Desquamative interstitial pneumonia is a disease characterized by massive alveolar cell proliferation and desquamation with sparse interstitial involvement. The reported case shows an unusually widespread radiographic reticulo-nodular image and abundant alveolar cells in the sputum. Functional studies reveal the expected diffusion defect with practically normal mechanical properties of the lung, in contrast with interstitial fibrosing lung diseases. On the basis of the pathological findings, especially the behaviour of alveolar cells, the individuality of this disease is discussed. We think that it is different from other diseases classed as varieties of a single disease or as different entities under the names of primary interstitial fibrosis or chronic fibrosing alveolitis.
Desquamative interstitial pneumonia (DIP) is a rare form of interstitial lung disease (ILD) commonly found among healthy smokers. ILD is a rare manifestation of systemic lupus erythematosus (SLE), and typically associated with a histopathological pattern of nonspecific interstitial pneumonia (NSIP). The present article describes an unusual case of DIP in a non-smoking patient with SLE presenting as NSIP. DIP can occur in the context of SLE in patients with a negative smoking history, and clinicians should consider lung biopsy to correctly classify ILD with unusual presentation on computed tomography scan.
Connective tissue disease; Interstitial lung disease; Lupus
The present article is the first in a series that will review selected rare lung diseases. The objective of this series is to promote a greater understanding and awareness of these unusual conditions among respirologists. Each article will begin with a case that serves as a focal point for a discussion of the pathophysiology and management of the particular condition. The first article is on lymphangioleiomyomatosis (LAM); subsequent articles will focus on pulmonary alveolar proteinosis, alpha-1-antitrypsin deficiency and primary ciliary dyskinesia.
LAM is a rare, progressive and (without intervention) often fatal interstitial lung disease that predominantly affects women of childbearing age. LAM is characterized by progressive interstitial infiltration of the lung by smooth muscle cells, resulting in diffuse cystic changes of the lung parenchyma. The molecular basis of this disorder has been delineated over the past five years and LAM is now known to be a consequence of mutations in the tuberous sclerosis genes. This knowledge, combined with advances in our understanding of the signalling pathways regulated by these genes, has given rise to potential molecular therapies that hold great promise for treating this devastating disease.
Chylothorax; Lymphatic channels; Molecular therapy; Pneumothorax; Sirolimus; Tuberous sclerosis
Postoperative exacerbation of interstitial pneumonia in patients with lung cancer and interstitial lung disease has emerged as a serious problem. Therefore, the risk factors for postoperative exacerbation of interstitial pneumonia in patients with interstitial lung disease must be identified. We analyzed 22 patients diagnosed as having lung cancer with interstitial lung disease who underwent surgical treatment at the Kitasato University Hospital. Among the patients with lung cancer and interstitial lung disease, 5 patients (22.7%) had postoperative exacerbation of interstitial pneumonia. The prognosis of the patients with postoperative exacerbation was significantly poorer than that of patients without. Patients with postoperative exacerbation had a significantly higher age (≥75 years) and a significantly lower frequency of postoperative administration of steroid than patients without postoperative exacerbation. Almost all patients with postoperative exacerbation underwent lobectomy, had elevated KL-6 levels in the serum pre-operatively, and had significantly advanced stages of disease. Of the 5 patients with postoperative exacerbation, 2 had a history of inflammation prior to their exacerbation: 1 had a common cold and the other pyothorax. In patients with lung cancer and interstitial lung disease, advanced age, advanced stage disease, no postoperative administration of steroid and a pre-operative episode of inflammation are all risk factors for postoperative exacerbation of interstitial pneumonia.
