Z-100, Extracted from Mycobacterium tuberculosis Strain Aoyama B, Inhibits the Development of Collagen-Induced Arthritis in Mice

We evaluated the effects of Z-100, extracted from human type Mycobacterium tuberculosis strain Aoyama B, on collagen-induced arthritis (CIA) in mice. One hundred thirty-five DBA-1K mice, 8 weeks of age, were assigned to 9 groups and immunized with bovine type II collagen (CII) or CFA. From the next day, Z-100 at does of 0.004, 0.04 or 0.4 mg/kg B.W./d for 48 d was intradermally injected into the tail base. Methotrexate (MTX) at daily doses of 0.1, 0.3, or 1.0 mg/kg B.W. and cyclophosphamide (CY) and at a daily dose of 5 mg/kg. B.W. were used as reference drugs. The effects of these drugs on CIA mice were evaluated in terms of the incidence of CIA, the arthritis index (AI), and hind paw edema, after which the animals were sacrificed at 49 d, and both anti-CII antibody titer and delayed-type hypersensitivity (DTH) reaction were measured. In the arthritic control groups, the AI and hind paw edema were significantly increased after the second immunization on day 28. The anti-CII antibody titer and DTH reaction were significantly increased compared to normal mice on day 49. Z-100 significantly inhibited the AI at a dose of 0.4 mg/kg/d on day 49, and suppressed the incidence of both CIA and hind paw edema. Increases in both anti-CII antibody titer and DTH reaction in CIA mice were prevented by treatment with Z-100 at 0.4 mg/kg/d. MTX, in a dose-dependent manner, and CY, at a dose of 5 mg/kg/d, inhibited the incidence of CIA, AI hind paw edema, anti-CII antibody titer and DTH reaction in CIA mice. Z-100 at a dose of 0.4 mg/kg was as effective as MTX was at a dose of 0.3 mg/kg against the DTH reaction, and it had no side effects. These results suggest the usefulness of Z-100 in patients with chronic rheumatoid arthritis.