Bordetella pertussis type three secretion system inhibits interleukin-6 secretion by pulmonary epithelial cells

LAMBERTI, YANINA; CAFIERO, JUAN HILARIO; GORGOJO, JUAN PABLO; RODRIGUEZ, MARÍA EUGENIA

CABA (Bs. As.)

Congreso; IV LASID Meeting, LXIII Argentinen Society for Immunology Meeting, and II French Society for Immunology Meeting; 2015

LASID - FAIC -SAI

Whooping cough is an acute respiratory disease caused by B. pertussis (Bp). Through the BvgAS, a two component system, this pathogen regulates the expression of virulence factors, such as pertussis (Ptx) and adenylate cyclase (ACT) toxins, with known immunomodulatory activities. The BvgAS system also regulates a recently described functional type III secretion system (TTSS) whose role in Bp pathogenesis remains to be elucidated. Studies in murine models suggests that Ptx is capable of modulating the proinflamatory response. The pulmonary epithelium is considered an important source cytokines during infection, however, its response to Bp interaction was poorly characterized. We here examined the capacity of Bp wild type, an avirulent Bvg mutant (BpΔBvgA), and mutant strains deficient in Ptx (BpΔptx), ACT (BpΔACT) and TTSS secretion system apparatus (BpΔbscN), to elicit an inflammatory response upon human bronchial (16HBE14o-) and alveolar (A549) epithelial cell lines infection. A low multiplicity of infection (1 bacteria/cell) and a short infection period (6 h) was used to prevent the cytotoxic effects elicited by ACT on epithelial cells. The secretion of IL-8 and IL-6 by A549 cells and 16HBE14o- cells infected with Bpwt, BpΔptx or BpΔcya strains was similar to that observed in non-infected controls. However, IL-6 secretion of cells infected with ΔbscN and ΔBvgA strains increased 2 to 3 fold, respectively (p