Mononuclear Phagocytes and Airway Epithelial Cells: Novel Sources of Matrix Metalloproteinase-8 (MMP-8) in Patients with Idiopathic Pulmonary Fibrosis

Objectives: Matrix metalloproteinase-8 (MMP-8) promotes lung fibrotic responses to bleomycin in mice. Although prior studies reported that MMP-8 levels are increased in plasma and bronchoalveolar lavage fluid (BALF) samples from IPF patients, neither the bioactive forms nor the cellular sources of MMP-8 in idiopathic pulmonary fibrosis (IPF) patients have been identified. It is not known whether MMP-8 expression is dys-regulated in IPF leukocytes or whether MMP-8 plasma levels correlate with IPF outcomes. Our goal was to address these knowledge gaps. Methods: We measured MMP-8 levels and forms in blood and lung samples from IPF patients versus controls using ELISAs, western blotting, and qPCR, and assessed whether MMP-8 plasma levels in 73 IPF patients correlate with rate of lung function decline and mortality. We used immunostaining to localize MMP-8 expression in IPF lungs. We quantified MMP-8 levels and forms in blood leukocytes from IPF patients versus controls. Results: IPF patients have increased BALF, whole lung, and plasma levels of soluble MMP-8 protein. Active MMP-8 is the main form elevated in IPF lungs. MMP-8 mRNA levels are increased in monocytes from IPF patients, but IPF patients and controls have similar levels of MMP-8 in PMNs. Surprisingly, macrophages and airway epithelial cells are the main cells expressing MMP-8 in IPF lungs. Plasma and BALF MMP-8 levels do not correlate with decline in lung function and/or mortality in IPF patients. Conclusion: Blood and lung MMP-8 levels are increased in IPF patients. Active MMP-8 is the main form elevated in IPF lungs. Surprisingly, blood monocytes, lung macrophages, and airway epithelial cells are the main cells in which MMP-8 is upregulated in IPF patients. Plasma and BALF MMP-8 levels are unlikely to serve as a prognostic biomarker for IPF patients. These results provide new information about the expression patterns of MMP-8 in IPF patients

Mitochondrial iron chelation ameliorates cigarette-smoke induced bronchitis and emphysema in mice

Chronic obstructive pulmonary disease (COPD) is linked to both cigarette smoking and genetic determinants. We have previously identified iron-responsive element binding protein 2 (IRP2) as an important COPD susceptibility gene, with IRP2 protein increased in the lungs of individuals with COPD. Here we demonstrate that mice deficient in Irp2 were protected from cigarette smoke (CS)-induced experimental COPD. By integrating RIP-Seq, RNA-Seq, gene expression and functional enrichment clustering analysis, we identified IRP2 as a regulator of mitochondrial function in the lung. IRP2 increased mitochondrial iron loading and cytochrome c oxidase (COX), which led to mitochondrial dysfunction and subsequent experimental COPD. Frataxin-deficient mice with higher mitochondrial iron loading had impaired airway mucociliary clearance (MCC) and higher pulmonary inflammation at baseline, whereas synthesis of cytochrome c oxidase (Sco2)-deficient mice with reduced COX were protected from CS-induced pulmonary inflammation and impairment of MCC. Mice treated with a mitochondrial iron chelator or mice fed a low-iron diet were protected from CS-induced COPD. Mitochondrial iron chelation also alleviated CS-impairment of MCC, CS-induced pulmonary inflammation and CS-associated lung injury in mice with established COPD, suggesting a critical functional role and potential therapeutic intervention for the mitochondrial-iron axis in COPD

Asthma–COPD overlap syndrome (ACOS) in primary care of four Latin America countries: the PUMA study

Abstract Background Asthma–COPD overlap syndrome (ACOS) prevalence varies depending on the studied population and definition criteria. The prevalence and clinical characteristics of ACOS in an at-risk COPD primary care population from Latin America was assessed. Methods Patients ≥40 years, current/ex-smokers and/or exposed to biomass, attending routine primary care visits completed a questionnaire and performed spirometry. COPD was defined as post-bronchodilator forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) < 0.70; asthma was defined as either prior asthma diagnosis or wheezing in the last 12 months plus reversibility (increase in post-bronchodilator FEV1 or FVC ≥200 mL and ≥12%); ACOS was defined using a combination of COPD with the two asthma definitions. Exacerbations in the past year among the subgroups were evaluated. Results One thousand seven hundred forty three individuals completed the questionnaire, 1540 performed acceptable spirometry, 309 had COPD, 231 had prior asthma diagnosis, and 78 asthma by wheezing + reversibility. ACOS prevalence in the total population (by post-bronchodilator FEV1/FVC < 0.70 plus asthma diagnosis) was 5.3 and 2.3% by post-bronchodilator FEV1/FVC < 0.70 plus wheezing + reversibility. In the obstructive population (asthma or COPD), prevalence rises to 17.9 and 9.9% by each definition, and to 26.5 and 11.3% in the COPD population. ACOS patients defined by post-bronchodilator FEV1/FVC < 0.7 plus wheezing + reversibility had the lowest lung function measurements. Exacerbations for ACOS showed a prevalence ratio of 2.68 and 2.20 (crude and adjusted, p < 0.05, respectively) (reference COPD). Conclusions ACOS prevalence in primary care varied according to definition used. ACOS by post-bronchodilator FEV1/FVC < 0.7 plus wheezing + reversibility represents a clinical phenotype with more frequent exacerbations, which is probably associated with a different management approach

