Idiopathic Pulmonary Fibrosis Is Associated with Common Genetic Variants and Limited Rare Variants.

Rationale: Idiopathic pulmonary fibrosis (IPF) is a rare, irreversible, and progressive disease of the lungs. Common genetic variants, in addition to nongenetic factors, have been consistently associated with IPF. Rare variants identified by candidate gene, family-based, and exome studies have also been reported to associate with IPF. However, the extent to which rare variants, genome-wide, may contribute to the risk of IPF remains unknown. Objectives: We used whole-genome sequencing to investigate the role of rare variants, genome-wide, on IPF risk. Methods: As part of the Trans-Omics for Precision Medicine Program, we sequenced 2,180 cases of IPF. Association testing focused on the aggregated effect of rare variants (minor allele frequency ⩽0.01) within genes or regions. We also identified individual rare variants that are influential within genes and estimated the heritability of IPF on the basis of rare and common variants. Measurements and Main Results: Rare variants in both TERT and RTEL1 were significantly associated with IPF. A single rare variant in each of the TERT and RTEL1 genes was found to consistently influence the aggregated test statistics. There was no significant evidence of association with other previously reported rare variants. The SNP heritability of IPF was estimated to be 32% (SE = 3%). Conclusions: Rare variants within the TERT and RTEL1 genes and well-established common variants have the largest contribution to IPF risk overall. Efforts in risk profiling or the development of therapies for IPF that focus on TERT, RTEL1, common variants, and environmental risk factors are likely to have the largest impact on this complex disease.

Changes in physical activity in people with idiopathic pulmonary fibrosis before and after virtual pulmonary rehabilitation: a feasibility study.

BACKGROUND: Pulmonary rehabilitation (PR) is recommended for the treatment of people with idiopathic pulmonary fibrosis (IPF). Physical activity is an important health behaviour, closely linked to survival in people with IPF. Little is known about the impact of virtual (V) PR on physical activity in people with IPF. OBJECTIVE: To explore the feasibility of conducting a trial to explore effect of virtual PR on objectively measured physical activity in people with IPF. METHODS: All patients with a diagnosis of IPF in a stable phase of the disease were invited to participate in VPR: a 10 week exercise programme delivered twice-weekly for one hour. Data were collected at baseline (BL) and post VPR (10 weeks): Kings Brief Interstitial Lung Disease (K-BILD), Exercise capacity (6-minute walk test (6MWT) or 1-minute sit-to-stand (STS)) and Physical Activity. Physical activity was measured with a triaxial accelerometer for seven days. Screening, recruitment, adherence and safety data were collected. RESULTS: 68 people were screened for this study. N = 16 participants were recruited to the study. There was one dropout. N = 15 completed VPR. All results reported in mean (standard deviation) (SD). Participants attended 18.1(2.0) of the 20 sessions. No adverse events were detected. The mean age of participants was 71.5(11.5) years, range: 47-95 years; 7 M:9 F. Mean (SD) FEV1 2.3(0.3)L, FVC 2.8(0.7)L. No statistically significant changes were observed in outcome measures apart from exercise capacity. Light physical activity increased from 152(69.4) minutes per day (n = 16) to 161.9(88.7) minutes per day (n = 14), mean change (SD) (CI) p-value: 9.9 (39.8) [-12.3 to 30.9] p = 0.4. Moderate-to-vigorous physical activity increased from 19.1(18.6) minutes per day (n = 16) to 25.7(28.3) minutes per day (n = 14), mean change (SD) (CI) p-value: 6.7 (15.5) [-2.1 to 15.1] p = 0.1. Step count increased from 3838(2847) steps per day (n = 16) to 4537(3748) steps per day (n = 14), mean change (SD) (CI) p-value: 738 (1916) [-419.3 to 1734.6] p = 0.2. K-BILD (n = 15) increased from 55.1(7.4) at BL to 55.7(7.9) post VPR mean change (SD) [95% confidence interval] (CI) p-value: 1.7(6.5) [-1.7 to 5.3], p = 0.3. 6MWT (n = 5) increased from 361.5(127.1) to 452.2(136.1) meters, mean change (SD) (CI) p-value: 63.7 (48.2) [-3.8 to 123.6], p = 0.04 and 1-minute STS increased from 17.6(3.0) (n = 11) to 23.7(6.3) (n = 10), mean change (SD) (CI) p-value 5.8 (4.6) [2.6 to 9.1], p = 0.003. CONCLUSION: VPR can improve physical activity in people with IPF. A number of important feasibility issues included recruitment, retention, adherence and safety have been reported which are crucial for future research in this area. A fully powered trial is needed to determine the response of people with IPF to PR with regard to physical activity.

