Evaluating newly approved drugs in combination regimens for multidrug-resistant tuberculosis with fluoroquinolone resistance (endTB-Q): study protocol for a multi-country randomized controlled trial

BACKGROUND

Treatment for fluoroquinolone-resistant multidrug-resistant/rifampicin-resistant tuberculosis (pre-XDR TB) often lasts longer than treatment for less resistant strains, yields worse efficacy results, and causes substantial toxicity. The newer anti-tuberculosis drugs, bedaquiline and delamanid, and repurposed drugs clofazimine and linezolid, show great promise for combination in shorter, less-toxic, and effective regimens. To date, there has been no randomized, internally and concurrently controlled trial of a shorter, all-oral regimen comprising these newer and repurposed drugs sufficiently powered to produce results for pre-XDR TB patients.

METHODS

endTB-Q is a phase III, multi-country, randomized, controlled, parallel, open-label clinical trial evaluating the efficacy and safety of a treatment strategy for patients with pre-XDR TB. Study participants are randomized 2:1 to experimental or control arms, respectively. The experimental arm contains bedaquiline, linezolid, clofazimine, and delamanid. The control comprises the contemporaneous WHO standard of care for pre-XDR TB. Experimental arm duration is determined by a composite of smear microscopy and chest radiographic imaging at baseline and re-evaluated at 6 months using sputum culture results: participants with less extensive disease receive 6 months and participants with more extensive disease receive 9 months of treatment. Randomization is stratified by country and by participant extent-of-TB-disease phenotype defined according to screening/baseline characteristics. Study participation lasts up to 104 weeks post randomization. The primary objective is to assess whether the efficacy of experimental regimens at 73 weeks is non-inferior to that of the control. A sample size of 324 participants across 2 arms affords at least 80% power to show the non-inferiority, with a one-sided alpha of 0.025 and a non-inferiority margin of 12%, against the control in both modified intention-to-treat and per-protocol populations.

DISCUSSION

This internally controlled study of shortened treatment for pre-XDR TB will provide urgently needed data and evidence for clinical and policy decision-making around the treatment of pre-XDR TB with a four-drug, all-oral, shortened regimen.

TRIAL REGISTRATION

ClinicalTrials.Gov NCT03896685. Registered on 1 April 2018; the record was last updated for study protocol version 4.3 on 17 March 2023.

Evaluating newly approved drugs for multidrug-resistant tuberculosis (endTB): study protocol for an adaptive, multi-country randomized controlled trial

BACKGROUND

Treatment of multidrug- and rifampin-resistant tuberculosis (MDR/RR-TB) is expensive, labour-intensive, and associated with substantial adverse events and poor outcomes. While most MDR/RR-TB patients do not receive treatment, many who do are treated for 18 months or more. A shorter all-oral regimen is currently recommended for only a sub-set of MDR/RR-TB. Its use is only conditionally recommended because of very low-quality evidence underpinning the recommendation. Novel combinations of newer and repurposed drugs bring hope in the fight against MDR/RR-TB, but their use has not been optimized in all-oral, shorter regimens. This has greatly limited their impact on the burden of disease. There is, therefore, dire need for high-quality evidence on the performance of new, shortened, injectable-sparing regimens for MDR-TB which can be adapted to individual patients and different settings.

METHODS

endTB is a phase III, pragmatic, multi-country, adaptive, randomized, controlled, parallel, open-label clinical trial evaluating the efficacy and safety of shorter treatment regimens containing new drugs for patients with fluoroquinolone-susceptible, rifampin-resistant tuberculosis. Study participants are randomized to either the control arm, based on the current standard of care for MDR/RR-TB, or to one of five 39-week multi-drug regimens containing newly approved and repurposed drugs. Study participation in all arms lasts at least 73 and up to 104 weeks post-randomization. Randomization is response-adapted using interim Bayesian analysis of efficacy endpoints. The primary objective is to assess whether the efficacy of experimental regimens at 73 weeks is non-inferior to that of the control. A sample size of 750 patients across 6 arms affords at least 80% power to detect the non-inferiority of at least 1 (and up to 3) experimental regimens, with a one-sided alpha of 0.025 and a non-inferiority margin of 12%, against the control in both modified intention-to-treat and per protocol populations.

