The Role of Microvascular Injury in the Evolution of Idiopathic Pulmonary Fibrosis

Association study of human leukocyte antigen variants and idiopathic pulmonary fibrosis

Introduction

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial pneumonia marked by progressive lung fibrosis and a poor prognosis. Recent studies have highlighted the potential role of infection in the pathogenesis of IPF, and a prior association of the HLA-DQB1 gene with idiopathic fibrotic interstitial pneumonia (including IPF) has been reported. Owing to the important role that the human leukocyte antigen (HLA) region plays in the immune response, here we evaluated if HLA genetic variation was associated specifically with IPF risk.

Methods

We performed a meta-analysis of associations of the HLA region with IPF risk in individuals of European ancestry from seven independent case-control studies of IPF (comprising 5159 cases and 27 459 controls, including a prior study of fibrotic interstitial pneumonia). Single nucleotide polymorphisms, classical HLA alleles and amino acids were analysed and signals meeting a region-wide association threshold of p<4.5×10-4 and a posterior probability of replication >90% were considered significant. We sought to replicate the previously reported HLA-DQB1 association in the subset of studies independent of the original report.

Results

The meta-analysis of all seven studies identified four significant independent single nucleotide polymorphisms associated with IPF risk. However, none met the posterior probability for replication criterion. The HLA-DQB1 association was not replicated in the independent IPF studies.

Conclusion

Variation in the HLA region was not consistently associated with risk in studies of IPF. However, this does not preclude the possibility that other genomic regions linked to the immune response may be involved in the aetiology of IPF.

Prognostic Value of Serum Biomarkers in Patients with Idiopathic Pulmonary Fibrosis in Relation to Disease Progression

BACKGROUND

The aim of this present study was to determine serum biomarker levels and their correlation with respiratory function and the clinical course of patients with idiopathic pulmonary fibrosis (IPF).

MATERIALS AND METHODS

This study included 72 IPF patients, according to the ATS/ERS criteria, in whom antifibrotic treatment was initiated. Blood samples were taken, and serum biomarkers, such as KL-6, SP-D, CCL18, CXCL13, VEGF-A, IL-8, IGFBP-1, IGFBP-2, IGFBP-7 and ICAM-1 were measured using ELISA methodology. Pulmonary function tests (FVC, TLC, DLCO-% pred) were determined at baseline and after 12 and 24 months and analyzed in correlation with the biomarkers.

RESULTS

The majority of patients (mean age 72 ± 6 years) were men (83%). The FVC and DLCO values at the 12-month follow-up were found to be statistically decreased in deceased patients (p < 0.05). The SP-D (p < 0.001) and the IGFBP-1 (p = 0.021) levels were found to be increased at the 1-year follow-up in deceased patients, and similarly, the SP-D (p = 0.005) and ICAM-1 (p = 0.043) levels at the 2-year follow-up. A chi-square test revealed that 70% of the category IV GAP index was found with cut-off elevated levels of a biomarker combination (KL-6, SP-D, VEGF-A) from the ROC curve analysis (p < 0.05).

CONCLUSION

This study provides evidence, for the first time in a Greek population, of the possibility of using a combination of KL-6, SP-D, and VEGF-A serum levels along with the GAP index.

Association study of human leukocyte antigen (HLA) variants and idiopathic pulmonary fibrosis

Introduction

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial pneumonia marked by progressive lung fibrosis and a poor prognosis. Recent studies have highlighted the potential role of infection in the pathogenesis of IPF and a prior association of the HLA-DQB1 gene with idiopathic fibrotic interstitial pneumonia (including IPF) has been reported. Due to the important role that the Human Leukocyte Antigen (HLA) region plays in the immune response, here we evaluated if HLA genetic variation was associated specifically with IPF risk.

Methods

We performed a meta-analysis of associations of the HLA region with IPF risk in individuals of European ancestry from seven independent case-control studies of IPF (comprising a total of 5,159 cases and 27,459 controls, including the prior study of fibrotic interstitial pneumonia). Single nucleotide polymorphisms, classical HLA alleles and amino acids were analysed and signals meeting a region-wide association threshold p<4.5×10-4 and a posterior probability of replication >90% were considered significant. We sought to replicate the previously reported HLA-DQB1 association in the subset of studies independent of the original report.

Results

The meta-analysis of all seven studies identified four significant independent single nucleotide polymorphisms associated with IPF risk. However, none met the posterior probability for replication criterion. The HLA-DQB1 association was not replicated in the independent IPF studies.

Conclusion

Variation in the HLA region was not consistently associated with risk in studies of IPF. However, this does not preclude the possibility that other genomic regions linked to the immune response may be involved in the aetiology of IPF.

Interstitial Lung Disease and Anti-Neutrophil Cytoplasmic Antibody–Associated Vasculitis

Interstitial lung disease is a common complication of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). It is seen most commonly in microscopic polyangiitis owing to the pathogenic effect of myeloperoxidase in the lung. Oxidative stress, neutrophil elastase release, and expression of inflammatory proteins by neutrophil extracellular traps result in fibroblast proliferation and differentiation and therefore fibrosis. Usually, interstitial pneumonia pattern fibrosis is common and associated with poor survival. Treatment for patients with AAV and interstitial lung disease lacks evidence, and those with vasculitis are treated with immunosuppression, whereas those with progressive fibrosis may well benefit from antifibrotic therapy.

The Role of Herpes Viruses in Pulmonary Fibrosis

Pulmonary fibrosis (PF) is a serious lung disease which can result from known genetic or environmental exposures but is more commonly idiopathic (IPF). In familial PF (FPF), the majority of identified causal genes play key roles in the maintenance of telomeres, the protective end structures of chromosomes. Recent evidence suggests that short telomeres may also be implicated causally in a significant proportion of idiopathic cases. The possible involvement of herpes viruses in PF disease incidence and progression has been examined for many years, with some studies showing strong, statistically significant associations and others reporting no involvement. Evidence is thus polarized and remains inconclusive. Here we review the reported involvement of herpes viruses in PF in both animals and humans and present a summary of the evidence to date. We also present several possible mechanisms of action of the different herpes viruses in PF pathogenesis, including potential contributions to telomere attrition and cellular senescence. Evidence for antiviral treatment in PF is very limited but suggests a potential benefit. Further work is required to definitely answer the question of whether herpes viruses impact PF disease onset and progression and to enable the possible use of targeted antiviral treatments to improve clinical outcomes.

