B cells are not essential for Lactobacillus-mediated protection against lethal pneumovirus infection

• Published in: The Journal of immunology (1950) 2014-06, Vol.192 (11), p.5265-5272
• Main Authors: Percopo, Caroline M, Dyer, Kimberly D, Garcia-Crespo, Katia E, Gabryszewski, Stanislaw J, Shaffer, 3rd, Arthur L, Domachowske, Joseph B, Rosenberg, Helene F
• Format: Article
• Language: English
• Subjects: Animals; Antibodies, Bacterial - genetics; Antibodies, Bacterial - immunology; B-Lymphocytes - immunology; Cytokines - genetics; Cytokines - immunology; Lactobacillus - immunology; Lung - immunology; Lung - pathology; Lung - virology; Mice; Mice, Inbred BALB C; Pneumovirus - genetics; Pneumovirus - immunology; Pneumovirus Infections - genetics; Pneumovirus Infections - immunology; Pneumovirus Infections - pathology; Respiratory Mucosa - immunology; Respiratory Mucosa - pathology; Respiratory Mucosa - virology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.1400087

We have shown previously that priming of respiratory mucosa with live Lactobacillus species promotes robust and prolonged survival from an otherwise lethal infection with pneumonia virus of mice, a property known as heterologous immunity. Lactobacillus priming results in a moderate reduction in virus recovery and a dramatic reduction in virus-induced proinflammatory cytokine production; the precise mechanisms underlying these findings remain to be elucidated. Because B cells have been shown to promote heterologous immunity against respiratory virus pathogens under similar conditions, in this study we explore the role of B cells in Lactobacillus-mediated protection against acute pneumovirus infection. We found that Lactobacillus-primed mice feature elevated levels of airway Igs IgG, IgA, and IgM and lung tissues with dense, B cell (B220(+))-enriched peribronchial and perivascular infiltrates with germinal centers consistent with descriptions of BALT. No B cells were detected in lung tissue of Lactobacillus-primed B cell deficient μMT mice or Jh mice, and Lactobacillus-primed μMT mice had no characteristic infiltrates or airway Igs. Nonetheless, we observed diminished virus recovery and profound suppression of virus-induced proinflammatory cytokines CCL2, IFN-γ, and CXCL10 in both wild-type and Lactobacillus-primed μMT mice. Furthermore, Lactobacillus plantarum-primed, B cell-deficient μMT and Jh mice were fully protected from an otherwise lethal pneumonia virus of mice infection, as were their respective wild-types. We conclude that B cells are dispensable for Lactobacillus-mediated heterologous immunity and were not crucial for promoting survival in response to an otherwise lethal pneumovirus infection.