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Treating Veterans with chronic obstructive pulmonary disease complicated by pulmonary hypertension (COPD-PH) using phosphodiesterase type-5 inhibitor pharmacotherapy is common, but efficacy data are lacking. To address this further, patients with COPD-PH from five Department of Veterans Affairs hospitals were randomized (1∶1) to receive placebo or oral tadalafil (40 mg/day) for 12 months. The primary endpoint was changed from baseline in 6-min walk distance at 12 months. Secondary endpoints included change from baseline in pulmonary vascular resistance, mean pulmonary artery pressure, and symptom burden by the University of California San Diego shortness of breath questionnaire scale at 6 months. A total of 42 subjects (all male; 68 ± 7.6 years old) were randomized to placebo (

Background: In pulmonary hypertension subgroups, elevated pulmonary vascular resistance (PVR) of 3·0 Wood units or more is associated with poor prognosis. However, the spectrum of PVR risk in pulmonary hypertension is not known. To address this area of uncertainty, we aimed to analyse the relationship between PVR and adverse clinical outcomes in pulmonary hypertension. Methods: We did a retrospective cohort study of all patients undergoing right heart catheterisation (RHC) in the US Veterans Affairs health-care system (Oct 1, 2007–Sep 30, 2016). Patients were included in the analyses if data from a complete RHC and at least 1 year of follow-up were available. Both inpatients and outpatients were included, but individuals with missing mean pulmonary artery pressure (mPAP), pulmonary artery wedge pressure, or cardiac output were excluded. The primary outcome measure was time to all-cause mortality assessed by the Veteran Affairs vital status file. Cox proportional hazards models were used to assess the association between PVR and outcomes, and the mortality hazard ratio was validated in a RHC cohort from Vanderbilt University Medical Center (Sept 24, 1998–June 1, 2016). Findings: The primary cohort (N=40 082; 38 751 [96·7%] male; median age 66·5 years [IQR 61·1–73·5]; median follow-up 1153 days [IQR 570–1971]), included patients with a history of heart failure (23 201 [57·9%]) and chronic obstructive pulmonary disease (13 348 [33·3%]). We focused on patients at risk for pulmonary hypertension based on a mPAP of at least 19 mm Hg (32 725 [81·6%] of 40 082). When modelled as a continuous variable, the all-cause mortality hazard for PVR was increased at around 2·2 Wood units compared with PVR of 1·0 Wood unit. Among patients with a mPAP of at least 19 mm Hg and pulmonary artery wedge pressure of 15 mm Hg or less, the adjusted hazard ratio (HR) for mortality was 1·71 (95% CI 1·59–1·84; p

Background— Pulmonary hypertension (PH) is associated with increased morbidity across the cardiopulmonary disease spectrum. Based primarily on expert consensus opinion, PH is defined by a mean pulmonary artery pressure (mPAP) ≥25 mm Hg. Although mPAP levels below this threshold are common among populations at risk for PH, the relevance of mPAP Methods and Results— We analyzed retrospectively all US veterans undergoing right heart catheterization (2007–2012) in the Veterans Affairs healthcare system (n=21 727; 908-day median follow-up). Cox proportional hazards models were used to evaluate the association between mPAP and outcomes of all-cause mortality and hospitalization, adjusted for clinical covariates. When treating mPAP as a continuous variable, the mortality hazard increased beginning at 19 mm Hg (hazard ratio [HR]=1.183; 95% confidence interval [CI], 1.004–1.393) relative to 10 mm Hg. Therefore, patients were stratified into 3 groups: (1) referent (≤18 mm Hg; n=4 207); (2) borderline PH (19–24 mm Hg; n=5 030); and (3) PH (≥25 mm Hg; n=12 490). The adjusted mortality hazard was increased for borderline PH (HR=1.23; 95% CI, 1.12–1.36; P P P =0.0149) and PH (HR=1.15; 95% CI, 1.09–1.22; P 15 mm Hg; (2) pulmonary vascular resistance ≥3.0 Wood units; or (3) inpatient status at the time of right heart catheterization. Conclusions— These data illustrate a continuum of risk according to mPAP level and that borderline PH is associated with increased mortality and hospitalization. Future investigations are needed to test the generalizability of our findings to other populations and study the effect of treatment on outcome in borderline PH.

The angiotensin II type I receptor (AT1) was modified by replacing its third intracellular loop and C-terminal tail with the corresponding regions from the bradykinin B2 receptor. Transgenic mice were produced that overexpress this mutated receptor (AB3T). Considerably less collagen content in the intact aorta and in primary aortic smooth muscle (aSMCs) cultures was observed in the transgenic mice. On the other hand, elastin content remained unchanged as measured by western blot, and insoluble amino acid quantitation. The contraction of isolated aortas also remained unaltered. The aSMCs derived from the transgenic mice showed a reduction in angiotensin II responsive type I collagen production. In aSMCs from transgenic mice, the cascade of Akt to the mammalian target rapamycin (mTOR) to p70 S6 kinase (p70S6K) was not angiotensin II activated, while in the aSMCs from wild type mice the cascade was angiotensin II activated. Angiotensin activation of Smad2 and Stat3 was also reduced in the AB3T aSMCs. However, no change in the effect of transforming growth factor β (TGFβ) on type I collagen production was observed. Also, the activation of ERK and JNK and G protein linked signaling remained unaltered in response to angiotensin II. Akt and PI3K activation inhibitors blocked angiotensin II stimulated type I collagen expression in WT aSMCs, whereas ERK inhibitor had no such effect. Our results point to an Akt/ mTOR/ p70S6K regulation of collagen production by angiotensin II with participation of Smad2 and Stat3 cascades in this process.

To identify biological pathways associated with myocardial recovery from heart failure (HF), gene profiling and gene set enrichment analysis (GSEA) were examined in left ventricle of spontaneously hypertensive rats with HF (SHR-F) with no treatment, following treatment with the angiotensin converting enzyme inhibitor captopril, and treatment with captopril combined with the short chain fatty acid derivative phenylbutyrate. Failing hearts demonstrated depressed left ventricular ejection fraction, while ventricular volume and mass increased. Captopril treatment alone prevented further deterioration but did not improve myocardial function; relatively few transcripts were differentially expressed relative to untreated SHR-F. Gene sets identified by GSEA as downregulated with captopril treatment compared to SHR-F group included those related to hypoxia and reactive oxygen species, while upregulated gene sets included G protein signaling. Treatment with phenylbutyrate alone did not improve survival (no animals in this group survived the 30 day treatment period), while phenylbutyrate combined with captopril increased survival and significantly improved cardiac function in vivo and in vitro . Normalized microarray data identified 780 genes that demonstrated a combined treatment effect of which 258 genes were modified with HF. Fatty acid metabolism and ion transport were among the most significantly upregulated pathways in the combined treatment group compared to untreated SHR with HF, whereas those related to oxidative stress, growth, inflammation, protein degradation, and TGF-β signaling were downregulated. These findings demonstrate improved myocardial function and regression of cardiac hypertrophy, and identify many HF related gene sets altered with phenylbutyrate and captopril treatment, but not captopril alone. These results characterize gene sets associated with recovery from HF, and suggest that phenylbutyrate may be a potentially effective adjunctive treatment, together with captopril, by synergistically modulating pathways that contribute to restoration of contractile function of the failing SHR heart.