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.

Changing Expression Profiles of Messenger RNA, MicroRNA, Long Non-coding RNA, and Circular RNA Reveal the Key Regulators and Interaction Networks of Competing Endogenous RNA in Pulmonary Fibrosis

Pulmonary fibrosis is a kind of interstitial lung disease with architectural remodeling of tissues and excessive matrix deposition. Apart from messenger RNA (mRNA), microRNA (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA) could also play important roles in the regulatory processes of occurrence and progression of pulmonary fibrosis. In the present study, the pulmonary fibrosis model was administered with bleomycin. Whole transcriptome sequencing analysis was applied to investigate the expression profiles of mRNAs, lncRNAs, circRNAs, and miRNAs. After comparing bleomycin-induced pulmonary fibrosis model lung samples and controls, 286 lncRNAs, 192 mRNAs, 605 circRNAs, and 32 miRNAs were found to be differentially expressed. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to investigate the potential functions of these differentially expressed (DE) mRNAs and non-coding RNAs (ncRNAs). The terms related to inflammatory response and tumor necrosis factor (TNF) signaling pathway were enriched, implying potential roles in regulatory process. In addition, two co-expression networks were also constructed to understand the internal regulating relationships of these mRNAs and ncRNAs. Our study provides a systematic perspective on the potential functions of these DE mRNAs and ncRNAs during PF process and could help pave the way for effective therapeutics for this devastating and complex disease.

HIP/PAP protects against bleomycin-induced lung injury and inflammation and subsequent fibrosis in mice

Hepatocarcinoma‐intestine‐pancreas/pancreatitis‐associated protein (HIP/PAP), a C‐type lectin, exerts anti‐oxidative, anti‐inflammatory, bactericidal, anti‐apoptotic, and mitogenic functions in several cell types and tissues. In this study, we explored the role of HIP/PAP in pulmonary fibrosis (PF). Expression of HIP/PAP and its murine counterpart, Reg3B, was markedly increased in fibrotic human and mouse lung tissues. Adenovirus‐mediated HIP/PAP expression markedly alleviated bleomycin (BLM)‐induced lung injury, inflammation, and fibrosis in mice. Adenovirus‐mediated HIP/PAP expression alleviated oxidative injury and lessened the decrease in pulmonary superoxide dismutase (SOD) activity in BLM‐treated mice, increased pulmonary SOD expression in normal mice, and HIP/PAP upregulated SOD expression in cultured human alveolar epithelial cells (A549) and human lung fibroblasts (HLF‐1). Moreover, in vitro experiments showed that HIP/PAP suppressed the growth of HLF‐1 and ameliorated the H₂O₂‐induced apoptosis of human alveolar epithelial cells (A549 and HPAEpiC) and human pulmonary microvascular endothelial cells (HPMVEC). In HLF‐1, A549, HPAEpiC, and HPMVEC cells, HIP/PAP did not affect the basal levels, but alleviated the TGF‐β1‐induced down‐regulation of the epithelial/endothelial markers E‐cadherin and vE‐cadherin and the over‐expression of mesenchymal markers, such as α‐SMA and vimentin. In conclusion, HIP/PAP was found to serve as a potent protective factor in lung injury, inflammation, and fibrosis by attenuating oxidative injury, promoting the regeneration of alveolar epithelial cells, and antagonizing the pro‐fibrotic actions of the TGF‐β1/Smad signaling pathway.

Multimodal noninvasive prediction of pulmonary hypertension in IPF

INTRODUCTION AND OBJECTIVE

Pulmonary hypertension (PH) complicating idiopathic pulmonary fibrosis (IPF) is challenging to diagnose given inaccuracy of transthoracic echocardiogram (TTE) measurements. However, it has significant prognostic implications and is therefore important to accurately identify.

METHODS

We conducted a cross-sectional study of patients with IPF who underwent RHC as part of their evaluation. A variety of commonly available noninvasive variables were evaluated for their ability to predict pulmonary arterial pressure in a linear regression model, including the traditionally used right ventricular systolic pressure (RVSP) estimated from TTE.

RESULTS

There were 105 eligible patients identified from January 2006 to July 2016. The average age was 62.7 ± 7.7 years, 35 had RHC proven PH and 43% ultimately underwent lung transplantation. A linear model including three terms: RVSP (ANOVA P < .01), the ratio of FVC/DLCO from PFTs (P = .05) and pulmonary artery to aorta diameter ratio from CT (P < .01) was found to predict the mean pulmonary artery pressure more reliably than RVSP alone (R² .39 vs .29, P < .05), with a lower rate of incorrect classification of PH status in these individuals (27.6 vs 35.2%, P = .05) and high negative predictive value (87.2%).

CONCLUSION

If used in conjunction with RVSP from TTE, parameters from PFTs and the CT scan more accurately predict the presence or absence of PH than any of the variables in isolation. Using these in concert may allow greater discrimination in deciding which patients to subject to diagnostic right heart catheterization.

Secondary pulmonary arterial hypertension: to treat or not to treat?

PURPOSE OF REVIEW

The purpose of this review is to review recent literature related to mechanisms and treatment options for 'secondary' (i.e., WHO Groups 3 and 5) pulmonary arterial hypertension (PAH).

RECENT FINDINGS

Published randomized controlled trials, in general, do not support the use of approved therapies for 'primary' (i.e., WHO Group 1) PAH patients in patients with Group 3 PAH because of the small numbers of patients and inconsistent benefit. Therefore, we currently recommend against the use of these medications for Group 3 PAH. Similarly, there is limited evidence supporting the use of Group 1 PAH medications in Group 5 patients. In most patients with Group 5 PAH, treatment should be directed to the underlying disease.