lung cancer; interstitial lung disease; postoperative exacerbation
We present a case of progressive interstitial fibrosis in a retired shipyard worker who was exposed to asbestos during the postwar era of the late 1940s and 1950s, when asbestos exposures in the workplace were not regulated. Forty years later, at 63 years of age, the patient presented with restrictive lung disease. The patient was diagnosed with asbestos-related pleural disease and parenchymal asbestosis. He remained stable for the next 7 years, but then he began to manifest rapid clinical progression, which raised the possibility of an unusual variant of asbestosis, a concomitant interstitial process, or an unrelated disease. Lung biopsy was not undertaken because of the patient's low pulmonary reserve and limited treatment options. An empiric trial of oral steroids was initiated, but his pulmonary status continued to deteriorate and he died of pulmonary failure at 72 years of age. Many diseases result in pulmonary interstitial fibrosis. Ideally, open lung biopsy should be performed, but this procedure inevitably causes complications in many patients with end-stage restrictive lung disease. Furthermore, while the presence of asbestos bodies in tissue sections is a sensitive and specific marker of asbestos exposure, neither this finding nor any other charge is a marker indicative of asbestosis or the severity of asbestosis. With the enactment of the Asbestos Standard in the United States, asbestos exposures have been decreasing in this country. However, industries that produce asbestos products and wastes continue to expand in developing countries. Prevention of asbestos-related lung disease should be a global endeavor, and asbestos exposures should be regulated in both developed and developing countries.
Clubbing is very uncommon in respiratory bronchiolitis-associated interstitial lung disease, and primarily raises the suspicion of idiopathic pulmonary fibrosis in a patient presenting with diffuse parenchymal lung disease. If idiopathic pulmonary fibrosis can be excluded, clubbing should raise the suspicion of an occult tumour.
We describe a heavy smoker presenting with dyspnea and severe clubbing. Surgical lung biopsy revealed the histologic diagnosis of respiratory bronchiolitis-associated interstitial lung disease. Respiratory bronchiolitis-associated interstitial lung disease is a distinct clinicopathologic entity within idiopathic interstitial pneumonia patients described almost exclusively in cigarette smokers. The disease is associated with a good prognosis and mild symptoms but not with clubbing. After smoking cessation the radiologic findings of interstitial lung disease improved in parallel with improvement in lung function and gas exchange. However, a central squamous cell carcinoma was detected in the follow-up.
In this case, clubbing was most probably caused by the occult tumor rather than by respiratory bronchiolitis-associated interstitial lung disease.
The reported prevalence of interstitial lung disease in patients with rheumatoid arthritis has varied from 10% to 50%, yet less than 5% of patients with arthritis develop severe fibrosing interstitial lung disease. This suggests that subclinical disease may not always presage progressive disease. Bronchoalveolar lavage fluid from patients with rheumatoid arthritis and either clinically evident interstitial lung disease or subclinical disease was examined for the presence of factors with a putative role in the development of interstitial fibrosis. Patients with subclinical disease were identified by prospective radiographic and lung function screening of 93 patients with rheumatoid arthritis. Fourteen patients were identified in this manner and an association between subclinical disease and smoking history was noted. Eleven patients with established interstitial lung disease had increased neutrophils (p less than 0.05), collagenase, and type III procollagen N terminal peptide levels (p less than 0.01) in the bronchoalveolar lavage fluid. Preliminary characterisation of the bronchoalveolar lavage collagenase suggested that it originated from neutrophils. Ten patients with subclinical interstitial lung disease underwent bronchoalveolar lavage. Of these, one had increased neutrophils and two had increased collagenase concentrations--abnormalities associated with advanced interstitial lung disease and a poor prognosis. These results suggest that in arthritis patients with evidence of subclinical pulmonary interstitial disease bronchoalveolar lavage might be useful in identifying those who may require careful monitoring in the hope that early treatment will prevent severe fibrosis.
It has become obvious that several interstitial lung diseases, and even viral lung infections, can progress rapidly, and exhibit similar features in their lung morphology. The final histopathological feature, common in these lung disorders, is diffuse alveolar damage (DAD). The histopathology of DAD is considered to represent end stage phenomenon in acutely behaving interstitial pneumonias, such as acute interstitial pneumonia (AIP) and acute exacerbations of idiopathic pulmonary fibrosis (IPF). Acute worsening and DAD may occur also in patients with nonspecific interstitial pneumonias (NSIPs), and even in severe viral lung infections where there is DAD histopathology in the lung. A better understanding of the mechanisms underlying the DAD reaction is needed to clarify the treatment for these serious lung diseases. There is an urgent need for international efforts for studying DAD-associated lung diseases, since the prognosis of these patients has been and is still dismal.
