Increase of nitrosative stress in patients with eosinophilic pneumonia

Idiopathic pulmonary fibrosis (IPF): Diagnostic routes using novel biomarkers

Idiopathic pulmonary fibrosis (IPF) diagnosis is still the diagnosis of exclusion. Differentiating from other forms of interstitial lung diseases (ILDs) is essential, given the various therapeutic approaches. The IPF course is now unpredictable for individual patients, although some genetic factors and several biomarkers have already been associated with various IPF prognoses. Since its early stages, IPF may be asymptomatic, leading to a delayed diagnosis. The present review critically examines the recent literature on molecular biomarkers potentially useful in IPF diagnostics. The examined biomarkers are grouped into breath and sputum biomarkers, serologically assessed extracellular matrix neoepitope markers, and oxidative stress biomarkers in lung tissue. Fibroblasts and complete blood count have also gained recent interest in that respect. Although several biomarker candidates have been profiled, there has yet to be a single biomarker that proved specific to the IPF disease. Nevertheless, various IPF biomarkers have been used in preclinical and clinical trials to verify their predictive and monitoring potential.

Understanding the role of S-nitrosylation/nitrosative stress in inflammation and the role of cellular denitrosylases in inflammation modulation: Implications in health and diseases

S-nitrosylation is a very fundamental post-translational modification of protein and non-protein thiols due the involvement of it in a variety of cellular processes including activation/inhibition of several ion channels such as ryanodine receptor in the cardiovascular system; blood vessel dilation; cGMP signaling and neurotransmission. S-nitrosothiol homeostasis in the cell is tightly regulated and perturbations in homeostasis result in an altered redox state leading to a plethora of disease conditions. However, the exact role of S-nitrosylated proteins and nitrosative stress metabolites in inflammation and in inflammation modulation is not well-reviewed. The cell utilizes its intricate defense mechanisms i.e. cellular denitrosylases such as Thioredoxin (Trx) and S-nitrosoglutathione reductase (GSNOR) systems to combat nitric oxide (NO) pathology which has also gained current attraction as novel anti-inflammatory molecules. This review attempts to provide state-of-the-art knowledge from past and present research on the mechanistic role of nitrosative stress intermediates (RNS, OONO^-, PSNO) in pulmonary and autoimmune diseases and how cellular denitrosylases particularly GSNOR and Trx via imparting opposing effects can modulate and reduce inflammation in several health and disease conditions. This review would also bring into notice the existing gaps in current research where denitrosylases can be utilized for ameliorating inflammation that would leave avenues for future therapeutic interventions.

Clinical Values of Nitric Oxide Parameters from the Respiratory System

BACKGROUND

Fractional exhaled nitric oxide (FENO) concentration reliably reflects central airway inflammation, but it is not sensitive to changes in the NO dynamics in the lung periphery. By measuring FENO at several different flow rates one can estimate alveolar NO concentration (C_ANO), bronchial NO flux (J_awNO), bronchial wall NO concentration (C_awNO) and the bronchial diffusivity of NO (D_awNO).

OBJECTIVE

We aimed to describe the current knowledge and clinical relevance of NO parameters in different pulmonary diseases.

METHODS

We conducted a systematic literature search to identify publications reporting NO parameters in subjects with pulmonary or systemic diseases affecting the respiratory tract. A narrative review was created for those with clinical relevance.

RESULTS

Estimation of pulmonary NO parameters allows for differentiation between central and peripheral inflammation and a more precise analysis of central airway NO output. C_ANO seems to be a promising marker of parenchymal inflammation in interstitial lung diseases and also a marker of tissue damage and altered gas diffusion in chronic obstructive pulmonary disease and systemic diseases affecting the lung. In asthma, C_ANO can detect small airway involvement left undetected by ordinary FENO measurement. Additionally, C_awNO and D_awNO can be used in asthma to assess if FENO is increased due to enhanced inflammatory activity (increased C_awNO) or tissue changes related to bronchial remodelling (altered D_awNO).

CONCLUSION

NO parameters may be useful for diagnosis, prediction of disease progression and prediction of treatment responses in different parenchymal lung and airway diseases. Formal trials to test the added clinical value of NO parameters are needed.

The comparision of two exhaled nitric oxide analyzers: NIOX VERO and SUNVOU-CA2122

BACKGROUND

As a marker of eosinophilic airway inflammation, fractional exhaled nitric oxide (FeNO) was widely used in clinical practice. NIOX VERO (VERO) and SUNVOU-CA2122 (CA2122) are two commonly used exhaled nitric oxide (eNO) analyzers in China. However, what's the difference and agreement between the two devices and whether the two types of devices can be replaced by each other in the application of common respiratory diseases have not been reported.

