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

Extracellular Matrix Component Remodeling in Respiratory Diseases: What Has Been Found in Clinical and Experimental Studies?

Changes in extracellular matrix (ECM) components in the lungs are associated with the progression of respiratory diseases, such as asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory distress syndrome (ARDS). Experimental and clinical studies have revealed that structural changes in ECM components occur under chronic inflammatory conditions, and these changes are associated with impaired lung function. In bronchial asthma, elastic and collagen fiber remodeling, mostly in the airway walls, is associated with an increase in mucus secretion, leading to airway hyperreactivity. In COPD, changes in collagen subtypes I and III and elastin, interfere with the mechanical properties of the lungs, and are believed to play a pivotal role in decreased lung elasticity, during emphysema progression. In ARDS, interstitial edema is often accompanied by excessive deposition of fibronectin and collagen subtypes I and III, which can lead to respiratory failure in the intensive care unit. This review uses experimental models and human studies to describe how inflammatory conditions and ECM remodeling contribute to the loss of lung function in these respiratory diseases.

Fibre-based spectral ratio endomicroscopy for contrast enhancement of bacterial imaging and pulmonary autofluorescence

Fibre-based optical endomicroscopy (OEM) permits high resolution fluorescence microscopy in endoscopically accessible tissues. Fibred OEM has the potential to visualise pathologies targeted with fluorescent imaging probes and provide an in vivo in situ molecular pathology platform to augment disease understanding, diagnosis and stratification. Here we present an inexpensive widefield ratiometric fibred OEM system capable of enhancing the contrast between similar spectra of pathologically relevant fluorescent signals without the burden of complex spectral unmixing. As an exemplar, we demonstrate the potential of the platform to detect fluorescently labelled Gram-negative bacteria in the challenging environment of highly autofluorescent lung tissue in whole ex vivo human lungs.

Matrix Metalloproteinases in COPD and atherosclerosis with emphasis on the effects of smoking

Background

Matrix metalloproteinases (MMP´s) are known biomarkers of atherosclerosis. MMP´s are also involved in the pathophysiological processes underlying chronic obstructive pulmonary disease (COPD). Cigarette smoking plays an important role in both disease states and is also known to affect the concentration and activity of MMP´s systemically. Unfortunately, the epidemiological data concerning the value of MMP´s as biomarkers of COPD and atherosclerosis with special regards to smoking habits are limited.

Methods

450 middle-aged subjects with records of smoking habits and tobacco consumption were examined with comprehensive spirometry, carotid ultrasound examination and biomarker analysis of MMP-1, -3, -7, -10 and -12. Due to missing data 33 subjects were excluded.

Results

The remaining 417 participants were divided into 4 different groups. Group I (n = 157, no plaque and no COPD), group II (n = 136, plaque but no COPD), group III (n = 43, COPD but no plaque) and group IV (n = 81, plaque and COPD). Serum levels of MMP-1,-7,-10-12 were significantly influenced by smoking, and MMP-1, -3, -7 and-12 were elevated in subjects with COPD and carotid plaque. This remained statistically significant for MMP-1 and-12 after adjusting for traditional risk factors.

Conclusion

COPD and concomitant plaque in the carotid artery were associated with elevated levels of MMP-1 and -MMP-12 even when adjusting for risk factors. Further studies are needed to elucidate if these two MMP´s could be useful as biomarkers in a clinical setting. Smoking was associated with increased serum levels of MMP´s (except for MMP-3) and should be taken into account when interpreting serum MMP results.

Smooth muscle brain-derived neurotrophic factor contributes to airway hyperreactivity in a mouse model of allergic asthma

Recent studies have demonstrated an effect of neurotrophins, particularly brain-derived neurotrophic factor (BDNF), on airway contractility [ via increased airway smooth muscle (ASM) intracellular calcium [Ca2+]i] and remodeling (ASM proliferation and extracellular matrix formation) in the context of airway disease. In the present study, we examined the role of BDNF in allergen-induced airway inflammation using 2 transgenic models: 1) tropomyosin-related kinase B (TrkB) conditional knockin (TrkBKI) mice allowing for inducible, reversible disruption of BDNF receptor kinase activity by administration of 1NMPP1, a PP1 derivative, and 2) smooth muscle-specific BDNF knockout (BDNFfl/fl/SMMHC11Cre/0) mice. Adult mice were intranasally challenged with PBS or mixed allergen ( Alternaria alternata, Aspergillus fumigatus, house dust mite, and ovalbumin) for 4 wk. Our data show that administration of 1NMPP1 in TrkBKI mice during the 4-wk allergen challenge blunted airway hyperresponsiveness (AHR) and reduced fibronectin mRNA expression in ASM layers but did not reduce inflammation per se. Smooth muscle-specific deletion of BDNF reduced AHR and blunted airway fibrosis but did not significantly alter airway inflammation. Together, our novel data indicate that TrkB signaling is a key modulator of AHR and that smooth muscle-derived BDNF mediates these effects during allergic airway inflammation.-Britt, R. D., Jr., Thompson, M. A., Wicher, S. A., Manlove, L. J., Roesler, A., Fang, Y.-H., Roos, C., Smith, L., Miller, J. D., Pabelick, C. M., Prakash, Y. S. Smooth muscle brain-derived neurotrophic factor contributes to airway hyperreactivity in a mouse model of allergic asthma.

Pulmonary Manifestations of Predominantly Antibody Deficiencies

Predominantly antibody deficiencies (PADs) are the most frequent forms of primary immunodeficiency diseases (PIDs). Commonly accompanied with complications involving several body systems, immunoglobulin substitution therapy along with prophylactic antibiotics remained the cornerstone of treatment for PADs and related complications. Patients with respiratory complications should be prescribed an appropriate therapy as soon as possible and have to be adhering to more and longer medical therapies. Recent studies identified a gap for screening protocols to monitor respiratory manifestations in patients with PADs. In the present chapter, the pulmonary manifestations of different PADs for each have been discussed. The chapter is mainly focused on X-linked agammaglobulinemia, common variable immunodeficiency, activated PI3K-δ syndrome, LRBA deficiency, CD19 complex deficiencies, CD20 deficiency, other monogenic defects associated with hypogammaglobulinemia, immunoglobulin class switch recombination deficiencies affecting B-cells, transient hypogammaglobulinemia of infancy, and selective IgA deficiency.

Cigarette smoke-induced RANKL expression enhances MMP-9 production by alveolar macrophages

Background and purpose

Cigarette smoke (CS) induces alveolar destruction through overproduction of proteinases including matrix metalloproteinase (MMP)-9 by alveolar macrophages (AMs). Receptor activator of nuclear factor-κB ligand (RANKL) functions in immune regulation and cytokine secretion; whether it is involved in CS-induced MMP-9 expression is unknown. The purpose of our study was to investigate the expression and functional role of RANKL pathway in MMP-9 production pertaining to the pathogenesis of COPD.

Materials and methods

We first localized RANKL and its receptor RANK in the lungs of mice exposed to long-term CS exposure. Next, we studied RANKL and RANK expression under CS extract (CSE) stimulation in vitro. Lastly, we studied the in vitro biological function of RANKL in CS-induced production of MMP-9.

Results

Both RANKL and RANK were highly expressed in AMs in CS-exposed mice, but not in the control mice. In vitro, CSE increased the expressions of RANKL and RANK in macrophages. AMs responded to CSE and RANKL stimulation by overexpressing MMP-9, and CSE-induced MMP-9 expression was partly blocked by using monoclonal anti-RANKL antibody.

Conclusion

RANKL/RANK pathway mediates CS-induced MMP-9 expression in AMs, suggesting a novel mechanism for CS-associated emphysema.

