Clinical application of expectorant therapy in chronic inflammatory airway diseases (Review)

cAMP-PDE signaling in COPD: Review of cellular, molecular and clinical features

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death among non-contagious diseases in the world. PDE inhibitors are among current medicines prescribed for COPD treatment of which, PDE-4 family is the predominant PDE isoform involved in hydrolyzing cyclic adenosine monophosphate (cAMP) that regulates the inflammatory responses in neutrophils, lymphocytes, macrophages and epithelial cells The aim of this study is to investigate the cellular and molecular mechanisms of cAMP-PDE signaling, as an important pathway in the treatment management of patients with COPD. In this review, a comprehensive literature review was performed about the effect of PDEs in COPD. Generally, PDEs are overexpressed in COPD patients, resulting in cAMP inactivation and decreased cAMP hydrolysis from AMP. At normal amounts, cAMP is one of the essential agents in regulating metabolism and suppressing inflammatory responses. Low amount of cAMP lead to activation of downstream inflammatory signaling pathways. PDE4 and PDE7 mRNA transcript levels were not altered in polymorphonuclear leukocytes and CD8 lymphocytes originating from the peripheral venous blood of stable COPD subjects compared to healthy controls. Therefore, cAMP-PDE signaling pathway is one of the most important signaling pathways involved in COPD. By examining the effects of different drugs in this signaling pathway critical steps can be taken in the treatment of this disease.

Naringenin Regulates Lipopolysaccharide-Induced Abnormal Airway Surface Liquid Secretion

Airway surface liquid (ASL) is one of the key factors affecting the respiratory system's physiological function. Abnormal ASL secretion can increase the incidence of various respiratory diseases. Lipopolysaccharide (LPS) stimulation can damage the airway epithelial barrier, affect the concentration of ASL contents, and down-regulate ion channel expression, which in turn causes abnormal ASL secretion. Naringenin, which exists in many Citrus foods, has the ability to promote airway surface liquid secretion. This work is designed to investigate the regulatory mechanism of naringenin on LPS-induced abnormal ASL secretion. The effects of naringenin and LPS on the viability of Calu-3 cells were measured by CellTiter 96® AQueous One Solution Cell Proliferation Assay (MTS). ASL secretion volume was measured by a micropipette on air–liquid interface cultured cells. The concentration of Cl−, Na+, lysozyme, and total protein in ASL were respectively measured by assay kits. The mRNA expressions were determined by quantitative real-time polymerase chain reaction, and proteins were measured by enzyme-linked immunosorbent assay. The results indicated that LPS could affect ASL secretion and regulate cystic fibrosis transmembrane conductance regulator (CFTR), aquaporin 1 (AQP1) and aquaporin 5 (AQP5) expression. Naringenin had the ability to regulate the ASL secretion by increasing secretion volume, and Cl− and Na+ concentrations, reducing lysozyme and total protein content, and regulating CFTR, AQP1, and AQP5 expression. This study indicated that naringenin had regulating effects to attenuate LPS-induced abnormal ASL secretion.

Association of Etoricoxib treatment and incident hypoxia in patients with aortic dissection undergoing endovascular aortic repair

OBJECTIVE

The current study was to evaluate the association of Etoricoxib treatment and incident hypoxia among type-B aortic dissection (AD) patients undergoing endovascular aortic repair (EVAR).

METHODS

Patients undergoing EVAR were retrospectively recruited. Based on Etoricoxib use, patients were divided into the non-treated and Etoricoxib-treated groups. Baseline characteristics including demographics, laboratory parameters, characteristics of aortic computer tomography and echocardiography, medications used, and procedural characteristics were collected from the electronic health record.

RESULTS

Compared to non-treated group (n = 36), prevalence of obesity and fever at baseline was higher in Etoricoxib-treated group (n = 24; P < 0.05). Mean number of neutrophils, and mean serum CRP and D-dimer levels were higher in Etoricoxib-treated group (P < 0.05). The overall incidence of hypoxia was lower in Etoricoxib-treated group (44.4% vs 33.4%, P < 0.05). Increase in neutrophils count, serum CRP and D-dimer levels was associated with incident hypoxia, with an odds ratio (OR) of 1.36 (95% confidence interval [CI] 1.07-1.65), 1.44 (95% CI 1.12-1.78) and 1.25 (95% CI 1.01-1.47) respectively. In unadjusted model, Etoricoxib use was associated with a 44% lower odds of incident hypoxia. After adjustment for inflammatory markers, the association between Etoricoxib and incident hypoxia was non-significant, with OR of 0.95% and 95% CI of 0.78-1.06.

