Effects of formoterol and ipratropium bromide on repeated cadmium inhalation-induced pulmonary inflammation and emphysema in rats.

The anti-inflammatory properties of inhaled formoterol and ipratropium bromide, alone or in combination, were investigated in a rat model of chronic pulmonary inflammation with airspace enlargement induced by cadmium inhalation. At the end of the protocol, cadmium-induced increase of airway resistance was prevented by formoterol (4 mg/30 ml) or ipratropium (0.20 mg/20 ml). Formoterol elicited a significant decrease in total cell and neutrophil counts in bronchoalveolar lavage fluid as well as on the activity of gelatinase B (MMP-9), an enzyme strongly expressed in alveolar macrophages and epithelial cells. Additionally, a significant attenuation of the lung lesions characterized by inflammatory cell infiltration within the alveoli and the interstitium and a decrease in mean linear intercept were observed. Although ipratropium alone had no effects on the cadmium-induced pulmonary inflammation and emphysema, its combination with an inefficient concentration of formoterol (1 mg/30 ml) showed a synergistic inhibitory effect on neutrophil and total cell counts as well as on the mean linear intercept associated with a synergistic inhibition on the MMP-9 activity. Gelatinase A (MMP-2) activity was not influenced by drug pretreatments. Neither macrophage metalloelastase (MMP-12) activity nor levels of cytokines IL-1ß, TNF-α and GM-CSF in bronchoalveolar lavage fluid were modified in rats chronically exposed to cadmium. No desensitization of ß(2)-adrenoceptors or cholinergic receptors on airway smooth muscles and inflammatory cells during the protocol was observed. In conclusion, formoterol alone or combined with ipratropium bromide partially protects the lungs against the chronic inflammation and airspace enlargement by reducing neutrophilic infiltration possibly via the inhibition of MMP-9 activity.

Anti-inflammatory effects of formoterol and ipratropium bromide against acute cadmium-induced pulmonary inflammation in rats.

In this study, the anti-inflammatory properties of formoterol and ipratropium bromide, alone or in combination, were investigated in a rat model of acute pulmonary inflammation induced by cadmium inhalation. Airway resistance and inflammatory responses, including matrix metalloproteinease-2 (MMP-2) and matrix metalloproteinease-9 (MMP-9) activities, were evaluated. Compared to values obtained in rats exposed to cadmium, pretreatment by bronchodilators administered alone significantly prevented the cadmium-induced increase of airway resistance. Formoterol elicited a significant decrease in total cell number, neutrophil and macrophage counts in bronchoalveolar lavage fluid, whereas ipratropium bromide reduced neutrophil numbers. The two compounds administered alone significantly attenuated the lung lesions associated with parenchyma inflammatory cell influx and congestion observed in the cadmium group. The increased MMP-9 activity was significantly attenuated. Although only formoterol induced a decrease protein concentration in bronchoalveolar lavage fluid, both compounds inhibited the pulmonary edema by reducing wet-to-dry weight ratio which returned to values similar to those recorded in the sham group. All the effects of formoterol on the cadmium-induced inflammatory responses were reversed by propranolol. Similar anti-inflammatory effects were obtained in rats pretreated with ilomastat which showed a significant reduction on inflammatory cell infiltration and MMP-9 activity in bronchoalveolar lavage fluid. Neither synergistic nor additive effects were obtained when the two bronchodilators were administered in combination. In conclusion, formoterol and ipratropium bromide partially protect the lungs against the inflammation by reducing neutrophilic infiltration. This protective effect is associated with reduced MMP-9 activity known to play an important pro-inflammatory role in acute inflammatory process.