Radiological versus histological diagnosis in UIP and NSIP: survival implications

Therapeutic targeting of CC ligand 21 or CC chemokine receptor 7 abrogates pulmonary fibrosis induced by the adoptive transfer of human pulmonary fibroblasts to immunodeficient mice

Idiopathic interstitial pneumonias (IIPs) are a collection of pulmonary fibrotic diseases of unknown etiopathogenesis. CC chemokine receptor 7 (CCR7) is expressed in IIP biopsies and primary fibroblast lines, but its role in pulmonary fibrosis was not previously examined. To study the in vivo role of CCR7 in a novel model of pulmonary fibrosis, 1.0 x 10(6) primary fibroblasts grown from idiopathic pulmonary fibrosis/usual interstitial pneumonia, nonspecific interstitial pneumonia, or histologically normal biopsies were injected intravenously into C.B-17 severe combined immunodeficiency (SCID)/beige (bg) mice. At days 35 and 63 after idiopathic pulmonary fibrosis/usual interstitial pneumonia fibroblast injection, patchy interstitial fibrosis and increased hydroxyproline were present in the lungs of immunodeficient mice. Adoptively transferred nonspecific interstitial pneumonia fibroblasts caused a more diffuse interstitial fibrosis and increased hydroxyproline levels at both times, but injected normal human fibroblasts did not induce interstitial remodeling changes in C.B-17SCID/bg mice. Systemic therapeutic immunoneutralization of either human CCR7 or CC ligand 21, its ligand, significantly attenuated the pulmonary fibrosis in groups of C.B-17SCID/bg mice that received either type of IIP fibroblasts. Thus, the present study demonstrates that pulmonary fibrosis is initiated by the intravenous introduction of primary human fibroblast lines into immunodeficient mice, and this fibrotic response is dependent on the interaction between CC ligand 21 and CCR7.

Analysis of 39 cases of idiopathic chronic interstitial pneumonia

OBJECTIVE

To make a retrospective analysis of lung biopsy samples obtained from patients diagnosed with chronic idiopathic interstitial pneumonia, as defined in the American Thoracic Society/European Respiratory Society classification system made public in 2000.

METHODS

Samples from 252 open-lung biopsies of patients with interstitial lung disease, all performed between 1977 and 1999, were reviewed, and 39 cases of idiopathic interstitial lung disease were selected and re-evaluated by two pathologists in accordance with the American Thoracic Society/European Respiratory Society classification system.

RESULTS

Among those 39 cases, the diagnoses were maintained in 28 (71.8%). A new pathologic entity, nonspecific interstitial pneumonia, was included in the reclassification, and overlapping patterns were observed in 6 cases. Of the 28 cases in which the diagnosis of chronic idiopathic interstitial pneumonia remained unchanged, idiopathic pulmonary fibrosis was accompanied by cryptogenic organizing pneumonia in 4, cryptogenic organizing pneumonia was accompanied by nonspecific interstitial pneumonia in 1, and desquamative interstitial pneumonia was accompanied by nonspecific interstitial pneumonia in 1. All cases of idiopathic pulmonary fibrosis were confirmed, although 3 of those were found to be accompanied by cryptogenic organizing pneumonia. Virtually all prior diagnoses were maintained in the review of the biopsy samples (p > 0,05).

CONCLUSION

The American Thoracic Society/European Respiratory Society system of classifying interstitial lung disease is a useful tool for pathologists who deal with lung biopsies.

Is there a uniform approach to the management of diffuse parenchymal lung disease (DPLD) in the UK? A national benchmarking exercise

Background

Benchmarking is the comparison of a process to the work or results of others. We conducted a national benchmarking exercise to determine how UK pulmonologists manage common clinical scenarios in diffuse parenchymal lung disease (DPLD), and to determine current use and availability of investigative resources. We compared management decisions to existing international guidelines.

Methods

Consultant members of the British Thoracic Society were mailed a questionnaire seeking their views on the management of three common scenarios in DPLD. They were asked to choose from various management options for each case. Information was also obtained from the respondents on time served as a consultant, type of institution in which they worked and the availability of a local radiologist and histopathologist with an interest/expertise in thoracic medicine.

Results

370 out of 689 consultants replied (54% response rate). There were many differences in the approach to the management of all three cases. Given a scenario of relapsing pulmonary sarcoidosis in a lady with multiple co-morbidities, half of respondents would institute treatment with a variety of immunosuppressants while a half would simply observe. 42% would refer a 57-year old lady with new onset DPLD for a surgical lung biopsy, while a similar number would not. 80% would have referred her for transplantation, but a fifth would not. 50% of consultants from district general hospitals would have opted for a surgical biopsy compared to 24% from cardiothoracic centres: this may reflect greater availability of a radiologist with special interest in thoracic imaging in cardiothoracic centres, obviating the need for tissue diagnosis. Faced with an elderly male with high resolution CT thorax (HRCT) evidence of usual interstitial pneumonia (UIP), three quarters would observe, while a quarter would start immunosuppressants. 11% would refer for a surgical biopsy. 14% of UK pulmonologists responding to the survey revealed they had no access to a radiologist with an interest in thoracic radiology.

Conclusion

From our survey, it appears there is a lack of consensus in the management of DPLD. This may reflect lack of evidence, lack of resources or a failure to implement current guidelines.

A double blind randomised placebo controlled pilot study of oral co-trimoxazole in advanced fibrotic lung disease

BACKGROUND

In 1996, clinical improvement with oral co-trimoxazole was noted in a patient with biopsy proven advanced fibrotic lung disease who was awaiting a lung transplant. Subsequently, 14 patients with end stage fibrotic lung disease also responded to oral co-trimoxazole. This prompted a double blind randomised placebo controlled pilot study in patients with advanced stages of idiopathic interstitial pneumonias (IIP) to objectively measure benefit.

PATIENTS

Twenty patients (aged 49-84 years; 11 males) with progressive fibrotic lung disease who had differing subtype diagnosis from CT scans of progressive fibrotic IIP, and showed oxygen desaturation on exertion were selected.

METHOD

A detailed assessment of arterial gases, lung function, and progressive shuttle-walking tests combined with oxygen saturation monitoring. Quality of life data was recorded. Randomisation was to co-trimoxazole or identical placebo for 3 months followed by 6 weeks of pulmonary rehabilitation before decoding. Placebo patients received active treatment upon decoding with continued follow up of all patients.

MAIN OUTCOME MEASURES

Primary 1. Shuttle walking test. Secondary 2. FVC and quality of life.