Invasive cardiopulmonary exercise testing (iCPET) combines full central hemodynamic assessment with continuous measurements of pulmonary gas exchange and ventilation to help in understanding the pathophysiology underpinning unexplained exertional intolerance. There is increasing evidence to support the use of iCPET as a key methodology for diagnosing heart failure with preserved ejection fraction and exercise-induced pulmonary hypertension as occult causes of exercise limitation, but there is little information available outlining the methodology to use this diagnostic test in clinical practice. To bridge this knowledge gap, the operational protocol for iCPET at our institution is discussed in detail. In turn, a standardized iCPET protocol may provide a common framework to describe the evolving understanding of mechanism(s) that limit exercise capacity and to facilitate research efforts to define novel treatments in these patients.

Fibulin-5 (FBLN5), an extracellular matrix glycoprotein required for normal elastogenesis, is coordinately expressed with elastin during lung injury and repair. We found that treatment with transforming growth factor-beta (TGF-beta) induced a rapid but transient increase in FBLN5 heterogeneous nuclear RNA (hnRNA) followed by a sustained increased in the steady-state level of FBLN5 mRNA. The transcription start site of the human FBLN5 gene was localized at 221 nucleotides upstream of the translation start site by using primer extension, Northern blots, and functional analysis of transcriptional activity in reporter plasmids containing 5'-flanking regions. TGF-beta markedly increased FBLN5 promoter activity in transient transfection assays. Two putative Smad-binding sites were identified within the proximal promoter and are required for this TGF-beta induction. Electrophoretic gel mobility shift assay revealed that TGF-beta strongly increased binding of Smad2 and Smad3 nuclear complexes to the proximal FBLN5 promoter and induced a Smad2/3-dependent binding of slow migrating nuclear protein complex. FBLN5 mRNA induction by TGF-beta was blocked by pretreatment with TGF-beta receptor inhibitor SB-431542, the phosphatidylinositol 3-kinase (PI3-kinase) inhibitor LY-294002, and actinomycin D. Basal and TGF-beta-induced FBLN5 hnRNA and mRNA were strongly and proportionally decreased by LY-294002, as was TGF-beta-induced phosphorylation of Akt, but not Smad3, as measured by Western blot analysis. In addition, LY-294002 markedly and proportionally decreased FBLN5 promoter activity in transient transfection analyses with TGF-beta-treated or untreated lung fibroblasts. These studies demonstrate that induction of FBLN5 gene expression in lung fibroblasts is mediated via canonical TGF-beta/Smad signaling and requires the PI3-kinase/Akt pathway.

Osteopontin is a multifunctional matricellular protein identified as one of the most upregulated genes in pulmonary fibrosis. Experimental animal models have identified early pro-fibrotic cytokines as essential to the pathogenesis of inflammation-induced pulmonary fibrosis. However, the principal sources of osteopontin in the fibroproliferative lung, and the factors responsible for its induction, have not been fully defined. We isolated primary rat lung fibroblasts in culture to examine the expression and regulation of lung fibroblast-derived osteopontin. Our results demonstrate a potent and dramatic increase in osteopontin expression induced by interleukin-1beta (IL-1beta), whereas tumor necrosis factor-alpha, transforming growth factor-beta, and angiotensin II had minimal effect. Stimulation with IL-1beta resulted in the secretion of soluble osteopontin protein. We found that osteopontin expression by IL-1beta was regulated via signaling primarily through the mitogen-activated protein kinase member ERK1/2, partially by p38 MAPK, but not at all by JNK. Finally, the mechanism of IL-1beta increase in osteopontin mRNA requires de novo transcription and translation. In conclusion, we find that osteopontin is expressed by primary lung fibroblasts and is potently upregulated by the early inflammatory and pro-fibrotic cytokine IL-1beta. Activated fibroblasts may be a significant source of osteopontin production during lung fibrogenesis.

Macrophage and neutrophil proteinases damage lung elastin, disrupting alveolar epithelium and filling alveoli with inflammatory exudate. Alveolar collapse and regional hypoxia occur. Whether low oxygen tension alters fibroblast-mediated lung repair is unknown. To determine the effect of chronic hypoxia on repair of enzyme-induced elastin disruption, primary rat lung fibroblasts produced elastin matrix for 5 wk before treatment with porcine pancreatic elastase (PPE). After exposure to PPE or saline, cultures recovered for 2 wk in normoxia (21% O2) or hypoxia (3% O2). Hypoxia suppressed regeneration of hot alkali-resistant elastin, achieving only 49% of the repair achieved in normoxic cultures. Vascular smooth muscle cells and lung fibroblasts repair elastin by two pathways: de novo synthesis and salvage repair. Although both pathways were affected, hypoxia predominantly inhibited de novo synthesis, decreasing formation of new elastin matrix by 63% while inhibiting salvage repair by only 36%. Prolonged hypoxia alone downregulated steady-state levels of elastin mRNA by 45%, whereas PPE had no significant effect on elastin gene expression. Electron microscopy documented preservation of intracellular organelles and intact nuclei. Together, these data suggest that regional hypoxia limits lung elastin repair following protease injury at least in part by inhibiting elastin gene expression.

The repair of alveolar structures following endotracheal administration of porcine pancreatic elastase (PPE) to mice involves the coordinated deposition of new matrix elements. We determined the induction of the myofibroblast phenotype following elastolytic injury to mouse lung by examining the expression of alpha-smooth muscle actin (alpha-SMA) by immunohistochemistry. We also examined elastin and alpha1(I) collagen mRNA expression by in situ hybridization. Changes in airspace dimensions were assessed by determining mean linear intercept. In untreated mice, alpha-SMA was localized to vascular structures and large airways, with no detectable expression in alveolar units. PPE induced alpha-SMA expression in damaged areas surrounding large vessels, in septal remnants, and in the opening ring of alveolar ducts. Elastin and alpha1(I) collagen mRNA expression were up-regulated in residual alveolar structures and septal walls. PPE dose-response studies indicated that alpha1(I) collagen and elastin mRNA expression were not induced in areas of normal lung adjacent to damaged lung. The administration of low dose PPE resulted in increased alpha-SMA protein and elastin mRNA expression in the cells comprising the opening ring of alveolar ducts. Our data suggest that repair mechanisms following elastolytic injury are confined to overtly damaged alveolar structures and involve the induction of the myofibroblast phenotype.

Interstitial fibroblasts are an integral component of the alveolar wall. These cells produce matrix proteins that maintain the extracellular scaffold of alveolar structures. Emphysema is characterized by airspace enlargement resulting from the loss of alveolar cellularity and matrix. In this study, we explored the endotracheal delivery of fibroblasts to the lung parenchyma as a means of repairing damaged alveolar structures directly or indirectly for the delivery of transgenes. Fibroblasts were isolated from the lungs of neonatal transgenic mice expressing GFP during the period of rapid alveolarization. These GFP+ cells maintained their myofibroblast phenotype in culture and expressed elastin and alpha-smooth muscle actin mRNA. We administered GFP+ fibroblasts to saline- and elastase-treated mice by endotracheal instillation. We detected more GFP+ fibroblasts in the alveolar walls and in the interstitial areas of elastase-injured lungs than in normal lungs as assessed by immunohistochemistry and fluorescent imaging. The presence of GFP+ fibroblasts in the interstitium demonstrated transepithelial migration of these cells. Expression of GFP+ fibroblasts in recipient lungs was maintained for at least 20 d after endotracheal administration. These cells synthesize matrix components including elastin in vitro and could contribute to restoring the structural integrity of the alveolar wall.

