Association between Pepsin in Bronchoalveolar Lavage Fluid and Prognosis of Chronic Fibrosing Interstitial Lung Disease.

Chronic fibrosing interstitial lung disease (ILD)s are characterized by chronic progressive fibrosis of lung which include idiopathic pulmonary fibrosis (IPF), nonspecific interstitial pneumonia (NSIP), and connective tissue disease-associated interstitial lung disease (CTD-ILD). IPF is an irreversible fibrotic lung disease which results in respiratory failure. Although NSIP and CTD-ILD can be improved or stable by treatment with corticosteroid or immunosuppressant, some of them progress to fibrotic lung diseases. Aspiration of gastric contents is suggested as an aggravating factor of ILDs. We measured pepsin, a marker of gastric aspiration, in bronchoalveolar lavage (BAL) fluid of chronic fibrosing ILD patients to evaluate the association between BAL fluid pepsin and prognosis of chronic fibrosing ILDs. Patients with chronic fibrosing ILDs, who underwent bronchoscopy between December 2010 and April 2015 were prospectively enrolled. Pepsin levels were measured using a commercial ELISA kit. Clinical characteristics, lung function data, and mortality were analyzed. Fifty-one patients with chronic fibrosing ILDs were enrolled (26 with IPF, 15 with NSIP, and 10 with CTD-ILD). Pepsin levels in BAL fluid were 69.87 ± 74.16 ng/mL in IPF, 110.68 ± 94.93 ng/mL in NSIP, and 101.87 ± 88.44 ng/mL in CTD-ILDs. There were no statistically significant differences in BAL fluid pepsin levels among patients with the different chronic fibrosing ILDs. In multivariate regression analysis, higher BAL pepsin levels were associated with higher mortality (adjusted odds ratio [aOR] = 1.021, p = 0.025). BAL fluid pepsin may be used as a prognostic marker for predicting mortality in chronic fibrosing ILD patients.

Therapeutic plasma exchange in antisynthetase syndrome with severe interstitial lung disease.

Antisynthetase syndrome (ASS) is a rare condition characterized by interstitial lung disease (ILD), inflammatory myositis, fever, Raynaud phenomenon, mechanic's hand, and inflammatory polyarthritis in the setting of antibodies to amino acyl-transfer RNA synthetases, with anti-Jo-1 antibody being the most common. Prognosis is very poor especially when there is associated ILD. To date, there is no standardized treatment for ILD associated ASS. Therapy is based on the use of steroids alone or in combination with other immunosuppressive agents, especially in severe or refractory cases. The role of therapeutic plasma exchange (TPE) in the management of this rare condition has not been established. Here, we report a case of severe ILD associated ASS in a 41-year-old woman who did not show clinical or laboratory response after six doses of high dose steroids and a dose of IV cyclophosphamide. Because of the aggressive nature of her disease and poor prognostic indices present, a decision was made to add TPE to her treatment. She underwent five sessions of TPE. At the end of the 5th session, the anti-Jo-1 antibody levels dropped to 3.6 AI (antibody index) and her creatinine kinase (CK) level from 875 to 399 U L(-1) (Units per liter) with overall improvement in her respiratory status. This case suggests TPE may be a promising treatment option in patients with ILD associated ASS refractory to steroids and other immunosuppressive therapy, particularly those with severe disease.

Chitinase 1 is a biomarker for and therapeutic target in scleroderma-associated interstitial lung disease that augments TGF-ß1 signaling.

Interstitial lung disease (ILD) with pulmonary fibrosis is an important manifestation in systemic sclerosis (SSc, scleroderma) where it portends a poor prognosis. However, biomarkers that predict the development and or severity of SSc-ILD have not been validated, and the pathogenetic mechanisms that engender this pulmonary response are poorly understood. In this study, we demonstrate in two different patient cohorts that the levels of chitotriosidase (Chit1) bioactivity and protein are significantly increased in the circulation and lungs of SSc patients compared with demographically matched controls. We also demonstrate that, compared with patients without lung involvement, patients with ILD show high levels of circulating Chit1 activity that correlate with disease severity. Murine modeling shows that in comparison with wild-type mice, bleomycin-induced pulmonary fibrosis was significantly reduced in Chit1⁻/⁻ mice and significantly enhanced in lungs from Chit1 overexpressing transgenic animals. In vitro studies also demonstrated that Chit1 interacts with TGF-ß1 to augment fibroblast TGF-ß receptors 1 and 2 expression and TGF-ß-induced Smad and MAPK/ERK activation. These studies indicate that Chit1 is potential biomarker for ILD in SSc and a therapeutic target in SSc-associated lung fibrosis and demonstrate that Chit1 augments TGF-ß1 effects by increasing receptor expression and canonical and noncanonical TGF-ß1 signaling.

