore the molecular mechanisms of GN, and single-sample gene set enrichment analysis (ssGSEA) was performed to discover the abnormal inflammation in GN. In addition, a nomogram model was generated using the R package "glmnet", and the calibration curve was plotted to evaluate the predictive power of the nomogram model. Finally, deep learning (DL) based on a multilayer perceptron (MLP) network was performed to explore the characteristic genes for GN. (3) Results: we screened out 274 common up-regulated or down-regulated DIRGs in the glomeruli and tubulointerstitium. These DIRGs are mainly involved in T-cell differentiation, the RAS signaling pathway, and the MAPK signaling pathway. ssGSEA indicates that there is a significant increase in DC (dendritic cells) and macrophages, and a significant decrease in neutrophils and NKT cells in glomeruli, while monocytes and NK cells are increased in tubulointerstitium. A nomogram model was constructed to predict GN based on 7 DIRGs, and 20 DIRGs of each subtype of GN in glomeruli and tubulointerstitium were selected as characteristic genes. (4) Conclusions: this study reveals that the DIRGs are closely related to the pathogenesis of GN and could serve as genetic biomarkers in GN. DL further identified the characteristic genes that are essential to define the pathogenesis of GN and develop targeted therapies for eight GN subtypes.

Implantation of dedifferentiated fat cells ameliorated antineutrophil cytoplasmic antibody glomerulonephritis by immunosuppression and increases in tumor necrosis factor-stimulated gene-6.

INTRODUCTION: The implantation of dedifferentiated fat (DFAT) cells has been shown to exert immunosuppressive effects. To develop DFAT cell therapy for antineutrophil cytoplasmic antibody (ANCA) glomerulonephritis, the effects of the implantation of DFAT cells on ANCA glomerulonephritis were investigated in mice. METHODS: PKH26-labeled DFAT cells (105) were infused through the posterior orbital venous plexus to investigate delivery of DFAT cells in ICR mice. DFAT cells (105) were also implanted in SCG mice as a model for ANCA glomerulonephritis. Expression of tumor necrosis factor-stimulated gene-6 (TSG-6) mRNA and protein in kidney was evaluated, and the expression of microRNAs associated with TSG-6 in plasma, lung and kidney was analyzed. Expressions of CD44, prostaglandin (PG) E2, interleukin (IL)-10, IL-1ß, tumor necrosis factor (TNF)-α mRNAs, C-C motif chemokine ligand 17 (CCL-17) and monocyte chemoattractant protein (MCP)-1 proteins were measured in kidney from SCG mice implanted with DFAT cells. RESULTS: After their intravenous infusion, almost all DFAT cells were trapped in the lung and not delivered into the kidney. Implantation of DFAT cells in SCG mice suppressed glomerular crescent formation, decreased urinary protein excretions and increased expression of TSG-6 mRNA, protein and immunostaining in kidney from these mice. Increased expression of microRNA 23b-3p in plasma, kidney and lung; decreased expression of CD44 mRNA; and increased expression of PGE2 and IL-10 mRNAs were also observed in kidney from these mice. Implantation of DFAT cells also decreased the expression of TNF-α and MCP-1 proteins and increased that of CCL-17 protein in kidney from the SCG mice. Survival rates were higher in SCG mice implanted with DFAT cells than in SCG mice without implantation. CONCLUSION: Mechanisms underlying the effects of improvement of ANCA glomerulonephritis are associated with immunosuppressive effects by TSG-6 and the transition of M1-M2 macrophages, suggesting that implantation of DFAT cells may become a cell therapy for ANCA glomerulonephritis.

Pathophysiology and system biology of rat c-BSA induced immune complex glomerulonephritis and pathway comparison with human gene sequencing data.

Immune-complex glomerulonephritis (ICGN) is a major cause of nephrotic syndrome in adults and children. Cationic BSA (c-BSA) intravenous injection could produce significant albuminuria within a short time, and is a suitable in vivo experimental animal model to investigate the pathophysiology of ICGN and for drug screening, but lack of thorough study to clarify its dynamic pathophysiological alteration so far, as well as detailed changes in mRNA and LncRNA levels. The purpose of this study is to investigate the dynamic alteration in renal function, lipid metabolism and histopathology during the progress of c-BSA induced ICGN. RNA sequencing was used to identified differentially expressed mRNA and LncRNA in kidney cortex of ICGN. Results demonstrated that c-BSA induced ICGN model could completely exhibit clinical features of immune-mediated nephrotic syndrome with gradual declining renal function, and increased albuminuria and deteriorated histopathological injuries. The correlation analysis suggested that complement activation was the most key element in mediating of ICGN. RNA sequencing using rat kidney tissues combined with Gene Expression Omnibus (GEO) data of human glomerulonephritis showed the most enriched KEGG pathways in ICGN were Toll-like receptor signaling pathway, B cell receptor and Focal adhesion. The differential lncRNAs in ICGN rats were also screened, and the lncRNA-mRNA co-expression network was constructed to clarify lncRNA role in molecular mechanism of ICGN progression. Their human homogenous lncRNAs were also identified, such as ST3GAL5-AS1 and DIO3OS, which provide the potential lncRNA targets to treat ICGN. All the differential LncRNAs in ICGN kidneys caused by MMF were also identified and provided another possible pharmacological mechanism of MMF through lncRNA regulation. In summary, the current study firstly described the dynamic physiological changes of c-BSA induced ICGN, identified most key KEGG pathways, and provided lncRNA-mRNA regulatory network in ICGN.