A qualitative exploration of people living with idiopathic pulmonary fibrosis experience of a virtual pulmonary rehabilitation programme.

BACKGROUND: Pulmonary rehabilitation (PR) is recommended in the treatment of people with idiopathic pulmonary fibrosis (IPF). Little is known about the experiences of people with IPF of PR. Due to Covid-19 there has been a rapid shift of PR services to remote/virtual delivery. OBJECTIVE: To explore people living with IPFs experience of a virtual PR (VPR) programme. METHODS: All patients with a diagnosis of IPF in a stable phase of the disease were invited to participate in virtual PR: a 10 week exercise programme delivered twice-weekly for one hour. One-to-one semi- structured interviews were conducted within one week following the programme. All interviews were recorded, transcribed and analysed using Braun and Clarke thematic analysis by two independent assessors. RESULTS: N=13 participants took part in the semi-structured interviews, mean (standard deviation (SD)) age 69.5(10.4) years; 7M:6F. Mean (SD) FEV1 2.6(0.3)L, FVC 2.9(0.4)L. Four key themes were identified: 1) The impact of VPR on health and outlook, (2) The reality of VPR, (3) Being active after VPR and (4) Living with IPF during the COVID-19 Pandemic. Participants reported high levels of enjoyment and engagement with the programme regardless of the health benefits experienced. Most participants expressed a desire for a longer programme. Participants expressed different levels of maintenance with exercise since finishing the programme, specific motivators and strategies for maintenance included lung transplant, the maintenance of benefits from the programme and social support. COVID-19 and the restrictions imposed had some negative impacts on some participants lives, engaging with PR helped overcome some of these. CONCLUSION: Despite the progressive nature of IPF, all participants expressed high levels of enjoyment with the programme. Future research should explore strategies for maintenance post PR and the optimum duration of PR for people with IPF.

Unexpected paracetamol (acetaminophen) hepatotoxicity at standard dosage in two older patients: time to rethink 1 g four times daily?

We present two cases of acute hepatotoxicity associated with elevated paracetamol (acetaminophen) levels in older patients. Both patients were receiving a standard European dose of oral paracetamol (2 × 500 mg QDS) with no risk factors for slowed metabolism (weight <50 kg, interacting medications, hepatic enzyme inducers, history of liver disease). Significantly, both patients had recently had a dose escalation from 'as needed' dosing to 4 g daily, and the medication was being administered by nursing staff. Our experience shows that even when prescribed appropriately at the usual therapeutic dosage, paracetamol can be hepatotoxic.

Comparing new treatments for idiopathic pulmonary fibrosis--a network meta-analysis.

BACKGROUND: The treatment landscape for idiopathic pulmonary fibrosis, a devastating lung disease, is changing. To investigate the effectiveness of treatments for idiopathic pulmonary fibrosis we undertook a systematic review, network meta-analysis and indirect comparison. METHODS: We searched MEDLINE, EMBASE and The Cochrane library for relevant studies. Randomised controlled trials of pirfenidone, nintedanib or N-acetylcysteine were eligible. Predefined processes for selecting references, extracting data and assessing study quality were applied. Our network meta-analysis of published data used a fixed effect model. For forced vital capacity measures a standardised mean difference approach was used and converted to odds ratios for interpretation. RESULTS: Of 1076 references, 67 were retrieved and 11 studies included. Studies were of reasonable size, populations were similar, and the overall quality was good. Only two treatments, pirfenidone (odds ratio 0.62, 95% credible interval 0.52, 0.74) and nintedanib (0.41, 95% credible interval 0.34, 0.51) produced a statistically significant slowing in the rate of forced vital capacity decline compared with placebo. In an indirect comparison, results indicate that nintedanib is statistically significantly better than pirfenidone in slowing forced vital capacity decline (odds ratio 0.67, 95% credible interval 0.51, 0.88). Results were stable in scenario analysis and random effects models. Indirect comparisons of mortality were not statistically significant between nintedanib and pirfenidone. CONCLUSIONS: Two treatments show beneficial effects and when compared indirectly nintedanib appears to have superior benefit on forced vital capacity. Limitations to indirect comparisons should be considered when interpreting these results, however, our findings can be useful to inform treatment decisions.

