Pulmonary fibrosis

Kathon Induces Fibrotic Inflammation in Lungs: The First Animal Study Revealing a Causal Relationship between Humidifier Disinfectant Exposure and Eosinophil and Th2-Mediated Fibrosis Induction

Currently available toxicity data on humidifier disinfectants are primarily limited to polyhexamethylene guanidine phosphate-induced lung fibrosis. We, therefore, investigated whether the sterilizer component Kathon, which is a mixture of chloromethylisothiazolinone and methylisothiazolinone, induces fibrotic lung injury following direct lung exposure in an animal model. Mice were intratracheally instilled with either the vehicle or Kathon. Differential cell counts, cytokine analysis, and histological analysis of lung tissue were then performed to characterize the injury features, and we investigated whether Kathon altered fibrosis-related gene expression in lung tissues via RNA-Seq and bioinformatics. Cell counting showed that Kathon exposure increased the proportion of macrophages, eosinophils, and neutrophils. Moreover, T helper 2 (Th2) cytokine levels in the bronchoalveolar lavage were significantly increased in the Kathon groups. Histopathological analysis revealed increased perivascular/alveolar inflammation, eosinophilic cells, mucous cell hyperplasia, and pulmonary fibrosis following Kathon exposure. Additionally, Kathon exposure modulated the expression of genes related to fibrotic inflammation, including the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway, extracellular signal regulated kinase (ERK)1 and ERK2 cascade, extracellular matrix (ECM)-receptor interaction pathway, transforming growth factor beta receptor signaling pathway, cellular response to tumor necrosis factor, and collagen fibril organization. Our results suggest that Kathon exposure is associated with fibrotic lung injury via a Th2-dependent pathway and is thus a possible risk factor for fibrosis.

Drug-Induced Lung Toxicity

The number of blood-borne chemotherapeutic agents implicated in drug-induced lung toxicity continues to increase, although problems in detection remain. The initiation of drug-induced lung injury can have an immunologic or nonimmunologic basis. If endothelial cells are injured, interstitial pulmonary edema may result. Regardless of the source of injury, the progression of drug-induced lung toxicity is often quite similar, involving (1) parenchymal damage, (2) recruitment of inflammatory cells, and (3) progression of the inflammatory process. If the inflammatory reponse is sufficiently severe and disperse, increased collagen can be deposited in interstitial and intra-alveolar areas. The resulting attenuation of gas exchange can induce dyspnea and possibly death. Recent research suggests mediation of the fibrogenic process via cytokines such as transforming growth factor-β and tumor necrosis factor. Preliminary results demonstrating amelioration of cytokine mediated lung-induced fibrosis in animal models with appropriate antibodies suggest a possible future modality of therapy. Certain amphiphilic drugs are capable of eliciting a more specific form of lung toxicity. This class of drugs can interfere with phospholipid metabolism in pulmonary macrophages. In these cases, phospholipidosis results from phospholipid accumulation. The physiologic sequelae in human phospholipidosis is still uncertain.

Differential diagnosis of eosinophilic chronic rhinosinusitis

Eosinophilic chronic rhinosinusitis (ECRS) encompasses a wide variety of etiologies. To date, a unifying pathophysiologic mechanism remains elusive. Eosinophilia is frequently, but not exclusively, caused by immunoglobulin (Ig)E-mediated hypersensitivity and is dominated by the associated cytokine milieu of Th2 inflammation. The provisional subcategories of ECRS include superantigen-induced eosinophilic chronic rhinosinusitis, allergic fungal sinusitis, nonallergic fungal eosinophilic chronic rhinosinusitis, and aspirin-exacerbated eosinophilic chronic rhinosinusitis. Within each subcategory, recent findings supporting distinct mechanisms that promote eosinophilic infiltration are presented, and, therefore, targeted therapeutic interventions with specific antibacterial, antifungal, or immune modulation may be indicated.

