Immunobiotic Lactobacillus rhamnosus enhances systemic and respiratory innate immune response in malnourished mice

VILLENA, JULIO; HERRERA, MATÍAS; SALVA, SUSANA; BARBIERI, NATALIA; KITASAWA, HARUKI; ALVAREZ, SUSANA

Taiwan

Congreso; 14th Asian-Australasian Association of Animal Production Societies (AAAP). Animal Science Congress; 2010

The oral administration of Lactobacillus rhamnosus CRL1505 (Lr) to malnourished mice, was capable of improving resistance against Streptococcus pneumoniae (Sp) (1, 2). In this work we studied the effects of Lr on the innate immune response against Sp. Malnourished Swiss mice received during 7 d a balanced conventional diet (BD) or BD supplemented with Lr (108 cells/mouse/d) (BD+Lr group).On day 8, these groups, the well-nourished (WNC) and malnourished (MNC) controls, were infected nasally with Sp (105 cells/mouse). We analyzed in broncho-alveolar lavages (BAL), blood and bone marrow (BM): a) the total and differential cell counts, b) activity of phagocytes, c) Gr-1 and CD34 expression with flow cytometry, and d) the levels of IL-6 and TNF-α in BAL and serum. Before the challenge, we observed that malnutrition induced a decrease of the population of granulocytes in both blood and BM (FSC vs SSC), being the mature myeloid cells (Gr-1high) the main population responsible for this effect. In addition, MNC mice showed lower neutrophils peroxidase activity than WNC group. The treatment with BD+Lr was able to normalize the number of blood and BM Gr-1high cells and improved neutrophils peroxidase activity. Challenge with the pathogen increase the number of respiratory phagocytes in all experimental groups, however, MNC showed impaired respiratory phagocytes activity and neutrophils recruitment into the lungs. BD+Lr mice showed values of neutrophils in BAL similar to those of WNC mice and the activation of phagocytic cells was significantly higher when compared with all the experimental groups. Infection increase the number of blood and BM Gr-1 cells in all groups; however, in MNC and BD it was observed an increase of BM Gr-1high cells, while in WNC and BD+Lr there was an increase of BM Gr-1low cells. The challenge with the respiratory pathogen increased the number of BM immature myeloid cells (Gr-1+/CD34+) in all experimental groups; however, the levels of these cells in the MNC and BD groups were lower than the other groups. The DB+Lr treatment induced the normalization of the cytokine profiles studied,both before and during infection with Sp. Therefore, the oral administration of Lr was able to improve the innate immune response against Sp in malnourished immunocompromised mice. This effect would be related to the ability of Lr to induce an early recovery of myeloid cells in blood and BM.