Lactobacillus rhamnosus CRL 1505 improves respiratory and systemic innate immunity in malnourished mice

HERRERA MATÍAS; SALVA SUSANA; VILLENA JULIO; BARBIERI NATALIA; ALVAREZ SUSANA

San Miguel de Tucumán. Tucumán. Argentina

Simposio; III International Symposium on Lactic Acid Bacteria. II Argentinean LAB Net Meeting; 2009

CERELA-CONICET

We demonstrated previously that the oral administration of Lactobacillus rhamnosus CRL 1505 (Lr) to malnourished mice, was capable of improving resistance against Streptococcus pneumoniae. In this work we studied the effect of Lr on the innate immune response against the respiratory pathogen. Weaned mice were malnourished after consuming a protein-free diet (PFD) for 21 days. Malnourished mice were fed a balanced conventional diet (BD) for 7 days (BD group) or BD for 7 days with supplemental Lr (108 cells/mouse/day) from day 3 to day 7 (BD+Lr group). The malnourished control group (MNC) received PFD while the well-nourished control (WNC) mice consumed BD. At the end of treatments the different groups of mice were infected nasally with S. pneumoniae (105 cells/mouse). We analyzed in bronco-alveolar lavages (BAL), blood and bone marrow (BM): a) the total and differential cell counts, b) activity of phagocytes, and c) Gr-1 and CD34 expression with flow cytometry. 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 (Blood neutrophils: WNC=0.9±0.07 109cells/l; MNC=0.6±0.08; BD=0.7±0.03; BD+Lr=0.9±0.07; BM Gr-1+ cells: WNC=21.8±2.1 106 cells/femur; MNC=13.5±1.8; BD=14.9±1.0; BD+Lr=21.2±1.6). 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 (p