Expression of Human ACE2 in Lactobacillus and Beneficial Effects in Diabetic Retinopathy in Mice

Abstract

The angiotensin converting enzyme 2 (ACE2) catalyzes the degradation of Angiotensin II (Ang II) to generate Angiotensin-(1-7), which reduces inflammation and oxidative stress stimulated by Ang II. ACE2 has been shown to be protective in cardiovascular and metabolic diseases including diabetes and its complications. However, the challenge for its clinical application is large-scale production of high-quality ACE2 with sufficient target tissue bioavailability. We developed an expression and delivery system based on the use of probiotic species Lactobacillus paracasei (LP) to serve as a live vector for oral delivery of human ACE2. We show that codon-optimized ACE2 can be efficiently expressed in LP. Mice treated with the recombinant LP expressing the secreted ACE2 in fusion with the non-toxic subunit B of cholera toxin, which acts as a carrier to facilitate transmucosal transport, showed increased ACE2 activities in serum and tissues. ACE2-LP administration reduced the number of acellular capillaries, blocked retinal ganglion cell loss, and decreased retinal inflammatory cytokine expression in two mouse models of diabetic retinopathy. These results provide proof of concept for feasibility of using engineered probiotic species as live vector for delivery of human ACE2 with enhanced tissue bioavailability for treating diabetic retinopathy, as well as other diabetic complications.

Angiotensin-(1–7) Expressed From Lactobacillus Bacteria Protect Diabetic Retina in Mice

“…As reported previously, 39 the backbone Lactobacillus shuttle plasmid containing a GFP reporter gene driven by the lactate dehydrogenase (LDH) promoter from Lactobacillus acidophilus was from Addgene (Plasmid #27167). 40 The original GFP reporter gene was replaced by a synthetic gene construct in which the Ang-(1–7) peptide is expressed as a secreted fusion protein with the CTB ( Fig.…”

“…We generated an expression system based on the use of recombinant Lactobacillus paracasei (LP) to serve as a live vector for the oral delivery of the Ang-(1–7) using the strategy that we have reported previously. 39 The Ang-(1–7) peptide is expressed as a secreted fusion protein with the chorea toxin binding protein subunit B (CTB), which facilitates the transmucosal transport into circulation and tissue uptake by GM1 receptor mediated endocytosis. We show that oral administration of LP expressing Ang-(1–7) significantly attenuated diabetes-induced loss of retinal capillaries and retinal ganglion cells (RGCs), and reduced the inflammatory cytokine expression in diabetic animals.…”

Recent Developments in Diabetic Retinal Neurodegeneration: A Literature Review

“…Among substances with unknown or mixed mechanisms, flavonoids and other nutritional supplements show great promise [ 125 – 129 , 137 – 140 ]. Substances that alter the RAS have been extensively studied, with exciting new prospects [ 147 – 149 ]. Other promising agents with neuroprotective effects in animal models of DRN include GLP-1RA liraglutide [ 150 – 154 ], lamivudine (P2rx7 inhibitor) [ 155 ], endothelin-1 receptor antagonists [ 156 , 157 ], and agents lowering intraocular pressure [ 158 , 159 ].…”

“…Treatment of STZ-induced diabetic rats with an angiotensin-converting enzyme 2 (ACE2) activator significantly reduced the apoptotic cell death of RGCs compared with untreated diabetic rats [ 148 ]. Verma et al used engineered probiotic species as live vector for oral delivery of human ACE2 with enhanced tissue bioavailability, blocking RGC loss in two mouse models of diabetic retinopathy, while also reducing retinal inflammatory cytokine expression and the number of acellular capillaries [ 149 ].…”

Probiotics in the prophylaxis of COVID-19: something is better than nothing

“…It helps the host cells in preventing viral replication (Conti et al 2009). Furthermore, the study of Verma et al 2019, demonstrated the expression and secretion of Human (Angiotensin-Converting Enzyme) ACE-2 (a receptor required by COVID-19 virus for its binding) in Lactobacillus paracasei (Verma et al 2019).…”