Circulating cytokeratin 8:anti-cytokeratin 8 antibody immune complexes in sera of patients with pulmonary fibrosis

BACKGROUND: It has been suggested that the humoral immune system plays a role in the pathogenesis of idiopathic pulmonary fibrosis (IPF) and pulmonary fibrosis associated with collagen vascular disorders (PF-CVD). Although circulating immune complexes in patients' sera have been suggested, none of the antigens have been characterized. OBJECTIVES: The purpose of this study is to characterize the antigen of the immune complexes in patients' sera of pulmonary fibrosis. METHODS: As we previously established that one of the antibodies against A549 cells (lung alveolar type II cells) was anti-cytokeratin 8 (CK8), we confirmed the existence of anti-CK8 antibody in patients' sera by Western immunoblot. In addition, we tried to demonstrate circulating CK8:anti-CK8 immune complexes in patients' sera by Western immunoblot. Furthermore, we established an enzyme-linked immunosorbent assay to quantitate CK8:anti-CK8 immune complexes. RESULTS: In patients with pulmonary fibrosis, anti-CK8 antibodies were clearly demonstrated in sera by Western immunoblot. In addition, circulating CK8:anti-CK8 immune complexes were also clearly demonstrated by Western immunoblot. It was possible to establish ELISA to quantitate CK8:anti-CK8 immune complexes. If the cutoff value, which was determined based on the highest value of normal volunteers, was introduced, high CK8:anti-CK8 antibody complexes were demonstrated in 9 of 31 patients (29.0%) with IPF and PF-CVD. CONCLUSIONS: This is the first study to clarify the antigen of the circulating immune complex in sera of patients with IPF. These results suggest that circulating CK8:anti-CK8 immune complexes may have played a role in the process of lung injury in pulmonary fibrosis.     

Elevation of Anti-Cytokeratin 18 Antibody and Circulating Cytokeratin 18: Anti-Cytokeratin 18 Antibody Immune Complexes in Sera of Patients with Idiopathic Pulmonary Fibrosis

In this study, we hypothesize that anti-cytokeratin 18 (CK18) antibody and CK18:anti-CK18 immune complex increase in sera in patients with idiopathic pulmonary fibrosis (IPF). To prove the existence of anti-CK18 antibodies in patients' sera, bovine CK18 was stained with patients' sera using a Western blotting. In patients with IPF, anti-CK18 antibodies were clearly demonstrated in sera by Western blotting. Then, we tried to establish an enzyme-linked immunosorbent assay (ELISA) to quantify anti-CK18 antibodies and CK18:anti-CK18 immune complexes in sera of patients with IPF. Levels of anti-human CK18 antibodies in sera of patients with IPF (0.81 ± 0.31, mean ± SD) measured by ELISA were significantly high compared with that of normal volunteers (0.45 ± 0.06, p < 0.01). In addition, levels of CK18:anti-CK18 antibody complexes in patients' sera (0.64 ± 0.35, man ± SD) significantly increased compared with those of normal subjects (0.40 ± 0.10, p < 0.01). These results suggest that anti-CK18 antibody and its immune complex may have played a role in the process of lung injury in IPF. Accepted for publication 30 March 2000     

Elevated serum and BAL cytokeratin 19 fragment in pulmonary fibrosis and acute interstitial pneumonia.

Cytokeratin 19 fragment (CK19) levels in serum have already been documented as a useful tumour marker for lung cancer. In the present study, it was hypothesized that CK19 may be increased in the serum and epithelial lining fluid of the respiratory tract from patients with pulmonary fibrosis. CK19 was measured in the serum and bronchoalveolar lavage fluid (BALF) of patients with pulmonary fibrosis and the correlation between CK19 levels and clinical parameters evaluated. Nineteen patients diagnosed with idiopathic pulmonary fibrosis (IPF), eight with pulmonary fibrosis associated with a collagen vascular disorder (PF-CVD), seven patients with acute interstitial pneumonia (AIP), and 10 normal smokers as a control group were studied. CK19 levels in sera of patients with IPF and patients with PF-CVD were significantly increased compared to those of normal smokers. CK19 levels in sera of patients with AIP were significantly increased compared to those of other groups. CK19 values in the BALF of patients with pulmonary fibrosis were significantly elevated compared to those of normal smokers. CK19 values in sera charged according to the progression or improvement of the acute lung injury. Immunohistochemical study using pulmonary tissues obtained from patients with AIP demonstrated that the hyaline membrane and proliferating type II pneumocytes were stained by anti-human cytokeratin 19 antibody. These data demonstrated that the measurement of cytokeratin 19 fragment is a useful parameter to evaluate the activity of lung epithelial cell damage and repair.     

