Causal relationship between inflammatory skin diseases and immunoglobulin A nephropathy: A Mendelian randomization and enrichment analysis study.

OBJECTIVE: To investigate the causal relationship between inflammatory skin diseases (atopic dermatitis, and psoriasis) and IgA nephropathy using Mendelian randomization and enrichment analysis. METHODS: The instrumental variables (IVs) in the European Bioinformatics Institute (EBI) database were used for two-sample MR analysis. The results of inverse variance weighting (IVW) were used as the main method, the MR-Egger method was used for pleiotropy analysis and the leave-one-out method was used for sensitivity analysis to verify the reliability of the data. Combined with the human genome database GeneCards database and Metascape enrichment analysis. RESULTS: People with AD had an increased risk of IgA nephropathy (IVW: OR = 1.06, 95% CI [1.0002-1.1248], p = 0.0491). Psoriasis and IgA nephropathy (IVW: OR = 0.97, 95% CI [0.9394-1.0055], p = 0.1002) no statistical significance, therefore cannot prove cause-and-effect relationship between. CONCLUSIONS: This study provides evidence that atopic dermatitis is associated with an increased risk of IgA nephropathy, but does not provide evidence that psoriasis is causologically associated with IgA nephropathy. Enrichment analysis suggested a causal relationship between inflammatory skin diseases and IgA nephropathy at the genetic level.

Exploring the crosstalk molecular mechanisms between IgA nephropathy and Sjögren's syndrome based on comprehensive bioinformatics and immunohistochemical analyses.

IgA nephropathy (IgAN) and Sjogren's syndrome (SS) are two autoimmune diseases with undetermined etiology and related to abnormal activation of lymphocytes. This study aims to explore the crucial genes, pathways and immune cells between IgAN and SS. Gene expression profiles of IgAN and SS were obtained from the Gene Expression Omnibus and Nephroseq data. Differentially expressed gene (DEG) and weighted gene co-expression network analyses (WGCNA) were done to identify common genes. Enrichment analysis and protein-protein interaction network were used to explore potential molecular pathways and crosstalk genes between IgAN and SS. The results were further verified by external validation and immunohistochemistry (IHC) analysis. Additionally, immune cell analysis and transcription factor prediction were also conducted. The DEG analysis revealed 28 commonly up-regulated genes, while WGCNA identified 98 interactively positive-correlated module genes between IgAN and SS. The enrichment analysis suggested that these genes were mainly involved in the biological processes of response to virus and antigen processing and presentation. The external validation and IHC analysis identified 5 hub genes (PSMB8, PSMB9, IFI44, ISG15, and CD53). In the immune cell analysis, the effector memory CD8 T and T follicular helper cells were significantly activated, and the corresponding proportions showed positively correlations with the expressions of the 5 hub genes in the two autoimmune diseases. Together, our data identified the crosstalk genes, molecular pathways, and immune cells underlying the IgAN and SS, which provides valuable insights into the intricate mechanisms of these diseases and offers potential intervention targets.

Causal role of immune cells in IgA nephropathy: a mendelian randomization study.

BACKGROUND: Previous observational studies have shown that immune cells play an important role in IgA nephropathy. However, the specific causal relationship between the two is inconsistent. METHODS: We used a two-sample mendelian randomization(MR) analysis to investigate the causal association between 731 immune cell signatures and IgA nephropathy in this study. Based on published GWAS data, immune cells were characterized by four immune types absolute cell (AC) counts, median fluorescence intensity (MFI), morphological parameters (MP), relative cell (RC) counts. Meanwhile, heterogeneity test, horizontal pleiotropy and sensitivity test were used to evaluate the robustness and reliability of the results. RESULTS: An important causal association was achieved for 14 RC traits/IgA nephropathy, 3 AC traits/IgA nephropathy, 10 MFI traits/IgA nephropathy, and 1 MP trait/IgA nephropathy. However, after false discovery rate (FDR) correction, only one immunophenotype was found to be protective against IgA nephropathy. The OR of herpesvirus entry mediator (HVEM) on terminally differentiated CD4+ T cell (maturation stages of T-cell panel) on IgA nephropathy risk was estimated to be 0.727 (95%CI: 0.624-0.847, p = 4.20e - 05, PFDR = 0.023) according to inverse variance weighting (IVW) method, and the weighted-median method yielded similar results (OR = 0.743, 95% CI: 0.596-0.927, p = 0.008). Although not statistically significant, the association was consistent with MR-Egger, simple mode and weighted mode. CONCLUSIONS: Our study further confirmed that immune cells play a complex and important role in the pathogenesis of IgA nephropathy, providing evidence for clinical research.

