Potential therapeutic initiatives for fibrogenic lung diseases

Prolidase could act as a diagnosis and treatment mediator in lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease with unknown etiology and pathogenesis. With high mortality risks, most of the IPF cases emerged after a damage of alveolar epithelium, where this situation stimulates the over expression of matrix components. Inflammatory process observed as a reaction to emerged damage. Prolidase as an iminodipeptidase significantly increased during the development of fibrosis. The aim of this study is to measure prolidase activity as a marker of treatment and diagnosis in an experimental lung fibrosis animal model. Thirty male Wistar rats randomly divided into three experimental groups, with ten rats in each group. Group 1, control group; group 2, bleomycin (BLM)-induced lung fibrosis group, and group 3, BLM-induced lung fibrosis treated with palosuran (urotensin-II receptor antagonist). For histopathology, the middle lobes of right lungs were embedded in paraffin, followed by fixation in 10 % buffered formalin, and evaluation of IPF was performed using the Ashcroft scoring method. Prolidase activity was determined by a photometric method based on the measurement of proline levels produced by prolidase. The fibrosis scores and the prolidase activity were significantly enhanced by BLM stimulation. The BLM + palosuran treatment decreased prolidase activity in group 3. There was a positive correlation between prolidase activity and fibrosis scores. Palosuran seems to be effective in the treatment of lung fibrosis, and prolidase activity can be used for the diagnosis and/or for management of the treatment. However, further clinical and experimental studies with animals and/or patients are needed to verify these conclusions.

Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic condition of unknown etiology with an unfavorable outcome from progressively deteriorating respiratory function, leading ultimately to death from respiratory failure. It is characterized by sequential acute lung injury resulting in progressive fixed tissue fibrosis, architectural distortion and loss of function. An excess of profibrotic cytokines and/or a deficiency in antifibrotic cytokines have been implicated in the pathological process as has excessive oxidation. IPF is distinguished from other forms of diffuse pulmonary fibrosis by the presence of the specific histological pattern of usual interstitial pneumonitis. Oral corticosteroids are the usual treatment, but objective response rates are poor and good quality studies do not exist. Other therapies either alone or in combination with corticosteroids are widely used, including azathioprine, colchicine, cyclophosphamide and penicillamine. There is a paucity of good quality information regarding the effectiveness of most noncorticosteroid immunosuppressive agents. Older studies of lesser methodological quality have shown benefits from these drugs, generally when added to corticosteroids. Many were retrospective reviews or uncontrolled, nonrandomized, open-label, prospective studies and often included other histological patterns of disease which are now thought to respond better to immunosuppressive agents. The results of intervention with colchicine and azathioprine have been disappointing when assessed by good quality trials using modern diagnostic criteria. Modern high quality studies are lacking for several agents, notably cyclophosphamide and penicillamine. The older agents may yet prove to be effective but further good quality trials will be necessary to assess these agents adequately. Other new anti-inflammatory, antioxidant, antifibrotic or anticytokine compounds are largely untried or unreported. One trial using interferon-gamma-1b showed a significant improvement in pulmonary function but there are concerns regarding the generalizability of this study. Pirfenidone, cyclosporine and acetylcysteine may also prove to be of benefit but current studies are of insufficient quality to allow for any conclusions to be drawn. Currently there is no good evidence to support the routine use of oral corticosteroids, azathioprine, cyclophosphamide, penicillamine, colchicine, cyclosporine or any other immunosuppressive, antifibrotic or immunomodulatory agent in the management of IPF. Interferon, pirfenidone and other new agents may be of benefit but further studies are required. Any recommendations for treatment must therefore be made on an individual and empiric basis. As some other forms of pulmonary fibrosis may respond better to immunosuppressive agents, it remains important to make an accurate diagnosis, by open lung biopsy if necessary.

