Objectives Our aim was to evaluate serum IL-17A, IL-17B, IL-17C, IL-17F and IL-23 levels in Psoriatic Arthritis (PsA) patients and to explore the relationships between serum IL levels and clinical and laboratory findings and disease activity indices.

Methods 40 patients fulfilling CASPAR criteria for PsA were consecutively selected for this study. Patients with disease which may be effect interleukine levels were excluded. Control group consisted of 27 healthy volunteers. Demographic, clinical and laboratory data of the patients were recorded. The Body Mass Index (BMI), severity of pain (VAS), global assessment of general health (VAS), morning stiffness, disease duration were evaluated. Quality of life was assessed with PsAQoL, SF-36 and Notthingham Health Profile. Maastricht Ankylosing Spondylitis EnthesitisScore (MASES) was used for evaluation of enthesitis. Patients and control group serum IL -17A, IL-17B, IL-17C, IL-17F and IL-23 levels were evaluated by ELISA method. Mann-whitney U test, independent sample t test, Spearman rho test were used in statistical analysis. p <0.05 was accepted as statistically significant.

Results 40 patients (14 men, 26 women) and age and sex matched 27 healthy volunteers (12 men, 15 women) were recruited into the study. The mean age and BMI of patients and control group were 46,14 (SD:10,54), 49,96 (SD:6,35) years and 30,57 (SD:5,66), 28,96 (SD:5,84) kg/m² respectively ( p=0,102; p=0,277 ). The median duration of psoriatic arthritis was 8 months (min: 1, max: 144, interquartile range: 1-36). The median morning stiffness duration was 30 minutes (interquartile range: 0-35). The patients’ scores (mean ± SD) were; VAS pain 41,67 (SD:28,45) mm; VAS general health status: 41,72 (SD:26,69) mm. There was a statistically significant difference between PsA and control groups for IL-17A and IL-17C serum levels (p=0,012, p=0,003 respectively). There was not any difference in PsA group for IL levels between smokers and nonsmokers. There was a significant negative correlation between IL-17C levels and VAS pain, VAS general health (p=0,015, r=-0,439; p=0,037, r=-0,369 respectively). There was not any statistically significant correlation between serum IL-17A, IL-17B, IL-17C, IL-17F and IL-23 levels and morning stiffness, duration of PsA, thoracal and lomber schöbers, ESR, PASI scores, MASES, NHP and PsAQoL scores. When analyzed according to smoking status, in control group, IL-17C level was found to be sigificantly higher in smokers group. We could not find such a relation for IL-17A, IL-17B, IL-17C, IL-17F and IL-23 levels in either groups

Conclusions Interleukin-17A level was significantly higher in PsA patients compared to healthy subjects concordant with the literature. Interestingly IL-17C serum levels were significantly higher in healthy controls. There was a significant negative correlation between IL-17C levels and VAS pain, VAS general health. There was not any significant relation between interleukine levels and clinical and functional parameters in PsA patients. The role of IL-17A in pathogenesis of PsA, and probable effect of smoking on IL levels and inflammation should be evaluated in large series.

Disclosure of Interest None Declared