Differing Expression of Cytokines and Tumor Markers in Combined Pulmonary Fibrosis and Emphysema Compared to Emphysema and Pulmonary Fibrosis

This study aimed to explore the different pathogeneses of combined pulmonary fibrosis and emphysema (CPFE) from emphysema and pulmonary fibrosis. The levels of transforming growth factor-β₁ (TGF-β₁), vascular endothelial growth factor (VEGF), Krebs Von Den Lungen-6 (KL-6), matrix metalloproteinase-9 (MMP-9), tissue inhibitors of metalloproteinases-1 (TIMP-1), cytokeratin 19 fragment (CYFRA21-1), squamous cell carcinoma antigen (SCC), and the telomerase activity in peripheral blood were measured in 38 CPFE patients, 50 pulmonary emphysema patients, and 34 idiopathic pulmonary fibrosis (IPF) patients. The results demonstrated that the levels of VEGF and TGF-β₁ in IPF patients were significantly higher than those in emphysema patients (p < 0.05), and no significant differences were detected between CPFE patients and other two groups (p > 0.05). The levels of KL-6 and CYFRA21-1 in IPF patients were significantly higher than those in emphysema and CPFE patients (p < 0.05), and the latter had the similar levels (p > 0.05). Among the three groups, the levels of SCC, MMP-9, TIMP-1, MMP-9/TIMP-1 ratio, and telomerase activity were not different (p > 0.05). Our study showed that VEGF, TGF-β₁, KL-6, and CYFRA21-1 may play a role in the pathogenesis of pulmonary fibrosis. The lower levels of KL-6 and CYFRA21-1 in CPFE patients may be one of the reasons why these patients develop emphysema on the basis of fibrosis.     

Idiopathic Pulmonary Fibrosis is Associated with Circulating Antiepithelial Antibodies

Purpose

Idiopathic pulmonary fibrosis (IPF) is a restrictive fibrotic lung disease of uncertain etiology. Alveolar epithelial injury may be one of the inciting triggers in the pathogenesis of this disorder. We hypothesized that circulating antibodies to alveolar epithelial and endothelial cells may be involved in the pathogenesis of IPF.

Methods

Antibodies to alveolar epithelial and endothelial cells were analyzed by indirect immunofluorescence using alveolar epithelial cells (A549) and human umbilical vein endothelial cells respectively. IgG and IgM antibodies in patients’ serum were evaluated. Patterns of immunofluorescence, including membranous, cytoplasmic, and nuclear staining, were analyzed by fluorescence microscopy. The severity of immunofluorescence was divided into mild, moderate, and severe categories. Fifty-six patients (IPF?=?28, non-IPF ILD?=?9, non-ILD control?=?19) were evaluated for antiepithelial antibodies, and 28 patients (IPF?=?12, non-IPF ILD?=?3, non-ILD control?=?13) were studied for antiendothelial antibodies.

Results

Compared with control subjects, serum from IPF patients displayed significantly higher IgG binding to alveolar epithelial cells (P?=?0.041) with a membranous pattern of immunofluorescence. However, there was no significant difference in immunofluorescence with IgG on endothelial cells (P?=?0.165). In terms of IgM antibodies, there was no differential fluorescence observed for either epithelial or endothelial cells.

Conclusions

There is evidence of increased IgG antibodies directed against alveolar epithelium in IPF. These antibodies may play a significant role in the pathogenesis of this fibrotic disorder. The findings of this study suggest further evaluation of the role of immune mediated alveolar epithelial injury in IPF.     

Prognostic role of eosinophils in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) and pulmonary fibrosis associated with a collagen vascular disorder (PF-CVD) are chronic inflammatory lung disorders which may be characterized in various subgroups of patients by increased numbers of macrophages, neutrophils, lymphocytes, and/or eosinophils. Previous studies have suggested that the cell populations recovered with bronchoalveolar lavage (BAL) may be important in predicting disease progression and response to therapy. We evaluated this hypothesis in 27 patients by determining if the cell populations recovered with BAL differed between patients who improved, remained stable, or worsened in their pulmonary functions (as defined by at least a 15 percent change in forced vital capacity) over a six-month observation period. The findings suggested that BAL eosinophilia may be a marker of progressive lung disease in patients with IPF and PF-CVD.     