RESULTS

Active treatment showed a significant improvement in shuttle walking test from 255 to 355 m (p=0.002) (95% CI 200-450) with reduced oxygen desaturations during exercise (p=0.003). FVC improved on treatment (+21%) from median 1.9 to 2.3 L (p=0.05) (95% CI 1.3-3.0) but TLC and DLCO were not significantly changed although stable at 12 months. The MRC 5 Point Dyspnoea Score showed improvement (p=0.05) at 3 months for the active group which was maintained at 12 months. The SGHRQ showed a significant reduction in symptom scores at 12 months (p=0.05). The placebo group showed no significant change in any parameters, but demonstrated identical improvement following oral co-trimoxazole. Serum vascular endothelial growth factor (VEGF) was reduced 50% in the active group at 3 months, but just failed to reach statistical significance. 'Out of study' HRCT scans in 12 patients showed significant reduction in ground glass changes (p=0.05) after 12 months of continuous co-trimoxazole treatment.

CONCLUSION

The findings of the pilot study show significant improvements in objective and subjective parameters which fulfil the ATS/ERS (2000) criteria of 'a favourable response to treatment'.

Is HRCT the best way to diagnose idiopathic interstitial fibrosis?

PURPOSE OF REVIEW

High-resolution computed tomography (HRCT) has been the major advance in the diagnosis of idiopathic interstitial pneumonias in the last two decades. In diffuse lung diseases, HRCT now has a central role in routine diagnostic evaluation, and a major impact on the utility of other diagnostic tests, especially bronchoalveolar lavage and surgical lung biopsy.

RECENT FINDINGS

Numerous published studies have evaluated the accuracy of HRCT. The clinical information was not always utilized to generate a noninvasive diagnosis, however. Despite failure to identify idiopathic pulmonary fibrosis on HRCT in a significant minority of cases, given compatible clinical data, characteristic HRCT appearances justify noninvasive diagnosis in most patients. The limitations of the published studies highlight importance of integrating HRCT data with baseline clinical information and, in selected cases, histopathologic findings.

SUMMARY

When HRCT and clinical findings are both typical of an individual diffuse lung disease, i.e. 'pathognomonic', it is generally appropriate to institute management based on a confident noninvasive diagnosis. When clinical and HRCT data are divergent, or when HRCT features are 'indeterminate', however, histologic evaluation continues to play an essential role. Integration of histology with radiologic and clinical data is the best way to formulate the final diagnosis in these cases.

Classification and natural history of the idiopathic interstitial pneumonias

In the American Thoracic Society/European Respiratory Society consensus classification, idiopathic interstitial pneumonias are classified into seven clinicopathologic entities. The classification is largely based on histopathology, but depends on the close interaction of clinician, radiologist, and pathologist. An accurate diagnosis can be very difficult, especially when deciding between idiopathic pulmonary fibrosis and fibrotic nonspecific interstitial pneumonia; better diagnostic markers are needed. The prognosis of idiopathic pulmonary fibrosis is very poor, with median survival of 2-4 yr after the diagnosis, yet the course of individual patients is highly variable. Predicting prognosis in the individual patient is challenging but various clinical and radiologic variables have been identified. According to several recent clinical trials, the natural history of this disease may involve periods of relative stability punctuated by acute exacerbations of disease that result in substantial morbidity or death. Nonspecific interstitial pneumonia is characterized by a distinct histopathologic appearance and a better prognosis than idiopathic pulmonary fibrosis. However, there is still confusion and controversy over the relationship between idiopathic pulmonary fibrosis and fibrotic nonspecific interstitial pneumonia.

Clinical review: Idiopathic pulmonary fibrosis—Past, present and future

Idiopathic pulmonary fibrosis (IPF) is an important, and devastating, interstitial lung disease. It has a median mortality of only 3 years, worse than many cancers, and its incidence continues to rise. In this article, an overview of key developments in our understanding and clinical management of IPF will be provided.

Usual Interstitial Pneumonia and Chronic Idiopathic Interstitial Pneumonia: Analysis of CT Appearance in 92 Patients

PURPOSE

To retrospectively analyze computed tomographic (CT) findings of chronic idiopathic interstitial pneumonia (IIP) and to determine which findings are most helpful for distinguishing IIP from usual interstitial pneumonia (UIP) with univariate and multivariate analyses.

MATERIALS AND METHODS

Institutional review board approval and informed consent were not required for this retrospective review of patient records and images. Two observers working independently and without knowledge of the diagnosis evaluated the extent and distribution of various thin-section CT findings (ground-glass opacity, consolidation, reticulation, and honeycombing) in 92 patients (51 men, 41 women; mean age, 56 years; age range, 29-81 years) with a histologic diagnosis of UIP (n = 20), cellular nonspecific interstitial pneumonia (NSIP) (n = 16), fibrotic NSIP (n = 16), respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) (n = 11), desquamative interstitial pneumonia (DIP) (n = 15), or lymphoid interstitial pneumonia (LIP) (n = 14). Observers used univariate and multivariate statistical analyses to compare their findings with the extent and distribution of UIP.

RESULTS

Observers made the correct diagnosis in 145 (79%) of 184 readings. Multivariate logistic regression analysis showed that the independent findings that distinguished UIP from cellular NSIP were the extent of honeycombing and the most proximal bronchus with traction bronchiectasis (odds ratio, 5.16 and 0.37, respectively); the finding that distinguished UIP from fibrotic NSIP was the extent of honeycombing (odds ratio, 2.10). CT features that distinguished UIP from RB-ILD and DIP included extent of ground-glass opacity (odds ratio, 0.76), thickening of bronchovascular bundles (odds ratio, 1.58), the most proximal bronchus with traction bronchiectasis (odds ratio, 0.22), and the number of segments with traction bronchiectasis (odds ratio, 3.64).

CONCLUSION

UIP has a characteristic appearance that usually facilitates distinction from other types of chronic IIPs at thin-section CT. The most useful finding when differentiating UIP from NSIP was the extent of honeycombing.

Evolving concepts in the early and accurate diagnosis of idiopathic pulmonary fibrosis

The diagnosis of idiopathic pulmonary fibrosis (IPF) requires an integrated multidisciplinary approach involving pulmonologists, radiologists, and pathologists. Early recognition of IPF and of its differentiation from other interstitial lung diseases is important for directing patient management and predicting prognosis. Clinical suspicion of IPF should be raised when patients, particularly those over 50 years of age, present with dyspnea that is gradual in onset and progressive. A confident diagnosis of IPF can be made based on clinical assessment, pulmonary function test results, and radiographic and bronchoscopic evaluation. However, the definitive diagnosis of IPF requires a surgical lung biopsy to confirm the histopathologic pattern of usual interstitial pneumonia.

