The lung as a metabolic organ

A critical assessment of the cellular defences of the avian respiratory system: are birds in general and poultry in particular relatively more susceptible to pulmonary infections/afflictions?

In commercial poultry farming, respiratory diseases cause high morbidities and mortalities, begetting colossal economic losses. Without empirical evidence, early observations led to the supposition that birds in general, and poultry in particular, have weak innate and adaptive pulmonary defences and are therefore highly susceptible to injury by pathogens. Recent findings have, however, shown that birds possess notably efficient pulmonary defences that include: (i) a structurally complex three-tiered airway arrangement with aerodynamically intricate air-flow dynamics that provide efficient filtration of inhaled air; (ii) a specialised airway mucosal lining that comprises air-filtering (ciliated) cells and various resident phagocytic cells such as surface and tissue macrophages, dendritic cells and lymphocytes; (iii) an exceptionally efficient mucociliary escalator system that efficiently removes trapped foreign agents; (iv) phagocytotic atrial and infundibular epithelial cells; (v) phagocytically competent surface macrophages that destroy pathogens and injurious particulates; (vi) pulmonary intravascular macrophages that protect the lung from the vascular side; and (vii) proficiently phagocytic pulmonary extravasated erythrocytes. Additionally, the avian respiratory system rapidly translocates phagocytic cells onto the respiratory surface, ostensibly from the subepithelial space and the circulatory system: the mobilised cells complement the surface macrophages in destroying foreign agents. Further studies are needed to determine whether the posited weak defence of the avian respiratory system is a global avian feature or is exclusive to poultry. This review argues that any inadequacies of pulmonary defences in poultry may have derived from exacting genetic manipulation(s) for traits such as rapid weight gain from efficient conversion of food into meat and eggs and the harsh environmental conditions and severe husbandry operations in modern poultry farming. To reduce pulmonary diseases and their severity, greater effort must be directed at establishment of optimal poultry housing conditions and use of more humane husbandry practices.

A shift from glycolytic and fatty acid derivatives toward one-carbon metabolites in the developing lung during transitions of the early postnatal period

During postnatal lung development, metabolic changes that coincide with stages of alveolar formation are poorly understood. Responding to developmental and environmental factors, metabolic changes can be rapidly and adaptively altered. The objective of the present study was to determine biological and technical determinants of metabolic changes during postnatal lung development. Over 118 metabolic features were identified by liquid chromatography with tandem mass spectrometry (LC-MS/MS, Sciex QTRAP 5500 Triple Quadrupole). Biological determinants of metabolic changes were the transition from the postnatal saccular to alveolar stages and exposure to 85% hyperoxia, an environmental insult. Technical determinants of metabolic identification were brevity and temperature of harvesting, both of which improved metabolic preservation within samples. Multivariate statistical analyses revealed the transition between stages of lung development as the period of major metabolic alteration. Of three distinctive groups that clustered by age, the saccular stage was identified by its enrichment of both glycolytic and fatty acid derivatives. The critical transition between stages of development were denoted by changes in amino acid derivatives. Of the amino acid derivatives that significantly changed, a majority were linked to metabolites of the one-carbon metabolic pathway. The enrichment of one-carbon metabolites was independent of age and environmental insult. Temperature was also found to significantly influence the metabolic levels within the postmortem sampled lung, which underscored the importance of methodology. Collectively, these data support not only distinctive stages of metabolic change but also highlight amino acid metabolism, in particular one-carbon metabolites as metabolic signatures of the early postnatal lung.

Lung, Pleura, and Mediastinum

The lung is constantly exposed to a large volume of inhaled air that may contain toxicant xenobiotics. With the possibility of exposure to a variety of respiratory toxicants from airborne pollutants in our environment during the course of daily activities, in occupational settings, the use of aerosol sprays for household products, and the development of inhalant bronchial therapies, pulmonary toxicology has become an important subspecialty of toxicology. The lung is susceptible to injury following hematogenous exposure to toxicants. Susceptibility to injury and the type of response following exposure to air- or blood-borne toxicants is largely dependent on the physiochemical characteristics and concentration of the toxicant, duration of exposure, site/tissue specific sensitivity, and the integrity of the defense mechanisms of the lung. In this chapter, nonneoplastic and neoplastic spontaneous lesions and those that develop in the lungs of rats following exposure to toxicants by various routes, but primarily by inhalation, are discussed in detail which provides insight into our understanding of how human lungs respond to toxic chemicals. In addition, the gross and microscopic anatomy of the rat lung is also discussed some detail. Although inhalation is the primary route of exposure in experimental studies, in the past, many studies used intratracheal instillation or direct injection of known carcinogens into the lung. These experiments often resulted in the development of squamous cell carcinomas even though they are very rare as a naturally occurring neoplasm. Instillation of chemicals or particles into the trachea or pleura or direct injection into the lung results in lesions or responses that may not be as relevant to understanding the mechanism of pulmonary carcinogenesis as inhalation of materials under more normal conditions. There remain, however, many areas where our understanding of the response of the lung to toxic chemicals is incomplete.

