Raised plasma concentrations of alpha-defensins in patients with idiopathic pulmonary fibrosis

HSP47: A Therapeutic Target in Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease characterized by a progressive decline in lung function and poor prognosis. The deposition of the extracellular matrix (ECM) by myofibroblasts contributes to the stiffening of lung tissue and impaired oxygen exchange in IPF. Type I collagen is the major ECM component and predominant collagen protein deposited in chronic fibrosis, suggesting that type I collagen could be a target of drugs for fibrosis treatment. Heat shock protein 47 (HSP47), encoded by the serpin peptidase inhibitor clade H, member 1 gene, is a stress-inducible collagen-binding protein. It is an endoplasmic reticulum-resident molecular chaperone essential for the correct folding of procollagen. HSP47 expression is increased in cellular and animal models of pulmonary fibrosis and correlates with pathological manifestations in human interstitial lung diseases. Various factors affect HSP47 expression directly or indirectly in pulmonary fibrosis models. Overall, understanding the relationship between HSP47 expression and pulmonary fibrosis may contribute to the development of novel therapeutic strategies.

Potential biomarkers for diagnosis and disease evaluation of idiopathic pulmonary fibrosis

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease characterized by progressive lung fibrogenesis and histological features of usual interstitial pneumonia. IPF has a poor prognosis and presents a spectrum of disease courses ranging from slow evolving disease to rapid deterioration; thus, a differential diagnosis remains challenging. Several biomarkers have been identified to achieve a differential diagnosis; however, comprehensive reviews are lacking. This review summarizes over 100 biomarkers which can be divided into six categories according to their functions: differentially expressed biomarkers in the IPF compared to healthy controls; biomarkers distinguishing IPF from other types of interstitial lung disease; biomarkers differentiating acute exacerbation of IPF from stable disease; biomarkers predicting disease progression; biomarkers related to disease severity; and biomarkers related to treatment. Specimen used for the diagnosis of IPF included serum, bronchoalveolar lavage fluid, lung tissue, and sputum. IPF-specific biomarkers are of great clinical value for the differential diagnosis of IPF. Currently, the physiological measurements used to evaluate the occurrence of acute exacerbation, disease progression, and disease severity have limitations. Combining physiological measurements with biomarkers may increase the accuracy and sensitivity of diagnosis and disease evaluation of IPF. Most biomarkers described in this review are not routinely used in clinical practice. Future large-scale multicenter studies are required to design and validate suitable biomarker panels that have diagnostic utility for IPF.

The role of precision medicine in interstitial lung disease

The management of interstitial lung disease (ILD) may benefit from a conceptual shift. Increased understanding of this complex and heterogeneous group of disorders over the past 20 years has highlighted the need for individualised treatment strategies that encompass diagnostic classification and disease behaviour. Biomarker-based approaches to precision medicine hold the greatest promise. Robust, large-scale biomarker-based technologies supporting ILD diagnosis have been developed, and future applications relating to staging, prognosis and assessment of treatment response are emerging. Artificial intelligence may redefine our ability to base prognostic evaluation on both diagnosis and underlying disease processes, sharpening individualised treatment algorithms to a level not previously achieved. Compared with therapeutic areas such as oncology, precision medicine in ILD is still in its infancy. However, the heterogeneous nature of ILD suggests that many relevant molecular, environmental and behavioural targets may serve as useful biomarkers if we are willing to invest in their identification and validation.

Significance of nuclear LOXL2 inhibition in fibroblasts and myofibroblasts in the fibrotic process of acute respiratory distress syndrome

Fibrotic scarring is an important prognostic factor of acute respiratory distress syndrome (ARDS). There are currently no antifibrotic drugs or other therapeutic agents for ARDS. Lysyl oxidase-like 2 (LOXL2), an amine oxidase, contributes to fibrotic scarring by facilitating collagen cross-linking. Recent clinical trials revealed that a monoclonal inhibitory antibody against LOXL2 failed to show benefit over placebo in patients with fibrotic disorders involving the lungs. These clinical results raise the possibility that targeting the extracellular enzymic activity of LOXL2 is not in itself sufficient to prevent fibrotic scarring. We investigated the role of LOXL2 in the pathogenesis of ARDS in vivo, in vitro, and in samples from patients with ARDS. After lung injury, LOXL2 was unevenly expressed in the nuclei of lung fibroblasts and myofibroblasts in the fibrotic phase. Nuclear LOXL2 expression was upregulated in lung fibroblasts after transforming growth factor-beta1 (TGF-β1)-treatment. LOXL2 silencing abrogated the TGF-β1-induced expression of a myofibrogenic-progenitor marker, the appearance of proto-myofibroblasts, and the evolution of differentiated myofibroblasts in lung fibroblasts. Nuclear upregulation of Snail was evident in myofibroblasts during the fibrotic phase after lung injury. We detected high levels of LOXL2 protein in the lungs of ARDS patients, specifically during the proliferative and fibrotic phases. Our results highlight nuclear LOXL2 in fibroblasts as a primary causative driver of cell-fate decision toward myofibroblasts and of the progression of fibrotic scarring. A nuclear-LOXL2-targeted agent could be a promising therapeutic strategy against fibrotic disorders including ARDS.

PAD4 Deficiency Improves Bleomycin-induced Neutrophil Extracellular Traps and Fibrosis in Mouse Lung

Excessive release of neutrophil extracellular traps (NETs) has been implicated in several organ fibrosis, including pulmonary fibrosis. NETs constitute a phenomenon in which decorated nuclear chromatin with cytosolic proteins is released into the extracellular space. PAD4 (peptidylarginine deiminase 4) plays an important role in the formation of NETs. However, the role of NETs in the pathogenesis of pulmonary fibrosis remains undefined. Here, we identified NETs in the alveolar and interstitial lung space of mice undergoing bleomycin (BLM)-induced lung fibrosis, which was suppressed by a pan-PAD inhibitor, Cl-amidine. In vitro, BLM directly induced NETs in blood neutrophils, which was also inhibited by Cl-amidine. Furthermore, Padi4 gene knockout (PAD4-KO) in mice led to the alleviation of BLM-induced NETs and pulmonary fibrosis and to the expression of inflammatory and fibrotic genes. PAD4 deficiency prevented decreases in alveolar epithelial and pulmonary vascular endothelial cell numbers and increases in ACTA2-positive mesenchymal cells and S100A4-positive fibroblasts in the lung. Hematopoietic cell grafts from PAD4-KO mice, not wild-type mice, resolved BLM-induced lung fibrosis and fibrotic gene expression in wild-type and PAD4-KO mice, suggesting that expression of PAD4 in hematopoietic cells may be involved in the development of lung fibrosis. These data suggest that PAD4 deficiency could ameliorate BLM-induced formation of NETs and lung fibrosis, suggesting that this pathway could serve as a therapeutic target for pulmonary fibrosis treatment.

Serum defensin levels in patients with systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis of skin and lung as well as involvement of kidney, gastrointestinal system and heart. Aetiology and exact mechanism of disease is poorly understood. The association between antimicrobial peptides (AMPs) and other diseases such as idiopathic pulmonary fibrosis, diffuse panbronchiolitis, pulmoner alveolar proteinosis and psoriasis have been reported. A small number of studies have examined the role of AMPs on autoimmune diseases which has not been studied in scleroderma yet. We aimed to investigate AMP serum levels and their association with disease characteristics of SSc.

METHODS

Forty-two patients (40 female, mean age 42 years) and 38 healthy subjects (32 female, mean age 38 years) were enrolled. For SSc patients, the following data were recorded: disease subset (limited/diffuse), autoantibodies (antinuclear, anti-centromere (ACA), and anti-SCL-70), blood tests, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), modified Rodnan skin score, presence and history of digital ulcers, kidney, gastrointestinal disease and lung involvement assessed by computed tomography and pulmonary function tests. Association between serum AMPs and disease characteristics were analysed.

