Variability in standard care for cytomegalovirus prevention and detection in pediatric lung transplantation: survey of eight pediatric lung transplant programs

Cytomegalovirus (CMV) infection after pediatric lung transplantation is a significant risk factor for morbidity and mortality in the first year after transplantation. Multiple strategies have been reported for CMV prevention among adult lung transplant programs. In contrast, little information has been reported regarding protocols for prevention and detection of CMV from pediatric programs. We conducted a survey to better understand the range of practice patterns for CMV prevention and detection at pediatric lung transplant centers. A self-administered questionnaire was distributed to 11 pediatric lung transplant centers identified through the International Pediatric Lung Transplant Collaborative in September 2002. A member of the lung transplant team from each institution was asked to provide the methods of CMV prevention and surveillance. Eight of 11 centers surveyed responded to the questionnaire accounting for 45.6% (26 of 57) and 100% (three of three) of the pediatric lung transplants performed in the US and UK in 2001, respectively. All centers used prophylactic therapy against CMV with either ganciclovir or valganciclovir with duration ranging from 3.5 wk to indefinitely. Most centers (six of eight) prescribed a prophylactic regimen based on donor and recipient CMV serostatus. Half (four of eight) of the centers report using CMV hyperimmune globulin in addition to an antiviral agent. Method for CMV detection varied widely, including use of conventional viral culture (n = 1), antigenemia (n = 7), and polymerase chain reaction (n = 2). A wide range of strategies is used to prevent and detect CMV in pediatric lung transplant recipients with little empiric evidence demonstrating the optimal approach. A retrospective analysis among these centers is being conducted to evaluate the efficacy of these approaches.

Modulation of Sp1 and Sp3 in lung epithelial cells regulates ClC-2 chloride channel expression

ClC-2 is a pH- and voltage-activated chloride channel, which is highly expressed in fetal airways and downregulated at birth. The ClC-2 promoter contains consensus binding sites within the first 237 bp, which bind transcription factors Sp1 and Sp3(1). This study directly links Sp1 and Sp3 with ClC-2 protein expression by demonstrating: (i) induction of ClC-2 protein by transient overexpression of each transcription factor in adult rat Type II cells, which have low levels of ClC-2; and (ii) reduction of ClC-2 expression by incubation with a competitive inhibitor of Sp1 and Sp3 in fetal rat Type II cells, which have high levels of endogenous ClC-2. Endogenous fetal lung Sp1 is differentially expressed as two major species of 105 kD and 95 kD. Although low-level expression of Sp1 in adult cells is almost exclusively the 105-kD species, overexpression of Sp1 results in increased expression of the 95-kD band. These experiments suggest that the mechanism for postnatal reduction of ClC-2 expression in lung epithelia is based on decreased interaction of Sp1 and Sp3 with the ClC-2 promoter.

Cyclosporin and tacrolimus do not potentiate oxidative damage in pulmonary epithelial cells

Oxidative stress can lead to cellular injury and apoptosis within the pulmonary allograft. We investigated the effects of oxidative damage on the growth and survival of cultured human pulmonary epithelial cells treated with hydrogen peroxide (H(2)O(2)) in the presence and absence of cyclosporin A (CsA) and tacrolimus. Treatment of A549 cells with 1 mmol/l H(2)O(2) for 48 h led to a 39% decrease in cell growth. Treatment with 500 ng/ml CsA for 48 h reduced cell survival by 68%, and treatment with 30 ng/ml tacrolimus reduced cell survival by 32%. The addition of CsA or tacrolimus to cells grown in H(2)O(2) did not further diminish cell survival. These studies demonstrated that H(2)O(2), CsA, and tacrolimus treatments decrease survival of pulmonary epithelial cells. However, CsA and tacrolimus do not further potentiate H(2)O(2)-induced toxicity.

Ciprofloxacin-induced renal insufficiency in cystic fibrosis

Acute renal insufficiency is known to occur in patients who are taking ciprofloxacin, particularly the elderly. We report two young patients with cystic fibrosis who presented with acute renal insufficiency after 2-3 weeks of oral ciprofloxacin therapy. The incidence of this adverse effect in children and young adults who have cystic fibrosis is unknown. Multiple mechanisms for ciprofloxacin-induced nephrotoxicity have been proposed.

