Mechanisms of ＂kidney governing bones＂ theory in traditional Chinese medicine

Studies conducted by our group on the mechanism of ＂kidney governing bones＂ theory in traditional Chinese medicine （TCM） are reviewed in this paper. Conclusions can be summarized as follows. （1） Neuroendocrine-immune network （NIN）-osteoclast regulatory pathway OPG-RANKL-RANK is one of the mechanisms of ＂kidney governing bones.＂ Although kidney-reinforcing therapy is regarded as one of the holistic regulatory mechanisms of the body, characteristic holistic regulation in TCM can be reflected through nonselective regulation of the NIN during kidney reinforcement therapy, which can be used to treat osteoporosis through microadjustments in the microenvironment of the bone marrow. （2） Marrow exhaustion in TCM, which is the state wherein lipocytes in the bone marrow increase whereas other cells decrease, serves as the pathogenesis of osteoporosis brought about by failure of the ＂kidney governing bones.＂ （3） The kidney in TCM can be regarded as a complex system comprising multiple functional units in the body, including the unit ＂governing bones.＂ Kidney deficiency refers to a deficiency in only one or more units of the kidney system and not the whole system itself, which explains the kidney-reinforcing effect of many herbs; some herbs can treat osteoporosis, but some cannot. Although both classified as kidney-reinforcing agents, the former can resolve failure of the ＂kidney governing bones＂ unit while the latter regulates the failure of other units in the kidney system. Despite the current understanding on ＂kidney governing bones＂ theory, the mechanism of ＂kidney governing bones＂ remains complicated and unresolved. Thus, further studies in this area are warranted.

New Insights into the Molecular Basis of Kidney Governing Bone Theory

Kidney governing bone theory plays an important role in treating bone metabolic disease such as osteoporosis, and many tonifying kidney prescriptions/herbs are widely used in Traditional Chinese Medicine(TCM). However, the exact biological basis of kidney governing bone theory in the context of new advances in biology is still not fully established. In this paper, the content of kidney governing bone theory in biology has been fully demonstrated from different aspects. We first propose that bone and kidney mutually affect each other in pathology and physiology, particularly through homeostasis of calcium, phosphorus and fibroblast growth factor-23(FGF-23). Next, we identify that tonifying kidney prescriptions/herbs exert bone protective effects, thus treating osteoporosis by regulating bone formation and bone resorption.Furthermore, the exact molecular mechanisms of tonifying kidney prescriptions, herbs and their effective components in treating osteoporosis have been systematically reviewed. Finally, we come into the conclusion that kidney regulating bone mineral homeostasis, bone protective effects of tonifying kidney herbs and regulatory effects on bone homeostasis are all the manifestations of kidney governing bone theory.Therefore, the new insights into kidney governing bone theory in biology will promote the development of clinical practices, and drugs discovery in treating osteoporosis.