Matrix metalloproteinase-1 polymorphism (-1607G) and disease severity in non-cystic fibrosis bronchiectasis in Taiwan

Pathophysiology and genomics of bronchiectasis

Bronchiectasis is a complex and heterogeneous inflammatory chronic respiratory disease with an unknown cause in around 30-40% of patients. The presence of airway infection together with chronic inflammation, airway mucociliary dysfunction and lung damage are key components of the vicious vortex model that better describes its pathophysiology. Although bronchiectasis research has significantly increased over the past years and different endotypes have been identified, there are still major gaps in the understanding of the pathophysiology. Genomic approaches may help to identify new endotypes, as has been shown in other chronic airway diseases, such as COPD.Different studies have started to work in this direction, and significant contributions to the understanding of the microbiome and proteome diversity have been made in bronchiectasis in recent years. However, the systematic application of omics approaches to identify new molecular insights into the pathophysiology of bronchiectasis (endotypes) is still limited compared with other respiratory diseases.Given the complexity and diversity of these technologies, this review describes the key components of the pathophysiology of bronchiectasis and how genomics can be applied to increase our knowledge, including the study of new techniques such as proteomics, metabolomics and epigenomics. Furthermore, we propose that the novel concept of trained innate immunity, which is driven by microbiome exposures leading to epigenetic modifications, can complement our current understanding of the vicious vortex. Finally, we discuss the challenges, opportunities and implications of genomics application in clinical practice for better patient stratification into new therapies.

Epithelial-Mesenchymal Transition Mechanisms in Chronic Airway Diseases: A Common Process to Target?

Epithelial-to-mesenchymal transition (EMT) is a reversible process, in which epithelial cells lose their epithelial traits and acquire a mesenchymal phenotype. This transformation has been described in different lung diseases, such as lung cancer, interstitial lung diseases, asthma, chronic obstructive pulmonary disease and other muco-obstructive lung diseases, such as cystic fibrosis and non-cystic fibrosis bronchiectasis. The exaggerated chronic inflammation typical of these pulmonary diseases can induce molecular reprogramming with subsequent self-sustaining aberrant and excessive profibrotic tissue repair. Over time this process leads to structural changes with progressive organ dysfunction and lung function impairment. Although having common signalling pathways, specific triggers and regulation mechanisms might be present in each disease. This review aims to describe the various mechanisms associated with fibrotic changes and airway remodelling involved in chronic airway diseases. Having better knowledge of the mechanisms underlying the EMT process may help us to identify specific targets and thus lead to the development of novel therapeutic strategies to prevent or limit the onset of irreversible structural changes.

Impacts of Nontuberculous Mycobacteria Isolates in Non-cystic Fibrosis Bronchiectasis: A 16-Year Cohort Study in Taiwan

Background

The prevalence of nontuberculous mycobacteria (NTM) in patients with chronic respiratory disease has increased. The implication of NTM in non-CF bronchiectasis remained controversial. This study investigated the impact of NTM in non-CF bronchiectasis in Taiwan.

Methods

Clinical manifestation, imaging, and microbiological data were retrieved from the Chang Gung Research Database, the largest electronic medical record-based database in Taiwan. Patients with bronchiectasis during 2001–2016 were included. Cox proportional hazard model was employed to compare outcomes between patients with negative and positive NTM isolates after 1:1 propensity score matching.

Results

A total of 19,647 non-CF bronchiectasis patients were enrolled and 11,492 patients were eligible for analysis after exclusion screening. Finally, patients with negative and positive NTM isolates—650 each—were analyzed after propensity score matching. The patients with negative NTM isolates were divided into three groups: Pseudomonas aeruginosa isolates (n = 53); fungus isolates (n = 26); and concomitant P. aeruginosa and fungus isolates (n = 8). The patients with positive NTM isolates were divided into five groups: single NTM isolate (n = 458); multiple NTM isolates (n = 60); concomitant NTM and P. aeruginosa isolates (n = 89); concomitant NTM and fungus isolates (n = 33); and concomitant NTM, P. aeruginosa, and fungus isolates (n = 10). Patients with P. aeruginosa isolates; concomitant NTM and P. aeruginosa isolates; concomitant NTM, P. aeruginosa, and fungus isolates had independently associated with respiratory failure and death. Patients with single or multiple NTM isolates were not related to ventilator use, but both were independent risk factor for mortality.

