CD44 mediates stem cell mobilization to damaged lung its novel transcriptional targets, Cortactin and Survivin

Beyond their role in bone and lung homeostasis, mesenchymal stem cells (MSCs) are becoming popular in cell therapy. Various insults may disrupt the repair mechanisms involving MSCs. One such insult is smoking, which is a major risk factor for osteoporosis and respiratory diseases. Upon cigarette smoke-induced damage, a series of reparatory mechanisms ensue; one such mechanism involves Glycosaminoglycans (GAG). One of these GAGs, namely hyaluronic acid (HA), serves as a potential therapeutic target in lung injury. However, much of its mechanisms of action through its major receptor CD44 remains unexplored. Our previous studies have identified and functionally validated that both cortactin (CTTN: marker of motility) and Survivin (BIRC5: required for cell survival) act as novel HA/CD44-downstream transcriptional targets underpinning cell motility. Here, human MSCs were treated with "" smoke to investigate the effects of cigarette smoke condensate (CSC) on these HA-CD44 novel signaling pathways. Our results show that CSC decreased the expression of both CD44 and its downstream targets CTTN and BIRC5 in MSCs, and that HA reversed these effects. Interestingly, CSC inhibited migration and invasion of MSCs upon CD44-targeted RNAi treatment. This shows the importance of CD44-HA/CTTN and CD44-HA/BIRC5 signaling pathways in MSC motility, and further suggests that these signaling pathways may provide a novel mechanism implicated in migration of MSCs during repair of lung tissue injury. These findings suggest that one should use caution before utilizing MSC from donors with history of smoking, and further pave the way towards the development of targeted therapeutic approaches against CD44-associated diseases

Diversity of resistance mechanisms in carbapenem-resistant Enterobacteriaceae at a health care system in Northern California, from 2013 to 2016

The mechanism of resistance in carbapenem-resistant Enterobacteriaceae (CRE) has therapeutic implications. We comprehensively characterized emerging mechanisms of resistance in CRE between 2013 and 2016 at a health system in Northern California. A total of 38.7% (24/62) of CRE isolates were carbapenemase gene-positive, comprising 25.0% (6/24) blaOXA-48 like, 20.8% (5/24) blaKPC, 20.8% (5/24) blaNDM, 20.8% (5/24) blaSME, 8.3% (2/24) blaIMP, and 4.2% (1/24) blaVIM. Between carbapenemases and porin loss, the resistance mechanism was identified in 95.2% (59/62) of CRE isolates. Isolates expressing blaKPC were 100% susceptible to ceftazidime–avibactam, meropenem–vaborbactam, and imipenem–relebactam; blaOXA-48 like–positive isolates were 100% susceptible to ceftazidime–avibactam; and metallo β-lactamase–positive isolates were nearly all nonsusceptible to above antibiotics. Carbapenemase gene-negative CRE were 100% (38/38), 92.1% (35/38), 89.5% (34/38), and 31.6% (12/38) susceptible to ceftazidime–avibactam, meropenem–vaborbactam, imipenem–relebactam, and ceftolozane–tazobactam, respectively. None of the CRE strains were identical by whole genome sequencing. At this health system, CRE were mediated by diverse mechanisms with predictable susceptibility to newer β-lactamase inhibitors

<em>In Vitro</em> Immunomodulation of a Whole Blood IFN-γ Release Assay Enhances T Cell Responses in Subjects with Latent Tuberculosis Infection

<div><h3>Background</h3><p>Activation of innate immunity via pathogen recognition receptors (PRR) modulates adaptive immune responses. PRR ligands are being exploited as vaccine adjuvants and as therapeutics, but their utility in diagnostics has not been explored. Interferon-gamma (IFN-γ) release assays (IGRAs) are functional T cell assays used to diagnose latent tuberculosis infection (LTBI); however, novel approaches are needed to improve their sensitivity.</p> <h3>Methods</h3><p>In vitro immunomodulation of a whole blood IGRA (QuantiFERON®-TB GOLD In-Tube) with Toll-like receptor agonists poly(I:C), LPS, and imiquimod was performed on blood from subjects with LTBI and negative controls.</p> <h3>Results</h3><p>In vitro immunomodulation significantly enhanced the response of T cells stimulated with <em>M. tuberculosis</em> antigens from subjects with LTBI but not from uninfected controls. Immunomodulation of IGRA revealed T cell responses in subjects with LTBI whose T cells otherwise do not respond to in vitro stimulation with antigens alone. Similar to their <em>in vivo</em> functions, addition of poly(I:C) and LPS to whole blood induced secretion of inflammatory cytokines and IFN-α and enhanced the surface expression of antigen presenting and costimulatory molecules on antigen presenting cells.</p> <h3>Conclusions</h3><p>In vitro immunomodulation of whole blood IGRA may be an effective strategy for enhancing the sensitivity of T cells for diagnosis of LTBI.</p> </div

Immunomodulation of Quantiferon assay elicits an IFN-γ response in IGRA-unresponsive subjects with LTBI.

<p>IFN-γ response (TB Ag minus Nil) for individuals with history of LTBI. Each individual was tested with the QFT-GIT assay in the absence or presence of poly(I:C) 40 µg/ml, LPS 250 pg/ml, and imiquimod (IMQ) 2 µg/ml. The cut-off value for the standard QFT-GIT assay (dashed line) is shown for reference.</p

Immunomodulation of Quantiferon assay with TLR ligands enhances markers of innate immune activation.

<p>(Panel A) Induction of IL-6, IL-12, and IFN-α in whole blood stimulated with TLR agonists. Blood from four donors with LTBI (red symbols) and four uninfected controls (black symbols) was incubated in the QFT-GIT Nil tube in the absence or presence of poly(I:C) 40 µg/ml and LPS 250 pg/ml for 22 h. (Panel B) Flow cytometry analysis of surface expression of MHC class I and II and costimulatory molecules on monocytes stimulated with poly(I:C) and LPS. Whole blood from six donors was incubated in the QFT-GIT Nil tube in the absence (dashed red line) or presence (solid blue line) of poly(I:C) 40 µg/ml and LPS 250 pg/ml for 3 h. (Panel C) Kinetics of IFN-γ response (IFN-γ response, TB Ag minus Nil) in the QFT-GIT assay without and with immunomodulation with poly(I:C) 40 µg/ml and LPS 250 pg/ml. Data in B and C are representative of 6 individuals in each group. The Wilcoxon signed-rank test was used to compare responses with and without PRR ligands. The asterisks indicate significant difference. *, <i>P</i>≤0.05, **, <i>P</i>≤0.005, *** <i>P</i>≤0.0005.</p