Modulation of hyperoxia-induced TNF-alpha expression in the newborn rat lung by thalidomide and dexamethasone

Effects of postnatal corticosteroids on lung development in newborn animals. A systematic review

BACKGROUND

Postnatal systemic corticosteroids reduce the risk of bronchopulmonary dysplasia but the effect depends on timing, dosing, and type of corticosteroids. Animal studies may provide valuable information on these variable effects. This systematic review summarizes the effects of postnatal systemic corticosteroids on lung development in newborn animals.

METHODS

A systematic search was performed in PubMed and Embase in December 2022. The protocol was published on PROSPERO (CRD42021177701).

RESULTS

Of the 202 eligible studies, 51 were included. Only newborn rodent studies met the inclusion criteria. Most studies used dexamethasone (98%). There was huge heterogeneity in study outcome measures and corticosteroid treatment regimens. Reporting of study quality indicators was mediocre and risk of bias was unclear due to poor reporting of study methodology. Meta-analysis showed that postnatal corticosteroids caused a decrease in body weight as well as persistent alveolar simplification. Subgroup analyses revealed that healthy animals were most affected.

CONCLUSION

In newborn rodents, postnatal systemic corticosteroids have a persistent negative effect on body weight and lung development. There was huge heterogeneity in experimental models, mediocre study quality, unclear risk of bias, and very small subgroups for meta-analysis which limited firm conclusions.

IMPACT

Postnatal corticosteroids reduce the risk of bronchopulmonary dysplasia but the effect depends on timing, dosing, and type of corticosteroids while the underlying mechanism of this variable effect is unknown. This is the first systematic review and meta-analysis of preclinical newborn animal studies reviewing the effect of postnatal systemic corticosteroids on lung development. In newborn rodent models, postnatal corticosteroids have a persistent negative effect on body weight and lung alveolarization, especially in healthy animals.

Iloprost attenuates hyperoxia-mediated impairment of lung development in newborn mice

Cyclooxygenase-2 (COX-2/PTGS2) mediates hyperoxia-induced impairment of lung development in newborn animals and is increased in the lungs of human infants with bronchopulmonary dysplasia (BPD). COX-2 catalyzes the production of cytoprotective prostaglandins, such as prostacyclin (PGI2), as well as proinflammatory mediators, such as thromboxane A2. Our objective was to determine whether iloprost, a synthetic analog of PGI2, would attenuate hyperoxia effects in the newborn mouse lung. To test this hypothesis, newborn C57BL/6 mice along with their dams were exposed to normoxia (21% O2) or hyperoxia (85% O2) from 4 to 14 days of age in combination with daily intraperitoneal injections of either iloprost 200 µg·kg-1·day-1, nimesulide (selective COX-2 antagonist) 100 mg·kg-1·day-1, or vehicle. Alveolar development was estimated by radial alveolar counts and mean linear intercepts. Lung function was determined on a flexiVent, and multiple cytokines and myeloperoxidase (MPO) were quantitated in lung homogenates. Lung vascular and microvascular morphometry was performed, and right ventricle/left ventricle ratios were determined. We determined that iloprost (but not nimesulide) administration attenuated hyperoxia-induced inhibition of alveolar development and microvascular density in newborn mice. Iloprost and nimesulide both attenuated hyperoxia-induced, increased lung resistance but did not improve lung compliance that was reduced by hyperoxia. Iloprost and nimesulide reduced hyperoxia-induced increases in MPO and some cytokines (IL-1β and TNF-α) but not others (IL-6 and KC/Gro). There were no changes in pulmonary arterial wall thickness or right ventricle/left ventricle ratios. We conclude that iloprost improves lung development and reduces lung inflammation in a newborn mouse model of BPD.

Postnatal inflammation in the pathogenesis of bronchopulmonary dysplasia

Exposure to hyperoxia, invasive mechanical ventilation, and systemic/local sepsis are important antecedents of postnatal inflammation in the pathogenesis of bronchopulmonary dysplasia (BPD). This review will summarize information obtained from animal (baboon, lamb/sheep, rat and mouse) models that pertain to the specific inflammatory agents and signaling molecules that predispose a premature infant to BPD.

