Changes in Inflammatory Markers Following Bariatric Surgery and the Impact of the Surgical Procedure: A 12-Month Longitudinal Study

BACKGROUND: Obesity is associated with an increased risk of cardiometabolic morbidity and mortality, which may be attributable to systemic low-grade inflammation. The impact of bariatric surgery-induced weight loss on low-grade inflammation has not yet thoroughly been described. We investigated the effect of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) on the plasma levels of cytokines, chemokines, and cytokine receptors prior to surgery (baseline), and then three and 12 months after surgery.

METHODS: We recruited 68 individuals (41 females, 27 males) with severe obesity (42.84 ± 6.28) who had been referred for bariatric surgery (RYGB: n = 29, SG: n = 39). Blood samples were collected after an overnight fast at baseline (immediately before surgery), 3 and 12 months after surgery. Eleven patients without obesity or cardiometabolic disease served as controls at baseline. Ninety-two plasma proteins were measured using an Olink Target 96 inflammation panel.

RESULTS: We used a linear mixed model to test differences in inflammatory markers at baseline, across time points and between groups. At baseline, 36 cytokines were found to be differentially expressed between the bariatric surgery patients and controls. Of these cytokines, 13 had significantly decreased three months after bariatric surgery and 27 had significantly decreased 12 months after surgery, compared with baseline. Two cytokines (CCL25 and CCL28) increased markedly after 12 months. Only one cytokine (CCL25) was significantly different between the procedures performed, where it increased in the RYGB group 12 months after surgery.

CONCLUSION: Individuals with severe obesity have increased expression of plasma inflammatory cytokines compared to controls, but low-grade inflammation improves following bariatric surgery, regardless of whether it is RYGB or SG.