Dexmedetomidine Promoted The Th1 Cell Differentiation Though STAT1/T-bet Pathway

BackgroundCD4⁺T helper cells respond to a variety of pathogens though regulating appropriate cell-mediated immunity and humoral immunity.T help 1?Th1?and T help2?Th2?cells derived from CD4 T helper cells are the key to protecting the host from pathogen invasion.The breakdown of the immune balance controlled by them was one of the important inducements in various immune dysfunctions.Surgery-induced imbalance of Th1/Th2 cells could inhibit the cell-mediated immunity,increasing the incidence of postoperative infection.Dexmedetomidine,as an?₂ adrenergic receptor agonist,has sedative and analgesic effects.Clinical studies suggested that dexmedetomidine could significantly increase the proportion of Th1 cells and shift the Th1/Th2 cells balance toward Th1cells to decrease the incidence of postoperative infection in patients.It has been reported that?₂ adrenergic receptors were expressed on the surface of T cells and participated in the differentiation of T cells.Thus,we speculate that dexmedetomidine may promote T cell differentiation to Th1 by activating?₂ receptors on the surface of T cells.T-bet,as one of the transcription factors,was described as the key transcription factor in the differentiation of Th1 cells.T-bet enhanced the expression of Th1characteristic genes IFN-?and IL-12 by changing the epigenetic or chromatin environment and induced Th1 cells differentiation.Then,the increased expression of IFN-?could strengthen T-bet expression and Th1 cell differentiation to form positive feedback regulation.Furthermore,T-bet down-regulated the expression of GATA3,a key transcription factor for Th2 cell differentiation,to inhibit the differentiation of Th cells to Th2 cells,and indirectly promoted T cells to drift to Th1 cell.Transcriptional signal transducer and activator-1?STAT1?,as a member of the STAT family,can regulate cell growth and differentiation.STAT1 specifically binds to the IFN-?promoter to enhance IFN-?expression.Inhibited Th1 cell differentiation and decreased T-bet expression in STAT1-/-mice suggest that STAT1 may regulate T-bet expression and participate in Th1 cell differentiation.We speculate that the enhancement of STAT1 phosphorylation induced by dexmedetomidine-activated?₂ receptors could increase the expression of T-bet to promote Th1 cell drift.The effect of dexmedetomidine could be reversed by?₂receptor antagonists and STAT1 inhibitors in CD4⁺T cells.Purposes1.The purpose of this study is to determine the effect of dexmedetomidine in Th1 cells differentiation.2.To investigate whether dexmedetomidine promotes Th1 cell drift through the STAT1/T-bet pathway.Methods1.Purified CD4⁺T cells were activated by CD3 antibody and CD28 antibody.Then,different concentrations of dexmedetomidine were added to stimulate cells for 6hours.Flow cytometry was used to detect the proportion of Th1 and Th2 cells.RT-PCR and ELISA were used to measure IFN-?and IL-4 expression and concentration,respectively.2.Purified CD4⁺T cells were activated by CD3 antibody and CD28 antibody.Then,Cells were stimulated with 0.1 nM dexmedetomidine for 6h in the presence or absence of the?₂ receptor inhibitor atipamezole.Western blotting was used to determine the STAT1 phosphorylation level and T-bet expression.At the same time,the mRNA levels of T-bet and GATA3 was tested by RT-PCR.3.Purified CD4⁺T cells were activated by CD3 antibody and CD28 antibody.Then,Cells were stimulated with 0.1 nM dexmedetomidine for 6h in the presence or absence of fludarabine?STAT1 inhibitor?.The phosphorylation of STAT1 and expression of T-bet were observed by western blotting.RT-PCR was also used to conform the mRNA levels of T-bet and GATA3.Results1.After dexmedetomidine stimulation,Th1 cell differentiation,IFN-?mRNA expression and concentration were significantly increased,especially the concentration of dexmedetomidine was 0.1 nM.However,there was no significant difference in Th2 cell ratio,IL-4 expression and concentration.2.After dexmedetomidine stimulation,phosphorylated STAT1 levels?p-STAT1?,T-bet mRNA and protein levels were increased,but GATA3 mRNA expression had no significant changes.3.After the cells were co-stimulated by atipamezole and dexmedetomidine,the ratio of Th1 cells,IFN-?mRNA level and content,STAT1 phosphorylation level,T-bet mRNA and protein levels were significantly decreased.4.After the cells were co-stimulated by fludarabine and dexmedetomidine,the ratio of Th1 cells,IFN-?mRNA level and content,T-bet mRNA and protein levels were significantly decreased.Conclusions1.Dexmedetomidine induced Th1 cell differentiation by directly activating?₂receptors on the surface of T cells,especially at a concentration of 0.1 nM.2.STAT1 phosphorylation levels and T-bet expression were increased in dexmedetomidine-induced Th1 cell differentiation.This effect could be reversed by atipamezole and fludarabine,indicating that dexmedetomidine promoted Th1 cell drift through the STAT1/T-bet pathway after activating?₂ receptor.