SUMMARY

The utility of PAH-specific therapy in WHO Group 3 PAH is unclear because of the small numbers of patients evaluated and inconsistent beneficial effects observed. There is limited evidence supporting the use of PAH medications in Group 5 patients, and they may be harmful in some cases.

Feixian Recipe inhibits pulmonary fibrosis by targeting pulmonary microvascular endothelial cells and VEGF/VEGFR2 signaling pathway

Objective: To investigate the regulatory mechanism of PMVECs and vascular endothelial growth factor VEGF/vascular endothelial growth factor receptor 2 (VEGFR2) signaling pathway in pulmonary fibrosis and the inhibitory effect of Feixian Recipe (FXR) in pulmonary fibrosis by targeting VEGF/VEGFR2 signal pathway.

Methods: In this study, pulmonary microvascular endothelial cells (PMVECs) were successfully isolated from rats with pulmonary fibrosis. Cells were divided into six groups: model group, prednisone group, losartan group and three different concentrated (100[Formula: see text]ug/mL, 60[Formula: see text]ug/mL, 20[Formula: see text]ug/mL) FXR groups. The adhesion rate, migration and closed blood vessels of each PMVECs group were detected. The mRNA expression of VEGF, VEGFR2, phosphoinositide 3-kinase (PI3K), mitogen-activated protein kinases 38 (P38 MAPK) and activin receptor-like kinase (ALK) were detected by SYBR Green I real-time fluorescence quantitative PCR.

Results: Compared with the model group, the adhesion rate, migration and angiogenesis of PMVECs were decreased in FXR groups ([Formula: see text]). Compared with prednisone and losartan groups, the mRNA expressions of VEGF, VEGFR2, PI3K and P38 MAPK were down-regulated significantly by FXR ([Formula: see text]).

Conclution: FXR can inhibit the migration, adhesion and angiogenesis of PMVECs in rats with pulmonary fibrosis by targeting VEGF/VEGFR2 signal pathway, and inhibit the progress of pulmonary fibrosis.

Exertional dyspnoea in interstitial lung diseases: the clinical utility of cardiopulmonary exercise testing

Interstitial lung diseases (ILDs) represent a heterogeneous group of pathologies characterised by alveolar and interstitial damage, pulmonary inflammation (usually associated with fibrosis), decreased lung function and impaired gas exchange, which can be attributed to either a known or an unknown aetiology. Dyspnoea is one of the most common and disabling symptoms in patients with ILD, significantly impacting quality of life. The mechanisms causing dyspnoea are complex and not yet fully understood. However, it is recognised that dyspnoea occurs when there is an imbalance between the central respiratory efferent drive and the response of the respiratory musculature. The respiratory derangement observed in ILD patients at rest is even more evident during exercise. Pathophysiological mechanisms responsible for exertional dyspnoea and reduced exercise tolerance include altered respiratory mechanics, impaired gas exchange, cardiovascular abnormalities and peripheral muscle dysfunction.

This review describes the respiratory physiology of ILD, both at rest and during exercise, and aims to provide comprehensive and updated evidence on the clinical utility of the cardiopulmonary exercise test in the assessment and management of these pathological entities. In addition, the role of exercise training and pulmonary rehabilitation programmes in the ILD population is addressed.

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.

Pulmonary Hypertension in Diffuse Parenchymal Lung Diseases

Pulmonary hypertension (PH) can be triggered by any number of disease processes that result in increased pulmonary vascular resistance. Although historically associated with idiopathic pulmonary arterial hypertension (PAH), most patients with PH do not have the idiopathic subtype, but rather PH associated with another underlying diagnosis, such as left heart or lung disease. The World Health Organization (WHO) classification of PH helps conceptualize the different categories based on presumed etiology. WHO group 3 is PH associated with lung disease. This review focuses on PH in diffuse parenchymal lung diseases (DPLDs), such as the idiopathic interstitial pneumonias and other more rare forms of DPLD. Although there are clear associations of PH with DPLD, the exact pathophysiologic mechanisms and full clinical significance remain uncertain. Treatment of PH related to DPLD remains investigational, but an area of great interest given the negative prognostic implications and the growing number of available pulmonary vasoactive agents.

Serum analysis of coagulation factors in IPF and NSIP

Recent literature and our previous proteomic findings prompted us to study the coagulation system in idiopathic pulmonary fibrosis (IPF), the pathogenesis of which remains unclear. The aim of this study was to compare coagulation factors in idiopathic pulmonary fibrosis and idiopathic nonspecific interstitial pneumonia (NSIP) patients and healthy controls. Thirty-three IPF patients (23 acute exacerbation and 10 stable IPF patients), 7 NSIP patients, and 44 controls were enrolled. Concentrations of D-dimer, homocysteine, functional protein C, protein C antigen, free and total protein S antigen and activity, fibrinogen and factor VIIIc were analyzed in serum of patients and controls. The lupus anticoagulant (LAC) test was also performed. Factor VIIIc levels were significantly higher in acute exacerbation IPF patients than controls (p = 0.0001) and in stable IPF patients than controls (p = 0.002). Factor VIIIc levels were higher and PT levels were lower in acute exacerbation IPF patients who died after exacerbation than in patients who survived (p = 0.04 and p = 0.003, respectively). D-dimer, fibrinogen, and homocysteine levels were also significantly higher in IPF patients than controls (p < 0.01). Protein C activity was increased in acute exacerbation IPF patients than controls (p = 0.005). The LAC test was positive in seven IPF patients and negative in controls. Procoagulant status was demonstrated in IPF patients (mainly in acute exacerbation/IPF) than controls and NSIP patients, probably due to endothelial activation and microvascular injury. These preliminary results are of interest because of their potential implications in the pathogenesis and treatment of this disease.

Increased platelet binding to circulating monocytes in idiopathic pulmonary fibrosis

PURPOSE

Idiopathic pulmonary fibrosis (IPF) is the most common idiopathic interstitial pneumonia and its prognosis is poor. Epidemiological evidence suggests an association of IPF with vascular disease and thrombotic tendency, which may be related to platelet activation.

