Arginines Plasma Concentration and Oxidative Stress in Mild to Moderate COPD

The Interplay between Nitrosative Stress, Inflammation, and Antioxidant Defense in Patients with Lichen Planus

BACKGROUND

Lichen planus (LP) is a chronic inflammatory skin disease of unelucidated etiology. LP immunopathogenesis is mainly governed by cytotoxic T lymphocytes that mediate an immune response in basal keratinocytes, which may transform into a reservoir of antigens able to initiate an autoimmune reaction. However, other pathogenic pathways complement these mechanisms. Recent studies highlight the involvement of nitrosative stress in the pathogenesis of chronic inflammatory skin diseases. Current data on its role in the pathogenesis of LP are scarce.

METHODS

In this article, we investigated nitrosative stress in 40 cutaneous LP (CLP) patients compared to 40 healthy subjects using serum markers including nitrosative stress markers-direct nitrite, total nitrite, nitrate and symmetric dimethylarginine (SDMA), total antioxidant status (TAS), and hsCRP, a marker of inflammation, and analyzed the relationship between nitrosative stress, antioxidant defense, and inflammation to offer new insights into the role of the NO pathway in LP pathogenesis.

RESULTS

We identified significantly higher serum levels of direct nitrite, total nitrite, nitrate, SDMA and hsCRP, and significantly lower levels of TAS in CLP patients versus controls. There were significant negative correlations between the serum levels of TAS and significantl positive correlations between the serum levels of hsCRP and the analyzed nitrosative stress markers in patients with CLP.

CONCLUSION

Our results indicate an increased level of nitrosative stress in LP patients that correlates with a pro-inflammatory status and altered antioxidant defense.

Targeting type I PRMTs as promising targets for the treatment of pulmonary disorders: Asthma, COPD, lung cancer, PF, and PH

Pulmonary disorders, including asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis (PF), pulmonary hypertension (PH), and lung cancer, seriously impair the quality of lives of patients. A deeper understanding of the occurrence and development of the above diseases may inspire new strategies to remedy the scarcity of treatments. Type I protein arginine methyltransferases (PRMTs) can affect processes of inflammation, airway remodeling, fibroblast proliferation, mitochondrial mass, and epithelial dysfunction through substrate methylation and non-enzymatic activity, thus affecting the occurrence and development of asthma, COPD, lung cancer, PF, and PH. As potential therapeutic targets, inhibitors of type I PRMTs are developed, moreover, representative compounds such as GSK3368715 and MS023 have also been used for early research. Here, we collated structures of type I PRMTs inhibitors and compared their activity. Finally, we highlighted the physiological and pathological associations of type I PRMTs with asthma, COPD, lung cancer, PF, and PH. The developing of type I PRMTs modulators will be beneficial for the treatment of these diseases.

Arginine, Transsulfuration, and Folic Acid Pathway Metabolomics in Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis

There is an increasing interest in biomarkers of nitric oxide dysregulation and oxidative stress to guide management and identify new therapeutic targets in patients with chronic obstructive pulmonary disease (COPD). We conducted a systematic review and meta-analysis of the association between circulating metabolites within the arginine (arginine, citrulline, ornithine, asymmetric, ADMA, and symmetric, SDMA dimethylarginine), transsulfuration (methionine, homocysteine, and cysteine) and folic acid (folic acid, vitamin B6, and vitamin B12) metabolic pathways and COPD. We searched electronic databases from inception to 30 June 2023 and assessed the risk of bias and the certainty of evidence. In 21 eligible studies, compared to healthy controls, patients with stable COPD had significantly lower methionine (standardized mean difference, SMD = -0.50, 95% CI -0.95 to -0.05, p = 0.029) and folic acid (SMD = -0.37, 95% CI -0.65 to -0.09, p = 0.009), and higher homocysteine (SMD = 0.78, 95% CI 0.48 to 1.07, p < 0.001) and cysteine concentrations (SMD = 0.34, 95% CI 0.02 to 0.66, p = 0.038). Additionally, COPD was associated with significantly higher ADMA (SMD = 1.27, 95% CI 0.08 to 2.46, p = 0.037), SDMA (SMD = 3.94, 95% CI 0.79 to 7.08, p = 0.014), and ornithine concentrations (SMD = 0.67, 95% CI 0.13 to 1.22, p = 0.015). In subgroup analysis, the SMD of homocysteine was significantly associated with the biological matrix assessed and the forced expiratory volume in the first second to forced vital capacity ratio, but not with age, study location, or analytical method used. Our study suggests that the presence of significant alterations in metabolites within the arginine, transsulfuration, and folic acid pathways can be useful for assessing nitric oxide dysregulation and oxidative stress and identifying novel treatment targets in COPD. (PROSPERO registration number: CRD42023448036.).