OBJECTIVES

The purpose of this study was to compare the two types of devices and to evaluate the difference between them in clinical use and whether they could be replaced.

METHODS

FeNO levels in 244 respiratory patients (including asthma, COPD, chronic cough) were measured by SUNVOU-CA2122 analyzer (CA2122) and NIOX VERO analyzer (VERO), respectively. FeNO values obtained by the two devices were compared and analyzed for the difference. The success rate, the number of attempts and the total time required for a successful measurement by CA2122 and VERO were compared. The FeNO values measured offline by CA2122 were compared with FeNO values measured online by CA2122 and VERO.

RESULTS

FeNO values obtained by CA2122 were slightly higher than those of VERO [median(range): 29.0(9-271) ppb vs 25.5 (5-263) ppb, P=0.000]. There was a high correlation between FeNO values measured by the two types of devices (r = 0.964, P= 0.000). By comparison, there was a high degree of agreement between the FeNO values measured by two devices, in all patients with different respiratory diseases. FeNO values measured online and offline by CA2122 were highly correlated and there was a high degree of agreement between online and offline methods. The success rate of CA2122 was higher than VERO, and the number of attempts (2.1 vs 2.4) and the total time (110.5±35.7 vs 117.5±48.1 seconds) required for a successful measurement by CA2122 were lower than those of VERO.

CONCLUSIONS

CA2122 and VERO can be replaced by each other, and FeNO values can be converted if necessary. CA2122 has some advantages in success rate, the mean attempts and time required for successful measurement of FeNO.

Extended Exhaled Nitric Oxide Analysis in Interstitial Lung Diseases: A Systematic Review

Fractional exhaled nitric oxide (FeNO) is a well-known and widely accepted biomarker of airways inflammation that can be useful in the therapeutic management, and adherence to inhalation therapy control, in asthmatic patients. However, the multiple-flows assessment of FeNO can provide a reliable measurement of bronchial and alveolar production of NO, supporting its potential value as biomarker also in peripheral lung diseases, such as interstitial lung diseases (ILD). In this review, we first discuss the role of NO in the pathobiology of lung fibrosis and the technique currently approved for the measurement of maximum bronchial flux of NO (J'awNO) and alveolar concentration of NO (CaNO). We systematically report the published evidence regarding extended FeNO analysis in the management of patients with different ILDs, focusing on its potential role in differential diagnosis, prognostic evaluation and severity assessment of disease. The few available data concerning extended FeNO analysis, and the most common comorbidities of ILD, are explored too. In conclusion, multiple-flows FeNO analysis, and CaNO in particular, appears to be a promising tool to be implemented in the diagnostic and prognostic pathways of patients affected with ILDs.

An official JRS statement: The principles of fractional exhaled nitric oxide (FeNO) measurement and interpretation of the results in clinical practice

Nitric oxide (NO) is produced in the body and has been shown to have diverse actions in the abundance of research that has been performed on it since the 1970s, leading to Furchgott, Murad, and Ignarro receiving the Nobel Prize in Physiology or Medicine in 1998. NO is produced by nitric oxide synthase (NOS). NOS is broadly distributed, being found in the nerves, blood vessels, airway epithelium, and inflammatory cells. In asthma, inflammatory cytokines induce NOS activity in the airway epithelium and inflammatory cells, producing large amounts of NO. Measurement of fractional exhaled nitric oxide (FeNO) is a simple, safe, and quantitative method of assessing airway inflammation. The FeNO measurement method has been standardized and, in recent years, this noninvasive test has been broadly used to support the diagnosis of asthma, monitor airway inflammation, and detect asthma overlap in chronic obstructive pulmonary disease (COPD) patients. Since the normal upper limit of FeNO for healthy Japanese adults is 37 ppb, values of 35 ppb or more are likely to be interpreted as a signature of inflammatory condition presenting features with asthma, and this value is used in clinical practice. Research is also underway for clinical application of these measurements in other respiratory diseases such as COPD and interstitial lung disease. Currently, there remains some confusion regarding the significance of these measurements and the interpretation of the results. This statement is designed to provide a simple explanation including the principles of FeNO measurements, the measurement methods, and the interpretation of the measurement results.

