Effect of ambroxol of neutrophil chemotaxis in vitro

Effect of ambroxol on the concentration of cefotaxime in the bronchoalveolar lavage fluid of rats with pulmonary fibrosis

This study aimed to investigate the effect of ambroxol on the concentration of cefotaxime in the bronchioalveolar lavage fluid of rats with bleomycin-induced pulmonary fibrosis. A total of 54 Wistar male rats were randomly divided into three groups, namely the normal control group, model group and ambroxol group. On experimental day 0, the rats were intratracheally instilled with bleomycin (5 mg/kg body weight) or sterile saline. The rats in the ambroxol group were then treated with ambroxol (35 mg/kg/day) intraperitoneally. On days 7, 14, 28 after instillation, six rats from each group were sacrificed, bronchial alveolar fluids were recovered and the lungs were collected for histopathological examination following the injection of cefotaxime (600 mg/kg) intravenously. The concentration of cefotaxime in the bronchial alveolar fluids was assayed by a liquid chromatography-mass spectrometry method. On day 7, the concentration of cefotaxime in the bronchial alveolar fluid of the ambroxol group was lower than that of the model group. On day 14, the concentration of cefotaxime in the bronchial alveolar fluids of the ambroxol group was higher than that of the model group, and the difference between these groups was significant statistically (P<0.001). On day 28, the concentration of cefotaxime in the bronchial alveolar fluids of the ambroxol group decreased sharply, and was lower than that of the model group (P=0.126). These results indicate that ambroxol increased the concentration of cefotaxime in the bronchial alveolar fluids at the primary fibrosis stage.

Biofilm-dependent airway infections: a role for ambroxol?

Biofilms are a key factor in the development of both acute and chronic airway infections. Their relevance is well established in ventilator associated pneumonia, one of the most severe complications in critically ill patients, and in cystic fibrosis, the most common lethal genetic disease in Caucasians. Accumulating evidence suggests that biofilms could have also a role in chronic obstructive pulmonary disease and their involvement in bronchiectasis has been proposed as well. When they grow in biofilms, microorganisms become multidrug-resistant. Therefore the treatment of biofilm-dependent airway infections is problematic. Indeed, it still largely based on measures aiming to prevent the formation of biofilms or remove them once that they are formed. Here we review recent evidence suggesting that the mucokinetic drug ambroxol has specific anti-biofilm properties. We also discuss how additional pharmacological properties of this drug could be beneficial in biofilm-dependent airway infections. Specifically, we review the evidence showing that: 1-ambroxol exerts anti-inflammatory effects by inhibiting at multiple levels the activity of neutrophils, and 2-it improves mucociliary clearance by interfering with the activity of airway epithelium ion channels and transporters including sodium/bicarbonate and sodium/potassium/chloride cotransporters, cystic fibrosis transmembrane conductance regulator and aquaporins. As a whole, the data that we review here suggest that ambroxol could be helpful in biofilm-dependent airway infections. However, considering the limited clinical evidence available up to date, further clinical studies are required to support the use of ambroxol in these diseases.

Ambroxol: a multifaceted molecule with additional therapeutic potentials in respiratory disorders of childhood

INTRODUCTION

Mucoactive drugs are currently used to cleanse the respiratory tract following disturbance of the normal mucociliary clearance due to mucous hyperproduction and/or modification of its physicochemical characteristics. However, in addition to possessing the ability to perform specific actions on airway secretion, these compounds have the capability to modulate the mechanisms involved in abnormal secretions. Indeed, over the years, in the postmarketing phase, a large number of studies have been published showing interesting pharmacological activities in addition to their secretagogue activity.

AREAS COVERED

This article collates available data on ambroxol (2-amino-3,5-dibromo-N-[trans-4-hydroxycyclohexyl]benzylamine), a metabolite of bromhexine, used as a secretagogue in the treatment of childhood airway diseases. This article goes beyond the mucoactive aspects of the drug covering its multiple pharmacological properties.

