Construction of a recombinant adenovirus vector expressing IL-18BP/IL-4 fusion gene and the anti-inflammatory effect induced by this gene on lipopolysaccharide-stimulated synovial fibroblasts.

Objective: To construct a recombinant adenovirus vector for expressing the IL-18 binding protein (IL-18BP)/IL-4 fusion gene and confirm the anti-inflammatory effect of this gene.

Materials And Methods: The recombinant virus expressing IL-18BP/IL-4 fusion protein (AD-IL-18BP/IL-4) was constructed. AD-IL-18BP/IL-4 was used to infect synovial fibroblasts (SF). ELISA and Western blot analysis were used to determine the expressions of the proteins IL-4 and IL-18BP. To investigate the protective effects of this vector on rheumatoid arthritis, SF were infected with AD-IL-18BP/IL-4 and stimulated by LPS (1 microg/ml) 4 h later. The expression levels of TNF-alpha, IL-6, IL-8, and IL-18 in the culture supernatant were detected by ELISA and production of PGE2 and NO was estimated. The protein expression of COX-2, iNOS, and NF-kappaB p50 in treated SF was analyzed by Western blot.

Results: AD-IL-18BP/IL-4 can effectively express the IL-18BP/IL-4 fusion protein. The expressions of TNF-alpha, IL-6, IL-8, and IL-18 were significantly inhibited in LPS-stimulated SF after treatment with AD-IL-18BP/IL-4. The production of PGE2 and NO was significantly decreased. Moreover, NF-kappaB p50, COX-2, and iNOS levels in SF were markedly suppressed by AD-IL-18BP/IL-4.

Conclusion: AD-IL-18BP/IL-4 can suppress the production and expression of inflammatory cytokines such as COX-2, iNOS, and NF-kappaB in LPS-stimulated SF.