Fasudil, a Rho-kinase inhibitor, attenuates bleomycin-induced pulmonary fibrosis in mice

The mechanisms underlying the pathogenesis of idiopathic pulmonary fibrosis (IPF) involve multiple pathways, such as inflammation, epithelial mesenchymal transition, coagulation, oxidative stress, and developmental processes. The small GTPase, RhoA, and its target protein, Rho-kinase (ROCK), may interact with other signaling pathways known to contribute to pulmonary fibrosis. This study aimed to determine the beneficial effects and mechanisms of fasudil, a selective ROCK inhibitor, on bleomycin-induced pulmonary fibrosis in mice. Our results showed that the Aschcroft score and hydroxyproline content of the bleomycin-treated mouse lung decreased in response to fasudil treatment. The number of infiltrated inflammatory cells in the bronchoalveolar lavage fluid (BALF) was attenuated by fasudil. In addition, fasudil reduced the production of transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), alpha-smooth muscle actin (α-SMA), and plasminogen activator inhibitor-1 (PAI-1) mRNA and protein expression in bleomycin-induced pulmonary fibrosis. These findings suggest that fasudil may be a potential therapeutic candidate for the treatment of pulmonary fibrosis.

Glycogen synthase kinase-3beta inhibition attenuates the development of bleomycin-induced lung injury

Glycogen synthase kinase-3 (GSK-3) is an ubiquitous serine-threonine protein kinase that participates in a multitude of cellular processes and has recently been implicated in the pathophysiology of a number of diseases. The aim of this study is to investigate the effects of TDZD-8, a potent and selective GSK-3beta inhibitor, on the development of lung injury caused by administration of bleomycin (BLM). Mice subjected to intra-tracheal administration of BLM developed significant lung injury characterized by marked neutrophil infiltration and tissue edema. An increase in immunoreactivity to nitrotyrosine, iNOS, TNF-alpha and IL-1beta was also observed in the lungs of BLM-treated mice. In contrast, administration of BLM-treated mice with TDZD-8 (1 mg/kg daily) significantly reduced (I) the degree of lung injury, (II) the increase in staining (immunohistochemistry) for myeloperoxidase (MPO), nitrotyrosine, iNOS, TNF-alpha and IL-1beta and (III) the degree of apoptosis, as evaluated by Bax and Bcl-2 immunoreactivity and TUNEL staining. Taken together, these results clearly demonstrate treatment with the GSK-3beta inhibitor TDZD-8 reduces the development of lung injury and inflammation induced by BLM in mice.

Genetic and pharmacological inhibition of GITR‐GITRL interaction reduces chronic lung injury induced by bleomycin instillation

We have recently identified a gene named GITR (glucocorticoid-induced TNF receptor related gene). GITR is expressed in different cells and tissues such as T lymphocytes from thymus and spleen and lymph nodes, and also in the lung. GITR ligand (GITRL) is expressed in several cells including macrophages, B cells, dendritic cells, and endothelial cells. In the present study, by comparing the responses in wild-type (WT) mice (GITR+/+) and GITR-deficient mice (GITR-/-), we investigated the role played by GITR-GITRL interaction in the development of chronic lung injury caused by bleomycin instillation. When compared with bleomycin-treated GITR+/+ mice, bleomycin-treated GITR-/- mice exhibited a reduced degree of i) lung infiltration with polymorphonuclear neutrophils (MPO activity); ii) edema formation; iii) histological evidence of lung injury; iv) TNF-alpha and interleukin (IL)-1beta production; v) nitrotyrosine formation; and vi) NF-kappaB activation. The cotreatment of GITR+/+ mice with Fc-GITR fusion protein (6.25 microg/mouse) also significantly attenuated all of the above indicators of lung damage and inflammation. Our results clearly demonstrate that GITR-GITRL interaction plays an important role in the chronic lung injury induced by bleomycin in the mice.

ROLE OF ENDOGENOUS AND EXOGENOUS LIGANDS FOR THE PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR α IN THE DEVELOPMENT OF BLEOMYCIN-INDUCED LUNG INJURY

The peroxisome proliferator-activated receptor-alpha (PPAR-alpha) is a member of the nuclear receptor superfamily of ligand-dependent transcription factors related to retinoid, steroid, and thyroid hormone receptors. The aim of the present study was to examine the effects of endogenous and exogenous the PPAR-alpha ligand on the development of lung injury caused by bleomycin administration. Lung injury was induced in PPAR-alpha wild-type (WT) mice and PPAR-alpha knockout (KO) mice by intratracheal administration of bleomycin. An increase of immunoreactivity to poly-ADP-ribose, TNF-alpha, and IL-1 beta, as well as a significant loss of body weight and mortality was observed in the lung of bleomycin-treated PPAR-alpha WT mice. The absence of a functional PPAR-alpha gene in PPAR-alpha KO mice resulted in a significant augmentation of all the above-described parameters. On the contrary, the treatment of PPAR-alpha WT with WY-14643 (1 mg/kg daily) significantly reduced the degree of lung injury, the rise in myeloperoxidase activity, and the increase in staining (immunohistochemistry) for poly-ADP-ribose, TNF-alpha, and IL-1 beta caused by bleomycin administration. Thus, endogenous and exogenous PPAR-alpha ligands reduce the degree of lung injury induced by bleomycin in the mice. Therefore, we propose that the PPAR-alpha ligand may be useful in the treatment of lung injury.