BACKGROUND: The sensitivity and accuracy of death certificates and mortality data as sources of population based data on the occurrence of interstitial lung diseases has received limited attention. To determine the usefulness of these data sources, death certificates and mortality data from patients in New Mexico were examined. METHODS: Patients with an interstitial lung disease were identified from a population based registry. For subjects who had died, diagnostic information from their death certificates and from mortality data was compared with the clinical diagnoses made before death. RESULTS: Of 385 patients with a clinical diagnosis of an interstitial lung disease, 134 died between October 1988 and August 1994. Death certificates were obtained for 96% of these patients. An interstitial lung disease was listed somewhere on the death certificate for only 46% of the patients, and as an immediate cause of death for only 15%. For the patients with an interstitial lung disease listed somewhere on the death certificate the overall concordance between the diagnoses before death and those on the death certificate was 76%. Mortality data for the State of New Mexico showed a diagnosis of interstitial lung disease to be the assigned cause of death for only 22% of the patients. The overall agreement between the diagnoses made before death and those of the state mortality data was only 21%. CONCLUSIONS: These results suggest that death certificates and state mortality data are neither sensitive nor accurate for describing the occurrence of interstitial lung diseases. This finding may partly explain the apparently low mortality rates from idiopathic pulmonary fibrosis in the USA compared with other countries.
Interstitial lung disease encompasses a diverse group of chronic lung conditions characterised by distressing dyspnoea, fatigue, reduced exercise tolerance and poor health-related quality of life. Exercise training is one of the few treatments to induce positive changes in exercise tolerance and symptoms, however there is marked variability in response. The aetiology and severity of interstitial lung disease may influence the response to treatment. The aims of this project are to establish the impact of exercise training across the range of disease severity and to identify whether there is an optimal time for patients with interstitial lung disease to receive exercise training.
One hundred and sixteen participants with interstitial lung disease recruited from three tertiary institutions will be randomised to either an exercise training group (supervised exercise training twice weekly for eight weeks) or a usual care group (weekly telephone support). The 6-minute walk distance, peripheral muscle strength, health-related quality of life, dyspnoea, anxiety and depression will be measured by a blinded assessor at baseline, immediately following the intervention and at six months following the intervention. The primary outcome will be change in 6-minute walk distance following the intervention, with planned subgroup analyses for participants with idiopathic pulmonary fibrosis, dust-related interstitial lung disease and connective-tissue related interstitial lung disease. The effects of disease severity on outcomes will be evaluated using important markers of disease severity and survival, such as forced vital capacity, carbon monoxide transfer factor and pulmonary hypertension.
This trial will provide certainty regarding the role of exercise training in interstitial lung disease and will identify at what time point within the disease process this treatment is most effective. The results from this study will inform and optimise the clinical management of people with interstitial lung disease.
Australian New Zealand Clinical Trials Registry ACTRN12611000416998
Interstitial lung diseases; Diffuse parenchymal lung diseases; Idiopathic pulmonary fibrosis; Idiopathic interstitial pneumonias; Asbestosis; Sarcoidosis; Hypersensitivity pneumonitis; Connective tissue diseases; Exercise; Rehabilitation
The aphorism that children are not little adults certainly applies for the imaging of interstitial lung disease. Acquiring motion-free images of fine pulmonary structures at desired lung volumes is much more difficult in children than in adults. Several forms of interstitial lung disease are unique to children, and some forms of interstitial lung disease encountered in adults rarely, if ever, occur in children. Meticulous attention to imaging technique and specialized knowledge are required to properly perform and interpret chest imaging studies obtained for the evaluation of childhood interstitial lung disease (chILD). This review will address technique recommendations for imaging chILD, the salient imaging findings in various forms of chILD, and the efficacy of imaging in the diagnosis and management of chILD.
