Prevention of chronic deterioration of heart allograft by recombinant adeno-associated virus-mediated heme oxygenase-1 gene transfer.

Allograft deterioration is the major obstacle to organ transplantation as a long-term treatment of end-stage heart failure. In this study, we transduced the antioxidant gene, heme oxygenase-1 (HO-1), to heart grafts using a recombinant adeno-associated viral vector (rAAV) in a rat heart transplantation model and investigated its potentiality in prevention of chronic graft deterioration. rAAV/HO-1 was administered to heart grafts through the coronary arteries during cold preservation. We investigated the expression patterns and activities of transgene, graft survival, graft histomorphology, and relevance of HO-1 expression on graft survival and chronic graft deterioration by itself. Long-term allograft survival can be achieved by rAAV/HO-1-mediated stable transgene expression. The development of graft arteriosclerosis and interstitial fibrosis was prevented in rAAV/HO-1-transduced allografts on day 100. rAAV/HO-1-mediated long-term graft protection was accompanied by remarkable downregulation of the intragraft mRNA level of macrophage migration inhibitory factor, tumor necrosis factor-alpha, and transforming growth factor-beta1. Blockage of HO activities by zinc protoporphyrin IX at different posttransplant phases showed that the stable expression of HO-1 is a prerequisite for both survival of grafts and prevention of graft arteriosclerosis. rAAV/HO-1 gene transfer represents a novel therapeutic approach to prevent chronic allograft deterioration in clinical heart transplantation.

Tsui TY ，Wu X ，Lau CK ，Ho DW ，Xu T ，Siu YT ，Fan ST ... -  《-》

Systemic rather than local heme oxygenase-1 overexpression improves cardiac allograft outcomes in a new transgenic mouse.

Heme oxygenase-1 (HO-1), a rate-limiting enzyme in heme catabolism, exhibits potent antioxidant and anti-inflammatory properties. We developed HO-1 transgenic (Tg) mice using a rat HO-1 genomic transgene under the control of the endogenous promoter. Transgene expression was demonstrated by RT-PCR in all studied tissues, and a modest HO-1 overexpression was documented by Western, ELISA, and enzyme activity assays. To assess the effect of local vs systemic HO-1 in the acute rejection response, we used Tg mice as organ donors or recipients of MHC-incompatible heart grafts. In the local HO-1 overexpression model, Tg allografts survived 10.5 +/- 0.7 days (n = 10), compared with 6.5 +/- 0.4 days (n = 6) for wild-type donor controls (p = 0.0001). In the systemic HO-1 overexpression model, Tg recipients maintained allografts for 26.8 +/- 3.4 days (n = 10), compared with 6.3 +/- 0.1 days (n = 12) in wild-type controls (p = 0.00009). Inhibition of HO activity by treatment with tin protoporphyrin blunted survival advantage in Tg mice and resulted in acute graft rejection (n = 3). Increased carboxyhemoglobin levels were consistently noted in Tg mice. Comparisons of grafts at day 4 indicated that HO-1 overexpression was inversely associated with vasculitis/inflammatory cell infiltrate in both models. Hearts transplanted into Tg recipients showed decreased CD4(+) lymphocyte infiltration and diminished immune activation, as judged by CD25 expression. Thus, although local and systemic HO-1 overexpression improved allograft outcomes, systemic HO-1 led to a more robust protection and resulted in a significant blunting of host immune activation. This Tg mouse provides a valuable tool to study mechanisms by which HO-1 exerts beneficial effects in organ transplantation.

Araujo JA ，Meng L ，Tward AD ，Hancock WW ，Zhai Y ，Lee A ，Ishikawa K ，Iyer S ，Buelow R ，Busuttil RW ，Shih DM ，Lusis AJ ，Kupiec-Weglinski JW ... -  《JOURNAL OF IMMUNOLOGY》

Targeting of interleukin-10 is superior to cytotoxic T-lymphocyte associated antigen 4 with human immunoglobulin G(1) for the prevention of chronic allograft deterioration in organ transplantation.