Melatonin limits lung injury in bleomycin treated mice

Melatonin is the principal secretory product of the pineal gland and its role as an immuno-modulator is well established. Recent evidence shows that melatonin is a scavenger of oxyradicals and peroxynitrite and exerts protective effects in septic shock, hemorrhagic shock and inflammation. The aim of this study was to investigate the effect of melatonin on the lung injury caused by bleomycin (BLM) administration. Mice subjected to intratracheal administration of BLM developed significant lung injury characterized by a marked neutrophil infiltration [assessed by myeloperoxidase (MPO) activity] and by tissue edema. In addition, an increase of immunoreactivity to nitrotyrosine, poly-ADP-ribose (PAR) was also observed in the lung of BLM-treated mice. Also, lung injury induced by BLM administration was correlated with a significant loss of body weight and with a significant mortality. Administration of melatonin (10 mg/kg i.p.) daily significantly reduced the (i) loss of body weight, (ii) mortality rate, (iii) infiltration of the lung with polymorphonuclear neutrophils (MPO activity), (iv) edema formation and (v) histological evidence of lung injury. Administration of melatonin also markedly reduced the nitrotyrosine and PAR formation. Taken together, our results demonstrate that treatment with melatonin significantly reduces lung injury induced by BLM in the mice.

Activation of Discoidin Domain Receptor 1 on CD14-Positive Bronchoalveolar Lavage Fluid Cells Induces Chemokine Production in Idiopathic Pulmonary Fibrosis

Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase activated by collagen. We previously reported the functional expression of DDR1 on human monocyte-derived macrophages in vitro; however, information regarding its role in diseases is limited. Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease, and the lesions contain an abundance of collagen. In this study, we examined DDR1 expression on bronchoalveolar lavage fluid (BALF) cells and investigated its functionality using samples obtained from 28 IPF patients, 13 chronic obstructive pulmonary disease patients, and 14 healthy volunteers. The DDR1 expression level in CD14-positive BALF cells was higher in IPF patients than in chronic obstructive pulmonary disease patients or healthy volunteers. The predominant isoform was DDR1b in the IPF group, while DDR1a was predominant in the other two groups. Using immunohistochemical analysis, we also detected DDR1 expression on infiltrating inflammatory cells in the IPF lesion. In IPF patients, DDR1 activation induced the production of MCP-1, IL-8, MIP-1 alpha, and matrix metalloproteinase-9 (MMP-9) from CD14-positive BALF cells in a p38 MAPK-dependent manner. In contrast, DDR1 activation of CD14-positive BALF cells in the other groups did not induce the production of these chemokines or MMP-9. These chemokines and MMP-9 contribute to the development of IPF and, therefore, we suggest that DDR1 might be associated with the pathogenesis of IPF in the tissue microenvironment.

The role of transforming growth factor beta in lung development and disease

Transforming growth factor (TGF) beta plays an important role in normal pulmonary morphogenesis and function and in the pathogenesis of lung disease. The effect of TGFbeta is regulated via a selective pathway of TGFbeta synthesis and signaling that involves activation of latent TGFbeta, specific TGFbeta receptors, and intracellular signaling via Smad molecules. All three isoforms of TGFbeta are expressed at high levels during normal lung development, being particularly important for branching morphogenesis and epithelial cell differentiation with maturation of surfactant synthesis. Small amounts of TGFbeta are still present in the adult lung, and TGFbeta is involved in normal tissue repair following lung injury. However, in a variety of forms of pulmonary pathology, the expression of TGFbeta is increased. These include chronic lung disease of prematurity as well as several forms of acute and chronic adult lung disease. While TGFbeta1 appears to be the predominant isoform involved, elevated levels of all three isoforms have been demonstrated. The increase in TGFbeta precedes abnormalities in lung function and detectable lung pathology, but correlates with the severity of the disease. TGFbeta plays a key role in mediating fibrotic tissue remodeling by increasing the production and decreasing the degradation of connective tissue via several mechanisms.