Acute lung injury in preterm fetuses and neonates: mechanisms and molecular pathways

Acute lung injury (ALI) results in high morbidity and mortality among preterm neonates and efforts have therefore been devoted to both antenatal and postnatal prevention of the disease. ALI is the result of an inflammatory response which is triggered by a variety of different mechanisms. It mostly affects the fetal lung and, in particular, causes damage to the integrity of the lung's alveolar-capillary unit while weakening its cellular linings. Chemotactic activity and inflammatory products, such as proinflammatory cytokines TNF-α, IL-1, IL-6, IL-11, VEGF,TGF-α and TGF-β, provoke serious damage to the capillary endothelium and the alveolar epithelium, resulting in hyaline membrane formation and leakage of protein-rich edema fluid into the alveoli. Chorioamnionitis plays a major part in triggering fetal lung inflammation, while mechanical ventilation, the application of which is frequently necessary in preterm neonates, also causes ALI by inducing proinflammatory cytokines. Many different ventilation-strategies have been developed in order to reduce potential lung injury. Furthermore, tissue injury may occur as a result of injurious oxygen by-products (Reactive Oxygen Species, ROS), secondary to hyperoxia. Knowledge of the inflammatory pathways that connect intra-amniotic inflammation and ALI can lead to the formulation of novel interventional procedures. Future research should concentrate on the pathophysiology of ALI in preterm neonates and οn possible pharmaceutical interventions targeting prevention and/or resolution of ALI.

Adult Rat Bone Marrow-Derived Stem Cells Promote Late Fetal Type II Cell Differentiation in a Co-Culture Model

Bronchopulmonary dysplasia develops in preterm infants due to a combination of lung immaturity and lung injury. Cultured pluripotent bone marrow stem cells (BMSC) are known to reduce injury and induce repair in adult and in immature lungs, possibly through paracrine secretion of soluble factors. The paracrine relationship between BMSC and primary fetal lung epithelial type II cells is unknown. We determined the effects of BMSC on type II cell and fibroblast behavior using an in vitro co-culture model. Rat BMSC were isolated and co-cultured with primary fetal E21 rat type II cells or lung fibroblasts in a Transwell^® system without direct cell contact. Effects of BMSC conditioned media (CM) on type II cell and fibroblast proliferation and on type II cell surfactant phospholipid (DSPC) synthesis and mRNA expression of surfactant proteins B and C (sftpb and sftpc) were studied. We also determined the effect of fibroblast and type II cell CM on BMSC proliferation and surface marker expression. Co-culture with BMSC significantly decreased type II cell and fibroblast proliferation to 72.5% and 83.7% of controls, respectively. Type II cell DSPC synthesis was significantly increased by 21% and sftpb and sftpc mRNA expressions were significantly induced (2.1 fold and 2.4 fold, respectively). BMSC proliferation was significantly reduced during the co-culture. Flow cytometry confirmed that BMSC retained the expression of undifferentiated stem cell markers despite their exposure to fetal lung cell CM. We conclude that BMSC induce fetal type II cell differentiation through paracrine release of soluble factors. These studies provide clues for how BMSC may act in promoting alveolar repair following injury.

Long-term (postnatal day 70) outcome and safety of intratracheal transplantation of human umbilical cord blood-derived mesenchymal stem cells in neonatal hyperoxic lung injury

PURPOSE

This study was performed to evaluate the long-term effects and safety of intratracheal (IT) transplantation of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in neonatal hyperoxic lung injury at postnatal day (P)70 in a rat model.

MATERIALS AND METHODS

Newborn Sprague Dawley rat pups were subjected to 14 days of hyperoxia (90% oxygen) within 10 hours after birth and allowed to recover at room air until sacrificed at P70. In the transplantation groups, hUCB-MSCs (5×10⁵) were administered intratracheally at P5. At P70, various organs including the heart, lung, liver, and spleen were histologically examined, and the harvested lungs were assessed for morphometric analyses of alveolarization. ED-1, von Willebrand factor, and human-specific nuclear mitotic apparatus protein (NuMA) staining in the lungs and the hematologic profile of blood were evaluated.

