Warm needling reduces oxidative damage and inflammation of cartilage in knee osteoarthritis rats

Abstract

To observe the effect of warm needling on the expression of oxidative stress related factors and pro-inflammatory factors in cartilage of mono sodium iodoacetate (MIA) induced knee osteoarthritis (KOA) model rats, so as to explore its mechanisms underlying improvement of KOA. Sixty male Sprague Dawley rats were randomly divided into 5 groups: control, model, acupuncture, moxibustion,warm needling, with 12 rats in each group. Rats of the acupuncture, moxibustion,warm needling groups received manual acupuncture or moxibustion or both stimulation of "Zusanli" (ST36) for 15 minutes, once a day for 21 days beginning from the third day after modeling. The foot volume was measured by drainage method, and the plantar mechanical contraction reflex threshold (mechanical pain threshold, MPT) measured by using an electronic pain meter. After 21 days of treatment, the histopathological changes of knee joint were observed by HE staining, and Mankin score was calculated to evaluate the degree of cartilage destruction. The malondialdehyde (MDA) level was measured by colorimetry, and immunofluorescence staining was used to observe the expression of NOX2, SOD2 or IL-1β. Compared with the control group, the knee joint swelling volume from the 3rd day after modeling, Mankin score, MDA level, and the number of NOX2 and IL-1β positive cells were significantly increased (P<0.01, P<0.05), while the MPT from the 3rd day after modeling, and the number of SOD2 positive cells were considerably decreased (P<0.01) in the model group. After the interventions, the increased levels of the knee joint swelling volume from the 12th day after modeling, and the Mankin score, MDA level, NOX2 and IL-1β positive cells, and the levels of decreased MPT from the 9th day after modeling and SOD2 positive cell number were reversed in the acupuncture, moxibustion,warm needling groups (P<0.05, P<0.01), and the effects of warm needling were significantly superior to those of simple manual acupuncture and simple moxibustion in down-regulating knee joint volume, Mainkin score, MDA le-vel, and NOX2 and IL-1β positive cells, and in up-regulating MPT from the 12th day after modeling, and the number of SOD2 positive cells (P<0.05). No significant differences were found between the acupuncture and moxibustion groups in the levels of all the indexes mentioned above (P>0.05). HE staining showed rough and damaged articular surface, with subchondral neovascularization and moderate connective tissue hyperplasia, and abundant lymphocyte and monocyte infiltration in the model group, which was milder in the acupuncture, moxibustion groups particularly in the warm needling group after 21 days' interventions. Warm needling can relieve knee joint pain, swelling and inflammatory damage in KOA rats, which may be associated with its function in inhibiting oxidative stress and inflammation in the cartilage of KOA. The therapeutic effect of warm needling is better than that of manual acupuncture and moxibustion alone.