Brucella abortus induces apoptosis of human T lymphocytes

Autor: Paula Barrionuevo, Romina Scian, Juliana Cassataro, Lis N. Velásquez, Lorena M. Coria, M. Cruz Miraglia, Andrés E. Ibañez, Guillermo H. Giambartolomei, M. Victoria Delpino
Rok vydání: 2012
Předmět:
Zdroj: Microbes and Infection. 14:639-650
ISSN: 1286-4579
DOI: 10.1016/j.micinf.2012.02.004
Popis: Immune evasion is essential for Brucella abortus to survive in the face of robust adaptive CD4+ T cell response. We have previously demonstrated that B. abortus can indirectly inhibit CD4+ T cells by down-regulating MHC-II expression and antigen presentation on macrophages. However, whether B. abortus is able to directly interfere with T lymphocytes is not known. We report here that B. abortus induces apoptosis of human T lymphocytes, even though invasion of T lymphocytes was low and non-replicative. The ability of heat-killed B. abortus to reproduce the same phenomenon suggested that there was a bacterial structural component involved. We demonstrated that a prototypical B. abortus outer membrane lipoprotein (l-Omp19), but not its unlipidated form, induced T lymphocyte apoptosis. Moreover, a synthetic lipohexapeptide that mimics the structure of the protein lipid moiety also induced an increase in T lymphocyte cell death, indicating that the structural component implicated in the phenomenon could be any B. abortus lipoprotein. B. abortus-induced T lymphocyte apoptosis was dependent on the secretion of TNF-α since pre-incubation of T lymphocytes with anti-TNF-α mAb inhibited the apoptosis of the cells. Overall, these results represent a new mechanism whereby B. abortus by directly inhibiting T cell-mediated responses may evade adaptive immune responses.
Databáze: OpenAIRE
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