Allograft transduction of IL-10 prolongs survival following orthotopic liver transplantation

T cell responsiveness to IL-10 defines the immunomodulatory effect of costimulation blockade via anti-CD154 and impacts transplant survival

Costimulation blockade (CoB)-based immunotherapy is a promising alternative to immunosuppression for transplant recipients; however, the current limited understanding of the factors that impact its efficacy restrains its clinical applicability. In this context, pro- and anti-inflammatory cytokines are being recognized as having an impact on T cell activation beyond effector differentiation. This study aims at elucidating the impact of direct IL-10 signaling in T cells on CoB outcomes. We used a full-mismatch skin transplantation model where recipients had a T cell-restricted expression of a dominant negative IL-10 receptor (10R-DN), alongside anti-CD154 as CoB therapy. Unlike wild-type recipients, 10R-DN mice failed to benefit from CoB. This accelerated graft rejection correlated with increased accumulation of T cells producing TNF-α, IFN-γ, and IL-17. In vitro experiments indicated that while lack of IL-10 signaling did not change the ability of anti-CD154 to modulate alloreactive T cell proliferation, the absence of this pathway heightened TH1 effector cell differentiation. Furthermore, deficiency of IL-10 signaling in T cells impaired Treg induction, a hallmark of anti-CD154 therapy. Overall, these findings unveil an important and novel role of IL-10 signaling in T cells that defines the success of CoB therapies and identifies a target pathway for obtaining robust immunoregulation.

EnILs: A General Ensemble Computational Approach for Predicting Inducing Peptides of Multiple Interleukins

Interleukins (ILs) are a group of multifunctional cytokines, which play important roles in immune regulations and inflammatory responses. Recently, IL-6 has been found to affect the development of COVID-19, and significantly elevated levels of IL-6 cytokines have been reported in patients with severe COVID-19. IL-10 and IL-17 are anti-inflammatory and proinflammatory cytokines, respectively, which play multiple protective roles in host defense against pathogens. At present, a number of machine learning methods have been proposed to predict ILs inducing peptides, but their predictive performance needs to be further improved, and the inducing peptides of different ILs are predicted separately, rather than using a general approach. In our work, we combine the statistical features of peptide sequence with word embedding to design a general ensemble model named EnILs to predict inducing peptides of different ILs, in which the predictive probabilities of random forest, eXtreme Gradient Boosting and neural network are integrated in an average way. Compared with the state-of-the-art machine learning methods, EnILs shows considerable performance in the prediction of IL-6, IL-10, and IL-17 inducing peptides. In addition, we predict the most promising IL-6 inducing peptides in Severe Acute Respiratory Syndrome Coronavirus 2 spike protein in the case study for further experimental verification.

Role of Glycogen Synthase Kinase-3 in Interferon-γ-Mediated Immune Hepatitis

Glycogen synthase kinase-3 (GSK-3), a serine/threonine kinase, is a vital glycogen synthase regulator controlling glycogen synthesis, glucose metabolism, and insulin signaling. GSK-3 is widely expressed in different types of cells, and its abundant roles in cellular bioregulation have been speculated. Abnormal GSK-3 activation and inactivation may affect its original bioactivity. Moreover, active and inactive GSK-3 can regulate several cytosolic factors and modulate their diverse cellular functional roles. Studies in experimental liver disease models have illustrated the possible pathological role of GSK-3 in facilitating acute hepatic injury. Pharmacologically targeting GSK-3 is therefore suggested as a therapeutic strategy for liver protection. Furthermore, while the signaling transduction of GSK-3 facilitates proinflammatory interferon (IFN)-γ in vitro and in vivo, the blockade of GSK-3 can be protective, as shown by an IFN-γ-induced immune hepatitis model. In this study, we explored the possible regulation of GSK-3 and the potential relevance of GSK-3 blockade in IFN-γ-mediated immune hepatitis.

Computer-aided designing of immunosuppressive peptides based on IL-10 inducing potential

In the past, numerous methods have been developed to predict MHC class II binders or T-helper epitopes for designing the epitope-based vaccines against pathogens. In contrast, limited attempts have been made to develop methods for predicting T-helper epitopes/peptides that can induce a specific type of cytokine. This paper describes a method, developed for predicting interleukin-10 (IL-10) inducing peptides, a cytokine responsible for suppressing the immune system. All models were trained and tested on experimentally validated 394 IL-10 inducing and 848 non-inducing peptides. It was observed that certain types of residues and motifs are more frequent in IL-10 inducing peptides than in non-inducing peptides. Based on this analysis, we developed composition-based models using various machine-learning techniques. Random Forest-based model achieved the maximum Matthews's Correlation Coefficient (MCC) value of 0.59 with an accuracy of 81.24% developed using dipeptide composition. In order to facilitate the community, we developed a web server "IL-10pred", standalone packages and a mobile app for designing IL-10 inducing peptides (http://crdd.osdd.net/raghava/IL-10pred/).

Modulation of Alloimmune Responses by Interleukin-10 Prevents Rejection of Implanted Allogeneic Smooth Muscle Cells and Restores Postinfarction Ventricular Function

Interleukin-10 (IL-10) gene transduction into allogeneic smooth muscle cells (SMCs) was evaluated to improve the long-term benefits of allogeneic cell transplantation into infarcted myocardium. Allogeneic cells, including SMCs, have been demonstrated to restore cardiac function and repair the infarcted myocardium, but late rejection of the transplanted cells by the host immune system may reverse the benefits of cell therapy. In a rat myocardial infarction model, three groups of rats were injected with either unmodified autologous, unmodified allogeneic, or allogeneic + IL-10 SMCs into the infarct region. Three weeks later, most of the allogeneic cells were rejected, whereas autologous cells were engrafted in the myocardium. IL-10 gene transduction of the allogeneic SMCs significantly improved the cell survival. To understand the mechanism of this improved survival, we evaluated the host immune responses against the SMCs. Allogeneic SMCs expressing IL-10 decreased leukocyte-mediated cytotoxicity in coculture, decreased the number of cytotoxic CD8+ T-cells, and increased the number of CD4+CD25+ regulatory T-cells in vitro and in vivo. Furthermore, IL-10 prevented the production of antidonor antibodies by the recipients against the allogeneic SMCs. Transplantation of unmodified autologous SMCs, but not unmodified allogeneic SMCs, significantly improved fractional shortening and left ventricular dimensions compared to the media-injected control group. However, IL-10 gene-enhanced allogeneic SMCs improved ventricular function, increased wall thickness, and decreased scar length in association with their enhanced survival. We conclude that IL-10 gene-enhanced cell therapy with allogeneic SMCs prevents detrimental alloimmune responses in the recipient, thereby increasing the survival of transplanted allogeneic SMCs and more effectively restoring cardiac function.