Lung Transplant Center Volume Ameliorates Adverse Influence of Prolonged Ischemic Time on Mortality

The influence of prolonged ischemic time on outcomes after lung transplant is controversial, but no research has investigated ischemic time in the context of center volume. We used data from the United Network for Organ Sharing to estimate the influence of ischemic time on patient survival conditional on center volume in the post-lung allocation score era (2005-2015). The analytic sample included 14 877 adult lung transplant recipients, of whom 12 447 were included in multivariable survival analysis. Patient survival was improved in high-volume centers compared with low-volume centers (log-rank test p = 0.001), although mean ischemic times were longer at high-volume centers (5.16 ± 1.70 h vs. 4.83 ± 1.63 h, p < 0.001). Multivariable Cox proportional hazards regression stratified by transplant center found an adverse influence of longer ischemic time at low-volume centers but not at high-volume centers. At centers performing 50 transplants in the period 2005-2015, for example, 8 versus 6 h of ischemia were associated with an 18.9% (95% confidence interval 6.5-32.7%; p < 0.001) greater mortality hazard, whereas at centers performing 350 transplants in this period, no differences in survival by ischemic time were predicted. Despite longer mean ischemic time at high-volume transplant centers, these centers had favorable patient outcomes and no adverse survival implications of prolonged ischemia.

Influence of graft ischemic time on survival in children with cystic fibrosis after lung transplantation

BACKGROUND

The influence of graft ischemic time on survival after lung transplantation (LTx) in children with cystic fibrosis (CF) is not well studied.

METHODS

The United Network for Organ Sharing (UNOS) database was queried from May 2005 to September 2013 to examine the impact of ischemic time of <4, 4-6, and >6 hr in pediatric LTx recipients with CF.

RESULTS

One hundred and ninety-nine patients with CF under 18 years of age that were first-time LTx recipients from cadaveric donors were included in the analysis. Compared to 4-6 hr, univariate analysis showed a significant increase in mortality hazard with an ischemic time of <4 hr (HR = 2.407; 95%CI: 1.292, 4.485; P = 0.006) but not >6 hr (HR = 1.350; 95%CI: 0.796, 2.290; P = 0.266). A Kaplan-Meier plot demonstrated the highest survival with 4-6 hr (Log-rank test P = 0.018) of ischemic time. Multivariate Cox model confirmed a significantly higher mortality risk with <4 hr (HR = 2.388; 95%CI: 1.169, 4.764; P = 0.014) and not >6 hr (HR = 1.407; 95%CI: 0.760, 2.605; P = 0.278) in relation to 4-6 hr. Sub-analysis examining ischemic time and the hazard of bronchiolitis obliterans syndrome with death as a competing risk found no significant differences in the hazard of this outcome across the three ischemic time categories.

CONCLUSIONS

Ischemic time of 4-6 hr was associated with the highest long-term survival in first-time pediatric LTx recipients with CF, with ischemic time <4 hr related to diminished survival. Pediatr Pulmonol. 2016; 51:908-913. © 2016 Wiley Periodicals, Inc.

Impact of Donor Arterial Partial Pressure of Oxygen on Outcomes After Lung Transplantation in Adult Cystic Fibrosis Recipients

INTRODUCTION

Donor PaO2 levels are used for assessing organs for lung transplantation (LTx), but survival implications of PaO2 levels in adult cystic fibrosis (CF) patients receiving LTx are unclear.

METHODS

UNOS registry data spanning 2005-2013 were used to test for associations of donor PaO2 with patient survival and bronchiolitis obliterans syndrome (BOS) in adult (age ≥ 18 years) first-time LTx recipients diagnosed with CF.

