Improvements in lung compliance after pulmonary transplantation: correlation with interleukin 8 expression

Determination of Redox Status in Serum

Free radicals of oxidative and nitrosative stress can trigger both pro-inflammatory and anti-inflammatory responses. In the transplant setting, reactive oxygen species (ROS) and reactive nitrogen species (RNS) are produced at the rejection site by different cell types including endothelial cells and macrophages. In particular, production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) seems to play an important role in promoting inflammation after exposure to inflammatory stimuli. In xenotransplantation, NO produced by iNOS upregulate multiple vasoactive substances, cytokines, chemokines, and growth factors, whereas production of NO by endothelial nitric oxide synthase (eNOS) could confer a protective effect to the graft. Accordingly, further research is needed to better understand the associated mechanisms in order to enhance protection and prevent tissue damage. Here, we describe simple methods to determine the redox state in serum that could be applied to animal models such as for xenotransplantation studies, as well as to clinical samples. Notably, caution should be taken when interpreting results of ROS and RNS measurements due to this dual role of free radicals in protecting and injuring the graft.

Beneficial effect of a nitric oxide donor in an ex vivo model of pig-to-human pulmonary xenotransplantation

BACKGROUND

Nitric oxide (NO) can reduce platelet adhesion and vascular resistance. Tempol can scavenge the reactive oxygen species (ROS) that induce tissue injury. As xenograft rejection attenuates endogenous NO production and generates ROS, we evaluated the potential effect of an NO donor (SIN-1, 3-morpholinosydnonimine) and tempol on hyperacute xenograft dysfunction using an ex vivo porcine lung perfusion model.

METHODS

For the evaluation of von Willebrand factor (vWF) secretion, human endothelial cells were stimulated with thrombin. Porcine lungs were perfused with either fresh human whole blood (unmodified control group [n = 4]), SIN-1 (n = 4), or SIN and tempol (n = 4).

RESULTS

SIN-1 and tempol significantly inhibited vWF secretion from endothelial cells in vitro. However, they did not suppress xenogeneic complement activation. In an ex vivo pulmonary perfusion model, SIN-1 improved pulmonary xenograft function by reducing pulmonary vascular resistance (PVR), inhibiting complement activation, and inhibiting thrombin generation. Combined treatment with tempol and SIN-1 potentiated PVR reduction, but slightly enhanced complement activation.

CONCLUSIONS

An NO donor is expected to improve pulmonary xenograft function through inhibition of vWF secretion, vasoconstriction, thrombin generation, and indirectly through inhibition of complement activation. The additional effects of tempol on an NO donor were not considered significant in an ex vivo xenograft system.

Inflammatory response in islet transplantation

Islet cell transplantation is a promising beta cell replacement therapy for patients with brittle type 1 diabetes as well as refractory chronic pancreatitis. Despite the vast advancements made in this field, challenges still remain in achieving high frequency and long-term successful transplant outcomes. Here we review recent advances in understanding the role of inflammation in islet transplantation and development of strategies to prevent damage to islets from inflammation. The inflammatory response associated with islets has been recognized as the primary cause of early damage to islets and graft loss after transplantation. Details on cell signaling pathways in islets triggered by cytokines and harmful inflammatory events during pancreas procurement, pancreas preservation, islet isolation, and islet infusion are presented. Robust control of pre- and peritransplant islet inflammation could improve posttransplant islet survival and in turn enhance the benefits of islet cell transplantation for patients who are insulin dependent. We discuss several potent anti-inflammatory strategies that show promise for improving islet engraftment. Further understanding of molecular mechanisms involved in the inflammatory response will provide the basis for developing potent therapeutic strategies for enhancing the quality and success of islet transplantation.

Analysis of beta-cell gene expression reveals inflammatory signaling and evidence of dedifferentiation following human islet isolation and culture