A vaccinia virus armed with interleukin-10 is a promising therapeutic agent for treatment of murine pancreatic cancer

PURPOSE

Vaccinia virus has strong potential as a novel therapeutic agent for treatment of pancreatic cancer. We investigated whether arming vaccinia virus with interleukin-10 (IL10) could enhance the antitumor efficacy with the view that IL10 might dampen the host immunity to the virus, increasing viral persistence, thus maximizing the oncolytic effect and antitumor immunity associated with vaccinia virus.

EXPERIMENTAL DESIGN

The antitumor efficacy of IL10-armed vaccinia virus (VVLΔTK-IL10) and control VVΔTK was assessed in pancreatic cancer cell lines, mice bearing subcutaneous pancreatic cancer tumors and a pancreatic cancer transgenic mouse model. Viral persistence within the tumors was examined and immune depletion experiments as well as immunophenotyping of splenocytes were carried out to dissect the functional mechanisms associated with the viral efficacy.

RESULTS

Compared with unarmed VVLΔTK, VVLΔTK-IL10 had a similar level of cytotoxicity and replication in vitro in murine pancreatic cancer cell lines, but rendered a superior antitumor efficacy in the subcutaneous pancreatic cancer model and a K-ras-p53 mutant-transgenic pancreatic cancer model after systemic delivery, with induction of long-term antitumor immunity. The antitumor efficacy of VVLΔTK-IL10 was dependent on CD4(+) and CD8(+), but not NK cells. Clearance of VVLΔTK-IL10 was reduced at early time points compared with the control virus. Treatment with VVLΔTK-IL10 resulted in a reduction in virus-specific, but not tumor-specific CD8(+) cells compared with VVLΔTK.

CONCLUSIONS

These results suggest that VVLΔTK-IL10 has strong potential as an antitumor therapeutic for pancreatic cancer.

Interleukin-10-1082G/A polymorphism and acute liver graft rejection: A meta-analysis

AIM: To investigate the association between interleukin (IL)-10-1082 (G/A) promoter polymorphism and acute rejection (AR) in liver transplant (LT) recipients.

METHODS: Two investigators independently searched the Medline, Embase, China National Knowledge Infrastructure, and Chinese Biomedicine Databases. Summary odds ratios (ORs) and 95% CIs for IL-10-1082 G/A polymorphism and AR were calculated in a fixed- and a random-effects model as appropriate.

RESULTS: This meta-analysis included seven case-control studies, which comprised 652 cases of LT recipients in which 241 cases developed AR and 411 cases did not develop AR. Overall, the variant A allele was not associated with AR risk when compared with the wild-type G allele (OR = 0.94, 95% CI: 0.64-1.39). Moreover, similar results were observed when the AA genotype was compared with the AG/GG genotype (OR = 1.05, 95% CI: 0.55-2.02). When stratifying for ethnicity, no significant association was observed among either Caucasians or Asians. Because only one study was performed in Asian patients, the result of subgroup analysis by ethnicity would not be reliable for Asians. Limiting the analysis to the studies with controls in the Hardy-Weinberg equilibrium, the results were persistent and robust. No publication bias was found in the present study.

CONCLUSION: This meta-analysis suggests that IL-10-1082 G/A polymorphism may be not associated with AR risk in LT recipients among Caucasians.

Prolonged amelioration of acute lung allograft rejection by sequential overexpression of human interleukin-10 and hepatocyte growth factor in rats

The effect of prolonged electroporation-mediated human interleukin-10 (hIL-10) overexpression 24 hours before transplantation, combined with sequential human hepatocyte growth factor (HGF) overexpression into skeletal muscle on day 5, on rat lung allograft rejection was evaluated. Left lung allotransplantation was performed from Brown-Norway to Fischer-F344 rats. Gene transfer into skeletal muscle was enhanced by electroporation. Three groups were studied: group I animals (n = 5) received 2.5 μg pCIK-hIL-10 (hIL-10/CMV [cytomegalovirus] early promoter enhancer) on day -1 and 80 μg pCIK-HGF (HGF/CMV early promoter enhancer) on day 5. Group II animals (n = 4) received 2.5 μg pCIK-hIL-10 and pUbC-hIL-10 (hIL-10/pUbC promoter) on day -1. Control group III animals (n = 4) were treated by sham electroporation on days -1 and 5. All animals received daily nontherapeutic intraperitoneal dose of cyclosporin A (2.5 mg/kg) and were sacrificed on day 15. Graft oxygenation and allograft rejection were evaluated. Significant differences were found between study groups in graft oxygenation (Pao(2)) (P = .0028; group I vs. groups II and III, P < .01 each). Pao(2) was low in group II (31 ± 1 mm Hg) and in group III controls (34 ± 10 mm Hg), without statistically significant difference between these 2 groups (P = .54). In contrast, in group I, Pao(2) of recipients sequentially transduced with IL-10 and HGF plasmids was much improved, with 112 ± 39 mm Hg (vs. groups II and III; P < .01 each), paralleled by reduced vascular and bronchial rejection (group I vs. groups II and III, P < .021 each). Sequential overexpression of anti-inflammatory cytokine IL-10, followed by sequential and overlapping HGF overexpression on day 5, preserves lung function and reduces acute lung allograft rejection up to day 15 post transplant as compared to prolonged IL-10 overexpression alone.

Suppressive effects of interleukin-18 on liver function in rat liver allografts

BACKGROUND

Interleukin-18 (IL-18) is a potent proinflammatory cytokine that augments both innate and acquired immune responses. It is also a crucial regulator of lymphocyte production of interferon-γ (IFN-γ), which can promote acute cellular rejection of transplanted solid organs.

METHODS

To evaluate the role of IL-18 in liver transplantation, we constructed an adenoviral vector encoding IL-18 binding protein (Adex-IL18bp), which specifically suppressed the biologic activity of IL-18, and examined the effect of this suppression on liver allografts by using a high-responder rat model (ACI to Lewis) of orthotopic liver transplantation (OLTx). Donor rats were given one intravenous injection of Adex-IL18bp or Adex-LacZ (control vector) 2 d before OLTx.

RESULTS

Seven days after OLTx, overexpression of IL-18bp resulting from the adenovirus gene transfer was associated with significantly decreased serum alanine aminotransferase levels and less histologic hepatic injury in recipient rats with Adex-IL18bp-pretreated donors compared with Adex-LacZ controls. Adex-IL18bp pretreatment also significantly prolonged rat/allograft survival, inhibited expression of IFN-γ, and reduced levels (versus control values) of both CXCL10 and CX3CL1, which can be induced by IFN-γ.