Conclusion

NTM, either combined with P. aeruginosa or fungus, exhibited more frequent exacerbations in non-CF bronchiectasis patients. Moreover, NTM predicted mortality in non-CF bronchiectasis patients and were also correlated to respiratory failure while concomitantly isolated with P. aeruginosa and fungus.

Predicting mortality in non-cystic fibrosis bronchiectasis patients using distance-saturation product

BACKGROUND

The bronchiectasis severity index (BSI) and FACED score are currently used in predicting outcomes of non-cystic fibrosis bronchiectasis (NCFB). Distance-saturation product (DSP), the product of distance walked, and lowest oxygen saturation during the 6-min walk test showed strong predictive power of mortality in non-CF bronchiectasis patients. This study aimed to compare the efficacy of these scores and DSP in predicting mortality.

METHODS AND PATIENTS

Our retrospective study included NCFB patients from January 2004 to December 2017. We recorded the basic data, pulmonary function, radiologic studies, sputum culture results, acute exacerbations (AE), emergency department (ED) visits, hospitalization, and mortality.

RESULTS

A total 130 NCFB patients were analysed. The mean BSI score, FACED score, and DSP were 8.8 ± 4.9, 3.4 ± 1.7, and 413.1 ± 101.5 m%, respectively. BSI and FACED scores had comparable predictive power for AE (p=.011; p=.010, respectively). The BSI score demonstrated a significant correlation with ED visits (p=.0003). There were 12 deaths. Patients were stratified using a DSP cut-off value of 345 m% according to the best area under receiver operator characteristic curve (AUC) value in mortality. DSP was not correlated with AE and ED visits. BSI, FACED scores, and DSP demonstrated statistically significant correlations with hospitalization (p<.0001; p<.0001; p=.0007, respectively). The AUC for overall mortality was similar for BSI, FACED score, and DSP (0.80 versus 0.85, p=.491; 0.85 versus 0.83, p=.831).

CONCLUSION

DSP had comparable predictive power for mortality as the well-validated BSI and FACED scores and is relatively easy to use in clinical practice.KEY MESSAGEDistance-saturation product (DSP) comprised with the product of distance walked, and lowest oxygen saturation during the 6-min walk test, which is common used in clinical practice.DSP demonstrated strong and comparable predictive power of mortality as the well-validated BSI and FACED scores in non-CF bronchiectasis patients.

An inflammatory triangle in Sarcoidosis: PPAR-γ, immune microenvironment, and inflammation

INTRODUCTION

Sarcoidosis is an inflammatory disorder characterized by granuloma formation in several organs. Sarcoidosis patients experience higher inflammatory responses resulting in pulmonary fibrosis. Although the precise mechanisms have not been well elucidated, the relationship between the immune system activation and inflammatory status is pivotal in the pathogenesis of sarcoidosis.

AREAS COVERED

Peroxisome proliferator-activated receptor (PPAR) includes the transcription factors involved in cell metabolism, proliferation, and immune response. In the alveolar macrophages of patients with sarcoidosis, the reduced activity and a decreased level of PPAR-γ have been shown. In this study, we discuss how reducing the level of PPAR-γ could lead to increased inflammation and immune responses in patients with sarcoidosis.

EXPERT OPINION

Lack of PPAR-γ may contribute to the development of a suitable milieu for the formation of immune-associated pulmonary granuloma. Reduced levels of PPAR-γ in sarcoidosis could result from over-activation of the immune system and elevated inflammatory responses, as well. Due to the anti-inflammatory function of PPAR-γ, identifying the relation between PPAR-γ, sarcoidosis development, and inflammatory state could be essential to identify the appropriate therapeutic targets. The synthesis of PPAR-γ agonists or PPAR-γ ligands may be an effective step toward the treatment of sarcoidosis patients in the future.

Oxygen desaturation during the 6-min walk test as a risk for osteoporosis in non-cystic fibrosis bronchiectasis

BACKGROUND

Osteoporosis is a common comorbidity in non-cystic fibrosis (non-CF) bronchiectasis patients. We determined whether desaturation during 6-min walk test (6MWT) can be a predictor for osteoporosis risk.