Spiruchostatin A inhibits proliferation and differentiation of fibroblasts from patients with pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive scarring disorder characterized by the proliferation of interstitial fibroblasts and the deposition of extracellular matrix causing impaired gas exchange. Spiruchostatin A (SpA) is a histone deacetylase inhibitor (HDI) with selectivity toward Class I enzymes, which distinguishes it from other nonspecific HDIs that are reported to inhibit (myo)fibroblast proliferation and differentiation. Because the selectivity of HDIs may be important clinically, we postulated that SpA inhibits the proliferation and differentiation of IPF fibroblasts. Primary fibroblasts were grown from lung biopsy explants obtained from patients with IPF or from normal control subjects, using two-dimensional or three-dimensional culture models. The effect of SpA on fibroproliferation in serum-containing medium ± transforming growth factor (TGF)-ß(1) was quantified by methylene blue binding. The acetylation of histone H3, the expression of the cell-cycle inhibitor p21(waf1), and the myofibroblast markers α-smooth muscle actin (α-SMA) and collagens I and III were determined by Western blotting, quantitative RT-PCR, immunofluorescent staining, or colorimetry. SpA inhibited the proliferation of IPF or normal fibroblasts in a time-dependent and concentration-dependent manner (concentration required to achieve 50% inhibition = 3.8 ± 0.4 nM versus 7.8 ± 0.2 nM, respectively; P < 0.05), with little cytotoxicity. Western blot analyses revealed that SpA caused a concentration-dependent increase in histone H3 acetylation, paralleling its antiproliferative effect. SpA also increased p21(waf1) expression, suggesting that direct cell-cycle regulation was the mechanism of inhibiting proliferation. Although treatment with TGF-ß(1) induced myofibroblast differentiation associated with increased expression of α-SMA, collagen I and collagen III and soluble collagen release, these responses were potently inhibited by SpA. These data support the concept that bicyclic tetrapeptide HDIs merit further investigation as potential treatments for IPF.

A disintegrin and metalloprotease (ADAM) 33 protein in patients with pulmonary sarcoidosis.

BACKGROUND AND OBJECTIVE: A disintegrin and metalloproteinase (ADAM) 33 is a susceptibility gene associated with inflammatory lung and skin diseases. It is selectively expressed in mesenchymal cells, and its metalloprotease activity has been linked to angiogenesis and tissue remodelling. A soluble form of ADAM33 (sADAM33) has been identified in the bronchoalveolar lavage fluid (BALF) of asthmatic patients, and its levels inversely correlate with lung function. Because of its association with inflammatory lung diseases, it was hypothesized that sADAM33 is elevated in BALF of patients with pulmonary sarcoidosis. METHODS: After removal of Ig using Protein A/G and enrichment using Concanavalin A beads, sADAM33 was identified in BALF by Western blotting. A fluorescence resonance energy transfer peptide cleavage assay was used to assess ADAM33-like activity in BALF. RESULTS: sADAM33 protein in BALF was detected as a 25 kDa fragment, and levels were significantly increased in samples from sarcoid patients when compared to healthy controls (P < 0.05). Levels of sADAM33 were inversely correlated with lung function (FVC%) (P < 0.05) and DL(CO) % predicted (P < 0.01). No difference in sADAM33 enzymatic activity was observed between healthy and sarcoid BALF samples. CONCLUSIONS: Release of sADAM33 is increased in sarcoid and may be associated with abnormal lung function. sADAM33 may be a biomarker of lung tissue inflammation and remodelling in sarcoid.

