Valutazione degli effetti protettivi della somministrazione in vivo di Lactobacillus fermentum sui danni causati dallo stress ossidativo indotto dal trattamento con etanolo

Chronic alcohol consumption alters the morpho-functional characteristics of skeletal muscle, causing pain, chronic inflammation and loss of muscle mass, which in terms of skeletal fiber seems to be related to micronutrient deficiency. Based on the gut-muscle axis, alcohol-induced dysbiosis alters the composition of the intestinal microbiota, promoting its intestinal permeability and allowing the passage of microbial products, including lipopolysaccharides (LPS) in the bloodstream. Endotoxins and unmetabolized alcohol also reach the systemic circulation and other organs, including skeletal muscle, leading to reduced muscle mass, quality and function. We hypothesized that probiotic supplementation could play a key role in protecting against alcohol damage by modulating the intestinal microbiota and indirectly acting on skeletal muscle through the gut-muscle axis. The aim of this thesis was therefore to study the protective effects of the probiotic Lactobacillus fermentum (L. fermentum) against oxidative stress damage and inflammation induced by chronic consumption of ethanol (EtOH), using a mouse model of alcohol abuse. Young female mice were fed daily with EtOH for 8 (n=10) and 12 (n=10) weeks to induce oxidative stress and chronic inflammation. Twenty mice received only EtOH daily for 8 (n=10) and 12 (n=10) weeks, to induce oxidative stress and cause skeletal muscle damage; twenty mice received simultaneously EtOH and L. fermentum daily for 8 (n=10) and 12 (n=10) weeks to study the effectiveness of probiotics in alcohol-induced damage. Both groups were compared with control mice for 8 (n=10) and 12 (n=10) weeks, fed a standard diet. Our analysis showed that the administration of EtOH for 8 and 12 weeks induced muscle atrophy in all types of muscle fibers analyzed (type 1, 2A and 2B), a condition reversed following treatment with L. fermentum which seems to be fibro-specific and act mainly on oxidative fibers, both slow and fast, compared to glycolic fibers. Since alcohol consumption induces inflammation, levels of some cytokines such as IL-6, IL-10 and TNF-α were measured by ELISA, revealing the ability of probiotic to reduce alcohol-induced systemic inflammation, although histological analyses showed no signs of muscle fibrosis in the ethanol treated groups. An interesting correlation has emerged between oxidative stress induced muscle atrophy and the processes of fiber differentiation and repair damaged by chronic alcohol-mediated consumption of satellite cells. Analyzing the levels of HSP60, a well-known marker of oxidative stress, it was found that its expression was reduced following the administration of L. fermentum, hypothesizing a possible antioxidant role for the probiotic, counteracting the harmful effects of alcohol-mediated ROS overproduction. In addition, the reduction of oxidative stress was very well correlated with the ability to differentiate and repair satellite cells (SCs), evidenced by the high number of MyoD-positive cells following the administration of the probiotic. These data therefore indicate that L. fermentum could have antioxidant and antiinflammatory effects, suggesting its possible application in the treatment of muscular pathologies, such as sarcopenia and cachexia. the administration of L. fermentum, hypothesizing a possible antioxidant role for the probiotic, counteracting the harmful effects of alcohol-mediated ROS overproduction. In addition, the reduction of oxidative stress was very well correlated with the ability to differentiate and repair satellite cells (SCs), evidenced by the high number of MyoD-positive cells following the administration of the probiotic. These data therefore indicate that L. fermentum could have antioxidant and antiinflammatory effects, suggesting its possible application in the treatment of muscular pathologies, such as sarcopenia and cachexia.