Pilot study of interleukin-27 in pathogenesis of dermatomyositis and polymyositis: associated with interstitial lung diseases.

OBJECTIVE: To determine whether interleukin (IL)-27 is involved in dermatomyositis (DM) and polymyositis (PM). METHODS: Serum IL-27, IL-18 and interferon-γ (IFN-γ) levels in 37 DM and 15 PM were detected by enzyme-linked immunosorbent assay (ELISA). RESULTS: Serum IL-27, IL-18 and IFN-γ levels were significantly higher in DM and PM patients than in healthy controls. Significant higher levels of IL-27 were found in high creatine kinase (CK) level group and in patients with interstitial lung disease (ILD). Level of IL-27 was correlated with global 100-mm visual analog scales (VASs) score in patients with PM. CONCLUSION: These data supports the hypothesis that IL-27 maybe involved in DM and PM pathogenesis.

A therapeutic role for matrix metalloproteinase inhibitors in lung diseases?

Disruption of the balance between matrix metalloproteinases (MMPs) and their endogenous inhibitors is considered a key event in the development of pulmonary diseases such as chronic obstructive pulmonary disease, asthma, interstitial lung diseases and lung cancer. This imbalance often results in elevated net MMP activity, making MMP inhibition an attractive therapeutic strategy. Although promising results have been obtained, the lack of selective MMP inhibitors, together with limited knowledge regarding the exact functions of a particular MMP, hampers clinical application. This review discusses the involvement of different MMPs in lung disorders and future opportunities and limitations of therapeutic MMP inhibition.

Heme Oxygenase-1 in Patients With Interstitial Lung Disease: A Review of the Clinical Evidence.

The clinical course and rate of progression of interstitial lung disease (ILD) are extremely variable among patients. For the purpose of monitoring disease activity, ILD diagnosis, and predicting disease prognosis, there are various biomarkers, including symptoms, physiological, radiological, and pathological findings, and peripheral blood and bronchoalveolar lavage fluid results. Of these, blood biomarkers such as sialylated carbohydrate antigen, surfactant proteins-A and -D, CC-chemokine ligand 18, matrix metalloprotease-1 and -7, CA19-9, and CA125 have been previously proposed. In the future, heme oxygenase-1 (HO-1) may also become a candidate ILD biomarker; it is a 32-kDa heat shock protein converting heme to carbon monoxide, biliverdin/bilirubin, and free iron to play a role in the pulmonary cytoprotective reaction in response to various stimuli. Recent research suggests that HO-1 can increase in lung tissues of patients with ILD, reflecting anti-inflammatory M2 macrophage activation, and the measurement of HO-1 levels in peripheral blood can be useful for evaluating the severity of lung damage in ILD and for predicting subsequent fibrosis formation.

A 12-Year-Old Girl Presenting With Recurrent Dyspnea and Pulmonary Ground-Glass Opacities.

CASE PRESENTATION: A 12-year-old girl presented with shortness of breath with exercise for 2 weeks. Her oxygen saturation was 85% during exercise. Birth and family histories were unremarkable. The girl was healthy until 7.1 years of age, when she suffered a "pneumonia" with fever, dyspnea, and hypoxemia, which diminished after a 19-day treatment with antibiotics and methylprednisolone. These symptoms relapsed 8 months later, and she was diagnosed with rapidly progressive interstitial lung disease (ILD) and a Mycoplasma pneumoniae infection. At that time, her symptoms failed to respond to a course of antibiotic therapy but resolved with IV methylprednisolone at 2.7 mg/kg/day. She remained on a tapering dose of methylprednisolone plus methotrexate for the next 18 months until withdrawal of these medications because of return of almost normal lung imaging. She had never had myalgia, muscle weakness, arthritis, rashes, mechanic's hands, Raynaud's phenomenon, dry mouth, or dry eyes.