Paraoxonase/Arylesterase Activity of Serum Paraoxonase-1 and Schizophrenia: A Systematic Review and Meta-Analysis

The presence of a pro-oxidant state in patients with schizophrenia may account for the increased risk of atherosclerosis and cardiovascular disease in this group and supports the potential utility of circulating biomarkers of oxidative stress for risk stratification and management. We investigated this issue by conducting a systematic review and meta-analysis of the association between the circulating concentrations of paraoxonase-1, an antioxidant calcium-dependent high-density lipoprotein (HDL)-associated esterase, with paraoxonase and arylesterase activity in schizophrenia. We searched electronic databases from inception to 31 May 2023 for studies investigating paraoxonase-1 in patients with schizophrenia and healthy controls and assessed the risk of bias and the certainty of evidence (PROSPERO registration number: CRD42023435442). Thirteen studies were identified for analysis. There were no significant between-group differences in paraoxonase (standard mean difference, SMD = 0.12, 95% CI -0.23 to 0.48, p = 0.50; extremely low certainty of evidence) or arylesterase activity (SMD = -0.08, 95% CI -0.39 to 0.23, p = 0.61; very low certainty of evidence). However, in meta-regression and subgroup analysis we observed significant associations between the SMD of paraoxonase and age (p = 0.003), HDL-cholesterol (p = 0.029), and study country (p = 0.04), and the SMD of arylesterase and age (p = 0.007), body mass index (p = 0.012), HDL-cholesterol (p = 0.002), and pharmacological treatment for schizophrenia (p < 0.001). In the absence of overall between-group differences, our systematic review and meta-analysis suggests that alterations in paraoxonase-1 may reflect a pro-oxidant state in specific subgroups of patients with schizophrenia that require further assessment in appropriately designed studies.

Markers of Oxidative Stress in Patients with Acne: A Literature Review

Acne vulgaris is a chronic inflammatory skin disease of the pilosebaceous unit. Its pathogenesis is multifactorial and involves the overlap between four main processes: alteration of the keratinization, increased sebum production, colonization with Cutibacterium acnes, and inflammation. The role of oxidative stress (OS) has been intensively studied in inflammatory skin conditions such as psoriasis, vitiligo, or atopic dermatitis. However, the involvement of OS in the pathogenesis of acne is less known. The evidence accumulated over the last decade suggests that in the case of acne patients, there is an imbalance between oxidants and antioxidants. In this review, we analyzed studies that evaluated markers of OS in patients with acne, published in the last ten years, with the aim of providing new insights into the pathogenesis of acne.

Asymmetric Dimethylarginine in COPD Exacerbation

Objectives

Chronic obstructive pulmonary disease (COPD) is a disease with progressive airway limitation. The asymmetric dimethylarginine (ADMA) molecule is known to be effective in airway inflammation and remodeling. We investigated the relationship between ADMA and COPD, and its role in the course of the disease in cases with exacerbation.

Methods

This single-center study performed in our patient clinic included 56 patients (57.1% of males) with median age 67 (41-88) presented with COPD exacerbation and 26 sex-matched healthy controls. ADMA, white blood cell count, eosinophil, neutrophil, lymphocyte, C-reactive protein, fibrinogen, oxygen saturation%, and pulmonary function test values were compared.

Results

ADMA values were significantly higher (516.93 vs. 320.05 median, p<0.05) in the COPD group compared to the control group. No significant difference was demonstrated in ADMA concentrations according to Global Initiative for Chronic Obstructive Lung Disease Stages (p>0.05). In the receiver operating characteristic analysis to estimate the predictive power of COPD, the cutoff ADMA concentration >301 ng/ml was found to be able to distinguish COPD patients in all cases.

