Acupuncture and its ability to restore and maintain immune homeostasis

Immune homeostasis is a steady immune state that not only protects the host from pathogens but also prevents the emergence of pathological self-reactive immune cells. The disruption of immune homeostasis leads to the development of various diseases, such as cancer and autoimmune diseases. An emerging paradigm for the treatment of these diseases with dysfunctional immune systems is the restoration and maintenance of immune homeostasis. However, currently available drugs exert a unidirectional influence on immunity whereby they either augment or inhibit it. This strategy is associated with the drawback of potential adverse effects arising from uncontrolled activation or suppression of the immune system. Fortunately, evidence suggests that acupuncture can bidirectionally regulate the immune system to maintain immune homeostasis. In cases of immunosuppressive diseases (e.g. cancer), acupuncture has an enhancing effect on immunity. Conversely, in autoimmune diseases (e.g. rheumatoid arthritis), acupuncture has been observed to have an immunosuppressive effect, which helps restore normal immune tolerance. However, there is no publication systematically summarizing the bidirectional regulatory effects of acupuncture on the immune system in the literature. Here, our review provides a comprehensive overview of the various mechanisms through which acupuncture modulates the immune system in a bidirectional manner. These mechanisms include the augmentation of NK and CD8+ T cell function, as well as the restoration of Th1/Th2, Th17/Treg and M1/M2 balance. Thus, we propose the concept that acupuncture has the potential to alleviate illnesses through the facilitation of immune normalization. Moreover, we further highlight the therapeutic potential of acupuncture.