Genetic association of miRNA-146a with systemic lupus erythematosus in Europeans through decreased expression of the gene

Polymorphisms in miRNA genes and their involvement in autoimmune diseases susceptibility

MicroRNAs (miRNAs) are small non-coding RNA molecules that negatively regulate the expression of multiple protein-encoding genes at the post-transcriptional level. MicroRNAs are involved in different pathways, such as cellular proliferation and differentiation, signal transduction and inflammation, and play crucial roles in the development of several diseases, such as cancer, diabetes, and cardiovascular diseases. They have recently been recognized to play a role also in the pathogenesis of autoimmune diseases. Although the majority of studies are focused on miRNA expression profiles investigation, a growing number of studies have been investigating the role of polymorphisms in miRNA genes in the autoimmune diseases development. Indeed, polymorphisms affecting the miRNA genes can modify the set of targets they regulate or the maturation efficiency. This review is aimed to give an overview about the available studies that have investigated the association of miRNA gene polymorphisms with the susceptibility to various autoimmune diseases and to their clinical phenotypes.

microRNAs in the haemostatic system: More than witnesses of thromboembolic diseases?

MicroRNAs (miRNAs) are small endogenous RNAs that post-transcriptionally regulate gene expression. In the last few years, these molecules have been implicated in the regulation of haemostasis, and an increasing number of studies have investigated their relationship with the development of thrombosis. In this review, we discuss the latest developments regarding the role of miRNAs in the regulation of platelet function and secondary haemostasis. We also discuss the genetic and environmental factors that regulate miRNAs. Finally, we address the potential use of miRNAs as prognostic and diagnostic tools in thrombosis.

Identifying Pri-miRNA Transcription Start Sites

MicroRNAs (miRNAs) are small non-coding RNAs that can regulate gene expression playing vital role in nearly all biological pathways. Even though miRNAs have been intensely studied for more than two decades, information regarding miRNA transcription regulation remains limited. The rapid cleavage of primary miRNA transcripts (pri-miRNAs) by Drosha in the nucleus hinders their identification with conventional RNA-seq approaches. Identifying the transcription start site (TSS) of miRNAs will enable genome-wide identification of their expression regulators, including transcription factors (TFs), other non-coding RNAs (ncRNAs) and epigenetic modifiers, providing significant breakthroughs in understanding the mechanisms underlying miRNA expression in development and disease. Here we present a protocol that utilizes microTSS, a versatile computational framework for accurate and single-nucleotide resolution miRNA TSS predictions as well as miRGen, a database of miRNA gene TSSs coupled with genome-wide maps of TF binding sites.

Prognostic role of MIR146A polymorphisms for cardiovascular events in atrial fibrillation

There are few biomarkers able to forecast new thrombotic events in patients with AF. In this framework, microRNAs have emerged as critical players in cardiovascular biology. In particular, miR-146a-5p is recognised as an important negative regulator of inflammation. This study aims to evaluate the prognostic role and biological effect of functional MIR146A polymorphisms, rs2431697 and rs2910164, in non-valvular atrial fibrillation (AF) patients under oral anticoagulation. We studied 901 patients with permanent/paroxysmal AF stabilized for at least six months. Patients were followed-up for two years and adverse cardiovascular events (ACE) were recorded. In vitro studies were performed in monocytes from healthy homozygous for the two genotypes of rs2431697. Rs2910164 had no association with ACE. However, multivariate analysis (adjusted by CHA2DS2–VASc score) revealed that rs2431697TT was associated with adverse cardiovascular events [HR: 1.64 (1.09–2.47); p=0.017]. The predictive value of usefulness of the CHA2DS2–VASc+IL6+rs2431697 for predicting ACE, was statistically better than that predicted by CHA2DS2–VASc+IL6. Functional studies showed that after 24 hours incubation, monocytes from CC individuals showed a 65 % increase in miR-146a-5p levels, while TT individuals only showed a 28 % increase. Indeed, after 24 hours of LPS activation, TT monocytes showed a higher increase in IL6 mRNA expression than CC (52 % vs 26 %). Our study established MIR146A rs2431697 as a prognostic biomarker for ACE in anticoagulated AF patients. These data suggest that TT individuals, when submitted to an inflammatory stress, may be prone to a highest pro-inflammatory state due, in part, to lower levels of miR-146a-5p.

Functional polymorphisms in pre-miR146a and pre-miR499 are associated with systemic lupus erythematosus but not with rheumatoid arthritis or Graves' disease in Mexican patients

Recently, different microRNA (miRNA) gene polymorphisms have been evaluated in patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and Graves’ disease (GD). In the present study, we examined three single-nucleotide polymorphisms (SNPs) located in the pre-miR-146a (rs2910164G/C), pre-miR-196a-2 (rs11614913C/T), and pre-miR-499 (rs3746444A/G) genes. Our study population included 900 Mexican patients with RA, SLE, or GD, as well as 486 healthy control individuals with no family history of inflammatory or autoimmune diseases. Genotyping was performed using TaqMan probes and a 5′ exonuclease assay. None of the investigated SNPs were associated with RA or GD susceptibility under any genetic model (co-dominant, recessive, or dominant). Genotype and allele frequencies of the miR-196a-2 rs11614913C/T polymorphism were similar between SLE cases and controls. In contrast, the miR-146a rs2910164G/C and miR-499 rs3746444A/G polymorphisms were associated with SLE susceptibility. These SNPs were not associated with lupus nephritis (LN). Our results suggest that polymorphisms in miR-146a, miR-196a-2, and miR-499 are not associated with RA or GD susceptibility. This is the first report documenting that the miR-146a rs2910164G/C and miR-499 rs3746444 polymorphisms are associated with SLE susceptibility but not with LN.

Genetics of systemic lupus erythematosus and Sjögren's syndrome: an update

PURPOSE OF REVIEW

To describe the recent studies on the genetics of systemic lupus erythematosus (SLE) and Sjögren's syndrome.

RECENT FINDINGS

We overview the most recent findings on the genetic susceptibility of the diseases and provide information on their genetic similarities and differences.

SUMMARY

SLE and Sjögren's syndrome are two closely related systemic autoimmune diseases that share multiple clinical and molecular aspects, including a significant number of susceptibility genes. Several genome-wide association studies were recently published in different populations that provide a better picture of their molecular mechanisms. It is becoming clear that their genetic architecture is quite well established, but more information is required on expression quantitative trait loci, epigenetic genome-wide analyses, gene × gene interactions and the role of rare variants.