The objective of this study was to investigate the histology of tissue formed when fetal rat lung cells were grown in a collagen-glycosaminoglycan (GAG) tissue-engineering scaffold. The goal was the formation of lung histotypic structures in the tissue-engineering scaffolds in vitro. Achieving this goal would facilitate future investigations of the effects of selected scaffold design parameters on processes that may underlie aspects of lung regeneration in vivo. Lung cells were obtained from Sprague-Dawley rats after 16 and 19 days of gestation. These dissociated cells were seeded into type I collagen-chondroitin 6-sulfate matrices, 8 mm in diameter by 2 mm in thickness, cross-linked and sterilized by dehydrothermal treatment. Approximately 28 million cells were seeded into each spongelike sample. Histological and immunohistochemical studies were performed at termination periods of 2 days and 1, 2, and 3 weeks. The enzymatically dissociated 19-day gestation fetal rat lung cells formed and maintained alveolar-like structures, 50-60 microm in diameter, in the collagen- GAG scaffold. A novel finding was that all of the cell-seeded scaffolds underwent cell-mediated contraction that appeared to be associated with the finding by immunohistochemistry of expression of alpha-smooth muscle actin in some cells. These results demonstrate the capability of dissociated lung cells to form lung histotypic structures in collagen-GAG tissue-engineering scaffolds in vitro. This culture system may be of value in facilitating exploration of strategies for preparing such scaffolds for the regeneration of lung tissue in vivo.

Fibrotic lung diseases are characterized by excess extracellular matrix production, in particular type I collagen. Phenylbutyrate (PB) is a non-toxic pharmacological compound that functions as a weak histone deacetylase inhibitor. In hepatic stellate cells, the synthesis of type I collagen expression is decreased by inhibiting histone acetylation. Our studies examined the regulation of type I collagen by PB in human lung fibroblasts. We found that PB decreases basal and transforming growth factor-beta-stimulated alpha1(I) collagen mRNA and protein levels. Northern blot analyses demonstrated that PB decreases steady-state alpha1(I) collagen mRNA levels by 78% without significantly changing the stability of the mRNA transcript. PB stimulates cAMP production and increases the acetylation of histone H4, but does not affect the activity of two transforming growth factor-beta (TGF-beta)-responsive luciferase reporter constructs. These data suggest that PB regulates type I collagen expression in human lung fibroblasts by mechanisms that include cAMP production and histone acetylation. PB may have therapeutic use in fibrotic lung diseases.

We previously showed that interleukin (IL)-1beta decreases elastin gene transcription through activation of the NF-kappaB subunit p65 in neonatal rat lung fibroblasts. The present study was undertaken to further explore the molecular mechanisms responsible for the inhibitory effect of IL-1beta on elastin gene transcription. We found that cycloheximide blocked IL-1beta-induced downregulation of elastin mRNA but did not inhibit IL-1beta-induced translocation of p65 into the nucleus. IL-1beta treatment increased CCAAT/enhancer-binding protein (C/EBP)beta mRNA and protein levels including liver-enriched activating protein (LAP) and liver-enriched inhibitory protein (LIP), which was cycloheximide sensitive. C/EBPbeta isoforms bound a GCAAT-containing sequence in the proximal elastin promoter as determined by electrophoretic gel shift studies and confirmed by using specific anti-C/EBPbeta antibodies and by competition studies with oligonucleotides. Transient transfection of LIP expression vectors strongly decreased the transcriptional activity of the cotransfected elastin promoter and decreased levels of endogenous elastin mRNA. We demonstrated that IL-1beta-induced downregulation of elastin mRNA is dependent on NF-kappaB activation and C/EBPbeta expression. These results indicate that IL-1beta treatment activates NF-kappaB, which subsequently induces LIP expression and inhibition of elastin gene transcription.

Background: Administration of all-trans retinoic acid (ATRA) to adult Sprague-Dawley rats with emphysema induced by porcine pancreatic elastase (PPE) reversed the emphysema perhaps by inducing new alveolar formation. Objective: A study was conducted to determine whether ATRA can induce new alveolar septa and reverse the airspace enlargement caused in adult mice by PPE treatment. Methods: 48 FVB mice were divided into 6 groups. Three groups received 15 µg of PPE in 0.1 ml of 0.9% saline and 3 groups received 0.1 ml of saline, intratracheally. Starting at day 22, the mice received 12 daily intraperitoneal injections of cottonseed oil, with or without ATRA (12.5 µg or 50 µg). The mice were killed for study 1 day after the last injection. Results: Measurements of plasma and lung tissue ATRA levels showed statistically significant elevated levels after the 50-µg but not after the 12.5-µg doses of ATRA. In situ hybridization studies of elastin and α1(I) collagen mRNA expression in pulmonary parenchyma as well as in airways and blood vessels showed no effect of ATRA. Airspace size was determined by the mean linear intercept (Lm) method. The Lm of the groups receiving PPE and ATRA (46.2 ± 4.1 µm, mean ± SD) was not significantly different from the group receiving PPE and oil (47.8 ± 6.0 µm). The Lm for groups receiving saline and ATRA (40.6 ± 2.5 µm) were not significantly different from the group receiving saline and oil (41.0 ± 2.7 µm). Comparison of the fixed lung volume data and calculated internal surface area also showed no differences between the control and ATRA-treated groups. Conclusion: ATRA treatment does not affect airspace size or expression of elastin or α1(I) collagen mRNA in adult FVB mice with PPE-induced emphysema.

Paired pacing has been shown to potentiate contractile function of cardiac muscle, and it has been suggested that this may enhance contractile function of diaphragmatic muscle. The primary goal of this study was to study the effect of paired pacing on potentiation of contractile function of diaphragmatic muscle compared to atrial and ventricular myocardium. Diaphragmatic muscle was isolated from mouse and rat, and atrial and ventricular myocardium from dogs. Potentiation was induced by isolated extrastimuli (equal in duration and intensity to the pacing stimulus) and by repetitive extrastimuli (i.e. paired pacing) at a paced rate of 12, 30 and 60 beats/min. Baseline studies were performed while preparations were isometrically contracting at L(max) in oxygenated Krebs-Henseleit solution at 28 degrees C. Maximal force generation in response to a premature stimulus was determined at each rate by scanning the coupling interval between paced beats. Under baseline conditions, diaphragmatic muscle contracted faster than atrial and ventricular muscle. In all tissues, maximum potentiation (increase in force above baseline) was approximately 100% of baseline force, and peak potentiation occurred at shorter coupling intervals with increasing rates of stimulation. Single and paired pacing of diaphragm potentiated the contraction during which the extrastimuli were introduced, while in cardiac muscle, extrastimuli potentiated the contraction following the extrastimulus. The maximum potentiated response occurred when the extrastimulus was introduced prior to the development of peak force in diaphragmatic muscle. In contrast, in atrial and ventricular muscle, a single or paired premature stimulus potentiated the subsequent beat when delivered late during relaxation. In cardiac muscle, maximal potentiation gradually occurred following several repetitive stimuli. Following cessation of single and paired pacing, the beat following the potentiated response immediately returned to baseline in diaphragmatic muscle, while a gradual decline was evident over several subsequent beats in cardiac muscle. Increasing the bath temperature from 28 to 37 degrees C resulted in a leftward shift in the peak potentiated force vs. coupling interval curve without a decline in the magnitude of potentiated force in diaphragmatic muscle. In diaphragm muscle, exposure to ryanodine markedly decreased baseline force and maximal potentiation. We conclude that closely timed extrastimuli applied to diaphragmatic muscle can potentiate developed force in a given contraction, while in cardiac tissue a delayed stimulus potentiates the subsequent beat. These differences in contractile responsiveness are not due to differences in loading conditions, but appear to reflect intrinsic differences in calcium handling.