CONCLUSION

Compared to patients who did not receive Etoricoxib during hospitalization, those treated with Etoricoxib had lower incidence of hypoxia, which might be attributed to its anti-inflammatory effects.

Jatropha mutabilis, a new source of vitexin: HPLC quantification and pharmacological evaluation

Jatropha mutabilis (Pohl) Baill is an endemic species of the Caatinga biome, little studied in terms of chemical composition. The objective of this work was to develop an analytical methodology to quantify vitexin in the ethanolic extract of J. mutabilis and to evaluate the expectorant and antitussive activities in mice. The expectorant activity was performed by measuring the phenol red obtained from the bronchoalveolar fluid in animals and the antitussive activity was evaluated by the cough method induced by citric acid (0.4 M). The method developed by HPLC-DAD proved to be simple, linear, precise, accurate, robust and specific. Besides, both vitexin (0.2, 1 and 5 mg/kg) and the extract of J. mutabilis (20, 102, 510 mg/kg) showed efficacy in decrease cough and increase aqueous mucus in mice, but vitexin was more potent. Lastly, the identification of vitexin opens the possibility of new studies for J. mutabilis.

Regulation effects of naringin on diesel particulate matter-induced abnormal airway surface liquid secretion

BACKGROUND

PM_2.5 is closely related to the incidence and mortality of respiratory diseases. Diesel particulate matter (DPM) is the main component of particulate air pollution and an important source of PM_2.5.

HYPOTHESIS/PURPOSE

This study mainly explored the effect of DPM on airway surface liquid (ASL) secretion and the regulation of naringin in this process, to evaluate therapeutic potentials of naringin for the treatment of abnormal secretion of the respiratory tract caused by PM_2.5.

METHODS

The concentration of lysozyme was measured by Lysozyme Assay Kit. Total protein content was determined by the BCA Protein Assay Kit. The concentration of cAMP and MUC5AC, expressions of CFTR, AQP1, and AQP5 proteins were measured by ELISA. Expressions of CFTR, AQP1 and AQP5 mRNA were determined by qPCR. Amount of CFTR on the cell membrane was determined by immunofluorescence.

RESULTS

The in vitro and in vivo studies had indicated that DPM could inhibit ASL secretion and increased the viscosity of the liquid. Naringin had the functions to attenuate DPM-induced injury, reduce liquid viscosity by reducing MUC5AC and total protein secretion, increase DPM-induced CFTR, AQP1, and AQP5 mRNA and protein expression, positively regulate apical CFTR insertion and promote CFTR activation by increasing intracellular cAMP.

CONCLUSION

These results demonstrated that naringin had regulating effects on the DPM-induced abnormal secretion of the respiratory tract.

Identification of potential inflammatory inhibitors from Aster tataricus

Aster tataricus L.f. is a traditional Eastern Asian herbal medicine used for the relief of cough-related illnesses. In this study, 32 known compounds and two novel monoterpene glycosides were isolated from the roots of A. tataricus. With the aid of reported data, elucidation of the root-extract components was carried out using a multitude of spectroscopic techniques. All isolates were investigated for their ability to inhibit nitric oxide (NO) secretion in lipopolysaccharide-activated RAW264.7 cells. Compound 7 remarkably suppressed NO production with an IC₅₀ value of 8.5 µM. In addition, compound 7 exhibited significant inhibitory activity against the production of inflammatory cytokines (prostaglandin E₂, interleukin-6, and interleukin-1 beta) and the expression of inflammatory enzymes (inducible nitric oxide synthase and cyclooxygenase-2) via inhibition of nuclear factor-kappa B activation. Moreover, compound 7 effectively prevented the downstream activation of the mitogen-activated protein kinase signaling pathway by inhibiting phosphorylation of c-Jun N-terminal kinases, extracellular signal-regulated kinases, and p38. These results outline compound 7 as a potential inhibitor for the broad treatment of inflammatory diseases, such as atopic dermatitis, asthma, and various allergies.

Analytical and pharmacological validation of the quantification of phenol red in a mouse model: An optimized method to evaluate expectorant drugs

INTRODUCTION

The evaluation of expectorant activity has been extensively studied in murine models, involving the secretion of phenol red in the trachea or bronchus to estimate the secretory capacity of lower airway mucosa. However, differences in the experimental protocols of several studies evidenced the need of to standardize the quantification of phenol red in the bronchoalveolar fluid (BALF).

METHODS

The analytical methodology for the quantification of phenol red in the BALF was optimized by investigation of pH influence, quantity of the alkali agent added and appropriate wavelength for quantification of phenol red by UV-VIS spectroscopy. Different phenol red suspensions (0.05, 0.5, 1.25, 2.5 and 5%) were prepared and administered intraperitoneally in mice at doses 5, 25, 50, 250 or 500 mg/kg.