Immunomodulatory agents for idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic Pulmonary Fibrosis (IPF) or Usual Interstitial Pneumonia (UIP) is a form of chronic fibrosing interstitial pneumonia of unknown aetiology, with progressively deteriorating respiratory function and ultimately death from respiratory failure. Most treatments are intended to suppress inflammation but none has been proven to alter this process. The most widespread approach uses oral corticosteroids; others use immunosuppressive, immunomodulatory or anti-fibrotic agents, alone or with corticosteroids. A Cochrane review of corticosteroids in IPF has found no evidence that they are of benefit.

OBJECTIVES

To determine the effect of non-corticosteroid immunosuppressive, anti-fibrotic and immunomodulatory agents in the treatment of IPF(UIP).

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL - The Cochrane Library, Issue 2 2003), MEDLINE (January 1966 to April 2003), EMBASE (January 1985 to April 2003) and with additional handsearching.

SELECTION CRITERIA

RCTs/CCTs utilising non-corticosteroid immunosuppressive, anti-fibrotic or immunomodulatory agents versus either placebo or corticosteroids alone in adult patients with histological evidence of IPF(UIP) or with a diagnosis consistent with published American Thoracic Society guidelines were included.

DATA COLLECTION AND ANALYSIS

We retrieved abstracts of identified articles and reviewed those possibly fulfilling inclusion criteria and included or excluded. Two reviewers assessed the studies for inclusion in the review. Where doubt existed a third reviewer re-assessed the article and consensus was obtained. Methodological quality was assessed using the Jadad scale and the Cochrane assessment of allocation of concealment.

MAIN RESULTS

59 studies were identified. Quality was generally poor. Only three RCT/CCTs were suitable for meta-analysis, two lesser quality RCTs were included in discussion only, 52 studies were excluded and two ongoing trials were identified. Each high quality trial used a different agent (azathioprine, colchicine, interferon-gamma 1b) and meaningful comparisons are not possible. Azathioprine and Interferon were studied as additional therapy, whilst colchicine was compared with oral corticosteroids. Only interferon was shown to produce any significant improvement in pulmonary function and arterial oxygenation. There may be a small (but undefined) long term survival advantage for azathioprine. One of the lower quality studies showed a marginal benefit for cyclophosphamide and prednisone over prednisone alone; the other showed no benefit for azathioprine and prednisone over prednisone alone. There are no high quality studies utilising cyclophosphamide.

REVIEWER'S CONCLUSIONS

There is little good quality information regarding the efficacy of non-corticosteroid agents in IPF(UIP). The older agents have generally not been well evaluated. A number of new agents require further evaluation. Currently there is little to justify the routine use of any non-corticosteroid agent in the management of IPF(UIP).

Increased blood carboxyhaemoglobin concentrations in inflammatory pulmonary diseases

BACKGROUND

Exhaled carbon monoxide has been reported to increase in inflammatory pulmonary diseases and to be correlated with blood carboxyhaemoglobin (Hb-CO) concentration. A study was undertaken to determine whether arterial blood Hb-CO increases in patients with inflammatory pulmonary diseases.

METHODS

The Hb-CO concentration in arterial blood was measured with a spectrophotometer in 34 normal control subjects, 24 patients with bronchial asthma, 52 patients with pneumonia, and 21 patients with idiopathic pulmonary fibrosis (IPF).