A case of completely resolved pneumatocoeles in desquamative interstitial pneumonia

Desquamative interstitial pneumonia (DIP), also known as alveolar macrophage pneumonia (AMP), represents a subset of idiopathic interstitial pneumonia that responds better to steroids and has a more favourable prognosis than usual interstitial pneumonia. Recently, we encountered a case of DIP with the formation of multiple pulmonary cysts during corticosteroid maintenance treatment. After the introduction of cyclophosphamide, the cysts gradually disappeared. This complete resolution is believed to have resulted from the clearance of check-valve-like bronchiolar obstructions that may be another interesting terminal airway pathology in DIP.

Fibrosis in hypertensive heart disease: role of the renin-angiotensin-aldosterone system

Structural homogeneity of cardiac tissue is governed by mechanical and humoral factors that regulate cell growth, apoptosis, phenotype, and extracellular matrix turnover. ANGII has endocrine, autocrine, and paracrine properties that influence the behavior of cardiac cells and matrix by AT1 receptor binding. Various paradigms have been suggested, including ANGII-mediated up-regulation of collagen types I and III formation and deposition in cardiac conditions, such as HHD. A growing body of evidence, however, deals with the potential role of aldosterone, either local or systemic, in inducing cardiac fibrosis. Aldosterone might also mediate the profibrotic actions of ANGII. To reduce the risk of heart failure that accompanies HHD, its adverse structural remodeling (eg, myocardial hypertrophy and fibrosis) must be targeted for pharmacologic intervention. Cardioprotective agents must reverse not only the exaggerated growth of cardiac cells, but also regress existing abnormalities in fibrillar collagen. Available experimental and clinical data suggest that agents interfering with ACE, the AT1 receptor, or the mineralocorticoid receptor may provide such a cardioprotective effect.

Relationship between the eosinophilia of bronchoalveolar lavage fluid (BALF) and the severity of pulmonary fibrosis induced by bleomycin in rats

A large number of studies have demonstrated that the presence of eosinophils in the lungs of patients with pulmonary fibrosis correlates with poor prognosis or resistance to therapy. However, direct evidence of the relationship between the influx of eosinophil and pulmonary fibrosis has not yet been described experimentally. In this article, pulmonary fibrosis was induced by different doses of bleomycin (BLM) and using different aged rats. On selected days afterwards, the lungs were lavaged and harvested for analyzing fibrosis, eosinophil influx and cytokine expression. There was a significant relationship between eosinophilia and the pulmonary fibrosis (r=0.98, p<0.01). In spite of the fact that there was no significant increase in hydroxyproline of the lung, eosinophil influxes of bronchoalveolar lavage fluid (BALF) was maximal 7 d after BLM administration. Moreover, there were similar patterns among transforming growth factor beta (TGF)-beta(1), hepatocyte growth factor (HGF) and eosinophil influx of BALF in that they were dependent on dose of BLM and age. These findings, taken together, have suggested the causal correlation of eosinophilia during the early stage with subsequent pulmonary fibrosis. The possible role of eosinophils in the pathogenesis of pulmonary fibrosis might contribute to not only TGF-beta(1) but also HGF production.

Classification of idiopathic interstitial pneumonias: making sense of the alphabet soup

Since Liebow and Carrington's original classification of idiopathic interstitial pneumonias, there have been controversies over which histological patterns should be included and how they relate to clinicopathological diseases such as cryptogenic fibrosing alveolitis/idiopathic pulmonary fibrosis (CFA/IPF). Because of these differences and the wealth of overlapping terminology, a consensus classification system has been proposed, devised by a group of clinicians, radiologists and pathologists. Seven histological patterns are recognized: usual interstitial pneumonia (UIP), non-specific interstitial pneumonia (NSIP), diffuse alveolar damage (DAD), organizing pneumonia (OP), desquamative interstitial pneumonia (DIP), respiratory bronchiolitis (RB) and lymphocytic interstitial pneumonia (LIP), each with a clinicopathological counterpart, the most well defined being UIP and CFA/IPF. The system is applicable both in terms of the pathologist identifying histological patterns in isolation and in terms of the pathologist's role in contributing to the final clinicopathological diagnosis. It will probably provide greater consistency in diagnosis, early studies suggesting that the system is reproducible, and also identify purer cohorts for studies investigating causation. It also highlights the fact that the 'gold standard for diagnosis' is no longer a surgical lung biopsy in isolation but more the clinicopathological conference, when clinical, imaging and histological data are jointly discussed to produce the final clinicopathological diagnosis.

