Impact of human interleukin-10 on vector-induced inflammation and early graft function in rat lung transplantation

Designer Organs: Ethical Genetic Modifications in the Era of Machine Perfusion

Gene therapy is a rapidly developing field, finally yielding clinical benefits. Genetic engineering of organs for transplantation may soon be an option, thanks to convergence with another breakthrough technology, ex vivo machine perfusion (EVMP). EVMP allows access to the functioning organ for genetic manipulation prior to transplant. EVMP has the potential to enhance genetic engineering efficiency, improve graft survival, and reduce posttransplant complications. This will enable genetic modifications with a vast variety of applications, while raising questions on the ethics and regulation of this emerging technology. This review provides an in-depth discussion of current methodologies for delivering genetic vectors to transplantable organs, particularly focusing on the enabling role of EVMP. Organ-by-organ analysis and key characteristics of various vector and treatment options are assessed. We offer a road map for research and clinical translation, arguing that achieving scientific benchmarks while creating anticipatory governance is necessary to secure societal benefit from this technology.

Machine Perfusion and Bioengineering Strategies in Transplantation-Beyond the Emerging Concepts

Solid organ transplantation has progressed rapidly over the decades from the first experimental procedures to its role in the modern era as an established treatment for end-stage organ disease. Solid organ transplantation including liver, kidney, pancreas, heart, and lung transplantation, is the definitive option for many patients, but despite the advances that have been made, there are still significant challenges in meeting the demand for viable donor grafts. Furthermore, post-operatively, the recipient faces several hurdles, including poor early outcomes like primary graft dysfunction and acute and chronic forms of graft rejection. In an effort to address these issues, innovations in organ engineering and treatment have been developed. This review covers efforts made to expand the donor pool including bioengineering techniques and the use of ex vivo graft perfusion. It also covers modifications and treatments that have been trialed, in addition to research efforts in both abdominal organs and thoracic organs. Overall, this article discusses recent innovations in machine perfusion and organ bioengineering with the aim of improving and increasing the quality of donor organs.

Creating superior lungs for transplantation with next-generation gene therapy during ex vivo lung perfusion

Engineering donor organs to better tolerate the harmful non-immunological and immunological responses inherently related to solid organ transplantation would improve transplant outcomes. Our enhanced knowledge of ischemia-reperfusion injury, alloimmune responses and pathological fibroproliferation after organ transplantation, and the advanced toolkit available for gene therapies, have brought this goal closer to clinical reality. Ex vivo organ perfusion has evolved rapidly especially in the field of lung transplantation, where clinicians routinely use ex vivo lung perfusion (EVLP) to confirm the quality of marginal donor lungs before transplantation, enabling safe transplantation of organs originally considered unusable. EVLP would also be an attractive platform to deliver gene therapies, as treatments could be administered to an isolated organ before transplantation, thereby providing a window for sophisticated organ engineering while minimizing off-target effects to the recipient. Here, we review the status of lung transplant first-generation gene therapies that focus on inducing transgene expression in the target cells. We also highlight recent advances in next-generation gene therapies, that enable gene editing and epigenetic engineering, that could be used to permanently change the donor organ genome and to induce widespread transcriptional gene expression modulation in the donor lung. In a future vision, dedicated organ repair and engineering centers will use gene editing and epigenetic engineering, to not only increase the donor organ pool, but to create superior organs that will function better and longer in the recipient.

High-throughput CRISPR technology: a novel horizon for solid organ transplantation

Organ transplantation is the gold standard therapy for end-stage organ failure. However, the shortage of available grafts and long-term graft dysfunction remain the primary barriers to organ transplantation. Exploring approaches to solve these issues is urgent, and CRISPR/Cas9-based transcriptome editing provides one potential solution. Furthermore, combining CRISPR/Cas9-based gene editing with an ex vivo organ perfusion system would enable pre-implantation transcriptome editing of grafts. How to determine effective intervention targets becomes a new problem. Fortunately, the advent of high-throughput CRISPR screening has dramatically accelerated the effective targets. This review summarizes the current advancements, utilization, and workflow of CRISPR screening in various immune and non-immune cells. It also discusses the ongoing applications of CRISPR/Cas-based gene editing in transplantation and the prospective applications of CRISPR screening in solid organ transplantation.

Immunomodulation of the donor lung with CRISPR-mediated activation of IL-10 expression

BACKGROUND

Inflammatory injury in the donor lung remains a persistent challenge in lung transplantation that limits donor organ usage and post-transplant outcomes. Inducing immunomodulatory capacity in donor organs could address this unsolved clinical problem. We sought to apply clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas) technologies to the donor lung to fine-tune immunomodulatory gene expression, exploring for the first time the therapeutic use of CRISPR-mediated transcriptional activation in the whole donor lung.

METHODS

We explored the feasibility of CRISPR-mediated transcriptional upregulation of interleukin 10 (IL-10), a key immunomodulatory cytokine, in vitro and in vivo. We first evaluated the potency, titratability, and multiplexibility of the gene activation in rat and human cell lines. Next, in vivo CRISPR-mediated IL-10 activation was characterized in rat lungs. Finally, the IL-10-activated donor lungs were transplanted into recipient rats to assess the feasibility in a transplant setting.

RESULTS

The targeted transcriptional activation induced robust and titrable IL-10 upregulation in vitro. The combination of guide RNAs also facilitated multiplex gene modulation, that is, simultaneous activation of IL-10 and IL1 receptor antagonist. In vivo profiling demonstrated that adenoviral delivery of Cas9-based activators to the lung was feasible with the use of immunosuppression, which is routinely applied to organ transplant recipients. The transcriptionally modulated donor lungs retained IL-10 upregulation in isogeneic and allogeneic recipients.