Basophils trigger emphysema development in a murine model of COPD through IL-4-mediated generation of MMP-12-producing macrophages

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. It has generally been considered a non-Th2-type lung disorder, characterized by progressive airflow limitation with inflammation and emphysema, but its cellular and molecular mechanism remains ill defined, compared with that of asthma characterized by reversible airway obstruction. Here we show a previously unappreciated role for basophils at the initiation phase of emphysema formation in an elastase-induced murine model of COPD in that basophils represent less than 1% of lung-infiltrating cells. Intranasal elastase instillation elicited the recruitment of monocytes to the lung, followed by differentiation into interstitial macrophages (IMs) but rarely alveolar macrophages (AMs). Matrix metalloproteinase-12 (MMP-12) contributing to emphysema formation was highly expressed by IMs rather than AMs, in contrast to the prevailing assumption. Experiments using a series of genetically engineered mice suggested that basophil-derived IL-4, a Th2 cytokine, acted on lung-infiltrating monocytes to promote their differentiation into MMP-12-producing IMs that resulted in the destruction of alveolar walls and led to emphysema development. Indeed, mice deficient for IL-4 only in basophils failed to generate pathogenic MMP-12-producing IMs and hence develop emphysema. Thus, the basophil-derived IL-4/monocyte-derived IM/MMP-12 axis plays a crucial role in emphysema formation and therefore may be a potential target to slow down emphysema progression at the initiation phase of COPD.

Extracellular vesicle-associated MMPs: A modulator of the tissue microenvironment

Extracellular vesicles (EVs) are small particles that mediate intercellular communications in local and distant microenvironments. Due to their ability to carry bioactive materials such as proteins, nucleic acids, and lipids, and to transfer their cargo into target cells, EVs are thought to be crucial mediators under pathological and physiological conditions. Recent investigations of their protein profiles have revealed the presence of metalloproteinases such as matrix metalloproteinases (MMPs) in EVs from various cell types and body fluids. Although information regarding the biological and clinical significance of MMPs in EVs is still limited, EV-associated MMPs can alter EV cargo by ectodomain shedding, exerting proteolytic activity following uptake by target cells, or directly contributing to degradation of extracellular matrix proteins surrounding cells. This review focuses on recent findings regarding EV-associated MMPs, and we further discuss their potential involvement in human diseases.

Elevated circulating MMP-9 is linked to increased COPD exacerbation risk in SPIROMICS and COPDGene

BACKGROUND

Matrix metalloprotease 9 (MMP-9) is associated with inflammation and lung remodeling in chronic obstructive pulmonary disease (COPD). We hypothesized that elevated circulating MMP-9 represents a potentially novel biomarker that identifies a subset of individuals with COPD with an inflammatory phenotype who are at increased risk for acute exacerbation (AECOPD).

METHODS

We analyzed Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS) and Genetic Epidemiology of COPD (COPDGene) cohorts for which baseline and prospective data were available. Elevated MMP-9 was defined based on >95th percentile plasma values from control (non-COPD) sample in SPIROMICS. COPD subjects were classified as having elevated or nonelevated MMP-9. Logistic, Poisson, and Kaplan-Meier analyses were used to identify associations with prospective AECOPD in both cohorts.

RESULTS

Elevated MMP-9 was present in 95/1,053 (9%) of SPIROMICS and 41/140 (29%) of COPDGene participants with COPD. COPD subjects with elevated MMP-9 had a 13%-16% increased absolute risk for AECOPD and a higher median (interquartile range; IQR) annual AECOPD rate (0.33 [0-0.74] versus 0 [0-0.80] events/year and 0.9 [0.5-2] versus 0.5 [0-1.4] events/year for SPIROMICS and COPDGene, respectively). In adjusted models within each cohort, elevated MMP-9 was associated with increased odds (odds ratio [OR], 1.71; 95%CI, 1.00-2.90; and OR, 3.03; 95%CI, 1.02-9.01), frequency (incidence rate ratio [IRR], 1.45; 95%CI, 1.23-1.7; and IRR, 1.24; 95%CI, 1.03-1.49), and shorter time-to-first AECOPD (21.7 versus 31.7 months and 14 versus 21 months) in SPIROMICS and COPDGene, respectively.

CONCLUSIONS

Elevated MMP-9 was independently associated with AECOPD risk in 2 well-characterized COPD cohorts. These findings provide evidence for MMP-9 as a prognostic biomarker and potential therapeutic target in COPD.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01969344 (SPIROMICS) and NCT00608764 (COPDGene).

FUNDING

This work was funded by K08 HL123940 to JMW; R01HL124233 to PJC; Merit Review I01 CX000911 to JLC; R01 (R01HL102371, R01HL126596) and VA Merit (I01BX001756) to AG. SPIROMICS (Subpopulations and Intermediate Outcomes in COPD Study) is funded by contracts from the NHLBI (HHSN268200900013C, HHSN268200900014C,HHSN268200900015C HHSN268200900016C, HHSN268200900017C, HHSN268200900018C, HHSN268200900019C, and HHSN268200900020C) and a grant from the NIH/NHLBI (U01 HL137880), and supplemented by contributions made through the Foundation for the NIH and the COPD Foundation from AstraZeneca/MedImmune; Bayer; Bellerophon Therapeutics; Boehringer-Ingelheim Pharmaceuticals Inc.; Chiesi Farmaceutici; Forest Research Institute Inc.; GlaxoSmithKline; Grifols Therapeutics Inc.; Ikaria Inc.; Novartis Pharmaceuticals Corporation; Nycomed GmbH; ProterixBio; Regeneron Pharmaceuticals Inc.; Sanofi; Sunovion; Takeda Pharmaceutical Company; and Theravance Biopharma and Mylan. COPDGene is funded by the NHLBI (R01 HL089897 and R01 HL089856) and by the COPD Foundation through contributions made to an Industry Advisory Board composed of AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, Pfizer, Siemens, and Sunovion.

The Interplay Between Immune Response and Bacterial Infection in COPD: Focus Upon Non-typeable Haemophilus influenzae

Chronic obstructive pulmonary disease (COPD) is a debilitating respiratory disease and one of the leading causes of morbidity and mortality worldwide. It is characterized by persistent respiratory symptoms and airflow limitation due to abnormalities in the lower airway following consistent exposure to noxious particles or gases. Acute exacerbations of COPD (AECOPD) are characterized by increased cough, purulent sputum production, and dyspnea. The AECOPD is mostly associated with infection caused by common cold viruses or bacteria, or co-infections. Chronic and persistent infection by non-typeable Haemophilus influenzae (NTHi), a Gram-negative coccobacillus, contributes to almost half of the infective exacerbations caused by bacteria. This is supported by reports that NTHi is commonly isolated in the sputum from COPD patients during exacerbations. Persistent colonization of NTHi in the lower airway requires a plethora of phenotypic adaptation and virulent mechanisms that are developed over time to cope with changing environmental pressures in the airway such as host immuno-inflammatory response. Chronic inhalation of noxious irritants in COPD causes a changed balance in the lung microbiome, abnormal inflammatory response, and an impaired airway immune system. These conditions significantly provide an opportunistic platform for NTHi colonization and infection resulting in a "vicious circle." Episodes of large inflammation as the consequences of multiple interactions between airway immune cells and NTHi, accumulatively contribute to COPD exacerbations and may result in worsening of the clinical status. In this review, we discuss in detail the interplay and crosstalk between airway immune residents and NTHi, and their effect in AECOPD for better understanding of NTHi pathogenesis in COPD patients.

