Immunophenotype of circulatory T-helper cells in patients with non-segmental vitiligo

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.

Expression patterns of long non-coding RNAs in peripheral blood mononuclear cells of non-segmental vitiligo

OBJECTIVE

We explored the patterns of long non-coding RNA (lncRNA) expression in peripheral blood mononuclear cells (PBMCs) from patients with non-segmental vitiligo.

METHODS

We used high-throughput RNA sequencing technology to generate sequence data from five patients with non-segmental vitiligo alongside five normal healthy individuals, and then performed bioinformatics analyses to detect the differential expression of lncRNA in PBMCs. Gene Ontology (GO) and pathway analyses were performed for functional annotation, and quantitative real-time polymerase chain reaction (qRT-PCR) was used to verify gene expression. Target miRNAs and mRNAs of differentially expressed lncRNAs were predicted using bioinformatics analysis.

RESULTS

A total of 292 lncRNAs were differentially expressed in non-segmental vitiligo (fold change ≥ 2.0, P < .05), of which 171 were upregulated and 121 were downregulated. Six differentially expressed lncRNAs were selected, namely ENST00000460164.1, ENST00000393264.2, NR-046211.1, NR-135491.1, NR-135320.1, and ENST00000381108.3, for validation by qRT-PCR. The results showed that ENST00000460164.1 and NR-046211.1 were highly expressed in PBMCs of non-segmental vitiligo. An lncRNA-miRNA-mRNA network containing two lncRNAs, 17 miRNAs, and 223 mRNAs was constructed.

CONCLUSION

Our results revealed patterns of differentially expressed lncRNAs in the PBMCs of non-segmental vitiligo individuals. ENST00000460164.1, and NR-046211.1 may be potential biomarkers and drug targets for the treatment of non-segmental vitiligo.

Altered circulating memory T cells in vitiligo cases followed NB-UVB therapy

Background

Vitiligo represents a commonly diagnosed autoimmune disease caused by the depletion of epidermal melanocytes. Many subsets of T cells contribute to vitiligo pathogenesis, including resident and circulating memory T cells.

Objectives

To analyze the amounts of CD4⁺ and CD8⁺memory T‐cell subsets in peripheral blood specimens from vitiligo patients and alterations caused by narrowband ultraviolet B (NB‐UVB) phototherapy.

Methods

Circulating CD4⁺ and CD8⁺ central memory T (T_CM) and effector memory T (T_EM) cell frequencies in 33 patients with non‐segmental vitiligo and 16 healthy donors were evaluated by flow cytometry. Related chemokine levels were also detected.

Results

Peripheral blood CD4⁺ T_CM and CD8⁺ T_CM counts were markedly reduced in vitiligo cases while they were higher in active vitiligo compared with stable vitiligo cases. Circulating CD8⁺ T_CM frequency in vitiligo was closely related to disease duration. Interestingly, CD4⁺ T_CM and CD8⁺ T_CM frequencies, alongside CXCL9 and CXCL10 amounts in peripheral blood of patients with vitiligo, were significantly decreased after NB‐UVB phototherapy.

Conclusions

Decreased frequencies of circulating CD4⁺ T_CM and CD8⁺ T_CM by NB‐UVB suggest a possible immunosuppressive effect of phototherapy. The chemokines CXCL9 and CXCL10 are the bridge between circulating and skin resident memory T cells. NB‐UVB blocks the homing of circulating memory T cells into vitiligo lesions by down‐regulating CXCL9 and CXCL10. Targeting the above proteins could provide novel, durable treatment options to cure and prevent flares of this disease.

Decreased levels of interleukin 27 in the serum of vitiligo patients

BACKGROUND

Vitiligo is a common skin disorder in which melanocytes are destroyed by auto-reactive immune responses. The loss of melanocytes results in the appearance of depigmented areas in different parts of the body. Cytokines have remarkable roles in the pathogenesis of vitiligo, such as IL-1, IL-6, and TNF-α; interleukin 27 (IL-27) is a new member of the IL-6/IL-12 family, mainly released by activated antigen-presenting cells. IL-27 has been suggested to function as a pro-inflammatory as well as an anti-inflammatory cytokine. Altered concentrations of IL-27 have been shown in various auto-immune diseases such as multiple sclerosis, rheumatoid arthritis, and psoriasis. No studies have been conducted to determine the expression of this cytokine in vitiligo patients.

OBJECTIVE

The objective of this study was to determine the serum concentration of IL-27 in vitiligo patients and compare it with normal individuals.

METHODS

The serum concentration of IL-27 in 79 vitiligo patients was evaluated in comparison to 45 healthy controls using ELISA assay.

RESULTS

Results showed decreased concentration of IL-27 in vitiligo patients as compared with healthy subjects (p=0.026). Furthermore, no correlation between IL-27 concentrations and disease parameters such as vitiligo severity and the extension of the depigmented area was observed.

STUDY LIMITATION

A larger sample size would be more recommended for this study.

CONCLUSION

The reduction in the serum levels of IL-27 in vitiligo patients compared to normal subjects suggested the possible anti-inflammatory role of this cytokine in vitiligo. Thus, IL-27 may be considered as a new target for the manipulation of the immune system in vitiligo patients.