RESULTS

Twenty-nine of the patients had diffuse (69%) and 13 of the patients had limited (31%) systemic sclerosis. Average disease duration was 5.5 years. Pulmonary involvement was detected in 20 patients (47.6%). Serum concentration of alpha defensin was higher than healthy subjects (563 ± 415 vs 377 ± 269 ng/mL, p = 0.02). However, no difference was observed for beta-1 and beta-2 defensins in SSc patients and healthy controls. In sub-group analysis patients with interstitial lung disease had higher levels of alpha defensin than those without lung involvement (684 ± 473 vs 430 ± 299 ng/ml, p = 0.04). There was also correlation between alfa defensin serum concentrations and CRP (r = 0.34).

CONCLUSIONS

Alpha defensin levels are increased in scleroderma patients and correlated with lung involvement indicating a role in the pathogenesis of disease.

TRIAL REGISTRATION

This study is not a clinical trial study.

Mass Spectrometry Imaging Reveals Neutrophil Defensins as Additional Biomarkers for Anti-PD-(L)1 Immunotherapy Response in NSCLC Patients

(1) Background: Therapeutic blocking of the interaction between programmed death-1 (PD-1) with its ligand PD-L1, an immune checkpoint, is a promising approach to restore the antitumor immune response. Improved clinical outcomes have been shown in different human cancers, including non-small cell lung cancer (NSCLC). Unfortunately, still a high number of NSCLC patients are treated with immunotherapy without obtaining any clinical benefit, due to the limitations of PD-L1 protein expression as the currently sole predictive biomarker for clinical use; (2) Methods: In this study, we applied mass spectrometry imaging (MSI) to discover new protein biomarkers, and to assess the possible correlation between candidate biomarkers and a positive immunotherapy response by matrix-assisted laser desorption/ionization (MALDI) MSI in 25 formalin-fixed paraffin-embedded (FFPE) pretreatment tumor biopsies (Biobank@UZA); (3) Results: Using MALDI MSI, we revealed that the addition of neutrophil defensin 1, 2 and 3 as pretreatment biomarkers may more accurately predict the outcome of immunotherapy treatment in NSCLC. These results were verified and confirmed with immunohistochemical analyses. In addition, we provide in-vitro evidence of the immune stimulatory effect of neutrophil defensins towards cancer cells; and (4) Conclusions: With proteomic approaches, we have discovered neutrophil defensins as additional prospective biomarkers for an anti-PD-(L)1 immunotherapy response. Thereby, we also demonstrated that the neutrophil defensins contribute in the activation of the immune response towards cancer cells, which could provide a new lead towards an anticancer therapy.

Application of Antimicrobial Peptides of the Innate Immune System in Combination With Conventional Antibiotics-A Novel Way to Combat Antibiotic Resistance?

Rapidly growing resistance of pathogenic bacteria to conventional antibiotics leads to inefficiency of traditional approaches of countering infections and determines the urgent need for a search of fundamentally new anti-infective drugs. Antimicrobial peptides (AMPs) of the innate immune system are promising candidates for a role of such novel antibiotics. However, some cytotoxicity of AMPs toward host cells limits their active implementation in medicine and forces attempts to design numerous structural analogs of the peptides with optimized properties. An alternative route for the successful AMPs introduction may be their usage in combination with conventional antibiotics. Synergistic antibacterial effects have been reported for a number of such combinations, however, the molecular mechanisms of the synergy remain poorly understood and little is known whether AMPs cytotoxicy for the host cells increases upon their application with antibiotics. Our study is directed to examination of a combined action of natural AMPs with different structure and mode of action (porcine protegrin 1, caprine bactenecin ChBac3.4, human alpha- and beta-defensins (HNP-1, HNP-4, hBD-2, hBD-3), human cathelicidin LL-37), and egg white lysozyme with varied antibiotic agents (gentamicin, ofloxacin, oxacillin, rifampicin, polymyxin B, silver nanoparticles) toward selected bacteria, including drug-sensitive and drug-resistant strains, as well as toward some mammalian cells (human erythrocytes, PBMC, neutrophils, murine peritoneal macrophages and Ehrlich ascites carcinoma cells). Using “checkerboard titrations” for fractional inhibitory concentration indexes evaluation, it was found that synergy in antibacterial action mainly occurs between highly membrane-active AMPs (e.g., protegrin 1, hBD-3) and antibiotics with intracellular targets (e.g., gentamicin, rifampcin), suggesting bioavailability increase as the main model of such interaction. In some combinations modulation of dynamics of AMP-bacterial membrane interaction in presence of the antibiotic was also shown. Cytotoxic effects of the same combinations toward normal eukaryotic cells were rarely synergistic. The obtained data approve that combined application of antimicrobial peptides with antibiotics or other antimicrobials is a promising strategy for further development of new approach for combating antibiotic-resistant bacteria by usage of AMP-based therapeutics. Revealing the conventional antibiotics that increase the activity of human endogenous AMPs against particular pathogens is also important for cure strategies elaboration.

Laboratory diagnosis of Prosthetic Joint Infections: Current concepts and present status

Prosthetic joint infection (PJI) is a challenging complication of total joint arthroplasty for both a microbiologist and an Arthroplasty surgeon with respect to diagnosis and management. The various investigations used for diagnosis of PJI based on different reference criteria have their own fallacies. Amongst the newer biomarkers evaluated to strengthen the diagnosis of PJI, Alpha defensins has been found to be a useful synovial fluid biomarker. In this review, we have discussed the various laboratory investigations, their benefits and shortcomings for the diagnosis of PJI. Other newer diagnostic methods like molecular methods and modified culture techniques to increase the performance characteristics for the diagnosis of PJI have also been presented.

Acute Exacerbation of Idiopathic Pulmonary Fibrosis

Acute exacerbation (AEx) of idiopathic pulmonary fibrosis (IPF) is a clinically important complication of IPF that carries a high morbidity and mortality. In the last decade we have learned much about this event, but there are many remaining questions: What is it? Why does it happen? How can we prevent it? How can we treat it? This chapter attempts to summarize and update our current understanding of the epidemiology, etiology, and management of acute exacerbation of IPF and point out areas where additional data are needed.

Significance of molecular biomarkers in idiopathic pulmonary fibrosis: A mini review

Idiopathic pulmonary fibrosis (IPF) is a chronic, irreversible condition with poor prognosis that is characterized by a variable clinical course in each patient, which renders it a complex disease with unknown causes. Despite the proven efficacy of novel antifibrotic therapies, including pirfenidone and nintedanib, the diagnosis and follow-up of IPF remain challenging. Hence, the identification of molecular biomarkers for early detection of IPF and to predict biologically determined individual clinical courses, has recently piqued the interest of researchers. Previous studies have demonstrated the diagnostic and prognostic efficacy of blood proteins such as KL-6, Surfactant protein (SP)-A, and SP-D, in patients with IPF. Due to their use in clinical practice in Japan, for approximately twenty years, a significant amount of data about these biomarkers has been accumulated. This paper reviews the recent literature on molecular biomarkers for IPF that have been developed in Japan as well as other potential molecular biomarkers.