Blood and sputum protein biomarkers for chronic obstructive pulmonary disease (COPD)

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a heterogeneous set of disorders, characterized by airflow limitation, and reduced lung function. Despite increasing knowledge regarding its pathophysiology, there has been limited advancement in therapeutics and the current treatment strategy is symptom management and prevention of exacerbations. Areas covered: Biomarkers represent important tools for the implementation of precision medicine. As fundamental molecules of all living processes, proteins could provide crucial information about how genes interact with the environment. Proteomics studies could act as important tools in identifying reliable biomarkers to enable a more precise therapeutic approach. In this review, we will explore the most promising blood and sputum protein biomarkers in COPD that have been consistently reported in the literature. Expert commentary: Given the complexity of COPD, no single protein biomarker has been able to improve the outcomes of COPD patients. According to preliminary studies, precision medicine in COPD will likely require a combination of different proteins in a biomarker panel for clinical translation. With advancements in current mass spectrometry techniques, an enhancement in the identification of new biomarkers will be observed, and improvements in sequence database search can fill in potential gaps between biomarker discovery and patient care.

MMP-12 activates protease-activated receptor-1, upregulates placenta growth factor, and leads to pulmonary emphysema

Because of the expansion of aging and smoking populations, chronic obstructive pulmonary disease (COPD) is predicted to be the third leading cause of death worldwide in 2030. Therefore, it is pertinent to develop effective therapy to improve management for COPD. Cigarette smoke-mediated protease-antiprotease imbalance is a major pathogenic mechanism for COPD and results in massive pulmonary infiltration of neutrophils and macrophages, releasing excessive neutrophil elastase (NE) and matrix metalloproteinases (MMPs). Our previous studies indicated that placenta growth factor (PGF) and PGF-triggered downstream signaling molecules mediate NE-induced lung epithelial cell apoptosis, which is a major pathogenic mechanism for pulmonary emphysema. However, the relationship between MMP-directed COPD and PGF remains elusive. We hypothesize that MMPs may upregulate PGF expression and be involved in MMP-mediated pathogenesis of COPD. In this study, we demonstrate that only MMP-12 can increase the expression of PGF by increasing early-growth response protein 1 (Egr-1) level through the activation of protease-activated receptor 1 (PAR-1). The PGF-mediated downstream signaling molecules drive caspase-3 and caspase-9-dependent apoptosis in bronchial epithelial cells. Both the upregulation of PGF by MMP-12 and PGF downstream signaling molecules with pulmonary apoptosis and emphysema were also demonstrated in animals. Given these findings, we suggest that both human COPD-associated elastases, NE, and MMP-12, upregulate PGF expression and promote the progression of emphysema and COPD.

The effect of conjugated linoleic acid on oxidative stress and matrix metalloproteinases 2 and 9 in patients with COPD

Background

Natural antioxidants in foods may be used in prevention and treatment of oxidative stress and inflammation in COPD. Therefore, this study aimed to evaluate the effect of conjugated linoleic acid (CLA) supplement as natural antioxidants on oxidative stress levels, and MMP2 and MMP9 serum levels in COPD patients.

Materials and methods

This clinical trial study was conducted on 90 (supplement group=45 and control group=45) COPD patients in Ardabil city, Iran, in 2015. After obtaining written consent, general information was collected from each patient using a validated and reliable questionnaire. Supplement group received 3.2 g of CLA and those in the control group were given 3.2 g of placebo for 6 weeks on a daily basis. Fasting blood samples were taken from all of the patients for testing of malondialdehyde (MDA), MMP2, and MMP9 levels at the beginning and end of the study. Data were analyzed using Kolmogorov–Smirnov test, independent samples t-test, paired sample t-test, chi-square test, and ANOVA.

Results

There were no significant differences between the two groups with regard to mean age, smoking status, and serum level of MDA at the beginning of the study. In the supplement group, the serum level of MDA decreased significantly at the end of the 6th week compared to that in the beginning of the study (p=0.0004), while in the placebo group, the difference was found to be insignificant. The serum level of MMP9 decreased significantly in the supplement group, while in the placebo group its level increased significantly as compared to that at the beginning of the study (p<0.05). The serum levels of MMP2 indicated no significant differences between the two groups neither at the beginning nor at the end of the study.

Conclusion

These findings indicated that CLA supplementation may be helpful for COPD patients through inhibiting the production of oxidative stress and controlling MMP9 serum levels.

Mesenchymal stromal cells: a novel therapy for the treatment of chronic obstructive pulmonary disease?

COPD is characterised by tissue destruction and inflammation. Given the lack of curative treatments and the progressive nature of the disease, new treatments for COPD are highly relevant. In vitro cell culture and animal studies have demonstrated that mesenchymal stromal cells (MSCs) have the capacity to modify immune responses and to enhance tissue repair. These properties of MSCs provided a rationale to investigate their potential for treatment of a variety of diseases, including COPD. Preclinical models support the hypothesis that MSCs may have clinical efficacy in COPD. However, although clinical trials have demonstrated the safety of MSC treatment, thus far they have not provided evidence for MSC efficacy in the treatment of COPD. In this review, we discuss the rationale for MSC-based cell therapy in COPD, the main findings from in vitro and in vivo preclinical COPD model studies, clinical trials in patients with COPD and directions for further research.

Pentagalloyl glucose increases elastin deposition, decreases reactive oxygen species and matrix metalloproteinase activity in pulmonary fibroblasts under inflammatory conditions

Emphysema is characterized by degradation of lung alveoli that leads to poor airflow in lungs. Irreversible elastic fiber degradation by matrix metalloproteinases (MMPs) and reactive oxygen species (ROS) activity leads to loss of elasticity and drives the progression of this disease. We investigated if a polyphenol, pentagalloyl glucose (PGG) can increase elastin production in pulmonary fibroblasts. We also studied the effect of PGG treatment in reducing MMP activity and ROS levels in cells. We exposed rat pulmonary fibroblasts to two different types of inflammatory environments i.e., tumor necrosis factor-α (TNF-α) and cigarette smoke extract (CSE) to mimic the disease. Parameters like lysyl oxidase (LOX) and elastin gene expression, MMP-9 activity in the medium, lysyl oxidase (LOX) activity and ROS levels were studied to assess the effect of PGG on pulmonary fibroblasts. CSE inhibited lysyl oxidase (LOX) enzyme activity that resulted in a decreased elastin formation. Similarly, TNF-α treated cells showed less elastin in the cell layers. Both these agents caused increase in MMP activity and ROS levels in cells. However, when supplemented with PGG treatment along with these two inflammatory agents, we saw a significant increase in elastin deposition, reduction in both MMP activity and ROS levels. Thus PGG, which has anti-inflammatory, anti-oxidant properties coupled with its ability to aid in elastic fiber formation, can be a multifunctional drug to potentially arrest the progression of emphysema.

Mice overexpressing latent matrix metalloproteinase-2 develop lung emphysema after short-term exposure to cigarette smoke extract

Chronic obstructive pulmonary disease is the major growing cause of mortality and morbidity worldwide, and it is going to become the third most common cause of death by 2020. Chronic obstructive pulmonary disease is pathologically characterized by lung emphysema and small airway inflammation. Animal models are very important to get insights into the disease pathogenesis but current models of chronic obstructive pulmonary disease take a long time to develop. The need of a new model is compelling. In the present study we focus on the role of matrix metalloproteinases in the pathogenesis of chronic obstructive pulmonary disease and hypothesized that lung overexpression of latent matrix metalloproteinases-2 would allow the development of emphysema after short-term exposure to cigarette smoke extract inhalation. Human latent matrix metalloproteinases-2 transgenic mouse expressing high level of the protein in the lungs and wild type mouse were exposed to aerosolized cigarette smoke extract for two weeks. Transgenic mice showed significant lung emphysematous changes, increased infiltration of inflammatory cells and enhanced lung concentrations of inflammatory cytokines in the lungs compared to their wild type counterparts after inhalation of cigarette smoke extract. This novel mouse model will be a very useful tool for evaluating the mechanistic pathways and for development of novel therapies in cigarette smoke-associated lung emphysema.