Most of the interstitial lung diseases are rare, chronic, progressive and fatal disorders, especially in familial form. The etiology of the majority of interstitial lung disease is still unknown. Host susceptibility, genetic and environmental factors may influence clinical expression of each disease. With familial interstitial lung diseases, mutations of surfactant protein B and surfactant protein C or other additional genetic mechanisms (e.g. mutation of the gene for ATP-binding cassette transporter A3) could be associated. We found a 21 month-old girl with respiratory symptoms, abnormal radiographic findings and abnormal open lung biopsy findings compatible with nonspecific interstitial pneumonitis that is similar to those of her older sister died from this disease. We performed genetic studies of the patient and her parents, but we could not find any mutation in our case. High-dose intravenous methylprednisolone and oral hydroxychloroquine were administered and she is still alive without progression during 21 months of follow-up.
Lung Diseases, Interstitial; Causality; Methylprednisolone
Chronic active Epstein-Barr virus (CAEBV) infection is characterized by persistent infectious mononucleosis-like symptoms, an unusual pattern of Epstein-Barr virus (EBV) antibodies, detection of the EBV genome in affected tissues or peripheral blood, and chronic illness that cannot be attributed to any other known disease. This is the first reported Korean case of an immunocompetent adult with CAEBV-associated interstitial pneumonitis. A 28-year-old female was admitted with a fever that persisted for 3 weeks. She had multiple lymphadenopathy, hepatosplenomegaly, pancytopenia, and elevated serum aminotransferase levels. Serology for antibodies was positive and chest computed tomography showed diffuse ground glass opacities in both lungs. Histopathology of the lung tissue showed lymphocyte infiltration, and EBV DNA was detected in those lymphocytes using in situ hybridization with an EBV-encoded RNA probe. After 1 month of hospitalization, she improved without specific treatment.
Epstein-Barr virus infection; Immunocompetence; Lung diseases; Interstitial pneumonitis
Interstitial lung disease in children represents a group of rare chronic respiratory disorders. There is growing evidence that mutations in the surfactant protein C gene play a role in the pathogenesis of certain forms of pediatric interstitial lung disease. Recently, mutations in the ABCA3 transporter were found as an underlying cause of fatal respiratory failure in neonates without surfactant protein B deficiency. Especially in familiar cases or in children of consanguineous parents, genetic diagnosis provides an useful tool to identify the underlying etiology of interstitial lung disease. The aim of this review is to summarize and to describe in detail the clinical features of hereditary interstitial lung disease in children. The knowledge of gene variants and associated phenotypes is crucial to identify relevant patients in clinical practice.
interstitial lung disease; children; surfactant-protein C; ABCA3; mutations
Hamman-Rich syndrome, also known as acute interstitial pneumonia, is a rare and fulminant form of idiopathic interstitial lung disease. It should be considered as a cause of idiopathic acute respiratory distress syndrome. Confirmatory diagnosis requires demonstration of diffuse alveolar damage on lung histopathology. The main treatment is supportive care. It is not clear if glucocorticoid therapy is effective in acute interstitial pneumonia. We report the case of a 77-year-old woman without pre-existing lung disease who initially presented with mild upper respiratory tract infection and then progressed to rapid onset of hypoxic respiratory failure similar to acute respiratory distress syndrome with unknown etiology. Despite glucocorticoid therapy, she did not achieve remission and expired after 35 days of hospitalization. The diagnosis of acute interstitial pneumonia was supported by the histopathologic findings on her lung biopsy.
Rationale: Idiopathic interstitial pneumonia (IIP) and its familial variants are progressive and largely untreatable disorders with poorly understood molecular mechanisms. Both the genetics and the histologic type of IIP play a role in the etiology and pathogenesis of interstitial lung disease, but transcriptional signatures of these subtypes are unknown.
Objectives: To evaluate gene expression in the lung tissue of patients with usual interstitial pneumonia or nonspecific interstitial pneumonia that was either familial or nonfamilial in origin, and to compare it with gene expression in normal lung parenchyma.