Mixed methods protocol to examine the acceptability and clinical characteristics of a remote monitoring programme for delivery of COVID-19 care, among healthcare staff and patients.

INTRODUCTION: The use of remote monitoring technology to manage the care of patients with COVID-19 has been implemented to help reduce the burden placed on healthcare systems during the pandemic and protect the well-being of both staff and patients. Remote monitoring allows patients to record their signs and symptoms remotely (eg, while self-isolating at home) rather than requiring hospitalisation. Healthcare staff can, therefore, continually monitor their symptoms and be notified when the patient is showing signs of clinical deterioration. However, given the recency of the COVID-19 outbreak, there is a lack of research regarding the acceptance of remote monitoring interventions to manage COVID-19. This study will aim to evaluate the use of remote monitoring for managing COVID-19 cases from the perspective of both the patient and healthcare staff. METHODS AND ANALYSIS: Discharged patients from a large urban teaching hospital in Ireland, who have undergone remote monitoring for COVID-19, will be recruited to take part in a cross-sectional study consisting of a quantitative survey and a qualitative interview. A mixed methods design will be used to understand the experiences of remote monitoring from the perspective of the patient. Healthcare staff who have been involved in the provision of remote monitoring of patients with COVID-19 will be recruited to take part in a qualitative interview to understand their experiences with the process. Structural equation modelling will be used to examine the acceptance of the remote monitoring technology. Latent class analysis will be used to identify COVID-19 symptom profiles. Interview data will be examined using thematic analysis. ETHICS AND DISSEMINATION: Ethical approval has been granted by the ethical review boards at University College Dublin and the National Research Ethics Committee for COVID-19-related Research. Findings will be disseminated via publications in scientific journals, policy briefs, short reports and social media.

Routine Hematological Parameters May Be Predictors of COVID-19 Severity.

To date, coronavirus disease 2019 (COVID-19) has affected over 100 million people globally. COVID-19 can present with a variety of different symptoms leading to manifestation of disease ranging from mild cases to a life-threatening condition requiring critical care-level support. At present, a rapid prediction of disease severity and critical care requirement in COVID-19 patients, in early stages of disease, remains an unmet challenge. Therefore, we assessed whether parameters from a routine clinical hematology workup, at the time of hospital admission, can be valuable predictors of COVID-19 severity and the requirement for critical care. Hematological data from the day of hospital admission (day of positive COVID-19 test) for patients with severe COVID-19 disease (requiring critical care during illness) and patients with non-severe disease (not requiring critical care) were acquired. The data were amalgamated and cleaned and modeling was performed. Using a decision tree model, we demonstrated that routine clinical hematology parameters are important predictors of COVID-19 severity. This proof-of-concept study shows that a combination of activated partial thromboplastin time, white cell count-to-neutrophil ratio, and platelet count can predict subsequent severity of COVID-19 with high sensitivity and specificity (area under ROC 0.9956) at the time of the patient's hospital admission. These data, pending further validation, indicate that a decision tree model with hematological parameters could potentially form the basis for a rapid risk stratification tool that predicts COVID-19 severity in hospitalized patients.

Time taken from primary care referral to a specialist centre diagnosis of idiopathic pulmonary fibrosis: an opportunity to improve patient outcomes?

For patients with IPF, length of time in healthcare systems prior to review in an ILD clinic reflects disease severity and may impact upon patient outcome https://bit.ly/2TkO26r.