METHODS

This was a retrospective cross-sectional study. Sixty-six non-CF bronchiectasis patients were enrolled. Lung function, walking distance, the lowest oxygen saturation (SpO₂), the fall in SpO₂ (ΔSpO₂), and the distance-saturation product (DSP) were determined during the 6MWT. Desaturators (n = 45) were defined as those with ΔSpO₂ > 10% or the lowest SpO₂ < 88%. Bone mineral density (BMD) was determined through dual-energy X-ray absorptiometry. The severity of non-CF bronchiectasis was evaluated using high-resolution computed tomography.

RESULTS

Osteoporosis was evident in more desaturators (82%) than non-desaturators (43%, p < 0.01). BMD at the level of the femoral neck was significantly lower in desaturators than in non-desaturators (- 3.6 ± 1.1 vs. - 2.4 ± 0.9, p < 0.01). BMD was correlated positively with the lowest SpO₂ and negatively with ΔSpO₂ and severe exacerbations. In multivariate linear regression analysis, desaturation during 6MWT was the most significant predictive factor for osteoporosis (95% confidence interval - 1.60 to - 0.26, p = 0.01). Other risk factors included old age, low body mass index and severe exacerbation.

CONCLUSIONS

Exertional desaturation during the 6MWT was a significant predictive factor for osteoporosis in Asian non-CF bronchiectasis patients. The 6MWT may be useful in identifying the osteoporotic phenotype of non-CF bronchiectasis and increasing clinician awareness to promote early intervention.

Impact of concomitant nontuberculous mycobacteria and Pseudomonas aeruginosa isolates in non-cystic fibrosis bronchiectasis

Purpose

Pseudomonas aeruginosa is associated with pulmonary function decline and high disease severity in non-cystic fibrosis (CF) bronchiectasis. The prevalence of nontuberculous mycobacteria (NTM) in non-CF bronchiectasis patients has increased recently. This study investigated the impact of NTM with or without P. aeruginosa isolates in non-CF bronchiectasis patients.

Patients and methods

Our retrospective study included 96 non-CF bronchiectasis patients from January 2005 to December 2014. We recorded the presentation, exacerbations, emergency department (ED) visits, hospitalization, serial pulmonary function, radiologic studies, and sputum culture results. All patients were followed up for at least 2 years.

Results

The 96 patients were divided into four groups: patients with concomitant negative NTM and P. aeruginosa isolates (n=41; group 1), patients with positive NTM isolates (n=20; group 2), patients with positive P. aeruginosa isolates (n=20; group 3), and patients with concomitant positive NTM and P. aeruginosa isolates (n=15; group 4). Compared with group 1 patients, patients in groups 2 and 3 showed a significant decline in forced expiratory volume in 1 second (FEV₁). They also had more frequent annual acute exacerbations (AE), ED visits, and hospitalization. Group 4 patients had the greatest FEV₁ and forced vital capacity (FVC) decline and the most frequent AE, ED visits, and hospitalization.

Conclusion

Concomitant NTM and P. aeruginosa isolates in non-CF bronchiectasis are associated with the greatest pulmonary function decline and the worst disease severity. This result suggested that early recognition and prompt treatment of concomitant NTM and P. aeruginosa isolates may improve the outcome in non-CF bronchiectasis patients.

Pathophysiology and Genetics of Bronchiectasis Unrelated to Cystic Fibrosis

Bronchiectasis is characterized by deregulated inflammatory response and recurrent bacterial infection resulting in progressive lung damage and an irreversible dilatation of bronchi and bronchioles. Generally accepted model of the development of bronchiectasis is the "vicious cycle hypothesis" that proposes compromising of the mucociliary clearance by an initial event, which leads to the infection of the respiratory tract followed by further impairment of mucociliary function, bacterial proliferation, and more inflammation. Bronchiectasis is a very common symptom in patients with cystic fibrosis (CF), while bronchiectasis unrelated to CF is heterogeneous pathology of unknown cause with a large number of potential contributory factors and poorly understood pathogenesis. It is presumed that bronchiectasis unrelated to CF is a multifactorial condition predisposed by genetic factors. Different molecules have been implicated in the onset and development of idiopathic bronchiectasis, as well as modulation of the disease severity and response to therapy. Most of these molecules are involved in the processes that contribute to the homeostasis of the lung tissue, especially mucociliary clearance, protease-antiprotease balance, and immunomodulation. Evaluation of the studies performed towards investigation of the role these molecules play in bronchiectasis identifies genetic variants that may be of potential importance for clinical management of the disease, and also of interest for future research efforts. This review focuses on the molecules with major roles in lung homeostasis and their involvement in bronchiectasis unrelated to CF.

