The Expression And Significance Of The Wnt/β-catenin Signaling Pathway In Subchondral Bone Of Human Knee Osteoarthritis

Objective:The aim of the study was to detect the expression of the Wnt/β-catenin signaling pathway and its antagonist sclerostin in subchondral bone of knee osteoarthritis(OA) patients,and to determine the potential role of the Wnt/β-catenin signaling pathway in knee osteoarthritis.Methods:The tibial plateaus were obtained from patients(n=45)undergoing total knee replacement for primary knee OA between 2013 and 2014.After gross observation,the cartilage-bone specimens were taken out from the most weight-bearing regions in the internal areas of the medial or lateral plateaus.All specimens were divided into two parts along the coronal plane.One part was used to make the formalin-fixed,decalcified, paraffinembedded coronal osteochondral specimens,from which sections(4um) were stained with Safranin O/fast green for cartilage assessment(Mankin score),staging(mild,moderate and severe), and bone histomorphometry:The thickness of total articular cartilage(TAC),subchondral bone plate(SCP),and the trabecular bone volume(BV/TV) were measured by Image Pro Plus 6.0 imagingsystem.The immunohistochemical staining was employed to detect the expression of β-catenin and sclerostin in osteocyte of subchondral bone;The cartilage was rejected in other part.Western blot test methods were employed to detect the expression of β-catenin,TCF-4 and sclerostin in subchondral bone in each group;RT-PCR methods were employed to detect the m RNA expression of β-catenin,TCF-4 and SOST in subchondral bone in each group.SPSS20.0 was employed the different expression among the groups.Results:(1)In the 45 samples,15 samples were at stage Ⅰ,13 samples were at stage Ⅱ and 17 samples were at stage Ⅲ.The bone histomorphometric study showed that TAC thickness was nagetive correlated with severity of OA(P<0.05);the ratios of BV/TV,and SCP thickness was positively correlated with severity of OA(P<0.05).(2)Immunohistochemical staining showed that the expression levels of β-catenin and sclerostin showed difference in osteocyte of subchondral bone in the mild,moderate and severe OA group with statistical significance(P<0.05).The levels of β-catenin were positively correlated with severity of OA;The levels of sclerostin were negatively correlated with severity of OA(P<0.05).(3)Western blot showed that the expression of β-catenin,TCF-4 and sclerostin showed difference in the mild,moderate and severe OA group with statistical significance(P<0.05).(4)RT-PCR showed that the m RNA expression of β-catenin,TCF-4 and sclerostin showed difference in the mild,moderate and severe OA group with statistical significance(P<0.05).The m RNA expression of β-catenin and TCF-4 were positively correlated with severity of OA;The m RNA expression of sclerostin were negatively correlated with severity of OA(P<0.05).Conclusions:The activation of the Wnt/β-catenin signaling pathway in subchondral bone may contribute to the onset and progress of osteoarthritis(OA).