A six-month weight loss intervention is associated with significant changes in serum biomarkers related to inflammation, bone and cartilage metabolism in obese patients with psoriatic arthritis and matched controls.

BACKGROUND: Obesity is highly overrepresented in patients with psoriatic arthritis (PsA) and associated with increased disease activity and inferior treatment outcome. We have previously reported in 41 patients with PsA and body mass index (BMI) ≥ 33 kg/m(2) that weight loss treatment with Very Low Energy Diet (VLED) resulted in a median weight loss of 18,6% and concomitantly a significant improvement in C-reactive protein (CRP) and disease activity at six months (M6). This sub-study analyzes the effects on serum biomarkers associated with inflammation, bone and cartilage metabolism in the same PsA patients and matched controls. METHODS: Patients and controls received VLED treatment (640 kcal/day) during 12-16 weeks depending on baseline (BL) BMI < 40 or ≥ 40 kg/m(2), followed by an energy restricted diet. Serum was collected at BL and M6, and biomarkers were measured with Magnetic Luminex(®) Assays and enzyme-linked immunosorbent assay (ELISA). Nonparametric statistics and paired comparison tests were used. RESULTS: In the PsA patients, the following proteins were significantly reduced at M6 as compared to BL: hepatocyte growth factor (HGF) (median (first-third quartile) 327.9 (250.3-413.6) pg/mL vs. 271.3 (206.9-331.0) pg/mL, p < 0.01), vascular endothelial growth factor (VEGF) (79.6 (55.9-113.5) pg/mL vs. 69.6 (53.1-105.3) pg/mL, p = 0.01), B-cell activating factor (BAFF) (794.4 (716.4-868.3) pg/mL vs. 674.6 (613.2-790.5) pg/mL, p = 0.01) and cartilage oligomeric matrix protein (COMP) (266.1 (209.9-366.0) ng/mL vs. 217.0 (156.0-272.0) ng/mL, p < 0.01), whereas carboxyterminal telopeptide of type-1 collagen (CTX-1) was significantly increased (268.0 (196.0-378.5) pg/mL vs. 508.0 (350.0-640.0) pg/mL, p < 0.01). Similar results were found in the control group. CONCLUSIONS: Weight loss was associated with reduced levels of serum biomarkers related to inflammation and cartilage degradation, and increased biomarkers for bone resorption. The study supports the strong relationship between obesity, inflammation, bone and cartilage metabolism, identifying BMI as a possible confounder for biomarker levels. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02917434, registered on September 21, 2016, retrospectively registered.