| Background:Drowning is one of the most significant public health problems. It’s defined as a duration of submersion, a set number of fluid aspirated and a experiencing respiratory impairment from immersion in liquid. Seawater drowning is a major leading courses of accidental death in navigation, offshore production and touring on the sea. The World Health Organisation (WHO) estimates that there are about450,000people die each year from drowning all over the world. Inhaled seawater with high osmolarity have a number of pernicious effects on capillary endothelium, alveolar pneumocytes and surfactant production. It may lead to SW-ALI which is characterized by pulmonary edema and acute inflammation and its more severe form:seawater-induced acute respiratory distress syndrome (SW-ARDS). PE-SWD is a prominent manifestation of SW-ALI. It is the major pathological basis of acute respiratory failure and it has been recognized as a vital cause of death in drowning victims.Nuclear factor of activated T cells5(NFAT5), is a rel family transcription factor. It was initially identified as a tonicity regulated transcription factor from its role of counteract the pernicious effects of cell shrinkage in order to protect cells from hypertonicity with an adaptive response. The response is the accumulation of organic osmolytes such as myo-inositol, betaine, taurine and sorbitol are superseded the excess electrolytes.Objective:1.To explore the mechanism and expression of nuclear factor of activated T cells5(NFAT5) on pulmonary edema induced by seawater drowning in rats.2.To investigate the potential mechanism of NFAT5in inflammation after seawater drowning.Method:In vivo:56Sprague-Dawley (SD) rats, which were weighing180-200g each(5-7weeks), were randomly divided into8groups:a normal control group (n=8), lh,2h,3h,4h,5h and6h seawater group (n=8). Before being administered seawater (4ml/kg body weight) through the trachea,3%pentobarbital sodium (2.0g/kg) intraperitoneal injection were given to the rats in order to anesthetised. The expression of NFAT5were detected by qRT-PCR and immunohistochemistry. The degree of pulmonary edema were evaluated by wet to dry ratio and LPI. Pulmonary histological changes were investigated by HE. LC-MS used for detecting osmolytes, such as taurine, sorbitol and betain.In Vitro:A549cells were used in cell experiments. Cells were cultured in RPMI1640as standard medium at37℃in a humidified atmosphere with5%CO2and95%air. For all cells, iso-osmotic medium (280mOsmol/kg) was made hypertonic medium with graded seawater concentration. Based on the MTT assay results, the final concentration is20%,30%,40%,50%seawater for6h. At the end of experiment, culture medium were collected and used for determination of IL-1β, IL-6and TNF-α expression by ELISA. The cells were washed with PBS for western blot and quantitative real-time PCR measurement.Results:In this study, Seawater aspiration induced injuries of the lung alveolar structures, such as edema, focal hemorrhage, distortion, thickened alveolar wall and the infiltration of inflammatory cells. In contrast, normal lung tissue architecture were existed in the normal group. The W/D ratio and LPI were significantly increased after seawater aspiration when compared with normal control. The noteworthy change occured at1h after seawater aspiration and then gradually decreased, P<0.01. The expression of NFAT5mRNA and protein level were remarkably higher in seawater group than in normal group by the measurement of qRT-PCR and immunohistochemistry. Furthermore, the up-regulated NFAT5alleviate seawater-induced pulmonary edema (PE-SWD) by regulated BGT1, AR and TauT transporters. ELISA and qRT-PCR results suggested that overexpression of NFAT5stimulate the production of pro-inflammatory cytokines.Conclusion:These findings demonstrated that NFAT5play a dual role in the development of seawater-induced acute lung injury (SW-ALI). It can alleviate pulmonary edema, but the overexpression of NFAT5may aggravate the inflammation in the later stage. |
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