Abstract 009: Genetically Modified Probiotics for Oral Delivery of Angiotensin-(1-7) Confers Protection Against Pulmonary Hypertension

Background: Previous studies have established that activation of the members of the vasoprotective axis of the renin-angiotensin system [Angiotensin Converting Enzyme 2 (ACE2) or Angiotensin-(1-7) (Ang-(1-7))] prevents and arrests progression of pulmonary hypertension (PH) pathophysiology. Our objective in this present study was to generate a probiotic containing Ang-(1-7) and test the hypothesis that oral administration of such a probiotic would provide cardiopulmonary protection against PH. Methods: In this study, we genetically modified the commensal bacterium Lactobacillus paracasei (LP), commonly found in the gut and used as a probiotic, to serve as a live vector for the oral delivery of Ang-(1-7) and investigated its therapeutic potential in attenuating PH. The vectors pTRKH3- ldh -SP-GFP or pTRKH3- ldh -SP-Ang-(1-7) were introduced by electroporation into LP. PH was induced by a single injection of monocrotaline (MCT; 50 mg/Kg s.c) in rats. A subset of animals was orally gavaged every other day for four weeks with 1x10 9 CFU of LP, LP secreting GFP (LP-GFP), or LP secreting Ang-(1-7) (LP-A). Results: Oral feeding of LP-A significantly reduced MCT-induced right ventricular systolic pressure (RVSP) by 43% (Control: 27±1; MCT: 76±8; MCT+LP: 56±6; MCT+LP-GFP: 59±7; MCT+LP-A: 43±3 mmHg) and RV hypertrophy by 33% (Control: 0.25±0.01; MCT: 0.6+0.02; MCT+LP: 0.48±0.04; MCT+LP-GFP: 0.48±0.04; MCT+LP-A: 0.41±0.03). Moreover, LP-A feeding restored cardiac contractility (Control: 2070±95; MCT: 3133±295; LP-A: 2060±119 mmHg/s) and attenuated myocardial fibrosis. These beneficial effects on the cardiopulmonary system were associated with profound changes in gut pathology. MCT-induced PH was associated with an increase in ileum villus length and thickening of proximal colon, and a decrease in goblet cells/villus area, all of which indicate intestinal injury and altered immune status. However, these parameters were significantly attenuated by oral feeding of LP-A. Conclusions: Oral administration of a genetically modified commensal bacterium that can secrete Ang-(1-7) provides cardiopulmonary protection against PH. Thus, delivery of Ang-(1-7) by probiotic means could be considered an innovative therapeutic strategy for PH.