Modified reperfusion and ischemia-reperfusion injury in human lung transplantation

OBJECTIVE: Ischemia-reperfusion injury remains a major cause of mortality and morbidity in clinical lung transplantation. Interaction of activated leukocytes with injured graft endothelial cells participates in the development of ischemia-reperfusion injury. We sought to determine if modification of the reperfusate (with depletion of leukocytes and alteration of its composition) would decrease the incidence of ischemia-reperfusion injury in human lung transplantation when compared with whole blood reperfusion in a historical group of patients. METHODS: Between June 1999 and July 2001, 23 adult patients undergoing lung transplantation consented to modified reperfusion. After implantation, a catheter was inserted into the main or individual pulmonary arteries, and modified reperfusate was administered at a pressure less than 20 mm Hg. The modified reperfusate was depleted of leukocytes, supplemented with nitroglycerin, adjusted for pH and calcium level, and enriched with aspartate, glutamate, and dextrose. After 10 minutes of modified reperfusion, the removal of pulmonary artery clamp or weaning of cardiopulmonary bypass was performed per usual protocol. Age- and diagnosis-matched historical patients served as the control group. Ischemia-reperfusion injury was defined as Pao(2)/Fio(2) < 150 with diffuse infiltrate on the radiograph in absence of other causes. RESULTS: There was no difference in donor age or oxygenation indices, recipient age, the number of patients requiring cardiopulmonary bypass, ischemia time, and recipient oxygenation indices between the modified reperfusate group and the control group. However, none of the patients in the modified reperfusate group developed ischemia-reperfusion injury in contrast to 5 patients in the control group (P <.05). The early survival in the modified reperfusate group was 96% versus 81% in the control group (P = NS). CONCLUSION: This study suggests that modification of the reperfusate content decreases the incidence of ischemia-reperfusion injury in human lung transplantation when compared with whole blood reperfusion in a historical group of patients. Modified reperfusate may allow acceptance of marginal lungs and expansion of the donor pool.     

Selective adenosine-A2A activation reduces lung reperfusion injury following transplantation

Background: The adenosine-A_2A receptor on the neutrophil is responsible for several anti-inflammatory actions. We hypothesized that DWH-146e, a selective adenosine-A_2A agonist, would reduce lung reperfusion injury following transplantation.MethodsWe used an isolated, whole blood–perfused, ventilated rabbit lung model. Donor rabbits underwent lung harvest after pulmonary arterial PGE₁ injection and Euro-Collins preservation solution flush, and lungs were preserved for 18 hours at 4°C. Group I lungs (n = 9) served as control subjects. Group II lungs (n = 9) were reperfused with whole blood that was first passed through a leukocyte-depleting filter. In group III (n = 9), DWH-146e was added to the blood reperfusate (25 μg/kg) immediately before reperfusion and was administered throughout the reperfusion period (1 μg/kg/min). All lungs were reperfused for 30 minutes.ResultsArterial oxygenation in group II and group III was significantly higher than that of group I after 30 minutes of reperfusion (514.27 ± 35.80 and 461.12 ± 43.77 vs 91.41 ± 20.58 mm Hg, p < .001). Pulmonary vascular resistance was significantly reduced in group III (22,783 ± 357 dynes · s · cm⁻⁵) compared to both group II and group I (31,057 ± 1743 and 36,911 ± 2173 dynes · s · cm⁻⁵, p < .001). Airway compliance was improved in groups II and III when compared to group I (1.68 ± 0.08 and 1.68 ± 0.05 vs 1.36 ± 0.13, p = .03). Microvascular permeability in group III was reduced to 106.82 ± 17.09 compared with 165.70 ± 21.83 ng Evans blue dye per gram of tissue in group I (p = .05). Group III myeloperoxidase activity was 39.88 ± 4.87 compared with 88.70 ± 18.69 ΔOD/g/min in group I (p = .03); group II myeloperoxidase activity was 56.06 ± 7.46.ConclusionsDWH-146e reduced lung neutrophil sequestration and dramatically improved pulmonary graft function. Neutrophils are important components of the inflammatory cascade of reperfusion injury and their source may include both the circulating blood and the lung graft itself. Selective adensosine-A_2A activation interrupts the neutrophil-mediated inflammatory response and reduces lung reperfusion injury following transplantation.     

Pulmonary macrophages are involved in reperfusion injury after lung transplantation

BACKGROUND: Reperfusion injury is a perplexing cause of early graft failure after lung transplantation. Although recipient neutrophils are thought to have a role in the development of reperfusion injury, some researchers have shown that neutrophils are not involved in its earliest phase. Intrinsic donor pulmonary macrophages may be responsible for this early phase of injury. Using the macrophage inhibitor gadolinium chloride, we attempted to investigate the role of pulmonary macrophages in reperfusion injury after lung transplantation. METHODS: Using our isolated, ventilated, blood-perfused rabbit lung model, all groups underwent lung harvest followed by 18-hour storage (4 degrees C) and blood reperfusion for 30 minutes. Group I served as a control. Group II received gadolinium chloride at 7 mg/kg 24 hours before harvest. Group III received gadolinium chloride at 14 mg/kg 24 hours before harvest. RESULTS: Group III had significantly improved arterial oxygenation and pulmonary artery pressures compared with groups I and II after 30 minutes of reperfusion. CONCLUSIONS: The earliest phase of reperfusion injury after lung transplantation involves donor pulmonary macrophages.     

