RESUMO
OBJECTIVE: To investigate the induction and activation of heparinase by extracellular histones in acute respiratory distress syndrome(ARDS) induced by chlorine in mice.METHODS: The specific pathogen free adult male C57 BL/6 mice were randomly divided into control group, chlorine injured group, histone injured group, anti-histone antibody group and heparinase inhibitor group, with six mice in each group.The mice in the control group and histone injured group were exposed to clean air, and the mice in the other three groups were exposed to chlorine gas at a dose of 580.0 mg/m~3 for 30 minutes by systemic dynamic inhalation.Mice in the histone injured group were injected with 50 mg/kg body weight calf thymus histone by tail vein.One hour before exposure, mice in the anti-histone antibody group were pretreated with 20 mg/kg body weight anti-histone H4 antibody by tail vein injection, and mice in the heparinase inhibitor group were injected with 2 mg/kg body weight OGT2115(heparinase inhibitor). The other three groups were given equal volume of 0.9% sodium chloride solution by tail vein injection. After 24 hours of exposure, arterial blood was collected for blood gas analysis and the lung tissue was collected for histopathological examination. The protein level of heparinase in lung tissue were detected using enzyme-linked immunosorbent assay, and the activity of heparinase were detected by measuring the product of heparan degradation. The protein expression of pro-heparinase and active heparinase were detected by Western blotting.RESULTS: The dyspnea developed of mice in the chlorine injured group and histone injured group, diffuse inflammation occurred in lung tissue, the oxygenation index in arterial blood decreased(all P<0.05), and the protein level and activity of heparinase in lung tissue, as well as the relative expression of pro-heparinase and active heparinase were increased compared with the control group(all P<0.05). The dyspnea, hypoxemia and acute lung injury of mice in the anti-histone antibody group were alleviated, and the protein level of heparinase in lung tissue, as well as the relative expression levels of pro-heparinase and active heparinase were decreased(all P<0.05), compared with chlorine injury group and histone injury group.The dyspnea, hypoxemia and acute lung injury were alleviated in the heparinase inhibitor group, and the activity of heparinase and the relative expression of pro-heparinase in the lung tissue were decreased compared with the chlorine injury group(all P<0.05). CONCLUSION: During the occurrence and development of chlorine-induced ARDS in mice, extracellular histones aggravate lung injury by inducing the expression and activation of heparinase. Acute lung injury can be alleviated by inhibiting the expression and activation of heparinase.
RESUMO
Of all toxic inhalant exposures, chlorine is one of the most common toxic chemical inhalants. When acutely inhaled, it can be responsible for symptoms ranging from upper air way irritation to more serious respiratory effects. It can also deteriorate lung function and lead to death. Chlorine and its compounds such as chlorinated cyanurates and hypochlorites are commonly used in water disinfection. The chemical agents discussed in this article are sodium dichloroiso cyanurate and calcium hypochlorite which are the two most popular products for swimming pool chlorination. They are both strong oxidizing agents which are soluble in water. Between the above two alkali agents, acid-base interaction occurred and generated heat. And the acid drove the combination of hypochlorous and chloride ions to form chlorine gas. We have experienced, two boys who had inhalation injuries caused by an accidental explosion which occurred in a swimming pool by mixing two different chlorinating agents : sodium dichloroiso cyanurate and calcium hypochlorite. The children suffered from respiratory difficulties after the exposure. They both required intensive care management and one needed the support of mechanical ventilation