Exogenous expression of IL-1Ra and TGF-β1 promotes in vivo repair in experimental rabbit osteoarthritis

Objectives: Potential gene therapy application of single and co-expression of interleukin 1 (IL-1) receptor antagonist (IL-1Ra) and transforming growth factor-beta 1 (TGF-beta 1) to alter disease progression was investigated in an in-vivo rabbit model of osteoarthritis (OA). Method: Sixteen young adult rabbits were randomly and equally divided into four groups: blank control group, IL-1Ra transfection group, TGF-beta 1 transfection group, and IL-1Ra/TGF-beta 1 double transfection group. Histological examinations were performed to monitor disease progression after haematoxylin and eosin (H&E) staining of articular cartilage. Immunohistochemistry was used to detect IL-1Ra and TGF-beta 1 in synovial membrane tissues. Exogenous IL-1Ra and TGF-beta 1 content was assessed in joint lavage fluid using an enzyme-linked immunosorbent assay (ELISA). Results: ELISA measurements from the joint lavage fluid showed high expressions of IL-1Ra and TGF-beta 1 in the single and double transfection groups. Remarkably, concomitant reductions in IL-1 beta and tumour necrosis factor alpha (TNF-alpha) levels were observed in these single and double transfection groups. Radioimmunoassay (RIA)-based detection showed that IL-1 beta and TNF-alpha levels in the gene transfection groups were significantly lower compared to the blank control group, in parallel experiments. Importantly, injection of IL-1Ra and TGF-beta 1 expressing cartilage cells into joints led to a significant inhibition of cartilage matrix degradation. Finally, IL-1Ra and TGF-beta 1 expression in tissues correlated with disease reversal in the experimental group, with improved tissue architecture and collagen deposition. Conclusions: Our results reveal that both single-and double-gene transfection of IL-1Ra and TGF-beta 1 promote extensive repair of damaged cartilage, and double transfections showed better recovery than single transfections, suggesting that coexpression of IL-1Ra and TGF-beta 1 inhibits degeneration and improves repair of articular cartilage in OA.