The pyrin inflammasome senses OCTN2-mediated uptake of extracellular ʟ-carnitine from muscle injury or ingestion.

Extracellular L-carnitine activates the pyrin inflammasome via OCTN2 in macrophages, linking skeletal muscle injury and red meat consumption to inflammation.

• Why it matters: Understanding how red meat and excess dietary carnitine promote inflammation addresses a key gap in the mechanisms underlying diet-related chronic inflammatory diseases.
• What they did: The study used LPS-challenged mice and LPS-primed murine and human macrophages to show that extracellular L-carnitine represses mevalonate synthesis and triggers pyrin inflammasome activation through OCTN2-mediated import.
• The result: Findings suggest macrophages detect extracellular L-carnitine as a marker of muscle damage, providing a mechanistic basis for how dietary carnitine may contribute to inflammatory disease.