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

What Do We Need to Know About Rising Rates of Idiopathic Pulmonary Fibrosis? A Narrative Review and Update

The most common type of idiopathic interstitial pneumonia is idiopathic pulmonary fibrosis (IPF), an irreversible, progressive disorder that has lately come into question for possible associations with COVID-19. With few geographical exceptions, IPF is a rare disease but its prevalence has been increasing markedly since before the pandemic. Environmental exposures are frequently implicated in IPF although genetic factors play a role as well. In IPF, healthy lung tissue is progressively replaced with an abnormal extracellular matrix that impedes normal alveolar function while, at the same time, natural repair mechanisms become dysregulated. While chronic viral infections are known risk factors for IPF, acute infections are not and the link to COVID-19 has not been established. Macrophagy may be a frontline defense against any number of inflammatory pulmonary diseases, and the inflammatory cascade that may occur in patients with COVID-19 may disrupt the activity of monocytes and macrophages in clearing up fibrosis and remodeling lung tissue. It is unclear if COVID-19 infection is a risk factor for IPF, but the two can occur in the same patient with complicating effects. In light of its increasing prevalence, further study of IPF and its diagnosis and treatment is warranted.

Impact of COVID-19 pneumonia on interstitial lung disease: semi-quantitative evaluation with computed tomography

OBJECTIVES

To evaluate the CT scores and fibrotic pattern changes in interstitial lung disease (ILD) patients, with and without previous COVID-19 pneumonia.

METHODS

Patients with ILD (idiopathic pulmonary fibrosis (IPF) and connective tissue disease-associated ILD (CTD-ILD)) were retrospectively enrolled in the study which consisted of patients who had COVID-19 pneumonia while the control group had not. All patients had two CT scans, initial and follow-up, which were evaluated semi-quantitatively for severity, extent, and total CT scores, fibrosis patterns, and traction bronchiectasis.

RESULTS

A total of 102 patients (pneumonia group n = 48; control group n = 54) were enrolled in the study. For both groups, baseline characteristics were similar and CT scores were increased. While there was a 4.5 ± 4.6 point change in the total CT score of the COVID-19 group, there was a 1.2 ± 2.7 point change in the control group (p < 0.001). In the IPF subgroup, the change in total CT score was 7.0 points (95% CI: 4.1 to 9.9) in the COVID-19 group and 2.1 points (95% CI: 0.8 to 3.4) in the control group. Seven patients (14.6%) in the COVID-19 group progressed to a higher fibrosis pattern, but none in the control group.

CONCLUSIONS

Semi-quantitative chest CT scores in ILD patients demonstrated a significant increase after having COVID-19 pneumonia compared to ILD patients who had not had COVID-19 pneumonia. The increase in CT scores was more prominent in the IPF subgroup. There was also a worsening in the fibrosis pattern in the COVID-19 group.

KEY POINTS

• The impact of COVID-19 pneumonia on existing interstitial lung diseases and fibrosis is unclear. • COVID-19 pneumonia may worsen existing interstitial lung involvement with direct lung damage and indirect inflammatory effect. • COVID-19 pneumonia may affect existing lung fibrosis by triggering inflammatory pathways.

Idiopathic pulmonary fibrosis therapy development: a clinical pharmacology perspective

Drug development for idiopathic pulmonary fibrosis (IPF) has been challenging due to poorly understood disease etiology, unpredictable disease progression, highly heterogeneous patient populations, and a lack of robust pharmacodynamic biomarkers. Moreover, because lung biopsy is invasive and dangerous, making the extent of fibrosis as a direct longitudinal measurement of IPF disease progression unfeasible, most clinical trials studying IPF can only assess progression of fibrosis indirectly through surrogate measures. This review discusses current state-of-art practices, identifies knowledge gaps, and brainstorms development opportunities for preclinical to clinical translation, clinical populations, pharmacodynamic endpoints, and dose optimization strategies. This article highlights clinical pharmacology perspectives in leveraging real-world data as well as modeling and simulation, special population considerations, and patient-centric approaches for designing future studies.

Bacterial and viral coinfection in idiopathic pulmonary fibrosis patients: the prevalence and possible role in disease progression

Background

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial pneumonia of unknown aetiology with a mean survival rate of less than 3 years. No previous studies have been performed on the role of co-infection (viral and bacterial infection) in the pathogenesis and progression of IPF. In this study, we investigated the role of viral/bacterial infection and coinfection and their possible association with pathogenesis and progression of IPF.

Methods

We investigated the prevalence and impact of bacterial and viral coinfection in IPF patients (n = 67) in the context of pulmonary function (FVC, FEV₁ and DL_CO), disease status and mortality risk. Using principal component analysis (PCA), we also investigated the relationship between distribution of bacterial and viral co-infection in the IPF cohort.

Results

Of the 67 samples, 17.9% samples were positive for viral infection, 10.4% samples were positive for bacterial infection and 59.7% samples were positive coinfection. We demonstrated that IPF patients who were co-infected had a significantly increased risk of mortality compared (p = 0.031) with IPF patients who were non-infected [Hazard ratio: 8.12; 95% CI 1.3–26.9].

Conclusion

In this study, we report for the first time that IPF patients who were coinfected with bacterial and viral infection have significantly decreased FVC and DL_CO (% predicted). Besides, the results demonstrated the increased AE-IPF, increased incidence of death and risk of mortality in infected/coinfected patients compared to non-infected IPF patients.

Microbiota and IPF: hidden and detected relationships

Lung microbiota (LM) is an interesting new way to consider and redesign pathogenesis and possible therapeutic approach to many lung diseases, such as idiopathic pulmonary fibrosis (IPF), which is an interstitial pneumonia with bad prognosis. Chronic inflammation is the basis but probably not the only cause of lung fibrosis and although the risk factors are not completely clear, endogenous factors (e.g. gastroesophageal reflux) and environmental factors like cigarette smoking, industrial dusts, and precisely microbial agents could contribute to the IPF development. It is well demonstrated that many bacteria can cause epithelial cell injuries in the airways through induction of a host immune response or by activating flogosis mediators following a chronic, low-level antigenic stimulus. This persistent host response could influence fibroblast responsiveness suggesting that LM may play a role in repetitive alveolar injury in IPF. We reviewed literature regarding not only bacteria but also the role of virome and mycobiome in IPF. In fact, some viruses such as hepatitis C virus or certain fungi could be etiological agents or co-factors in the IPF progress. We aim to illustrate how the cross-talk between different local microbiotas throughout specific axis and immune modulation governed by microorganisms could be at the basis of lung dysfunctions and IPF development. Finally, since the future direction of medicine will be personalized, we suggest that the analysis of LM could be a goal to research new therapies also in IPF.

