Modification of the animal immune system by feeding probiotics

摘要

The objective of this study was to examine immune effects of feeding novel probiotic Lactobacillus acidophilus strain NP51 to specific pathogen-free Balb/c mice challenged with Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of Johne\u27sdisease (JD). We hypothesized that feeding the NP51 would activate the adaptive immunity and impede the development of MAP infection in murine model of JD. Thus, Balb/c mice were randomized to treatment groups in a factorial design including mice that either fed the heat-killed or viable NP51 (HNP51 or VNP51, respectively) and challenged with either a heat-killed or a viable MAP (HMAP or VMAP, respectively). Mice were fed 1 × 106 CFU of either HNP51 orVNP51*mice-1*day-1 mixed with standard mouse chow until the end of the study. Subsequently, mice were challenged with 1 × 108 CFU of HMAP or VMAP injected intraperitonealy on day 45 of the study. Ten mice from each group were euthanized on days 45, 90, 135, and 180. Spleens were excised and used for an in vitro splenocytes cell cultures that were either stimulated with sonicated MAP antigen or concanavalin A and examined for the cytokine secretion pattern andfrequency of T lymphocyte subpopulations. Blood was withdrawn by cardiac puncture and used for examination of immunoglobulins production. HNP51 and VNP51 differentially stimulated the adaptive immunity and decrease MAP tissue burden. With VMAP as the inoculum, both VNP51 and HNP51 stimulated CD8α+ immune cell-mediated immunity and decreased the humoral immunity. When HMAP was used as the inoculum, VNP51 stimulated the CD8α+ immune cells-mediated and the humoral immunity. In contrast, HNP51 feeding induced CD8α+ immune cells-mediated immunity only as verified by the differential cytokines and immunoglobulins secretion pattern. The data provide persuasive evidence that NP51 has the potency to prevent JD infection in murine model of JD.