Myeloperoxidase-dependent oxidative metabolism of nitric oxide in the cystic fibrosis airway

Fermented Mangosteen (Garcinia mangostana L.) Supplementation in the Prevention of HPV-Induced Cervical Cancer: From Mechanisms to Clinical Outcomes

Simple Summary

Human papillomavirus (HPV) is connected with virtually all cases of cervical cancer. The viral infection-associated chronic inflammation, oxidative stress, and alterations in apoptosis have been considered as leading risk factors for carcinogenesis in humans. In an observational clinical study, we identified oxidative markers and the cervical/circulating ligands of TNF-alpha-induced apoptosis involved in HPV-associated cervical carcinogenesis. In the following clinical trial, 250 females infected with high-cancer-risk HPV16/18 (healthy and pre-cancerous) were recruited into a placebo-controlled clinical study of supplementation with fermented mangosteen (FM, 28g/day, daily) for three months. Our findings indicate that FM, and not a placebo, in combination with routine anti-viral therapy, could prevent, slow down, or even interrupt HPV-associated cervical carcinogenesis, mainly through the suppression of leukocyte recruitment into infected tissue, through anti-inflammatory effects, and through the restoration of nitric oxide metabolite-initiated TRAIL-dependent apoptosis.

Abstract

In the observational clinical study, we identified the oxidative markers of HPV-associated cervical carcinogenesis and the local/circulating ligands of TNF-alpha-induced apoptosis. Cervical biopsies of 196 females infected with low-cancer-risk HPV10/13 or high-cancer-risk HPV16/18 (healthy, pre-cancerous CIN I and CIN II, and CIN III carcinoma) were analysed for OH radical scavenging, catalase, GSH-peroxidase, myeloperoxidase (MPO), nitrate/nitrite, nitrotyrosine, and isoprostane. Ligands of TNF-alpha-dependent apoptosis (TNF-alpha, TRAIL, IL-2, and sFAS) were determined in cervical fluid, biopsies, and serum. Cervical MPO was highly enhanced, while nitrotyrosine decreased in CIN III. Local/circulating TRAIL was remarkably decreased, and higher-than-control serum TNF-alpha and IL-2 levels were found in the CIN I and CIN III groups. Then, 250 females infected with HPV16/18 (healthy and with CIN I and CIN II) were recruited into a placebo-controlled clinical study of supplementation with fermented mangosteen (FM, 28g/day, daily) for three months. Post-trial colposcopy revealed normal patterns in 100% of the FM group versus 62% of the placebo group. Inflammatory cells in cervical fluid were found in 21% of the FM group versus 40% of the placebo group. Locally, FM drastically diminished MPO and NO₂/NO₃, while it remarkably increased TRAIL. Additionally, FM supplementation normalised serum TRAIL, TNF-alpha, and IL-2.

Withania somnifera (L.) Dunal as Add-On Therapy for COPD Patients: A Randomized, Placebo-Controlled, Double-Blind Study

Background: The current gold-standard therapies for chronic obstructive pulmonary disease (COPD) lack disease-modifying potential and exert adverse side effects. Moreover, COPD patients are at a higher risk of severe outcomes if they get infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, the cause of the current epidemic. This is the first study to document clinical research on an adaptogenic and steroidal activity–containing herb as a complementary medicine for COPD treatment.

Objective: We aimed to evaluate the efficacy of Withania somnifera (L.) Dunal [Solanaceae] (WS) as an add-on therapy for COPD patients.

Methods: A randomized, placebo-controlled, and double-blind clinical study was conducted. A total of 150 patients were randomly assigned to three groups: control, placebo, and WS group. In addition to conventional medicines, WS root capsules or starch capsules were given twice a day to the WS group and the placebo group, respectively. Their lung functioning, quality of life, exercise tolerance, systemic oxidative stress (OS), and systemic inflammation were assessed before and after 12 weeks of intervention. WS root phytochemicals were identified by LC-ESI-MS. The inhibitory activity of these phytochemicals against angiotensin-converting enzyme 2 (ACE-2); the SARS-CoV-2 receptor; myeloperoxidase (MPO); and interleukin-6 (IL-6) was evaluated by in silico docking to investigate the mechanism of action of WS.

