Influence of IL-6 and TNF-α on clinical manifestations, activity and comorbidity in a group of patients with psoriatic arthritis

Abstract

Objectives To relate the levels of IL-6 and TNF-α in patients with psoriatic arthritis (PsA) with the clinical variants, the disease activity and the presence of comorbidities. Methods Cross-sectional observational study that included 184 patients with PsA according to CASPAR criteria. IL-6 and TNF-α levels were determined. As clinical variables, the clinical form (peripheral, axial or mixed), the presence of dactylitis, the severity of psoriasis measured by PASI and HLA-B27 were determined. Disease activity was measured by the tender joint count, swollen joint count, entheses affected, the severity of psoriasis measured by PASI, ESR, and CRP. The minimum disease activity (MDA) was also measured. Cardiovascular risk markers such as waist /hip ratio (w/ h) and analytical variables: apolipoprotein A, apolipoprotein B, lipoprotein a, insulin, insulin resistance (HOMA-R) and microalbuminuria in urine 24 hours (MA) were included in comorbidity. The presence of fatty liver was measured by ultrasound and fatigue by the FACIT-F questionnaire. Results The mean age of the patients was 55.12 years (SD: 11.29). One hundred and one were men (54.89%). 14.67% of the patients were on treatment with biologic DMARD (bDMARD). One hundred and two patients had peripheral involvement (55.43%), 69 mixed (37.5%) and 13 (7.07%) exclusively axial. 17.93% of the patients had a positive HLA-B27. 53.26% of the patients achieved a MDA. In the analysis of IL-6, we found a correlation with CRP (R: 0.32; P = 0.001), in addition, in patients with positive HLA-B27 we found lower concentrations of IL-6 (3.25 + 2, 26 Vs 5.81 + 7.23) -p < 0.001). We found no association with other variables related to inflammatory activity and / or comorbidity. TNF-α concentrations were higher in patients receiving TNF-α inhibitors ((178.89 SD: 181.31 vs 10.42 SD: 11.15; P < 0.001). Excluding these patients, we only found a correlation with the MA (R: 0.39; p < 0.001). Conclusions In our patients, the presence of HLA-B27 influenced IL-6 concentrations. TNF-α could be considered as a marker of subclinical renal damage.