ENHANCED IMMUNE RESPONSE TO PNEUMOCOCCAL INFECTION IN MALNOURISHED MICE NASALLY TREATED WITH HEAT KILLED Lactobacillus casei

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

S. M. de Tucumán. Tucumán. Argentina

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

CERELA-CONICET

This work analyzed whether the nasal administration of viable and non-viable Lactobacillus casei CRL 431 to immunocompromised mice was capable of increasing resistance against Streptococcus pneumoniae infection. 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 or BD for 7 days with viable or non-viable L. casei nasal treatments (109 cells/mouse/day) on days 6 and 7 (BD+LcV and BD+LcN, respectively). The malnourished control group (MNC) received PFD while the well-nourished control (WNC) mice consumed BD. In addition, malnourished mice replete only with BD were used as controls (BDC group). At the end of treatments the different groups of mice were infected nasally with S. pneumoniae (105 cells/mouse). The resistance against the pathogen and the innate and specific immune responses were studied during 10 days after the challenge. MNC mice showed greater lung colonization, more severe lung injuries, impaired leukocyte recruitment and reduced antibodies and cytokine production when compared with WNC mice. Administration of L. casei increased the resistance of malnourished mice to the infection. Both BD+LcV and BD+LcN treatments prevented the dissemination of the pathogen to the blood and induced its lung clearance (Lung bacterial cell count: WNC=3.2±0.12 log CFU/ g lung; MNC=5.91±0.11; BDC=4.4±0.11; BD+LcV