The prognostic significance of the histologic pattern of interstitial pneumonia in patients presenting with the clinical entity of cryptogenic fibrosing alveolitis

Lone cryptogenic fibrosing alveolitis (CFA) is a progressive interstitial lung disease, with a median survival of 3 to 6 yr from the onset of dyspnea. CFA can be subdivided into prognostically significant histopathologic patterns, including nonspecific interstitial pneumonia (NSIP). We reviewed 78 patients with a clinicopathologic diagnosis of CFA, biopsied between 1978 and 1989, to evaluate the prevalence and prognostic significance of these histopathologic patterns, in particular NSIP. Biopsy appearances were reclassified by two pulmonary histopathologists as usual interstitial pneumonia (UIP) (47%), NSIP (36%), or desquamative interstitial pneumonia (DIP)/respiratory bronchiolitis-associated interstitial lung disease (RBILD) (17%). The kappa coefficient of agreement between pathologists was 0.49. In 67 cases, follow-up was complete to death or 10 yr after biopsy, with 50 deaths during a median follow-up of 42 mo (UIP, 89%; NSIP, 61%, DIP/RBILD, 0%). Survival was highest in DIP/RBILD and higher in NSIP than UIP, p < 0.0005. When analysis was confined to patients with UIP or NSIP, the mortality of UIP remained higher, p < 0.01, but the 5-yr survival in patients with fibrotic NSIP was only 45%, indicating that this histologic appearance is often associated with a poor outcome. A response to treatment was more frequent in DIP/RBILD than in NSIP (p < 0.01) or UIP (p < 0.0005). This study confirms the prognostic value of subclassifying patients with CFA according to histopathologic pattern. However, in patients with clinically typical CFA, a histologic diagnosis of fibrotic NSIP needs to be interpreted with caution and does not necessarily denote a good outcome.

High-Resolution Computed Tomography and Survival in Fibrosing Alveolitis

High-resolution computed tomography findings were reviewed in 32 patients with cryptogenic fibrosing alveolitis and 18 with fibrosing alveolitis associated with connective tissue diseases (other than scleroderma). The percentage of abnormal lung, total ground-glass attenuation, ground-glass attenuation not associated with fibrosis, and fibrosis (reticular pattern and honeycombing) were compared with lung function and survival. In cryptogenic fibrosing alveolitis, 1-year mortality tended to be higher in patients with predominantly fibrotic lesions (39%) compared to mainly ground-glass attenuation (11%). Similar results were obtained in fibrosing alveolitis associated with connective tissue disease (1-year mortality 44% for fibrosis versus 22% for ground-glass attenuation), but the differences were not statistically significant. In cryptogenic fibrosing alveolitis, the extent of abnormal lung on initial computed tomography was 67% ± 20% in survivors at 1 year and 86% ± 8% in nonsurvivors (p < 0.005); this difference was still significant at 4 years. In fibrosing alveolitis associated with connective tissue disease, the degree of lung involvement between survivors and nonsurvivors was different at 1 year only, thus other factors seem to determine survival. Ground-glass attenuation associated with fibrosis adversely affected survival in cryptogenic fibrosing alveolitis, in contrast to isolated ground-glass attenuation.