Increased Levels of Free Circulating Dna in Patients with Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is difficult to diagnose because of numerous interstitial lung diseases with similar symptoms. As serum DNA has proven useful for early lung cancer detection, we aimed to define the relevance of this marker in discriminating IPF from other fibrotic and nonfibrotic/nonmalignant lung diseases. DNA was quantified in 191 subjects: 64 healthy individuals, 58 patients with IPF, 17 patients with nonspecific pulmonary fibrosis (13 idiopathic nonspecific interstitial pneumonia, 4 chronic hypersensitivity pneumonitis), and 52 patients with other diffuse/nonmalignant lung diseases. The median value of free DNA in IPF patients was 61.1 ng/mL (range 7.1–405), which was significantly higher than that of healthy donors (median 6.8, range 2.2–184) (p<0.001) and that of patients with other diffuse/nonmalignant lung diseases (median 28.0, range 4.2–281) (p=0.004). The area under the ROC curve was 0.926 (95% CI 0.879–0.973) when IPF patients were compared with healthy donors, and 0.702 (95% CI 0.609–0.796) when a comparison was made with non-IPF pulmonary diseases. In conclusion, we observed significantly higher levels of free circulating DNA in patients with IPF than in those with other fibrotic or diffuse/nonmalignant lung diseases.

Elevated α-defensin levels in plasma and bronchoalveolar lavage fluid from patients with myositis-associated interstitial lung disease

BACKGROUND

Interstitial lung disease (ILD) is a prognostic indicator of poor outcome in myositis. Although the pathogenesis of myositis-associated ILD is not well understood, neutrophils are thought to play a pivotal role. Neutrophils store azurophil granules that contain defensins, which are antimicrobial peptides that regulate the inflammatory response. Here, we evaluated levels of the human neutrophil peptides (HNPs) α-defensin 1 through 3 in patients with myositis-associated ILD to determine whether HNPs represent disease markers and play a role in the pathogenesis of myositis-associated ILD.

METHODS

HNP levels were measured in the plasma and bronchoalveolar lavage fluid (BALF) of 56 patients with myositis-associated ILD and 24 healthy controls by enzyme-linked immunosorbent assay.

RESULTS

Analysis revealed significantly higher HNP levels in plasma and BALF samples from patients with myositis-associated ILD as compared to those of healthy controls; however, plasma HNPs were significantly correlated with total cell counts in BALF. Additionally, BALF HNP levels were positively correlated with serum surfactant protein-A and the percentage of neutrophils in BALF, and BALF HNP levels correlated with the percentage of reticular opacities in high-resolution computed tomography results for patients with anti-aminoacyl-tRNA synthetase (ARS) antibody positive myositis-associated ILD. Survival did not differ between patients with higher and lower levels of plasma and BALF HNPs.

CONCLUSIONS

Plasma and BALF HNPs might reflect the disease activities of myositis-associated ILD, especially in patients with anti-ARS antibody positive myositis-associated ILD. However further studies are necessary to clarify whether HNPs represent disease markers and play roles in disease pathogenesis.

Biomarkers in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, debilitating, fibrotic lung disease leading to respiratory failure and ultimately to death. Being the prototype of interstitial lung diseases, IPF is characterized by marked heterogeneity regarding its clinical course. Despite significant progress in the understanding of its pathogenesis, we still cannot reliably predict the course of the disease and the response to treatment of an individual patient. Non-invasive biomarkers, in particular serum biomarkers, for the (early) diagnosis, differential diagnosis, prognosis and prediction of therapeutic response are urgently needed. Numerous molecules involved in alveolar epithelial cell injury, fibroproliferation and matrix remodeling as well as immune regulation have been proposed as potential biomarkers. Furthermore, genetic variants of TOLLIP, MUC5B, and other genes are associated with a differential response to treatment and with the development and/or the prognosis of IPF. Additionally, the bacterial signature in IPF lungs, as shown from microbiome analyses, as well as mitochondrial DNA seem to have promising roles as biomarkers. Moreover, combination of multiple biomarkers may identify comprehensive biomarker signatures in IPF patients. However, there is still a long way until these potential biomarkers complete or substitute for the clinical and functional parameters currently available for IPF.

Biomarkers of Tuberculosis Severity and Treatment Effect: A Directed Screen of 70 Host Markers in a Randomized Clinical Trial

More efficacious treatment regimens are needed for tuberculosis, however, drug development is impeded by a lack of reliable biomarkers of disease severity and of treatment effect. We conducted a directed screen of host biomarkers in participants enrolled in a tuberculosis clinical trial to address this need. Serum samples from 319 protocol-correct, culture-confirmed pulmonary tuberculosis patients treated under direct observation as part of an international, phase 2 trial were screened for 70 markers of infection, inflammation, and metabolism. Biomarker assays were specifically developed for this study and quantified using a novel, multiplexed electrochemiluminescence assay. We evaluated the association of biomarkers with baseline characteristics, as well as with detailed microbiologic data, using Bonferroni-adjusted, linear regression models. Across numerous analyses, seven proteins, SAA1, PCT, IL-1β, IL-6, CRP, PTX-3 and MMP-8, showed recurring strong associations with markers of baseline disease severity, smear grade and cavitation; were strongly modulated by tuberculosis treatment; and had responses that were greater for patients who culture-converted at 8weeks. With treatment, all proteins decreased, except for osteocalcin, MCP-1 and MCP-4, which significantly increased. Several previously reported putative tuberculosis-associated biomarkers (HOMX1, neopterin, and cathelicidin) were not significantly associated with treatment response. In conclusion, across a geographically diverse and large population of tuberculosis patients enrolled in a clinical trial, several previously reported putative biomarkers were not significantly associated with treatment response, however, seven proteins had recurring strong associations with baseline radiographic and microbiologic measures of disease severity, as well as with early treatment response, deserving additional study.

Acute Exacerbation in Interstitial Lung Disease

Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) has been defined as an acute, clinically significant deterioration that develops within less than 1 month without obvious clinical cause like fluid overload, left heart failure, or pulmonary embolism. Pathophysiologically, damage of the alveoli is the predominant feature of AE-IPF which manifests histopathologically as diffuse alveolar damage and radiologically as diffuse, bilateral ground-glass opacification on high-resolution computed tomography. A growing body of literature now focuses on acute exacerbations of interstitial lung disease (AE-ILD) other than idiopathic pulmonary fibrosis. Based on a shared pathophysiology it is generally accepted that AE-ILD can affect all patients with interstitial lung disease (ILD) but apparently occurs more frequently in patients with an underlying usual interstitial pneumonia pattern. The etiology of AE-ILD is not fully understood, but there are distinct risk factors and triggers like infection, mechanical stress, and microaspiration. In general, AE-ILD has a poor prognosis and is associated with a high mortality within 6–12 months. Although there is a lack of evidence based data, in clinical practice, AE-ILD is often treated with a high dose corticosteroid therapy and antibiotics. This article aims to provide a summary of the clinical features, diagnosis, management, and prognosis of AE-ILD as well as an update on the current developments in the field.

Host-Microbial Interactions in Idiopathic Pulmonary Fibrosis

RATIONALE

Changes in the respiratory microbiome are associated with disease progression in idiopathic pulmonary fibrosis (IPF). The role of the host response to the respiratory microbiome remains unknown.

OBJECTIVES

To explore the host-microbial interactions in IPF.

METHODS

Sixty patients diagnosed with IPF were prospectively enrolled together with 20 matched control subjects. Subjects underwent bronchoalveolar lavage (BAL), and peripheral whole blood was collected into PAXgene tubes for all subjects at baseline. For subjects with IPF, additional samples were taken at 1, 3, and 6 months and (if alive) 1 year. Gene expression profiles were generated using Affymetrix Human Gene 1.1 ST arrays.

MEASUREMENTS AND MAIN RESULTS

By network analysis of gene expression data, we identified two gene modules that strongly associated with a diagnosis of IPF, BAL bacterial burden (determined by 16S quantitative polymerase chain reaction), and specific microbial operational taxonomic units, as well as with lavage and peripheral blood neutrophilia. Genes within these modules that are involved in the host defense response include NLRC4, PGLYRP1, MMP9, and DEFA4. The modules also contain two genes encoding specific antimicrobial peptides (SLPI and CAMP). Many of these particular transcripts were associated with survival and showed longitudinal overexpression in subjects experiencing disease progression, further strengthening the relationship of the transcripts with disease.