Causal relationship between Helicobacter pylori infection and IgA nephropathy: a bidirectional two-sample mendelian randomization study.

IgA nephropathy (IgAN) is one of the most common primary glomerulonephritis, and serum Helicobacter pylori (H. pylori) antibody levels are increased in patients with IgA N, but the role of H. pylori infection in the pathogenesis of IgAN is unclear. In this study, we investigated whether there is a causal relationship and reverse causality between IgAN and H. pylori infection by using a bidirectional two-sample Mendelian randomization (MR) analysis. This study was estimated using inverse variance weighted (IVW), MR-Egger and weighted median methods, with the IVW method having the strongest statistical efficacy. Seven common serum H. pylori antibodies were selected as exposure factors for positive MR analysis. The results showed that there was no evidence of a causal relationship between H. pylori infection and IgAN. Reverse MR analysis showed that there was also no evidence that the occurrence of IgAN leads to an increased risk of H. pylori infection.

Mendelian Randomization Analysis of Systemic Iron Status and Risk of Different Types of Kidney Disease.

With rapid increases in incidence, diverse subtypes, and complicated etiologies, kidney disease remains a global public health problem. Iron, as an essential trace element, has pleiotropic effects on renal function and the progression of kidney diseases. A two-sample Mendelian randomization (MR) analysis was implemented to determine the potential causal effects between systemic iron status on different kidney diseases. Systemic iron status was represented by four iron-related biomarkers: serum iron, ferritin, transferrin saturation (TfSat), and total iron binding capacity (TIBC). For systemic iron status, 163,511, 246,139, 131,471, and 135,430 individuals were included in the genome-wide association study (GWAS) of serum iron, ferritin, TfSat, and TIBC, respectively. For kidney diseases, 653,143 individuals (15,658 cases and 637,485 controls), 657,076 individuals (8160 cases and 648,916 controls), and 659,320 individuals (10,404 cases and 648,916 controls) were included for immunoglobulin A nephropathy (IgAN), acute kidney disease (AKD), and chronic kidney disease (CKD), respectively. Our MR results showed that increased serum iron [odds ratio (OR): 1.10; 95% confidence interval (95% CI): 1.04, 1.16; p < 0.0042], ferritin (OR: 1.30; 95% CI: 1.14, 1.48; p < 0.0042), and TfSat (OR: 1.07; 95% CI: 1.04, 1.11; p < 0.0042)] and decreased TIBC (OR: 0.92; 95% CI: 0.88, 0.97; p < 0.0042) were associated with elevated IgAN risk. However, no significant associations were found between systemic iron status and AKD or CKD. In our MR study, the genetic evidence supports elevated systemic iron status as a causal effect on IgAN, which suggests a potential protective effect of iron chelation on IgAN patients.

A Mendelian randomization study investigating the causal relationships between inflammation and immunoglobulin A nephropathy.