Conclusion

ADMA levels increase with complex mechanisms in COPD. It can be a significant indicator of the disease. However, more extensive research is needed for its use as a biomarker in severity and progression of COPD.

Dysregulation of the Nitric Oxide/Dimethylarginine Pathway in Hypoxic Pulmonary Vasoconstriction—Molecular Mechanisms and Clinical Significance

The pulmonary circulation responds to hypoxia with vasoconstriction, a mechanism that helps to adapt to short-lived hypoxic episodes. When sustained, hypoxic pulmonary vasoconstriction (HPV) may become deleterious, causing right ventricular hypertrophy and failure, and contributing to morbidity and mortality in the late stages of several chronic pulmonary diseases. Nitric oxide (NO) is an important endothelial vasodilator. Its release is regulated, amongst other mechanisms, by the presence of endogenous inhibitors like asymmetric dimethylarginine (ADMA). Evidence has accumulated in recent years that elevated ADMA may be implicated in the pathogenesis of HPV and in its clinical sequelae, like pulmonary arterial hypertension (PAH). PAH is one phenotypic trait in experimental models with disrupted ADMA metabolism. In high altitude, elevation of ADMA occurs during long-term exposure to chronic or chronic intermittent hypobaric hypoxia; ADMA is significantly associated with high altitude pulmonary hypertension. High ADMA concentration was also reported in patients with chronic obstructive lung disease, obstructive sleep apnoea syndrome, and overlap syndrome, suggesting a pathophysiological role for ADMA-mediated impairment of endothelium-dependent, NO-mediated pulmonary vasodilation in these clinically relevant conditions. Improved understanding of the molecular (dys-)regulation of pathways controlling ADMA concentration may help to dissect the pathophysiology and find novel therapeutic options for these diseases.

Association of asymmetric dimethylarginine with the pathological process of persistent pulmonary hypertension of the newborn

OBJECTIVES

To study the change in asymmetric dimethylarginine (ADMA) in the circulation system of full-term infants with persistent pulmonary hypertension of the newborn (PPHN) and its association with treatment response, as well as the possibility of ADMA as a therapeutic target and a marker for treatment response.

METHODS

A prospective study was performed. A total of 30 full-term neonates who were diagnosed with PPHN within 3 days after birth were enrolled as the PPHN group, and the neonates without PPHN, matched for gestational age and age, who were treated or observed in the department of neonatology were enrolled as the control group. Serum samples were collected on days 1, 7, and 14 of treatment. The high-performance liquid chromatography-tandem mass spectrometry was used to measure the serum concentrations of L-arginine, ADMA, and its isomer symmetric dimethylarginine (SDMA).

RESULTS

For the neonates in the control group, the serum concentrations of ADMA and L-arginine continuously increased and the serum concentration of SDMA continuously decreased within the first 14 days of treatment. On days 1 and 14, there was no significant difference in the serum concentration of ADMA between the control and PPHN groups (P>0.05). On day 7, the PPHN group had a significantly higher serum concentration of ADMA than the control group (P<0.05), while there were no significant differences in serum concentrations of SDMA or L-arginine (P>0.05). Moreover, after 7 days of treatment, the PPHN neonates with a systolic pulmonary arterial pressure (sPAP) of >35 mmHg had a significantly higher serum concentration of ADMA than those with an sPAP of ≤35 mm Hg.

CONCLUSIONS

There are continuous increases in the ADMA concentration and the ADMA/SDMA ratio in the circulation system of full-term infants within the first 2 weeks after birth, and this process is accelerated by the pathological process of PPHN, suggesting that ADMA may be involved in the pathologic process of PPHN. A high level of ADMA is associated with the resistance to PPHN treatment, suggesting that inhibition of ADMA might be a potential target of drug intervention to improve the treatment response of PPHN.