Transancestral mapping and genetic load in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with marked gender and ethnic disparities. We report a large transancestral association study of SLE using Immunochip genotype data from 27,574 individuals of European (EA), African (AA) and Hispanic Amerindian (HA) ancestry. We identify 58 distinct non-HLA regions in EA, 9 in AA and 16 in HA (∼50% of these regions have multiple independent associations); these include 24 novel SLE regions (P<5 × 10⁻⁸), refined association signals in established regions, extended associations to additional ancestries, and a disentangled complex HLA multigenic effect. The risk allele count (genetic load) exhibits an accelerating pattern of SLE risk, leading us to posit a cumulative hit hypothesis for autoimmune disease. Comparing results across the three ancestries identifies both ancestry-dependent and ancestry-independent contributions to SLE risk. Our results are consistent with the unique and complex histories of the populations sampled, and collectively help clarify the genetic architecture and ethnic disparities in SLE.

Systemic lupus erythematosus (SLE) is an autoimmune disease with a strong ethnic and gender bias. In a transancestral genetic association study, Langefeld et al. identify 24 novel regions associated with risk to lupus and propose a cumulative hits hypothesis for loci conferring risk to SLE.

Omics studies: their use in diagnosis and reclassification of SLE and other systemic autoimmune diseases

Omics studies of systemic autoimmune diseases (SADs) in general, and SLE in particular, have delivered isolated information from transcriptome, epigenome, genome, cytokine and metabolome analyses. Such analyses have resulted in the identification of disease susceptibility genes and the description of IFN expression signatures, allowing extensive insight into the mechanisms of disease and the development of new therapies. Access to such technologies allows the recognition of patterns of disease at a pathway level, thereby, to reclassify SLE and other SADs and to develop new therapeutics from a personalized perspective. The use of omic information allows the discovery of correlative patterns involving drugs not currently suspected to be of value in SADs. In this review, we summarize the omics findings for SLE and propose ways of using the data for the identification of new biomarkers, finding new drugs and reclassifying patients not only with SLE, but also with other SADs.

Two Single Nucleotide Polymorphisms (rs2431697 and rs2910164) of miR-146a Are Associated with Risk of Coronary Artery Disease

The coronary artery disease (CAD) is one of the most severe cardiovascular diseases. MicroRNA-146a (miR-146a) influences the pathology of cardiovascular diseases. Two single nucleotide polymorphisms (SNPs) of miR-146a (rs2431697 and rs2910164) have been reported to alter the function or expression of microRNA. The purpose of this study is to evaluate the association between miR-146a gene polymorphism and the risk of CAD in the Chinese population. A total of 353 CAD patients and 368 controls were recruited, and SNPs were analyzed by the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and Sequenom MassARRAY system. The gene frequencies of rs2431697 and rs2910164 were significantly different between the two groups. The mutant type (T allele) of rs2431697 and wild type (C allele) of rs2910164 were more frequent in CAD patients. T allele carriers in rs2431697 had an increased CAD risk, while G allele of rs2910164 decreased the risk of CAD significantly. In conclusion, we found that the T allele of rs2431697 was a risk factor of CAD in the Chinese population. Meanwhile, we demonstrated that the G allele of rs2910164 decreased the susceptibility of CAD.

MicroRNA-146a reduces MHC-II expression via targeting JAK/STAT signaling in dendritic cells after stem cell transplantation

Acute Graft-versus-host disease (GVHD) is a major immunological complication after allogeneic hematopoietic cell transplantation and a better understanding of the molecular regulation of the disease could help to develop novel targeted therapies. Here we found that a G/C polymorphism within the human microRNA-146a (miR-146a) gene of transplant-recipients, which causes reduced miR-146a levels, was strongly associated with the risk of developing severe acute GVHD (n=289). In mice, deficiency of miR-146a in the hematopoietic system or transfer of recipient-type miR 146a^-/- dendritic cells (DCs) enhanced GVHD, while miR-146a mimic-transfected-DCs ameliorated disease. Mechanistically, lack of miR-146a enhanced JAK2 STAT1-pathway activity, which led to higher expression of class II-transactivator (CIITA) and consecutively increased MHCII-levels on DCs. Inhibition of JAK1/2 or CIITA knockdown in DCs prevented miR-146a^-/- DC-induced GVHD exacerbation. Consistent with our findings in mice, patients with the miR-146a polymorphism rs2910164 in hematopoietic cells displayed higher MHCII levels on monocytes, which could be targeted by JAK1/2-inhibition.

Our findings indicate that the miR-146a polymorphism rs2910164 identifies patients at high risk for GVHD before allo HCT. Functionally we show that miR-146a acts as a central regulator of recipient-type DC activation during GVHD by dampening the pro-inflammatory JAK-STAT/CIITA/MHCII axis, which provides a scientific rationale for early JAK1/2-inhibition in selected patients.

Associations of microRNA single nucleotide polymorphisms and disease risk and pathophysiology

Single nucleotide polymorphisms (SNPs) are genetic variations that contribute to human phenotypes associated with various diseases. SNPs are involved in the regulation of a broad range of physiological and pathological processes, such as cellular senescence, apoptosis, inflammation, and immune response, by upregulating the expression of classical inflammation markers. Recent studies have suggested that SNPs located in gene-encoding microRNAs (miRNAs) affect various aspects of diseases by regulating the expression or activity of miRNAs. In the last few years, miRNA polymorphisms that increase and/or reduce the risk of developing many diseases, such as cancers, autoimmune diseases, and cardiovascular diseases, have attracted increasing attention not only because of their involvement in the pathophysiology of diseases but also because they can be used as prognostic biomarkers for a variety of diseases. In this review, we summarize the relationships between miRNA SNPs and the pathophysiology and risk of diseases.

Pharmacological effects of β-d-mannuronic acid (M2000) on miR-146a, IRAK1, TRAF6 and NF-κB gene expression, as target molecules in inflammatory reactions

BACKGROUND

Impaired expression and function of microRNAs (miRNAs) are involved in the pathogenesis of many autoimmune and inflammatory diseases. Moreover, there is a close relationship between TLRs and miRNAs and impairment in regulating their expression which can play a vital role in the immunopathogenesis of many inflammatory reactions. This research aimed to study the pharmaceutical effects of M2000 (β-d-mannuronic acid) on the expression of miR-146a and its two target molecules (IRAK1 and TRAF6), and the transcription factor NF-κB in the HEK-Blue hTLR2 cell line.

METHODS

The cytotoxicity of M2000 was assessed by the MTT assay, and the qRT-PCR technique was employed in the presence and absence of M2000 treatment to measure gene-expression levels of miR-146a, IRAK1, TRAF6, and NF-κB.

RESULTS

MTT assay indicated that M2000 (before the concentration of 500μg/ml) had no cytotoxic effect on HEK-Blue hTLR2 cells. Our results showed that M2000 at low and high doses (5 and 25μg/well) could significantly reduce gene expression levels of miR-146a (p<0.01). Furthermore, it was found that this medication at two different doses could considerably decrease IRAK1 and TRAF6 gene expression (p<0.001). Moreover, this study revealed that expression level of NF-κB also significantly declined at these two doses (p<0.01).

