Role of Acupuncture on the Brain-Gut-Joint Axis in Osteoarthritis

Osteoarthritis (OA) is a predominantly degenerative disease with heterogeneous phenotypes, including subsets with low-grade inflammation. Emerging data suggest that the gut microbiota may contribute to OA biology. While noting that definitive, longitudinal links between acupuncture-induced microbiome modulation and joint outcomes are yet to be established clinically, acupuncture has been associated with symptomatic improvement of OA alongside immune and microbiome changes. Within a brain-gut-joint framework, preclinical, and mechanistic studies (N = 13) were assessed in this scoping review. The neuro-immune pathways, such as the vagal–adrenal/splenic, and sympatho–adrenal/splenic axes, when activated by acupuncture, can modulate gut microbial composition. These activated pathways likely involve the vagus nerve (a component of the parasympathetic nervous system) and the sympathetic nerves (which are connected to gastrointestinal-related organs, including the adrenal gland, spleen, and gut). Acupuncture may also activate the neuroendocrine system via the hypothalamic–pituitary–adrenal axis, which regulates stress, thereby releasing hormones that contribute to anti-inflammatory effects. Acupuncture may support the treatment and management of OA via the brain-gut-joint axis. Given that acupuncture is associated with fewer side effects than conventional medications, it represents a promising therapeutic strategy for OA.