Probiotics are emerging as a very fascinating therapeutic strategy for inflammatory bowel diseases (IBD). Their ability to recondition the altered microbiota of IBD patients could be enriched by selective delivery of bioactive molecules directly in the intestine via genetically engineered probiotics. Palmitoylethanolamide (PEA) is an endogenous ALIAmide that exhibits a wide range of anti-inflammatory and anti-angiogenic effects associated with the ability to restore the intestinal permeability in impaired epithelial barrier conditions. Thus, PEA takes place as a very promising candidate to reverse the pathological course of the disease in IBD patients. Because of PEA's unpredictable concentrations after oral administration, the present research plan is aimed at evaluating the effects of genetically modified bacteria able to biosynthesize PEA in an acute colitis model in mice. We will test the probiotic Lactobacillus paracasei subsp paracasei F19 (LP), that we have already engineered with human NAPEpld gene (pNAPE-LP) (European Patent EP3040070A1, Inventors: Augusto Sannetti, Rosario Cuomo, Giovanni Sarnelli, Giuseppe Esposito), in a set of in-vitro and in-vivo experiments to evaluate his ability (i) to release PEA under the boost of an ultra-low dose of exogenous palmitate and (ii) lead to a colitis resolution in comparison with LP transformed by the empty plasmid vector (pLP). Also, we will assess the efficacy of pNAPE-LP/palmitate formulation in cultured human colonic biopsies deriving from ulcerative colitis patients.
Preclinical data showing the involvement of endocannabinoids (ECs) in the regulation of inflammatory and immune response in the digestive tract inevitably promoted research on the role of ECs in IBD. ECs represent both an appealing therapeutic strategy and a captivating scientific dilemma since results from clinical trials must be carefully interpreted owing to possible reporting-biases related to cannabinoids' psychotropic effects. Moreover, discriminating between symptomatic improvement and the real gain on the underlying inflammatory process is often challenging. Currently, three main classes of cannabinoid-related drugs are considered for their potential therapeutic role in IBD: (1) "classical" cannabinoid receptor agonists, (2) inhibitors of enzymes involved in ECs catabolism, and (3) "non-classical" cannabinoid receptor agonists. Despite the evidence in humans is still sparse and generally limited to retrospective studies, the beneficial effects displayed by classical cannabinoid receptor agonists, as delta-9 tetrahydrocannabinol (THC), in Crohn's disease (CD) and ulcerative colitis (UC) patients strongly encourage their use in the IBD therapy. In fact, despite the inconsistent data produced, in a large Canadian survey, nearly 40% of IBD patients, who were regularly consuming Cannabis, believed that it was superior to corticosteroids for IBD management, and nearly 87% of them would recommend Cannabis to other IBD patients (Ahmed and Katz, 2016; Weiss and Friedenberg, 2015). Yet, a retrospective study has also indicated that Cannabis use is associated with an increased surgical risk in CD patients, questioning whether the perceived beneficial effects outweigh the risk of Cannabis use (Alhouayek and Muccioli, 2012; Hasenoehrl et al., 2017). These alarming figures urge the scientific community to successfully design novel therapeutics lacking central side-effects. CBD and inhibitors of enzymes involved in ECs catabolism have shown encouraging results in pre-clinical models of intestinal inflammation; however, clinical trials demonstrated the lack of significant clinical response and the induction of permanent neurological side effects, for at least one of the FAAH inhibitors. Contrariwise, non-classical ECs, like PEA, show high safety and excellent tolerability profile (Nestmann, 2016). Despite the lack of controlled trials assessing ALIAmides efficacy in IBD, these compounds represent very promising candidate-drugs and the main factor limiting their medical use is the often-unpredictable concentrations, following oral administration. One possibility to efficiently increase PEA tissue exposure could be the use of formulation enhancing its contact surface, like m-PEA and um-PEA or alternatively, the co-administration with anti-oxidants, like polydatin.
A very intriguing alternative strategy could be the oral administration of genetically engineered probiotics, able to successfully colonize the intestinal surface and to locally produce PEA, enhancing the likelihood of its tissue exposure. Remarkably, OEA-producing strains of E. Coli Nissle have been recently developed and tested with very promising results in a mouse model of obesity (Chen et al., 2014). In IBD, the synergistic targeting of the microbiota-host interactions and the ECs signaling pathway would represent a very fascinating therapeutic strategy. It would indeed allow us to overcome some of the main flaws shown by the previous trials evaluating cannabinoids-related drugs, given PEA virtually absent adverse events and the possibility of enhancing its delivery at the mucosal surface. Administration of engineered probiotics may represent a novel and useful approach for the management of IBD and other inflammatory gut-related diseases. This represents the main goal of our project involving engineered PEA-producing probiotics (European Patent number: 3040070A1, Sannetti A, Cuomo R, Sarnelli G, Esposito G).