Instability of bronchial epithelium in chronic pulmonary diseases

Pathomorphological examination of large bronchi in patients with occupational diseases, lung cancer, and in subjects exposed to radiation revealed structural and functional heterogeneity of the epithelium: the presence of focal atrophy, metaplasia, hyper- and dysplasia in the same biopsy specimen. This phenomenon was termed as instability of the epithelium. Thickness of the epithelium greatly varied, especially, in neoplastic processes. Atrophy and epithelial instability phenomenon are interpreted as morphological markers of ecological and oncological risk.

Fulminant desquamative interstitial pneumonitis

A previously well, 48-year-old female presented with a short history of respiratory distress and fever for which no cause could be found. Open lung biopsy was not contributory. She died within nine days of presentation of hypoxia and multi-organ failure. Post mortem examination revealed the pattern of desquamative interstitial pneumonitis.

Differentiation of desquamative interstitial pneumonia (DIP) from pulmonary adenocarcinoma by immunocytochemistry

AIM

After a misdiagnosis of pulmonary adenocarcinoma as desquamative interstitial pneumonia (DIP), we investigated whether immunohistochemical markers could differentiate these conditions.

METHODS AND RESULTS

Three cases of DIP and one pulmonary adenocarcinoma masquerading as DIP were studied by light and electron microscopy. All cases were mucin-negative. The cases of DIP were CD68 positive but cytokeratin-negative. The adenocarcinoma was cytokeratin-positive (AE1/3 and CAM5.2), as well as showing some CD68-positive cells. Markers for carcinoma (CEA, Ber-EP4, and Leu M1) were negative in all cases. Ultrastructurally the adenocarcinoma appeared to be derived from Type II pneumocytes.

CONCLUSION

Before a diagnosis of DIP is made, cytokeratin markers should be used.

Disease progression in usual interstitial pneumonia compared with desquamative interstitial pneumonia. Assessment with serial CT

OBJECTIVE

To determine the outcome of areas of ground-glass attenuation and assess disease progression on serial high-resolution CT (HRCT) scans of patients with biopsy specimen-proved usual interstitial pneumonia (UIP) and desquamative interstitial pneumonia (DIP).

MATERIALS AND METHODS

Twelve patients with biopsy specimen-proved UIP and 11 patients with biopsy specimen-proved DIP who had initial and follow-up HRCT scans (median interval, 10 months) were reviewed. Eleven patients with UIP and 11 with DIP received treatment between the initial and follow-up CT scans. The scans were evaluated for the presence and extent of ground-glass attenuation, irregular linear opacities and honeycombing, and overall extent of parenchymal involvement.

RESULTS

On initial CT scans, all 12 patients with UIP had areas of ground-glass attenuation (mean +/- SD extent, 30 +/- 16%) and irregular lines (mean +/- SD extent, 17 +/- 7%) and 10 patients had honeycombing (mean +/- SD extent, 10 +/- 6%). All 11 patients with DIP had areas of ground-glass attenuation on initial HRCT scans (mean +/- SD extent, 51 +/- 26%), 5 patients had irregular linear opacities (mean +/- SD extent, 5 +/- 5%), and 1 patient had honeycombing. Nine of the 12 patients with UIP showed increase in the extent of ground-glass attenuation (n = 6) or progression to irregular lines (n = 2) or honeycombing (n = 4) on follow-up as compared with only 2 patients with DIP who showed progression to irregular lines (n = 1) or honeycombing (n = 1) (p < 0.01 chi 2 test).

CONCLUSION

In patients with UIP, areas of ground-glass attenuation usually increase in extent or progress to fibrosis despite treatment. Areas of ground-glass attenuation in most patients with DIP remain stable or improve with treatment.