CONCLUSION

These results suggest that IL-18 has an important role in liver allograft rejection through IFN-γ and chemokines and that specific suppression of IL-18 may improve liver function early after transplantation.

PPARalpha ligand WY14643 reduced acute rejection after rat lung transplantation with the upregulation of IL-4, IL-10 and TGFbeta mRNA expression

BACKGROUND

The peroxisome proliferators-activated receptor-alpha (PPARalpha) is important in lipid metabolism and regulation of inflammation. Recent studies have demonstrated the immunoregulatory effects of PPARalpha. This investigated the immunosuppressive effects of PPARalpha using its ligand, WY14643, on acute lung allograft rejection in a rat model and its mechanism of action.

METHOD

The left lungs were transplanted orthotopically from Brown-Norway donors to F344 recipients. The recipients were then divided into control and WY14643 treatment groups. The allograft rejection was evaluated by daily chest X-ray imaging and was evaluated histologically on Day 7 after transplantation. The cytokine messenger RNA (mRNA) expression at Days 3 and 5 were also evaluated in allografts and recipient spleens.

RESULTS

The radiologic and histologic findings indicated that treatment with the WY14643 reduced acute allograft rejection. WY14643 also significantly extended the allograft survival time. This amelioration of acute rejection by WY14643 was also associated with up-regulated interleukin (IL)-4, IL-10, and transforming growth factor-beta (TGFbeta) mRNA expression in the lung allografts and spleens.

CONCLUSION

This study demonstrated that the administration of the PPARa ligand, WY14643, ameliorates acute lung allograft rejection in rats. Treatment with WY14643 reduced histopathologic scores, prolonged graft survival, and up-regulated the expression of anti-inflammatory cytokine IL-4, IL-10, and TGFbeta mRNA compared with the control.

Gene therapy in transplantation

Gene therapy is an exciting and novel technology that offers the prospect of improving transplant outcomes beyond those achievable with current clinical protocols. This review explores both the candidate genes and ways in which they have been deployed to overcome both immune and non-immune barriers to transplantation success in experimental models. Finally, the major obstacles to implementing gene therapy in the clinic are considered.

IL-10 secretion increases signal persistence of HEMA-MMA-microencapsulated luciferase-modified CHO fibroblasts in mice

Microencapsulation of cells in a polymer membrane [e.g., poly(hydroxyethyl methacrylate-co-methyl methacrylate) (HEMA-MMA)] has been proposed as a vehicle for the delivery of therapeutic biomolecules, but cells (especially xenogeneic cells) survive only for short times, limiting the utility of this approach. Murine interleukin-10 (mIL-10) has been shown to downregulate the xenogeneic immune response, and we tested the hypothesis that mIL-10 produced by microencapsulated Chinese hamster ovary (CHO) cells would modulate the transplant-site environment leading to prolonged cell function in a xenogeneic model without other immunomodulatory agents. Prior to encapsulation, CHO cells were genetically engineered to express mIL-10 and a firefly bioluminescence protein, luciferase, which allowed for noninvasive tracking of transplanted cells in vivo with the Xenogen IVIS Imaging System. This nondestructive imaging system was sufficiently sensitive to detect photon signal emitted by a single capsule containing around 800 luciferase-transduced CHO (CHO(LUC)) cells in vitro, and to track changes in luciferase expression in vivo over time. Effective modulation of the transplantation-site environment with mIL-10 secreted from capsules was evident by greater luciferase expression at 10 and 21 days after transplantation relative to encapsulated luciferase-transfected cells that did not produce mIL-10. Longer duration effects require further investigation to extend this proof-of-concept study.

Interleukin-10 Gene Transfection of Donor Pancreas Grafts Protects against Rejection after Heterotopic Pancreas Transplantation in a Rat Model

OBJECTIVE

The aim of this study was to assess the effect of immunoregulatory cytokine interleukin-10 (IL-10) gene therapy on pancreas tissue rejection in a heterotopic pancreas transplantation model.

BACKGROUND

Modulation of inflammatory responses by anti-inflammatory cytokines (e.g., IL-10) has been suggested to minimize organ rejection. In this context, modulation of cytokines using gene therapy could be a new therapeutic modality in preventing organ rejection.

METHODS

The study was performed using male inbred Wistar rats as recipients and Sprague-Dawley rats as donors. 24 h before transplantation, groups of rats, named IL-10 (n = 20) and green fluorescent protein (GFP, n = 20), were injected with viral vectors Ad5CMVhIL10 or Ad5CMVGFP. Sham-operated rats (n = 20) underwent saline injection only before transplantation. The pancreatic tissue from each of these donor rats was subsequently transplanted into the corresponding groups of streptozotocin-induced diabetic recipient rats. Recipients were thus transfected with either IL-10 (n = 20), GFP-only carrying viral vectors (n = 20) or no viral vectors (normal saline, n = 20). A selected number of animals from each recipient group (n = 5) was sacrificed at weekly intervals for 3 weeks and some were further followed up to 12 weeks before sacrifice. Histological assessment of the pancreatic tissue was made based on rejection and GFP expression. Blood glucose levels were checked daily in all groups until sacrifice. Upon sacrifice, serum cytokine and insulin levels were measured. Histopathological correlations between blood glucose levels, serum insulin levels and serum IL-10 levels were made.

RESULTS

IL-10 gene therapy significantly attenuated pancreas rejection compared to controls, provided more normal blood glucose levels and elevated plasma insulin levels. Upon assumed natural deactivation of transferred viruses after 4 weeks, differences between groups in terms of rejection, blood glucose and insulin levels disappeared.

CONCLUSION

These findings suggest that IL-10 gene therapy significantly reduced pancreas rejection.

Lipid-Mediated Transbronchial Human Interleukin-10 Gene Transfer Decreases Acute Inflammation Associated With Allograft Rejection in a Rat Model of Lung Transplantation

BACKGROUND

Transferring genes with immunoregulatory capacity to transplanted organs has the potential to modify allograft rejection (AR). We examined the effect of ex vivo lipid-mediated transbronchial human interleukin-10 (hIL-10) gene transfer on acute AR in a rat model of lung transplantation.

METHODS

Left single lung transplantations were performed between a highly histoincompatible rat combination: Brown Norway to Lewis. The extracted donor left lung was intrabronchially instilled with a plasmid encoding hIL-10 or Escherichia coli beta-galactosidase (control), mixed with a cationic lipid. On day 6 posttransplantation, the degree of AR was graded histologically (stages 1-4) based upon pathological categories of inflammation: perivascular, peribronchial, and peribronchiolar lymphocytic infiltrates, edema, intraalveolar hemorrhage, and necrosis.