Surgical biopsy: its appropriateness in diagnosing interstitial lung disease

PURPOSE OF REVIEW

Our goal is to update advances in the use of surgical lung biopsy in the idiopathic interstitial pneumonias. We discuss an approach for identifying patients with idiopathic interstitial pneumonias who may benefit from surgical lung biopsy, newer surgical approaches and complications and risks of surgery.

RECENT FINDINGS

A consensus statement on idiopathic interstitial pneumonias has described the natural history and response to therapy of idiopathic interstitial pneumonias. The statement discussed selection of patients with idiopathic interstitial pneumonias for surgical lung biopsy and avoidance of unneeded biopsy, particularly for patients with 'classical' radiographic findings of idiopathic pulmonary fibrosis. Video-assisted thoracoscopic lung biopsy continues to be the standard procedure for surgical lung biopsy. Newer approaches have used outpatient surgery for selected patients, earlier removal of chest tubes and modifications of surgical technique. At-risk patients include those with respiratory failure, rapid progression of disease, pulmonary hypertension and advanced disease.

SUMMARY

Standard video-assisted thoracoscopic lung biopsy should be considered in patients with interstitial lung diseases of unknown cause who have a subacute course, ground-glass opacities on high-resolution computed tomography or features atypical for idiopathic pulmonary fibrosis, as these patients may respond to therapy. A step-wise process for selection of patients for surgical lung biopsy is recommended.

Idiopathic pulmonary fibrosis: prognostic value of changes in physiology and six-minute-walk test

RATIONALE AND HYPOTHESIS

Idiopathic pulmonary fibrosis is a fatal disease with a variable rate of progression. We hypothesized that changes in distance walked and quantity of desaturation during a six-minute-walk test (6MWT) would add prognostic information to changes in FVC or diffusing capacity for carbon monoxide.

METHODS

One hundred ninety-seven patients with idiopathic pulmonary fibrosis were evaluated. Desaturation during the 6MWT was associated with increased mortality even if a threshold of 88% was not reached. Baseline walk distance predicted subsequent walk distance but was not a reliable predictor of subsequent mortality in multivariate survival models. The predictive ability of serial changes in physiology varied when patients were stratified by the presence/absence of desaturation < or = 88% during a baseline 6MWT. For patients with a baseline saturation < or = 88% during a 6MWT, the strongest observed predictor of mortality was serial change in diffusing capacity for carbon monoxide. For patients with saturation > 88% during their baseline walk test, serial decreases in FVC and increases in desaturation area significantly predicted subsequent mortality, whereas decreases in walk distance and in diffusing capacity for carbon monoxide displayed less consistent statistical evidence of increasing mortality in our patients.

CONCLUSION

These data highlight the importance of stratifying patients by degree of desaturation during a 6MWT before attributing prognostic value to serial changes in other physiologic variables.

The role of CCL12 in the recruitment of fibrocytes and lung fibrosis

We have previously shown that mice that are genetically deficient in the CCR2 gene (CCR2-/- mice) are protected from fluorescein isothiocyanate (FITC)-induced lung fibrosis. Protection from fibrosis correlated with impaired recruitment of fibrocytes (bone marrow-derived cells, which share both leukocyte and mesenchymal markers). There are three ligands for CCR2 in the mouse: CCL2, CCL7, and CCL12. CCL2 and CCL12 are both elevated in the lung after FITC injury, but with different kinetics. CCL2 is maximal at Day 1 and absent by Day 7 after FITC. In contrast, CCL12 peaks at Day 3, but remains elevated through Day 21 after FITC. We now demonstrate that while CCR2-/- mice are protected from FITC-induced fibrosis, CCL2-/- mice are not. CCL2-/- mice are able to recruit fibrocytes to FITC-injured airspaces, unlike CCR2-/- mice. Adoptive transfer of CCR2-expressing fibrocytes augments FITC-induced fibrosis in both wild-type and CCR2-/- mice, suggesting that these cells play a pathogenic role in the disease process. Both CCL2 and CCL12 are chemotactic for fibrocytes. However, neutralization of CCL12 in wild-type mice significantly protects from FITC-induced fibrosis, whereas neutralization of CCL2 was less effective. Thus, CCL12 is likely the CCR2 ligand responsible for driving fibroproliferation in the mouse. As murine CCL12 is homologous to human CCL2, we suggest that the pathobiology of murine CCL12 in fibroproliferation may correlate to human CCL2 biology.

Focal interstitial CC chemokine receptor 7 (CCR7) expression in idiopathic interstitial pneumonia

BACKGROUND/AIMS

Idiopathic interstitial pneumonias (IIPs) are a diverse grouping of chronic pulmonary diseases characterised by varying degrees of pulmonary fibrosis. The triggers of the fibroproliferative process in IIP remain enigmatic but recent attention has been directed towards chemokine involvement in this process.

METHODS

The expression of two chemokine receptors, CCR7 and CXCR4, and their respective ligands, CCL19, CCL21, and CXCL12, were examined in surgical lung biopsies (SLBs) from patients with IIP. Transcript and protein expression of these receptors and their ligands was compared with that detected in histologically normal margin SLBs.

RESULTS

CCR7 and CXCR4 were detected by gene array and real time polymerase chain reaction analysis and CCR7, but not CXCR4, expression was significantly raised in usual interstitial pneumonia (UIP) relative to biopsies from patients diagnosed with non-specific interstitial pneumonia (NSIP) or respiratory bronchiolitis/interstitial lung disease (RBILD). CCR7 protein was expressed in interstitial areas of all upper and lower lobe UIP SLBs analysed. CCR7 expression was present in 50% of NSIP SLBs, and CCR7 was restricted to blood vessels and mononuclear cells in 75% of RBILD SLBs. Immune cell specific CXCR4 expression was seen in IIP and normal margin biopsies. CCR7 positive areas in UIP biopsies were concomitantly positive for CD45 (the leucocyte common antigen) but CCR7 positive areas in all IIP SLBs lacked the haemopoietic stem cell antigen CD34, collagen 1, and alpha smooth muscle actin.

CONCLUSION

This molecular and immunohistochemical analysis showed that IIPs are associated with abnormal CCR7 transcript and protein expression.

Interstitial Lung Disease: Effects of Thin-Section CT on Clinical Decision Making

PURPOSE

To retrospectively quantify the change in the diagnosis and management of suspected interstitial lung disease when thin-section computed tomography (CT) is added to pretest probabilities.

MATERIALS AND METHODS

The institutional review board does not require approval or patient informed consent for retrospective study of case records and CT studies. Six pulmonologists reviewed data sheets containing clinical information and results of pulmonary function tests and chest radiographs of 168 consecutive patients (86 women and 82 men; mean age, 59.8 years; age range, 22-86 years) suspected of having interstitial lung disease. Differential diagnoses and responses to specific questions regarding patient care were recorded before and after assimilation of thin-section CT findings. Both unweighted and weighted kappa analyses were used to determine agreement between pulmonologists before and after CT.

