IL-1Ra and vIL-10 gene transfer using retroviral vectors ameliorates particle-associated inflammation in the murine air pouch model

Objective: This study examined anti-inflammatory gene therapy to ameliorate tissue responses to ultra high molecular weight polyethylene (UHMWPE) particles in the murine air pouch. Methods: Retroviruses encoding human interleukin-1 receptor antagonist (IL-1Ra), viral interleukin-10 (vIL-10), or LacZ (reporter) genes were injected into murine air pouches stimulated by UHMWPE particles. Pouch membranes and fluids were harvested at 1, 3 and 7 days post gene-transduction, and assayed for markers of inflammation using histological, molecular, and immunological techniques. Results: Real time RT-PCR and ELISA showed a strong production of IL-1beta in pouch tissue and lavage fluid induced by particle stimulation, accompanied by a lower expression of IL-6, TNF-alpha and IL-4. Transduction of IL-1Ra or vIL-10 genes resulted in a significant reduction of IL-1beta both at the mRNA and at the protein level. The gene therapy also resulted in diminution of IL-6 and TNF-alpha expression. In addition, significant elevation of TGF-beta expression was observed in IL-1Ra transduced pouches. Histological analysis revealed that the membranes of pouches transduced with vIL-10 or IL-1Ra were significantly less inflamed than the membranes of non-viral and LacZ-transduced pouches, with less cellular proliferation and lowered monocyte/macrophage influx. Conclusions: IL-1Ra or vIL-10 gene transduction was effective in ameliorating local inflammation by reducing the IL-1 production and subsequent cellular events elicited in response to UHMWPE particles in this model. These findings suggest that IL-1 directed gene therapy might be excellent therapeutic candidates to prevent or retard the inflammatory response to wear debris that contributes to the pathology of aseptic loosening.