Autophagy is involved in the pathogenesis of experimental autoimmune neuritis in rats

Recent studies have shown that autophagy is involved in peripheral nervous system disease. However, the role of autophagy in the pathogenesis of experimental autoimmune neuritis (EAN) remains unclear. Therefore, EAN was induced by a subcutaneous injection into both hind footpads of synthetic neuritogenic P2(57-81) peptide in male Lewis rats. The clinical evaluation was completed using a 10-point scale method. The histological alteration of sciatic nerves was analyzed by hematoxylin and eosin and luxol fast blue staining. The ultrastructure of sciatic nerves was analyzed by transmission electron microscopy. Expressions of beclin-1 and microtubule-associated protein light chain-3 (LC3) and p62/SQSTM1 were determined by western blot. 3-Methyladenine, the inhibitor of autophagy, was used in this research. Results showed that the clinical scores were significantly increased from day 6 to day 16 after immunization compared with the control group. Compared with the control group, the number of inflammatory cells and the histological score of sciatic nerves were significantly increased, expressions of beclin-1 and LC3-II and the ratio of LC3-II/LC3-I in the sciatic nerve were significantly increased, and the expression of p62 was significantly decreased in the EAN model group. Considerable double-membrane autophagosomes in axons and myelin sheaths of sciatic nerves were observed and the number of autophagosomes in axons and myelin sheaths of sciatic nerves in the EAN model group was obviously increased compared with the control group. 3-Methyladenine ameliorated the neurologic severity of EAN. Our results suggest that autophagy activity in nerve tissue of EAN rats is increased, which may be associated with the pathogenesis of EAN.