Paraoxonase 1 and Chronic Obstructive Pulmonary Disease: A Meta-Analysis

Oxidative stress is a driving factor in the pathophysiology of chronic obstructive pulmonary disease (COPD). While paraoxonase 1 (PON1) is an antioxidant enzyme and a potential biomarker of this disease, data regarding the status of PON-1 in COPD are inconclusive. In this regard, to shed light on this issue, we performed a meta-analysis of data on PON1 activity in COPD. Electronic databases (MEDLINE, Embase and CENTRAL) were searched for available studies on PON1 activity in patients with stable COPD published before October 2021. A meta-analysis was performed using random-effects models. Twelve studies (12 studies on paraoxonase and three on arylesterase) were identified. Patients with COPD had lower levels of paraoxonase activity (standard mean difference [SMD] -0.77, 95% confidence interval [CI] -1.35 to -0.18) and arylesterase activity (SMD -1.15, 95% CI -1.95 to -0.36) in comparison to healthy controls. In subgroup analyses, paraoxonase activity was lower in patients of studies as consisted of mainly non-severe COPD (SMD -1.42, 95% CI -2.04 to -0.79) and, by contrast, slightly higher in patients of studies including severe COPD (SMD 0.33, 95% CI 0.02 to 0.64) in comparison to healthy controls. Arylesterase activity showed a similar trend. Overall, PON1 activity was lower in patients with COPD, suggesting that PON1-related antioxidant defense is impaired in COPD. Future studies are warranted.

Reactive Oxygen Species and Antioxidative Defense in Chronic Obstructive Pulmonary Disease

The respiratory system is continuously exposed to endogenous and exogenous oxidants. Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation of the airways, leading to the destruction of lung parenchyma (emphysema) and declining pulmonary function. It is increasingly obvious that reactive oxygen species (ROS) and reactive nitrogen species (RNS) contribute to the progression and amplification of the inflammatory responses related to this disease. First, we described the association between cigarette smoking, the most representative exogenous oxidant, and COPD and then presented the multiple pathophysiological aspects of ROS and antioxidative defense systems in the development and progression of COPD. Second, the relationship between nitric oxide system (endothelial) dysfunction and oxidative stress has been discussed. Third, we have provided data on the use of these biomarkers in the pathogenetic mechanisms involved in COPD and its progression and presented an overview of oxidative stress biomarkers having clinical applications in respiratory medicine, including those in exhaled breath, as per recent observations. Finally, we explained the findings of recent clinical and experimental studies evaluating the efficacy of antioxidative interventions for COPD. Future breakthroughs in antioxidative therapy may provide a promising therapeutic strategy for the prevention and treatment of COPD.

Elevated levels of arginase activity are related to inflammation in patients with COPD exacerbation

Introduction

Within the pathogenesis of the chronic obstructive pulmonary disease (COPD) there are interactions between different inflammatory mediators that are enhanced during an exacerbation. Arginase is present in bronchial epithelial cells, endothelial, fibroblasts and alveolar macrophages, which make it a probable key enzyme in the regulation of inflammation and remodelling. We aimed to find a potential relationship between arginase activity, inflammatory mediators in COPD patients in stable phase and during exacerbations.

Methods

We performed a prospective, observational study of cases and controls, with 4 study groups (healthy controls, stable COPD, COPD during an exacerbation and COPD 3 months after exacerbation). We measured arginase, inflammation markers (IL-6, IL-8, TNF-∝, IFN-γ and C reactive protein), and mediators of immunity: neutrophils, monocytes, total TCD3 + lymphocytes (CD3ζ), CD4 + T cells, CD8 + T cells, NK cells.

Results

A total of 49 subjects were recruited, average age of 69.73 years (59.18% male). Arginase activity is elevated during an exacerbation of COPD, and this rise is related to an increase in IL-6 production. The levels of IL-6 and IL-8 remained elevated in patients with COPD at 3 months after hospital exacerbation.

We did not find a clear relationship between arginase activity, immunity or with the degree of obstruction in COPD patients.

Conclusions

Arginase activity is elevated during an exacerbation of COPD, and it could be related to an increase in the production of IL-6. Levels of IL-6, IL-8, and arginase activity remain elevated in patients with COPD at 3 months after hospital exacerbation. Arginase activity could contribute to the development of COPD.