Cathepsin-K is a sensitive immunohistochemical marker for detection of micro-granulomas in hypersensitivity pneumonitis.

UNLABELLED: Hypersensitivity Pneumonitis (HP) is an interstitial lung disease that occurs upon exposure to a variety of inhaled organic antigens. The presence of small non-caseating granulomas and isolated giant cells is not specific, but is considered a relevant histological feature for HP. The detection of granulomas is widely considered as easy on standard histological stains, but microgranuloma detection can be difficult and/or time consuming, especially in chronic HP cases. Cathepsin K (Cath-K) is a potent cysteine protease expressed at high levels in activated macrophages (osteoclasts, and epithelioid cells in granulomas), but is not expressed in resident macrophages thus representing a promising marker to rapidly detect and quantitatively evaluate microgranulomas in interstitial lung diseases. We analyzed the expression of Cath-K by immunohistochemistry in 22 subacute and chronic HP cases, using semi-quantitative scores. Control samples included normal lung tissue, and a variety of interstitial lung diseases: 3 Wegener's granulomatosis, 3 sarcoidosis, 3 tuberculosis, 1 berylliosis, 20 idiopathic pulmonary fibrosis (IPF), 2 Langerhans' cell histiocytosis, 5 nonspecific-interstitial pneumonia (NSIP), 5 cryptogenic organising-pneumonia (COP), 2 Airway-Centered Interstitial Fibrosis (ACIF), 5 desquamative interstitial pneumonia (DIP), 3 respiratory bronchiolitis interstitial lung disease (RB-ILD). Intense expression of Cath-K was demonstrated in epithelioid and giant cells in all cases containing granulomas (HP, sarcoidosis, Wegener's granulomatosis, berylliosis, tuberculosis). Among HP cases 19/22 (86.3%) contained granulomas that could be semiquantitatively evaluated. In all HP and control cases alveolar macrophages did not express Cath-K, including cases characterised by large collections of alveolar macrophages such as DIP and RB-ILD. CONCLUSIONS: Cath-K represents a sensitive and specific marker to detect and quantitate granulomatous reactions in interstitial lung diseases, and is particularly useful in chronic HP cases.

Antisynthetase syndrome presenting as rheumatoid-like polyarthritis.

BACKGROUND: The antisynthetase syndrome is a systemic inflammatory disease associated with anti-tRNA synthetase antibodies and consisting of the clinical features of inflammatory myopathy arthritis, interstitial lung disease (ILD), fever, Raynaud syndrome, and rash. It rarely presents with symmetric arthritis as the initial manifestation of the disease. OBJECTIVE: The aim of the study was to describe the clinical, laboratory, and radiographic characteristics of patients with antisynthetase syndrome who presented with symptoms of inflammatory arthritis, mimicking rheumatoid arthritis (RA) at the time of initial evaluation. METHODS: Six cases derived from a single university-based rheumatology clinic in Wisconsin are presented. The major clinical, laboratory, radiographic, and histopathologic data are described. RESULTS: All 6 patients demonstrated symmetric synovitis involving the hands. Five patients met the American College of Rheumatology classification criteria for RA. Three patients had nail-fold capillary abnormalities, and 4 patients were observed to have Raynaud phenomenon. Three patients demonstrated a cytoplasmic pattern when testing for antinuclear antibodies by immunofluorescent assay, and all had t-RNA synthetase antibodies. Two patients had positive rheumatoid factors, but none had strongly positive cyclic citrullinated peptide antibodies. None of the patients demonstrated radiographic erosions. All patients had evidence of ILD by imaging or pulmonary function testing. Prognosis was generally favorable, although disease severity and treatment varied considerably. CONCLUSION: In patients who present with features mimicking but atypical for RA, such as early ILD, nail-fold capillary abnormalities, Raynaud phenomenon, cytoplasmic antinuclear antibody pattern, negative cyclic citrullinated peptide antibody status, and nonerosive arthritis, the antisynthetase syndrome should be considered.

