Abstract 086: Examining The Role Of Bacterial Extracellular Vesicles In Host Blood Pressure Regulation

Abstract

We have demonstrated that disruption of the normal gut microbiota, termed gut dysbiosis, is an underlying cause of hypertension (HT). However, the mechanisms by which the microbiota influences host blood pressure (BP) are largely unknown. We hypothesized that extracellular vesicles (EVs) released by gut microbiota gain access to the circulation, deliver cargo to host tissues involved in BP regulation, inducing inflammation and ultimately HT. Bacterial EVs (bEVs) were isolated from cecal content of spontaneously hypertensive stroke prone rats (SHRSP) or Wistar-Kyoto rats (WKY) by size exclusion chromatography. BEV cargo including small RNAs, LPS, and 16s rRNA, was assessed. To directly examine the role of bEVs on BP, purified WKY and SHRP bEVs were transplanted to recipient rats of the same and opposite strain by oral gavage (1.5x10 10 EVs/rat) every other day for 4 weeks. The inflammatory status of ileum and brain were assessed by flow cytometry. Global analysis of small RNA cargo of bEVs was found to be significantly different between WKY and SHRSP (n=6, p=0.001). BEVs from SHRSP contained significantly greater LPS as compared to those from WKY (49 vs 38 EU/ml, n=6, p=0.01). EVs isolated from plasma of both strains contained bacterial 16s rRNA, demonstrating bEVs gain access to host circulation. Finally, as compared to WKY rats receiving WKY bEVs, WKY rats transplanted with SHRSP bEVs had 1) significant elevations in BP at 4 weeks (176 mmHg vs 150 mmHg, n=6, p<0.01), 2) significant reduction of T regulatory cells in ileum (49% vs 58%, n=6, p<0.05) and brain (9% vs 18%, n=6, p<0.05), and 3) significant increases in macrophages in ileum (39% vs 6%, n=6, p<0.001) and microglia in brain (24% vs 8%, n=6, p<0.05). SHRSP rats transplanted with WKY bEVs had significantly lower BP at 4 weeks (160 mmHg vs 175 mmHg, n=6, p<0.05), reduced macrophages in ileum (5% vs 42%, n=6, p<0.001) and microglia in brain (5% vs 29%, n=6, p<0.01), as compared to SHRSP receiving SHRSP bEVs. In conclusion, BEVs originating from the dysbiotic gut of hypertensive SHRSP rats carry distinct cargo, reach the host circulation, and are involved in host gut- and neuroinflammation and HT. These studies identify bEVs as a previously unrecognized mechanism for microbiota-host interaction involved in BP regulation.