Major histocompatibility complex expression and lung ischemia-reperfusion in rats

The effects of apigenin administration on the inhibition of inflammatory responses and oxidative stress in the lung injury models: a systematic review and meta-analysis of preclinical evidence

BACKGROUND/OBJECTIVE

Apigenin is a member of the flavonoid family that can regulate various biological processes, which is characterized as a treatment of different inflammatory disorders and pathological problems associated with oxidative stress (OS). Recent research has focused on apigenin immunomodulatory properties as a potential treatment for different types of lung injuries. This meta-analysis was designed to determine the impact of apigenin treatment on inflammatory markers and OS parameters in animal models of lung injuries.

METHODS

The comprehensive literature search was conducted using electronic databases such as Google Scholar, PubMed, Web of Science, Scopus, and Embase up to August 2021. To assess apigenin's effect on inflammatory mediators and OS biomarkers in lung injury animal models, we used the I² statistic to determine the heterogeneity. We then pooled data as standardized mean difference (SMD) with a 95% confidence interval (CI).

RESULTS

Our meta-analysis of the pooled data for inflammatory biomarkers demonstrated that the apigenin administration significantly decreased the NF-κB expression (SMD - 1.60, 95% CI [- 2.93 to - 0.26]; I² = 89.0%, p < 0.001), IL-1β (SMD - 4.30, 95% CI [- 6.24 to - 2.37]; I² = 67.3%, p = 0.047), IL-6 (SMD - 4.10, 95% CI [- 5.04 to - 3.16]; I² = 72.6%, p < 0.001), TNF-α (SMD - 3.74, 95% CI [- 4.67 to - 2.82]; I² = 84.1%, p < 0.001), and TNF-α gene expression (SMD - 3.44, 95% CI [- 4.44 to - 2.43]; I² = 0.0%, p = 0.622). This study also indicated the efficacy of apigenin in increasing the level of CAT (SMD 4.56, 95% CI [3.57 to 5.55]; I² = 15.3%, p = 3.15), GSH (SMD 5.12, 95% CI [3.53 to 6.70]; I² = 77.6%, p < 0.001), and SOD (SMD 3.45, 95% CI [2.50 to 4.40]; I² = 79.2%, p < 0.001), and decreasing the level of MDA (SMD - 3.87, 95% CI [- 5.25 to - 2.49]; I² = 80.3%, p < 0.001) and MPO (SMD - 4.02, 95% CI [- 5.64 to - 2.40]; I² = 88.9%, p < 0.001), TGF- β (SMD - 3.81, 95% CI [- 4.91 to - 2.70]; I² = 73.4%, p = 0.001) and W/D level (SMD - 3.22, 95% CI [- 4.47 to - 1.97]; I² = 82.1%, p < 0.001) than control groups.

CONCLUSION

Overall, our findings showed the immunomodulatory potential of apigenin as an alternative treatment for the suppression of inflammatory responses and OS in different types of lung injury diseases. Nevertheless, due to the paucity of clinical studies, reliable preclinical models, and clinical settings, evaluating the influence of apigenin on lung injury is required in the future. Before conducting large-scale clinical trials, detailed human pharmacokinetic studies are also needed to establish dosage ranges and determine the initial safety and tolerability of apigenin.

Use of donor-derived-cell-free DNA as a marker of early allograft injury in primary graft dysfunction (PGD) to predict the risk of chronic lung allograft dysfunction (CLAD)

BACKGROUND

Primary graft dysfunction (PGD) is a risk factor for chronic lung allograft dysfunction (CLAD). However, the association between PGD and degree of allograft injury remains poorly defined. In this study, we leverage a novel biomarker for allograft injury, percentage donor-derived cell-free DNA (%ddcfDNA), to study the association between PGD, degree of allograft injury, and the development of CLAD.

METHODS

This prospective cohort study recruited 99 lung transplant recipients and collected plasma samples on days 1, 3, and 7 for %ddcfDNA measurements. Clinical data on day 3 was used to adjudicate for PGD. %ddcfDNA levels were compared between PGD grades. In PGD patients, %ddcfDNA was compared between those who developed CLAD and those who did not.

RESULTS

On posttransplant day 3, %ddcfDNA was higher in PGD than in non-PGD patients (median [IQR]: 12.2% [8.2, 22.0] vs 8.5% [5.6, 13.2] p = 0.01). %ddcfDNA correlated with the severity grade of PGD (r = 0.24, p = 0.02). Within the PGD group, higher levels of %ddcfDNA correlated with increased risk of developing CLAD (log OR(SE) 1.38 (0.53), p = 0.009). PGD patients who developed CLAD showed ∼2-times higher %ddcfDNA levels than patients who did not develop CLAD (median [IQR]: 22.4% [11.8, 27.6] vs 9.9% [6.7, 14.9], p = 0.007).

CONCLUSION

PGD patients demonstrated increased early posttransplant allograft injury, as measured by %ddcfDNA, in comparison to non-PGD patients, and these high %ddcfDNA levels were associated with subsequent development of CLAD. This study suggests that %ddcfDNA identifies PGD patients at greater risk of CLAD than PGD alone.

The role of innate immunity in the long-term outcome of lung transplantation

Long-term survival after lung transplantation remains suboptimal due to chronic lung allograft dysfunction (CLAD), a progressive scarring process affecting the graft. Although anti-donor alloimmunity is central to the pathogenesis of CLAD, its underlying mechanisms are not fully elucidated and it is neither preventable nor treatable using currently available immunosuppression. Recent evidence has shown that innate immune stimuli are fundamental to the development of CLAD. Here, we examine long-standing assumptions and new concepts linking innate immune activation to late lung allograft fibrosis.

A prospective randomized, controlled trial of eculizumab to prevent ischemia-reperfusion injury in pediatric kidney transplantation

Ischemia-reperfusion injury has multiple effects on a transplanted allograft, including delayed or impaired graft function, compromised long-term survival, and an association with an increased incidence of rejection. Eculizumab, a monoclonal antibody blocking terminal complement activation, has been postulated to be an effective agent in the prevention or amelioration of IRI. We performed a single-center prospective, randomized controlled trial involving 57 pediatric kidney transplant recipients between 2012 and 2016. The immunosuppressive protocol included two doses of alemtuzumab; half of the patients were randomized to receive a single dose of eculizumab prior to transplantation. Maintenance immunosuppression was based on a combination of low-dose tacrolimus and mycophenolate, without steroids. Eculizumab-treated patients had a significantly better early graft function, less arteriolar hyalinosis and chronic glomerulopathy on a protocol biopsies taken on day 30, 1 year, and 3 years after transplantation. In the eculizumab group, four non-vaccinated children lost their grafts during the course of a flu-like infection. Eculizumab is associated with better early graft function and improved graft morphology; however, there was an unacceptably high number of early graft losses among the eculizumab-treated children. While a promising strategy, the best approach to complement inhibition remains to be established.