[Assessment of smoking related pathologic changes and MMP-9, TIMP-1 expressions of the lung]. / Akcigerde sigaraya bagli patolojik degisimler, MMP-9 ve TIMP-1 ekspresyonlarinin degerlendirilmesi.

The impact of smoking on the peripheral airways, the determining field of respiratory functions in the lungs, is well known. Fifty two cases were included in the study; autopsy cases of non-cardiopulmonary related deaths with a smoking history, and cases with lung resection, known as smokers. Ten cases without a smoking history and a systemic disease were used as a control group at the histopathological examination. Parenchymal samples were taken from the central and peripheral airways (1st, 2nd, 3rd division) and from each lob. In addition, age, gender, amount and duration of smoking (package/year) were considered and histopathological changes of the lung are evaluated under the light microscope. The relations of all parameters to each other are evaluated and compared with the control group. On the distal airways with small diameter, Respiratory Bronchiolitis (RB) was determined in 14 (26.9%) cases, and Respiratory Bronchiolitis-associated interstitial lung disease (RB-ILD) in 16 (30.7%) cases. Two (3.8%) cases were diagnosed as Desquamative Interstitial Pneumonia (DIP). MMP-9, a matrix metalloproteinase known for its role in the development and repair of obstructive diseases of the lung related to smoking, and TIMP-1, an inhibitor, were used on the lung samples by means of immunohistochemical method. MMP-9 and TIMP-1 expressions of all cases were compared statistically with the existing pathological findings and the control group. MMP-9, TIMP-1 were expressed from the alveolar macrophages, endothelial and epithelial cells. Considering the MMP-9 and TIMP-1 density of alveolar macrophages, no statistically significant differences were found among the RB, RBILD and DIP case groups. However; despite of the significant MMP-9 expression of the DIP cases, TIMP-1 expression could not be determined. Compared to the control group, a more intensive and widespread positive reaction on MMP-9 was found in the alveolar macrophages. In conclusion, although there was no significant relation between the level and duration of smoking and the MMP-9 and TIMP-1 expressions, alveolar macrophages were found to be more important in lung damage related to smoking and the MMP-9 expression from these cells to be more intensive than the control group.

[Assessment of glutathione peroxidase activity (GPX) in the diagnosis of diffuse pulmonary parenchymal changes]. / Ocena aktywnosci peroksydazy glutationowej (GPX) w diagnostyce rozsianych zmian miazszowych pluc.

UNLABELLED: DNA damage caused by free radicals is one of the mechanisms which are responsible for the occurrence of lung tumors, especially in case of cigarette smokers.Their tumors are radiologically often disseminated changes. AIM OF THIS STUDY: To define the correlation between GPX activity in erythrocyte hemolysate and pulmonary parenchymal extract and the etiology of diffuse pulmonary parenchymal changes. MATERIAL AND METHODS: The study group comprised 40 subjects classified to VTS due to diffuse pulmonary parenchymal changes. The control group included 40 clinically healthy subjects. In the examined group GPX activity in erythrocyte hemolysate and pulmonary parenchymal extract was marked. The material was 5.4 ml of vein blood taken one-time from all subjects and a sample of pulmonary parenchyma obtained during VTS or toracotomy in patients with pulmonary parenchymal changes. RESULTS: Lower values of GPX activity in erythrocyte hemolysate and pulmonary parenchymal extract which are statistically significant were observed compared with the control group. CONCLUSIONS: Higher GPX activity in erythrocyte hemolysate and healthy pulmonary parenchymal extract compared with pulmonary parenchymal changes can show the influence of GPX on the development of disease process. Higher GPX activity in erythrocte hemolysate and pulmonary parenchymal extract in the "sarcoidosis group" compared with the "lung carcinoma group" can be an additional marker in differential dignostics. The determination of GPX activity in erythrocyte hemolysate can be used as a supplementary laboratory test which will facilitate diagnosis of pulmonary parenchymal changes.

Two cases with autoantibodies to small ubiquitin-like modifier activating enzyme: A potential unique subset of dermatomyositis-associated interstitial lung disease.