Extracorporeal photopheresis in the treatment of persistent rejection in a pediatric lung transplant recipient

Lung transplantation is an accepted therapy for children with end-stage lung disease. One-year lung transplant survival rates of 86% have been reported by the United Network for Organ Sharing. Allograft rejection is a common cause of death following transplantation. Extracorporeal photopheresis is a novel therapy used to treat solid-organ rejection; this therapy involves separating the leukocyte-rich fraction from whole blood, treating with psoralen and ultraviolet light A exposure. The objective of therapy is to reverse progressive and persistent rejection. Working collaboratively with an institution that offers extracorporeal photopheresis may provide an alternative or additional therapy in the management of ongoing rejection following solid-organ transplantation.

Effect of adeno-associated virus-specific immunoglobulin G in human amniotic fluid on gene transfer

Intra-amniotic administration of adeno-associated virus (AAV) vector may be an effective way to deliver gene therapy for treatment of congenital pulmonary and intestinal disorders. In an effort to understand potential barriers to intra-amniotic gene therapy better, we determined whether human amniotic fluid (AF) could act as an inhibitor of AAV2-mediated gene transfer. AF samples were obtained from 21 different human pregnancies during routine amniocentesis at 16-20 weeks of gestation. An immortalized fetal human tracheal epithelial cell line (FHTE) was infected with AAV2 containing a luciferase reporter gene driven by the SV40 promoter in the presence and absence of each AF sample. Inhibition of transgene expression was observed in 8 (38%) of the AF samples (inhibitory AF) and resulted in luciferase levels of only 1.4% +/- 0.6% of those obtained with infection in normal media. Infections in 13 samples (62%) resulted in transgene expression comparable or in excess of infection in media alone (noninhibitory AF). Removal of immunoglobulin G (IgG) from inhibitory AF samples with Protein A returned luciferase expression to control levels (119% +/- 37% of control), suggesting the possible presence of inhibiting antibody. Eleven of the AF samples were evaluated by enzyme-linked immunosorbent assay (ELISA) for specific anti-AAV antibodies. All noninhibitory AF samples were negative (titers of < 1:20; n = 3), and 6 of the 8 inhibitory samples contained specific anti-AAV antibodies at titers ranging from 1:40 to 1:160. These studies demonstrate that AF from some individuals contains AAV-specific IgG that can inhibit gene transfer.

cis-Acting elements within CFTR 5'-flanking DNA are not sufficient to decrease gene expression in response to phorbol ester

The cystic fibrosis transmembrane conductance regulator gene (CFTR) is regulated in a tissue-specific and developmental fashion. Although it has been known for some time that phorbol esters decrease CFTR expression in cell lines that have high CFTR mRNA levels, the cis-acting elements that control this down-regulation remain ill-defined. The role of cis-acting elements within the CFTR minimal promoter in modulating responses to phorbol 12-myristate 13-acetate (PMA) and forskolin was assessed using luciferase reporter gene (luc)-containing plasmids transfected into Calu-3 and HT-29 cells. PMA treatment had no effect on luciferase activity in Calu-3 cells transiently transfected with plasmids containing luc driven by up to 2.3 kb of CFTR 5'-flanking DNA. PMA increased luciferase activity in transfected HT-29 cells. A more extensive region of DNA was evaluated using a yeast artificial chromosome (YAC) containing luc driven by approximately 335 of CFTR 5'-flanking DNA (y5'luc) stably introduced into HT-29 cells. Clonal cell lines containing y5'luc were created and assessed for luciferase activity at baseline and in response to forskolin and PMA. There was a wide range of baseline luciferase activities among the clones (42-1038 units/microg protein) that was not entirely due to the number of luc copies present within the cells. Treatment with both PMA and forskolin led to increased luciferase activity in six randomly selected clonal cell lines. As expected, endogenous CFTR expression increased in response to forskolin and decreased in response to PMA. These studies demonstrate that luc-containing YAC vectors can be used to study CFTR expression in human cells. In addition, these data suggest that important regulatory elements responsible for decreased CFTR expression in response to PMA are not located upstream of CFTR in the approximately 335 kb 5'-flanking sequence included in this YAC construct.

