Bordetella parapertussis ADENYLATE CYCLASE TOXIN MODULATES THE HOST DEFENSE AND INFLAMMATORY RESPONSE ULTIMATELY PROMOTING BACTERIAL INTRACELLULAR SURVIVAL

CARRICA M; GORGOJO JUAN; VALDEZ HUGO; RODRÍGUEZ M E

Buenos Aires

Congreso; LXVIII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI); 2020

SOCIEDAD ARGENTINA DE INMUNOLOGÍA

B. pertussis (Bp) and B. parapertussis (Bpp) are the etiologic agents of whooping cough in humans, which is a re-emerging infectious disease. We have previously found that both species survive and even replicate inside human macrophages, indicating that these cells might serve as a niche for persistence. We further found that pertussis toxin and adenylate cyclase (CyaA) are involved in the intracellular survival of Bp. Bpp expresses solely CyaA, which is the main toxin of this species. Although the genes encoding this toxin in Bp and Bpp display limited polymorphism, there are studies showing different post-translational modifications that eventually lead to less citotoxic Bpp-CyaA, as observed in certain host cells. The aim of this work was to investigate the effect of Bpp-CyaA in macrophage defense response and its eventual role in the non-bactericidal interaction of Bpp with macrophages. To this end, we constructed a Bpp deletion mutant defective in CyaA. The human monocyte cell line (THP-1) was differentiated into macrophages and further infected with the mutant or the parental strain. By means of specific markers and confocal microscopy for bacterial intracellular trafficking studies and antibiotic protection assays, we found that Bpp-CyaA is involved in the early stages of macrophage infection, affecting phagocytosis and lysosomal maturation promoting intracellular survival. Accordingly, by qRT-PCR assays performed at 3 h p.i., we demonstrated that Bpp-CyaA down-regulates the transcription of genes encoding antimicrobial peptides, proteins involved in enzymatic or oxidative defense mechanisms, and the pro-inflammatory cytokine TNF-α, while it up-regulates the transcription of anti-inflammatory cytokine IL-10. All the data were statistically significant with p