BACKGROUND: Immunoglobulin A nephropathy (IgAN) is an autoimmune disease characterized by the production of galactose­deficient IgA1 (Gd­IgA1) and the deposition of immune complexes in the kidney. Exploring the landscape of immune dysregulation in IgAN is valuable for pathogenesis and disease treatment. We conducted Mendelian randomization (MR) to assess the causal correlations between inflammation and IgAN. METHODS: Based on available genetic datasets, we investigated potential causal links between inflammation and the risk of IgAN using two-sample MR. We used genome-wide association study (GWAS) summary statistics of 5 typical inflammation markers, 41 inflammatory cytokines, and 731 immune cell signatures, accessed from the public GWAS Catalog. The primary method employed for MR analysis was Inverse Variance Weighted (IVW). To confirm consistency across results, four supplementary MR methods were also conducted: MR-Egger, Weighted Median, Weighted Mode, and Simple Mode. To assess pleiotropy, we used the MR-Egger regression intercept test and Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO) test. Cochrane's Q statistic was applied to evaluate heterogeneity. Additionally, the stability of the MR findings was verified through the leave-one-out sensitivity analysis. RESULTS: This study revealed that interleukin-7 (IL-7) and stem cell growth factor beta (SCGF-ß) were possibly associated with the risk of IgAN according to the IVW approach, with estimated odds ratios (OR) of 1.059 (95 % confidence interval [CI] 1.015 to 1.104, P = 0.008) and 1.043 (95 % CI 1.002 to 1.085, P = 0.037). Five immune traits were identified that might be linked to IgAN risk, each with P-values below 0.01, including natural killer T %T cell (OR = 1.058, 95 % CI: 1.020 to 1.097, P = 0.002), natural killer T %lymphocyte (OR = 1.055, 95 % CI: 1.016 to 1.096, P = 0.006), CD25++ CD8+ T cell %T cell (OR = 1.057, 95 % CI: 1.016 to 1.099, P = 0.006), CD3 on effector memory CD4+ T cell (OR = 1.045, 95 % CI: 1.019 to 1.071, P = 0.001), and CD3 on CD28+ CD45RA+ CD8+ T cell (OR = 1.042, 95 % CI: 1.016 to 1.068, P = 0.001). CD4 on central memory CD4+ T cell might be a protective factor for IgAN (OR = 0.922, 95 % CI: 0.875 to 0.971, P = 0.002). Moreover, IgAN may be implicated in a high risk of elevated granulocyte colony-stimulating factor (G-CSF) (OR = 1.114, 95 % CI 1.002 to 1.239, P = 0.046). CONCLUSION: Our study revealed exposures among typical inflammation markers, inflammatory cytokines, and immune cell signatures that may potentially linked to IgAN risk by MR analysis. This insight may advance our understanding of the etiology of IgAN and support the development of targeted therapeutic strategies.

Comprehensive Analysis of ceRNA Network and Immune Cell Infiltration Pattern of Autophagy-Related Genes in IgA Nephropathy.

INTRODUCTION: IgA nephropathy (IgAN) is a prevalent worldwide glomerular disease with a complex pathophysiology that has significant economic implications. Despite the lack of successful research, this study aims to discover the potential competing endogenous RNA (ceRNA) network of autophagy-associated genes in IgAN and examine their correlation with immune cell infiltration. METHODS: Autophagy-related hub genes were discovered by assessing the GSE116626 dataset and constructing a protein-protein interaction network. Nephroseq v5 analysis engine was used to analyze correlations between hub genes and proteinuria, glomerular filtration rate (GFR), and serum creatinine levels. Then, a ceRNA network construction and the CIBERSORT tool for immune cell infiltration analysis were also performed. Additionally, the differentially expressed autophagy-related genes were used to predict potential targeted medications for IgAN. RESULTS: Overall, 1,396 differentially expressed genes were identified in IgAN along with 25 autophagy-related differentially expressed messenger RNAs. Enrichment analysis revealed significant involvement of autophagy and apoptosis in biological processes. Next, we evaluated the top hub nodes based on their highest degrees. The ability of IgAN discrimination was confirmed in the GSE35487 and GSE37460 datasets by validating the five hub genes: SIRT1, FOS, CCL2, CDKN1A, and MYC. In the Nephroseq v5 analysis engine, the clinical correlation of the five hub genes was confirmed. Furthermore, the ceRNA network identified 18 circular RNAs and 2 microRNAs associated with hub autophagy-related genes in IgAN. Our investigation identified hsa-miR-32-3p and hsa-let-7i-5p as having elevated expression levels and substantial diagnostic value. Finally, four distinctively infiltrated immune cells were found to be associated with the hub autophagy-related genes, and 67 drugs were identified as potential therapeutic options for IgAN. CONCLUSION: This study sheds light on a novel ceRNA regulatory network mechanism associated with autophagy in IgAN development.