CONCLUSIONS

This study for the first time shows that M2000 as a novel NSAID with immunosuppressive properties is able to modify TLR signaling through suppressing the adaptor molecules IRAK1 and TRAF6, the transcription factor NF-κB and miR-146a as a new therapeutic approach.

MicroRNA-146a rs2910164 is associated with severe preeclampsia in Black South African women on HAART

BACKGROUND

South African (SA) Black women have a high prevalence of preeclampsia and HIV, both conditions associated with increased inflammation. miR-146a is an inflammatory-associated miR and a common single nucleotide polymorphism (rs2910164) has been associated with several disease conditions. To date, this SNP has not been investigated in SA Black women. We therefore aimed to investigate the miR-146a G > C SNP in SA Blacks with preeclampsia, and further examine possible association among preeclamptic (PE) women with HIV infection on HAART.

METHODS

This hospital-based, case-control study included 95 normotensive and 98 PE Black SA women (aged 16-46 years old). Patients and controls were genotyped by PCR-RFLP. Using a Cytometric Bead Array assay, serum cytokine levels (including Th1- and Th2-related cytokines) were determined in 4 groups of pregnant women, viz: normotensive, HIV infected, PE + HIV infected, and PE women.

RESULTS

There was no significant association between the miR-146a polymorphism and PE susceptibility in our data. However, in the subgroup analyses, the variant genotypes (GC/CC) were significantly associated with lower severe PE risk (p = 0.0497), more especially in the presence of HIV and HAART (p = 0.017). In the normotensive group, the variant genotypes were associated with lower IL-2 in both the total normotensive group (269 ± 1.26 (36) vs 273 ± 1.31 (23); p = 0.035) and the PE HIV+ sub-group 265 ± 1.54 (19) vs 271 ± 1.38 (11); p = 0.008).

CONCLUSIONS

Our study suggests that miR-146a rs2910164 polymorphism might not be associated with PE susceptibility, cytokines or related features. However, the miR-146a GC/CC genotype might reduce susceptibility to severe PE, which might be further influenced by the presence of co-morbid HIV infection among pregnant women on HAART. This variant genotype may also be associated with reduced circulating IL-2 levels and thus reduced pro-inflammatory response in normotensive women, which may be further influenced by the presence of HIV infection and HAART.

Polymorphisms in MIR499A and MIR125A gene are associated with autoimmune thyroid diseases

BACKGROUND

Single nucleotide polymorphisms (SNPs) of the miR-146a, miR-499a and miR-125a have been shown to be associated with the susceptibility to several autoimmune diseases. This study was conducted to identify the association of SNPs rs2910164, rs57095329, rs3746444 and rs12976445 with autoimmune thyroid diseases (AITDs) in a Chinese Han population.

METHODS

We enrolled 1061 patients with AITDs, including 701 patients with Graves' disease (GD) and 360 patients with Hashimoto's thyroiditis (HT), and 938 healthy individuals for a case-control genetic association study. Four SNPs were selected for genotyping by multiplex polymerase chain reaction and ligase detection reaction.

RESULTS

The frequencies of rs3746444 genotypes in patients with AITD and GD differed significantly from those in the controls. The frequencies of rs12976445 genotypes in patients with HT differed significantly from those in the controls. The frequencies of allele C in HT groups were significantly higher than those in control group. For the rs3746444 polymorphism, genetic associations between the combinational genotype and AITD/GD risk were observed in the dominant model, recessive model, and overdominant model. For the rs12976445 polymorphism, genetic associations between the combinational genotype and HT risk were also found in the dominant model and overdominant model. Moreover, gene-sex interactions were identified by GMDR and 2 × 2 crossover analysis.

CONCLUSIONS

Our results suggest rs3746444 (miR-499a) and rs12976445 (miR-125a) associated with AITD susceptibility and potential gene-sex interactions between the four polymorphisms and AITD.

Identification of more objective biomarkers for Blood-Stasis syndrome diagnosis

Background

Blood-stasis syndrome (BSS) is one of the Traditional Chinese medicine (TCM) syndrome differentiations that are commonly seen in stroke and ischemic heart diseases; however, the BSS differentiation criterion is not standardized. More objective biomarkers for BSS diagnosis are needed.

Methods

Acute ischemic stroke (AIS) or unstable angina (UA) patients with BSS and healthy controls were enrolled. The miRNA and mRNA expression profiles of UA patients and AIS patients were compared to those of healthy controls to identify the differentially expressed miRNA and mRNA of BSS. Bioinformatics analysis was used to identify significantly deregulated miRNAs and mRNAs correlated to BSS. QRT-PCR was performed to validate the bioinformatics analysis results.

Results

Approximately 401 mRNAs and 11 miRNAs were differentially expressed in both UA and AIS patients compared to healthy controls. Gene ontology (GO) functional analysis was performed, and multiple GO terms were enriched. Among the overlapping DE miRNAs and mRNAs, miR-146b-5p, -199a-5p and 23 targeted mRNAs were pivotal genes in the BSS genomic characteristics. These 2 miRNAs and 23 mRNAs formed network-type biomarkers for BSS.

Conclusions

The genomic characteristics of BSS were shown in this study. miR-146b-5p, -199a-5p and the 23 targeted mRNAs formed a diagnostic network for BSS. Further improvement and validation of this diagnostic network might lead to more objective diagnostic criteria for BSS.

Post-transcriptional Regulation of BRCA2 through Interactions with miR-19a and miR-19b

Breast cancer type 2, early onset susceptibility gene (BRCA2) is a major component of the homologous recombination DNA repair pathway. It acts as a tumor suppressor whose function is often lost in cancers. Patients with specific mutations in the BRCA2 gene often display discrete clinical, histopathological, and molecular features. However, a subset of sporadic cancers has wild type BRCA2 and display defects in the homology-directed repair pathway, which is the hallmark of ‘BRCAness.’ The mechanisms by which BRCAness arises are not well understood but post-transcriptional regulation of BRCA2 gene expression by microRNAs (miRNAs) may contribute to this phenotype. Here, we examine the post-transcriptional effects that some members of the six-miRNA cluster known as the miR-17/92 cluster have on the abundance of BRCA2’s messenger RNA (mRNA) and protein. We discuss two interactions involving the miR-19a and miR-19b members of the cluster and the 3′UTR of BRCA2’s mRNA. We investigated these miRNA:mRNA interactions in 15 cell lines derived from pancreatic, breast, colon, and kidney tissue. We show that over-expression of these two miRNAs results in a concomitant decrease of BRCA2’s mRNA and protein expression in a subset of the tested cell lines. Additionally, using luciferase reporter assays we identified direct interactions between miR-19a/miR-19b and a miRNA response element (MRE) in BRCA2’s 3′UTR. Our results suggest that BRCA2 is subject to a complex post-transcriptional regulatory program that has specific dependencies on the genetic and phenotypic background of cell types.