Bilateral diaphragm paralysis following lung transplantation and cardiac surgery in a 17-year-old

Bilateral diaphragm paralysis is a rare complication of lung transplantation. This report describes the development of chronic respiratory failure due to bilateral diaphragm paralysis following bilateral lung transplantation and closure of a patent foramen ovale. This patient required prolonged mechanical ventilation post-operatively; however, he eventually had adequate recovery of diaphragm function to wean from mechanical ventilation.

Skeletal dysplasias and their effect on the respiratory system

Children with skeletal dysplasia frequently have pulmonary disease which can be life threatening. These pulmonary problems are due to multiple aetiologies including thoracic and craniofacial anomalies predisposing to restrictive lung disease, upper airway obstruction and central apnoea. Recognition of pulmonary disease and early intervention improves the survival and quality of life for these children.

Eosinophilic infiltrates in a pulmonary allograft: a case and review of the literature

An unusual case of peribronchial eosinophilic infiltrates associated with peripheral blood eosinophilia in a lung transplant patient is described. The role that eosinophils play in lung allograft rejection is reviewed. Tissue eosinophils have been associated with acute pulmonary allograft rejection. Although, eosinophils in bronchoalveolar lavage fluid (BAL) have been observed in allograft rejection, this relationship is less well defined. The role of eosinophils in the pathophysiology of allograft rejection is unclear.

An unusual case of fatal pulmonary allograft rejection

This case report describes an atypical form of acute pulmonary allograft rejection that was refractory to conventional therapy. The rejection manifested primarily as interstitial lymphocytic infiltrates with little perivascular involvement. Despite aggressive therapy the patient died within 7 months of transplant. The timely recognition and treatment of unusual forms of allograft rejection is vital in the management of pulmonary transplant patients.

CFTR intron 1 increases luciferase expression driven by CFTR 5'-flanking DNA in a yeast artificial chromosome

The DNA elements that account for the highly regulated expression of the cystic fibrosis transmembrane conductance regulator gene (CFTR) are poorly understood. The goal of this study was to assess the feasibility of using a yeast artificial chromosome (YAC)-based reporter gene construct to define these elements further. An approximately 350-kb YAC (y5'luc) was constructed by replacing CFTR with a luciferase reporter gene (luc). A second YAC (y5'lucI) was similarly constructed but included a putative positive regulatory element from CFTR intron 1. Stable Chinese hamster ovary (CHO-K1) cell clones were derived using each YAC to assess the role that luc copy number and the presence of intron 1 played in luc expression. The CHO-K1 clonal cell lines demonstrated a wide range of luciferase activity. On average, this activity was significantly higher in clones derived from y5'lucI. After correcting for luc copy number, the presence of intron 1 was still associated with an increase in luciferase activity (P < 0.05), despite the fact that luciferase activity did not correlate with luc copy number in y5'luc-derived clones (r = -0.12). In contrast, the luciferase activity correlated well with luc copy number in the clones derived from y5'luc (r = 0. 75). These data are consistent with a positive role for intron 1 in regulating CFTR expression, but suggest that copy number is not the only factor that determines expression levels, particularly when this element is present. This YAC-based reporter system will provide a unique strategy for further assessment of the cis-acting elements that control CFTR expression.

Sleep-disordered breathing in children with achondroplasia

OBJECTIVE

Our objective was to characterize sleep-disordered breathing in 88 children with achondroplasia aged 1 month to 12.6 years.

RESULTS

At the time of their initial polysomnography, five children had previously undergone tracheostomy, and seven children required supplemental oxygen. Initial polysomnography demonstrated a median obstructive apnea index of 0 (range, 0 to 19.2 apneas/hr). The median number of central apneas with desaturation per study was 0.5 (0 to 49), the median oxygen saturation nadir was 91% (50% to 99%), and the median peak end-tidal pCO2 was 47 mm Hg (36 to 87 mm Hg). Forty-two children (47.7%) had abnormal initial study results, usually caused by hypoxemia. Two children with severe obstructive sleep apnea eventually required continuous positive airway pressure therapy, and three additional children required tracheostomies.

CONCLUSIONS

(1) Children with achondroplasia often have sleep-related respiratory disturbances, primarily hypoxemia. (2) The majority do not have significant obstructive or central apnea; however, a substantial minority are severely affected. (3) Tonsillectomy and adenoidectomy decreases the degree of upper airway obstruction in most but not all children with achondroplasia and obstructive sleep apnea. (4) Restrictive lung disease can present at a young age in children with achondroplasia.

