Electroacupuncture Improves Pulmonary Function of Rats with Chronic Obstructive Pulmonary Disease by Down-regulating Inflammatory Reaction and Expression of Macrophage Migration Inhibitory Factor/CD 74-CD 44/p 38 MAPK Signaling in Lung Tissues

Abstract

To observe the effect of electroacupuncture (EA) at "Zusanli" (ST 36) and "Feishu" (BL 13) on pulmonary function, inflammatory reaction and expression of macrophage migration inhibitory factor (MIF) and its receptor complex CD 74-CD 44, etc. in rats with chronic obstructive pulmonary disease (COPD), so as to explore its mechanism underlying improvement of COPD. Thirty male SD rats were randomly divided into normal, model and EA groups (n＝10 in each group). The COPD model was established by intratracheal infusion of Lipopolysaccharide (LPS, 1 mg/mL) and forced smoke-inhaling. EA was applied to bilateral ST 36 and BL 13 for 30 min, once daily for 7 days. The rat's lung function (forced vital capacity [FVC], forced expiratory capacity ratio ([FEV 0.1/FVC] and [FEV 0.3/FVC]) was detected under anesthesia. Pathological changes of the lung tissue were detected by H．E. staining, and the contents of MIF, tumor necrosis factor-α (TNF-α), interleukin-1 β (IL-1 β) and IL-8 in serum, bronchoalveolar lavage fluid (BALF) and lung tissue were assayed by ELISA. The immunoactivity of CD 74 and CD 44 was detected by immunohistochemistry, and the expression levels of MIF, CD 74, CD 44 and p 38 MAPK mRNAs and proteins were examined by quantitative RT-PCR and Western blot, respectively. Compared with the normal group, the FVC, FEV 0.1, FEV 0.3, FEV 0.1/FVC and FEV 0.3/FVC levels were significantly decreased in the model group (P<0.01). After EA treatment, the FVC, FEV 0.1, FEV 0.3, FEV 0.1/FVC and FEV 0.3/FVC were significantly increased (P<0.01, P<0.05), suggesting an improvement of the pulmonary function after EA. H．E. staining showed that the severity of modeling induced alveolar expansion and inflammatory cell infiltration in the lung tissue was relatively milder in the EA group relevant to the model group. The contents of MIF, TNF-α， IL-1 β and IL-8 in the serum, BALF and lung tissues were significantly higher in the model group than in the normal group (P<0.01), and significantly down-regulated in the EA group relevant to the model group (P<0.01). The expression levels of MIF, CD 74, CD 44 and p 38 MAPK mRNAs and proteins and the immunoactivity levels of CD 74, CD 44 in the lung tissue were obviously higher in the model group than those in the normal group (P<0.01), and considerably lower in the EA group than those in the model group (P<0.01). There was a positive correlation between p 38 MAPK and MIF in mRNA and protein expression levels (P<0.01). EA intervention can improve the pulmonary function in COPD rats, which may be related to its effects in inhibiting inflammatory reaction, and MIF/CD 74-CD 44/p 38 MAPK signaling pathway.