ADAM9 Is a Novel Product of Polymorphonuclear Neutrophils:Regulation of Expression and Contributions to Extracellular Matrix Protein Degradation during Acute Lung Injury

A disintegrin and a metalloproteinase domain 9 (ADAM9) is known to be expressed by monocytes and macrophages. Herein, we report that ADAM9 is also a product of human and murine polymorphonuclear neutrophils (PMNs). ADAM9 is not synthesized de novo by circulating PMNs. Rather, ADAM9 protein is stored in the gelatinase and specific granules and the secretory vesicles of human PMNs. Unstimulated PMNs express minimal quantities of surface ADAM9, but activation of PMNs with degranulating agonists rapidly (within 15 min) increases PMN surface ADAM9 levels. Human PMNs produce small quantities of soluble forms of ADAM9 (sADAM9). Surprisingly, ADAM9 degrades several extracellular matrix (ECM) proteins including fibronectin, entactin, laminin, and insoluble elastin as potently as MMP-9. However, ADAM9 does not degrade types I, III, or IV collagen, or denatured collagens in vitro. To determine whether Adam9 regulates PMN recruitment or ECM protein turnover during inflammatory responses, we compared wild type (WT) and Adam9(−/−) mice in bacterial lipopolysaccharide (LPS)- and bleomycin-mediated acute lung injury (ALI). Adam9 lung levels increase 10-fold during LPS-mediated ALI in WT mice (due to increases in leukocyte-derived Adam9), but Adam9 does not regulate lung PMN (or macrophage) counts during ALI. Adam9 increases mortality, promotes lung injury, reduces lung compliance, and increases degradation of lung elastin during LPS- and/or bleomycin-mediated ALI. Adam9 does not regulate collagen accumulation in the bleomycin-treated lung. Thus, ADAM9 is expressed in an inducible fashion on PMN surfaces where it degrades some ECM proteins, and promotes alveolar-capillary barrier injury during ALI in mice

A Pilot Study Linking Endothelial Injury in Lungs and Kidneys in Chronic Obstructive Pulmonary Disease

Rationale: Patients with chronic obstructive pulmonary disease (COPD) frequently have albuminuria (indicative of renal endothelial cell injury) associated with hypoxemia.Objectives: To determine whether (1) cigarette smoke (CS)induced pulmonary and renal endothelial cell injury explains the association between albuminuria and COPD, (2) CS-induced albuminuria is linked to increases in the oxidative stress-advanced glycation end products (AGEs) receptor for AGEs (RAGE) pathway, and (3) enalapril (which has antioxidant properties) limits the progression of pulmonary and renal injury by reducing activation of the AGEs-RAGE pathway in endothelial cells in both organs.Methods: In 26 patients with COPD, 24 ever-smokers without COPD, 32 nonsmokers who underwent a renal biopsy or nephrectomy, and in CS-exposed mice, we assessed pathologic and ultrastructural renal lesions, and measured urinary albumin/creatinine ratios, tissue oxidative stress levels, and AGEs and RAGE levels in pulmonary and renal endothelial cells. The efficacy of enalapril on pulmonary and renal lesions was assessed in CS-exposed mice.Measurements and Main Results: Patients with COPD and/or CS-exposed mice had chronic renal injury, increased urinary albumin/creatinine ratios, and increased tissue oxidative stress and AGEs-RAGE levels in pulmonary and renal endothelial cells. Treating mice with enalapril attenuated CS-induced increases in urinary albumin/creatinine ratios, tissue oxidative stress levels, endothelial cell AGEs and RAGE levels, pulmonary and renal cell apoptosis, and the progression of chronic renal and pulmonary lesions.Conclusions: Patients with COPD and/or CS-exposed mice have pulmonary and renal endothelial cell injury linked to increased endothelial cell AGEs and RAGE levels. Albuminuria could identify patients with COPD in whom angiotensin-converting enzyme inhibitor therapy improves renal and lung function by reducing endothelial injury

MMP-8 levels in plasma do not correlate with decline in pulmonary function in IPF patients.

<p>Serial FVC and DLCO measurements of lung function were performed on IPF patients being evaluated for lung transplantation. Annual rates of decline in both measures were calculated as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097485#s2" target="_blank">Methods</a> and plotted against plasma MMP-8 levels measured using an ELISA. Correlations between MMP-8 plasma levels and absolute annual rate of decline in FVC (<b>A</b>) or DLCO (<b>B</b>) were calculated using the Spearman Rank Correlation Coefficient; 45 IPF patients were studied in <b>A</b> and <b>B</b>.</p

The lack of MMP-8 staining in type II alveolar epithelial cells in IPF lungs is not due to increased rates of apoptosis of these cells.

<p>Lung sections from a control and IPF patient were stained with a red fluorophore for a marker of type II alveolar epithelial cells (SP-C, left column) and with a green fluorophore for active caspase-3 (Casp3; middle column as a marker of apoptotic cells). Merged images (right) show apoptotic cells (stained green) in an area of severe fibrosis in the IPF lung, but these apoptotic cells are not ATII cells as assessed by the lack of co-localization of active caspase-3 and SP-C staining. There is no apoptosis in alveolar epithelial cells in the control lung, as expected. The images are representative of immuno-stained lung sections from 2 control subjects and 3 patients with IPF. Magnification is X 600.</p