Downregulating the P2X3 receptor in the carotid body to reduce blood pressure via acoustic gene delivery in canines

Abstract

The purinergic P2X3 receptor in the carotid body (CB) is considered a new target for treating hypertension, although approaches for targeted regulating P2X3 receptor expression are lacking. Here, we explored the feasibility of targeted P2X3 receptor down-regulation in CBs by localized low-intensity focused ultrasound (LIFU)-mediated gene delivery to reduce the blood pressure. Thirty-two Kunming canines were randomly assigned to the treatment group (n = 14), negative control group (n = 10), LIFU + cationic microbubbles group (n = 4), and LIFU-only group (n = 4). Plasmid-loaded cationic microbubbles were injected and bilateral CBs were irradiated with a LIFU-based transducer. Flow cytometry showed that 33.15% of transfected cells expressed the green fluorescent protein reporter gene. T7 endonuclease I assays showed an insertion-deletion rate of 8.30%. The P2X3 receptor mRNA- and protein-expression levels in CBs decreased by 56.31% and 45.10%, respectively, in the treatment group. Mean systolic (152.5 ± 3.0 vs 138.0 ± 2.9 mm Hg, P = 0.003) and diastolic (97.8 ± 1.5 vs 87.2 ± 2.3 mm Hg, P= 0.002) blood pressures reduced on day 14 in the treatment group, compared with the baseline values, whereas no effects were observed with LIFU treatment or cationic microbubbles injection alone. Canines treated with this strategy exhibited no local or systemic adverse events. Thus, LIFU-mediated gene delivery to CBs successfully modulated CB function and reduced blood pressure in a canine model, suggesting a new possibility for treating hypertension and further clinical translation.

Keywords: Acoustic gene delivery; Carotid body; Hypertension; Low-intensity focused ultrasound; P2X3 receptor.