CONCLUSIONS

Integrated analysis of the host transcriptome and microbial signatures demonstrated an apparent host response to the presence of an altered or more abundant microbiome. These responses remained elevated in longitudinal follow-up, suggesting that the bacterial communities of the lower airways may act as persistent stimuli for repetitive alveolar injury in IPF.

Role of Microbial Agents in Pulmonary Fibrosis

Pulmonary fibrosis is a form of lung disease that develops due to aberrant wound-healing following repeated alveoli injury in genetically susceptible individuals, resulting in chronic inflammation, excess deposition of the extracellular matrix components, mainly collagen, and scarring of lung tissue. In addition to irradiation, environmental agents such occupational inhalants, and chemotherapeutic agents, microbial agents also play a role in the etiology of the disease. While viruses have received the most attention, emerging evidence suggest that bacteria and fungi also play a part in the etiology of pulmonary fibrosis. Furthermore, successful use of antibiotics, antiviral and antifungal drugs in several studies to attenuate fibrosis progression is also an indication of microbial involvement in the pathogenesis of the disease and could be a promising therapeutic modality for treating pulmonary fibrosis initiated or exacerbated by infectious agents.

Low concentrations of human neutrophil peptide ameliorate experimental murine colitis

Human neutrophil peptides (HNPs) not only have antimicrobial properties, but also exert multiple immunomodulatory effects depending on the concentration used. We have previously demonstrated that the intraperitoneal administration of high-dose HNP-1 (100 µg/day) aggravates murine dextran sulfate sodium (DSS)-induced colitis, suggesting a potential pro-inflammatory role for HNPs at high concentrations. However, the role of low physiological concentrations of HNPs in the intestinal tract remains largely unknown. The aim of this study was to examine the effects of low concentrations of HNPs on intestinal inflammation. We first examined the effects of the mild transgenic overexpression of HNP-1 in DSS-induced colitis. HNP-1 transgenic mice have plasma HNP-1 levels similar to the physiological concentrations in human plasma. Compared to wild-type mice treated with DSS, HNP-1 transgenic mice treated with DSS had significantly lower clinical and histological scores, and lower colonic mRNA levels of pro-inflammatory cytokines, including interleukin (IL)-1β and tumor necrosis factor (TNF)-α. We then injected low-dose HNP-1 (5 µg/day) or phosphate-buffered saline (PBS) intraperitoneally into C57BL/6N and BALB/c mice administered DSS. The HNP-1-treated mice exhibited significantly milder colitis with reduced expression levels of pro-inflammatory cytokines compared with the PBS-treated mice. Finally, we examined the in vitro effects of HNP-1 on the expression of cytokines associated with macrophage activation. Low physiological concentrations of HNP-1 did not significantly affect the expression levels of IL-1β, TNF-α, IL-6 or IL-10 in colonic lamina propria mononuclear cells activated with heat-killed Escherichia coli, suggesting that the anti-inflammatory effects of HNP-1 on murine colitis may not be exerted by direct action on intestinal macrophages. Collectively, our data demonstrated a biphasic dose-dependent effect of HNP-1 on DSS-induced colitis: an amelioration at low concentrations and an aggravation at high concentrations. Low concentrations of HNPs may contribute to the maintenance of intestinal homeostasis.

Elevated Concentration of Defensins in Hepatitis C Virus-Infected Patients

Hepatitis C virus (HCV) is the major etiological agent of human non-A and non-B hepatitis, affecting around 180 million people worldwide. Defensins, small cysteine-rich cationic peptides, are shown to have potent antibacterial, antiviral, and antifungal properties. Defensins can be found in both normal and microbial infected patients, at variable concentrations. Notably, viral infections are often associated with elevated concentrations of defensins. The current study aimed to estimate the concentrations of total, α-, and β-defensins in serum taken from normal and HCV-infected patients. 12 healthy (noninfected) and 34 HCV-infected patients were enrolled. Standardized immunoassay kits were used to obtain serum concentrations of defensins. The obtained results were calibrated against kit standard reagents. Total defensin concentrations in HCV-infected patients were significantly higher (2- to 105-fold) compared to healthy individuals. The concentrations of α-defensins were also significantly elevated in the HCV-infected patients (31–1398 ng/50 μL). However, concentrations of β-defensins ranged from 44.5 ng/50 μL to 1056 ng/50 μL. The results did not reveal differences in serum defensin concentration between male and female HCV-infected patients. A-defensin concentration of ≥250 ng/50 μL was found to contain more β-defensins than total defensins and α-defensins. This study concludes, for the first time, that serum defensin levels are elevated in HCV-infected patients.

Association of elevated α-defensin levels with interstitial pneumonia in patients with systemic sclerosis

Background

Interstitial lung disease (ILD) is the leading cause of mortality in patients with systemic sclerosis (SSc). Although the pathogenesis of SSc-ILD is not well understood, neutrophils may play a pivotal role in this process. Neutrophils store azurophil granules that contain defensins, antimicrobial peptides that function in regulating the inflammatory response, and IL-8, a potent chemoattractant for neutrophils. The present study evaluated the levels of defensins and IL-8 in patients with SSc-ILD to determine their roles in disease pathogenesis.

Methods

Defensins (also known as human neutrophil peptides, HNPs) and IL-8 levels were measured in the serum and bronchoalveolar lavage fluid (BALF) of 33 patients with SSc-ILD and in 20 healthy controls by using ELISA.

Results

BALF analysis revealed a significant increase in HNPs in SSc-ILD patients (median; 240.0 pg/mL) than that of healthy controls (79.7 pg/mL). Additionally, IL-8 levels were higher in SSc-ILD patient serum and BALF as compared to healthy controls (16.4 pg/mL vs. 5.8 pg/mL and 15.4 pg/mL vs. 14.5 pg/mL, respectively). However, plasma HNPs levels were relatively unchanged. HNP and IL-8 levels in patient BALF displayed a significant positive correlation significantly correlated (r = 0.774, p <0.01), and which also correlated with clinical disease parameters—such as ILD biomarkers, pulmonary function tests, ratio of neutrophils and eosinophils in BALF, tricuspid regurgitation peak gradient (TRPG), and the extent of high-resolution computed tomography (HRCT) findings in the lung. Levels of plasma HNPs and serum IL-8 did not show a significant correlation with any clinical parameter. SSc-ILD progression was evaluated by pulmonary function tests, but no association was observed between VC change ratios and HNPs or IL-8 levels.

Conclusions

BALF levels of HNPs and IL-8 were higher in SSc-ILD than in healthy controls, and are associated with various clinical disease parameters. Further studies are needed to clarify the role of defensins and IL-8 in SSc-ILD pathogenesis.

Elevated plasma α-defensins in patients with acute exacerbation of fibrotic interstitial pneumonia

BACKGROUND

Patients with fibrosing interstitial lung diseases can develop acute exacerbation (AE). The aetiology of AE remains obscure, but neutrophils might play a pivotal role in the pathogenesis. Neutrophils store azurophil granules containing defensins that are antimicrobial peptides that also function in regulating the inflammatory response. The present study evaluates plasma levels of defensins in patients with AE of interstitial pneumonia (AE-IP) to determine their role(s) in the pathogenesis of AE-IP and whether defensins could serve as a biomarker of AE-IP.

METHODS

Plasma levels of defensins including human neutrophil peptides (HNPs) and human beta defensin 2 (HBD2) were measured using ELISA in 21 patients with AE-IP, 44 with stable (S)-IP, nine with IP complicated with pulmonary infection (Infec-IP), and in 23 healthy volunteers. Lung HNP expression was immunohistochemically analyzed in biopsy and autopsy tissues diagnosed as S-IP and AE-IP.

