Neuropilin-1/GIPC1 Signaling Regulates α5β1 Integrin Traffic and Function in Endothelial Cells

Neuropilin 1 (Nrp1) is a coreceptor for vascular endothelial growth factor A165 (VEGF-A165, VEGF-A164 in mice) and semaphorin 3A (SEMA3A). Nevertheless, Nrp1 null embryos display vascular defects that differ from those of mice lacking either VEGF-A164 or Sema3A proteins. Furthermore, it has been recently reported that Nrp1 is required for endothelial cell (EC) response to both VEGF-A165 and VEGF-A121 isoforms, the latter being incapable of binding Nrp1 on the EC surface. Taken together, these data suggest that the vascular phenotype caused by the loss of Nrp1 could be due to a VEGF-A164/SEMA3A-independent function of Nrp1 in ECs, such as adhesion to the extracellular matrix. By using RNA interference and rescue with wild-type and mutant constructs, we show here that Nrp1 through its cytoplasmic SEA motif and independently of VEGF-A165 and SEMA3A specifically promotes α5β1-integrin-mediated EC adhesion to fibronectin that is crucial for vascular development. We provide evidence that Nrp1, while not directly mediating cell spreading on fibronectin, interacts with α5β1 at adhesion sites. Binding of the homomultimeric endocytic adaptor GAIP interacting protein C terminus, member 1 (GIPC1), to the SEA motif of Nrp1 selectively stimulates the internalization of active α5β1 in Rab5-positive early endosomes. Accordingly, GIPC1, which also interacts with α5β1, and the associated motor myosin VI (Myo6) support active α5β1 endocytosis and EC adhesion to fibronectin. In conclusion, we propose that Nrp1, in addition to and independently of its role as coreceptor for VEGF-A165 and SEMA3A, stimulates through its cytoplasmic domain the spreading of ECs on fibronectin by increasing the Rab5/GIPC1/Myo6-dependent internalization of active α5β1. Nrp1 modulation of α5β1 integrin function can play a causal role in the generation of angiogenesis defects observed in Nrp1 null mice

A Controlled Clinical Trial of E5 Murine Monoclonal IgM Antibody to Endotoxin in the Treatment of Gram-Negative Sepsis

Objective. —To assess the efficacy of adjunctive monoclonal antibody antiendotoxin immunotherapy in patients with gram-negative sepsis. Design. —Double-blind, randomized, placebo-controlled trial. Setting. —Thirty-three university-affiliated centers, including Veterans Affairs, community, and municipal hospitals. Patients. —Hospitalized adults with signs of gram-negative infection and a systemic septic response. Intervention. —Patients were assigned to receive either 2 mg/kg of a murine monoclonal antibody directed against gram-negative endotoxin (E5) or placebo. A second infusion was administered 24 hours later. Main Outcome Measures. —Mortality over the 30-day study period, resolution of organ failures, and safety. Results. —Four hundred eighty-six patients were enrolled. Three hundred sixteen had confirmed gram-negative sepsis (54% bacteremic, 46% nonbacteremic). The survival difference was not statistically significant for all patients. Among patients with gram-negative sepsis who were not in shock at study entry (n = 137), E5 treatment resulted in significantly greater survival (relative risk, 2.3; P =.01). Resolution of individual organ failures was more frequent among these patients, occurring in 19 (54%) of 35 patients in the E5 group vs eight (30%) of 27 in the placebo group (P =.05). Four reversible allergic reactions occurred among 247 patients (1.6%) receiving E5. No other toxicity was identified. Conclusions. —Treatment with E5 antiendotoxin antibody appears safe. It reduces mortality and enhances the resolution of organ failure among patients with gram-negative sepsis who are not in shock when treated.(JAMA. 1991;266:1097-110

A Controlled Clinical Trial of E5 Murine Monoclonal IgM Antibody to Endotoxin in the Treatment of Gram-Negative Sepsis

Objective. —To assess the efficacy of adjunctive monoclonal antibody antiendotoxin immunotherapy in patients with gram-negative sepsis. Design. —Double-blind, randomized, placebo-controlled trial. Setting. —Thirty-three university-affiliated centers, including Veterans Affairs, community, and municipal hospitals. Patients. —Hospitalized adults with signs of gram-negative infection and a systemic septic response. Intervention. —Patients were assigned to receive either 2 mg/kg of a murine monoclonal antibody directed against gram-negative endotoxin (E5) or placebo. A second infusion was administered 24 hours later. Main Outcome Measures. —Mortality over the 30-day study period, resolution of organ failures, and safety. Results. —Four hundred eighty-six patients were enrolled. Three hundred sixteen had confirmed gram-negative sepsis (54% bacteremic, 46% nonbacteremic). The survival difference was not statistically significant for all patients. Among patients with gram-negative sepsis who were not in shock at study entry (n = 137), E5 treatment resulted in significantly greater survival (relative risk, 2.3; P =.01). Resolution of individual organ failures was more frequent among these patients, occurring in 19 (54%) of 35 patients in the E5 group vs eight (30%) of 27 in the placebo group (P =.05). Four reversible allergic reactions occurred among 247 patients (1.6%) receiving E5. No other toxicity was identified. Conclusions. —Treatment with E5 antiendotoxin antibody appears safe. It reduces mortality and enhances the resolution of organ failure among patients with gram-negative sepsis who are not in shock when treated.(JAMA. 1991;266:1097-110