The presence of anti-aminoacyl tRNA synthetase (ARS) or anti-melanoma differential-associated gene 5 (MDA5) is strongly related to interstitial lung disease (ILD) in patients with dermatomyositis (DM). Several studies suggest a potential relationship between ILD and anti-small ubiquitin-like modifier activating enzyme (SAE) antibody in DM patients, but detailed clinical characteristics of anti-SAE-associated ILD still remain unknown. We have experienced 2 cases who were positive for anti-SAE antibody, who presented with ILD in the context of clinically amyopathic DM. These 2 patients had the following common ILD characteristics: an insidious course with preserved pulmonary function; a limited extent of pulmonary lesions with subpleural peripheral-dominant small ground glass opacity/consolidation on high-resolution computed tomography; and a favorable treatment response. These findings suggest that anti-SAE-associated ILD is unique in terms of clinical and imaging features and differs from ILD associated with anti-ARS or anti-MDA5 antibody.

Is metalloproteinase-7 specific for idiopathic pulmonary fibrosis?

BACKGROUND: Matrix metalloproteinase (MMP)-7 was reported to be a key molecule in the pathogenesis of idiopathic pulmonary fibrosis (IPF) based on the result of microarray analysis and knockout mice. However, the role of MMP-7 has not been determined in other types of idiopathic interstitial pneumonia (IIP). The aim of this study was to investigate the role of MMP-7 in IIP by comparing its expression in usual interstitial pneumonia (UIP) and cryptogenic organizing pneumonia (COP). METHODS: Levels of MMP and tissue inhibitors of metalloproteinase in BAL fluid and their expression on lung tissues were compared between normal control subjects (n = 5) and the patients with IPF (n = 6) and COP (n = 11). RESULTS: There was no significant difference in BAL fluid MMP-7 levels between UIP and COP, although it was higher in both diseases compared to normal control subjects. Furthermore, the pattern and the degree of MMP-7 expression in lung tissues were also similar in both IPF and COP, whereas MMP-2 level was higher in COP and MMP-9 level was higher in IPF. CONCLUSION: MMP-7 seems to play an important role in the pathogenesis of not only IPF but also COP; therefore, it may not be the key factor determining the prognosis or reversibility of IIPs.

AKR1B10 in usual interstitial pneumonia: expression in squamous metaplasia in association with smoking and lung cancer.

The incidence of lung cancer (LC) is markedly increased among patients with usual interstitial pneumonia (UIP), and tobacco smoking is its superimposed risk factor. AKR1B10 (aldo-keto reductase 1B10) is frequently overexpressed in pulmonary squamous cell carcinoma and adenocarcinoma in smokers. To investigate the role of AKR1B10 in the pulmonary carcinogenesis in UIP with correlation to tobacco smoking, we examined 13 UIP cases with LC, 13 UIP cases without LC, and 30 cases of non-UIP LC using AKR1B10 immunohistochemistry. AKR1B10 immunoreactivity was confined to squamous metaplasia in honeycomb lesions of UIP and neoplastic cells of LC. Squamous metaplastic foci showed AKR1B10 immunoreactivity more frequently in UIP with LC (24/36 foci, 67%) than in UIP without LC (16/44 foci, 37%) (P<0.01). AKR1B10 expression in UIP was also more frequent in squamous metaplastic foci in smokers (38/67 foci, 57%) than in non-smokers (2/13 foci, 15%) (P<0.01). AKR1B10 expression was frequently observed in both UIP-associated LC (10/13 foci, 77%) and non-UIP LC (18/30 foci, 60%). Ki-67 labeling index was significantly higher in AKR1B10-positive squamous metaplasia of UIP than in AKR1B10-negative squamous metaplasia of UIP. Our results demonstrate that AKR1B10 is involved in the development of LC in UIP in association with smoking. AKR1B10 might be useful as a new marker for identification of high LC risk patients in UIP.

Elevated matrilysin levels in bronchoalveolar lavage fluid do not distinguish idiopathic pulmonary fibrosis from other interstitial lung diseases.