RESULTS

Plasma levels of HNPs were significantly higher in patients with AE-IP than with S-IP, but did not differ from those with Infec-IP and were not associated with other clinical features and prognosis. Plasma HNP were not specific in terms of distinguishing AE-IP from S-IP. Immunohistochemical analysis showed increased HNPs expression in accumulated neutrophils from patients with AE-IP. Plasma levels of HBD2 did not differ among patients with AE-IP, S-IP and Infec-IP.

CONCLUSIONS

Elevated plasma levels of HNPs were higher in AE-IP than in S-IP, but not specific enough to serve as candidate biomarkers of AE-IP. Further studies are needed to clarify the role of defensins in the pathogenesis of AE-IP.

Nonenzymatic conversion of ADP-ribosylated arginines to ornithine alters the biological activities of human neutrophil peptide-1

Activated neutrophils, recruited to the airway of diseased lung, release human neutrophil peptides (HNP1-4) that are cytotoxic to airway cells as well as microbes. Airway epithelial cells express arginine-specific ADP ribosyltransferase (ART)-1, a GPI-anchored ART that transfers ADP-ribose from NAD to arginines 14 and 24 of HNP-1. We previously reported that ADP-ribosyl-arginine is converted nonenzymatically to ornithine and that ADP-ribosylated HNP-1 and ADP-ribosyl-HNP-(ornithine) were isolated from bronchoalveolar lavage fluid of a patient with idiopathic pulmonary fibrosis, indicating that these reactions occur in vivo. To determine effects of HNP-ornithine on the airway, three analogs of HNP-1, HNP-(R14orn), HNP-(R24orn), and HNP-(R14,24orn), were tested for their activity against Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus; their cytotoxic effects on A549, NCI-H441, small airway epithelial-like cells, and normal human lung fibroblasts; and their ability to stimulate IL-8 and TGF-β1 release from A549 cells, and to serve as ART1 substrates. HNP and the three analogs had similar effects on IL-8 and TGF-β1 release from A549 cells and were all cytotoxic for small airway epithelial cells, NCI-H441, and normal human lung fibroblasts. HNP-(R14,24orn), when compared with HNP-1 and HNP-1 with a single ornithine substitution for arginine 14 or 24, exhibited reduced cytotoxicity, but it enhanced proliferation of A549 cells and had antibacterial activity. Thus, arginines 14 and 24, which can be ADP ribosylated by ART1, are critical to the regulation of the cytotoxic and antibacterial effects of HNP-1. The HNP analog, HNP-(R14,24orn), lacks the epithelial cell cytotoxicity of HNP-1, but partially retains its antibacterial activity and thus may have clinical applications in airway disease.

Molecular biomarkers in idiopathic pulmonary fibrosis

Molecular biomarkers are highly desired in idiopathic pulmonary fibrosis (IPF), where they hold the potential to elucidate underlying disease mechanisms, accelerated drug development, and advance clinical management. Currently, there are no molecular biomarkers in widespread clinical use for IPF, and the search for potential markers remains in its infancy. Proposed core mechanisms in the pathogenesis of IPF for which candidate markers have been offered include alveolar epithelial cell dysfunction, immune dysregulation, and fibrogenesis. Useful markers reflect important pathological pathways, are practically and accurately measured, have undergone extensive validation, and are an improvement upon the current approach for their intended use. The successful development of useful molecular biomarkers is a central challenge for the future of translational research in IPF and will require collaborative efforts among those parties invested in advancing the care of patients with IPF.

Acute Exacerbation of Idiopathic Pulmonary Fibrosis

Acute exacerbation of idiopathic pulmonary fibrosis (IPF) is a clinically important complication of IPF that carries a high morbidity and mortality. In the last decade, we have learned much about this event, but there are many remaining questions: What is it? Why does it happen? How can we prevent it? How can we treat it? This chapter attempts to summarize our current understanding of the epidemiology, etiology, and management of acute exacerbation of IPF and point out areas where additional data are sorely needed.

Cellular response to Trypanosoma cruzi infection induces secretion of defensin α-1, which damages the flagellum, neutralizes trypanosome motility, and inhibits infection

Human defensins play a fundamental role in the initiation of innate immune responses to some microbial pathogens. Here we show that colonic epithelial model HCT116 cells respond to Trypanosoma cruzi infection by secreting defensin α-1, which reduces infection. We also report the early effects of defensin α-1 on invasive trypomastigotes that involve damage of the flagellar structure to inhibit parasite motility and reduce cellular infection. Short exposure of defensin α-1 to trypomastigotes shows that defensin α-1 binds to the flagellum, resulting in flagellar membrane and axoneme alterations, followed by breaking of the flagellar membrane connected to the trypanosome body, leading to detachment and release of the parasite flagellum. In addition, defensin α-1 induces a significant reduction in parasite motility in a peptide concentration-dependent manner, which is abrogated by anti-defensin α-1 IgG. Preincubation of trypomastigotes with a concentration of defensin α-1 that inhibits 50% trypanosome motility significantly reduced cellular infection by 80%. Thus, human defensin α-1 is an innate immune molecule that is secreted by HCT116 cells in response to T. cruzi infection, inhibits T. cruzi motility, and plays an important role in reducing cellular infection. This is the first report showing a novel cellular innate immune response to a human parasite by secretion of defensin α-1, which neutralizes the motility of a human parasite to reduce cellular infection. The mode of activity of human defensin α-1 against T. cruzi and its function may provide insights for the development of new antiparasitic strategies.

Acute exacerbations in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, fibrosing interstitial lung disease that primarily affects older adults. Median survival after diagnosis is 2–3 years. The clinical course of IPF may include periods of acute deterioration in respiratory function, which are termed acute exacerbations of IPF (AEx-IPF) when a cause cannot be identified. AEx-IPF may represent a sudden acceleration of the underlying disease process of IPF, or a biologically distinct pathological process that is clinically undiagnosed. An AEx-IPF can occur at any time during the course of IPF and may be the presenting manifestation. The incidence of AEx-IPF is hard to establish due to variation in the methodology used to assess AEx-IPF in different studies, but AEx-IPF are believed to occur in between 5 and 10% of patients with IPF every year. Risk factors for AEx-IPF are unclear, but there is evidence that poorer lung function increases the risk of an AEx-IPF and reduces the chances of a patient surviving an AEx-IPF. The presence of comorbidities such as gastroesophageal reflux disease (GERD) and pulmonary hypertension may also increase the risk of an AEx-IPF. AEx-IPF are associated with high morbidity and mortality. Patients who experience an AEx-IPF show a worsened prognosis and AEx-IPF are believed to reflect disease progression in IPF. Current treatments for AEx-IPF have only limited data to support their effectiveness. The latest international treatment guidelines state that supportive care remains the mainstay of treatment for AEx-IPF, but also give a weak recommendation for the treatment of the majority of patients with AEx-IPF with corticosteroids. There is emerging evidence from clinical trials of investigational therapies that chronic treatment of IPF may reduce the incidence of AEx-IPF. Additional clinical trials investigating this are underway.

Acute exacerbation of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive and ultimately fatal disease, the clinical course of which in individual patients is highly variable. Sudden deterioration of a patient's respiratory condition during a stable course is not uncommon. Many cases of uncertain etiology have been called acute exacerbation (AEx) of IPF, under the assumption of sudden acceleration of the underlying disease process. In recent years, several studies have reported the clinical significance of AEx-IPF. In 2007 Collard and colleagues created a Consensus Perspective, which proposed consensus definition and standard diagnostic criteria. This review primarily discusses studies performed after this Consensus Perspective.

The diagnosis of idiopathic pulmonary fibrosis and its complications

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a devastating, progressive condition with a median survival of 2.8 - 4 years from diagnosis. Clinicians confronted with a patient with fibrosing lung disease need to be reliably able to distinguish IPF from other diffuse parenchymal lung diseases. Furthermore, they need to be able to gauge prognosis, evaluate timing of interventions including referral for transplant, assess reliably the effectiveness of treatment and be able to detect rapidly the development of disease complications.

