Browsing by Author "Collins, Madison M."

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The Accessory Gene saeP of the SaeR/S Two-Component Gene Regulatory System Impacts Staphylococcus aureus Virulence During Neutrophil Interaction
(2020-04) Collins, Madison M.; Behera, Ranjan K.; Pallister, Kyler B.; Evans, Tyler J.; Burroughs, Owen; Flack, Caralyn; Guerra, Fermin E.; Pullman, Willis; Cone, Brock; Dankoff, Jennifer G.; Nygaard, Tyler K.; Brinsmade, Shaun R.; Voyich, Jovanka M.
Staphylococcus aureus (S. aureus) causes a range of diseases ranging from superficial skin and soft-tissue infections to invasive and life-threatening conditions (Klevens et al., 2007; Kobayashi et al., 2015). S. aureus utilizes the Sae sensory system to adapt to neutrophil challenge. Although the roles of the SaeR response regulator and its cognate sensor kinase SaeS have been demonstrated to be critical for surviving neutrophil interaction and for causing infection, the roles for the accessory proteins SaeP and SaeQ remain incompletely defined. To characterize the functional role of these proteins during innate immune interaction, we generated isogenic deletion mutants lacking these accessory genes in USA300 (USA300ΔsaeP and USA300ΔsaeQ). S. aureus survival was increased following phagocytosis of USA300ΔsaeP compared to USA300 by neutrophils. Additionally, secreted extracellular proteins produced by USA300ΔsaeP cells caused significantly more plasma membrane damage to human neutrophils than extracellular proteins produced by USA300 cells. Deletion of saeQ resulted in a similar phenotype, but effects did not reach significance during neutrophil interaction. The enhanced cytotoxicity of USA300ΔsaeP cells toward human neutrophils correlated with an increased expression of bi-component leukocidins known to target these immune cells. A saeP and saeQ double mutant (USA300ΔsaePQ) showed a significant increase in survival following neutrophil phagocytosis that was comparable to the USA300ΔsaeP single mutant and increased the virulence of USA300 during murine bacteremia. These data provide evidence that SaeP modulates the Sae-mediated response of S. aureus against human neutrophils and suggest that saeP and saeQ together impact pathogenesis in vivo.
Differential regulation of CD103 (alphaE integrin) expression in human dendritic cells by retinoic acid and Toll-like receptor ligands
(2017-05) Roe, Mandi M.; Swain, Steve; Sebrell, T. Andrew; Sewell, Marisa A.; Collins, Madison M.; Perrino, Brian A.; Smith, Phillip D.; Smythies, Lesley E.; Bimczok, Diane
CD103 (alphaE integrin) is an important dendritic cell (DC) marker that characterizes functionally distinct DC subsets in mice and humans. However, the mechanism by which CD103 expression is regulated in human DCs and the role of CD103 for DC function are not very well understood. Here, we show that retinoic acid (RA) treatment of human monocyte-derived DCs (MoDCs) increased the ability of the DCs to synthesize RA and induced MoDC expression of CD103 and beta7 at the mRNA and protein level. In contrast, RA was unable to induce the expression of CD103 in primary human DCs isolated from the gastric mucosa. Inhibition of TGF-beta signaling in MoDCs down-regulated RA-induced CD103 expression, indicating that TGF-beta-dependent pathways contribute to the induction of CD103. Conversely, when RA-treated MoDCs were stimulated with live Helicobacter pylori, commensal bacteria, LPS, or a TLR2 agonist, the RA-induced up-regulation of CD103 and beta7 integrin expression was completely abrogated. To determine whether CD103 expression impacts DC priming of CD4+ T cells, we next investigated the ability of CD103+ and CD103â”€ DCs to induce mucosal homing and T cell proliferation. Surprisingly, RA treatment of DCs enhanced both alpha4beta7 expression and proliferation in cocultured T cells, but no difference was seen between RA-treated CD103+ and CD103â”€ DCs. In summary, our data demonstrate that RA, bacterial products, and the tissue environment all contribute to the regulation of CD103 on human DCs and that DC induction of mucosal homing in T cells is RA dependent but not CD103 dependent.