The histone deacetylase inhibitor, romidepsin, as a potential treatment for pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive disease that usually affects elderly people. It has a poor prognosis and there are limited therapies. Since epigenetic alterations are associated with IPF, histone deacetylase (HDAC) inhibitors offer a novel therapeutic strategy to address the unmet medical need. This study investigated the potential of romidepsin, an FDA-approved HDAC inhibitor, as an anti-fibrotic treatment and evaluated biomarkers of target engagement that may have utility in future clinical trials. The anti-fibrotic effects of romidepsin were evaluated both in vitro and in vivo together with any harmful effect on alveolar type II cells (ATII). Bronchoalveolar lavage fluid (BALF) from IPF or control donors was analyzed for the presence of lysyl oxidase (LOX). In parallel with an increase in histone acetylation, romidepsin potently inhibited fibroblast proliferation, myofibroblast differentiation and LOX expression. ATII cell numbers and their lamellar bodies were unaffected. In vivo, romidepsin inhibited bleomycin-induced pulmonary fibrosis in association with suppression of LOX expression. LOX was significantly elevated in BALF of IPF patients compared to controls. These data show the anti-fibrotic effects of romidepsin, supporting its potential use as novel treatment for IPF with LOX as a companion biomarker for evaluation of early on-target effects.

Three-dimensional characterization of fibroblast foci in idiopathic pulmonary fibrosis.

In idiopathic pulmonary fibrosis (IPF), the fibroblast focus is a key histological feature representing active fibroproliferation. On standard 2D pathologic examination, fibroblast foci are considered small, distinct lesions, although they have been proposed to form a highly interconnected reticulum as the leading edge of a "wave" of fibrosis. Here, we characterized fibroblast focus morphology and interrelationships in 3D using an integrated micro-CT and histological methodology. In 3D, fibroblast foci were morphologically complex structures, with large variations in shape and volume (range, 1.3 × 104 to 9.9 × 107 µm3). Within each tissue sample numerous multiform foci were present, ranging from a minimum of 0.9 per mm3 of lung tissue to a maximum of 11.1 per mm3 of lung tissue. Each focus was an independent structure, and no interconnections were observed. Together, our data indicate that in 3D fibroblast foci form a constellation of heterogeneous structures with large variations in shape and volume, suggesting previously unrecognized plasticity. No evidence of interconnectivity was identified, consistent with the concept that foci represent discrete sites of lung injury and repair.

Persistent culture-positive Legionella infection in an immunocompromised host.

Legionella pneumophila is an important cause of community-acquired and nosocomial pneumonia. We describe an immunocompromised patient with severe pneumonia from whom Legionella species were isolated from sputum samples by culture for 30 days, despite administration of treatment with appropriate antimicrobial agents. However, clear improvement in the patient's respiratory condition was evident, and he subsequently recovered completely.

The clinical effectiveness and cost-effectiveness of treatments for idiopathic pulmonary fibrosis: a systematic review and economic evaluation.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a life-limiting lung disease that generally affects people over 60 years old. The main symptoms are shortness of breath and cough, and as the disease progresses there is a considerable impact on day-to-day life. Few treatments are currently available. OBJECTIVES: To conduct a systematic review of clinical effectiveness and an analysis of cost-effectiveness of treatments for IPF based on an economic model informed by systematic reviews of cost-effectiveness and quality of life. DATA SOURCES: Eleven electronic bibliographic databases, including MEDLINE, EMBASE, Web of Science, and The Cochrane Library and the Centre for Reviews and Dissemination databases, were searched from database inception to July 2013. Reference lists of relevant publications were also checked and experts consulted. METHODS: Two reviewers independently screened references for the systematic reviews, extracted and checked data from the included studies and appraised their risk of bias. An advisory group was consulted about the choice of interventions until consensus was reached about eligibility. A narrative review with meta-analysis was undertaken, and a network meta-analysis (NMA) was performed. A decision-analytic Markov model was developed to estimate cost-effectiveness of pharmacological treatments for IPF. Parameter values were obtained from NMA and systematic reviews. Univariate and probabilistic sensitivity analyses were undertaken. The model perspective is NHS and Personal Social Services, and discount rate is 3.5% for costs and health benefits. RESULTS: Fourteen studies were included in the review of clinical effectiveness, of which one evaluated azathioprine, three N-acetylcysteine (NAC) (alone or in combination), four pirfenidone, one BIBF 1120, one sildenafil, one thalidomide, two pulmonary rehabilitation, and one a disease management programme. Study quality was generally good, with a low risk of bias. The current evidence suggests that some treatments appear to be clinically effective. The model base-case results show increased survival for five pharmacological treatments, compared with best supportive care, at increased cost. General recommendations cannot be made of their cost-effectiveness owing to limitations in the evidence base. LIMITATIONS: Few direct comparisons of treatments were identified. An indirect comparison through a NMA was performed; however, caution is recommended in the interpretation of these results. In relation to the economic model, there is an assumption that pharmacological treatments have a constant effect on the relative rate of per cent predicted forced vital capacity decline. CONCLUSIONS: Few interventions have any statistically significant effect on IPF and a lack of studies on palliative care approaches was identified. Research is required into the effects of symptom control interventions, in particular pulmonary rehabilitation and thalidomide. Other research priorities include a well-conducted randomised controlled trial on inhaled NAC therapy and an updated evidence synthesis once the results of ongoing studies are reported. STUDY REGISTRATION: This study is registered as PROSPERO CRD42012002116. FUNDING: The National Institute for Health Research Health Technology Assessment programme.

