Cytokine imbalance in irritable bowel syndrome: a systematic review and meta-analysis

Abstract Background Irritable bowel syndrome ( IBS ) is a functional gastrointestinal disorder of unknown etiology; although infection and inflammation have recently been considered as important etiologic agents. A recent meta‐analysis showed correlations between cytokine [interleukin‐10 ( IL ‐10) and tumor necrosis factor ( TNF )] gene polymorphisms and IBS ; however, it is still unknown whether patients with IBS have different cytokine profiles compared to healthy population. Methods To determine the relationships between serum/plasma levels or mucosal expression of IL ‐10/ TNF ‐ α and IBS , we conducted a systematic review and meta‐analysis based on case–control studies retrieved from PubMed and EMBASE search through A ugust 2013. Standardized mean difference ( SMD ) was generated by using the inverse variance method. Heterogeneity was assessed based on I 2 values. Key Results Serum/plasma levels of TNF ‐ α tended to be higher in IBS vs controls ( p = 0.09); this reached significance in IBS subtypes vs controls and in female patients with IBS . However, serum/plasma levels of IL ‐10 were not significantly different in IBS patients vs controls. Further analysis of serum/plasma IL ‐10 levels in IBS subtypes did not show any difference; however, analysis based on gender showed a significantly lower serum/plasma IL ‐10 levels in male patients with IBS vs male controls ( p = 0.02). Colonic IL ‐10 m RNA had a significantly lower expression in IBS vs control ( p = 0.001). Conclusions & Inferences There is an imbalance of proinflammatory TNF ‐ α , and anti‐inflammatory IL ‐10, cytokines in IBS . Stratifying IBS patients based on cytokine profile may represent an opportunity for personalized treatment of this condition.