RESULTS

First-choice diagnosis changed in 520 (51%) of 1008 cases, and agreement on first-choice diagnosis increased from 0.47 to 0.72 after thin-section CT. In addition, confidence in the first-choice diagnosis increased, and there was a reduction in the number of differential diagnoses offered by all pulmonologists (P < .005 and P < .001, respectively). Agreement on diagnostic probabilities for individual disorders increased substantially, particularly for diagnoses of idiopathic pulmonary fibrosis (weighted kappa = 0.58-0.89). With CT findings, pulmonologists changed their pre-CT responses regarding the use of bronchoalveolar lavage, transbronchial biopsy, and thoracoscopic biopsy in 242 (24.0%), 282 (28.0%), and 292 (29.0%) of 1008 cases, respectively. However, agreement for the use of these investigations was low both before and after CT. The request rate for thoracoscopic biopsy in patients in whom idiopathic fibrosis was diagnosed decreased from 48 of 179 (26.8%) to 26 of 233 (11.2%) after CT.

CONCLUSION

Thin-section CT resulted in a change in first-choice diagnosis in half the cases. Diagnostic confidence improved, and CT findings increased agreement between pulmonologists on diagnostic probabilities across a range of interstitial lung diseases.

Idiopathic pulmonary fibrosis: spectrum of high-resolution CT findings

OBJECTIVE

Characteristic high-resolution CT (HRCT) findings of idiopathic pulmonary fibrosis (IPF) include reticulation, architectural distortion, and honeycombing involving mainly the lung periphery and the lower lobes. In 50% of IPF patients, HRCT is nonspecific. This article illustrates the HRCT findings of IPF correlating with the pathology.

CONCLUSION

The spectrum of HRCT manifestations varies from typical findings that allow confident diagnosis to atypical patterns mimicking other diseases, including predominance of ground-glass opacity, consolidation, nodules, and atypical distribution of lesions.

Usual interstitial pneumonia and non-specific interstitial pneumonia: serial thin-section CT findings correlated with pulmonary function

Objective

We wanted to demonstrate and compare the serial high-resolution CTs (HRCT) and the pulmonary function test (PFT) findings of the usual interstitial pneumonia (UIP) and the non-specific interstitial pneumonia (NSIP).

Materials and Methods

The serial HRCT scans and the PFT results were retrospectively analysed and compared for 35 patients having UIP without significant honeycombing (UIP-w/o hc, < 5% of honeycombing at CT), 35 patients having UIP with honeycombing (UIP-w/i hc, ≥ 5% of honeycombing), and 25 patients with NSIP. The mortality rates were also compared. Follow-up CT scans were available in 75 patients (29 UIP-w/o hc patients, 22 UIP-w/i hc patients and 24 NSIP patients) and the follow-up periods ranged from 150 to 2,370 days. The initial and follow-up PFT data were available for 71 patients.

Results

On the initial CT, significant differences were present between the UIP-w/i hc patients and both the UIP-w/o hc patients and the NSIP patients in the overall extent, ground-glass opacity (GGO) away from the reticulation, reticulation and honeycombing (all p < 0.05). Improvement was noticed in five (17%) of 29 UIP-w/o hc patients, none of 22 UIP-w/i hc patients, and 9 (37%) of 24 NSIP patients; deterioration was noted in six (21%) UIP-w/o hc patients, two (9%) UIP-w/i hc patients and three (13%) NSIP patients (p = 0.044 between UIP-w/o and UIP-w/i hc; p = 0.637 between UIP-w/o hc and NSIP; p = 0.007 between UIP-w/i hc and NSIP). The serial changes of the pulmonary function in the NSIP patients were different from those noted for the UIP-w/i hc and UIP-w/o hc patients (p = 0.440 between UIP-w/o and UIP-w/i hc; p = 0.022 between UIP-w/o hc and NSIP; p = 0.003 between UIP-w/i hc and NSIP). Five (14%) of the 35 patients with UIP-w/o hc, 16 (46%) of the 35 patients with UIP-w/i hc and three (12%) of the 25 patients with NSIP died (p = 0.002, comparison for the three groups).

Conclusion

On CT, NSIP and UIP-w/o hc patients have similar patterns of parenchymal abnormalities and a similar likelihood of change in the extent of disease on follow-up. Patients with UIP-w/i hc have distinctive features and a worst prognosis.

Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and usually fatal pulmonary disease for which there are no proven drug therapies. Anti-inflammatory and immunosuppressive agents have been largely ineffective. The precise relationship of IPF to other idiopathic interstitial pneumonias (IIPs) is not known, despite the observation that different histopathologic patterns of IIP may coexist in the same patient. We propose that these different histopathologic 'reaction' patterns may be determined by complex interactions between host and environmental factors that alter the local alveolar milieu. Recent paradigms in IPF pathogenesis have focused on dysregulated epithelial-mesenchymal interactions, an imbalance in T(H)1/T(H)2 cytokine profile and potential roles for aberrant angiogenesis. In this review, we discuss these evolving concepts in disease pathogenesis and emerging therapies designed to target pro-fibrogenic pathways in IPF.

Proliferation of Pulmonary Interstitial Fibroblasts Is Mediated by Transforming Growth Factor-β1-induced Release of Extracellular Fibroblast Growth Factor-2 and Phosphorylation of p38 MAPK and JNK

Idiopathic pulmonary fibrosis (IPF; a progressive lung disease) is characterized by parenchymal remodeling with enlarged air spaces called honeycomb cysts and palisades of fibroblasts called fibroblast foci. In IPF, lung epithelial cells covering honeycomb cysts and fibroblast foci aberrantly express the active conformation of the potent fibrogenic cytokine transforming growth factor-beta1 (TGF-beta1). Using explanted rat lung slices, we transfected alveolar epithelial cells with the retrovirus pMX containing a site-directed mutation in which Cys223 and Cys225 were substituted with serines, resulting in release of biologically active TGF-beta1 and fibroblast proliferation and remodeling that resembled IPF. Fibroblasts obtained from transfected explants and in culture for 6 weeks incorporated 6.59 +/- 1.55-fold more [3H]thymidine compared with control fibroblasts without transfection or fibroblasts obtained from transfected explants cultured with antibody to fibroblast growth factor-2 (FGF-2). Primary lung fibroblasts obtained from normal rat lungs cultured with TGF-beta1 expressed increased levels of phosphorylated p38 MAPK and JNK, but not ERK1/2. The presence of TGF-beta1 caused an immediate release of extracellular FGF-2 from primary pulmonary fibroblasts; and in the presence of anti-FGF-2 antibody, phosphorylated p38 MAPK and JNK were abrogated. TGF-beta inhibits cell proliferation by suppression of c-Myc and induction of p15INK46, p21CIP1, or p27KIP. Fibroblasts cultured with TGF-beta1 showed no regulation of c-Myc or induction of p15INK46, p21CIP1,or p27KIP. These findings suggest that pulmonary fibroblasts may not respond to the anti-proliferative effects of TGF-beta1, but proliferate in response to TGF-beta1 indirectly by the release of FGF-2, which induces phosphorylation of p38 MAPK and JNK.