Urinary exosomal mRNAs as biomarkers for predicting the therapeutic effect of renin-angiotensin system inhibitors in IgA nephropathy patients.

BACKGROUND: Renin-angiotensin system inhibitors (RASi) treatment is the basic therapy for IgA nephropathy (IgAN) patients. However, there is few of biomarker that can predict the efficacy of RASi. This study aimed to find urinary exosomal mRNAs related to the therapeutic effect of RASi in the treatment of proteinuria in IgAN patients. METHODS: We divided IgAN patients in screening cohort into A1 (proteinuria increase at 3 months), B1 (proteinuria decrease less than 50 % at 3 months), C1 (proteinuria decrease more than 50 % at 3 months) groups according to changes of proteinuria after treatment. The urinary exosomes were collected before biopsy, RNAs were extracted and analyzed with the microarray assay. The candidate genes were screened by differentially expressed genes (DEGs) analysis and then validated by quantitative real-time polymerase chain reaction (qPCR) in a validation cohort. A receiver operating characteristic (ROC) curve was used to evaluate gene performance in predicting therapeutic effect on RASi reducing proteinuria in IgAN patients. RESULTS: ECE1 and PDE1A mRNAs were significantly different among the three groups, and were gradually decreased among A1, B1 and C1 groups. In the validation cohort, the level of urinary exosomal ECE1 and PDE1A mRNAs were also significantly lower in A2 group compared with C2 group(ECE1, P < 0.001;PDE1A, P < 0.01). Besides, the level of ECE1 mRNA was also lower in B2 group compared with C2 group (P < 0.01). The ROC curve verified that urinary exosomal ECE1 and PDE1A gene level predicted RASi efficacy in IgAN patients with area under curve (AUC) 0.68 and 0.63 respectively. CONCLUSION: Urinary exosomal ECE1 and PDE1A mRNAs expression can serve as potential biomarkers for predicting the RASi efficacy to reduce proteinuria in IgAN patients.

Genome-wide analysis of long noncoding RNAs as cis-acting regulators of transcription factor-encoding genes in IgA nephropathy.

BACKGROUND: IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis in the world, but the disease pathogenesis noncoding is yet to be elucidated. Previous studies have revealed regulatory functions for long noncoding RNA (lncRNA) in various diseases; however, the roles of lncRNA in IgAN and regulation of transcription factors (TFs) have been scarcely investigated. METHODS: Renal tissue samples (n = 5) from patients with IgAN and control samples (n = 4) were collected and RNA sequencing (RNA-seq) was performed. Four software programs were employed for lncRNA prediction. GO (Gene Ontology)/KEGG (Kyoto Encyclopedia of Genes and Genomes) were employed for analysis of the identified differentially expressed genes (DEGs). A regulatory network model of DE lncRNA-TF-DEG was developed, and the levels of expression of key lncRNAs, TFs, and corresponding target genes were assessed using qRT-PCR and immunofluorescence. RESULTS: The current study identified 674 upregulated and 1,011 downregulated DE mRNAs and 260 upregulated and 232 downregulated DE lncRNAs in IgAN samples compared with control samples. The upregulated DE mRNAs showed enrichment in cell adhesion and collagen glial fiber organization pathways. The DE lncRNAs-DE mRNAs showing co-expression are associated with transmembrane transport. A novel regulatory network model of lncRNA-TF-DEG has been developed. This study identified seven TFs that are cis-regulated by 6 DE lncRNAs, and show co-expression with 132 DEGs (correlation coefficient ≥ 0.8, P ≤ 0.01), generating 158 pairs that showed co-expression. The lncRNAs NQO1-DT and RP5-1057120.6 were found to be highly expressed in IgAN samples. The TFs vitamin D Receptor (VDR) and NFAT5, along with their target genes were also aberrantly expressed. CONCLUSION: Key lncRNAs and TFs centrally associated with IgAN have been identified in this study. A regulatory network model of lncRNA-TF-mRNA was constructed. Further studies on the genes identified herewith could provide insight into the pathogenesis of IgAN.

