Cholesterol domains are involved in B. pertussis attachment to epithelial respiratory cells

YANINA LAMBERTI; MARIA LAURA PEREZ VIDAKOVICS; MARIA EUGENIA RODRIGUEZ

Paris, Francia

Simposio; 8th International Symposium: Saga of the Genus Bordetella; 2006

Instituto Pasteur de Paris

The nature of bacterial attachment to host cells is often the key event in the outcome of the infection. B. pertussis (Bp) adhesins, like Filamentous Hemagglutinin (FHA) or Adenylate Cyclase (ACT), recently found critical for the binding activity of FHA, are expressed only in the virulent phase. However, the avirulent phase of Bp proved also able to attach to respiratory cells. We here investigated the role of the cholesterol, a molecule involved in other infectious processes, in the interaction of Bp with the host cells. Human respiratory cells (A549) treated with and without metyl-b-cyclodextrin, a cholesterol sequestering drug, were incubated with virulent and avirulent Bp wild type strain or isogenic mutants deficient of either FHA or ACT. The synthesis of cholesterol de novo was inhibited by the addition of lovastatin. The results showed that the lack of cholesterol led to a significant decrease in bacterial attachment (about 75%) which proved independent of the virulent state or the presence of FHA or ACT. Treatment of A549 cells with cholesterol binding drugs like nystatin or filipin rendered similar results. Attachment studies with growing concentrations of cholesterol confirmed its involvement in the bacterial binding. Moreover, internalization and survival studies showed a relevant role of cholesterol in the intracellular trafficking. Whether this mechanism of attachment is relevant during transmission, when bacteria is not yet expressing FHA, or at later stages in pathogenesis remains to be investigated.