MicroRNA‑155 inhibits the proliferation of CD8+ T cells via upregulating regulatory T cells in vitiligo

The role of regulatory T cells in vitiligo and therapeutic advances: a mini-review

BACKGROUND

Regulatory T cells (Tregs) play vital roles in controlling immune reactions and maintaining immune tolerance in the body. The targeted destruction of epidermal melanocytes by activated CD8+T cells is a key event in the development of vitiligo. However, Tregs may exert immunosuppressive effects on CD8+T cells, which could be beneficial in treating vitiligo.

METHODS

A comprehensive search of PubMed and Web of Science was conducted to gather information on Tregs and vitiligo.

RESULTS

In vitiligo, there is a decrease in Treg numbers and impaired Treg functions, along with potential damage to Treg-related signaling pathways. Increasing Treg numbers and enhancing Treg function could lead to immunosuppressive effects on CD8+T cells. Recent research progress on Tregs in vitiligo has been summarized, highlighting various Treg-related therapies being investigated for clinical use. The current status of Treg-related therapeutic strategies and potential future directions for vitiligo treatment are also discussed.

CONCLUSIONS

A deeper understanding of Tregs will be crucial for advancing Treg-related drug discovery and treatment development in vitiligo.

Expression Signature of Immune-Related MicroRNAs in Autoimmune Skin Disease: Psoriasis and Vitiligo Insights

BACKGROUND

Psoriasis and vitiligo are both chronic, skin-specific diseases classified as autoimmune diseases due to the involvement of several biochemical pathways in their pathogenesis, similar to those altered in other autoimmune diseases. The role of miRNAs in regulating skin autoimmune function has yet to be fully characterized.

AIM

The aim of this study was to assess the expression profile of a panel of 11 circulating immune-related miRNAs in patients with autoimmune skin diseases, specifically psoriasis and vitiligo, and correlate their expression signature with the clinicopathological features of the diseases.

SUBJECTS AND METHODS

Relative gene expression quantification for 11 immune-related circulating miRNAs in plasma was done for 300 subjects-100 patients with psoriasis, 100 patients with vitiligo and 100 normal healthy volunteers-followed by different modalities of bioinformatics analysis for the results.

RESULTS

The expression levels of all the studied immune-related miRNAs were elevated in both autoimmune skin disorders, with much higher levels of expression in psoriasis than in vitiligo patients. There was a significant correlation between most of the studied miRNAs, suggesting shared target genes and/or pathways. Moreover, all the studied miRNAs showed significant results as biomarkers for autoimmune skin disease, with miRNA-145 being the best candidate. Regarding the clinicopathological data, miRNA-7, miRNA-9, miRNA-145, miRNA-148a, and miRNA-148b were positively correlated with age. All the miRNAs were inversely correlated with obesity and disease duration.

CONCLUSION

This study highlights the critical role of miRNAs in skin-specific autoimmune diseases that proved to be potential biomarkers for autoimmune skin disorders, warranting their exploration as therapeutic targets.

Meta-Analysis of Alterations in Regulatory T Cells’ Frequency and Suppressive Capacity in Patients with Vitiligo

Vitiligo is a noncontagious autoimmune skin depigmenting disease. Regulatory T cells (Tregs) play a key role in maintaining peripheral tolerance; however, Tregs' number, suppressive function, and associated suppressive molecules (FOXP3, IL-10, and TGF-β) are found to be reduced in vitiligo patients. Although, the role of Tregs in vitiligo pathogenesis is well established, there are several contrary findings which suggest a controversial role of Tregs in vitiligo. Therefore, to clarify the role of Tregs in vitiligo pathogenesis, we aimed to study Tregs' frequency, suppressive capacity, and associated suppressive molecules (FOXP3, IL-10, and TGF-β) in vitiligo patients through meta-analysis approach. A total of 30 studies involving 1223 vitiligo patients and 1109 controls were included in the study. Pooled results from our meta-analysis suggested significantly reduced Treg cells' frequency in vitiligo patients (p = 0.002). Interestingly, Tregs' suppressive capacity was also significantly reduced in vitiligo patients (p = 0.0002); specifically, Treg-mediated suppression of CD8⁺T cells was impaired in vitiligo patients (p < 0.00001). Moreover, FOXP3, a key Tregs' transcription factor, was significantly reduced in blood and skin of vitiligo patients (p < 0.00001). Intriguingly, the FOXP3 expression was significantly reduced in the lesional skin as compared to perilesional and nonlesional skin (p = 0.007 and p = 0.04). Furthermore, the expression of key Treg-associated suppressive cytokines IL-10 and TGF-β were significantly reduced in vitiligo patients (p = 0.0005 and p = 0.01). The disease activity-based analysis suggested for reduced Tregs' frequency and FOXP3 expression in active vitiligo patients (p = 0.05 and p = 0.01). We also studied the effect of microRNA-based treatment, narrow band–UVB phototherapy, and Treg-associated treatments on Tregs' frequency, FOXP3, and IL-10 expression. Interestingly, we found increased Tregs' frequency, FOXP3, and IL-10 expression after the treatment (p = 0.007, p < 0.0001, and p = 0.002). Overall, our meta-analysis suggests that the Tregs play a crucial role in pathogenesis and progression of vitiligo, and hence, Treg-based therapeutic interventions could be effective in vitiligo patients.