Case study review

Examining case studies from patients with interstitial lung diseases (ILDs) is important in order to evaluate current diagnosis and treatment options. Two cases will be discussed; the first case examines a patient with usual interstitial pneumonia, and the second case examines a patient with subacute ILD and elements to suggest a forme fruste presentation of an unclassifiable connective tissue disease. Each case highlights components of the differential diagnosis, as well as reviews the treatments and prognoses of these patients. The cases provide clinical pearls that are designed to enhance the reader's understanding of ILDs.

Non-specific interstitial pneumonia; as the first clinical presentation of various collagen vascular disorders

Recently, we have experienced significant numbers of patients diagnosed with non-specific interstitial pneumonia (NSIP) by open lung biopsy or video-assisted thoracoscopic surgery. The purpose of this work was to describe the clinical features of patients with collagen vascular disorders (CVD) presenting NSIP in the absence of systemic involvement. This study also involved a retrospective review of patients with CVD presenting clinical and pathological evidence of NSIP in the absence of systemic manifestations of CVD. We found seven patients (six from our experience and one from literature review) with histologically proven NSIP who later developed typical CVD more than 6 months after the first presentation of NSIP. In these cases, it was difficult to speculate the development of CVD at the point of first presentation. Therefore, association of CVD should be considered in patients with NSIP even in the absence of classical systemic involvement.

Exercise testing determines survival in patients with diffuse parenchymal lung disease evaluated for lung transplantation

STUDY OBJECTIVES

Diffuse parenchymal lung disease is associated with a high risk of mortality despite early referral and listing for lung transplantation. We hypothesized that cardiopulmonary exercise test results and the distance walked in 6min (6MWTD) would be associated with survival in patients with diffuse parenchymal lung disease referred for lung transplantation.

DESIGN

Retrospective cohort study.

SETTING

Tertiary care center.

PATIENTS

We included 51 consecutive patients with diffuse parenchymal lung disease who underwent exercise testing after referral to the Lung Transplant Program at the New York Presbyterian Hospital between January 2000 and December 2002. Thirty-three patients were listed, and 7 underwent transplantation during the study period. There were 17 deaths with 1 death post-transplantation.

RESULTS

A 6MWTD < 350 m was associated with an increased risk of death (HR = 4.6, 95% CI 1.5-14.2, P = 0.009). Oxygen saturation with unloaded exercise (HR = 0.91, 95% CI 0.84-0.98, P = 0.015) and oxygen consumption at peak exercise adjusted for weight (HR = 0.88, 95% CI 0.79-0.99, P = 0.039) were also associated with the risk of death. A patient with oxygen saturation <95% during unloaded exercise had a 75% chance of dying on the list for transplantation. A patient with 6MWTD < 350 m had a 67% chance of dying on the list.

CONCLUSIONS

Cardiopulmonary exercise test parameters and the 6MWTD were associated with the risk of death. Measures during exercise may be useful for determination of prognosis and for prioritizing patients with diffuse parenchymal lung disease for lung transplantation.

Interferon Gamma-1b in the Treatment of Idiopathic Pulmonary Fibrosis

Objective:

To examine the clinical aspects of idiopathic pulmonary fibrosis (IPF) and the efficacy and safety of interferon gamma-1b (IFNγ−1b) in its treatment.

Data Sources:

Epidemiologic, preclinical, and clinical studies published in the English language were identified by a MEDLINE search (1966–January 2005) using the search terms idiopathic pulmonary fibrosis, cryptogenic fibrosing alveolitis, and interferon. Additional citations were identified from the reference lists of related publications.

Study Selection and Data Extraction:

Selected preclinical studies describing the pathophysiologic basis for IFNγ−1b therapy and all clinical studies were included. Additional trials describing other treatment modalities and the determinants of response to therapy in patients with IPF were also reviewed.

Data Synthesis:

IFNγ−1b targets the fibrotic rather than inflammatory processes of IPF. The efficacy of IFNγ−1b in patients with IPF is inconsistent with regard to changes in pulmonary function and mortality, although a modest survival benefit was observed in the largest clinical trial. Adverse events related to IFNγ−1b are frequent although transient. Several cases of respiratory failure occurring subsequent to the administration of IFNγ−1b are documented.

CONCLUSIONS:

To date, although trials suggest that earlier-stage IPF may be responsive to IFNγ−1b, study results overall are inconsistent; further investigation is needed.

High-Resolution CT in Diagnosis of Diffuse Infiltrative Lung Disease

The chest radiograph remains the first imaging modality for the approach to diffuse infiltrative lung disease (DILD), but, 23 years after its introduction, high-resolution CT (HRCT) is still considered the best imaging tool for the evaluation of the pulmonary interstitium and to diagnose and assess DILD. The introduction of multidetector computed tomography (MDCT) has provided the thoracic radiologist with a powerful tool with which to image the lung. Moreover MDCT has enabled radiologists to understand better the functional information contained within CT images of DILD. By focusing on the HRCT signs, patterns, and distributions of abnormalities, and mentioning the clinical aspects and the new recent advances in pulmonary imaging, in this article we provide an overview of a practical approach to the interpretation of the DILD.

Current concepts in the classification of interstitial lung disease

The diagnosis and classification of idiopathic interstitial pneumonias continue to be problematic areas for pathologists. The recently proposed American Thoracic Society/European Respiratory Society International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumonias defines specific clinical, radiologic, and pathologic criteria for each of the pulmonary disorders that encompass the idiopathic interstitial pneumonias. In this review, the highlights of this classification are presented, along with recommended guidelines for handling lung biopsy specimens and diagnosing interstitial lung diseases.

High-Resolution Computed Tomography in Idiopathic Pulmonary Fibrosis

RATIONALE

High-resolution computed tomography (HRCT) is an integral aspect of the evaluation of patients with suspected idiopathic pulmonary fibrosis (IPF). However, few studies have evaluated its use in a large cohort.

OBJECTIVES

To describe HRCT features in patients with mild to moderate IPF, compare diagnostic evaluations by a radiology core (three thoracic radiologists) with those by study-site radiologists, correlate baseline clinical and physiologic variables with HRCT findings, and evaluate their association with mortality.