Follicular Helper T Cells in Systemic Lupus Erythematosus: Why Should They Be Considered as Interesting Therapeutic Targets?

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by B cell hyperactivity leading to the production of autoantibodies, some of which having a deleterious effect. Reducing autoantibody production thus represents a way of controlling lupus pathogenesis, and a better understanding of the molecular and cellular factors involved in the differentiation of B cells into plasma cells could allow identifying new therapeutic targets. Follicular helper T cells (T_FH) represent a distinct subset of CD4⁺ T cells specialized in providing help to B cells. They are required for the formation of germinal centers and the generation of long-lived serological memory and, as such, are suspected to play a central role in SLE. Recent advances in the field of T_FH biology have allowed the identification of important molecular factors involved in T_FH differentiation, regulation, and function. Interestingly, some of these T_FH-related molecules have been described to be dysregulated in lupus patients. In the present review, we give an overview of the aberrant expression and/or function of such key players in lupus, and we highlight their potential as therapeutic targets.

The genetic basis of systemic lupus erythematosus: What are the risk factors and what have we learned

The genome-wide association study is a free-hypothesis approach based on screening of thousands or even millions of genetic variants distributed throughout the whole human genome in relation to a phenotype. The relevant role of the genome-wide association studies in the last decade is undisputed because it has permitted to elucidate multiple risk genetic factors associated with the susceptibility to several human complex diseases. Regarding systemic lupus erythematosus (SLE) this approach has allowed to identify more than 60 risk loci for SLE susceptibility across populations to date, increasing our understanding on the pathogenesis of this disease. We present the latest findings in the genetic of SLE across populations using genome-wide approaches. These studies revealed that most of the genetic risk is shared across borders and ethnicities. Finally, we focus on describing the most important risk loci for SLE attempting to cover the genetic findings in relation to functional polymorphisms, such as missense single nucleotide polymorphisms (SNPs) or regulatory variants involved in the development of the disease. The functional studies try to identify the causality of some GWAS-associated variants, many of which fall in non-coding regions of the genome, suggesting a regulatory role. Many loci show an environmental interaction, another aspect revealed by the studies of epigenetic modifications and those associated with genetic variants. Finally, new-generation sequencing technologies can open other paths in the research on SLE genetics, the role of rare variants and the detailed identification of causal regulatory variation. The clinical relevance of the genetic factors will be shown when we are able to use them or in combination with other molecular measurements to re-classify a heterogeneous disease such as SLE.

Advances in lupus genetics

PURPOSE OF REVIEW

The field of systemic lupus erythematosus (SLE) genetics has been advancing rapidly in recent years. This review will summarize recent advances in SLE genetics.

RECENT FINDINGS

Genome-wide-association and follow-up studies have greatly expanded the list of associated polymorphisms, and much current work strives to integrate these polymorphisms into immune system biology and the pathogenic mediators involved in the disease. This review covers some current areas of interest, including genetic studies in non-European SLE patient populations, studies of pathogenic immune system subphenotypes such as type I interferon and autoantibodies, and a rapidly growing body of work investigating the functional consequences of the genetic polymorphisms associated with SLE.

SUMMARY

These studies provide a fascinating window into human SLE disease biology. As the work proceeds from genetic association signal to altered human biology, we move closer to tailoring interventions based upon an individual's genetic substrate.

Solving the genetic puzzle of systemic lupus erythematosus

In recent years, genome-wide association studies on systemic lupus erythematosus (SLE) have significantly improved our understanding of the genetic architecture of this prototypic autoimmune disease. However, there is still a long way to go before we can fully understand the genetic factors for this very heterogeneous disease and the interplays between environmental factors and genetic predisposition that lead to the pathogenesis of SLE. Here we summarize the recent advances in our understanding of the genetics of SLE and discuss the future directions towards fully elucidating the mechanisms of this disease.

MicroRNAs in lupus

Systemic lupus erythematosus is a prototypic autoimmune disease characterized by the production of an array of pathogenic autoantibodies, including high-affinity anti-dsDNA IgG antibodies, which play an important role in disease development and progression. Lupus preferentially affects women during their reproductive years. The pathogenesis of lupus is contributed by both genetic factors and epigenetic modifications that arise from exposure to the environment. Epigenetic marks, including DNA methylation, histone post-translational modifications and microRNAs (miRNAs), interact with genetic programs to regulate immune responses. Epigenetic modifications influence gene expression and modulate B cell functions, such as class-switch DNA recombination, somatic hypermutation and plasma cell differentiation, thereby informing the antibody response. Epigenetic dysregulation can result in aberrant antibody responses to exogenous antigens or self-antigens, such as chromatin, histones and dsDNA in lupus. miRNAs play key roles in the post-transcriptional regulation of most gene-regulatory pathways and regulate both the innate and adaptive immune responses. In mice, dysregulation of miRNAs leads to aberrant immune responses and development of systemic autoimmunity. Altered miRNA expression has been reported in human autoimmune diseases, including lupus. The dysregulation of miRNAs in lupus could be the result of multiple environmental factors, such as sex hormones and viral or bacterial infection. Modulation of miRNA is a potential therapeutic strategy for lupus.

Common MIR146A Polymorphisms in Chinese Ankylosing Spondylitis Subjects and Controls

Common polymorphisms of microRNA gene MIR146A were reported as associated with different autoimmune diseases, include systemic lupus erythematosus, psoriatic arthritis, asthma and ankylosing spondylitis. In this study we investigated MIR146A SNPs in Chinese people with ankylosing spondylitis. Three common SNPs: rs2910164, rs2431697 and rs57095329 were selected and genotyped in 611 patients and 617 controls. We found no association between these SNPs and ankylosing spondylitis in our samples.

Extracellular Vesicles as Biomarkers of Systemic Lupus Erythematosus

Systemic lupus erythematosus is an autoimmune disease that predominantly affects women and typically manifests in multiple organs. The damage caused by this disorder is characterized by a chronic inflammatory state. Extracellular vesicles (EVs), including microvesicles (also known as microparticles), apoptotic bodies, and exosomes, are recognized vehicles of intercellular communication, carrying autoantigens, cytokines, and surface receptors. Therefore, the evidence of EVs and their cargo as biomarkers of autoimmune disease is rapidly expanding. This review will focus on biogenesis of extracellular vesicles, their pathophysiological roles, and their potential as biomarkers and therapeutics in inflammatory disease, especially in systemic lupus erythematosus.