Methods: We profiled RNA from the lungs of 16 patients with sporadic IIP, 10 with familial IIP, and 9 normal control subjects on a whole human genome oligonucleotide microarray.
Results: Significant transcriptional differences exist in familial and sporadic IIPs. The genes distinguishing the genetic subtypes belong to the same functional categories as transcripts that distinguish IIP from normal samples. Relevant categories include chemokines and growth factors and their receptors, complement components, genes associated with cell proliferation and death, and genes in the Wnt pathway. The role of the chemokine CXCL12 in disease pathogenesis was confirmed in the murine bleomycin model of lung injury, with C57BL/6CXCR4+/− mice demonstrating significantly less collagen deposition than C57BL/6CXCR4+/+ mice. Whereas substantial differences exist between familial and sporadic IIPs, we identified only minor gene expression changes between usual interstitial pneumonia and nonspecific interstitial pneumonia.
Conclusions: Taken together, our findings indicate that differences in gene expression profiles between familial and sporadic IIPs may provide clues to the etiology and pathogenesis of IIP.
familial interstitial pneumonia; global transcription analysis; interstitial lung disease; lung fibrosis; microarrays
bronchiolitis-associated interstitial lung disease (RBILD) is a rare
form of interstitial lung disease which may present in similar fashion
to other types of chronic interstitial pneumonia. The purpose of this
study was to undertake a clinicopathological review of 10 patients with
RBILD and to examine the clinical and imaging data related to its
histopathological pattern, in particular the relationship of RBILD to smoking.
out of 168 retrospectively reviewed patients, from whom biopsy
specimens were taken for suspected diffuse lung disease, were
identified with a histopathological pattern of RBILD. Three cases were
rejected as follow up data were unavailable. The 10remaining cases
constituted the study group and both clinical and imaging data were
collected from patients' notes and referring physicians.
four cases of RBILD overlapped with the pattern of desquamative
interstitial pneumonitis (DIP) and nine also had microscopic evidence
of centrilobular emphysema. Nine patients were smokers, ranging from 3 to 80 pack years. The one non-smoker had an occupational exposure to
the fumes of solder flux. The sex distribution was equal with an age
range of 32-65 years. Two patients were clubbed. Lung function tests
showed both restrictive and obstructive patterns together with severe
reductions in carbon monoxide transfer factor in seven patients. Chest
radiographs showed reticular or reticulonodular infiltrates in five
patients and a ground glass pattern in two. CT scans were consistent
with either DIP or RBILD in six of eight patients. Although seven
patients remained stable or improved, either with or without treatment, three patients deteriorated.
adds weight to the hypothesis that smoking can cause clinically
significant interstitial lung disease, with deterioration in pulmonary
function despite treatment. Given the overlapping histopathological
patterns of RBILD and DIP and their strong association with smoking,
the term "smoking related interstitial lung disease" is suggested
for those patients who are smokers.
(1) Determine the prevalence of interstitial lung disease and isolated low diffusing capacity for carbon monoxide (DLCO) in a large cohort of dermatomyositis outpatients. (2) Compare the pulmonary abnormalities of classic dermatomyositis (CDM) and clinically amyopathic dermatomyositis (CADM) patients.
Retrospective cohort study.
University hospital outpatient dermatology referral center.
Records of 91 outpatients with adult-onset dermatomyositis seen between May 26, 2006 and May 25, 2009 were reviewed.
Main Outcome Measures
Presence of interstitial lung disease on thin slice chest computed tomography (CT) scans and DLCO.
Of the 71 dermatomyositis patients who had CT or DLCO data, 23% (16/71, 95% confidence interval [CI] = 13–33%) had interstitial lung disease as defined by CT results. All interstitial lung disease patients had a reduced DLCO, and the interstitial lung disease prevalence was not different between CADM (29% [10/35]) and CDM (17% [6/36]) patients (p=0.27). Twenty-five percent (18/71, 95% CI = 15–36%) of patients (20% [7/35], CADM; 31% [11/36], CDM; p=0.41), had an isolated low DLCO in the absence of CT findings showing interstitial lung disease.