DISCUSSION

The lack of a safe and effective regimen that can be used in all patients is a major obstacle to delivering appropriate treatment to all patients with active MDR/RR-TB. Identifying multiple shorter, safe, and effective regimens has the potential to greatly reduce the burden of this deadly disease worldwide.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT02754765. Registered on 28 April 2016; the record was last updated for study protocol version 3.3, on 27 August 2019.

Targeting of c-kit+ haematopoietic progenitor cells prevents hypoxic pulmonary hypertension

Haematopoietic c-kit+ progenitor cells may contribute to pulmonary vascular remodelling and pulmonary hypertension (PH). Stromal derived factor-1 (SDF-1/CXCL12) and its receptors CXCR4 and CXCR7 have been shown to be critical for homing and mobilisation of haematopoietic c-kit+ progenitor cells in the perivascular niche. We administered AMD3100, a CXCR4 antagonist, and CCX771, a CXCR7 antagonist, to chronic hypoxia exposed mice in order to study the role of c-kit+ progenitor cells in PH. CXCL12, CXCR4 and CXCR7 protein expression, haemodynamic parameters, right ventricular mass, extent of vascular remodelling and perivascular progenitor cell accumulation were studied. Chronic hypoxia-exposed mice showed increased total lung tissue expression of CXCR4, CXCR7 and CXCL12 after development of PH. This was associated with significantly increased right ventricular systolic pressure and evidence of right ventricular hypertrophy, vascular remodelling and perivascular c-kit+/sca-1+ progenitor cell accumulation. CCX771 administration did not abrogate these effects. In contrast, administration of AMD3100, whether alone or combined with CCX771, prevented vascular remodelling, PH and perivascular accumulation of c-kit+/sca-1+ progenitor cells, with a synergistic effect of these agents. This study offers important pathophysiological insights into the role of haematopoietic c-kit+ progenitors in hypoxia-induced vascular remodelling and may have therapeutic implications for PH.

Dendritic cell recruitment in lesions of human and experimental pulmonary hypertension

In the present study, the hypothesis that dendritic cells (DCs), key players in immunity and tolerance, might be involved in the immunopathology of idiopathic pulmonary arterial hypertension (IPAH) was tested. The phenotype and localisation of DCs were characterised by immunohistochemistry and double-labelling immunofluorescence in lung samples from controls, human IPAH patients and an experimental pulmonary hypertension model (monocrotaline-exposed rats). As compared with controls, morphometric analysis demonstrated increased numbers of dendritic cell-specific intercellular adhesion molecule-grabbing nonintegrin (DC-SIGN)-positive cells in muscular pulmonary arteries in IPAH and OX-62-positive DCs in monocrotaline-induced pulmonary hypertension. In human samples, the mean+/-SEM number of DC-SIGN-positive cells.artery(-1) of 100-300 microm diameter was 1.4+/-0.4 in controls versus 26.4+/-2.7 in IPAH. In rats, the number of OX-62-positive cells.artery(-1) of 50-150 microm diameter was 0.5+/-0.2 in controls, and 0.7+/-0.5, 3.1+/-0.5 and 8.4+/-0.6 at day 7, 14 and 28 after monocrotaline exposure, respectively. Human complex lesions of muscular pulmonary arteries showed transmural DC infiltration. Phenotyping revealed an immature DC profile in human and experimental pulmonary hypertension. The results support the concept that immature dendritic cells accumulate in remodelled pulmonary vessels and hence could be involved in the immunopathology of pulmonary hypertension.

Fractalkine-induced smooth muscle cell proliferation in pulmonary hypertension

Pulmonary hypertension is characterised by a progressive increase in pulmonary arterial resistance due to endothelial and smooth muscle cell proliferation resulting in chronic obstruction of small pulmonary arteries. There is evidence that inflammatory mechanisms may contribute to the pathogenesis of human and experimental pulmonary hypertension. The aim of the study was to address the role of fractalkine (CX3CL1) in the inflammatory responses and pulmonary vascular remodelling of a monocrotaline-induced pulmonary hypertension model. The expression of CX3CL1 and its receptor CX3CR1 was studied in monocrotaline-induced pulmonary hypertension by means of immunohistochemistry and quantitative reverse-transcription PCR on laser-captured microdissected pulmonary arteries. It was demonstrated that CX3CL1 was expressed by inflammatory cells surrounding pulmonary arterial lesions and that smooth muscle cells from these vessels had increased CX3CR1 expression. It was then shown that cultured rat pulmonary artery smooth muscle cells expressed CX3CR1 and that CX3CL1 induced proliferation but not migration of these cells. In conclusion, the current authors proposed that fractalkine may act as a growth factor for pulmonary artery smooth muscle cells. Chemokines may thus play a role in pulmonary artery remodelling.

