Objective To observe the effect of warm acupuncture on the expression of Janus protein tyrosine kinase 2/signal transducer and activator of transcription 3(JAK2/STAT3) signaling pathway and inflammatory factors of articular cartilage in rabbits with knee osteoarthritis(KOA)

so as to explore its underlying mechanisms in improving KOA. Methods New Zea-land rabbits were randomly divided into blank

model

warm acupuncture and medication groups(12 rabbits in each group). The KOA model was prepared by using the right hind limb tubular plaster extension fixation method. The rabbits in the warm acupuncture group received acupuncture of “Neixiyan”(EX-LE4)

“Waixiyan”(ST35)

“Heding”(EX-LE2) and “Zusanli”(ST36)

followed by attaching an ignited moxa-stick segment to the acupuncture-handle. The treatment was conducted for 15 min

once a week for 4 weeks. The rabbits in the medication group received gavage of diclofenac sodium solution(0.35 mg/kg)

once daily for 4 weeks. The dysfunction severity state of the rabbit's knee-joint was evaluated using Lequesne scale(0-3 points)

and the histopathological changes of cartilage were observed under microscope after H.E. staining and the state of distribution of chondrocytes in different layers and the extracellular matrix was assessed using Mankin score(0-6 points). The contents of serum interleukin(IL)-6

tumor necrosis factor-α(TNF-α) and matrix metalloproteinase-9(MMP-9) were measured by using ELISA

and the expression levels of p-JAK2/JAK2

p-STAT3/STAT3 and MMP-9 in knee cartilage tissue were detected using Western blot. Results Compared with the blank group

the Lequesne score

Mankin score

and the contents of serum IL-6

TNF-α and MMP-9

and the ratios of p-JAK2/JAK2 and p-STAT3/STAT3

and the expression level of MMP-9 protein in knee cartilage tissue were significantly increased in the model group(P<0.01). In comparison with the model group

the Lequesne score

Mankin score

contents of serum IL-6

TNF-α and MMP-9

and the ratios of p-JAK2/JAK2 and p-STAT3/STAT3

and the expression of MMP-9 protein in knee cartilage tissue were notably decreased in both the warm acupuncture and medication groups(P<0.01

P<0.05). The levels of Lequesne score

Mankin score

contents of serum IL-6

TNF-α and MMP-9

and the ratios of p-JAK2/JAK2 and p-STAT3/STAT3 in knee cartilage tissue were significantly lower in the warm acupuncture group than in the medication group(P<0.01

P<0.05). No significant difference was found between the warm acupuncture and medication groups in the expression of MMP-9 protein(P>0.05). Outcomes of H.E. showed injury of the perichondrium of knee joint

obvious reduction of the cartilage matrix staining

cystic changes

clustered and disordered arrangement and severe pyknosis and necrosis of the surface cells with reduction of number of cells and increase of vacuoles in the model group

which was milder in both warm acupuncture and medication groups. Conclusion Warm acupuncture can improve motor function and reduce cartilage injury in KOA rabbits

which may be related to its functions in inhibiting the secretion of pro-inflammatory factors and regulating JAK2/STAT3 signaling and downregulating MMP-9 expression in the cartilage tissue.