Background Adenoviral (Ad) vectors expressing anti-inflammatory cytokines are used for therapy in experimental arthritis. Cell recognition and entry is dependent on the initial recognition of the coxsackievirus and adenovirus receptor (CAR) on cells. Recently introducing an Arg-Gly-Asp (RGD) motif in the HI loop of the fibre knob modified the tropism of the virus.1 The RGD motif is capable of mediating a CAR-independent cell entry via interactions with the αvb3 and αvb5 integrins.
Objectives In this study we explored the transfection efficiency of the RGD modified viruses and investigated the effectiveness of intra-articular IL-1Ra overexpression in the collagen-induced arthritis (CIA) model mediated by the RGD modified vector compared to wildtype viruses.
Methods 10e7 pfu of the AdLuc, AdLucRGD, AdmIL-1Ra, or AdmIL-1RaRGD were intra-articularly injected in all experiments. The CIA model was used to compare the wild type and the RGD viruses on their ability to downregulate arthritis. DBA/1 mice were immunised with collagen type II, and boostered 22 days later. Four days after the booster the adenoviral vectors were injected into both knee joints of the mice. Clinical scores of the knee joints were on a scale of 0–3.
Results Twenty-four hours after intra-articular injection of 10e7 pfu virus into normal knee joints, luciferase production in AdlucRGD injected joints was around 22 times higher than in Adluc injected joints. On day 26 of the CIA model, 10e7 pfu of AdLuc, AdLucRGD, AdmIL-1Ra, or AdmIL-1RaRGD were injected into the knee joints. Onset of the CIA was significantly inhibited in the AdmIL-1RaRGD group (clinical score in the knee joints at day 38 was 0.82 ± 0.24) compared to the other groups (clinical scores were 1.57 ± 0.24 for the AdmIL-1Ra group and 1.86 ± 0.21 for the AdLucRGD group).
Conclusion Transduction of the synovial lining cells in normal knee joints was up to 30 times more efficient when the RGD mediated pathway was used. CIA was significantly better inhibited when mIL-1Ra was overexpressed using the RGD adenoviruses for infection compared to the wild type adenovirus.
Dmitriev I, Krasnykh V, Miller CR, Wang M, Kashentseva E, Mikheeva G, Belousova N, Curiel DT. An adenovirus vector with genetically modified fibers demonstrates expanded tropism via utilization of a coxsackievirus and adenovirus receptor-independent cell entry mechanism. J Virol. 1998;72(12):9706–13