Proinflammatory Mediators, IL (Interleukin)-1β, TNF (Tumor Necrosis Factor) α, and Thrombin Directly Induce Capillary Tube Regression

Arterioscler Thromb Vasc Biol. 2020 Feb;40(2):365-377. doi: 10.1161/ATVBAHA.119.313536. Epub 2019 Dec 19.


Objective: In this work, we examine the molecular basis for capillary tube regression and identify key proregressive factors, signaling pathways, and pharmacological antagonists of this process. Approach and Results: We demonstrate that the proinflammatory mediators, IL (interleukin)-1β, TNF (tumor necrosis factor) α, and thrombin, singly and in combination, are potent regulators of capillary tube regression in vitro. These proregressive factors, when added to endothelial cell-pericyte cocultures, led to selective loss of endothelial cell-lined tube networks, with retention and proliferation of pericytes despite the marked destruction of adjacent capillary tubes. Moreover, treatment of macrophages with the TLR (toll-like receptor) agonists Pam3CSK4 and lipopolysaccharide generates conditioned media with marked proregressive activity, that is completely blocked by a combination of neutralizing antibodies directed to IL-1β and TNFα but not to other factors. The same combination of blocking antibodies, as well as the anti-inflammatory cytokine IL-10, interfere with macrophage-dependent hyaloid vasculature regression in mice suggesting that proinflammatory cytokine signaling regulates capillary regression in vivo. In addition, we identified a capillary regression signaling signature in endothelial cells downstream of these proregressive agents that is characterized by increased levels of ICAM-1 (intercellular adhesion molecule-1), phospho-p38, and phospho-MLC2 (myosin light chain-2) and decreased levels of phospho-Pak2, acetylated tubulin, phospho-cofilin, and pro-caspase3. Finally, we identified combinations of pharmacological agents (ie, FIST and FISTSB) that markedly rescue the proregressive activities of IL-1β, TNFα, and thrombin, individually and in combination.

Conclusions: Overall, these new studies demonstrate that the major proinflammatory mediators, IL-1β, TNFα, and thrombin, are key regulators of capillary tube regression-a critical pathological process regulating human disease.

Keywords: endothelial cells; interleukins; pericytes; thrombin; tumor necrosis factor-α.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Capillaries / metabolism*
  • Capillaries / pathology
  • Cells, Cultured
  • Disease Models, Animal
  • Endothelial Cells / metabolism*
  • Endothelial Cells / pathology
  • Endothelium, Vascular / metabolism*
  • Endothelium, Vascular / pathology
  • Female
  • Humans
  • Inflammation / metabolism*
  • Inflammation / pathology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Signal Transduction
  • Thrombin / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism*


  • Tumor Necrosis Factor-alpha
  • Thrombin