Molecular characterization of m6A RNA methylation regulators with features of immune dysregulation in IgA nephropathy.

The role of RNA N6-methyladenosine (m6A) modification in immunity is being elucidated. This study aimed to explore the potential association between m6A regulators and the immune microenvironment in IgA nephropathy (IgAN). The expression profiles of 24 m6A regulators in 107 IgAN patients were obtained from the Gene Expression Omnibus (GEO) database. The least absolute shrinkage and selection operator (LASSO) regression and logistic regression analysis were utilized to construct a model for distinguishing IgAN from control samples. Based on the expression levels of m6A regulators, unsupervised clustering was used to identify m6A-induced molecular clusters in IgAN. Gene set enrichment analysis (GSEA) and immunocyte infiltration among different clusters were examined. The gene modules with the highest correlation for each of the three clusters were identified by weighted gene co-expression network analysis (WGCNA). A model containing 10 m6A regulators was developed using LASSO and logistic regression analyses. Three molecular clusters were determined using consensus clustering of 24 m6A regulators. A decrease in the expression level of YTHDF2 in IgAN samples was significantly negatively correlated with an increase in resting natural killer (NK) cell infiltration and was positively correlated with the abundance of M2 macrophage infiltration. The risk scores calculated by the nomogram were significantly higher for cluster-3, and the expression levels of m6A regulators in this cluster were generally low. Immunocyte infiltration and pathway enrichment results for cluster-3 differed significantly from those for the other two clusters. Finally, the expression of YTHDF2 was significantly decreased in IgAN based on immunohistochemical staining. This study demonstrated that m6A methylation regulators play a significant role in the regulation of the immune microenvironment in IgAN. Based on m6A regulator expression patterns, IgAN can be classified into multiple subtypes, which might provide additional insights into novel therapeutic methods for IgAN.

[Current status and prospects of genetic research on IgA nephropathy].

IgA nephropathy is the most common primary glomerulonephritis worldwide, and genetic factors may play an important role in its pathogenesis. Following candidate gene association analysis and genome-wide linkage study, genome-wide association studies (GWAS) have found multiple susceptibility genes related to the pathogenesis and clinical phenotype of IgA nephropathy. Meanwhile, structural variation and epigenetic changes are also closely related to IgA nephropathy. Genetic variants have been found to explain about 11% of its heritability. In the current era of genomic medicine, how to find more susceptible genes/loci, whole genome sequencing studies (WGS) provide clues to further understand the genetic variation of IgA nephropathy. How to find the cell type-specific susceptibility genes associated with IgA nephropathy, multi-omics studies will conduct comprehensive analysis via single-cell sequencing, expression quantitative trait locus (eQTL) and genomics to find the pathogenic genes and offer insights into the development of targeted drugs, which will be the trend and direction of future research.

From genomic insights to clinical hope: Targeting NEU1 in IgA nephropathy.

BACKGROUND: IgA Nephropathy (IgAN), the primary form of glomerulonephritis, presents significant clinical challenges due to its obscure pathogenesis and lack of targeted treatments. We conducted a proteome-wide Mendelian randomization (MR) study to identify therapeutic targets for IgAN. METHODS: Utilizing a plasma proteome dataset comprising 4907 blood plasma proteins as the exposure variable, and renal biopsy-confirmed IgAN cases as the outcome, this study employed MR to pinpoint proteins potentially pathogenic to IgAN. The robustness of our findings was affirmed through external dataset validation, reverse causation testing, and Bayesian colocalization analysis. Additionally, we conducted phenotypic scanning and analyzed downstream metabolites to investigate candidate proteins's biological function. RESULTS: In our study, a significant association was identified between an increase in neuraminidase 1 (NEU1) expression and the risk of IgAN. Specifically, a one standard deviation increase in NEU1 expression was associated with an odds ratio of 11.80 for the development of IgAN (95% confidence interval: 4.03-34.54). This association was substantiated across various statistical models and external validations. Colocalization analysis indicated a shared causal variant between NEU1 expression and IgAN. Furthermore, an increased influenza risk associated with NEU1 was observed, supporting the therapeutic potential of NEU1 inhibitors for IgAN. However, our study found no significant role for neuraminic acid-related metabolites in IgAN's development, suggesting an independent pathway for NEU1's influence. CONCLUSION: This study identifies NEU1 as a promising therapeutic target for IgAN, backed by robust genetic evidence. Future research should explore NEU1's therapeutic potential in diverse populations and clinical scenarios, further establishing its role in IgAN.