Functional human CFTR produced by stable Chinese hamster ovary cell lines derived using yeast artificial chromosomes

The cystic fibrosis transmembrane conductance regulator gene (CFTR) encodes a transmembrane protein (CFTR) which functions in part as a cyclic adenosine monophosphate (cAMP)-regulated chloride channel. CFTR expression is controlled temporally and cell specifically by mechanisms that are poorly understood. Insight into CFTR regulation could be facilitated by the successful introduction of the entire 230 kb human CFTR and adjacent sequences into mammalian cells. To this end, we have introduced two different CFTR-containing yeast artificial chromosomes (YACs) (320 and 620 kb) into Chinese hamster ovary-K1 (CHO) cells. Clonal cell lines containing human CFTR were identified by PCR, and the genetic and functional analyses of one clone containing each YAC are described. Integration of the human CFTR-containing YACs into the CHO genome at a unique site in each cell line was demonstrated by fluorescence in situ hybridization (FISH). Southern blot analysis suggested that on the order of one copy of human CFTR was integrated per CHO cell genome. Fiber-FISH and restriction analysis suggested that CFTR remained grossly intact. Northern analysis showed full-length, human CFTR mRNA. Immunoprecipitation followed by phosphorylation with protein kinase demonstrated mature, glycosylated CFTR. Finally, chloride secretion in response to cAMP indicated the functional nature of the human CFTR. This study provides several novel results including: (i) functional human CFTR can be expressed from these YACs; (ii) CHO cells are a permissive environment for expression of human CFTR; (iii) the level of human CFTR expression in CHO cells is unexpectedly high given the lack of endogenous CFTR production; and (iv) the suggestion by Fiber-FISH of CFTR integrity correlates with functional gene expression. These YACs and the cell lines derived from them should be useful tools for the study of CFTR expression.

Role of tropoelastin fragmentation in elastogenesis in rat smooth muscle cells

Neonatal rat aortic smooth muscle cell cultures produce two major soluble elastin molecules termed protropoelastin (77 kDa) and tropoelastin (71 kDa). Cell layer extracts are protroproelastin-enriched, while protropoelastin, tropoelastin, and significant amounts of discrete elastin fragments (Mr of 66,000, 61,000, 56,000, and 45,000) are present in preparations from the medium of these cultures. To determine the role of the various elastin molecules in the metabolism of elastin in neonatal rat aortic smooth muscle cell cultures, the amino termini of these proteins were sequenced. All soluble elastin components present in the medium were purified as a single peak by high performance liquid chromatography; further separation of the components was achieved by polyacrylamide gel electrophoresis and electroblotting. The bands were excised and sequenced. The amino-terminal sequences of protropoelastin, tropoelastin, and the 66-kDa, 61-kDa, and 56-kDa fragments were identical: Gly-Gly-Val-Pro-Gly-Ala-Val-Pro-Gly-Gly. This sequence is identical with published amino-terminal sequences of tropoelastins from several other species. As expected, when the cell cultures were pulsed with [3H]valine, all the soluble elastin molecules were radioactive, while only protropoelastin appeared radioactive after [35S] cysteine pulsing. Since cysteine is present only in the carboxyl-terminal end of the molecule, all the data indicate that the cleavage of the elastin fragments identified in the culture are occurring at the carboxyl end of protropoelastin. These results are consistent with the original hypothesis that a precursor-product relationship exists between the 77-kDa and 71-kDa soluble elastin molecules. Based on known tropoelastin sequences and the molecular weights of the discrete fragments, additional fragmentation of protropoelastin and/or tropoelastin most likely occurs at the lysine/alanine-enriched domains presumably involved in cross-link formation.

