Markers of Metabolic Abnormalities in Vitiligo Patients

Comprehensive Overview of Cytokine Interplay in Vitiligo: A Decade of Meta-Analyses Systematically Reviewed

(1) Background: Vitiligo is an autoimmune skin disorder characterized by melanocyte destruction. Despite metabolic disturbances and oxidative stress also playing a key role in its pathogenesis, accumulating evidence highlights a prominent role for cytokine dysregulation. (2) Methods: A systematic search was conducted to identify meta-analyses published in the last decade that investigated cytokine involvement in vitiligo. (3) Results: Based on predefined inclusion criteria, nine meta-analyses were retrieved and reviewed. The findings confirm a central role for interferon-gamma (IFN-γ) in vitiligo pathogenesis, although recent meta-analyses suggest that IFN-γ gene polymorphisms are more broadly associated with autoimmunity rather than being vitiligo-specific. Elevated interleukin-17 (IL-17) levels have been consistently reported in vitiligo patients, supporting its contribution to immune-mediated melanocyte destruction. Regulatory T cell dysfunction appears to play a crucial role in disease progression. Additionally, TNF-α-308 G/A polymorphism has been linked to a genetic susceptibility to vitiligo, particularly in specific populations, reinforcing the role of TNF-α in immune dysregulation. Lastly, chemokines involved in immune cell recruitment to melanocytes further illustrate the complex inflammatory network underlying the disease. (4) Conclusions: This systematic review consolidates evidence from a decade of meta-analyses, underscoring the significance of cytokine dysregulation in vitiligo and highlighting potential therapeutic targets.

Metabolic anomalies in vitiligo: a new frontier for drug repurposing strategies

Vitiligo is a chronic autoimmune condition characterized by the destruction of melanocytes, leading to patchy loss of skin depigmentation. Although its precise cause remains unclear, recent evidence suggests that metabolic disturbances, particularly oxidative stress and mitochondrial dysfunction, may play a significant role in the pathogenesis of the disease. Oxidative stress is thought to damage melanocytes and trigger inflammatory responses, culminating in melanocyte immune-mediate destruction. Additionally, patients with vitiligo often exhibit extra-cutaneous metabolic abnormalities such as abnormal glucose metabolism, dyslipidemia, high fasting plasma glucose levels, high blood pressure, out of range C-peptide and low biological antioxidant capacity, suggesting a potential link between metabolic impairment and vitiligo development. This implies that the loss of functional melanocytes mirrors a more general systemic targetable dysfunction. Notably, therapies targeting metabolic pathways, particularly those involving mitochondrial metabolism, such as the peroxisome proliferator-activated nuclear receptor γ (PPARγ) agonists, are currently being investigated as potential treatments for vitiligo. PPARγ activation restores mitochondrial membrane potential, mitochondrial DNA copy number and, consequently, ATP production. Moreover, PPARγ agonists counteract oxidative stress, reduce inflammation, inhibit apoptosis, and maintain fatty acid metabolism, in addition to the well-known capability to enhance insulin sensitivity. Additionally, increasing evidence of a strong relationship between metabolic alterations and vitiligo pathogenesis suggests a role for other approved anti-diabetic treatments, like metformin and fibrates, in vitiligo treatment. Taken together, these data support the use of approaches alternative to traditional immune-suppressive treatments for the treatment of vitiligo.

Defective Intracellular Insulin/IGF-1 Signaling Elucidates the Link Between Metabolic Defect and Autoimmunity in Vitiligo

Background: Vitiligo is featured by the manifestation of white maculae and primarily results from inflammatory/immune-selective aggression to melanocytes. The trigger mechanism leading to the activation of resident immune cells in the skin still lacks a molecular description. There is growing evidence linking altered mitochondrial metabolism to vitiligo, suggesting that an underlying metabolic defect may enable a direct activation of the immune system. Recent evidence demonstrated the association of vitiligo with disorders related to systemic metabolism, including insulin resistance (IR) and lipid disarrangements. However, IR, defined as a cellular defect in the insulin-mediated control of glucose metabolism, and its possible role in vitiligo pathogenesis has not been proven yet. Methods: In this study, we compared the Ins/IGF-1 intracellular signaling of dermal and epidermal cells isolated from non-lesional vitiligo skin to that belonging to cells obtained from healthy donors. Results: We demonstrated that due to the intensified glucose uptake, S6, and insulin receptor substrate 1 (IRS1) chronic phosphorylation, their inducibilities were downsized, a condition that coincides with the definition of insulin resistance at the cellular level. Correspondingly, the mitogenic and metabolic activities normally provoked by Ins/IGF-1 exposure resulted in significantly compromised vitiligo cells (p ≤ 0.05). Besides all the vitiligo-derived skin cells manifesting an energetic disequilibrium consisting of a low ATP, catabolic processes activation, and chronic oxidative stress, the functional consequences of this state appear amplified in the keratinocyte lineage. Conclusion: The presented data argue for insulin and IGF-1 resistance collocating dysfunctional glucose metabolism in the mechanisms of vitiligo pathogenesis. In vitiligo keratinocytes, the intrinsic impairment of intracellular metabolic activities, particularly when associated with stimulation with Ins/IGF-1, converges into an aberrant pro-inflammatory phenotype that may initiate immune cell recruitment.

Pathogenesis and regenerative therapy in vitiligo and alopecia areata: focus on hair follicle

Vitiligo is an autoimmune disease characterized by the loss of functional melanocytes in the hair follicles and epidermis, leading to white patches on the skin and mucous membranes. Alopecia areata (AA) is a common immune-mediated condition in which autoimmune attack on hair follicles cause non-scarring hair loss. Both diseases significantly impact patients's physical and mental health. Hair follicles, dynamic mini-organs, house diverse stem cell populations that form hair structures. Melanocyte stem cell (McSCs) and hair follicle stem cells (HFSC) located in the hair follicle bulge contribute to follicular structures during each anagen phase of the hair cycle, synchronizing periodic activities to impact color to the hair. Hair follicle dysfunction may contribute to hair loss and could potentially interfere with repigmentation efforts in vitiligo lesions. This article reviews the role of hair follicles in the pathogenesis, clinical manifestations, and therapeutic options for vitiligo and AA, aiming to deepen clinicians' understanding of follicular involvement in these diseases and explore potential treatment avenues.