Genetic variants of microRNA-146a gene: an indicator of systemic lupus erythematosus susceptibility, lupus nephritis, and disease activity

Association of Immune-Related Genetic and Epigenetic Alterations with Lupus Nephritis

BACKGROUND

The familial clustering phenomenon together with environmental influences indicates the presence of a genetic and epigenetic predisposition to systematic lupus erythematosus (SLE). Interestingly, regarding lupus nephritis (LN), the worst complication of SLE, mortality, and morbidity were not consistent with SLE in relation to sexuality and ethnicity.

SUMMARY

Genetic and epigenetic alterations in LN include genes and noncoding RNAs that are involved in antigen-presenting, complements, immune cell infiltration, interferon pathways, and so on. Once genetic or epigenetic change occurs alone or simultaneously, they will promote the formation of immune complexes with autoantibodies that target various autoantigens, which results in inflammatory cytokines and autoreactive immune cells colonizing renal tissues and contributing to LN.

KEY MESSAGES

Making additional checks for immunopathology-related heredity and epigenetic factors may lead to a more holistic perspective of LN.

Association between genetic variants of microRNA-21 and microRNA-155 and systemic lupus erythematosus: A case-control study from a Chinese population

Background

Systemic lupus erythematosus (SLE) is a common autoimmune disease, and its pathogenesis remains unclear. The alteration of genetic materials is believed to play a role in SLE development. This study evaluated the association between the genetic variants of microRNA‐21 (miR‐21) and microRNA‐155 (miR‐155) and SLE.

Methods

The SNaPshot genotyping method was used to detect the genotypes of selected SNPs in patients and controls. The expression of miR‐21 and miR‐155 was analyzed using reverse transcription‐quantitative polymerase chain reaction (RT‐qPCR). The functional annotation and the biological effects of SNPs were assessed by HaploReg V4.1 and Regulome DB V2.0 software. The Hardy–Weinberg equilibrium test was used to gather statistics, and odds ratios (ORs) and 95% confidence intervals (CIs) were evaluated by logistic regression.

Results

The distribution difference of TA genotype in rs767649 was observed (TA vs. T/T: OR = 0.68, 95%CI, 0.48–0.95, p = 0.026). There was a significant difference in the T/A + A/A (T/A + A/A vs. T/T: OR = 0.68, 95%CI, 0.49–0.94, p = 0.020). A significant difference in T allele distribution was found in the depressed complement of SLE (T vs. A: OR = 0.67, 95%CI, 0.47–0.95, p = 0.026). There were significant differences in genetic variants of rs13137 between the positive and the negative SSB antibodies (Anti‐SSB) (T vs. A: OR = 0.67, 95%CI, 0.47–0.95, p = 0.026; T/A + T/T vs. AA: OR = 2.23, 1.18–4.49, p = 0.013). The expression levels of miR‐21 and miR‐155 were significantly higher in patients than in controls (p < 0.001).

Conclusions

This study provides novel insight that genetic variants of rs767649 and rs13137 are associated with susceptibility to SLE.

mir-146a genetic polymorphisms in systemic lupus erythematosus patients: Correlation with disease manifestations

This study aimed to investigate the genetic polymorphisms of miR-146a SNPs (rs2910164, rs57095329, and rs2431697) in systemic lupus erythematosus (SLE) patients and their association with clinical manifestations. The implication of SNPs on miR-146a expression level was also evaluated. SLE patients (113) and healthy controls (104) were registered in this study. The miR-146a SNPs were genotyped by polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP). Quantitative real-time PCR was used to measure the miR-146a expression in peripheral blood mononuclear cells (PBMCs). Our results showed that the genotype frequency of miR-146a SNPs didn't deviate significantly from the Hardy–Weinberg equilibrium (HWE). The AG genotype and G allele of miR-146a (rs57095329 A/G) might be considered a risk factor for the disease (OR = 2.27; CI: 0.78–6.57 and OR: 2.35; CI: 0.79–6.92 for AG genotype and G allele, respectively). Although, no statistical significance in the distribution of miR-146a SNPs (rs2910164, rs57095329, and rs2431697) was found, indicating the lack of association between the three SNPs and SLE susceptibility. Significantly, the higher frequency of the AA genotype of miR-146a (rs57095329) was associated with pancytopenia (P < 0.05), while the CT genotype of miR-146a (rs2431697) was associated (P < 0.05) with the antiphospholipid syndrome (APS). SLE patients had significantly higher levels of miR-146a compared to controls (P < 0.05). Elevation of miR-146a was independent of any SNP genotypes. In conclusion, this pilot study shows no association between miR-146a SNPs in our population group and susceptibility to lupus. Studies concerning other miRNAs in larger sample sizes are essential for a better understanding of their role in susceptibility to SLE disease.

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This study is concerned with genetic polymorphisms of miR-146a in Lupus patients.

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The AG genotype and G allele of miR-146a (rs57095329 A/G) might be considered a risk factor.

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No significance in the distribution of miR-146a SNPs (rs2910164, rs57095329, and rs2431697).

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miR-146a level was significantly elevated in SLE irrespective to any SNP genotypes.

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AA genotype of rs57095329 was associated with pancytopenia while the CT genotype of rs2431697 was associated with the APS.

Tim-1 alleviates lupus nephritis-induced podocyte injury via regulating autophagy

Introduction

Lupus nephritis (LN) is a complication of systemic lupus erythematosus (SLE) which seriously threatens the health of people. Tim-1 is known to be associated with the pathogenesis of SLE. However, the role of Tim-1 in LN is still unclear.