Lung Tissue Microbiome Is Associated With Clinical Outcomes of Idiopathic Pulmonary Fibrosis

Background: Several studies using bronchoalveolar lavage fluid (BALF) reported that lung microbial communities were associated with the development and clinical outcome of idiopathic pulmonary fibrosis (IPF). However, the microbial communities in IPF lung tissues are not well known. This study is aimed to investigate bacterial microbial communities in lung tissues and determine their impact on the clinical outcomes of patients with IPF. Methods: Genomic DNA extracted from lung tissues of patients with IPF (n = 20; 10 non-survivors) and age- and sex-matched controls (n = 20) was amplified using fusion primers targeting the V3 and V4 regions of the 16S RNA genes with indexing barcodes. Results: Mean age of IPF subjects was 63.3 yr, and 65% were male. Alpha diversity indices did not significantly differ between IPF patients and controls, or between IPF non-survivors and survivors. The relative abundance of Lactobacillus, Paracoccus, and Akkermansia was increased, whereas that of Caulobacter, Azonexus, and Undibacterium decreased in patients with IPF compared with that in the controls. A decreased relative abundance of Pelomonas (odds ratio [OR], 0.352, p = 0.027) and Azonexus (OR, 0.013, p = 0.046) was associated with a diagnosis of IPF in the multivariable logistic analysis adjusted by age and gender. Multivariable Cox analysis adjusted for age and forced vital capacity (FVC) revealed that higher relative abundance of Streptococcus (hazard ratio [HR], 1.993, p = 0.044), Sphingomonas (HR, 57.590, p = 0.024), and Clostridium (HR, 37.189, p = 0.038) was independently associated with IPF mortality. The relative abundance of Curvibacter (r = 0.590) and Thioprofundum (r = 0.373) was correlated positively, whereas that of Anoxybacillus (r = -0.509) and Enterococcus (r = -0.593) was correlated inversely with FVC. In addition, the relative abundance of the Aquabacterium (r = 0.616) and Peptoniphilus (r = 0.606) genera was positively correlated, whereas that of the Fusobacterium (r = -0.464) and Phycicoccus (r = -0.495) genera was inversely correlated with distance during the 6-min walking test. Conclusions: The composition of the microbiome in lung tissues differed between patients with IPF and controls and was associated with the diagnosis, mortality, and disease severity of IPF.

The Role of Microbiome and Virome in Idiopathic Pulmonary Fibrosis

The interest in the lung microbiome and virome and their contribution to the pathogenesis, perpetuation and progression of idiopathic pulmonary fibrosis (IPF) has been increasing during the last decade. The utilization of high-throughput sequencing to detect microbial and/or viral genetic material in bronchoalveolar lavage fluid or lung tissue samples has amplified the ability to identify and quantify specific microbial and viral populations. In stable IPF, higher microbial burden is associated with worse prognosis but no specific microbe has been identified to contribute to this. Additionally, no causative relation has been established. Regarding viral infections, although in the past they have been associated with IPF, causation has not been proved. Although in the past the diagnosis of acute exacerbation of IPF (AE-IPF) was not considered in patients with overt infection, this was amended in the last few years and infection is considered a cause for exacerbation. Besides this, a higher microbial burden has been found in the lungs of patients with AE-IPF and an association with higher morbidity and mortality has been confirmed. In contrast, an association of AE-IPF with viral infection has not been established. Despite the progress during the last decade, a comprehensive knowledge of the microbiome and virome in IPF and their role in disease pathogenesis are yet elusive. Although association with disease severity, risk for progression and mortality has been established, causation has not been proven and the potential use as a biomarker or the benefits of antimicrobial therapeutic strategies are yet to be determined.

The role of viral and bacterial infections in the pathogenesis of IPF: a systematic review and meta-analysis

Background

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease. Several risk factors such as smoking, air pollution, inhaled toxins, high body mass index and infectious agents are involved in the pathogenesis of IPF. In the present study, this meta-analysis study investigates the prevalence of viral and bacterial infections in the IPF patients and any possible association between these infections with pathogenesis of IPF.

Methods

The authors carried out this systematic literature review from different reliable databases such as PubMed, ISI Web of Science, Scopus and Google Scholar to December 2020.Keywords used were the following “Idiopathic pulmonary fibrosis”, “Infection”, “Bacterial Infection” and “Viral Infection”, alone or combined together with the Boolean operators "OR”, “AND” and “NOT” in the Title/Abstract/Keywords field. Pooled proportion and its 95% CI were used to assess the prevalence of viral and bacterial infections in the IPF patients.

Results

In this systematic review and meta-analyses, 32 studies were selected based on the exclusion/inclusion criteria. Geographical distribution of included studies was: eight studies in American people, 8; in European people, 15 in Asians, and one in Africans. The pooled prevalence for viral and bacterial infections w ere 53.72% (95% CI 38.1–69.1%) and 31.21% (95% CI 19.9–43.7%), respectively. The highest and lowest prevalence of viral infections was HSV (77.7% 95% CI 38.48–99.32%), EBV (72.02%, 95% CI 44.65–90.79%) and Influenza A (7.3%, 95% CI 2.66–42.45%), respectively. Whereas the highest and lowest prevalence in bacterial infections were related to Streptococcus sp. (99.49%, 95% CI 96.44–99.9%) and Raoultella (1.2%, 95% CI 0.2–3.08%), respectively.

Conclusions

The results of this review were confirmed that the presence of viral and bacterial infections are the risk factors in the pathogenesis of IPF. In further analyses, which have never been shown in the previous studies, we revealed the geographic variations in the association strengths and emphasized other methodological parameters (e.g., detection method). Also, our study supports the hypothesis that respiratory infection could play a key role in the pathogenesis of IP.