DNA Methylation: A Potential Biomarker of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a serious public health concern worldwide. By 2040, 4.41 million people are estimated to expire annually due to COPD. However, till date, it has remained difficult to alter the activity or progress of the disease through treatment. In order to address this issue, the best way would be to find biomarkers and new therapeutic targets for COPD. DNA methylation (DNAm) may be a potential biomarker for disease prevention, diagnosis, and prognosis, and its reversibility further makes it a potential drug design target in COPD. In this review, we aimed to explore the role of DNAm as biomarkers and disease mediators in different tissue samples from patients with COPD.

Reliability and Usefulness of Different Biomarkers of Oxidative Stress in Chronic Obstructive Pulmonary Disease

Introduction

Chronic obstructive pulmonary disease (COPD) is a progressive disease characterized by airflow limitation that is not fully reversible after inhaled bronchodilator use associated with an abnormal inflammatory condition. The biggest risk factor for COPD is cigarette smoking. The exposure to noxious chemicals contained within tobacco smoke is known to cause airway epithelial injury through oxidative stress, which in turn has the ability to elicit an inflammatory response. In fact, the disruption of the delicate balance between oxidant and antioxidant defenses leads to an oxidative burden that has long been held responsible to play a pivotal role in the pathogenesis of COPD. There are currently several biomarkers of oxidative stress in COPD that have been evaluated in a variety of biological samples. The aim of this review is to identify the best studied molecules by summarizing the key literature findings, thus shedding some light on the subject.

Methods

We searched for relevant case-control studies examining oxidative stress biomarkers in stable COPD, taking into account the analytical method of detection as an influence factor.

Results

Many oxidative stress biomarkers have been evaluated in several biological matrices, mostly in the blood. Some of them consistently differ between the cases and controls even when allowing different analytical methods of detection.

Conclusions

The present review provides an overview of the oxidative stress biomarkers that have been evaluated in patients with COPD, bringing focus on those molecules whose reliability has been confirmed by the use of different analytical methods.

The Phenotypic Characterization of the Cammalleri Sisters, an Example of Exceptional Longevity

This article shows demographic, clinical, anamnestic, cognitive, and functional data as well as biochemical, genetic, and epigenetic parameters of two exceptional siblings: Diega (supercentenarian) and Filippa (semisupercentenarian) Cammalleri. The purpose of this study is to provide new insights into the extreme phenotypes represented by semisupercentenarians and supercentenarians. Different studies have been published on supercentenarians, but to the best of our knowledge, this is the only concerning two sisters and the most detailed from a phenotypic point of view. Our findings agree with the suggestion that supercentenarians have an increasing relative resistance to age-related diseases, approximating the limits of the functional human reserve to address successfully the acute causes of death. More interestingly, our data agree with, and extend, the suggestion that inflammation and oxidative stress predict centenarian mortality.

Systemic transsulfuration pathway thiol concentrations in chronic obstructive pulmonary disease patients

BACKGROUND

It is amply reported that patients with chronic obstructive pulmonary disease (COPD) have increased risk of cardiovascular disease (CVD). Recent evidence suggests that COPD patients have elevated concentrations of plasma homocysteine (Hcy), a transsulfuration pathway analyte that is commonly regarded as a CVD risk factor.

DESIGN

We comprehensively investigated the plasma concentrations of transsulfuration pathway analytes, and their relationship with markers of oxidative stress and inflammation, to identify which low molecular thiols might play a pathophysiological role both in CVD and in COPD. Hcy, cysteine (Cys), glutathione (GSH), cysteinylglycine (CysGly), glutamylcysteine (GluCys), taurine (Tau), oxidative stress markers (TBARS and protein-SH, PSH) and the inflammation marker kynurenine/tryptophan (Kyn/Trp) ratio were measured in 54 COPD patients and 54 control subjects.

RESULTS

We found increased concentrations of total Hcy (P < .01) and total CysGly (P < .05) in COPD patients when compared to controls. Total Hcy and CysGly were also significantly associated with abnormal lung function parameters and COPD severity. In COPD patients, total Hcy was significantly associated with the Kyn/Trp ratio (P = .0017) whereas total CysGly was significantly associated with both PSH (P = .0298) and the Kyn/Trp ratio (P = <.0001).