RESULTS

Impaired alveolar and vascular growth, which evidenced by an increased mean linear intercept and decreased amount of von Willebrand factor, respectively, and the hyperoxia-induced inflammatory responses, as evidenced by inflammatory foci and ED-1 positive alveolar macrophages, were attenuated in the P70 rat lungs by IT transplantation of hUCB-MSCs. Although rare, donor cells with human specific NuMA staining were persistently present in the P70 rat lungs. There were no gross or microscopic abnormal findings in the heart, liver, or spleen, related to the MSCs transplantation.

CONCLUSION

The protective and beneficial effects of IT transplantation of hUCB-MSCs in neonatal hyperoxic lung injuries were sustained for a prolonged recovery period without any long-term adverse effects up to P70.

Calcitonin gene-related peptide ameliorates hyperoxia-induced lung injury in neonatal rats

Therapies with prolonged exposure to high-concentration oxygen are common in the treatment of critical pulmonary and cardiac conditions in newborns. However, prolonged exposure to hyperoxia could result in lung damages and developmental disorders manifested as acute lung injury and bronchopulmonary dysplasia, respectively. Calcitonin gene-related peptide (CGRP) has been shown to have a broad regulatory effect on the respiratory system. In this study, we explored the protective effects of CGRP on the hyperoxia-induced lung damage. Newborn Sprague-Dawley rats were randomly divided into three groups: normoxia, hyperoxia, and hyperoxia with CGRP. Hyperoxia groups were exposed to 95% oxygen for 14 days and treated once every other day with saline or CGRP. Hyperoxia exposure reduced the survival rate to 73%, when compared with the 93% survival rate observed in the normoxia group. The survival rate was improved to 84% with CGRP treatment. Treatment with CGRP under hyperoxia significantly alleviated the hyperoxia-induced lung histomorphological changes and the increases in leukocyte counts and total protein levels in bronchoalveolar lavage fluid that reflect the pulmonary microvasular damages. CGRP treatment also restored the decreased activity of superoxide dismutase, while it decreased the increased level of malondialdehyde in the lung tissues. Importantly, CGRP treatment significantly decreased the magnitude of the hyperoxia-mediated increase in the expression levels of tumor necrosis factor-α mRNA and transforming growth factor-β 1 protein. In conclusion, the hyperoxia-induced acute lung injury is associated with both oxidative stress and inflammatory responses, and CGRP may ameliorate the hyperoxia-induced lung injury by down-regulating these processes.

Hyperoxia-derived lung damage in preterm infants

Hyperoxia-induced lung injury is characterized by an influx of inflammatory cells, increased pulmonary permeability, endothelial and epithelial cell death. This review highlights the mechanistic aspects of inflammation, vascular leak and cell death. The focus will be on agents that contribute to hyperoxia-induced lung injury in developmentally appropriate animal models, and those that have been detected in human premature neonates.

Thalidomide treatment modulates macrophage pro-inflammatory function and cytokine levels in Klebsiella pneumoniae B5055 induced pneumonia in BALB/c mice

Lung innate immune response plays an important role in the clearance of pathogens from lungs, however, profound activation of innate immune cells (alveolar macrophages or neutrophils) can lead to development of acute lung inflammation or injury by producing various pro-inflammatory molecules (IL-1, TNF-alpha and H2O2 etc.). Present study is designed to investigate the immunomodulatory action of thalidomide in Klebsiella pneumoniae B5055 induced acute lung infection in BALB/c mice. Acute lung inflammation was induced by intranasal instillation of K. pneumoniae B5055 into mice without any anaesthesia and treated with thalidomide (30 mg/kg/day/po) or normal saline orally using a treatment schedule shown to modulate pro-inflammatory innate immune response. Thalidomide treatment modulated pro-inflammatory function of alveolar macrophages by significantly (p<0.05) decreasing their phagocytic potential in terms of phagocytic uptake and intracellular killing, spreading and hydrogen peroxide (H2O2) release. Besides that thalidomide treatment also significantly (p<0.05) decreased neutrophil infiltration into the lung alveoli. Remarkably, the levels of pro-inflammatory cytokines (IL-1alpha and TNF-alpha) were found to be decreased significantly (p<0.05) in thalidomide treated group but the levels of IL-10 were found to be significantly (p<0.05) elevated. Thus thalidomide proved a promising immunomodulatory agent in acute lung inflammation associated with pneumonia caused by gram negative bacterial infection.