C1-esterase inhibitor deficiency and elective caesarean section

C1-esterase inhibitor deficiency is a rare disorder of the complement system characterised by episodes of cutaneous and mucosal oedema. Life-threatening airway oedema can follow airway instrumentation or minor trauma. We describe the successful management of a 37-year-old primiparous woman with inherited C1-esterase inhibitor deficiency who was admitted at 38 weeks' gestation for elective caesarean section. Whilst undergoing general anaesthesia 18 months previously she had experienced facial and pharyngeal oedema despite prophylaxis (one unit of fresh frozen plasma). On this occasion she underwent elective caesarean section following intrathecal anaesthesia with 0.5% hyperbaric bupivacaine 2 mL and diamorphine 300 microg. Cardiovascular stability was ensured using glycopyrolate and intravenous Hartmann's solution 2 L; a live female infant was delivered successfully. There were no peri- or postoperative complications. Regional anaesthesia is the safest method for providing surgical anaesthesia in the obstetric patient. We believe elective caesarean section under regional anaesthesia should be considered if there are predicted difficulties with vaginal delivery.     

N-acetylcysteine reduces lung reperfusion injury after deep hypothermia and total circulatory arrest

OBJECTIVE: We hypothesized that the use of N-acetylcysteine would ameliorate the lung reperfusion injury observed after deep hypothermia and total circulatory arrest (DHTSA). METHODS: Experiments were carried out on 12 adult mongrel dogs of either sex weighing 25 to 30 kg. The animals were randomly divided into two groups of six animals each. All animals were cooled to an esophageal temperature of 15 degrees C during 30 minutes and underwent 60 minutes of DHTSA, followed by the reinstitution of cardiopulmonary bypass (CPB) and rewarming. Before rewarming, while 100 mL physiologic saline solution was added into the pump in group I, 50 mg/kg N-acetylcysteine(NAC) was given in group II. Heart rate, mean arterial pressure, pulmonary arterial pressure, left atrial pressure, central venous pressure, and cardiac output were recorded. To measure lung tissue malondialdehyde (MDA), water content and polymorphonuclear leukocytes (PMNs) count, lung tissue samples were taken before CPB and after weaning CPB. In addition, alveolar-arterial oxygen difference (AaDO(2))()for tissue oxygenation was calculated by obtaining arterial blood gas samples. Dynamic lung compliance (DLC) was measured before CPB and after CPB. RESULTS: MDA levels before CPB of 44.2 +/- 3.9 nmol/g tissue rose to 76.6 +/- 5.6 nmol/g tissue after weaning CPB in group I (p = 0.004). In group II also, the MDA levels increased from 43.5 +/- 4.2 to 57.4 +/- 5.6 nmol MDA/g tissue after weaning CPB (p = 0.006). The MDA increase in group II after CPB was found to be significantly lower than in group I (p = 0.006). The wet-to-dry lung weight ratio in the NAC group was 5.1 +/- 0.2, significantly less than in the control group (5.9 +/- 0.3), (p = 0.004). AaDO(2) significantly increased in the group I and II (p = 0.002 and p = 0.002, respectively); this elevation in group I was significant than in group II (p = 0.044). In histopathological examination, it was observed that neutrophil counts in the lung parenchyma rose significantly after CPB in both groups (p < 0.001). The increase in group I was significantly larger than group II (p < 0.001). CONCLUSIONS: Results represented in our study indicate that addition of NAC into the pump after DHTSA can reduce lung reperfusion injury.     

Neutrophil elastase inhibitor ameliorates reperfusion injury in a canine model of lung transplantation

BACKGROUND: We investigated the effects of neutrophil elastase inhibitor ONO-5046 Na on lung ischemia-reperfusion injury in a canine model of single lung transplantation. METHODS: 24 mongrel dogs, 12 donors and 12 recipients, were used for single lung transplantation. Lung grafts were preserved for 18 h by cold ischemia then transplanted into the left thoracic cavity of recipients. In 6 recipients (ONO group), a bolus of ONO-5046 Na (10 mg/kg) was introduced before reperfusion and followed by continuous infusion (10 mg/kg/h). The remaining 6 recipients (control group) did not receive ONO-5046 Na and thus served as controls. We evaluated lung function and respiratory parameters over 240 min. RESULTS: The total cell number in bronchoalveolar lavage fluid increased significantly in the control group in comparison to that in the ONO group. Histologic scores after 4 h of reperfusion and myeloperoxidase activity were significantly lower in the ONO group than in the control group. CONCLUSION: Neutrophil elastase inhibitor ONO-5046 Na may be useful in ameliorating lung reperfusion injury after transplantation.     

