In this episode, Annet Kirabo, Jane Ferguson, and colleagues provide evidence that high-salt diet-induced changes in the gut microbiome promote dendritic cell activation, leading to inflammation and hypertension.
Excess dietary salt contributes to inflammation and hypertension via poorly understood mechanisms. Antigen-presenting cells including DCs play a key role in regulating intestinal immune homeostasis in part by surveying the gut epithelial surface for pathogens. Previously, we found that highly reactive γ-ketoaldehydes or isolevuglandins (IsoLGs) accumulate in DCs and act as neoantigens, promoting an autoimmune-like state and hypertension. We hypothesized that excess dietary salt alters the gut microbiome leading to hypertension and this is associated with increased immunogenic IsoLG adduct formation in myeloid antigen-presenting cells. To test this hypothesis, we performed fecal microbiome analysis and measured blood pressure of healthy human volunteers with salt intake above or below the American Heart Association recommendations. We also performed 16S rRNA analysis on cecal samples of mice fed normal or high-salt diets. In humans and mice, high-salt intake was associated with changes in the gut microbiome reflecting an increase in Firmicutes, Proteobacteria, and genus Prevotella bacteria. These alterations were associated with higher blood pressure in humans and predisposed mice to vascular inflammation and hypertension in response to a subpressor dose of angiotensin II. Mice fed a high-salt diet exhibited increased intestinal inflammation, including the mesenteric arterial arcade and aorta, with a marked increase in the B7 ligand CD86 and formation of IsoLG protein adducts in CD11c+ myeloid cells. Adoptive transfer of fecal material from conventionally housed high-salt diet–fed mice to germ-free mice predisposed them to increased inflammation and hypertension. These findings provide potentially novel insights into the mechanisms underlying inflammation and hypertension associated with excess dietary salt and may lead to interventions targeting the microbiome to prevent and treat this important disease.
Jane F. Ferguson, Luul A. Aden, Natalia R. Barbaro, Justin P. Van Beusecum, Liang Xiao, Alan J. Simmons, Cassandra Warden, Lejla Pasic, Lauren E. Himmel, Mary K. Washington, Frank L. Revetta, Shilin Zhao, Shivani Kumaresan, Matthew B. Scholz, Zhengzheng Tang, Guanhua Chen, Muredach P. Reilly, Annet Kirabo