Sirt1 expression is associated with CD31 expression in blood cells from patients with chronic obstructive pulmonary disease

Melatonin and mesenchymal stem cells co-administration alleviates chronic obstructive pulmonary disease via modulation of angiogenesis at the vascular-alveolar unit

Chronic obstructive pulmonary disease (COPD) is considered a severe disease mitigating lung physiological functions with high mortality outcomes, insufficient therapy, and pathophysiology pathways which is still not fully understood. Mesenchymal stem cells (MSCs) derived from bone marrow play an important role in improving the function of organs suffering inflammation, oxidative stress, and immune reaction. It might also play a role in regenerative medicine, but that is still questionable. Additionally, Melatonin with its known antioxidative and anti-inflammatory impact is attracting attention nowadays as a useful treatment. We hypothesized that Melatonin may augment the effect of MSCs at the level of angiogenesis in COPD. In our study, the COPD model was established using cigarette smoking and lipopolysaccharide. The COPD rats were divided into four groups: COPD group, Melatonin-treated group, MSC-treated group, and combined treated group (Melatonin-MSCs). We found that COPD was accompanied by deterioration of pulmonary function tests in response to expiratory parameter affection more than inspiratory ones. This was associated with increased Hypoxia inducible factor-1α expression and vascular endothelial growth factor level. Consequently, there was increased CD31 expression indicating increased angiogenesis with massive enlargement of airspaces and thinning of alveolar septa with decreased mean radial alveolar count, in addition to, inflammatory cell infiltration and disruption of the bronchiolar epithelial wall with loss of cilia and blood vessel wall thickening. These findings were improved significantly when Melatonin and bone marrow-derived MSCs were used as a combined treatment proving the hypothesized target that Melatonin might augment MSCs aiming at vascular changes.

Prognostic value of the serum creatinine/cystatin C ratio in patients with chronic obstructive pulmonary disease

BACKGROUND

Sarcopenia, characterized by skeletal muscle atrophy and physical inactivity, is a manifestation of chronic obstructive pulmonary disease (COPD) and is associated with a poor prognosis. The serum creatinine (Cr)/cystatin C (CysC) ratio has been proposed as a marker of sarcopenia, given its correlation with total skeletal muscle mass, and as a prognostic indicator in COPD. This study aimed to evaluate the usefulness of the serum Cr/CysC ratio as a prognostic determinant in these patients.

METHODS

A total of 124 outpatients with COPD were enrolled in this study. Their serum Cr and CysC levels were measured. Survival time analyses were conducted to compare mortality rates between the low and high serum Cr/CysC ratio groups. Multivariate analysis was performed to investigate the association between various factors.

RESULTS

Using a serum Cr/CysC cut-off value of 0.885, the mortality rate (per 1000 person-years) for overall mortality was significantly higher in the low serum Cr/CysC ratio group (69.2 versus 28.6; hazard ratio, 2.47; 95% confidence interval, 1.06-5.79; p < 0.05). Similarly, the mortality rate due to respiratory disease was also higher (37.8 versus 8.2; hazard ratio, 4.68; 95% confidence interval, 1.05-20.9; p < 0.05). Multivariate Cox proportional hazards analysis revealed that serum Cr/CysC was an independent risk factor for respiratory disease mortality, regardless of age and airflow limitations.

CONCLUSIONS

The serum Cr/CysC ratio could be a valuable clinical parameter for identifying sarcopenia and severe airflow obstruction. The study findings highlight the utility of this ratio as a prognostic predictor in patients with COPD.

Recombinant Human HAPLN1 Mitigates Pulmonary Emphysema by Increasing TGF-β Receptor I and Sirtuins Levels in Human Alveolar Epithelial Cells