The effectiveness and cost-effectiveness of treatments for idiopathic pulmonary fibrosis: systematic review, network meta-analysis and health economic evaluation.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a life-limiting lung disease with considerable impact on patients and carers as the disease progresses. Currently few treatments are available. We aimed to evaluate the clinical and cost-effectiveness of available treatments for IPF. METHODS: Systematic reviews of clinical effectiveness, quality of life and cost effectiveness were undertaken. Eleven bibliographic databases were searched from inception to July 2013 and studies were assessed for eligibility against a set of pre-defined criteria. Two reviewers screened references, extracted data from included studies and appraised their quality. An advisory group was consulted about the choice of interventions. A narrative review was undertaken and where feasible fixed effect and random effects meta-analysis were undertaken including a network meta-analysis (NMA). A decision-analytic Markov model was developed to estimate cost-effectiveness of pharmacological treatments for IPF. Following best practice recommendations, the model perspective was of the national health service and personal social services, a discount rate of 3.5% for costs and health benefits was applied and outcomes were expressed as cost per quality adjusted life-year gained. Parameter values were obtained from the NMA and systematic reviews. Sensitivity analyses were undertaken. RESULTS: Fourteen studies were included in the review of clinical effectiveness, of which one evaluated azathioprine, three N-acetylcysteine [NAC] (alone or in combination), four pirfenidone, one nintedanib, one sildenafil, one thalidomide, two pulmonary rehabilitation, and one a disease management programme. Study quality was generally good. Evidence suggests that some effective treatments are available. In NMA only nintedanib and pirfenidone show statistically significant improvements. The model results show increased survival for five pharmacological treatments (NAC triple therapy, inhaled NAC, nintedanib, pirfenidone, and sildenafil) compared with best supportive care, at increased cost. Only inhaled NAC was cost-effective at current willingness to pay thresholds but it may not be clinically effective. CONCLUSIONS: Few interventions have any statistically significant effect and the cost-effectiveness of treatments is uncertain. A lack of studies on palliative care approaches was identified and there is a need for further research into pulmonary rehabilitation and thalidomide in particular. A well conducted RCT on inhaled NAC therapy should also be considered.

Asbestos-related lung disease.

The inhalation of asbestos fibers may lead to a number of respiratory diseases, including lung cancer, asbestosis, pleural plaques, benign pleural effusion, and malignant mesothelioma. Although exposure is now regulated, patients continue to present with these diseases because of the long latent period between exposure and clinical disease. Presenting signs and symptoms tend to be nonspecific; thus, the occupational history helps guide clinical suspicion. High-risk populations include persons in construction trades, boilermakers, shipyard workers, railroad workers, and U.S. Navy veterans. Every effort should be made to minimize ongoing exposure. Patients with a history of significant asbestos exposure may warrant diagnostic testing and follow-up assessment, although it is unclear whether this improves outcomes. Patients with significant exposure and dyspnea should have chest radiography and spirometry. The prognosis depends on the specific disease entity. Asbestosis generally progresses slowly, whereas malignant mesothelioma has an extremely poor prognosis. The treatment of patients with asbestos exposure and lung cancer is identical to that of any patient with lung cancer. Because exposure to cigarette smoke increases the risk of developing lung cancer in patients with a history of asbestos exposure, smoking cessation is essential. Patients with asbestosis or lung cancer should receive influenza and pneumococcal vaccinations.

