Respiratory viral detection and small airway inflammation in lung tissue of patients with stable, mild COPD.

BACKGROUND: Viral respiratory tract infections are implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). In lung tissue specimens from patients with stable, mild COPD and from control smokers without airflow obstruction, we determined the prevalence and load of nucleic acid from common respiratory viruses and concomitant inflammation of small airways measuring less than 2-mm in diameter. METHODS: Frozen lung tissue obtained from patients with stable, mild COPD (n = 20) and control subjects (n = 20) underwent real-time quantitative PCR (qPCR) for 13 respiratory viruses, and quantitative histology for inflammation of small airways. The two groups were compared for viral prevalence and load, and airway inflammation. The relationship between viral load and airway inflammatory cells was also analyzed. RESULTS: Viral nucleic acid were detected in lung tissue of 18/40 (45.0%) of the individuals studied and included seven co-infections that were characterized by a "dominant virus" contributing to most of the total measured viral load. Lung tissue of COPD patients had a significantly higher prevalence of viral nucleic acid (particularly influenza A virus), and increased inflammation of small airways by macrophages and neutrophils versus controls. In qPCR-positive individuals, linear regression analysis showed a direct correlation between viral load and airway neutrophils, and between influenza A virus load and airway macrophages. CONCLUSION: The lung tissue of patients with stable, mild COPD has a higher prevalence and load of respiratory viruses versus non-obstructed control subjects, and increased inflammation of small airways. Respiratory viruses may represent potential targets in COPD patient management.

The lung tissue microbiome in chronic obstructive pulmonary disease.

RATIONALE: Based on surface brushings and bronchoalveolar lavage fluid, Hilty and coworkers demonstrated microbiomes in the human lung characteristic of asthma and chronic obstructive pulmonary disease (COPD), which have now been confirmed by others. OBJECTIVES: To extend these findings to human lung tissue samples. METHODS: DNA from lung tissue samples was obtained from nonsmokers (n = 8); smokers without COPD (n = 8); patients with very severe COPD (Global Initiative for COPD [GOLD] 4) (n = 8); and patients with cystic fibrosis (CF) (n = 8). The latter served as a positive control, with sterile water as a negative control. All bacterial community analyses were based on polymerase chain reaction amplifying 16S rRNA gene fragments. Total bacterial populations were measured by quantitative polymerase chain reaction and bacterial community composition was assessed by terminal restriction fragment length polymorphism analysis and pyrotag sequencing. MEASUREMENT AND MAIN RESULTS: Total bacterial populations within lung tissue were small (20-1,252 bacterial cells per 1,000 human cells) but greater in all four sample groups versus the negative control group (P < 0.001). Terminal restriction fragment length polymorphism analysis and sequencing distinguished three distinct bacterial community compositions: one common to the nonsmoker and smoker groups, a second to the GOLD 4 group, and the third to the CF-positive control group. Pyrotag sequencing identified greater than 1,400 unique bacterial sequences and showed an increase in the Firmicutes phylum in GOLD 4 patients versus all other groups (P < 0.003) attributable to an increase in the Lactobacillus genus (P < 0.0007). CONCLUSIONS: There is a detectable bacterial community within human lung tissue that changes in patients with very severe COPD.

Differential expression of tissue repair genes in the pathogenesis of chronic obstructive pulmonary disease.

RATIONALE: The airflow limitation that defines severity of chronic obstructive pulmonary disease (COPD) is caused by a combination of small airway obstruction and emphysematous lung destruction. OBJECTIVES: To examine the hypothesis that small airway obstructive and emphysematous destructive lesions are produced by differential expression of genes associated with tissue repair. METHODS: The expression of 54 genes associated with repair of repetitively damaged tissue was measured in 136 paired samples of small bronchioles and surrounding lung tissue separated by laser capture microdissection. These samples were collected from 63 patients at different levels of disease severity who required surgery for either lung cancer or lung transplantation for very severe COPD. Gene expression was measured by quantitative polymerase chain reaction in these paired samples and compared with the FEV(1) by linear regression analysis. MEASUREMENTS AND MAIN RESULTS: After corrections for false discovery rates, only 2 of 10 genes (serpin peptidase inhibitor/plasminogen activator inhibitor member 2 and matrix metalloproteinase [MMP] 10) increased, whereas 8 (MMP2, integrin-alpha1, vascular endothelial growth factor, a disintegrin and metallopeptidase domain 33, scatter factor/hepatocyte growth factor, tissue inhibitor of matrix metalloproteinase-2, fibronectin, and collagen 3alpha1) decreased in small airways in association with FEV(1). In contrast, 8/12 genes (early growth response factor 1, MMP1, MMP9, MMP10, plasminogen activator urokinase, plasminogen activator urokinase receptor, tumor necrosis factor, and IL13) increased and 4/12 (MMP2, tissue inhibitor of matrix metalloproteinase-1, collagen 1alpha1, and transforming growth factor-beta3) decreased in the surrounding lung tissue in association with progression of COPD. CONCLUSIONS: The progression of COPD is associated with the differential expression of a cluster of genes that favor the degradation of the tissue surrounding the small conducting airways.