Genetic insight into primary glomerulonephritis.

Primary glomerulonephritis is a major global health concern and a disorder with significant heritable components. Rapid advances in sequencing technologies have led to genome-wide, high-throughput investigations of the genetic basis of complex human traits. Genetic studies have successfully mapped several susceptibility loci and disease-causing genes for different subtypes of primary glomerulonephritis. These studies have revealed that IgA nephropathy-associated genes have a highly complex, polygenic and pleiotropic genetic architecture and that genetic susceptibility to membranous nephropathy may be driven by a few large-effect loci. Furthermore, both susceptibility genes and high-penetrant gene mutations reportedly contribute to the development of the most heterogeneous phenotype of focal segmental glomerulosclerosis. The genetic heterogeneity between each glomerular disease type and within different populations has indicated disease-specific and ethnicity-specific underlying molecular mechanisms for the disorders. The findings from genome-wide association studies (GWAS) have mainly included variants on or near the major histocompatibility (MHC) loci, highlighting the molecular basis for the shared pathogenesis of the immune-mediated disease. Recent studies with increased sample sizes and higher resolutions of genome-wide imputation have provided novel insights into the pathogenesis of glomerular disorders. Further integration of results from genomic studies with functional genomics datasets can indicate novel targets for drug discovery as well as potential tools for patient diagnosis and stratification. However, larger GWASs and sequencing studies in independent cohorts and more standardized inclusion of phenotypes across studies are required for each subtype of glomerular disease.

Single-cell RNA Sequencing Identified Novel Nr4a1+ Ear2+ Anti-Inflammatory Macrophage Phenotype under Myeloid-TLR4 Dependent Regulation in Anti-Glomerular Basement Membrane (GBM) Crescentic Glomerulonephritis (cGN).

Previously, this study demonstrates the critical role of myeloid specific TLR4 in macrophage-mediated progressive renal injury in anti-glomerular basement membrane (anti-GBM) crescentic glomerulonephritis (cGN); however, the underlying mechanism remains largely unknown. In this study, single-cell RNA sequencing (scRNA-seq), pseudotime trajectories reconstruction, and motif enrichment analysis are used, and macrophage diversity in anti-GBM cGN under tight regulation of myeloid-TLR4 is uncovered. Most significantly, a myeloid-TLR4 deletion-induced novel reparative macrophage phenotype (Nr4a1+ Ear2+) with significant upregulated anti-inflammatory and tissue repair-related signaling is discovered, thereby suppressing the M1 proinflammatory responses in anti-GBM cGN. This is further demonstrated in vitro that deletion of TLR4 from bone marrow-derived macrophages (BMDMs) induces the Nr4a1/Ear2-expressing anti-inflammatory macrophages while blocking LPS-stimulated M1 proinflammatory responses. Mechanistically, activation of the Nr4a1/Ear2-axis is recognized as a key mechanism through which deletion of myeloid-TLR4 promotes the anti-inflammatory macrophage differentiation in vivo and in vitro. This is confirmed by specifically silencing macrophage Nr4a1 or Ear2 to reverse the anti-inflammatory effects on TLR4 deficient BMDMs upon LPS stimulation. In conclusion, the findings decode a previously unidentified role for a myeloid-TLR4 dependent Nr4a1/Ear2 negative feedback mechanism in macrophage-mediated progressive renal injury, implying that activation of Nr4a1-Ear2 axis can be a novel and effective immunotherapy for anti-GBM cGN.

RNA-seq profiling of tubulointerstitial tissue reveals a potential therapeutic role of dual anti-phosphatase 1 in glomerulonephritis.

Transcriptome profiling of tubulointerstitial tissue in glomerulonephritis may reveal a potential tubulointerstitial injury-related biomarker. We profiled manually microdissected tubulointerstitial tissue from biopsy cores of 65 glomerulonephritis cases, including 43 patients with IgA nephropathy, 3 with diabetes mellitus nephropathy, 3 with focal segmental glomerulosclerosis, 3 with lupus nephritis, 4 with membranous nephropathy and 9 with minimal change disease, and additional 22 nephrectomy controls by RNA sequencing. A potential biomarker was selected based on the false discovery rate, and experiments were performed in TNF-α-stimulated primary cultured human tubular epithelial cells (hTECs). We identified 3037 genes with low expression and 2852 genes with high expression in the disease samples compared to the controls. Dual-specificity phosphatase 1 (DUSP1) exhibited universal low expression in various diseases (log2 fold change, -3.87), with the lowest false discovery rate (7.03E-132). In further experimental validation study, DUSP1 overexpression ameliorated inflammatory markers related to MAP kinase pathways in hTECs, while pharmacologic inhibition of DUSP1 increased these markers. The combination of DUSP1 overexpression with low-concentration corticosteroid treatment resulted in more potent suppression of inflammation than high-concentration corticosteroid treatment alone. The profiled transcriptomes provide insights into the pathophysiology of tubulointerstitial injury in kidney diseases and may reveal a potential therapeutic biomarker.