OBJECTIVE/METHOD

This paper provides an overview of currently available diagnostic tests for IPF and its complications and evaluates the possible future role of candidate biomarkers in the diagnosis and assessment of patients with IPF. A literature search was performed for papers evaluating diagnostic tests in the diagnosis of IPF and its complications.

CONCLUSION

Computed tomography combined with clinical data is sufficient for diagnosing IPF in approximately two-thirds of patients with the condition. For the remaining patients, histological assessment is important in achieving a precise diagnosis. Serial measurements of carbon monoxide diffusing capacity and forced vital capacity provide the best prognostic indicator in IPF. Potential biomarkers for diagnosing IPF include KL-6, MMP1 and MMP7. Brain naturetic peptide shows promise as a non-invasive screening tool for the diagnosis of IPF-associated pulmonary hypertension.

The peripheral blood transcriptome identifies the presence and extent of disease in idiopathic pulmonary fibrosis

Rationale

Peripheral blood biomarkers are needed to identify and determine the extent of idiopathic pulmonary fibrosis (IPF). Current physiologic and radiographic prognostic indicators diagnose IPF too late in the course of disease. We hypothesize that peripheral blood biomarkers will identify disease in its early stages, and facilitate monitoring for disease progression.

Methods

Gene expression profiles of peripheral blood RNA from 130 IPF patients were collected on Agilent microarrays. Significance analysis of microarrays (SAM) with a false discovery rate (FDR) of 1% was utilized to identify genes that were differentially-expressed in samples categorized based on percent predicted D_LCO and FVC.

Main Measurements and Results

At 1% FDR, 1428 genes were differentially-expressed in mild IPF (D_LCO >65%) compared to controls and 2790 transcripts were differentially- expressed in severe IPF (D_LCO >35%) compared to controls. When categorized by percent predicted D_LCO, SAM demonstrated 13 differentially-expressed transcripts between mild and severe IPF (< 5% FDR). These include CAMP, CEACAM6, CTSG, DEFA3 and A4, OLFM4, HLTF, PACSIN1, GABBR1, IGHM, and 3 unknown genes. Principal component analysis (PCA) was performed to determine outliers based on severity of disease, and demonstrated 1 mild case to be clinically misclassified as a severe case of IPF. No differentially-expressed transcripts were identified between mild and severe IPF when categorized by percent predicted FVC.

Conclusions

These results demonstrate that the peripheral blood transcriptome has the potential to distinguish normal individuals from patients with IPF, as well as extent of disease when samples were classified by percent predicted D_LCO, but not FVC.

Cationic host defence peptides: multifaceted role in immune modulation and inflammation

Host defence peptides (HDPs) are innate immune effector molecules found in diverse species. HDPs exhibit a wide range of functions ranging from direct antimicrobial properties to immunomodulatory effects. Research in the last decade has demonstrated that HDPs are critical effectors of both innate and adaptive immunity. Various studies have hypothesized that the antimicrobial property of certain HDPs may be largely due to their immunomodulatory functions. Mechanistic studies revealed that the role of HDPs in immunity is very complex and involves various receptors, signalling pathways and transcription factors. This review will focus on the multiple functions of HDPs in immunity and inflammation, with special reference to cathelicidins, e.g. LL-37, certain defensins and novel synthetic innate defence regulator peptides. We also discuss emerging concepts of specific HDPs in immune-mediated inflammatory diseases, including the potential use of cationic peptides as therapeutics for immune-mediated inflammatory disorders.

A genetic polymorphism in the CAV1 gene associates with the development of bronchiolitis obliterans syndrome after lung transplantation

Background

Caveolin 1 (Cav-1) is the primary structural component of cell membrane invaginations called 'caveolae'. Expression of Cav-1 is implicated in the pathogenesis of pulmonary fibrosis. Genetic polymorphisms in the CAV1 gene influence the function of Cav-1 in malignancies and associate with renal allograft fibrosis. Chronic allograft rejection after lung transplantation, called 'bronchiolitis obliterans syndrome' (BOS), is also characterised by the development of fibrosis.

In this study, we investigated whether CAV1 genotypes associate with BOS and whether Cav-1 serum levels are influenced by the CAV1 genotype and can be used as a biomarker to predict the development of BOS.

Methods

Twenty lung transplant recipients with BOS (BOS^pos), ninety without BOS (BOS^neg) and four hundred twenty-two healthy individuals donated DNA samples. Four SNPs in CAV1 were genotyped. Serial Cav-1 serum levels were measured in a matched cohort of 10 BOS^pos patients and 10 BOS^neg patients. Furthermore, single-time point Cav-1 serum levels were measured in 33 unmatched BOS^neg patients and 60 healthy controls.

Results

Homozygosity of the minor allele of rs3807989 was associated with an increased risk for BOS (odds ratio: 6.13; P = 0.0013). The median Cav-1 serum level was significantly higher in the BOS^pos patients than in the matched BOS^neg patients (P = 0.026). Longitudinal analysis did not show changes in Cav-1 serum levels over time in both groups. The median Cav-1 serum level in the group of 43 BOS^neg patients was lower than that in the healthy control group (P = 0.046).

In lung transplant recipients, homozygosity of the minor allele of rs3807989 and rs3807994 was associated with increased Cav-1 serum levels.

Conclusion

In lung transplant recipients, the CAV1 SNP rs3807989 was associated with the development of BOS and Cav-1 serum levels were influenced by the CAV1 genotype.

Human neutrophil peptide in lung chronic allograft dysfunction

CONTEXT

Our previous case-control study identified human neutrophil peptide (HNP) as a potential biomarker for bronchiolitis obliterans syndrome (BOS) in lung transplant recipients.

OBJECTIVE

To prospectively validate HNP as a biomarker for BOS.

MATERIALS AND METHODS

HNP was measured by ELISA in bronchoalveolar lavage (BAL) fluid in lung transplant recipients.

RESULTS

The first HNP measurement after reaching baseline pulmonary function was predictive of developing BOS ≥2 (p = 0.0419). HNP remained elevated in those that developed BOS. The effect of potential confounders did not significantly impact BOS-free survival time.

CONCLUSION

HNP levels are elevated early and persistently in those that develop BOS.

TLR9 differentiates rapidly from slowly progressing forms of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis is characterized by diffuse alveolar damage and severe fibrosis, resulting in a steady worsening of lung function and gas exchange. Because idiopathic pulmonary fibrosis is a generally progressive disorder with highly heterogeneous disease progression, we classified affected patients as either rapid or slow progressors over the first year of follow-up and then identified differences between the two groups to investigate the mechanism governing rapid progression. Previous work from our laboratory has demonstrated that Toll-like receptor 9 (TLR9), a pathogen recognition receptor that recognizes unmethylated CpG motifs in bacterial and viral DNA, promotes myofibroblast differentiation in lung fibroblasts cultured from biopsies of patients with idiopathic pulmonary fibrosis. Therefore, we hypothesized that TLR9 functions as both a sensor of pathogenic molecules and a profibrotic signal in rapidly progressive idiopathic pulmonary fibrosis. Indeed, TLR9 was present at higher concentrations in surgical lung biopsies from rapidly progressive patients than in tissue from slowly progressing patients. Moreover, fibroblasts from rapid progressors were more responsive to the TLR9 agonist, CpG DNA, than were fibroblasts from slowly progressing patients. Using a humanized severe combined immunodeficient mouse, we then demonstrated increased fibrosis in murine lungs receiving human lung fibroblasts from rapid progressors compared with mice receiving fibroblasts from slowly progressing patients. This fibrosis was exacerbated by intranasal CpG challenges. Furthermore, CpG induced the differentiation of blood monocytes into fibrocytes and the epithelial-to-mesenchymal transition of A549 lung epithelial cells. These data suggest that TLR9 may drive the pathogenesis of rapidly progressive idiopathic pulmonary fibrosis and may serve as a potential indicator for this subset of the disease.