CONCLUSIONS

Our findings highlight the potential of CRISPR epigenome editing to improve lung transplant outcomes by creating a more favorable immunomodulatory environment in the donor organ, a paradigm that may be extendable to other organ transplants.

Cytokines in Lung Transplantation

Lung transplantation has developed significantly in recent years, but post-transplant care and patients' survival still need to be improved. Moreover, organ shortage urges novel modalities to improve the quality of unsuitable lungs. Cytokines, the chemical mediators of the immune system, might be used for diagnostic and therapeutic purposes in lung transplantation. Cytokine monitoring pre- and post-transplant could be applied to the prevention and early diagnosis of injurious inflammatory events including primary graft dysfunction, acute cellular rejection, bronchiolitis obliterans syndrome, restrictive allograft syndrome, and infections. In addition, preoperative cytokine removal, specific inhibition of proinflammatory cytokines, and enhancement of anti-inflammatory cytokines gene expression could be considered therapeutic options to improve lung allograft survival. Therefore, it is essential to describe the cytokines alteration during inflammatory events to gain a better insight into their role in developing the abovementioned complications. Herein, cytokine fluctuations in lung tissue, bronchoalveolar fluid, peripheral blood, and exhaled breath condensate in different phases of lung transplantation have been reviewed; besides, cytokine gene polymorphisms with clinical significance have been summarized.

Photobiomodulation Improves Serum Cytokine Response in Mild to Moderate COVID-19: The First Randomized, Double-Blind, Placebo Controlled, Pilot Study

Background

Because the major event in COVID-19 is the release of pre- and inflammatory cytokines, finding a reliable therapeutic strategy to inhibit this release, help patients manage organ damage and avoid ICU admission or severe disease progression is of paramount importance. Photobiomodulation (PBM), based on numerous studies, may help in this regard, and the present study sought to evaluate the effects of said technology on cytokine reduction.

Methods

This study was conducted in the 2nd half of 2021. The current study included 52 mild-to-moderately ill COVID-19, hospitalized patients. They were divided in two groups: a Placebo group and a PBM group, treated with PBM (620-635 nm light via 8 LEDs that provide an energy density of 45.40 J/cm2 and a power density of 0.12 W/cm2), twice daily for three days, along with classical approved treatment. 28 patients were in Placebo group and 24 in PBM group. In both groups, blood samples were taken four times in three days and serum IL-6, IL-8, IL-10, and TNF-α levels were determined.

Results

During the study period, in PBM group, there was a significant decrease in serum levels of IL-6 (-82.5% +/- 4, P<0.001), IL-8 (-54.4% ± 8, P<0.001), and TNF-α (-82.4% ± 8, P<0.001), although we did not detect a significant change in IL-10 during the study. The IL-6/IL-10 Ratio also improved in PBM group. The Placebo group showed no decrease or even an increase in these parameters. There were no reported complications or sequelae due to PBM therapy throughout the study.

Conclusion

The major cytokines in COVID-19 pathophysiology, including IL-6, IL-8, and TNF-α, responded positively to PBM therapy and opened a new window for inhibiting and managing a cytokine storm within only 3-10 days.

Gene Therapy: Will the Promise of Optimizing Lung Allografts Become Reality?

Lung transplantation is the definitive therapy for patients living with end-stage lung disease. Despite significant progress made in the field, graft survival remains the lowest of all solid organ transplants. Additionally, the lung has among the lowest of organ utilization rates-among eligible donors, only 22% of lungs from multi-organ donors were transplanted in 2019. Novel strategies are needed to rehabilitate marginal organs and improve graft survival. Gene therapy is one promising strategy in optimizing donor allografts. Over-expression or inhibition of specific genes can be achieved to target various pathways of graft injury, including ischemic-reperfusion injuries, humoral or cellular rejection, and chronic lung allograft dysfunction. Experiments in animal models have historically utilized adenovirus-based vectors and the majority of literature in lung transplantation has focused on overexpression of IL-10. Although several strategies were shown to prevent rejection and prolong graft survival in preclinical models, none have led to clinical translation. The past decade has seen a renaissance in the field of gene therapy and two AAV-based in vivo gene therapies are now FDA-approved for clinical use. Concurrently, normothermic ex vivo machine perfusion technology has emerged as an alternative to traditional static cold storage. This preservation method keeps organs physiologically active during storage and thus potentially offers a platform for gene therapy. This review will explore the advantages and disadvantages of various gene therapy modalities, review various candidate genes implicated in various stages of allograft injury and summarize the recent efforts in optimizing donor lungs using gene therapy.

Engineered mesenchymal stromal cell therapy during human lung ex vivo lung perfusion is compromised by acidic lung microenvironment

Ex vivo lung perfusion (EVLP) is an excellent platform to apply novel therapeutics, such as gene and cell therapies, before lung transplantation. We investigated the concept of human donor lung engineering during EVLP by combining gene and cell therapies. Premodified cryopreserved mesenchymal stromal cells with augmented anti-inflammatory interleukin-10 production (MSCIL-10) were administered during EVLP to human lungs that had various degrees of underlying lung injury. Cryopreserved MSCIL-10 had excellent viability, and they immediately and efficiently elevated perfusate and lung tissue IL-10 levels during EVLP. However, MSCIL-10 function was compromised by the poor metabolic conditions present in the most damaged lungs. Similarly, exposing cultured MSCIL-10 to poor metabolic, and especially acidic, conditions decreased their IL-10 production. In conclusion, we found that "off-the-shelf" MSCIL-10 therapy of human lungs during EVLP is safe and feasible, and results in rapid IL-10 elevation, and that the acidic target-tissue microenvironment may compromise the efficacy of cell-based therapies.