Disrupting the Btk Pathway Suppresses COPD-Like Lung Alterations in Atherosclerosis Prone ApoE-/- Mice Following Regular Exposure to Cigarette Smoke

Chronic obstructive pulmonary disease (COPD) is associated with severe chronic inflammation that promotes irreversible tissue destruction. Moreover, the most broadly accepted cause of COPD is exposure to cigarette smoke. There is no effective cure and significantly, the mechanism behind the development and progression of this disease remains unknown. Our laboratory has demonstrated that Bruton’s tyrosine kinase (Btk) is a critical regulator of pro-inflammatory processes in the lungs and that Btk controls expression of matrix metalloproteinase-9 (MMP-9) in the alveolar compartment. For this study apolipoprotein E null (ApoE^−/−) mice were exposed to SHS to facilitate study in a COPD/atherosclerosis comorbidity model. We applied two types of treatments, animals received either a pharmacological inhibitor of Btk or MMP-9 specific siRNA to minimize MMP-9 expression in endothelial cells or neutrophils. We have shown that these treatments had a protective effect in the lung. We have noted a decrease in alveolar changes related to SHS induced inflammation in treated animals. In summary, we are presenting a novel concept in the field of COPD, i.e., that Btk may be a new drug target for this disease. Moreover, cell specific targeting of MMP-9 may also benefit patients affected by this disease.

Development of matrix metalloproteinase-targeted probes for lung inflammation detection with positron emission tomography

As matrix metalloproteinases (MMPs), especially MMP-9 and MMP-12 are involved in the pathological processes associated with chronic obstructive pulmonary disease (COPD), we developed a novel radiofluorinated probe, ¹⁸F-IPFP, for MMPs-targeted positron emission tomography (PET). ¹⁸F-IPFP was designed by iodination of MMP inhibitor to enhance the affinity, and labelled with a compact prosthetic agent, 4-nitrophenyl 2-¹⁸F-fluoropropionate (¹⁸F-NFP). As a result, IPFP demonstrated the highest affinity toward MMP-12 (IC₅₀ = 1.5 nM) among existing PET probes. A COPD model was employed by exposing mice to cigarette smoke and the expression levels of MMP-9 and MMP-12 were significantly increased in the lungs. Radioactivity accumulation in the lungs 90 min after administration of ¹⁸F-IPFP was 4× higher in COPD mice than normal mice, and 10× higher than in the heart, muscle, and blood. Ex vivo PET confirmed the radioactivity distribution in the tissues and autoradiography analysis demonstrated that accumulation differences in the lungs of COPD mice were 2× higher than those of normal mice. These results suggest that ¹⁸F-IPFP is a promising probe for pulmonary imaging and expected to be applied to various MMP-related diseases for early diagnosis, tracking of therapeutic effects, and new drug development in both preclinical and clinical applications.

Simvastatin Therapy and Bronchoalveolar Lavage Fluid Biomarkers in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a progressive disease underlain by airway inflammation. Despite trials with new generations of anti-inflammatory drugs to alleviate the disease burden, the effective curative treatment remains elusive. In this context, the aim of this study was to assess the influence of simvastatin, a leading member of the family of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, known to display anti-inflammatory and immunomodulatory activity, on symptoms and lung function, as well as the proportion of inflammatory cells, cytokines, proteolytic enzymes, and surfactant protein D (SP-D) content in bronchoalveolar lavage fluid (BALF) in COPD patients. There were 50 patients with moderate-to-severe airway obstructions included into the study, subdivided into simvastatin-treated (Zocor - MSD; 40 mg daily) and control simvastatin-untreated groups, other treatment being equal. Pulmonary functions tests and bronchofiberoscopy with BALF procedure were performed before and after 3-month-long treatment in both groups. The major finding was that simvastatin treatment caused a distinct increase in the airway content of SP-D. Further effects, albeit smaller in magnitude, consisted of reductions in the proportion of airway neutrophils and in MMP-9 content, all with a benefit of improved score in the disease activity assessment test. There were no appreciable changes noted in lung function or dyspnea perception, which could be ascribed to simvastatin treatment. We conclude that statin's anti-inflammatory and surfactant homeostasis preserving properties may offer promise as an adjunctive treatment in COPD patients. The SP-D content in BALF has a potential to become a marker of COPD inflammatory activity and treatment monitoring.

Biomarkers of collagen turnover are related to annual change in FEV1 in patients with chronic obstructive pulmonary disease within the ECLIPSE study

Background

Change in forced expiratory volume in one second (FEV₁) is important for defining severity of chronic obstructive pulmonary disease (COPD). Serological neoepitope markers of collagen turnover may predict rate of change in FEV₁.

Methods

One thousand COPD subjects from the observational, multicentre, three-year ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) study (NCT00292552, trial registration in February 2006) were included. Matrix metalloproteinase (MMP)-generated fragments of collagen type I, and type VI (C1M and C6M) were assessed in month six serum samples. A random-coefficient model with both a random intercept and a random slope was used to test the ability of the markers to predict post-dose bronchodilator FEV₁ (PD-FEV₁) change over two years adjusting for sex, age, BMI, smoking, bronchodilator reversibility, prior exacerbations, emphysema and chronic bronchitis status at baseline.

Results

Annual change of PD-FEV₁ was estimated from a linear model for the two-year study period. Serum C1M and C6M were independent predictors of lung function change (p = 0.007/0.005). Smoking, bronchodilator reversibility, plasma hsCRP and emphysema were also significant predictors. The effect estimate between annual change in PD-FEV₁ per one standard deviation (1SD) increase of C1M and C6M was +10.4 mL/yr. and +8.6 mL/yr. C1M, and C6M, had a significant association with baseline FEV₁.

Conclusion

We demonstrated that markers of tissue turnover were significantly associated with lung function change. These markers may function as prognostic biomarkers and possibly as efficacy biomarkers in clinical trials focusing on lung function change in COPD.

Trial registration

NCT00292552, Retrospectively registered, trial registration in February 2006.

Electronic supplementary material

The online version of this article (10.1186/s12890-017-0505-4) contains supplementary material, which is available to authorized users.

The CNGRC-GG-D(KLAKLAK)2 peptide induces a caspase-independent, Ca2+-dependent death in human leukemic myeloid cells by targeting surface aminopeptidase N/CD13

The CD13 antigen's binding site for the Asn-Gly-Arg (NGR) motif enables NGR-containing chemotherapeutic drugs to be delivered to CD13-positive tumours. Human CD13-positive acute myeloid leukemia (AML) cells proliferate abnormally and escape death. Here, we show that the CNGRC-GG-D(KLAKLAK)2 peptide induces death in AML cell lines (U937, THP-1, NB4, HL-60) and primary blood cells from AML patients. Cell death was characterized as a caspase-independent mechanism, without DNA fragmentation, but phosphatidylserine externalization and membrane disruption. Our results demonstrate in U937 cells that (i) the NGR-peptide triggers the loss of mitochondrial potential(ΔΨm) and generates superoxide anion (O2-), (ii) N-acetyl-L-cysteine (NAC) and extra/intracellular Ca2+ chelators (BAPTA) prevent both O2- production and cell death, (iii) the Ca2+-channel blocker nifedipine prevents cell death (indicating that Ca2+ influx is the initial death trigger), and (iv) BAPTA, but not NAC, prevents ΔΨm loss (suggesting O2- is a mitochondrial downstream effector). AML cell lines and primary blasts responding to the lethal action of NGR-peptide express promatrix metalloproteinase-12 (proMMP-12) and its substrate progranulin (an 88 kDa cell survival factor). A cell-free assay highlighted proMMP-12 activation by O2-. Accordingly, NGR-peptide's downregulation of 88 kDa progranulin protein was prevented by BAPTA and NAC. Conversely, AML blast resistance to NGR-peptide is associated with the expression of a distinct, 105 kDa progranulin isoform. These results indicate that CNGRC-GG-D(KLAKLAK)2 induces death in AML cells through the Ca2+-mitochondria-O2.-pathway, and support the link between proMMP-12 activation and progranulin cleavage during cell death. Our findings may have implications for the understanding of tumour biology and treatment.