Chronic obstructive pulmonary disease (COPD) will be the third leading cause of death worldwide by 2030. One of its components, emphysema, has been defined as a lung disease that irreversibly damages the lungs' alveoli. Treatment is currently unavailable for emphysema symptoms and complete cure of the disease. Hyaluronan (HA) and proteoglycan link protein 1 (HAPLN1), an HA-binding protein linking HA in the extracellular matrix to stabilize the proteoglycan structure, forms a bulky hydrogel-like aggregate. Studies on the biological role of the full-length HAPLN1, a simple structure-stabilizing protein, are limited. Here, we demonstrated for the first time that treating human alveolar epithelial type 2 cells with recombinant human HAPLN1 (rhHAPLN1) increased TGF-β receptor 1 (TGF-β RI) protein levels, but not TGF-β RII, in a CD44-dependent manner with concurrent enhancement of the phosphorylated Smad3 (p-Smad3), but not p-Smad2, upon TGF-β1 stimulation. Furthermore, rhHAPLN1 significantly increased sirtuins levels (i.e., SIRT1/2/6) without TGF-β1 and inhibited acetylated p300 levels that were increased by TGF-β1. rhHAPLN1 is crucial in regulating cellular senescence, including p53, p21, and p16, and inflammation markers such as p-NF-κB and Nrf2. Both senile emphysema mouse model induced via intraperitoneal rhHAPLN1 injections and porcine pancreatic elastase (PPE)-induced COPD mouse model generated via rhHAPLN1-containing aerosols inhalations showed a significantly potent efficacy in reducing alveolar spaces enlargement. Preclinical trials are underway to investigate the effects of inhaled rhHAPLN1-containing aerosols on several COPD animal models.

E-Cigarette Aerosol Condensate Leads to Impaired Coronary Endothelial Cell Health and Restricted Angiogenesis

Cardiovascular disease (CVD) is a leading cause of mortality worldwide, with cigarette smoking being a major preventable risk factor. Smoking cessation can be difficult due to the addictive nature of nicotine and the withdrawal symptoms following cessation. Electronic cigarettes (e-Cigs) have emerged as an alternative smoking cessation device, which has been increasingly used by non-smokers; however, the cardiovascular effects surrounding the use of e-Cigs remains unclear. This study aimed to investigate the effects of e-Cig aerosol condensate (EAC) (0 mg and 18 mg nicotine) in vitro on human coronary artery endothelial cells (HCAEC) and in vivo on the cardiovascular system using a mouse model of ‘e-vaping’. In vitro results show a decrease in cell viability of HCAEC when exposed to EAC either directly or after exposure to conditioned lung cell media (p < 0.05 vs. control). Reactive oxygen species were increased in HCAEC when exposed to EAC directly or after exposure to conditioned lung cell media (p < 0.0001 vs. control). ICAM-1 protein expression levels were increased after exposure to conditioned lung cell media (18 mg vs. control, p < 0.01). Ex vivo results show an increase in the mRNA levels of anti-angiogenic marker, FKBPL (p < 0.05 vs. sham), and endothelial cell adhesion molecule involved in barrier function, ICAM-1 (p < 0.05 vs. sham) in murine hearts following exposure to electronic cigarette aerosol treatment containing a higher amount of nicotine. Immunohistochemistry also revealed an upregulation of FKBPL and ICAM-1 protein expression levels. This study showed that despite e-Cigs being widely used for tobacco smoking cessation, these can negatively impact endothelial cell health with a potential to lead to the development of cardiovascular disease.

SIRT1 as a Potential Therapeutic Target for Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common, preventable, and treatable disease characterized by irreversible airflow obstruction and lung function decline. It is well established that COPD represents a major cause of morbidity and mortality globally. Due to the substantial economic and social burdens associated with COPD, it is necessary to discover new targets and develop novel beneficial therapies. Although the pathogenesis of COPD is complex and remains to be robustly elucidated, numerous studies have shown that oxidative stress, inflammatory responses, cell apoptosis, autophagy, and aging are involved in the pathogenesis of COPD. Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase belonging to the silent information regulator 2 (Sir2) family. Multiple studies have indicated that SIRT1 plays an important role in oxidative stress, apoptosis, inflammation, autophagy, and cellular senescence, which contributes to the pathogenesis and development of COPD. This review aimed to discuss the functions and mechanisms of SIRT1 in the progression of COPD and concluded that SIRT1 activation might be a potential therapeutic strategy for COPD.

Serum Derivatives of Reactive Oxygen Metabolites are Associated with Severity of Chronic Obstructive Pulmonary Disease and Affected by a p53 Gene Polymorphism

Purpose

Oxidative stress is known to activate tumor suppressor p53, which inhibits cell cycle progression and induces apoptosis. Levels of p53 in lung tissues from patients with chronic obstructive pulmonary disease (COPD) are increased compared with levels in nonsmokers or smokers without emphysema. A polymorphism in p53 codon 72 (rs1042522) is associated with emphysematous changes in patients with COPD. However, whether oxidative stress in the serum is associated with the p53 polymorphism and disease severity in COPD patients is unclear.