Association of COVID-19 and other viral infections with interstitial lung diseases, pulmonary fibrosis, and pulmonary hypertension: A narrative review

Background

Interstitial lung diseases (ILDs) include a broad range of diffuse parenchymal lung disorders and are characterized by diffuse parenchymal lung abnormalities leading to irreversible fibrosis. ILDs are correlated with the occurrence of pulmonary fibrosis (PF), which generally also results in pulmonary hypertension (PH). Interferons, secreted in larger amounts during viral infections, are an important possible risk factor contributing to this outcome.

Aims

In this narrative review, the role of 10 different viral infections on the generation/development of ILDs and their outcomes are described in detail. The aim of this review is to determine the probable risk that COVID-19 and other viral infections pose in the post-infection development of ILDs, PF, and PH.

Methods

Searches in PubMed (Medline), Google Scholar, Web of Science (ISI, Researcher ID, Publons), ResearchGate, Scopus, and secondary sources yielded 134 studies. After exclusion criteria, 92 studies containing the terms “Coronavirus” (COVID-19), “Interstitial Lung Diseases,” “Pulmonary Fibrosis,” “Pulmonary Hypertension” and “viral infections” were selected for inclusion. Selected articles were read with a focus on the roles of the 10 commonly studied viral infections on generation/intensification of ILDs and classified according to their dominant effect on the respiratory system, with a focus on each infection’s effects on parenchyma of the lungs and generation and/or intensification of ILDs.

Results

This review found that ILDs, PF, and PH can occur after a COVID-19 viral infection. Similar results are also seen in post-infection cases of other viral infections, including Epstein–Barr virus, Cytomegalovirus, Human herpesvirus-8, adenovirus, Hepatitis C, Torque-Teno (Transfusion-Transmitted) Virus, Human Immunodeficiency Virus, Severe Acute Respiratory Syndrome, and Middle East Respiratory Syndrome.

Conclusion

Results of current studies show probable possibility for generation and/or intensification of ILDs in COVID-19 infected patients like other studied viruses. Studies on determination of the actual prevalence of ILD, PF and PH in post-COVID-19 infected patients, follow-up studies on the prevention of ILDs in recovered COVID-19 patients, and meta-analyzed studies on pulmonary outcomes of pandemic corona viruses are strongly recommended as topics for future studies.

Emerging cellular and molecular determinants of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF), the most common form of idiopathic interstitial pneumonia, is a progressive, irreversible, and typically lethal disease characterized by an abnormal fibrotic response involving vast areas of the lungs. Given the poor knowledge of the mechanisms underpinning IPF onset and progression, a better understanding of the cellular processes and molecular pathways involved is essential for the development of effective therapies, currently lacking. Besides a number of established IPF-associated risk factors, such as cigarette smoking, environmental factors, comorbidities, and viral infections, several other processes have been linked with this devastating disease. Apoptosis, senescence, epithelial-mesenchymal transition, endothelial-mesenchymal transition, and epithelial cell migration have been shown to play a key role in IPF-associated tissue remodeling. Moreover, molecules, such as chemokines, cytokines, growth factors, adenosine, glycosaminoglycans, non-coding RNAs, and cellular processes including oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, hypoxia, and alternative polyadenylation have been linked with IPF development. Importantly, strategies targeting these processes have been investigated to modulate abnormal cellular phenotypes and maintain tissue homeostasis in the lung. This review provides an update regarding the emerging cellular and molecular mechanisms involved in the onset and progression of IPF.

Assessment of viral RNA in idiopathic pulmonary fibrosis using RNA-seq

Background

Numerous publications suggest an association between herpes virus infection and idiopathic pulmonary fibrosis (IPF). These reports have employed immunohistochemistry, in situ hybridization and/or PCR, which are susceptible to specificity artifacts.

Methods

We investigated the possible association between IPF and viral RNA expression using next-generation sequencing, which has the potential to provide a high degree of both sensitivity and specificity. We quantified viral RNA expression for 740 viruses in 28 IPF patient lung biopsy samples and 20 controls. Key RNA-seq results were confirmed using Real-time RT-PCR for select viruses (EBV, HCV, herpesvirus saimiri and HERV-K).

Results

We identified sporadic low-level evidence of viral infections in our lung tissue specimens, but did not find a statistical difference for expression of any virus, including EBV, herpesvirus saimiri and HERV-K, between IPF and control lungs.

Conclusions

To the best of our knowledge, this is the first publication that employs RNA-seq to assess whether viral infections are linked to the pathogenesis of IPF. Our results do not address the role of viral infection in acute exacerbations of IPF, however, this analysis patently did not support an association between herpes virus detection and IPF.

The Role of the Lung's Microbiome in the Pathogenesis and Progression of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrosing interstitial lung disease that commonly affects older adults and is associated with the histopathological and/or radiological patterns of usual interstitial pneumonia (UIP). Despite significant advances in our understanding of disease pathobiology and natural history, what causes IPF remains unknown. A potential role for infection in the disease's pathogenesis and progression or as a trigger of acute exacerbation has long been postulated, but initial studies based on traditional culture methods have yielded inconsistent results. The recent application to IPF of culture-independent techniques for microbiological analysis has revealed previously unappreciated alterations of the lung microbiome, as well as an increased bacterial burden in the bronchoalveolar lavage (BAL) of IPF patients, although correlation does not necessarily entail causation. In addition, the lung microbiome remains only partially characterized and further research should investigate organisms other than bacteria and viruses, including fungi. The clarification of the role of the microbiome in the pathogenesis and progression of IPF may potentially allow its manipulation, providing an opportunity for targeted therapeutic intervention.

Diagnosis of Idiopathic Pulmonary Fibrosis. An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline

BACKGROUND

This document provides clinical recommendations for the diagnosis of idiopathic pulmonary fibrosis (IPF). It represents a collaborative effort between the American Thoracic Society, European Respiratory Society, Japanese Respiratory Society, and Latin American Thoracic Society.

METHODS

The evidence syntheses were discussed and recommendations formulated by a multidisciplinary committee of IPF experts. The evidence was appraised and recommendations were formulated, written, and graded using the Grading of Recommendations, Assessment, Development, and Evaluation approach.