[Acute exacerbation of idiopathic pulmonary fibrosis]

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disease. Its natural history may have episodes of acute exacerbation (AE-IPF), whose best accepted definition would be a clinically significant acute worsening, without identified cause, in patients with an underlying IPF. The incidence of AE-IPF ranges from 5%-19% of patients per year. It is estimated that acute deterioration of the respiratory status occurred in 47% of these patients before death. A rapidly progressive dyspnoea is the most prominent symptom, with associated cough, fever and flu-like symptoms. The diagnosis is strengthened by the presence of leukocytosis on the blood count, neutrophilia on the bronchoalveolar lavage, and development of new diffuse bilateral ground-glass opacities superimposed on the pre-existing radiographic findings. The major histological finding is diffuse alveolar damage. Methylprednisolone seems to be the best therapeutic option, although the treatment response is usually poor.

Human defensins and LL-37 in mucosal immunity

Defensins are widespread in nature and have activity against a broad range of pathogens. Defensins have direct antimicrobial effects and also modulate innate and adaptive immune responses. We consider the role of human defensins and the cathelicidin LL-37 in defense of respiratory, gastrointestinal, and genitourinary tracts and the oral cavity, skin, and eye. Human beta-defensins (hBDs) and human defensins 5 and 6 (HD5 and -6) are involved most obviously in mucosal responses, as they are produced principally by epithelial cells. Human alpha-defensins 1-4 (or HNPs 1-4) are produced principally by neutrophils recruited to the mucosa. Understanding the biology of defensins and LL-37 is the beginning to clarify the pathophysiology of mucosal inflammatory and infectious diseases (e.g., Crohn's disease, atopic dermatitis, lung or urinary infections). Challenges for these studies are the redundancy of innate defense mechanisms and the presence and interactions of many innate defense proteins in mucosal secretions.

ADP-ribosylation of human defensin HNP-1 results in the replacement of the modified arginine with the noncoded amino acid ornithine

Defensins (e.g., human neutrophil peptides, or HNPs) contribute to innate immunity through diverse actions, including microbial killing; high concentrations are present in the lung in response to inflammation. Arginines are critical for HNP activity, which is decreased by their replacement with ornithine. ADP-ribosyltransferases (ARTs) catalyze transfer of ADP-ribose from NAD to an acceptor arginine in a protein substrate, whereas ADP-ribosylarginine hydrolases release ADP-ribose. ART1 on the surface of airway epithelial cells ADP-ribosylated HNP-1 specifically on arginines 14 and 24, with ADP-ribosylation altering biological activity. Di- and mono-ADP-ribosylated HNP-1 were isolated from bronchoalveolar lavage fluid (BALF) of patients with asthma and idiopathic pulmonary fibrosis (IPF), suggesting a role for ADP-ribosylation in disease. In the present study, we observed that ART1-catalyzed ADP-ribosylation of HNP-1 in vitro generated a product with ADP-ribose on arginine 24, and ornithine replacing arginine at position 14. We hypothesized that ADP-ribosylarginine is susceptible to a nonenzymatic hydrolytic reaction yielding ornithine. On incubation of di- or mono-ADP-ribosyl-HNP-1 at 37 degrees C, ADP-ribosylarginine was partially replaced by ornithine, whereas ornithine was not detected by amino acid analysis and mass spectrometry of unmodified HNP-1 incubated under the same conditions. Further, ornithine was produced from the model compound, ADP-ribosylarginine. BALF from an IPF patient contained ADP-ribosyl-HNP-ornithine as well as mono- and di-ADP-ribosylated HNP-1, consistent with in vivo conversion of arginine to ornithine. Targeted ADP-ribosylation of specific arginines by transferases, resulting in their replacement with ornithine, is an alternative pathway for regulation of protein function through posttranslational modification.

Alpha-defensins increase lung fibroblast proliferation and collagen synthesis via the beta-catenin signaling pathway

Alpha-defensins are released from granules of leukocytes and are implicated in inflammatory and fibrotic lung diseases. In the present study, the effects of alpha-defensins on the proliferation and collagen synthesis of lung fibroblasts were examined. We found that alpha-defensin-1 and alpha-defensin-2 induced dose-dependent increases in the incorporation of 5-bromo-2'-deoxy-uridine into newly synthesized DNA in two lines of human lung fibroblasts (HFL-1 and LL-86), suggesting that alpha-defensin-1 and alpha-defensin-2 stimulate the proliferation of lung fibroblasts. alpha-defensin-1 and alpha-defensin-2 also increased collagen-I mRNA (COL1A1) levels and protein contents of collagen-I and active/dephosphorylated beta-catenin without changes in total beta-catenin protein content in lung fibroblasts (HFL-1 and LL-86). Inhibition of the beta-catenin signaling pathway using quercetin prevented increases in cell proliferation and the protein content of collagen-I and active/dephosphorylated beta-catenin in lung fibroblasts, and in COL1A1 mRNA levels and collagen release into culture medium induced by alpha-defensin-1 and alpha-defensin-2. Knocking-down beta-catenin using small interfering RNA technology also prevented alpha-defensin-induced increases in cell proliferation and the protein content of collagen-I and active/dephosphorylated beta-catenin in lung fibroblasts, and in COL1A1 mRNA levels. Moreover, increases in the phosphorylation of glycogen synthase kinase 3beta, accumulation/activation of beta-catenin, and collagen synthesis induced by alpha-defensin-1 and alpha-defensin-2 were prevented by p38 mitogen-activated protein kinase inhibitor SB203580 and phosphoinositide 3-kinase inhibitor LY294002. These results indicate that alpha-defensin-1 and alpha-defensin-2 stimulate proliferation and collagen synthesis of lung fibroblasts. The beta-catenin signaling pathway mediates alpha-defensin-induced increases in cell proliferation and collagen synthesis of lung fibroblasts. alpha-defensin-induced activation of beta-catenin in lung fibroblasts might be caused by phosphorylation/inactivation of glycogen synthase kinase 3beta as a result of the activation of the p38 mitogen-activated protein kinase and phosphoinositide 3-kinase/Akt pathways.

Gene expression profiles of acute exacerbations of idiopathic pulmonary fibrosis

RATIONALE

The molecular mechanisms underlying acute exacerbations of idiopathic pulmonary fibrosis (IPF) are poorly understood. We studied the global gene expression signature of acute exacerbations of IPF.

OBJECTIVES

To understand the gene expression patterns of acute exacerbations of IPF.

METHODS

RNA was extracted from 23 stable IPF lungs, 8 IPF lungs with acute exacerbation (IPF-AEx), and 15 control lungs and used for hybridization on Agilent gene expression microarrays. Functional analysis of genes was performed with Spotfire and Genomica. Gene validations for MMP1, MMP7, AGER, DEFA1-3, COL1A2, and CCNA2 were performed by real-time quantitative reverse transcription-polymerase chain reaction. Immunohistochemistry and in situ terminal deoxynucleotidyltransferase dUTP nick end-labeling assays were performed on the same tissues used for the microarray. ELISA for alpha-defensins was performed on plasma from control subjects, patients with stable IPF, and patients with IPF-AEx.

MEASUREMENTS AND MAIN RESULTS

Gene expression patterns in IPF-AEx and IPF samples were similar for the genes that distinguish IPF from control lungs. Five hundred and seventy-nine genes were differentially expressed (false discovery rate < 5%) between stable IPF and IPF-AEx. Functional analysis of these genes did not indicate any evidence of an infectious or overwhelming inflammatory etiology. CCNA2 and alpha-defensins were among the most up-regulated genes. CCNA2 and alpha-defensin protein levels were also higher and localized to the epithelium of IPF-AEx, where widespread apoptosis was also detected. alpha-Defensin protein levels were increased in the peripheral blood of patients with IPF-AEx.

