Correlation between serum IL-17 and peripheral blood Treg cells and efficacy of 308 nm excimer light therapy in progressive vitiligo.

OBJECTIVE

We hypothesized that baseline immune status, specifically the Th17/Treg axis, influences therapeutic outcomes. This study aimed to investigate the correlation between serum interleukin-17 (IL-17) and peripheral blood regulatory T cells (Tregs), Vitiligo Area Scoring Index (VASI), and the efficacy of 308 nm excimer light therapy by comparing an active treatment group of progressive vitiligo patients (subdivided into effective and ineffective subgroups) with a control group of stable vitiligo patients. Key variables investigated included baseline and post-treatment IL-17, Treg cell levels, and VASI scores.

METHODS

A total of 117 patients with progressive vitiligo treated with 308 nm excimer light were divided into ineffective (n = 31) and effective (n = 86) groups based on 6-month outcomes. An additional 35 patients with stable vitiligo were recruited as a control group. Serum IL-17, Treg cell levels, and VASI scores were measured at baseline and after 6 months of therapy for progressive vitiligo patients, and once for stable vitiligo patients. These parameters were compared between groups. Changes from baseline were analyzed. Risk factors for treatment failure were analyzed using logistic regression based on baseline parameters, and receiver operating characteristic (ROC) curves evaluated the exploratory predictive value of baseline IL-17 and Treg cells.

RESULTS

At baseline, the ineffective progressive vitiligo group had significantly higher IL-17 and VASI scores, and lower Treg cell levels compared to the effective group (p < 0.05). After 6 months of treatment, the effective group showed a significant decrease in IL-17 and VASI, and an increase in Treg cells (P < 0.05), while the ineffective group showed no significant changes. Post-treatment IL-17 and Treg levels in the ineffective group remained significantly different from the effective group (p < 0.05). Patients with stable vitiligo had significantly lower IL-17 and higher Treg cell levels compared to both progressive vitiligo groups at baseline (p < 0.05). Baseline VASI scores correlated positively with baseline IL-17 and negatively with baseline Treg cells (p < 0.05). Multivariate logistic regression identified baseline autoimmune comorbidities, baseline VASI scores, IL-17, and Treg cells as independent predictors for treatment failure (p < 0.05). ROC analysis revealed optimal cutoff values of 21.15 ng/L for baseline IL-17 (sensitivity 80.65%, specificity 79.07%, AUC 0.875) and 3.75% for baseline Treg cells (sensitivity 83.87%, specificity 74.42%, AUC 0.818). Combined detection of baseline markers achieved a sensitivity of 80.65%, a specificity of 95.35% and an AUC of 0.921. These exploratory predictive models are internally derived and require external validation.

CONCLUSION

Baseline and post-treatment serum IL-17 and Treg cell levels, along with VASI scores, correlate with 308 nm excimer light therapy outcomes in progressive vitiligo. These baseline biomarkers, particularly IL-17 and Treg cells, are associated with treatment response. Distinct biomarker profiles exist between progressive and stable vitiligo. Combined baseline marker testing improves the evaluation of treatment potential.