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VAV guanine nucleotide exchange factor is required for Dectin-1 mediated phagocytosis
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Surgical Forum Abstracts
mained closed without failure at 14 days, however cellular infiltration was decreased in IL-1R KO mice. Analysis of day 1 wound fluid demonstrated a 15-fold decrease in IL-6 (3⫾2 vs. 47⫾10 ng/ml in control), as well as decreased VEGF (68⫾17 vs. 137⫾17 pg/ml) and TGF beta (5.3⫾0.8 vs. 7.8⫾0.7 ng/ml) in IL-1R KO animals (p⬍0.05). These cytokines did not differ at other time points. CONCLUSIONS: Fetal wound healing restores normal dermal architecture with less cellular infiltration and no scarring. Interruption of IL-1R signaling does not impair the rate of wound closure, but drastically reduces fibrosis while creating a fetal-like appearance of incisional wounds. Potential mechanisms include early reductions in cytokines known to have pro-fibrotic actions: IL-6, VEGF and TGF beta. Modulation of the IL-1R pathway has therapeutic potential in abnormal healing.
Histone deacetylase inhibition: A novel treatment for lethal septic shock Elizabeth A Sailhamer MD, Yongqing Li, Hang Zhao PhD, Charles A Hales MD, Fahad Shuja MD, Muhammad U Butt MD, George C Velmahos MD, FACS, Marc A deMoya MD, Hasan B Alam MD, FACS Massachusetts General Hospital/Harvard Medical School, Boston, MA INTRODUCTION: Lipopolysaccharide (LPS) and trauma-induced heat shock protein 60 (HSP60) can bind to toll-like receptor 4 (TLR4), which in turn recruits MyD88 adaptor for downstream expression of many inflammatory cytokines. We have recently found that suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, improves survival in lethal model of hemorrhagic shock in rats. The purpose of the present study was to determine whether SAHA would prevent LPS-induced septic shock, and improve survival in a rodent model. METHODS: C57B1/6J mice were given intraperitoneal (ip) SAHA (50 mg/kg in 6-7 l vehicle fluid, n⫽5). Untreated mice (Control, n⫽7) and MyD88 knockout mice (MyD88⫺/⫺, n⫽2) received vehicle agent only. They were then injected with LPS (20 mg/kg, ip), and treated animals were given a second dose of SAHA. All animals were observed until death. In a parallel study, lungs were harvested from normal and LPS- injected mice (with or without SAHA treatment) after 3 hours. RESULTS: SAHA treated animals displayed significantly higher long-term survival (75%), compared to control and MyD88⫺/⫺ mice groups, in which 100% of the mice died within 50 hours. Moreover, SAHA markedly increased the acetylation of histone protein (H3 at lysine 9) and reduced gene expression of IL-1 and TNF-␣ in the lung. CONCLUSIONS: We report for first time that SAHA (50 mg/kg) improves survival from LPS-induced septic shock in an animal model. This appears to be independent of TLR-4 receptor. SAHA attenuates LPS-induced mRNA expression of pro-inflammatory cytokines (IL-1 and TNF-␣) in the lung through hyperacetylation of histone protein.
