This is particularly true for innate immunity in cases including acute melioidosis where excessive acti vation of inflammatory genes is commonly associated with septic shock. We did not see up regulation in the levels of anti inflammatory signals and TLR negative regulators at 24 hpi, suggesting that the failure to suppress inflamma tion at this early time point contributes to the excessive inflammation and acute nature of this infection. Neverthe less, at 42 hpi, a significant decrease in expression of these potent inflammatory genes was observed and may actually benefit the intracellular pathogen. However, the underlying factors that contribute to the decrease in expression of these inflammatory genes remain unclear as the production of anti inflammatory cytokines was relatively insufficient to counter the high pro inflammatory responses at 24 hpi.
Acute forms of melioidosis that lead to sepsis, multi ple organ failure and death are thought to result from an uncontrolled inflammatory reaction that ultimately leads to excessive inflammation and eventually tissue injury Inhibitors,Modulators,Libraries in Inhibitors,Modulators,Libraries the B. pseudomallei infected host. Activation of proteasomal degradation following tissue injury suggests the production of immunological waste products such as apoptotic cells and immune complexes in the B. pseu domallei infected host. This could be attributed to a failure in activating the complement system in AV-951 time, leading to the accumulation of waste and uncontrolled spread of the pathogen. The low levels of the potent anaphyatoxin C5a observed in our study most likely inhibit the downstream terminal complement pathway.
Inhibitors,Modulators,Libraries Inhibitors,Modulators,Libraries As a result, deficient rapid clearance of apop totic cells resulting in extracellular disintegration of the cell and release of intracellular components triggers inflammatory cytokine production and contributes to breaking tolerance by facilitating an immune response to intracellular constituents. This is the first evi dence of failure of the downstream complement path way in acute melioidosis. The B. pseudomallei infected host also over express many cell death related genes which suggests that the host initiates various cell death defence responses and disrupts cell regulation to limit a favourable intracellular niche for the pathogens. Elevation of caspase 2, 3, 7 and 8, as well as the BCL 2 family protein BID and TNF receptor superfamily suggests that the host triggers apoptosis signalling via the death receptor mediated pathway.
In addition, we saw an up regulation of inflammasome related genes not pre viously reported in the B. pseudomallei infected host. B. pseudomallei virulence factors such as type three secre tion factors, flagellin and channel forming toxins like hemolysin could trigger inflammasome dependent caspase 1 activation. B. pseudomallei is known to interfere with iNOS expression in RAW264. 7 macrophages and abrogate nitric oxide production during the early stages of infection.