RESULTS

The mean (SE) Hb-CO concentrations in patients with bronchial asthma during exacerbations (n=24, 1.05 (0.05)%), with pneumonia at the onset of illness (n=52, 1.08 (0.06)%), and with IPF (n=21, 1.03 (0.09)%) were significantly higher than those in control subjects (n=34, 0.60 (0.07)%) (mean difference 0.45% (95% confidence interval (CI) 0.23 to 0.67), p<0.01 in patients with bronchial asthma, mean difference 0.48% (95% CI 0.35 to 0.60), p<0.0001 in patients with pneumonia, and mean difference 0.43% (95% CI 0.26 to 0.61) p<0.001 in patients with IPF). In 20 patients with bronchial asthma the Hb-CO concentration decreased after 3 weeks of treatment with oral glucocorticoids (p<0.001). In 20 patients with pneumonia the Hb-CO concentration had decreased after 3 weeks when patients showed evidence of clinical improvement (p<0.001). The values of C-reactive protein (CRP), an acute phase protein, correlated with Hb-CO concentrations in patients with pneumonia (r=0.74, p<0.0001) and in those with IPF (r=0.46, p<0.01). In patients with bronchial asthma changes in Hb-CO concentrations were significantly correlated with those in forced expiratory volume in 1 second (FEV(1)) after 3 weeks (r=0.67, p<0.01). Exhaled carbon monoxide (CO) concentrations were correlated with Hb-CO concentrations (n=33, r=0.80, p<0.0001).

CONCLUSIONS

Hb-CO concentrations are increased in inflammatory pulmonary diseases including bronchial asthma, pneumonia, and IPF. Measurement of arterial Hb-CO may be a useful means of monitoring pulmonary inflammation.

The ability of mineral dusts and fibres to initiate lipid peroxidation. Part II: relationship to different particle-induced pathological effects

Exposure to pathogenic mineral dusts and fibres is associated with pulmonary changes including fibrosis and cancer. Investigations into aetiological mechanisms of these diseases have identified modifications in specific macromolecules as well as changes in certain early processes, which have preceded fibrosis and cancer. Peroxidation of lipids is one such modification, which is observed following exposure to mineral dusts and fibres. Their ability to initiate lipid peroxidation and the parameters that determine this ability have recently been reviewed. Part II of this review examines the relationship between the capacity of mineral dusts and fibres to initiate lipid peroxidation and a number of pathological changes they produce. The oxidative modification of polyunsaturated fatty acids is a major contributor to membrane damage in cells and has been implicated in a great variety of pathological processes. In most pathological conditions where an induction of lipid peroxidation is observed it is assumed to be the consequence of disease, without further establishing if the induction of lipid peroxidation may have preceded or accompanied the disease. In the great majority of instances, however, despite the difficulty in proving this association, a causal relationship between lipid peroxidation and disease cannot be ruled out.

Contribution of small GTPase Rho and its target protein rock in a murine model of lung fibrosis

Excess fibroblasts and inflammatory cells may play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). The small GTPase, Rho, and its target protein, Rho-associated coiled-coil-forming protein kinase (ROCK), have been recognized to be major regulators of cell locomotion mediated by reorganization of the actin cytoskelton. Activated ROCK inhibits myosin phosphatase, and this in turn induces phosphorylation of the myosin light chain (MLC). To determine the mechanisms underlying the deterioration process of IPF, we investigated the effect of Y-27632, a selective ROCK inhibitor, in a murine model of bleomycin (BLM)-induced lung fibrosis. The Aschcroft score and hydroxyproline content of the BLM-treated mouse lung decreased in response to Y-27632 treatment. The number of broncoalveolar cells was decreased by Y-27632, and migration of macrophages, neutrophils, and fibroblasts in vitro was inhibited by Y-27632 regardless of various stimuli. Although expression of ROCK-II mRNA in the lung homogenates of the BLM-treated mice was increased approximately 9-fold, expression of ROCK-II protein showed only a slight tendency to increase. BLM elevated MLC phosphorylation levels, and Y-27632 inhibited BLM response. These findings indicate that the Rho/ROCK-mediated pathway plays an important role in IPF, and that blocking of this pathway leads to inhibition of IPF development.