Novel immune cross-talk between inflammatory bowel disease and IgA nephropathy.

The mechanisms underlying the complex correlation between immunoglobulin A nephropathy (IgAN) and inflammatory bowel disease (IBD) remain unclear. This study aimed to identify the optimal cross-talk genes, potential pathways, and mutual immune-infiltrating microenvironments between IBD and IgAN to elucidate the linkage between patients with IBD and IgAN. The IgAN and IBD datasets were obtained from the Gene Expression Omnibus (GEO). Three algorithms, CIBERSORTx, ssGSEA, and xCell, were used to evaluate the similarities in the infiltrating microenvironment between the two diseases. Weighted gene co-expression network analysis (WGCNA) was implemented in the IBD dataset to identify the major immune infiltration modules, and the Boruta algorithm, RFE algorithm, and LASSO regression were applied to filter the cross-talk genes. Next, multiple machine learning models were applied to confirm the optimal cross-talk genes. Finally, the relevant findings were validated using histology and immunohistochemistry analysis of IBD mice. Immune infiltration analysis showed no significant differences between IBD and IgAN samples in most immune cells. The three algorithms identified 10 diagnostic genes, MAPK3, NFKB1, FDX1, EPHX2, SYNPO, KDF1, METTL7A, RIDA, HSDL2, and RIPK2; FDX1 and NFKB1 were enhanced in the kidney of IBD mice. Kyoto Encyclopedia of Genes and Genomes analysis showed 15 mutual pathways between the two diseases, with lipid metabolism playing a vital role in the cross-talk. Our findings offer insights into the shared immune mechanisms of IgAN and IBD. These common pathways, diagnostic cross-talk genes, and cell-mediated abnormal immunity may inform further experimental studies.

A cluster of type I interferon-regulated genes associates with disease activity and prognosis in patients with IgA nephropathy.

The exact pathogenesis of IgA nephropathy (IgAN) is complex and so far, not well defined. Since it has been shown that microbial infections could induce high levels of type I interferon (IFN-I) and there is an evident link between mucosal infection and gross hematuria in IgAN, we hypothesized that IFN-I may play a role in the pathogenic process. In this study, we investigated the type I interferon status in IgAN based on the expression of 17 IFN-regulated genes (IRGs) in whole blood from 59 IgAN patients in a cross-sectional study, of which 34 patients followed longitudinally. Analysis of the IFN-score showed that there was a significant elevated IFN-score in the IgAN patients compared with healthy controls (n = 28, p = 9.80 × 10-3), and we observed an elevated IFN-score in the group with less tubular atrophy/interstitial fibrosis (p = 1.07 × 10-2) and with a lower proportion of mesangial hypercellularity (p = 1.23 × 10-2). In the longitudinal analysis, Cox regression analysis revealed that a higher IFN level was associated with a better renal outcome in IgAN after adjustments for gender and age (hazard ratio, 0.90; 95 % confidence interval, 0.81 to 0.97; p = 4.20 × 10-2). In conclusion, our finding suggested that IFN score may represent a novel type of biomarker in IgAN, which requires further exploration on its mechanism and therapeutic targeting.

Protective effect of modified Huangqi Chifeng decoction on immunoglobulin A nephropathy through toll-like receptor 4/myeloid differentiation factor 88/nuclear factor-kappa B signaling pathway.

