Eosinophil recruitment to inflamed lung is a hallmark of allergic asthma. The literature has shown that soluble guanylyl cyclase (sGC) plays a key antiinflammatory role by inhibiting leukocyte recruitment, and that increased cGMP intracellular levels inhibit human eosinophil chemotaxis in vitro. The soluble guanylyl cyclase is stimulated by NO, its physiological agonist. Other compounds are able to NO-independently stimulate sGC, such as the family of NO-independent and heme-dependent stimulators, and the NO-and hemeindependent stimulators, known as sGC activators. Therefore, this study aimed to investigate the effects of BAY 60-2770 (NO-and haem-independent sGC activator) in pulmonary allergic inflammation in mice and human eosinophil chemotaxis in vitro induced by eotaxin. Part I: Male C57BL6 mice were sensitized (100 µg of ovalbumin, s.c.; day 0 and 7) and intranasally challenged with OVA (10 µg; twice a day, 6 h between challenges) at days 14 and 15, with BAY 60-2770 (1 mg/Kg/gavage; 14 days) and/or its vehicle. Mice were anaesthetized and exsanguinated at 48 hours post first-OVA challenge, and biological samples were collected. The inflammatory profile was evaluated by total and differential cell counts in bronchoalveolar lavage (BAL) fluids, peripheral blood, bone marrow perfusate and histological slides. Serum OVA-specific IgE levels were measured and Th 1 (IFN-γ), Th 2 (IL-4, IL-5, IL-10) cytokines, TNF-α and eotaxin levels were quantified in BAL fluids. Soluble guanylyl cyclase subunits (α 1 and β 1 ) and iNOS protein expression were determined in lung parenchyma. The experimental design was divided in four groups, namely: Vehicle treated-instilled with Saline (VS group); Vehicle treatedchallenged with OVA (VO group); BAY 60-2770 treated-instilled with Saline (BS group) and BAY 60-2770 treated-challenged with OVA (BO group). Our results showed seric elevated IgE levels (p<0.05) in OVA-sensitized mice compared with naive animals, confirming the efficiency of sensitization procedure, which was not affected under BAY 60-2770 treatment. As expected, the OVA-challenge in VO group triggered a pulmonary allergic inflammatory response, characterized by markedly eosinophil migration to lung, elevated IL-4 levels in BAL fluid, as well as blood eosinophilia and marrow eosinophilopoiesis in bone marrow. This response was significantly accompanied by x reduced GCs (subunits α 1 and β 1 ) and increased iNOS expression in lung parenchyma, compared with non-challenged animals (VS group). No differences on TNF-α and eotaxin levels in BAL fluids were observed among studied groups. Levels of IFN-γ and IL-10 were not detected in BAL fluids of any groups. Chronic oral treatment with BAY 60-2770 (BO group) significantly reduced IL-4 and IL-5 levels in BAL fluids, inhibited pulmonary (BAL), blood and peri-bronchiolar eosinophilia, and supressed bone marrow eosinophilopoiesis, which was accompanied by restoration of sGC and iNOS expression in lung parenchyma, compared with vehicle treated group (VO). In separate experiments, is...
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