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Genes related to emphysema are enriched for ubiquitination pathways

ABSTRACT: Increased small airway resistance and decreased lung elasticity contribute to the airflow limitation in chronic obstructive pulmonary disease (COPD). The lesion that corresponds to loss of lung elasticity is emphysema; the small airway obstruction is due to inflammatory narrowing and obliteration. Despite their convergence in altered physiology, different mechanisms contribute to these processes. The relationships between gene expression and these specific phenotypes may be more revealing than comparison with lung function. We measured the ratio of alveolar surface area to lung volume (SA/V) in lung tissue from 43 smokers. Two samples from 21 subjects, in which SA/V differed by > 49 cm2/mL were profiled to select genes whose expression correlated with SA/V. The level of expression of 181 transcripts was related to SA/V ( p< 0.05). The relationship between expression of these transcripts and SA/V was tested in the 22 remaining subjects as a replication. Thirty of the 181 genes remained significantly associated with SA/V (P<0.05) and the direction of association was the same in 164/181. Pathway and network analysis revealed enrichment of genes involved in protein ubiquitination, and western blotting showed altered expression of genes involved in protein ubiquitination in obstructed individuals. These data implicate modified protein ubiquitination and degradation as a potentially important pathway in the pathogenesis of emphysema. Raw data not available for this study

ORGANISM(S): Homo sapiens

PROVIDER: GSE63073 | GEO | 2014/11/07

SECONDARY ACCESSION(S): PRJNA266547

REPOSITORIES: GEO

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Project description:Progressive decline in lung function is a hallmark of chronic obstructive pulmonary disease (COPD). Although airway dysbiosis occurs in COPD, whether it contributes to disease progression remains unknown. Here, through a longitudinal analysis on 181 COPD individuals from two large cohorts involving four UK clinical centers, we showed that baseline airway dysbiosis, characterized by enrichment of opportunistic pathogenic taxa, was associated with rapid forced expiratory volume in one second (FEV1) decline over two years. Co-presence of Moraxella, Staphylococcus and Stenotrophomonas was associated with an accelerated FEV1 decline by 139.7 mL/year. The dysbiosis was associated with exacerbation-related FEV1 fall and sudden FEV1 fall at clinical stability, two critical events contributing to long-term FEV1 decline. The microbiota association with FEV1 decline was validated in a third, independent cohort in China. Human multi-omics, murine and cellular mechanistic studies showed that chronic airway colonization of Staphylococcus aureus promoted lung function decline through producing homocysteine, which elicited an apoptosis-to-NETosis shift in neutrophils toward persistent inflammation via AKT1-S100A8/A9 axis. Prophylactic and therapeutic depletion of S. aureus via bacteriophage restored lung function in emphysema mice. These results provide a fresh approach to slow COPD progression by targeting the airway microbiome. Linked studies:UPLC-MS/MS assays of human samples are reported in this study.UPLC-MS/MS assays of murine samples are reported in <a href='https://www.ebi.ac.uk/metabolights/MTBLS6894' rel='noopener noreferrer' target='_blank'>MTBLS6894</a>.UPLC-MS/MS assays of original cohort human samples are reported in <a href='https://www.ebi.ac.uk/metabolights/MTBLS4017' rel='noopener noreferrer' target='_blank'>MTBLS4017</a>.

Project description:Background: Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease characterized by varying degrees of emphysematous lung destruction and small airway disease, each with distinct effects on clinical outcomes. There is little known about how microRNAs contribute specifically to the emphysema phenotype. We examined how microRNA expression is altered with regional emphysema severity within the lung and how these microRNAs regulate disease-associated gene-expression networks. Results: We profiled microRNAs in different regions in the lung with varying degrees of emphysema from 6 smokers with COPD and 2 controls (8 regions x 8 lungs = 64 samples). 63 microRNAs (p<0.05) were altered with regional emphysema severity as quantified by mean linear intercept (Lm). MicroRNA and gene expression data were then integrated in the same samples. A subset of microRNAs, including miR-638, miR-30c, and miR-181d, correlated with many of their predicted gene targets, suggesting a role in regulating the gene networks that underlie emphysematous lung destruction. Modulating miR-638 expression in primary human lung fibroblasts recapitulated the alterations in its targeted gene-expression network associated with emphysema progression. Pathway analysis revealed that genes involved in oxidative stress and accelerated aging were affected by miR-638 knock-down in fibroblasts. Many miR-638 gene targets in these pathways were amongst those negatively correlated with miR-638 expression in emphysematous lung tissue. Conclusions: Our findings demonstrate that microRNAs are altered with regional emphysema severity and modulate disease-associated gene expression networks. Furthermore, miR-638 may regulate gene expression associated with the oxidative stress response and aging in emphysematous lung tissue and fibroblasts. Paired samples were obtained from 8 regions at regular intervals between the apex and base of each explanted lung from six patients with severe COPD and two donors. The degree of emphysematous destruction was quantified in one sample from each region by mean linear intercept (Lm), while microRNA expression was profiled in the adjacent sample from the same region using the NCode Version 3 microRNA microarrays (Invitrogen, Carlsbad, CA). After quality control 60 samples were used for the analysis.

Project description:The glutathione S-transferase (GST) gene family codes for enzymes that detoxify xenobiotics by catalyzing the conjugation of xenobiotics to glutathione. Based on reports that inherited copy number variations (CNV) in the genome modulate some GST expression levels and with the knowledge that cigarette smoke contains >3000 xenobiotics, and that the small airway epithelium and alveolar macrophages are involved early in the pathogensis of smoking-induced lung disease, we asked: do germline CNVs modulate GST expression level in the small airway epithelium and alveolar macrophages? Affymetrix HG U133 Plus 2.0 microarrays were used to survey GST gene expression in the small airway epithelium and alveolar macrophages obtained by bronchoscopic brushings from current smokers (n=35) and nonsmokers (n=35). The CNV genotypes of these 70 subjects were determined by Affymetrix Human SNP array 5.0 chips. Sixteen % of subjects had deletions of both GSTM1 alleles. These deletions were associated with reduced GSTM1 mRNA levels in both the small airway epithelium (p<10-7) and alveolar macrophages (p<0.05). Thirty % of subjects had homozygous deletions of GSTT1 with concomitant reduced mRNA levels in both small airway epithelium and alveolar macrophages (p<10-7). In contrast, genes flanking the CNV regions of both GST genes showed no difference in expression level among subjects with and without the GST deletions (p>0.3). Interestingly, GSTT2B, a duplicate gene of GSTT2, exhibited homozygous deletion in blood in 27% of subjects and was not expressed in small airway epithelium in the remainder of subjects but was expressed in alveolar macrophages of heterozygotes and wild type subjects, proportionate to genotype (p<10-3). These data demonstrate that highly prevalent CNV deletions of genes critical to ameliorating smoking-associated xenobiotic-induced damage in the lung can result in significant modulation of the gene expression levels, with the linear relationship of genotype to expression level suggesting minimal compensation of gene expression levels in heterozygotes consistent with GST polymorphisms playing a role in the risk for development of smoking-induced lung disease.

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Genes related to emphysema are enriched for ubiquitination pathways

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