METHODS

We assessed HRCT scans from patients with IPF (n = 315) enrolled in a randomized controlled study evaluating IFN-gamma1b.

MEASUREMENTS AND MAIN RESULTS

There was concordance between study-site and core radiologists regarding the diagnosis of IPF in 86% of cases. Diffusing capacity of carbon monoxide (DLCO) was the physiologic characteristic most highly correlated with HRCT findings. Multivariate analysis identified three independent predictors of mortality: a higher extent of fibrosis score increased the risk of death (p < 0.0001), whereas a higher percent-predicted DLCO (p = 0.004) and treatment assignment to IFN-gamma1b rather than placebo (p = 0.04) reduced the risk of death.

CONCLUSIONS

A study-site diagnosis of IPF on HRCT was regularly confirmed by core radiologists. Extent of reticulation and honeycombing on HRCT is an important independent predictor of mortality in patients with IPF.

Volumetric Expiratory HRCT Imaging With MSCT

Expiratory HRCT is a powerful adjunct to inspiratory HRCT for detecting various small airway diseases. Current standard expiratory HRCT protocol consists of a limited number of non-contiguous scans at selected levels. We have developed a new volumetric expiratory HRCT protocol that allows volumetric data acquisition of lungs both at end-inspiration and end-expiration. By reducing the x-ray tube current, the radiation dose of this new protocol is equivalent to the standard expiratory HRCT protocol at our institution. This volumetric expiratory HRCT has been applied in patients with diffuse lung disease with small airway abnormalities. In this review, we describe: (1) technical considerations of VEHRCT including dose reduction, (2) the advantages of contiguous scans and multiplanar reformations, (3) clinical application of volumetric expiratory HRCT in various diffuse lung diseases, and (4) future directions including computational qualitative assessment of lung biomechanics.

Serum biomarkers in interstitial lung diseases

The use of biomarkers in medicine lies in their ability to detect disease and support diagnostic and therapeutic decisions. New research and novel understanding of the molecular basis of the disease reveals an abundance of exciting new biomarkers who present a promise for use in the everyday clinical practice. The past fifteen years have seen the emergence of numerous clinical applications of several new molecules as biologic markers in the research field relevant to interstitial lung diseases (translational research). The scope of this review is to summarize the current state of knowledge about serum biomarkers in interstitial lung diseases and their potential value as prognostic and diagnostic tools and present some of the future perspectives and challenges.

Idiopathic Interstitial Pneumonias: CT Features

Idiopathic interstitial pneumonias comprise usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP), desquamative interstitial pneumonia (DIP), respiratory bronchiolitis-associated interstitial lung disease (RB-ILD), cryptogenic organizing pneumonia (COP), acute interstitial pneumonia (AIP), and lymphoid interstitial pneumonia (LIP). Each of these entities has a typical imaging and histologic pattern, although in practice the imaging patterns may be variable. Each entity may be idiopathic or may be secondary to a recognizable cause such as collagen vascular disease or inhalational exposure. The diagnosis of idiopathic interstitial pneumonia is made by means of correlation of clinical, imaging, and pathologic features. The characteristic computed tomographic (CT) features of UIP are predominantly basal and peripheral reticular pattern with honeycombing and traction bronchiectasis. NSIP is characterized by predominantly basal ground-glass opacity and/or reticular pattern, often with traction bronchiectasis. DIP and RB-ILD are smoking-related lung diseases characterized by ground-glass opacity and centrilobular nodules. COP is characterized by patchy peripheral or peribronchovascular consolidation. AIP manifests as diffuse lung consolidation and ground-glass opacity. LIP is associated with a CT pattern of ground-glass opacity sometimes associated with perivascular cysts.

Nonspecific Interstitial Pneumonia Versus Usual Interstitial Pneumonia

OBJECTIVE

To assess the capability of the density histogram of high-resolution CT (HRCT) in differentiating nonspecific interstitial pneumonia (NSIP) from usual interstitial pneumonia (UIP) without definite honeycombing.

METHODS

Twenty-eight NSIP and 32 UIP patients without definite honeycombing on CT were included in this study. We evaluated a CT image at the level of 1 cm above the diaphragm. The pixels of the lung parenchyma were classified into 4 ranges. The fractions of each range of corresponding density were calculated. The skewness (the degree of asymmetry of a distribution) and kurtosis (how sharply peaked a histogram is) were obtained from the density histogram. The mean value and the mode value of the lung attenuation were also measured.

RESULTS

The fraction of the range of ground-glass opacity and reticular opacity was greater in NSIP patients (32%, 12%) than in UIP patients (23%, 8%) (P < 0.001). UIP had a larger fraction of the range of normal lung. The density histogram was less skewed (P = 0.01) and had a wider peak (P = 0.02) in NSIP (skewness = 1.2879 +/- 0.5672, kurtosis = 1.2115 +/- 1.9470) than in UIP (skewness = 1.6426 +/- 0.4664, kurtosis = 2.3880 +/- 1.8183).

CONCLUSION

The density histogram reflected the differences in the CT features between NSIP and UIP. Therefore, a density histogram may be helpful for differentiating NSIP from UIP without definite honeycombing.

Treatment of idiopathic pulmonary fibrosis: Is there anything new?

Idiopathic pulmonary fibrosis (IPF) is a specific form of chronic fibrosing interstitial pneumonia of unknown aetiology and is associated with the histological picture of usual interstitial pneumonia. Treatment in most cases is unsatisfactory and the prognosis remains poor. There is insufficient evidence to suggest that any treatment, apart from lung transplantation, improves survival or halts disease progression for IPF patients. Data on treatment response are limited by the paucity of clinical trails, the lack of homogenous clinical features, the small number of patients, and the absence of histological and radiological documentation in many cases. Anti-inflammatory medications such as corticosteroids, azathioprine and cyclophosphamide remain the commonly used medications. More recently, it has been proposed that IPF is a primary fibrotic disease rather than an inflammatory condition. Antifibrotic agents such as colchicine, pirfenidone and interferon-gamma (IFN-gamma) have been tried. However, a recent placebo-controlled trial has failed to demonstrate a significant effect of IFN-gamma on disease progression, lung function or quality of life in IPF patients, though a clinically significant survival benefit of the drug could not be ruled out.