Apigenin Reduces NF-κB and Subsequent Cytokine Production as Protective Effect in a Rodent Animal Model of Lung Ischemia-Reperfusion Injury

PURPOSE

Lung ischemia-reperfusion injury (LIRI) can complicate lung transplantation or cardiac surgery with cardiopulmonary bypass, increasing morbidity and mortality. In LIRI, pro-inflammatory cytokines are activated, reactive oxygen species are generated and nuclear factor-κB (NF-κB) is up-regulated, altering lung mechanics. We tested the effect of the flavonoid apigenin on a rodent model of LIRI.

METHODS

Thirty-seven Wistar rats were subjected to LIRI with or without a single or double dose of apigenin. Induction of LIRI involved sternotomy and clamping of either the left lung hilum or the pulmonary artery alone for 30 min, followed by 60 min of reperfusion. Control groups consisted of LIRI plus NaCl, a sham group and a baseline group. At the end of the experiments, both lungs were analyzed by RT-PCR, Western blot, and light microscopy.

RESULTS

In placebos, the expression levels of pro-inflammatory markers were increased in both lungs significantly, whereas NF-κB was markedly up-regulated. Administration of apigenin reduced the activation of NF-κB and the expression of TNFα, iNOS, and IL-6. These effects were observed in total lung ischemia. Histology showed greater hemorrhage and exudation in the pulmonary periphery of all groups, whereby damage was practically absent in the central lung regions of the apigenin animals. A second dose of apigenin did not outclass a single one.

CONCLUSIONS

We conclude that apigenin given intraperitoneally can reduce activation of NF-κB and also attenuate the expression of TNFα, IL-6, and iNOS in a surgical model of LIRI. The surgical procedure itself can induce significant damage to the lungs.

Bronchiolitis obliterans syndrome: the Achilles' heel of lung transplantation

Lung transplantation is a therapeutic option for patients with end-stage pulmonary disorders. Unfortunately, chronic lung allograft dysfunction (CLAD), most commonly manifest as bronchiolitis obliterans syndrome (BOS), continues to be highly prevalent and is the major limitation to long-term survival. The pathogenesis of BOS is complex and involves alloimmune and nonalloimmune pathways. Clinically, BOS manifests as airway obstruction and dyspnea that are classically progressive and ultimately fatal; however, the course is highly variable, and distinguishable phenotypes may exist. There are few controlled studies assessing treatment efficacy, but only a minority of patients respond to current treatment modalities. Ultimately, preventive strategies may prove more effective at prolonging survival after lung transplantation, but their remains considerable debate and little data regarding the best strategies to prevent BOS. A better understanding of the risk factors and their relationship to the pathological mechanisms of chronic lung allograft rejection should lead to better pharmacological targets to prevent or treat this syndrome.

In the face of chronic aspiration, prolonged ischemic time exacerbates obliterative bronchiolitis in rat pulmonary allografts

Aspiration of gastric fluid into the lung mediates the development of obliterative bronchiolitis (OB) in orthotopic WKY-to-F344 rat pulmonary transplants that have been subjected to immunosuppression with cyclosporine. However, the contribution of ischemic time to this process remains unknown. In this study, the effect of long (n = 16) and short (n = 12) ischemic times (average of 6 h and of 73 min, respectively) on rat lung transplants receiving aspiration of gastric fluid was assessed. Long ischemic times (LIT) led to significantly (p < 0.05) greater development of OB (ratio of OB lesions/total airways = 0.45 ± 0.07, mean ± standard error) compared to short ischemic times (ratio = 0.19 ± 0.05). However, the development of OB was dependent on aspiration, as controls receiving aspiration with normal saline showed little development of OB, regardless of ischemic time (p < 0.05). These data suggest that LIT, while insufficient by itself to lead to OB, works synergistically with aspiration of gastric fluid to exacerbate the development of OB.

When is injury potentially reversible in a lung ischemia-reperfusion model?

OBJECTIVE

To verify the impact of ischemic time on lung cell viability in an experimental model of lung ischemia-reperfusion (IR) injury and its repercussion on lung performance after reperfusion.

METHODS

Twenty-four animals were subjected to selective clamping of the left pulmonary artery and divided into four groups (n = 6) according to ischemic time: 15 (IR15), 30 (IR30), 45 (IR45), and 60 min (IR60). All animals were observed for 120 min after reperfusion. The hemodynamics, arterial blood gases measurements, and histologic changes were analyzed. Immunofluorescence assays for caspase 3 and annexin V were performed. Lipid peroxidation was assessed by thiobarbituric acid-reactive substances, and caspase 3 activity was assessed by colorimetric extract.

RESULTS

The partial pressure of arterial oxygen significantly decreased at the end of the observation period in the IR30, IR45, and IR60 groups (P < 0.05). The final mean arterial pressure significantly decreased in the IR60 group (P < 0.05). We observed a significant increase in caspase 3 activity and caspase 3-positive cells by immunofluorescence in the IR45 group compared with the other groups (P < 0.05). Additionally, there was an increase in necrotic cells assessed by annexin V in the IR60 group. The histologic score did not show differences among the different groups.

CONCLUSIONS

The degree of cell damage had a negative impact on lung performance. Sixty minutes of lung ischemia and posterior reperfusion resulted in an increased number of necrotic cells, suggesting that these cells may not be able to reverse the effects of the IR injury because of the lack of viable cells.

Alveolar preservation with high inflation pressure and intermediate oxygen concentration reduces ischemia-reperfusion injury of the lung

BACKGROUND

This study investigated the optimal alveolar oxygen concentration and inflation pressure during ischemia that reduces lung ischemia-reperfusion injury (LIRI).

METHODS

Male Sprague-Dawley rats (n = 66) underwent 150 minutes of left lung ischemia by hilar clamping at an airway inflation pressure (P) of 5 or 30 cm H(2)O and an oxygen (O) concentration of 0%, 30%, or 100% (P(5)O(0), P(5)O(30), P(5)O(100), P(30)O(0), P(30)O(30) and P(30)O(100) groups). Lungs preserved with 0% oxygen were inflated with 100% nitrogen. Measurements of arterial blood gas values, pulmonary compliance, histology, flow cytometry of bronchoalveolar lavage fluid were performed on day 2 postoperatively.

RESULTS

Inflation with 30 cm H(2)O resulted in increased partial pressure of arterial oxygen (Pao(2)) and lung compliance, decreased diffuse alveolar damage, and less infiltration of CD4(+) and CD8(+) lymphocytes and major histocompatibility complex class II-positive (MHCII(+)) antigen-presenting cells (APCs) in the left lung on day 2 compared with clamping at an airway inflation pressure of 5 cm H(2)O. The 100% oxygen groups demonstrated a lower Pao(2) and a decreased pulmonary compliance than 30% oxygen groups. More CD8(+) lymphocytes and MHCII(+) APCs were found in the P(5)O(100) group than in the P(5)O(0) and P(5)O(30) groups.

CONCLUSION

Alveolar inflation with a pressure of 30 cm H(2)O and an oxygen concentration of 30% decreases the severity of LIRI. The protective effect is mainly due to hyperinflation and, to a lesser extent, through oxygen concentration.

