A single-nucleotide polymorphism of miR-196a-2 and vitiligo: an association study and functional analysis in a Han Chinese population

Association between miR-202, miR-211, and miR-1238 gene polymorphisms and risk of vitiligo

Vitiligo, as a common pigment defect in the skin, hair, and mucous membranes, results from the destruction of melanocytes. Recent investigations have shown that miRNA dysregulation contributes in the pathogenesis of vitiligo. Therefore, in this research, our aim is to explore the relationship between miR-202 rs12355840, miR-211 rs8039189, and miR-1238 rs12973308 polymorphisms and susceptibility to vitiligo. A total number of 136 vitiligo patients and 129 healthy individuals as a control group were included in this research. The salting out approach was implemented to extraction genomic DNA. The genetic polymorphisms of miR-202 rs12355840, miR-211 rs8039189, and miR-1238 rs12973308 were determined using PCR-RFLP approach. The findings revealed that miR-202 rs12355840 polymorphism under codominant (CT and TT genotypes), dominant, recessive, overdominant, and also allelic models is correlated with increased risk of vitiligo. In addition, codominant, dominant, overdominant, as well as allelic models of miR-211 rs8039189 polymorphism decrease risk of vitiligo. No significant relationship was observed between the miR-1238 rs12973308 polymorphism and susceptibility to vitiligo. The miR-211 rs8039189 polymorphism may serve a protective effect on vitiligo development and miR-202 rs12355840 polymorphism may act as a risk factor for vitiligo susceptibility.

The Essential Role of microRNAs in Inflammatory and Autoimmune Skin Diseases-A Review

The etiopathogenesis of autoimmune skin diseases is complex and still not fully understood. The role of epigenetic factors is emphasized in the development of such diseases. MicroRNAs (miRNAs), a group of non-coding RNAs (ncRNAs-non-coding RNAs), are one of the important post-transcriptional epigenetic factors. miRNAs have a significant role in the regulation of the immune response by participating in the process of the differentiation and activation of B and T lymphocytes, macrophages, and dendritic cells. Recent advances in research on epigenetic factors have provided new insights into the pathogenesis and potential diagnostic and therapeutic targets of many pathologies. Numerous studies revealed a change in the expression of some microRNAs in inflammatory skin disorders, and the regulation of miRNA expression is a promising therapeutic goal. This review presents the state of the art regarding changes in the expression and role of miRNAs in inflammatory and autoimmune skin diseases, including psoriasis, atopic dermatitis, vitiligo, lichen planus, hidradenitis suppurativa, and autoimmune blistering diseases.

MicroRNAs: Emerging players in the pathogenesis of vitiligo

Vitiligo is an autoimmune skin disease characterized by presence of pale patchy areas of depigmentation. MicroRNAs (miRNAs) are important regulators of gene expression and play significant roles in diverse biological and pathological processes. Accumulating evidence has shown that miRNAs were differentially expressed in skin lesions and peripheral blood mononuclear cells of patients with vitiligo. In particular, miRNAs are significantly correlated with the development and progression of vitiligo. The abundance of some miRNAs in serum was also correlated with the vitiligo lesion severity, indicating that miRNAs might serve as prognostic biomarkers. Importantly, the direct involvement of miRNAs in the pathogenesis of vitiligo has been demonstrated. For example, increased expression of miR-25 contributes to vitiligo through promoting the dysfunction and oxidative stress-induced destruction of melanocytes. However, there are limited studies on the function and mechanism of deregulated miRNAs in vitiligo. Further studies are required to establish clinical applications of miRNAs for vitiligo. More in-depth investigations of miRNAs are needed for the understanding of the pathogenesis of vitiligo and the development of novel therapeutic targets. This present review summarizes the current literature on the deregulation and pathogenic roles of miRNAs in vitiligo. We also highlight the potential clinical applications of miRNAs in patients with vitiligo.

Human TYRP1: Two functions for a single gene?

In the animal kingdom, skin pigmentation is highly variable between species, and it contributes to phenotypes. In humans, skin pigmentation plays a part in sun protection. Skin pigmentation depends on the ratio of the two pigments pheomelanin and eumelanin, both synthesized by a specialized cell population, the melanocytes. In this review, we explore one important factor in pigmentation: the tyrosinase-related protein 1 (TYRP1) gene which is involved in eumelanin synthesis via the TYRP1 protein. Counterintuitively, high TYRP1 mRNA expression is associated with a poor clinical outcome for patients with metastatic melanomas. Recently, we were able to explain this unexpected TYRP1 function by demonstrating that TYRP1 mRNA sequesters microRNA-16, a tumor suppressor miRNA. Here, we focus on actors influencing TYRP1 mRNA abundance, particularly transcription factors, single nucleotide polymorphisms (SNPs), and miRNAs, as they all dictate the indirect oncogenic activity of TYRP1.

