Drug resistant HTN (rHTN) affects around 15% to 20% of hypertensive (HTN) patients. The underlying mechanisms of resistance to treatment remain poorly understood. The majority of angiotensin-converting enzyme inhibitors (ACEi) are esters, whereby we hypothesized that select gut microbiota hydrolyze ACEi rendering lower efficacy (Figure 1A). To test this hypothesis, we investigated if and which gut microbe modulates the effectiveness of ACEi.
Vancomycin, Meropenem and Omeprazole (VMO) were given to 16-week-old male Spontaneously Hypertensive Rats (SHR) at 50 mg/kg/day for five days. A single dose of 8mg/kg Quinapril was orally administered to both SHR and SHR+VMO, and blood pressure (BP) was recorded via radio-telemetry. Liquid chromatography–mass spectrometry was used to measure the catabolism of quinapril. The hydrolysis of p-nitro-phenylbutyrate was used to measure the activity of bacterial esterase. 16S rRNA sequencing was used to study the microbial composition. At last, ester ACEi ramipril and non-ester lisinopril were co-administered with Coprococcus comes, respectively, to generalize the effect of C. comes on ACEis effectiveness
Compared to the SHR, depletion of gut microbiota in the SHR+VMO group preserved the BP lowering effect of Quinapril, an ester ACEi (Figure 1B). The SHR+VMO group showed (1) reduced Coprococcus (Figure 1C); (2) lower esterase activity per gram of cecal microbiota to hydrolyze quinapril (Figure 1D); (3) a 50% lower reduction in quinapril quantity (nmol) after incubation with 1mg of cecal lysate for 3 hr (Figure 1E). C. comes, a species in Coprococcus genus, catabolized quinapril in vitro and reduced its BP-lowering effects in the SHR (Figure 2A-B). Importantly, C. comes also reduced the BP-lowering effects of ramipril (ester), but not lisinopril (non-ester) in the SHR
These observations constitute the first report of an unrecognized role of a select gut microbe, C. comes, in reducing the effectiveness of ester ACEi. As such, this mechanistic study serves as the foundation for expanding clinical management of antihypertensive drug resistance via manipulation of gut microbiota.