Transforming growth factor-β (TGF-β) and interleukin-4 (IL-4) have fibrogenic properties and induce extracellular matrix production in a variety of lung diseases. Connective tissue growth factor (CTGF) is a matrix signaling molecule stimulated by TGF-β that in part mediates α1(I) collagen mRNA expression. In these studies, the regulation of CTGF expression by IL-4 in human lung fibroblasts was examined. Following 6 h of stimulation with IL-4, basal CTGF mRNA levels were unchanged as assessed by Northern blot analysis. However, IL-4 attenuated the TGF-β-stimulated induction of CTGF mRNA expression by 50%. This effect was selective because IL-4 did not affect fibronectin or α1(I) collagen mRNA expression induced by TGF-β. Experiments employing the transcriptional inhibitor actinomycin D suggest that IL-4 did not affect the stability of the CTGF mRNA. Transient transfection assays with 3TP-Lux, a luciferase gene controlled by a TGF-β inducible promoter, and with a CTGF promoter construct indicate that IL-4 interfered with the TGF-β-induced transcriptional activation of the CTGF gene. J. Cell. Biochem. 85: 496–504, 2002. © 2002 Wiley-Liss, Inc.

A single intratracheal dose of porcine pancreatic elastase, which is cleared from the lung by 24 hours, was administered to wild-type, IL-1beta type 1 receptor-deficient, double TNF-alpha (type 1 and type 2) receptor-deficient, and combined TNF-alpha (type 1 receptor) plus IL-1beta receptor-deficient mice. The mean linear intercept (Lm) of saline-treated mice was 32(3) microm [mean(SE)]. For wild-type elastase-treated mice, Lm was 81(6) microm at 21 days versus 52(5) microm at 5 days after treatment, indicating that alveolar wall remodeling occurs long after the elastase injury. At 21 days, Lm values were 67(10), 62(3), and 39(5) microm in elastase-treated mice deficient in the IL-1beta receptor, double TNF-alpha receptors, and combined receptors, respectively. The level of apoptosis assessed by a terminal deoxynucleotidyl transferase-catalyzed in situ nick end-labeling assay was increased at 5 days after elastase treatment and was markedly and similarly attenuated in the IL-1beta, the double TNF-alpha, and the combined receptor-deficient mice. Our results indicate that inflammatory mediators exacerbate elastase-induced emphysema. We estimate that in the combined TNF-alpha + IL-1beta receptor-deficient mice, inflammation accounts for about 80% of the emphysema that develops after elastase treatment; decreased apoptosis of lung cells likely contributes to decreased severity of emphysema.

We investigated the effect of the dietary flavonoid apigenin on myofibroblast function. We report that in myofibroblasts treated with apigenin, proliferation and basal levels of alpha1(I) collagen and alpha-smooth muscle actin mRNAs were markedly reduced. Apigenin also attenuated the transforming growth factor-beta-stimulated increases of alpha1(I) collagen and alpha-smooth muscle actin mRNAs. Characterization of the apigenin effects indicates that apigenin reduces both the stability of the alpha1(I) collagen mRNA and the rate of transcription of the alpha1(I) collagen gene through a cycloheximide-sensitive pathway. Western blot analyses indicate that Akt activity is reduced in apigenin-treated myofibroblasts.

We investigated the role of phosphatidylinositol 3-kinase (PI3K) in the expression of α1(I) collagen mRNA. We report that the basal level of α1(I) collagen mRNA was reduced when PI3K activity was inhibited by either LY-294002 or wortmannin. These PI3K inhibitors also blocked increases of α1(I) collagen mRNA levels after the addition of transforming growth factor-β. The effect of PI3K inhibition was abolished by the removal of the inhibitor or by the addition of cycloheximide. Inhibition of PI3K activity decreased the stability of the α1(I) collagen mRNA with no change in the rate of transcription of the α1(I) collagen gene as assessed by Northern blotting with actinomycin D-treated fibroblasts and nuclear run-on assays. Expression of a truncated α1(I) collagen minigene driven by a cytomegalovirus promoter in murine fibroblasts was decreased by LY-294002 treatment. These data indicate that PI3K activation results in increased stabilization of α1(I) collagen mRNA. In vivo, the PI3K activity in fibroblasts may regulate basal levels of α1(I) collagen mRNA expression.

Background: Bleomycin (Bleo)-induced lung injury in mice serves as an animal model of pulmonary fibrosis. The pathogenesis of pulmonary fibrosis remains unclear, but it comprises both inflammatory and fibrotic components. The cytokine interferon (IFN)-α is produced by macrophages and may modulate both fibrogenesis and the determination of T lymphocyte phenotype in pulmonary fibrosis. Objective: To investigate the effect of two preparations of recombinant IFN-α (IFN-αA/D and IFN-α2a) on Bleo-induced lung injury in C57BL/6 mice. Methods: Mice were treated by a single intratracheal (IT) instillation of 0.06 mg of Bleo in 0.1 ml of saline or saline alone. One of two different IFN-α preparations, IFN-αA/D or IFN-α2a in saline, or saline alone were administered by daily intraperitoneal injections starting 1 day prior to IT instillation. The treatment groups were as follows: IT Bleo and intraperitoneal saline; IT Bleo and intraperitoneal IFN-α2a; IT Bleo and intraperitoneal IFN-αA/D; IT saline and intraperitoneal IFN-αA/D or IFN-α2a; IT saline and intraperitoneal saline. The animals were sacrificed 14 days after IT instillation. Lung injury was evaluated by total and differential cell count in bronchoalveolar lavage (BAL) fluid, by a semiquantitative morphological index of lung injury and a quantitative image analysis of cellularity and fibrosis fraction and by biochemical analysis of lung hydroxyproline content. Results: In Bleo-treated mice, IFN-α2a treatment caused a significant rise in BAL lymphocytes and in cellularity and fibrosis fractions in lung tissue. In contrast, IFN-αA/D treatment had no effect on Bleo-induced lung injury. Conclusion: IFN-α may enhance Bleo-induced lung injury but this effect varies with different IFN preparations.

