Introduction: Epigenetic modifications have been implicated to mediate several complications of diabetes mellitus (DM), especially nephropathy and retinopathy. Our aim was to ascertain whether epigenetic alterations in whole blood discriminate among patients with DM with normal, delayed, and rapid gastric emptying (GE).
Methods: Using the ChIP-seq (chromatin immunoprecipitation combined with next-generation sequencing) assays, we compared the genome-wide enrichment of 3 histone modifications (i.e., H3K4me3, H3K9ac, and H3K27ac) in buffy coats from 20 diabetic patients with gastrointestinal symptoms and normal (n = 6), delayed (n = 8), or rapid (n = 6) GE.
Results: Between patients with DM with delayed vs normal GE, there were 108 and 54 genes that were differentially bound (false discovery rate < 0.05) with H3K27ac and H3K9ac, respectively; 100 genes were differentially bound with H3K9ac in patients with rapid vs normal GE. The differentially bound genes with H3K27ac were functionally linked to the type 2 immune response, particularly Th2 cell activation and function (e.g., CCR3, CRLF2, CXCR4, IL5RA, and IL1RL1) and glucose homeostasis (FBP-1, PDE4A, and CMKLR1). For H3K9ac, the differentially occupied genes were related to T-cell development and function (e.g., ICOS and CCR3) and innate immunity (RELB, CD300LB, and CLEC2D). Compared with normal GE, rapid GE had differential H3K9ac peaks at the promoter site of diverse immunity-related genes (e.g., TNFRSF25 and CXCR4) and genes related to insulin resistance and glucose metabolism. Motif analysis disclosed enrichment of binding sites for transcription factors relevant to the pathogenesis and complications of DM.
Discussion: GE disturbances in DM are associated with epigenetic alterations that pertain to dysimmunity, glucose metabolism, and other complications of DM.