Commentary from the Editorial Board to Vitiligo: interplay between oxidative stress and immune system (Laddha et al.)

Autoimmune vitiligo in rheumatic disease in the mestizo Mexican population

Vitiligo is a chronic disease characterized by the dysfunction or destruction of melanocytes with secondary depigmentation. The aim of the present study was to determine the prevalence of vitiligo associated with autoimmune rheumatic diseases. The clinical records from a 10-year database of patients with rheumatic diseases and associated vitiligo was analysed, with one group of patients having autoimmune rheumatic disease and another non-autoimmune rheumatic disease. Available serum samples were used to assess the anti-melanocyte antibodies. A total of 5,251 individual clinical files were archived in the last 10 years, and these patients underwent multiple rheumatology consultations, with 0.3% of the group presenting with vitiligo. The prevalence of vitiligo in the autoimmune rheumatic disease group was 0.672%, which was mainly associated with lupus and arthritis. However, patients with more than one autoimmune disease had an increased relative risk to develop vitiligo, and anti-melanocyte antibodies were positive in 92% of these patients. By contrast, the prevalence was 0.082% in the group that lacked autoimmune rheumatic disease and had negative autoantibodies. In conclusion, the association between vitiligo and autoimmune rheumatic diseases was relatively low. However, the relative risk increased when there were other autoimmune comorbidities, such as thyroiditis or celiac disease. Therefore, the presence of multiple autoimmune syndromes should be suspected.

Oxidative stress and immune system in vitiligo and thyroid diseases

Vitiligo is an acquired dermatological disease frequently associated with autoimmune thyroid disorders. Several theories have been proposed so far to unravel the complex vitiligo pathogenesis. Currently, the autocytotoxic and the autoimmune theories are the most accredited hypothesis, since they are sustained by several important clinical and experimental evidences. A growing body of evidences shows that autoimmunity and oxidative stress strictly interact to finally determine melanocyte loss. In this scenario, associated thyroid autoimmunity might play an active and important role in triggering and maintaining the depigmentation process of vitiligo.

High prevalence of circulating autoantibodies against thyroid hormones in vitiligo and correlation with clinical and historical parameters of patients

BACKGROUND

Autoantibodies against thyroid hormones (THAbs) directed towards triiodothyronine (T3-Ab) and/or thyroxine (T4-Ab) are very rare in the general population. They are increased in some nonthyroidal autoimmune diseases, where they seem to predict autoimmune thyroid disorders (ATDs). So far, their presence in patients with vitiligo has not been evaluated, but it might have a possible predictive role.

OBJECTIVES

To assess the prevalence of THAbs in a group of vitiligo patients and to correlate their presence with clinical and historical parameters.

METHODS

In total 79 patients with nonsegmental vitiligo and 100 controls were examined. Clinical characteristics of vitiligo and family and personal medical history were evaluated. Antinuclear autoantibodies, thyroid hormones and thyroid autoantibodies were measured. IgM T3-Ab, IgG T3-Ab, IgM T4-Ab and IgG T4-Ab were assayed by a radioimmunoprecipitation technique. Fisher's test, Student's t-test and χ(2)-test were used for statistical analysis.

RESULTS

Overall 77 of 79 patients (97%) had at least one type of THAb (11 T3-Ab, 10 T4-Ab, 56 both). In the control group, only one person (1%) had THAbs. In patients with vitiligo, T3-Abs were significantly associated with leucotrichia (IgM+IgG, P = 0.033; IgG, P = 0.039; IgM, P = 0.005) and thyroglobulin autoantibodies (IgM+IgG, P = 0.031; IgG, P = 0.058), while the absence of T3-Ab was related to personal history of cancer (IgM+IgG, P = 0.021; IgG, P = 0.039). T4-Abs were significantly associated with vitiligo activity (IgM+IgG, P < 0.001; IgM, P = 0.037) and duration (IgG, P = 0.013).

CONCLUSIONS

The surprisingly high prevalence of THAb in patients with vitiligo and their associations suggest a possible pathogenetic role in the disease and stress the tight link between vitiligo and ATDs. Further evaluation in a larger group of patients and an adequate follow-up are needed to define their potential predictive role.

Vitiligo and alopecia areata: apples and oranges?

Vitiligo and alopecia areata are common autoimmune diseases of the skin. Vitiligo is caused by the destruction of melanocytes and results in the appearance of white patches on any part of the body, while alopecia areata is characterized by patchy hair loss primarily on the scalp, but may also involve other areas as well. At first glance, the two diseases appear to be quite different, targeting different cell types and managed using different treatment approaches. However, the immune cell populations and cytokines that drive each disease are similar, they are closely associated within patients and their family members, and vitiligo and alopecia areata have common genetic risk factors, suggesting that they share a similar pathogenesis. Like apples and oranges, vitiligo and alopecia areata have some obvious differences, but similarities abound. Recognizing both similarities and differences will promote research into the pathogenesis of each disease, as well as the development of new treatments.