Role of MMP-1 (-519A/G, -1607 1G/2G), MMP-3 (Lys45Glu), MMP-7 (-181A/G), and MMP-12 (-82A/G) Variants and Plasma MMP Levels on Obesity-Related Phenotypes and Microvascular Reactivity in a Tunisian Population

Aims

The impact of MMP-1 (-519A/G, -1607 1G/2G), MMP-3 Lys45Glu (A/G), MMP-7 -181A/G, and MMP-12 -82A/G variants and plasma MMP levels on obesity and microvascular reactivity in Tunisians.

Methods

Our population included 202 nonobese and 168 obese subjects. Anthropometric, biochemical, and microvascular parameters were determined according to standard protocols. PCR-RFLP and ELISA were used to determine the genetic variants and levels of MMPs, respectively.

Results

The MMP-3 45Glu (G) allele associates with higher anthropometric values and MMP-3 levels compared to AA genotype carriers (BMI (kg/m²): 30 ± 0.51 versus 27.33 ± 0.8, P = 0.004; MMP-3 levels: 7.45 (4.77–11.91) versus 5.21 (3.60–10.21) ng/ml, P = 0.006). The MMP-12 -82G allele was also associated with higher BMI values when compared to subjects carrying the AA genotype (31.41 ± 0.85 versus 28.76 ± 0.43, P < 0.001). Individuals carrying the MMP-3 45G or MMP-12 -82G variants were also associated with a higher risk for severe forms of obesity (MMP-3: OR = 1.9, P = 0.002; MMP-12: OR = 2.63, P = 0.003). Similarly, the MMP-7 -181G allele was associated with a higher MMP-7 level and an increased risk for morbid obesity when compared to AA genotype carriers (0.32 (0.31–0.60) versus 0.18 (0.17–0.24) ng/ml, P = 0.01; OR = 1.67, P = 0.02, resp.).

Conclusion

MMP-3, MMP-7, and MMP-12 polymorphisms associate with obesity risk and its severity.

MMP-2 (-1306 C/T) Polymorphism Affects Serum Matrix Metalloproteinase (MMP)-2 Levels and Correlates with Chronic Obstructive Pulmonary Disease Severity: A Case-Control Study of MMP-1 and -2 in a Tunisian Population

OBJECTIVE

The aim of this study was to determine the role of MMP-1 (-1607 1G/2G; -519 A/G) and MMP-2 (-1306 C/T; -735 C/T) polymorphisms in the development and severity of chronic obstructive pulmonary disease (COPD) in Tunisian patients. We also evaluated the impact of these genetic variants on serum levels of the corresponding proteins.

METHODS

The study included 138 patients with COPD and 216 healthy controls. Pulmonary function was evaluated using body plethysmography, and COPD severity was determined based on forced expiratory volume in 1 s (FEV1%). MMP-1 and MMP-2 variants were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), while serum matrix metalloproteinase (MMP)-1 and -2 levels were determined by enzyme-linked immunosorbent assay (ELISA) and activity of MMP-2 was determined by gelatin zymography.

RESULTS

No significant associations were found between genetic variations in MMP-1 and MMP-2 variants and the risk of development of COPD. Additionally, no significant impact of the MMP-1 (-1607 1G/2G; -519 A/G) and MMP-2 (-735 C/T) polymorphisms was observed on the respective protein levels and clinical parameters of the disease. Interestingly, a significant correlation was identified between the MMP-2 (-1306) C/T and disease severity [p = 0.01; Bonferroni corrected p value (p _c) = 0.04]. Increased levels of MMP-2 were also identified in patients with the MMP-2 (-1306) CC genotype compared with those with CT and TT genotypes (105 [84.69-121.5] vs. 86.29 [80.99-92.62] ng/ml; p = 0.01, p _c = 0.04). Additionally, MMP-2 activity was enhanced in patients carrying the CC genotype compared with those carrying the T variant (p = 0.01, p _c = 0.02).