Since transforming growth factor beta (TGF-beta) is presumed to play a role in lung fibrosis, we evaluated the effect of suramin (Sur), a substance with an anti-TGF-beta effect, in vivo on bleomycin (Bleo)-induced pulmonary injury in mice and in vitro on human lung fibroblasts. Four groups of C57BL/6 mice each received one of four treatments: (1) intratracheal (i.t.) instillation of Bleo and intraperitoneal (i.p.) injections of Sur, every other day, starting one day before i.t. instillation of Bleo (Bleo-Sur); (2) i.t. Bleo and i.p. injections of saline (Bleo-Sal); (3) i.t. saline and i.p. Sur (Sal-Sur); and (4) i.t. and i.p. saline (Sal-Sal). Animals were sacrificed 14 days after i.t. treatment. Lung injury was evaluated by analysis of bronchoalveolar lavage (BAL) fluid, histologically by the semiquantitative morphological index, and biochemically by analysis of lung hydroxyproline content. In vitro, Sur did not affect TGF-beta induced increase of alpha1 (I) collagen mRNA in human lung fibroblasts. In vivo treatment of mice with Sur did not affect Bleo-induced lung injury. These results indicate that despite its potential anti TGF-beta and lymphocytotoxic effects, Sur is not a therapeutic candidate drug for rescue of lung fibrosis.

P148 The arterial wall in hypertension is characterized by thickening of the media, in part due to increased deposition of connective tissue. Autocrine and paracrine factors may participate in this process; including products of the kallikrein-kinin system. We evaluated early signal transduction events and effects on collagen formation in B 1 -stimulated human myofibroblast cells (IMR-90). We measured cytosolic calcium (Ca cyt ) levels in cells loaded with FURA-2AM. Gene expression of connective tissue growth factor (CTGF) and α1(I) collagen was determined by estimating mRNA levels using Northern analysis of B 1 stimulated cells. Activation of the B 1 receptor with des-arg 10 -kallidin stimulated a three-fold increase in CTGF mRNA by increasing its stability. Furthermore, B 1 receptor activation caused an increase in α1(I) collagen mRNA and a four-fold increase in type I collagen synthesis in these cells; events not observed in B 2 receptor-stimulated cells. Activation of the B 1 receptor stimulated a dose dependent rise in Ca cyt (EC 50 =1.9nM) which was completely inhibited by des-arg 10 -[leu 9 ]-kallidin (100nM), a B 1 receptor antagonist. Isosmotic replacement of extracellular Na + with N -methyl,D-glucamine blocked > 90% of the B 1 stimulated rise in Ca cyt . A similar effect was observed when Ca 2+ was removed from the extracellular media, suggesting a role for the plasma membrane Na + /Ca 2+ exchanger (NCX). To further define a role for the NCX on CTGF formation we used dichlorobenzamil (DCB) and KB-R7943, two specific NCX inhibitors. DCB completely blocked the activation of B 1 receptor induced increase in CTGF mRNA stability while not affecting basal CTGF mRNA levels. In contrast, preincubation with EIPA, an amiloride analog, did not affect basal or stimulated CTGF mRNA levels. Furthermore, 60μM KB-R7943 blocked the B 1 stimulated rise in Ca cyt . NCX isoform 1 was identified in these cells using RT-PCR and immuno-detection. Thus, B 1 receptor stimulation increases fibrogenesis through a mechanism that involves modulation of cation metabolism via reverse-mode activation of NCX.

Hypoxia and amino acid deprivation downregulate expression of extracellular matrix genes in lung fibroblasts. We examined the effect of hypoxia on amino acid uptake and protein formation in human lung fibroblasts. Low O2tension (0% O2) suppressed incorporation of [3H]proline into type I collagen without affecting [35S]methionine labeling of other proteins. Initial decreases in intracellular [3H]proline incorporation occurred after 2 h of exposure to 0% O2, with maximal suppression of intracellular [3H]proline levels at 6 h of treatment. Hypoxia significantly inhibited the uptake of radiolabeled proline, 2-aminoisobutyric acid (AIB), and 2-(methylamino)isobutyric acid (methyl-AIB) while inducing minor decreases in leucine transport. Neither cycloheximide nor indomethacin abrogated hypoxia-related suppression of methyl-AIB uptake. Efflux studies demonstrated that hypoxia inhibited methyl-AIB transport in a bidirectional fashion. The downregulation of amino acid transport was not due to a toxic effect; function recovered on return to standard O2conditions. Kinetic analysis of AIB transport revealed a 10-fold increase in Kmaccompanied by a small increase in maximal transport velocity among cells exposed to 0% O2. These data indicate that low O2tension regulates the system A transporter by decreasing transporter substrate affinity.

Fibrotic lung diseases are characterized by excessive deposition of type I collagen. Amino acid availability regulates type I collagen mRNA levels in quiescent human lung fibroblasts. In these studies, the effect of amino acid availability on type I collagen protein accumulation in quiescent human lung fibroblasts was examined. Following amino acid deprivation, alpha1(I) procollagen protein levels were not detected by Western blot analysis in either the intracellular or the extracellular compartments. Fibronectin levels and total protein levels were not affected. Amino acid deprivation resulted in a more pronounced decrease in alpha1(I) procollagen protein levels than in alpha1(I) procollagen mRNA levels, suggesting that post-transcriptional events were responsible for the further decrease inalpha1(I) procollagen protein levels. The addition of transforming growth factor-beta to amino acid deprived fibroblasts increased alpha1(I) procollagen mRNA levels without affecting alpha1(I) procollagen protein levels, confirming a post-transcriptional site for regulatory control by amino acid deprivation. In the absence of ascorbic acid, alpha1(I) procollagen protein levels increased in amino acid deprived fibroblasts, but alpha1(I) procollagen mRNA levels were not affected. The absence of ascorbic acid likely resulted in the accumulation of nonhelical procollagen in the endoplasmic reticulum, indicating that translational mechanisms for alpha1(I) procollagen were intact. The addition of chloroquine, an inhibitor of lysosomal degradation of proteins, increased alpha1(I) procollagen protein levels in amino acid deprived fibroblasts. These data suggest that following amino acid deprivation of quiescent fibroblasts, newly synthesized type I collagen was degraded intracellularly, primarily by a process that involved lysosomal proteinases.

Elastolytic lung injury disrupts cell barriers, flooding alveoli and producing regional hypoxia. Abnormal O2tensions may alter repair of damaged elastin fibers. To determine the effect of hypoxia on extravascular elastin formation, we isolated rat lung fibroblasts and cultured them under a variety of O2conditions. Hypoxia downregulated tropoelastin mRNA in a dose- and time-related fashion while upregulating glyceraldehyde-3-phosphate dehydrogenase mRNA levels. The changes in tropoelastin gene expression were not due to cell toxicity as measured by chromium release and cell proliferation studies. Neither cycloheximide nor actinomycin D abrogated this effect. Hypoxia induced early decreases in tropoelastin mRNA stability; minor suppression of gene transcription occurred later. When returned to 21% O2, tropoelastin mRNA recovered to control levels in part by upregulating tropoelastin gene transcription. Taken together, these data indicate that hypoxia regulates tropoelastin gene expression and may alter repair of acutely injured lung.