Results: The pulmonary functioning, quality of life, and exercise tolerance improved, and inflammation reduced notably the most in the WS group. Systemic oxidative stress subsided significantly only in the WS group. Although a minor placebo effect was observed in the SGRQ test, but it was not present in other tests. Withanolides found in the WS roots demonstrated substantial inhibitory activity against the proteins ACE-2, MPO, and IL-6, compared to that of a standard drug or known inhibitor. Moreover, FEV1% predicted had significant correlation with systemic antioxidative status (positive correlation) and malondialdehyde (MDA, negative correlation), suggesting that the antioxidative potential of WS has significant contribution to improving lung functioning.

Conclusion: Our study clinically demonstrated that WS root when given along with conventional drugs ameliorated COPD significantly more in comparison to the conventional drugs alone, in GOLD 2 and 3 categories of COPD patients. In silico, it has potent inhibitory activity against SARS-CoV-2 receptor, ACE-2, MPO, and IL-6.

[Usefulness of measurement of nitric oxide in exhaled air in diagnostics and treatment of allergic rhinitis and asthma in children and adolescents]

Nitric oxide is produced by enzymes called nitric oxide synthases. It fulfills many important functions in the human body, but produced in excess amount has a proinflammatory activity. Fractional exhaled nitric oxide measurements are used in the diagnosis and monitoring of eosinophilic inflammation in the lower airways, but should not be used as an independent parameter to make a diagnosis of asthma or for the monitoring of asthma treatment. Evaluation of fractional exhaled nitric oxide concentrations is also used to determine the pathogenesis of symptoms in patients with rhinitis. In addition, they are helpful in detecting and monitoring eosinophilic inflammation in the lower respiratory tract that coexists with inflammation in the upper airways. Fractional exhaled nitric oxide concentrations may be abnormal (lowered or elevated) in other chronic diseases, such as cystic fibrosis, primary ciliary dyskinesia and inflammatory bowel diseases. Many factors, e.g. atopy, genetic polymorphisms of NOS, and the lipid profile affect the fractional exhaled nitric oxide measurement. Nasal nitric oxide measurement is useful in assessing the prevalence and severity of eosinophilic inflammation in the upper respiratory tract.

Bis(phenylimidazoselenazolyl) diselenide elicits antinociceptive effect by modulating myeloperoxidase activity, NOx and NFkB levels in the collagen-induced arthritis mouse model

Bis(phenylimidazoselenazolyl) diselenide (BPIS) is an organoselenium with acute antinociceptive and antioxidant properties.

OBJECTIVES

The aim of this study was to investigate BPIS effect on a collagen-induced arthritis (CIA) model in mice.

METHODS

Protocol of exposure consisted in arthritis induction by chicken collagen type II on day 0 with booster injection on day 21. On day 60 after collagen injection, incidence of mechanic allodynia (Von Frey test) or thermal hyperalgesia (hot plate test) was evaluated. During following 5 days, mice were treated with BPIS (0.1-1 mg/kg; p.o.; daily) or vehicle. On day 65, mice were killed, and paws and spinal cord were removed for analyses.

KEY FINDINGS

Mice submitted to CIA model developed both mechanical allodynia and thermal hyperalgesia, which were reversed by BPIS at the highest dose. In paw, BPIS reversed the increase in myeloperoxidase activity in the CIA group. In the spinal cord, BPIS decreased NOx and NFkB levels increased in the CIA group. BPIS-treated animals had lower cyclooxygenase-2 levels in the spinal cord.

CONCLUSIONS

The myeloperoxidase activity in paw and NOx and NFkB levels in spinal cord are related to antinociceptive properties of BPIS in CIA model.

Regulation of the nitric oxide oxidase activity of myeloperoxidase by pharmacological agents

