Dietary Fibre Attenuates Hypertension By Reducing Macrophage Infiltration Via Gut Microbiota-Derived Metabolite-Sensing Receptors

High dietary fibre is fermented by the gut microbiota, resulting in the release of metabolites called short-chain fatty acids (SCFAs). Both fibre and SCFAs can reduce high blood pressure (BP) and its associated cardio-renal complications. However, the underlying mechanisms remain unclear. SCFAs can be detected by metabolite-sensing receptors GPR41 and GPR43, highly expressed by immune cells such as macrophages. We hypothesised that dietary fibre attenuates hypertension by modulating renal macrophage infiltration via metabolite-sensing receptors GPR41 and GPR43. To test this, we developed a novel GPR41/GPR43 double knockout (DKO) mice and characterised the cardiovascular and immune phenotype in both sham and angiotensin-II (Ang-II, 0.5mg/kg/day) treated DKO and wild-type (WT) mice (n=7-12 per group). WT Ang-II mice fed a high-fibre diet had significantly lower renal galectin-3 (p=0.0004), a macrophage marker, compared to WT Ang-II mice fed a low-fibre diet. Sham DKO mice on standard chow diet had no difference in BP or heart function but had higher kidney/tibia length index (p=0.049) and renal fibrosis levels compared to WT mice (p=0.004). Moreover, untreated DKO mice had higher numbers of renal macrophages compared to WT mice (p=0.002). Ang-II infusion of DKO mice resulted in higher BP (p<0.0001), renal fibrosis (p=0.007), and mortality (hazard ratio=5.6) compared to WT mice. In the gut, we found significant inflammatory changes, gut barrier integrity disruption, gut microbiota and metabolome changes (all p<0.05). We also found evidence of lipopolysaccharides (LPS) translocation from the gut into the circulation of DKO mice. In conclusion, we show that a high-fibre diet attenuates hypertension by modulating renal macrophages via the gut microbiota-derived metabolite-sensing GPR41 and GPR43 receptors. These receptors can be targeted as a novel treatment for hypertension.