Biology subjects

Vance, R. E.

Publications and source records attributed to Vance, R. E..

21 records · Page 2Linked to original sources

bioRxiv2019

Inflammasome-mediated antagonism of type I interferon enhances Rickettsia pathogenesis

Inflammasomes and interferons constitute two critical arms of innate immunity. Most facultative bacterial pathogens that inhabit the host cell cytosol avoid activating inflammasomes and are often resistant to killing by type I interferon (IFN-I). We report that the human pathogen Rickettsia parkeri, an obligate intracellular pathogen that resides in the cytosol, is sensitive to IFN-I. The mechanism of IFN-I-dependent restriction requires the transcription factor IRF5, which upregulates anti-rickettsial factors including guanylate-binding proteins and iNOS. However, R. parkeri curtails cGAS-dependent IFN-I production by causing caspase-11-dependent pyroptosis. In vivo, inflammasome activation antagonizes IFN-I production, enhancing R. parkeri abundance in the spleen. Mice lacking either IFN-I or IFN-{gamma} signaling are resistant to infection, but mice lacking both rapidly succumb, revealing that both interferons are required to control R. parkeri. This study illuminates how an obligate cytosolic pathogen exploits the intrinsic trade-off between cell death and cytokine production to escape killing by innate immunity.\n\nHighlightsO_LIRickettsia killed by GBPs activates caspase-11 and GSDMD, promoting pyroptosis\nC_LIO_LIRickettsia exploits pyroptosis to avoid cGAS-dependent type I interferon\nC_LIO_LIIRF5, GBPs, and iNOS contribute to controlling R. parkeri infection\nC_LIO_LIIfnar-/-Ifngr-/- mice succumb to infection, uncovering a mouse model to study R. parkeri\nC_LI

immunology↗

bioRxiv2018

Interleukin-1 receptor antagonist mediates type I interferon-driven susceptibility to Mycobacterium tuberculosis

The bacterium Mycobacterium tuberculosis (Mtb) causes tuberculosis (TB) and is responsible for more human mortality than any other single pathogen1. Although ~1.7 billion people are infected with Mtb2, most infections are asymptomatic. Progression to active disease occurs in ~10% of infected individuals and is predicted by an elevated type I interferon (IFN) response3-8. Type I IFNs are vital for antiviral immunity, but whether or how they mediate susceptibility to Mtb has been difficult to study, in part because the standard C57BL/6 (B6) mouse model does not recapitulate the IFN-driven disease that appears to occur in humans3-5,8. Here we examined B6. Sst1S congenic mice that carry the C3H \"sensitive\" allele of the Sst1 locus that renders them highly susceptible to Mtb infections9,10. We found that B6.Sst1S mice exhibit markedly increased type I IFN signaling, and that type I IFNs were required for the enhanced susceptibility of B6. Sst1S mice to Mtb. Type I IFNs affect the expression of hundreds of genes, several of which have previously been implicated in susceptibility to bacterial infections11,12. Nevertheless, we found that heterozygous deficiency in just a single IFN target gene, IL-1 receptor antagonist (IL-1Ra), is sufficient to reverse IFN-driven susceptibility to Mtb. As even a partial reduction in IL-1Ra levels led to significant protection, we hypothesized that IL-1Ra may be a plausible target for host-directed anti-TB therapy. Indeed, antibody-mediated neutralization of IL-1Ra provided therapeutic benefit to Mtb-infected B6. Sst1S mice. Our results illustrate how the diversity of inbred mouse strains can be exploited to better model human TB, and demonstrate that IL-1Ra is an important mediator of type I IFN-driven susceptibility to Mtb infections in vivo.

immunology↗

bioRxiv2018

Functional degradation: a mechanism of NLRP1 inflammasome activation by diverse pathogen enzymes

Inflammasomes are multi-protein platforms that initiate innate immunity by recruitment and activation of Caspase-1. The NLRP1B inflammasome is activated upon direct cleavage by the anthrax lethal toxin protease. However, the mechanism by which cleavage results in NLRP1B activation is unknown. Here we find that cleavage results in proteasome-mediated degradation of the N-terminal domains of NLRP1B, liberating a C-terminal fragment that is a potent Caspase-1 activator. Proteasome-mediated degradation of NLRP1B is both necessary and sufficient for NLRP1B activation. Consistent with our new functional degradation model, we identify IpaH7.8, a Shigella flexneri ubiquitin ligase secreted effector, as an enzyme that induces NLRP1B degradation and activation. Our results provide a unified mechanism for NLRP1B activation by diverse pathogen-encoded enzymatic activities.\n\nOne Sentence SummaryTwo distinct pathogen enzymes activate an innate immune sensor called NLRP1B by a mechanism that requires proteasome-mediated degradation of NLRP1B.

immunology↗