The leukocyte-derived heme enzyme myeloperoxidase (MPO) is released extracellularly during inflammation and impairs nitric oxide (NO) bioavailability by directly oxidizing NO or producing NO-consuming substrate radicals. Here, structurally diverse pharmacological agents with activities as MPO substrates/inhibitors or antioxidants were screened for their effects on MPO NO oxidase activity in human plasma and physiological model systems containing endogenous MPO substrates/antioxidants (tyrosine, urate, ascorbate). Hydrazide-based irreversible/reversible MPO inhibitors (4-ABAH, isoniazid) or the sickle cell anaemia drug, hydroxyurea, all promoted MPO NO oxidase activity. This involved the capacity of NO to antagonize MPO inhibition by hydrazide-derived radicals and/or the ability of drug-derived radicals to stimulate MPO turnover thereby increasing NO consumption by MPO redox intermediates or NO-consuming radicals. In contrast, the mechanism-based irreversible MPO inhibitor 2-thioxanthine, potently inhibited MPO turnover and NO consumption. Although the phenolics acetaminophen and resveratrol initially increased MPO turnover and NO consumption, they limited the overall extent of NO loss by rapidly depleting H₂O₂ and promoting the formation of ascorbyl radicals, which inefficiently consume NO. The vitamin E analogue trolox inhibited MPO NO oxidase activity in ascorbate-depleted fluids by scavenging NO-consuming tyrosyl and urate radicals. Tempol and related nitroxides decreased NO consumption in ascorbate-replete fluids by scavenging MPO-derived ascorbyl radicals. Indoles or apocynin yielded marginal effects. Kinetic analyses rationalized differences in drug activities and identified criteria for the improved inhibition of MPO NO oxidase activity. This study reveals that widely used agents have important implications for MPO NO oxidase activity under physiological conditions, highlighting new pharmacological strategies for preserving NO bioavailability during inflammation.

Application of nitric oxide measurements in clinical conditions beyond asthma

Fractional exhaled nitric oxide (FeNO) is a convenient, non-invasive method for the assessment of active, mainly Th2-driven, airway inflammation, which is sensitive to treatment with standard anti-inflammatory therapy. Consequently, FeNO serves as a valued tool to aid diagnosis and monitoring in several asthma phenotypes. More recently, FeNO has been evaluated in several other respiratory, infectious, and/or immunological conditions. In this short review, we provide an overview of several clinical studies and discuss the status of potential applications of NO measurements in clinical conditions beyond asthma.

Lung arginase expression and activity is increased in cystic fibrosis mouse models

The activity of arginase is increased in airway secretions of patients with cystic fibrosis (CF). Downstream products of arginase activity may contribute to CF lung disease. We hypothesized that pulmonary arginase expression and activity would be increased in mouse models of CF and disproportionally increased in CF mice with Pseudomonas aeruginosa pneumonia. Expression of arginase isoforms in lung tissue was quantified with reverse transcriptase-PCR in naive cystic fibrosis transmembrane conductance regulator ( Cftr)-deficient mice and β-epithelial sodium channel-overexpressing [β-ENaC-transgenic (Tg)] mice. An isolated lung stable isotope perfusion model was used to measure arginase activity in Cftr-deficient mice before and after intratracheal instillation of Pseudomonas aeruginosa. The expression of arginase-2 in lung was increased in adult Cftr-deficient animals and in newborn β-ENaC-Tg. Arginase-1 lung expression was normal in Cftr-deficient and in newborn β-ENaC-Tg mice, but was increased in β-ENaC-Tg mice at age 1, 3, and 6 wk. Arginase activity was significantly higher in lung (5.0 ± 0.7 vs. 3.2 ± 0.3 nmol·−1·h−1, P = 0.016) and airways (204.6 ± 49.8 vs. 79.3 ± 17.2 nmol·−1·h−1, P = 0.045) of naive Cftr-deficient mice compared with sex-matched wild-type littermate controls. Infection with Pseudomonas aeruginosa resulted in a far greater increase in lung arginase activity in Cftr-deficient mice (10-fold) than in wild-type controls (6-fold) ( P = 0.01). This is the first ex vivo characterization of arginase expression and activity in CF mouse lung and airways. Our data show that pulmonary arginase expression and activity is increased in CF mice, especially with Pseudomonas aeruginosa infections.

Mechanism and regulation of peroxidase-catalyzed nitric oxide consumption in physiological fluids: critical protective actions of ascorbate and thiocyanate

