OP‐3 THE PROTECTIVE ROLE OF LACTOBACILLUS RHAMNOSUS GG‐DERIVED FACTORS AGAINST LPS‐INDUCED DAMAGE OF HUMAN COLONIC SMOOTH MUSCLE CELLS.

Abstract

Impaired gut barrier function has been reported in some functional gastrointestinal (GI) disorders.Evidences suggest that gut microbiota affects GI motility in particular Lactobacillus species elicits anti‐inflammatory activity and exerts protective effects on damage induced by pathogen Gram negative‐derived lipopolysaccharide(LPS). LPS produced an oxidative imbalance in human colonic smooth muscle cells (SMC) that persists after LPS‐washout and contributes to SMC morphofunctional alterations. Aim: evaluate if supernatants harvested from LGG cultures protect SMC from LPS‐induced myogenic damage.Methods:L. rhamnosus GG (ATCC 53103 strain) was grown in MRS medium and samples were collected from bacterial cultures in middle exponential phase, in early, in middle and late stationary phase (overnight).Supernatants were recovered, filtered and stored at ‐20 °C. Highly pure human SMC culture was then exposed for 24 h to highly purified LPS (1 μg/ml) of E.coli (O111:B4) in the absence and presence of the supernatants.Their effects were evaluated on LPS‐induced SMC morphofunctional alterations and pro‐inflammatory IL‐6 production. Data are expressed as mean ± SE (p < 0.05 significant).Results:LPS induced persistent significant 20.7% ± 1.2 cell shortening and 35.2% ± 2.6 decrease in contraction of human colonic SMC. These alterations were paralleled to a 238.5% ± 82.5 increase in IL‐6 production.These effects disappeared in the presence of LGG‐supernatants, following a progression related to LGG growth curve phases. Supernatants collected in the middle exponential phase already significantly partially restored LPS‐induced cell shortening by 43.4% ± 10.2 and IL6 increase by 47.6% ± 13.1 but had no effect on LPS‐induced inhibition of contraction. Supernatants collected later, in the early and middle stationary phase, further counteract LPS‐induced damage, including inhibition of contraction. Maximal protective effects were observed with supernatants of the late stationary phase where LPS‐induced cell shortening was reversed by 86% ± 4.7, inhibition of contraction by 98.2% ± 1.8 and IL6 basal production by 91.3% ± 0.6.Conclusions: LGG secreted products are substances/byproducts able to directly protect human SMC from LPS‐induced myogenic damage. Novel insights are then provided about the possibility that LGG‐derived products could reduce the risk of progression to a post‐infective motor disorder.