Abstract： Objective To explore the mechanism of glycoprotein,granulocyte macrophage-colony stimulating factor(GM-CSF)targeted inhibitor combined with interleukin(IL)-23 targeted inhibitor in alleviating spinal fibrosis in mice with ankylosing spondylitis(AS).Methods Six healthy subjects(HC group)and six AS patients(AS group)were recruited,and their peripheral venous blood were collected,the serum levels of tumor necrosis factor-α(TNF-α),IL-23,IL-17 and GM-CSF were detected.AS mice model were established.A total of 30 mice were randomly divided into the Control group,the Model group,the IL-17A Inh group(positive control group),the IL-23 Inh group,and the GM-CSF Inh+IL-23 Inh group,with 6 mice in each group.The levels of TNF-α,IL-23,IL-17 and GM-CSF in serum of mice were detected by ELISA.Western blot was used to detect the levels of epithelial mesenchymal transition(EMT)markers E-cadherin,N-cadherin,snail and Vimentin in muscle/ligament tissues around spine,as well as the levels of receptor activator of nuclear factor-κB ligand(RANKL),osteoprotegerin(OPG)and alkaline phosphatase(ALP)in spinal bone tissues.Micro-CT was used to measure the volume of new bone and the mature bone in the left hind paw and spine(L5～6 vertebrae)of mice.Results Compared with the HC group,the levels of TNF-α,IL-23,IL-17 and GM-CSF in serum of patients in the AS group were increased(P<0.05).Compared with the Control group,the levels of TNF-α,IL-23,IL-17 and GM-CSF in serum of mice in the Model group were increased(P<0.05),the relative expression level of E-cadherin was down-regulated(P<0.05),while the relative expression levels of N-cadherin,snail and Vimentin in muscle/ligament tissues around spine were up-regulated(P<0.05),the relative expression level of RANKL in spinal bone tissues was up-regulated(P<0.05),and the volume of new bone in the left hind paw and L5～6 vertebrae of mice increased(P<0.05).Compared with the Model group,the levels of the above indexes in the GM-CSF Inh+IL-23 Inh group were reversed(P<0.05),while there was no significant difference in the above indexes in the IL-23 Inh group(P>0.05).Compared with the Control group,the relative expression levels of OPG and ALP in spinal bone tissues of mice in the Model group were up-regulated(P<0.05).Compared with the Model group,there was no significant difference in the above indexes in the GM-CSF Inh+IL-23 Inh group(P>0.05).Conclusion The combination therapy of GM-CSF targeted inhibitor and IL-23 targeted inhibitor can reduce the inflammation level,alleviate the fibrosis of muscle and ligament tissues around spine,inhibit the expression of RANKL in the spinal bone tissues,reduce new bone formation and pathological bone remodeling,and protect the activity of the spine.