Ambient particulate matter accelerates coagulation via an IL-6-dependent pathway

Area of Science:

• Environmental Health
• Cardiovascular Science
• Hematology

Background:

• Particulate matter (PM) exposure is linked to cardiovascular events, but mechanisms remain unclear.
• Emerging data suggest PM may alter hemostatic factors, influencing thrombosis risk.

Purpose of the Study:

• To elucidate the mechanisms by which particulate matter exposure accelerates thrombosis.
• To investigate the role of interleukin-6 (IL-6) and macrophages in PM-induced prothrombotic effects.

Main Methods:

• Mice were exposed to well-characterized particulate matter (<10 µm).
• Assessed bleeding time, plasma clotting times, fibrinogen, and clotting factor activity.
• Measured intravascular thrombin generation, arterial thrombosis, IL-6 levels, and macrophage activity.

Main Results:

• PM exposure shortened bleeding time and decreased plasma clotting times.
• Increased fibrinogen, clotting factor activity (II, VIII, X), and thrombin generation were observed.
• PM exposure increased IL-6 in bronchoalveolar fluid; IL-6 knockout mice were protected, and macrophage depletion attenuated these effects.

Conclusions:

• Particulate matter exposure induces IL-6 production by alveolar macrophages.
• This IL-6 mediated pathway leads to reduced clotting times, increased thrombin generation, and accelerated arterial thrombosis.
• Findings suggest a mechanism linking air pollution exposure to thrombotic cardiovascular events.