J Am Coll Surg
VAV guanine nucleotide exchange factor is required for Dectin-1 mediated phagocytosis Jill Kathleen Johnstone MD, Nicole A Morin BS, Jorge E Albina MD, William G Cioffi MD, FACS, Jonathan S Reichner PhD Rhode Island Hospital/ Brown University, Providence, RI INTRODUCTION: Phagocytosis, an essential part of innate immunity, is the cellular process of recognition and engulfment of particles, which involves an array of cell surface receptors. VAV is a guanine nucleotide exchange factor that regulates RhoGTPase activity, which in turn regulate cytockeleton rearrangement. Actin polymerization is a common aspect of phagocytosis, however, its regulatory pathways are complex and may be receptor specific. We tested the hypothesis that VAV is essential for the phagocytosis of fungal particles by Dectin-1 receptors but is not required for Fc-mediated phagocytosis. METHODS: Bone marrow macrophages were derived from wild type and VAV-knockout mice, and were assayed for phagocytosis of fluorescenated zymocel (Dectin-1 dependent) or IgG opsonized latex beads (FcR-dependent) for 30 minutes at 37C. Cells were then photographed on a Nikon TE2000 microscope and intracellular particles were enumerated per 100 cells. Immunoprecipitation/immunoblot analysis was used to evaluate tyrosine phosphorylation of VAV in wild-type murine macrophages when exposed to zymocel versus IgG opsonized latex beads. RESULTS: In the Dectin-1 phagocytic assay, VAV-knockout macrophages ingested 67.3%⫾7.4% fewer zymocel particles than wild-type macrophages (p⬍0.0001). In the Fc-mediated phagocytic assay, VAV-knockout macrophages ingested 17.5%⫾6.1% more IgG-opsonized latex beads then wild-type (p⬎0.05). Immunoprecipitation/immunoblot analysis showed an increase in tyrosine phosphorylation of VAV in wild-type macrophages when exposed to zymocel but not to IgG opsonized latex beads. CONCLUSIONS: These findings are the first demonstration of the role of VAV in Dectin-1 mediated phagocytosis and further define the complex regulation of phagocytosis by highlighting a receptorspecific intracellular signaling mechanism.
Whence resistance? Rosemarie Metzger MD, Brian R Swenson MD, Hugo Bonatti MD, Traci L Hedrick MD, Shannon T McElearney MD, Kimberley A Popovsky RN, Robert G Sawyer MD, FACS University of Virginia Health System, Charlottesville, VA INTRODUCTION: Antimicrobial resistance is an important determinant of morbidity and mortality in critical care settings. Strategies to prevent emergence and spread of resistant organisms include both pharmacologic and non-pharmacologic measures, notably isolation and contact precautions that can decrease contact with patients. We hypothesized that resistant infections in the ICU occur in the setting of antimicrobial pressure rather than via spread from other patients. METHODS: We reviewed a prospectively collected dataset of all ICU-acquired infections in surgical and trauma patients from 12/
Surgical Forum Abstracts
mained closed without failure at 14 days, however cellular infiltration was decreased in IL-1R KO mice. Analysis of day 1 wound fluid demonstrated a 15-fold decrease in IL-6 (3⫾2 vs. 47⫾10 ng/ml in control), as well as decreased VEGF (68⫾17 vs. 137⫾17 pg/ml) and TGF beta (5.3⫾0.8 vs. 7.8⫾0.7 ng/ml) in IL-1R KO animals (p⬍0.05). These cytokines did not differ at other time points. CONCLUSIONS: Fetal wound healing restores normal dermal architecture with less cellular infiltration and no scarring. Interruption of IL-1R signaling does not impair the rate of wound closure, but drastically reduces fibrosis while creating a fetal-like appearance of incisional wounds. Potential mechanisms include early reductions in cytokines known to have pro-fibrotic actions: IL-6, VEGF and TGF beta. Modulation of the IL-1R pathway has therapeutic potential in abnormal healing.