Catalytic consumption of nitric oxide (NO) by myeloperoxidase and related peroxidases is implicated as playing a key role in impairing NO bioavailability during inflammatory conditions. However, there are major gaps in our understanding of how peroxidases consume NO in physiological fluids, in which multiple reactive enzyme substrates and antioxidants are present. Notably, ascorbate has been proposed to enhance myeloperoxidase-catalyzed NO consumption by forming NO-consuming substrate radicals. However, we show that in complex biological fluids ascorbate instead plays a critical role in inhibiting NO consumption by myeloperoxidase and related peroxidases (lactoperoxidase, horseradish peroxidase) by acting as a competitive substrate for protein-bound redox intermediates and by efficiently scavenging peroxidase-derived radicals (e.g., urate radicals), yielding ascorbyl radicals that fail to consume NO. These data identify a novel mechanistic basis for how ascorbate preserves NO bioavailability during inflammation. We show that NO consumption by myeloperoxidase Compound I is significant in substrate-rich fluids and is resistant to competitive inhibition by ascorbate. However, thiocyanate effectively inhibits this process and yields hypothiocyanite at the expense of NO consumption. Hypothiocyanite can in turn form NO-consuming radicals, but thiols (albumin, glutathione) readily prevent this. Conversely, where ascorbate is absent, glutathione enhances NO consumption by urate radicals via pathways that yield S-nitrosoglutathione. Theoretical kinetic analyses provide detailed insights into the mechanisms by which ascorbate and thiocyanate exert their protective actions. We conclude that the local depletion of ascorbate and thiocyanate in inflammatory microenvironments (e.g., due to increased metabolism or dysregulated transport) will impair NO bioavailability by exacerbating peroxidase-catalyzed NO consumption.

Myeloperoxidase: a leukocyte-derived protagonist of inflammation and cardiovascular disease

SIGNIFICANCE

The heme-enzyme myeloperoxidase (MPO) is one of the major neutrophil bactericidal proteins and is stored in large amounts inside azurophilic granules of neutrophils. Upon cell activation, MPO is released and extracellular MPO has been detected in a wide range of acute and chronic inflammatory conditions. Recent ADVANCES AND CRITICAL ISSUES: Apart from its role during infection, MPO has emerged as a critical modulator of inflammation throughout the last decade and is currently discussed in the initiation and propagation of cardiovascular diseases. MPO-derived oxidants (e.g., hypochlorous acid) interfere with various cell functions and contribute to tissue injury. Recent data also suggest that MPO itself exerts proinflammatory properties independent of its catalytic activity. Despite advances in unraveling the complex action of MPO and MPO-derived oxidants, further research is warranted to determine the precise nature and biological role of MPO in inflammation.

FUTURE DIRECTIONS

The identification of MPO as a central player in inflammation renders this enzyme an attractive prognostic biomarker and a potential target for therapeutic interventions. A better understanding of the (patho-) physiology of MPO is essential for the development of successful treatment strategies in acute and chronic inflammatory diseases.

Molecular profiling of the human nasal epithelium: A proteomics approach

A comprehensive proteomic profiling of nasal epithelium (NE) is described. This study relies on simple subcellular fractionation used to obtain soluble- and membrane-enriched fractions followed by 2-dimensional liquid chromatography (2D-LC) separation and tandem mass spectrometry (MS/MS). The cells were collected using a brushing technique applied on NE of clinically evaluated volunteers. Subsequently, the soluble- and the membrane-protein enriched fractions were prepared and analyzed in parallel using 2D-LC-MS/MS. In a set of 1482 identified proteins, 947 (63.9%) proteins were found to be associated to membrane fraction. Grand average hydropathy value index (GRAVY) analysis, the transmembrane protein mapping and annotations of primary location deposited in the Human Protein Reference Database (HPRD) confirmed an enrichment of hydrophobic proteins on this dataset. Ingenuity Pathway Analysis (IPA) of soluble fraction revealed an enrichment of molecular and cellular functions associated with cell death, protein folding and drug metabolism while in membrane fraction showed an enrichment of functions associated with molecular transport, protein trafficking and cell-to-cell signaling and interaction. The IPA showed similar enrichment of functions associated with cellular growth and proliferation in both soluble and membrane subproteomes. This finding was in agreement with protein content analysis using exponentially modified protein abundance index (emPAI). A comparison of our data with previously published studies focusing on respiratory tract epithelium revealed similarities related to identification of proteins associated with physical barrier function and immunological defence. In summary, we extended the NE molecular profile by identifying and characterizing proteins associated to pivotal functions of a respiratory epithelium, including the control of fluid volume and ionic composition at the airways' surface, physical barrier maintenance, detoxification and immunological defence. The extent of similarities supports the applicability of a less invasive analysis of NE to assess prognosis and treatment response of lung diseases such as asthma, cystic fibrosis and chronic obstructive pulmonary disease.

