[Effects of Triptolide on the Autophagy in Synovial, Spleen and Thymus of Rats with Adjuvant Arthritis]

Abstract

Objective: To determine the effect of triptolide (TP) on the expression of ATG /LC3-Ⅱ Beclin1 in synovial, spleen, and thymusof rats with adjuvant arthritis (AA).

Methods: Rats were divided for four groups: normal control (NC), model control (MC), leflunomide (LEF) treatment, and triptolide (TP)treatment, with 12 rats in each group.The AA model was established through Freund's complete adjuvant (0.1 mL each) injection into the right foot plantar skin to introduce inflammation and 10 days of tail root injection of 0.05 mL Freund's complete adjuvant for immunity strengthening. Drug administration started 13 days after induction of inflammation. Rats in the NC and MC groups were given normal saline (1 mL/100 g) once a day for 30 days, compared with 5 mg/kg of oral LEF for the rats in the LEF group and 50 μg/kg of oral TP for the rats in the TP group. Paw swelling (E), joint arthritis index(AI) and joint pathological changes of the rats were recorded. The serum expressions of cytokines B lymphocyte stimulating factor (BAFF), interleukin (IL)-1, tumor necrosis factor (TNF) alpha, IL-15,and IL-10 were detected by ELISA. The expressions of Atg5, Atg7, and Atg12 mRNA in synovial, spleen, and thymus of the rats were detected by RT-PCR.The expressions of LC3-Ⅱ and Beclin1 in synovial, spleen, and thymus of the rats were detected by Western blot assay.

Results: The AA model rats had lower serum BAFF, IL-1, TNF alpha, IL-15, and IL-10; lower Atg5and Atg12 mRNA in synovial; lower Atg5 mRNA, Atg7, and Atg12 mRNA in spleen; higher Atg12 mRNA in thymus; and lower LC3-Ⅱ and Beclin1 in synovial, spleen and thymus(P<0.05 or 0.01). TP treatment led to reduced paw swelling and arthritis index; declined Atg7 and Atg12 mRNA in synovial; declined Atg5, Atg7 mRNA and Atg12 mRNA in spleen; decreased Atg5 and Atg7mRNA in thymus; increased Atg12 mRNA in thymus; and increased LC3-Ⅱ and Beclin1 in synovial, spleen and thymus (P<0.05 or 0.01). Compared with rats treated with LEF, TP treated rats had lower TNF-α and BAFF and higher E and IL-15 (P<0.05 or 0.01); as well as decreased expressions of Atg7 mRNA (synovial) and Atg5, Atg7 mRNA (thymus), and increased expressions of Atg12 mRNA (thymus) and Atg5, Atg7, Atg12 mRNA (spleen).

Conclusion: TP regulates autophagy in synovial, thymus and spleen of AA rats, and improves theirjointinflammatory response.

Keywords: Adjuvant arthritis; Atg; Autophagy; LC3-Ⅱ/Beclin1; Synovial inflammation; Triptolide.