Effects of ambroxol on spontaneous or stimulated generation of reactive oxygen species by bronchoalveolar lavage cells harvested from patients with or without chronic obstructive pulmonary diseases

New drugs under development for COPD

The characteristic features of chronic obstructive pulmonary disease (COPD) include inflammation and remodelling of the lower airways and lung parenchyma together with activation of inflammatory and immune processes. Due to the increasing habit of cigarette smoking worldwide COPD prevalence is increasing globally. Current therapies are unable to prevent COPD progression in many patients or target many of its hallmark characteristics which may reflect the lack of adequate biomarkers to detect the heterogeneous clinical and molecular nature of COPD. In this chapter we review recent molecular data that may indicate novel pathways that underpin COPD subphenotypes and indicate potential improvements in the classes of drugs currently used to treat COPD. We also highlight the evidence for new drugs or approaches to treat COPD identified using molecular and other approaches including kinase inhibitors, cytokine- and chemokine-directed biologicals and small molecules, antioxidants and redox signalling pathway inhibitors, inhaled anti-infectious agents and senolytics. It is important to consider the phenotypes/molecular endotypes of COPD patients together with specific outcome measures to target new therapies to particular COPD subtypes. This will require greater understanding of COPD molecular pathologies and a focus on biomarkers of predicting disease subsets and responder/non-responder populations.

Role of oxidative stress in the pathogenesis of COPD

Chronic inhalation of cigarette smoke is a prominent cause of chronic obstructive pulmonary disease (COPD) and provides an important source of exogenous oxidants. In addition, several inflammatory and structural cells are a source of endogenous oxidants in the lower airways of COPD patients, even in former smokers. This suggests that oxidants play a key role in the pathogenesis of COPD. This oxidative stress is counterbalanced by the protective effects of the various endogenous antioxidant defenses of the lower airways. A large amount of data from animal models and patients with COPD have shown that both the stable phase of the disease, and during exacerbations, have increased oxidative stress in the lower airways compared with age-matched smokers with normal lung function. Thus, counteracting the increased oxidative stress may produce clinical benefits in COPD patients. Smoking cessation is currently the most effective treatment of COPD patients and reduces oxidative stress in the lower airways. In addition, many drugs used to treat COPD have some antioxidant effects, however, it is still unclear if their clinical efficacy is related to pharmacological modulation of the oxidant/antioxidant balance. Several new antioxidant compounds are in development for the treatment of COPD.

Immunomodulatory Effects of Ambroxol on Airway Hyperresponsiveness and Inflammation

Ambroxol is used in COPD and asthma to increase mucociliary clearance and regulate surfactant levels, perhaps through anti-oxidant and anti-inflammatory activities. To determine the role and effect of ambroxol in an experimental model of asthma, BALB/c mice were sensitized to ovalbumin (OVA) followed by 3 days of challenge. Airway hyperresponsiveness (AHR), lung cell composition and histology, and cytokine and protein carbonyl levels in bronchoalveolar lavage (BAL) fluid were determined. Ambroxol was administered either before the first OVA challenge or was begun after the last allergen challenge. Cytokine production levels from lung mononuclear cells (Lung MNCs) or alveolar macrophages (AM) were also determined. Administration of ambroxol prior to challenge suppressed AHR, airway eosinophilia, goblet cell metaplasia, and reduced inflammation in subepithelial regions. When given after challenge, AHR was suppressed but without effects on eosinophil numbers. Levels of IL-5 and IL-13 in BAL fluid were decreased when the drug was given prior to challenge; when given after challenge, increased levels of IL-10 and IL-12 were detected. Decreased levels of protein carbonyls were detected in BAL fluid following ambroxol treatment after challenge. In vitro, ambroxol increased levels of IL-10, IFN-γ, and IL-12 from Lung MNCs and AM, whereas IL-4, IL-5, and IL-13 production was not altered. Taken together, ambroxol was effective in preventing AHR and airway inflammation through upregulation of Th1 cytokines and protection from oxidative stress in the airways.

Effect of Ambroxol and Beclomethasone on Lipopolysaccharide-Induced Nitrosative Stress in Bronchial Epithelial Cells

BACKGROUND

Nitrosative stress is involved in different airway diseases. Lipopolysaccharide (LPS) induces neutrophil-related cytokine release and nitrosative stress in human bronchial epithelial (BEAS-2B) cells alone or with human polymorphonuclear neutrophils (PMNs). Ambroxol protects against oxidative stress, and beclomethasone dipropionate is an anti-inflammatory drug.

OBJECTIVES

We evaluated the ability of ambroxol and/or beclomethasone dipropionate to inhibit LPS-induced expression/release of RANTES, IL-8, inducible NO synthase (iNOS), myeloperoxidase (MPO) and 3-nitrotyrosine (3-NT: nitrosative stress biomarker) in BEAS-2B ± PMNs stimulated with LPS (1 μg/ml).

METHODS

The effect of ambroxol and/or beclomethasone dipropionate on IL-8, RANTES and iNOS levels was assessed by Western blot analysis; IL-8, MPO and 3-NT levels were measured by ELISA. Cell viability was assessed by the trypan blue exclusion test.

