Anti-rheumatic activities of histone deacetylase (HDAC) inhibitors in vivo in collagen-induced arthritis in rodents

Abstract

Background and purpose: Rheumatoid arthritis (RA) is a chronic inflammatory disease. Histone deacetylase inhibitors (HDACi), a new class of anti-cancer agents, have recently been reported to exhibit potent anti-inflammatory activities. A proof of concept study was carried out with suberoylanilide hydroxamic acid (SAHA) and MS-275, two HDACi currently undergoing clinical investigations for various oncological indications.

Experimental approach: The anti-rheumatic effects of SAHA and MS-275 were assessed in both mouse and rat collagen induced arthritis (CIA) models.

Key results: SAHA exhibited moderate prophylactic efficacy. It attenuated paw swelling due to inflammation, decreased bone erosion in both mice and rats and reduced slightly the RA-induced bone resorption in rats. However, SAHA could not inhibit the onset of arthritis. In contrast, MS-275 displayed dramatic anti-rheumatic activities. In prophylactic intervention, high doses of MS-275 prevented bone erosion and markedly delayed the onset of arthritis; at low doses, MS-275 strongly attenuated paw swelling, bone erosion, and bone resorption associated with RA. Furthermore, the therapeutic efficacy of MS-275 was also documented. After the onset of arthritis, it could stop the disease progression and joint destruction. An anti inflammatory effect of MS-275 was also confirmed through its capacity to decrease serum IL-6 and IL-1beta levels in the CIA induced mouse model. The anti-rheumatic activity of MS-275 was also confirmed through histological observation. No synovial hyperplasia, pannus formation, cartilage or bone destruction were observed in the high dose prophylactic intervention in mice.

Conclusion and implication: This study strongly supported HDACi as an innovative therapeutic strategy for RA.

Figure 1

Prophylactic efficacy of HDACi in mice. CIA was induced as described in the Methods section. Mice were treated with vehicle, prophylactic doses of SAHA, MS-275 or MTX (5 days per week). (a) Arthritic score. Arthritic score was assessed three times weekly after the onset of arthritis. (b) Body weight. The change in body weight was calculated from the body weight of each individual mouse at weeks 5 and 6. (c) Serum IL-6 levels were assessed 3 days before termination of the experiment at day 43. (d) Serum IL-1β levels were assessed 3 days before day 40. Symbols represent mean value with s.e.m. shown. ^*P<0.05, ^**P<0.01, ^***P<0.001, as compared with vehicle treatment; n=10 for each group. (Clinical score: Wilcoxon two sample test; change in body weight: two-tailed independent sample t-test.)

Figure 2

Histological analysis of CIA in mice. The histological analysis was performed with mice hind paw sections stained by H&E. (a) Metatarsal joints from a symptom-free mouse (intact), arthritis-bearing mouse (vehicle) and a mouse treated with MS-275 (10 mg kg⁻¹) (magnification × 125). Synovial hyperplasia, pannus formation and bone and joint destruction were observed in the metatarsal joint of the mouse receiving vehicle treatment. (b) Histological score. Mice were treated with vehicle or prophylactic doses of SAHA, MS-275 or MTX. The histological score was assessed according to the severity of synovial hyperplasia, bone damage and cartilage destruction. Symbols represent mean value with s.e.m. ^*P<0.05, ^**P<0.01, ^***P<0.001; n=10 for each group (Wilcoxon two-sample test), as compared with vehicle treatment of each study.

Figure 3

Prophylactic efficacy of HDACi in rats. Arthritis was induced as described in the Methods section. Rats were treated with vehicle, prophylactic doses of SAHA, MS-275 or MTX (5 day per week). (a) Arthritic score: SAHA prophylactic study. Arthritic score was assessed three times weekly after the onset of arthritis. (b) Arthritic score: MS-275 prophylactic study. Arthritic score was assessed daily after the onset of arthritis. (c) Body weight. The change in body weight was calculated from the body weight of each individual rat at weeks 3 and 4. Symbols represent mean value with s.e.m. shown. ^*P<0.05, ^**P<0.01, ^***P<0.001, as compared with vehicle treatment; see methods section for details of group sizes (5–10) (clinical score: Wilcoxon two sample test; change in body weight: two-tailed independent sample t-test).

Figure 4

Therapeutic efficacy of HDACi in rats with CIA. Rats received daily treatment of vehicle from days 1 to 15 (5 days per week); daily therapeutic intervention of MS-275 or MTX lasted from day 17 to day 28. (a) Arthritic score. Arthritic score was assessed daily after the onset of arthritis. (b) X-ray photo. The X-ray photo was taken of the hind paws of the rats. Arthritis-bearing rats suffered serious bone erosion and joint narrowing. (c) Radiological score. The severity of bone erosion was assessed with the radiological score system. (d) Bone resorption. The bone resorption was measured with micro-CT scan and the BV/TV value was recorded. Symbols represent mean value with s.e.m. ^*P<0.05, ^**P<0.01, ^***P<0.001; n=10 all groups (radiological score: Wilcoxon two-sample test; BV/TV: two-tailed independent sample t-test), as compared with vehicle treatment.