Crystalline and amorphous silica differentially regulate the cyclooxygenase-prostaglandin pathway in pulmonary fibroblasts: implications for pulmonary fibrosis.

Inhalation of crystalline (CS) and amorphous silica (AS) results in human pulmonary inflammation. However, silicosis develops only following CS exposure, and the pathogenic mechanisms are poorly understood. This report describes the differential abilities of CS and AS to directly upregulate the early inflammatory mediator COX-2, the recently identified prostaglandin E (PGE) synthase and the downstream mediator PGE2 in primary human lung fibroblasts. Increased cyclooxygenase (COX)-2 gene transcription and protein production were demonstrated by ribonuclease protection assay, Western blot analysis, and immunocytochemistry. In each case the ability of AS to induce COX-2 exceeded that of CS. Similarly, downstream of COX-2, production of the antifibrotic prostaglandin PGE2 was induced in a dose-dependent fashion, but AS was significantly more potent (maximal production: CS = 4,710 pg/ml and AS = 7,651 pg/ml). These increases in COX-2 and PGE2 were preceded by induction of the PGE2 synthase protein, demonstrating the potential role of this novel molecule in silica-mediated inflammation. There was specificity of induction of prostaglandins, as PGF2alpha, but not PGD2, was induced. Using specific COX-2 inhibitors, we showed increased PG production to be dependent on the COX-2 enzyme. Furthermore, stimulation of fibroblasts was particle specific, as silica but not carbon black resulted in fibroblast activation. These results demonstrate that silica can directly stimulate human lung fibroblasts to produce key inflammatory enzymes and prostaglandins. Moreover, they suggest a mechanism to explain the differing fibrogenic potential of CS and AS. The molecules COX-2, PGE synthase, and PGE2 are identified as effectors in silicosis.

Cigarette smoke induces cyclooxygenase-2 and microsomal prostaglandin E2 synthase in human lung fibroblasts: implications for lung inflammation and cancer.

Cigarette smoking can lead to many human pathologies including cardiovascular and respiratory disease. Recent studies have defined a role for fibroblasts in the development of colon cancer. Moreover, fibroblasts are now thought of as key "sentinel" cells that initiate inflammation by releasing proinflammatory mediators including prostaglandins (PGs). Pathological overexpression of cyclooxygenase-2 (COX-2) and excess eicosanoid production are found in the early stages of carcinogenesis. By promoting chronic inflammation, COX-2 and eicosanoid production may actually cause a predisposition to malignancy. Furthermore, the associated inflammation induced by production of these mediators is central to the pathogenesis of chronic obstructive pulmonary disease. Little is known of the responses of normal lung fibroblasts to cigarette smoke, despite their abundance. We report herein that normal human lung fibroblasts, when exposed to cigarette smoke extract, induce COX-2 with concurrent synthesis of prostaglandin E2 (PGE2). The mechanisms by which cigarette-derived toxicants lead to increased COX-2 levels and PGE2 synthesis include increases in steady-state COX-2 mRNA levels (approximately four- to fivefold), phosphorylation of ERK1/2, and nuclear translocation of the p50 and p65 subunits of the transcription factor NF-kappaB, which are important elements in COX-2 expression. Furthermore, there was a dramatic 25-fold increase in microsomal prostaglandin E synthase, the key enzyme involved in the production of PGE2. We propose that normal human lung fibroblasts, when exposed to cigarette smoke constituents, elicit COX-2 expression with consequent prostaglandin synthesis, thus creating a proinflammatory environment. This chronic inflammatory state may act as one of the first steps towards epithelial transformation.