Transfusion-related acute lung injury

Transfusion-related acute lung injury is a clinical syndrome that occurs within 6 hours of transfusion. It is the leading cause of transfusion-related mortality. It presents with shortness of breath, acute pulmonary edema, fever, hypotension, or hypertension followed by hypotension. Treatment consists of respiratory support and fluid administration to support blood pressure. A majority of cases are associated with antibodies to white blood cells in the blood donor. Blood centers in the United States are currently taking measures to reduce the risk of transfusion-related acute lung injury from blood components.

Carbon monoxide reduces pulmonary ischemia-reperfusion injury in miniature swine

OBJECTIVES

Carbon monoxide is produced endogenously as a by-product of heme catalysis and has been shown to reduce ischemia-reperfusion injury in a variety of organs in murine models. The aims of this translational research were to establish an in situ porcine lung model of warm ischemia-reperfusion injury and to evaluate the cytoprotective effects of low-dose inhaled carbon monoxide in this model.

METHODS

Warm ischemia was induced for 90 minutes by clamping the left pulmonary artery and veins in 8 Clawn miniature swine (Japan Farm CLAWN Institute, Kagoshima, Japan). The left main bronchus was also dissected and reanastomosed just before reperfusion. Four animals were treated with inhaled carbon monoxide at a concentration of approximately 250 ppm throughout the procedure. Lung function and structure were serially accessed via lung biopsy, chest x-ray films, and blood gas analysis.

RESULTS

Carbon monoxide inhalation dramatically decreased the lung injury associated with ischemia and reperfusion. Two hours after reperfusion, the arterial oxygen tension of the carbon monoxide-treated group was 454 +/- 34 mm Hg, almost double the arterial oxygen tension of the control group (227 +/- 57 mm Hg). There were fewer pathologic changes seen on chest x-ray films and in biopsy samples from animals in the carbon monoxide-treated group. Animals in the carbon monoxide-treated group also had fewer inflammatory cell infiltrates and a markedly smaller increase in serum concentrations of the proinflammatory cytokines interleukin 1beta, interleukin 6, and high-mobility group box 1 after ischemia-reperfusion injury.

CONCLUSIONS

The perioperative administration of low-dose inhaled carbon monoxide decreases warm ischemia-reperfusion injury in lungs in miniature swine. This protective effect is mediated in part by the downregulation of proinflammatory mediators.

Porcine traumatic lung injury model induced by hilum clamping

OBJECTIVE

To establish a temporary pulmonary hilum clamping model for thoracic damage control surgery, as well as to determine the safety time latitude of this manipulation.

METHODS

Pigs were anaesthetised and instrumented with a thermodilution cardiac output catheter. The left pulmonary hilum was clamped with a urethral catheter after thoracotomy, maintained for three different time periods (n=6 for each group), 90min (C90), 120min (C120) and 150min (C150) and then unclamped. Haemodynamic data were recorded and the serum samples were collected for D-dimer detection and other haematological analysis. A 1-cm(3) pulmonary tissue of the left lower lobe was also obtained for histological study before clamping, at the end of clamping and at 0.5, 1, 1.5, 2 and 4h after unclamping.

RESULTS

Postoperative survival rate in each group of the pigs was as follows: 100% (all six) of C90, 83.3% (five of six) of C120, and 33.3% (two of six) of C150. Blood pressure (BP) and heart rate (HR) increased after clamping and gradually declined after unclamping. The animals of C150 group suffered highest BP and HR, respiratory index, pulmonary dynamic compliance and cardiac output. Platelet count showed no significant changes between the C90 and C120 groups, whereas a decline was noticed in the C150 group. Pulmonary vascular resistance increased significantly after pulmonary hilum clamping; when unclamped, there were minor changes in animals of C90 and C120 groups while there was a persistent elevation in the C150 group. An elevated D-dimer was detected in the C150 group, whereas it was normal in the C90 and C120 groups. There was significantly serious inflammatory cell infiltration, perivascular oedema and haemorrhagic infiltration in the C150 group compared with the C90 and C120 groups.

CONCLUSIONS

We established a pulmonary hilum clamping animal model for investigating pulmonary damage. By studying the haemodynamic and lung function changes of three different unilateral pulmonary hilum clamping time, it was determined that 120min was the longest safety time for hilum clamping without lethal pulmonary injury in porcine models.

Late primary graft dysfunction after lung transplantation and bronchiolitis obliterans syndrome

Primary graft dysfunction (PGD) is a common early complication after lung transplantation. We conducted a retrospective cohort study of 334 recipients to evaluate the impact of PGD graded at 24, 48 and 72 h on the risk of bronchiolitis obliterans syndrome (BOS) development (stage 1) and progression (stages 2 and 3). We constructed multivariable Cox proportional hazards models to determine the risk of BOS attributable to PGD in the context of other potential risk factors including acute rejection, lymphocytic bronchitis and respiratory viral infections. All grades of PGD at all time points were significant risk factors for BOS development and progression independent of acute rejection, lymphocytic bronchitis and respiratory viral infections. Specifically, PGD grade 1 at T24 was associated with a relative risk of BOS stage 1 of 1.93, grade 2 with a relative risk of 2.29 and grade 3 with a relative risk of 3.31. Furthermore, this direct relationship between the severity of PGD and the risk of BOS persisted at all time points. We conclude that all grades of PGD at all time points are independent risk factors for BOS development and progression. Future strategies that might attenuate the severity of PGD may mitigate the risk of BOS.

Heterotopic rat heart transplantation (Lewis to F344): early ICAM-1 expression after 8 hours of cold ischemia

BACKGROUND

Primary graft dysfunction is a still poorly understood complication after cardiac transplantation. Ischemia/reperfusion injury contributes to different disorders resulting in impaired graft function.

METHODS

In a heterotopic rat heart transplantation model we extended graft ischemic time up to 8 hours.

RESULTS

Using immunohistochemistry we detected an up to 4-fold increase in intracellular adhesion molecule-1 (ICAM-1) expression during 4 hours of reperfusion, independent of ischemic time (30-minute ischemia: 7.65 +/- 2.15 without reperfusion, 19.46 +/- 4.6 after 4-hour reperfusion; 240-minute ischemia: 5.6 +/- 1.99 and 22.3 +/- 3.77; 480-minute ischemia: 3.7 +/- 1.56 and 13.1 +/- 2.2). Eight-hour ischemic allografts had an increase in CD8-positive cells (1.37 +/- 0.5 and 2.3 +/- 0.77) and a significant increase in MHC II expression (11.48 +/- 2.1 and 18.27 +/- 1.34) during 4 hours of reperfusion.

CONCLUSIONS

We hypothesize that these findings reflect an early inflammatory reaction in the allograft possibly triggered by oxidative stress. During therapeutic interventions, both of these pathways must be considered.