CONCLUSION

Both total Hcy and CysGly concentrations were significantly associated with the presence and severity of COPD and with markers of oxidative stress (total CysGly) and inflammation (total Hcy and CysGly). This suggests that specific low molecular mass thiols might play a role in the inflammatory and oxidative stress pathways involved in both CVD and COPD.

Asymmetric Dimethylarginine Levels and Its Correlation to Cerebral Blood Flow in Children with Sickle Cell Anemia

Asymmetric dimethylarginine (ADMA) level may play a role in the pathogenesis of cerebrovascular stroke in Children with Sickle Cell Anemia (SCA). To assess the plasma level of ADMA in children with SCA and its correlation to cerebral blood flow. This is a cross sectional study was carried out on 30 children with homozygous SCA under follow up in the Out Patients Clinic, Pediatric Department at Tanta University Hospital and 30 healthy children as a control group. Both groups had undergone the following investigations: Complete blood count, lactate dehydrogenase enzyme, and plasma level of ADMA by a commercial ADMA ELISA Kit. Trans-cranial Doppler were done for both groups. ADMA plasma level was significantly higher in-patient group in comparison to the control group (p < 0.001), with a mean value 1.43 ± 0.20 μmol/l, 0.48 ± 0.16 μmol/l respectively. The time-averaged mean maximum velocities for middle cerebral artery, anterior cerebral artery, inferior cerebral artery and posterior cerebral artery were significantly different between patient and control group, p < 0.05. Trans-cranial Doppler data revealed that, 86.7% of patients have low velocity (< 70 cm/s) and 13.3% having very low velocity (< 10 cm/s) while control group have normal velocity. There was a significant negative correlation between ADMA plasma levels and cerebral blood flow. Elevated ADMA levels may have a role in the pathogenesis of the decreased cerebral blood flow in children with SCA.

Differences in plasma amino acid levels in patients with and without bacterial infection during the early stage of acute exacerbation of COPD

PURPOSE

No consensus has been reached regarding appropriate nutritional intervention and rehabilitation during early acute exacerbation of COPD (AECOPD). Given the individual differences in symptoms of AECOPD, patients should be classified by their pathology. For example, it is known that there are differences in the inflammatory response between AECOPD with and without bacterial infection. However, there have been few reports on AECOPD from a nutritional perspective. The aim of this study was to investigate amino acid levels in patients with AECOPD.

PATIENTS AND METHODS

Blood was collected from patients who were hospitalized with AECOPD and from patients with COPD that was in a stable state. We divided the patients with AECOPD into those without bacterial infection (group A) and those with bacterial infection (group B). The patients with COPD that was stable served as controls (group C). The plasma levels of 9 essential amino acids, 13 nonessential amino acids, and total amino acids were compared between the three groups.

RESULTS

In the early stages of AECOPD, differences in plasma levels of only three amino acids (glycine, phenylalanine, and arginine) were observed between groups C and A. Differences in total amino acids and 13 amino acids were observed between groups C and B. Group B had lower levels of total amino acids and of seven amino acids (asparagine, citrulline, glutamine, histidine, methionine, serine, and threonine) compared with the other study groups.

CONCLUSION

The findings of this study show that amino acid levels in plasma differ in patients with AECOPD depending on whether or not bacterial infection is present. Our results suggest that specific amino acids (ie, asparagine, citrulline, glutamine, histidine, serine, and threonine) have potential utility as diagnostic markers to distinguish between bacterial and nonbacterial AECOPD.

Circulating serotonin levels in COPD patients: a pilot study

Background

Chronic obstructive pulmonary disease (COPD) is a major and increasing global health problem. Serotonin is a neurotransmitter that participates in several pulmonary functions and it has been involved in oxidative stress, which plays essential roles in the pathogenesis of COPD. The current study aimed at establishing the levels of circulating serotonin in COPD, and investigating eventual relations between serotonin and oxidative stress markers.