The Role of MicroRNAs in Vitiligo: Regulators and Therapeutic Targets

Vitiligo is an acquired skin disorder clinically characterized by the progressive appearance of white maculae due to a loss of functioning epidermal melanocytes. Studies have shown that microRNAs (miRNAs) modulate cellular differentiation, proliferation and apoptosis, including immune cell and melanocyte development and functions. The role of miRNAs in the pathogenesis of several immune-related diseases has been explored. Novel approaches to target miRNAs have recently emerged allowing modulation of miRNAs levels in diverse pathological processes, thus making them promising targets for molecular-based diagnostics and therapy. Here, we report the present status of research on miRNAs expression and functional alterations in vitiligo, in order to more fully understand the role of these molecules in vitiligo pathology.

Serum levels of miRNA-21-5p in vitiligo patients and effects of miRNA-21-5p on SOX5, beta-catenin, CDK2 and MITF protein expression in normal human melanocytes

BACKGROUND

Epigenetics of vitiligo was evaluated in few studies. In particular, the role of miR-21, a microRNA involved in various processes, including melanogenesis, was never investigated.

OBJECTIVE

Evaluation of serum levels of miR-21-5p in vitiligo patients and miR-21-5p effects on melanogenesis.

METHODS

We measured serum levels of miR-21-5p in 40 patients affected by nonsegmental vitiligo and 40 sex- and age-matched healthy controls. Next, normal human melanocytes were transfected with miR-21-5p to study the effects of this microRNA, which targeted some proteins involved in melanogenesis pathway like SOX5, beta-catenin, cyclin-dependent kinase 2 (CDK2), and MITF.

RESULTS

The expression of miR-21-5p in vitiligo patients was 3.6-4454.4 fold (mean 990.4 ± 1397.9) higher than in controls. The relative expression of miR-21-5p was directly and significantly correlated with disease severity, defined by VASI (Vitiligo Area and Severity Index) score (Rho = 0.89, p = 10^-7), but not other individual or clinical characteristics. In the second part of the study, a significant reduction of SOX5, beta-catenin and CDK2 protein expression and increase of MITF protein expression was observed in cultured melanocytes after 24 h trasfection with miR-21-5p.

CONCLUSION

According to literature, miR-21-5p upregulation and consequent SOX5 downregulation should upregulate melanogenesis, while vitiligo is characterized by skin depigmentation. Our results suggest that current knowledge of the pathogenesis of vitiligo is probably incomplete. Clinical manifestations could result from an altered balance between metabolic pathways with contrasting effects. In this view, miR-21-5p upregulation might be a tentative compensation mechanism. Further studies appear necessary to confirm and better understand our results and their importance.

Factors affecting vitiligo response to treatment: do MiRNA 196a2C/T gene polymorphism and serum tyrosinase levels have any role?

BACKGROUND

Factors contributing to the pathogenesis of vitiligo and factors affecting its response to treatment are still a major area of debate.

AIM OF THE WORK

The study aimed to assess the serum levels of tyrosinase and Micro-RNAs (miRNAs) gene polymorphism in a sample of Egyptian vitiligo patients, and to determine factors affecting the response of vitiligo to treatment.

SUBJECTS AND METHODS

This prospective case-control interventional study included 212 non-segmental vitiligo patients and 96 control subjects. Before treatment, vitiligo was evaluated using Vitiligo Area Severity Index. Detection of miRNA 196a-2 polymorphism was done using PCR-REELP and serum tyrosinase was measured using ELISA. After treatment, patients were reevaluated clinically and serum tyrosinase levels were re-measured.

RESULTS

The tyrosinase levels were significantly elevated in patients. The TT genotype was the most prevalent one in the patients. The percentage of improvement showed a significant positive correlation with patients' ages and age of the disease onset and a negative correlation with disease duration, baseline VASI scores and serum tyrosinase levels.

CONCLUSION

MiRNA 196a-2 C/T (11614913) gene polymorphism and the elevated serum tyrosinase levels might be related to the pathogenesis of vitiligo and may affect its therapeutic response.