Myeloid-derived suppressor cells (MDSCs) and mechanistic target of rapamycin (mTOR) signaling pathway interact through inducible nitric oxide synthase (iNOS) and nitric oxide (NO) in asthma

BACKGROUND

Down-regulation of mechanistic target of rapamycin (mTOR) activity in myeloid-derived suppressor cells (MDSCs) has been shown to promote inducible nitric oxide (NO) synthase (iNOS) expression and NO production. Importantly, pharmacological inhibition of iNOS blocks MDSCs recruitment in immunological hepatic injury. As bronchial asthma is also an immune disease, whether mTOR could interact with MDSCs via iNOS and NO or not is unclear.

OBJECTIVE

The aim of this study was to determine whether mTOR could interact with MDSCs via iNOS and NO in asthma.

METHODS

Ovalbumin-induced asthma mouse model was established to perform our investigation, and asthmatic markers were evaluated by hematoxylin and eosin (H&E), immunohistochemistry (IHC), and periodic acid-Schiff (PAS) staining. The levels of iNOS and NO in serum were determined by enzyme linked immunosorbent assay (ELISA). Mice lung tissues were stained with antibodies against phosphorylated (p)-mTOR, and p-p70S6K, and yellow/brown staining was considered as giving a positive signal, meanwhile, the protein levels of p-mTOR, and p-p70S6K were also detected using western blot assay. Mice iNOS activity was determined by radioimmunoassay.

RESULTS

Tumor-derived MDSCs in asthmatic mice were regulated by mTOR and iNOS. mTOR pathway activation in asthmatic mice was regulated by iNOS and tumor-derived MDSCs. NO production in asthmatic mice was regulated by mTOR and tumor-extracted MDSCs. Positive correlation of iNOS with mTOR pathway and serum MDSCs was observed.

CONCLUSION

The data indicated that rapamycin, an inhibitor of mTOR, blocked iNOS and NO production during asthma onset. Thus, our results revealed potential novel targets for asthma therapy.

Breath biomarkers in idiopathic pulmonary fibrosis: a systematic review

BACKGROUND

Exhaled biomarkers may be related to disease processes in idiopathic pulmonary fibrosis (IPF) however their clinical role remains unclear. We performed a systematic review to investigate whether breath biomarkers discriminate between patients with IPF and healthy controls. We also assessed correlation with lung function, ability to distinguish diagnostic subgroups and change in response to treatment.

METHODS

MEDLINE, EMBASE and Web of Science databases were searched. Study selection was limited to adults with a diagnosis of IPF as per international guidelines.

RESULTS

Of 1014 studies screened, fourteen fulfilled selection criteria and included 257 IPF patients. Twenty individual biomarkers discriminated between IPF and controls and four showed correlation with lung function. Meta-analysis of three studies indicated mean (± SD) alveolar nitric oxide (CalvNO) levels were significantly higher in IPF (8.5 ± 5.5 ppb) than controls (4.4 ± 2.2 ppb). Markers of oxidative stress in exhaled breath condensate, such as hydrogen peroxide and 8-isoprostane, were also discriminatory. Two breathomic studies have isolated discriminative compounds using mass spectrometry. There was a lack of studies assessing relevant treatment and none assessed differences in diagnostic subgroups.

CONCLUSIONS

Evidence suggests CalvNO is higher in IPF, although studies were limited by small sample size. Further breathomic work may identify biomarkers with diagnostic and prognostic potential.

Role of thioredoxin nitration in bleomycin-induced pulmonary fibrosis in rats

Oxidant stimulation has been suggested to play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Our study aimed to investigate the role and mechanisms of thioredoxin (Trx) nitration during the development of IPF. A rat model of IPF was established by intratracheal instillation of bleomycin (BLM). Male Wistar rats were randomly distributed among the control group and BLM-treated group, in which rats were intratracheally instilled with a single dose of BLM (5.0 mg/kg body mass in 1.0 mL phosphate-buffered saline). At 7 or 28 days after instillation the rats were euthanized. Histopathological and biochemical examinations were performed. The activity and protein level of thioredoxin were assessed. The thioredoxin nitration level was determined using immunoprecipitation and immunoblotting techniques. Our results demonstrated that protein tyrosine nitration increased in the BLM-treated group compared with the control group. Trx activity decreased in the BLM group compared with control group, whereas Trx expression and nitration level increased dramatically in the BLM group compared with the control group. Our results indicated that Trx nitration might be involved in the pathogenesis of IPF.