Methods

Whole blood serotonin was assessed in 43 consecutive patients with stable COPD and in 43 age and sex-matched healthy controls.

Results

Serotonin blood levels were significantly higher in COPD patients than in controls (median 0.81 μmol/L, IQR: 0.61–4.02 vs 0.65 μmol/L, IQR: 0.53–1.39, p = 0.02). The univariate logistic regression analysis evidenced that serotonin levels are independently associated with presence of COPD (crude OR = 7.29, 95% CI: 1.296–41.05, p = 0.003) and such an association was confirmed also after adjusting for several confounders (OR 21.92, 95% CI 2.02–237.83; p = 0.011).

Conclusions

Our study showed higher levels of circulating serotonin in COPD and an inverse correlation with the worsening of airway obstruction. Future studies are necessary to investigate the clinical utility of this finding.

Systemic concentrations of asymmetric dimethylarginine (ADMA) in chronic obstructive pulmonary disease (COPD): state of the art

Experimental evidence suggests that oxidative stress (OS) may increase the activity of arginine methylating enzymes that produce the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA). In addition, it is well documented that OS can significantly decrease the synthesis and/or activity of ADMA degrading enzymes, thus causing ADMA accumulation in biological fluids. Recent reports have focused on circulating methylated arginine concentrations in chronic obstructive pulmonary disease, a disease characterized by a significant increase in OS. This review discusses the results of these studies and the opportunities for further research in this area.

Circulating malondialdehyde concentrations in patients with stable chronic obstructive pulmonary disease: a systematic review and meta-analysis

The aim of this meta-analysis was to review the available evidence regarding the blood concentrations of the oxidative stress marker malondialdehyde (MDA) in chronic obstructive pulmonary disease (COPD) patients in comparison to healthy individuals. 14 studies were included in the meta-analysis (from inception to October 2017) with a total of 817 COPD patients and 530 healthy controls. Pooled MDA concentrations were significantly higher in patients with COPD than controls (standardized mean differences = 2.39 μmol/l, 95% CI: 1.50-3.28 μmol/l; p < 0.001). Our meta-analysis showed that the blood concentrations of MDA are consistently higher in patients with COPD when compared with healthy controls, suggesting an important role of lipid peroxidation, and thus oxidative stress, in the pathogenesis of COPD.

Increased kynurenine plasma concentrations and kynurenine-tryptophan ratio in mild-to-moderate chronic obstructive pulmonary disease patients

AIM

Since an increase in kynurenine (Kyn) plasma concentrations has been proposed as marker of immune system activation, we studied the associations between the Kyn levels and presence and severity of chronic obstructive pulmonary disease (COPD).

METHODS & RESULTS

Plasma Kyn, tryptophan (Trp) and Kyn/Trp ratio were measured in 43 COPD patients with clinically defined mild (n = 29) or moderate (n = 14) disease and 43 age- and sex-matched healthy controls. When compared with controls, COPD patients had significantly higher plasma Kyn concentrations and Kyn/Trp ratios. In multiple logistic regression analysis, after adjusting for clinical and demographic confounders, the Kyn/Trp ratio was independently associated with COPD severity.

DISCUSSION & CONCLUSION

Kyn and Kyn/Trp ratio might represent a new, sensitive, biomarker of systemic inflammation in COPD patients.

Phenotyping of Chronic Obstructive Pulmonary Disease Based on the Integration of Metabolomes and Clinical Characteristics

Apart from the refined management-oriented clinical stratification of chronic obstructive pulmonary disease (COPD), the molecular pathologies behind this highly prevalent disease have remained obscure. The aim of this study was the characterization of patients with COPD, based on the metabolomic profiling of peripheral blood and exhaled breath condensate (EBC) within the context of defined clinical and demographic variables. Mass-spectrometry-based targeted analysis of serum metabolites (mainly amino acids and lipid species), untargeted profiles of serum and EBC of patients with COPD of different clinical characteristics (n = 25) and control individuals (n = 21) were performed. From the combined clinical/demographic and metabolomics data, associations between clinical/demographic and metabolic parameters were searched and a de novo phenotyping for COPD was attempted. Adjoining the clinical parameters, sphingomyelins were the best to differentiate COPD patients from controls. Unsaturated fatty acid-containing lipids, ornithine metabolism and plasma protein composition-associated signals from the untargeted analysis differentiated the Global Initiative for COPD (GOLD) categories. Hierarchical clustering did not reveal a clinical-metabolomic stratification superior to the strata set by the GOLD consensus. We conclude that while metabolomics approaches are good for finding biomarkers and clarifying the mechanism of the disease, there are no distinct co-variate independent clinical-metabolic phenotypes.