Patients and Methods

A total of 251 patients with a history of smoking more than 10 pack-years were enrolled in this study, and serum levels of derivatives of reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), and d-ROMs/BAP ratio (oxidative stress index; OSI) were measured. The percent low-attenuation area (LAA%) and cross-sectional area of the erector spinae muscles (ESM_CSA) at the Th₁₂ level were calculated from chest high-resolution computed tomography images. p53 codon 72 C/G genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism analysis.

Results

In patients carrying the p53 GG genotype, LAA% was significantly higher than in those carrying the CC genotype. d-ROM levels and OSI were associated with COPD severity and correlated with airflow limitation and markers of muscle atrophy (ESM_CSA and creatinine/cystatin C ratio). Associations between markers of oxidative stress and COPD severity were observed primarily in patients carrying the p53 codon 72 GG genotype.

Conclusion

Susceptibility to pulmonary emphysema and responses to oxidative stress may be affected by the p53 gene polymorphism.

Serum Creatinine/Cystatin C Ratio Associated with Cross-Sectional Area of Erector Spinae Muscles and Pulmonary Function in Patients with Chronic Obstructive Pulmonary Disease

Purpose

Muscle atrophy is a major clinical feature of chronic obstructive pulmonary disease (COPD) and is considered a predictor of mortality in COPD patients. Recently, the cross-sectional area (CSA) of the erector spinae muscles measured by chest computed tomography (CT) scans (ESM_CSA) has been reported as a clinical parameter reflecting disease severity and future prognosis in patients with COPD. In addition, the serum creatinine (Cr)/cystatin C (CysC) ratio has been considered a quantitative marker of residual muscle mass, because serum Cr levels are affected by muscle mass, and correction by CysC counteracts the effect of renal function on serum Cr levels. The purpose of this study was to assess whether the serum Cr level corrected by serum CysC can be used as a predictive marker of pulmonary function and disease severity in patients with COPD.

Patients and Methods

A total of 99 patients without COPD and 201 patients with COPD, with a smoking history of more than 10 pack-years were enrolled in this study, and serum Cr and CysC levels were measured. On chest high-resolution CT images, %low attenuation area (LAA%) (≤960 Hounsfield units (HU)) and ESM_CSA at the Th₁₂ level were identified.

Results

There was a significant correlation between the ESM_CSA and the Cr/CysC ratio. The Cr/CysC ratio was significantly associated with forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) values, especially in former smokers.

Conclusion

The serum Cr/CysC ratio could be a convenient substitute for the measurement of muscle atrophy and pulmonary function testing in patients with COPD.

Histidine ameliorates elastase- and lipopolysaccharide-induced lung inflammation by inhibiting the activation of the NLRP3 inflammasome

Histidine treatment has anti-inflammatory effects on several diseases such as colitis and obesity. We revealed that histidine levels were decreased in the serum of patients with chronic obstructive pulmonary disease (COPD) in our previous study. However, whether histidine confers protection against COPD is unclear. In the present study, we evaluated the protective effects of histidine in a porcine pancreatic elastase- and lipopolysaccharide-induced COPD mouse model. We found that the serum histidine concentration was decreased in COPD mice. Histidine supplementation improved the COPD mouse lung function and reduced the inflammatory cell counts and production of cytokines in bronchoalveolar lavage fluid. In addition, histidine treatment ameliorated lung inflammation by inhibiting the nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain-containing 3 inflammasome activation both in vivo and in vitro. Furthermore, we found that the potential anti-inflammatory mechanism involved the upregulation of silent information regulator factor 2-related enzyme 1. These results suggest that histidine may be a valuable therapeutic target for COPD.

MicroRNAs as Potential Regulators of Immune Response Networks in Asthma and Chronic Obstructive Pulmonary Disease

Chronic respiratory diseases (CRDs) are an important factor of morbidity and mortality, accounting for approximately 6% of total deaths worldwide. The main CRDs are asthma and chronic obstructive pulmonary disease (COPD). These complex diseases have different triggers including allergens, pollutants, tobacco smoke, and other risk factors. It is important to highlight that although CRDs are incurable, various forms of treatment improve shortness of breath and quality of life. The search for tools that can ensure accurate diagnosis and treatment is crucial. MicroRNAs (miRNAs) are small non-coding RNAs and have been described as promising diagnostic and therapeutic biomarkers for CRDs. They are implicated in multiple processes of asthma and COPD, regulating pathways associated with inflammation, thereby showing that miRNAs are critical regulators of the immune response. Indeed, miRNAs have been found to be deregulated in several biofluids (sputum, bronchoalveolar lavage, and serum) and in both structural lung and immune cells of patients in comparison to healthy subjects, showing their potential role as biomarkers. Also, miRNAs play a part in the development or termination of histopathological changes and comorbidities, revealing the complexity of miRNA regulation and opening up new treatment possibilities. Finally, miRNAs have been proposed as prognostic tools in response to both conventional and biologic treatments for asthma or COPD, and miRNA-based treatment has emerged as a potential approach for clinical intervention in these respiratory diseases; however, this field is still in development. The present review applies a systems biology approach to the understanding of miRNA regulatory networks in asthma and COPD, summarizing their roles in pathophysiology, diagnosis, and treatment.