Effect of the reducing environment on the accumulation of elastin and collagen in cultured smooth-muscle cells

We show here that cultured neonatal-rabbit aortic smooth-muscle cells produce and accumulate significant amounts of insoluble elastin. When grown in the presence of ascorbic acid, the amount of insoluble elastin in these cultures decreases, whereas the accumulation of collagen increases. These changes have been attributed to increased hydroxylation of proline in elastin. The function of ascorbic acid in proline hydroxylation is thought to be that of a reductive cofactor that maintains the proper oxidation state of molecular iron in the enzyme complex. This study shows that both ascorbic and isoascorbic acids act similarly to modify the accumulation of elastin and collagen in culture. On the other hand, cultures grown in the presence of dithiothreitol, a reducing agent previously shown to act as a cofactor for prolyl hydroxylase, do not demonstrate altered elastin accumulation. These studies are consistent with the suggestion that there is a specific role for ascorbic acid in this cellular system that cannot be replaced by other reducing cofactors.

Congo red binding of elastin in aortic smooth muscle cell cultures

These studies demonstrate that the strong binding capacity of elastin for Congo red can be used to advantage in aortic smooth muscle cell cultures. A fibrous elastin network fluoresces when Congo red is added. Congo red does not alter accumulation of elastin or of total protein, even when the cells are grown in the presence of the dye for long periods of time, indicating that it is not toxic. Porcine pancreatic elastase was used to solubilize elastin in these cultures, to determine the molar ratio of Congo red to elastin, thus making it possible to estimate the amount of elastin solubilized when the cultures are injured. Congo red binding to elastin will be useful in studying elastin accumulation and/or degradation in vitro and in vivo.

Glycosaminoglycan content in neonatal rat aortic smooth muscle cell cultures

In the present study the biosynthesis of glycosaminoglycans (GAGs) by neonatal rat aortic smooth muscle cells in culture was studied. Heparan sulfate (HS) was the predominant GAG of the cell layer accounting for 32-49% of the total GAGs depending on the time in culture. The presence of low sulfated chondroitin sulfate (LSC) in aortic smooth muscle cell cultures is reported here for the first time. The effect of ascorbate on the synthesis and accumulation of these macromolecules resulted in a relative increase of C4S and DS in the cell layer. In contrast, the distribution of the GAGs which were secreted into the medium was not significantly effected by the addition of ascorbate. While HS was always found to be a minor component, the other GAGs were present in about equal concentrations. The total GAG accumulation in the medium was much greater (91-97%) than that of the cell layer (3-9%) indicating that the cells are synthesizing relatively large amounts of GAGs, although incorporation of these macromolecules into the extracellular matrix was consistently low.

Elastase effect on the extracellular matrix of rat aortic smooth muscle cells in culture

The effect of elastase on the extracellular matrix of neonatal rat aortic smooth muscle cell cultures was monitored both chemically and ultrastructurally. Porcine pancreatic elastase was shown to decrease the elastin content in these cultures. Although chemically no distinction could be made between the elastin remaining in the culture matrix after elastase when compared to that in the nontreated cultures, the elastin was dramatically altered morphologically. The elastin assumed a "mottled" appearance after elastase treatment similar to that seen in vivo in emphysema models. A highly sensitive immunogold staining technique was used to detect elastin at the earliest stages of accumulation. Pulse experiments demonstrated an increase in protein synthesis by the cells 20 hr after elastase exposure. The culture system described here provides a model for probing in vivo elastase effects on elastin-containing tissues.

Effect of protein-hydroxyethylmethacrylate hydrogels on cultured endothelial cells

The use of protein hydroxy ethylmethacrylate (HEMA) hydrogels to control cell morphology and growth, as well as the synthesis of extracellular matrix components, is described in this communication. HEMA hydrogels prepared with collagen support growth of embryonic lung fibroblasts (IMR-90), as well as bovine aortic and pulmonary artery endothelial cells at a level comparable to the respective cells grown on tissue culture surfaces. On the other hand, HEMA hydrogels prepared with solubilized elastin inhibit the fibroblast growth and prevent both types of endothelial cell cultures from achieving their normal morphology. These morphologically altered endothelial cells resume a normal cobblestone-like appearance when subcultivated from the elastin-HEMA hydrogels to tissue culture plastic. When pulsed with [14C]proline, the procollagens synthesized by the endothelial cells on the different surfaces vary, as shown by immunoprecipitation and polyacrylamide gel electrophoresis. On the standard tissue culture plastic, the confluent cells produce mainly type III procollagen in the medium, whereas those endothelial cells grown on collagen and elastin-HEMA hydrogels synthesize primarily type I procollagen (much like sprouting cells on tissue culture plastic), regardless of their morphology.