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226: Lung transplant recipients with nocturnal reflux have an increased risk of gastric aspiration, irrespective of the presence of BOS
The Journal of Heart and Lung Transplantation Volume 26, Number 2S
226 LUNG TRANSPLANT RECIPIENTS WITH NOCTURNAL REFLUX HAVE AN INCREASED RISK OF GASTRIC ASPIRATION, IRRESPECTIVE OF THE PRESENCE OF BOS K. Blondeau,1 V. Mertens,1 B.M. Vanaudenaerde,2 D.E. van Raemdonck,2 G.M. Verleden,2 D. Sifrim,1 L.J. Dupont,2 1 Center for Gastroenterological Research, Katholieke Universiteit Leuven, Leuven, Belgium; 2Lung Transplantation Unit, University Hospital Gasthuisberg, Leuven, Belgium Purpose: Gastroesophageal reflux has been associated with the development of Bronchiolitis obliterans syndrome (BOS) after lung transplantation (LTx) and anti-reflux surgery has been suggested to protect LTx recipients from BOS. The aim of our study was to investigate the occurence of gastric aspiration and the relation to acid and non-acid reflux both in stable lung transplant recipients and in patients with BOS. Methods and Materials: BALF was collected from LTx recipients and pepsin levels were measured using ELISA. Acid and non-acid reflux was detected by means of a 24hrs pH-impedance recording. A control group of 14 non-transplanted patients requiring bronchoscopy was included in the analysis. Results: All 66 LTx patients had detectable levels of pepsin in the BALF. The pepsin levels were significantly higher in LTx recipients (545 ng/ml) when compared to controls (23.8 ng/ml). Patients with a SSLTx had significantly higher levels of pepsin (768.8ng/ml) in the BALF compared to patients with a SLTx (260.2ng/ml) or HLTx (109.8ng/ml). There was no significant correlation between pepsin levels and FEV1 (r2⫽0.013, p⫽0.5). Pepsin levels in patients with BOSⱖ1 were similar to patients without BOS (610 ng/ml versus 600.5 ng/ml, respectively). There was no correlation between pepsin and number of reflux events. However, pepsin levels were significantly higher in patients with nocturnal reflux episodes (611ng/ml) compared to patients without nocturnal reflux (242 ng/ml, p⫽0.05). Nineteen patients had predominantly acid reflux during the night, 11 had predominantly non-acid reflux and 3 patients had both acid and non-acid reflux. Conclusions: All LTx recipients had elevated levels of pepsin in the lungs, suggesting that gastric aspiration is a common finding after LTx. The presence of acid or non-acid reflux during the night may increase the risk of gastric aspiration. However, gastric aspiration, as determined by the amount of pepsin in the BALF does not appear to be related to the presence or degree of BOS. 227 ENDOTHELIN AXIS UP-REGULATION IN A MURINE MODEL OF BRAIN STEM DEATH A.J. Sutherland,1 F. Kermeen,1 J. Dunning,1 J.F. Fraser,1 1Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia Purpose: The molecular mechanisms of ischaemia-reperfusion injury (IRI) post lung transplant (LT) remains unclear. Alveolar macrophages (AM) are implicated in the development of acute lung injury. Endothelin (ET)-1 has been shown to be raised post LT and in acute inflammatory processes. The link between AM and ET-1 has not been described in lung transplantation, nor in the donor. Aims: 1. To investigate ratio of AM and pulmonary neutrophils in a murine model of BSD. 2 To investigate the endothelin axis in the AM, specifically ET-1 and the receptor subtypes, ET-A and ET-B. Methods and Materials: Fourteen Wistar-Kyoto rats were anaesthetised, ventilated and a catheter positioned in the subdural space. The catheter was inflated in eight rats inducing BSD; with six sham rats there was no inflation. After 4 hours of ventilation, lung specimens
Abstracts
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were immunohistochemically labelled with ET1 ET-A and ET-B. CD68 staining was used to characterise the AM. Results: The ratio of alveolar macrophages to polymorphonuclear neutrophils was significantly greater in BSD group than control (9.07⫾4.13 Vs 3.09 ⫾ 0.59, p⫽0.002) .ET-1, ETA R and ETB R levels were elevated in the BSD group (27.57⫾5.26 Vs 7.01⫾1.75, 36.1⫾4.57 Vs 17.73⫾2.56, 54.98⫾7.07 Vs 19.75⫾3.73, respectively; p⬍0.0001 compared with control. Conclusions: In a murine model, BSD is associated with up-regulation of the pulmonary endothelin axis. The ratio of alveolar macrophage to infiltrating neutrophils is significantly increased after 4 hours of BSD compared to the sham-control. Alveolar macrophages express significantly higher levels of ET-1 in BSD compared to control. Endothelin blockade in BSD donors may reduce the risk of IRI.