RESULTS

The guideline panel updated the diagnostic criteria for IPF. Previously defined patterns of usual interstitial pneumonia (UIP) were refined to patterns of UIP, probable UIP, indeterminate, and alternate diagnosis. For patients with newly detected interstitial lung disease (ILD) who have a high-resolution computed tomography scan pattern of probable UIP, indeterminate, or an alternative diagnosis, conditional recommendations were made for performing BAL and surgical lung biopsy; because of lack of evidence, no recommendation was made for or against performing transbronchial lung biopsy or lung cryobiopsy. In contrast, for patients with newly detected ILD who have a high-resolution computed tomography scan pattern of UIP, strong recommendations were made against performing surgical lung biopsy, transbronchial lung biopsy, and lung cryobiopsy, and a conditional recommendation was made against performing BAL. Additional recommendations included a conditional recommendation for multidisciplinary discussion and a strong recommendation against measurement of serum biomarkers for the sole purpose of distinguishing IPF from other ILDs.

CONCLUSIONS

The guideline panel provided recommendations related to the diagnosis of IPF.

Hepatitis C virus infection could affect the pathogenesis of ischemic heart diseases in northern Japan

AIMS

Previously, our group reported that lymphotropic hepatitis C virus (HCV) could induce various kinds of immune dysfunctions. The immune dysfunctions could cause vascular disease by inducing cryoglobulinemia. It has been reported that ischemic heart diseases might be caused by HCV. However, the infectious rate of HCV in patients with ischemic heart disease has not been clarified in northern Japan. Therefore, we tried to determine the rate of HCV infectivity in patients with ischemic heart disease.

METHODS

The target patients of this study were automatically selected using an electronic medical record system to exclude selection bias. The system identified 16 484 patients with ischemic heart disease who were included in this study. In addition, 12 902 subjects who had received medical checkups were included as the control group.

RESULTS

The positive rate of HCV antibody among the patients with ischemic disease in our hospital was 2.58%, which was significantly higher (P < 0.01) than in the medical checkup patients (0.84%). The positive rate of HCV antibody in the patients with ischemic heart disease in each age group was significantly higher than in the corresponding age groups of the medical checkup patients. The rate of chronic kidney disease in HCV antibody-positive patients treated by percutaneous coronary intervention (PCI) was significantly higher than in HCV antibody-negative patients treated by PCI (P = 0.02).

CONCLUSIONS

Hepatitis C virus infection might be associated with the pathogenesis of ischemic heart disease and HCV antibody positivity might be a risk factor for ischemic heart disease in northern Japan.

Korean Guidelines for Diagnosis and Management of Interstitial Lung Diseases: Part 2. Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive fibrosing interstitial pneumonia, which presents with a progressive worsening dyspnea, and thus a poor outcome. The members of the Korean Academy of Tuberculosis and Respiratory Diseases as well as the participating members of the Korea Interstitial Lung Disease Study Group drafted this clinical practice guideline for IPF management. This guideline includes a wide range of topics, including the epidemiology, pathogenesis, risk factors, clinical features, diagnosis, treatment, prognosis, and acute exacerbation of IPF in Korea. Additionally, we suggested the PICO for the use of pirfenidone and nintendanib and for lung transplantation for the treatment of patients with IPF through a systemic literature review using experts' help in conducting a meta-analysis. We recommend this guideline to physicians, other health care professionals, and government personnel in Korea, to facilitate the treatment of patients with IPF.

Uncommon immune-mediated extrahepatic manifestations of HCV infection

INTRODUCTION

Chronic hepatitis C virus (HCV) infection has been associated with myriad extrahepatic manifestations, often resulting from aberrant immune responses. Among the most common immune-mediated manifestations of HCV infection, mixed cryoglobulinemia is the best known extra-hepatic complication. Areas covered: Here we review less common extrahepatic manifestations of HCV infection, with ascertained or presumed immune pathogenesis and the role of the new all oral direct-acting antiviral agents. Rheumatologic, dermatologic, ophthalmologic, renal, pulmonary, hematologic, cardiovascular, and neuropsychiatric manifestations of HCV infection have been considered. Expert commentary: Pathogenesis of HCV-induced aberrant immune responses resulting in peculiar clinical manifestations is not restricted to a single mechanism. A sound approach would therefore consider implementation of an etiologic treatment, through use of antiviral medications, to stop upstream in the pathogenic process all the immune mechanisms leading to hepatic and extrahepatic abnormalities. With the recent introduction of interferon-free, direct antiviral agents, capable of warranting cure for nearly all HCV-infected patients subjected to therapy, both common and uncommon extrahepatic manifestations of chronic hepatitis C are expected to no longer constitute a matter of comorbidity in the course of HCV infection.

Risk factors for interstitial lung disease: a 9-year Nationwide population-based study

Background

Understanding the risk factors that are associated with the development of interstitial lung disease might have an important role in understanding the pathogenetic mechanism of interstitial lung disease as well as prevention. We aimed to determine independent risk factors of interstitial lung disease development.

Methods

This was a retrospective cohort study with nationwide population-based 9-year longitudinal data. We selected subjects who were aged > 40 years at cohort entry and with a self-reported history of cigarette smoking. Cases were selected based on International Classification of Diseases codes. A cohort of 312,519 subjects were followed until December 2013. We used Cox regression analysis to calculate the hazard ratios (HRs) for interstitial lung disease development.

Results

Interstitial lung disease developed in 1972 of the 312,519 subjects during the 9-year period. Smoking (HR: 1.2; 95% confidence interval [CI]: 1.1–1.4), hepatitis C (HR: 1.6; 95% CI: 1.1–2.3), history of tuberculosis (HR: 1.5; 95% CI: 1.1–1.9), history of pneumonia (HR: 1.6; 95% CI: 1.3–2.0), and chronic obstructive pulmonary disease (HR: 1.8; 95% CI: 1.6–2.1), men (HR: 1.9; 95% CI: 1.7–2.1) were significantly associated with the development of interstitial lung disease. The risk of interstitial lung disease development increases with age, and the risk was 6.9 times higher (95% CI: 5.9–8.0) in those aged over 70 than in their forties.

