Study On Discovery Of Active Compounds In The Treatment Of Osteoarthritis And Psoriasis

Osteoarthritis（OA）is a progressive joint degenerative disease,also known as degenerative arthritis,senile arthritis and proliferative arthritis.Clinical symptoms of osteoarthritis include chronic joint pain,stiffness,swelling and joint deformities.According to the progress of the disease,step-by-step treatment is mainly adopted at present,including basic treatment dominated by physiotherapy and action support therapy,drug treatment dominated by analgesic drugs and symptomatic slow-acting drugs for osteoarthritis,restorative treatment dominated by arthroscopic surgery and cartilage repair,as well as reconstruction treatment dominated by joint replacement at the end of the disease.Among them,drug treatment is the first-line treatment of osteoarthritis.Up to now,there is no drug that can cure osteoarthritis.The research and development of treatment strategies are mainly focused on relieving inflammatory joint pain and improving cartilage/subchondral bone lesions.Small molecular compounds with anti-inflammatory effects,osteoclastogenesis inhibitory activity and chondrocyte protection are expected to become potential therapeutical drugs for osteoarthritis.So far,it has been found that the most important signal pathway related to osteoclast differentiation is composed of nuclear factorκB receptor activator ligand（RANKL）,nuclear factorκB receptor activator（RANK）and osteoprotegerin.After binding to the RANK receptor on the surface of osteoclast progenitor cells,RANKL initiates the differentiation and formation of osteoclasts and inhibits the apoptosis of osteoclasts at the same time.Through the osteoclast differentiation system of RAW264.7 cells induced by RANKL and macrophage colony stimulating factor（M-CSF）,betulinic acid derivatives with significant osteoclastogenesis inhibitory activity and low cytotoxicity were obtained.Then,using the classical macrophage system stimulated by bacterial lipopolysaccharide（LPS）,it was found that the compound with osteoclastogenesis inhibitory activity significantly inhibited the production of interleukin-1β（IL-1β）by macrophages.IL-1βplays a key role in maturation and function formation of osteoclasts after differentiation.The results of multiple rounds of screening suggested that betulinic acid derivatives optimized by structural modification had potential osteoclastogenesis inhibitory activity and anti-inflammatory activity.In this study,we further evaluated the therapeutic effect of YCH-1919,a candidate compound with high osteoclastogenesis inhibitory activity,in OA rat model induced by sodium iodoacetate（MIA）.Two kind of behavioral tests,the paw mechanical withdrawal threshold and the weight bearing difference,were measured on the 0^th,3^rd,7^th,10^thand 14^th day after MIA induction.On the 3rd day after MIA injection（at the moment the OA indication was established and the pain sensitivity increased notably）,the model animals were divided into four groups averagely:high-dose of YCH-1919group,middle-dose of YCH-1919 group,dexamethasone（Dex）group and vehicle group.On the 4th and 11th day,the compound YCH-1919（100μg,50μg）,the positive drug dexamethasone 125μg,or same volume solvent were injected into the articular cavity of each group.The results showed that the pain behavior of rats in the YCH-1919injection group was dramatically improved.The pain relief degree of the rats injected with YCH-1919 100μg was similar to that of Dex,and there was no weight loss in the former group.The results of pathological section of joint tissue showed that local injection of YCH-1919 obviously improved the loss of articular chondrocytes and proteoglycan.In the meantime,YCH-1919 reduced the formation of osteoclasts in the subchondral bone region and inhibited the occurrence of subchondral bone erosion.Finally,we used RANKL and M-CSF to stimulate RAW 264.7 cells to establish an in vitro osteoclast model,and found that compound YCH-1919 could also markedly decrease the m RNA transcription level of genes related to osteoclast differentiation.In addition,we also carried out part of the pharmacodynamic evaluation of reversible SAHH inhibitor DZ2002 in the treatment of psoriatic skin inflammation.In addition,we also carried out part of the pharmacodynamic evaluation of reversible S-adenosyl-L-homocysteine hydrolase inhibitor DZ2002 in the treatment of psoriatic skin inflammation.It was found that DZ2002 not only significantly alleviated the typical psoriasis-like symptoms,but also reversed the abnormal innate immune response in psoriasis.To sum up,betulinic acid derivatives can prominently inhibit osteoclast differentiation induced by RANKL/M-CSF and inflammatory cytokine IL-1βproduction induced by macrophages.Among them,compound YCH-1919 has a more ideal therapeutic window.In MIA-induced rat OA model,low-frequency intra-articular injection of YCH-1919 can significantly relieve joint pain,improve cartilage destruction and bone remodeling of subchondral bone.The therapeutical effect of YCH-1919 on OA model is similar to that of hormone drug Dex,and does not cause weight loss caused by hormone application.It is expected to obtain a new type of OA therapeutic drug with development prospect through further structural optimization.