Recent advances in amino acid analysis by capillary electromigration methods: June 2015-May 2017

In the tenth edition of this article focused on recent advances in amino acid analysis using capillary electrophoresis, we describe the most important research articles published on this topic during the period from June 2015 to May 2017. This article follows the format of the previous articles published in Electrophoresis. The new developments in amino acid analysis with CE mainly describe improvements in CE associated with mass spectrometry. Focusing on applications, we mostly describe clinical works, although metabolomics studies are also very important. Finally, works focusing on amino acids in food and agricultural applications are also described.

Blood global DNA methylation is decreased in non-severe chronic obstructive pulmonary disease (COPD) patients

BACKGROUND

Alterations in global DNA methylation have been associated with oxidative stress (OS). Since chronic obstructive pulmonary disease (COPD) is characterized by increased oxidative stress we aimed to evaluate the levels of global DNA methylation in this patient group.

METHODS

We assessed methylcytosine (mCyt) levels in DNA from blood collected in 43 COPD patients (29 with mild and 14 with moderate disease) and 43 age- and sex-matched healthy controls.

RESULTS

DNA methylation was significantly lower in COPD patients vs. controls (4.20 ± 0.18% mCyt vs. 4.29 ± 0.18% mCyt, p = 0.02). Furthermore, DNA methylation in COPD patients with moderate disease was significantly lower than that in patients with mild disease (4.14 ± 0.15% mCyt vs. 4.23 ± 0.19% mCyt, p < 0.05). Univariate logistic regression analysis showed that lower DNA methylation levels were associated with presence of COPD (crude OR = 0.06, 95% CI 0.00 to 0.67, p = 0.023). This relationship remained significant after adjusting for several confounders (OR 0.03, 95% CI 0.00 to 0.67; p = 0.028). Receiver operating characteristics (ROC) curve analysis demonstrated the area under the curve of mCyt was 0.646, with 46.6% sensitivity and 79.1% specificity for presence of COPD.

CONCLUSIONS

There were no significant correlations between methylation and OS indices. The presence and severity of COPD is associated with progressively lower DNA methylation in blood. However, this epigenetic alteration seems independent of oxidative stress.

The ADMA/DDAH/NO pathway in human vein endothelial cells exposed to arsenite

Inorganic arsenic (iAs) exposure is related to cardiovascular disease, which is characterized by endothelial dysfunction and nitric oxide (NO) depletion. The mechanisms underlying NO depletion as related to iAs exposure are not fully understood. The endogenous inhibitor of nitric oxide synthase, asymmetric dimethylarginine (ADMA), might be a molecular target of iAs. ADMA concentrations are regulated by proteins involved in its synthesis (arginine methyl transferase 1 [PRMT-1]) and degradation (dimethylarginine dimethylaminohydrolase [DDAH]). Both, ADMA and NO are susceptible to oxidative stress. We aimed to determine the ADMA/DDAH/NO pathway in human vein endothelial cells (HUVEC-CS) exposed to arsenite. We exposed HUVEC-CS cells to 1, 2.5 and 5μM of arsenite for 24h. We proved that arsenite at 5μM was able to decrease NO levels with an associated increase in ADMA and depletion of l-arginine in HUVEC-CS cells. We also found a decrease in DDAH-1 protein expression with 5μM of arsenite compared to the control group. However, we did not observe significant differences in PRMT-1 protein expression at any of the concentrations of arsenite employed. Finally, arsenite (2.5 and 5μM) increased NADPH oxidase 4 protein levels compared with the control group. We conclude that ADMA, l-arginine and DDAH are involved in NO depletion produced by arsenite, and that the mechanism is related to oxidative stress.