Proapoptotic activity of Bordetella bronchiseptica lipopolysaccharide in epithelial and immune host cells

SISTI FEDERICO; FERNÁNDEZ JULIETA; BOTTERO DANIELA; GAILLARD MARÍA EMILIA; GRAIEB AUGUSTO; HOZBOR DANIELA

Iguazú, Argentina

Congreso; XL Reunion De La Sociedad Argentina De Investigación Bioquímica Y Biología Molecular; 2004

Bordetella bronchiseptica is a gram-negative bacteria that cause respiratory tract infections characterized by a chronic period. In this period the bacteria presents some phenotypic variations that includes the lipopolysaccharide (LPS) structure. While in the first acute period the LPS has a smooth structure, in the chronic period a deep rough LPS is present. This change in the LPS structure could be essential for bacterial survival within the host and, more specifically within the host cell. Taking into account that the LPS from other Gram-negative pathogens are involved in apoptotic induction mechanisms in different host cells, we decided to analyze if those different LPS forms of B. bronchiseptica were able to induce apoptosis in the host cells that were in close contact with the bacteria during the infection. For this purpose we used the smooth and deep rough forms of LPS obtained from either B. bronchiseptica isolated from different stage of human infection or B. bronchiseptica collection strain and its deep rough mutant constructed by us. In epithelial cells (A549) all the LPS forms studied induce apoptosis (3 to 5 times higher than the control) but not necrosis. In neutrophils we observed that smooth as well as the deep rough LPS forms induce apoptosis (6 times higher than the control) and necrosis. An interesting result was obtained when monocytes cells were used. In this case we observed that the deep rough LPS form was the unique structure of LPS that induced apoptosis suggesting that this form is critical for the persistence of the bacteria within the host cell.