Skeletal interoception regulates joint homeostasis and PGE2-induced pain: implication of disease-modifying treatment.

Interoception is a core process through which the body perceives its internal state and regulates physiological homeostasis via bidirectional communication between the central and peripheral nervous system. Skeletal interoception is a specific circuitry for the brain control of the weight-bearing system, particularly responsible for sensing bone-derived internal signals to maintain skeletal homeostasis in response to mechanical loading. Recent studies uncovered that prostaglandin E2 (PGE2) plays a crucial role in skeletal interoception, and is therefore involved in major skeletal disorders and pain conditions such as low back pain, osteoarthritis and particularly ankle osteoarthritis (AOA). Ankle pain is clinically common, with a prevalence of 9%-15% among adults, severely impairing work productivity and quality of life. This article reviews the progress of skeletal interoception in skeletal pathogenesis and pain, with AOA as an example. Specifically, it discusses PGE2 and skeletal interoception in relation to pain and inflammation. We also attempted to interpret non-steroidal anti-inflammatory drugs (NSAIDs), surgical interventions and Traditional Chinese Medicine (TCM) therapies, especially acupuncture and electroacupuncture, in the therapy of pain and osteoarthritis from the viewpoint of skeletal interoception. Interoception is an emerging science in understanding how the brain regulates peripheral organs. Skeletal interoception mediated by PGE2 provides an opportunity to understand the potential of NSAIDs and acupuncture in regulating interoception for the treatment of skeletal disorders including ankle pain.