RESULTS

The stage of AR in the IL-10 group (3.1 +/- 0.4) was significantly lower than the control group (3.8 +/- 0.4). Pathological scores for edema, intraalveolar hemorrhage, and necrosis in the IL-10 group (2.3 +/- 0.8, 0.3 +/- 0.5, and 0.3 +/- 0.5, respectively) were also significantly decreased compared with those in the control group (3.2 +/- 0.4, 2.2 +/- 0.8, and 1.2 +/- 0.4, respectively).

CONCLUSION

Ex vivo lipid-mediated transbronchial hIL-10 gene transfer attenuated acute inflammation associated with AR in a rat model of lung transplantation.

Hydrodynamic plasmid DNA gene therapy model in liver transplantation

BACKGROUND

There is great interest in the field of transplantation to genetically modify grafts to decrease preservation injury or allograft rejection. Although adenoviral gene transfer has been effective in experimental liver transplantation, viral toxicity and safety concerns limit potential use in clinical trials. Therefore, the purpose of this study was to develop a model of nonviral gene transfer in the liver transplant setting, allowing for efficient transgene expression.

MATERIALS AND METHODS

Orthotopic syngeneic rat liver transplantation was performed with 3 h cold ischemia using University of Wisconsin (UW) preservation. A hydrodynamic gene transfer technique was developed where plasmid DNA was delivered to the liver graft by ex vivo rapid infusion of DNA in UW via the IVC with other vessels clamped. Expression plasmids for the marker genes luciferase and secreted human alpha1-antitrypsin (alpha1-AT) were used. Hepatic injury was assessed by graft histology and liver transaminases. Transgene expression was determined by hepatic luciferase relative light units activity (RLU) and serum alpha1-AT protein levels. Variables examined included the effect of (a) volume injected on the intravenous pressure in the liver graft; (b) injury to the liver, as measured by hepatic enzymes and histopathology; (c) variable expression between lobes; (d) volume of UW that the plasmid is administered in; (e) amount of DNA plasmid; (f) type of the promoter used; (g) clamp time; as well as (h) the time course of the marker gene expression.

RESULTS

Control rats underwent standard orthotopic syngeneic rat liver transplantation and had no detectable hepatic luciferase activity or serum human alpha1-AT. The optimal DNA plasmid dose was found to be 400 mug/liver graft, as there was no increase in the luciferase expression by increasing the dose. Furthermore, cytomegalovirus promoter yielded greater expression than Rous sarcoma virus. A high injection pressure gradient allowed for more efficient transgene expression, but produced greater liver injury shown by elevated transaminases and centrilobular necrosis. Lowering injection volume from 75 to 50% of graft weight decreased liver injury by 4.5-fold. Although higher UW injection volumes were associated with increased expression, volumes of only 50% led to luciferase expression up to 10,000,000 RLU/mg; this expression was homogeneous between the different liver lobes. Human alpha1-AT was detected in recipient blood as early as 6 h, peaked at 24 h, and remained high for 5 days.

CONCLUSIONS

We have developed a nonviral gene transfer technique where hydrostatic pressure across the cold-preserved liver vascular bed allows for efficient plasmid DNA delivery. This simple strategy should prove useful to genetically modify liver grafts in the transplantation setting.

Prometheus' challenge: molecular, cellular and systemic aspects of liver regeneration

The fascinating aspect of the liver is the capacity to regenerate after injury or resection. A variety of genes, cytokines, growth factors, and cells are involved in liver regeneration. The exact mechanism of regeneration and the interaction between cells and cytokines are not fully understood. There seems to exist a sequence of stages that result in liver regeneration, while at the same time inhibitors control the size of the regenerated liver. It has been proven that hepatocyte growth factor, transforming growth factor, epidermal growth factor, tumor necrosis factor-alpha, interleukins -1 and -6 are the main growth and promoter factors secreted after hepatic injury, partial hepatectomy and after a sequence of different and complex reactions to activate transcription factors, mainly nuclear factor kappaB and signal transduction and activator of transcription-3, affects specific genes to promote liver regeneration. Unraveling the complex processes of liver regeneration may provide novel strategies in the management of patients with end-stage liver disease. In particular, inducing liver regeneration should reduce morbidity for the donor and increase faster recovery for the liver transplantation recipient.

Prolonged skin allograft survival by IL-10 gene-introduced CD4 T cell administration

Both CD4 and CD8 T cells play crucial roles in immune responses in transplantation. Immunosuppressive drugs, such as FK506 and cyclosporin A, block the priming of alloreactive CD4 T(h) cells and the subsequent induction of allospecific CD8 cytotoxic effector T cells and inhibit allograft rejection. However, the desire to minimize chronic complications that may arise from the use of immunosuppressive agents drives the search for additional strategies for immunosuppression of allograft rejection. In this study, CD4 or CD8 T cells into which the IL-10 gene is introduced using an adenovirus vector containing human IL-10 (hIL-10) cDNA (Ad-hIL-10) and into mouse T cells transgenic for the Coxsackie virus and adenovirus receptor form a model system to study the effect of administration of IL-10-secreting T cells on the survival of the allogenic skin grafts. Ad-hIL-10-infected CD4 and CD8 T cells secreted a large amount of hIL-10 for 3-4 days in culture in vitro. Ad-hIL-10-infected CD4 T cells administered in vivo could be detected in the spleen for 7 days post-transfer. Significantly prolonged survival of grafts was observed in animals that received either Ad-hIL-10-infected activated CD4 T cells or T(h)2-skewed CD4 T cells as compared with controls. Furthermore, substantial enhancement of the effect was observed in B6.C-H2(bm1)/ByJ transplants. Thus, a direct manipulation of T cells through the introduction of the immunosuppressive cytokine gene IL-10 may be a novel strategy for the control of allograft rejection.

Gene therapy in renal diseases

Kidney-targeted gene therapy could be an ideal treatment for renal diseases since the therapeutic molecule is limited in the kidney and the systemic effect may be minimized. The technical development of the gene delivery to kidney and the identification of the responsive gene for a particular disease encourage the challenge to hereditary diseases. Collagen type IV reassembling was reported to be succeeded in Alport syndrome model by introduction of exogenous COL4A5 gene. Many gene therapies are evaluated in various glomerulonephritis models and unilateral ureteral obstruction (UUO) model, and favorable results are accumulated. Transplant kidney is an ideal target for gene therapy, by which ischemia reperfusion, acute rejection and chronic allograft nephropathy can be treated. The importation of the novel technology, for example hybrid stem cell-gene therapy could promote the gene therapy of renal diseases toward clinical application.