3,4,5-Trihydroxycinnamic acid exerts a protective effect on pulmonary inflammation in an experimental animal model of COPD

3,4,5-Trihydroxycinnamic acid (THCA), a derivative of hydroxycinnamic acid, has been reported to exert anti-inflammatory and antioxidant activities. However, its anti-inflammatory effects in chronic obstructive pulmonary disease (COPD) have not yet been elucidated. Therefore, we explored the protective effects of THCA on pulmonary inflammation in an experimental COPD model elicited by cigarette smoke (CS) and lipopolysaccharide (LPS). Oral administration of THCA significantly inhibited the activity of elastase, the release of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1), myeloperoxidase (MPO) and the numbers of neutrophils and macrophages in the bronchoalveolar lavage fluid (BALF) of experimental COPD mice. THCA also exerted inhibitory effects on the recruitment of inflammatory cells, the levels of PAS positive cells and cAMP-response-element-binding protein (CREB) activation, and the expression of phosphodiesterase 4 (PDE4) in the lungs of experimental COPD mice. In addition, THCA exerted a regulatory effect on the activation of p38, ERK and nuclear factor-κB (NF-κB) in the lungs of experimental COPD mice. THCA also significantly upregulated the expression of NAD(P)H dehydrogenase (quinone 1) 1 (NQO1) and the activation of nuclear factor erythroid-derived 2-related factor 2 (Nrf2) in the lungs of mice. Furthermore, THC restored the reduction of NAD-dependent protein deacetylase sirtuin-1 (SIRT1) in the lungs of experimental COPD mice. In phorbol myristate acetate (PMA)-stimulated A549 or H292 airway epithelial cells, pretreatment of THCA dose-dependently inhibited the generation of IL-6. THCA also led to increased NQO1 expression in H292 cells. Collectively, these protective effects of antioxidant THCA were notably excellent and are thought to be associated with the downregulation of MAPK (partial)/NF-κB signaling and upregulation of NQO1 and SIRT1 expression.

Sirtuins family as a target in endothelial cell dysfunction: implications for vascular ageing

The vascular endothelium is a protective barrier between the bloodstream and the vasculature that may be disrupted by different factors such as the presence of diseased states. Diseases like diabetes and obesity pose a great risk toward endothelial cell inflammation and oxidative stress, leading to endothelial cell dysfunction and thereby cardiovascular complications such as atherosclerosis. Sirtuins are NAD⁺-dependent histone deacetylases that are implicated in the pathophysiology of cardiovascular diseases, and they have been identified to be important regulators of endothelial cell function. A handful of recent studies suggest that disbalance in the regulation of endothelial sirtuins, mainly sirtuin 1 (SIRT1), contributes to endothelial cell dysfunction. Herein, we summarize how SIRT1 and other sirtuins may contribute to endothelial cell function and how presence of diseased conditions may alter their expressions to cause endothelial dysfunction. Moreover, we discuss how the beneficial effects of exercise on the endothelium are dependent on SIRT1. These mainly include regulation of signaling pathways related to endothelial nitric oxide synthase phosphorylation and nitric oxide production, mitochondrial biogenesis and mitochondria-mediated apoptotic pathways, oxidative stress and inflammatory pathways. Sirtuins as modulators of the adverse conditions in the endothelium hold a promising therapeutic potential for health conditions related to endothelial dysfunction and vascular ageing.