Lymphocyte Subsets in Lung Tissues of Non-specific Interstitial Pneumonia and Pulmonary Fibrosis Associated with Collagen Vascular Disorders: Correlation with CD4/CD8 Ratio in Bronchoalveolar Lavage

This study was designed to evaluate the distribution of lymphocyte subsets in lung specimens that were obtained by open-lung biopsy from 8 patients with idiopathic nonspecific interstitial pneumonia/fibrosis (NSIP) and 10 patients with pulmonary fibrosis associated with collagen vascular disorders (PF-CVD). Distributions of B lymphocytes, CD4-positive T lymphocytes, and CD8-positive T lymphocytes were evaluated immunohistochemically and compared with the cell composition in BALF. Correlation between CD4/CD8 ratios in bronchoalveolar lavage fluids (BALF) and CD4/CD8 ratios in lung tissues was also examined. B lymphocytes were mostly restricted in lymphoid follicles. CD4-positive T lymphocytes were observed inside and around lymphoid follicles and in the thick fibrotic wall of reconstructed alveoli with fibrosis. In contrast, CD8-positive T lymphocytes were diffusely distributed, especially in relatively thin alveoli. Correlation was weak between CD4/CD8 ratios in lung tissue and CD4/CD8 ratios in BALF. However, even in patients with very low CD4/CD8 ratios in BALF, many CD4 lymphocytes were observed in lung tissues, suggesting that CD8-positive lymphocytes diffusely distributed in thin alveolar architecture were more easily recovered in BALF than CD4-positive lymphocytes. Therefore, a low CD4/CD8 ratio in BALF may indicate that the alveolar structure was not severely reconstructed by fibrosis. This is the first report that compared lymphocyte subsets in lung tissues and in BALF. Accepted for publication: 14 November 2000     

Detection of antibodies in serum of patients with idiopathic pulmonary fibrosis against isolated rat alveolar type II cells

The serum of 2 patients suffering from idiopathic pulmonary fibrosis (IPF) repeatedly demonstrated a positive antibody reaction against rat alveolar type II cells isolated by the use of a combination of elastase and trypsin for disaggregation and a Percoll density gradient for purification. Neither of the other 8 IPF patients examined nor any of the controls showed a positive reaction. Because the 2 patients with serum antibodies against alveolar type II cells did not show any antinuclear antibodies, it is concluded that the antibodies against the surface of rat alveolar type II cells found in the serum of IPF patients may be autoantibodies involved in the pathogenesis of IPF.     

The role of anti-epithelial cell antibodies in the pathogenesis of bilateral radiation pneumonitis caused by unilateral thoracic irradiation

Two cases of bilateral radiation pneumonitis associated with unilateral thoracic irradiation against lung cancer are described. Both patients died of respiratory failure and autopsy was performed. Histologically, bilateral diffuse alveolar damage was demonstrated in both cases, associated with marked organization of hyaline membrane in one case (case 1). In addition, numerous hyperplastic type II pneumocytes which strongly expressed cytokeratins 8, 18 and 19 were observed. In both patients' sera, antibodies against cytokeratin 8, 18 and 19 were demonstrated by a Western immunoblot. The possible association between autoantibodies to cytokeratins and diffuse alveolar damage observed in patients with bilateral radiation pneumonitis are discussed.     

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.     

Idiopathic pulmonary fibrosis and high prevalence of serum antibodies to hepatitis C virus.

The prevalence of serum antibodies to hepatitis C virus (HCV) was assessed by an enzyme-linked immunosorbent assay (ELISA) in 66 patients (46 male and 20 female; mean age +/- SEM, 61.5 +/- 10.1 yr) with idiopathic pulmonary fibrosis (IPF). Nineteen (28.8%) were positive for this test. The frequency of HCV positiveness was significantly higher in the patients with IPF than in the 9,464 control subjects, whose ages were comparable with those of the patients (3.66%, p less than 0.05). Importantly, 12 of the 19 patients with IPF and positive ELISA results (63.2%) had positive results on the Chiron recombinant immunoblotting assay (RIBA), which is known to be more specific for HCV. We judged the 12 perceptible reactions as eight reactive and four indeterminate. When we examined liver function retrospectively, only two of eight patients who tested positive for the HCV had liver dysfunction, suggesting that anti-HCV positivity in IPF was not observed as a result of liver disease. These results lead us to speculate that HCV infection may play an important role in the pathogenesis of IPF, or that the sera of patients with IPF may contain some antibody against an unknown epitope and cross-react with the anti-HCV assay.     

