title: A new modified animal model of myosin-induced experimental autoimmune myositis enhanced by defibrase.
abstract: BACKGROUND
  We investigated the effect of defibrase (a proteolytic enzyme extraction of Agkistrodon halys venom) on experimental autoimmune myositis (EAM) in guinea pigs and explored the option of using a modified pig model of EAM to enhance the study of this disease.
  
  
  METHODS
  Guinea pigs were divided into 3 groups: group A (control group) was immunized with complete Freund adjuvant (CFA), then received 6 injections of saline weekly; group B (EAM group) was immunized with partially purified rabbit myosin emulsified with CFA, then received an injection of saline; group C (EAM + defibrase group) was immunized with purified rabbit myosin emulsified with CFA, then received an injection of defibrase. The animals were observed for their general health condition and the body weight was measured daily. Plasma levels of fibrinogen and creatine kinase (CK) were determined. Muscle tissues were examined histologically.
  
  
  RESULTS
  After immunizations for 6 weeks, incidence of EAM in groups A, B and C was 0 (0/7), 83.3% (10/12) and 100% (15/15), respectively. Guinea pigs with EAM presented angeitis symptoms of muscle weakness. Histological analysis revealed a significant difference. Muscles with EAM had scattered or diffuse inflammatory manifestations, which are also common pathological features of human idiopathic polymyositis (IPM). Defibrase-treated animals displayed extensive inflammation and fiber necrosis compared with the EAM group (histological score: 2.80 ±1.15 vs. 1.88 ±1.32, p < 0.05). Severity of inflammation of group B was mainly mild to moderate; 16.7% (2/12) of animals developed severe inflammation. Incidence of severe inflammation with a score up to 4 in group C was 40% (6/15).
  
  
  CONCLUSIONS
  Defibrase can exacerbate myosin-induced EAM; thus a new modified model was generated.
authors.affiliation: Department of Neurology, Chinese PLA General Hospital, Beijing, China; Department of Neurology, Chinese PLA Wuhan General Hospital of Guangzhou Military Command, Wuhan, China.
authors.forename: Luo
authors.initials: L
authors.lastname: Wen-Jing
authors.affiliation: Department of Neurology, Chinese PLA General Hospital, Beijing, China.
authors.forename: Pu
authors.initials: P
authors.lastname: Chuan-Qiang
authors.affiliation: Department of Neurology, Chinese PLA Wuhan General Hospital of Guangzhou Military Command, Wuhan, China.
authors.forename: Li
authors.initials: L
authors.lastname: Hong-Hua
authors.affiliation: Department of Neurology, Chinese PLA General Hospital, Beijing, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Xiang-Hui
authors.affiliation: Department of Neurology, Chinese PLA General Hospital, Beijing, China.
authors.forename: Liu
authors.initials: L
authors.lastname: Jie-Xiao
keywords: defibrase; experimental autoimmune myositis; fibrinogen; guinea pigs; idiopathic polymyositis