Association between rs2431697 T allele on 5q33.3 and systemic lupus erythematosus: case-control study and meta-analysis

rs2431697 is located on 5q33.3, between pituitary tumor-transforming gene 1 and miR-146a. Several studies have estimated the association between rs2431697 and systemic lupus erythematosus risk. However, the results were inconsistent. A case-control study was carried out to explore the association between rs2431697 and systemic lupus erythematosus risk in a central Chinese population. Meta-analyses combining present with previous studies were conducted to further explore the association. Our case-control study included 322 cases and 353 controls. rs2431697 T allele was associated with increased risk of systemic lupus erythematosus (odds ratios (ORs) = 1.461, 95 % confidence intervals (CI) 1.091–1.957, P = 0.011). The association was stronger between T allele and the risk of anti-double-stranded DNA (dsDNA)-positive systemic lupus erythematosus (OR = 2.510, 95 % CI 1.545–4.077, P < 0.001). The meta-analyses included 8648 systemic lupus erythematosus patients and 10947 controls. rs2431697 T allele had an overall OR of 1.262 (95 % CI 1.205–1.323, P < 0.001) under fixed-effects model. After stratified by ethnicity, I² reduced from 24.3 to 0 %. T allele had an OR of 1.213 (95 % CI 1.145–1.284, P < 0.001) in European descendant and 1.365 (95 % CI 1.259–1.480, P < 0.001) in Asian under fixed-effects model. Data on women were also extracted, and T allele had an OR of 1.337 (95 % CI 1.162–1.539, P < 0.001) under random-effects model. The pooled ORs were not influenced by each study in sensitivity analyses. There were no publication biases observed in these analyses. The results from our case-control study and the meta-analyses indicate that rs2431697 T allele significantly associates with the increased risk of systemic lupus erythematosus.

Meta-analysis of microRNA-146a rs2910164 G>C polymorphism association with autoimmune diseases susceptibility, an update based on 24 studies

BACKGROUND

Published data showed that the susceptibility of autoimmune diseases (ADs) was associated with the polymorphism rs2910164 in microRNA-146a (miR-146a). However, the results remain controversial so far. Two meta-analyses published in 2013 and 2014 came to opposite conclusions. In order to derive a more precise estimation of the relationship, we performed this meta-analysis.

METHODS

We searched the PubMed, OvidSP and CNKI databases (published prior to September 8th, 2014) and extracted data from eligible studies. The procedure of meta-analysis was performed by using the Stata 12.0 software. Random effect model or fixed effect model were chosen respectively, according to the between study heterogeneities.

RESULTS

A total of 24 case-control studies, 11 more than previous meta-analysis on this topic, were involved. We took stratified analyses by different ethnicities and different types of diseases in different genetic models. In Caucasian subgroup, significant increased risks of GC genotype and GC+CC genotype with ADs susceptibility were found in heterozygote model (GC vs GG, OR = 1.38, 95% CI 1.04-1.83, p = 0.024) and dominant model (GC+CC vs GG, OR = 1.37, 95% CI 1.01-1.85, p = 0.041), respectively. Meanwhile, in other disease subgroup, significant increased risks of C allele, CC genotype and GC+CC genotype were found in allele model (C vs G, OR = 1.16, 95% CI 1.04-1.31, p = 0.010), homozygote model (CC vs GG, OR = 1.42, 95% CI 1.10-1.84, p = 0.006) and dominant model (GC+CC vs GG, OR = 1.25, 95% CI 1.04-1.51, p = 0.020), respectively.

CONCLUSIONS

MiR-146a rs2910164 G>C polymorphism was associated with the susceptibility of ADs.

Association analyses confirm five susceptibility loci for systemic lupus erythematosus in the Han Chinese population

Introduction

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease. Currently, numerous genetic loci of SLE have been confirmed. Here we try to further explore additional genes contributing to SLE susceptibility in this study.

Methods

Forty nine single nucleotide polymorphisms (SNPs) with moderate-risk for SLE in previous study were genotyped in a large-scale replication study with a total of 3,522 cases and 8,252 controls using the Sequenom Massarray system. Association analyses were performed using logistic regression with gender or sample cohorts as a covariate through PLINK 1.07 software.

Results

This replication effort confirmed five reported SLE susceptibility loci reaching genome-wide levels of significance (P_meta <5.00 × 10⁻⁰⁸): TNFSF4 (rs1418190, odds ratio (OR) = 0.81, P_meta = 1.08 × 10⁻⁰⁸; rs4916219, OR = 0.80, P_meta = 7.77 × 10⁻⁰⁹), IRF8 (rs2934498, OR = 1.25, P_meta = 4.97 × 10⁻⁰⁹), miR-146a (rs2431697, OR = 0.69, P_meta = 1.15 × 10⁻²²), CD44 (rs2732547, OR = 0.82, P_meta = 1.55 × 10⁻¹¹), and TMEM39A (rs12494314, OR = 0.84, P_meta = 1.01 × 10⁻⁰⁹). Further logistic regression analysis indicated that the genetic effects within TNFSF4 detected in this study are independent from our previously reported signals.

Conclusions

This study increases the number of established susceptibility loci for SLE in Han Chinese population and highlights the contribution of multiple variants of modest effect. Although further studies will be required to identify the causal alleles within these loci, the findings make a significant step forward in our understanding of the genetic contribution to SLE in Chinese population.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0602-9) contains supplementary material, which is available to authorized users.

The plasmacytoid dendritic cell as the Swiss army knife of the immune system: molecular regulation of its multifaceted functions

Plasmacytoid dendritic cells (pDC) have been regarded as the "professional type I IFN-producing cells" of the immune system following viral recognition that relies on the expression of TLR7 and TLR9. Furthermore, pDC link the innate and adaptive immune systems via cytokine production and Ag presentation. More recently, their ability to induce tolerance and cytotoxicity has been added to their "immune skills." Such a broad range of actions, resembling the diverse functional features of a Swiss army knife, requires strong and prompt molecular regulation to prevent detrimental effects, including autoimmune pathogenesis or tumor escape. Over the last decades, we and other investigators have started to unravel some aspects of the signaling pathways that regulate the various functions of human pDC. In this article, we review aspects of the molecular regulatory mechanisms to control pDC function in light of their multifaceted roles during immunity, autoimmunity, and cancer.