Microarray studies have shown that matrilysin or matrix metalloproteinase (MMP)-7 is highly upregulated in the lungs of patients with idiopathic pulmonary fibrosis (IPF), but MMP-7 protein expression has not been systematically compared between IPF and other interstitial lung diseases. MMP-7 levels in bronchoalveolar lavage fluid (BALF) were compared to corresponding samples from nonspecific interstitial pneumonia (NSIP), sarcoidosis, and healthy controls. MMP-7 levels in the BALF were determined by ELISA and localization of MMP-7 in the lung tissue by immunohistochemistry. MMP-7 was similarly elevated in the BALF of all these disorders compared to healthy controls (p=0.007). Even control subjects with prolonged cough displayed a tendency towards elevated MMP-7 expression. There was a negative correlation between BALF MMP-7 levels and forced expiratory vital capacity (r=-0.348, p=0.02, n=42). In IPF lung, MMP-7 immunoreactivity appeared predominantly in the fibrotic parenchyma and arterial wall. In sarcoidosis and NSIP, prominent MMP-7 immunoreactivity was found in areas of inflammation. These results demonstrate that elevated BALF MMP-7 is not restricted to IPF alone but is also observed in other interstitial lung diseases and cannot be used as a differential diagnostic marker for IPF.

Enhanced mast cell chymase expression in human idiopathic interstitial pneumonia.

Previous studies have shown that mast cell chymase induces and promotes fibrogenesis in injured tissues. We studied the roles of mast cell chymase in the fibritic processes of human idiopathic interstitial pneumonias. Frozen tissue sections from human lungs with usual interstitial pneumonia (n=7), nonspecific interstitial pneumonia (n=4) and normal lungs (n=10) were studied immunohistochemically. Monoclonal antibodies against mast cell chymase, tryptase, interleukin-4, and smooth muscle actin were used. Stained cells or areas were quantified by computer-aided morphometry. The numbers of both tryptase-positive mast cells and chymase-positive mast cells were significantly greater in lung tissues with idiopathic interstitial pneumonia than in normal lung tissues. The increase in the number of chymase-positive mast cells in the diseased lung tissues was closely related to an increase in interleukin-4-positive cells, and also to an accumulation of smooth muscle cells and myofibroblasts. Because smooth muscle cell and myofibroblast proliferation is a principal pathological change in idiopathic interstitial pneumonias, these observations suggest that mast cell chymase, possibly induced by interleukin-4-dependent phenotypic modulation, may be an important mediator in the inflammatory and fibrotic processes of idiopathic interstitial pneumonia in humans.

Chitotriosidase activity in patients with interstitial lung diseases.

BACKGROUND: In previous papers, we found significantly higher activity of chitotriosidase, a macrophage derived enzyme, in serum and BAL of patients with sarcoidosis, especially in those with progressing disease and lung involvement, than in controls. Locally and systemically produced chitotriosidase activity was correlated with radiological stage and also with degree of lung infiltration, suggesting that this enzyme may play a role in the pathogenesis of sarcoidosis and may be used as a marker of disease severity. AIM: To analyse chitotriosidase activity in serum and bronchoalveolar lavage of patients with idiopathic pulmonary fibrosis and pulmonary fibrosis associated with systemic sclerosis and to compare it with chitotriosidase activity in controls and sarcoidosis patients. METHODS: Chitotriosidase activity was determined by a fluorometric assay. RESULTS: The results showed that serum chitotriosidase activity was only elevated in sarcoidosis patients; in patients with idiopathic pulmonary fibrosis and pulmonary fibrosis associated with systemic sclerosis it was in the normal range. On the contrary, in BAL of sarcoidosis and idiopathic pulmonary fibrosis patients the activity was significantly higher than in controls. CONCLUSION: Serum chitotriosidase is a potential marker of sarcoidosis severity; it increases in sarcoidosis in relation to radiological stage and degree of lung infiltration. The increase in chitotriosidase activity in BAL of sarcoidosis and idiopathic pulmonary fibrosis patients suggests that the enzyme could be involved in fibrogenesis in diffuse lung diseases. Further research is needed to understand the role of chitotriosidase in the pathogenesis of sarcoidosis and its involvement in fibrotic remodelling in certain diffuse lung diseases.

