Study On The Immunosuppressive Effect And Mechanism Of Berkeleyacetal C From Penicillium Purpurogenum MHZ 11

Immune function is the important role in maintaining stability of internal environment by cleaning up invasive pathogens,damaged cells and mutant cells.However,hyperactivation of immune response will result in inflammatory diseases,allergic diseases and autoimmune diseases.Currently,the therapeutic drugs for these diseases have many defects,including unsatisfactory effects,excessive side effects,and low compliance of injection administration.It’s meaningful to develop novel immunosuppresents from natural products to improve therapy of these diseases.In this study,we isolated Berkeleyacetal C(BAC),a meroterpenoid compound,from the fungus Penicilium purpurogenum MHZ 111.BAC showed favorable activity of inhibiting the expression of inducible nitric oxide synthase(iNOS)and the following NO production by macrophages stimulated by lipopolysaccharide(LPS)in our preliminary screening,which may have a potential anti-inflammatory effect.Therefore,this study systematically investigated the regulatory effect of BAC on various natural immune cells such as macrophages,neutrophils,dendritic cells.RT-PCR and ELISA detected the expression and secretion of inflammatory factors and chemokines in macrophages induced by LPS,BAC was found to significantly inhibit LPS induced macrophage expression and secretion of tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),interleukin-1β(IL-1β),macrophage inflammatory protein-lα(MIP-lα),and monocyte chemotactic protein-1(MCP-1).The flow cytometry assays showed that BAC could significantly inhibit the shedding of CD62L and upregulation of CD11b on neutrophils induced by conditioned medium,as well as the production of reactive oxygen species by inflammatory conditioned medium and phorbol ester(PMA)induced neutrophils.LPS induced upregulation of costimulatory molecules expression and secretion of cytokines in dendritic cells.The flow cytometry results showed BAC decreased upregulation of costimulatory molecules CD80,detcreased expresstion and secretion of interleukin-12(IL-12)and interleukin-23(IL23),and promoted upregulation of CD86 on dendritic cells.In innate immune mechanism studies,western blot methods exploration found BAC selectively suppressed phosphorylation of inhibitor-κB(I-κB),extracellular signal-regulated protein kinases 1 and 2(ERK1/2),and interferon regulatory transcription factor 3(IRF3)during the activation of NF-κB,mitogenactivated protein kinase(MAPK),and IRF3 signaling pathways induced by LPS.and its target may be the common kinase upstream of these signaling pathways.This indicates that BAC has strong anti-inflammatory natural immunosuppressive activity.After inhibitory activity of BAC on innate immunity was discovered,we futher investigated the regulatory effects of BAC on various adaptive immune cells.The activation,proliferation and differentiation of CD4+T cells and CD8+T cells induced by CD3e and CD28 antibodies and the activation,proliferation and differentiation of LPS induced B cells were analyzed,the results showed that BAC had only a slight inhibitory effect on the activation and proliferation of CD4+T cells induced by CD3e and CD28.It had a significant inhibitory activity on the secretion of cytokine IL-4 by CD4+T cells,and only slightly inhibited the secretion of IFN-y,but strongly inhibited differentiation of CD4+T cells into helper T cells,especially Th2 cells.In addition,BAC significantly inhibited the proliferation of CD4+T cells which were induced by heterologous dendritic cells after co-cultured.Except for a weakly suppressive effect on activation of CD8+ T cells stimulated by CD3e and CD28,BAC exerted no inhibitory effects on proliferation and interferon-γ(IFN-γ)secretion of CD8+ T cells.For B cells,BAC slightly suppressed its activation and proliferation which were induced by LPS,but intensively inhibited its differentiation and antibody secretion.These results indicated that BAC exerts favorable innate and adaptive immunosuppressive activity,especially humoral immunity,and has potential to be developed into therapeutic drug for inflammatory diseases,allergic diseases and autoimmune diseases.