Melanocyte Precursors in the Hair Follicle Bulge of Repigmented Vitiligo Skin Are Controlled by RHO-GTPase, KCTD10, and CTNNB1 Signaling

Computer-Aided Assessment of Repigmentation Rates in Vitiligo Patients: Implications for Treatment Efficacy - A Retrospective Study

Precise evaluation of repigmentation in vitiligo patients is crucial for monitoring treatment efficacy and enhancing patient satisfaction. This study aimed to develop a computer-aided system for assessing repigmentation rates in vitiligo patients, providing valuable insights for clinical practice. A retrospective study was conducted at the Dermatology Department of Shenzhen People's Hospital between June 2019 and November 2022. Pre- and post-treatment images of vitiligo lesions under Wood's lamp were collected, involving 833 participants stratified by sex, age, and pigmentation patterns. Our results demonstrated that the marginal pigmentation pattern exhibited a higher repigmentation rate of 72% compared with the central non-follicular pattern at 45%. Males had a slightly higher average repigmentation rate of 0.37 in comparison to females at 0.33. Among age groups, individuals aged 0-20 years showed the highest average repigmentation rate at 0.41, while the oldest age group (61-80 years) displayed the lowest rate at 0.25. Analysis of multiple visits identified the marginal pattern as the most prevalent (60%), with a mean repigmentation rate of 40%. This study introduced a computational system for evaluating vitiligo repigmentation rates, enhancing our comprehension of patient responses, and ultimately contributing to enhanced clinical care.

RhoJ: an emerging biomarker and target in cancer research and treatment

RhoJ is a Rho GTPase that belongs to the Cdc42 subfamily and has a molecular weight of approximately 21 kDa. It can activate the p21-activated kinase family either directly or indirectly, influencing the activity of various downstream effectors and playing a role in regulating the cytoskeleton, cell movement, and cell cycle. RhoJ's expression and activity are controlled by multiple upstream factors at different levels, including expression, subcellular localization, and activation. High RhoJ expression is generally associated with a poor prognosis for cancer patients and is mainly due to an increased number of tumor blood vessels and abnormal expression in malignant cells. RhoJ promotes tumor progression through several pathways, particularly in tumor angiogenesis and drug resistance. Clinical data also indicates that high RhoJ expression is closely linked to the pathological features of tumor malignancy. There are various cancer treatment methods that target RhoJ signaling, such as direct binding to inhibit the RhoJ effector pocket, inhibiting RhoJ expression, blocking RhoJ upstream and downstream signals, and indirectly inhibiting RhoJ's effect. RhoJ is an emerging cancer biomarker and a significant target for future cancer clinical research and drug development.

Vitiligo non-responding lesions to narrow band UVB have intriguing cellular and molecular abnormalities that may prevent epidermal repigmentation

We have discovered that human vitiligo patients treated with narrow-band UVB (NBUVB) demonstrated localized resistance to repigmentation in skin sites characterized by distinct cellular and molecular pathways. Using immunostaining studies, discovery-stage RNA-Seq analysis, and confirmatory in situ hybridization, we analyzed paired biopsies collected from vitiligo lesions that did not repigment after 6 months of NBUVB treatment (non-responding) and compared them with repigmented (responding) lesions from the same patient. Non-responding lesions exhibited acanthotic epidermis, had low number of total, proliferative, and differentiated melanocyte (MC) populations, and increased number of senescent keratinocytes (KCs) and of cytotoxic CD8+ T cells as compared with responding lesions. The abnormal response in the non-responding lesions was driven by a dysregulated cAMP pathway and of upstream activator PDE4B, and of WNT/β-catenin repigmentation pathway. Vitiligo-responding lesions expressed high levels of WNT10B ligand, a molecule that may prevent epidermal senescence induced by NBUVB, and that in cultured melanoblasts prevented the pro-melanogenic effect of α-MSH. Understanding the pathways that govern lack of NBUVB-induced vitiligo repigmentation has a great promise in guiding the development of new therapeutic strategies for vitiligo.