Six-Minute Walk, Maximal Exercise Tests

Resting pulmonary function and exercise variables are widely used to stage and monitor idiopathic interstitial pneumonia (IIP). However, the variability of exercise data (maximal exercise and the 6-minute walk test) has not been evaluated definitively. We have prospectively quantified the reproducibility of resting and exercise functional data in fibrotic IIP (idiopathic pulmonary fibrosis, fibrotic nonspecific interstitial pneumonia) and have evaluated interrelationships between variables. Thirty consecutive patients with fibrotic IIP underwent serial resting pulmonary function tests, 6-minute walk (n = 29), and maximal exercise (n = 24) at an interval of 1 week, with all testing performed in accordance with American Thoracic Society standards. Within-subject reproducibility was excellent for 6-minute walk distance (SD/mean = 4.2%) and clinically acceptable for resting pulmonary function indices and VO(2)max on maximal exercise testing. However, the amplitude of oxygen desaturation at the end of exercise was poorly reproducible in both 6-minute walk and maximal exercise testing (SD/mean > 25%). There was a highly significant relationship between VO2max on maximal exercise testing and 6-minute walk distance (r(s) = 0.78, p < 0.0001). In fibrotic IIP, the excellent reproducibility of the 6-minute walk distance is a major advantage in routine staging and monitoring, whereas maximal exercise variables are poorly reproducible.

Clinical advances in the diagnosis and therapy of the interstitial lung diseases

The last century experienced remarkable advances in the classification, diagnosis, and understanding of the pathogenesis of the interstitial lung diseases. Technological advances, particularly physiologic testing, lung imaging studies, bronchoalveolar lavage, surgical lung biopsy, and histopathologic assessment, improved our understanding of these entities. In particular, the advent of high-resolution computed tomography, the narrowed pathologic definition of usual interstitial pneumonia, and recognition of the prognostic importance of separating usual interstitial pneumonia from other idiopathic interstitial pneumonia patterns have profoundly changed the approach to these processes. Most recently, genetic medicine, the use of new technologies (e.g., microarrays, mass spectroscopic analysis of proteins, and laser capture microdissection), and the development of animal models have had a major impact on understanding the pathogenesis and potential molecular targets for interfering with fibrogenesis. This article highlights some of the advances and changes in clinical practice that took place in the management of patients with interstitial lung diseases over the last century.

Physiology Is a Stronger Predictor of Survival than Pathology in Fibrotic Interstitial Pneumonia

The histopathologic pattern provides the most important prognostic marker for idiopathic interstitial pneumonia; however, studies have suggested that short-term changes in lung function may be more important. We investigated the prognostic factors for fibrotic interstitial pneumonia. The clinical features and follow-up course of 179 patients (131 with idiopathic pulmonary fibrosis and 48 with nonspecific interstitial pneumonia; 41 fibrotic types and 7 cellular) were analyzed retrospectively. The lung function indices improved or stabilized in most patients with fibrotic nonspecific interstitial pneumonia in contrast to the deterioration or stable condition of most patients with idiopathic pulmonary fibrosis. The 5-year survival of patients with fibrotic nonspecific interstitial pneumonia (76.2%) was better than for those with idiopathic pulmonary fibrosis (43.8%) (p = 0.007). Multivariate analysis at the time of presentation revealed that pathologic pattern, age, and diffusion capacity had important prognostic implications. However, after 6 months of follow-up, changes in FVC, initial diffusion capacity, and sex were the only independent prognostic factors, with no additional prognostic information conferred by the histologic diagnosis. Our data confirmed the importance of physiological parameters including short-term change in FVC. However, at the time of diagnosis, histopathology was important for the prediction of prognosis and future change in lung function.

Serial high resolution CT in non-specific interstitial pneumonia: prognostic value of the initial pattern

AIM

To assess the relationship between initial CT pattern and serial changes in CT findings and pulmonary function tests (PFTs) in patients with non-specific interstitial pneumonia (NSIP).

MATERIALS AND METHODS

Serial high resolution (HR) CTs and PFTs were retrospectively analyzed in 38 cases of histologically proven NSIP, including 4 with cellular NSIP, 13 with mixed cellular and fibrotic NSIP, and 21 with fibrotic NSIP. The presence and extent of various CT findings were assessed. A fibrosis index (defined as the ratio of the extent of a reticular/honeycomb pattern to the overall extent of abnormal parenchyma) was derived.

RESULTS

The predominant CT pattern was reticular/honeycomb in 27 (84%) cases and ground-glass/consolidation in 6 (16%) cases. Between scans, mean disease extent reduced by 5.2%. Disease extent reduced by >10% in 13 (34%) and increased by >10% in 6 (16%) patients. Histopathological subtype of NSIP did not correlate with individual CT pattern, predominant pattern, fibrosis index or serial change in disease extent on CT or PFTs. Response on follow-up CT was associated with fibrosis index, predominant pattern and extent of consolidation on initial CT.

CONCLUSION

In NSIP disease, progression on CT correlates with the predominant CT pattern, fibrosis index, and extent of consolidation but not with histopathological subtype. An inflammatory (ground-glass/consolidation) predominant pattern is associated with better outcome in terms of disease extent on HRCT.

Lung Transplantation

The timing of the referral and listing of patients for lung transplantation remains a difficult decision. Life expectancy and quality of life with and without transplantation are the pivotal issues that need to be considered by physicians and presented to prospective transplant candidates. The recognition of recent advances in the understanding of the various primary diseases, other potential therapies, and the latest posttransplant statistics are essential for a balanced discussion or decision about lung transplantation. This article provides a review of these and other pertinent issues for patients with various forms of advanced lung disease.

Inhibition of gelatinase B (matrix metalloproteinase-9) by dihydrolipoic acid

Alpha-lipoic acid (LA) is a disulphide-containing fatty acid that is absorbed from the diet and transported to tissues. Once it has been taken up by mammalian cells, LA is reduced to dihydrolipoic acid (DHLA), a vicinal dithiol, and rapidly effluxed into the extracellular milieu. We hypothesized that DHLA may be an effective inhibitor of human gelatinase B (GelB). Purified human GelB was incubated with 0 to 200 µmol/L DHLA, and residual enzyme activity was measured by HPLC using a fluorogenic substrate (matrix metalloproteinase substrate III). DHLA inhibited GelB in a dose-dependent fashion with an IC50of 20 µmol/L. Oxidation of DHLA resulted in a loss of DHLA's capacity to inhibit GelB. The DHLA-mediated inhibition of GelB was independent of the zinc concentration in the reaction buffer. DHLA had no inhibitory effect on gelatinase A. Zymographs of activated neutrophil lysates demonstrated that higher concentrations of DHLA also prevent the activation of GelB proenzyme. Bronchoalveolar lavage fluid from mice fed a diet enriched with LA showed significantly increased GelB inhibitory capacity (p = 0.0002 vs. regular diet). We conclude that DHLA can modulate neutrophil-derived GelB activity through direct inhibition of enzyme activity and by preventing the activation of GelB proenzyme.Key words: matrix metalloproteinases, pulmonary fibrosis, thiols, neutrophils, inflammation.

