Umeå universitets logga

Introduction: Roux-en-Y Gastric Bypass (RYGB) is a common treatment option for obesity. After RYGB, loss of both adipose tissue and lean body mass is seen. In this study, we have investigated the dynamic metabolic changes of hyaluronan (HA) and associated biomarkers reflecting the extracellular matrix after RYGB.

Materials and Methods: In this exploratory cohort study, a total of 306 serum samples were collected at 5 different times from 96 RYGB patients, preoperatively until 6 months after surgery, where 44/96 (46%) contributed samples at 6 months. HA and the cell-surface receptor CD44 were studied by enzyme-linked immunosorbent assay (ELISA), while Luminex Multiplex assays were used for MMP-2, MMP-9, TNF-α, IL-1β, IL-6 and IL-10.

Results: Preoperatively, an elevated HA-concentration (> 120 ng/ml) was seen in 39.6% of the study population. From baseline to day of surgery, we found a statistically significant decrease (p < 0.05) in HA (Δ-21.4ng/mL [-42.6, -0.27]), CD44 (Δ-26.7ng/mL [-46.4, -6.9]), MMP-2 (Δ-32.4 ng/mL [-41.4 -23.4]) and MMP-9 (Δ-138.2 ng/mL [-188.0, -88.4]), TNF-α(Δ-3.1 pg/mL [-5.4, -0.8]), IL-1β (Δ-14.4 pg/mL [-22.2, -6.6]) and IL-6 (Δ-2.0 pg/mL [-3.1, -0.9]). At one month postoperatively, a subsequent increase was seen. Although the mean concentration of HA was unchanged at 6 months, patients with baseline HA ≥ 120 ng/mL demonstrated a decrease, (Δ-37.1 [-55.8 to -14.7] p < 0.01; exploratory analysis)

Conclusion: Although mean HA levels returned to baseline at 6 months, a significant transient decrease was observed immediately postoperatively, and patients with elevated preoperative HA (> 120ng/ml) showed a sustained reduction. The postoperative increase of MMP-2 suggests a continuous remodeling of the extracellular matrix.