Association of a single-nucleotide polymorphism within the miR-146a gene with susceptibility for acute-on-chronic hepatitis B liver failure

Micro-Players of Great Significance-Host microRNA Signature in Viral Infections in Humans and Animals

Over time, more and more is becoming known about micro-players of great significance. This is particularly the case for microRNAs (miRNAs; miR), which have been found to participate in the regulation of many physiological and pathological processes in both humans and animals. One such process is viral infection in humans and animals, in which the host miRNAs—alone or in conjunction with the virus—interact on two levels: viruses may regulate the host’s miRNAs to evade its immune system, while the host miRNAs can play anti- or pro-viral roles. The purpose of this comprehensive review is to present the key miRNAs involved in viral infections in humans and animals. We summarize the data in the available literature, indicating that the signature miRNAs in human viral infections mainly include 12 miRNAs (i.e., miR-155, miR-223, miR-146a, miR-122, miR-125b, miR-132, miR-34a, miR -21, miR-16, miR-181 family, let-7 family, and miR-10a), while 10 miRNAs are commonly found in animals (i.e., miR-155, miR-223, miR-146a, miR-145, miR-21, miR-15a/miR-16 cluster, miR-181 family, let-7 family, and miR-122) in this context. Knowledge of which miRNAs are involved in different viral infections and the biological functions that they play can help in understanding the pathogenesis of viral diseases, facilitating the future development of therapeutic agents for both humans and animals.

The association between SNPs and hepatitis B virus related acute-on-chronic liver failure

OBJECTIVE

This study intended to investigate the association between ten single nucleotide polymorphisms (rs1143623, rs12692386, rs1799983, rs2297518, rs2910164, rs3129859, rs4251961, rs4846085, rs641738, rs873457) with susceptibility and prognosis of hepatitis B related acute-on-chronic liver failure (HBV-ACLF).

METHODS

This is a hospital-based case-control study included 274 patients with HBV-ACLF and 534 patients with chronic hepatitis B. The patients who were successfully followed were divided into the survival group and the death group according to the clinical outcome during the hospitalization and 90 days after discharge. The ten SNPs were genotyped in all subjects by using imLDR. Genotype, allele frequency, dominant model, recessive model and codominant model were constructed to investigate the association between single nucleotide polymorphisms with susceptibility and prognosis of HBV-ACLF.

RESULTS

The genotype distribution of rs1143623 was statistically different between the two groups (P = 0.04), but the allele frequency was not statistically significant (P = 0.44). GC and GG + CG genotypes at rs1143623 reduced the risk of HBV-ACLF. There were only two GG and GT genotypes in rs1799983 in our study, and the genotype and allele frequency were statistically different between the death group and the survival group (P = 0.027, P = 0.023). Patients with T allele may reduce the risk of death in patients with HBV-ACLF. The genotype and allele frequency of rs2297518 showed no significant difference. In dominant models, patients with GA + AA genotypes at rs2297518 had a reduced risk of death.

Plasma miR-146a predicts serological conversion of hepatitis B e-antigen (HBeAg) in chronic hepatitis B patients treated with nucleotide analogs

Background

To investigate the association of plasma miR-146a with serological conversion of hepatitis B e-antigen (HBeAg) in patients with chronic hepatitis B (CHB) treated with nucleotide analogs (NAs).

Methods

This was a retrospective study of 115 HBeAg-positive patients with CHB treated at Xiangya Hospital, Central South University, Changsha, China, between September 2009 and March 2014. Patients were grouped according to whether they had achieved seroconversion of HBeAg by 104 weeks of NAs treatment. We assessed plasma miR-146a using miScript polymerase chain reaction (PCR). Serum alanine transaminase (ALT), hepatitis B virus (HBV) deoxyribonucleic acid (DNA) load, hepatitis B surface antigen (HBsAg) titer, HBeAg titer, and plasma miR-146a were measured at 0, 24, 48, and 104 weeks of treatment. Finally, we also determined ΔmiR-146a_24w and ΔmiR-146a_48w.

Results

ΔmiR-146a_48w was independently associated with seroconversion of HBeAg at 104 weeks [odds ratio (OR) =1.302; 95% confidence interval (CI), 1.159-1.962; P=0.029]. We obtained an area under the receiver operating characteristic (ROC) curve (AUC) of ΔmiR-146_48w of 0.757 for seroconversion of HBeAg (P=0.013). At the optimal cutoff value equivalent to a Youden index of 67.9%, the specificity and sensitivity of ΔmiR-146_48w were 63.7% and 88.3%, respectively. Positive (PPV) and negative (NPV) predictive values were 70.87% and 84.48%, respectively.

Conclusions

ΔmiR-146a_48w was independently associated with seroconversion of HBeAg in CHB patients treated with NAs.