Background: The role of lymphocytes and their subpopulations in lung fibrosis is as yet unclear. Objective: To define the role of immunomodulation in bleomycin-induced inflammatory fibrotic lung injury, by testing the effect of two known Th1 inhibitors: linomide and pentoxifylline. Methods: C57BL/6 mice were treated by a single intratracheal instillation of 0.06 mg bleomycin in 0.01 ml saline or saline alone. Treatment groups included: (1) intratracheal bleomycin and daily treatment with linomide or pentoxifylline; (2) intratracheal bleomycin and daily water; (3) intratracheal saline and daily linomide or pentoxifylline; (4) intratracheal saline and daily water. Linomide and pentoxifylline were available per os in the drinking water from 1 day prior to intratracheal instillation. Animals were studied 14 days after intratracheal instillation. Lung injury was evaluated by total and differential cell count in bronchoalveolar lavage fluid, by a semiquantitative morphological index of lung injury and a quantitative image analysis of cellularity, fibrosis fraction and alveolar wall area fraction, and by biochemical analysis of lung hydroxyproline content. Results: Linomide or pentoxifylline did not cause any lung injury in saline-treated control mice. Overt signs of lung injury were apparent in bleomycin-treated mice. These changes were not affected by daily treatment with linomide or pentoxifylline, which were given in the highest tolerable dose. Conclusion: This study does not support the use of linomide or pentoxifylline to prevent or ameliorate lung fibrosis and may suggest that drug-induced differentiation of T lymphocytes into Th1/th2 subpopulations does not affect the evolution of bleomycin-induced lung injury.

We have evaluated the effect of intraperitoneal (I.P.) injection of human recombinant interferon-2alpha (IFN-alpha) on Bleomycin-induced pulmonary injury in hamsters. Pulmonary injury was induced by a single intratracheal (I.T.) instillation of Bleomycin (Bleo). Six groups of male Syrian hamsters were treated as follows: 1) I.T. Bleo and daily I.P. injections of low-dose interferon-alpha (2 x 10(4) U), 2) I.T. Bleo and daily I.P. injections of high-dose interferon-alpha (10(5) U), 3) I.T. Bleo and I.P. injections of saline, 4) I.T. saline and I.P. low-dose IFN-alpha, 5) I.T. saline and I.P. high-dose IFN-alpha, 6) I.T. saline and I.P. saline. Animals were sacrificed 28 days after I.T. treatment. Lung injury was evaluated histologically and biochemically. Treatment of hamsters with low-dose but not high-dose IFN-alpha significantly augmented the Bleo-induced lung injury, as determined by a semiquantitative morphological index. Lung hydroxyproline measurements were highest in Bleo-low-dose-IFN-alpha followed by Bleo-high-dose-IFN-alpha and Bleo-Sal as compared to Sal-Sal and Sal-IFN-alpha controls. These results suggest that IFN-alpha augments Bleo-induced lung injury but that this effect is complex and does not follow a simple-dose-response pattern.

The steady state levels of alpha1(I) collagen mRNA are decreased by retinoic acid and prostaglandin E2. These effector substances decrease the uptake of A system amino acids. We examined the effect of amino acid deprivation on the steady state levels of alpha1(I) collagen in human lung fibroblasts. Maintenance of fibroblasts in amino acid-free medium decreased alpha1(I) collagen mRNA levels by 29% at 24 h and 78% at 72 h. Frequent refeeding of cultures with amino acid-free medium resulted in more rapid decreases in intracellular amino acids and in alpha1(I) collagen mRNA levels. The decrease in alpha1(I) collagen mRNA levels was mediated by decreases in mRNA stability as assessed by a half-life determination using actinomycin D and by decreases in the rate of transcription as assessed by nuclear run-on assay. Treatment of fibroblasts with medium containing amino acids resulted in rapid restoration of alpha1(I) collagen mRNA levels. This increase in alpha1(I) collagen mRNA expression required protein synthesis as determined by cycloheximide sensitivity and was inhibited by prostaglandin E2. These data indicate that alpha1(I) collagen mRNA levels are sensitive to alterations in the amount of intracellular amino acids and suggest a potential mechanism whereby alpha1(I) collagen accumulation may be regulated independent of inflammatory mediators following lung injury.

Transgenic mice containing a rat collagen alpha 1 (I) promoter (3.6 kilobases) fused to the reporter gene chloramphenicol acetyl transferase (CAT) express the reporter gene parallel to endogenous gene in most connective tissues other than vascular tissue [Pavlin et al. (1992): J Cell Biol 116:227-236; Bedalov et al. (1994): J Biol Chem 269:4903-4909]. We have challenged transgenic mice with subcutaneous injections of transforming growth factor-beta (TGF-beta) or intratracheal instillation of bleomycin. In situ hybridization studies of skin revealed increased CAT expression in the papillary dermis of TGF-beta treated animals. In contrast, alpha 1 (I) collagen mRNA was expressed throughout the dermis including granulation tissue and reticular dermis. Therefore, the transgenic promoter responds to TGF-beta in a subset of dermal fibroblasts. Endotracheal instillation of bleomycin induces lung fibrosis which is thought to be mediated in part by TGF-beta. CAT gene expression in lungs was increased 6-8-fold at 2 weeks post bleomycin treatment. In situ hybridization studies revealed focal areas of cells expressing both CAT and collagen genes in the interstitium. However, most regions, especially around airways, contained a subset of cells expressing the endogenous gene with little or no CAT expression as judged by in situ hybridization. These cells could be myofibroblasts that require additional cis-acting elements to activate alpha 1 (I) collagen gene expression similar to smooth muscle cells.

Prostaglandin E2, transforming growth factor-beta, and interleukin-1 beta variably regulate the expression of cyclooxygenase 1, cyclooxygenase 2, and lysyl oxidase in IMR90, human embryo lung fibroblasts. Prostaglandin E2 at 100 nM upregulates cyclooxygenase 1 mRNA by approximately three-fold while it downregulates lysyl oxidase mRNA levels. Notably, prostaglandin E2 suppresses the enhancing effect of TGF-beta on basal levels of lysyl oxidase mRNA. These changes in steady state mRNA levels reflect transcriptional level control, at least in part. Corresponding changes are seen in the protein levels of lysyl oxidase, cyclooxygenase 1 and cyclooxygenase 2 and catalytic activities of these enzymes, including net prostaglandin E2 synthesis. Cyclooxygenase 2 mRNA(t1/2, 30 min) is considerably less stable than that of cyclooxygenase 1 (t1/2, 4 h) while lysyl oxidase mRNA is unusually stable (t1/2 > 14 h). Taken together with the differing kinetics with which these genes respond to perturbation by these cytokines, the present results suggest a coordinated, autocrine-like mechanism of regulation of cyclooxygenase 1 and cyclooxygenase 2 and further point to the potential of their metabolic product, prostaglandin E2, to suppress the expression of lysyl oxidase in the inflammatory response to injury.