RESULTS

In BEAS-2B alone, LPS (at 12 h) increased RANTES/iNOS expression and IL-8 levels (p < 0.001). Ambroxol suppressed LPS-induced RANTES expression and IL-8 release (p < 0.001), whilst inhibiting iNOS expression (p < 0.05). Beclomethasone dipropionate had no effect on RANTES but halved iNOS expression and IL-8 release. Coculture of BEAS-2B with PMNs stimulated IL-8, MPO and 3-NT production (p < 0.001), potentiated by LPS (p < 0.001). Ambroxol and beclomethasone dipropionate inhibited LPS-stimulated IL-8, MPO and 3-NT release (p < 0.05). Ambroxol/beclomethasone dipropionate combination potentiated the inhibition of IL-8 and 3-NT production in BEAS-2B with PMNs (p < 0.05 and p < 0.01, respectively). Ambroxol and/or beclomethasone dipropionate inhibited nitrosative stress and the release of neutrophilic inflammatory products in vitro.

CONCLUSION

The additive effect of ambroxol and beclomethasone dipropionate on IL-8 and 3-NT inhibition suggests new therapeutic options in the treatment of neutrophil-related respiratory diseases such as chronic obstructive pulmonary disease and respiratory infections.

Ambroxol inhibits rhinovirus infection in primary cultures of human tracheal epithelial cells

The mucolytic drug ambroxol hydrochloride reduces the production of pro-inflammatory cytokines and the frequency of exacerbation in patients with chronic obstructive pulmonary disease (COPD). However, the inhibitory effects of ambroxol on rhinovirus infection, the major cause of COPD exacerbations, have not been studied. We examined the effects of ambroxol on type 14 rhinovirus (RV14) infection, a major RV group, in primary cultures of human tracheal epithelial cells. RV14 infection increased virus titers and cytokine content in the supernatants and RV14 RNA in the cells. Ambroxol (100 nM) reduced RV14 titers and cytokine concentrations of interleukin (IL)-1β, IL-6 and IL-8 in the supernatants and RV14 RNA in the cells after RV14 infection, in addition to reducing susceptibility to RV14 infection. Ambroxol also reduced the expression of intercellular adhesion molecule-1 (ICAM-1), the receptor for RV14, and the number of acidic endosomes from which RV14 RNA enters the cytoplasm. In addition, ambroxol reduced the activation of the transcription factor nuclear factor kappa B (NF-κB) in the nucleus. These results suggest that ambroxol inhibits RV14 infection partly by reducing ICAM-1 and acidic endosomes via the inhibition of NF-κB activation. Ambroxol may modulate airway inflammation by reducing the production of cytokines in rhinovirus infection.

Simultaneous high-throughput determination of clenbuterol, ambroxol and bromhexine in pharmaceutical formulations by HPLC with potentiometric detection

Potentiometric detection of clenbuterol, ambroxol and bromhexine in marketed pharmaceuticals was described in six isocratic HPLC systems. The podant- and macrocyclic-type neutral ionophores, N,N,N',N'-tetracyclohexyl-oxybis(o-phenyleneoxy)diacetamide (TOPA) and hexakis(2,3,6-tri-O-octyl)-alpha-cyclodextrin (OCD), were applied in poly(vinyl)chloride (PVC)-based liquid membrane electrodes. Both types of neutral ionophores improve the sensitivity for all mentioned drugs when compared with a tetrakis(p-chlorophenyl)borate (BOR)-based electrode as well as with single wavelength UV detection. Detection limits (S/N=3) of 2.6 x 10(-10) mol l(-1) (injected concentration) for the highly hydrophobic bromhexine were achieved with the TOPA-based electrode and a cyano reversed-phase (RP)-HPLC with Uptisphere UP5CN-25QS silica column (250 x 4.6 mm i.d.) eluted with acetonitrile (AcN)-ethanol-perchloric acid (1.66 mM) (60:2:38, v/v/v) (pH* 2.45). Comparable result was obtained with OCD-based electrodes and an XTerra RP18 hybrid silica-polymer column eluted with AcN-phosphoric acid (20 mM) (25:75, v/v) (pH* 2.60). In the mobile phases containing 60-75% v/v AcN or methanol, stable and reproducible response of both types of neutral ionophore-based electrodes was observed for at least 3 days. The results of the validated procedure for reliable simultaneous determination of the drugs in fortified representative samples of pharmaceuticals were also presented.

Reactive oxygen species in acute respiratory distress syndrome

In the metabolism of almost all human cells, a sequential addition of electrons to oxygen leads to the formation of reactive oxygen species (ROS). ROS have been implicated in more than 100 diseases and may be the common denominator in the pathogenesis of the most important health problems facing the world today. The last decade has been characterized by a progressive increase in the understanding of oxidant chemistry and the role of ROS in pulmonary disease. The majority of deaths among critically ill patients are the result of sepsis and its sequelae, including acute respiratory distress syndrome (ARDS). Nurses must understand the processes involving ROS that are in play when they are caring for patients with ARDS. This article describes what is known about the formation of ROS, the pathophysiology of ARDS, and the role ROS play in the pathogenesis of ARDS.