Prevention of hepatopulmonary syndrome and hyperdynamic state by pentoxifylline in cirrhotic rats

Inhibition of tumour necrosis factor-alpha (TNF-alpha), levels of which are increased in the blood of cirrhotic rats, prevents hyperdynamic circulatory state, mainly by decreasing the vascular overproduction of nitric oxide. Hepatopulmonary syndrome, which is characterised by intrapulmonary vascular dilatation and increased alveolar to arterial oxygen tension difference (PA-a,O2), is mainly related to pulmonary over-production of NO by macrophages accumulated in lung vessels. Since TNF-alpha is a potent activator of macrophagic inducible nitric oxide synthase (NOS), the aim of this study was to investigate whether TNF-alpha inhibition prevented hepatopulmonary syndrome and hyperdynamic circulatory state in rats with cirrhosis. TNF-alpha was inhibited by 5 weeks of pentoxifylline (10 mg x kg body weigh(-1) x day(-1)) in rats with cirrhosis induced by common bile duct ligation. Cardiac output, pulmonary and systemic vascular resistance, PA-a,O2 and cerebral uptake of intravenous technetium-99m-labelled albumin macroaggregates (which reflects intrapulmonary vascular dilatation) were similar in sham- and pentoxifylline-treated cirrhotic rats. Blood TNF-alpha concentrations and pulmonary intravascular macrophage sequestration, as assessed by morphometric analysis and radioactive colloid uptake, were decreased with pentoxifylline. Pentoxifylline also prevented increases in aorta and lung NOS activities and inducible NOS expression. Thus pentoxifylline prevents development of hyperdynamic circulatory state and hepatopulmonary syndrome, probably by inhibiting the effects of tumour necrosis factor-alpha on vascular nitric oxide synthase and intravascular macrophages. These results support an important role for tumour necrosis factor-alpha in the genesis of hepatopulmonary syndrome.

Role of nitric oxide in hepatopulmonary syndrome in cirrhotic rats

The hepatopulmonary syndrome (HPS) is characterized by intrapulmonary vascular dilatations and an increased alveolar-arterial oxygen difference (AaPO(2)). Exhaled nitric oxide (NO) concentrations are elevated, suggesting that pulmonary NO overproduction may be the mechanism underlying HPS. We investigated whether common bile duct ligation in rats results in lung NO overproduction and whether normalization of NO synthesis by a 6-wk course of N(G)-nitro-L-arginine methyl ester (L-NAME) (5 mg x kg(-)(1) x d(-)(1)) prevents HPS. Untreated cirrhotic rats showed increases in AaPO(2) and in cerebral uptake of intravenous (99m)Tc-labeled albumin macroaggregates (indicating intrapulmonary vascular dilatations), with decreases in pulmonary vascular resistance and in pulmonary vasoconstriction induced by angiotensin II and hypoxia. Increases were found in exhaled NO; pulmonary total and calcium-dependent NO synthase (NOS) activities; and pulmonary expression of inducible and, to a lesser extent, endothelial NOS. Accumulation of intravascular macrophages accounted for the inducible NOS expression. L-NAME normalized AaPO(2), brain radioactivity, pulmonary vascular resistance, reactivity to hypoxia and angiotensin II, exhaled NO, and NOS activities. These findings suggest that HPS and the associated reduced response to pulmonary vasoconstrictors seen in untreated cirrhotic rats are related to increased pulmonary NO production dependent primarily on increases in the expression and activities of inducible NOS within pulmonary intravascular macrophages.

[Free radical scavenging activity of 4-hydroxycoumarin derivatives]

The study of the relationships between the structure and the free radical scavenging activity of substituted 4-hydroxycoumarine derivatives, indicates the favorable effect of electron donating substituents.