Aim of the study

To explore the expression and the potential regulatory molecular mechanism of Tim-1 in LN-induced podocyte injury.

Material and methods

An in vivo model of LN was established to detect the expression of Tim-1, inflammatory cytokines and autophagy-related proteins. Podocytes were treated with immunoglobulin G (IgG) to establish the LN in vitro model and then treated with an autophagy inhibitor. RT-qPCR and western blot were performed to investigate the effect of Tim-1 on inflammatory responses as well as autophagy in podocytes. The function of Tim-1 in IgG-induced podocytes was detected by CCK-8 and flow cytometry, respectively.

Results

Tim-1, L3BII/L3BI ratio and inflammatory cytokines were upregulated in LN mice. Tim-1 notably inhibited IgG-induced inflammatory responses in podocytes via reducing tumor necrosis factor α (TNF-α), interleukin (IL)-6 and IL-1β expression, and it could protect podocytes against LN-induced injury via inducing autophagy. Meanwhile, Tim-1 significantly promoted the proliferation of IgG-induced podocytes via inhibiting apoptosis. The autophagy inhibitor reversed the effect of Tim-1 on inflammatory cytokines and autophagy-related proteins in IgG-treated podocytes.

Conclusions

Tim-1 protects podocytes against LN-induced injury via mediating autophagy, which might serve as a new target for the treatment of LN.

Meta-Analysis of miRNA Variants Associated with Susceptibility to Autoimmune Disease

Purpose

Various studies have shown an association between miRNA polymorphisms and susceptibility to autoimmune disease (AD); however, the results are inconclusive. To evaluate whether miRNA polymorphisms account for a significant risk of AD, a total of 87 articles, including 39431 patients and 56708 controls, were identified to estimate their association with 12 AD subtypes.

Methods

Several electronic databases were searched to analyze population-based studies on the relationship between miRNA variants and AD risk. Fixed effects or random effect models were used in the meta-analysis for the risk assessment.

Results

In our meta-analysis, miR-146a rs2910164/rs57095329 conferred a marginally elevated risk for AD (allele model, OR = 1.08, 95% CI: 1.01-1.15, P = 0.019; allele model, OR = 1.09, 95 CI: 1.05-1.15, P < 0.001, respectively). Furthermore, miR-196a2 rs11614913 was also associated with AD risk (allele model, OR = 0.92, 95% CI: 0.88-0.97, P = 0.001) as well as miR-499 rs3746444 (allele model, OR = 1.16, 95% CI: 1.03-1.29, P = 0.011). In addition, associations were observed between miR-149 rs2292832/miR-27a rs895819 and AD susceptibility in the overall population (allele model, OR = 1.15, 95% CI: 1.06-1.24, P < 0.001; allele model, OR = 1.11, 95% CI:1.01-1.22, P = 0.043, respectively).

Conclusions

Evidence from our systematic review suggests that miR-146a, miR-196a2, miR-499, miR-149, and miR-27a polymorphisms are associated with susceptibility to AD.

miRNA-Mediated Control of B Cell Responses in Immunity and SLE

Loss of B cell tolerance is central to autoimmune diseases such as systemic lupus erythematosus (SLE). As such, the mechanisms involved in B cell development, maturation, activation, and function that are aberrantly regulated in SLE are of interest in the design of targeted therapeutics. While many factors are involved in the generation and regulation of B cell responses, miRNAs have emerged as critical regulators of these responses within the last decade. To date, miRNA involvement in B cell responses has largely been studied in non-autoimmune, immunization-based systems. However, miRNA profiles have also been strongly associated with SLE in human patients and these molecules have proven critical in both the promotion and regulation of disease in mouse models and in the formation of autoreactive B cell responses. Functionally, miRNAs are small non-coding RNAs that bind to complementary sequences located in target mRNA transcripts to mediate transcript degradation or translational repression, invoking a post-transcriptional level of genetic regulation. Due to their capacity to target a diverse range of transcripts and pathways in different immune cell types and throughout the various stages of development and response, targeting miRNAs is an interesting potential therapeutic avenue. Herein, we focus on what is currently known about miRNA function in both normal and SLE B cell responses, primarily highlighting miRNAs with confirmed functions in mouse models. We also discuss areas that should be addressed in future studies and whether the development of miRNA-centric therapeutics may be a viable alternative for the treatment of SLE.

IFN-I Mediates Lupus Nephritis From the Beginning to Renal Fibrosis

Lupus nephritis (LN) is a common complication of systemic lupus erythematosus (SLE) and a major risk factor for morbidity and mortality. The abundant cell-free nucleic (DNA/RNA) in SLE patients, especially dsDNA, is a key substance in the pathogenesis of SLE and LN. The deposition of DNA/RNA-immune complexes (DNA/RNA-ICs) in the glomerulus causes a series of inflammatory reactions that lead to resident renal cell disturbance and eventually renal fibrosis. Cell-free DNA/RNA is the most effective inducer of type I interferons (IFN-I). Resident renal cells (rather than infiltrating immune cells) are the main source of IFN-I in the kidney. IFN-I in turn damages resident renal cells. Not only are resident renal cells victims, but also participants in this immunity war. However, the mechanism for generation of IFN-I in resident renal cells and the pathological mechanism of IFN-I promoting renal fibrosis have not been fully elucidated. This paper reviews the latest epidemiology of LN and its development process, discusses the mechanism for generation of IFN-I in resident renal cells and the role of IFN-I in the pathogenesis of LN, and may open a new perspective for the treatment of LN.