The stresses encountered during islet isolation and culture may have deleterious effects on beta-cell physiology. However, the biological response of human islet cells to isolation remains poorly characterized. A better understanding of the network of signaling pathways induced by islet isolation and culturing may lead to strategies aimed at improving islet graft survival and function. Laser capture microdissection (LCM) was used to extract beta-cell RNA from 1) intact pancreatic islets, 2) freshly isolated islets, 3) islets cultured for 3 days, and changes in gene expression were examined by microarray analysis. We identified a strong inflammatory response induced by islet isolation that continues during in-vitro culture manifested by upregulation of several cytokines and cytokine-receptors. The most highly upregulated gene, interleukin-8 (IL-8), was induced by 3.6-fold following islet isolation and 56-fold after 3 days in culture. Immunofluorescence studies showed that the majority of IL-8 was produced by beta-cells themselves. We also observed that several pancreas-specific transcription factors were down-regulated in cultured islets. Concordantly, several pancreatic progenitor cell-specific transcription factors like SOX4, SOX9, and ID2 were upregulated in cultured islets, suggesting progressive transformation of mature beta-cell phenotype toward an immature endocrine cell phenotype. Our findings suggest islet isolation and culture induces an inflammatory response and loss of the mature endocrine cell phenotype. A better understanding of the signals required to maintain a mature beta-cell phenotype may help improve the efficacy of islet transplantation.

Therapy with nonglycosaminoglycan-binding mutant CCL7: a novel strategy to limit allograft inflammation

Chemokines are immobilized by binding to glycosaminoglycans (GAGs). A non-GAG-binding mutant CCL7 (mtCCL7) was developed that retained its affinity for chemokine receptors. This mtCCL7 induced leukocyte chemotaxis in diffusion gradients but did not stimulate trans-endothelial migration (p<0.01). Unlike wild-type CCL7, mtCCL7 persisted in the circulation of BALB/c mice for more than 6 h and prevented leukocyte infiltration of skin isografts (p<0.05). Treatment with mtCCL7 marginally increased the survival of C57BL/6 to BALB/c skin allografts and reduced graft infiltration by CD3+ cells (p<0.05). Importantly, mtCCL7 promoted long-term (>40 day) graft survival following minor histocompatibility (HY) antigen mismatched C57BL/6 skin transplantation; control grafts were rejected by day 24. Treatment with mtCCL7 produced a significant decrease in the frequency of IFN-gamma producing donor-reactive splenic T cells, reduced CCR2 expression by circulating leukocytes for 6 h (p<0.01) and blocked the normal increase in affinity of alpha4beta1 integrins for VCAM-1 following transient chemokine stimulation. These data suggest that mtCCL7 persists in the circulation and reduces both specific T-cell priming and the capacity of circulating immune cells to respond to GAG-bound chemokine at sites of developing inflammation.

Failure of IL-8 to assess early reperfusion injury following lung transplantation of cardiac death donor pigs

Although interleukins (IL) 8 and 10 predict lung viability in lung transplantation from heart beating donors (HBD) and IL-1beta is a marker of ex vivo performance from after cardiac death donors (ACDD), IL expression in the recipient remains unknown. This study assessed IL-1beta, IL-8 and IL-10 as indicators of functional performance in single-lung transplantation from ACDD pigs. Animals were divided into: (i) HBD: immediate lung excision; (ii) ACDD: fibrillation, 30 min warm ischemia and 3 h topical cooling. Left lungs of both groups were then flushed with Perfadex and stored at 3-4 degrees C for 3 h. IL in bronchoalveolar lavage fluid (BAL) and hemodynamic and graft function were measured in the donor and during the 2 h reperfusion period in the recipient. Myeloperoxidase, nuclear factor kappa beta, wet/dry weight ratio and a histologic injury score were assessed from biopsies in basal conditions in the donor and at the end of reperfusion. Despite similar pulmonary function and histologic markers of injury in both groups and higher IL-1beta in the donor of ACDD, IL-8 during reperfusion was significantly lower in ACDD (119 +/- 33% of basal) than in HBD (306 +/- 238%, P < 0.05) recipients. The paradoxical behavior of IL-8 makes it an unreliable predictor of ACDD early outcome in this transplantation model.

Are serum cytokines early predictors for the outcome of burn patients with inhalation injuries who do not survive?

Introduction

Severely burned patients suffering from inhalation injury have a significantly increased risk for mortality compared with burned patients without inhalation injury. Severe burn is associated with a distinct serum cytokine profile and alterations in cytokines that contribute to morbidity and mortality. The aim of the present study was therefore to determine whether severely burned pediatric patients with concomitant inhalation injury who had a fatal outcome exhibited a different serum cytokine profile compared with burn patients with inhalation injury who survived. Early identification followed by appropriate management of these high-risk patients may lead to improved clinical outcome.