The effects and interaction of transforming growth factor-beta (TGF-beta) and insulin on collagen production in human fetal lung fibroblasts was examined. Fibroblasts were labeled with [3H]proline and collagen production was analyzed by polyacrylamide gel electrophoresis. The addition of insulin (2 micrograms/ml) increased collagen production 5 fold and TGF-beta (5 ng/ml) increased collagen production 6-fold. The combination of TGF-beta and insulin further increased type I collagen production (12 fold). We found that TGF-beta increased pro-alpha 1 (I) collagen mRNA levels 2-3 fold, insulin increased mRNA levels by less than 2 fold, and the combination stimulated a 3-4 fold increase. In a nuclear run-on assay, we found a 1.7 fold increase in the rate of transcription for the pro-alpha 1 (I) collagen gene in insulin-treated cultures and a 2-fold increase in TGF-treated cultures. In fibroblasts transfected with a plasmid containing 2.4 kb of the 5' flanking sequences of the human pro-alpha 1 (I) collagen gene, TGF-beta stimulated a 2.8 fold increase in promoter activity. In contrast, the addition of insulin stimulated a small increase (less than 2 fold) in the pro-alpha 1 (I) collagen promoter activity when administered alone or in combination with TGF-beta. Insulin prolonged the half-life of pro-alpha 1 (I) collagen mRNA from 9.1 h to 14.3 h as assessed by treatment with actinomycin D. The insulin-induced increase in pro-alpha 1 (I) collagen mRNA was blocked by the presence of cycloheximide indicating a requirement for new protein synthesis. These results show that the combination of TGF-beta and insulin stimulate large increases in type I collagen formation by acting at different sites in the collagen biosynthetic pathway.

This study evaluated the effect of cyclosporin-A (CyA), a potent immunosuppressive drug, on Bleomycin (Bleo)-induced pulmonary inflammation in hamsters. Pulmonary injury was induced by a single intratracheal (i.t.) instillation of Bleo. Four groups of 10 male Syrian hamsters each received one of four treatments: (1) i.t. Bleo and daily intraperitoneal (i.p.) injections of CyA starting 1 day before i.t. instillation of Bleo (Bleo-CyA); (2) i.t. Bleo and i.p. injections of saline (Bleo-Sal); (3) i.t. saline and i.p. CyA (Sal-CyA); (4) i.t. saline and i.p. saline (Sal-Sal). Animals were sacrificed 14 days after i.t. treatment. Lung injury was evaluated histologically, biochemically, and by analysis of bronchoalveolar lavage (BAL) fluid. Treatment of hamsters with CyA significantly ameliorated the Bleo-induced lung injury, as determined by a semiquantitative morphological index that assesses the severity and extent of the injury on a scale of 0-3. Lung hydroxyproline measurements were lower in Bleo-CyA compared to Bleo-Sal, comparable to Sal-Sal and Sal-CyA controls. The percentage of neutrophils, eosinophils, and lymphocytes in BAL fluid was higher in Bleo-Sal and Bleo-CyA animals when compared with control Sal-CyA or Sal-Sal animals. A further increase in percentage of eosinophils was observed in Bleo-CyA compared with Bleo-Sal animals (13.3 +/- 6.6% [mean +/- SE] and 3.7 +/- 2.1%, respectively, p = .0007). BAL fluid protein content was higher in Bleo-Sal compared to Sal-Sal animals, but BAL fluid protein content from Bleo-CyA was not significantly different from that of Bleo-Sal animals. These results indicate that CyA ameliorates the Bleo-induced inflammation but does not prevent leakage of plasma protein or cells into the airspaces. The increased eosinophil numbers in Bleo-CyA-treated hamsters suggests enhanced production of interleukin-4 and -5.

Fibrotic process affecting the lung and other tissues is characterized by stimulation of fibroblast proliferation and connective tissue deposition. Conventional therapy consisting of glucocorticoids or cytotoxic agents is usually ineffective in blocking progression of disease. Potential new therapies have emerged from the use of animal models of pulmonary fibrosis and recent advances in the cellular and molecular biology of inflammatory reactions. Such therapies involve the use of substances directed against the action of certain growth factors, cytokines, or oxidants that are elaborated during the fibrotic reaction. In this article, we review possible therapeutic applications of these advances.

A prominent feature of fibrotic tissue in general and of lungs in particular is fibroblast proliferation and accumulation. In patients overcoming fibrosis, apoptosis limits this excessive cell growth. We have previously shown resistance to Fas-induced apoptosis of primary lung fibroblasts from mice with bleomycin-induced lung fibrosis, their escape from immune surveillance, and continued accumulation in spite of overexpression of the Fas death receptor. Cellular FLICE-like inhibitory protein (c-FLIP) is a regulator of cell death receptor–induced apoptosis in many cell types. We aimed to determine c-FLIP levels in myofibroblasts from fibrotic lungs and to directly assess c-FLIP’s role in apoptosis and proliferation of primary lung myofibroblasts. c-FLIP levels were determined by apoptosis gene array, flow cytometry, Western blot, and immunofluorescence before and after down-regulation with a specific small interfering RNA. Apoptosis was assessed by caspase cleavage in Western blot and by Annexin V affinity labeling after FACS and tissue immunofluorescence. Proliferation was assessed by BrdU uptake, also using FACS and immunofluorescence. We show that myofibroblasts from lungs of humans with idiopathic pulmonary fibrosis and from bleomycin-treated versus normal saline-treated mice up-regulate c-FLIP levels. Using the animal model, we show that fibrotic lung myofibroblasts divert Fas signaling from apoptosis to proliferation and that this requires signaling by TNF receptor–associated factor (TRAF) and NF-κB. c-FLIP down-regulation reverses the effect of Fas activation, causing increased apoptosis, decreased proliferation, and diminished recruitment of TRAF to the DISC complex. This indicates that c-FLIP is essential for myofibroblast accumulation and may serve as a potential target to manipulate tissue fibrosis.

The regulation of lysyl oxidase produced by cultured, lipid-enriched, neonatal rat lung fibroblasts was explored. The presence of 40 pM of transforming growth factor-beta 1 (TGF-beta 1) in overnight cultures increased levels of enzyme secreted into the medium by 1.6-fold while steady-state levels of lysyl oxidase mRNA increased similarly. In contrast, incubation of these cultures with 100 nM of prostaglandin E2 (PGE2) reduced enzyme activity levels by 40 to 50% although steady-state mRNA was not changed. Consistent with the effect of PGE2, the presence of indomethacin stimulated levels of secreted enzyme activity. When present in cultures simultaneously with TGF-beta 1, PGE2 prevented the stimulation beyond control levels seen with TGF-beta 1 alone. Densitometry of protein bands immunoprecipitated by antibody to lysyl oxidase indicated that the degree of conversion of the 50 kD proenzyme to the 29 kD enzyme was not significantly altered by TGF-beta 1 or PGE2. However, the net accumulation of all forms of lysyl oxidase protein was increased by TGF-beta 1 and decreased by PGE2. These results indicate that TGF-beta 1 and specific prostaglandin(s) exert opposing effects on the expression of lysyl oxidase in these lung fibroblasts.

The type II TGF-β receptor is a serine/threonine kinase whose expression is essential for the action of TGF-β. In this paper, we describe the cloning and expression of the human type II TGF-β promoter. DNA sequence analysis indicates that the region near the transcription initiation site lacks a TATA and CAAT box but contains Sp l binding sites. A similar promoter type has been identified in the 5′ flanking regions of genes that code for certain other growth factor receptors. Transfection of the promoter (888 bp fragment) mediated transcriptional activity in bovine vascular smooth muscle cells and human lung fibroblasts.