Inhibitory effects of a lecithinized superoxide dismutase on bleomycin-induced pulmonary fibrosis in mice

Oxidant/antioxidant imbalance is thought to be involved in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Therefore, antioxidants, such as superoxide dismutase (SOD), are expected to have an inhibitory potential against IPF. To elucidate whether a lecithinized SOD (phosphatidylcholine [PC]-SOD) has the potential to be a new therapeutic agent for IPF, we investigated the inhibitory effects of PC-SOD at doses of 1 mg/kg/d (low dose) and 10 mg/kg/d (high dose) and of methylprednisolone (mPSL) on bleomycin (BLM)-induced pulmonary fibrosis in mice. Histopathologic evaluation and lung hydroxyproline content revealed that the severity of fibrosis was attenuated in mice treated with low-dose PC-SOD, whereas no significant effect was observed in other mice. In bronchoalveolar lavage fluid on Day 1 after treatment with BLM, BLM-induced increases in total cell number, populations of lymphocytes and neutrophils, and expression of messenger RNA for interleukin-1beta and platelet-derived growth factor (PDGF)-A were significantly suppressed in PC-SOD-treated mice. The suppression of PDGF-A expression was significantly greater in mice treated with low-dose PC-SOD than in mice treated with high-dose PC-SOD or mPSL. In summary, this study demonstrated the inhibitory effects of low-dose PC-SOD on the development of pulmonary fibrosis, which indicates the potential usefulness of PC-SOD as a new treatment agent for IPF or at least for BLM-induced pulmonary fibrosis in humans.

Lovastatin induces fibroblast apoptosis in vitro and in vivo. A possible therapy for fibroproliferative disorders

Diseases associated with pathological fibroproliferation represent a major cause of morbidity and mortality. Despite the importance of this class of disorders, current therapy is of limited value, and no therapy is available to reduce the fibroblast population size within existing fibrotic lesions. In this regard, constitutive expression of growth-promoting genes can sensitize cells to undergo apoptosis. Studies in our laboratory have demonstrated that lovastatin potently induces apoptosis in fibroblasts constitutively expressing Myc, and that lung fibroblasts isolated from fibrotic lesions constitutively express growth-promoting genes. In this study, we sought to determine if nontransformed lung fibroblasts would manifest susceptibility to lovastatin-induced apoptosis similar to that observed in fibroblasts ectopically expressing Myc. Here we show that clinically achievable concentrations of lovastatin induce apoptosis in normal and fibrotic lung fibroblasts in vitro, as evidenced by acridine orange staining, terminal transferase nick end translation (TUNEL), and DNA laddering. Apoptosis of human lung fibroblasts was dose- and time-dependent, and blocked by exogenous mevalonic acid. Furthermore, apoptosis was associated with decreased levels of mature Ras, a molecule directly implicated in fibroblast rescue from apoptosis. The ability of lovastatin to induce fibroblast apoptosis in vivo was examined using a guinea pig wound chamber model. Lovastatin (5 microM, 8 d) reduced granulation tissue formation in the wound chambers by 64.7%, with associated ultrastructural evidence of fibroblast apoptosis. These findings support further study of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors as potential therapy for patients with fibroproliferative disorders.

Idiopathic pulmonary fibrosis: current concepts

Idiopathic pulmonary fibrosis (IPF) is generally defined as a progressive, fibrosing inflammatory disease of the lung parenchyma of unknown cause. It is characterized by slowly increasing dyspnea, diffuse interstitial lung infiltrates, restrictive lung dysfunction, and impaired gas exchange. Ultimately, it is fatal in most patients, and treatment options remain unsatisfactory. The advent of high-resolution computed tomography of the chest and modifications in the histopathologic classification of interstitial pneumonias have reshaped the concept of IPF. Although initially thought to be a relatively specific clinicopathologic entity, it seems likely that IPF as previously defined is a heterogeneous disorder consisting of several clinicopathologic entities with differing histopathologic patterns, clinical course, response to therapy, and prognosis. The most common histologic pattern in cases previously defined as IPF is usual interstitial pneumonia, which is associated with a median survival of less than 3 years. For accurate prognosis and optimal management of patients, the clinician should attempt to be as precise as possible in distinguishing various clinicopathologic entities that have been included under the clinical heading of IPF. In the future, we recommend that the use of the term "idiopathic pulmonary fibrosis" be restricted to patients with usual interstitial pneumonia and that clinicians recognize the fact that other idiopathic interstitial pneumonias do not have the same prognostic effect traditionally ascribed to IPF.