The fibrogenic process and the unleashing of acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is a life-threatening condition characterized by a rapid deterioration of previously well-compensated chronic liver diseases. One of the main obstacles in ACLF is the lack of knowledge of the pathogenesis and specific broad-spectrum treatments. An excessive systemic inflammatory response has been proposed to explain the pathogenesis of ACLF; this hypothesis involves stellate cells, which are implicated in many liver homeostatic functions that include vitamin A storage, regulation of sinusoidal blood flow, local inflammation, maintenance of the hepatocyte phenotype and extracellular matrix remodeling. However, when there is damage to the liver, these cells are the main target of the inflammatory stimulus, as a result, the secretion of the extracellular matrix is altered. Activated hepatic stellate cells raise the survival of neutrophils by the stimulation of granulocytes colonies and macrophages, which exacerbates liver inflammation and promotes damage to hepatocytes. Elevation of pathogen-associated molecular patterns is related to liver damage by different pathophysiological mechanisms of decompensation, showing ballooning degeneration and cell death with a predominance of cholestatic infection. Moreover, patients with ACLF present a marked elevation of C-reactive protein together with an elevation of the leukocyte count. Chronic liver disease is a complex pathological state with a heterogeneous pathophysiology in which genetic factors of the host and external triggers interact and culminate in hepatic insufficiency. The better understanding of such interactions should lead to a better comprehension of the disease and to the discovery of new treatment targets that will make acute decompensations preventable and even decrease mortality.

Association between miRNA-146a rs2910164 (G/C) polymorphism with the susceptibility to chronic HBV infection and spontaneous viral clearance in an Iranian population

Hepatitis B virus (HBV) infection is one of the clinical dilemmas in chronic liver diseases. MicroRNAs (miRNAs) are small noncoding RNA molecules that play an important role in the pathogenesis of liver diseases and single nucleotide polymorphisms (SNPs) in miRNA genes affect the clinical course of HBV infection. Previous studies have shown that miRNA-146a rs2910164 polymorphism can be associated with the pathogenesis of liver diseases such as hepatocellular carcinoma. The present study investigated the association between miRNA-146a rs2910164 polymorphism and susceptibility to HBV infection in an Iranian population. The study comprised 266 patients with chronic HBV infection, 172 patients with spontaneous viral clearance (SVC) after acute HBV infection, and 266 healthy control adjusted for sex and age. The genotyping of the miRNA-146a rs2910164 polymorphism was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Our data revealed that GG genotype and G allele of miRNA-146a rs2910164 SNP is dominated (P < 0.001) in patients with chronic HBV infection (Odds ratio [OR] = 3.92; 95% confidence interval [CI] = 2.1-7.32). miRNA-146a rs2910164 polymorphism showed a statistically significant association (P < 0.001) between CC genotype and allele C with SVC (OR = 2.92; 95% CI = 1.56-546). Our findings suggest miRNA-146a SNP (C/G) in our population may be associated with the susceptibility to HBV infection and CC genotype is associated with SVC. Also, the GG genotype and G allele at miRNA-146a rs2910164 is associated with chronic HBV infection in our population.

MicroRNA-Related Polymorphisms in Infectious Diseases-Tiny Changes With a Huge Impact on Viral Infections and Potential Clinical Applications

MicroRNAs (miRNAs) are single-stranded sequences of non-coding RNA with approximately 22 nucleotides that act posttranscriptionally on gene expression. miRNAs are important gene regulators in physiological contexts, but they also impact the pathogenesis of various diseases. The role of miRNAs in viral infections has been explored by different authors in both population-based as well as in functional studies. However, the effect of miRNA polymorphisms on the susceptibility to viral infections and on the clinical course of these diseases is still an emerging topic. Thus, this review will compile and organize the findings described in studies that evaluated the effects of genetic variations on miRNA genes and on their binding sites, in the context of human viral diseases. In addition to discussing the basic aspects of miRNAs biology, we will cover the studies that investigated miRNA polymorphisms in infections caused by hepatitis B virus, hepatitis C virus, human immunodeficiency virus, Epstein–Barr virus, and human papillomavirus. Finally, emerging topics concerning the importance of miRNA genetic variants will be presented, focusing on the context of viral infectious diseases.

Hepatitis B virus inhibits intrinsic RIG-I and RIG-G immune signaling via inducing miR146a

Previous studies showed that hepatitis B virus (HBV), as a latency invader, attenuated host anti-viral immune responses. miRNAs were shown to be involved in HBV infection and HBV-related diseases, however, the precise role of miRNAs in HBV-mediated immunosuppression remains unclear. Here, we observed that down-regulated RIG-I like receptors might be one critical mechanism of HBV-induced suppression of type I IFN transcription in both HBV(+) hepatoma cell lines and liver cancer tissues. Then, miR146a was demonstrated to negatively regulate the expression of RIG-I-like receptors by directly targeting both RIG-I and RIG-G. Further investigation showed that antagonizing miR146a by anti-sense inhibitors or sponge approach accelerated HBV clearance and reduced HBV load both in vitro and in a HBV-carrying mouse model. Therefore, our findings indicated that HBV-induced miR146a attenuates cell-intrinsic anti-viral innate immunity through targeting RIG-I and RIG-G, and silencing miR146a might be an effective target to reverse HBV-induced immune suppression.