Conclusions

Smoking, hepatitis C, history of tuberculosis, history of pneumonia, chronic obstructive pulmonary disease, male sex, and older age were significantly associated with interstitial lung disease development.

EZH2 enhances the differentiation of fibroblasts into myofibroblasts in idiopathic pulmonary fibrosis

The accumulation of fibroblasts/myofibroblasts in fibrotic foci is one of the characteristics of idiopathic pulmonary fibrosis (IPF). Enhancer of zeste homolog 2 (EZH2) is the catalytic component of a multiprotein complex, polycomb repressive complex 2, which is involved in the trimethylation of histone H3 at lysine 27. In this study, we investigated the role and mechanisms of EZH2 in the differentiation of fibroblasts into myofibroblasts. We found that EZH2 was upregulated in the lungs of patients with IPF and in mice with bleomycin-induced lung fibrosis. The upregulation of EZH2 occurred in myofibroblasts. The inhibition of EZH2 by its inhibitor 3-deazaneplanocin A (DZNep) or an shRNA reduced the TGF-β1-induced differentiation of human lung fibroblasts into myofibroblasts, as demonstrated by the expression of the myofibroblast markers α-smooth muscle actin and fibronectin, and contractility. DZNep inhibited Smad2/3 nuclear translocation without affecting Smad2/3 phosphorylation. DZNep treatment attenuated bleomycin-induced pulmonary fibrosis in mice. We conclude that EZH2 induces the differentiation of fibroblasts to myofibroblasts by enhancing Smad2/3 nuclear translocation.

Hepatitis C Virus-Associated Extrahepatic Manifestations in Lung and Heart and Antiviral Therapy-Related Cardiopulmonary Toxicity

Besides liver cirrhosis and hepatocellular carcinoma, chronic hepatitis C virus (HCV) infection is associated with many extrahepatic manifestations (EHMs). HCV exhibits lymphotropism that is responsible for various EHM. An important characteristic of HCV is escape from the immune system, which enables it to produce chronic infections and autoimmune disorders along with accumulation of circulating immune complexes. These EHMs have large spectrum, because they affect many organs such as heart, lungs, kidney, brain, thyroid, and skin. HCV-related cardiac and pulmonary manifestations include myocarditis, cardiomyopathies, cardiovascular diseases (i.e., Stroke, ischemic heart disease), chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, asthma, and interstitial lung diseases. This review discusses etiology and pathogenesis of HCV-associated cardiac and pulmonary manifestations and how different genes, immune system, indirectly linked factors (mixed cryoglobulinemia), liver cirrhosis, and antiviral treatment are involved in HCV-related heart and lung diseases, however, their exact mechanism is not clear.

Other Extrahepatic Manifestations of Hepatitis C Virus Infection (Pulmonary, Idiopathic Thrombocytopenic Purpura, Nondiabetes Endocrine Disorders)

Extrahepatic manifestations of hepatitis C virus (HCV) infection are a rare but serious condition. This article summarizes the current literature on the association between HCV and endocrine and pulmonary manifestations, as well as idiopathic thrombocytopenic purpura (ITP). HCV may directly infect extrahepatic tissues and interact with the immune system predisposing for obstructive and interstitial lung disease, ITP, autoimmune thyroiditis, infertility, growth hormone and adrenal deficiencies, osteoporosis, and potentially lung and thyroid cancers. However, in many cases, the current evidence is divergent and cannot sufficiently confirm a true association, which emphasizes the need for future targeted projects in this field.

The Role of Infection in Interstitial Lung Diseases: A Review

Interstitial lung disease (ILD) comprises an array of heterogeneous parenchymal lung diseases that are associated with a spectrum of pathologic, radiologic, and clinical manifestations. There are ILDs with known causes and those that are idiopathic, making treatment strategies challenging. Prognosis can vary according to the type of ILD, but many exhibit gradual progression with an unpredictable clinical course in individual patients, as seen in idiopathic pulmonary fibrosis and the phenomenon of "acute exacerbation"(AE). Given the often poor prognosis of these patients, the search for a reversible cause of respiratory worsening remains paramount. Infections have been theorized to play a role in ILDs, both in the pathogenesis of ILD and as potential triggers of AE. Research efforts thus far have shown the highest association with viral pathogens; however, fungal and bacterial organisms have also been implicated. This review aims to summarize the current knowledge on the role of infections in the setting of ILD.

Classification of idiopathic interstitial pneumonias using anti-myxovirus resistance-protein 1 autoantibody

Chronic fibrosing idiopathic interstitial pneumonia (IIP) can be divided into two main types: idiopathic pulmonary fibrosis (IPF), a steroid-resistant and progressive disease with a median survival of 2-3 years, and idiopathic non-specific interstitial pneumonia (INSIP), a steroid-sensitive and non-progressive autoimmune disease. Although the clinical courses of these two diseases differ, they may be difficult to distinguish at diagnosis. We performed a comprehensive analysis of serum autoantibodies from patients definitively diagnosed with IPF, INSIP, autoimmune pulmonary alveolar proteinosis, and sarcoidosis. We identified disease-specific autoantibodies and enriched KEGG pathways unique to each disease, and demonstrated that IPF and INSIP are serologically distinct. Furthermore, we discovered a new INSIP-specific autoantibody, anti-myxovirus resistance-1 (MX1) autoantibody. Patients positive for anti-MX1 autoantibody constituted 17.5% of all cases of chronic fibrosing IIPs. Notably, patients rarely simultaneously carried the anti-MX1 autoantibody and the anti-aminoacyl-transfer RNA synthetase autoantibody, which is common in chronic fibrosing IIPs. Because MX1 is one of the most important interferon-inducible anti-viral genes, we have not only identified a new diagnostic autoantibody of INSIP but also obtained new insight into the pathology of INSIP, which may be associated with viral infection and autoimmunity.

