Kiyohiro Oshima

Localized interleukin-10 gene transfer induces apoptosis of alloreactive T cells via FAS/FASL pathway, improves function, and prolongs survival of cardiac allograft.

We hypothesized that localized IL-10 gene transfer can induce alloreactive T cell apoptosis and tested this hypothesis with liposome-mediated ex vivo intracoronary IL-10 gene transfer using a functional heterotopic allograft heart transplant model in rabbits. Localized IL-10 overexpression prolonged cardiac allograft survival over three folds. In parallel with the time-course of IL-10 overexpression, the percentage of apoptotic CD3+ cells among total CD3+ cells was significantly increased in the gene therapy group (36.5±3.9%) compared with that in the control group (6.2±2.6%, P <0.01) on postoperative day (POD) 3–6, and it was further increased (45.8±5.7%) on POD7–10. Apoptotic CD4+ and CD8+ cells were also significantly increased in the gene group (P <0.01). In contrast, the percentage of apoptotic myocytes significantly decreased from 10.1±0.8% in the control group to 3.5±0.4% in the gene group on POD7–10 (P <0.01). This reduction was inversely correlated with the increase in the percentages of apoptotic CD4+ and CD8+ cells (P <0.01). The percentage of caspase-3 positive myocytes was significantly reduced, although percentages of caspase-3 positive CD4+ and CD8+ cells were markedly increased in the gene group (P <0.01). Moreover, about 60–80% of apoptotic T lymphocytes expressed Fas in the gene group compared with less than 10% in the control group (P <0.01). These results suggest that localized IL-10 gene transfer induces alloreactive T cell apoptosis via the Fas/FasL pathway that may contribute to the alleviated acute rejection, improved cardiac function, and prolonged survival in the IL-10 gene-treated cardiac allografts.

Liposome-Mediated Combinatorial Cytokine Gene Therapy Induces Localized Synergistic Immunosuppression and Promotes Long-Term Survival of Cardiac Allografts

Localized gene transfer has the potential to introduce immunosuppressive molecules only into the transplanted allograft, which would limit systemic side effects, and prolong allograft survival. However, an applicable gene transfer strategy is not available, and the feasible therapeutic gene(s) has not yet been determined. We developed an ex vivo liposome-mediated gene therapy strategy that is able to intracoronary deliver the combination of IL-4 and IL-10 cDNA expression vectors to the allograft simultaneously. We examined the efficiency, efficacy, and cardiac adverse effects of this combinatorial gene therapy protocol using a rabbit functional cervical heterotopic heart transplant model. Although the efficiency was moderate, the expression of both transgenes was long lasting and localized only in the target organ. The mean survival of cardiac allograft was prolonged from 7 to >100 days. Synergism of overexpressed IL-4 and IL-10 in the inhibition of T lymphocyte infiltration and cytoxicity, and modulation of Th1/Th2 cytokine production promote long-term survival of cardiac allografts.