Alpha-phenyl-N-tert-butylnitrone attenuates hyperoxia-induced lung injury by down-modulating inflammation in neonatal rats

This study was done to determine whether alpha -phenyl-N-tert-butylnitrone (PBN), a spin-trapping agent possessing significant anti-inflammatory capabilities, could attenuate hyperoxia-induced lung injury, and if so, whether this protective effect is mediated by the down-modulation of inflammation in neonatal rats. Newborn Sprague-Dawley rat pups were subjected to 14 days of hyperoxia (> 90% oxygen) within 10 hours after birth. PBN treatment, given 100 mg/kg intraperitoneally daily throughout the experiment, significantly attenuated hyperoxia-induced lung pathology, such as decreased radial alveolar count, increased mean linear intercept, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling-positive cells. Hyperoxia-induced activation of nicotinamide adenine dinucleotide phosphate oxidase that is responsible for superoxide anion production, as evidenced by up-regulation and membrane translocation of p67phox, and the inflammatory responses, such as increased mRNA expression of tumor necrosis factor-alpha, interleukin-6, and transforming growth factor-beta, were also significantly attenuated with PBN treatment. In summary, a spin-trapping agent PBN significantly attenuated hyperoxia-induced lung injury by down-regulating the inflammatory responses in neonatal rats.

Human umbilical cord blood-derived mesenchymal stem cells attenuate hyperoxia-induced lung injury in neonatal rats

Recent evidence suggests mesenchymal stem cells (MSCs) can downmodulate bleomycin-induced lung injury, and umbilical cord blood (UCB) is a promising source for human MSCs. This study examined whether intratracheal or intraperitoneal transplantation of human UCB-derived MSCs can attenuate hyperoxia-induced lung injury in immunocompetent newborn rats. Wild-type Sprague-Dawley rats were randomly exposed to 95% oxygen or air from birth. In the transplantation groups, a single dose of PKH26-labeled human UCB-derived MSCs was administered either intratracheally (2 x 10(6) cells) or intraperitoneally (5 x 10(5) cells) at postnatal day (P) 5. At P14, the harvested lungs were examined for morphometric analyses of alveolarization and TUNEL staining, as well as the myeoloperoxidase activity, the level of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and transforming growth factor (TGF)-beta mRNA, alpha-smooth muscle actin (SMA) protein, and collagen levels. Differentiation of MSCs to the respiratory epithelium was also evaluated both in vitro before transplantation and in vivo after transplantation. Despite one fourth dosage of MSCs, significantly more PKH26-labeled donor cells were recovered with intratracheal administration than with intraperitoneal administration both during normoxia and hyperoxia. The hyperoxia-induced increase in the number of TUNEL-positive cells, myeloperoixdase activity, and the level of IL-6 mRNA were significantly attenuated with both intratracheal and intraperitoneal MSCs transplantation. However, the hyperoxia-induced impaired alveolarization and increased the level of TNF-alpha and TGF-beta mRNA, alpha-SMA protein, and collagen were significantly attenuated only with intratracheal MSCs transplantation. MSCs differentiated into respiratory epithelium in vitro and a few PKH26-positive donor cells were colocalized with pro surfactant protein C in the damaged lungs. In conclusion, intratracheal transplantation of human UCB-derived MSCs is more effective than intraperitoneal transplantation in attenuating the hyperoxia-induced lung injury in neonatal rats.

