Tessa Bergsbaken

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Eukaryotic cells can initiate several distinct programmes of self-destruction, and the nature of the cell death process (non-inflammatory or proinflammatory) instructs responses of neighbouring cells, which in turn dictates important systemic physiological outcomes. Pyroptosis, or caspase 1-dependent cell death, is inherently inflammatory, is triggered by(More)
Caspase-1 cleaves the inactive IL-1beta and IL-18 precursors into active inflammatory cytokines. In Salmonella-infected macrophages, caspase-1 also mediates a pathway of proinflammatory programmed cell death termed "pyroptosis." We demonstrate active caspase-1 diffusely distributed in the cytoplasm and localized in discrete foci within macrophages(More)
Infection of macrophages by Yersinia species results in YopJ-dependent apoptosis, and naïve macrophages are highly susceptible to this form of cell death. Previous studies have demonstrated that macrophages activated with lipopolysaccharide (LPS) prior to infection are resistant to YopJ-dependent cell death; we found this simultaneously renders macrophages(More)
We report that oral infection with Yersinia pseudotuberculosis results in the development of two distinct populations of pathogen-specific CD8(+) tissue-resident memory T cells (TRM cells) in the lamina propria. CD103(-) T cells did not require transforming growth factor-β (TGF-β) signaling but were true resident memory cells. Unlike CD103(+)CD8(+) T cells,(More)
FliC is a natural antigen recognized by the innate and adaptive immune systems during Salmonella infection in mice and humans; however, the regulatory mechanisms governing its expression in vivo are incompletely understood. Here, we use flow cytometry to quantify fliC gene expression in single bacteria. In vitro, fliC transcription was not uniformly(More)
Membrane vesicle (MV) release remains undefined, despite its conservation among replicating Gram-negative bacteria both in vitro and in vivo. Proteins identified in Salmonella MVs, derived from the envelope, control MV production via specific defined domains that promote outer membrane protein-peptidoglycan (OM-PG) and OM protein-inner membrane protein(More)
The complement system is an essential component of host defense against pathogens. Previous research in our laboratory identified StcE, a metalloprotease secreted by Escherichia coli O157:H7 that cleaves the serpin C1 esterase inhibitor (C1-INH), a major regulator of the classical complement cascade. Analyses of StcE-treated C1-INH activity revealed that(More)
Yersinia pestis, the etiological agent of plague, is one of the most deadly pathogens on our planet. This organism shares important attributes with its ancestral progenitor, Yersinia pseudotuberculosis, including a 70-kb virulence plasmid, lymphotropism during growth in the mammalian host, and killing of host macrophages. Infections with both organisms are(More)
Activation of caspase-1 leads to pyroptosis, a program of cell death characterized by cell lysis and inflammatory cytokine release. Caspase-1 activation triggered by multiple nucleotide-binding oligomerization domain-like receptors (NLRs; NLRC4, NLRP1b, or NLRP3) leads to loss of lysosomes via their fusion with the cell surface, or lysosome exocytosis.(More)
Escherichia coli O157:H7 is a source of foodborne illness, causing diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome. E. coli O157:H7 secretes, via the etp type II secretion system, a metalloprotease, StcE, that specifically cleaves the serpin C1 esterase inhibitor. We determined by hybridization techniques the prevalence of stcE and etpD, a type(More)