Pulmonary thromboendarterectomy for chronic thromboembolic obstruction of the pulmonary artery in piglets

OBJECTIVE

The 2 main causes of death after thromboendarterectomy for chronic pulmonary thromboembolism are incomplete repermeabilization responsible for persistent pulmonary hypertension and acute high-permeability pulmonary edema. We wish to establish an experimental model of chronic pulmonary thromboembolism to replicate the conditions encountered during and after pulmonary thromboendarterectomy.

METHODS

Multiple-curled coils and tissue adhesive were embolized in 6 piglets to induce complete obstruction of the left pulmonary artery, documented by angiography. After 5 weeks, the main pulmonary artery was repermeabilized by thromboendarterectomy during circulatory arrest. The left lung was reperfused ex vivo with autologous blood at constant flow, and patency of the pulmonary artery was evaluated on a barium angiogram. The endarterectomy-reperfusion procedure was also done in 6 nonembolized piglets that served as the controls. The severity of lung injury induced by 60 minutes of reperfusion was assessed on the basis of measurements of the lung filtration coefficient and of lung myeloperoxidase activity.

RESULTS

Marked hypertrophy of the bronchial circulation was seen in the chronic pulmonary thromboembolism group. Thromboendarterectomy removed the organized obstructing thrombus that was incorporated into the arterial wall and restored patency of the pulmonary artery. Acute lung inflammation and high-permeability edema occurred after reperfusion, as indicated by a 1.5-fold increases in both lung filtration coefficient and lung myeloperoxidase values in the chronic pulmonary thromboembolism group; these 2 variables being correlated.

CONCLUSIONS

Our model replicated the perioperative conditions of pulmonary thromboendarterectomy, suggesting that it may prove useful for improving the repermeabilization technique and for investigating the mechanisms and prevention of reperfusion injury.

Evidence of human non-alpha-galactosyl antibodies involved in the hyperacute rejection of pig lungs and their removal by pig organ perfusion

BACKGROUND

Human natural xenoantibodies represent a major hurdle to the clinical application of pig lungs in transplantation by initiating hyperacute rejection within minutes to hours.

OBJECTIVE

The object was to compare pig organ perfusion and specific depletion of anti-alpha-galactosyl xenoantibodies for prevention of hyperacute rejection in the pig to human lung combination.

METHODS

Large White pig (20-25 kg) left lungs were removed and continuously ventilated and reperfused ex vivo either with (1) whole human blood previously perfused in situ through pig right lung (group I), liver (group II), or spleen (group III) or with (2) human plasma in vitro immunoabsorbed on columns containing alpha-galactosyl disaccharide (Gal-alpha-(1-3)Gal-beta-(CH2)3NH2; B disaccharide) (group IV). Each study group included 6 animals.

RESULTS

The in situ and in vitro preperfusions depleted anti-alpha-galactosyl xenoantibodies and all in situ perfused pig organs showed histologic signs of hyperacute rejection. After the ex vivo reperfusion, group I xenografts had a significantly (P < .001) longer functional and histologic survival than did xenografts in groups II, III, and IV. Human blood reperfusing group I xenografts had a significantly (P < 0.05) lower (1) decline of clotting factors and total circulating immunoglobulins, (2) total and membrane attack complex (C5b,6,7,8,9) complement activation, and (3) hemolysis. By Western blot analysis, the in situ lung preperfusion removed antibodies against non-alpha-galactosyl proteins of low molecular weight that were not eliminated by the alpha-galactosyl column.

CONCLUSIONS

Results demonstrate that specific depletion of anti-alpha-galactosyl antibodies alone incompletely protects pig lungs from hyperacute rejection. It is speculated that the more complete prevention of this rejection afforded by pig lung preperfusion relates to the removal of other, non-alpha-galactosyl antibodies.