RESULTS

It was shown that phenol red should be used at dose 500 mg/kg and intraperitoneal administration should be performed from a suspension at 1.25% (w/v). Furthermore, the alkalinizing agent of choice would be NaOH (0.1 M). The pharmacological validation of the analytical method showed that ambroxol (30, 60 or 120 mg/kg), guaifenesin (100 mg/kg), NH₄Cl (2000 mg/kg) or salbutamol (4 mg/kg) can be used as positive controls.

DISCUSSION

The phenol red quantification in the BALF is a rapid and low cost assay for the discovery of new expectorant drugs. Thus, it was proposed a standardization of the analytical and pharmacological methods to ensure the reliability of BALF processing and reproducibility of phenol red quantification for data analysis.

TAS-203, an oral phosphodiesterase 4 inhibitor, exerts anti-inflammatory activities in a rat airway inflammation model

Cyclic adenosine monophosphate (cAMP) is a key intracellular second messenger, which is degraded by phosphodiesterase 4 (PDE4). PDE4 suppresses cAMP levels, and thus stimulates the activity of inflammatory cells. Therefore, PDE4 has been considered as a therapeutic target for airway inflammatory diseases including asthma and chronic obstructive pulmonary disease (COPD). Roflumilast, an approved PDE4 inhibitor, has been shown to have clinical benefits in COPD. However, central nervous system-related side effects including nausea and vomiting have limited the therapeutic index of roflumilast. Moreover, although airway mucus hypersecretion is the characteristic feature, which is associated with the severity and prognosis, the inhibitory effect of roflumilast on sputum production is limited to a minority of patients. In this study, we demonstrate the inhibitory effects of TAS-203, which is an orally active PDE4 inhibitor associated with a lowered emetic effect, on airway inflammation and mucus hypersecretion. A cell-based assay showed TAS-203 treatment suppressed epidermal growth factor (EGF)-induced mucin MUC5AC expression. TAS-203 also suppressed monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-5 and IL-13 production in a Sephadex-induced airway inflammation model, and the number of infiltrating cells in bronchoalveolar lavage (BAL) fluid. TAS-203 caused marked reduction of goblet cell hyperplasia in a histopathological analysis of airway epithelium. Furthermore, TAS-203 suppressed 5-hydroxytryptamine (5-HT)-induced airway hyperresponsiveness (AHR). In addition, we preliminarily confirmed TAS-203 prevents airway MUC5AC production in BAL fluid, and shows lower specific airway resistance (sRaw) in a cigarette smoke-induced COPD-like model. Our data suggest that TAS-203 might be useful in the treatment of airway inflammatory disease.

Persistent induction of goblet cell differentiation in the airways: Therapeutic approaches

Dysregulated induction of goblet cell differentiation results in excessive production and retention of mucus and is a common feature of several chronic airways diseases. To date, therapeutic strategies to reduce mucus accumulation have focused primarily on altering the properties of the mucus itself, or have aimed to limit the production of mucus-stimulating cytokines. Here we review the current knowledge of key molecular pathways that are dysregulated during persistent goblet cell differentiation and highlights both pre-existing and novel therapeutic strategies to combat this pathology.

Mitomycin-C suppresses mucus secretion in an ileal neobladder rat model

The aim of the present study was to investigate the mucus secretion status of mature goblet cells following the application of mitomycin-C (MMC) in ileal neobladder rat models. Bladder substitution models were established in Sprague Dawley rats, which had been divided into five groups, namely the control (sham), normal saline (NS), high-dose MMC (HMMC), low-dose MMC (LMMC) and dehydrated alcohol (DA) groups. To evaluate the total protein concentration and level of sialic acid following the therapy, urine from the rats in each group was collected on days 8, 11 and 14. In addition, to observe the variances between mucus secretion and the ileum goblet cells, immunohistochemistry and hematoxylin and eosin staining were conducted in the different groups on day 17. The results indicated that the ileal neobladder mucosas in the MMC groups were clearly undamaged, as compared with the DA group. Furthermore, the MMC and DA groups were shown to inhibit the proliferation of goblet cells. The concentration of protein and sialic acid in the LMMC group was found to be lower compared with the NS group, while the concentration in the HMMC group was considerably lower. In conclusion, HMMC was demonstrated to evidently reduce the mucin and sialic acid concentration in the urine, without visible damage to the ileal neobladder mucus membrane. Therefore, MMC may provide a novel therapeutic approach for the treatment of certain bladder conditions.