The Effect Of Dexamethasone And Vitamin D On The Expression Of Histone Deacetylase In Airways Of Allergic Mice

Objective: Histone deacetylase?HDAC?is a kind of protease which is widely exists in eukaryotic cells,it can make the histone deacetylase,thus play a role in the express of gene.Studies have found that the activity of HDAC is reduced in the patients with asthma,and increased histone deacetylase is associated with increased inflammatory cells,inflammatory mediators;Recent years have show that vitamin D3 in addition to regulate the metabolism of Calcium and phosphorus,it also can do something like differentiation and regulation in people's immune system,Studies have found that lack of 1,25?OH?₂D₃ may influence the pathogenesis of asthma,but it is still unclear in regulating the transcription of specific molecular mechanism.Recently,there has not report about the role of dexamethasone and 1,25?OH?₂D₃ on the expression of HDAC in bronchial of asthma.So we build OVA asthma mice model,using dexamethasone?Dex?and 1,25?OH?₂D₃ intervention,then to observe the expression and activity of HDAC2 in the airway,and whether it has synergistic effect with dexamethasone in the inhibition of inflammatory cytokine secretion,and discusses the influence of dexamethasone and 1,25?OH?₂D₃ on expression of HDAC2.Methods : The 50 female Balb/c mice?20-45g?were seperated 1-50:mices of 1-10 were in PBS group,mices of 11-20 were in OVA group,mices of 21-30 were in vitamin D group,mices of 31-40 were in dexamethasone group,mices of 41-50 were in vitamin D and dexamethasone group.Mice were sensitized respectively by i.p.injections on day 1and day 8,and challenged five times intranasally on day 22 to day 26.Mice from vitamin D group were treated by i.p.Injections 1,25?OH?₂D₃?0.25ug/kg?30 min before every challenge,while Mice from dexamethasone group were treated by i.p.Injections dexamethasone?1mg/kg?30 min before every challenge,We injected and challenge normal PBS to the mices of control at the same doses,everyday observe the condition of the mices,the last inspire,mice were killed after 24 hours,then collect the specimens.And lung biopsy pathological examination by hisopathologic examination,bronchoalveolar lavage fluid?BALF?for cell count;the serum IL-4 levels were evaluated using ELASA;The expression of NF-KB p65 in lung were determined respectively by RT-PCR while HDAC2 were tested by Western Blot.The data of IL-4?NF-KB p65 and HDAC2 were completed by one-way ANOVA.Results: 1?The amounts of the inflammatory cell are less in N group.In OVA group,the spirit and the appetite of the mices are loss,some visible mainland incontinence,the structure of lung tissue is damage,the lung of OVA group animals have a large number of inflammatory cells,some dead cells can be seen in the airway,mucosa become thickening,even can see lumen collapse;it is clear in the lung tissue,and inflammatory cells 's amounts are alleviated by trearment of Vitamin D and dexamethasone.2?Comparing with the PBS group,the total number of leukocytes and eosinophil are increased in M group?P < 0.05?,serum IL-4 levels are significantly increased in asthma mice?P < 0.05?;leukocytes and eosinophil amounts in vitamin D group or dexamethasone group is decreased in the OVA group?all P < 0.05?,the mice serum IL-4 content significantly decreased?P < 0.05?;comparing with the dexamethasone group,it is higher in vitamin D group?P < 0.05?.3?NF-k B p65 in lung of mice from OVA group are higher than the PBS group?P < 0.05?;with vitamin D or dexamethasone,the m RNA levels are significantly reduced?all P < 0.05?;the m RNA levels in dexamethasone group are reduced in the vitamin D group?P < 0.05?.4?Western:comparing with the PBS group,the level of HDAC2 protein in lung of mice from OVA group was obviously reduced?P < 0.05?,after treatment with vitamin D or dexamethasone the level of HDAC2 protein was improved?all P < 0.05?;the HDAC2 protein in dexamethasone is higher than vitamin D group?all P < 0.05?.Conclusions: 1?The level of NF-k B p65 are improved in OVA induced mice,and the expression of HDAC2 protein are descend.2?1,25?OH?₂D₃ can inhibit asthma mice inflammatory cells and Th2 cells secretion are reduced,and can down-regulate the level of NF-k Bp65,induced the expression of HDAC2 protein and its enzyme activity,thus reduce airway inflammation in asthma mice.3?In the inhibition of inflammatory cytokine secretion and the NF-k B p65 and HDAC2's level,1,25?OH?₂D₃ has synergistic effect with dexamethasone.4?1,25?OH?₂D₃ might be useful as a novel HDAC2 activator in the treatment of asthma.