Effect of ambroxol on oxygen radical production and generation by bronchoalveolar lavage cells in young and aged guinea pigs

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.

Attenuation by ambroxol of monochloramine-enhanced gastric carcinogenesis: a possible prevention against Helicobacter pylori-associated gastric carcinogenesis

The effects of combined administration of a reactive oxidant, monochloramine, and a mucoregulatory agent, ambroxol, on the development of gastric cancers induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were investigated in inbred Wistar rats. After receiving oral MNNG and regular chow pellets for 25 weeks, rats received regular chow pellets or chow pellets containing 20% ammonium acetate, and normal tap water or water containing 30 mM sodium hypochlorite, with or without subcutaneous injection of ambroxol at high or low doses, until the end of the experiment at week 52. Treatment with both ammonium acetate and sodium hypochlorite, which produce monochloramine, significantly increased the incidence of gastric cancers at week 52, whereas concomitant administration of ambroxol with ammonium acetate and sodium hypochlorite significantly attenuated this enhanced gastric carcinogenesis. Results also revealed that ambroxol scavenged monochloramine. Because monochloramine is closely related to Helicobacter pylori-associated gastric carcinogenesis, these findings suggest that ambroxol may prevent H. pylori-associated gastric carcinogenesis.

Effects of N-acetylcysteine and ambroxol on the production of IL-12 and IL-10 in human alveolar macrophages

BACKGROUND

N-acetylcysteine (NAC) and ambroxol (AMB) have recently been proposed as possible therapeutic agents in the treatment of pulmonary disorders. IL-12 plays an important role in host resistance to infection and the development of Th-1 cells. In contrast, IL-10 is involved in anti-inflammatory and immunoregulatory mechanisms.

OBJECTIVE

We investigated the effects of NAC and AMB on secretions of IL-12 and IL-10 from human alveolar macrophages.

METHODS

Alveolar macrophages were obtained from 7 healthy nonsmokers by bronchoalveolar lavage. The cells were first incubated with either NAC or AMB for 2 h and then cultured in lipopolysaccharide (LPS) solution for 24 h. IL-12 and IL-10 secretions were measured by ELISA.

RESULT

Both NAC and AMB enhanced LPS-induced secretion of IL-12. NAC also enhanced LPS-induced IL-10 secretion, while AMB did not. The ratio IL-12/IL-10 secretion was increased by AMB, but NAC did not affect it.

CONCLUSIONS

The results suggest that NAC enhances inflammatory and immune responses and prevents excessive responses reciprocally, through keeping local balance of IL-12 and IL-10 production in alveolar macrophages at inflammatory sites of bacterial pneumonia. AMB appears to strengthen inflammatory responses and cell-mediated immunity, facilitating the development of Th-1 cells, through shifting the local balance to IL-12 dominance.

Inhibitory effects of angiotensin-converting enzyme (ACE) inhibitors on oxygen radicals produced by bronchoalveolar lavage cells in young and aged guinea pigs

We examined the effect of angiotensin-converting enzyme (ACE) inhibitors and age on oxygen radical formation by bronchoalveolar lavage (BAL) cells. Lung-free cells, including pulmonary alveolar macrophages, were harvested from young (4-month-old) and aged (28-month-old) male guinea pigs using BAL. The oxygen radicals produced by BAL cells were measured by a lucigenin-dependent chemiluminescence method using a photon counter. Although spontaneous oxygen radical production by BAL cells from young and aged guinea pigs did not differ, the oxygen radical generation after maximal stimulation with phorbol-myristate acetate (PMA) was greater than that produced without PMA stimulation in both young and aged animals. ACE inhibitors with and without an SH-group (alacepril and lisinopril, respectively) were tested for their effect on oxygen radical formation by BAL cells; both ACE inhibitors inhibited oxygen radical production and generation by BAL cells from both young and aged guinea pigs in a dose-dependent manner. However, the alacepril concentration giving 50% inhibition (IC50) of oxygen radical generation by BAL cells was smaller than the IC50 of lisinopril in both young and aged guinea pigs. These results indicate that ACE inhibitors, in particular those with an SH-group, effectively reduce oxygen radical production by BAL cells from young and aged guinea pigs, and suggest that treatment with ACE inhibitors may be useful for ameliorating oxidant-associated pulmonary disorders in young and aged patients.

Effects of angiotensin-converting enzyme (ACE) inhibitors on oxygen radical production and generation by murine lung alveolar macrophages

We examined the effect of angiotensin-converting enzyme (ACE) inhibitors on oxygen radical production before and generation after phorbol-myristate acetate (PMA) stimulation of lung alveolar macrophages. Lung free cells, predominantly pulmonary alveolar macrophages, were obtained from Fischer 344 rats and guinea pigs using bronchoalveolar lavage. The oxygen radicals produced by pulmonary alveolar macrophages with or without stimulation of PMA were measured by lucigenin-dependent chemiluminescence method using a photon counter, Lumat 9501 (Berthold, Germany). Alacepril, an ACE inhibitor with SH-group, inhibited the oxygen radical production and generation by lung alveolar macrophages harvested from both rats and guinea pigs in a dose-dependent fashion. Approximately 0.3 mM of alacepril inhibited 50% of oxygen radical production of lung alveolar macrophages in both rats and guinea pigs, whereas a higher concentration (1-5 mM) of lisinopril, an ACE inhibitor without SH-group, was necessary to inhibit 50% of oxygen radical production of lung alveolar macrophages in the animals. These results suggest that an ACE inhibitor with SH-group acts as an antioxidant in murine lungs and the treatment with the ACE inhibitor may reduce oxidant stress in hypertensive patients with asthma.

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.

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

We examined the effects of ambroxol on spontaneous or stimulated generation of reactive oxygen species (ROS) by bronchoalveolar lavage (BAL) cells prepared from 6 patients with chronic obstructive pulmonary disease (COPD) and age-matched control subjects without COPD. The ROS produced by BAL cells were measured by the lucigenin-dependent chemiluminescence method. The application of ambroxol into culture media containing BAL cells inhibited spontaneous and stimulated generation of ROS by BAL cells harvested from COPD patients and control subjects in an ambroxol concentration-dependent manner. These results indicate that ambroxol may be a candidate agent for reducing oxidant stresses of airways in COPD.

Hydrogen peroxide-induced apoptosis and necrosis in human lung fibroblasts: protective roles of glutathione

Although reactive oxygen species (ROS)-related cell damage has been implicated in pathogenesis of fibrogenetic pulmonary disorders, features of ROS-mediated cell death in human lung fibroblasts are not completely understood. We therefore examined the effects of hydrogen peroxide (H2O2) on cell growth kinetics in human lung fibroblasts (HFL-1 cells) and tested the roles of antioxidants on the H2O2-induced cell death (i.e., necrosis and apoptosis) in HFL-1 cells. We found that the relatively low concentrations of H2O2 ranging from 10 microM to 100 microM induced predominantly apoptosis, whereas higher concentration of H2O2 ranging 1 mM-10 mM induced predominantly necrosis in HFL-1 cells. Extracellular supplementation of glutathione (GSH) in culture media significantly abolished the H2O2-induced cell death, whereas GSH-depleted cells by pretreatment with buthionine sulfoxime (BSO) were likely to undergo cell death caused by a lower concentration of H2O2 than normal HFL-1 cells without BSO treatment. These results indicate that H2O2 induces both necrosis and apoptosis of human lung fibroblasts at least in part through the action of ROS and that modulation of the ROS production inside and outside of cells may influence the cell survival during oxidative insults.