Extracellular vesicles are integral and functional components of the extracellular matrix

Extracellular vesicles (EV) are small plasma membrane-derived particles released into the extracellular space by virtually all cell types. Recently, EV have received increased interest because of their capability to carry nucleic acids, proteins, lipids and signaling molecules and to transfer their cargo into the target cells. Less attention has been paid to their role in modifying the composition of the extracellular matrix (ECM), either directly or indirectly via regulating the ability of target cells to synthesize or degrade matrix molecules. Based on recent results, EV can be considered one of the structural and functional components of the ECM that participate in matrix organization, regulation of cells within it, and in determining the physical properties of soft connective tissues, bone, cartilage and dentin. This review addresses the relevance of EV as specific modulators of the ECM, such as during the assembly and disassembly of the molecular network, signaling through the ECM and formation of niches suitable for tissue regeneration, inflammation and tumor progression. Finally, we assess the potential of these aspects of EV biology to translational medicine.

A murine model of elastase- and cigarette smoke-induced emphysema

Objective:

To describe a murine model of emphysema induced by a combination of exposure to cigarette smoke (CS) and instillation of porcine pancreatic elastase (PPE).

Methods:

A total of 38 C57BL/6 mice were randomly divided into four groups: control (one intranasal instillation of 0.9% saline solution); PPE (two intranasal instillations of PPE); CS (CS exposure for 60 days); and CS + PPE (two intranasal instillations of PPE + CS exposure for 60 days). At the end of the experimental protocol, all animals were anesthetized and tracheostomized for calculation of respiratory mechanics parameters. Subsequently, all animals were euthanized and their lungs were removed for measurement of the mean linear intercept (Lm) and determination of the numbers of cells that were immunoreactive to macrophage (MAC)-2 antigen, matrix metalloproteinase (MMP)-12, and glycosylated 91-kDa glycoprotein (gp91phox) in the distal lung parenchyma and peribronchial region.

Results:

Although there were no differences among the four groups regarding the respiratory mechanics parameters assessed, there was an increase in the Lm in the CS + PPE group. The numbers of MAC-2-positive cells in the peribronchial region and distal lung parenchyma were higher in the CS + PPE group than in the other groups, as were the numbers of cells that were positive for MMP-12 and gp91phox, although only in the distal lung parenchyma.

Conclusions:

Our model of emphysema induced by a combination of PPE instillation and CS exposure results in a significant degree of parenchymal destruction in a shorter time frame than that employed in other models of CS-induced emphysema, reinforcing the importance of protease-antiprotease imbalance and oxidant-antioxidant imbalance in the pathogenesis of emphysema.

The Balance of Tissue Inhibitor of Metalloproteinase-1 and Matrix Metalloproteinase-9 in the Autoimmune Inner Ear Disease Patients

Tissue inhibitor of metalloproteinase-1 (TIMP-1) is a protein implicated in the control of inflammation in a number of autoimmune diseases. We hypothesized that the balance of TIMP-1 and matrix metalloproteinase-9 (MMP-9) may influence the control or perpetuation of inflammation in corticosteroid-responsive (RES) and corticosteroid-resistant (NR) autoimmune inner ear disease (AIED) patients. In the present study, we observed that plasma from AIED patients exhibited greater levels of TIMP-1 values compared with normal healthy controls. TIMP-1 abrogates lipopolysaccharide-mediated interleukin (IL)-1β release from peripheral blood mononuclear cells in a dose-dependent manner. RES AIED patients have higher basal TIMP-1 levels and produce more TIMP-1 in response to IL-1β. Conversely, consistent with our previous studies, we found that NR patients have higher basal MMP-9 levels and produce more MMP-9 levels in response to IL-1β.

Brain-derived neurotrophic factor and airway fibrosis in asthma

Airway remodeling in asthma driven by inflammation involves proliferation of epithelial cells and airway smooth muscle (ASM), as well as enhanced extracellular matrix (ECM) generation and deposition, i.e., fibrosis. Accordingly, understanding profibrotic mechanisms is important for developing novel therapeutic strategies in asthma. Recent studies, including our own, have suggested a role for locally produced growth factors such as brain-derived neurotrophic factor (BDNF) in mediating and modulating inflammation effects. In this study, we explored the profibrotic influence of BDNF in the context of asthma by examining expression, activity, and deposition of ECM proteins in primary ASM cells isolated from asthmatic vs. nonasthmatic patients. Basal BDNF expression and secretion, and levels of the high-affinity BDNF receptor TrkB, were higher in asthmatic ASM. Exogenous BDNF significantly increased ECM production and deposition, especially of collagen-1 and collagen-3 (less so fibronectin) and the activity of matrix metalloproteinases (MMP-2, MMP-9). Exposure to the proinflammatory cytokine TNFα significantly increased BDNF secretion, particularly in asthmatic ASM, whereas no significant changes were observed with IL-13. Chelation of BDNF using TrkB-Fc reversed TNFα-induced increase in ECM deposition. Conditioned media from asthmatic ASM enhanced ECM generation in nonasthmatic ASM, which was blunted by BDNF chelation. Inflammation-induced changes in MMP-2, MMP-9, and tissue inhibitor metalloproteinases (TIMP-1, TIMP-2) were reversed in the presence of TrkB-Fc. These novel data suggest ASM as an inflammation-sensitive source of BDNF within human airways, with autocrine effects on fibrosis relevant to asthma.

Human adipose-derived mesenchymal stem cell spheroids improve recovery in a mouse model of elastase-induced emphysema

Emphysema, a pathologic component of the chronic obstructive pulmonary disease, causes irreversible destruction of lung. Many researchers have reported that mesenchymal stem cells can regenerate lung tissue after emphysema. We evaluated if spheroid human adipose-derived mesenchymal stem cells (ASCs) showed greater regenerative effects than dissociated ASCs in mice with elastase-induced emphysema. ASCs were administered via an intrapleural route. Mice injected with spheroid ASCs showed improved regeneration of lung tissues, increased expression of growth factors such as fibroblast growth factor-2 (FGF2) and hepatocyte growth factor (HGF), and a reduction in proteases with an induction of protease inhibitors when compared with mice injected with dissociated ASCs. Our findings indicate that spheroid ASCs show better regeneration of lung tissues than dissociated ACSs in mice with elastase-induced emphysema.

Therapeutic Potential of Medicinal Plants and Their Constituents on Lung Inflammatory Disorders

Acute bronchitis and chronic obstructive pulmonary diseases (COPD) are essentially lung inflammatory disorders. Various plant extracts and their constituents showed therapeutic effects on several animal models of lung inflammation. These include coumarins, flavonoids, phenolics, iridoids, monoterpenes, diterpenes and triterpenoids. Some of them exerted inhibitory action mainly by inhibiting the mitogen-activated protein kinase pathway and nuclear transcription factor-κB activation. Especially, many flavonoid derivatives distinctly showed effectiveness on lung inflammation. In this review, the experimental data for plant extracts and their constituents showing therapeutic effectiveness on animal models of lung inflammation are summarized.