Favorable effect of cotransfection with TGF-beta and CTLA4Ig of the donor kidney on allograft survival

BACKGROUND/AIMS

Gene transfer of viral interleukin 10 (vIL-10) or transforming growth factor beta (TGF-beta) successfully prolonged liver and heart graft survival. Here we assessed whether injection of adenovirus (Ad) coding vIL-10 (AdvIL-10) or TGF-beta3 (AdTGF-beta3) prolonged kidney allograft survival. Since we previously demonstrated that transfection of the donor kidney with CTLA4Ig significantly prolonged allograft survival, we also evaluated the effect of a combined injection of AdvIL-10 or AdTGF-beta3 with the AdCTLA4Ig.

METHODS

Adenoviral vectors or saline were ex vivo injected into the renal artery of Brown Norway (RT.1n) donor kidneys subsequently grafted into Lewis (RT.1(l)) rats. Graft survival, transgene expression, graft cell infiltration, and histological changes were assessed.

RESULTS

Allografts of saline or Ad-beta-galactosidase controls were promptly rejected (mean survival time +/- SE 7.6 +/- 0.2 and 7.8 +/- 0.3 days, respectively). AdvIL-10 significantly prolonged survival only in 2 out of 9 animals (23.2 +/- 9.9 days), with vIL-10 expression detected on day 4. Survival was prolonged in 1 out of 5 animals by AdTGF-beta3 (14.4 +/- 5.3 days) despite the fact that the transgene was still observed after 14 days. While the combined injection of AdvIL-10 with AdCTLA4Ig did not protect the kidney from rejection (17.4 +/- 4.6 days), AdTGF-beta3 added to AdCTLA4Ig consistently prolonged the allograft lifespan in all animals (70.6 +/- 39.6 days), inducing indefinite survival in 1 animal which showed long-term gene expression and T cells hyporesponsive to alloantigens.

CONCLUSION

Overexpression of AdTGF-beta3 concomitant with the blockade of the CD28/B7 pathway by AdCTLA4Ig induces strong immunosuppression that occasionally allows the acceptance of a fully major histocompatibility complex mismatched renal graft.

Perspectives for gene therapy in renal diseases

Somatic cell gene therapy has made considerable progress last five years and has shown clear success in some clinical trials. In the field of nephrology, both the elucidation of pathophysiology of renal diseases and the development of gene transfer technique have become driving force for new therapy of incurable renal diseases, such as Alport syndrome and polycystic kidney disease. Gene therapy of renal cancer, although its application is limited to advanced cancer, is the front-runner of clinical application. Erythropoietin gene therapy has provided encouraging results for the treatment of anemia in uremic rats and recently progressed to the inducible one in response to hypoxia. Gene therapy for glomerulonephritis and renal fibrosis showed prominent impact on experimental models, although the safety must be confirmed for prolonged treatment. Transplant kidney is an ideal material for gene modification and induction of tolerance in the transplant kidney is an attractive challenge. Emerging techniques are becoming available such as stem cell technology and messenger RNA silencing strategies. We believe that the future of gene therapy research is exciting and promising and it holds an enormous potential for clinical application.

The multifaceted relationship between IL-10 and adaptive immunity: putting together the pieces of a puzzle

Interleukin-10 (IL-10) is a pleiotropic cytokine that modulates the function of several adaptive immunity-related cells. Although generally considered an immunosuppressive molecule, IL-10 possesses immunostimulatory properties in several in vitro and in vivo models. These very different outcomes are believed to depend upon experimental conditions, the dominant immune effector mediating a given immune response, the timing of IL-10 production/administration, and IL-10 dose and/or location of expression. In the present work, we review the current knowledge regarding IL-10 activity on adaptive immunity related cells, emphasize new insights on IL-10 molecular/cellular targets, and summarize the available data on the relationship between IL-10 and some pathological conditions (e.g. infectious diseases, autoimmunity, allergy, cancer and transplantation) involving adaptive immunity.

Non-viral human IL-10 gene expression reduces acute rejection in heterotopic auxiliary liver transplantation in rats

We studied nonviral delivery, expression, and the effect of the human interleukin-10 (Hu IL-10) gene on the rat model of heterotopic auxiliary liver transplantation (HALT). Two previous pilot studies showed remarkable expression of the Hu IL-10 gene in donor and recipient rats, and a decreasing effect of acute rejection in certain cases. In this study, we focused on the efficacy of Hu IL-10 gene expression to decrease acute rejection compared with cyclosporine A (CyA) in a HALT model. Three study groups and one control group were designed. Each group consisted of 6 DA donor and 6 Lewis recipient rats, which underwent HALT. In the control group, donors and recipients were not treated at all. In group II, recipients were treated with one dose of CyA. In group III, donors were treated with Hu IL-10 plasmid. In group IV, donors were treated with Hu IL-10 plasmid, and recipients were treated with one dose of CyA. Rejection was established by histopathology: it revealed 100% rejection in control and 33.3% rejection in study groups II, III, and IV. Human IL-10 gene expression prevented acute rejection with the same efficacy as CyA in the HALT model in rats.

Dual upregulation of Fas and Bax promotes alloreactive T cell apoptosis in IL-10 gene targeting of cardiac allografts

Activation-induced cell death and cytokine deprivation are demonstrated by peripheral T cell populations at the conclusion of natural immune responses, and each of these processes is modulated by the immunosuppressive cytokine interleukin (IL)-10 in vitro. This study employs a clinically relevant in vivo model of IL-10 gene transfer with heterotopically transplanted cardiac allografts to determine the mechanisms of the effects of IL-10 on T cell survival. IL-10 protein overexpression within allografts 4-5 days after gene transfer augments apoptosis of CD4+ and CD8+ graft-infiltrating lymphocytes by 7.1-fold (P < 0.001) and 6.0-fold (P < 0.001), respectively. Graft-infiltrating T cells express 10-fold more proapoptotic Fas (P < 0.01) and 30-fold more Bax (P < 0.01) than controls. The fractions of activated caspase-8 (FADD-like IL-1beta-converting enzyme) and activated caspase-9 were increased 7- and 2.3-fold, respectively, in IL-10 gene-treated allografts at postoperative day 4-5. These changes in the Fas-Fas ligand pathway and Bcl-2 mitochondrial apoptosis regulation are enhanced by complete suppression of antiapoptotic FADD-like IL-1beta-converting enzyme inhibitory protein (FLIP) (from 30.5 to 0.0%, P < 0.01) and Bcl-xL (from 22.5 to 0.1%, P = 0.03) expression among these cells from the earliest days after gene transfer. Although changes in proteins of Fas- and Bcl-2-mediated apoptosis signaling occur, only the levels of Fas and FLIP correlate to the rate of apoptosis of graft-infiltrating CD3 lymphocytes and histological rejection scores. These results indicate that dichotomous apoptosis-regulatory pathways are affected by IL-10 gene therapy, but Fas-mediated mechanisms of activation-induced cell death more substantially contribute to the greater cell death of graft-infiltrating T cells after ex vivo IL-10 gene transfer.

