Bordetella pertussis modulates cathepsins expression during infection

OVIEDO, JUAN MARCOS; GORGOJO, JUAN; VALDEZ, HUGO; RODRIGUEZ, MARIA EUGENIA

Buenos Aires

Congreso; LXIII Argentinean Society for Immunology meeting (SAI), IV LASID meeting, and II French Society for Immunology Meeting; 2015

Sociedad Argentina de Inmunologia

We have previously demonstrated that Bordetella pertussis (Bp) is able to survive within human macrophages while down-regulating MHC-II expression. Antigen presentation involves the expression of cathepsins which are also potent microbicidal factors. In this study, we investigated the time course expression of cathepsins A, B, C, D, G, and S during the development of Bp intracellular infection. We used THP-1 differentiated into macrophages as a model, and samples were taken at 3, 24 and 48 hs post infection. First, RNA was extracted and used for qPCR, B2M was the housekeeping, and uninfected cells served as control. We observed that CTSA and CTSC increased soon after infection and remained high over time of infection, while CTSB, CTSD, CTSG and CTSS, showed an increase early after infection followed by a significant down-modulation at 48 h post infection as compared to the control group. CTSS and CTSD expression was confirmed at protein levels by flow cytometry. Pertussis toxin and adenylate cyclase were previously found to be involved in B. pertussis MHC-II down-regulation. We here used Bp mutants deficient in each toxin to further dissect their role in cathepsins´ regulation. Our results showed that none of the mutant strains could down regulate the cathepsins expression as the wild type did. The intracellular survival of these mutants decreased as compared with the wild type in Polymixin B protection assays. Taken together these data suggest that virulent Bp is able to manipulate macrophage bactericidal activity.