Virulence markers of LCR plasmid in Indian isolates of Yersinia pestis

Recombinant YopJ induces apoptotic cell death in macrophages through TLR2

Bacterial species evolved evasive maneuvers to bypass their recognition by the receptors primarily TLRs of the innate immune cells. We have reported that 3μg/ml of recombinant YopJ when provided extracellularly induced apoptosis in murine peritoneal macrophages in vitro. The present investigations demonstrate the role of TLR2 in apoptotic signals induced by rYopJ protein in murine peritoneal macrophages. The role of TLR2 in rYopJ induced macrophage apoptosis was shown by neutralization experiments and its co-immunoprecipitation with downstream molecule MyD88. The observed functional consequence of TLR2 neutralization were the inhibition of caspase-8 and caspase-3 activation, change in mitochondrial membrane potential (Δψm) and DNA fragmentation induced by rYopJ in macrophages. Further, rYopJ induced enhanced expression of IRAK-4, FADD, phosphorylation of IκB and p38 MAP kinase in macrophages. Pharmacological inhibitor of p38 MAP kinase and neutralization of TLR2 with neutralizing antibodies significantly inhibited the rYopJ induced caspases activation and DNA fragmentation, suggesting the possible involvement of TLR2 and p38 MAP kinase in rYopJ induced macrophages apoptosis.

Recombinant YopJ induces apoptosis in murine peritoneal macrophages in vitro: involvement of mitochondrial death pathway

Yersinia species during infection adhere to host immune cells primarily to macrophages and employ its secretary proteins known as Yersinia outer proteins to trigger death in infected cells. In the present study, it is shown that recombinant Yersinia outer protein J (rYopJ) could induce apoptosis in murine peritoneal macrophages in vitro as assessed by morphological features, internucleosomal DNA fragmentation, change in mitochondrial membrane potential (MMP) (Deltapsim), activation of caspases and Annexin V binding. rYopJ-induced cell death was dose and time dependent. Pre-treatment with broad-spectrum caspase inhibitor Z-VAD-FMK, caspase-3 inhibitor Ac-DEVD-CHO and caspase-8 inhibitor Z-IETD-FMK prevented the change in MMP and DNA fragmentation, suggesting caspase-dependent apoptosis of rYopJ-treated macrophages. Blocking the endocytosis by pre-treatment of cells with cytochalasin B did not prevent the rYopJ-induced macrophages apoptosis. The data further suggest that rYopJ-induced apoptosis is mediated by molecules upstream of caspase-8 and relay through mitochondrial pathway involving Bax, Bcl-2, activation of caspase-8 and caspase-3, Bid and polyadenosine diphosphate-ribose polymerase cleavage, cytochrome c release and DNA fragmentation.