Role of carbohydrate antigens sialyl Lewis (a) (CA19-9) in bronchoalveolar lavage in patients with pulmonary fibrosis

BACKGROUND: It has been reported that carbohydrate antigen sialyl Lewis (a) (CA19-9) levels are elevated in serum as well as in bronchoalveolar lavage fluid (BALF) of patients with pulmonary fibrosis. However, the biological significance of CA19-9 is unclear. OBJECTIVE: The purpose of the present study was to evaluate correlations between CA19-9 levels in BALF and several biochemical as well as clinical parameters in patients with pulmonary fibrosis. In addition, biological functions of CA19-9 were also examined. METHODS: We studied 24 patients with a diagnosis of pulmonary fibrosis: 16 with idiopathic pulmonary fibrosis (IPF) and 8 with pulmonary fibrosis associated with a collagen vascular disorder (PF-CVD). In BALF, carbohydrate antigens sialyl Lewis (a) (CA19-9), elastase: alpha(1)-proteinase inhibitor complex (E-PI), hepatocyte growth factor (HGF), LDH, IgG, IgA, albumin, and cell differentiation were measured. We also evaluated the effects of CA19-9 on neutrophil functions. RESULTS: CA19-9/albumin levels in BALF significantly correlated with HGF/albumin, elastase/albumin, LDH/albumin, total number of alveolar macrophages, and total number of neutrophils. Purified CA19-9 had a chemotactic activity for neutrophils. In addition, neutrophil chemotactic activity to C5a, fMLP, and interleukin 8 was significantly stimulated after incubation with purified CA19-9. Furthermore, CA19-9 increased the expression of CD15s on neutrophils. CONCLUSIONS: Our data demonstrated (i) CA19-9 in BALF correlated with other markers of inflammation in pulmonary fibrosis, and (ii) CA19-9 can modify neutrophil functions. These results suggest that CA19-9 may play a role in the process of lung injury in patients with pulmonary fibrosis.     

[Translated article] Diagnostic and Therapeutic Developments in Progressive Pulmonary Fibrosis

In addition to idiopathic pulmonary fibrosis (IPF), other diffuse interstitial lung diseases (ILD) are also associated with pulmonary fibrosis and occur in a variable proportion of patients, depending on the entity. The name given to this fibrotic component, that may progress despite treatment, is progressive pulmonary fibrosis (PPF). In this context, PPF is not an entity per se but a common clinical condition or behavior that may occur in association with different types of fibrosing diffuse ILDs, compromising patient prognosis. PPF is identified from worsening clinical, physiological, and/or radiological criteria during patient follow-up. Randomized clinical trials in patients with IPF or progressive non-IPF ILD have shown that treatment with antifibrotic drugs, either nintedanib or pirfenidone, slows progression. We are seeing the start of a new era in the clinical management of this subgroup of patients, offering the perfect opportunity for exploring still uncharted territories.     

A Case of Microscopic Polyangiitis Following Mycoplasma Infection in a Patient with MPO-ANCA Positive Pulmonary Fibrosis

BackgroundMicroscopic polyangiitis is a vasculitic disease that may result in a pulmonary renal syndrome. Anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis is strongly associated with infection.Case SummaryWe describe a case of microscopic polyangiitis that developed in a patient with MPO-ANCA positive pulmonary fibrosis following infection with mycoplasma. A renal biopsy was undertaken following the detection of microscopic hematuria during follow-up but no abnormal findings were evident. The MPO-ANCA titer increased following infection with mycoplasma pneumonia and a second renal biopsy demonstrated crescentic glomerulonephritis. The degree of pulmonary fibrosis was unaffected.DiscussionThe present case suggests that the mycoplasma infection triggered the elevation of MPO-ANCA titer and provoked glomerulonephritis in a patient with MPO-ANCA positive IPF. This case indicates the importance of testing for MPO-ANCA at the time of initial diagnosis, performing urinalysis and examining the urine sediment during follow-up and being alert to the potential onset of vasculitis in cases of pulmonary fibrosis.     