Animal models of acute lung injury

Acute lung injury in humans is characterized histopathologically by neutrophilic alveolitis, injury of the alveolar epithelium and endothelium, hyaline membrane formation, and microvascular thrombi. Different animal models of experimental lung injury have been used to investigate mechanisms of lung injury. Most are based on reproducing in animals known risk factors for ARDS, such as sepsis, lipid embolism secondary to bone fracture, acid aspiration, ischemia-reperfusion of pulmonary or distal vascular beds, and other clinical risks. However, none of these models fully reproduces the features of human lung injury. The goal of this review is to summarize the strengths and weaknesses of existing models of lung injury. We review the specific features of human ARDS that should be modeled in experimental lung injury and then discuss specific characteristics of animal species that may affect the pulmonary host response to noxious stimuli. We emphasize those models of lung injury that are based on reproducing risk factors for human ARDS in animals and discuss the advantages and disadvantages of each model and the extent to which each model reproduces human ARDS. The present review will help guide investigators in the design and interpretation of animal studies of acute lung injury.

Ischemia of the lung causes extensive long-term pulmonary injury: an experimental study

Background

Lung ischemia-reperfusion injury (LIRI) is suggested to be a major risk factor for development of primary acute graft failure (PAGF) following lung transplantation, although other factors have been found to interplay with LIRI. The question whether LIRI exclusively results in PAGF seems difficult to answer, which is partly due to the lack of a long-term experimental LIRI model, in which PAGF changes can be studied. In addition, the long-term effects of LIRI are unclear and a detailed description of the immunological changes over time after LIRI is missing. Therefore our purpose was to establish a long-term experimental model of LIRI, and to study the impact of LIRI on the development of PAGF, using a broad spectrum of LIRI parameters including leukocyte kinetics.

Methods

Male Sprague-Dawley rats (n = 135) were subjected to 120 minutes of left lung warm ischemia or were sham-operated. A third group served as healthy controls. Animals were sacrificed 1, 3, 7, 30 or 90 days after surgery. Blood gas values, lung compliance, surfactant conversion, capillary permeability, and the presence of MMP-2 and MMP-9 in broncho-alveolar-lavage fluid (BALf) were determined. Infiltration of granulocytes, macrophages and lymphocyte subsets (CD45RA⁺, CD5⁺CD4⁺, CD5⁺CD8⁺) was measured by flowcytometry in BALf, lung parenchyma, thoracic lymph nodes and spleen. Histological analysis was performed on HE sections.

Results

LIRI resulted in hypoxemia, impaired left lung compliance, increased capillary permeability, surfactant conversion, and an increase in MMP-2 and MMP-9. In the BALf, most granulocytes were found on day 1 and CD5⁺CD4⁺ and CD5⁺CD8⁺-cells were elevated on day 3. Increased numbers of macrophages were found on days 1, 3, 7 and 90. Histology on day 1 showed diffuse alveolar damage, resulting in fibroproliferative changes up to 90 days after LIRI.

Conclusion

The short-, and long-term changes after LIRI in this model are similar to the changes found in both PAGF and ARDS after clinical lung transplantation. LIRI seems an independent risk factor for the development of PAGF and resulted in progressive deterioration of lung function and architecture, leading to extensive immunopathological and functional abnormalities up to 3 months after reperfusion.

Length of pressure-controlled reperfusion is critical for reducing ischaemia-reperfusion injury in an isolated rabbit lung model

Background

Ischaemia-reperfusion injury is still a major problem after lung transplantation. Several reports describe the benefits of controlled graft reperfusion. In this study the role of length of the initial pressure-controlled reperfusion (PCR) was evaluated in a model of isolated, buffer-perfused rabbit lungs.

Methods

Heart-lung blocks of 25 New Zealand white rabbits were used. After measurement of baseline values (haemodynamics and gas exchange) the lungs were exposed to 120 minutes of hypoxic warm ischaemia followed by repeated measurements during reperfusion. Group A was immediately reperfused using a flow of 100 ml/min whereas groups B, C and D were initially reperfused with a maximum pressure of 5 mmHg for 5, 15 or 30 minutes, respectively. The control group had no period of ischaemia or PCR.

Results

Uncontrolled reperfusion (group A) caused a significant pulmonary injury with increased pulmonary artery pressures (PAP) and pulmonary vascular resistance and a decrease in oxygen partial pressure (PO₂), tidal volume and in lung compliance. All groups with PCR had a significantly higher PO₂ for 5 to 90 min after start of reperfusion. At 120 min there was also a significant difference between group B (264 ± 91 mmHg) compared to groups C and D (436 ± 87 mmHg; 562 ± 20 mmHg, p < 0.01). All PCR groups showed a significant decrease of PAP compared to group A.

Conclusion

Uncontrolled reperfusion results in a severe lung injury with rapid oedema formation. PCR preserves pulmonary haemodynamics and gas exchange after ischaemia and might allows for recovery of the impaired endothelial function. 30 minutes of PCR provide superior results compared to 5 or 15 minutes of PCR.

Genomic profiling of kidney ischemia-reperfusion reveals expression of specific alloimmunity-associated genes: Linking "immune" and "nonimmune" injury events

Increased organ ischemia time leads to delayed graft function (DGF), increased acute rejection (AR), enhanced chronic allograft nephropathy (CAN), and reduced long-term allograft survival. The mechanisms by which IRI predisposes to AR and CAN are unknown. We hypothesized that gene expression profiling of ischemia-reperfusion injury (IRI)-affected kidney would identify how IRI predisposes to AR and CAN. Furthermore, we examined how current immunosuppressive drug molecular targets are altered by IRI. C57BL/6J mice were exposed to 30 (n = 3) or 60 (n = 3) minutes of bilateral kidney ischemia or sham surgery (n = 5). At 36 hour kidney tissue was collected and analyzed using Affymetrix 430MOEA (22626 genes) array and GC-RMA-SAM pipeline. Genes with the false discovery rate (q < 1%) and +/-50% fold change (FC) were considered affected by IRI. Genes coding for histocompatibility and antigen-presenting factors, calcineurin, and mammalian target of rapamycin (mTOR) pathway-associated proteins were selected using Gene Ontology (GO) analysis. GO analysis identified 10 and 17 alloimmunity-related genes affected by IRI induced by 30 and 60 minutes of ischemia, respectively, including Traf6 (FC = 2.99) and H2-D1 (FC = 2.58). We also detected significant IRI genomic responses in calcineurin and mTOR pathways represented by Fkbp5 (FC = 4.18) and Fkbp1a (FC = 2.0), and Eif4ebp1 (FC = 16.8) and Akt1 (FC = 3.64), respectively. These data demonstrated that IRI up-regulates expression of several alloimmunity-associated genes, which can in turn enhance alloimune responses. Our discovery of IRI-induced up-regulation of genes associated with calcineurin and mTOR pathways are consistent with clinical observations that FK506 and Rapamycin can alter the course of DGF. Further validation and dissection of these pathways can lead to novel approaches by which improved management of early "nonimmune" transplant events can decrease susceptibility to more classic "immune" changes and CAN.

