Effect of moxibustion on expression of autophagy related molecules in synovial tissues of rheumatoid arthritis rats

OBJECTIVE To observe the effect of moxibustion on expression of autophagy related gene(Atg), serine/threonine protein kinase-uncoordinated 51 like kinase-1 (ULK1), Beclin1 and microtubule associated proteins light chain 3 (LC3) and ultrastructure of synovium in rheumatoid arthritis (RA) rats, so as to explore its mechanisms underlying improvement of RA. METHODS Forty SD rats were randomly divided into normal control, RA model, moxibustion, cigarette-roasting and medication groups (n=8 rats in each group). The RA model was established by keeping the rats in wind, cold and wet environment for 12 h, once a day for 20 days and subcutaneous injection of Freund's adjuvant complete into the sole of the left hind paw. Moxibustion was applied to the left Zusanli (ST36) for 20 min, once a day for 15 days. Rats of the cigarette-roasting group was treated by ignited cigarettes instead of moxa strips. Rats of the medication group was treated by gavage of Tripterygium wilfordii polyglycoside tablet suspension (0.8 mg/100 g) once a day for 15 days. The rats' paw volume of the left hindlimb was measured by using a water-based paw plethysmometer. The synovial tissue of the left plantar joint was harvested at the end of experiments for observing changes of the ultrastructure with transmission electron microscope, and the expression of ULK1, Atg3, Atg5, and Atg12 mRNAs was detected with quantitative real-time PCR and the expression of LC3-Ⅱ and Beclin-1 proteins were detected with Western blot. RESULTS Following modeling, the paw volume of the left hindlimb was significantly increased (P<0.01), while the expression levels of Atg3, Atg5, Atg12 and ULK1 mRNAs, and LC3-Ⅱ and Beclin-1 proteins of the synovial tissue were notably down-regulated in the model group relevant to the normal control group (P<0.01). The increase of the paw volume in the moxibustion and medication groups and the down-regulation of synovial Atg3, Atg12 and ULK1 mRNAs in the 3 intervention groups, and Atg5 mRNA , and LC3-Ⅱ and Beclin-1 proteins in both moxibustion and medication groups were considerably suppressed (P<0.01, P<0.05). The therapeutic effect of moxibustion was apparently superior to that of cigarette-roasting in down-regulating the paw volume, and up-regulating the expression levels of Atg3, Atg5, Atg12 and ULK1 mRNAs, and LC3-Ⅱ and Beclin-1 proteins (P<0.05, P<0.01), and notably weaker than that of medication in up-regulating Atg3 and ULK1 mRNAs (P<0.01), but was comparable to that of medication in up-regulating the expression levels of Atg5 and Atg12 mRNAs, LC3-Ⅱand Beclin-1 proteins (P＞0.05). Results of the ultrastructural observation showed an obvious injury of synovial cells, such as unclear and incomplete nuclear membrane, chromatin condensation, swollen mitochondria with broken crests, cavitation-like degeneration of cytoplasma, and appearance of autophagosomes and lysosomes in the model group, which was relatively milder in the 3 intervention groups. CONCLUSION Moxibustion can reduce the paw edema and inflammatory injury of the plantar synovial tissue in RA rats, which may be related to its effects in up-regulating Atg3, Atg5, Atg12 and ULK1 mRNAs, and LC3-Ⅱ and Beclin-1 proteins to enhance the cellular autophagy. The therapeutic effect of moxibustion is obviously superior to that of cigarette-roasting and medication in relieving swelling.