Bronchodilator and Anti-Inflammatory Action of Theophylline in a Model of Ovalbumin-Induced Allergic Inflammation

Inhaled pan-phosphodiesterase inhibitors ameliorate ovalbumin-induced airway inflammation and remodeling in murine model of allergic asthma

Asthma is a heterogeneous, chronic respiratory disease characterized by airway inflammation and remodeling. Phosphodiesterase (PDE) inhibitors represent one of the intensively studied groups of potential anti-asthmatic agents due to their affecting both airway inflammation and remodeling. However, the effect of inhaled pan-PDE inhibitors on allergen induced asthma has not been reported to date. In this study we investigated the impact of two, representative strong pan-PDE inhibitors from the group of 7,8-disubstituted derivatives of 1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione: compound 38 and 145, on airway inflammation and remodeling in murine model of ovalbumin (OVA)-challenged allergic asthma. Female Balb/c mice were sensitized and challenged with OVA, 38 and 145 were administrated by inhalation, before each OVA challenge. The inhaled pan-PDE inhibitors markedly reduced the OVA-induced airway inflammatory cell infiltration, eosinophil recruitment, Th2 cytokine level in bronchoalveolar lavage fluid, as well as both, total and OVA-specific IgE levels in plasma. In addition, inhaled 38 and 145 decreased many typical features of airway remodeling, including goblet cell metaplasia, mucus hypersecretion, collagen overproduction and deposition, as well as Tgfb1, VEGF, and α-SMA expression in airways of allergen challenged mice. We also demonstrated that both 38 and 145 alleviate airway inflammation and remodelling by inhibition of the TGF-β/Smad signaling pathway activated in OVA-challenged mice. Taken together, these results suggest that the investigated pan-PDE inhibitors administered by inhalation are dual acting agents targeting both airway inflammation and remodeling in OVA-challenged allergic asthma and may represent promising, anti-asthmatic drug candidates.

Effects of superimposed pressure oscillations on a chronic sensitized airways mouse model

The hyperconstriction of airway smooth muscle (ASM) is the main driving mechanism during an asthmatic attack. The airway lumen is reduced, resistance to airflow increases, and normal breathing becomes more difficult. The tissue contraction can be temporarily relieved by using bronchodilator drugs, which induce relaxation of the constricted airways. In vitro studies indicate that relaxation of isolated, precontracted ASM is induced by mechanical oscillations in healthy subjects but not in asthmatic subjects. Further, short-term acute asthmatic subjects respond to superimposed pressure oscillations (SIPO) generated in the range of 5-15 Hz with ~50% relaxation of preconstricted sensitized airways. Mechanical oscillations, and specifically SIPO, are not widely characterized in asthmatic models. The objective of this in vivo study is to determine the effects of a range of oscillation patterns similar to our previous acute study differing from normal breathing. Both healthy and sensitized mice were observed, with their responses to SIPO treatments measured during induced bronchoconstriction resulting from acetylcholine (Ach) challenge. SIPO-generated results were compared with data from treatments using the bronchorelaxant isoproterenol (ISO). The study shows that SIPO in the range of 5-20 Hz induces relaxation in chronic sensitized airways, with significant improvements in respiratory parameters at SIPO values near 1.7 cmH₂O irrespective of the frequency of generation.

Progress in active compounds effective on ulcerative colitis from Chinese medicines

Ulcerative colitis (UC), a chronic inflammatory disease affecting the colon, has a rising incidence worldwide. The known pathogenesis is multifactorial and involves genetic predisposition, epithelial barrier defects, dysregulated immune responses, and environmental factors. Nowadays, the drugs for UC include 5-aminosalicylic acid, steroids, and immunosuppressants. Long-term use of these drugs, however, may cause several side effects, such as hepatic and renal toxicity, drug resistance and allergic reactions. Moreover, the use of traditional Chinese medicine (TCM) in the treatment of UC shows significantly positive effects, low recurrence rate, few side effects and other obvious advantages. This paper summarizes several kinds of active compounds used in the experimental research of anti-UC effects extracted from TCM, mainly including flavonoids, acids, terpenoids, phenols, alkaloids, quinones, and bile acids from some animal medicines. It is found that the anti-UC activities are mainly focused on targeting inflammation or oxidative stress, which is associated with increasing the levels of anti-inflammatory cytokine (IL-4, IL-10, SOD), suppressing the levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-8, IL-23, NF-κB, NO), reducing the activity of MPO, MDA, IFN-γ, and iNOS. This review may offer valuable reference for UC-related studies on the compounds from natural medicines.

Determination of Phosphodiesterase Inhibitors Tadalafil, Roflumilast and Roflumilast N-Oxide Using LC-MS in Guinea Pig Plasma

Phosphodiesterases are known as a super-family of 11 isoenzymes, which can exert various functions based on their organ distribution. In this work, a rapid and sensitive ultra-high performance liquid chromatography-tandem mass spectrometry method was developed for quantification of tadalafil (phosphodiesterase five inhibitor), roflumilast (RF) (phosphodiesterase four inhibitor) and its active metabolite, RF N-oxide in guinea pig plasma. Chromatographic separation was carried out on UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) at a flow rate 0.5 mL/min, using 0.2% formic acid in acetonitrile and 0.2% formic acid in water as mobile phases within 4 min. Detection was performed using a triple quadrupole mass spectrometer employing electrospray ionization operated in positive mode using multiple reaction monitoring mode. The method utilized deuterium labeled internal standards, and was validated according to European Medicines Agency guidelines. It showed excellent linearity in the range of 0.5-500.0 ng/mL for all analytes with coefficient of determination >0.99. The intra- and inter-day precisions (relative standard deviation %) were within 6.7%, and the recoveries were greater than 73.4%. Using this method, plasma samples from experiments of phosphodiesterase four, and five inhibitors in a model of ovalbumin-induced allergic inflammation in guinea pigs were analyzed.

