The Impact of Sleeve Gastrectomy on Inflammatory Markers and Immune Response: A Study of Cytokine Changes, Weight Loss, and Insulin Resistance

Objectives: Obesity is strongly associated with chronic low-grade inflammation and immune system dysregulation, contributing to metabolic complications such as insulin resistance. Sleeve gastrectomy, a common bariatric surgery, is known for its weight-reducing effects, but its impact on inflammatory markers and immune response remains underexplored, particularly in Iraqi populations. This study aims to evaluate how sleeve gastrectomy influences specific blood cytokine levels, weight loss, and insulin sensitivity over time. Materials and Methods: A total of 40 obese patients (BMI >35 kg/m²) undergoing sleeve gastrectomy were enrolled from a private clinic in Baghdad. Participants were grouped based on the time of evaluation: before surgery, 3 months post-surgery, and 6 months post-surgery. Data collected included demographic information, BMI, fasting blood glucose, insulin, CRP, and serum levels of IL-1β, IL-12, IL-23, IL-33, IFN-α, IFN-γ, and MCP-1. Cytokines were measured using ELISA kits, and insulin resistance was calculated using the HOMA-IR model. Statistical analysis was conducted using ANOVA and Pearson correlation. Results: Following surgery, patients showed significant reductions in BMI and fasting blood glucose. Levels of IL-1β, IL-12, and IL-23 decreased markedly at both 3 and 6 months post-surgery (P<0.001), with additional reductions between the two postoperative periods. IL-33, IFN-α, and IFN-γ levels also declined significantly after surgery, although no notable difference was observed between 3 and 6 months. MCP-1 levels remained stable across all groups. Improvements in weight and inflammation were positively correlated, suggesting an immunomodulatory benefit of surgery. Conclusion: Sleeve gastrectomy leads to substantial weight loss and a significant reduction in systemic inflammation, reflected by lower cytokine levels. These changes may enhance immune balance and metabolic health, supporting the broader therapeutic value of bariatric surgery in managing obesity-related inflammation.