METHODS

Platelet-monocyte adhesion in peripheral blood was examined by flow cytometry in patients with IPF (n = 19), interstitial lung disease (ILD) other than IPF (n = 9), and control subjects without pulmonary fibrosis (n = 14). Expression of platelet activation markers P-selectin (CD62P), PSGL-1 (CD162), and CD40 ligand (CD40L) on leukocytes and platelets were studied. Plasma concentrations of soluble P-selectin and CD40L were measured by ELISA.

RESULTS

Significantly elevated levels of platelet-monocyte binding were found in patients with IPF (35.6 ± 4.34 % [mean ± SEM]) compared with patients with non-IPF ILD (23.5 ± 3.68 %) and non-ILD control subjects (16.5 ± 2.26 %; P < 0.01). There was a trend towards increased divalent cation-independent platelet-monocyte binding in IPF (6.0 ± 0.77 % [mean ± SEM]) compared with non-IPF ILD (4.3 ± 1.38 %) and control subjects without ILD (3.1 ± 1.75 %; P = 0.058). There was no differential surface expression of platelet activation markers on subsets of leukocytes or platelets. Plasma concentrations of CD40L and soluble P-selectin did not differ between IPF and control subjects. Platelet-monocyte binding had no significant correlation with percent predicted TLco or FVC.

CONCLUSIONS

Platelet-monocyte binding is increased in IPF, suggesting increased platelet activation. This conjugation is predominantly calcium-dependent, but there may be more calcium-independent adhesion in IPF. These findings support further research into the role of platelet activation in IPF.

Thiol-redox antioxidants protect against lung vascular endothelial cytoskeletal alterations caused by pulmonary fibrosis inducer, bleomycin: comparison between classical thiol-protectant, N-acetyl-L-cysteine, and novel thiol antioxidant, N,N'-bis-2-mercaptoethyl isophthalamide

Lung vascular alterations and pulmonary hypertension associated with oxidative stress have been reported to be involved in idiopathic lung fibrosis (ILF). Therefore, here, we hypothesize that the widely used lung fibrosis inducer, bleomycin, would cause cytoskeletal rearrangement through thiol-redox alterations in the cultured lung vascular endothelial cell (EC) monolayers. We exposed the monolayers of primary bovine pulmonary artery ECs to bleomycin (10 µg) and studied the cytotoxicity, cytoskeletal rearrangements, and the macromolecule (fluorescein isothiocyanate-dextran, 70,000 mol. wt.) paracellular transport in the absence and presence of two thiol-redox protectants, the classic water-soluble N-acetyl-L-cysteine (NAC) and the novel hydrophobic N,N'-bis-2-mercaptoethyl isophthalamide (NBMI). Our results revealed that bleomycin induced cytotoxicity (lactate dehydrogenase leak), morphological alterations (rounding of cells and filipodia formation), and cytoskeletal rearrangement (actin stress fiber formation and alterations of tight junction proteins, ZO-1 and occludin) in a dose-dependent fashion. Furthermore, our study demonstrated the formation of reactive oxygen species, loss of thiols (glutathione, GSH), EC barrier dysfunction (decrease of transendothelial electrical resistance), and enhanced paracellular transport (leak) of macromolecules. The observed bleomycin-induced EC alterations were attenuated by both NAC and NBMI, revealing that the novel hydrophobic thiol-protectant, NBMI, was more effective at µM concentrations as compared to the water-soluble NAC that was effective at mM concentrations in offering protection against the bleomycin-induced EC alterations. Overall, the results of the current study suggested the central role of thiol-redox in vascular EC dysfunction associated with ILF.

Idiopathic pulmonary fibrosis is associated with circulating antiepithelial antibodies

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Susac syndrome: an organ-specific autoimmune endotheliopathy syndrome associated with anti-endothelial cell antibodies

Susac syndrome (SS) is the triad of encephalopathy, branch retinal artery occlusions (BRAOs), and hearing loss. Migraines may herald and accompany encephalopathy. Little is known about pathogenesis. Based on light microscopic findings in brain biopsy material analogous to anti-endothelial cell antibody (AECA)-mediated microvascular injury, we postulated that SS microangiopathy was attributable to AECAs. We examined serum samples from 11 patients with SS for AECAs; 9 were positive by indirect immunofluorescence and Western blot studies. A highly distinctive band on Western blots corresponding to a 50-kDa protein was observed in 8 positive SS samples; the other positive case exhibited specific reactivity with a protein band at 40 kDa. Of the 2 negative cases, 1 had been inactive since 1988; the other was an abortive variant characterized solely by BRAOs. There was enhanced surface binding of SS serum using live endothelial cell substrates compared with samples from healthy subjects. Additional serum samples from apparently healthy patients, 2 with atypical migraines, and patients with other forms of autoinflammatory disease did not show the distinctive band of immunoreactivity. SS is a distinct autoimmune endotheliopathy syndrome associated with AECAs; the antibody target seems specific in many cases and may be a disease biomarker. The exact role of AECAs in disease propagation remains unanswered.

Pulmonary hypertension secondary to interstitial lung disease

Interstitial lung diseases (ILDs) may be complicated by the development of pulmonary hypertension (PH), which is associated with worse functional impairment and a poorer prognosis. This article reviews the current state of knowledge on the prevalence, pathogenesis, diagnosis and prognosis of ILD-related PH. Whether the treatment of ILD-related PH changes clinical outcomes is currently unknown, but the current studies are summarized and the authors' perspective is offered.

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.

Interstitial lung disease associated with the idiopathic inflammatory myopathies: what progress has been made in the past 35 years?

Interstitial lung disease is commonly associated with the autoimmune inflammatory myopathies dermatomyositis and polymyositis and accounts for significant morbidity and mortality in these conditions. In the 35 years since the association between inflammatory myopathy and interstitial lung disease was initially described, there has been progress in diagnosing and treating this dis-order. Nevertheless, there remains much about pathogenesis and therapeutics to be learned. This review examines the changes in the understanding of this complex condition, highlighting recent advances and areas deserving of further study.

