Repigmentation Competence in Vitiligo: Integrating Immune, Regulatory, Regenerative, and Microenvironmental Axes

Vitiligo is an autoimmune depigmenting disorder characterized by marked heterogeneity in therapeutic response, both between patients and among lesions within the same individual. While current therapies primarily target interferon-γ (IFN-γ)-driven inflammation, clinical outcomes remain variable and frequently incomplete, suggesting that additional lesion-specific biological factors contribute to repigmentation potential. In this narrative review, we propose the concept of repigmentation competence to describe the capacity of an individual lesion to achieve clinically meaningful repigmentation under therapy. We hypothesize that this competence emerges from the interaction of four interconnected biological axes: (i) cytokine network and immune memory, (ii) local immune regulation, (iii) regenerative capacity, and (iv) microenvironmental permissiveness. A targeted search of PubMed/MEDLINE and ClinicalTrials.gov up to March 2026 was conducted to identify translational studies, mechanistic models, and clinical trials relevant to these pathways. Evidence was synthesized thematically with emphasis on cytokine-mediated mechanisms and their interaction with regenerative and tissue-context processes. The IFN-γ/CXCL9/CXCL10 axis and tissue-resident memory T cells (TRM) represent the most clinically validated drivers of disease persistence, as demonstrated by the therapeutic efficacy of JAK inhibitors, although immune suppression alone often fails to achieve complete or durable repigmentation. In contrast, regulatory pathways involving PD-1/PD-L1 signaling, regulatory T cells (Tregs), IL-10, TGF-β, and IL-2-based strategies remain biologically compelling but only partially translated into effective therapies. Regenerative capacity has also emerged as an important determinant of treatment response, with growing evidence supporting the role of melanocyte stem cell niches, follicular regeneration, and Wnt/β-catenin signaling. Accordingly, regenerative approaches such as non-cultured epidermal cell suspension (NCES) are increasingly being integrated into combination therapeutic strategies. The lesional microenvironment remains the least therapeutically developed axis despite growing experimental evidence supporting its importance in melanocyte survival and migration. Collectively, these observations suggest that the variable efficacy of current therapies may reflect different combinations of lesion-specific biological constraints. The emerging benefit of combination strategies may therefore derive not simply from additive effects, but from the simultaneous engagement of multiple axes involved in repigmentation competence. Our review supports a shift from a predominantly drug-centered model toward a lesion-oriented framework integrating immune, regenerative, regulatory, and microenvironmental determinants of response.