Current insight into the roles of microRNA in vitiligo

Vitiligo is a common chronic depigmented skin disease characterized by melanocyte loss or dysfunction in the lesion. The pathogenesis of vitiligo has not been fully clarified. Most studies have suggested that the occurrence and progression of vitiligo are due to multiple factors and gene interactions in which noncoding RNAs contribute to an individual's susceptibility to vitiligo. Noncoding RNAs, including microRNAs (miRNAs), are a hot topic in posttranscriptional regulatory mechanism research. miRNAs are noncoding RNAs with a length of approximately 22 nucleotides and play a negative regulatory role by binding to the 3'-UTR or 5'-UTR of the target mRNA to inhibit translation or initiate mRNA degradation. Previous studies have screened the differential expression profiles of miRNAs in the skin lesions, melanocytes, peripheral blood mononuclear cells (PBMCs) and sera of patients and mouse models with vitiligo. Moreover, several studies have focused on miRNA-25, miRNA-155 and other miRNAs involved in melanin metabolism, oxidative stress, and melanocyte proliferation and apoptosis. These miRNAs and regulatory processes further illuminate the pathogenesis of vitiligo and provide hope for the application of small molecules in the treatment of vitiligo. In this review, we summarize miRNA expression profiles in different tissues of vitiligo patients and the mechanisms by which key miRNAs mediate vitiligo development.

Co-exposure to polycyclic aromatic hydrocarbons and metals, four common polymorphisms in microRNA genes, and their gene-environment interactions: Influences on oxidative damage levels in Chinese coke oven workers

BACKGROUND

Human are often simultaneously exposed to polycyclic aromatic hydrocarbons (PAHs) and metals, yet relatively little is known regarding their co-exposure effects on oxidative damage. Genetic factors and the gene-environment interactions can also determine the severity of oxidative damage. Four polymorphisms in microRNA (miRNA) genes (rs11614913, rs2292832, rs2910164, and rs3746444) have been well-studied to be associated with oxidative damage-related diseases.

OBJECTIVE

To investigate the influences of PAH-metal co-exposure, four polymorphisms, and their interactions on oxidative damage levels.

METHODS

We conducted a cross-sectional study in 1385 coke oven workers. We quantified exposure levels of PAHs and metals by urinary monohydroxy-PAHs, plasma benzo[a]pyrene-7,8-diol-9,10-epoxide-albumin adducts, and urinary metals, respectively, and measured oxidative damage levels by 8-iso-prostaglandin-F2α and 8-hydroxydeoxyguanosine. We also genotyped four polymorphisms.

RESULTS

In multiple-pollutant models, 8-iso-prostaglandin-F2α and 8-hydroxydeoxyguanosine were associated with multiple PAH exposure biomarkers, as well as with multiple metals (p_trend < 0.05). Metabolites of phenanthrene and pyrene interacted synergistically with lead and zinc to influence 8-iso-prostaglandin-F2α (β_interaction > 7.75%, false discovery rate-adjusted p_interaction ≤ 2.25 × 10^-5). Significantly higher 8-hydroxydeoxyguanosine was observed in carriers of rs11614913 CC variant homozygote than TC carriers (p = 0.037). Associations of the number of rs11614913 C allele with increased 8-iso-prostaglandin-F2α and 8-hydroxydeoxyguanosine were significant (β_std > 0, p_trend < 0.05) and more pronounced in workers with lower metals [p for modifying effect (p_ME) < 0.040]. Positive associations of some PAHs and metals with 8-iso-prostaglandin-F2α and 8-hydroxydeoxyguanosine were weaker in carriers of rs11614913 CC genotype or C allele (p_ME < 0.05).

CONCLUSION

PAH-metal co-exposure, rs11614913, and their interactions may affect oxidative damage levels in Chinese population in a complex manner that are worthy of further investigation.

