| Objective: Acute lung injury is a kind of acute and diffuse inflammatory lung injury caused by various direct or indirect traumatic factors such as severe infection,poisoning,shock and trauma.Mechanical ventilation is one of the most important measures to treat acute lung injury and control symptoms clinically.However,the complications associated with mechanical ventilation also significantly affect the prognosis of patients with acute lung injury and even cause death.Hyaluronic acid(HA)is an endogenous macromolecule acidic mucopolysaccharide with the function of moisturizing and immunomodulatory.High molecular weight hyaluronic acid(HMW HA,1600 kDa)has anti-inflammatory effects,but the related research is relatively rare.Therefore,we study the anti-inflammatory effect of HA on lipopolysaccharide-induced acute lung injury in mechanical ventilation rat and NR8383 cell in vivo and in vitro.Methods:(1)Animal experiments: Sprague-Dawley rats were randomLy divided into three groups: nonventilated control rats;mechanical ventilated rats with lipopolysaccharide(LPS)infusion;mechanical ventilation plus LPS infusion with HMW HA(1600 kDa).Rats were subjected to left bronchial alveolar lavage for white blood cell count and neutrophil count.The right lung was taken to paraffin sections.Pathological changes was observed through HE staining and MPO activity was detected.The mRNA expression of TNF-α,IL-1β,IL-8,iNOS were detected by qPCR and The protein expression of TNF-α and IL-1β were detected by ELISA.the therapeutic effect of HA on LPS-induced acute lung injury in mechanical wentilated rats was explored through above test method.(2)Cell experiments: The expression of NLRP3 inflammasome in lung tissue was detected by immunofluorescence.The protein expression of NLRP3,ASC and caspase-1 in NR8383 cells was detected by immunoprecipitation and Western Blot.Mechanism of lung injury.The mechanism of HA treating LPS-induced acute lung injury by NLRP3 inflammasome was investigated through above test method.Results:(1)Rats receiving LPS had increased BAL white blood cells and neutrophils as compared with rats without LPS treatment.Treatment with HMW HA decreased BAL white blood cells and neutrophils.In group with HMW HA tremeatment,the structure of lung tissue was clear and complete,and the infiltration and number of neutrophils and monocytes decreased,which indicated that HMW HA reduced LPS-induced inflammation in mechanical ventilated rats.(2)The results of MPO activity,qPCR and ELISA showed that the MPO activity of lung tissue and the expression of TNF-α,IL-1β,IL-8,iNOS decreased significantly after HA treatment,which further indicated that HMW HA reduced LPS-induced inflammation in mechanical ventilated rats.(3)Immunofluorescence of lung tissue showed that HMW HA inhibited NLRP3 inflammasome expression in rat lung tissue.Immunoprecipitation and Western Blot showed that HMW HA inhibited the expression of NLRP3,ASC and caspase-1 protein as compared with rats without HMW HA treatment,which indicated that the intervention mechanism of HMW HA on LPS-induced inflammation was related to NLRP3 inflammasome.Conclusion: In vitro and Experimental results in vivo indicated that HWM HA had a therapeutic effect on LPS-induced acute lung injury in mechanical ventilated rats.And experimental results in vitro indicated that NLRP3 inflammasome was a main pathway of HWM HA treating LPS-induced inflammation in NR8383 cells. |
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