Photobiomodulation and Antiviral Photodynamic Therapy in COVID-19 Management

Coronavirus disease 2019 (COVID-19) has shocked the world by its spread and contagiousness. There is no approved vaccine and no proven treatment for this infection. Some potential treatments that have already been associated with antiviral and anti-inflammatory effects are under investigation. Photobiomodulation therapy (PBMT) is a photon-based therapy that uses light to mediate a variety of metabolic, analgesic, anti-inflammatory, and immunomodulatory effects. Antiviral photodynamic therapy (aPDT) is a branch of photodynamic therapy based on the reaction between a photosensitizing agent and a light source in the presence of oxygen, which can produce oxidative and free radical agents to damage the viral structures such as proteins and nucleic acids. This chapter aims to discuss the potential therapeutic benefit of PBMT and aPDT in the context of the novel coronavirus. Studies indicate that PBMT and aPDT could be useful in many viral and bacterial pulmonary complications like influenza, SARS-CoV, and MERS, but we found no direct study on SARS-CoV-2. With a combination of PBMT and aPDT, we may be able to combat COVID-19 with minimal interference with pharmaceutical agents. It might improve the efficacy of PBMT and aPDT by using monoclonal antibodies and preparing new photosensitizers at the nanoscale that target the lung tissue specifically. More animal and human studies would need to take place to reach an effective protocol. This chapter would encourage other scientists to work on this new platform.

Probable positive effects of the photobiomodulation as an adjunctive treatment in COVID-19: A systematic review

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Photobiomodulation (PBM) can reduce lung edema, cytokines in bronchoalveolar parenchyma, neutrophil influx.

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PBM reduces TNF-α, IL-1β, IL-6, ICAM-1, MIP-2 and Reactive oxygen species.

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Transthoracic approach is the direct methods for reducing lung inflammation.

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Intravenous approach increases the oxygenation of red blood cells.

Background

COVID-19, as a newly-emerged viral infection has now spread all over the world after originating in Wuhan, China. Pneumonia is the hallmark of the disease, with dyspnea in half of the patients and acute respiratory distress syndrome (ARDS) in up to one –third of the cases. Pulmonary edema, neutrophilic infiltration, and inflammatory cytokine release are the pathologic signs of this disease. The anti-inflammatory effect of the photobiomodulation (PBM) has been confirmed in many previous studies. Therefore, this review study was conducted to evaluate the direct effect of PBM on the acute lung inflammation or ARDS and also accelerating the regeneration of the damaged tissues. The indirect effects of PBM on modulation of the immune system, increasing the blood flow and oxygenation in other tissues were also considered.

Methodology

The databases of PubMed, Cochrane library, and Google Scholar were searched to find the relevant studies. Keywords included the PBM and related terms, lung inflammation, and COVID-19 -related signs. Studies were categorized with respect to the target tissue, laser parameters, and their results.

Results

Seventeen related papers were included in this review. All of them were in animal models. They showed that the PBM could significantly decrease the pulmonary edema, neutrophil influx, and generation of pro-inflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin 1 beta (IL-1β), interleukin 6 (IL-6), intracellular adhesion molecule (ICAM), reactive oxygen species (ROS), isoform of nitric oxide synthase (iNOS), and macrophage inflammatory protein 2 (MIP-2)).

Conclusion

Our findings revealed that the PBM could be helpful in reducing the lung inflammation and promoting the regeneration of the damaged tissue. PBM can increase the oxygenation indirectly in order to rehabilitate the affected organs. Thus, the infra-red lasers or light-emitting diodes (LEDs) are recommended in this regard.

Transplanting Marginal Organs in the Era of Modern Machine Perfusion and Advanced Organ Monitoring

Organ transplantation is undergoing profound changes. Contraindications for donation have been revised in order to better meet the organ demand. The use of lower-quality organs and organs with greater preoperative damage, including those from donation after cardiac death (DCD), has become an established routine but increases the risk of graft malfunction. This risk is further aggravated by ischemia and reperfusion injury (IRI) in the process of transplantation. These circumstances demand a preservation technology that ameliorates IRI and allows for assessment of viability and function prior to transplantation. Oxygenated hypothermic and normothermic machine perfusion (MP) have emerged as valid novel modalities for advanced organ preservation and conditioning. Ex vivo prolonged lung preservation has resulted in successful transplantation of high-risk donor lungs. Normothermic MP of hearts and livers has displayed safe (heart) and superior (liver) preservation in randomized controlled trials (RCT). Normothermic kidney preservation for 24 h was recently established. Early clinical outcomes beyond the market entry trials indicate bioenergetics reconditioning, improved preservation of structures subject to IRI, and significant prolongation of the preservation time. The monitoring of perfusion parameters, the biochemical investigation of preservation fluids, and the assessment of tissue viability and bioenergetics function now offer a comprehensive assessment of organ quality and function ex situ. Gene and protein expression profiling, investigation of passenger leukocytes, and advanced imaging may further enhance the understanding of the condition of an organ during MP. In addition, MP offers a platform for organ reconditioning and regeneration and hence catalyzes the clinical realization of tissue engineering. Organ modification may include immunological modification and the generation of chimeric organs. While these ideas are not conceptually new, MP now offers a platform for clinical realization. Defatting of steatotic livers, modulation of inflammation during preservation in lungs, vasodilatation of livers, and hepatitis C elimination have been successfully demonstrated in experimental and clinical trials. Targeted treatment of lesions and surgical treatment or graft modification have been attempted. In this review, we address the current state of MP and advanced organ monitoring and speculate about logical future steps and how this evolution of a novel technology can result in a medial revolution.