Genetic manipulation of the allograft is an attractive approach to prevent the graft against chronic deterioration through stable expression of immunomodulatory or protective genes. However, the best strategy for prevention of chronic allograft deterioration remains unclear. The efficacies of adeno-associated viral vector-mediated stable expression of indoleamine 2,3-dioxygenase (IDO), cytotoxic T-lymphocyte associated antigen 4 with human immunoglobulin G(1) (CTLA4Ig) or interleukin-10 (IL-10) in the prevention of chronic allograft deterioration were compared in a rat heart transplantation model. Transduction of grafts with IL-10 significantly prolonged allograft survival, whereas transduction of grafts with IDO did not improve graft survival compared to controls. Analysis of long-term survived heart allografts showed that both CTLA4Ig and IL-10 could significantly reduced the T cells and macrophage infiltration. However, stable expression of CTLA4Ig failed to prevent the development of transplant arteriosclerosis. By contrast, IL-10 suppressed the development of transplant arteriosclerosis effectively. The suppressive effects of IL-10 in preventing the development of chronic allograft deterioration were associated with lower transcript levels of transforming tumor growth factor beta 1 and macrophage migration inhibitory factor in the graft. In addition, higher transcript levels of heme oxygenase-1 were found in IL-10-transduced allograft. Targeting on IL-10 is superior to CTLA4Ig or IDO for the treatment of chronic allograft deterioration.

Xu T ，Haering C ，Lau CK ，Obed A ，Ma J ，Doenecke A ，Scherer MN ，Schnitzbauer AA ，Fan ST ，Schlitt HJ ，Tsui TY ... -  《-》

rAAV-mediated stable expression of heme oxygenase-1 in stellate cells: a new approach to attenuate liver fibrosis in rats.

Liver fibrosis is the consequence of activation of hepatic stellate cells mediated by persistent or recurrent liver injury, where oxidative stress or inflammatory response resulting from immune cells and cytokines are involved. Targeting of hepatic stellate cells could be an important strategy for the therapy of liver fibrosis. In this study, we showed a tropism of recombinant adeno-associated virus (rAAV, serotype 2) with high efficiency in transduction of a homeostatic gene, heme oxygenase-1 (HO-1), to activated stellate cells. The binding of rAAVs to stellate cells increased significantly after serum-stimulated activation compared with quiescent status. Portal injection of rAAVs to normal or carbon tetrachloride (CCl(4))-induced liver fibrosis showed a distinct distribution of rAAV binding. The majority of injected rAAVs bound to the cells in fibrotic areas that were associated with higher expression levels of fibroblast growth factor receptor-1alpha at 2 hours after administration. Isolation of different types of cells from CCl(4)-induced fibrotic livers showed predominant expression of transgene in stellate cells after rAAV/HO-1 administration on day 3 and remained stable for 12 weeks. In addition, HO-1-transduced stellate cells showed reduced transcript levels of type 1 collagen and impaired proliferative ability compared with controls. With this approach, the severity of established micronodular cirrhosis was markedly reduced. In conclusion, these findings suggest a new approach for the treatment of liver fibrosis using adeno-associated virus-mediated gene transfer.

Tsui TY ，Lau CK ，Ma J ，Wu X ，Wang YQ ，Farkas S ，Xu R ，Schlitt HJ ，Fan ST ... -  《HEPATOLOGY》

Gene therapy strategy for long-term myocardial protection using adeno-associated virus-mediated delivery of heme oxygenase gene.

Ischemia and oxidative stress are the leading mechanisms for tissue injury. An ideal strategy for preventive/protective therapy would be to develop an approach that could confer long-term transgene expression and, consequently, tissue protection from repeated ischemia/reperfusion injury with a single administration of a therapeutic gene. In the present study, we used recombinant adeno-associated virus (rAAV) as a vector for direct delivery of the cytoprotective gene heme oxygenase-1 (HO-1) into the rat myocardium, with the purpose of evaluating this strategy as a therapeutic approach for long-term protection from ischemia-induced myocardial injury. Human HO-1 gene (hHO-1) was delivered to normal rat hearts by intramyocardial injection. AAV-mediated transfer of the hHO-1 gene 8 weeks before acute coronary artery ligation and release led to a dramatic reduction (>75%) in left ventricular myocardial infarction. The reduction in infarct size was accompanied by decreases in myocardial lipid peroxidation and in proapoptotic Bax and proinflammatory interleukin-1beta protein abundance, concomitant with an increase in antiapoptotic Bcl-2 protein level. This suggested that the transgene exerts its cardioprotective effects in part by reducing oxidative stress and associated inflammation and apoptotic cell death. This study documents the beneficial therapeutic effect of rAAV-mediated transfer, before myocardial injury, of a cytoprotective gene that confers long-term myocardial protection from ischemia/reperfusion injury. Our data suggest that this novel "pre-event" gene transfer approach may provide sustained tissue protection from future repeated episodes of injury and may be beneficial as preventive therapy for patients with or at risk of developing coronary ischemic events.

Melo LG ，Agrawal R ，Zhang L ，Rezvani M ，Mangi AA ，Ehsan A ，Griese DP ，Dell'Acqua G ，Mann MJ ，Oyama J ，Yet SF ，Layne MD ，Perrella MA ，Dzau VJ ... -  《-》