Research On The Role Of LSD1 In Macrophage Immune Characteristics Transformation And Its Related Mechanisms

Macrophages present in almost every tissues,plays an important role in immune defense.Macrophages show a remarkable degree of plasticity,when microenvironment changes,macrophages phenotype and function would also alter correspondingly.Epigenetics can regulate the plasticity of macrophages.In recent years,more and more evidences show that epigenetic can regulate macrophages gene expression and then affect macrophages polarization.Among them,histone lysine-specific demethylase LSD1 not only regulates hematopoietic stem cell(HSC)differentiation and tumor epithelial mesenchymal transformation(EMT),but also plays an important role in B cells development and an increase in tumor immunogenicity.Based on the potential of LSD1 in immune regulation,we would explore whether LSD1 plays an important role in regulate macrophages polarization.Firstly,we induce monocytes differentiate into macrophages in vitro,and then further induce macrophages into classically activated macrophages(M1)and alternative activated macrophages(M2).To explore whether LSD1 can regulate macrophage polarization,we respectively suppress LSD1 enzyme activity or silence LSD 1 expression,assess LSDl's role in regulating macrophages polarization,by measure the change of macrophages morphology,surface markers,cytokine,and phagocytosis.Results show that,using LSD1 inhibitors(ORY1001 to inhibit LSD1 enzyme activity or restraining LSD1 expression,all of these can polarize macrophages to M1.In macrophage whose LSD1 has been inhibited,the morphology is more closely to M1,the expression of pro-inflammatory cytokines(MCP1,IFN-y,TNF-?)were increased significantly,the expression of anti-inflammatory cytokines(TGF-?,VEGF)were significantly reduced,the expression of M1 markers(CD80,CD86,HLA-DR)were significantly increased,and the phagocytic was also significantly enhanced.All of the above results fully proved that LSD1 plays an immportant role in macrophage polarization,inhibit LSD1 can induce macrophage polarize to M1.Tumor-associated macrophages(TAMs)are an important part of the tumor microenvironment and can promote tumor proliferation,metastasis and angiogenesis,similar to M2.We have proved that inhibit LSD1 can induce macrophage polarize to Ml and enhance its immune function.Based on the above,we would further explore whether LSD1 inhibition can switch TAMs transformation from M2-type to Ml-type.Considering that TAMs is a highly heterogeneous groups,to fully explore the role of LSD1 in TAMs,we respectively inhibit LSD1 in M1,M2 and TAMs,evaluate the change of macrophages polarization.The results showed that,inhibit LSD1 could further enhance the pro-inflammtory function of M1.We can see that,after inhibit LSD1 in M1,the expression of pro-inflammatory cytokines(IL-1,IL-6,IL-12,TNF-?,MCP1)was significantly increased,the secretion of pro-inflammatory cytokines TNF-? was significantly increased,the expression of M1 marker CD86 was significantly enhanced,and then the phagocytosis was also been significantly heightened.In addition,inhibit LSD1 in M2 can reverse its phenotype and function.LSD1 Inhibition in M2 would result in the significantly decreased expression of anti-inflammatory cytokines(IL-10,VEGF,MMP9),the significantly increased expression of pro-inflammatory cytokines(MCP1,IL-6,TGF-?),and the significantly enhancement in macrophages phagocytic.Subsequently,we further found that,inhibit LSD1 in TAMs can significantly impact the ability of TAMs in promote gastric cancer cells proliferation and metastasis,significantly promote the apoptosis of gastric cancer cells.The above research shows that inhibit LSD1 in macrophages under different polarization states all can promote inflammation,reverse the tumor-promoting phenotype to anti-tumor phenotype.Based on the above,we preliminarily explored the molecular mechanism of LSD1 in macrophages polarization,and found that TLR4-NF?B is the way which LSD1 though it to affect the polarization of macrophages.Inhibition of LSD1 can promote the phosphorylation of NF?B p65,thereby activating the transcription of pro-inflammtory cytokines(such as TNF,IL-12,MCP1,and so on),so as to promote the inflammatory response.In summary,inhibition of LSD1 can not only enhance the pro-inflammtory function of M1 in M0 and M1,but also can reverse the tumor-promoting phenotype of M2 and TAMs to anti-tumor phenotype,so as to achieve the purpose of anti-tumor.Therefore,targeted LSD1 in macrophages may be a new way in tumor therapy.