The possible role of Wnt/β-catenin signalling in vitiligo treatment

Vitiligo is a common chronic skin disease which has an adverse impact on patients' life. Its pathogenesis is complex, involving autoimmunity and oxidative stress (OS). Autoimmunity leads to the loss of epidermal melanocytes and the formation of the depigmented patches of the disease. Treatment of vitiligo should control the exaggerated immune response to arrest the progress of active disease, and then promote melanocytes to repigmentation. Wnt/β-catenin signalling pathway has been of recent interest in vitiligo. Wnt/β-catenin signalling pathway is downregulated in vitiligo. Upregulation of Wnt/β-catenin signalling possibly control vitiligo autoimmune response by protecting melanocyte from OS damage, inhibiting CD8+ T cell effector cell differentiation and enhancing Treg. Wnt/β-catenin signalling plays a critical role in the melanocyte regeneration by driving the differentiation of melanocyte stem cells (McSCs) into melanocytes. Promoting Wnt/β-catenin signalling can not only arrest the progress of active disease of vitiligo but also promote repigmentation. Some of the main effective therapies for vitiligo are likely to work by activating Wnt/β-catenin signalling. Agents that can enhance the effect of Wnt/β-catenin signalling may become potential candidates for the development of new drugs for vitiligo treatment.

The journey from melanocytes to melanoma

Over the past decade, melanoma has led the field in new cancer treatments, with impressive gains in on-treatment survival but more modest improvements in overall survival. Melanoma presents heterogeneity and transcriptional plasticity that recapitulates distinct melanocyte developmental states and phenotypes, allowing it to adapt to and eventually escape even the most advanced treatments. Despite remarkable advances in our understanding of melanoma biology and genetics, the melanoma cell of origin is still fiercely debated because both melanocyte stem cells and mature melanocytes can be transformed. Animal models and high-throughput single-cell sequencing approaches have opened new opportunities to address this question. Here, we discuss the melanocytic journey from the neural crest, where they emerge as melanoblasts, to the fully mature pigmented melanocytes resident in several tissues. We describe a new understanding of melanocyte biology and the different melanocyte subpopulations and microenvironments they inhabit, and how this provides unique insights into melanoma initiation and progression. We highlight recent findings on melanoma heterogeneity and transcriptional plasticity and their implications for exciting new research areas and treatment opportunities. The lessons from melanocyte biology reveal how cells that are present to protect us from the damaging effects of ultraviolet radiation reach back to their origins to become a potentially deadly cancer.

Occludin Promotes Adhesion of CD8+ T Cells and Melanocytes in Vitiligo via the HIF-1α Signaling Pathway

Loss of melanocytes induced by activated CD8+ T cells is the pathological hallmark of vitiligo. Melanocyte-specific CD8+ T cells are recruited to the skin via chemokines, thereby releasing perforin, granzyme, and other cytotoxic substances that destroy the melanocytes. However, the mechanism of CD8+ T cells to adhere to melanocytes is unknown. Previous transcriptome sequencing results published by our group showed that the occluding (OCLN) gene was significantly upregulated in CD8+ T cells from skin lesions of vitiligo. Occludin is a crucial component of the tight junction between cells; in cells without tight junction, occludin mediates the adhesion of two cells in the form of a self-ligand. This study demonstrated that OCLN gene expression was elevated in the CD8+ T cells of vitiligo patients, and occludin mediates the adherence of CD8+ T cells to melanocytes. Besides, pathological changes in vitiligo skin lesions reveal that CD8+ T cells continuously persist in the skin lesions, which is related to the persistence of the disease. In this regard, we found that fibroblasts from vitiligo patients significantly express occludin, which may participate in the continuous retention of CD8+ T cells in the skin lesions. The pathogenesis of vitiligo is closely related to oxidative stress, and our data suggest that overexpression of hypoxia-inducible factor-1α (HIF-1α) increases the expression of occludin. Besides, ChIP-qPCR of CD8+ T cells revealed that HIF-1α directly binds to the OCLN promoter. Thus, occludin upregulation promotes the adhesion of CD8+ T cells and melanocytes via the HIF-1α signaling pathway. Our study results suggested a critical role for OCLN in the occurrence, progression, and maintenance of vitiligo. Therefore, inhibiting the expression of OCLN gene may be a potential targeted treatment strategy.