228 HYPOXIA-REPERFUSION INJURY INCREASES CELL SPECIFIC ENDOTHELIAL PROGENITOR CELL ADHESION IN AN ICAM-1 DEPENDENT MANNER J.L. Jackman,1 E. Partidge,1 M. Ward,2 L. Tumiati,1 M. Badiwala,1 R. Sheshgiri,1 D. Stewart,2 V. Rao,1 1Cardiovascular Surgery, University of Toronto, Toronto, ON, Canada; 2Division of Cardiology, University of Toronto, Toronto, ON, Canada Purpose: Transplant vasculopathy (TV) remains a primary cause of long-term graft loss. TV is characterized by the infiltration of vascular smooth muscle cells at sites of endothelial damage. Bone-marrow derived endothelial progenitor cells (EPCs) have an antiatherogenic effect, making them an attractive candidate for preventing TV. It is important to understand how EPCs home to sites of transplantation induced endothelial injury to be able to augment their atheroprotective potential. In this study we examined the adhesion of EPCs to vascular cells following hypoxia and reoxygenation to simulate reperfusion injury during transplantation. Methods and Materials: Human coronary artery endothelial cells (EC) and smooth muscle cells (SMC) were subjected to 18hr of hypoxia (pO2 ⫽ 0.1%) followed by 4hr of reperfusion (pO2 ⫽ 21%). EPCs isolated from human peripheral blood were fluorescently labeled and incubated with hypoxia-injured EC or SMC. After 30 minutes adherent EPCs were counted using fluorescent microscopy. Normal and TNF-␣ injured EC and SMC were used as controls. ICAM-1 (Intracellular Adhesion Molecule 1) expression in EC or SMC was assessed at different reperfusion times by western blotting. Results: Basal EPC adhesion to SMC was found to be 1.44⫾0.10 (p⫽0.05) fold higher than adhesion to EC. After hypoxic injury, EPC adhesion to EC increased by 1.59⫾0.03 fold (p⬍0.05), while adhesion to SMC increased by 2.84⫾0.44 fold (p⬍0.01). This increase in adhesion correlated with ICAM-1 expression in both cell types. While basal ICAM-1 expression was higher in SMC than EC, expression increased in both cell types throughout reperfusion. Conclusions: Our data has shown that hypoxia-reoxygenation injury upregulated ICAM-1 in both endothelial and smooth muscle cells, coinciding with increased EPC adhesion. This suggests that hypoxia and reperfusion during transplantation activates expression of ICAM-1 in both EC and SMC. This activation may play a key role in homing of recipient EPCs to the transplanted organ.
229 APOPTOSIS INHIBITION IMPROVES LEFT VENTRICULAR FUNCTION AFTER PROLONGED COLD CARDIOPLEGIC ARREST
226 LUNG TRANSPLANT RECIPIENTS WITH NOCTURNAL REFLUX HAVE AN INCREASED RISK OF GASTRIC ASPIRATION, IRRESPECTIVE OF THE PRESENCE OF BOS K. Blondeau,1 V. Mertens,1 B.M. Vanaudenaerde,2 D.E. van Raemdonck,2 G.M. Verleden,2 D. Sifrim,1 L.J. Dupont,2 1 Center for Gastroenterological Research, Katholieke Universiteit Leuven, Leuven, Belgium; 2Lung Transplantation Unit, University Hospital Gasthuisberg, Leuven, Belgium Purpose: Gastroesophageal reflux has been associated with the development of Bronchiolitis obliterans syndrome (BOS) after lung transplantation (LTx) and anti-reflux surgery has been suggested to protect LTx recipients from BOS. The aim of our study was to investigate the occurence of gastric aspiration and the relation to acid and non-acid reflux both in stable lung transplant recipients and in patients with BOS. Methods and Materials: BALF was collected from LTx recipients and pepsin levels were measured using ELISA. Acid and non-acid reflux was detected by means of a 24hrs pH-impedance recording. A control group of 14 non-transplanted patients requiring bronchoscopy was included in the analysis. Results: All 66 LTx patients had detectable levels of pepsin in the BALF. The pepsin levels were significantly higher in LTx recipients (545 ng/ml) when compared to controls (23.8 ng/ml). Patients with a SSLTx had significantly higher levels of pepsin (768.8ng/ml) in the BALF compared to patients with a SLTx (260.2ng/ml) or HLTx (109.8ng/ml). There was no significant correlation between pepsin levels and FEV1 (r2⫽0.013, p⫽0.5). Pepsin levels in patients with BOSⱖ1 were similar to patients without BOS (610 ng/ml versus 600.5 ng/ml, respectively). There was no correlation between pepsin and number of reflux events. However, pepsin levels were significantly higher in patients with nocturnal reflux episodes (611ng/ml) compared to patients without nocturnal reflux (242 ng/ml, p⫽0.05). Nineteen patients had predominantly acid reflux during the night, 11 had predominantly non-acid reflux and 3 patients had both acid and non-acid reflux. Conclusions: All LTx recipients had elevated levels of pepsin in the lungs, suggesting that gastric aspiration