Erythropoietin attenuates hyperoxia-induced lung injury by down-modulating inflammation in neonatal rats

This study was done to determine whether recombinant human erythropoietin (rhEPO) treatment could attenuate hyperoxia-induced lung injury, and if so, whether this protective effect is mediated by the down-modulation of inflammation in neonatal rats. Newborn Sprague Dawley rat pups were subjected to 14 days of hyperoxia (>95% oxygen) within 10 hr after birth. Treatment with rhEPO significantly attenuated the mortality and reduced body weight gain caused by hyperoxia. With rhEPO treatment, given 3 unit/gm intraperitoneally at 4th, 5th, and 6th postnatal day, hyperoxia- induced alterations in lung pathology such as decreased radial alveolar count, increased mean linear intercept, and fibrosis were significantly improved, and the inflammatory changes such as myeloperoxidase activity and tumor necrosis factor-alpha expression were also significantly attenuated. In summary, rhEPO treatment significantly attenuated hyperoxia-induced lung injury by down-modulating the inflammatory responses in neonatal rats.

Thalidomide Prevents Bleomycin-Induced Pulmonary Fibrosis in Mice

Pulmonary fibrosis in humans can occur as a result of a large number of conditions. In idiopathic pulmonary fibrosis (IPF), pulmonary function becomes progressively compromised resulting in a high mortality rate. Currently there are no proven effective treatments for IPF. We have recently reported that IL-6 and TGF-beta(1) plays an important role in proliferation and differentiation of lung fibroblasts, and all-trans-retinoic acid (ATRA) prevented bleomycin-induced lung fibrosis through the inhibition of these cytokines. Thalidomide (Thal) has been used in the treatment of multiple myeloma through the inhibitory effect on IL-6-dependent cell growth and angiogenesis. In this study, we examined the preventive effect of Thal on bleomycin-induced pulmonary fibrosis in mice. We performed histological examinations and quantitative measurements of IL-6, TGF-beta(1), collagen type Ialpha1 (COL1A1), vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) in bleomycin-treated mouse lung tissues with or without the administration of Thal. Thal histologically ameliorated bleomycin-induced fibrosis in mouse lung tissues. Thal decreased the expressions of IL-6, TGF-beta(1), VEGF, Ang-1 Ang-2, and COL1A1 mRNA in mouse lung tissues. In addition, Thal inhibited angiogenesis in the lung. In vitro studies disclosed that Thal reduced 1) production of IL-6, TGF-beta(1), VEGF, Ang-1, and collagen synthesis from human lung fibroblasts, and 2) both IL-6-dependent proliferation and TGF-beta(1)-dependent transdifferentiation of the cells, which could be the mechanism underlying the preventive effect of Thal on pulmonary fibrosis. These data may provide a rationale to explore clinical use of Thal for the prevention of pulmonary fibrosis.

Class A scavenger receptor (CD204) attenuates hyperoxia-induced lung injury by reducing oxidative stress

To clarify the role of macrophage class A scavenger receptors (SR-A, CD204) in oxidative lung injury, we examined lung tissue of SR-A deficient (SR-A(-/-)) and wild-type (SR-A(+/+)) mice in response to hyperoxic treatment. Protein levels of bronchoalveolar lavage fluid (BALF) and pulmonary oedema (wet : dry weight ratios) were higher in SR-A(-/-) mice than those in SR-A(+/+) mice. Cumulative survival was significantly decreased in SR-A(-/-) mice. However, there were no differences in BALF macrophage and neutrophil count between the two groups. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) revealed that messenger RNA (mRNA) levels of the inducible nitric oxide synthase (iNOS) were increased during hyperoxic injury, and this increase was more prominent in SR-A(-/-) mice. Expression levels of iNOS in alveolar macrophages after hyperoxia in vivo and in vitro were higher in SR-A(-/-) macrophages compared with SR-A(+/+) macrophages. Immunohistochemistry using anti-nitrotyrosine antibodies revealed distinctive oxidative stress in the injured lung in both groups, but it was more remarkable in the SR-A(-/-) mice. After hyperoxic treatment, pulmonary mRNA levels of tumour necrosis factor-alpha(TNF-alpha) were elevated more rapidly in SR-A(-/-) mice than in SR-A(+/+) mice. Together these results suggest that SR-A expression attenuates hyperoxia-induced lung injury by reducing macrophage activation.