RESULTS

The analysis included 1587 patients, of whom 1420 had complete data for multivariable Cox models. No statistically significant differences among donor PaO2 categories of ≤200, 201-300, 301-400, or >400 mmHg were found in univariate survival analysis (log-rank test p = 0.290). BOS onset did not significantly differ across donor PaO2 categories (Chi-square p = 0.480). Multivariable Cox models of patient survival supported the lack of difference across donor PaO2 categories. Interaction analysis found a modest difference in survival between the two top categories of donor PaO2 when examining patients with body mass index (BMI) in the lowest decile (≤16.5 kg/m(2)).

CONCLUSIONS

Donor PaO2 was not associated with survival or BOS onset in adult CF patients undergoing LTx. Notwithstanding statistically significant interactions between donor PaO2 and BMI, there was no evidence of post-LTx survival risk associated with donor PaO2 below conventional thresholds in any subgroup of adults with CF.

Pharmacokinetics of idarubicin in the isolated perfused rat lung: effect of cinchonine and rutin

This study was designed to examine the effect of rutin and cinchonine on the uptake and metabolism of idarubicin (IDA) in the isolated perfused rat lung. IDA (2 mg) was infused for 2 min into the truncus pulmonalis in the presence of P-glycoprotein (P-gp) modulators cinchonine (1 microM) or rutin (6 microM). (Rutin is also known as an aldo-keto reductase inhibitor.) Venous outflow samples were collected up to 60 min, and the concentration of IDA and its primary metabolite idarubicinol (IDOL) were measured by high-performance liquid chromatography) with fluorescence detection. Thereafter, the tissue concentrations of IDA and IDOL were determined in the lung (n = 5 in each group). The estimated mean transit times for IDA in the treatment groups (MTT(cinchonine) = 21.8+/-3.5 min; MTT(rutin) = 20.1+/-5.0 min) were significantly higher than in the control group (11.6+/-2.1 min). Both cinchonine and rutin significantly enhanced the lung tissue concentrations of IDA (1.7- and 2.4-fold), as well as of IDOL (2.1- and 2.4-fold). Cinchonine and rutin also increased the outflow recovery of IDOL 2.6- and 2.7-fold, respectively. The results suggest that uptake kinetics of IDA into the rat lung is partly controlled by a P-gp efflux pump and its inhibition enhances the accumulation of IDA.

Pharmacokinetics and toxicity of idarubicin in the rat

This study was designed to examine the pharmacokinetics and toxicity of idarubicin (IDA) in rats. In two groups of rats IDA was infused either into the V. iugularis interna or into the A. carotis communis, respectively. The venous plasma concentration of IDA and its primary metabolite idarubicinol (IDOL) were measured up to 48 hours by high-performance liquid chromatography (HPLC) with fluorescence detection. The weights of the rats and the levels of haemoglobin, leukocytes, and thrombocytes were recorded. The plasma concentration-time data were analysed, assuming a biexponential disposition curve, both by the traditional (two-stage) method and by population pharmacokinetic modelling. The basic pharmacokinetic parameters clearance (CL = 27.0 ml min(-1)), mean disposition residence time (MDRT = 519.2 min), and volume of distribution at steady state (Vss = 12.51) were estimated for IDA. The mean residence time (MRT) of the generated IDOL was 2982.5 min. No significant differences between pre- and postpulmonal injection were found in the pharmacokinetics and pharmacodynamics of IDA. The mean survival time of 13.3 days is attributed to a severe myelosuppression.

Serial changes in N-isopropyl-p[125I]-iodoamphetamine in mouse lung observed with a confocal laser scanning microscope

Serial changes in N-isopropyl-p[125I]-iodoamphetamine (125I-IMP) in mouse lungs were observed with a confocal laser scanning microscope. Male mice were intravenously injected with 125I-IMP and subjected to autoradiographic procedures 20 minutes, and 3 and 24 hours after injection. Differential interference contrast (DIC) images and confocal images were obtained with a confocal laser scanning microscope, and superimposed images were evaluated. Large numbers of silver grains were observed in the interstitium, bronchioles, and alveolar sacs 20 minutes after the injection, and lamellar distribution of the grains was observed on the ciliary surface. The numbers of silver grains in the interstitium and bronchioles had decreased 3 hours after the injection of 125I-IMP, but the numbers of silver grains in the alveolar spaces had not. Although small numbers of silver grains remained in both the bronchioles and alveolar sacs 24 hours after the injection, most of them had washed out. Confocal laser scanning microscopy is considered to be a useful procedure for studying the distribution of radioisotopes by microautoradiography, because it allows clear autoradiographs to be obtained in which tissues and silver grains are perfectly matched and all silver grains are in focus.