is a common finding after LTx. The presence of acid or non-acid reflux during the night may increase the risk of gastric aspiration. However, gastric aspiration, as determined by the amount of pepsin in the BALF does not appear to be related to the presence or degree of BOS. 227 ENDOTHELIN AXIS UP-REGULATION IN A MURINE MODEL OF BRAIN STEM DEATH A.J. Sutherland,1 F. Kermeen,1 J. Dunning,1 J.F. Fraser,1 1Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia Purpose: The molecular mechanisms of ischaemia-reperfusion injury (IRI) post lung transplant (LT) remains unclear. Alveolar macrophages (AM) are implicated in the development of acute lung injury. Endothelin (ET)-1 has been shown to be raised post LT and in acute inflammatory processes. The link between AM and ET-1 has not been described in lung transplantation, nor in the donor. Aims: 1. To investigate ratio of AM and pulmonary neutrophils in a murine model of BSD. 2 To investigate the endothelin axis in the AM, specifically ET-1 and the receptor subtypes, ET-A and ET-B. Methods and Materials: Fourteen Wistar-Kyoto rats were anaesthetised, ventilated and a catheter positioned in the subdural space. The catheter was inflated in eight rats inducing BSD; with six sham rats there was no inflation. After 4 hours of ventilation, lung specimens
Abstracts
S141
were immunohistochemically labelled with ET1 ET-A and ET-B. CD68 staining was used to characterise the AM. Results: The ratio of alveolar macrophages to polymorphonuclear neutrophils was significantly greater in BSD group than control (9.07⫾4.13 Vs 3.09 ⫾ 0.59, p⫽0.002) .ET-1, ETA R and ETB R levels were elevated in the BSD group (27.57⫾5.26 Vs 7.01⫾1.75, 36.1⫾4.57 Vs 17.73⫾2.56, 54.98⫾7.07 Vs 19.75⫾3.73, respectively; p⬍0.0001 compared with control. Conclusions: In a murine model, BSD is associated with up-regulation of the pulmonary endothelin axis. The ratio of alveolar macrophage to infiltrating neutrophils is significantly increased after 4 hours of BSD compared to the sham-control. Alveolar macrophages express significantly higher levels of ET-1 in BSD compared to control. Endothelin blockade in BSD donors may reduce the risk of IRI.
228 HYPOXIA-REPERFUSION INJURY INCREASES CELL SPECIFIC ENDOTHELIAL PROGENITOR CELL ADHESION IN AN ICAM-1 DEPENDENT MANNER J.L. Jackman,1 E. Partidge,1 M. Ward,2 L. Tumiati,1 M. Badiwala,1 R. Sheshgiri,1 D. Stewart,2 V. Rao,1 1Cardiovascular Surgery, University of Toronto, Toronto, ON, Canada; 2Division of Cardiology, University of Toronto, Toronto, ON, Canada Purpose: Transplant vasculopathy (TV) remains a primary cause of long-term graft loss. TV is characterized by the infiltration of vascular smooth muscle cells at sites of endothelial damage. Bone-marrow derived endothelial progenitor cells (EPCs) have an antiatherogenic effect, making them an attractive candidate for preventing TV. It is important to understand how EPCs home to sites of transplantation induced endothelial injury to be able to augment their atheroprotective potential. In this study we examined the adhesion of EPCs to vascular cells following hypoxia and reoxygenation to simulate reperfusion injury during transplantation. Methods and Materials: Human coronary artery endothelial cells (EC) and smooth muscle cells (SMC) were subjected to 18hr of hypoxia (pO2 ⫽ 0.1%) followed by 4hr of reperfusion (pO2 ⫽ 21%). EPCs isolated from human peripheral blood were fluorescently labeled and incubated with hypoxia-injured EC or SMC. After 30 minutes adherent EPCs were counted using fluorescent microscopy. Normal and TNF-␣ injured EC and SMC were used as controls. ICAM-1 (Intracellular Adhesion Molecule 1) expression in EC or SMC was assessed at different reperfusion times by western blotting. Results: Basal EPC adhesion to SMC was found to be 1.44⫾0.10 (p⫽0.05) fold higher than adhesion to EC. After hypoxic injury, EPC adhesion to EC increased by 1.59⫾0.03 fold (p⬍0.05), while adhesion to SMC increased by 2.84⫾0.44 fold (p⬍0.01). This increase in adhesion correlated with ICAM-1 expression in both cell types. While basal ICAM-1 expression was higher in SMC than EC, expression increased in both cell types throughout reperfusion. Conclusions: Our data has shown that hypoxia-reoxygenation injury upregulated ICAM-1 in both endothelial and smooth muscle cells, coinciding with increased EPC adhesion. This suggests that hypoxia and reperfusion during transplantation activates expression of ICAM-1 in both EC and SMC. This activation may play a key role in homing of recipient EPCs to the transplanted organ.
229 APOPTOSIS INHIBITION IMPROVES LEFT VENTRICULAR FUNCTION AFTER PROLONGED COLD CARDIOPLEGIC ARREST