Assessment of the role of vitamin D and IL-17 in the pathogenesis of acne vulgaris

Aim-hypothesis: Acne vulgaris (AV) is a chronic, inflammatory disease of the pilosebaceus unit which commonly affects adolescents. The four major pathogenetic factors are follicular epithelial hyperproliferation and consequent follicular blockage, hormonal effects, increased secretion of sebum, and an increase in the presence and activity of Propionibacterium acnes (P. acnes). There are reports that P. acnes, which is believed to play a role in pathogenetic mechanisms and almost all of the steps, is the main factor in the induction of the immunization system and in the onset of the resulting inflammation. Although the immunoreactivity mediated through both the innate immune system via Toll-like receptor 2 (TLR2) and the acquired immune system through the activation of Th1 lymphocytes, recent studies have also demonstrated roles of Th17 cells and IL-17 . Vitamin D, which we know to be involved in bone metabolism, has also been shown to play a role in immunoregulation. There is evidence that vitamin D inhibits TLR2 expression and Th17 cells on monocytes, thereby reducing the production of proinflammatory cytokines. We aimed to evaluate the effect of IL-17 and vitamin D levels on the pathogenesis of AV in our study. The roles of these two substances in AV severity and their effects on each other was also to be analyzed. Methods: Between October 2015 and April 2017, 80 AV patients (49 women / 31 men) and 80 healthy controls (40 women / 40 men) were admitted to the study at the Dermatology Clinic of Adnan Menderes University Hospital. Patients with history or physical examination of chronic disease, those using vitamin D supplements previus month, patients under the age of 15 or over 45 years were not included. AV patients who had received systemic or topical treatment for AV disease in the previus month were also not included. Demographic and clinical features were recorded. Blood samples were collected from all participants. IL-17, was studied by sandwich ELISA method and vitamin D was studied by the chemiluminescence method. Results: 80 (49 female / 31 male) acne vulgaris cases and 80 (40 female / 40 male) healthy controls were included in the study. There was no significant difference between acne and control groups with regards to age and gender distribution. The median vitamin 25 (OH) D3 vitamine level of the patient group was 18.90 (11.50-22.95) ng / ml. The median vitamin 25 (OH) D3 level in the control group was 17,20 (10,40-19,30) ng / ml. In the patient group vitamin 25 (OH) D3 level was significantly higher than the control group (p = 0.038). In our study, the median IL-17 level of the patient group was 469,71 (157,26- 640,00) (pg / ml) while the median IL-17 level of the control group was 468,40 (153,54-640,00). There was no statistically significant difference between the two groups (p = 0.959). When the AV patients were classified according to the global acne grading system as mild (<18) and moderate-severe (> 18) according to severity, vitamin D level in the mild group was 18,45 (12,75-23,12) ng / ml while the vitamin D level in the moderate-severe group was 17,95 (11,18-23,13) ng / ml. There was no significant relationship between the severity of AV lesions and the vitamin 25 (OH) D3 levels(p = 0,623). IL-17 levels in the mild group was 534,70 (207,36- 640,00) pg / ml, In the moderate-severe group, the level of IL-17 was found to be 368.05 (137.64-640.00) pg / ml. There was no significant relationship between the severity of AV lesions and IL-17 level in the patients either (p = 0,256). Conclusion: In this study, which examined the role of vitamin D and IL-17 levels in the pathogenesis of AV disease, no significant relationship between AV disease and vitamin D and IL-17 levels was obversed. Keywords: Acne vulgaris, vitamin D, IL-17