Clinical studies of alveolar-capillary permeability using technetium-99m DTPA aerosol

Soluble radioaerosols such as technetium-99m diethylene triamine pentacetate (DTPA) permit simple quantitative studies of alveolar-capillary permeability to be performed, since the submicronic aerosols are deposited mainly at the lung periphery and are cleared across the alveolar-capillary membrane. Regional alterations in permeability can also be noted using this radionuclide technique. We have measured the pulmonary epithelial permeability in normal subjects and the alteration in smokers, in glue-sniffers, in patients with inhalation burns, in chronic obstructive pulmonary disease (COPD) and in patients with lung metastases from thyroid cancer treated with radioiodine 131I. In the normal volunteers, the time taken for 50% of inhaled 99mTcDTPA to be cleared form the lungs (T1/2) was 66 minutes +/- 1sd of 12 mins. The smokers had a mean T1/2 of 20 mins +/- 1sd 4 min. In the hard-core glue-sniffing group, the majority were smokers who had stopped smoking and glue-sniffing for periods varying from 1 day to 42 days, and it was possible to note the changes in clearance times against period of abstinence. In the patients with inhalations burns, there was change in lung clearance arising from pulmonary epithelial damage; these patients showed increased rate of clearance (short T1/2) with mean T1/2 of 36 min +/- 1sd of 11 mins, while the retention images revealed regional lung damage in moderately severe inhalation burns. Twenty-four patients with COPD had inhalation scans done with Tc-99m tin colloid radioaerosol, and these images were compared with the perfusion lung scans done with 99mTc macroaggregated albumin (MAA); in general the perfusion images matched the defects noted in the inhalation scans. The 99mTc DTPA clearance rate in these patients was normal i.e. T 1/2 = 78 +/- 14 mins. In the thyroid cancer patients with lung metastases, who had high doses of radioiodine treatment, the T 1/2 values were normal or prolonged slightly, mean T1/2 = 76 min +/- 23.

Intra-arterial infusion of N-isopropyl-p[123I]iodoamphetamine for assessing effective blood supply to pulmonary and hepatic neoplasms

The biodistribution and pharmacokinetics of intra-arterially administered N-isopropyl-p[123I] iodoamphetamine (123I-IMP) were prospectively evaluated in 38 patients with histologically proven pulmonary or hepatic tumors. Intra-arterially infused 123I-IMP was distributed initially in peripheral tissues in which the blood supply was maintained. Its concentration in malignant neoplasms was demonstrated to be higher than in normal tissues. In pulmonary cancer, the tumor uptake of the administered dose without a tissue attenuation correction (% uptake) of 123I-IMP at 1-2 min after injection was 14.7 +/- 5.7% (s.d.). The tumor to normal tissue ratio was 2.1 +/- 0.7 in hepatocellular carcinoma and 1.4 +/- 0.7 in metastatic tumors. The biodistribution of 123I-IMP was also compared to that of 99mTc-macroaggregated albumin (99mTc-MAA) in 9 cases of hepatic cancer. The distribution of 123I-IMP resembled that of 99mTc-MAA in 5 cases and was different in 4 cases. 123I-IMP was more concentrated in the tumor than 99mTc-MAA. Intra-arterial infusion scintigraphy with 123I-IMP seems to provide information on effective blood supply to neoplasms which are targeted in interventional radiology.

Favorable biodistribution of 99mTc-ECD for brain SPECT comparing with 123I-IMP using alternative body scan

In order to evaluate the lung and brain uptake of 99mTc ethyl cysteinate dimer (99mTc-ECD) and N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP), alternative body scans were carried out in 15 cases of cerebrovascular disease. The biodistribution of 99mTc-ECD was 5.5 +/- 0.7%, 3.8 +/- 0.7% in the brain; 13.1 +/- 3.7%, 2.2 +/- 1.2%, in the lung at 15 min and at 4 hours, respectively, whereas that of 123I-IMP was 3.9 +/- 1.4%, 5.0 +/- 1.0% in the brain; 32.2 +/- 7.6%, 12.7 +/- 3.3%, in the lung at 15 min and at 4 hours, respectively. 99mTc-ECD accumulated in comparatively high amounts in the brain but remained low in the lung in the early image compared to 123I-IMP. However there was a high inverse correlation between brain and lung uptake of 123I-IMP (r = -0.82), but not of 99mTc-ECD (r = -0.18). We concluded that 99mTc-ECD had a better biodistribution in terms of low lung accumulation than 123I-IMP in brain SPECT.