A gene expression signature of emphysema-related lung destruction and its reversal by the tripeptide GHK.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease consisting of emphysema, small airway obstruction, and/or chronic bronchitis that results in significant loss of lung function over time. METHODS: In order to gain insights into the molecular pathways underlying progression of emphysema and explore computational strategies for identifying COPD therapeutics, we profiled gene expression in lung tissue samples obtained from regions within the same lung with varying amounts of emphysematous destruction from smokers with COPD (8 regions × 8 lungs = 64 samples). Regional emphysema severity was quantified in each tissue sample using the mean linear intercept (Lm) between alveolar walls from micro-CT scans. RESULTS: We identified 127 genes whose expression levels were significantly associated with regional emphysema severity while controlling for gene expression differences between individuals. Genes increasing in expression with increasing emphysematous destruction included those involved in inflammation, such as the B-cell receptor signaling pathway, while genes decreasing in expression were enriched in tissue repair processes, including the transforming growth factor beta (TGFß) pathway, actin organization, and integrin signaling. We found concordant differential expression of these emphysema severity-associated genes in four cross-sectional studies of COPD. Using the Connectivity Map, we identified GHK as a compound that can reverse the gene-expression signature associated with emphysematous destruction and induce expression patterns consistent with TGFß pathway activation. Treatment of human fibroblasts with GHK recapitulated TGFß-induced gene-expression patterns, led to the organization of the actin cytoskeleton, and elevated the expression of integrin ß1. Furthermore, addition of GHK or TGFß restored collagen I contraction and remodeling by fibroblasts derived from COPD lungs compared to fibroblasts from former smokers without COPD. CONCLUSIONS: These results demonstrate that gene-expression changes associated with regional emphysema severity within an individual's lung can provide insights into emphysema pathogenesis and identify novel therapeutic opportunities for this deadly disease. They also suggest the need for additional studies to examine the mechanisms by which TGFß and GHK each reverse the gene-expression signature of emphysematous destruction and the effects of this reversal on disease progression.

The relationship between respiratory viral loads and diagnosis in children presenting to a pediatric hospital emergency department.

BACKGROUND: respiratory viral infections account for a considerable proportion of pediatric emergency room visits. Illnesses range in severity from mild upper respiratory tract infections to serious lower respiratory tract infections (LRTI). The relationship between viral load and specific viruses to clinical diagnosis made by physicians in this setting is poorly understood. METHODS: we applied a real-time, quantitative polymerase chain reaction (qPCR) panel for 13 common respiratory viruses to 195 frozen, archival nasopharyngeal aspirate specimens obtained from symptomatic children ≤ 4 months of age presenting to the emergency room. Mean total viral load and number of viruses per archival nasopharyngeal aspirate specimen were compared between LRTI (n = 70) and non-LRTI (1 or more of upper respiratory tract infection, fever, or cough) (n = 125), as were yield and concordance of qPCR results to viral culture/direct fluorescence assay (DFA). RESULTS: children with LRTI had significantly increased total viral load and harbored more viruses than the non-LRTI group. Respiratory syncytial virus-A and -B were significantly associated with LRTI, and parainfluenza virus-1 with non-LRTI. Individual loads of parainfluenza virus-2 and human rhinovirus were increased in LRTI versus non-LRTI. Quantitative PCR yielded more viruses (including coinfections, where a "dominant virus" was typically identified) than viral culture/DFA and documented nucleic acid from pathogens not tested by culture/DFA including human rhinovirus; coronaviruses -OC43, -229E, and -NL63; and metapneumovirus. CONCLUSIONS: in symptomatic children presenting to the emergency room, total viral load is related to clinical diagnosis; specific viruses are associated with particular clinical diagnoses, and qPCR has a higher yield than other viral diagnostic methods.