Pulmonary fibrosis inducer, bleomycin, causes redox-sensitive activation of phospholipase D and cytotoxicity through formation of bioactive lipid signal mediator, phosphatidic acid, in lung microvascular endothelial cells

The mechanisms of lung microvascular complications and pulmonary hypertension known to be associated with idiopathic pulmonary fibrosis (IPF), a debilitating lung disease, are not known. Therefore, we investigated whether bleomycin, the widely used experimental IPF inducer, would be capable of activating phospholipase D (PLD) and generating the bioactive lipid signal-mediator phosphatidic acid (PA) in our established bovine lung microvascular endothelial cell (BLMVEC) model. Our results revealed that bleomycin induced the activation of PLD and generation of PA in a dose-dependent (5, 10, and 100 µg) and time-dependent (2-12 hours) fashion that were significantly attenuated by the PLD-specific inhibitor, 5-fluoro-2-indolyl des-chlorohalopemide (FIPI). PLD activation and PA generation induced by bleomycin (5 µg) were significantly attenuated by the thiol protectant (N-acetyl-L-cysteine), antioxidants, and iron chelators suggesting the role of reactive oxygen species (ROS), lipid peroxidation, and iron therein. Furthermore, our study demonstrated the formation of ROS and loss of glutathione (GSH) in cells following bleomycin treatment, confirming oxidative stress as a key player in the bleomycin-induced PLD activation and PA generation in ECs. More noticeably, PLD activation and PA generation were observed to happen upstream of bleomycin-induced cytotoxicity in BLMVECs, which was protected by FIPI. This was also supported by our current findings that exposure of cells to exogenous PA led to internalization of PA and cytotoxicity in BLMVECs. For the first time, this study revealed novel mechanism of the bleomycin-induced redox-sensitive activation of PLD that led to the generation of PA, which was capable of inducing lung EC cytotoxicity, thus suggesting possible bioactive lipid-signaling mechanism/mechanisms of microvascular disorders encountered in IPF.

The pathogenesis of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease with an appalling prognosis. The failure of anti-inflammatory therapies coupled with the observation that deranged epithelium overlies proliferative myofibroblasts to form the fibroblastic focus has lead to the emerging concept that IPF is a disease of deregulated epithelial-mesenchymal crosstalk. IPF is triggered by an as yet unidentified alveolar injury that leads to activation of transforming growth factor-β (TGF-β) and alveolar basement membrane disruption. In the presence of persisting injurious pathways, or disrupted repair pathways, activated TGF-β can lead to enhanced epithelial apoptosis and epithelial-to-mesenchymal transition (EMT) as well as fibroblast, and fibrocyte, transformation into myofibroblasts which are resistant to apoptosis. The resulting deposition of excess disrupted matrix by these myofibroblasts leads to the development of IPF.

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.

Comorbidities of advanced lung disease

Lung disease in advanced stages is often accompanied by multiple comorbidities. Often, these processes lead to significant morbidity and occasionally mortality. Symptoms of pulmonary comorbidities, including pulmonary embolus, pulmonary hypertension, sleep-disordered breathing, and lung malignancy, may be intertwined with symptoms of advancing lung disease. However, the occurrence of extrapulmonary processes, including depression, diabetes mellitus, osteoporosis, and gastroesophageal reflux disease, may be subtle. Clinicians caring for advanced lung disease should be aware of the many comorbid processes that may accompany advancing lung disease.

Treatment of idiopathic interstitial pneumonias

The idiopathic interstitial pneumonias can be grouped, for treatment purposes, into primary inflammatory disorders, fibrotic nonspecific interstitial pneumonia (in which inflammation is thought to precede and progress to fibrosis) as well as the most common of the idiopathic interstitial pneumonia subgroups, idiopathic pulmonary fibrosis. Over the past decade, there have been several paradigm shifts in the understanding of idiopathic interstitial pneumonias and their treatment. In particular, we highlight changes in the use of prognostic markers, clinical trial end points and the understanding of pathogenesis of idiopathic pulmonary fibrosis. We outline a practical approach to the treatment of these three patient groups.

[Various clinical symptoms in human parvovirus B19 infection]

Human parvovirus B19 infection causes erythema infectiosum in child, aplastic crisis in patients with chronic hemolytic anemia, chronic pure red cell aplasia in immunocompromised patients and hydrops fetalis. Human parvovirus B19 causes arthritis and acute glomerulonephritis due to immunological mechanism. Other disorders, rheumatoid arthritis, vasculitis and thrombotic microangiopathy, are linked in human parvovirus B19 infection. Parvovirus B19 infection causes choronic rheumatoid-like arthropathy. Autoantibody and low complement were seen in acute human parvovirus infection, and parvovirus B19 infection present clinically lupus like tableau.

Viruses as co-factors for the initiation or exacerbation of lung fibrosis

Idiopathic pulmonary fibrosis (IPF) remains exactly that. The disease originates from an unknown cause, and little is known about the mechanisms of pathogenesis. While the disease is likely multi-factorial, evidence is accumulating to implicate viruses as co-factors (either as initiating or exacerbating agents) of fibrotic lung disease. This review summarizes the available clinical and experimental observations that form the basis for the hypothesis that viral infections may augment fibrotic responses. We review the data suggesting a link between hepatitis C virus, adenovirus, human cytomegalovirus and, in particular, the Epstein-Barr gammaherpesvirus, in IPF. In addition, we highlight the recent associations made between gammaherpesvirus infection and lung fibrosis in horses and discuss the various murine models that have been used to investigate the contribution of gammaherpesviruses to fibrotic progression. We review the work demonstrating that gammaherpesvirus infection of Th2-biased mice leads to multi-organ fibrosis and highlight studies showing that gammaherpesviral infections of mice either pre- or post-fibrotic challenge can augment the development of fibrosis. Finally, we discuss potential mechanisms whereby viral infections may amplify the development of fibrosis. While none of these studies prove causality, we believe the evidence suggests that viral infections should be considered as potential initiators or exacerbating agents in at least some cases of IPF and thereby justify further study.