Augmentation of local antitumor immunity in liver by interleukin-2 gene transfer via portal vein

Metastasis to the liver remains an important problem in the treatment of patients with gastrointestinal cancer. We examined the mechanism and effect on liver metastasis of in vivo interleukin-2 (IL-2) gene transfer to the liver. RCN-9 cells derived from F344 rat colon adenocarcinoma were injected into syngeneic rats via the ileocecal vein to induce liver tumors. A total of 2.5x10(9) pfu of adenovirus vector harboring the human IL-2 gene (AdCMVhIL-2), or 2.5x10(9) pfu of control vector encoding beta-galactosidase was administered before RCN-9 cell challenge. On day 14, mean tumor weight was 4.0+/-2.4 g in the control group, whereas IL-2-transduced livers had no tumors. Survival of AdCMVhIL-2-treated rats was significantly longer than that of control rats (P<.01). Flow cytometry demonstrated that the proportion of natural killer (NK) cells had increased among sinusoidal cells collected from IL-2-transduced livers. These cells were highly cytotoxic to RCN-9 cells in vitro in the presence of a physiological high concentration of recombinant IL-2. Preventative effects of IL-2 transduction of the liver against liver metastasis were lost after depletion of NK cells by treatment with anti-asialo GM1 antibodies. Our results indicate that IL-2 gene transfer to the liver prevents liver metastasis by continuously providing physiological high concentrations of IL-2 in the liver, thereby activating sinusoidal NK cells.

Investigation of promoter polymorphisms in the tumor necrosis factor-alpha and interleukin-10 genes in liver transplant patients

BACKGROUND

Cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 play significant roles in the inflammatory and immune responses that mediate allograft rejection. The presence of a G-->A polymorphism at position -308 in the promoter region of the TNF-alpha gene increased its transcription 6- to 7-fold. A similar polymorphism at position -1082 of the IL-10 promoter results in decreased production of IL-10 protein. In this study we have determined whether the single nucleotide polymorphisms in the promoter regions of the TNF-alpha and IL-10 genes can predict the outcome of the allograft in liver recipients.

METHODS

DNA was extracted from whole blood of liver recipients. The genotype of the patients was determined by polymerase chain reaction using sequence-specific primers. The level of TNF-alpha and IL-10 protein was measured by ELISA after stimulation of peripheral blood mononuclear cells with concanavalin A.

RESULTS

There was significant correlation between acute cellular rejection and the presence of the -308A polymorphism (P<0.001), with 8 of 13 patients with the TNF-alpha polymorphism having evidence of acute rejection. Cell stimulation studies revealed that the level of TNF-alpha protein produced by patients with liver rejection was significantly higher than for patients without rejection (P=0.001). There were no strong associations between the presence of the IL-10 polymorphisms and rejection (P=0.71).

CONCLUSIONS

This study adds to the understanding of the role of cytokine polymorphisms in liver transplants. The data suggest that cytokine promoter polymorphisms may be a risk factor associated with allograft rejection in the liver.

Induction of donor-specific tolerance by adenovirus-mediated CD40Ig gene therapy in rat liver transplantation

BACKGROUND

Blockade of CD40-CD40 ligand (CD154) costimulatory pathway with anti-CD154 antibody (Ab) prolongs allograft survival in experimental organ transplantations; however, repeated agent administration is needed to provide an adequate immunosuppression. Seeking for simple and effective approach to interfere this signaling, we applied adenovirus-mediated gene therapy by encoding CD40Ig gene (AdCD40Ig).

METHODS

Liver graft from ACI (RT1av1) rat was transplanted orthotopically into LEW (RT1l) rat, and AdCD40Ig was given to animals via the penile vein immediately after grafting (n=6).

RESULTS

A single treatment with AdCD40Ig at 1x10(9) plaque forming units induced specific expression of CD40Ig gene on allograft liver, produced substantial amount of the protein in the sera, and allowed indefinite graft survival. Whereas, LEW recipients given no treatment or control adenovirus vector (AdLacZ) promptly rejected ACI liver. In addition, AdCD40Ig-treated, long-term survivors accepted skin graft from the donor strain but not the third party graft. Histopathology revealed that liver structure of the long-term surviving animals was completely preserved in normal with no infiltration of mononuclear cells.

CONCLUSION

Blockade of CD40-CD154 pathway by CD40Ig gene therapy is a potent alloantigen-specific immunosuppressive strategy to induce permanent acceptance of liver allograft and would be a new therapeutic candidate in a clinical liver transplantation.

Gene therapy in transplantation

Gene transfer and gene therapy represent a relatively new field that has grown and expanded enormously in the last 5-10 years. The application of gene transfer and gene medicines to transplantation is currently in its infancy. Consideration for gene medicines in transplantation requires delivery of vectors, either to the graft or to the immune system. Delivery of vectors to the graft provides a choice of potential immunologic targets including: costimulatory signals; inhibitory cytokines; adhesion molecules; and molecules relating to apoptosis. In addition, non-immunologic targets, that increase graft protective mechanisms by reducing ischemic and immunologic damage, represent significant targets for gene transfer. Delivery of vectors to the immune system includes potential targets to modify the immune system, and results in tolerance. Other considerations for gene therapy include the development of additional technologies, such as gene conversion or transgenesis coupled with xenotransplantation, which may provide genetically modified organs. Another important aspect of gene transfer relates to regulation of the transgene expression. A variety of issues concerning innate immunity, adaptive immunity, response to vector components, response to transgene products, and entry of vectors into the antigen presentation and processing pathway require further investigation and refinement of approaches. Lastly, regulatable promoters and the understanding of their interaction with individual cells, tissues and organs, and their interaction with innate and adaptive immunity, are of paramount importance to improving the efficacy and utility of gene transfer. There is no doubt that there is much exciting basic and translational science to be accomplished in the next decade in order to solve these potential barriers and advance gene medicines into the clinical realm in transplantation.

