Impact of gene polymorphisms of interleukin-18, transforming growth factor-β, and vascular endothelial growth factor on development of IgA nephropathy and thin glomerular basement membrane disease

Evaluating Single-Nucleotide Polymorphisms in Inflammasome Proteins and Serum Levels of IL-18 and IL-1β in Kidney Interstitial Damage in Anti-Neutrophilic Cytoplasmic Antibody-Associated Vasculitis

The inflammasome regulates the innate inflammatory response and is involved in autoimmune diseases. In this study, we explored the levels of IL-18 and IL-1β in serum and urine and the influence of various single-nucleotide polymorphisms (SNPs) on kidney lesions at diagnosis in patients with ANCA-associated vasculitis (AAV) and their clinical outcomes. Ninety-two patients with renal AAV were recruited, and blood and urine were collected at diagnosis. Serum and urine cytokine levels were measured by ELISA. DNA was extracted and genotyped using TaqMan assays for SNPs in several inflammasome genes. Lower serum IL-18 (p = 0.049) and the IL-18 rs187238 G-carrier genotype (p = 0.042) were associated with severe fibrosis. The IL-18 rs1946518 TT genotype was associated with an increased risk of relapse (p = 0.05), whereas GG was related to better renal outcomes (p = 0.031). The rs187238 GG genotype was identified as a risk factor for mortality within the first year after AAV diagnosis, independent of the requirement for dialysis or lung involvement (p = 0.013). We suggest that decreased cytokine levels could be a surrogate marker of scarring and chronicity of the renal lesions, together with the rs187238 GG genotype. If our results are validated, the rs1946518 TT genotype predicts the risk of relapse and renal outcomes during follow-up.

Interleukin Variants Are Associated with the Development and Progression of IgA Nephropathy: A Candidate-Gene Association Study and Meta-Analysis

The interleukin-1 gene cluster encodes cytokines, which modulate mesangial cell proliferation and matrix expansion, both constituting central factors in the development and progression of immunoglobulin A nephropathy (IgAN). A candidate-gene study was performed to examine the association of polymorphisms of the interleukin-1 gene cluster with the risk of progressive IgAN. To gain deeper insights into the involvement of interleukin genes in IgAN, a meta-analysis of genetic association studies (GAS) that examine the association between interleukin variants and IgAN was conducted. Association study: The case-control study consisted of 121 unrelated Caucasians with sporadic, histologically diagnosed IgAN and of 246 age- and sex-matched healthy controls. Persistent proteinuria (>2 g/24 h) and/or impaired kidney function (serum creatinine > 1.5 mg/dL) defined progressive (n = 67) vs. non-progressive (n = 54) IgAN cases. Genotypes were assessed for two promoter-region single-nucleotide polymorphisms, C-899T (rs1800587) in IL1A and C-511T (rs16944) in IL1B, and for one penta-allelic variable-length tandem repeat polymorphism (VNTR 86 bp intron 2) in IL1RN. The association of these variants with the susceptibility of IgAN and the development of progressive IgAN (healthy status, IgAN, progressive IgAN) was tested using the generalized odds ratio (ORG) metric. Linkage disequilibrium and haplotype analysis were also performed. Meta-analysis: We included in the meta-analysis 15 studies investigating association between 14 interleukin variants harbored in eight different genes and IgAN. The ORG was used to evaluate the association between interleukin variants and IgAN using random effects models. The present case-control study revealed association of IL1B C-511T (rs16944) with the progression of IgAN (p = 0.041; ORG = 2.11 (1.09-4.07)). On haplotype analysis, significant results were derived for the haplotypes C-C-1 (p = 0.005; OR = 0.456 (0.261~0.797)) and C-T-2 (p = 0.003; OR = 4.208 (1.545-11.50)). Regarding association and meta-analysis results, variants in IL1B (rs1143627 and rs16944), IL1RN (rs928940, rs439154, and rs315951) and IL10 (rs1800871) were associated with IgAN based on either genotype or allele counts. Genetic variants and haplotypes in the IL1B, IL1RN, and IL10 genes might contribute to an increased risk for development and progression of IgAN.

Association of Immune and Inflammatory Gene Polymorphism With the Risk of IgA Nephropathy: A Systematic Review and Meta-Analysis of 45 Studies

IgA nephropathy is the most prevalent primary glomerulonephritis worldwide, with identical immunopathological characteristics caused by multiple etiologies as well as influenced by geographical and ethnical factors. To elucidate the role of immunologic and inflammatory mechanisms in the susceptibility to IgA nephropathy, we explored single nucleotide polymorphisms of related molecules in the immune pathways. We searched the PubMed database for studies that involved all gene variants of molecules in the 20 immunologic and inflammatory pathways selected from the Kyoto Encyclopedia of Genes and Genomes database. The odds ratios with their corresponding 95% confidence intervals in six genetic models (allele model, dominant model, homozygote model, heterozygote model, overdominant model, and recessive model) were summarized using fixed or random effect models. Subgroup analysis was conducted based on different ethnicities with generalized odds ratios. Heterogeneity was evaluated using the Q and I² tests. Begg’s funnel plot and Egger’s linear regression test were used to evaluating possible publication bias among the included studies, and sensitivity analysis was used to test the stability of the overall results. A total of 45 studies met our selection criteria and eight related genetic association studies were retrieved, including 320 single-nucleotide polymorphisms from 20 candidate pathways, ranging from 2000 to 2021. A total of 28,994 healthy people versus 20,600 IgA nephropathy patients were enrolled. Upon meta-analyzed results that TGFB1 (rs1800469, rs1982073, rs1800471), IL-1B (rs1143627), IL-18 (rs1946518), and TLR1 (rs5743557) showed effect with or without ethnicity difference. And 10 variants presented stable and robust related to IgA nephropathy. This research showed that genetic variants are related to the immunologic and inflammatory effects of IgA nephropathy pathogenesis. The meta-analysis results supported the previous researches, and may help deepen the understanding of pathogenesis and explore new targets for IgA nephropathy-specific immunotherapy.