Viruses in Idiopathic Pulmonary Fibrosis. Etiology and Exacerbation

Viral infections are important contributors to exacerbation of asthma and chronic obstructive pulmonary disease; however, the role of viruses in the pathogenesis of idiopathic pulmonary fibrosis (IPF) is less clear. This likely reflects that fact that IPF acute exacerbations are defined clinically as "noninfectious," and little attention has been paid to the outcomes of patients with IPF with diagnosed infections. However, accumulating evidence suggests that infections (both bacterial and viral) may influence disease outcomes either as exacerbating agents or initiators of disease. Support for a viral role in disease initiation comes from studies demonstrating the presence of herpesviral DNA and epithelial cell stress in the lungs of asymptomatic relatives at risk for developing familial IPF. In addition, the number of studies that can associate viral (especially herpesviral) signatures in the lung with the development of IPF is steadily growing, and activated leukocyte signatures in patients with IPF provide further support for infectious processes driving IPF progression. Animal modeling has been used to better understand how a gamma herpesvirus infection can modulate the pathogenesis of lung fibrosis and has demonstrated that preceding infections appear to reprogram lung epithelial cells during latency to produce profibrotic factors, making the lung more susceptible to subsequent fibrotic insult, whereas exacerbations of existing fibrosis, or infections in susceptible hosts, involve active viral replication and are influenced by antiviral therapy. In addition, there is new evidence that bacterial burden in the lungs of patients with IPF may predict a poor prognosis.

Studying human respiratory disease in animals--role of induced and naturally occurring models

Respiratory disorders like asthma, emphysema, and pulmonary fibrosis affect millions of Americans and many more worldwide. Despite advancements in medical research that have led to improved understanding of the pathophysiology of these conditions and sometimes to new therapeutic interventions, these disorders are for the most part chronic and progressive; current interventions are not curative and do not halt disease progression. A major obstacle to further advancements relates to the absence of animal models that exactly resemble the human condition, which delays the elucidation of relevant mechanisms of action, the unveiling of biomarkers of disease progression, and identification of new targets for intervention in patients. There are currently many induced animal models of human respiratory disease available for study, and even though they mimic features of human disease, discoveries in these models have not always translated into safe and effective treatments in humans. A major obstacle relates to the genetic, anatomical, and functional variations amongst species, which represents the major challenge to overcome when searching for appropriate models of respiratory disease. Nevertheless, rodents, in particular mice, have become the most common species used for experimentation, due to their relatively low cost, size, and adequate understanding of murine genetics, among other advantages. Less well known is the fact that domestic animals also suffer from respiratory illnesses similar to those found in humans. Asthma, bronchitis, pneumonia, and pulmonary fibrosis are among the many disorders occurring naturally in dogs, cats, and horses, among other species. These models might better resemble the human condition and are emphasized here, but further investigations are needed to determine their relevance.

Advances in the treatment of idiopathic pulmonary fibrosis

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is a lung limited, progressive fibrotic disease with a poor prognosis. The cause is unknown, and currently there is no treatment that reverses the disease or stops progression. This combination of a poor prognosis and the absence of curative therapy has prompted a sustained investigative effort to identify beneficial treatments. Recently released trial results suggest progress.

AREAS COVERED

Although the mechanism of disease is poorly understood, a number of compounds that influence pathways thought to play a mechanistic role have been studied for use in IPF. This article discusses a number of these landmark trials.

EXPERT OPINION

From these studies we conclude that the future treatment of IPF will include expanding pharmacological options. Recent studies have identified two agents that appear to slow disease progression and may offer a window into pathogenesis and future drug targets.

Interstitial lung disease in rheumatoid arthritis: Current concepts in pathogenesis, diagnosis and therapeutics

Rheumatoid arthritis (RA) is the most common chronic autoimmune inflammatory joint disease. RA-associated interstitial lung disease (RA-ILD) is a major extra-articular complication and causes symptoms that lead to a deterioration in the quality of life, high utilization of health resources, and an increased risk of earlier mortality. Early in the course of RA-ILD, symptoms are highly variable, making the diagnosis difficult. Therefore, a rational diagnostic strategy that combines an adequate clinical assessment with the appropriate use of clinical tests, including pulmonary function tests and high-resolution computed tomography, should be used. In special cases, lung biopsy or bronchioalveolar lavage should be performed to achieve an early diagnosis. Several distinct histopathological subtypes of RA-ILD are currently recognized. These subtypes also have different clinical presentations, which vary in therapeutic response and prognosis. This article reviews current evidence about the epidemiology of RA-ILD and discusses the varying prevalence rates observed in different studies. Additionally, aspects of RA-ILD pathogenesis, including the role of cytokines and other molecules such as autoantibodies, as well as the evidence linking several drugs used to treat RA with lung damage will be discussed. Some aspects of the clinical characteristics of RA-ILD are noted, and diagnostic strategies are reviewed. Finally, this article analyzes current treatments for RA-ILD, including immunosuppressive therapies and biologic agents, as well as other therapeutic modalities. The prognosis of this severe complication of RA is discussed. Additionally, this paper examines updated evidence from studies identifying an association between drugs used for the treatment of RA and the development of ILD.

The association of exposure to hepatitis B and C viruses with lung function and respiratory disease: a population based study from the NHANES III database

BACKGROUND

Globally, 500 million people are chronically infected with Hepatitis B virus (HBV) and Hepatitis C virus (HCV). While these viruses are notorious for their detrimental effect on the liver they are also known to affect multiple organs in the body including the lungs.

AIM

To investigate if exposure to HBV and HCV is associated with lung function and respiratory diseases.

METHODS

Data from the Third National Health and Nutrition Examination Survey (NHANES III) was analysed using multiple linear regressions to investigate the association between exposure to HBV and HCV with the various measures of lung function, while multiple logistic regressions were used to evaluate the association with the respiratory diseases asthma and chronic obstructive pulmonary disease (COPD).

RESULTS

Exposure to HCV was significantly associated with an increase in Forced Expiratory Volume in 1 s, FEV1 (Coef: 97.94 ml, 95% CI: 38.87 to 157.01) and Full Vital Capacity, FVC (Coef: 90 ml, 95% CI: 14.50 to 166.24). Individuals who had been exposed to both HBV and HCV also had a significantly higher FEV1 (Coef: 145.82, CI: 60.68 to 230.94) and FVC (Coef: 195.09, CI: 78.91 to 311.26). There was also a significant association between exposure to HBV and asthma (OR: 1.28, 95% CI: 1.05 to 1.58). These associations were no longer significant after additionally adjusting for cocaine and marijuana use as well as poverty income ratio.