The role of interleukin-10 in lung transplantation

Interleukin-10 (IL-10) is a pleiotropic cytokine and its main function is to limit and terminate inflammatory responses. Lung transplantation is a relatively young clinical field compared to the transplantation of other solid organs and long-term survival is still limited. Complications after lung transplantation include ischemia-reperfusion injury immediately after transplantation, acute rejection and infection within the first year after transplantation and chronic allograft dysfunction in form of bronchiolitis obliterans thereafter. In the setting of lung transplantation two key functions of IL-10 might be of interest: (1) the inhibition of inflammatory immune responses; and (2) the inhibition of T-cell mediated immune responses. In animal models, it has been shown that exogenous IL-10 is able to prevent posttransplant ischemia-reperfusion injury as well as to decrease acute rejection. It was also effective in preventing airway obliteration in an animal model of posttransplant bronchiolitis obliterans. Beneficial effects of IL-10 may be found early and late after lung transplantation. Location of IL-10 expression as well as the timing of administration seems to be important for the desired effects.

Secretion of interleukin-10 from murine colon carcinoma cells suppresses systemic antitumor immunity and impairs protective immunity induced against the tumors

Interleukin-10 (IL-10) is a T helper type 2 (Th2) cytokine that suppresses Th1-mediated, cell-mediated immune responses and reciprocally enhances antibody-mediated responses. Previous studies, however, demonstrated that forced expression of the IL-10 gene in tumor cells could unexpectedly produce antitumor effects. We then examined whether tumor-derived IL-10 could modulate systemic immune responses. Murine colon carcinoma (Colon 26) cells that were retrovirally transduced with the murine IL-10 gene (Colon 26/IL-10) were inoculated in syngeneic immunocompetent or T cell-defective nude mice. Growth of Colon 26/IL-10 tumors was augmented in immunocompetent and, to less extent, in nude mice compared with that of wild-type tumors developed in respective mice. Growth of wild-type tumors was accelerated to the same level as that of Colon 26/IL-10 tumors when wild type and Colon 26/IL-10 cells were respectively inoculated in different flanks of the same immunocompetent mice. This enhanced growth of wild-type tumors was not observed in nude mice. Immunocompetent mice that had rejected IL-2- or IL-12-secreting Colon 26 cells developed protective immunity and became completely resistant to wild-type Colon 26 cells subsequently challenged. However, some of the mice that had rejected IL-2 or IL-12 producers developed Colon 26/IL-10 tumors inoculated thereafter. The present study showed that production of IL-10 from tumor cells impaired T cell- and non-T cell-mediated systemic antitumor immunity in hosts.

Interleukin-10 and the interleukin-10 receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

Immunosuppression by IL-10-transfected human retinal pigment epithelial cells in vitro

PURPOSE

Retinal pigment epithelium (RPE) transplantation seems to be a possible therapy for restoring vision in the case of retinal degeneration. As there is a risk of allergic rejection, a gene-transfer of immunosuppressive cytokines into the graft may diminish this reaction. Therefore, we investigated the transfer of interleukin-10 (IL-10) into an immortalised human RPE cell line (hTERT-RPE1) and its effect on the proliferation of allogeneic immune competent cells.

METHODS

The hTERT-RPE1 cells were transiently transfected with the cDNA of human IL-10 using a lipid-based transfection reagent. The expression of IL-10 mRNA was ana-lysed by reverse transcription-polymerase chain reaction and an enzyme-linked immunosorbent assay measured the secretion of the cytokine over 7 days. The effect of the secreted IL-10 on the proliferation of allogeneic T cells with and without homologous macrophages was investigated colorimetrically. To enhance this reaction, RPE cells were pre-activated with interferon-gamma (IFN-gamma). Anti-IL-10 antibodies were used in a neutralising assay.

RESULTS

A transfection efficiency of 23.3 +/- 9.03% was achieved. IL-10 mRNA could only be shown in IL-10-transfected hTERT-RPE1 cells. The same was found for the level of cytokine, with a maximum on day 3 (10.34 +/- 0.09 ng/ml). A significant suppressive effect of the secreted IL-10 on T-cell proliferation was detectable on days 5 and 6. This effect could be significantly abolished with anti-IL-10 antibodies.

CONCLUSIONS

The IL-10-producing hTERT-RPE1 cells had an immunosuppressive action on T-cell proliferation in vitro. A gene-transfer into RPE allografts before transplantation may be able to promote graft survival.

Role of cytokine gene polymorphism in hepatitis C recurrence and allograft rejection among liver transplant recipients

BACKGROUND

Cytokines play a key role in the regulation of immune responses. The maximal capacity of cytokine production varies between individuals and was shown to correlate with polymorphism in cytokine gene promoters. The objective of this study was to analyze the role of cytokine allelic variations in susceptibility to early graft rejection episodes and recurrence of hepatitis C infection in liver transplant (LTx) recipients.

METHODS

The genetic profile of five cytokines was studied in 68 LTx recipients and 49 controls using polymerase chain reaction sequence specific primers. All individuals were genotyped as high or low producers of TNF-alpha and IL-6 and high, intermediate, or low producers of transforming growth factor beta (TGF-beta), interferon gamma (IFN-gamma), and interleukin 10 (IL-10) based on single nucleotide substitutions.

RESULTS

No statistically significant differences were observed between patients with or without early rejection episodes. A significant proportion of patients more prone to rejection were genotyped as having a low production profile of IL-10 compared with the control population (P=0.04). These data are in accordance with reports regarding other solid-organ transplant recipients. Patients with no recurrence of hepatitis C had the inherent ability to produce higher TGF-beta levels than did patients with recurrent disease (P=0.042). Among nonrecurrent patients, the percentage of genetically low IL-10 producers was higher than among recurrent patients (P=0.07). Furthermore, a genetic tendency to produce higher levels of IFN-gamma was noted among LTx recipients with nonrecurrent hepatitis C than among those with recurrent hepatitis C.

CONCLUSIONS

While no significant correlation was detected between particular cytokine profile and early rejection episodes, our data strongly suggest an association between cytokine gene polymorphism of TGF-beta, IL-10, and INF-gamma and recurrence of hepatitis C in LTx recipients.

Prolongation of sheep corneal allograft survival by ex vivo transfer of the gene encoding interleukin-10

BACKGROUND

Modification of a donor cornea by gene therapy ex vivo has potential to modulate irreversible rejection, the major cause of corneal graft failure. Our aim was to transfer the gene encoding mammalian IL-10 to ovine donor corneas and to determine subsequent orthotopic corneal allograft survival in an outbred sheep model.