Upregulation of microRNA-146a by hepatitis B virus X protein contributes to hepatitis development by downregulating complement factor H

Hepatic injuries in hepatitis B virus (HBV) patients are caused by immune responses of the host. In our previous study, microRNA-146a (miR-146a), an innate immunity-related miRNA, and complement factor H (CFH), an important negative regulator of the alternative pathway of complement activation, were differentially expressed in HBV-expressing and HBV-free hepatocytes. Here, the roles of these factors in HBV-related liver inflammation were analyzed in detail. The expression levels of miR-146a and CFH in HBV-expressing hepatocytes were assessed via analyses of hepatocyte cell lines, transgenic mice, adenovirus-infected mice, and HBV-positive human liver samples. The expression level of miR-146a was upregulated in HBV-expressing Huh-7 hepatocytes, HBV-expressing mice, and patients with HBV infection. Further results demonstrated that the HBV X protein (HBx) was responsible for its effects on miR-146a expression through NF-κB-mediated enhancement of miR-146a promoter activity. HBV/HBx also downregulated the expression of CFH mRNA in hepatocyte cell lines and the livers of humans and transgenic mice. Furthermore, overexpression and inhibition of miR-146a in Huh-7 cells downregulated and upregulated CFH mRNA levels, respectively. Luciferase reporter assays demonstrated that miR-146a downregulated CFH mRNA expression in hepatocytes via 3′-untranslated-region (UTR) pairing. The overall effect of this process in vivo is to promote liver inflammation. These results demonstrate that the HBx–miR-146a–CFH–complement activation regulation pathway might play an important role in the immunopathogenesis of chronic HBV infection. These findings have important implications for understanding the immunopathogenesis of chronic hepatitis B and developing effective therapeutic interventions.

Hepatitis B virus (HBV) remains an important pathogen and can cause severe liver diseases, including hepatitis, liver cirrhosis, and hepatocellular carcinoma. Although HBV was found in 1966, the molecular mechanisms of pathogenesis are still poorly understood. In the present study, we found that the HBV X protein (HBx) promoted the expression of miR-146a, an innate immunity-related miRNA, through the NF-κB signal pathway and that increasingly expressed miR-146a downregulated its target complement factor H (CFH), an important negative regulator of the complement alternative pathway, leading to the promotion of liver inflammation. We demonstrated that the HBx–miR-146a–CFH–complement activation regulation pathway is potentially an important mechanism of immunopathogenesis caused by chronic HBV infection. Our data provide a novel molecular mechanism of HBV pathogenesis and thus help to understand the correlations between the complement system, an important part of innate immunity, and HBV-associated disease. These findings will also be important to identify potential therapeutic targets for HBV infection.

Association of miR-146a rs2910164 with childhood IgA nephropathy

BACKGROUND

Micro-RNAs (miRNAs) play important roles in the regulation of immune response and inflammation. The purpose of this study was to investigate the association between three single nucleotide polymorphisms (SNPs) (mir-146a rs2910164, let-7a-2 rs1143770, miR-196a2 rs11614913) and susceptibility to and severity of childhood immunoglobulin A (IgA) nephropathy (IgAN).

METHODS

We genotyped three miRNA SNPs in two independent Han Chinese populations composed of 158 patients and 265 controls (discovery set), and 246 patients and 446 controls (validation set), respectively.

RESULTS

We found that rs2910164 was significantly associated with IgAN in the discovery but not the validation set. Combined analysis revealed that rs2910164 CC and CG genotypes were associated with increased risk of IgAN compared with the GG genotype [adjusted odds ratios (OR) = 1.684, 95 % confidence interval (CI)1.190-2.384, P = 0.003; adjusted OR = 1.472, 95 % CI 1.079-2.007, P = 0.015, respectively). We also found that the frequency of the rs2910164 CC genotype was significantly higher in patients with Haas grade III-V than in those with Haas grade I-II for all study populations (P < 0.05). The expression of miR-146a in normal renal tissues with CC genotype was lower than in those with a G allele (P = 0.038).

CONCLUSIONS

These results indicated that rs2910164 may affect the susceptibility and severity of pediatric IgAN. Further studies are needed to validate these findings.

Association of miR-146a gene polymorphism with risk of nasopharyngeal carcinoma in the central-southern Chinese population

This case-control study focused on estimating the association between miR-146a polymorphism and risk of nasopharyngeal carcinoma (NPC) in central-south China. In total, 160 patients with NPC and 200 healthy controls in central-south China were genotyped using polymerase chain reaction-restriction fragment length polymorphism assay. Chi-square test was used to assess the different distribution of miR-146a polymorphism between NPC patients and controls; and logistic regression analysis was applied to analyze the associations between miR-146a polymorphism with cancer risk in different contrast models. Significant differences between NPC patients and controls were found in genotype (P=0.033 for GG versus CG versus CC; and odds ratio (OR)=0.568, 95% confidence interval (CI)=0.354-0.912, P=0.019 for CG versus CC; and OR=0.503, 95% CI=0.261-0.971, P=0.041 for CG versus CC; and OR=0.564, 95% CI=0.360-0.884, P=0.012 for GG+CG versus CC, respectively) and allelic analysis (P=0.025 for G versus C). Our findings suggested that polymorphism of mir-146a was associated with NPC in the central-southern Chinese population.