Identification of the Risk HLA-A Alleles and Autoantigen in Han Chinese Vitiligo Patients and the Association of CD8+T Cell Reactivity with Disease Characteristics

BACKGROUND Multiple studies have implicated a role for CD8+T cell-mediated immune response to autoantigens in vitiligo. However, the antigen-specific T lymphocyte reactivity against the peptide epitopes is diverse among different world populations. This study aimed to identify the risk HLA-A allele in vitiligo and study CD8+ T cell reactivity to 5 autoantigenic peptides in Han Chinese populations, and to analyze the association of CD8+ T cell reactivity with disease characteristics. MATERIAL AND METHODS The risk HLA-A allele was analyzed by case-control study. Enzyme linked immunospot (ELISPOT) assay was used to compare T cell reactivity to the 5 autoantigenic peptides between vitiligo patients and healthy controls, then we analyzed the association of CD8+ T cell reactivity to 2 positive peptides with disease activity and area of skin lesions. RESULTS The results indicated that the most frequent allele in the Han Chinese vitiligo patients was the HLA-A*02: 01 allele with a significantly higher frequency compared to controls (20.20% versus 13.79%, P=6.64×10-5). The most frequently encountered epitopes were 2 gp100 modified peptides, IMDQVPFSV and YLEPGPVTV, whereas a weak T cell reactivity against tyrosinase and Melan-A/MART-1 were evaluated. Moreover, we demonstrated that T cell reactivity against the 2 positive peptides was significantly associated with disease characteristics including disease activity and area of skin lesions. CONCLUSIONS Our findings showed that the HLA-A*02: 01 allele was the major risk HLA-A allele, and 2 gp100 modified peptides were identified as autoantigens and were found to be closely related to disease characteristics which might play a critical role in Han Chinese vitiligo patients.

microRNAs in Cancer Susceptibility

microRNAs (miRNAs) are a small RNA species without protein-coding potential. However, they are key modulators of protein translation. Many studies have linked miRNAs with cancer initiation, progression, diagnosis, and prognosis, and recent studies have also linked them with cancer etiology and susceptibility, especially through single-nucleotide polymorphisms (SNPs). This review discusses some of the recent advances in miRNA-SNP literature-including SNPs in miRNA genes, miRNA target sites, and the processing machinery. In addition, we highlight some emerging areas of interest, including isomiRs and non-3'UTR focused miRNA-binding mechanisms that could provide further novel insight into the relationship between miR-SNPs and cancer. Finally, we note that additional epidemiological and experimental research is needed to close the gap in our understanding of the genotype-phenotype relationship between miRNA-SNPs and cancer.

Vitiligo blood transcriptomics provides new insights into disease mechanisms and identifies potential novel therapeutic targets

BACKGROUND

Significant gaps remain regarding the pathomechanisms underlying the autoimmune response in vitiligo (VL), where the loss of self-tolerance leads to the targeted killing of melanocytes. Specifically, there is incomplete information regarding alterations in the systemic environment that are relevant to the disease state.

METHODS

We undertook a genome-wide profiling approach to examine gene expression in the peripheral blood of VL patients and healthy controls in the context of our previously published VL-skin gene expression profile. We used several in silico bioinformatics-based analyses to provide new insights into disease mechanisms and suggest novel targets for future therapy.

RESULTS

Unsupervised clustering methods of the VL-blood dataset demonstrate a "disease-state"-specific set of co-expressed genes. Ontology enrichment analysis of 99 differentially expressed genes (DEGs) uncovers a down-regulated immune/inflammatory response, B-Cell antigen receptor (BCR) pathways, apoptosis and catabolic processes in VL-blood. There is evidence for both type I and II interferon (IFN) playing a role in VL pathogenesis. We used interactome analysis to identify several key blood associated transcriptional factors (TFs) from within (STAT1, STAT6 and NF-kB), as well as "hidden" (CREB1, MYC, IRF4, IRF1, and TP53) from the dataset that potentially affect disease pathogenesis. The TFs overlap with our reported lesional-skin transcriptional circuitry, underscoring their potential importance to the disease. We also identify a shared VL-blood and -skin transcriptional "hot spot" that maps to chromosome 6, and includes three VL-blood dysregulated genes (PSMB8, PSMB9 and TAP1) described as potential VL-associated genetic susceptibility loci. Finally, we provide bioinformatics-based support for prioritizing dysregulated genes in VL-blood or skin as potential therapeutic targets.

CONCLUSIONS

We examined the VL-blood transcriptome in context with our (previously published) VL-skin transcriptional profile to address a major gap in knowledge regarding the systemic changes underlying skin-specific manifestation of vitiligo. Several transcriptional "hot spots" observed in both environments offer prioritized targets for identifying disease risk genes. Finally, within the transcriptional framework of VL, we identify five novel molecules (STAT1, PRKCD, PTPN6, MYC and FGFR2) that lend themselves to being targeted by drugs for future potential VL-therapy.

