Inhibition of collagen-induced arthritis in mice by inducible AAV-mediated transfer of viral IL-10 gene

Objective

The purpose of this study is to assess the therapeutic efficiency of vIL-10 gene transfer mediated by a tetracycline-inducible AAV vector in mice model of arthritis.

Method

The AAV-tetON-vIL10 vector (1.5 × 10⁹ pi) was injected intramuscularly 3 weeks before immunization with bovine type II collagen. DBA1 mice with collagen-induced arthritis then received dox diet (200 mg/kg) from days 21–42 of immunization. Severity of arthritis was determined by measuring paw swelling, evaluating X-ray and histological paw features. Expression of vIL-10 was measured by RT-PCR and ELISA in injected muscle.

Results

The incidence and severity of arthritis was significantly reduced at macroscopic, radiologic and histologic levels in the group of animals treated with AAV-TetON-vIL10 vector plus doxycycline, compared with vector alone or control groups (AAV-GFP + doxycycline and doxycycline alone). Only 30% of mice developed arthritis against 89% in controls. Mice from the control groups showed earlier onset of arthritis, with clinical signs of the disease starting on day 32.63 ± 4.07, compared with 36.67 ± 3.51 in the AAV-TetON-vIL10 injected group treated with doxycycline (P = 0.033). The benefit was not only observed at the inflammatory level, but also on cartilage and bone erosion (P < 0.01). Gene transfer led to detectable levels of vIL-10 transcript and protein in the AAV-tetON-vIL10 injected muscles, inducible by doxycycline. A basal transcription of vIL-10 was observed, significantly induced by doxycycline (× 2.7, P = 0.0094), leading to a higher secretion of vIL-10 protein (284.4 ± 358.2 versus 181.9 ± 130.2 pg/mg protein, NS). The biodistribution of the vector genome beyond the site of injection was determined by RT-PCR, vIL-10 transcript was found in five out of 29 spleens.

Conclusion

These data support AAV-tetON-vIL10 as a valuable approach for anti-inflammatory gene therapy in RA.