Pretreatment with pro- and synbiotics reduces peritonitis-induced acute lung injury in rats

Background: To study whether enteral pretreatment with a synbiotic composition of lactic acid bacteria and bioactive fibers can reduce peritonitis-induced lung neutrophil infiltration and tissue injury in rats. Materials and Methods: Rats were divided into five groups, and subjected: to induction of peritonitis-induced lung injury using a cecal ligation and puncture model (CLP). All animals were pretreated for 3 weeks prior the CLP by daily gavage with either (1) a synbiotic composition (10(10) CFU of Pediococcus pentosaceus 5-33:3,: 10(10) CFU of Leuconostoc mesenteroides 77:1, 10(10) CFU of L. paracasei subspecies paracasei, 10(10) CFU of L. plantarum 2362 plus fermentable fibers), (2) fermentable fibers alone, (3) nonfermentable fibers, (4) a probiotic composition (10(10), CFU of P. pentosaceus 5-33:3, 10(10) CFU of L. mesenteroides 77:1, 10(10) CFU of L. paracasei subsp. paracasei, 10(10) CFU of L. plantarum 2,362), or (5) a heat-killed probiotic composition. All animals were killed 24 hours after CLP and lung tissue samples were studied for degree of neutrophil infiltration and levels of tumor necrosis factor (TNF)-alpha, Interleukin (IL)-1 beta. In addition the lung wet-to-dry tissue weight ratio, the myeloperoxidase activity, and malondialdehyde content were also assessed. Results: No mortality was encountered in any of the groups. Histologic signs of lung injury (number of neutrophils and TNF-alpha, IL-1 beta staining) were observed in all groups except the synbiotic and probiotic treated groups. Myeloperoxidase activity and malondialdehyde content were significantly lower in the two lactobacillus-pretreated groups, with no difference between them. Heavy infiltration of lung tissue with neutrophils was observed only in fiber-treated (302.20 +/- 7.92) and placebo-treated (266.90 +/- 8.92) animals. This was totally abolished in the synbiotic-treated group (34.40 +/- 2.49). Lung edema (wet-to-dry lung weight ratio) was significantly reduced in the synbiotic-treated group (4.92 +/- 0.13 vs. 5.07 +/- 0.08 and 5.39 +/- 0.10, respectively). Conclusion: Three weeks of preoperative enteral administration of a synbiotic composition reduced peritonitis-induced acute lung injury in rats in a CLP model.