Gene therapy for oxidant injury-related diseases: adenovirus-mediated transfer of superoxide dismutase and catalase cDNAs protects against hyperoxia but not against ischemia-reperfusion lung injury

Hyperoxia and ischemia-reperfusion cause profound lung cellular damage mediated, in part, by generation of oxygen radicals. We hypothesized that gene therapy can be used to overcome oxidant injury by augmenting intracellular antioxidant enzymes. Adult rats were injected intratracheally with an adenovirus (Ad) vector encoding human superoxide dismutase (CuZn-SOD) or catalase cDNA, a mixture of both Ad vectors, or a control Ad vector containing no exogenous gene. Expression of human catalase and CuZn-SOD was demonstrated 3 days later in distal lung epithelial cells and alveolar macrophages, using ELISA and immunochemistry. After exposure to 100% O2 for 62 hr, survival was greater in rats injected with the catalase and/or SOD Ad vectors than in control rats. Ischemia-reperfusion injury was evaluated in the isolated perfused lung model. Overexpression of SOD worsened ischemia-reperfusion injury. Interestingly, concomitant overexpression of catalase prevented this adverse effect, but did not protect against ischemia-reperfusion injury. We conclude that Ad-mediated transfer to lungs of both catalase and SOD cDNAs protects from pulmonary O2 toxicity. Absence of protection against ischemia-reperfusion using intratracheal Ad injections may be related to the lack of endothelial protection, despite epithelial expression of catalase and SOD.

Effect of 48 hours of nitric oxide inhalation on pulmonary vasoreactivity in rats

Nitric oxide (NO) has been shown to down regulate its own synthesis in vitro. We tested the hypothesis that NO inhalation (30 ppm under normoxic conditions) could decrease the release of endogenous endothelial NO, and thus alter pulmonary vasoreactivity. Pulmonary vasoreactivity was assessed in isolated perfused rat lungs immediately or 6 h after a 48 h NO inhalation period, and compared with a control group. NO inhalation resulted in an increase in pulmonary vasoconstrictor reactivity to angiotensine II and U-46619, a reduction in the potentiation by the eNOS inhibitor L-NAME of the angiotensine II response, a decrease in endothelium-dependent vasodilation to arginine vasopressin, whereas non-endothelium-dependent vasodilation to sodium nitroprusside remained unaltered. These alterations returned to control values in the group studied 6 h after the end of NO inhalation, and were not prevented by inhibition of the prostanoid synthesis, or by pretreatment with the endothelin receptors antagonist Bosentan. These results indicate that NO inhalation over 2 d induces a reversible alteration of pulmonary vasoreactivity in relationship with a decrease in endogenous NO release. Inhibition of eNOS could be involved.

Gene therapy in lung transplantation: feasibility of ex vivo adenovirus-mediated gene transfer to the graft

Lung transplantation is associated with complications such as reperfusion injury and graft rejection. Gene therapy targeted to the graft offers a promising approach to the prevention of these complications. Because adenovirus vectors can transfer genes in vivo to the lung vasculature, we evaluated the feasibility of adenovirus-mediated gene transfer to the lung graft in a porcine model of left lung allotransplantation. Following removal of the donor lung, an adenovirus vector encoding the beta-galactosidase (beta-Gal) gene was injected ex vivo into the lumen of the upper lobe pulmonary artery of the graft. After 2 hr of incubation at 10 degrees C, the lung graft was implanted into the recipient animal. Three days later, the animals were sacrificed and the lung graft was evaluated for beta-Gal activity. No beta-Gal activity was detected in the left lower lobe used as a control. In contrast, beta-Gal activity was detected in endothelial cells of the left upper lobe pulmonary circulation, and was also observed in airway and alveoli epithelial cells. However, less than 1% of cells of the graft expressed beta-Gal. In vitro experiments showed that this may be explained in part by the low temperature and the short duration of adenovirus incubation within the graft, and by the low susceptibility of porcine cells to human adenovirus. Furthermore, expression of the exogenous gene occurred in several organs of recipient animals. Thus, adenovirus-mediated gene transfer to the lung graft is feasible ex vivo, but several parameters limit gene transfer efficiency and need to be improved before clinical application is attempted.

