Crucial genes of inflammatory bowel diseases explored by gene expression profiling analysis.

OBJECTIVES

This study aimed to uncover new potential genes associated with the inflammatory bowel diseases (IBDs).

MATERIALS AND METHODS

The datasets GSE36807 and GSE9686 were obtained from Gene Expression Omnibus (GEO). Totally, 24 Crohn's disease (CD) samples, 20 ulcerative colitis (UC) samples and 15 healthy controls in the two datasets were used for our analysis. The differentially expressed genes (DEGs) were identified by limma package. Then, co-expression network was constructed by weighted gene correlation network analysis (WGCNA) package, and co-expression network modules were obtained via clustering method. The top 100 genes with the highest connectivity degrees were selected to construct a new co-expression network (CEN). Besides, pathway enrichment analysis for the genes in identified modules was conducted with the clusterProfiler package in R.

RESULTS

Totally, 302 and 2276 DEGs were respectively identified in CD and UC samples, and 291 ones were both differentially expressed in the two subtypes. Five modules were identified from the CEN. In the new CEN consisted of the top 100 genes with the highest connectivity degrees, the up-regulated DEGs all belonged to module 5, and the down-regulated ones all belonged to module 1. Furthermore, pathway enrichment analysis showed that some DEGs were related to primary immunodeficiency (e.g., CD4, CD3D and CD40LG), complement and coagulation cascades (e.g., C2, C1QB and C7) and nitrogen metabolism (e.g., CA1, CA12 and CA2).

CONCLUSION

The DEGs correlated with primary immunodeficiency, complement and coagulation cascades and nitrogen metabolism might be important for the development of IBD.