Induction of interleukin‐1 and subsequent tissue factor expression by anti‐proteinase 3 antibodies in human umbilical vein endothelial cells

Abstract

Objective. To assess the ability of anti‐proteinase 3 (anti‐PR3) classic antineutrophil cytoplasmic antibodies (cANCA) to stimulate endothelial expression of tissue factor (TF), which is the main initiator of the coagulation cascade that can lead to endothelial injury and thrombosis in patients with Wegener's granulomatosis. Methods. Human umbilical vein endothelial cells (HUVEC) were grown to confluence and stimulated with affinity‐purified anti‐PR3 antibodies, Igs from healthy subjects, and endotoxin (lipopolysaccharide) as positive control. Results. TF activity was generated in anti‐PR3‐ stimulated cells, as shown by a chromogenic test. This activity was inhibited by specific anti‐TF antibodies. TF messenger RNA (mRNA) was found in anti‐PR3‐ stimulated cells, as detected by reverse transcriptasepolymerase chain reaction, but not in cells stimulated with irrelevant human Igs or Igs from normal control sera. TF expression reached maximum levels 12 hours after exposure to the anti‐PR3 cANCA, and did not require complement. TF mRNA expression was inhibited by cycloheximide, suggesting a requirement for protein synthesis. When added to the incubation medium, interleukin‐1 (IL‐1) receptor antagonist inhibited the induced TF mRNA expression, suggesting that cANCA‐stimulated cells initiate IL‐1 synthesis. Moreover, cANCA induced IL‐lα mRNA before TF mRNA. Conclusion. This study showed that anti‐PR3 treatment of HUVEC induces sequential expression of IL‐lα mRNA and TF mRNA, as well as their corresponding proteins. Both proteins could have pathogenic roles in the vasculitic process, since TF is the main initiator of the coagulation cascade.

Rare diseases bullet 3: Wegener's granulomatosis

“…47 In in vitro studies the binding of anti-PR-3 to endothelial cells results in increased endothelial cell production of IL-8, an extremely potent neutrophil chemotactic agent 48. Concurrent with these events, endothelial cells exposed to anti-PR-3 also increase, in sequential fashion, IL-1α production and tissue factor, the principal initiator of the coagulation cascade 49. The monocyte, like the neutrophil, also produces PR-3 and, when activated and exposed to anti-PR-3, they will also increase IL-8 production markedly, further setting the stage for enhanced neutrophil chemotaxis 50.…”

Management of Wegener Granulomatosis

“…9,17 c-ANCA induces full activation of neutrophils with a respiratory burst followed by release of O 2 radicals and proinflammatory cytokines, 18,19 resulting in endothelial-cell injury and tissue damage. 10,20 -22 c-ANCA also indirectly augments expression of leukocyte adhesion molecules, 23,24 allowing for inflammatory cell localization to sites of injury. Additionally, human endothelium expresses PR-3, and c-ANCA antibodies have been shown to activate endothelial cells in vitro.…”

Wegener’s Granulomatosis and Vertebro-Basilar Thrombosis

“…Acquired endothelial dysfunction due to pro-infl ammatory cytokines such as tumor necrosis factor and PR-3 antibodies is another possibility. These cytokines result in the expression of tissue factor (TF) in the endothelium and enhance thrombogenicity [11]. TF is a major player in the coagulation cascade and induces a prothrombotic state.…”