METHODS

The replicative capacity of ovine corneal endothelium was determined by autoradiography after deliberate injury. A replication-defective adenovirus was used to deliver the lacZ reporter gene to ovine corneas and transfected corneas were organ-cultured in vitro to allow transfection efficiency, duration of reporter gene expression, and toxicity attributable to the vector to be determined. A cDNA encoding full-length ovine IL-10 was cloned into an adenoviral vector that was used to transfect donor corneas ex vivo before transplantation. Orthotopic penetrating corneal transplantation was performed in outbred sheep.

RESULTS

Sheep corneal endothelium was found to be essentially amitotic. Transfection of > 70% corneal endothelial cells was achieved with the viral vector and expression was maintained for 28 days in vitro. IL-10 mRNA was detectable in transfected, organ-cultured corneas for 21 days in vitro. Donor corneas transfected with cDNA encoding IL-10 showed significantly prolonged survival after penetrating keratoplasty (median 55 days, range 19 > or =300 days) compared with control corneas (median 20.5 days, range 18-32 days, P=0.011).

CONCLUSION

Local gene therapy-mediated expression of the immunomodulatory cytokine IL-10 has the potential to reduce the incidence of corneal graft rejection and to prolong corneal allograft survival.

Interleukin-10 and the Interleukin-10 Receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

Emergence of anti-inflammatory monocytes in long-term surviving hosts of IL-10-transduced liver allografts

We previously reported that transduction of IL-10 to rat liver allografts facilitates survival prolongation after orthotopic liver transplantation (OLT). In the current study, we examined Lewis hosts of IL-10-transduced allografts that had survived longer than 50 days in order to characterize peripheral blood mononuclear cells (PBMC). Phenotype analysis of the PBMC demonstrated an 18-fold increase in monocytes (CD11b/c(+)) with a massive increase in the monocyte/lymphocyte ratio. The monocytes expressed downregulated MHC class II (RT1B) but upregulated Fcgamma receptors in comparison with monocytes from the control hosts. The capacity of enriched monocytes to secrete TNF-alpha in response to LPS stimulation was downregulated in the survivors, while production of IL-10 was comparable. The monocytes from long-term survivors significantly inhibited the donor antigen stimulated secretion of IFN-gamma and IL-2. Monocytosis characterized by a shift to anti-inflammatory monocytes is associated with survival prolongation in the hosts of IL-10 transduced liver allografts.

Regulation of the IL-10 production by human T cells

Interleukin (IL)-10, an immunomodulatory cytokine predominantly produced by monocytes/macrophages and T cells, inhibits several functions of dendritic cells (DC), monocytes and T cells including their cytokine production, but it stimulates B cell immunoglobulin (Ig) production and cytotoxic T lymphocyte (CTL) generation. A precise knowledge of the mechanisms that control the IL-10 production is therefore highly important for understanding the immunoregulation. The IL-10 production was studied in cultures of freshly isolated human T cells. A rise in intracellular calcium as well as the common gamma-chain containing cytokine receptor triggering or CD28 triggering were found to be important signals for IL-10 induction. CD80, CD58, rIL-12 and rIFN-alpha all had efficacious and independent costimulatory activities on the IL-10 production, while PGE2 was inhibitory. Dependence on autocrine IL-2 signalling was shown by the effects of anti-IL-2 and anti-IL-2R monoclonal antibodies (MoAb), but the IL-10 production proceeded partly IL-2-independent when CD80 provided costimulation. Sensitivity to inhibition by CsA was not removed by CD80 or CD58 costimulation and/or by addition of rIL-12 or rIFN-alpha, pointing to the absolute requirement for calcineurin activity. These data reveal important differences in the regulatory pathways between IL-10 (a cytokine-inhibitory interleukin) and IL-2 (a cytokine-inducing interleukin), which can potentially be exploited therapeutically. The fact that CsA blocks the production of IL-10, which itself has important immunosuppressive properties, should be taken into account in defining immunosuppressive treatment schedules which include the use of CsA.

Prolongation of liver allograft survival after interleukin-10 gene transduction 24-48 hours before donation

BACKGROUND

Interleukin- (IL) 10 may be a potent regulator for controlling of allograft rejection. A single administration of IL-10 is not effective for controlling graft rejection. Gene transfer is an attractive vehicle for prolonging the expression of short-lived proteins.

METHODS

Donor or recipient livers were transduced with 1 x 10(10) p.f.u. of replication-deficient adenovirus vectors harboring human IL-10 cDNA (AdCMVhIL-10) via the ileocecal vein before or after rat orthotopic liver transplantation.

RESULTS

DA allografts given AdCMVhIL-10 24-48 hr before donation survived for more than 56 days in Lewis recipients, although DA allografts given the adenovirus vector 7 days or 6 hr before, and 3 days after transplantation were rejected within 30 days in recipients. Serum levels of human IL-10 in gene-transferred rats were maximum from day 2 to 7. The serum level of human IL-10 then decreased gradually, and human IL-10 was not detected by ELISA 30 days after gene-transduction. In gene-transduced long-term surviving liver allografts, IL-10 was expressed, and the expression of IL-4 was also up-regulated on posttransplant day 3, despite the expression of Th1 cytokines (IL-2 and interferon-gamma), although in rejected liver allografts, IL-2 and interferon-gamma were expressed without expression of IL-4 and IL-10.

CONCLUSIONS

The prolongation of survival of IL-10 cDNA transferred liver allografts might be due to inhibition of the early phase of alloimmune-response by over expression of IL-10, despite the expression of IL-2 and interferon-gamma.

Gene therapy in transplantation in the year 2000: moving towards clinical applications?

Transplantation faces several major obstacles that could be overcome by expression of immunomodulatory proteins through application of gene therapy techniques. Gene therapy strategies to prolong graft survival involve gene transfer of immunosuppressive or graft-protecting molecules. Very promising results have been obtained in small animal experimental models with inhibitors of co-stimulatory signals on T cells, immunosuppressive cytokines, donor major histocompatibility antigens and regulators of cell apoptosis or oxidative stress. The application of gene therapy techniques to transplantation offers a great experimental and therapeutic potential. Local production of immunosuppressive molecules may increase their therapeutic efficiency and reduce their systemic effects. When compared with other clinical situations, gene therapy in transplantation offers several potential advantages. Gene transfer into the graft can be performed ex vivo, during the transit between the donor and the recipient, thus avoiding many of the hurdles encountered with in vivo gene transfer. Furthermore, the difficulties associated with immune responses to the gene transfer vectors and transient gene expression may be easier to overcome when gene therapy protocols are applied to transplantation than when applied to other clinical situations. The next century should witness a rapid increase in the application of gene therapy techniques to large animal pre-clinical models of transplantation and later to clinical trials. Gene Therapy (2000) 7, 14-19.