Evaluation of serum granulysin and cathepsin-l levels in vitiligo patients

Vitiligo is a chronic acquired pigmentation disease characterized by selective destruction of melanocytes, with sharply demarcated, depigmented macules and patches on the skin and mucous membranes. Although its etiology is not clearly known, many theories have been proposed, and the most accepted one is the autoimmune theory. Natural killer cell and melanocyte-specific CD8+ T cell mediated cytotoxicity play a role in the pathogenesis of the disease. Granulysin is a cytolytic protein found in the granules of cytotoxic T lymphocytes and natural killer cells, which acts synergistically with perforin to induce apoptosis. It has been shown that the level of granulysin, which is also found in the serum of healthy individuals, increases with the increase in the activity of these cells. Cathepsin-L is a lysosomal protease involved in various physiological processes such as apoptosis, major histocompatibility complex class II mediated antigen presentation, and epidermal homeostasis in humans. Cathepsin-L also plays an important role in the formation of cytotoxic T lymphocytes and natural killer cell-mediated immune response. Increased cathepsin-L expression has been found in many inflammatory and neoplastic skin diseases. In this study, it was aimed to measure the serum granulysin and cathepsin-L levels in vitiligo patients and to evaluate the roles of these molecules in the pathogenesis of the disease and their relationship with disease activity and severity. The study was carried out with 92 volunteers, including 46 vitiligo patients and 46 control group. Disease severity and activity in the vitiligo group were evaluated by VASI and VIDA methods, respectively. The demographic characteristics of the patient and control groups and the data on the disease of the patient group were questioned and recorded. In addition, serum granulysin and cathepsin-L levels of both groups were measured by Elisa method. In both groups, those with concomitant autoimmune, allergic and/or chronic inflammatory systemic and/or skin diseases were excluded from the study as they may affect granulysin and cathepsin-L levels. Both groups included in the study consisted of 46 individuals. Age (31.22±10.91), gender (F/M=1.1) and body mass index (25.7±3.6) of the patient group and age (32.72±9.47), gender (F/M=1) and body mass index (25.22±3.57) of the control group were similar. When vitiligo was classified according to clinical subtypes, 27 patients (58.7%) had common, 12 patients (26.1%) had acral/acrofacial and 7 patients (15.2%) had focal vitiligo. The mean disease duration was 5.51±5.01 years and the age of onset was 25.84±12.12 years. The most common disease origin was head and neck (n=18). While the median value of the VASI score was 1 (0.10-46.15); VIDA score was -1 in 5 patients (10.9%), 0.1 in 10 patients (21.7%) +1 in 1 patient (2.2%) +2.7 in 8 patients (17.4%) ,2) +3 and +4 in 15 patients (32.6%). Halo nevus was present in 2 (4.3%), leukotrichia in 25 (53.8%), Köbner's phenomenon in 10 (21.7%) and mucosal involvement in 9 (19.6%) patients. There was a family history of vitiligo in 12 of 46 patients (26.1%), and the presence of vitiligo in the family was statistically significantly higher in the patient group compared to the control group (p=0.003). The mean serum granulysin level (45.53±31.42 ng/ml) in vitiligo patients was statistically significantly higher than the control group (34.26±21.53 ng/ml) (p=0.048). There was no statistically significant correlation between serum granulysin level and VIDA and VASI scores in the patient group. The mean serum cathepsin-L level (13.98±10.84 ng/ml) in vitiligo patients was statistically significantly higher than the control group (9.61±6.92 ng/ml) (p=0.024). There was no statistically significant correlation between serum cathepsin-L level and VIDA and VASI scores in the patient group. Although granulysin and cathepsin-L are molecules that may play a role in the pathogenesis of vitiligo, there is no relationship between their levels and disease activity and severity. It may be beneficial to conduct more comprehensive prospective studies on the role of these molecules in the pathogenesis of vitiligo.