[Efficacy of local injection of RhTNFR: Fc in collagen-induced arthritis of rats].

Objective: To evaluate the efficacy of recombinant human tumor necrosis factor-α receptor II: IgG fusion protein (RhTNFR:Fc) local injection in collagen-induced arthritis (CIA) of rats.

Methods: Twenty-four CIA rats were randomly divided into 3 groups: single therapy (Group I), multiply therapies (Group II) and control (Group III). Group I received normal saline thrice after a single RhTNFR:Fc local treatment while Groups II and III had 4 times of RhTNFR:Fc or normal saline local injection. The severities of right ankle and systemic inflammation were assessed by arthritis index (AI) at baseline and every week after local injection (visits 1, 2, 3 and 4). Serum C reactive protein (CRP) was measured after the last visit. And right ankles were further examined through radiology and pathology.

Results: Local or systemic AI of Group I were significantly lower than that of baseline at visit 1 (P < 0.05), but increased during other visits. And local or systemic AI of Group II gradually decreased at each follow-up, but AI of Group III showed no decline. The radiographic scores (5.70±0.67 and 4.90±0.73), histopathological scores (6.00±0.67 and 3.80±0.91) and serum CRP concentration (7.50±0.87 and 3.09±0.76 µg/ml) of Group I and Group II were lower than those of Group III (6.60±1.26, 7.10±0.7 and 12.15±3.47 µg/ml, P < 0.05). And all these parameters of Group I were higher than those of Group II (P < 0.05).

Conclusion: Local injection of RhTNFR:Fc can effectively alleviate disease activity of CIA and reduce CRP concentration, radiographic and histopathological scores. Multiple therapies show a better efficacy than single injection.