CONCLUSION

Our research implies that hepatotropic viruses may affect the respiratory system, but more work at a population level is needed to further explore these associations.

Gammaherpesviruses and Pulmonary Fibrosis

Progressive lung fibrosis in humans, typified by idiopathic pulmonary fibrosis (IPF), is a serious cause of morbidity and mortality in people. Similar diseases have been described in dogs, cats, and horses. The cause and pathogenesis of such diseases in all species is poorly understood. There is growing evidence in human medicine that IPF is a manifestation of abnormal wound repair in response to epithelial injury. Because viruses can contribute to epithelial injury, there is increasing interest in a possible role of viruses, particularly gammaherpesviruses, in the pathogenesis of pulmonary fibrosis. This review provides background information on progressive fibrosing lung disease in human and veterinary medicine and summarizes the evidence for an association between gammaherpesvirus infection and pulmonary fibrosis, especially Epstein-Barr virus in human pulmonary fibrosis, and equine herpesvirus 5 in equine multinodular pulmonary fibrosis. Data derived from experimental lung infection in mice with the gammaherpesvirus murine herpesvirus are presented, emphasizing the host and viral factors that may contribute to lung fibrosis. The experimental data are considered in the context of the pathogenesis of naturally occurring pulmonary fibrosis in humans and horses.

Diagnostic workup for diffuse parenchymal lung disease: schematic flowchart, literature review, and pitfalls

PURPOSE

The term diffuse parenchymal lung disease (DPLD) refers to a group of disorders affecting the lung parenchyma that can be categorized into those of known and those of unknown etiology. Early diagnosis is important since some forms of DPLD are characterized by a rapid progression to respiratory failure. Notwithstanding the fact that recently guidelines have been published, some issues concerning the practical evaluation of a patient with suspected DPLD remain unclear.

METHODS

In this article we propose a practical approach to the diagnosis and differentiation of DPLD. Moreover, a critical appraisal is provided based on the current literature and frequent pitfalls are highlighted.

CONCLUSION

we propose a practical workup, but in spite of increasing evidence concerning the diagnosis of DPLD, further studies will be needed to clarify several issues for efficient investigation of newly diagnosed patients with DPLD.

A novel screening method detects herpesviral DNA in the idiopathic pulmonary fibrosis lung

BACKGROUND

Herpesviruses could contribute to the lung epithelial injury that initiates profibrotic responses in idiopathic pulmonary fibrosis (IPF).

METHODS

We identified herpesviral DNA from IPF and control lung tissue using a multiplex PCR-and microarray-based method. Active herpesviral infection was detected by standard methods, and inflammatory cell subtypes were identified with specific antibodies. Patients that underwent lung transplantation were monitored for signs of herpesviral infection.

RESULTS

A total of 11/12 IPF samples were positive for Epstein-Barr virus (EBV) and 10/12 for human herpesvirus 6B (HHV-6B) DNA. Control lung samples (n = 10) were negative for EBV DNA, whereas three samples were positive for HHV-6B. EBV-encoded RNA (EBER) was identified in nine IPF samples and localized mainly to lymphocytic aggregates. HHV-6B antigens were detected in mononuclear cells in IPF lung tissue. CD20+ B lymphocytic aggregates that were surrounded by CD3+ T cells were abundant in IPF lungs. CD23+ cells (activated B cells, EBV-transformed lymphoblasts, and dendritic cells) were observed in the aggregates. IPF patients had no signs of increased herpesviral activation after lung transplantation.

CONCLUSIONS

Inflammatory cells are the main source of herpesviral DNA in the human IPF lung. Diagnostic tools should be actively used to elucidate whether herpesviral infection affects the pathogenesis, progression, and/or exacerbation of IPF.

Idiopathic pulmonary fibrosis-an epidemiological and pathological review

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease (ILD) affecting the pulmonary interstitium. Other forms of interstitial lung disease exist, and in some cases, an environmental etiology can be delineated. The diagnosis of IPF is typically established by high-resolution CT scan. IPF tends to have a worse prognosis than other forms of ILD. Familial cases of IPF also exist, suggesting a genetic predisposition; telomerase mutations have been observed to occur in familial IPF, which may also explain the increase in IPF with advancing age. Alveolar epithelial cells are believed to be the primary target of environmental agents that have been putatively associated with IPF. These agents may include toxins, viruses, or the autoantibodies found in collagen vascular diseases. The mechanism of disease is still unclear in IPF, but aberrations in fibroblast differentiation, activation, and proliferation may play a role. Epithelial-mesenchymal transition may also be an important factor in the pathogenesis, as it may lead to accumulation of fibroblasts in the lung and a disruption of normal tissue structure. Abnormalities in other components of the immune system, including T cells, B cells, and dendritic cells, as well as the development of ectopic lymphoid tissue, have also been observed to occur in IPF and may play a role in the stimulation of fibrosis that is a hallmark of the disease. It is becoming increasingly clear that the pathogenesis of IPF is indeed a complex and convoluted process that involves numerous cell types and humoral factors.

Viral infection and aging as cofactors for the development of pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a disease of unknown origin and progression that primarily affects older adults. Accumulating clinical and experimental evidence suggests that viral infections may play a role, either as agents that predispose the lung to fibrosis or exacerbate existing fibrosis. In particular, herpesviruses have been linked with IPF. This article summarizes the evidence for and against viral cofactors in IPF pathogenesis. In addition, we review mechanistic studies in animal models that highlight the fibrotic potential of viral infection, and explore the different mechanisms that might be responsible. We also review early evidence to suggest that the aged lung may be particularly susceptible to viral-induced fibrosis and make recommendations for future research directions.

An official ATS/ERS/JRS/ALAT statement: idiopathic pulmonary fibrosis: evidence-based guidelines for diagnosis and management

This document is an international evidence-based guideline on the diagnosis and management of idiopathic pulmonary fibrosis, and is a collaborative effort of the American Thoracic Society, the European Respiratory Society, the Japanese Respiratory Society, and the Latin American Thoracic Association. It represents the current state of knowledge regarding idiopathic pulmonary fibrosis (IPF), and contains sections on definition and epidemiology, risk factors, diagnosis, natural history, staging and prognosis, treatment, and monitoring disease course. For the diagnosis and treatment sections, pragmatic GRADE evidence-based methodology was applied in a question-based format. For each diagnosis and treatment question, the committee graded the quality of the evidence available (high, moderate, low, or very low), and made a recommendation (yes or no, strong or weak). Recommendations were based on majority vote. It is emphasized that clinicians must spend adequate time with patients to discuss patients' values and preferences and decide on the appropriate course of action.