Early immunological changes associated with laryngeal transplantation in a major histocompatibility complex-matched pig model

Laryngeal transplantation is an increasingly viable proposition for patients with irreversible diseases of the larynx. One human transplant has been performed successfully, but many questions remain before routine transplantation can begin. In order to measure the immunological changes in mismatched transplants, it is first necessary to know the immediate combined effects of ischaemia-reperfusion injury (IRI) plus the added insult of major surgery in a fully matched setting. We measured the changes in immunologically active mucosal cells following 3 h of cold ischaemia and 8 h of in situ reperfusion in a major histocompatibility complex (MHC)-matched minipig model (n = 4). Biopsies were prepared for quantitative, multiple-colour immunofluorescence histology. The number of immunologically active cells was significantly altered above (supraglottis) and below (subglottis) the vocal cords following transplantation and reperfusion (P < 0.05, P < 0.001, respectively). However, the direction of the change differed between the two subsites: cell numbers decreased post-transplant in the supraglottis and increased in the subglottis. Despite the statistical evidence for IRI, these changes were less than the large normal inter- and intrapig variation in cell counts. Therefore, the significance of IRI in exacerbating loss of function or rejection of a laryngeal allograft is open to question. Longer-term studies are required.

Impact of immediate primary lung allograft dysfunction on bronchiolitis obliterans syndrome

RATIONALE

Primary graft dysfunction is a common complication after lung transplantation and a significant risk factor for short- and long-term mortality.

OBJECTIVE

We examined the impact of primary graft dysfunction on bronchiolitis obliterans syndrome.

METHODS

We performed a retrospective cohort study of 334 adult lung transplant recipients at our program and graded the severity of primary graft dysfunction according to the International Society for Heart and Lung Transplantation definition. We evaluated the impact of primary graft dysfunction on acute rejection, lymphocytic bronchitis, and bronchiolitis obliterans syndrome stage 1, using univariable and multivariable Cox proportional hazards models.

MAIN RESULTS

Among the 334 recipients, 65 did not have primary graft dysfunction (grade 0), 130 had grade 1, 69 had grade 2, and 70 had grade 3. In the univariable analysis, all grades of primary graft dysfunction were associated with a significantly increased risk of bronchiolitis obliterans syndrome stage 1 (grade 1: relative risk [RR] = 1.73; grade 2: RR = 2.13; and grade 3: RR = 2.53, compared with grade 0). The multivariable model demonstrated that the increased risk of bronchiolitis obliterans syndrome associated with primary graft dysfunction was independent of acute rejection, lymphocytic bronchitis, and community-acquired respiratory viral infections. However, there was no association between primary graft dysfunction and acute rejection or lymphocytic bronchitis.

CONCLUSIONS

Primary graft dysfunction is associated with an increased risk of bronchiolitis obliterans syndrome independent of acute rejection, lymphocytic bronchitis, and community-acquired respiratory viral infections, and this risk is directly related to the severity of primary graft dysfunction.

Inflammatory response to pulmonary ischemia-reperfusion injury

Lung ischemia-reperfusion (IR) injury is one of the most important complications following lung transplant and cardiopulmonary bypass. The pulmonary dysfunction following lung IR has been well documented. Recent studies have shown that ischemia and reperfusion of the lung may each play significant yet differing roles in inducing lung injury. The mechanisms of injury involving neutrophil activation, and the release of numerous inflammatory mediators and oxygen radicals also contributes to lung cellular injury, pneumocyte necrosis, and apoptosis. We herein review the current understanding of the underlying mechanism involved in lung IR injury. The biomolecular mechanisms and interactions which lead to the inflammatory response, pneumocyte necrosis, and apoptosis following lung IR therefore warrant further investigation.

Prolonged Cold Ischemia in Rat Cardiac Allografts Promotes Ischemia–Reperfusion Injury and the Development of Graft Coronary Artery Disease in a Linear Fashion

BACKGROUND

Prolonged cold ischemia is thought to exacerbate ischemia-reperfusion injury and graft coronary artery disease (GCAD). We investigated the effect of varying lengths of cold ischemia on inflammation and apoptosis during ischemia-reperfusion injury and correlated this with the degree of GCAD in rat cardiac allografts.

METHODS

PVG rat (RT1c) hearts subjected to 30, 60, 90, 120, or 150 minutes of cold ischemia were heterotopically transplanted into ACI rats (RT1a). Grafts were procured after 4 hours of reperfusion and analyzed for superoxide generation, myeloperoxidase activity, tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and monocyte chemoattractant protein-1/chemokine (C-C motif) ligand 2 (MCP-1/CCL2) production, cardiomyocyte apoptosis, and caspase-2, -3, -8, -9 activities. Additional transplanted animals received cyclosporine A (7.5 mg/kg/day) for 10 days as chronic rejection models. Indices of GCAD were determined at 90 days.

RESULTS

A direct linear correlation was found between cold ischemic time, ischemia-reperfusion injury, and GCAD. Superoxide generation, myeloperoxidase activity, TNF-alpha, IL-1beta, MCP-1/CCL2 production, cardiomyocyte apoptosis, and caspase-2, -3, -8, and -9 activities increased with ischemic time, peaking at 120 minutes and plateauing at 150 minutes. GCAD, assessed by the percentage of luminal narrowing, the intima/media ratio, and the percentage of diseased vessels, worsened with increased ischemic time, peaking at 120 minutes and plateauing at 150 minutes. All tested variables in both the acute and chronic phases were significantly increased with 120-minute ischemia compared with 30-minute ischemia.

CONCLUSIONS

These data indicate that the degree of cardiomyocyte apoptosis and inflammatory response in cardiac allografts during ischemia-reperfusion injury depends on the duration of cold ischemia. More important, that prolonged cold ischemia correlates with increased GCAD.

A randomized, placebo-controlled trial of complement inhibition in ischemia-reperfusion injury after lung transplantation in human beings

OBJECTIVE

Complement activation has been shown to play a significant role in ischemia-reperfusion injury after lung transplantation. TP-10 (soluble complement receptor 1 inhibitor) inhibits the activation of complement by inactivating C3a and C5a convertases. This was a clinical trial of TP-10 to reduce ischemia-reperfusion injury in lung transplantation.

METHODS

In a randomized, double-blinded, multicenter, placebo-controlled trial, 59 patients from four lung transplant programs received TP-10 (10 mg/kg, n = 28) or placebo (n = 31) before reperfusion. This dose achieved 90% complement inhibition for 24 hours, and activity had returned toward normal by 72 hours.

RESULTS

At 24 hours, 14 of 28 patients in the TP-10 group (50%) were extubated, whereas only 6 of 31 patients in the placebo group (19%) were (P = .01). The total times on the ventilator and in the intensive care unit both tended to be shorter in the TP-10 group, but these differences did not achieve statistical significance. Among patients requiring cardiopulmonary bypass (n = 5 in placebo group and n = 7 in TP-10 group), the mean duration of mechanical ventilation was reduced by 11 days in the TP-10 group (10.6 +/- 5.0 days vs 21.5 +/- 5.9 days in placebo group, P = .2). Operative deaths, incidences of infection and rejection, and length of hospital stay were not significantly different between the two groups.

