The Roles Of BET Inhibitors JQ1 And I-BET726 In Regulating Inflammation And Attenuating Experimental Autoimmune Encephalomyelitis

The immune response is a series of physiological processes during which the immune cells recognize antigens,activate lymphocytes,generate molecules and perform certain immune functions.However,if the immune response is abnormal,there will cause severely histopathological damage.BET proteins are a group of epigenetic markers controlling transcription through reading acetylated histone tails and recruiting transcription complexes,but their regulative functions and detailed mechanisms in inflammatory response remain to be fully understood.In this study,we firstly investigated the impact of the BET bromodomain inhibition on LPS-induced maturation of BM-DCs.The expression of cell surface molecules was detected by flow cytometry.Furthmore,to determine whether BET proteins exert a direct effect on inflammatory response,cytokines in the BM-DCs and macrophages were analyzed using RT-PCR and quantitative real-time PCR.Subsequently,we use the MOG35-55-induced EAE mice,a model of MS,to evaluate the role of BET proteins in the development of inflammatory disease.Histopathologic examination of the spinal cords of EAE mice was carried out by HE and luxol fast blue(LFB)stain.Cytokine levels in the spinal cord were analyzed by quantitative real-time PCR.Finally,we explore the mechanisms of BET inhibitors in regulating inflammation and attenuating the development of EAE.The results showed that the increased expression of surface molecules CD40,CD54,CD80 and CD86 that occur in mature DCs stimulated by LPS were strongly attenuated by JQ1 and I-BET726.Moreover,JQ1 and I-BET726 lead to a suppressed generation of cytokines TNF-a,IL-12 and IL-6.Similarly,JQ1-and I-BET726-treated Raw264.7 macrophages exhibit markedly reduced production of proinflammatory cytokines in response to LPS.Furthermore,the BET inhibitors reduce antigen-specific T lymphocyte response in vivo.And then,we determined the BET inhibitors effectively attenuate the severity of neurological damage and reduce the clinical score of the EAE mice in vivo.Also,the JQ1 and I-BET726-treatments reduce the infiltration of inflammatory cells and mitigate the demyelination and myelin vacuolation in the spinal cords during the onset of EAE.We observed a reduction of inflammatory cytokines in the spinal cords of EAE/JQ1 and EAE/I-BET726 group mice.Finally,we found that the phosphorylation of PI3K-Akt and p38 MAPK pathways could be blocked by BET inhibitors in Raw264.7 cells.In conclusion,our articles showed that the BET inhibitors JQ1 and I-BET726 could profoundly affect initiaction of immune response by reducing the production of costimulatory molecules and inflammatory cytokines in dendritic cells.Besides,JQ1 and I-BET726 could also restrain inflammatory response of macrophages.In vivo experiments,administration of JQ1 and I-BET726 in the EAE model delayed onset of the disease and attenuated the inflammatory severity.Finally,our reseach primarily confirmed that the blocked PI3K-Akt and p38 MAPK pathways by BET inhibitors may be the underlying mechanisms.Nevertheless,these results demonstrate a potential therapeutic advantage of using BET inhibitors in inflammatory diseases.