CONCLUSIONS

Our results indicate that IPF-AEx is characterized by enhanced epithelial injury and proliferation, as reflected by increases in CCNA2 and alpha-defensins and apoptosis of epithelium. The concomitant increase in alpha-defensins in the peripheral blood and lungs may suggest their use as biomarkers for this disorder.

Plectasin has antibacterial activity and no affect on cell viability or IL-8 production

Animals and plants express endogenous peptide antibiotics called defensins. Defensins show broad-spectrum antimicrobial activity, even against bacteria that have resistance to conventional antibiotics, which has made them viable candidates for new antibiotics. However, human defensins have failed to reach the market because of their cytotoxic effects and non-antimicrobial bioactivities. Plectasin is a defensin that has shown promise but has not had its potentially negative effects clarified. To address this issue, we examined plectasin's cytotoxicity in human cells using an AlamarBlue reduction assay, its interleukin (IL)-8-inducing capacity using real-time PCR and ELISA, and measured its MIC against bacteria. We confirmed that plectasin has specific antibacterial activity against Streptococcus pneumoniae. Plectasin showed no cytotoxicity to A549 cells, normal human bronchial epithelial cells, or lung fibroblasts, and it did not induce IL-8 transcription or production in A549 cells. Our results suggest that plectasin could be an inoffensive alternative antibiotic for clinical application.

High serum levels of thrombospondin-1 in patients with idiopathic interstitial pneumonia

Thrombospondin-1 (TSP-1), a multifunctional matricellular glycoprotein, can activate transforming growth factor-beta, an important profibrotic cytokine involved in various fibrotic diseases. TSP-1 is expressed in the lung tissue of animal models of bleomycin-induced pulmonary fibrosis and in patients with some interstitial lung diseases. The present study investigated the serum and bronchoalveolar lavage fluid (BALF) levels of TSP-1 in the idiopathic interstitial pneumonias (IIPs) and the relationship between these levels and other clinical factors. The TSP-1 in the serum and BALF were measured in 45 patients with pathologically diagnosed IIPs [22 with usual interstitial pneumonia (UIP), 23 patients with non-specific interstitial pneumonia (NSIP)], as well as in 28 patients with pulmonary sarcoidosis and 15 healthy volunteers using a competitive enzyme immunoassay. The expression and localization of TSP-1 in the lungs were analyzed by immunohistochemical staining. The serum TSP-1 levels were significantly higher in patients with IIPs than in either those with sarcoidosis or the controls. These levels correlated well with those of an angiogenic cytokine vascular endothelial growth factor while correlating inversely with the %VC. Positive immunostaining of TSP-1 was predominantly observed in the regenerated alveolar epithelium and alveolar macrophages in the lung. Our findings suggest that the circulating TSP-1 levels are associated with the presence of interstitial pneumonia, but further studies are required before we can definitively conclude that TSP-1 plays a role in the pathogenesis of these diseases.

MMP1 and MMP7 as potential peripheral blood biomarkers in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive fibrotic lung disease associated with substantial morbidity and mortality. The objective of this study was to determine whether there is a peripheral blood protein signature in IPF and whether components of this signature may serve as biomarkers for disease presence and progression.

METHODS AND FINDINGS

We analyzed the concentrations of 49 proteins in the plasma of 74 patients with IPF and in the plasma of 53 control individuals. We identified a combinatorial signature of five proteins-MMP7, MMP1, MMP8, IGFBP1, and TNFRSF1A-that was sufficient to distinguish patients from controls with a sensitivity of 98.6% (95% confidence interval [CI] 92.7%-100%) and specificity of 98.1% (95% CI 89.9%-100%). Increases in MMP1 and MMP7 were also observed in lung tissue and bronchoalveolar lavage fluid obtained from IPF patients. MMP7 and MMP1 plasma concentrations were not increased in patients with chronic obstructive pulmonary disease or sarcoidosis and distinguished IPF compared to subacute/chronic hypersensitivity pneumonitis, a disease that may mimic IPF, with a sensitivity of 96.3% (95% CI 81.0%-100%) and specificity of 87.2% (95% CI 72.6%-95.7%). We verified our results in an independent validation cohort composed of patients with IPF, familial pulmonary fibrosis, subclinical interstitial lung disease (ILD), as well as with control individuals. MMP7 and MMP1 concentrations were significantly higher in IPF patients compared to controls in this cohort. Furthermore, MMP7 concentrations were elevated in patients with subclinical ILD and negatively correlated with percent predicted forced vital capacity (FVC%) and percent predicted carbon monoxide diffusing capacity (DLCO%).

CONCLUSIONS

Our experiments provide the first evidence for a peripheral blood protein signature in IPF to our knowledge. The two main components of this signature, MMP7 and MMP1, are overexpressed in the lung microenvironment and distinguish IPF from other chronic lung diseases. Additionally, increased MMP7 concentration may be indicative of asymptomatic ILD and reflect disease progression.

The role of cathelicidin and defensins in pulmonary inflammatory diseases

Antimicrobial peptides (AMPs) protect the epithelia of mucosal organs like the respiratory or the gastrointestinal tract from invading microorganisms. As an integral part of the innate immune system they display antimicrobial activity against gram- and gram-negative bacteria as well as against fungi and enveloped and non-enveloped viruses. Besides their microbicidal effects they have important functions in the regulation of repair and inflammation. AMPs are sometimes referred to as 'alarmins' due to their ability to recruit, modulate and activate components of the immune system. In contrast, some AMPs suppress activation of the immune system. AMPs are also involved in tissue repair, cancer biology and angiogenesis. Based on their antimicrobial and immunomodulatoy functions, AMPs are probably involved in the pathogenesis of infectious and inflammatory diseases of the lung. Inborn or acquired deficiencies contribute to susceptibility to infection and colonisation. The potential pro-inflammatory role of AMPs contributes to the disease processes in inflammatory disorders such as asthma, chronic obstructive pulmonary disease, sepsis or pulmonary fibrosis. This review summarises the knowledge about the functions of AMPs in the pulmonary innate host defence system and their role in respiratory disease.

Human defensin alpha-1 causes Trypanosoma cruzi membrane pore formation and induces DNA fragmentation, which leads to trypanosome destruction

Human defensins play a fundamental role in the initiation of innate immune responses to some microbial pathogens. Here we show that human defensin alpha-1 displays a trypanocidal role against Trypanosoma cruzi, the causative agent of Chagas' disease. The toxicity of human defensin alpha-1 against T. cruzi is mediated by membrane pore formation and the induction of nuclear and mitochondrial DNA fragmentation, leading to trypanosome destruction. Exposure of trypomastigote and amastigote forms of T. cruzi to defensin alpha-1 significantly reduced parasite viability in a peptide concentration-dependent and saturable manner. The toxicity of defensin alpha-1 against T. cruzi is blocked by anti-defensin alpha-1 immunoglobulin G. Electron microscopic analysis of trypomastigotes exposed to defensin alpha-1 revealed pore formation in the cellular and flagellar membranes, membrane disorganization, and blebbing as well as cytoplasmic vacuolization. Furthermore, human defensin alpha-1 enters the trypanosome when membrane pores are present and is associated with later intracellular damage. Trypanosome membrane depolarization abolished the toxicity of defensin alpha-1 against the parasite. Preincubation of trypomastigotes with defensin alpha-1 followed by exposure to human epithelial cells significantly reduced T. cruzi infection in these cells. Thus, human defensin alpha-1 is an innate immune molecule that causes severe toxicity to T. cruzi and plays an important role in reducing cellular infection. This is the first report showing that human defensin alpha-1 causes membrane pore formation in a human parasite, leading to trypanosome destruction.