Low-dose Radiation Therapy for Osteoarthritis / 生物化学与生物物理进展

ABSTRACT

Osteoarthritis (OA) is a chronic degenerative joint disease and the most common type of arthritis. It involves almost any joint and can lead to chronic pain and disability. In the late 19th century, Roentgen discovered X-rays, and then began to use radiotherapy to treat tumors. In the 1980s, Luckey thought that low-level radiation (LDRT) might be beneficial to biology, and it was gradually applied to the treatment of some diseases. This paper introduces the epidemiology, risk factors, clinical manifestations and treatment methods of OA, points out that the cartilage injury and the important effect of synovial inflammation in the pathogenesis of OA, namely when the homeostasis of articular cartilage are destroyed, synthetic metabolism and catabolism imbalances, cartilage cells damaged their breakdown products consumed by synovial cells. Synovial cells and synovial macrophages secrete proinflammatory cytokines, metalloproteinases and proteolytic enzymes, leading to cartilage matrix degradation and chondrocyte damage, which aggravates synovial inflammation and cartilage damage, forming a vicious cycle. The possible mechanism and clinical research progress of LDRT in alleviating OA are discussed. LDRT can regulate inflammatory response, inhibit the production of pro-inflammatory cytokines, and promote the production of anti-inflammatory cytokines, thereby achieving anti-inflammatory effect. Studies have shown that after irradiation, the expression of inducible nitric oxide synthase (iNOS) was decreased, the release of reactive oxygen species (ROS) and the production of superoxide were inhibited, the anti-inflammatory phenotype of macrophages was differentiated from M1 to M2, the inflammatory CD8+ T cells were transformed into CD4+ T cells, and the number of dendritic cells (DC) was significantly reduced. LDRT inhibit the production of proinflammatory factors in leukocytes, reduce their recruitment and adhesion, and down-regulate the expression levels of cell adhesion molecules such as selectin, intercellular adhesion molecule (ICAM) and vascular endothelial cell adhesion molecule (VCAM). LDRT can regulate endothelial cells, stimulate endothelial cells to produce a large amount of TGF-β1, reduce the adhesion of endothelial cells to peripheral blood mononuclear cells (PBMC), and contribute to the anti-inflammatory effect of LDRT. It also exerted anti-inflammatory effects by regulating mitochondrial growth differentiation factor 15 (GDF15). After low-level radiation, the MMP-13 (matrix metalloproteinases-13) and the ADAMTS5 (recombinant a disintegrin and metalloproteinase with thrombospondin-5) decreased, the Col2a1 (collagen type 2) increased in chondrocytes. In the existing clinical studies, most patients can achieve relief of joint pain and recovery of joint mobility after irradiation, and the patients have good feedback on the efficacy. The adverse reactions (acute reactions and carcinogenic risks) caused by LDRT in the treatment of OA are also discussed. During the treatment of OA, a few patients have symptoms such as redness, dryness or itching at the joint skin, and the symptoms are mild and do not require further treatment. Patients are thus able to tolerate more frequent and longer doses of radiotherapy. In general, LDRT itself has the advantages of non-invasive, less adverse reactions, and shows the effect of pain relief and movement improvement in the treatment of OA. Therefore, LDRT has a broad application prospect in the treatment of OA.