Identification of a unique gene expression signature in mercury and 2,3,7,8-tetrachlorodibenzo-p-dioxin co-exposed cells

Mercury (Hg) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are major environmental contaminants that commonly co-occur in the environment. Both Hg and TCDD are associated with a number of human diseases including cancers. While the individual toxicological effects of Hg and TCDD have been extensively investigated, studies on co-exposure are limited to a few genes and pathways. Therefore, a significant knowledge gap exists in the understanding of the deleterious effects of co-exposure to Hg and TCDD. Due to the prevalence of Hg and TCDD co-contamination in the environment and the major human health hazards they pose, it is important to obtain a fuller understanding of genome-wide effects of Hg and TCDD co-exposure. In this study, by performing a comprehensive transcriptomic analysis of human bronchial epithelial cells (BEAS-2B) exposed to Hg and TCDD individually and in combination, we have uncovered a subset of genes with altered expression only in the co-exposed cells. We also identified the additive as well as antagonistic effects of Hg and TCDD on gene expression. Moreover, we found that co-exposure impacted several biological and disease processes not affected by Hg or TCDD individually. Our studies show that the consequences of Hg and TCDD co-exposure on the transcriptional program and biological processes could be substantially different from single exposures, thus providing new insights into the co-exposure-specific pathogenic processes.

Biomarkers of extracellular matrix turnover are associated with emphysema and eosinophilic-bronchitis in COPD

Background

Chronic obstructive pulmonary disease (COPD) is characterized by airflow obstruction and loss of lung tissue mainly consisting of extracellular matrix (ECM). Three of the main ECM components are type I collagen, the main constituent in the interstitial matrix, type VI collagen, and elastin, the signature protein of the lungs. During pathological remodeling driven by inflammatory cells and proteases, fragments of these proteins are released into the bloodstream, where they may serve as biomarkers for disease phenotypes. The aim of this study was to investigate the lung ECM remodeling in healthy controls and COPD patients in the COPDGene study.

Methods

The COPDGene study recruited 10,300 COPD patients in 21 centers. A subset of 89 patients from one site (National Jewish Health), including 52 COPD patients, 12 never-smoker controls and 25 smokers without COPD controls, were studied for serum ECM biomarkers reflecting inflammation-driven type I and VI collagen breakdown (C1M and C6M, respectively), type VI collagen formation (Pro-C6), as well as elastin breakdown mediated by neutrophil elastase (EL-NE). Correlation of biomarkers with lung function, the SF-36 quality of life questionnaire, and other clinical characteristics was also performed.

Results

The circulating concentrations of biomarkers C6M, Pro-C6, and EL-NE were significantly elevated in COPD patients compared to never-smoking control patients (all p < 0.05). EL-NE was significantly elevated in emphysema patients compared to smoking controls (p < 0.05) and never-smoking controls (p < 0.005), by more than 250%. C1M was inversely associated with forced expiratory volume in 1 s (FEV₁) (r = −0.344, p = 0.001), as was EL-NE (r = −0.302, p = 0.004) and Pro-C6 (r = −0.259, p = 0.015). In the patients with COPD, Pro-C6 was correlated with percent predicted Forced Vital Capacity (FVC) (r = 0.281, p = 0.046) and quality of life using SF-36. C6M and Pro-C6, were positively correlated with blood eosinophil numbers in COPD patients (r = 0.382, p = 0.006 and r = 0.351, p = 0.012, respectively).

Conclusions

These data suggest that type VI collagen turnover and elastin degradation by neutrophil elastase are associated with COPD-induced inflammation (eosinophil-bronchitis) and emphysema. Serological assessment of type VI collagen and elastin turnover may assist in identification of phenotypes likely to be associated with progression and amenable to precision medicine for clinical trials.

Concomitant elevations of MMP-9, NGAL, proMMP-9/NGAL and neutrophil elastase in serum of smokers with chronic obstructive pulmonary disease

A growing body of evidence points towards smoking‐related phenotypic differences in chronic obstructive pulmonary disease (COPD). As COPD is associated with systemic inflammation, we determined whether smoking status is related to serum levels of matrix metalloproteinase‐9 (pro‐ and active MMP‐9), neutrophil gelatinase‐associated lipocalin (NGAL) and the proMMP‐9/NGAL complex in patients with COPD. Serum samples were collected in 100 stable‐phase COPD patients (82 smokers, 18 never‐smokers) and 28 healthy adults (21 smokers, 7 never‐smokers). Serum levels of studied factors were measured in ELISA. Our data provide the first evidence of simultaneously elevated serum levels of MMP‐9, NGAL and proMMP‐9/NGAL in COPD smokers. While the triad discriminated between smokers and non‐smokers in the COPD group, MMP‐9 and proMMP‐9/NGAL (but not NGAL) discriminated between smokers with and without COPD. Adjustment for age and smoking pack‐years did not alter the findings. Serum MMP‐9, NGAL and proMMP‐9/NGAL levels were not correlated with the GOLD stage or FEV1 decline. Furthermore, serum levels of neutrophil elastase (NE) and MMP‐3 (but not of IL‐6 and MMP‐12) were also higher in COPD smokers than in healthy smokers before and after adjustment for age and pack‐years. Among COPD smokers, levels of MMP‐9, NGAL and proMMP‐9/NGAL were positively correlated with NE (P < 0.0001) but not with the remaining factors. Gelatin zymography detected proMMP‐9 in serum samples of healthy and COPD smoking groups. Our results suggest that associated serum levels of proMMP‐9, NGAL, proMMP‐9/NGAL and NE may reflect the state of systemic inflammation in COPD related to cigarette smoking.

Eosinophilic and Neutrophilic Airway Inflammation in the Phenotyping of Mild-to-Moderate Asthma and Chronic Obstructive Pulmonary Disease

Asthma and chronic obstructive pulmonary disease (COPD) are heterogeneous diseases with different inflammatory phenotypes. Various inflammatory mediators play a role in these diseases. The aim of this study was to analyze the neutrophilic and eosinophilic airway and systemic inflammation as the phenotypic characterization of patients with asthma and COPD. Twenty-four patients with asthma and 33 patients with COPD were enrolled in the study. All the patients were in mild-to-moderate stage of disease, and none of them were treated with inhaled corticosteroids. Concentrations of IL-6, neutrophil elastase (NE), matrix metalloproteinase 9 (MMP-9), eosinophil cationic protein (ECP), and IL-33 and IL-17 in serum and induced sputum (IS) were measured by enzyme-linked immunosorbent assay (ELISA). The cellular composition of blood and IS was evaluated. Hierarchical clustering of patients was performed for the combination of selected clinical features and mediators. Asthma and COPD can be differentiated based on eosinophilic/neutrophilic systemic or airway inflammation with unsatisfactory efficiency. Hierarchical clustering of patients based on blood eosinophil percentage and clinical data revealed two asthma clusters differing in the number of positive skin prick tests and one COPD cluster with two subclusters characterized by low and high blood eosinophil concentrations. Clustering of patients according to IS measurements and clinical data showed two main clusters: pure asthma characterized by high eosinophil/atopy status and mixed asthma and COPD cluster with low eosinophil/atopy status. The neutrophilic phenotype of COPD was associated with more severe airway obstruction and hyperinflation.

Optical imaging of MMP-12 active form in inflammation and aneurysm

Matrix metalloproteinase (MMP)-12 plays a key role in the development of aneurysm. Like other members of MMP family, MMP-12 is produced as a proenzyme, mainly by macrophages, and undergoes proteolytic activation to generate an active form. Accordingly, molecular imaging of the MMP-12 active form can inform of the pathogenic process in aneurysm. Here, we developed a novel family of fluorescent probes based on a selective MMP-12 inhibitor, RXP470.1 to target the active form of MMP-12. These probes were stable in complex media and retained the high affinity and selectivity of RXP470.1 for MMP-12. Amongst these, probe 3 containing a zwitterionic fluorophore, ZW800-1, combined a favorable affinity profile toward MMP-12 and faster blood clearance. In vivo binding of probe 3 was observed in murine models of sterile inflammation and carotid aneurysm. Binding specificity was demonstrated using a non-binding homolog. Co-immunostaining localized MMP-12 probe binding to MMP-12 positive areas and F4/80 positive macrophages in aneurysm. In conclusion, the active form of MMP-12 can be detected by optical imaging using RXP470.1-based probes. This is a valuable adjunct for pathophysiology research, drug development, and potentially clinical applications.

