No abstract

The association between atherosclerosis and gut microbiota has been attracting increased attention. We previously demonstrated a possible link between gut microbiota and coronary artery disease. Our aim of this study was to clarify the gut microbiota profiles in coronary artery disease patients using data mining analysis of terminal restriction fragment length polymorphism (T-RFLP). This study included 39 coronary artery disease (CAD) patients and 30 age- and sex- matched no-CAD controls (Ctrls) with coronary risk factors. Bacterial DNA was extracted from their fecal samples and analyzed by T-RFLP and data mining analysis using the classification and regression algorithm. Five additional CAD patients were newly recruited to confirm the reliability of this analysis. Data mining analysis could divide the composition of gut microbiota into 2 characteristic nodes. The CAD group was classified into 4 CAD pattern nodes (35/39 = 90 %), while the Ctrl group was classified into 3 Ctrl pattern nodes (28/30 = 93 %). Five additional CAD samples were applied to the same dividing model, which could validate the accuracy to predict the risk of CAD by data mining analysis. We could demonstrate that operational taxonomic unit 853 (OTU853), OTU657, and OTU990 were determined important both by the data mining method and by the usual statistical comparison. We classified the gut microbiota profiles in coronary artery disease patients using data mining analysis of T-RFLP data and demonstrated the possibility that gut microbiota is a diagnostic marker of suffering from CAD.

The gut microbiota were shown to play critical roles in the development of atherosclerosis, but the detailed mechanism is limited. The purpose of this study is to clarify the influence of gut microbiota on atherogenesis via lipid metabolism and systemic inflammation. Germ-free or conventionally raised (Conv) ApoE-deficient (ApoE−/−) mice were fed chow diet and euthanized at 20 weeks of age. We found that the lack of gut microbiota in ApoE−/− mice caused a significant increase in the plasma and hepatic cholesterol levels compared with Conv ApoE−/− mice. The absence of gut microbiota changed the bile acid composition in the ileum, which was associated with activation of the enterohepatic fibroblast growth factor 15, fibroblast growth factor receptor 4 axis, and reduction of cholesterol 7α-hydroxylase and hepatic bile acid synthesis, resulting in the accumulation of liver cholesterol content. However, we found that the lack of microbiota caused a significant reduction in atherosclerotic lesion formation compared with Conv ApoE−/− mice, which might be associated with the attenuation of lipopolysaccharide-mediated inflammatory responses. Our findings indicated that the gut microbiota affected both hypercholesterolemia and atherogenesis in mice.

Although regulatory T cells (Tregs) have been shown to play a protective role in abdominal aortic aneurysm (AAA) formation, it remains unclear whether expansion of endogenous Foxp3 + Tregs prevents AAA. In the current study, we determined the effects of endogenous Foxp3 + Treg expansion or depletion in an experimental model of AAA. We continuously infused 12-week-old apolipoprotein E–deficient mice fed a high-cholesterol diet with angiotensin II (n=60) or normal saline (n=12) by implanting osmotic mini-pumps and evaluated AAA formation at 16 weeks. The angiotensin II–infused mice received interleukin-2/anti–interleukin-2 monoclonal antibody complex (interleukin-2 complex; n=31) or PBS (n=29). Eighty-one percent of angiotensin II–infused mice developed AAA, with 42% mortality possibly because of aneurysm rupture. Interleukin-2 complex treatment systemically increased the number of Foxp3 + Tregs and significantly decreased the incidence (52%) and mortality (17%) of AAA. Immunohistochemical analysis showed reduced accumulation of macrophages and increased numbers of Foxp3 + Tregs in aneurysmal tissues, suggesting that expansion of Tregs may suppress local inflammation in the vessel wall and provide protection against AAA formation. Furthermore, genetic depletion of Foxp3 + Tregs led to a significant increase in the mortality of AAA, suggesting the protective role of Foxp3 + Tregs against AAA. Our findings suggest that Foxp3 + Tregs may play a protective role in AAA formation and that promotion of an endogenous regulatory immune response may be a potentially valuable therapeutic approach for preventing AAA.