Idiopathic non-specific interstitial pneumonia: as an “autoimmune interstitial pneumonia”

Recently, we have experienced significant number of patients diagnosed with non-specific interstitial pneumonia (NSIP) by open lung biopsy or video-assisted thoracoscopic surgery. The purpose of this study is to compare clinical and pathological features of idiopathic NSIP and NSIP associated with underlying diseases (mainly autoimmune disorders). Forty-six patients with histologically proven NSIP were retrospectively collected. Twenty-four patients had underlying diseases (12 polymyositis/dermatomyositis, 5 systemic sclerosis, 2 rheumatoid arthritis, 2 Sjogren's syndrome, 1 ulcerative colitis, 1 primary biliary cirrhosis, and 1 multiple myeloma). Twenty-two of the 46 patients had no underlying diseases. It was very difficult to distinguish idiopathic NSIP and NSIP associated with underlying diseases, clinically and radiologically. Pathologically, Lymphocytic pneumonitis was demonstrated in both groups, and it was impossible to distinguish idiopathic NSIP and NSIP associated with underlying diseases. Since generalized symptoms were not observed in patients with idiopathic NSIP, and clinical and pathological features were identical to NSIP with several autoimmune disorders, we postulate new clinical entities of "autoimmune interstitial pneumonia" in cases without underlying diseases.

Nonspecific interstitial pneumonia: a real clinical entity?

Based on the current multidisciplinary classification of idiopathic interstitial pneumonia (IIP) organized by ATS/ERS, nonspecific interstitial pneumonia (NSIP) is considered as one type of IIP. An incidence of idiopathic NSIP is relatively small and possesses clinical features that are different than idiopathic pulmonary fibrosis (IPF) and usual interstitial pneumonia (UIP). Because there is little evidence of a long-term prognosis in patients with NSIP, some of them have an unfavorable prognosis similar to IPF/UIP. We review the significance of prognostic factors that have been reported in patients with IPF/UIP by applying them to patients with NSIP. The association with collagen vascular diseases focuses on etiologic background. Finally, the article discusses whether NSIP could be an early lesion of UIP based on the reported evidence and our own professional experiences.

Bone Marrow-Derived Cells in the Pathogenesis of Lung Fibrosis

Progressive pulmonary fibrosis is characterized by failed alveolar reepithelialization and fibroblast/myofibroblast accumulation, with deposition of extracellular matrix. This results in loss of lung elasticity, alveolar collapse and fibrosis, impaired gas exchange and progressive decline in pulmonary function. Myofibroblasts represent an activated, contractile cellular phenotype that are potent producers of collagen and other extracellular matrix proteins. It is generally thought that myofibroblasts derive from local tissue fibroblasts. However, recent evidence suggests a portion of the progenitors for these cells may arise from the bone marrow. Fibrocytes, which share both leukocyte and mesenchymal markers, are found in increased numbers in bone marrow and lung of injured mice. Fibrocytes circulate in blood and are recruited to injured sites via chemotactic signals. Studies with bone marrow chimeric and parabiotic mice suggest that fibroblasts (and in some cases myofibroblasts) arise from circulating bone marrow precursors. Chemokine and chemokine receptor interactions are critical for the recruitment of bone marrow-derived progenitors. Once fibrocytes arrive in injured tissues, local factors induce their differentiation into fibroblasts/myofibroblasts. This review will summarize the experimental findings, supporting a role for the participation of bone marrow-derived cells in animal models of lung fibrosis, and potential implications for the pathogenesis of fibrotic lung diseases.

Pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing lung disease limited to the lungs and associated with the histologic appearance of usual interstitial pneumonia (UIP) on surgical lung biopsy. The estimated prevalence in the United States is between 35,000 and 55,000 cases,and evidence suggests that the prevalence is increasing for IPF. Risk factors associated with pulmonary fibrosis include smoking, environmental exposures, gastroesophageal reflux dis-ease, commonly prescribed drugs, diabetes mellitus, infectious agents, and genetic factors. The diagnosis requires a careful history and physical examination, characteristic physiological and radiological studies, and, in some cases, a surgical lung biopsy. The natural history of IPF is not known, but evidence supports the concept of a continuum of idiopathic interstitial pneumonias that may overlap in time. Most patients with IPF succumb to respiratory failure, cardiovascular disease, lung cancer, pulmonary embolism, infection, and other health problems. The median survival time for patients with IPF is less than 3 yr. Factors that predict poor outcome include older age, male gender, severe dyspnea, history of cigarette smoking, severe loss of lung function, appearance and severity of fibrosis on radiological studies, lack of response to therapy,and prominent fibroblastic foci on histopathologic evaluation. Conventional therapy (corticosteroids, azathioprine, cyclophosphamide) provides only marginal benefit. Lung transplantation should be considered for patients with IPF refractory to medical therapy. In light of the poor prognosis and lack of response to available anti-inflammatory therapy, alternative approaches to therapy are being pursued. Emerging strategies to treat patients with IPF include agents that inhibit epithelial injury or enhance repair, anti-cytokine approaches, agents that inhibit fibroblast proliferation or induce fibroblast apoptosis, and other novel approaches.

Idiopathic pulmonary fibrosis in patients younger than 50 years

OBJECTIVE

To assess clinical, radiological, histopathologic, and prognostic differences in younger patients with idiopathic pulmonary fibrosis (IPF).

PATIENTS AND METHODS

This study consisted of patients younger than 50 years with IPF who were seen at the Mayo Clinic in Rochester, Minn, from January 1, 1994, to December 31, 2000. Clinical, radiological, and histopathologic data were abstracted from clinical records. Total lung capacity using plethysmography, vital capacity, diffusing capacity for carbon monoxide using the single-breath method, and alveolar volume using single-breath neon wash-in were measured.

RESULTS

Our study population was composed of 16 men and 6 women with a median age of 45 years (range, 28-49 years). Median survival was 2.1 years, with 1- and 2-year survival rates of 68% and 53%, respectively. Of the 22 patients, 2 were current smokers, 14 were former smokers, and 6 had never smoked. Three patients had familial pulmonary fibrosis, 21 had bibasilar inspiratory crackles, and 10 had digital clubbing. Median total lung capacity was 56.2%, vital capacity was 51.0%, diffusing capacity was 45.5%, and alveolar volume was 65.0%.

CONCLUSION

Although previous studies have suggested that younger age is a favorable prognostic factor in patients with IPF, we found that younger patients have the same poor prognosis as do older patients with this disorder. We observed no distinguishing differences in the clinical, radiological, and histopathologic features compared with those in older patients in whom the disorder is more common. Lung transplantation should be considered early in the treatment of younger patients with IPF.