Co-expression of TNF alpha and IL-1 beta in human acute pulmonary fibrotic diseases: an immunohistochemical analysis

To clarify the involvement of TNF alpha and IL-1 beta in the initiation of fibrotic lung diseases, their localization was examined by immunohistochemistry. Fibrotic lung diseases observed were classified into acute and old pulmonary fibrotic changes. The acute fibrotic changes included adult respiratory distress syndrome, acute interstitial pneumonia and idiopathic pulmonary fibrosis with acute exacerbation. Acute pulmonary fibrotic changes histopathologically corresponded to a mixture of the exudative and proliferative phases of diffuse alveolar damage. Both TNF alpha and IL-1 beta were positive in the alveolar macrophages and proliferating type II pneumocytes in acute fibrotic changes. In contrast, positive cells for TNF alpha and IL-1 beta were sparse in the areas of old fibrotic change and in the normal tissue. These findings suggest that TNF alpha and IL-1 beta play an important role in the initiation of pulmonary fibrotic responses and in the architectural remodeling, irrespective of the etiology of fibrotic lung diseases.

High-resolution CT and pulmonary function tests in collagen vascular disease: comparison with idiopathic pulmonary fibrosis

To estimate whether the lung abnormalities seen in collagen vascular diseases (CVD) were similar or distinct to those seen in idiopathic pulmonary fibrosis (IPF), and to ascertain whether the extent of the abnormalities on high-resolution CT (HRCT) correlated with pulmonary function, we reviewed HRCT findings and pulmonary function test results of 64 patients with either CVD (n = 55) or IPF (n = 9). Response to corticosteroid treatment was also evaluated in 20 of the 64. High incidence of honeycomb lesion was observed in IPF (9/9, 100%) and in progressive systemic sclerosis (PSS) (11/14, 79%). CVD, except for PSS, had a low incidence of honeycomb lesion (27%). On the other hand, incidence of ground-glass shadow in CVD (47/55, 85%) was the same as that in IPF (8/9, 89%). Diffusing capacity significantly correlated with the extent of all parenchymal abnormalities in all CVD and IPF, with honeycomb lesion in PSS, and with ground-glass shadow or air-space consolidation in CVD except for PSS (r < -0.7, P < 0.001). In all 15 cases in which corticosteroid therapy was effective, no honeycomb lesions were seen. Collagen vascular disease, except for PSS, had a different pattern of disease than IPF. The morphologic changes seen on HRCT correlated well with pulmonary function in CVD.

Anchorage-independent colony growth of pulmonary fibroblasts derived from fibrotic human lung tissue

Fibroblast heterogeneity is known to exist in chronically inflamed tissue such as pulmonary fibrosis (IPF) and scleroderma. We have previously shown differences in proliferation rates in primary lines and cloned lines of fibroblasts derived from IPF tissue compared with normal lung. In this study, we report that cell lines derived from fibrotic tissue demonstrate anchorage-independent growth in soft agarose culture whereas normal lung fibroblast lines do not. We also show that fibroblast lines derived from neonatal lung tissue form colonies at about the same frequency as the fibrotic cells. Colonies from both fibrotic and neonatal lines were shown to be positive for vimentin, laminin, fibronectin, fibronectin receptor, beta-actin, and tropomyosin by immunohistochemistry but were negative for desmin, keratin, Factor VIII, alpha-smooth muscle cell actin, and tenascin. Treatment with cytokines TGF-beta and PDGF or with corticosteroid modified the colony-forming capacity of fibrotic and neonatal cell lines, however, none of these treatments induced normal lung cell lines to form colonies. The presence of cells in adult fibrotic tissue with growth characteristics similar to those exhibited by neonatal cells is further evidence of fibroblast heterogeneity and suggests newly differentiated fibroblasts may be prevalent in fibrotic tissue and contribute directly to the matrix disorder seen in this disease.

Endocrine cells in diffuse pulmonary fibrosis

BACKGROUND

There is evidence to suggest, particularly from studies in animals, that the products of pulmonary endocrine cells, especially gastrin releasing peptide, may have a role in the pathogenesis of fibrosis in the lung. This study was carried out to examine the morphology, number, distribution, and content of pulmonary endocrine cells in tissue from 49 patients with diffuse pulmonary fibrosis.