Histone deacetylase inhibition: A novel treatment for lethal septic shock Elizabeth A Sailhamer MD, Yongqing Li, Hang Zhao PhD, Charles A Hales MD, Fahad Shuja MD, Muhammad U Butt MD, George C Velmahos MD, FACS, Marc A deMoya MD, Hasan B Alam MD, FACS Massachusetts General Hospital/Harvard Medical School, Boston, MA INTRODUCTION: Lipopolysaccharide (LPS) and trauma-induced heat shock protein 60 (HSP60) can bind to toll-like receptor 4 (TLR4), which in turn recruits MyD88 adaptor for downstream expression of many inflammatory cytokines. We have recently found that suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, improves survival in lethal model of hemorrhagic shock in rats. The purpose of the present study was to determine whether SAHA would prevent LPS-induced septic shock, and improve survival in a rodent model. METHODS: C57B1/6J mice were given intraperitoneal (ip) SAHA (50 mg/kg in 6-7 l vehicle fluid, n⫽5). Untreated mice (Control, n⫽7) and MyD88 knockout mice (MyD88⫺/⫺, n⫽2) received vehicle agent only. They were then injected with LPS (20 mg/kg, ip), and treated animals were given a second dose of SAHA. All animals were observed until death. In a parallel study, lungs were harvested from normal and LPS- injected mice (with or without SAHA treatment) after 3 hours. RESULTS: SAHA treated animals displayed significantly higher long-term survival (75%), compared to control and MyD88⫺/⫺ mice groups, in which 100% of the mice died within 50 hours. Moreover, SAHA markedly increased the acetylation of histone protein (H3 at lysine 9) and reduced gene expression of IL-1 and TNF-␣ in the lung. CONCLUSIONS: We report for first time that SAHA (50 mg/kg) improves survival from LPS-induced septic shock in an animal model. This appears to be independent of TLR-4 receptor. SAHA attenuates LPS-induced mRNA expression of pro-inflammatory cytokines (IL-1 and TNF-␣) in the lung through hyperacetylation of histone protein.
J Am Coll Surg
VAV guanine nucleotide exchange factor is required for Dectin-1 mediated phagocytosis Jill Kathleen Johnstone MD, Nicole A Morin BS, Jorge E Albina MD, William G Cioffi MD, FACS, Jonathan S Reichner PhD Rhode Island Hospital/ Brown University, Providence, RI INTRODUCTION: Phagocytosis, an essential part of innate immunity, is the cellular process of recognition and engulfment of particles, which involves an array of cell surface receptors. VAV is a guanine nucleotide exchange factor that regulates RhoGTPase activity, which in turn regulate cytockeleton rearrangement. Actin polymerization is a common aspect of phagocytosis, however, its regulatory pathways are complex and may be receptor specific. We tested the hypothesis that VAV is essential for the phagocytosis of fungal particles by Dectin-1 receptors but is not required for Fc-mediated phagocytosis. METHODS: Bone marrow macrophages were derived from wild type and VAV-knockout mice, and were assayed for phagocytosis of fluorescenated zymocel (Dectin-1 dependent) or IgG opsonized latex beads (FcR-dependent) for 30 minutes at 37C. Cells were then photographed on a Nikon TE2000 microscope and intracellular particles were enumerated per 100 cells. Immunoprecipitation/immunoblot analysis was used to evaluate tyrosine phosphorylation of VAV in wild-type murine macrophages when exposed to zymocel versus IgG opsonized latex beads. RESULTS: In the Dectin-1 phagocytic assay, VAV-knockout macrophages ingested 67.3%⫾7.4% fewer zymocel particles than wild-type macrophages (p⬍0.0001). In the Fc-mediated phagocytic assay, VAV-knockout macrophages ingested 17.5%⫾6.1% more IgG-opsonized latex beads then wild-type (p⬎0.05). Immunoprecipitation/immunoblot analysis showed an increase in tyrosine phosphorylation of VAV in wild-type macrophages when exposed to zymocel but not to IgG opsonized latex beads. CONCLUSIONS: These findings are the first demonstration of the role of VAV in Dectin-1 mediated phagocytosis and further define the complex regulation of phagocytosis by highlighting a receptorspecific intracellular signaling mechanism.
Whence resistance? Rosemarie Metzger MD, Brian R Swenson MD, Hugo Bonatti MD, Traci L Hedrick MD, Shannon T McElearney MD, Kimberley A Popovsky RN, Robert G Sawyer MD, FACS University of Virginia Health System, Charlottesville, VA INTRODUCTION: Antimicrobial resistance is an important determinant of morbidity and mortality in critical care settings. Strategies to prevent emergence and spread of resistant organisms include both pharmacologic and non-pharmacologic measures, notably isolation and contact precautions that can decrease contact with patients. We hypothesized that resistant infections in the ICU occur in the setting of antimicrobial pressure rather than via spread from other patients. METHODS: We reviewed a prospectively collected dataset of all ICU-acquired infections in surgical and trauma patients from 12/