Series "matrix metalloproteinases in lung health and disease": Matrix metalloproteinases in COPD

Recent advances in α-1-antitrypsin deficiency-related lung disease

α-1-antitrypsin deficiency (A1ATD) is an under-recognized hereditary disorder associated with the premature onset of chronic obstructive pulmonary disease. There is considerable heterogeneity in the phenotypic expression of lung disease in A1ATD and the pathophysiology is complex, involving the interaction of multiple pathways. Other genetic factors that may contribute to emphysema risk in A1AT-deficient individuals are beginning to be identified. Methods of monitoring disease progression have evolved, including the use of computed tomography densitometry and biomarkers of disease activity. Progress in the development of novel treatment strategies continues, including the hope for a potential cure through the use of gene therapies. In this article, the authors review the recent advances in this field and outline potential future directions of research in A1ATD.

Matrix metalloproteinase-9 -1562C/T promoter polymorphism confers risk for COPD: a meta-analysis

BACKGROUND

The role of matrix metalloproteinase (MMP) gene polymorphisms in the development of chronic obstructive pulmonary disease (COPD) has been reported with inconsistent results. This meta-analysis was performed to assess the association of MMP-1 -1607G/GG and MMP-9 -1562C/T promoter polymorphisms with COPD susceptibility.

METHODS

Published case-control studies from Pubmed and China National Knowledge Infrastructure (CNKI) databases were retrieved. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated.

RESULTS

A total of fourteen case-control studies were included in this meta-analysis. Pooled effect size showed an association of MMP-9 -1562 C/T with the risk of COPD (dominant model: TT+CT vs CC; OR: 1.46; 95% CI: 1.02-2.08; p = 0.04). However, no correlation with COPD was revealed in MMP-1 -1607G/GG polymorphism. When stratified by ethnicity, results indicated MMP-1 -1607G/GG (recessive model: G/G vs G/GG+GG/GG; OR: 1.20; 95% CI: 1.01-1.44; p = 0.04) and MMP-9 -1562 C/T (dominant model; OR: 1.66; 95% CI: 1.01-2.71; p = 0.04) were correlated with COPD susceptibility among Caucasians and Asians respectively. According to source of controls, significant association of MMP-9 -1562 C/T (additive model: T vs C; OR:1.71, 95% CI: 1.42-2.07; p<0.00001, and dominant model; OR: 1.92; 95% CI: 1.34-2.76; p = 0.0004) with COPD susceptibility was revealed in the subgroup with smoker-based controls. However, in the aforementioned risk estimates, only the association of MMP-9 -1562 C/T (additive and dominant models) with the risk of COPD in the subgroup with smoker-based controls persisted significantly after Bonferroni correction for multiple testing. Moreover, after excluding the studies without Hardy-Weinberg equilibrium and/or with small sample size, the pooled results were robust and no publication bias was found in this study.

CONCLUSION

This meta-analysis suggests, when using healthy smokers as controls, MMP-9 -1562 C/T, but not MMP-1 -1607 G/GG polymorphism is associated with the risk of COPD.

Moraxella catarrhalis: from interactions with the host immune system to vaccine development

Moraxella catarrhalis is a human-restricted commensal that over the last two decades has developed into an emerging respiratory tract pathogen. The bacterial species is equipped with various adhesins to facilitate its colonization. Successful evasion of the human immune system is a prerequisite for Moraxella infection. This strategy involves induction of an excessive proinflammatory response, intervention of granulocyte recruitment to the infection site, activation of selected pattern recognition receptors and cellular adhesion molecules to counteract the host bacteriolytic attack, as well as, finally, reprogramming of antigen presenting cells. Host immunomodulator molecules are also exploited by Moraxella to aid in resistance against complement killing and host bactericidal molecules. Thus, breaking the basis of Moraxella immune evasion mechanisms is fundamental for future invention of effective therapy in controlling Moraxella infection.

Simultaneous up-regulation of matrix metalloproteinases 1, 2, 3, 7, 8, 9 and tissue inhibitors of metalloproteinases 1, 4 in serum of patients with chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVE

Matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) have been implicated in chronic obstructive pulmonary disease (COPD) pathogenesis. However, the majority of studies have focused on single MMP, and there is limited information on parallel expression of MMP and their antagonists TIMP. We, therefore, investigated the serum profile of MMP 1-3, 7-9, 12 and 13, and TIMP 1-4 in COPD patients.

METHODS

Serum MMP 1-3, 7-9, 12 and 13, and TIMP 1-4 were measured in 74 COPD patients and 20 control subjects by multiple microsphere technology.

RESULTS

MMP 1-3 and MMP 7-9 were elevated in COPD patients compared with control subjects (P= 0.001-0.043). The increased concentrations of MMP 1, 8 and 9 paralleled GOLD stage (P= 0.002-0.007). TIMP 1 and 4 concentrations were elevated in COPD (P < 0.001). MMP 1, 8 and 9, and TIMP 1 and 4 serum levels in COPD non-smokers were higher than in control non-smokers (P = 0.002-0.025). MMP 12 and 13 levels were undetectable in our serum samples.

CONCLUSIONS

This study provides further evidence for increased MMP 1, 7-9, and TIMP 1 serum levels in COPD, and demonstrates for the first time serum elevation of MMP 2 and 3, and TIMP 4. The finding that circulating TIMP 4 levels are increased in COPD and the observed relationship between serum levels of MMP 1, 8 and 9, and GOLD stage requires verification in an expanded patient cohort.

The role of macrophages in healing the wounded lung

Acute tissue injury is often considered in the context of a wound. The host response to wounding is an orchestrated series of events, the fundamentals of which are preserved across all multicellular organisms. In the human lung, there are a myriad of causes of injury, but only a limited number of consequences: complete resolution, persistent and/or overwhelming inflammation, a combination of resolution/remodelling with fibrosis or progressive fibrosis. In all cases where complete resolution does not occur, there is the potential for significant ongoing morbidity and ultimately death through respiratory failure. In this review, we consider the elements of injury, resolution and repair as they occur in the lung. We specifically focus on the role of the macrophage, long considered to have a pivotal role in regulating the host response to injury and tissue repair.