A novel combined ex vivo and in vivo lentiviral interleukin-10 gene delivery strategy at the time of transplantation decreases chronic lung allograft rejection in mice

OBJECTIVE

Our objective was to develop a rapid-onset and durable gene-delivery strategy that is applicable at the time of transplant to determine its effects on both acute rejection and chronic lung allograft fibrosis using a mouse orthotopic lung transplant model.

METHODS

C57BL/6 mice received an orthotopic left lung transplant from syngeneic donors or C57BL/10 donors. By using syngeneic lung transplantation, we established a novel gene transfer protocol with lentivirus luciferase intrabronchial administration to the donor lung ex vivo before transplantation. This strategy was applied in allogeneic lung transplantation with lentivirus engineering expression of human interleukin-10 or lentivirus luciferase (control).

RESULTS

Bioluminescent imaging revealed that the highest early transgene expression was achieved when lentivirus luciferase was administered both directly into the donor lung graft ex vivo before implantation and subsequently to the recipient in vivo daily on post-transplant days 1 to 4, compared with post-transplant in vivo administration only (days 0 to 4). Our previous work with adenoviral interleukin-10 gene therapy indicates that early interleukin-10 expression in the allograft is desirable. Therefore, we selected the combined protocol for human interleukin-10 encoding lentiviral vector therapy. In the allogeneic transplant setting, ex vivo and in vivo human interleukin-10 encoding lentiviral vector therapy reduced acute rejection grade (2.0 vs 3.0, P < .05) at day 28. The percentage of fibrotic obliterated airways was reduced in the human interleukin-10 encoding lentiviral vector-treated group (10.9% ± 7.7% vs 40.9% ± 9.3%, P < .05).

CONCLUSIONS

Delivery of lentiviral interleukin-10 gene therapy, using a novel combined ex vivo and in vivo delivery strategy, significantly improves acute and chronic rejection in the mouse lung transplant model.

Experience with the first 50 ex vivo lung perfusions in clinical transplantation

OBJECTIVE

Normothermic ex vivo lung perfusion is a novel method to evaluate and improve the function of injured donor lungs. We reviewed our experience with 50 consecutive transplants after ex vivo lung perfusion.

METHODS

A retrospective study using prospectively collected data was performed. High-risk brain death donor lungs (defined as Pao(2)/Fio(2) <300 mm Hg or lungs with radiographic or clinical findings of pulmonary edema) and lungs from cardiac death donors were subjected to 4 to 6 hours of ex vivo lung perfusion. Lungs that achieved stable airway and vascular pressures and Pao(2)/Fio(2) greater than 400 mm Hg during ex vivo lung perfusion were transplanted. The primary end point was the incidence of primary graft dysfunction grade 3 at 72 hours after transplantation. End points were compared with lung transplants not treated with ex vivo lung perfusion (controls).

RESULTS

A total of 317 lung transplants were performed during the study period (39 months). Fifty-eight ex vivo lung perfusion procedures were performed, resulting in 50 transplants (86% use). Of these, 22 were from cardiac death donors and 28 were from brain death donors. The mean donor Pao(2)/Fio(2) was 334 mm Hg in the ex vivo lung perfusion group and 452 mm Hg in the control group (P = .0001). The incidence of primary graft dysfunction grade 3 at 72 hours was 2% in the ex vivo lung perfusion group and 8.5% in the control group (P = .14). One patient (2%) in the ex vivo lung perfusion group and 7 patients (2.7%) in the control group required extracorporeal lung support for primary graft dysfunction (P = 1.00). The median time to extubation, intensive care unit stay, and hospital length of stay were 2, 4, and 20 days, respectively, in the ex vivo lung perfusion group and 2, 4, and 23 days, respectively, in the control group (P > .05). Thirty-day mortality (4% in the ex vivo lung perfusion group and 3.5% in the control group, P = 1.00) and 1-year survival (87% in the ex vivo lung perfusion group and 86% in the control group, P = 1.00) were similar in both groups.

CONCLUSIONS

Transplantation of high-risk donor lungs after 4 to 6 hours of ex vivo lung perfusion is safe, and outcomes are similar to those of conventional transplants. Ex vivo lung perfusion improved our center use of donor lungs, accounting for 20% of our current lung transplant activity.

The clinical potential of ex vivo lung perfusion

The number of patients listed for lung transplantation largely exceeds the number of available transplantable organs because of both a shortage of organ donors and a low utilization rate of donor lungs. Normothermic ex vivo lung perfusion (EVLP) is a method that maintains the organ in physiologically protective conditions outside the body during preservation, and shows great promise to increase utilization of donor lungs by allowing more accurate evaluation, as well as treatment and repair, of damaged donor lungs prior to transplantation. This article will cover the rationale, technical details and results of experimental and clinical studies with EVLP. The significant potential applications of EVLP in lung transplantation, lung regeneration and oncology are discussed.

Ex vivo adenoviral vector gene delivery results in decreased vector-associated inflammation pre- and post-lung transplantation in the pig

Acellular normothermic ex vivo lung perfusion (EVLP) is a novel method of donor lung preservation for transplantation. As cellular metabolism is preserved during perfusion, it represents a potential platform for effective gene transduction in donor lungs. We hypothesized that vector-associated inflammation would be reduced during ex vivo delivery due to isolation from the host immune system response. We compared ex vivo with in vivo intratracheal delivery of an E1-, E3-deleted adenoviral vector encoding either green fluorescent protein (GFP) or interleukin-10 (IL-10) to porcine lungs. Twelve hours after delivery, the lung was transplanted and the post-transplant function assessed. We identified significant transgene expression by 12 hours in both in vivo and ex vivo delivered groups. Lung function remained excellent in all ex vivo groups after viral vector delivery; however, as expected, lung function decreased in the in vivo delivered adenovirus vector encoding GFP (AdGFP) group with corresponding increases in IL-1β levels. Transplanted lung function was excellent in the ex vivo transduced lungs and inferior lung function was seen in the in vivo group after transplantation. In summary, ex vivo delivery of adenoviral gene therapy to the donor lung is superior to in vivo delivery in that it leads to less vector-associated inflammation and provides superior post-transplant lung function.

