Cytokine gene polymorphisms are associated with irritable bowel syndrome: a systematic review and meta-analysis
Article first published online: 16 AUG 2012
© 2012 Blackwell Publishing Ltd
Neurogastroenterology & Motility
Volume 24, Issue 12, pages 1102–e566, December 2012
How to Cite
Bashashati, M., Rezaei, N., Bashashati, H., Shafieyoun, A., Daryani, N. E., Sharkey, K. A. and Storr, M. (2012), Cytokine gene polymorphisms are associated with irritable bowel syndrome: a systematic review and meta-analysis. Neurogastroenterology & Motility, 24: 1102–e566. doi: 10.1111/j.1365-2982.2012.01990.x
- Issue published online: 26 NOV 2012
- Article first published online: 16 AUG 2012
- Received: 30 March 2012 Accepted for publication: 5 July 2012
- genetic polymorphism;
- irritable bowel syndrome
Background Low-grade inflammation has been increasingly implicated in the pathophysiology of irritable bowel syndrome (IBS). Imbalances of pro- and anti-inflammatory cytokines and polymorphisms in cytokine genes have been reported in IBS; however, these findings have not been consistently observed. This may be due to small sample sizes and differences in ethnicities. Therefore, we performed a meta-analysis on the studies that investigated cytokine gene polymorphisms in IBS patients compared to healthy controls.
Methods A PubMed and EMBASE search was performed, and cytokine gene polymorphisms, which had been investigated in at least two case-control studies, were evaluated. Pooled odds ratios (OR) for the genotypes were calculated using random- or fixed-effects models.
Key Results Five studies that investigated interleukin-10 (IL-10; −1082 G/A), transforming growth factor-β1 (TGF-β1; +869 T/C and +915 G/C) and tumor necrosis factor (TNF; −308 G/A) polymorphisms in IBS patients and controls were included. High producer IL-10 (−1082 G/G; OR: 0.64 [95% CI: 0.48–0.87]) was significantly associated with a decreased risk of IBS. The intermediate producer TGF-β1 (+915 G/C) genotype showed a tendency toward decreasing the risk of IBS. No associations were found between TNF (−308 G/A) genotypes and IBS in the whole meta-analysis although an analysis of Asian studies revealed an association between TNF (−308 G/A and G/G) genotypes and IBS (OR: 0.50 [95% CI: 0.29–0.85]), and 1.82 [95% CI: 1.08–3.07], respectively).
Conclusions & Inferences This meta-analysis indicates a role for IL-10 polymorphisms in IBS in general and TNF in Asian populations. Whether or not gene polymorphisms are associated with alterations in cytokine levels leading to functional effects at the level of the gut needs further investigation.