PROTECTIVE EFFECT OF PROBIOTIC Lactobacillus rhmanosus AGAINST RESPIRATORY SYNCYTIAL VIRUS INFECTION IN YOUNG MICE

SALVA, SUSANA; CHIBA, ERIKA; VISOZO-PINTO, MARÍA GUADALUPE; KITASAWA, HARUKI; ALVAREZ, SUSANA; VILLENA, JULIO

Los Cocos, Córdoba

Congreso; LXI Reunión Anual de la Sociedad Argentina de Inmunología (SAI); 2013

Sociedad Argentina de Inmunología

The oral administration of Lactobacillus rhamnosus CRL1505 is capable of beneficially regulating the balance between pro- and anti-inflammatory mediators in the lungs of poly(I:C)-challenged mice, allowing an effective inflammatory response against the TLR3/RIG-I agonist but at the same time reducing tissue damage. In this work we investigated whether oral administration of the CRL1505 strain was able to improve resistance against respiratory syncytial virus (RSV) infection in infant mice and to evaluate the immunological mechanisms involved in the immunobiotic effect. L. rhamnosus CRL1505 or L. rhamnosus CRL1506 were orally administered to different groups of BALB/c mice of 3 weeks for 5 consecutive days at a dose of 108 cells/mouse/day. On day 6, these groups and untreated control mice were infected nasally with 2.4 x 106 PFU of RSV. Levels of protein, albumin and LDH and levels of IFN-β, TNF-α, IL-6, IFN-γ and IL-10 were studied in broncho-alveolar lavages (BAL). In addition, titers of RSV and expression of CD3, CD4, CD11b, CD11c, CD103, MHC II, IL-10 and INF-γ were studied in lung cells. We demonstrated that treatment with L. rhamnosus CRL1505 significantly reduce lung viral loads and tissue injuries after the challenge with RSV. Moreover, we showed that the protective effect achieved by the CRL1505 strain is related to its capacity to differentially modulate respiratory antiviral immune response. Our results shows that IFN-γ and IL-10 secreted in response to L. rhamnosus CRL1505 oral stimulation would modulate the pulmonary innate immune microenvironment conducting to the activation of CD103+ and CD11bhigh dendritic cells and the generation of CD3+CD4+IFN-γ+ Th1 cells with the consequent attenuation of the strong and damaging Th2 reactions associated with RSV challenge. Therefore, the modulation of the common mucosal immune system by immunobiotics could favor protective immunity against respiratory viral pathogens with a high attack rate in early infancy, such as RSV.