Cellular Activation Induced by BCG Is a PTK-Dependent Event

Mycobacterium bovis BCG but not Mycobacterium leprae induces TNF-alpha secretion in human monocytic THP-1 cells

“…Among these responses there is an extensive reorganization of the cytoskeleton resulting in morphological changes, and the secretion of cytokines into the medium. Although this interference in host cell metabolism could represent a central feature of their pathogenesis, these events are poorly understood in mononuclear phagocytes infected with mycobacteria and have only recently received attention by a few investigators (Kusner et al 1996, Mendez-Samperio et al 1996, Olivier et al 1998, Malik et al 2000. In the present study, we have employed an in vitro model to investigate the early molecular events evoked by mycobacteria after their phagocytosis by human monocytes.…”

Activation of ERK1/2 and TNF-α production are mediated by calcium/calmodulin, and PKA signaling pathways during Mycobacterium bovis infection

“…22 To investigate the involvement of PKA in M. bovis BCG-induced ERK1/2 phosphorylation, experiments were performed to analyse the effect of the PKA-specific inhibitor H-89 on ERK1/2 activation. Prior to infection, human monocytes were incubated 1 h with H-89, and ERK1/2 phosphorylation was determined by Western blotting.…”

Calcium signalling during cell interactions with bacterial pathogens

“…During M. tuberculosis infection of airway epithelial cells, IL-8 expression appears to occur following TNF-a release. In monocytes/ macrophages, there are conflicting reports as to whether IL-8 induction occurs as a primary response to bacterial challenge (Barnes et al, 1992;Méndez-Samperio et al, 1996;Méndez-Samperio et al, 2001). IL-8 induction was observed in a bacterial dose-dependent manner at significant higher levels than those observed with bacterial LPS and was insensitive to the LPS inhibitor polymyxin B, suggesting that M. tuberculosis determinants other than LPS were responsible for NF-jB induction.…”