Inhibitor of differentiation 1 promotes endothelial survival in a bleomycin model of lung injury in mice

The Id family of genes encodes negative regulators of basic helix-loop-helix transcription factors and has been implicated in diverse cellular processes such as proliferation, apoptosis, differentiation, and migration. However, the specific role of Id1 in lung injury has not been investigated. Bleomycin has been widely used to generate animal models of acute lung injury and fibrogenesis. In this study we found that, on bleomycin challenge, Id1 expression was significantly up-regulated in the lungs, predominantly in endothelial cells, as revealed by double immunolabeling and quantitative flow cytometric analysis. Mice with Id1 loss-of-function (Id1(-/-)) displayed increased vascular permeability and endothelial apoptosis in the lungs after bleomycin-induced injury. Cultured Id1(-/-) lung microvascular endothelial cells also showed decreased survival when exposed to bleomycin. We detected a decrease in the level of Bcl-2, a primary anti-apoptotic protein, in Id1(-/-) endothelial cells, suggesting that down-regulated Bcl-2 may promote endothelial apoptosis in the lung. Therefore, we propose that Id1 plays a crucial role in promoting endothelial survival in the adult lung on injury. In addition, bleomycin-exposed Id1(-/-) mice showed increased lung collagen accumulation and fibrogenesis, suggesting that Id1 up-regulation in the lung may play a critical role in lung homeostasis.

Susac's syndrome: 1975–2005 microangiopathy/autoimmune endotheliopathy

Susac's syndrome (SS) consists of the clinical triad of encephalopathy, branch retinal artery occlusions (BRAO) and hearing loss. It is due to a microangiopathy affecting the precapillary arterioles of the brain, retina, and inner ear (cochlea and semicircular canals). Women are more commonly affected than men (3:1); the age of onset ranges from 9 to 58 years; but young women between the ages of 20 and 40 are most vulnerable. The encephalopathy is almost always accompanied by headache which may be the presenting feature. Multifocal neurological signs and symptoms, psychiatric disturbances, cognitive changes, memory loss, and confusion may rapidly progress to dementia. The MRI shows a distinctive white matter disturbance that always affects the corpus callosum. The central callosal fibers are particularly vulnerable and central callosal holes develop as the active lesions resolve. Linear defects (spokes) and rather large round lesions (snowballs) sometime dominate the MRI findings, which include cortical, deep gray (70%) and leptomeningeal involvement (33%). Frequently, the lesions enhance and may be evident on diffusion weighted imaging (DWI). The BRAO are best evaluated with fluorescein angiography, which may show the pathognomonic multifocal fluorescence. Gass plaques are frequently present and reflect endothelial damage. Brain biopsy shows microinfarction to be the basic pathology, but more recent pathological studies have shown endothelial changes that are typical for an antiendothelial cell injury syndrome. Elevated levels of Factor VIII and von Willebrand Factor Antigen reflect the endothelial perturbation. Despite extensive evaluations, a procoagulant state has never been demonstrated. SS is an autoimmune endotheliopathy that requires treatment with immunosuppressants: steroids, cyclophosphamide, and intravenous immunoglobulin, usually in combination. Aspirin is a useful adjunct.

Microscopic polyangiitis presenting as a “pulmonary-muscle” syndrome: Is subclinical alveolar hemorrhage the mechanism of pulmonary fibrosis?

Microscopic polyangiitis (MPA) may present with a syndrome that resembles idiopathic pulmonary fibrosis (IPF). We describe an MPA patient with the clinical presentation of a "pulmonary-muscle" syndrome in which interstitial lung disease antedated the onset of myopathy. Identification of vasculitis on muscle biopsy was instrumental in recognizing clinical, radiographic, and histopathologic features that were more characteristic of MPA than of IPF. Institution of glucocorticoid and cyclophosphamide therapy led to the induction of a complete remission. The histologic findings in this case implicate subclinical episodes of alveolar hemorrhage as the mechanism of interstitial lung disease in MPA.

Autoimmune-Like Pulmonary Disease in Association With Parvovirus B19

Parvovirus B19, the agent responsible for fifth disease, has been emerging as a significant pathogenetic factor in various acute vasculitic syndromes such as Wegener's granulomatosis, Henoch-Schönlein purpura, and Kawasaki disease. It has also been implicated in more chronic vasculopathic syndromes, specifically in the context of scleroderma and dermatomyositis. The basis of this association is likely multifactorial; implicated mechanisms include the virus's affinity for endothelium, resulting in a state of neoantigenicity through varied mechanisms as well as the induction of tumor necrosis factor alpha, a factor involved in the propagation of ANCA-positive vasculitic syndromes. The authors present a series of 12 patients with interstitial lung disease including idiopathic pulmonary fibrosis, scleroderma-associated pulmonary fibrosis, lymphocytic interstitial pneumonitis, and septal capillaritis. In all cases there was evidence of chronic parvovirus B19 infection based on serologic assessment and the isolation of B19 DNA on lung samples in all patients. Furthermore, in two cases there was in situ localization of B19 RNA and tumor necrosis factor alpha to endothelium and stromal cells. On pathologic examination, there were varying degrees of both septal fibrosis and inflammation along with evidence of septal capillary injury. In those cases categorized as representing either scleroderma or idiopathic pulmonary fibrosis, the immunofluorescent studies showed evidence of anti-endothelial cell antibody formation. The ANCA-associated syndromes were, as expected, negative by fluorescent analysis. Significantly elevated factor VIII levels, a standard serologic index of endothelial cell injury, were seen in four of the six patients tested. The antiphospholipid profile revealed antiphospholipids in 7 of the 11 patients tested. This report highlights a possible causal role for parvovirus B19 in the pathogenesis of select pulmonary disorders.

Pathologic correlates of bronchiolitis obliterans syndrome in pulmonary retransplant recipients

RATIONALE

The main hindrance to long-term success of lung transplantation is bronchiolitis obliterans syndrome (BOS), generally thought to be a manifestation of chronic allograft rejection. BOS is associated histologically with epithelial injury, bronchocentric mononuclear inflammation, and fibrosis of small airways known as bronchiolitis obliterans (BO). Few studies have directly compared clinical, radiographic, and histologic findings of BOS and BO, particularly in the era of improved immunosuppression and infection prophylaxis. Patients undergoing pulmonary retransplantation for BOS provide a unique opportunity to investigate these relationships.