Methods

Thirteen severely burned children with inhalation injury who did not survive and 15 severely burned pediatric patients with inhalation injury who survived were enrolled in the study. Blood was collected within 24 hours of admission and 5 to 7 days later. Cytokine levels were profiled using multiplex antibody coated beads. Inhalation injury was diagnosed by bronchoscopy during the initial surgery. The number of days on the ventilator, peak inspiratory pressure rates, arterial oxygen tension (PaO₂)/fraction of inspired oxygen (FiO₂) ratio and incidence of acute respiratory distress syndrome were recorded for those patients.

Results

Significantly altered levels of IL-4, IL-6, IL-7, IL-10, and IL-13 were detected within the first 7 days after admission in serum from burn pediatric patients with concomitant inhalation injury who did not survive when compared with similar patients who did (P < 0.05). Alterations in these cytokines were associated with increased incidence of acute respiratory distress syndrome, number of days under ventilation, increased peak inspiratory pressure, and lower PaO₂/FiO₂ ratio in this patient population. Multiple logistic regression analysis revealed that patients with increased IL-6 and IL-10 as well as decreased IL-7 serum levels had a significantly greater risk for mortality (P < 0.05).

Conclusion

Early alterations in serum levels of IL-6, IL-7 and IL-10 may constitute useful predictive markers for identifying patients those who have sustained a burn with concomitant inhalation injury and who have high mortality.

Disease guided optimization of the respiratory delivery of microparticulate formulations

BACKGROUND

Inhalation of microparticulate dosage forms can be effectively used in the treatment of respiratory and systemic diseases.

OBJECTIVE

Disease states investigated for treatment by inhalation of microparticles were reviewed along with the drugs' pharmacological, pharmacokinetic and physical chemical properties to identify the advantages of microparticulate inhalation formulations and to identify areas for further improvement.

METHODS

Microbial infections of the lung, asthma, diabetes, lung transplantation and lung cancer were examined, with a focus on those systems intended to provide a sustained release.

CONCLUSION

In developing microparticulate formulations for inhalation in the lung, there is a need to understand the pharmacology of the drug as the key to revealing the optimal concentration time profile, the disease state, and the pharmacokinetic properties of the pure drug as determined by IV administration and inhalation. Finally, in vitro release studies will allow better identification of the best dosing strategy to be used in efficacy and safety studies.

Effect of Preservation Solution on Graft Viability in Single-Lung Transplantation From Heart-Beating Donors in Pigs

BACKGROUND

Low-potassium-dextran preservation solution Perfadex (PER) may provide better outcome of transplanted lungs than high-potassium Euro-Collins (EC) solution. However, there are no comparative studies of the recipient inflammatory response to the graft.

PURPOSE

The purpose of this study was to compare EC versus PER as preservation solutions with respect to the functional performance and inflammatory response in single-lung transplantation from heart-beating donors in pigs.

MATERIALS AND METHODS

The donor left lung flushed with the corresponding cold preservation solution was stored at 3 degrees C for 3 hours. We assessed hemodynamic values and pulmonary function in the recipient over a 2-hour reperfusion period calculated as percent of basal values, and expressed as mean of the reperfusion period. Interleukin-8 (IL-8) concentration in the donor was estimated in bronchoalveolar lavage fluid 2 hours after recipient reperfusion. Biopsies of the donor right lung and the transplanted lung were obtained to measure myeloperoxidase (MPO) activity. IL-8 and MPO values were expressed as percent of the donor value. We evaluated the wet/dry pulmonary weight ratio (W/D), polymorphonuclear neutrophil count (PMN), and a score of histological damage in the transplanted graft.

RESULTS

Pulmonary function evaluated by % static: 66.6 +/- 6.8 (EC), 82.3 +/- 10.2 (PER), and dynamic: 74.0 +/- 7.3 (EC), 89.3 +/- 7.7 (PER) compliances, as well as % IL-8: 562.5 +/- 168.6 (EC), 232.3 +/- 148.7 (PER), % MPO: 485.9 +/- 194.9 (EC), 140.8 +/- 21.1 (PER), W/D: 9.9 +/- 3.1 (EC), 6.8 +/- 1.4 (PER), PMN 13.5 +/- 6.8 (EC), 5.5 +/- 3.3 (PER) and the histological damage score: 3.0 +/- 1.5 (EC), 0.7 +/- 0.4 (PER) showed significant differences between the EC and the PER (P < .01).

CONCLUSIONS

PER affords good lung preservation with early graft function and modest evidences of inflammation, lung injury, and edema compared with the EC perfused lung.