Inhibitors of phosphodiesterases in the treatment of cough

A group of 11 enzyme families of metalophosphohydrolases called phosphodiesterases (PDEs) is responsible for a hydrolysis of intracellular cAMP and cGMP. Xanthine derivatives (methylxanthines) inhibit PDEs without selective action on their single isoforms and lead to many pharmacological effects, e.g. bronchodilation, anti-inflammatory and immunomodulating effects, and thus they can modulate the cough reflex. Contrary, selective PDE inhibitors have been developed to inhibit PDE isoforms with different pharmacological effects based on their tissue expression. In this paper, effects of non-selective PDE inhibitors (e.g. theophylline) are discussed, with a description of other putative mechanisms in their effects on cough. Antitussive effects of selective inhibitors of several PDE isoforms are reviewed, focusing on PDE1, PDE3, PDE4, PDE5 and PDE7. The inhibition of PDEs suggests participation of bronchodilation, suppression of TRPV channels and anti-inflammatory action in cough suppression. Selective PDE3, PDE4 and PDE5 inhibitors have demonstrated the most significant cough suppressive effects, confirming their benefits in chronic inflammatory airway diseases associated with bronchoconstriction and cough.

Dose dependent effects of tadalafil and roflumilast on ovalbumin-induced airway hyperresponsiveness in guinea pigs

INTRODUCTION

Chronic obstructive diseases of airways associated with cough and/or airway smooth muscle hyperresponsiveness are usually treated with bronchodilating and anti-inflammatory drugs. Recently, selective phosphodiesterase (PDE) 4 inhibitors have been introduced into the therapy of chronic obstructive pulmonary disease. Several studies have demonstrated their ability to influence the airway reactivity and eosinophilic inflammation by increasing the intracellular cAMP concentrations also in bronchial asthma. Furthermore, the expression of PDE5 in several immune cells suggests perspectives of PDE5 inhibitors in the therapy of inflammation, as well.

PURPOSE

The aim of this study was to assess the dose-dependent effects of PDE4 and PDE5 inhibitors in allergic inflammation. Therefore, the effects of 7-days administration of PDE4 inhibitor roflumilast and PDE5 inhibitor tadalafil at two different doses in experimentally-induced allergic inflammation were evaluated.

MATERIALS AND METHODS

In the study, male adult guinea pigs were used. Control group was non-sensitized. Other animals were sensitized with ovalbumin over two weeks and thereafter treated intraperitoneally for 7 days with roflumilast or tadalafil (daily dose 0.5 mg/kg or 1.0 mg/kg b.w.), or with vehicle.

RESULTS

Both roflumilast and tadalafil reduced specific airway resistance after nebulization of histamine (marker of in vivo airway reactivity) at both doses used. The in vitro airway reactivity to cumulative doses of acetylcholine was significantly reduced for roflumilast at higher dose, predominantly in the lung tissue strips. Histamine-induced contractile responses were significantly influenced in both lung and tracheal tissue strips, predominantly at the higher doses. Tadalafil led to a decrease in contractile responses induced by both acetylcholine and histamine, with more significant effects in the lung tissue strips. These changes were associated with decreased numbers of circulating leukocytes and eosinophils and concentrations of interleukin (IL)-4, IL-5 and TNF-α in the lung homogenate.

CONCLUSIONS

The selective PDE4 and PDE5 inhibitors alleviated allergic airway inflammation, with more significant effects at the higher doses.

Quantification of Theophylline in Guinea Pig Plasma by LC-MS/MS Using Hydrophilic Interaction Liquid Chromatography Stationary Phase: Method Development, Validation, and Application in Study

Theophylline has been used in the treatment of bronchial asthma and chronic obstructive pulmonary disease (COPD) for over 70 years. In order to maximize the effectiveness and safety of theophylline therapy it is important to individualize the dosage of the drug. In our study we focused on determination of theophylline concentrations in guinea pig plasma. A rapid, specific, and reliable LC-MS/MS-based method was developed and validated according to European Medicine Agency (EMA) guidelines. A hydrophilic interaction liquid chromatography (HILIC) separation mode for reduction time of sample preparation was used. The analysed sample was quantified in a positive ionization mode. Multiple reaction monitoring (MRM) using transition m/z 181.06→124.06 and m/z 187.17→127.06 was performed to quantify theophylline with deuterated internal standard ([2H6]-theophylline), respectively. Modification of collision energies was performed in parallel with chromatographic separation to further eliminate interference from the matrix. The method was validated for a range of 0.5 to 30 μg/mL of plasma sample. The intra-day and inter-day precision and accuracy of the quality control samples at low, me dium, and high concentration levels exhibited relative standard deviations (RSD) of less than 10 %. The method was successfully applied for the quantitation of theophylline in guinea pig plasma for better understanding its effects in a model of ovalbumin-induced allergic inflammation.