METHODS

Twenty patients with interstitial pneumonitis, 17 with early fibrosis, and 12 with frank honeycombing were studied, together with five age matched controls without pulmonary disease. Endocrine cells were immunolabeled by the avidin-biotin complex method for two general markers (protein gene product 9.5 and neuron specific enolase) and a range of normal and aberrant secretory products.

RESULTS

In the early stages, characterised by vigorous pneumonitis, endocrine cells were normal in appearance and distribution but very few in number. They contained only those secretory products normally found in such cells in health; inappropriate substances were not seen. By the time of early fibrosis endocrine cells were even fewer. None were identifiable in the lungs affected by honeycombing, despite the fact that all contained intact, well preserved epithelium.

CONCLUSIONS

It seems unlikely that the products of pulmonary endocrine cells can have any role in the pathogenesis of diffuse pulmonary fibrosis in man, the diminution in their number with advancing fibrosis probably reflecting their loss simply as a consequence of generalised epithelial damage.

Antibodies to topoisomerase II in idiopathic pulmonary fibrosis

Antibodies to DNA topoisomerase II (anti-topoisomerase II) were detected by ELISA in the sera of 18 out of 41 (44%) patients with idiopathic pulmonary fibrosis (IPF). Follow-up sera were also obtained from 19 of the patients. DNA topoisomerase II binding remained constantly high or low in the majority of follow-up sera, but 2 out of the 8 positive cases became negative while 3 out of the 11 negative cases became positive during follow-up. No association was found between occurrence of anti-topoisomerase II antibodies and any indices of disease severity. Furthermore, individual patient follow-up did not show any correlation between changes in topoisomerase II binding and deterioration or improvement of clinical status. In conclusion our study shows that although anti-topoisomerase II are detectable in a large fraction (approximately 50%) of IPF patients and are useful for diagnostic purposes, they do not provide a measure of clinical activity.

Biosynthetic and proliferative characteristics of tubulointerstitial fibroblasts probed with paracrine cytokines

Fibroblasts in parenchymal organs potentially contribute extracellular matrix to local fibrogenic processes. This contribution, in some circumstances, may be initiated by cytokines disseminated from inflammatory lesions. Different populations of fibroblasts, however, might respond distinctively to this cytokine bath depending on the microenvironment in which they reside. We have begun to explore this issue using syngeneic, low-passage fibroblasts cultured in serum-free media that were derived originally from the dermis (DFBs) and from tubulointerstitium (TFBs) of the kidney. Our findings indicate that, while fibroblasts from each compartment appear similar at the ultrastructural level, there are a variety of functional differences which distinguish their proliferative response, and their collagen secretory response (types I, III, IV, and V) following challenge with various doses of immune-relevant cytokines (TGF beta, EGF, IL-1, IL-2 and gamma IFN) in culture. DFBs, for example, express more surface EGF receptors than do TFBs, and, as a consequence, exhibit a more robust proliferative response to EGF in serum-free media. Unstimulated DFBs also secrete more collagen types I and III than TFBs, while unstimulated TFBs secrete more types IV and V. The expression of these collagens in TFBs was confirmed by Northern blot hybridization. When these sets of fibroblasts were further stimulated by cytokines, some of the cytokines not only differentially effect the secretion of various species of collagens within the same group of cells, but also between cells from populations which are anatomically distinct. DFBs, furthermore, at mid-level doses of cytokine, demonstrated a general trend towards less secretion of all types of collagen (particularly for TGF beta, EGF, and IL-2), while TFBs seemed less repressive. In TFBs the cytokine-induced responses for collagen types I and III tended to be discordant, and for types I and IV EGF inhibited, while TGF beta stimulated the secretory process. These findings speak collectively for the presence of a functional heterogeneity among organ-based populations of syngeneic fibroblasts in normal tissues.