Study on regulatory effects of warm needling moxibustion on chondrocyte senescence in rats with knee osteoarthritis

ObjectiveTo investigate the effect of warm needling moxibustion on chondrocyte senescence in rats with knee osteoarthritis （KOA）， and to compare its efficacy with that of mild moxibustion.MethodsForty-eight Wistar rats were randomly assigned to ４ groups （n=12）： normal， model， mild moxibustion， and warm needling. KOA was induced by intra-articular injection of monosodium iodoacetate （MIA） into the right knee. Rats in the mild moxibustion and warm needling moxibustion groups received interventions at the acupoints “Futu” （ST32） and “Zusanli” （ST36）， 30 min per session， once every other day for 4 weeks. After intervention， Lequesne MG scores， the right knee joint diameter， and right hind paw pain threshold were assessed. Histopathological changes in the rat knee joints were observed by hematoxylin–eosin （HE） and safranin O staining， and were scored using the Mankin’s and OARSI systems. Serum levels of interleukin-6 （IL-6）， interleukin-18 （IL-18）， and matrix metalloproteinase-13 （MMP-13） were measured by ELISA. Immunohistochemistry （IHC） was performed to detect the expressions of P16INK4A， P21Waf1/Cip1， IL-6， MMP-13， and type II collagen （Collagen-Ⅱ） in cartilage. Western blot was performed to detect the relative protein expression levels of P16INK4A， P21Waf1/Cip1， Collagen-Ⅱ， IL-6， and MMP-13 in cartilage tissue.ResultsCompared with the normal group， the model group showed a significantly higher Lequesne MG score （P<0.01）， an increased diameter of the right knee joint （P<0.01）， and a decreased pain threshold （P<0.01）. Compared with the model group， both treatment groups exhibited significantly lower scores （P<0.01）， reduced joint diameters （P<0.01）， and increased pain thresholds （P<0.01）. Compared with the mild moxibustion group， the warm needling group showed a lower score （P<0.01） and a higher pain threshold （P<0.01）. Histopathological staining revealed degenerative features in the model group， including damage to the superficial cartilage layer and disappearance of the tidemark， while both treatment groups exhibited milder degeneration. Compared with the normal group， both the Mankin’s and OARSI scores were significantly increased in the model group （P<0.01）. Compared with the model group， both scores were decreased in the mild moxibustion and warm needling groups （P<0.01）， and the scores in the warm needling group were significantly lower than those in the mild moxibustion group （P<0.05）. Compared with the normal group， the serum levels of IL-6， IL-18， and MMP-13 were significantly elevated in the model group （P<0.01）； in cartilage tissue， the expressions of P16INK4A， P21Waf1/Cip1， IL-6， and MMP-13 proteins were increased （P<0.01）， while Collagen-Ⅱ expression was reduced （P<0.01）. Compared with the model group， both treatment groups showed decreased serum IL-6， IL-18， and MMP-13 levels， and reduced expression of P16INK4A， P21Waf1/Cip1， IL-6， and MMP-13 proteins in cartilage tissue （P<0.05， P<0.01）， along with increased Collagen-Ⅱ expression （P<0.01）. Furthermore， compared with the mild moxibustion group， the warm needling group exhibited more significant changes in the above indicators （P<0.01， P<0.05）.ConclusionWarm needling moxibustion effectively improves knee osteoarthritis in rats and shows superior efficacy compared with mild moxibustion. Its therapeutic mechanism may be associated with the inhibition of chondrocyte senescence.