CONCLUSIONS

Short-term complement inhibition with TP-10 led to early extubation in a significantly higher proportion of lung transplant recipients. The effect of TP-10 was greater among patients undergoing cardiopulmonary bypass, with a large reduction in ventilator days. Complement inhibition thus significantly decreases the duration of mechanical ventilation and could be useful in improving the outcome of lung transplant recipients.

The effect of primary graft dysfunction on survival after lung transplantation

RATIONALE

Primary graft dysfunction is a severe acute lung injury syndrome after lung transplantation. Long-term outcomes of subjects with primary graft dysfunction have not been studied.

OBJECTIVES

We sought to test the relationship of primary graft dysfunction with both short- and long-term mortality using a large registry.

METHODS

We used data collected on 5,262 patients in the United Network for Organ Sharing/International Society of Heart and Lung Transplantation registry between 1994 and 2000. We assessed outcomes in all subjects; to assess potential bias from the effects of early mortality, we also evaluated subjects who survived at least 1 year, using Cox proportional hazards models with time-varying covariates.

MAIN RESULTS

The overall incidence of primary graft dysfunction was 10.2% (95% confidence intervals [CI], 9.2, 10.9). The incidence did not vary by year over the period of observation (p = 0.22). All-cause mortality at 30 days was 42.1% for primary graft dysfunction versus 6.1% in patients without graft dysfunction (relative risk = 6.95; 95% CI, 5.98, 8.08; p < 0.001); among subjects who died by 30 days, 43.6% had primary graft dysfunction. Among patients surviving at least 1 year, those who had primary graft dysfunction had significantly worse survival over ensuing years (hazard ratio, 1.35; 95% CI, 1.07, 1.70; p = 0.011). Adjustment for clinical variables including bronchiolitis obliterans syndrome did not change this relationship.

CONCLUSION

Primary graft dysfunction contributes to nearly half of the short-term mortality after lung transplantation. Survivors of primary graft dysfunction have increased risk of death extending beyond the first post-transplant year.

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.

Recipient T cells mediate reperfusion injury after lung transplantation in the rat

Leukocytes have been implicated in ischemia-reperfusion (IR) injury of the lung, but the individual role of T cells has not been explored. Recent evidence in mice suggests that T cells may play a role in IR injury. Using a syngeneic (Lewis to Lewis) rat lung transplant model, we observed that recipient CD4(+) T cells infiltrated lung grafts within 1 h of reperfusion and up-regulated the expression of CD25 over the ensuing 12 h. Nude rats (rnu/rnu) and heterozygous rats (rnu/+) were used to determine the role of T cells in IR injury. No significant difference in lung function was observed between nude and heterozygous recipient rats after 2 h of reperfusion. However, after 12 h of reperfusion, recipient nude rats had significantly higher oxygenation and lower peak airway pressure than recipient heterozygous rats. This was associated with significantly lower levels of IFN-gamma in transplanted lung tissue of recipient nude rats. Reconstitution of recipient nude rats with T cells from heterozygous rats restored IR injury after 12 h of reperfusion. The effect of T cells was independent of neutrophil recruitment and activation in the transplanted lung. These results demonstrate that recipient T cells are activated and mediate IR injury during lung transplantation in rats.

Matrix metalloproteinase inhibition decreases ischemia-reperfusion injury after lung transplantation

Increased microvascular permeability and extravasation of inflammatory cells are key events of lung ischemia-reperfusion (IR) injury. The purpose of this study was to investigate the role of matrix metalloproteinases (MMP) in IR-induced alveolar capillary membrane disruption after experimental lung transplantation. We used a rat model of lung orthotopic transplantation (n = 86) with a prolonged cold ischemic phase. MMP2 and MMP9 were elevated 4 h after the onset of ischemia and further increased during reperfusion. Compared to sham values, the alveolar-capillary membrane permeability increased by 105% and 82.6% after 4 h of ischemia and 2 h or 24 h of reperfusion, respectively. A 4- and 5-fold increase of the infiltration of ischemic tissue by neutrophils was also observed after 2 h and 24 h of reperfusion. The PO2/FIO2 ratio dropped significantly from 244 to 76.6 after 2 h of reperfusion and from 296.4 to 127.6 after 24 h of reperfusion. A nonselective inhibitor of MMP, administered to the rats and added to the preservation solution, reduced significantly the alveolar-capillary leakage, the transmigration of neutrophils and improved gas exchanges in animals submitted to 4 h of ischemia combined with 2 h or 24 h of reperfusion. We conclude that inhibition of MMP attenuates IR injury after experimental lung transplantation.

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

This study was undertaken to examine the time course of human interleukin (hIL)-10 gene expression after transtracheal administration of adenoviral (Ad)hIL-10 and its effect on the early adenoviral proinflammatory cytokine response and on post-transplant lung function. Using a rat lung transplant model, we observed that lungs retrieved 12 h after the administration of AdhIL-10 were associated with significant improvement in post-transplant lung function. Shorter periods of transfection were associated with significantly elevated levels of tumor necrosis factor-alpha and macrophage inflammatory protein-2 in lung tissue, leading to an increased degree of injury. The release of proinflammatory cytokines secondary to the adenoviral vector was reduced by high-dose methylprednisolone (30 mg/kg) administered 3 h before transfection. Reduction in the early adenoviral inflammatory response was associated with significant improvement in post-transplant lung function when lungs were retrieved 6 or 12 h after transtracheal administration of AdhIL-10. Transtracheal administration of adenoviral-mediated hIL-10 to donor lungs is associated with a significant early inflammatory response that may enhance ischemia-reperfusion injury if insufficient hIL-10 is expressed in lung tissue before retrieval. The period between delivery of AdhIL-10 and lung retrieval can be reduced if the early inflammatory response is suppressed with methylprednisolone.

Non-immune acute graft injury after lung transplantation and the risk of subsequent bronchiolitis obliterans syndrome (BOS)

BACKGROUND

Primary graft dysfunction remains a major cause of early morbidity and mortality after lung transplantation. Evidence from animal models shows acute non-immune lung injury increases organ immunogenicity by enhancing MHC Class II expression. We hypothesized that acute non-immune injury in the lung allograft may impact, not only on early survival, but also on longer term survival by increasing the incidence of bronchiolitis obliterans syndrome (BOS).

METHODS

A single-center, retrospective, observational study in a population of over 320 lung transplant recipients was undertaken. The histologic diagnosis of diffuse alveolar damage (DAD) in an early graft biopsy was used to define those recipients at risk. Serial measurements of forced expiratory volume in 1 second (FEV(1)) in long-term follow-up defined the incidence of BOS.

RESULTS

Early graft biopsy was available in 291 of the recipients following transplantation. DAD was confirmed in 55 (19%); their 30-day survival (62.5%) was significantly worse than in recipients without DAD (87.5%; p < 0.0001, chi-square test). When 30-day deaths were excluded, however, there was no difference in survival between recipients with and without DAD (hazards ratio 0.69 [0.37 to 1.3]; p = 0.25, Wilcoxon's survival analysis). The incidence of subsequent BOS over the follow-up period was not significantly different in those with and without DAD on early biopsy at 46% and 59%, respectively (hazards ratio 0.88 [0.48 to 1.62]; p = 0.22, chi-square test). BOS did not occur any earlier in the DAD group (median 953 days, range 152 to 1,393) days compared with the non-DAD group (median 665 days, range 52 to 4,299) (p = 0.48, Fisher's exact test).