OBJECTIVE: To examine the nephroprotective mechanism of modified Huangqi Chifeng decoction (, MHCD) in immunoglobulin A nephropathy (IgAN) rats. METHODS: To establish the IgAN rat model, the bovine serum albumin, lipopolysaccharide, and carbon tetrachloride 4 method was employed. The rats were then randomly assigned to the control, model, telmisartan, and high-, medium-, and low-dose MHCD groups, and were administered the respective treatments via intragastric administration for 8 weeks. The levels of 24-h urinary protein, serum creatinine (CRE), and blood urea nitrogen (BUN) were measured in each group. Pathological alterations were detected. IgA deposition was visualized through the use of immunofluorescence staining. The ultrastructure of the kidney was observed using a transmission electron microscope. The expression levels of interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and transforming growth factor-ß1 (TGF-ß1) were examined by immunohistochemistry and quantitative polymerase chain reaction. Levels of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), and nuclear factor-kappa B (NF-κB) P65, were examined by immunohistochemistry, Western blotting, and quantitative polymerase chain reaction. RESULTS: The 24-h urine protein level in each group increased significantly at week 6, and worsen from then on. But this process can be reversed by treatments of telmisartan, and high-, medium-, and low-dose of MHCD, and these treatments did not affect renal function. Telmisartan, and high-, and medium-dose of MHCD reduced IgA deposition. Renal histopathology demonstrated the protective effect of high-, medium-, and low-dose of MHCD against kidney injury. The expression levels of MCP-1, IL-6, and TGF-ß1 in kidney tissues were downregulated by low, medium and high doses of MHCD treatment. Additionally, treatment of low, medium and high doses of MHCD decreased the protein and mRNA levels of TLR4, MyD88, and NF-κB. CONCLUSIONS: MHCD exerted nephroprotective effects on IgAN rats, and MHCD regulated the expressions of key targets in TLR4/MyD88/NF-κB signaling pathway, thereby alleviating renal inflammation by inhibiting MCP-1, IL-6 expressions, and ameliorating renal fibrosis by inhibiting TGF-ß1 expression.

Sparsentan ameliorates glomerular hypercellularity and inflammatory-gene networks induced by IgA1-IgG immune complexes in a mouse model of IgA nephropathy.

IgA nephropathy (IgAN) is characterized by glomerular deposition of immune complexes (ICs) consisting of IgA1 with O-glycans deficient in galactose (Gd-IgA1) and Gd-IgA1-specific IgG autoantibodies. These ICs induce kidney injury, and in the absence of disease-specific therapy, up to 40% of patients with IgAN progress to kidney failure. IgA1 with its clustered O-glycans is unique to humans, which hampered development of small-animal models of IgAN. Here, we used a model wherein engineered ICs (EICs) formed from human Gd-IgA1 and recombinant human IgG autoantibody are injected into nude mice to induce glomerular injury mimicking human IgAN. In this model, we assessed the protective effects of sparsentan, a single-molecule dual endothelin angiotensin receptor antagonist (DEARA) versus vehicle on EIC-induced glomerular proliferation and dysregulation of gene expression in the kidney. Oral administration of sparsentan (60 or 120 mg/kg daily) to mice intravenously injected with EIC attenuated the EIC-induced glomerular hypercellularity. Furthermore, analysis of changes in the whole kidney transcriptome revealed that key inflammatory and proliferative biological genes and pathways that are upregulated in this EIC model of IgAN were markedly reduced by sparsentan, including complement genes, integrin components, members of the mitogen-activated protein kinase family, and Fc receptor elements. Partial overlap between mouse and human differentially expressed genes in IgAN further supported the translational aspect of the immune and inflammatory components from our transcriptional findings. In conclusion, our data indicate that in the mouse model of IgAN, sparsentan targets immune and inflammatory processes leading to protection from mesangial hypercellularity.NEW & NOTEWORTHY The mechanisms by which deposited IgA1 immune complexes cause kidney injury during early phases of IgA nephropathy are poorly understood. We used an animal model we recently developed that involves IgA1-IgG immune complex injections and determined pathways related to the induced mesangioproliferative changes. Treatment with sparsentan, a dual inhibitor of endothelin type A and angiotensin II type 1 receptors, ameliorated the induced mesangioproliferative changes and the associated alterations in the expression of inflammatory genes and networks.