Genetic underpinnings of lung function and COPD

Spirometry based measurement of lung function is a global initiative for chronic obstructive lung disease (GOLD) standard to diagnose chronic obstructive pulmonary disease (COPD), one of the leading causes of mortality worldwide. The environmental and behavioural risk factors for COPD includes tobacco smoking, air pollutants and biomass fuel exposure, which can induce one or more abnormal lung function patterns. While smoking remains the primary risk factor, only 15-20% smokers develop COPD, indicating that the genetic factors are also likely to play a role. According to the study of Global Burden of Disease 2015, ∼174 million people across the world have COPD. From a comprehensive literature search conducted using the 'PubMed' and 'GWAS Catalogue' databases, and reviewing the literature available, only a limited number of studies were identified which had attempted to investigate the genetics of COPD and lung volumes, implying a huge research gap. With the advent of genomewide association studies several genetic variants linked to lung function and COPD, like HHIP, HTR4, ADAM19 and GSTCD etc., have been found and validated in different population groups, suggesting their potential role in determining lung volume and risk for COPD. This article aims at reviewing the present knowledge of the genetics of lung function and COPD.

Association between circulating microRNA-126 expression level and tumour necrosis factor alpha in healthy smokers

Introduction: Smoking contributes to the death of a million people worldwide each year. Smokers experience an alteration in tumour necrosis factor-alpha (TNF-α), and the risk of expected lung cancer. The study aimed at investigating the expression levels of mir-126 and mir-124, as well as TNF-α as possible biomarkers of expected smoking-related diseases. Methods: Twenty-five male smokers' age and sex-matched with 25 non-smokers were recruited for the present study. Plasma expression levels of mir-126 and mir-124 were evaluated using quantitative real-time PCR. Lipid profile, TNF-α, interleukin-6 and C-reactive protein were assessed in plasma of each participant. Results: Plasma miR-126 was statistically down-regulated in smokers relative to non-smokers; however, mir-124 did not show any significant changes between groups. Among the measured parameters, mir-126 and tumour necrosis factor alpha (TNF-α) displayed a good discrimination and sensitivity between smokers and non-smokers (AUC = 0.809 (95% CI: 0.668-0.95; p < 0.001) and 0.742(95% CI: 0.584-0.9; p < 0.01), respectively. Also, the combined evaluation of miR-126 and TNF-α levels showed high discrimination (AUC= 0.889 (95% CI: 0.779-1.00; p < 0.0001), sensitivity = 85%, and specificity = 80% in the diagnosis of smokers with non-smokers. Conclusions: MiR-126 and TNF-α are potential biomarkers of smoking-related diseases and are important in assessing the expected tobacco-related harm.

Controversial Impact of Sirtuins in Chronic Non-Transmissible Diseases and Rehabilitation Medicine

A large body of evidence reports about the positive effects of physical activity in pathophysiological conditions associated with aging. Physical exercise, alone or in combination with other medical therapies, unquestionably causes reduction of symptoms in chronic non-transmissible diseases often leading to significant amelioration or complete healing. The molecular basis of this exciting outcome—however, remain largely obscure. Epigenetics, exploring at the interface between environmental signals and the remodeling of chromatin structure, promises to shed light on this intriguing matter possibly contributing to the identification of novel therapeutic targets. In this review, we shall focalize on the role of sirtuins (Sirts) a class III histone deacetylases (HDACs), which function has been frequently associated, often with a controversial role, to the pathogenesis of aging-associated pathophysiological conditions, including cancer, cardiovascular, muscular, neurodegenerative, bones and respiratory diseases. Numerous studies, in fact, demonstrate that Sirt-dependent pathways are activated upon physical and cognitive exercises linking mitochondrial function, DNA structure remodeling and gene expression regulation to designed medical therapies leading to tangible beneficial outcomes. However, in similar conditions, other studies assign to sirtuins a negative pathophysiological role. In spite of this controversial effect, it is doubtless that studying sirtuins in chronic diseases might lead to an unprecedented improvement of life quality in the elderly.

Nucleosides isolated from Ophiocordyceps sinensis inhibit cigarette smoke extract-induced inflammation via the SIRT1-nuclear factor-κB/p65 pathway in RAW264.7 macrophages and in COPD mice

Background

Ophiocordyceps sinensis (C. sinensis) extracts have been found to have a therapeutic effect on patients with chronic obstructive pulmonary disease (COPD). Silent information regulator 1 (SIRT1) plays an important role in the regulation of inflammatory mediators and correlates with lung function and COPD exacerbations. The objective of this work was to explore the anti-inflammatory effect and preliminary pathways of nucleosides from cultured C. sinensis on RAW264.7 macrophages and COPD mice.