Established interstitial lung disease and isolated reductions in DLCO, which may signify early interstitial lung disease or pulmonary hypertension, are very common in both classic and clinically amyopathic dermatomyositis dermatology outpatients. As the DLCO is an inexpensive test that is sensitive for pulmonary disease, it may be appropriate to screen all dermatomyositis patients with serial DLCO measurements and base further testing on DLCO results.
Imatinibmesylate (imatinib) is a small molecule tyrosine kinase inhibitor administered to patients with chronic myelogenous leukemia and gastrointestinal stromal tumor. Although imatinib-associated interstitial lung disease is uncommon, a few cases have been reported so far. However, in all these cases interstitial lung disease developed during the use of imatinib. The present case is the first report of imatinib-induced interstitial lung disease developing after discontinuation of the drug.
A 51-year-old woman was administered oral imatinib for gastrointestinal stromal tumor. Ten weeks later, imatinib was discontinued because of facial edema. On this occasion, chest radiography showed no abnormal findings. However, 2 weeks after discontinuation of imatinib, she developed fever, dry cough, and dyspnea. Chest radiography and computed tomography showed diffuse interstitial infiltrates in both lungs. Examination of bronchoalveolar lavage fluid showed an increased proportion of lymphocytes. Imatinib-induced interstitial lung disease was suspected, because no other cause was evident. After administration of corticosteroids, her clinical condition and chest radiographic findings improved.
We report a unique case of imatinib-induced interstitial lung disease that developed 2 weeks after discontinuation of the drug. Physicians should consider occurrence of imatinib-induced interstitial lung disease even after discontinuation of the drug.
Drug-induced interstitial lung disease; Drug-induced lung injury; Drug induced pneumonitis; Drug lymphocyte-stimulating test; Imatinibmesylate
Sarcoidosis commonly presents in young adults with bilateral hilar lymphadenopathy, lung parenchymal disease and/or skin lesions. Ocular symptoms are the presenting feature in up to 10% of cases, but eye involvement can be demonstrated in around a quarter of all patients. Renal disease is much rarer, and may manifest with hypercalcaemic nephropathy, granulomatous interstitial nephritis, tubular dysfunction or glomerulonephritis. Eye and renal involvement are rarely found together, and may be confused with Wegener's granulomatosis or polyarteritis. We report a case of a young man who developed renal failure due to sarcoidosis soon after presenting with uveitis. The case illustrates an unusual combination of systemic features that may not be widely recognized.
The pandemic of swine flu (H1N1) influenza spread to involve the whole world rapidly. Many patients manifested a mild clinical illness but some developed pneumonia and respiratory failure. High mortality was observed in patients with severe disease. Among survivors, studies are limited. Ground-glass opacities on a high-resolution computerized tomography scan and reduced diffusion capacity were noted after 3 months in a study. But long-term complications in patients with swine flu pneumonia have not been studied well. We are presenting an unusual case of swine flu pneumonia who developed interstitial lung disease after recovery.
Complications; diffuse parenchymal lung disease; Influenza A virus H1N1 subtype; pulmonary fibrosis
Interstitial lung disease is a frequent complication in sickle cell disease and is characterized by vascular remodeling and interstitial fibrosis. Bone marrow-derived fibrocytes have been shown to contribute to the pathogenesis of other interstitial lung diseases. The goal of this study was to define the contribution of fibrocytes to the pathogenesis of sickle cell lung disease.
