Gut microbiota dysbiosis augments atherosclerosis in LDLR-/- mice

Aim: In recent years the gut microbiome has been recognized as an important participant in the etiology of obesity and -associated comorbidities. Moreover, recent studies have implicated an involvement of the gut microbiota in both cardiovascular health and disease. Although the gut microbiome has been suggested as a contributor to atherosclerosis, firm evidence to support a causal role for the gut microbiota in atherosclerosis is limited. Methods: To investigate the effect of the gut microbiota in atherosclerosis, we performed fecal microbiota transplantation to transplant the gut microbiota of caspase1-/- mice, an established model for dysbiosis, into LDLR-/- mice (LDLR-/-[casp1-/-]). Fecal microbiota transplantation of the gut microbiota of LDLR-/- mice into LDLR-/- mice (LDLR-/-[LDLR-/-]) served as control. Mice were fed a chow or high-fat cholesterol diet (HFC, 0,21% cholesterol) for 13 weeks and fecal samples were collected to determine microbiota composition by 16S rRNA sequencing. Plaque size was analyzed in the aortic root and immune cell subsets were analyzed by flow cytometry. Results: 16S rRNA sequencing of fecal samples confirmed the induction of dysbiosis in LDLR-/-[casp1-/-] compared to LDLR-/-[LDLR-/-] mice. Body weight, plasma triglyceride and cholesterol levels were significantly increased by HFC-feeding in LDLR-/-[casp1-/-] and LDLR-/-[LDLR-/-] mice. However, dysbiosis did not affect these parameters. In contrast, plaque size was significantly increased in HFC-fed LDLR-/-[casp1-/-] compared to HFC-fed (LDLR-/-[LDLR-/-] mice. Furthermore, dysbiosis in LDLR-/- mice was associated with a moderate increase in circulatory levels of Ly6C-high monocytes. Conclusions: Our data shows that gut microbiota dysbiosis augments atherosclerosis, possibly by exacerbating low-grade systemic inflammation.