CONCLUSIONS

The development of severe non-immune acute graft injury after lung transplantation has a poor early prognosis. However, recipients with non-immune acute graft injury who survive >30 days show no significant difference in long-term survival or BOS-free time compared with recipients without early injury.

Ischemia-reperfusion injury after lung transplantation increases risk of late bronchiolitis obliterans syndrome

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is the most common cause of long-term morbidity and mortality after lung transplantation. Our hypothesis was that early ischemia-reperfusion injury after lung transplantation increases the risk of BOS.

METHODS

Data on 134 patients who had lung transplantation between January 1, 1990 and January 1, 2000, was used for univariate and multivariate logistic regression analysis.

RESULTS

After lung transplantation, 115 patients (115 of 134, 86%) survived more than 3 months. In that group, 41 patients developed BOS, of which 23 had progressive disease. Univariate analysis revealed that ischemia-reperfusion injury (p = 0.017) and two or more acute rejection episodes (p = 0.032) were predictors of BOS onset, whereas ischemia-reperfusion injury (p = 0.011) and cytomegalovirus infection (p = 0.009) predicted progressive BOS. Multivariate logistic regression analysis showed that ischemia-reperfusion injury was an independent predictor for both BOS development and BOS progression. Two or more acute rejection episodes were also an independent predictor of BOS development, whereas cytomegalovirus infection was an independent predictor of progressive BOS.

CONCLUSIONS

Ischemia-reperfusion injury increases the risk of BOS after lung transplantation.

In vivo transtracheal adenovirus-mediated transfer of human interleukin-10 gene to donor lungs ameliorates ischemia-reperfusion injury and improves early posttransplant graft function in the rat

We examined the effect of adenovirus-mediated transtracheal transfer of the human interleukin 10 (hIL-10) gene on lung ischemia-reperfusion (IR) injury, which is the insult due to hypothermic preservation plus graft reperfusion, and posttransplant lung function in Lewis rat lungs. Thirty rats were divided into 6 groups (n = 5). Groups 1 and 4 received 5 x 10(9) PFU of Ad5E1RSVhIL-10, groups 2 and 5 received 5 x 10(9) PFU of Ad5BGL2 ("empty" vector), and groups 3 and 6 received 3% sucrose (diluent). After 24 hr of in vivo transfection, lungs were stored at 4 degrees C (cold ischemic time, CIT) for 6 hr (groups 1-3) or 24 hr (groups 4-6) before transplantation. After 2 hr of reperfusion, lung function was assessed by oxygenation (FIO2, 1.0), airway pressure (AwP), and wet-to-dry (W/D) weight ratios. Rat tumor necrosis factor alpha (rTNF-alpha), interferon gamma (IFN-gamma), IL-10, and hIL-10 were measured in graft tissue and recipient plasma by ELISA and detected by immunohistochemistry (IHC). Partial pressure of oxygen (PaO2) levels in the hIL-10 group (6 hr of CIT) were higher than in empty vector and diluent groups (PaO2, 530 +/- 23 vs. 387 +/- 31 and 439 +/- 27 mmHg, respectively, p < 0.05). IL-10 rats after 24 hr of CIT showed higher PaO2 levels (260 +/- 29 mmHg) than empty vector (96 +/- 24 mmHg) or diluent (133 +/- 10 mmHg) lungs (p < 0.05). AwP and W/D ratios were reduced in hIL10 lungs (p < 0.05) compared with the other groups. rTNF-alpha and INF-gamma were reduced in tissue and plasma in groups 1 and 4 (p < 0.05). rIL-10 was reduced in the tissue of hIL-10 lungs (p < 0.05). IHC showed equal distribution of cytokines in tissue and abundant transgene expression in large and small airway epithelium in hIL-10 lungs.

Differentially expressed DNA sequences following recovery from unilateral testicular torsion in rat

The molecular response during recovery from torsion-induced stress in the testis is diverse with a variety of mechanisms. In this study, using unilateral testicular torsion in rat as a model, we used subtractive hybridisation to identify differentially expressed DNA sequences in the torsioned and control testes. Three genes were identified as being down regulated in the torsioned testis compared with controls: Control Testis genes 1, 2 and 3 (CT1, CT2 and CT3). Two genes were up regulated in the torsioned testes: Torsioned Testes genes 1 and 2 (TT1 and TT2). Differential expression was confirmed by Reverse Northern blot analysis. An homology search revealed that CT1 had 88% homology with rat metallothionein cDNA; CT2 had 81% homology with rat cell surface antigen in MHC class I, but no homology could be found for CT3. TT1 had 92% identity with rat Rieske iron-sulphur protein mRNA whereas TT2 had 73% identity with a human clone of unknown function (RP 11-252D22). These results indicate that changes in gene expression occur following torsion induced stress, and that identification of differentially expressed genes may provide insights into the mechanisms of cellular tissue damage in this model.

Elevated levels of interleukin-8 in donor lungs is associated with early graft failure after lung transplantation

Increased levels of the neutrophil chemokine interleukin (IL)-8 in the lungs of severe trauma patients can predict subsequent development of acute respiratory distress syndrome. Because the lungs of brain-dead organ donors can contain high levels of IL-8, we hypothesized that this may predispose to early graft failure in the recipient after lung transplantation. Twenty-six organ donors prospectively satisfying clinical criteria for lung donation underwent bronchoalveolar lavage and lung biopsy to determine the effect of neutrophil infiltration and IL-8 expression in the donor lung on graft function and survival in 26 respective recipients after lung transplantation. Nine recipients developed severe graft dysfunction, of whom six subsequently died (median survival: 24 d [range: 5 to 39 d]); all others survived beyond 6 mo. The IL-8 signal in the donor lung correlated with the percent neutrophils in bronchoalveolar lavage fluid (BALF) before implantation (42.4 +/- 7.24 [mean +/- SE]%, p = 0.03) and with the degree of impairment in graft oxygenation after implantation (p = 0.01). An increased level of IL-8 in the donor BALF was associated with the development of severe early graft dysfunction (p = 0.027) and with early recipient mortality (p = 0.0034). Use of donor lungs with high IL-8 levels is associated with a poor prognosis after lung transplantation. Attenuating the donor's inflammatory response before organ retrieval may improve early outcome after lung transplantation, and help maximize lung use from the existing donor pool.