EXPERT OPINION

The non-mucoactive functions exhibited by the compound may provide beneficial effects on airway structure and function in health and disease. Beyond the mucokinetic and secretagogue effects, ambroxol showed great antioxidant, anti-inflammatory, local anesthetic and surfactant synthesis stimulatory activities. Moreover, some antiviral and antibacterial activities were shown. These findings may better explain the clinical results observed in a variety of airway disorders and suggest additional therapeutic potential. Further studies are needed to better define the clinical relevance of these non-mucolytic activities.

Ambroxol-induced modification of ion transport in human airway Calu-3 epithelia

Ambroxol is often used as a mucolytic agent in various lung diseases. However, it is unclear how ambroxol acts on bronchial epithelial cells. To clarify the action of ambroxol, we studied the effects of ambroxol on the ion transport in human Calu-3 cells, a human submucosal serous cell line, measuring the transepithelial short-circuit current and conductance across monolayers of Calu-3 cells. Ambroxol of 100 microM diminished the terbutaline (a beta2-adrenergic agonist)-stimulated Cl-/HCO3(-)-dependent secretion without any decreases in the conductance of cystic fibrosis transmembrane conductance regulator (CFTR) channel locating on the apical membrane. On the other hand, under the basal (unstimulated) condition ambroxol increased the Cl(-)-dependent secretion with no significant change in the apical CFTR channel conductance and decreased the HCO3- secretion associated with a decrease in the apical CFTR channel conductance. Ambroxol had no major action on the epithelial Na+ channel (ENaC) or the ENaC-mediated Na+ absorption. These results indicate that in Calu-3 cells: (1) under the basal (unstimulated) condition ambroxol increases Cl- secretion by stimulating the entry step of Cl- and decreases HCO3- secretion by diminishing the activity of the CFTR channel and/or the Na+/HCO3(-)-dependent cotransporter, (2) under the adrenergic agonist-stimulated condition, ambroxol decreases Cl- secretion by acting on the Cl-/HCO3- exchanger, and (3) ambroxol has a more powerful action than the adrenergic agonist on the Cl-/HCO3- exchanger, leading fluid secretion to a moderately stimulated level from a hyper-stimulated level.

In vitro inhibition of human neutrophil histotoxicity by ambroxol: evidence for a multistep mechanism

Neutrophils are major culprits for the protease/antiprotease imbalance during various lung diseases, that is, chronic obstructive pulmonary disease, cystic fibrosis, idiopathic pulmonary fibrosis and adult respiratory distress syndrome. Thus, these cells are presently considered an ideal target for the pharmacologic control of tissue injury during these diseases. This study was planned in order to investigate if ambroxol and its precursor bromhexine are actually capable of preventing alpha-1-antitrypsin (A1AT) inactivation by stimulated neutrophils and possibly to look into the mechanisms underlying this event. Ambroxol inhibited the production of superoxide anion by activated neutrophils, whereas bromhexine had no inhibitory effect. Ambroxol decreased the production of hypochlorous acid (HOCl) from activated neutrophils with high efficiency, whereas bromhexine had a modest activity. Ambroxol and bromhexine were capable of limiting the chlorination of monochlorodimedon by HOCl, displaying the capacity of directly scavenging the oxidant. Ambroxol decreased the release of elastase and myeloperoxidase from activated neutrophils, whereas bromhexine was ineffective. Ambroxol prevented the A1AT inactivation by neutrophils, whereas bromhexine was completely ineffective. Among drugs currently available for in vivo use in humans, ambroxol is unique by virtue of its ability to prevent neutrophil-mediated A1AT inactivation via inhibition of HOCl production as well as HOCl scavenging. Also taking into account its capacity for curbing elastase release, the drug displays the potential to lessen the burden of oxidants/proteases and to increase the antiprotease shield at the site of inflammation. Thus, ambroxol appears to be a good candidate for raising attempts to develop new therapeutic histoprotective approaches to inflammatory bronchopulmonary diseases.

