Abstract

IL-1β is a pleotropic cytokine that may mediate increased procoagulant activity and permeability in endothelial tissue during inflammatory conditions. The procoagulant effects of IL-1β are mediated through induction of tissue factor (TF) but its alterations on vascular permeability are not well characterized. We found that IL-1β induced a rapid and dose-dependent increase in TF activity in human umbilical vein endothelial cells (ECs) under routine culture conditions. However, IL-1β caused a rapid and marked increase in permeability across confluent EC monolayers using a two-compartment in vitro model only in the presence of factor VIII-deficient plasma that was completely abrogated by neutralizing anti-TF antibody pre-treatment. In vitro permeability was associated with loss of EC surface expression of VE-cadherin and contraction of F-actin cytoskeletal elements that resulted in EC intercellular gap formation. These data demonstrate that IL-1β induces marked changes in permeability across activated endothelium via a TF dependent mechanism and suggest that modulation of TF activity may represent a strategy to treat various acute and chronic inflammatory conditions mediated by this cytokine.

Highlights

  • IL-1β is a pleotropic 17.5 kD cytokine, secreted primarily by monocytes and macrophages, that mediates the pathophysiology of various acute and chronic inflammatory conditions

  • tissue factor (TF) induction and permeability in endothelial cells by IL-1β in vitro TF induction in ECs was assessed under basal culture conditions using a single-stage coagulation assay after a 2hour exposure to various concentrations of IL-1β

  • There was little TF activity measured at concentrations of IL-1β below 100 pg/mL and no further increase in TF activity was observed above 1 ng/ml

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Summary

Introduction

IL-1β is a pleotropic 17.5 kD cytokine, secreted primarily by monocytes and macrophages, that mediates the pathophysiology of various acute and chronic inflammatory conditions. High levels of circulating IL-1 have been identified in experimental models of endotoxic shock and acute bacterial infection and increased gene expression of IL-1 has been identified in tissues at sites of experimentally induced inflammation [1,2]. High levels of circulating IL-1 have been identified in patients with acute bacterial infections and elevated levels of IL-1 have been detected in the diseased articular tissues of patients with chronic rheumatoid arthritis [3,4]. Increased vascular permeability most likely represents the initial event in pathological or reparative inflammation or angiogenesis by allowing efflux of plasma proteins into interstitium to serve as a provisional matrix for circulating inflammatory cells or activated endothelium [15]. In rodent or guinea pig models others have not demonstrated any independent effects of aerosolized or systemically administered IL-1 on pulmonary vascular permeability or injury [21,22]

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