Obesity and primary graft dysfunction after lung transplantation: the Lung Transplant Outcomes Group Obesity Study

RATIONALE

Obesity has been linked to acute lung injury and is a risk factor for early mortality after lung transplantation.

OBJECTIVES

To examine the associations of obesity and plasma adipokines with the risk of primary graft dysfunction after lung transplantation.

METHODS

We performed a prospective cohort study of 512 adult lung transplant recipients with chronic obstructive pulmonary disease or interstitial lung disease enrolled in the Lung Transplant Outcomes Group Study. In a nested case-control study, we measured plasma leptin, adiponectin, and resistin before lung transplantation and 6 and 24 hours after lung transplantation in 40 cases of primary graft dysfunction and 80 control subjects. Generalized linear mixed models and logistic regression were used to estimate risk ratios and odds ratios.

MEASUREMENTS AND MAIN RESULTS

Grade 3 primary graft dysfunction developed within 72 hours of transplantation in 29% participants. Obesity was associated with a twofold increased risk of primary graft dysfunction (adjusted risk ratio 2.1; 95% confidence interval, 1.7-2.6). The risk of primary graft dysfunction increased by 40% (confidence interval, 30–50%) for each 5 kg/m(2) increase in body mass index after accounting for center, diagnosis, cardiopulmonary bypass, and transplant procedure. Higher plasma leptin levels were associated with a greater risk of primary graft dysfunction (sex-adjusted P = 0.02). The associations of both obesity and leptin with primary graft dysfunction tended to be stronger among those who did not undergo cardiopulmonary bypass.

CONCLUSIONS

Obesity is an independent risk factor for primary graft dysfunction after lung transplantation.

Genetic therapies for cystic fibrosis lung disease

The aim of gene therapy for cystic fibrosis (CF) lung disease is to efficiently and safely express the CF transmembrane conductance regulator (CFTR) in the appropriate pulmonary cell types. Although CF patients experience multi-organ disease, the chronic bacterial lung infections and associated inflammation are the primary cause of shortened life expectancy. Gene transfer-based therapeutic approaches are feasible, in part, because the airway epithelium is directly accessible by aerosol delivery or instillation. Improvements in standard delivery vectors and the development of novel vectors, as well as emerging technologies and new animal models, are propelling exciting new research forward. Here, we review recent developments that are advancing this field of investigation.

Functional repair of human donor lungs by IL-10 gene therapy

More than 80% of potential donor lungs are injured during brain death of the donor and from complications experienced in the intensive care unit, and therefore cannot be used for transplantation. These lungs show inflammation and disruption of the alveolar-capillary barrier, leading to poor gas exchange. Although the number of patients in need of lung transplantation is increasing, the number of donors is static. We investigated the potential to use gene therapy with an adenoviral vector encoding human interleukin-10 (AdhIL-10) to repair injured donor lungs ex vivo before transplantation. IL-10 is an anti-inflammatory cytokine that mainly exerts its suppressive functions by the inactivation of antigen-presenting cells with consequent inhibition of proinflammatory cytokine secretion. In pigs, AdhIL-10-treated lungs exhibited attenuated inflammation and improved function after transplantation. Lungs from 10 human multiorgan donors that had suffered brain death were determined to be clinically unsuitable for transplantation. They were then maintained for 12 hours at body temperature in an ex vivo lung perfusion system with or without intra-airway delivery of AdhIL-10 gene therapy. AdhIL-10-treated lungs showed significant improvement in function (arterial oxygen pressure and pulmonary vascular resistance) when compared to controls, a favorable shift from proinflammatory to anti-inflammatory cytokine expression, and recovery of alveolar-blood barrier integrity. Thus, treatment of injured human donor lungs with the cytokine IL-10 can improve lung function, potentially rendering injured lungs suitable for transplantation into patients.

A breath of fresh air for lung transplant recipients

Lung transplantation is a definitive therapy for the treatment of many end-stage lung diseases. However, because of donor-related morbidities, only 15% of donor lungs are suitable for transplantation, which leads to an increased risk of death for prospective patients waiting for this lifesaving procedure. A technique reported by Keshavjee's group in this issue of Science Translational Medicine may help address this problem, not only by repairing donor lungs before transplant, but also by possibly preventing lung injury after transplantation.

Normothermic ex vivo perfusion prevents lung injury compared to extended cold preservation for transplantation

Treatment of injured donor lungs ex vivo to accelerate organ recovery and ameliorate reperfusion injury could have a major impact in lung transplantation. We have recently demonstrated a feasible technique for prolonged (12 h) normothermic ex vivo lung perfusion (EVLP). This study was performed to examine the impact of prolonged EVLP on ischemic injury. Pig donor lungs were cold preserved in Perfadex for 12 h and subsequently divided into two groups: cold static preservation (CSP) or EVLP at 37 degrees C with Steen solution for a further 12 h (total 24 h preservation). Lungs were then transplanted and reperfused for 4 h. EVLP preservation resulted in significantly better lung oxygenation (PaO(2) 531 +/- 43 vs. 244 +/- 49 mmHg, p < 0.01) and lower edema formation rates after transplantation. Alveolar epithelial cell tight junction integrity, evaluated by zona occludens-1 protein staining, was disrupted in the cell membranes after prolonged CSP but not after EVLP. The maintenance of integrity of barrier function during EVLP translates into significant attenuation of reperfusion injury and improved graft performance after transplantation. Integrity of functional metabolic pathways during normothermic perfusion was confirmed by effective gene transfer and GFP protein synthesis by lung alveolar cells. In conclusion, EVLP prevents ongoing injury associated with prolonged ischemia and accelerates lung recovery.