Prevention of ischemia-reperfusion lung injury by inhaled nitric oxide in neonatal piglets

Lung ischemia-reperfusion results in a decrease in the release of nitric oxide (NO) by the pulmonary endothelium. NO may have lung-protective effects by decreasing neutrophil accumulation in the lung. We tested whether NO inhalation would attenuate reperfusion-induced endothelial dysfunction and increases in microvascular permeability and total pulmonary vascular resistance (RT) by preventing neutrophil lung accumulation. After baseline determinations of RT, coefficient of filtration (Kfc), and circulating neutrophil counts, isolated neonatal piglet lungs were subjected to a 1-h period of ischemia followed by a 1-h period of blood reperfusion and reventilation with or without addition of NO (10 ppm). NO prevented reperfusion-induced increases in RT and Kfc, as well as the decrease in circulating neutrophils. After reperfusion, increases in Kfc were correlated with decreases in circulating neutrophils. NO prevented reperfusion-induced decrease in endothelium-dependent relaxation in precontracted pulmonary arterial rings. This demonstrates that inhaled NO prevents microvascular injury, endothelial dysfunction, and pulmonary neutrophil accumulation in a neonatal piglet model of lung ischemia-reperfusion.

Effects of calcium concentration, lactobionate content, and sodium/ potassium ratio of preservation solutions on resting left ventricular pressure and postreperfusion function of rabbit heterotopic heart transplants

BACKGROUND

We tested the hypothesis that the University of Wisconsin solution has a ionic composition (i.e., intracellular, calcium-free, lactobionate-enriched) that may be beneficial for cold heart graft preservation independently from any additives.

METHODS

St. Thomas' Hospital and University of Wisconsin solutions were compared with the following: (1) C solution, a simplified University of Wisconsin-like solution (i.e., intracellular, calcium-free, lactobionate-enriched); (2) A solution, an St. Thomas' Hospital-like solution (extracellular, calcium [Ca2+] = 1.2 mmol/L) in which chloride was replaced by lactobionate; (3) B solution, an intracellular, lactobionate-enriched, calcium-containing solution ([Ca2+] = 1.2 mmol/L). Rabbit hearts were transplanted heterotopically in the abdomen of recipient animals either immediately or after 6 hours of storage. Hemodynamic parameters were recorded 60 minutes after unclamping.

RESULTS

After a 6-hour storage, University of Wisconsin and C solutions provided better preservation than B and St. Thomas' Hospital solutions: diastolic pressures were lower; developed pressure and rate of pressure rise were higher. C solution was superior to University of Wisconsin solution only for rate of pressure rise. A solution was intermediary. A significant alteration of resting pressure and hemodynamic parameters was generally observed during the 6-hour storage. Nonsignificant changes of developed pressure and rate of pressure rise were only observed in C and B solutions: This is explained by systolic alteration after immediate reimplantation for the B group and good preservation for the C group. Resting pressure was unchanged over a 6-hour storage only for the C group, but this measure was not determined for University of Wisconsin. A correlation exists for various left ventricular volumes between resting pressure and postreperfusion hemodynamic data. Replacement of chloride by lactobionate (A versus St. Thomas' Hospital) may have improved resting and diastolic pressures by other mechanisms than limitation of net water gain during storage.

Amelioration of reperfusion injury by pentoxifylline after lung transplantation. The Université Paris-Sud Lung Transplant Group

BACKGROUND

Pentoxifylline attenuates neutrophil-mediated lung injury in several models of acute lung inflammation.

METHODS

Because pulmonary neutrophil sequestration is the main determinant of lung reperfusion injury, we sought to determine whether pentoxifylline prevented reperfusion injury in isolated perfused rat lung (4-hour cold ischemia, 1-hour reperfusion; pentoxifylline intravenously 40 mg) and in pigs after left lung allotransplantation (24-hour cold ischemia, 4-hour reperfusion; pentoxifylline 1.5 mg/kg/hr intravenously). In the pigs, inflatable cuffs placed around each pulmonary artery enabled us to evaluate each lung separately.

RESULTS

In rat lungs, the coefficient of lung permeability increased by 75% +/- 10% in controls and by 3% +/- 2% (p < 0.01) in pentoxifylline-treated lungs. In the pigs, with blood flow to the transplanted lung alone and ventilation with an inspired oxygen fraction of 1, the arterial oxygen tension was greater in the pentoxifylline group than in the control group (423 +/- 49 versus 265 +/- 43 mm Hg, p < 0.05), whereas the total pulmonary vascular resistance was lower (15 +/- 1 versus 30 +/- 9 mm Hg/L/min, p < 0.02). After reperfusion, the decrease in circulating leukocyte count fell by 35% +/- 3% in the control group and remained unchanged in the pentoxifylline group, and the leukocytes count per microscopic field in the transplanted lung was lower in the pentoxifylline group than in the control group (15 +/- 2 versus 140 +/- 50, p < 0.02).