Developmental differences in the responses of IL-6 and IL-13 transgenic mice exposed to hyperoxia

Our previous work has shown that adult mice with overexpression of IL-6 and IL-13 in the lung have enhanced survival in hyperoxia associated with reduced hyperoxia-induced lung injury and cell death. We hypothesized that there are developmental differences in these responses in the adult vs. the newborn (NB) animal, and these responses have clinical relevance in the human NB. We compared the responses to 100% O(2) of NB IL-6 and IL-13 transgenic mice with wild-type littermate controls by evaluating mortality, lung tissue TUNEL staining, and mRNA expression using RT-PCR. We used ELISA to measure IL-6 levels in tracheal aspirates from human neonates. Our results show that, in contrast to the cytoprotective effects in mature mice, IL-6 caused significantly increased mortality, DNA injury, caspases, cell death regulator and angiogenic factor expression in hyperoxia in the NB. Furthermore, tracheal aspirate levels of IL-6 were significantly increased in premature neonates with respiratory distress syndrome who had an adverse outcome (bronchopulmonary dysplasia/death). In contrast to the protective effects in adults, there was no survival advantage to the NB IL-13 mice in hyperoxia. These findings imply that caution should be exercised in extrapolating results from the adult to the NB.

Cytokines in tolerance to hyperoxia-induced injury in the developing and adult lung

Cytokines are peptides that are produced by virtually every nucleated cell type in the body, possess overlapping biological activities, exert different effects at different concentrations, can either synergize or antagonize the effects of other cytokines, are regulated in a complex manner, and function via cytokine cascades. Hyperoxia-induced acute lung injury (HALI) is characterized by an influx of inflammatory cells, increased pulmonary permeability, and endothelial and epithelial cell injury/death. Some of these effects are orchestrated by cytokines. There are significant differences in the response of the developing versus the adult lung to hyperoxia. We review here cytokines (and select growth factors) that are involved in tolerance toward HALI in animal models. Increased cytokine expression and release have a cascade effect in HALI. IL-1 precedes the increase in IL-6 and CINC-1/IL-8 and this seems to predate the influx of inflammatory cells. Inflammatory cells in the alveolar space amplify the lung damage. Other cytokines that are primarily involved in this inflammatory response include IFN-gamma, MCP-1, and MIP-2. Certain cytokines (and growth factors) seem to ameliorate HALI by affecting cell death pathways. These include GM-CSF, KGF, IL-11, IL-13, and VEGF. There are significant differences in the type and temporal sequence of cytokine expression and release in the adult and newborn lung in response to hyperoxia. The newborn lung is greatly resistant to hyperoxia compared to the adult. The delayed increase in lung IL-1 and IL-6 in the newborn could induce protective factors that would help in the resolution of hyperoxia-induced injury. Designing a therapeutic approach to counteract oxygen toxicity in the adult and immature lung first needs understanding of the unique responses in each scenario.

Role of tumor necrosis factor alpha and its receptor I in preconditioning by hyperoxia

Hyperoxic pretreatment (>95% O(2)) can evoke myocardial adaptation to ischemia, a method which is potentially clinically usable. We wanted to investigate the role of tumor necrosis factor alpha (TNFalpha) and its p55 receptor (receptor I) in signaling of hyperoxic adaptation to ischemia. Mice deficient for TNFalpha (TNFalpha -/-) or the TNF receptor I (TNFRI -/-) gene and their wild types were subjected to 60 minutes of hyperoxia or sham treatment. Their lungs were then collected for immunoblotting, their hearts isolated and subjected to global ischemia and reperfusion in a Langendorff system, and aortic rings mounted in organ baths for reactivity studies. Hyperoxia increased expression of TNFalpha and TNFalpha converting enzyme in pulmonary proteins from wild type mice, in which hyperoxia increased myocardial tolerance to ischemia. Post-ischemic heart function was improved and infarct size reduced in wild type mice, but not in TNFalpha -/- or TNFRI -/-. The contractile response to TNFalpha on aortic rings was attenuated by hyperoxic pretreatment and by TNFRI -/-. Thus we conclude that TNFalpha, acting through TNFRI, appears important for the protective effects of hyperoxia.