ELR+ CXC chemokines and their receptors (CXC chemokine receptor 1 and CXC chemokine receptor 2) as new therapeutic targets

ELR+ CXC chemokines, by direct interaction with their cell surface receptors CXC chemokine receptor 1 (CXCR1) and CXC chemokine receptor 2 (CXCR2), are believed to be crucially involved in the direct migration and activation of leukocytes. ELR+ CXC chemokines are supposed to play a key role in several inflammatory diseases and this makes ELR+ CXC chemokines and their receptors attractive therapeutic targets. The first aim of this review is to discuss the potential pathological role of ELR+ CXC chemokines in different pathologies, including ulcerative colitis (UC), ischaemia/reperfusion injury (RI), bronchiolitis obliterans syndrome (BOS) and tumor progression. Moreover, the most recently described inhibitors of ELR+ CXC chemokines and their therapeutic indications will be reviewed. Finally, the mode of action and the potential therapeutical use of reparixin, a new potent and selective inhibitor of CXCR1/2 activity, and its chemical derivatives are also discussed.

The role of antioxidant supplementation in cardiac transplantation: an experimental study in rats

BACKGROUND

We investigated three antioxidants, inositol hexaphosphate (IP6), superoxide dismutase (SOD), and catalase (CAT), using a Langendorf model of heart transplantation.

METHODS

Rat hearts were mounted on a Langendorf perfusion apparatus with addition of IP6, SOD+CAT, IP6+SOD+CAT to St. Thomas Hospital solution (n=6 for each) versus a control group (n=6), not containing supplementation. Global ischemia was achieved for 6 hours.

RESULTS

The worst peak-to-peak (PP) and +dp/dt maximum values were observed in the IP6+SOD+CAT group, the values being significantly lower than those in the SOD+CAT group. The lowest plasma creatine kinase (CK), CK-muscle-band (CK-MB), and lactate dehydrogenase levels were measured from the SOD+CAT group. The highest values for CK were in the control group, and those for CK-MB were in the IP6 group. The lowest myocardial malondialdehyde and adenosine triphosphate values were observed in the SOD+CAT group.

CONCLUSIONS

Supplementing St. Thomas Hospital solution with IP6 did not ameliorate myocardial damage following global ischemia. The contractility deteriorated further when IP6+SOD+CAT were used together; however, SOD+CAT improved cardiac mechanical functions, and significantly reduced myocardial damage.

Effects of Short-Term Inhaled Nitric Oxide on Interleukin-8 Release After Single-Lung Transplantation in Pigs

BACKGROUND

Lung transplantation has evolved to become an effective treatment for a variety of end-stage lung diseases. However, severe reperfusion injury is still a major cause for postoperative morbidity and mortality. Although lung reperfusion injury is complex and has not been fully comprehended yet, neutrophil infiltration and cytokine activation have been postulated to play a main role. Recent studies showed that nitric oxide (NO) therapy has salutary effects on lung chronic and acute pathologies because it inhibits interleukin-8 (IL-8) release, but no data have been found on its effects during organ harvest. The aim of this study was to assess whether low doses of inhaled NO pre-treatment at the time of harvesting improves allograft function during early reperfusion in a porcine model.

METHODS

Twenty-two Landrace pigs were randomly assigned to NO-treated and control groups. In NO-treated pigs, NO at 20 ppm was administered 30 min before harvest. During the early allograft reperfusion period IL-8 content, dynamic and static compliance and gas exchange (Pa/FiO2 and PaO2) were measured in both control and NO-treated lungs.

RESULTS

Pre-treatment with NO at the time of harvesting showed improvement of allograft function in terms of dynamic (92 +/- 8% in NO vs 72 +/- 7% in the control group, p < .05) and static (83 +/- 8% in NO vs 63 +/- 7% in the control group, p < 0.05) compliance and gas exchange (PaO2: 96 +/- 4% in NO vs 74 +/- 4.5% in the control group, p < 0.01; Pa/FiO2: 97 +/- 5% in NO vs 74 +/- 5% in the control group, p < 0.01) by diminishing IL-8 (66.5 +/- 4.7 pg/ml in NO versus 208 +/- 43 pg/ml in the control group, p < 0.05) release in pigs.

CONCLUSION

These results show for the first time that NO pre-treatment at the time of harvesting reduces allograft reperfusion injury in part due to its effects on IL-8 release.