Immunobiotic nasal priming can acelerate the recovery of nasopharynx-associated lymphoid tissue in malnoureished mice

Abstract

Malnutrition induces atrophy of mucosa-associated-lymphoid-tissue. However, little is known about the effect of malnutrition on the nasopharynx-associated-lymphoid-tissue (NALT). In addition, immunobiotic lactic acid bacteria and its postbiotics became an interesting and non-invasive alternative for the recovery of the respiratory immune response in malnourished hosts. We demonstrated that Lactobacillus rhamnosus CRL1505 peptidoglycan (PG05) increases the infection resistance against Streptococcus pneumoniae (Sp) and improves innate immune response in immunocompromised- malnourished mice. The aim of this work was to study the effect of nasal administration of L. rhamnosus CRL1505 (Lr05) and PG05 on the recovery of NALT in malnourished mice. Weaned mice were malnourished with a protein-free diet (PFD) for 21d. Malnourished mice received a balanced conventional diet (BCD) during 7d (BCD group) or BCD with nasal supplementation with L. rhamnosus CRL1505 (108 cells/mouse/day) or PG05 (8μg/mouse/day) during the last 2 days of treatment (BCD+Lr or BCD+PG groups). Malnourished control mice (MC) received PFD while the well-nourished control group (WC) consumed BCD. Histological studies and flow cytometry studies were carried out on NALT to study the impact on B and T cells, dendritic cells, macrophages and myeloid cells. Protein- malnutrition significantly reduced the number of total cells and the different cell populations. These results were related to a NALT atrophy in the malnourished mice. BCD treatment was not able to normalize these parameters. However, the BCD+Lr and BDC+PG groups showed histological characteristics similar to the WC group, and normal numbers of NALT B, T, dendritic cells and neutrophils. These results highlight the importance of NALT as a target for postbiotics and immunobiotics administration to improve respiratory immunity in immunocompromised malnourished hosts.