Update on donor assessment, resuscitation, and acceptance criteria, including novel techniques--non-heart-beating donor lung retrieval and ex vivo donor lung perfusion

The shortage of adequate organ donors remains a great challenge in clinical lung transplantation. With increasing experience in the medical management and surgical technique of lung transplantation, gradual expansion of the criteria for lung donor selection has occurred with beneficial effects on the donor pool. Interest in donation after cardiac death also is increasing as the gap increases between donors and the needs of listed patients. Successful use of these new sources of lungs depends on the accurate assessment and prediction of transplanted lung function. Promising techniques for lung assessment and diagnostics include investigating key genes associated with graft failure or good graft performance using molecular approaches, and ex vivo evaluation. Further studies are needed to answer remaining questions about the best technique and solution to reperfuse human lungs for several hours without edema formation. As the predictive ability to discern good from injured donor lungs improves, strategies to repair donor lungs become increasingly important. Prolonged normothermic EVLP seems to be a platform on which many reparative strategies can be realized. With these new methods for assessing and resuscitating lungs accurately, it is hoped that inroads will be made toward providing every listed patient a chance for successful lung transplantation.

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.

Carbon monoxide protects rat lung transplants from ischemia-reperfusion injury via a mechanism involving p38 MAPK pathway

Carbon monoxide (CO) provides protection against oxidative stress via anti-inflammatory and cytoprotective actions. In this study, we tested the hypothesis that a low concentration of exogenous (inhaled) CO would protect transplanted lung grafts from cold ischemia-reperfusion injury via a mechanism involving the mitogen-activated protein kinase (MAPK) signaling pathway. Lewis rats underwent orthotopic syngeneic or allogeneic left lung transplantation with 6 h of cold static preservation. Exposure of donors and recipients (1 h before and then continuously post-transplant) to 250 ppm CO resulted in significant improvement in gas exchange, reduced leukocyte sequestration, preservation of parenchymal and endothelial cell ultrastructure and reduced inflammation compared to animals exposed to air. The beneficial effects of CO were associated with p38 MAPK phosphorylation and were significantly prevented by treatment with a p38 MAPK inhibitor, suggesting that CO's efficacy is at least partially mediated by activation of p38 MAPK. Furthermore, CO markedly suppressed inflammatory events in the contralateral naïve lung. This study demonstrates that perioperative exposure of donors and recipients to CO at a low concentration can impart potent anti-inflammatory and cytoprotective effects in a clinically relevant model of lung transplantation and support further evaluation for potential clinical use.

Perfluorochemical (PFC) liquid enhances recombinant adenovirus vector-mediated viral interleukin-10 (AdvIL-10) expression in rodent lung

Adenovirus and cationic liposome mediated transfer of Interleukin-10 (IL-10), a potent anti-inflammatory cytokine, has been shown to decrease pro-inflammatory cytokine levels and overall lung inflammation in models of lung transplantation and injury. Limitations to current approaches of IL-10 gene therapy include poor vector delivery methods and pro-inflammatory properties of human IL-10 under certain conditions. We hypothesize that using perfluorochemical (PFC) liquid to deliver the highly homologous viral IL-10 (vIL-10), which is predominantly anti-inflammatory with minimal pro-inflammatory activities, can potentially be a more effective strategy to combat inflammatory lung diseases. In this study, we compare the use of PFC liquid versus aerosolized method to deliver adenovirus encoding the vIL-10 gene (AdvIL-10) in C57Bl6 mice. Detectable vIL-10 levels were measured from bronchoalveolar lavage fluid and lung homogenates at one, four, ten and thirty days after AdvIL-10. Furthermore, we determined if use of PFC liquid could allow for the use of a lower dose of AdvIL-10 by comparing the levels of detectable vIL-10 at different doses of AdvIL-10 delivered +/- PFC liquid. Results showed that PFC liquid enhanced detectable vIL-10 by up to ten fold and that PFC liquid allowed the use of ten-fold less vector. PFC liquid increased detectable vIL-10 in lung homogenates at all time points; however, the increase in detectable vIL-10 in BAL fluid peaked at four days and was no longer evident by thirty days after intratracheal instillation. In summary, this is the first report utilizing PFC liquid to enhance the delivery of a potentially therapeutic molecule, vIL-10. We believe this strategy can be used to perform future studies on the use of the predominantly anti-inflammatory vIL-10 to treat inflammatory lung diseases.

Sleeping Beauty-based gene therapy with indoleamine 2,3-dioxygenase inhibits lung allograft fibrosis

Sleeping Beauty (SB) transposon is a natural nonviral gene transfer system that can mediate long-term transgene expression. Its potential utility in treating organ transplantation-associated long-term complications has not yet been explored. In the present study we generated an improved SB transposon encoding the human gene indoleamine-2,3-dioxygenase (hIDO), an enzyme that possesses both T cell-suppressive and antioxidant properties and selectively delivered the SB transposon in combination with a hyperactive transposase plasmid to donor lung using the cationic polymer polyethylenimine (PEI) as transfection reagent. This nonviral gene therapeutic approach led to persistent and uniform transgene expression in the rat lung tissue without noticeable toxicity and inflammation. Importantly, IDO activity produced by hIDO transgene showed a remarkable therapeutic response, as evident by near normal pulmonary function (peak airway pressure and oxygenation), histological appearance, and reduced collagen content in lung allografts. In addition, we established a hIDO-overexpressing type II cell line using the SB-based gene transfer system and found that hIDO-overexpressing lung cells effectively inhibited transforming growth factor-beta-stimulated fibroblast proliferation in vitro. In summary, the SB-based gene therapy with hIDO represents a new strategy for treating lung transplantation-associated chronic complications, e.g., obliterative bronchiolitis.

