Therapeutic Delivery of Ang(1-7) via Genetically Modified Probiotic: A Dosing Study

Abstract

In recent years a number of beneficial health effects have been ascribed to the renin-angiotensin system (RAS) that extend beyond lowering blood pressure, primarily mediated via the angiotensin-converting enzyme-2 (ACE2)/angiotensin (1-7) or Ang(1-7)/MAS receptor axis. Moreover, once thought as merely a systemic effector, RAS components exist within tissues. The highest tissue concentrations of ACE2 mRNA are located in the gut making it an important target for altering RAS function. Indeed, genetically engineered recombinant probiotics are promising treatment strategies offering delivery of therapeutic proteins with precision. An Ang(1-7) secreting Lactobacillus paracasei (LP) or LP-A has been described for regulation of diabetes and hypertension; however, we are the first to the best of our knowledge to propose this paradigm as it relates to aging. In this Research Practice manuscript, we provide proof of concept for using this technology in a well-characterized rodent model of aging: the Fisher344 x Brown Norway Rat (F344BN). Our primary findings suggest that LP-A increases circulating levels of Ang(1-7) both acutely and chronically (after 8 or 28 treatment days) when administered 3× or 7×/week over 4 weeks. Our future preclinical studies will explore the impact of this treatment on gut and other age-sensitive distal tissues such as brain and muscle.

Keywords: Lactobacillus; Ang-(1–7); Dysbiosis; Probiotics; Renin-angiotensin system.

Figure 1.

Ang(1–7) promotes beneficial actions of the renin-angiotensin system (RAS). Once thought to merely regulate blood pressure, the RAS is now known to have a variety of physiologic functions, including beneficial effects of the Ang(1–7) axis.

Figure 2.

(A) Weekly body weight (Days 1, 8, 15, and 29) and (B) cumulative food intake were measured in 24-month-old male F344BN rats administration of 2 × 10¹¹ CFU/ kg body weight LP-A in four dosing conditions: 0×, 1×, 3×, or 7×/week. There were no observed differences in either measure indicating animals were tolerant of the treatment with no impact to gross overall health.

Figure 3.

Circulating RAS analytes were measured in 24-month-old male F344BN rats after 8 days (acute) and 29 days (chronic) administration of 2 × 10¹¹ CFU/ kg body weight LP-A in four dosing conditions: 0×, 1×, 3×, or 7×/week. The graphs describe results for (A) Ang(1–7); (B) AngII; (C) Ang(1–7)/Ang(II) ratio; (D) ACE2; (E) ACE; (F) ACE2/ACE ratio. Overall, dosing 3× and 7×/week resulted in significantly higher levels of Ang(1–7), lower levels AngII and a higher ratio of the Ang(1–7)/AngII at both time points. ACE2 levels were significantly higher acutely in the 1×, 3×, and 7×/weeks groups but these effects persisted chronically only in the 3× and 7×/week groups. ACE levels were higher only acutely in the 1×, 3×, and 7×/week groups. There were no differences observed with chronic treatment nor in the ratio of ACE2/ACE at either time point. Data are presented as mean ± SEM. * denotes dosing condition significantly different from the 0×/week condition at their respective time points. ACE2 = angiotensin-converting enzyme-2; Ang(1–7) = angiotensin (1–7); LP = Lactobacillus paracasei; RAS = renin-angiotensin system.