MicroRNA-146a regulates ICOS-ICOSL signalling to limit accumulation of T follicular helper cells and germinal centres

Tight control of T follicular helper (Tfh) cells is required for optimal maturation of the germinal centre (GC) response. The molecular mechanisms controlling Tfh-cell differentiation remain incompletely understood. Here we show that microRNA-146a (miR-146a) is highly expressed in Tfh cells and peak miR-146a expression marks the decline of the Tfh response after immunization. Loss of miR-146a causes cell-intrinsic accumulation of Tfh and GC B cells. MiR-146a represses several Tfh-cell-expressed messenger RNAs, and of these, ICOS is the most strongly cell autonomously upregulated target in miR-146a-deficient T cells. In addition, miR-146a deficiency leads to increased ICOSL expression on GC B cells and antigen-presenting cells. Partial blockade of ICOS signalling, either by injections of low dose of ICOSL blocking antibody or by halving the gene dose of Icos in miR-146a-deficient T cells, prevents the Tfh and GC B-cell accumulation. Collectively, miR-146a emerges as a post-transcriptional brake to limit Tfh cells and GC responses.

Maturation of antibody-producing B cells in germinal centers is orchestrated by T follicular helper cells. Here Pratama et al. show that miR-146a negatively regulates T follicular helper cells by targeting ICOS-ICOS ligand signaling in germinal centers.

Genetic association of CD247 (CD3ζ) with SLE in a large-scale multiethnic study

A classic T-cell phenotype in systemic lupus erythematosus (SLE) is the downregulation and replacement of the CD3ζ chain that alters T-cell receptor signaling. However, genetic associations with SLE in the human CD247 locus that encodes CD3ζ are not well established and require replication in independent cohorts. Our aim was therefore to examine, localize and validate CD247-SLE association in a large multiethnic population. We typed 44 contiguous CD247 single-nucleotide polymorphisms (SNPs) in 8922 SLE patients and 8077 controls from four ethnically distinct populations. The strongest associations were found in the Asian population (11 SNPs in intron 1, 4.99 × 10(-4) < P < 4.15 × 10(-2)), where we further identified a five-marker haplotype (rs12141731-rs2949655-rs16859085-rs12144621-rs858554; G-G-A-G-A; P(hap) = 2.12 × 10(-5)) that exceeded the most associated single SNP rs858554 (minor allele frequency in controls = 13%; P = 4.99 × 10(-4), odds ratio = 1.32) in significance. Imputation and subsequent association analysis showed evidence of association (P < 0.05) at 27 additional SNPs within intron 1. Cross-ethnic meta-analysis, assuming an additive genetic model adjusted for population proportions, showed five SNPs with significant P-values (1.40 × 10(-3) < P< 3.97 × 10(-2)), with one (rs704848) remaining significant after Bonferroni correction (P(meta) = 2.66 × 10(-2)). Our study independently confirms and extends the association of SLE with CD247, which is shared by various autoimmune disorders and supports a common T-cell-mediated mechanism.

Genetic Variation in miR-146a Is Not Associated with Susceptibility to IgA Nephropathy in Adults from a Chinese Han Population

BACKGROUND

MicroRNA 146a (miR-146a) is a 19 to 23 nucleotide long, small non-coding RNA with gene regulatory functions that has influence on the pathogenesis of many diseases. A single nucleotide polymorphism (rs2910164 C>G) in pre-miR-146a is correlated with the expression of miR-146a. The aim of this study was to perform an association analysis of rs2910164 with IgA nephropathy in adult patients from a Chinese Han population.

METHODS

A total of 145 patients with renal biopsy-proved IgA nephropathy (IgAN) and 179 healthy controls were recruited to the current study. rs2910164 was genotyped by the polymerase chain reaction (PCR) and high-resolution melting methods (HRM). Clinical characteristics and pathology grading of patients with IgAN were recorded at the time of kidney biopsy.

RESULT

There were significant differences among the population of patients grouped by different age of onset in a co-dominant model (CG vs. CC vs. GG) (p = 0.033) and a recessive model (CG+CC vs. GG) (p = 0.001). However, no significant difference was observed in the distribution of genotypes between cases and controls (p = 0.144). There was also no significant difference between rs2910164 and patient quantitative traits (all p > 0.003) or different pathology grading (Lee's grading system and tubular atrophy/interstitial fibrosis in the Oxford classification) (all p > 0.05).

CONCLUSIONS

There was no association of rs2910164 with susceptibility to IgAN in adults from a Chinese Han population. However, rs2910164 was correlated with the age of onset of IgAN in adult patients.

Epigenetics and lupus

Systemic lupus erythematosus (SLE) is among the systemic autoimmune diseases whose complex pathogenesis involves both genetic and environmental factors. Epigenetic dysregulation resulting in overexpression of certain genes in some of the key immune cells, such as T cells, has been incriminated in the pathophysiology of SLE. Epigenetics is defined as transmissible and reversible modifications in gene expression without alterations in the nucleotide sequences. Epigenetic information is carried chiefly by DNA itself, histones, and noncoding RNAs. Several epigenetic mechanisms may play a role in SLE pathogenesis. This review discusses the various epigenetic mechanisms that regulate gene expression and provides examples relevant to SLE.

MicroRNA-146a: A Dominant, Negative Regulator of the Innate Immune Response

MicroRNAs (miRNAs) are a class of small non-coding RNA molecules that can play critical roles as regulators of numerous pathways and biological processes including the immune response. Emerging as one of the most important miRNAs to orchestrate immune and inflammatory signaling, often through its recognized target genes, IRAK1 and TRAF6, is microRNA-146a (miR-146a). MiR-146a is one, of a small number of miRNAs, whose expression is strongly induced following challenge of cells with bacterial endotoxin, and prolonged expression has been linked to immune tolerance, implying that it acts as a fine-tuning mechanism to prevent an overstimulation of the inflammatory response. In other cells, miR-146a has been shown to play a role in the control of the differentiation of megakaryocytic and monocytic lineages, adaptive immunity, and cancer. In this review, we discuss the central role prescribed to miR-146a in innate immunity. We particularly focus on the role played by miR-146a in the regulation and signaling mediated by one of the main pattern recognition receptors, toll/IL-1 receptors (TLRs). Additionally, we also discuss the role of miR-146a in several classes of autoimmune pathologies where this miRNA has been shown to be dysregulated, as well as its potential role in the pathobiology of neurodegenerative diseases.

MiR-146a regulates the TRAF6/TNF-axis in donor T cells during GVHD

This study deciphers the regulatory role of miR-146a during GVHD in mice. In humans, the minor genotype of the SNP rs2910164, which reduces expression of miR-146a, was associated with higher GVHD severity.

Key principles of miRNA involvement in human diseases

Although rapid progress in our understanding of the functions of miRNA has been made by experimentation and computational approach, a considerable effort still has to be done in determining the general principles that govern the miRNA's mode of action in human diseases. We will further discuss how these principles are being progressively approached by molecular studies, as well as the importance of miRNA in regulating different target genes and functions in specific biological contexts. There is a great demand to understand the principles of context - specific miRNA target recognition in order to design future experiments and models of normal developmental and disease states.