Fibrocytes were quantified and characterized in subjects with sickle cell disease or healthy controls, and in a model of sickle cell disease, the NY1DD mouse. The role of the chemokine ligand CXCL12 in trafficking of fibrocytes and phenotype of lung disease was examined in the animal model. We found elevated concentration of activated fibrocytes in the peripheral blood of subjects with sickle cell disease, which increased further during vaso-occlusive crises. There was a similar elevations in the numbers and activation phenotype of fibrocytes in the bone marrow, blood, and lungs of the NY1DD mouse, both at baseline and under conditions of hypoxia/re-oxygenation. In both subjects with sickle cell disease and the mouse model, fibrocytes expressed a hierarchy of chemokine receptors, with CXCR4 expressed on most fibrocytes, and CCR2 and CCR7 expressed on a smaller subset of cells. Depletion of the CXCR4 ligand, CXCL12, in the mouse model resulted in a marked reduction of fibrocyte trafficking into the lungs, reduced lung collagen content and improved lung compliance and histology.
These data support the notion that activated fibrocytes play a significant role in the pathogenesis of sickle cell lung disease.
Although the relationship between muscle strength and exercise capacity has been demonstrated in dermatomyositis without lung dysfunction, little is known about the association between exercise capacity and interstitial lung disease in dermatomyositis. Eleven patients with dermatomyositis with interstitial lung disease without the manifestation of muscle weakness and 12 patients with idiopathic interstitial pneumonia underwent the 6-minute walk test (6MWT). PaO2, creatine kinase, percentage predicted 6MWT distance (6MWD%), and SpO2 at rest were similar between patients. Percentage predicted vital capacity, carbon monoxide diffusing capacity (DLCO%), and SpO2 after 6MWT were higher and exertional dyspnea was lower in patients with dermatomyositis than in patients with idiopathic interstitial pneumonia. SpO2 after 6MWT was positively correlated with 6MWD% in patients with dermatomyositis, while DLCO% and PaO2 were positively correlated with 6MWD% in patients with idiopathic interstitial pneumonia. Lung dysfunction in dermatomyositis might not be a major limitation factor in exercise capacity.
dermatomyositis; interstitial lung disease; exercise capacity; idiopathic interstitial pneumonia
The pulmonary macrophagic system is critical to the defense of the lung, keeping the alveoli clean and sterile and responding on demand with an adaptive outpouring of new cells into the air sacs. Under basal conditions alveolar macrophages, in common with other mononuclear phagocytes, are derived from the bone marrow. A population of macrophage precursors within the pulmonary interstitium provides a reserve pool capable of proliferation and delivery of phagocytes in response to unusually heavy loads of inhaled particles. This reserve system also produces macrophages when monocytic precursors in the bone marrow are depleted by diseases such as leukemia. The alveolar macrophage is destined to ingest particulate matter and to be eliminated along the mucociliary pathway; clearance by lymphatics is of minor importance and macrophages probably do not recross the alveolar epithelium to reach the pulmonary interstitial compartment. Although the protective role of the macrophage is dominant, this cell may participate, directly or indirectly, in the genesis of two major groups of chronic pulmonary disease, interstitial fibrosis and emphysema. Such inappropriate responses involve interactions with fibroblastic cells and tissue injury initiated by proteases secreted by the macrophage.
Antibodies to aminoacyl-tRNA synthetases (anti-Jo-1, anti-PL-7, anti-PL-12) have been found in the serum of some patients with polymyositis (PM). Patients with these antibodies have an unusually high rate of interstitial lung disease (ILD) in association with their PM. Two patients (K.J. and B.T.) with severe ILD and PM were found to have antibodies to a cytoplasmic antigen, but tests to determine whether the antigen was an aminoacyl-tRNA synthetase were negative, including tests of KJ serum for inhibitory effects on the 20 synthetases. KJ immunoprecipitates did not contain tRNA, in contrast to antisynthetase sera. When IgG samples were added to a reticulocyte in vitro translation system at a concentration of 0.3 mg/ml, KJ IgG inhibited globin mRNA translation by 98%, while anti-Jo-1 IgG inhibited 62% and normal IgG had little effect. Thus, both anti-KJ and the antisynthetases are directed at antigens that are involved in translation and protein synthesis, and both are associated with the syndrome of lung disease and PM. This syndrome may be associated with antibodies to translation-related proteins in general, which may have implications for the link of PM and enteroviruses, which are mRNA viruses.