Endogenous interleukin-4 and interleukin-10 regulate experimental lung ischemia reperfusion injury

BACKGROUND: Regulatory cytokines play functional roles in experimental heart, hindlimb, and liver ischemia reperfusion injury. However, little is known about their involvement in direct lung ischemia reperfusion injury (LIRI). These studies were undertaken to investigate the role of two regulatory cytokines, interleukin-4 (IL-4) and IL-10, in an in vivo model of LIRI. METHODS: Left lungs of Long-Evans rats underwent normothermic ischemia for 90 minutes and reperfusion for up to 4 hours. Treated animals received either recombinant IL-4 or recombinant IL-10, or antibodies to IL-4 or IL-10 immediately before reperfusion. Lung injury was quantitated by permeability indices, lung parenchymal neutrophil sequestration (myeloperoxidase [MPO] content), and alveolar leukocyte content in bronchoalveolar lavage (BAL) effluent. Expression of IL-4 and IL-10 was determined by immunoblotting, and mRNA expression for early response cytokines was evaluated by ribonuclease protection assays. RESULTS: IL-4 and IL-10 protein expression was significant after 2 hours of reperfusion. Animals receiving anti-IL-4 (p = 0.05) and anti-IL-10 (p = 0.01) antibodies demonstrated increased permeabilities compared with positive controls. Lung tissue neutrophil accumulation (p < 0.004) and BAL leukocyte content (p < 0.04) were also significantly increased in animals receiving anti-IL-10 antibodies. Conversely, animals receiving recombinant IL-4 and recombinant IL-10 demonstrated reduced permeabilities and lung MPO content. Both anti-IL-4 and anti-IL-10 treatment increased mRNA expression for a number of early response cytokines, including TNF-alpha and IL-1beta. CONCLUSIONS: IL-4 and IL-10 are expressed in response to LIRI and function to decrease injury severity. These effects are partly due to modulated expression of early proinflammatory cytokines.     

Living-donor lobar lung transplantation for bronchiolitis obliterans after bone marrow transplantation

We report a successful case of living-donor lobar lung transplantation (LDLLT) for severe bronchiolitis obliterans (BO) after bone marrow transplantation (BMT). The patient is a 29-year-old woman who underwent BMT because of aplastic anemia in 1995. In 1996, BO developed in the patient because of chronic graft-versus-host disease. In May 2000, a LDLLT was performed. Pulmonary function tests showed improvement of both vital capacity and forced expiratory volume in 1 second. At present, 91 months after BMT and 38 months after lung transplantation, the patient is in good health. LDLLT may offer a therapeutic option for the treatment of BO after BMT.     

sCR1sLe ameliorates ischemia/reperfusion injury in experimental lung transplantation

BACKGROUND: The nonspecific immune response with activation of the complement system and polymorphonuclear leukocytes is important for the mediation of reperfusion injury after lung transplantation. In this study, we investigated the combined blockade of the complement system and leukocyte adhesion by a novel drug combining soluble complement receptor type 1 (sCR1, CD35) with the selectin ligand sialyl Lewis X (sLe(X), CD15s) synthesized to sCR1sLe(X). Both sCR1 and sCR1sLe(X) were supplied by AVANT Immunotherapeutics, Inc, Needham, Massachusetts. METHODS: Orthotopic allogeneic single left lung transplantation was performed in male rats (Brown Norway to Fischer F344; n = 5 in all groups) after a total ischemic time of 20 hours. Recipients received either no specific treatment (control) or administration of sCR1 (10 mg/kg) or sCR1sLe(X) (10 mg/kg) 15 minutes before reperfusion by intracardiac injection. Twenty-four hours after reperfusion, the native contralateral lung was occluded to assess gas exchange of the graft only. In additional animals (5 per group), lung tissue was frozen 24 hours after reperfusion and assessed for myeloperoxidase activity as a measurement of neutrophil migration into the graft and thiobarbituric acid reactive substances to quantify lipid peroxidation. RESULTS: Graft function as assessed by arterial PO (2) in recipients treated with sCR1sLeX was superior not only to that of controls (383 +/- 53 vs 56 +/- 7 mm Hg, P =. 000095) but also to that of animals treated with sCR1 (243 +/- 45 mm Hg, P =.031). This improvement was confirmed by significant reduction of neutrophil migration (0.33 +/- 0.05 vs control, 1.0 +/- 0.09 DeltaOD/mg/min, P =.0000024) and lipid peroxidation (6.2 +/- 0. 38 vs control, 10.6 +/- 0.54 pmol/g, P =.00021). CONCLUSIONS: Our data indicate that combined inhibition of complement activation and leukocyte adhesion with sCR1sLe(X) reduces reperfusion injury significantly and that both mechanisms are effectively inhibited in this model.     

Endoscopic repair of bronchial dehiscence after lung transplantation

We report a case of bronchial dehiscence after right single lung transplantation and describe a novel means of management: bronchoscopic closure of the defect with alpha-cyanoacrylate glue.