The Role of Inflammasomes in Glomerulonephritis.

The inflammasome is an immune multiprotein complex that activates pro-caspase 1 in response to inflammation-inducing stimuli and it leads to IL-1ß and IL-18 proinflammatory cytokine production. NLRP1 and NLRP3 inflammasomes are the best characterized and they have been related to several autoimmune diseases. It is well known that the kidney expresses inflammasome genes, which can influence the development of some glomerulonephritis, such as lupus nephritis, ANCA glomerulonephritis, IgA nephropathy and anti-GBM nephropathy. Polymorphisms of these genes have also been described to play a role in autoimmune and kidney diseases. In this review, we describe the main characteristics, activation mechanisms, regulation and functions of the different inflammasomes. Moreover, we discuss the latest findings about the role of the inflammasome in several glomerulonephritis from three different points of view: in vitro, animal and human studies.

An adapted passive model of anti-MPO dependent crescentic glomerulonephritis reveals matrix dysregulation and is amenable to modulation by CXCR4 inhibition.

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are severe inflammatory disorders that often involve focal necrotizing glomerulonephritis (FNGN) and consequent glomerular scarring, interstitial fibrosis, and chronic kidney disease. Robust murine models of scarring in FNGN that may help to further our understanding of deleterious processes are still lacking. Here, we present a murine model of severe FNGN based on combined administration of antibodies against the glomerular basement membrane (GBM) and myeloperoxidase (MPO), and bacterial lipopolysaccharides (LPS), that recapitulates acute injury and was adapted to investigate subsequent glomerular and interstitial scarring. Hematuria without involvement of other organs occurs consistently and rapidly, glomerular necrosis and crescent formation are evident at 12 days, and consequent glomerular and interstitial scarring at 29 days after initial treatment. Using mass-spectrometric proteome analysis, we provide a detailed overview of matrisomal and cellular changes in our model. We observed increased expression of the matrisome including collagens, fibronectin, tenascin-C, in accordance with human AAV as deduced from analysis of gene expression microarrays and tissue staining. Moreover, we observed tissue infiltration by neutrophils, macrophages, T cells and myofibroblasts upon injury. Experimental inhibition of CXCR4 using AMD3100 led to a sustained histological presence of fibrin extravasate, reduced chemokine expression and leukocyte activation, but did not markedly affect ECM composition. Altogether, we demonstrate an adapted FNGN model that enables the study of matrisomal changes both in disease and upon intervention, as exemplified via CXCR4 inhibition.

Genetic abnormalities in biopsy-proven, adult-onset hemolytic uremic syndrome and C3 glomerulopathy.

Atypical hemolytic uremic syndrome (aHUS) and C3 glomerulopathy (C3G) have been linked to mutations in many of the proteins that are involved in alternative complement pathway activation. Age and etiology confounded, the prevalence of such mutations has been reported to be over 30 to 50% in these diseases. However, the cohorts studied included many children or individuals with a familial history of complement-related disorders and genetic tests were usually limited to exome sequencing of known causative or risk-associated genes. In this study, a retrospective adult cohort of 35 patients with biopsy-proven thrombotic microangiopathy (the largest in Canada) and 10 patients with C3 glomerulopathy was tested through an extended exome panel to identify causative defects in associated or candidate genes including those of the alternative and terminal complement pathways. A variant of unknown significance was also analyzed for pathogenicity through in vitro studies. To our surprise, the prevalence of known causative or risk-associated variants in either of these cohorts was found to be less than ~ 15% overall. However, the panel used and analyses carried out allowed to identify novel variants of potential clinical significance and a number of candidate genes. The prevalence of known genetic defects in adult-onset aHUS and C3G is thus probably much lower than 30 to 50%. Our results also point towards the importance of investigating diseases of the alternative complement pathway through extended exome panels and in vitro analyses. KEY MESSAGES: The alternative complement pathway plays a major role in the pathogenesis of hemolytic uremic syndrome and C3 glomerulopathy. Based on previous studies, both disorders have been commonly linked to variants in the various intermediates that sustain or regulate this pathway. The prevalence of such mutations in the adult-onset and sporadic forms of these diseases is probably much lower than expected based on larger series. The sporadic forms of complementopathies are likely to involve additional genes that are yet to be uncovered.

Recurrent Glomerular Disease after Kidney Transplantation: Diagnostic and Management Dilemmas.

Recurrent glomerular disease after kidney transplant remains an important cause of allograft failure. Many of the different entities post-transplant still suffer from incomplete knowledge on pathophysiology, and therefore lack targeted and effective therapies. In this review, we focus on specific clinical dilemmas encountered by physicians in managing recurrent glomerular disease by highlighting new insights into the understanding and treatment of post-transplant focal segmental glomerulosclerosis, membranous nephropathy, atypical hemolytic uremic syndrome, C3 glomerulopathy, amyloid light-chain (AL) amyloidosis, and IgA nephropathy.