Materials and methods

The nucleosides were extracted from cultured C. sinensis powder and further purified by macroporous resin D101 and glucan G10 columns. Inflammation and oxidative stress models in RAW264.7 macrophages and in mice were established by injection of cigarette smoke extract (CSE). We then examined how the isolated nucleosides regulated the production of the associated inflammatory mediators in vitro and in vivo by enzyme-linked immunosorbent assay, reverse transcription polymerase chain reaction, and Western blot.

Results

The nucleosides inhibited inflammatory mediator expression of tumor necrosis factor-α, interleukin-6, interleukin-1β, and nitric oxide in both the CSE-stimulated RAW264.7 macrophages and mice. Moreover, the nucleosides elevated SIRT1 activation and suppressed nuclear factor-κB (NF-κB)/p65 activation in vitro and in vivo. Nucleoside treatment significantly decreased the levels of the inflammatory mediators in the bronchoalveolar lavage fluid (BALF) and serum of the CSE-induced mice. The nucleosides also altered the recruitment of inflammatory cells in BALF and improved characteristic features of the lungs in the CSE-induced mice.

Conclusion

These results show that the nucleosides suppressed COPD inflammation through the SIRT1–NF-κB/p65 pathway, suggesting that the nucleosides may be partly responsible for the therapeutic effects of cultured C. sinensis on COPD patients.

SIRT1 and SIRT6 Signaling Pathways in Cardiovascular Disease Protection

SIGNIFICANCE

Oxidative stress represents the common hallmark of pathological conditions associated with cardiovascular disease (CVD), including atherosclerosis, heart failure, hypertension, aging, diabetes, and other vascular system-related diseases. The sirtuin (SIRT) family, comprising seven proteins (SIRT1-SIRT7) sharing a highly conserved nicotinamide adenine dinucleotide (NAD+)-binding catalytic domain, attracted a great attention for the past few years as stress adaptor and epigenetic enzymes involved in the cellular events controlling aging-related disorder, cancer, and CVD. Recent Advances: Among sirtuins, SIRT1 and SIRT6 are the best characterized for their protective roles against inflammation, vascular aging, heart disease, and atherosclerotic plaque development. This latest role has been only recently unveiled for SIRT6. Of interest, in recent years, complex signaling networks controlled by SIRT1 and SIRT6 common to stress resistance, vascular aging, and CVD have emerged.

CRITICAL ISSUES

We provide a comprehensive overview of recent developments on the molecular signaling pathways controlled by SIRT1 and SIRT6, two post-translational modifiers proven to be valuable tools to dampen inflammation and oxidative stress at the cardiovascular level.

FUTURE DIRECTIONS

A deeper understanding of the epigenetic mechanisms through which SIRT1 and SIRT6 act in the signalings responsible for onset and development CVD is a prime scientific endeavor of the upcoming years. Multiple "omic" technologies will have widespread implications in understanding such mechanisms, speeding up the achievement of selective and efficient pharmacological modulation of sirtuins for future applications in the prevention and treatment of CVD. Antioxid. Redox Signal. 28, 711-732.

ADRB2 gene polymorphism and emphysema heterogeneity can modulate bronchodilator response in patients with emphysema

BACKGROUND

Genetic variation in the β₂-adrenergic receptor (ADRB2) gene has been thought to have an important role in the differential response to β₂-agonist therapy for asthma. However, previous studies have shown little evidence for an association between these ADRB2 variants and the bronchial dilator response (BDR) in chronic obstructive pulmonary disease (COPD) patients. This discrepancy could be explained by differences in the distribution and heterogeneity of pulmonary emphysema in COPD patients, since emphysema distribution and heterogeneity are thought to have a role in pulmonary function in COPD patients. We hypothesized that differences in emphysema distribution and heterogeneity may have masked significant alterations of the bronchodilator response among ADRB2 genotypes in COPD patients in previous studies.

METHODS

The BDR (induced by 20 μg of procaterol) was measured in 211 patients who had a smoking history of more than 10 pack/years and had undergone chest high resolution computed tomography examination. A low attenuations area (<960 Hounsfield Units) was identified and the emphysema heterogeneity index (EHI%) was calculated with a range in value from -100% to 100%. ADRB2 Arg16Gly genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

The BDR was augmented in patients with homogenous emphysema compared with those with upper-dominant emphysema. In patients carrying the AA genotype of ADRB2, the BDR was significantly increased in patients with upper-dominant emphysema, but not in patients with lower-dominant emphysema.

CONCLUSION

Combination analysis of ADRB2 Arg16Gly polymorphism and EHI% may predict the effectiveness of β₂-adrenergic receptor agonist treatment in patients with COPD and emphysema.