MMP-8, MMP-9 and Neutrophil Elastase in Peripheral Blood and Exhaled Breath Condensate in COPD

Chronic obstructive pulmonary disease (COPD) is characterised by progressive and irreversible airflow limitation associated with chronic inflammation involving cytokines and metalloproteinases (MMPs). MMP-8, MMP-9 and neutrophil elastase (NE) are known to be implicated in COPD but the factors influencing activation and suppression remain unclear. This study aimed to compare MMP-8, MMP-9 and NE in the peripheral blood of COPD patients and controls and to likewise assess exhaled breath condensate (EBC) for these MMPs. Peripheral blood micro(mi)RNA139-5p levels, which may regulate MMPs in COPD, were also measured. Blood and EBC were collected from COPD patients (stable and during exacerbations) and healthy controls. Expression of mRNA for MMP-8, MMP-9, NE and miRNA-139-5p expression in peripheral blood mononuclear cells (PBMCs) was measured using qRT-PCR. MMP-8, MMP-9 and NE protein in plasma as well as MMP-8 and MMP-9 protein in EBC were analysed by enzyme-linked immunoassays. PBMCs from COPD patients showed greater expression of mRNA for MMP-8 (p = 0.0004), MMP-9 (p = 0.0023) and NE (p = 0.0019). PBMC expression of mRNA for NE was significantly higher in COPD exacerbations compared to stable cases (p < 0.05). Expression of mRNA for MMP-9 and NE correlated negatively with spirometry in patients (p < 0.05). Plasma from COPD patients showed greater levels of protein for MMP-8 (p = 0.003), MMP-9 (p = 0.046) and NE (p = 0.018). MMP-8 protein levels were lower in the EBC of COPD patients (p < 0.0001). In PBMCs, enhanced expression of mRNA for MMP-9 and NE is associated with COPD and may correlate with disease severity and exacerbations.

The inhibitor of semicarbazide-sensitive amine oxidase, PXS-4728A, ameliorates key features of chronic obstructive pulmonary disease in a mouse model

BACKGROUND AND PURPOSE

Chronic obstructive pulmonary disease (COPD) is a major cause of illness and death, often induced by cigarette smoking (CS). It is characterized by pulmonary inflammation and fibrosis that impairs lung function. Existing treatments aim to control symptoms but have low efficacy, and there are no broadly effective treatments. A new potential target is the ectoenzyme, semicarbazide-sensitive mono-amine oxidase (SSAO; also known as vascular adhesion protein-1). SSAO is elevated in smokers' serum and is a pro-inflammatory enzyme facilitating adhesion and transmigration of leukocytes from the vasculature to sites of inflammation.

EXPERIMENTAL APPROACH

PXS-4728A was developed as a low MW inhibitor of SSAO. A model of COPD induced by CS in mice reproduces key aspects of human COPD, including chronic airway inflammation, fibrosis and impaired lung function. This model was used to assess suppression of SSAO activity and amelioration of inflammation and other characteristic features of COPD.

KEY RESULTS

Treatment with PXS-4728A completely inhibited lung and systemic SSAO activity induced by acute and chronic CS-exposure. Daily oral treatment inhibited airway inflammation (immune cell influx and inflammatory factors) induced by acute CS-exposure. Therapeutic treatment during chronic CS-exposure, when the key features of experimental COPD develop and progress, substantially suppressed inflammatory cell influx and fibrosis in the airways and improved lung function.

CONCLUSIONS AND IMPLICATIONS

Treatment with a low MW inhibitor of SSAO, PXS-4728A, suppressed airway inflammation and fibrosis and improved lung function in experimental COPD, demonstrating the therapeutic potential of PXS-4728A for this debilitating disease.

Emerging concepts in smooth muscle contributions to airway structure and function: implications for health and disease

Airway structure and function are key aspects of normal lung development, growth, and aging, as well as of lung responses to the environment and the pathophysiology of important diseases such as asthma, chronic obstructive pulmonary disease, and fibrosis. In this regard, the contributions of airway smooth muscle (ASM) are both functional, in the context of airway contractility and relaxation, as well as synthetic, involving production and modulation of extracellular components, modulation of the local immune environment, cellular contribution to airway structure, and, finally, interactions with other airway cell types such as epithelium, fibroblasts, and nerves. These ASM contributions are now found to be critical in airway hyperresponsiveness and remodeling that occur in lung diseases. This review emphasizes established and recent discoveries that underline the central role of ASM and sets the stage for future research toward understanding how ASM plays a central role by being both upstream and downstream in the many interactive processes that determine airway structure and function in health and disease.

Characterization of a Mouse Model of Emphysema Induced by Multiple Instillations of Low-Dose Elastase

Many experimental models have been proposed to study the pathophysiological features of emphysema, as well as to search for new therapeutic approaches for acute or chronically injured lung parenchyma. We aimed to characterize an emphysema model induced by multiple instillations of elastase by tracking changes in inflammation, remodeling, and cardiac function after each instillation. Forty-eight C57BL/6 mice were randomly assigned across two groups. Emphysema (ELA) animals received 1, 2, 3, or 4 intratracheal instillations of pancreatic porcine elastase (PPE, 0.2 IU) with a 1-week interval between them. Controls (C) received saline following the same protocol. Before and after implementation of the protocol, animals underwent echocardiographic analysis. After the first instillation of PPE, the percentage of mononuclear cells in the lung parenchyma increased compared to C (p = 0.0001). The second instillation resulted in hyperinflated alveoli, increased mean linear intercept, and reduced elastic fiber content in lung parenchyma compared to C (p = 0.0197). Following the third instillation, neutrophils and collagen fiber content in alveolar septa and airways increased, whereas static lung elastance was reduced compared to C (p = 0.0094). After the fourth instillation, the percentage of M1 macrophages in lungs; levels of interleukin-1β (IL-1β), keratinocyte-derived chemokine, hepatocyte growth factor (HGF), and vascular endothelial growth factor (VEGF); and collagen fiber content in the pulmonary vessel wall were increased compared to C (p = 0.0096). At this time point, pulmonary arterial hypertension was apparent, with increased diastolic right ventricular wall thickness. In conclusion, the initial phase of emphysema was characterized by lung inflammation with predominance of mononuclear cells, whereas at the late stage, impairment of pulmonary and cardiovascular functions was observed. This model enables analysis of therapies at different time points during controlled progression of emphysema. Accordingly, early interventions could focus on the inflammatory process, while late interventions should focus on restoring cardiorespiratory function.