CONCLUSION

Our data suggest that, although MMP-1 (-1607 1G/2G; -519 A/G) and MMP-2 (-735 C/T) may not affect COPD risk and clinical parameters, the MMP-2 (-1306C/T) variant was correlated to COPD severity. These findings could be related to alterations in the level and activity of MMP-2 in serum from patients carrying the (-1306) CC genotype.

FUT2 genotype influences lung function, exacerbation frequency and airway microbiota in non-CF bronchiectasis

OBJECTIVE

To assess whether FUT2 (secretor) genotype affects disease severity and airway infection in patients with non-cystic fibrosis bronchiectasis.

PARTICIPANTS

Induced sputum samples were obtained from 112 adult patients with high-resolution CT scan-proven bronchiectasis and at least two exacerbations in the previous year, as part of an unrelated randomised control trial.

OUTCOME MEASURES

Presence of null FUT2 polymorphisms were determined by gene sequencing and verified by endobronchial biopsy histochemical staining. Outcome measures were FEV1% predicted, exacerbation frequency, and bacterial, fungal and viral components of the microbiota (measured by culture independent approaches).

RESULTS

Patients were grouped by FUT2 loss-of-function genotype; categorised as non-secretors (n=27, sese), heterozygous secretors (n=54, Sese) or homozygous secretors (n=31, SeSe). FEV1% was significantly lower in SeSe patients compared with sese patients (mean 61.6 (SD 20.0) vs 74.5 (18.0); p=0.023). Exacerbation frequency was significantly higher in SeSe (mean count 5.77) compared with sese (4.07; p=0.004) and Sese (4.63; p=0.026) genotypes. The time until first exacerbation was significantly shorter in SeSe compared with Sese (HR=0.571 (95% CI 0.343 to 0.950); p=0.031), with a similar trend for sese patients (HR=0.577 (0.311 to 1.07); p=0.081). sese had a significantly reduced frequency of Pseudomonas aeruginosa-dominated airway infection (8.7%) compared with Sese (31%; p=0.042) and SeSe (36%; p=0.035). In contrast, fungal, viral and non-dominant bacterial components of the microbiome were not significantly different between FUT2 genotypes.

CONCLUSIONS

FUT2 genotype in patients with non-cystic fibrosis bronchiectasis was significantly associated with disease outcomes, with homozygous secretors exhibiting lower lung function, higher exacerbation number and a higher frequency of P. aeruginosa-dominated infection.

TRIAL REGISTRATION NUMBER

ACTRN12609000578202 (anzctr.org.au); Pre-results.

Gender susceptibility to mycobacterial infections in patients with non-CF bronchiectasis

Non-tuberculous mycobacteria (NTM) are environmental microbes that cause a variety of diseases both in immunocompromised and immunocompetent patients. Epidemiologic data indicate that there has been a global rise in the incidence of NTM infections. It has also been noted that NTM infections have a predilection to occur in postmenopausal women. In a recent study, it was demonstrated that in patients with non-CF bronchiectasis the probability of NTM isolation was significantly higher in elderly female patients and in those with a low body mass index. However, the mechanisms of causality of these gender differences and morpho-phenotypes remain enigmatic. The present study reviews the data and plausible mechanisms which might provide clues to this gender susceptibility and morpho-phenotypes of patients with bronchiectasis and NTM.