Cytokine Profile After Lung Transplantation: Correlation With Allograft Injury

BACKGROUND

Post-lung transplant reperfusion edema (PLTRE) and its more severe form, primary graft failure (PGF), occur in 10% to 60% of lung transplant recipients. We hypothesized that PLTRE and PGF would be associated with an elevated proinflammatory cascade and that the allograft would be the source of cytokine appearance in the circulation.

METHODS

Pulmonary arterial and systemic arterial samples were obtained at baseline and at 4, 8, and 24 hours after reperfusion. Post-lung transplant reperfusion-edema and PGF were defined as PaO2/FiO2 less than 300 with a mild or moderate infiltrate, or less than 200 with a severe infiltrate and ventilator dependence after 72 hours, respectively. Tumor necrosis factor alpha (TNFalpha), interleukin (IL)-6, IL-8, and IL-10 concentrations were determined by immunoassay.

RESULTS

Fifteen single and 6 bilateral lung recipients were studied. Six (29%) had PLTRE and 4 (19%) had PGF; these patients had an overall elevation in plasma IL-6, IL-8, and IL-10 concentrations (all p < 0.05). Subgroup analysis revealed a significantly greater elevation in IL-6, IL-8, and IL-10 levels in PGF patients (all p < 0.01) versus PLTRE. In the PGF group, TNFalpha and IL-10 concentrations were significantly greater in the systemic versus the pulmonary arterial samples (p < 0.05).

CONCLUSIONS

Patients with PLTRE and PGF exhibited graded increases in IL-6, IL-8, and IL-10 concentrations. The PGF patients had higher TNFalpha and IL-10 systemic arterial concentrations overall, consistent with the allograft being a source of this cytokine production.

PREVENTION OF ISCHEMIA REPERFUSION INJURY BY POSITIVE PULMONARY VENOUS PRESSURE IN ISOLATED RAT LUNG

Pulmonary ischemia-reperfusion (I/R) without tissue hypoxia induces inflammatory cytokine mRNA expression in the lung under the condition of 0 mm Hg pulmonary venous pressure (0PVP), which might be a cause of I/R injury. Our aim is to determine whether the pulmonary vascular endothelium expresses cytokine mRNAs and their corresponding proteins or develops I/R injury when positive PVP is maintained during ischemia to provide a positive stretch to the endothelium throughout the ischemic period. In isolated, perfused, and ventilated rat lungs, the right and left pulmonary arteries were isolated, and the left lung was selectively occluded for 60 min and then reperfused for 30 min. During ischemia, the left atrial pressure was maintained at 5 mm Hg (5PVP) or 0PVP. TNF-alpha, IL-1beta, IL-6, and IL-10 mRNA expression in the lungs was evaluated by RT-PCR and in situ hybridization, and the production and localization of corresponding proteins were determined by staining with fluorescence-labeled antibodies against the cytokines and an antibody against CD34. Pulmonary vascular/epithelial permeability was evaluated by measuring albumin content in bronchoalveolar lavage (BAL) fluid and wet/dry ratio. At 5PVP, there were no increases in the left lung perfusion pressure, albumin content in BAL fluid, wet/dry ratio, or expression of cytokine mRNAs and their corresponding proteins on the vascular endothelium by I/R. In contrast, at 0PVP, the increased expression of cytokine mRNAs and their corresponding proteins on the vascular endothelium by I/R was verified. The finding that the application of 5PVP during ischemia abolished the expression of cytokine mRNAs and their corresponding proteins as well as the I/R injury gives us new insights in the study of lung preservation for transplantation.

CXCR2/CXCR2 Ligand Biology during Lung Transplant Ischemia-Reperfusion Injury

Lung transplantation is a therapeutic option for a number of end-stage pulmonary disorders. Early lung allograft dysfunction (ischemia-reperfusion injury) continues to be the most common cause of early mortality after lung transplantation and a significant risk factor for the development of bronchiolitis obliterans syndrome. Ischemia-reperfusion injury is characterized histopathologically by lung edema and a neutrophil predominate leukocyte extravasation. The specific mechanism(s) that recruit leukocytes to the lung during post-lung transplantation ischemia-reperfusion injury have not been fully elucidated. Because the ELR+ CXC chemokines are potent neutrophil chemoattractants, we investigated their role during post-lung transplantation ischemic-reperfusion injury. We found elevated levels of multiple ELR+ CXC chemokines in human bronchoalveolar lavage fluid from patients with ischemia-reperfusion injury. Proof of concept studies using a rat orthotopic lung transplantation model of "cold" ischemic-reperfusion injury demonstrated an increase in lung graft neutrophil sequestration and injury. In addition, lung expression of CXCL1, CXCL2/3, and their shared receptor CXCR2 paralleled lung neutrophil infiltration and injury. Importantly, inhibition of CXCR2/CXCR2 ligand interactions in vivo led to a marked reduction in lung neutrophil sequestration and graft injury. Taken together these experiments support the notion that increased expression of ELR+ CXC chemokines and their interaction with CXCR2 plays an important role in the pathogenesis of post-lung transplantation cold ischemia-reperfusion injury.