A passenger strand variant in miR-196a2 contributes to asthma severity in children and adolescents: A preliminary study

There is emerging evidence to support the role of microRNAs in allergic airway diseases and inflammation. Genetic variants in microRNA genes might affect microRNA-mediated cell regulation. This preliminary study was designed to investigate the association of the microRNA-196a2 rs11614913 (C/T) polymorphism with susceptibility to asthma and clinical outcomes in children and adolescents. Genotyping of rs11614913 polymorphism was determined in 96 patients with bronchial asthma (6-18 years of age) and 96 unrelated controls, using real-time polymerase chain reaction technology. In-silico target prediction and network core analyses were performed. The asthmatics did not show significant differences in genotype distribution (p = 0.609) and allele frequencies (p = 0.428) compared with the controls. There were also no associations with disease duration, age at onset, asthma phenotype, asthma control, therapeutic level, airway hyper-responsiveness, or biochemical parameters in the blood. However, the CC genotype was associated with a more severe degree of asthma (p = 0. 023) and higher frequency of nocturnal asthma (p = 0.002). Carriers for CC were 17 times more likely to develop nocturnal asthma, and had a more than 2.5-fold increased risk for poor disease outcome compared with CT and TT individuals. In conclusion, microRNA-196a2 rs11614913 polymorphism might be associated with asthma severity in our sample of the Egyptian population. Further investigations in studies with a larger sample size and functional tests are needed to validate our findings and to explore the detailed biological mechanisms.

miR-196a-2 rs11614913 polymorphism is associated with vitiligo by affecting heterodimeric molecular complexes of Tyr and Tyrp1

Tyrosinase and tyrosinase-related protein 1 (Tyr-Tyrp1) complex plays a critical role in the synthesis of melanin intermediates, which involves the production of reactive oxygen species (ROS) and contributes to the development of vitiligo. Based on our previous observation that rs11614913 single nucleotide polymorphism (SNP) in miR-196a-2 could affect the risk of vitiligo by influencing Tyrp1, we hypothesized that the same SNP could also regulate the level of Tyr in vitiligo. The aim of this study was to evaluate the potential association between rs11614913 SNP in miR-196a-2 and serum Tyr level in vitiligo and the regulatory role of miR-196a-2 in the expression of Tyr in melanocytes. The serum Tyr level was detected in 116 patients with vitiligo and 116 controls by ELISA plate assay. The expression level of Tyrp1 and Tyr in PIG1(normal melanocyte cell lines) cells was analyzed by western blotting. The ROS level and apoptosis rate in PIG1 cells transfected with si-Tyr or control siRNA were tested by flow cytometry. The results show that the individuals with TT+TC genotypes in miR-196a-2 and higher Tyr level in serum had an increased risk of vitiligo compared with those who had the CC genotype and lower Tyr level (P < 0.001). Furthermore, the rs11614913 C allele in miR-196a-2 enhanced its inhibitory regulation on the expression of Tyr, the down-regulation of which in melanocytes successfully reduced the intracellular ROS levels and the apoptosis rate. In conclusion, our findings suggest that miR-196a-2 polymorphisms can regulate the Tyr levels, which influences the susceptibility of vitiligo.

A single-nucleotide polymorphism of miR-146a and psoriasis: an association and functional study

Epidermal growth factor receptor (EGFR), which is overexpressed in psoriatic lesions, has been proven to contribute to the hyperproliferation of keratinocytes in psoriasis. Single nucleotide polymorphisms (SNPs) involved in miRNAs that can regulate the expression of EGFR could potentially influence the development of psoriasis. The present study investigated the association between a functional SNP of rs2910164 in miR-146a and the risk of psoriasis in the Chinese Han population. A total of 521 Han Chinese patients with psoriasis and 582 healthy controls were recruited in this study. The miR-146a rs2910164 SNP was genotyped by polymerase chain reaction-restriction fragment length polymorphism. Overall, a significantly increased risk of psoriasis was associated with the rs2910164 miR-146a CG and GG genotypes (adjusted OR, 1.38; 95% CI, 1.06–1.80). Furthermore, the rs2910164G allele in miR-146a attenuated its inhibitory regulation on the expression of EGFR as well as the proliferation of human keratinocytes, and lowered the level of miR-146a in the psoriatic lesions. These findings indicate that the rs2910164G allele in miR-146a weakens its suppression on the proliferation of keratinocytes probably through the decreased inhibition of the target gene, EGFR, which may account for the increased risk of psoriasis in this study population.