Comprehensive review of genetic association studies and meta-analysis on miRNA polymorphisms and rheumatoid arthritis and systemic lupus erythematosus susceptibility

BACKGROUND

MicroRNAs (miRNAs), small RNA molecules, play a role in the development and differentiation of immune cells in both innate and adaptive immune responses. Our study was aimed to investigate the association between three miRNA polymorphism and rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE) by using meta-analysis approach.

METHODS

A PubMed database search was conducted during August 2013 to identify case-control studies of miRNAs and RA or SLE risk. Two authors independently extracted information on the study design, the characteristics of the study participants, exposure and outcome assessments. The fix-effects and random-effects models were used for the risk estimates by Stata 11.0 software.

RESULTS

Our meta-analysis of six case-control studies involving a total of 998 RA cases and 1493 controls identified no significant association between mir-146a rs2910164 and RA, with an overall OR of 0.843 (95% CI=0.642-1.105; CC vs. GG). No association was observed in three studies with a total of 1532 cases and 2168 controls between miR-146a rs2910164 and SLE risk (OR=0.911, 95% CI=0.710-1.171; CC vs. GG). Three studies with a total of 529 cases and 595 controls evaluated the mir-499 rs3746444 polymorphism and its association with RA. There was a decreased overall risk of RA under the allelic and genotypic models [OR=0.616, 95% CI=0.384-0.981, (T vs. C allele) and OR=0.386, 95% CI=0.226-0.659, (TT vs. CC)]. Two studies with 4826 cases and 4181 controls evaluated miR-146a rs57095329 and its association with SLE. There was a significant association between miR-146a rs57095329 and SLE (OR=1.263, 95% CI=1.136-1.405, G vs. A allele).

CONCLUSIONS

The present meta-analysis suggests important roles for the mir-499 rs3746444 polymorphism in RA, especially in the Caucasian population and for miR-146a rs57095329 polymorphism in SLE. Further studies with large sample size are needed to confirm these associations.

Pre-miR-146a (rs2910164 G>C) single nucleotide polymorphism is genetically and functionally associated with leprosy

Mycobacterium leprae infects macrophages and Schwann cells inducing a gene expression program to facilitate its replication and progression to disease. MicroRNAs (miRNAs) are key regulators of gene expression and could be involved during the infection. To address the genetic influence of miRNAs in leprosy, we enrolled 1,098 individuals and conducted a case-control analysis in order to study four miRNAs genes containing single nucleotide polymorphism (miRSNP). We tested miRSNP-125a (rs12975333 G>T), miRSNP-223 (rs34952329 *>T), miRSNP-196a-2 (rs11614913 C>T) and miRSNP-146a (rs2910164 G>C). Amongst them, miRSNP-146a was the unique gene associated with risk to leprosy per se (GC OR = 1.44, p = 0.04; CC OR = 2.18, p = 0.0091). We replicated this finding showing that the C-allele was over-transmitted (p = 0.003) using a transmission-disequilibrium test. A functional analysis revealed that live M. leprae (MOI 100∶1) was able to induce miR-146a expression in THP-1 (p<0.05). Furthermore, pure neural leprosy biopsies expressed augmented levels of that miRNA as compared to biopsy samples from neuropathies not related with leprosy (p = 0.001). Interestingly, carriers of the risk variant (C-allele) produce higher levels of mature miR-146a in nerves (p = 0.04). From skin biopsies, although we observed augmented levels of miR-146a, we were not able to correlate it with a particular clinical form or neither host genotype. MiR-146a is known to modulate TNF levels, thus we assessed TNF expression (nerve biopsies) and released by peripheral blood mononuclear cells infected with BCG Moreau. In both cases lower TNF levels correlates with subjects carrying the risk C-allele, (p = 0.0453 and p = 0.0352; respectively), which is consistent with an immunomodulatory role of this miRNA in leprosy.

In spite of the successful drug therapy, leprosy is still affecting people worldwide. It is well known that host genetic background influences leprosy development and that genetic variants have been associated with the disease. Therefore we conducted a study to evaluate the role of microRNAs (miRNAs) polymorphisms in leprosy. We observed that a polymorphism in miR-146a is associated with the risk to develop leprosy in Brazilians. Based on the analysis of clinical specimens, we found that the genetic variant was correlated with elevated levels of miR-146a and it is also a negative regulator of tumor necrosis factor (TNF), an important inflammatory mediator in the leprosy context. These findings provide tenable evidences that miR-146a is important in the control of gene expression during M. leprae infection and also may contribute with leprosy development by controlling TNF levels.

Clinical perspectives on lupus genetics: advances and opportunities

In recent years, genome-wide association studies have led to an expansion in the identification of regions containing confirmed genetic risk variants within complex human diseases, such as systemic lupus erythematosus (SLE). Many of the strongest SLE genetic associations can be divided into groups based on their potential roles in different processes implicated in lupus pathogenesis, including ubiquitination, DNA degradation, innate immunity, cellular immunity, lymphocyte development, and antigen presentation. Recent advances have also shown several genetic associations with SLE subphenotypes and subcriteria. Many areas for further exploration remain to move lupus genetic studies toward clinically informative end points.

Ethnic specificity of lupus-associated loci identified in a genome-wide association study in Korean women

OBJECTIVES

To identify novel genetic candidates for systemic lupus erythematosus (SLE) in the Korean population, and to validate the risk loci for SLE identified in previous genome-wide association studies (GWAS).

METHODS

We performed a GWAS in 400 Korean female SLE patients and 445 controls. Selected single-nucleotide polymorphisms (SNP) were then replicated in an independent cohort of 385 SLE patients and 583 controls (replication cohort 1), and in a further 811 SLE patients and 1502 controls (replication cohort 2).

RESULTS

In the GWAS phase, rs9275428 located near HLA-DQB1 showed the strongest association with SLE (OR 0.50, false discovery rate (FDR) p=3.07×10(-6)). Although no loci reached genome-wide significance outside major histocompatibility complex (MHC), C8orf13-BLK, STAT4, CSMD1, DIAPH3, GLDC and TNFSF4 showed FDR p < 0.05. Our results suggest that STAT4, BLK, IRF5, PTTG1-miR-146a, UBE2L3 and TNFAIP3 are shared susceptibility loci among Caucasians and Asians, while ETS1, IKZF1, SLC15A4 are likely to be Asian-specific loci. In a combined analysis of 1596 SLE patients and 2540 controls for selected 22 candidate SNP, STAT4 and BLK as positive controls showed a strong association with SLE (FDR p=9.85×10(-13) and 2.28×10(-8), respectively). Of these, 16 candidates (PEX5L, TRAJ50, MYO18B, SOS1, ARHGAP26, SMURF1, CADPS, HAND1, FAM78B, DIAPH3, TBL1XR1, CSMD1, ZBTB20, C3orf21, HIPK1 and AP001042.1) showed only nominal significance (7.05×10(-4)≤FDR p≤4.38×10(-2)).

