Non-viable immunobiotic Lactobacillus rhamnosus CRL1505 and its peptidoglycan improve systemic and respiratory innate immune response during recovery of immunocompromised-malnourished mice

KOLLING, YANINA; SALVA, SUSANA; VILLENA, JULIO; MARRANZINO, GABRIELA; ALVAREZ, SUSANA

INTERNATIONAL IMMUNOPHARMACOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 25 p. 474 - 484

1567-5769

The effect of nasally administered non-viable Lactobacillus rhamnosus CRL1505 and its cell wall and peptidoglycan on respiratory immunity in malnourished mice was studied. Five experimental groups were used.Weaned mice were malnourished with a protein-free diet for 21 days (MNC group). Aged-matched well-nourished mice consumed a balanced conventional diet (BCD) for 21 days and were used as a control group (WNC group). In addition, malnourished mice received BCD during 7 d (BCD group) or BCD with nasal non-viable L. rhamnosus CRL1505 (BCD + UV group) or its cell wall (BCD + CW group) or peptidoglycan (BCD + PG group) supplementation during last 2 days of the treatment. On day 8, the five groups were infected nasally with Streptococcus pneumoniae. Resistance against pneumococci was significantly reduced in MNC mice since the levels of lung and blood bacterial cell counts were higher than those detected in WNC mice. Repletion with BCD significantly reduced lung and blood bacterial cell counts when compared to MNC mice but the counts did not reach the levels of the WNC group. However, when malnourished mice were repleted with BCD + UV, BCD + CW or BCD + PG, pneumococci was not detected in lung or blood samples. Challenge with S. pneumoniae increased the numbers of neutrophils and macrophages and levels of TNF-alpha, IL-1beta, IL-6, and IL-10 in the respiratory tract; however the values were lower in MNC than in WNC mice. BCD treatment was not able to improve phagocytes´ numbers or the levels of respiratory cytokines in response to the infection. BCD+UV and BCD+PG groups showed values of phagocytes, IL-1beta and IL-6 that were similar to WNC mice, while TNF-alpha was significantly higher in those groups when compared to WNC mice. Moreover, BCD + UV and BCD + PG treatments improved levels of respiratory IL-10, reaching values that were superior to those observed in the WNC mice. The work demonstrates for the first time that non-viable probiotic bacteria or their cellular fractions could be an interesting alternative as mucosal immunomodulators, especially in immunocompromised hosts in which the use of live bacteria might be dangerous.