Effect of cyclosporin A on inflammatory cytokine production by human alveolar macrophages

Cyclosporin A (CsA) is an immunomodulator drug that has been used in the treatment of several types of advanced pulmonary interstitial disease. This beneficial effect occurs mainly in circumstances in which alveolitis due to CD4 lymphocytes is absent, suggesting that CsA acts on other types of cells. The present study was undertaken to determine the effect of CsA on inflammatory cytokine secretion by human alveolar macrophages (AMs). Human AMs were collected by bronchoalveolar lavage from four control subjects and 13 patients with interstitial lung disease. Purified human AMs were incubated with different concentrations of CsA (200, 20 and 2 ng ml-1) in the presence or absence of lipopolysaccharide (LPS). Interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha), IL-6 and IL-8 levels were measured in supernatants using specific enzyme-linked immunosorbent assays. It was found that CsA inhibits basal secretion of TNF-alpha and IL-8 at 20 and 200 ng ml-1. However, none of the different concentrations of CsA modified basal secretion of IL-1 beta nor IL-6. By contrast, a lower concentration of CsA (2 ng ml-1) inhibits LPS-stimulated secretion of all inflammatory cytokines. It is concluded that CsA exerts a modest effect on inflammatory cytokine production by human AMs.

Lung transplantation for fibrotic lung diseases

The underlying disease of a candidate for lung transplantation, especially advanced pulmonary fibrosis, can cause particular and dramatic difficulties. Pulmonary fibrosis is the end-result of a variety of pathological diseases and their associated processes. This article summarizes the diagnosis and management of some of the more common causes of fibrosis, outlines their natural histories and treatment outcomes, and describes the trade-off of pulmonary fibrosis for lung transplantation. Four main categories of end-stage fibrosis are discussed: idiopathic pulmonary fibrosis, sarcoidosis, pulmonary fibrosis from systemic diseases or drugs, and occupational- or environmental-related pulmonary fibrosis. Each group will be covered systematically and the options and indications for lung transplantation will be addressed.

Are pleural fluid parameters related to the development of residual pleural thickening in tuberculosis?

STUDY OBJECTIVE

Identification of predictive factors for the development of residual pleural thickening (RPT).

DESIGN

Retrospective study.

LOCATION

A 1,500-bed tertiary hospital.

PATIENTS

Patients with pleural tuberculosis diagnosed between December 1991 and February 1995 in our Respiratory Disease Service.

INTERVENTIONS

The clinical and radiologic characteristics, and measurements of microbiological and biochemical parameters and markers in pleural fluid were studied. RPT was defined in a posteroanterior chest radiograph as a pleural space of >2 mm measured in the lower lateral chest at the level of an imaginary line intersecting the diaphragmatic dome.

MEASUREMENTS AND RESULTS

In 56 patients studied, 11 (19.6%) had RPT 10 mm and 24 (42.8%) had RPT >2 mm. The pleural fluid of patients with RPT 10 mm had a significantly lower glucose concentration and pH and higher lysozyme and tumor necrosis factor-alpha levels than the other patients. The pleural fluid of patients with RPT >2 mm showed no significant differences.

CONCLUSIONS

The development of RPT 10 mm was related to higher concentrations of lysozyme and tumor necrosis factor-alpha and lower glucose concentration and pH in pleural fluid compared with development of lower measurements of RPT.

Effects of neutrophil elastase inhibitor on bleomycin-induced pulmonary fibrosis in mice

Neutrophils play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). To elucidate the possible involvement of neutrophil elastase (NE) in pulmonary fibrosis, we investigated the efficacy of a new specific NE inhibitor (ONO-5046 Na) in a murine model of human IPF, bleomycin-induced pulmonary fibrosis. Bronchoalveolar lavage (BAL) and histopathological analysis were performed on bleomycin-treated mice (group A), bleomycin and ONO-5046 Na-treated mice (group B), and saline control groups at 1, 15, and 29 d after the end of bleomycin treatment. At 29 d, multifocal fibrosis was observed in group A, whereas no fibrotic regions were observed in group B. Interleukin-1 beta and macrophage inflammatory protein-2 mRNA levels in BAL cells on day 1, and platelet-derived growth factor-A and insulin-like growth factor-1 mRNA levels on days 1 and 15, were significantly lower in group B than in group A. Thus, we demonstrated an inhibitory effect of ONO-5046. Na on pulmonary fibrosis in mice, indicating the involvement of NE in the pathogenesis of pulmonary fibrosis. We propose that this effect might be related to suppressed expression of particular cytokines in alveolar macrophages and that this specific NE inhibitor could be a novel therapeutic agent for IPF.