Differential Expression of Serum Exosomal Hsa-miR-487b-3p in Progressive Vitiligo Before and After Systemic Corticosteroid Treatment

Background

Vitiligo is an acquired skin depigmentation disease. It can be misdiagnosed at an early stage and tend to relapse. Serum markers are essential to monitoring the progression of vitiligo. Exosomal miRNAs act as the communication mediator between melanocytes and immune cells. Our study aimed to use serum exosomal miRNAs as a reference for evaluating vitiligo progression.

Methods

The miRNAs were extracted from the serum exosomes of ten progressive vitiligo patients (before and after treatment) and ten healthy individuals. We profiled miRNAs expression by RNA sequencing and screened out potential miRNAs and plotted their receiver operating characteristic (ROC) curves to explore their sensitivity and specificity as prognostic biomarkers in vitiligo progression. We examined the correlation between miRNA expression and the lesion area. Different databases were used to predict gene targets of miRNAs, which were analyzed by gene ontology and Kyoto encyclopedia of genes and genomes (KEGG).

Results

Our results showed that 141 miRNAs were differentially expressed in serum exosomes of progressive vitiligo patients, and 365 miRNAs were differentially expressed in these patients after treatment compared to healthy individuals. The expression of hsa-miR-487b-3p was significantly lower in these patients compared to healthy individuals. Still, there was no difference in its levels in patients after corticosteroid treatment compared to healthy controls. ROC curve analysis (area under curve = 0.840) indicated that hsa-miR-487b-3p could serve as a biomarker for the prognosis of vitiligo progression. Its expression positively correlated with the lesion area. A total of 41 target genes of hsa-miR-487b-3p were predicted via different databases. KEGG pathways were enriched in phenylalanine metabolism, glycan degradation, and protein export.

Conclusion

Serum exosomal hsa-miR-487b-3p can be a biomarker to detect vitiligo progression. The predicted target genes of hsa-miR-487b-3p were enriched in catabolism. Thus, its in progressive vitiligo may accelerate catabolism in melanocytes and cause its impairment.

Emerging Role of Non-Coding RNAs in Regulation of T-Lymphocyte Function

T-lymphocytes (T cells) play a major role in adaptive immunity and current immune checkpoint inhibitor-based cancer treatments. The regulation of their function is complex, and in addition to cytokines, receptors and transcription factors, several non-coding RNAs (ncRNAs) have been shown to affect differentiation and function of T cells. Among these non-coding RNAs, certain small microRNAs (miRNAs) including miR-15a/16-1, miR-125b-5p, miR-99a-5p, miR-128-3p, let-7 family, miR-210, miR-182-5p, miR-181, miR-155 and miR-10a have been well recognized. Meanwhile, IFNG-AS1, lnc-ITSN1-2, lncRNA-CD160, NEAT1, MEG3, GAS5, NKILA, lnc-EGFR and PVT1 are among long non-coding RNAs (lncRNAs) that efficiently influence the function of T cells. Recent studies have underscored the effects of a number of circular RNAs, namely circ_0001806, hsa_circ_0045272, hsa_circ_0012919, hsa_circ_0005519 and circHIPK3 in the modulation of T-cell apoptosis, differentiation and secretion of cytokines. This review summarizes the latest news and regulatory roles of these ncRNAs on the function of T cells, with widespread implications on the pathophysiology of autoimmune disorders and cancer.

MicroRNA‑21‑5p protects melanocytes via targeting STAT3 and modulating Treg/Teff balance to alleviate vitiligo

Vitiligo (VIT) is caused by loss and degradation of functional epidermal melanocytes. Studies have indicated that melanocyte destruction may be associated with an imbalance between regulatory T cells (Treg cells) and effector T cells (Teff cells). The current study aimed to investigate the molecular mechanism through which Treg/Teff balance affects VIT pathogenesis. To explore this, peripheral blood mononuclear cells were isolated from patients with VIT and healthy individuals. The present study revealed that the proportions of CD4+ T cells, Treg cells and T helper 1 (Th1) cells were decreased in patients with VIT, but those of Teff cells (Th17 and Th22 cells) were increased; additionally, Foxp3 expression was decreased, but the expression levels of interferon‑γ, interleukin (IL)‑17A and IL‑22 were increased. Furthermore, in patients with VIT, microRNA (miR)‑21‑5p expression was decreased, while that of STAT3 was increased. Further in vitro experiments in CD4+ T cells revealed that STAT3 was targeted by miR‑21‑5p. Functional analysis further indicated that miR‑21‑5p overexpression in Th17‑polarized CD4+ T cells decreased the proportion of Teff cells and associated cytokines, such as IL‑17A and IL‑22, but increased the proportion of Treg cells and Foxp3. However, the effects of miR‑21‑5p overexpression were partly reversed by STAT3 overexpression. Increased apoptosis of melanocytes was detected after co‑culture with Th17‑polarized CD4+ T cells in the presence of a miR‑21‑5p mimic. However, this indirect effect of the miR‑21‑5p mimic on melanocytes was decreased via STAT3 overexpression. Therefore, miR‑21‑5p may protect melanocytes via targeting STAT3 and regulating Treg/Teff balance. The current findings may provide a possible treatment method for managing VIT.

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.