Anti-inflammatory effect of chymotrypsin to autoimmune response against CNS is dose-dependent

Multiple sclerosis is an inflammatory autoimmune disease of central nervous system (CNS) in which inflammatory cells release pro-inflammatory cytokines, proteases, and other toxic mediators. Proteases are involved in many aspects of inflammatory process. There are many reports regarding the effect of proteases on inflammation. Chymotrypsin is a serine protease with anti-inflammatory effect. We investigated chymotrypsin effect on experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis. Intra-CSF injection with 0.1 mg/ml, 0.2 mg/ml chymotrypsin, or saline was done on day 7 after EAE induction. Our study demonstrated that 0.1 mg/ml chymotrypsin treatment did not decrease clinical signs, but 0.2 mg/ml chymotrypsin ameliorated clinical signs and manipulated immune response in both brain and spinal cord. Administration of 0.1 mg/ml or 0.2 mg/ml chymotrypsin led to decreased IL-17 along with increased IL-4 and FoxP3 in 0.2 mg/ml chymotrypsin-treated animals. Presumably, chymotrypsin acts in a dose-dependent manner and concentrations of chymotrypsin more than 0.2 mg/ml may have more beneficial effect.