NOS3 and Hyperglycemia: Indeed, an engineered strain of Lactobacillus paracasei expressing the human ACE2 protein, besides ameliorating hyperglycaemia, is able to reduce systemic inflammation, improve the integrity of the gut epithelial barrier (as measured by the markers zonula occludens-1 (ZO-1) and p120-catenin), and counteract the development and progression of DR when administered preventively or therapeutically in Akita and endothelial nitric oxide synthase (eNOS)−/− mice (mouse models of diabetes) [209,212].