Pediatric bronchiectasis: No longer an orphan disease

Bronchiectasis is described classically as a chronic pulmonary disorder characterized by a persistent productive cough and irreversible dilatation of one or more bronchi. However, in children unable to expectorate, cough may instead be wet and intermittent and bronchial dilatation reversible in the early stages. Although still considered an orphan disease, it is being recognized increasingly as causing significant morbidity and mortality in children and adults in both affluent and developing countries. While bronchiectasis has multiple etiologies, the final common pathway involves a complex interplay between the host, respiratory pathogens and environmental factors. These interactions lead to a vicious cycle of repeated infections, airway inflammation and tissue remodelling resulting in impaired airway clearance, destruction of structural elements within the bronchial wall causing them to become dilated and small airway obstruction. In this review, the current knowledge of the epidemiology, pathobiology, clinical features, and management of bronchiectasis in children are summarized. Recent evidence has emerged to improve our understanding of this heterogeneous disease including the role of viruses, and how antibiotics, novel drugs, antiviral agents, and vaccines might be used. Importantly, the management is no longer dependent upon extrapolating from the cystic fibrosis experience. Nevertheless, substantial information gaps remain in determining the underlying disease mechanisms that initiate and sustain the pathophysiological pathways leading to bronchiectasis. National and international collaborations, standardizing definitions of clinical and research end points, and exploring novel primary prevention strategies are needed if further progress is to be made in understanding, treating and even preventing this often life-limiting disease.

Associations of MMP1, MMP2 and MMP3 Genes Polymorphism with Coal Workers' Pneumoconiosis in Chinese Han Population

Coal workers’ pneumoconiosis (CWP) has been associated with abnormalities in the extracellular matrix remodeling, as well as aberrant matrix metalloproteinases (MMPs) in lung tissues. We investigated the association of three functional polymorphisms in MMP gene promoters (MMP1 rs1799750, MMP2 rs2285053 and MMP3 rs522616) with the risk of CWP. A total of 693 CWP cases and 690 controls were included in a case-control study. Genotype analysis was performed by the TaqMan method. Statistically significant differences were found in distributions of MMP3 rs522616 under a recessive model (p = 0.047) between CWP cases and controls. In the stratification analysis, individuals with MMP3 rs522616 GG genotype decreased the risk of CWP (adjusted OR = 0.72, 95% CI = 0.52–0.99) compared to those with AA/AG genotype obviously, particularly among subgroups of no smokers (adjusted OR = 0.64, 95% CI = 0.41–1.00). Furthermore, serum MMP3 protein levels measured with enzyme-linked immune-sorbent assay in the control group was significantly lower than that in the CWP groups (p = 0.02). Extremely lower MMP3 among subjects with the rs522616 GG or AG genotype compared with the AA genotype carriers (p < 0.05, p < 0.01 respectively) in the normal serum. These findings indicate that the MMP3 rs522616 polymorphism may contribute to the etiology of CWP in the Chinese population and MMP3 might be a potential diagnostic biomarker for CWP, additional independent studies are warranted to validate our findings in different populations as well as in a larger series.

Heme Oxygenase-1 Regulation of Matrix Metalloproteinase-1 Expression Underlies Distinct Disease Profiles in Tuberculosis

Pulmonary tuberculosis (TB) is characterized by oxidative stress and lung tissue destruction by matrix metalloproteinases (MMPs). The interplay between these distinct pathological processes and the implications for TB diagnosis and disease staging are poorly understood. Heme oxygenase-1 (HO-1) levels were previously shown to distinguish active from latent TB, as well as successfully treated Mycobacterium tuberculosis infection. MMP-1 expression is also associated with active TB. In this study, we measured plasma levels of these two important biomarkers in distinct TB cohorts from India and Brazil. Patients with active TB expressed either very high levels of HO-1 and low levels of MMP-1 or the converse. Moreover, TB patients with either high HO-1 or MMP-1 levels displayed distinct clinical presentations, as well as plasma inflammatory marker profiles. In contrast, in an exploratory North American study, inversely correlated expression of HO-1 and MMP-1 was not observed in patients with other nontuberculous lung diseases. To assess possible regulatory interactions in the biosynthesis of these two enzymes at the cellular level, we studied the expression of HO-1 and MMP-1 in M. tuberculosis-infected human and murine macrophages. We found that infection of macrophages with live virulent M. tuberculosis is required for robust induction of high levels of HO-1 but not MMP-1. In addition, we observed that CO, a product of M. tuberculosis-induced HO-1 activity, inhibits MMP-1 expression by suppressing c-Jun/AP-1 activation. These findings reveal a mechanistic link between oxidative stress and tissue remodeling that may find applicability in the clinical staging of TB patients.