Early changes in circulating cytokines and leukocyte profiles after bariatric surgery: a six-month prospective study

Severe obesity is associated with chronic immunometabolic disturbances that may improve after bariatric surgery, although early postoperative immune trajectories remain incompletely characterized.

To characterize early postoperative changes in selected circulating cytokines and immune-cell profiles and explore their associations with postoperative weight loss.

In this prospective cohort study, adults undergoing Roux-en-Y gastric bypass or sleeve gastrectomy were evaluated at baseline, 3 months, and 6 months after surgery. Fifty participants were assessed at baseline, 17 had paired baseline-to-3-month data, and 7 completed all three assessments. Plasma interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α) concentrations were measured by ELISA. Peripheral blood mononuclear cells were analyzed by flow cytometry, including classical, intermediate, and non-classical monocytes; CD4+ and CD8+ T cells; and exploratory CD127^low/high fractions. The primary analysis comprised paired baseline-to-3-month comparisons, whereas analyses involving the 6-month assessment were exploratory because of follow-up attrition. Nonparametric tests with Holm-Bonferroni adjustment were applied.

In the primary paired analysis, no statistically significant baseline-to-3-month changes were detected in IL-10 or TNF-α concentrations. An exploratory complete-case analysis involving the 6-month assessment indicated lower IL-10 concentrations across follow-up, whereas TNF-α trajectories remained heterogeneous. The canonical monocyte-subset hierarchy and CD14/CD16 fluorescence-intensity patterns were observed across the available samples. No statistically significant longitudinal changes were detected in broad CD4+ and CD8+ T-cell distributions, while exploratory CD127 analyses suggested subtle differences within T-cell compartments. In an exploratory analysis of 15 participants, greater excess weight loss was associated with larger reductions in TNF-α.

The primary baseline-to-3-month analysis indicated limited changes in the selected circulating cytokines and broad immune-cell distributions evaluated. Additional patterns observed in the small 6-month complete-case cohort were exploratory and require confirmation in larger longitudinal studies.