Correlations among expression of intercellular adhesion molecule 1, cellular infiltration, and coronary arteriosclerosis during chronic rejection using the rat heart transplantation model

Immunologic mechanisms contribute to the development of coronary arteriosclerosis. In this study the rat heart transplantation model was used to investigate correlations among the expression of intercellular adhesion molecule 1, cellular infiltrate, and coronary arteriosclerosis during chronic rejection. Lewis rats served as heart donors and F-344 rats as recipients. Heart transplantations were performed heterotopically. The recipients were treated with cyclosporin A (5 mg/kg/day) by daily intramuscular injection for 30 days, beginning on the day of transplantation. Rejection grade and the intimal area were measured. The expression of intercellular adhesion molecule 1 and the numbers of infiltrating CD4- and CD8-positive cells and macrophages were examined immunohistochemically. The area of the intima was significantly increased in the allograft group after transplantation. In the allograft group, the level of expression of intercellular adhesion molecule 1 was considerably increased over the same time period. There was increased cellular infiltration in the 60-day group, and many expressed intercellular adhesion molecule 1. The expression of intercellular adhesion molecule 1 in vascular endothelium, infiltrating cells, and the sarcolemmal membrane of myocytes remained constant up to 120 days in the allograft group. In the allograft group, the number of infiltrating CD4- and CD8-positive cells and macrophages increased significantly between 30 and 60 days, and the infiltration of these cells remained constant. Continuous expression of intercellular adhesion molecule 1 induces the infiltration of T cells and macrophages, and the inflammation caused by such cells and their soluble products contributes to the arteriosclerotic process.

cAMP pulse during preservation inhibits the late development of cardiac isograft and allograft vasculopathy

The causes of transplant-associated coronary artery disease remain obscure, and there is no known treatment. Preservation injury of murine heterotopic vascularized cardiac isografts caused a small, albeit significant, increase in neointimal formation; preservation injury of allografts markedly increased both the incidence and severity of transplant-associated coronary artery disease. As cAMP is an important vascular homeostatic mediator the levels of which decline during organ preservation, buttressing cAMP levels solely during initial preservation both improved acute allograft function and reduced the severity of transplant-associated coronary artery disease in grafts examined 2 months later. Inhibiting the cAMP-dependent protein kinase abrogated these beneficial effects. cAMP treatment was associated with an early reduction in leukocyte infiltration and a reciprocal decrease in superoxide and increase in NO levels. These data indicate that alloantigen-independent injury to the graft, which occurs at the time of cardiac preservation, can set in motion pathological vascular events that are manifest months later. Furthermore, a cAMP pulse during cardiac preservation reduces the incidence and severity of transplant-associated coronary artery disease.

ICAM-1 antisense oligodesoxynucleotides prevent reperfusion injury and enhance immediate graft function in renal transplantation

BACKGROUND

Ischemia-reperfusion injury after organ transplantation is a major cause of delayed graft function. We showed earlier that antisense oligodesoxynucleotides (ODN) for intercellular adhesion molecule-1 (ICAM-1) ameliorate reperfusion injury after acute ischemia. This study tested the hypothesis that antisense ODN for ICAM-1 prevents ischemia-reperfusion injury and facilitates immediate graft function in a rat autotransplantation model.

METHODS

Both kidneys were removed from male Lewis rats and re-implanted the left kidney after 30 minutes of cold ischemia time. The warm ischemia time was 60 minutes. Sham operated, uninephrectomized animals served as controls for renal function and histology. ICAM-1 antisense ODN (5 mg/kg), reverse ODN, or saline-vehicle were administered to donor animals i.v. six hours before autotransplantation. Glomerular filtration rate (insulin clearance), and serum creatinine concentrations were measured 24 hours post-transplantation. Tubular necrosis severity was assessed by histological grading scale. ICAM-1 expression was determined by immunohistochemistry and Western blot.

RESULTS

Antisense ODN decreased ICAM-1 expression and leukocyte infiltration significant. Antisense ODN-treated animals showed significantly less tubular necrosis, than controls. Serum creatinine of antisense ODN-treated animals (N = 6) was 0.55 +/- 0.02 mg/dl compared to 1.92 +/- 0.07 mg/dl in reverse ODN-treated controls (N = 6; P < 0.01), 24 hours after transplantation. Antisense ODN-treated animals had normal GFR (0.93 +/- 0.07 ml/min/kidney wt) compared to sham-operated animals (0.95 +/- 0.09 ml/min/kidney wt), while autotransplanted animals treated with reverse ODN or saline-vehicle were all anuric. The ischemia-reperfusion-induced up-regulation of MHC class II was totally prevented by antisense ODN.

CONCLUSIONS

ICAM-1 inhibition ameliorates ischemia-reperfusion injury and prevents delayed graft function. Antisense ODN-treatment of donors or donor organs for ICAM-1 may be useful for the prevention of reperfusion injury in human renal transplantation.

Controlled reperfusion after lung ischemia: implications for improved function after lung transplantation

OBJECTIVES

Despite improvements in organ preservation, reperfusion injury remains a major source of morbidity and mortality after lung transplantation. This pilot study was designed to investigate the effects of controlled reperfusion after lung ischemia.

METHODS

Twenty adult pigs underwent 2 hours of warm lung ischemia by crossclamping the left bronchus and pulmonary artery. In five (group 1), the clamp was simply removed at the end of ischemia (uncontrolled reperfusion). The 15 other pigs underwent modified reperfusion using blood from the femoral artery to perfuse the lung through the pulmonary artery (pressure 40 to 50 mm Hg) for 10 minutes before removing the pulmonary artery clamp. In five (group 2), the blood was mixed with crystalloid, resulting in a substrate-enriched, hypocalcemic, hyperosmolar, alkaline solution. In five (group 3), the blood was circulated through a leukocyte-depleting filter, and the last five (group 4) underwent reperfusion with both a modified solution and white blood cell filter. Lung function was assessed 60 minutes after reperfusion, and biopsy specimens were taken.

RESULTS

Controlled reperfusion with both a white blood cell filter and modified solution (group 4) completely eliminated the reperfusion injury that occurred with uncontrolled reperfusion (group 1), resulting in complete preservation of compliance (98% +/- 1% vs 77% +/- 1%; p < 0.001, and arterial/alveolar ratio (97% +/- 2% vs 27% +/- 2%; p < 0.001); no increase in pulmonary vascular resistance (106% +/- 1% vs 198% +/- 1%; p < 0.001); lowered tissue edema (82.1% +/- 0.4% vs 84.3% +/- 0.2%; p < 0.001), and myeloperoxidase activity (0.18 +/- 0.02 vs 0.35 +/- 0.02 deltaOD/min/mg protein; p < 0.001). In contrast, using either a white blood cell filter or modified solution separately improved but did not avoid the reperfusion injury, resulting in pulmonary function and tissue edema levels that were intermediate between group 1 (uncontrolled reperfusion) and group 4 (white blood cell filter and modified solution).

CONCLUSION

After 2 hours of warm pulmonary ischemia, (1) a severe lung injury occurs after uncontrolled reperfusion, (2) controlled reperfusion with either a modified reperfusion solution or white blood cell filter limits, but does not avoid, a lung reperfusion injury, (3) reperfusion using both a modified reperfusate and white blood cell filter results in complete preservation of pulmonary function. We therefore believe surgeons should control the reperfusate after lung transplantation to improve postoperative pulmonary function.