Diffuse alveolar damage: a common phenomenon in progressive interstitial lung disorders

It has become obvious that several interstitial lung diseases, and even viral lung infections, can progress rapidly, and exhibit similar features in their lung morphology. The final histopathological feature, common in these lung disorders, is diffuse alveolar damage (DAD). The histopathology of DAD is considered to represent end stage phenomenon in acutely behaving interstitial pneumonias, such as acute interstitial pneumonia (AIP) and acute exacerbations of idiopathic pulmonary fibrosis (IPF). Acute worsening and DAD may occur also in patients with nonspecific interstitial pneumonias (NSIPs), and even in severe viral lung infections where there is DAD histopathology in the lung. A better understanding of the mechanisms underlying the DAD reaction is needed to clarify the treatment for these serious lung diseases. There is an urgent need for international efforts for studying DAD-associated lung diseases, since the prognosis of these patients has been and is still dismal.

Relationship between hepatitis C virus infection and pulmonary disorders: potential mechanisms of interaction

Recently, an increasing number of reports have suggested that chronic hepatitis C virus (HCV) infection is associated with pulmonary disorders. The effects of HCV on the lung may present as worsening of lung function and impaired responses to therapy in patients with chronic obstructive pulmonary disease and asthma. Moreover, chronic HCV infection may be associated with the pathogenesis of interstitial lung disease. It is believed that chronic HCV infection may contribute to the immune responses modulating the pathogenic processes underlying pulmonary disorders and, therefore, may lead to a wide spectrum of clinical presentations. Potential candidates for a role in these immune responses are the CD8(+) T lymphocytes and inflammatory cytokines. In this review, the effects of HCV on the lung and the potential mechanisms of interaction between chronic HCV infection and pulmonary disorders will be discussed.

Irreversible pulmonary hypertension associated with the use of interferon alpha for chronic hepatitis C

The interferons are a complex group of virally induced proteins produced by activated macrophages and lymphocytes, which have become the mainstay of therapy for hepatitis C infection. Sustained viral response (SVR) rates in noncirrhotic patients vary from 40-80% with interferon-based therapy. This, along with transplantation, has drastically changed the course of hepatitis C virus (HCV) infection over the last two decades. Numerous side effects associated with interferon therapy have been reported. These range from transient flu-like symptoms to serious effects such as cardiac arrhythmias, cardiomyopathy, renal and liver failure, polyneuropathy, and myelosuppression. Pulmonary side effects including pneumonitis, pulmonary fibrosis, and reversible pulmonary hypertension have been reported. Herein, we present four cases in which irreversible pulmonary hypertension was diagnosed after prolonged treatment with interferon alpha. In each case, other causes of pulmonary hypertension were systematically eliminated. Pulmonary artery hypertension, which may be irreversible, should be considered in patients being treated with interferon alpha who present with exertional dyspnea and do not have a readily identifiable inflammatory or thromboembolic cause.

The complex interrelationships between chronic lung and liver disease: a review

Lung complications may occur as a result of hepatic disease from any cause and represent a highly heterogeneous group of conditions. Early recognition of such complications may be challenging but is crucial both in forming a meaningful differential diagnosis and in avoiding severe sequelae and irreversible damage. Although a number of different pathogenetic mechanisms are likely to be involved, chronic liver dysfunction may cause pulmonary manifestations because of alterations in the production or clearance of circulating cytokines and other mediators. This is likely to be the case in hepatopulmonary syndrome, portopulmonary hypertension and primary biliary cirrhosis, although their pathogenesis remains largely speculative. Moreover, the severity of lung manifestations may or may not correspond to that of liver impairment, making disease outcome often unpredictable. Congenital and inflammatory disorders, however, may primarily affect both the liver and lung. Apart from specific diseases, a number of medications can also result in pulmonary and hepatic toxic effects. This is particularly important with cytokine therapy - used to treat viral hepatitis, among other diseases - because treatment consists of drug discontinuation, which, in turn, may cause reactivation or progression of the underlying disease that the drug was used for. This review summarizes salient diagnostic and therapeutic aspects of these often misdiagnosed conditions and highlights, based on the most recent literature, the need for early referral of such patients to centres with specific expertise in the field. In fact, a multidisciplinary approach involving pulmonologists, hepatologists and, in particularly severe cases, transplant surgeons has been already proven successful.

Strategies for treating idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common and most lethal diffuse fibrosing lung disease, with a mortality rate that exceeds that of many cancers. Recently, there have been many clinical trials of novel therapies for IPF. The results have mostly been disappointing, although two treatment approaches have shown some efficacy. This Review describes the difficulties of treating IPF and the approaches that have been tried or are in development, and concludes with suggestions of future therapeutic targets and strategies.

Determinants of initiation and progression of idiopathic pulmonary fibrosis

IPF is a devastating disease with few therapeutic options. The precise aetiology of IPF remains elusive. However, our understanding of the pathologic processes involved in the initiation and progression of this disease is improving. Data on the mechanisms underlying IPF have been generated from epidemiologic investigations as well as cellular and molecular studies of human tissues. Although no perfect animal model of human IPF exists, pre-clinical animal studies have helped define pathways which are likely important in human disease. Epithelial injury, fibroblast activation and repetitive cycles of injury and abnormal repair are almost certainly key events. Factors which have been associated with initiation and/or progression of IPF include viral infections, abnormal cytokine, chemokine and growth factor production, oxidant stress, autoimmunity, inhalational of toxicants and gastro-oesophageal reflux disease. Furthermore, recent evidence identifies a role for a variety of genetic and epigenetic abnormalities ranging from mutations in surfactant protein C to abnormalities in telomere length and telomerase activity. The challenge remains to identify additional inciting agents and key dysregulated pathways that lead to disease progression so that we can develop targeted therapies to treat or prevent this serious disease.