Serum IL-23 significantly decreased in obese patients with psoriatic arthritis six months after a structured weight loss intervention

Introduction Patients with psoriatic arthritis (PsA) are frequently obese. We have previously shown decreased disease activity in patients with PsA with a body mass index (BMI) ≥ 33 kg/m 2 following weight loss treatment with Very Low Energy Diet (VLED), resulting in a median weight loss of 18.6% at six months (M6) after baseline (BL). In this study we assessed the effects of VLED on cytokines and adipokines at M6 in the same patients with PsA and controls (matched on sex, age and weight). Methods VLED (640 kcal/day) during 12 or 16 weeks, depending on BL BMI < 40 or ≥ 40 kg/m 2 , was taken and followed by an energy-restricted diet. Cytokines and adipokines were measured with Magnetic Luminex Assays at BL and M6. Results Serum interleukin (IL)-23, (median (interquartile range) 0.40 (0.17–0.54) ng/mL vs. 0.18 (0.10–0.30) ng/mL, p < 0.001) and leptin (26.28 (14.35–48.73) ng/mL vs. 9.25 (4.40–16.24) ng/mL, p < 0.001) was significantly decreased in patients with PsA. Serum total (tot)-adiponectin and high molecular weight (HMW) adiponectin increased significantly. Similar findings were found in controls. Also, in patients with PsA, ∆BMI was positively correlated with ∆IL-23 (r S = 0.671, p < 0.001). In addition, significant positive correlations were found between ΔBMI and ΔDisease Activity Score (DAS28CRP), ΔCRP, Δtumor necrosis factor (TNF)-α, ΔIL-13, ∆IL-17 and Δleptin, and negative correlations between ΔBMI and Δtot-adiponectin. Conclusions Weight loss was associated with decreased levels of leptin and cytokines, in particular IL-23. These findings may partly explain the anti-inflammatory effect of weight reduction in PsA. Trial registration ClinicalTrials.gov identifier: NCT02917434, registered on September 21, 2016, retrospectively registered.