Depressant effect of ambroxol on stimulated functional responses and cell death in rat alveolar macrophages exposed to silica in vitro

The present study examined the effect of ambroxol on free radical production, granule enzyme release, and cell death in silica-activated rat alveolar macrophages. The action of ambroxol was assayed by measuring changes in the activities of protein kinase C (PKC) and tyrosine kinase (PTK) and in the intracellular calcium level. Ambroxol attenuated the production of superoxide, hydrogen peroxide, and nitric oxide and the release of acid phosphatase and lysozyme in macrophages activated by silica. Staurosporine, genistein, EGTA, and trifluoperazine inhibited the silica-induced free radical production and granule enzyme release. Silica induced the increase in PKC and PTK activities and the elevation of intracellular calcium level in macrophages, which was decreased by ambroxol. Silica induced a cell death and increased the caspase-3 activity in macrophages in a concentration-dependent manner. Ambroxol decreased the silica-induced cell viability loss in macrophages. The results show that ambroxol decreases the stimulated responses and cell death in rat alveolar macrophages exposed to silica, which may be accomplished by inhibition of activation processes, protein kinases, and calcium transport. The inhibitory effect of ambroxol on silica-induced cell death appears to provide the protective effect on pulmonary tissues against the toxic action of silica.

Depressant effects of ambroxol on lipopolysaccharide- or fMLP-stimulated free radical production and granule enzyme release by alveolar macrophages

In order to explore the depressant action of ambroxol, a bronchial expectorant, on the activated alveolar macrophage responses, its effect on lipopolysaccharide (LPS)- or N-formyl-methionyl-leucyl-phenylalanine (fMLP)- stimulated free radical production and granule enzyme release by rat lung alveolar macrophages was investigated. Ambroxol attenuated the 100 ng/ml LPS- or 1 microM fMLP-stimulated superoxide, H(2)O(2)and nitric oxide production and releases of acid phosphatase and lysozyme by alveolar macrophages. Ambroxol attenuated phorbol myristate acetate-stimulated superoxide and nitric oxide production that was inhibited by 100 nM staurosporine. N,N-dimethylsphingosine (DMS, 4.5 and 9 microM) alone stimulated superoxide production by macrophages, while 45 microM of the compound did not show a stimulatory effect. However, DMS decreased nitric oxide production in a dose-dependent manner. Ambroxol did not alter the DMS effect on free radical production that was affected by 10 microM genistein. A preincubation of macrophages with ambroxol (10 and 100 microM), staurosporine and genistein attenuated the elevation of [Ca(2+)](i)caused by LPS. The results suggest that ambroxol exerts a depressant effect on LPS- or fMLP-stimulated free radical production and granule enzyme release by rat alveolar macrophages, which may be attributed to its inhibitory action on the activation process, protein kinase C, but its action on protein tyrosine kinase is not suggested.

The inhibitory effect of ambroxol on respiratory burst, degranulation and cytosolic Ca2+ change in degraded immunoglobulin G-activated neutrophils

Superoxide and H2O2 production by neutrophils stimulated by 0.5 mg/ml degraded immunoglobulin G (IgG) and 1 microM N-formyl-methionyl-leucyl-phenylalanine (fMLP) was inhibited by ambroxol in a dose-dependent fashion, and at the concentration of 100 microM, 43.3% to 64.3% of inhibitions were detected. The inhibitory effect of ambroxol on H2O2 production by neutrophils was greater than that on superoxide production. The production of nitrite by lipopolysaccharide-activated murine peritoneal macrophages was significantly attenuated by ambroxol in a dose-dependent fashion and NG-monomethyl-L-arginine (NMMA). Ambroxol decreased the release of myeloperoxidase and lysozyme evoked by 0.5 mg/ml degraded immunoglobulin G and 1 microM fMLP in a dose-dependent fashion, and at the concentration of 100 microM, 37.1% to 64.2% of inhibitions were observed. The stimulatory effect of phorbol 12-myristate 13-acetate (PMA) (0.1 microg/ml) on superoxide production and myeloperoxidase, which is inhibited by 100 nM staurosporine, was not affected by 100 microM ambroxol. Degraded immunoglobulin G (0.5 mg/ml) caused an immediate elevation of [Ca2+]i in fura-2 load neutrophils in 1.23 mM Ca2+-containing medium. Preincubation of neutrophils with 10 microM to 100 microM ambroxol, 5 mM EGTA and 100 microM verapamil depressed the elevation of [Ca2+]i elicited by 0.5 mg/ml degraded immunoglobulin G. In conclusion, the inhibitory action of ambroxol on stimulated neutrophil responses, including respiratory burst and lysosomal enzyme release, appears to be attributed to its depressant action on the activation process, including the change in intracellular Ca2+ level. in which the role of protein kinase C is uncertain.