METHODS

All patients who underwent pulmonary retransplantation for BOS from 1992 to 2004 at Duke University Medical Center were reviewed. Pathology findings in explanted lung allografts were compared with clinical, radiographic, and transbronchial biopsy data.

RESULTS

Over the 12-year study period, 12 patients underwent pulmonary retransplantation for BOS. The median time to BOS was 517 days (intraquartile range, 396 to 819.8 days). BOS scores prior to retransplantation were 2 in 2 patients and 3 in 10 patients. We developed a semiquantitative scoring system for epithelial, inflammatory, and fibrotic changes in affected airways to permit better comparison between BO and BOS. Somewhat surprisingly, only 50% (6 of 12 patients) had severe fibrotic changes, although all had some degree of epithelial injury, fibrosis, or inflammation centered around the bronchi and bronchioles. Furthermore, pathology findings other than BO were present in most explanted allografts and included cholesterol clefts (n = 4), focal invasive aspergillosis (n = 1), interstitial fibrosis (n = 2), and chronic vascular rejection (n = 1).

CONCLUSIONS

In this series of patients with advanced BOS undergoing retransplantation, at least some degree of BO was present in all explanted allografts. However, the degree of epithelial changes, fibrosis, and inflammation present among affected bronchi varied considerably. Furthermore, a wide range of pathologic processes of potential clinical significance were evident in half of the patients. We conclude that significant histologic heterogeneity exists among patients undergoing retransplantation for BOS, potentially contributing to the variability of patient responses to treatment.

Idiopathic Pulmonary Fibrosis Related to Endothelial Injury and Antiendothelial Cell Antibodies

Mechanisms underlying idiopathic pulmonary fibrosis are not well understood. This paper presents data supporting the hypothesis that microvascular endothelial cell injury and antiendothelial cell antibodies play roles in human idiopathic pulmonary fibrosis. Serologic and pathologic features of 40 patients diagnosed with idiopathic pulmonary fibrosis were evaluated. All patients had open lung biopsies indicating either usual or nonspecific interstitial pneumonitis. All biopsies had morphologic evidence of microvascular injury to the endothelium, and direct immunofluorescence testing revealed variable deposition of IgG, IgM, or IgA within septal microvasculature suggestive of humorally mediated microvascular injury. Ultrastructural studies revealed changes of endothelial cell injury and necrosis and evidence of repetitive episodes of microvascular injury characterized by basement membrane zone collagen deposition and lamellation. Serum samples demonstrated reactivity to multiple endothelial cell antigenic epitopes, and indirect immunofluorescent testing demonstrated a prominent pattern of fluorescence in pulmonary endothelial cell preparations. Serum samples were positive in 37/40 patients for antiphospholipid antibodies with one fourth having positive lupus anticoagulant tests accompanied by thrombotic episodes. In patients with idiopathic pulmonary fibrosis, Factor VIII levels and C-reactive protein levels were also elevated, supporting the presence of endothelial cell injury and inflammation. These data underscore a potential role for immune-based microvascular injury in the evolution of usual or nonspecific interstitial pneumonitis and indicate that those patients have evidence of microvascular injury and endothelial cell necrosis. The high prevalence of antiphospholipid antibodies in these patients may lead to an inherent thrombophilic tendency.

Human cytomegalovirus pp65 lower matrix protein: a humoral immunogen for systemic lupus erythematosus patients and autoantibody accelerator for NZB/W F1 mice

Both the infection of human cytomegalovirus (HCMV) and the immunization of its recombinant glycoprotein (gB) in mice have been known to induce autoimmunity, resulting in symptoms similar to those of human systemic lupus erythematosus (SLE). Research has also found that the murine cytomegalovirus (MCMV)-specific monoclonal antibody (mAb) is able to react with a human U1-70K-like autoantigen. To investigate HCMV involvement in autoimmunity, we analysed the humoral responses to HCMV by autoimmune patients and normal adults. Our studies show unambiguously that sera from SLE patients exhibited an elevated IgG titre to HCMV when compared with those observed in controls and other connective tissue disease (CTD) patients (P < 0.001). The IgM titres to HCMV and IgG to HBV were evaluated, and no significant differences were noted among all testing groups. In addition to initiating T cell activity, as reported by many investigators, we found that the HCMV pp65 antigen (also known as lower matrix protein) was able to induce humoral responses in SLE patients. Immunoblot assays showed that 82.56% of sera from SLE patients reacted with the HCMV pp65 antigen, but only 11.11%, 23.53% and 31.17% of patients from normal control, rheumatoid arthritis (RA) and CTD patients, respectively, reacted to it. Unlike HCMV pp65, HCMV pp150 induced B cell activity in most collected sera (92.22%-98.04%). Finally, female NZB/W F1 mice immunized with plasmids encoding HCMV pp65 open reading frame (pcDNApp65) developed an early onset of autoantibody activity and more severe glomerulonephritis. Thus, we conclude that the HCMV pp65 antigen triggers humoral immunity in SLE patients and autoimmune-prone mice and that it could very well exacerbate the autoimmune responses in susceptible animals.

Lung infection with gamma-herpesvirus induces progressive pulmonary fibrosis in Th2-biased mice

Idiopathic pulmonary fibrosis (IPF) is a progressive, fibrotic lung disease of unknown etiology. A viral pathogenesis in IPF has been suggested since >95% of IPF patients have evidence of chronic pulmonary infection with one or more herpesviruses. To determine whether pulmonary infection with herpesvirus can cause lung fibrosis, we infected mice with the murine gamma-herpesvirus 68 (MHV68). Because IPF patients have a T helper type 2 (Th2) pulmonary phenotype, we used IFN-gammaR-/-, a strain of mice biased to develop Th2 responses. Chronic MHV68 infection of IFN-gammaR-/- mice resulted in progressive deposition of interstitial collagen as shown by light and electron microscopy. A significant decrease in tidal volume paralleled the collagen deposition. Five features typically seen in IPF, increased transforming growth factor-beta expression, myofibroblast transformation, production of Th2 cytokines, hyperplasia of type II cells, and increased expression of matrix metalloproteinase-7, were also present in chronically infected IFN-gammaR-/- mice. There also was altered synthesis of surfactant proteins, which is seen in some patients with familial IPF. MHV68 viral protein was found in type II alveolar epithelial cells, especially in lung areas with extensive alveolar remodeling. In summary, chronic herpesvirus pulmonary infection in IFN-gammaR-/- mice causes progressive pulmonary fibrosis and many of the pathological features seen in IPF.