The effect of retinoic acid (RA) on the uptake and utilization of extracellular amino acids by fetal lung fibroblasts was examined. RA decreased the incorporation of [3H]proline into collagen and other proteins. The effect was maximal at a RA concentration of 10(-5) M; smaller decreases were observed at a RA concentration of 10(-6) M. This decrease in collagen formation was associated with a large decrease in intracellular [3H] proline. The decrease in intracellular [3H]proline was first observed at 2 h following the addition of RA to cell cultures. Transport studies employing radiolabeled amino acids revealed that RA decreased the uptake of proline, 2-aminoisobutyric acid, and 2-(methylamino)isobutyric acid but not leucine or methionine. Kinetic analysis of 2-aminoisobutyric acid uptake indicated that this effect was mediated primarily by an increase in apparent Km, with a lesser decrease in Vmax, RA-induced inhibition of proline uptake was not abolished by the presence of cycloheximide nor by pretreatment with indomethacin. Na+,K(+)-ATPase activity was not affected by RA treatment. These results suggest that RA modulates protein production in fibroblasts by altering the function of the Na(+)-dependent A transport system for amino acid uptake.

The effects of shoe wear, custom-made inserts, patellar tendon-bearing (PTB) braces, and extra-padded PTB braces on load transmission to neuroarthropathic (Charcot) feet of six diabetic patients were assessed. A PTB brace with a free ankle and an extradepth shoe without external modifications was used. Four distinct anatomical regions were evaluated by an in-shoe technique measuring vertical force. The mean peak force transmitted to the entire foot was higher in the affected than in the unaffected extremity barefoot and shod. The mean peak forces under the midfoot were higher for the affected than for the unaffected extremity for all tested circumstances. In the affected foot, use of the standard PTB brace reduced mean peak force to the entire foot by 15%. Adding extra padding to the brace decreased the mean peak force 32%. The effect of padding on vertical load transmission was greatest for patients who had worn the brace the longest. For the patients who had worn it longer than average, the addition of padding decreased the mean peak force to the entire foot by 19%, to the hindfoot by 37%, and to the midfoot by 20%. Clinical Relevance: In this preliminary study, we found that a properly fitted PTB brace can reduce load transmission to the Charcot foot. Specifically, load transmission was reduced to the hindfoot, but not to the midfoot or forefoot. Based on these results, we cannot recommend its use to reduce vertical force transmission to the Charcot midfoot or forefoot. Long-term PTB brace use, especially in the limited weightbearing patient, should be regularly adjusted to ensure adequate brace fit.

We have located a cis-acting element (alpha 1-TAE) within the promoter sequences of the rat collagen alpha 1(I) gene (COL1A1) 1600 bases upstream of the transcription start site which mediates transcriptional activation by transforming growth factor beta (TGF-beta). The functional significance of this region was established by (1) deletion analysis of the alpha 1(I) promoter cloned upstream of the bacterial chloramphenicol acetyltransferase (CAT) gene and (2) by co-transfection of promoter constructs with double-stranded oligonucleotides. DNA-mobility-shift assays with radiolabelled alpha 1-TAE demonstrated increased nuclear binding activity after TGF-beta stimulation. Oligonucleotides encoding the alpha 1-TAE, additional upstream regions within the alpha 1(I) promoter, as well as consensus nuclear-factor-1 (NF-1) sequences, competed with the alpha 1-TAE sequence. The two collagen type I genes are stimulated by TGF-beta through different regions of their promoters.

Type I collagen is a major structural protein in the lung, the accumulation of which is stimulated during certain inflammatory reactions in the lung. Accumulating evidence suggests that type I collagen formation parallels changes in steady-state mRNA levels. Specific inflammatory substances modulate transcription of collagen genes and stabilization of collagen mRNA in vitro. However, the precise role for any particular mediator during fibrotic processes is difficult to identify because of the complex nature of the inflammatory reaction and potential interaction among mediators. The signal transduction mechanisms that regulate collagen accumulation remain to be defined. This review focuses on the regulation of collagen accumulation in the lung by specific inflammatory substances.

We investigated the effect of medium conditioned by bovine aortic endothelial cells on collagen accumulation and total protein formation by human embryonic fibroblasts or bovine smooth muscle cells in cultures. The conditioned medium at a 1:10 dilution induced a twofold increase in collagen and total protein accumulation in fibroblast cultures. At low concentration (1:50 dilution), the conditioned medium stimulated collagen accumulation preferentially; at high concentration (1:10 dilution), overall protein synthesis also was increased. The increase in type I collagen accumulation was associated with an increase in the steady-state level of alpha 1 (I) mRNA for collagen. The conditioned medium increased the production of types I and III collagen without affecting the proportion of collagen types in both fibroblast and smooth muscle cell cultures. Partial purification of the endothelial cell-derived factor disclosed it to be a heat-stable protein with an apparent molecular weight of 8-10 kDa. The stimulation of protein formation by this substance was not inhibited by antibodies against transforming growth factor-beta or the insulinlike growth factor I receptor. The partially purified factor stimulated protein production without affecting fibroblast proliferation. This endothelial cell-derived protein may play a role in the remodeling of vascular connective tissue by stimulating collagen synthesis.

The effect of recombinant interleukin-1 beta (rIL-1 beta) on elastin accumulation by lipid-laden interstitial cells (LIC) derived from neonatal rat lung was examined. The LIC, a fibroblast subtype, synthesized large amounts of elastin which was deposited into the extracellular matrix. This elastin was alkali-resistant and had an amino acid composition typical of adult rat elastin. Treatment of lipid-laden interstitial cell cultures with rIL-1 beta at 100 pg/ml caused a dramatic decrease in elastin accumulation as assessed by hot alkali treatment and transmission electron micrographs of the cell cultures. Tropoelastin formation was selectively decreased by rIL-1 beta relative to other proteins. Steady state levels of elastin mRNA were slightly decreased by rIL-1 beta at 5 pg/ml and markedly decreased by rIL-1 beta at 50 pg/ml or greater. The addition of indomethacin had no effect on rIL-1 beta-induced decreases in elastin mRNA levels. Inhibiting protein synthesis with cycloheximide blocked the effect of rIL-1 beta on elastin mRNA levels. The level of alpha 1(I) collagen mRNA was decreased by rIL-1 beta, but only at concentrations higher than that needed to induce a decrease in elastin mRNA. These data indicate that rIL-1 beta decreased steady state levels for elastin mRNA and elastin accumulation and can selectively regulate the accumulation of elastin and collagen.

The effect of phorbol 12-myristate 13-acetate (PMA) on collagen accumulation by human embryonic lung fibroblasts was determined. PMA (10 nM) dramatically inhibited collagen formation in cultures that were unstimulated or stimulated with transforming growth factor-beta (TGF-beta). Collagen accumulation was decreased by 50% in unstimulated cultures and by 80% in TGF-beta-treated cultures. This inhibition was associated with a marked decrease in steady-state levels for alpha 1(I) collagen mRNA and decreases in alpha 1(I) gene transcription as determined by nuclear run-off assays. The PMA-mediated decrease in alpha 1(I) collagen mRNA was not affected by the addition of cycloheximide or indomethacin. Prolonged treatment with PMA (100 nM) resulted in down-regulation of protein kinase C (PKC) activity to less than 3% of untreated cultures. When PKC activity was down-regulated, treatment with PMA did not block TGF-beta-stimulated collagen formation, and prostaglandin E2-induced inhibition of protein formation was still evident. These results suggests that PKC activity modulates the level of transcription of collagen genes and collagen accumulation in lung fibroblast cultures.