IMMUNOBIOTIC BACTERIA PEPTIDOGLYCAN PROTECTS INFANT MICE AGAINST TOLL-LIKE RECEPTOR 3-MEDIATED LUNG INFLAMMATORY DAMAGE AND SECONDARY PNEUMOCOCCAL INFECTION

PATRICIA CLUA; HORTENSIA ZELAYA; ASUKA TADA; GABRIELA MARRANZINO; SUSANA SALVA; SUSANA ALVAREZ; HARUKI KITAZAWA; JULIO VILLENA

Buenos Aires. Argentina

Congreso; LXIII Reunión Científica Anual de la Sociedad Argentina de Inmunología (SAI); 2015

Sociedad Argentina de Inmunología

Background: nasally administered Lactobacillus rhamnosus CRL1505 (Lr05) improves the outcome of respiratory virus infection and beneficially modulates TLR3-mediated inflammation. The capacity of Lr05 peptidoglycan (Pg05) to reduce viral inflammatory damage and decrease susceptibility to secondary pneumococcal infection was investigated.Methods: an experimental model of lung inflammation based on the nasal administration of poly(I:C) was used. Pg05 were nasally administered to different groups of infant mice for 2 days and then, mice received three doses of poly(I:C) with 24 hours rest period between each administration. Pneumococcal infection was performed at different times after the last poly(I:C) challenge. Lung tissue damage and respiratory immune response were studied.Results: poly(I:C) administration induced a marked inflammatory-mediated impairment of lung function and, significantly increased the susceptibility of infant mice to secondary pneumococcal infection. Treatment of infant mice with Pg05 reduced lung injuries and TNF-a, IL-6, IL-8 and MCP-1 respiratory levels after poly(I:C) challenge. Pg05 also increased lung and serum IL-10, lung IFN-γ levels and the number of respiratory CD3+CD4+IFN-γ+ T cells, and both CD103+MHC-II+ and CD11bhighMHC-II+ respiratory DCs after poly(I:C) challenge. Pg05 was also capable of reducing pneumococcal cell counts in lung and blood, as well as lung tissue damage associated to the infection.Conclusions: nasal administration of L. rhamnosus CRL1505 peptidoglycan is able to beneficially modulate the immune response triggered by TLR3 activation in the respiratory tract. Moreover, this is the first demonstration of the capacity of a peptidoglycan of immunobiotic bacteria to improve the outcome of secondary pneumococcal infection of infant mice.