Concentration of the antibacterial precursor thiocyanate in cystic fibrosis airway secretions

A recently discovered enzyme system produces antibacterial hypothiocyanite (OSCN(-)) in the airway lumen by oxidizing the secreted precursor thiocyanate (SCN(-)). Airway epithelial cultures have been shown to secrete SCN(-) in a CFTR-dependent manner. Thus, reduced SCN(-) availability in the airway might contribute to the pathogenesis of cystic fibrosis (CF), a disease caused by mutations in the CFTR gene and characterized by an airway host defense defect. We tested this hypothesis by analyzing the SCN(-) concentration in the nasal airway surface liquid (ASL) of CF patients and non-CF subjects and in the tracheobronchial ASL of CFTR-ΔF508 homozygous pigs and control littermates. In the nasal ASL, the SCN(-) concentration was ~30-fold higher than in serum independent of the CFTR mutation status of the human subject. In the tracheobronchial ASL of CF pigs, the SCN(-) concentration was somewhat reduced. Among human subjects, SCN(-) concentrations in the ASL varied from person to person independent of CFTR expression, and CF patients with high SCN(-) levels had better lung function than those with low SCN(-) levels. Thus, although CFTR can contribute to SCN(-) transport, it is not indispensable for the high SCN(-) concentration in ASL. The correlation between lung function and SCN(-) concentration in CF patients may reflect a beneficial role for SCN(-).

Evaluation of thiol-based antioxidant therapeutics in cystic fibrosis sputum: Focus on myeloperoxidase

Neutrophil-dependent reactions catalysed by myeloperoxidase (MPO) are thought to play important roles in the pulmonary pathobiology of cystic fibrosis (CF). Aerosolized thiol antioxidants such as glutathione (GSH) and N-acetylcysteine (NAC) are currently being utilized as therapeutics to modify CF respiratory tract oxidative processes. This study hypothesized that MPO in CF airway lining fluids may be a target of such therapeutics. MPO activity in sputum from 21 adult CF patients was found to be inversely associated with lung function (FEV(1)). In contrast, systemic inflammation (assessed by plasma C-reactive protein) was not correlated with lung function. Ex vivo studies revealed that GSH and NAC effectively scavenged N-chloramines in sputum and inhibited sputum MPO activity with potency exquisitely dependent upon MPO activity levels. Detailed kinetic analyses revealed that NAC and GSH inhibit MPO by distinct mechanisms. Activation of the key pro-inflammatory transcription factor NF-κB in cultured HBE1 cells was inhibited by GSH. The findings reveal that MPO activity and its reactive products represent useful predictors of the doses of inhaled thiol antioxidants required to ameliorate airway oxidative stress and inflammation in CF patients and provide mechanistic insight into the antioxidative/anti-inflammatory mechanisms of action of GSH and NAC when administered into the CF lung.

Exhaled breath condensate nitrates, but not nitrites or FENO, relate to asthma control

BACKGROUND

Asthma is a chronic respiratory disease, characterised by airways inflammation, obstruction and hyperresponsiveness. Asthma control is the goal of asthma treatment, but many patients have sub-optimal control. Exhaled NO and exhaled breath condensate (EBC) NO metabolites (nitrites and nitrates) measurements are non-invasive tools to assess airways inflammation. Our aim was to investigate the relationships between asthma control and the above-named biomarkers of airways inflammation.

METHODS

Thirty-nine non-smoking asthmatic patients (19 women) aged 50 (21-80) years performed measurements of exhaled NO (FENO), EBC nitrates, nitrites and pH, and answered Asthma Control Questionnaire (ACQ) and Asthma Control Test (ACT)-questionnaire.

RESULTS

The ACT and ACQ score were strongly interrelated (ρ = -0.84, p < 0.001). No relationships between ACT or ACQ score and FENO were found (p > 0.05). EBC nitrates were negatively related to ACT score (ρ = -0.34, p = 0.03) and positively related to ACQ score (ρ = 0.41, p = 0.001) while no relation of EBC nitrites to either ACQ or ACT score was found (p>0.05).

CONCLUSION

EBC nitrates were the only biomarker that was significantly related to asthma control. This suggests that nitrates, but not nitrites or FENO, reflect an aspect of airways inflammation that is closer related to asthma symptoms. Therefore there is a potential role for EBC nitrates in objective assessment of asthma control.