Effect of moxibustion of acupoints for both lung and intestine disorders on lung inflammation and intestinal short-chain fatty acids in asthmatic model rats

Abstract

To explore the mechanism of moxibustion in the treatment of asthmatic inflammation from the point of short-chain fatty acids (SCFAs) in rats with asthma. A total of 48 SD rats (half male and half female) were randomly divided into 4 groups： normal, model, lung treatment and joint-treatment of lung and intestine (joint-treatment), with 12 rats in each group. The asthma model was made by subcutaneous (bilateral back and inguinal regions) and intraperitoneal injection of mixture solution of ovalbumin and aluminium hydroxide gel (on day 1 and 8) and followed by inhalation of atomized 1% ovalbumin (20 min from day 15, once daily for one week). Moxibustion was applied to bilateral "Feishu" (BL13) for rats of the lung treatment group or bilateral "Feishu" (BL13) and "Tianshu" (ST25) for rats of the joint treatment group. One hour after the intervention, the rats in the later three groups were separately given atomized 1% ovalbumin solution inhalation for 20 min. The treatment was conducted for 30 min, once daily for 14 consecutive days. At the end of the intervention, the percentage of inflammatory cells in blood was detected by biochemical method and histopathological changes of the lung were observed after H.E. staining. The inflammatory cells in the bronchoalveolar lavage fluid (BALF) were counted after Wright-Giemsa staining. The mRNA expressions of interleukin (IL)-4, IL-5, IL-13, IL-17, IL-33, leukotriene (LT), thymic stromal lymphopoietin (TSLP) and prostaglandin D2 (PGD2) were detected by real-time PCR, and the contents of SCFAs in rats' feces were detected by gas chromatography-mass spectrometry. Relevant to the normal group, the model group had an obvious increase in the percentages of neutrophils, lymphocytes and eosinophils in the blood, the percentages of neutrophils and eosinophils in the BALF, and in the expression levels of PGD2, TSLP, LT, IL-4, IL-5, IL-13, IL-17 and IL-33 mRNAs in the lung tissues (P<0.01, P<0.05), and a marked decrease in the contents of acetic acid, propionic acid, isobutyric acid, butyric acid and valeric acid in feces (P<0.05, P<0.01). After the treatment, the percentages of neutrophils and lymphocytes in the peripheral blood, eosinophils in the BALF, and the expression levels of PGD2, TSLP, LT, IL-4, IL-17, IL-33 mRNAs in the lung tissues in both the lung treatment and joint treatment groups, as well as neutrophils of BALF, and expression of IL-5 and IL-13 mRNAs in the joint treatment group were significantly down-regulated (P<0.01, P<0.05), while the contents of acetic acid, propionic acid and valerate in the lung treatment group, and acetic acid, propionic acid, isobutyric acid, butyric acid and valeric acid in the joint treatment group were all strikingly increased (P<0.05, P<0.01). The effect of the joint treatment was superior to that of lung treatment in down-regulating the expressions of LT and IL-5 mRNAs (P<0.05, P<0.01) and up-requlating the content of propionic acid (P<0.05). Results of H.E. staining showed thickened alveolar wall, infiltration of a large number of inflammatory cells and interstitial fibrous tissue hyperplasia around the bronchus and scattered arrangement of cells of the lung tissue in the model group, which was relatively milder in both lung treatment and joint treatment groups, particularly the later. Joint treatment of asthma from the lung and intestine can better regulate the contents of intestinal SCFAs and alleviate the inflammatory response of asthmatic model rats, thus, intestinal SCFAs may be involved in the process of moxibustion in improving inflammatory response.