CONCLUSIONS

There are similarities and differences in genetic susceptibility for SLE between Caucasian and Asian ethnic groups. Although 16 putative novel loci for SLE have been suggested in the Korean population, further research on a larger sample is required to discriminate truth from error.

Novel insights into miRNA in lung and heart inflammatory diseases

MicroRNAs (miRNAs) are noncoding regulatory sequences that govern posttranscriptional inhibition of genes through binding mainly at regulatory regions. The regulatory mechanism of miRNAs are influenced by complex crosstalk among single nucleotide polymorphisms (SNPs) within miRNA seed region and epigenetic modifications. Circulating miRNAs exhibit potential characteristics as stable biomarker. Functionally, miRNAs are involved in basic regulatory mechanisms of cells including inflammation. Thus, miRNA dysregulation, resulting in aberrant expression of a gene, is suggested to play an important role in disease susceptibility. This review focuses on the role of miRNA as diagnostic marker in pathogenesis of lung inflammatory diseases and in cardiac remodelling events during inflammation. From recent reports, In this context, the information about the models in which miRNAs expression were investigated including types of biological samples, as well as on the methods for miRNA validation and prediction/definition of their gene targets are emphasized in the review. Besides disease pathogenesis, promising role of miRNAs in early disease diagnosis and prognostication is also discussed. However, some miRNAs are also indicated with protective role. Thus, identifications and usage of such potential miRNAs as well as disruption of disease susceptible miRNAs using antagonists, antagomirs, are imperative and may provide a novel therapeutic approach towards combating the disease progression.

Association of miR-146a polymorphisms with systemic lupus erythematosus: a meta-analysis

Objective

miR-146a may play important roles in the pathogenesis of systemic lupus erythematosus (SLE). Several studies have examined the association of miR-146a gene polymorphisms with SLE, but these studies have shown inconclusive results. To verify whether an association exists, we conducted a meta-analysis of all relevant reports cited in MEDLINE/PubMed and EMBASE before August 2013.

Methods

Meta-analyses were performed on three published studies of the association between the miR-146a rs57095329 SNP and SLE for 5934 patients with SLE and 5591 controls as well as on four published studies of the association between miR-146a rs2910164 SNP and SLE for 2505 patients with SLE and 3248 controls. In addition, two studies involving 1920 SLE patients and 2472 controls were included in a meta-analysis of the association between miR-146a rs2431697 SNP and SLE. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were pooled by the inverse of their variance.

Results

Of three SNPs analyzed, rs57095329 (OR 1.25, 95%CI 1.17–1.35) and rs2431697 (OR 1.24, 95% CI 1.13–1.37) were genetically associated with SLE. However, no significant association was found between rs2910164 and SLE susceptibility (OR 0.98, 95% CI 0.90–1.06). There was no significant heterogeneity across studies and no evidence of publication bias.

Conclusions

The results of our meta-analysis suggest that miR-146a rs57095329 and rs2431697 SNPs are associated with SLE susceptibility. In addition, our results suggest that there is an ethnical difference between Asian and European populations in the association between miR-146a SNPs and SLE susceptibility.

A genetic variant in the microRNA-146a gene is associated with susceptibility to alcohol use disorders

BACKGROUND

Polymorphisms in the microRNA (miRNA) regulatory pathways are novel functional genetic variants whose association with alcoholism susceptibility has not been previously studied. Given the potential relationship between certain miRNAs and alcohol use disorders (AUDs), this study was designed to explore the association between two polymorphisms within hsa-miR-146a and hsa-miR-196a2 genes and susceptibility to these diseases.

METHODS

Three hundred and one male patients with AUDs and 156 sex-matched healthy volunteers were enrolled. Polymorphisms were genotyped using TaqMan(®) PCR assays. Allele and genotype frequencies were compared between groups and logistic regression analysis was also performed to analyze the model of inheritance.

RESULTS

There was a significantly higher prevalence of allele C carriers (47.8%) of the miR-146a G>C polymorphism (rs2910164) among patients with AUDs when compared with controls (35.9%), and multivariable logistic regression analysis showed that the C allele was associated with these AUDs (OR=1.615, 95% CI 1.067-2.442; P=0.023). Neither the genotype nor the allele distribution of miR-196a2 polymorphism (rs11614913) was significantly different between groups.

CONCLUSIONS

This is the first genetic association study to explore the relationship of miRNA polymorphisms with AUDs and to show an association of the miR-146a C>G rs2910164 allelic variant with this disease.

Molecular basis of the irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional disorder characterized by abdominal pain, discomfort and bloating. The pathophysiology of IBS is poorly understood, but the presence of psychosocial basis is now known. There is an increasing number of publications supporting the role of genetics in IBS. Most of the variations are found in genes associated with the brain-gut axis, revealing the strong correlation of brain-gut axis and IBS. miRNAs, which play critical roles in physiological processes, are not well studied in IBS. However, so far there is found an involvement of alterations in miRNA expression or sequence, in IBS symptoms. IBS phenotype is affected by epigenetic alteration and environment. Changes in DNA and histone methylation are observed in patients who suffered childhood trauma or abuse, resulting in altered gene expression, such as the glucocorticoid receptor gene. Finally, diet is another factor associated with IBS, which may contribute to symptom onset. Certain foods may affect on bacterial metabolism and epigenetic modifications, predisposing to IBS.

miR-146a gene polymorphism rs2910164 and the risk of digestive tumors: A meta-analysis of 21 case-control studies

Digestive tumors have the highest incidence among all tumor types worldwide. miR-146a has been shown to play an important role in the development, apoptosis, invasion and metastasis of digestive tumors. Additionally, a miR-146a gene polymorphism has been associated with the risk of a variety of cancer types in the digestive system. Therefore, in order to investigate the correlation, a meta-analysis of reported data was conducted, for which we obtained 21 research studies concerning the association between the miR-146a gene polymorphism and digestive tumors. Odds ratio (OR) values and 95% confidence intervals (95% CI) were used to assess this association. We found that the miR-146a polymorphism rs2910164 might significantly increase the susceptibility of digestive tumors, in particular for esophageal cancer and colorectal cancers. Furthermore, the miR-146a polymorphism might significantly increase the risk of digestive tumors in Asians. However, no obvious correlation between the polymorphism and the risk for digestive tumors was found in Caucasians.