Patterns of retention of particulate matter in lung tissues of patients with COPD: potential role in disease progression.

BACKGROUND: Particulate matter (PM) is present in lung tissues of smokers and urban dwellers. This study was designed to quantify the burden of PM in different lung tissues of subjects with COPD and determine its relationship to disease severity. METHODS: Surgical lung tissue samples from nonsmokers (control subjects) were compared with those from smokers with normal spirometry and subjects in the four other categories of the GOLD (Global Initiative for Obstructive Lung Disease) classification of COPD severity using quantitative histologic techniques. RESULTS: PM was present in the lung parenchyma, blood vessel walls, airways, lymphoid follicles, and alveolar macrophages. The total burden of PM (volume fraction [Vv]) in all tissues of the lung was higher in smokers than nonsmokers (P < .001) and also in smokers with airflow obstruction compared with the smokers with normal spirometry (P < .01). There was an incremental increase in total PM burden with increased COPD severity that peaked in GOLD II and then trended downward in GOLD III and IV COPD. This same pattern of PM retention was also observed in alveolar walls. The total burden of PM in lung tissues correlated with a decline in FEV(1)/FVC as well as pack-years smoking. mRNA expression of fibrinogen (γ chain) correlated with total lung burden of PM and burden of PM in lung parenchyma (r(2) = 0.22, P < .001). CONCLUSIONS: We conclude that retained PM is widely distributed in lung tissues of subjects with COPD and that cigarette smoke exposure and airflow obstruction are associated with retention of PM in lung tissues. We attribute the downward trend in PM burden in severe COPD to either less deposition and retention or selective removal of PM containing tissues by emphysematous destruction.

What drives the peripheral lung-remodeling process in chronic obstructive pulmonary disease?

The smaller airways (<2 mm in diameter) offer little resistance in normal lungs but become the major site of obstruction in chronic obstructive pulmonary disease (COPD). We examined bronchiolar remodeling in COPD by combining quantitative histology, micro-computed tomography (CT), and gene expression studies. Volumes of bronchiolar tissue, total collagen, collagen-1, and collagen-3 were measured in lung tissue from 52 patients with different levels of COPD severity. Micro-CT was used to measure the number and lumen area of terminal bronchioles in four lungs removed before lung transplantation and in four donor lungs that served as controls. Laser capture microdissection provided 136 paired samples of bronchiolar and surrounding lung tissue from 63 patients and the gene expression of a cluster of tissue repair genes was compared. This study shows that total bronchiolar tissue decreased with progression of COPD and was associated with a reduction in total collagen and relative increase in collagen-3 over collagen-1. The micro-CT studies showed a 10-fold reduction in terminal bronchiolar number and a 100-fold reduction in lumen area. Interestingly, most genes associated with tissue accumulation during repair decreased their expression in both airways and in the surrounding lung as FEV(1) declined, but eight genes previously associated with COPD increased expression in the surrounding lung tissue. Our study shows that small airway remodeling is associated with narrowing and obliteration of the terminal bronchioles that begins before emphysematous destruction in COPD and in relation to differential expression of tissue repair genes in the airways and surrounding lung.

Evaluation of small sample cDNA amplification for microdissected airway expression profiling in COPD.

Small airway obstruction and emphysematous destruction account for the airflow limitation that defines chronic obstructive pulmonary disease (COPD). While laser capture microdissection (LCM) allows gene expression studies in small airways separately from the surrounding parenchyma, tissue size limits the number of genes examined. The present study evaluates the Clontech SMART amplification to test the hypothesis that this amplification provides RNA in sufficient quantity and quality to evaluate large numbers of genes in airways < 2 mm diameter obtained by LCM. Commercial reference RNA was amplified 200-fold and the expression levels of 51 genes relative to the unamplified RNA had a correlation coefficient of 0.84. For two pairs of RNA preparations (commercial placenta versus commercial lung; lung sections prepared for LCM from GOLD 0 (at risk for COPD) versus GOLD 2 (moderate disease) patients linear regression of Delta Ct's (delta cycle thresholds) of unamplified versus amplified RNA gave correlation coefficients of R = 0.95. In RNA from microdissected small airways, expression patterns in all GOLD classes of COPD severity were very similar between unamplified and amplified RNA. We conclude that SMART amplification provides cDNA sufficient for studying large numbers of genes even in laser-captured small airways and this cDNA maintains the relative expression found in corresponding unamplified RNAs.