Gelatin Binding Proteins in Reproductive Physiology

In order to advance the assisted reproductive technologies used in animals and human beings, it is important to accumulate basic informations about underlying molecular mechanisms that shape the biological processes of reproduction. From within seminal plasma, proteins perform a wide variety of distinct functions that regulate major reproductive events such as fertilization. The ability of such proteins to bind and interact with different antagonistic ions and biomolecules such as polysaccharides, lipids, and other proteins present in the male and female reproductive tract define these capabilities. Over the last two decades, extensive work has been undertaken in an attempt to define the role of seminal plasma proteins, of which, Gelatin binding proteins (GBPs) represent a large family. GBPs comprise of known group of Bovine seminal plasma (BSP) protein family, matrix metallo proteinases (MMP 2 and MMP 9) and fibronectin, which have been widely studied. The presence of a type II repeat is a characteristic feature of GBPs, which is similar in structure to the fibronectin type II domain (fn2), which has ability to bind multiple ligands including gelatin, glycosaminoglycans, choline phospholipids, and lipoproteins. Two fn2 domains are present within the BSP protein family, while, three fn2 domains are found in gelatinases (MMP-2 and MMP9), and ELSPBP1 (Epididymosomes Transfer Epididymal Sperm Binding Protein 1) contains four long fn2 domains. For the most part BSP proteins are exclusively expressed in seminal vesicles although mBSPH1, mBSPH2 and hBSPH1 are all expressed in the epididymis. The expression of gelatinases has been demonstrated in several organs and tissues such as the prostate, testis, epididymis, ovary, human placenta, cervix and endometrial wall. This review intends to bring current updates on the role of GBPs in reproductive physiology to light, which may act as basis for future studies on GBPs.

Loss of Peripheral Tolerance in Emphysema. Phenotypes, Exacerbations, and Disease Progression

Heterogeneity in the development and progression of cigarette smoke-induced lung diseases strongly argues for a need to improve the clinical and phenotypic characterization of patients with chronic obstructive lung disease and emphysema. Smokers with emphysema are at a much higher risk for accelerated loss of lung function, increased cardiovascular morbidity, and development of lung cancer. Recent evidence in human translational studies and animal models suggests that emphysema is associated with activation of specialized antigen-presenting cells and that cigarette smoke can disrupt the induction of immune tolerance in the lungs. Quantitative assessment of cytokines expressed by autoreactive T lymphocytes in response to human lung elastin fragments has shown a strong positive correlation between T helper Type 1 (Th1) and Th17 cells' immune responses and emphysema. In search of factors that could reduce the threshold for induction of autoimmune inflammation, we have discovered that cleavage of complement protein 3 (C3) generates bioactive molecules (e.g., C3a) and activates lung antigen-presenting cells. The autocrine and paracrine function of C3a and its receptor are required in T cell-mediated inflammatory responses to cigarette smoke in both human and preclinical models of emphysema. Targeting upstream molecules that reduce the potential for generation of autoreactive T cells could lead to the development of novel therapeutics to prevent progression of emphysema in smokers.

Featured Article: Nanoenhanced matrix metalloproteinase-responsive delivery vehicles for disease resolution and imaging

The wide array of proteases, including matrix metalloproteinases, produced in response to many pathogenic insults, confers a unique proteolytic signature which is often disease specific and provides a potential therapeutic target for drug delivery. Here we propose the use of collagen-based nanoenhanced matrix metalloproteinase-responsive delivery vehicles that display matrix metalloproteinase-specific degradation in diverse in vitro models of proteolysis. We demonstrate that collagen particles comprised of protease substrates (primarily collagen) can be made of uniform size and loaded efficiently with assorted cargo including fluorescently labeled mesoporous silica, magnetic nanoparticles, proteins and antioxidants. We also demonstrate that pathologic concentrations of proteases produced in situ or in vitro display protease-specific cargo release. Additionally, we show that the collagen-based particles display bright fluorescence when loaded with a fluorophore, and have the potential to be used as vehicles for targeted delivery of drugs or imaging agents to regions of high proteolytic activity.

Matrix Metalloproteinase-Targeted Imaging of Lung Inflammation and Remodeling

Imaging techniques for detection of molecular and cellular processes that precede or accompany lung diseases are needed. Matrix metalloproteinases (MMPs) play key roles in the development of pulmonary pathology. The objective of this study was to investigate the feasibility of in vivo MMP-targeted molecular imaging for detection of lung inflammation and remodeling.

METHODS

Lung-specific IL-13 transgenic (Club cell 10-kDa protein [CC10]-IL-13 Tg) mice and wild-type littermates were used in this study. Lung structure, gene expression, and MMP activity were assessed by histology, real-time reverse transcription polymerase chain reaction, Western blotting, and zymography. MMP activation was imaged by in vivo small-animal SPECT/CT followed by ex vivo planar imaging. Signal specificity was addressed using a control tracer. The correlation between in vivo MMP signal and gene expression was addressed.

RESULTS

CC10-IL-13 Tg mice developed considerable pulmonary tissue remodeling and inflammation. CD68, MMP-12, and MMP-13 were significantly higher in CC10-IL-13 Tg lungs. On in vivo small-animal SPECT/CT and ex vivo planar images, the MMP signal was significantly higher in the lungs of CC10-IL-13 Tg mice than wild-type animals. Furthermore, a nonbinding analog tracer showed significantly lower accumulation in CC10-IL-13 Tg lungs relative to the specific tracer. There was a significant correlation between small-animal SPECT/CT-derived MMP signal and CD68 expression in the lungs (r = 0.70, P < 0.01).

CONCLUSION

Small-animal SPECT/CT-based MMP-targeted imaging of the lungs is feasible and reflects pulmonary inflammation. If validated in humans, molecular imaging of inflammation and remodeling can potentially help early diagnosis and monitoring of the effects of therapeutic interventions in pulmonary diseases.

Matrix Metalloproteinases in Non-Neoplastic Disorders

The matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases belonging to the metzincin superfamily. There are at least 23 members of MMPs ever reported in human, and they and their substrates are widely expressed in many tissues. Recent growing evidence has established that MMP not only can degrade a variety of components of extracellular matrix, but also can cleave and activate various non-matrix proteins, including cytokines, chemokines and growth factors, contributing to both physiological and pathological processes. In normal conditions, MMP expression and activity are tightly regulated via interactions between their activators and inhibitors. Imbalance among these factors, however, results in dysregulated MMP activity, which causes tissue destruction and functional alteration or local inflammation, leading to the development of diverse diseases, such as cardiovascular disease, arthritis, neurodegenerative disease, as well as cancer. This article focuses on the accumulated evidence supporting a wide range of roles of MMPs in various non-neoplastic diseases and provides an outlook on the therapeutic potential of inhibiting MMP action.

Pathogenesis of COPD (Persistence of Airway Inflammation): Why Does Airway Inflammation Persist After Cessation of Smoking?

The structural features of airways in patients with COPD are airway wall inflammation, fibrosis, muscle hypertrophy, and goblet cell metaplasia. These structural cellular changes contribute to mucus hypersecretion and destruction of the alveolar walls and a decline in forced expiratory volume in one second (FEV₁). At the cellular level, macrophages, T lymphocytes, and neutrophils, driven by cytokines including interleukin-8 (IL-8), gather on the airways. The main cause of COPD inflammation is cigarette smoke. Smoke causes an increase in the secretion of matrix metalloproteinase (MMPs) and neutrophilic elastase from epithelial cells and neutrophils, which are responsible for mucin production and destruction of the lung. Initially, cigarette smoke influences the expression of pattern recognition receptors (PRRs) including Toll-like receptors (TLRs), the intracellularly located nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs), retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), and receptors for advanced glycation end products (RAGE) on lung epithelial cells, endothelial cells, and leukocytes in the lung. These actions bring about the production of cytokines and activation of inflammatory cells, leading to production of MMPs and neutrophilic elastase. The inflammatory changes persist for several months and years after smoking cessation and are sometimes irreversible. Damage-associated molecular patterns (DAMPs) released from dying cells after cigarette smoking increase the number of apoptotic cells, suppress efferocytosis, induce hypoxia and oxidative stress, and prolong the inflammatory changes, even after smoking cessation. Viral and bacterial infections of the respiratory tract then fortify these inflammatory responses. Exacerbations of COPD then worsen the deterioration of COPD.