In vivo molecular imaging characterizes pulmonary gene expression during experimental lung transplantation

Experimental gene therapy is a promising strategy to prevent ischemia-reperfusion (I/R) injury and allograft rejection after lung transplantation, and methods will eventually be needed to characterize pulmonary transgene expression in vivo in humans. Therefore, we studied positron emission tomography (PET) as a means of performing in vivo molecular imaging in rodent models of lung transplantation. Rats were transfected endotracheally with adenovirus encoding a fusion gene of a mutant Herpes simplex virus-1 thymidine kinase and the green fluorescent protein gene (the former serving as an imaging reporter gene). Twenty-four hours after transfection, lungs were transplanted in groups representing normal transplantation, I/R injury and acute allograft rejection. Imaging was obtained either 24 h after transplantation to study reperfusion injury or 4 days after transplantation to study graft rejection. After imaging, lungs were excised and analyzed for thymidine kinase activity. Imaging detected transgene expression in transplanted lungs even in the presence of acute rejection or I/R injury. The PET imaging signal correlated with in vitro lung tissue assays of thymidine kinase activity (r(2) = 0.534). Thus, noninvasive molecular imaging with PET is a feasible, sensitive and quantitative method for characterizing pulmonary transgene expression in experimental lung transplantation.

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.

Approaches to improving the kinetics of adenovirus-delivered genes and gene products

Adenovirus (Ad) vectors have been expected to play a great role in gene therapy because of their extremely high transduction efficiency and wide tropism. However, due to the intrinsic deficiency of their immunogenic toxicities, Ad vectors are rapidly cleared from the host, transgene expression is transient, and readministration of the same serotype Ad vectors is problematic. As a result, Ad vectors are continually undergoing refinement to realize their potential for gene therapy application. Even after 1999, when a patient fatally succumbed to the toxicity associated with Ad vector administration at a University of Pennsylvania (U.S.) experimental clinic, enthusiasm of gene therapists for Ad vectors has not waned. With great efforts from various research groups, significant advances have been achieved through comprehensive approaches to improving the kinetics of Ad vector-delivered genes and gene products.

A novel model for post-transplant obliterative airway disease reveals angiogenesis from the pulmonary circulation

We present a novel animal model for post-transplant obliterative airway disease in which the donor trachea is implanted into the recipient's lung parenchyma. Although this procedure is technically more challenging than the heterotopic model of implantation into a subcutaneous pouch, it has several important advantages some of which are the appropriate local environment and the possibility of local immunosuppressive therapy after transtracheal gene, cell or drug delivery. This model has revealed new insights into angiogenic potential of the pulmonary circulation.

Endobronchial Gene Transfer of Soluble Type I Interleukin-1 Receptor Ameliorates Lung Graft Ischemia-Reperfusion Injury

BACKGROUND

Soluble type I interleukin-1 receptor is a competitive inhibitor of interleukin-1 and may reduce its proinflammatory actions. The objective of this experiment was to demonstrate that endobronchial gene transfer of soluble type I interleukin-1 receptor IgG to donor lung grafts reduces posttransplant ischemia-reperfusion injury.

METHODS

All experiments utilized an orthotopic left lung isograft transplant model. Donors were divided into three groups (n = 6 each) for endobronchial transfection: group I received 2 x 10(7) plaque-forming units of adenovirus encoding soluble type I interleukin-1 receptor IgG; group II received 2 x 10(7) plaque-forming units of nonfunctional control adenovirus encoding beta-galactosidase; and group III received 0.1 mL of saline. Left lungs were harvested 24 hours after transfection and stored for 18 hours before transplantation. Graft function was assessed 24 hours after reperfusion using three measurements: isolated graft oxygenation, wet-to-dry lung weight ratio, and tissue myeloperoxidase activity. Transgene expression of soluble type I interleukin-1 receptor IgG was also evaluated using enzyme-linked immunosorbent assay and immunohistochemistry.

RESULTS

Isolated graft arterial oxygenation was significantly improved in group I compared with groups II and III (281.8 +/- 134.8 versus 115.7 +/- 121.5 and 88.0 +/- 58.9 mm Hg, p = 0.0197 and p = 0.0081, respectively). Myeloperoxidase activity was also significantly reduced in group I compared with groups II and III (0.083 +/- 0.044 versus 0.155 +/- 0.043 and 0.212 +/- 0.079 optical density units per minute per milligram protein, p = 0.0485 and p = 0.0016, respectively). Expression of soluble type I interleukin-1 receptor IgG was detected only in lungs from group I.

CONCLUSIONS

Endobronchial gene transfer of soluble type I interleukin-1 receptor IgG to donor lung grafts subjected to prolonged cold ischemia ameliorates ischemia-reperfusion injury by improving graft oxygenation and reducing lung edema and neutrophil sequestration.

Transbronchial administration of adenoviral-mediated interleukin-10 gene to the donor improves function in a pig lung transplant model

Interleukin-10 (IL-10) gene transfection of donor lungs prior to transplantation is an attractive strategy to reduce ischemia-reperfusion induced lung injury. However, experimental data with gene therapy in large animal models of lung transplantation are generally lacking. We have developed a simple clinically applicable technique for adenoviral-mediated gene delivery of human IL-10 to the lung of large animals that provides homogenous gene expression after 12-24 h of transfection. Using this technique of gene delivery, we have studied the dynamics of adenoviral gene delivery to the lung in the setting of lung transplantation. Although there is a persistent inflammatory response to the adenoviral vector, we achieved significant expression of human IL-10 in lung tissue before lung retrieval to obviate the deleterious impact of the adenoviral vector on the donor lung. The administration of adenoviral-mediated human IL-10 to the donor lung reduced ischemia-reperfusion injury and improved graft function after lung transplantation in this pig lung transplantation model. Transfection of adenoviral-mediated human IL-10 to the donor lung prevented the release of inflammatory cytokines such as IL-6 in lung tissue and plasma. We have demonstrated that IL-10 gene therapy has significant potential to prevent or treat the inflammatory response associated with ischemia-reperfusion injury in lung transplantation. In the future, IL-10 gene therapy could also be used for immunomodulation or tolerance induction.