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SummaryIn human intestinal disease induced by Salmonella enterica serotype Typhimurium (S. typhimurium) transepithelial migration of polymorphonuclear leukocytes (PMNs) rapidly follows attachment of the bacteria to the epithelial apical membrane. Previously, we have shown that the S. typhimurium effector protein, SipA, plays a pivotal role in signalling epithelial cell responses that lead to the transepithelial migration of PMNs. Thus, the objective of this study was to determine the functional domain of SipA that regulates this signalling event. SipA was divided into two fragments: the SipAb C-terminal fragment (259 AA), which binds actin, and the SipAa fragment 2-425 (424 AA), which a role has yet to be described. In both in vitro and in vivo models of S. typhimuriuminduced intestinal inflammation the SipAa fragment exhibited a profound ability to induce PMN transmigration, whereas the SipAb actin-binding domain failed to induce PMN transmigration. Subsequent mapping of the SipAa domain identified a 131-amino-acid region (SipAa3 ) responsible for modulating PMN transepithelial migration. Interestingly, neither intracellular translocation nor actin association of SipA was necessary for its ability to induce PMN transepithelial migration. As these results indicate SipA has at least two separate functional domains, we speculate that during infection S. typhimurium requires delivery of SipA to both extracellular and intracellular spaces to maximize pro-inflammatory responses and mechanisms of bacterial invasion.

Salmonella typhimurium elicits an intense proinflammatory response characterized by movement of polymorphonuclear neutrophils (PMN) across the epithelial barrier to the intestinal lumen. We previously showed that S. typhimurium, via the type III secretion system effector protein SipA, initiates an ADP-ribosylation factor-6- and phospholipase D-dependent lipid-signaling cascade that directs activation of protein kinase C (PKC) and subsequent transepithelial movement of PMN. Here we sought to determine the specific PKC isoforms that are induced by the S. typhimurium effector SipA in model intestinal epithelia and to link the functional consequences of these isoforms in the promotion of PMN transepithelial migration. In vitro kinase PKC activation assays performed on polarized monolayers of T84 cells revealed that S. typhimurium and recombinant SipA induced activation of PKC-alpha, -delta, and -epsilon. To elucidate which of these isoforms play a key role in mediating epithelial cell responses that lead to the observed PMN transepithelial migration, we used a variety of PKC inhibitors with different isoform selectivity profiles. Inhibitors selective for PKC-alpha (Gö-6976 and 2,2',3,3',4,4'-hexahydroxyl-1,1'-biphenyl-6,6'-dimethanoldimethyl ether) markedly reduced S. typhimurium- and recombinant SipA-induced PMN transepithelial migration, whereas inhibitors to PKC-delta (rottlerin) or PKC-epsilon (V1-2) failed to exhibit a significant decrease in transepithelial movement of PMN. These results were confirmed biochemically and by immunofluorescence coupled to confocal microscopy. Our results are the first to show that the S. typhimurium effector protein SipA can activate multiple PKC isoforms, but only PKC-alpha is involved in the signal transduction cascade leading to PMN transepithelial migration.

Objective Healthcare leaders seek guidance on prudent investment in programs that improve patient outcomes and reduce costs, which includes the value of nutrition therapy. The purpose of this project was to conduct an evidence review and evaluate claims analyses to understand the financial and quality impact of nutrition support therapy on high‐priority therapeutic conditions. Methods Task 1 included a review of existing literature from 2013 to 2018 to identify evidence that demonstrated the clinical and economic impact of nutrition intervention on patient outcomes across 13 therapeutic areas (TAs). In Task 2, analytic claims modeling was performed using the Medicare Parts A and B claims 5% sample dataset. Beneficiaries diagnosed in 5 selected TAs (sepsis, gastrointestinal [GI] cancer, hospital‐acquired infections, surgical complications, and pancreatitis) were identified in the studies from Task 1, and their care costs were modeled based on nutrition intervention. Results Beginning with 1099 identified articles, 43 articles met the criteria, with a final 8 articles used for the Medicare claims modeling. As examples of the modeling demonstrated, the use of advanced enteral nutrition formula could save at least $52 million annually in a sepsis population. The total projected annual cost savings from the 5 TAs was $580 million. Conclusion Overall, optimization of nutrition support therapy for specific patient populations is estimated to reduce Medicare spending by millions of dollars per year across key TAs. These findings demonstrate the evidence‐based value proposition of timely nutrition support to improve clinical outcomes and yield substantial cost savings.