Rhein: a potential biological therapeutic drug for intervertebral disc degeneration.

Intervertebral disc degeneration (IDD) is regarded as an important cause of low back pain, which continues to be a common disability. IDD is thought to involve sequential changes of intervertebral disc that lead to the reduction of disc cells and the extracellular matrix. In addition, inflammation is crucially involved in IDD. Currently, there is urgent need to develop biological therapies for IDD that can both relieve symptoms and directly reverse the process of degeneration. Rhein (RH) is an anthraquinone molecule with the abilities of enhancing the synthesis of matrix components and inhibiting inflammatory response. Recently, the metabolic precursor of RH called diacerein has been demonstrated to have significant effects on pain relief and function improvement in the treatment of osteoarthritis. Given the occurrence of matrix degeneration and involvement of inflammation in IDD, we propose that RH might be a promising biological therapeutic drug for IDD due to its bioactivities. In addition, we hypothesize that the underlying mechanisms might be that RH has the ability to diminish interleukin-1 (IL-1) induced apoptosis and inhibit IL-1 induced secretion of MMPs and aggrecanases.