Abstract
Diabetes mellitus (DM) is characterized by increased fatality associated with the atherogenetic process. Circulating trimethylamine-N-oxide (TMAO) levels are closely associated with atherosclerosis. The flavin mono-oxygenase family (Fmo) members oxidize trimethylamine (TMA) to TMAO. The effect and the regulatory mechanism of intestinal microflora on diabetes-induced Fmo3 and intercellular adhesion molecule (ICAM) expression were examined in streptozotocin-induced diabetic mice (STZDM) and Akita mice (C57BL/6J-Ins2Akita). STZDM-JNK1-/- and Ins2Akita-JNK1-/- mice were produced and used to study the role of pJNK in the regulatory mechanisms. Diabetic mice exhibited decreased Lactobacilli growth and reactive oxygen species (ROS) production in the intestinal mucosa; increased levels of pJNK and iNOS proteins in the intestinal mucosa; increased levels of serum nitrate, IL-1β, and TNF-α expression in Kupffer cells; increased Fmo3 expression in the liver; and increased ICAM expression in the aorta. Reversal of diabetes-induced enteric dysbiosis by prebiotic (FOS) or probiotic (dead L. plantarum) treatment decreased diabetes-induced pJNK and iNOS expression in the intestine, Fmo3 expression in the liver, IL-1β expression in Kupffer cells, and ICAM expression in the aorta and liver. Ins2Akita-JNK1-/- and STZDM-JNK1-/- mice demonstrated decreased levels of serum NO, IL-1β expression in Kupffer cells, Fmo3 expression in the liver, and ICAM expression in the aorta. GF mice cohoused with DM mice demonstrated an increase in ICAM expression in the liver. In conclusion, diabetes induced the expression of both Fmo3 and ICAM expression and possible vascular impairment through enteric dysbiosis. Diabetes-induced Fmo3 and ICAM expression could be reversed by pJNK inhibition or by correcting enteric dysbiosis.