Mitochondrial Damage and Metabolic Compensatory Mechanisms Induced by Hyperoxia in the U-937 Cell Line

Experimental hyperoxia represents a suitable in vitro model to study some pathogenic mechanisms related to oxidative stress. Moreover, it allows the investigation of the molecular pathophysiology underlying oxygen therapy and toxicity. In this study, a modified experimental set up was adopted to accomplish a model of moderate hyperoxia (50% O(2), 96 h culture) to induce oxidative stress in the human leukemia cell line, U-937. Spectrophotometric measurements of mitochondrial respiratory enzyme activities, NMR spectroscopy of culture media, determination of antioxidant enzyme activities, and cell proliferation and differentiation assays were performed. The data showed that moderate hyperoxia in this myeloid cell line causes: i) intriguing alterations in the mitochondrial activities at the levels of succinate dehydrogenase and succinate-cytochrome c reductase; ii) induction of metabolic compensatory adaptations, with significant shift to glycolysis; iii) induction of different antioxidant enzyme activities; iv) significant cell growth inhibition and v) no significant apoptosis. This work will permit better characterization the mitochondrial damage induced by hyperoxia. In particular, the data showed a large increase in the succinate cytochrome c reductase activity, which could be a fundamental pathogenic mechanism at the basis of oxygen toxicity.

Changes of free radical of liver and intestine in premature rat with hyperoxia-induced chronic lung disease

AIM: To investigate dynamic changes of free radical of liver and intestine in premature infant with hyperoxia-induced chronic lung disease (CLD).

METHODS: Superoxide dismutase (SOD) activity, concentration of malondialdehyde (MDA) in the liver, intestine and lung specimen on d 1, 3, 7, 14 and 21 in 40 premature rat with hyperoxia-induced CLD and 40 control premature rats were assayed with double wavelength scanning by spectrophotometer.

RESULTS: In model group, level of MDA in the liver and intestine was increased on day 14 (122±9 moL/g vs 68±7 moL/g, 117±9 moL/g vs 68±9 moL/g, P < 0.01), and then was decreased but still maintained at a higher level than that in control group at day 21 (P < 0.05). Level of MDA in the lung was increased on day 3, and reached a peak level on day 7 (94±12 mol/ g vs 24±5 mol/g, P < 0.001), and still maintained at a higher level than that in control group at day 21 (P < 0.01), but there was no significant difference in SOD activity among any groups (P>0.05).

CONCLUSION: Damage of free radicals in the liver and intestine can be induced by CLD in premature infant, but the time of occurrence is very delayed in the lung.

Short-term modulation of interleukin-1beta signaling by hyperoxia: uncoupling of IkappaB kinase activation and NF-kappaB-dependent gene expression