Characterization of N-acetylcysteine and ambroxol in anti-oxidant therapy

Reactive free oxygen radicals are known to play an important role in the pathogenesis of various lung diseases such as idiopathic pulmonary fibrosis (IPF), adult respiratory distress syndrome (ARDS) or cystic fibrosis (CF). They can originate from endogenous processes or can be part of exogenous exposures (e.g. ozone, cigarette smoke, asbestos fibres). Consequently, therapeutic enhancement of anti-oxidant defence mechanisms in these lung disorders seems a rational approach. In this regard, N-acetyl-L-cysteine (NAC) and ambroxol have both been frequently investigated. Because of its SH group, NAC scavenges H2O2 (hydrogen peroxide), .OH (hydroxol radical), and HOCl (hypochlorous acid). Furthermore, NAC can easily be deacetylated to cysteine, an important precursor of cellular glutathione synthesis, and thus stimulate the cellular glutathione system. This is most evident in pulmonary diseases characterized by low glutathione levels and high oxidant production by inflammatory cells (e.g. in IPF and ARDS). NAC is an effective drug in the treatment of paracetamol intoxication and may even be protective against side-effects of mutagenic agents. In addition NAC reduces cellular production of pro-inflammatory mediators (e.g. TNF-alpha, IL-1). Also, ambroxol [trans-4-(2-amino-3,5-dibromobenzylamino)-cyclohexane hydrochloride] scavenges oxidants (e.g. .OH, HOCl). Moreover, ambroxol reduces bronchial hyperreactivity, and it is known to stimulate cellular surfactant production. In addition, ambroxol has anti-inflammatory properties owing to its inhibitory effect on the production of cellular cytokines and arachidonic acid metabolites. For both substances effective anti-oxidant and anti-inflammatory function has been validated when used in micromolar concentrations. These levels are attainable in vivo in humans. This paper gives an up-to-date overview about the current knowledge of the hypothesis that oxidant-induced cellular damage underlies the pathogenesis of many human pulmonary diseases, and it discusses the feasibility of anti-oxidant augmentation therapy to the lung by using NAC or ambroxol.

Ambroxol inhibits Na+ absorption by canine airway epithelial cells in culture

To study the effect of ambroxol on ion transport functions of airway mucosa, we measured bioelectric properties of canine cultured tracheal epithelium under short-circuit conditions in-vitro. Addition of ambroxol to the submucosal but not to the mucosal solution in an Ussing chamber decreased short-circuit current, transepithelial potential difference and cell conductance. The ambroxol-induced decrease in short-circuit current was not affected by bumetanide or diphenylamine-2-carboxylate, but it was abolished by pretreatment of cells with amiloride. These results suggest that ambroxol may selectively inhibit Na+ absorption by airway epithelium, thereby increasing water composition in airway surface fluid and reducing mucus viscosity.

Ambroxol inhibits interleukin 1 and tumor necrosis factor production in human mononuclear cells

We have studied the effect of Ambroxol on the production of Interleukin-1 (IL-1) and Tumor Necrosis Factor (TNF) in human mononuclear cells (MNC). For this purpose MNC were cultured for 24 h in the presence of endotoxin and different doses of Ambroxol. The results indicate that Ambroxol markedly inhibited IL-1 and TNF production at doses of 10-100 microgram ml, without any apparent toxicity.