Leishmania donovani inhibits inflammasome-dependent macrophage activation by exploiting the negative regulatory proteins A20 and UCP2 [Research]

In visceral leishmaniasis, we found that the antileishmanial drug Amp B produces a higher level of IL-1β over the infected control. Moreover, administering anti-IL-1β antibody to infected Amp B–treated mice showed significantly less parasite clearance. Investigation revealed that Leishmania inhibits stimuli-induced expression of a multiprotein signaling platform, NLRP3 inflammasome, which in turn inhibits caspase-1 activation mediated maturation of IL-1β from its pro form. Attenuation of NLRP3 and pro-IL-1β in infection was found to result from decreased NF-B activity. Transfecting infected cells with constitutively active NF-B plasmid increased NLRP3 and pro-IL-1β expression but did not increase mature IL-1β, suggesting that IL-1β maturation requires a second signal, which was found to be reactive oxygen species (ROS). Decreased NF-B was attributed to increased expression of A20, a negative regulator of NF-B signaling. Silencing A20 in infected cells restored NLRP3 and pro-IL-1β expression, but also increased matured IL-1β, implying an NF-B-independent A20-modulated IL-1β maturation. Macrophage ROS is primarily regulated by mitochondrial uncoupling protein 2 (UCP2), and UCP2-silenced infected cells showed an increased IL-1β level. Short hairpin RNA-mediated knockdown of A20 and UCP2 in infected mice independently documented decreased liver and spleen parasite burden and increased IL-1β production. These result...
Source: FASEB Journal - Category: Biology Authors: Tags: Research Source Type: research