The Commensal Microbiota Enhances ADP-Triggered Integrin α IIb β 3 Activation and von Willebrand Factor-Mediated Platelet Deposition to Type I Collagen

Int J Mol Sci. 2020 Sep 28;21(19):7171. doi: 10.3390/ijms21197171.

Abstract

The commensal microbiota is a recognized enhancer of arterial thrombus growth. While several studies have demonstrated the prothrombotic role of the gut microbiota, the molecular mechanisms promoting arterial thrombus growth are still under debate. Here, we demonstrate that germ-free (GF) mice, which from birth lack colonization with a gut microbiota, show diminished static deposition of washed platelets to type I collagen compared with their conventionally raised (CONV-R) counterparts. Flow cytometry experiments revealed that platelets from GF mice show diminished activation of the integrin αIIbβ3 (glycoprotein IIbIIIa) when activated by the platelet agonist adenosine diphosphate (ADP). Furthermore, washed platelets from Toll-like receptor-2 (Tlr2)-deficient mice likewise showed impaired static deposition to the subendothelial matrix component type I collagen compared with wild-type (WT) controls, a process that was unaffected by GPIbα-blockade but influenced by von Willebrand factor (VWF) plasma levels. Collectively, our results indicate that microbiota-triggered steady-state activation of innate immune pathways via TLR2 enhances platelet deposition to subendothelial matrix molecules. Our results link host colonization status with the ADP-triggered activation of integrin αIIbβ3, a pathway promoting platelet deposition to the growing thrombus.

Keywords: Toll-like receptor-2; germ-free; microbiota; platelets; von Willebrand factor; αIIbβ3.

MeSH terms

  • Adenosine Diphosphate / pharmacology*
  • Animals
  • Arteries / metabolism
  • Arteries / pathology
  • Blood Platelets / drug effects*
  • Blood Platelets / immunology
  • Blood Platelets / pathology
  • Cell Adhesion / drug effects
  • Collagen Type I / genetics*
  • Collagen Type I / immunology
  • Female
  • Gastrointestinal Microbiome / immunology
  • Gene Expression
  • Germ-Free Life
  • Humans
  • Immunity, Innate
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Platelet Glycoprotein GPIIb-IIIa Complex / agonists
  • Platelet Glycoprotein GPIIb-IIIa Complex / genetics*
  • Platelet Glycoprotein GPIIb-IIIa Complex / immunology
  • Platelet Glycoprotein GPIb-IX Complex / genetics
  • Platelet Glycoprotein GPIb-IX Complex / immunology
  • Primary Cell Culture
  • Symbiosis / immunology
  • Thrombosis / genetics
  • Thrombosis / immunology
  • Thrombosis / microbiology*
  • Thrombosis / pathology
  • Toll-Like Receptor 2 / deficiency
  • Toll-Like Receptor 2 / genetics
  • Toll-Like Receptor 2 / immunology
  • von Willebrand Factor / genetics*
  • von Willebrand Factor / immunology

Substances

  • Collagen Type I
  • Platelet Glycoprotein GPIIb-IIIa Complex
  • Platelet Glycoprotein GPIb-IX Complex
  • Tlr2 protein, mouse
  • Toll-Like Receptor 2
  • adhesion receptor
  • von Willebrand Factor
  • Adenosine Diphosphate