CONCLUSIONS

These data suggest that pentoxifylline prevented reperfusion injury by decreasing neutrophil lung sequestration.

Evaluation of a new preservation solution: Celsior in the isolated rat lung. Paris-Sud University Lung Transplatation Group

BACKGROUND

We compared Celsior solution, a new and original extracellular preservation solution, with blood-based Wallwork's solution.

METHODS

In two groups of isolated rat lungs submitted to 4 hours of cold ischemia, pulmonary arterial and venous resistances, coefficient of filtration, and wet-to-dry lung weight ratio were determined at baseline and after 90 minutes of reperfusion.

RESULTS

After ischemia-reperfusion, percentage of increases above the respective baseline coefficient of filtration values were 93% +/- 7% in the Wallwork group and 7% +/- 3% in the Celsior group (p < 0.001 versus Wallwork's solution).

CONCLUSIONS

These results show that Celsior consistently prevented the ischemia-reperfusion-induced increase in pulmonary microvascular permeability as compared with Wallwork's solution.

Lung preservation with Euro-Collins, University of Wisconsin, Wallwork, and low-potassium-dextran solution. Université++ Paris-Sud Lung Transplant Group

Using isolated rat lungs, we compared prevention of ischemia-reperfusion injury provided by flushing the lungs with modified Euro-Collins solution (EC), University of Wisconsin solution (UW), low-potassium-dextran solution (LPD), or Wallwork solution (WA). After 4 hours' and 6 hours' cold ischemia, reperfusion injury was assessed on the basis of changes in filtration coefficients (Kfc) and pressure-flow curves, characterized by the slope of the curves (incremental resistance) and the extrapolation of this slope to zero flow (pulmonary pressure intercept [Ppi]). After 4 hours, Kfc and Ppi were higher with EC than with UW, LPD, and WA, and the incremental resistance was higher with EC and UW. After 6 hours, Kfc and incremental resistance Ppi were higher with LPD than with WA. Because ischemia-reperfusion injury is associated with decreased endothelial synthesis of prostacyclin and nitric oxide, we tested whether the addition of prostacyclin or the nitric oxide precursor L-arginine to WA would improve preservation. The Kfc and Ppi were lower with both treatments. In conclusion, ischemia-reperfusion injury was best prevented by using WA. The favorable effect of prostacyclin or L-arginine emphasizes the role played by endothelial dysfunction in ischemia-reperfusion injury.

Reduction of ischemia-reperfusion injury by pentoxifylline in the isolated rat lung. Paris-Sud University Lung Transplantation Group

Inhibition of pulmonary neutrophil sequestration attenuates ischemia-reperfusion (IR) lung injury. Pentoxifylline (PTX) reduced pulmonary sequestration of neutrophils and neutrophil-dependent lung injury in several experimental settings but has never been tested in IR models. We hypothesized that PTX may have a beneficial effect on IR lung injury as measured by the coefficient of filtration (Kfc) and may reduce IR-associated sequestration of neutrophils as assessed by lung myeloperoxidase (MPO) activity and by blood neutrophil count decrease during reperfusion. Three groups of isolated blood perfused rat lungs were studied: a time control group (n = 6) was perfused for 3 h, and two groups (n = 10) subjected to 1 h ischemia were treated with PTX or saline before a 2 h reperfusion. The increase in Kfc induced by IR was reduced fivefold by PTX compared with saline (+27 +/- 8% versus +112 +/- 12%, respectively; p < 0.001), and was similar to time controls (+9 +/- 9%). After IR, MPO and blood neutrophil count decrease were lower with PTX than with saline. Changes in Kfc were correlated to the percentage decrease in blood neutrophils during reperfusion. We conclude that PTX reduced rat lung IR microvascular injury. This effect may be mainly caused by decrease in lung sequestration of neutrophils during reperfusion.