Anticoagulant Therapy for Idiopathic Pulmonary Fibrosis

STUDY OBJECTIVE

To evaluate the effect of anticoagulant therapy on the survival of patients with idiopathic pulmonary fibrosis (IPF).

DESIGN

Prospective study.

SETTING

Five hospitals located in the Miyagi prefecture in Japan, including a university hospital, a Red Cross hospital, two public general hospitals, and a municipal hospital.

PATIENTS

Fifty-six patients with IPF (mean age, 69.4 years; range, 47 to 89) admitted to the hospitals from April 2001 to April 2004.

INTERVENTIONS

Patients were assigned to receive prednisolone alone or prednisolone plus anticoagulant therapy. The anticoagulants included oral warfarin in an outpatient setting and low-molecular-weight heparin for rehospitalized patients with severely progressive respiratory failure.

MEASUREMENTS AND RESULTS

There was no difference in baseline characteristics, including age, gender, clinical condition, pulmonary function, and plasma d-dimer level between the non-anticoagulant group and the anticoagulant group. The overall survival and hospitalization-free periods were assessed. There was a significant difference between survival curves of the non-anticoagulant group and the anticoagulant group, with a 2.9 hazard ratio (p = 0.04, Cox regression model). There was no significant difference in the probability of a hospitalization-free period between groups. The major cause of clinical deterioration was acute exacerbation during follow-up in the present study. Therefore, the mortality and plasma d-dimer levels in patients with an acute exacerbation were also assessed. The mortality associated with acute exacerbations of IPF in the anticoagulant group was significantly reduced compared to that in the non-anticoagulant group (18% vs 71%, respectively; p = 0.008, Fisher Exact Test). Furthermore, the plasma d-dimer levels in patients who died were significantly higher than those in survivors during acute exacerbation of IPF (3.3 +/- 2.3 microg/mL vs 0.9 +/- 0.7 microg/mL, p < 0.0001). Histologic analysis performed in three patients who died due to an exacerbation of IPF in the non-anticoagulant group demonstrated the features of usual interstitial pneumonia and acute lung injury.

CONCLUSIONS

Our data suggested that plasma d-dimer levels are associated with mortality in patients with an acute exacerbation of IPF, and that anticoagulant therapy has a beneficial effect on survival in patients with IPF.

Lung transplantation and interstitial lung disease

PURPOSE OF REVIEW

Interstitial lung disease includes a heterogeneous group of disorders that leads to respiratory insufficiency and death in a significant number of patients. Lung transplantation is a therapeutic option in select candidates.

RECENT FINDINGS

The indications, transplant procedure options, and outcomes continue to evolve. Various recipient comorbidities influence the choice of procedure in patients with interstitial lung disease. Single lung transplants are used as the procedure of choice and bilateral transplants are reserved for patients with suppurative lung disease and patients with pulmonary hypertension. Issues unique to patients with interstitial lung disease affect the morbidity, mortality and recurrence of the disease.

SUMMARY

Lung transplantation is an effective therapy for respiratory failure in interstitial lung disease with survival following transplant being similar to that achieved in transplant recipients with other diseases.

Cytomegalovirus-Associated Pulmonary Septal Capillary Injury Sine Inclusion Body Change

The authors describe four patients with symptomatic lung disease morphologically representing a septal capillary injury syndrome temporally associated with serologic and culture evidence of active cytomegalovirus (CMV) infection but without classic cytopathic changes. The authors conducted a thorough review of clinical data, microscopic examination, and in situ hybridization to detect CMV mRNA encoding immediate early protein. The assay detects transcripts that encode early and immediate early proteins. In two cases additional tissue was available for direct immunofluorescent studies. The disease process in each of the patients was morphologically indistinguishable from the pattern of organ injury associated with autoimmune diseases including a small vessel microvascular injury syndrome involving skin and lung and immune complex- mediated glomerulonephritis. Cytopenias were seen in all cases, most commonly thrombocytopenia. All treated patients demonstrated improvement on combined ganciclovir and low-dose steroid therapy. CMV infection may be of pathogenetic importance in some cases of alveolar hemorrhage, especially when accompanied by peripheral blood cytopenia in otherwise healthy patients and if clinical worsening occurs in the setting of a traditional immunosuppressive regimen typically used to treat vasculitis.

Variability of interalveolar septal remodeling after bleomycin treatment in mice

Although bleomycin-induced cellular injury in the lung parenchyma is followed by the development of patchy fibrosis, the authors hypothesized that remodeling of the interalveolar septum (IAS) following bleomycin is a diffuse process not limited to the formation of discrete fibrotic areas. To determine the spectrum of changes in the IAS induced by bleomycin treatment, lungs were harvested from mice at 1, 2, 3, and 4 weeks following intratracheal administration of 0.04, 0.06, or 0.08 units of bleomycin. Light microscopy with quantitative morphometric techniques and electron microscopy were used to evaluate the IAS alterations. At 4 weeks after treatment, there was evidence of diffuse IAS remodeling. By morphological analysis, two types of structural remodeling of the IAS were observed. One type showed thickening with extracellular matrix deposition and hyperplasia of lining epithelial cells. The other type showed localized thinning of the interstitium with capillary loss and reduction in number and in size of epithelial cells. The authors have defined these variants as septal thickening and septal atrophy, respectively. The findings indicate that studies investigating the pathogenesis of lung fibrosis should focus on septal remodeling as well as analysis of fibrotic foci and measurement of collagen content.