New Approaches to Modulating Idiopathic Pulmonary Fibrosis

Until recently, idiopathic pulmonary fibrosis (IPF) has been a devastating and generally fatal disease with no effective therapeutic. New developments in understanding the biology of the disease include a growing consensus that the lesions are mainly composed of cells that originated from resident fibroblasts. New developments in therapeutics include recommendations against several treatment regimes that have been previously used. On a positive note, the orally available drug pirfenidone has been approved for use in IPF in China, Japan, India, and the European Union, but not yet in the United States. Other possibilities for managing IPF include managing gastrointestinal reflux, and limiting excessive salt intake. A variety of potential therapeutics for IPF are in clinical trials; for instance, in a Phase 1b trial, intravenous injections of a recombinant version of the normal human serum protein Serum Amyloid P (SAP, also known as PTX2) improved lung function in IPF patients.     

The Aging Lung and Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is one of many clinical syndromes that are associated with aging, and is increasing in both incidence and prevalence with the rapid rise in aging populations world-wide. There is accumulating data on how the biology of aging may influence the susceptibility to lung fibrosis in the elderly. In this review, we explore some of the known “hallmarks of aging,” including telomere attrition, genomic instability, epigenetic alterations, loss of proteostasis, cellular senescence and mitochondrial dysfunction in the pathobiology of IPF. Additionally, we discuss age-associated alterations in extracellular matrix that may contribute to the development and/or progression of IPF.     

Genetics of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common form of interstitial lung disease. IPF is a complex disease, with environmental and genetic factors variably contributing to disease susceptibility and outcomes. A host of common gene variants with modest effect size impart disease risk in patients with sporadic IPF, while rare variants with large effect size influence disease risk in those with familial interstitial pneumonia. In this review, we highlight several common and rare variants underpinning IPF risk and call attention to recently published studies informing our understanding of this risk.     

Opsonic Defect in Patients with Cystic Fibrosis of the Pancreas

Cystic fibrosis of the pancreas is one of the most common inborn errors of metabolism. The high incidence of morbidity and mortality in these patients is primarily due to severe and frequent pulmonary infection. To date, no immune deficiency has been found in cystic fibrosis patients. Their sera contain normal quantities of immunoglobulins and hemolytic complement. In an assay of phagocytosis by alveolar macrophage, six out of nine sera from cystic fibrosis patients failed to support normal phagocytosis of Pseudomonas aeruginosa. This deficiency could be corrected by increasing the concentration of serum used in the assay. By contrast, their sera supported normal phagocytosis of Pseudomonas by blood polymorphonuclear leukocytes and continued to support normal phagocytosis when serum dilutions were used. Two patients with severe isolated deficiences of serum immunoglobulin A were found to have a similar defect in the alveolar macrophage assay, but normal phagocytosis by polymorphonuclear leukocytes. It is postulated that cystic fibrosis patients may have a quantitative and (or) functional defect of IgA antibodies, specific for Pseudomonas, and possibly of importance in the pathogenesis of their pulmonary disease.     

Significance of Serum Vascular Endothelial Growth Factor Level in Patients with Idiopathic Pulmonary Fibrosis

Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis, which has been implicated in the pathogenesis of fibrotic lung diseases, including idiopathic pulmonary fibrosis (IPF). The aim of this study was to examine the clinical significance of the serum VEGF level for evaluating disease severity and progression. The levels of VEGF in serum were measured in 41 patients with IPF, 14 patients with lung cancer, and 43 healthy volunteers. We measured the serum levels of CRP, LDH, KL-6, SP-D, and the parameters obtained from arterial blood gas analysis and pulmonary function tests. High-resolution computed tomography (HRCT) was performed to determine the extent of the interstitial and the alveolar opacities. The ability of each biomarker to predict disease severity was estimated by measuring the area under the receiver operating characteristic curve (AUC). The VEGF levels of IPF patients with high alveolar–arterial difference of oxygen (AaDO₂) levels were significantly elevated than those with low AaDO₂ levels and those of healthy volunteers. When examined within the IPF group, a significant positive correlation was found between the VEGF levels and the HRCT interstitial score (p = 0.027) and the KL-6 levels (p = 0.037). Among several serum biomarkers, VEGF showed the largest AUC for predicting disease severity as defined by a high AaDO₂ value. There was an inverse correlation between the baseline VEGF level and the monthly change in percent predicted vital capacity. The serum VEGF level may reflect the severity of IPF and offer clinical benefits to predict the disease’s progression.