We have been interested in elucidating how simultaneous stimuli modulate inflammation-related signal transduction pathways in lung parenchymal cells. We previously demonstrated that exposing respiratory epithelial cells to 95% oxygen (hyperoxia) synergistically increased tumor necrosis factor-alpha (TNF-alpha)-mediated activation of NF-kappaB and NF-kappaB-dependent gene expression by a mechanism involving increased activation of IkappaB kinase (IKK). Because the signal transduction mechanisms induced by IL-1beta are distinct to that of TNF-alpha, herein we sought to determine whether hyperoxia modulates IL-1beta-dependent signal transduction. In A549 cells, simultaneous treatment with hyperoxia and IL-1beta caused increased activation of IKK, prolonged the degradation of IkappaBalpha, and prolonged the nuclear translocation and DNA binding of NF-kappaB compared with cells treated with IL-1beta alone in room air. Hyperoxia did not affect IL-1beta-dependent degradation of the interleukin receptor-associated kinase differently from treatment with IL-beta alone. In contrast to the effects on the IKK/IkappaBalpha/NF-kappaB pathway, simultaneous treatment with hyperoxia and IL-1beta did not augment NF-kappaB-dependent gene expression compared with treatment with IL-1beta alone. Similar observations were made in a different human respiratory epithelial cell line, BEAS-2B cells. In addition, simultaneous treatment with hyperoxia and IL-1beta caused hyperphosphorlyation of the NF-kappaB p65 subunit compared with treatment with IL-1beta alone. In summary, concomitant treatment of A549 cells with hyperoxia and IL-1beta augments activation of IKK, prolongs degradation of IkappaBalpha, and prolongs nuclear translocation and DNA binding of NF-kappaB. This activation, however, is not coupled to increased expression of NF-kappaB-dependent genes, and the mechanism of this decoupling is not related to decreased phosphorylation of p65.

Release of cytokines and apoptosis in fetal rat Type II pneumocytes exposed to hyperoxia and nitric oxide: modulatory effects of dexamethasone and pentoxifylline

The response of the fetal rat Type II pneumocyte (FTIIP), the stem cell of the alveolar epithelium, to hyperoxia would be helpful to understand the effects of oxygen-induced injury to the immature lung. In such a scenario, the presence of nitric oxide (NO) may have a protective or detrimental effect. Our goals were to evaluate the release of cytokines and apoptotic cell death in freshly isolated FTIIP (19-day) in the presence of 95% O(2) and/or NO. The effects of dexamethasone and pentoxifylline on the FTIIP cytokine response were also studied. There was no significant difference in the levels of IL-1beta and IL-10 from FTIIP, in room air, hyperoxia and/or NO at 2, 6 and 24 h. However, IL-6 release was significantly higher, when measured over time, after 2, 6 and 24 h of exposure to hyperoxia and NO. Dexamethasone in the presence of hyperoxia and/or NO increased the release of IL-10 at 24 h. There was increased apoptosis in FTIIP exposed to hyperoxia alone and in combination with NO; this was significantly attenuated in the presence of dexamethasone and pentoxifylline. We speculate that the cytoprotective effects of dexamethasone in the immature lung may, in part, be mediated via IL-10.

Phase II study of the antiangiogenesis agent thalidomide in recurrent or metastatic squamous cell carcinoma of the head and neck

BACKGROUND

Thalidomide has been shown to have antiangiogenic effects in preclinical models as well as a significant antitumor effect in hematologic tumors such as multiple myeloma. The authors performed this Phase II study to determine the activity, toxicity profile, and antiangiogenic effect of thalidomide in patients with locoregionally recurrent or metastatic squamous cell carcinoma of the head and neck.

METHODS

Twenty-one patients with recurrent or metastatic squamous cell carcinoma of the head and neck were treated with single-agent thalidomide. All patients had received radiation therapy, and most had undergone surgery (95%) and/or chemotherapy (90%). Thalidomide was initiated at 200 mg;3>daily and increased to a target dose of 1000 mg daily. Patients continued treatment until disease progression, unacceptable toxicity, or death occurred.

RESULTS

All 21 patients eventually developed progressive disease. Median time to progression was 50 days (95% confidence interval, 28-70), with median overall survival time of 194 days (95% lower confidence boundary, 151), similar to the progression and survival times reported for this patient group with other agents. Thalidomide was generally well tolerated, with few patients experiencing Grades 3 to 4 toxicities. Serum vascular endothelial growth factor and basic fibroblast growth factor levels increased in six of seven patients, for whom paired serum samples were available and all of whom had progressive disease.

CONCLUSIONS

In this heavily pretreated population of patients with advanced squamous cell carcinoma of the head and neck, thalidomide does not appear to have single-agent antitumor activity. Further evaluation of the mechanism of action of thalidomide is indicated. Potentially, future evaluations of thalidomide may be performed in combination with other antiangiogenic or cytotoxic agents in patients with earlier stage disease or in patients with minimal residual disease.