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

LAMBERTI Y; CAFIERO, HILARIO; GORGOJO J; RODRIGUEZ ME

BS AS

Congreso; LXIII Reunión Anual de Sociedad Argentina de Inmunología; 2015

Whooping cough is an acute respiratory disease causedby B. pertussis (Bp). Through the BvgAS, a two componentsystem, this pathogen regulates the expression of virulence factors,such as pertussis (Ptx) and adenylate cyclase (ACT) toxins, withknown immunomodulatory activities. The BvgAS system alsoregulates 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 ofmodulating the proinflamatory response. The pulmonaryepithelium is considered an important source cytokines duringinfection, however, its response to Bp interaction was poorlycharacterized. We here examined the capacity of Bp wild type, anavirulent Bvg mutant (BpΔBvgA), and mutant strains deficient inPtx (BpΔptx), ACT (BpΔACT) and TTSS secretion systemapparatus (BpΔbscN), to elicit an inflammatory response uponhuman bronchial (16HBE14o-) and alveolar (A549) epithelial celllines infection. A low multiplicity of infection (1 bacteria/cell) anda short infection period (6 h) was used to prevent the cytotoxiceffects elicited by ACT on epithelial cells. The secretion of IL-8and IL-6 by A549 cells and 16HBE14o- cells infected with Bpwt,BpΔptx or BpΔcya strains was similar to that observed in noninfectedcontrols. However, IL-6 secretion of cells infected withΔbscN and ΔBvgA strains increased 2 to 3 fold, respectively(p