Bronchoalveolar matrix metalloproteinase 9 relates to restrictive lung function impairment in systemic sclerosis.

Systemic sclerosis (SSc) is frequently associated with interstitial lung disease (ILD) often leading to lung fibrosis. In this study we investigated whether matrix metalloproteinase 9 (MMP-9) and its natural inhibitor; the tissue inhibitor of matrix metalloproteinase 1 (TIMP-1), would be associated with remodelling in ILD in SSc. Levels of total MMP-9, pro-MMP-9 and TIMP-1 were measured in bronchoalveolar lavage (BAL) fluid from nine SSc patients with ILD, seven SSc patients without ILD and 16 age- and sex-matched healthy controls. Total MMP-9 and pro-MMP-9 levels were significantly elevated in SSc patients with ILD, compared to levels in SSc patients without ILD and healthy controls. In SSc patients with ILD calculated active MMP-9 levels were significantly higher than in SSc patients without ILD and tended to be higher than in healthy controls. TIMP-1 levels were elevated in both patient groups compared to healthy controls. Total-, pro- and active MMP-9 levels as well as pro-MMP-TIMP-1 and active MMP-9/TIMP-1 ratios were inversely associated with total lung capacity. The present study suggests that MMP-9 plays a pathophysiological role in the remodelling in ILD and lung fibrosis associated with SSc, and may represent a new therapeutic target in this condition.

COX-2 is widely expressed in metaplastic epithelium in pulmonary fibrous disorders.

Idiopathic usual interstitial pneumonia/idiopathic pulmonary fibrosis (UIP/IPF) and asbestosis represent progressive and often fatal pulmonary fibrous disorders, whereas cryptogenic organizing pneumonia (COP), desquamative interstitial pneumonia (DIP), and respiratory bronchiolitis-interstitial lung disease (RB-ILD) usually are reversible or nonprogressive conditions. Prostaglandin E2 (PGE2) inhibits fibroblast proliferation and myofibroblast transition, its production depending on cyclooxygenase-2 (COX-2). In patients with UIP/IPF, levels of PGE2 and COX-2 are reduced in fibroblasts, and levels of PGE2 in bronchioalveolar lavage fluid may be lowered. We analyzed the immunohistochemical expression of COX-2 in UIP/IPF, asbestosis, COP, DIP, and RB-ILD. Our results show that the metaplastic epithelium in UIP/IPF, asbestosis, and COP is widely COX-2+, whereas COX-2 positivity is scant in DIP and RB-ILD. The mesenchymal cells remained negative. Our results suggest that irrespective of the underlying disease, lung injury that causes extensive fibrosis induces wide expression of COX-2 in the regenerating metaplastic epithelium.

Glutathione peroxidase 3 localizes to the epithelial lining fluid and the extracellular matrix in interstitial lung disease.

Aberrant antioxidant activity and excessive deposition of extracellular matrix (ECM) are hallmarks of interstitial lung diseases (ILD). It is known that oxidative stress alters the ECM, but extracellular antioxidant defence mechanisms in ILD are incompletely understood. Here, we extracted abundance and detergent solubility of extracellular antioxidant enzymes from a proteomic dataset of bleomycin-induced lung fibrosis in mice and assessed regulation and distribution of glutathione peroxidase 3 (GPX3) in murine and human lung fibrosis. Superoxide dismutase 3 (Sod3), Gpx3, and Gpx activity were increased in mouse BALF during bleomycin-induced lung fibrosis. In lung tissue homogenates, Gpx3, but not Sod3, was upregulated and detergent solubility profiling indicated that Gpx3 associated with ECM proteins. Immunofluorescence analysis showed that Gpx3 was expressed by bronchial epithelial cells and interstitial fibroblasts and localized to the basement membrane and interstitial ECM in lung tissue. As to human ILD samples, BALF of some patients contained high levels of GPX3, and GPX3 was upregulated in lung homogenates from IPF patients. GPX3 expression in primary human bronchial epithelial cells and lung fibroblasts was downregulated by TNF-α, but more variably regulated by TGF-ß1 and menadione. In conclusion, the antioxidant enzyme GPX3 localizes to lung ECM and is variably upregulated in ILD.