The Effect And Mechanism Of HMGN2 On Immunity Of Neutrophil

Background: Neutrophils are the first line of defense against bacteria,fungus and other pathogens.When the body is infected,neutrophils rapidly migrate to the site of infection and eliminate pathogenic microorganisms through phagocytosis,degranulation,release of reactive oxygen species and inflammatory factors.The abnormal function of neutrophils will cause the body to face the risk of serious infection.HMGN2 is an important chromatin framework regulatory protein in eukaryotic cells and an important immunomodulatory molecule in the body.HMGN2 has been shown to affect the function of natural immune cells to fight infection by regulating multiple mechanisms including cell adhesion,skeleton rearrangement and oxidative stress.Through database analysis,it was found that,compared with other immune cells,HMGN2 molecule was significantly highly expressed in neutrophils.Moreover,the preliminary experimental data of our team demonstrated that HMGN2 knockout could affect the immune function of neutrophils,suggesting that HMGN2 may be involved in regulating the immune function of neutrophils against microbial infection.Purpose: To study the effects and regulatory mechanism of HMGN2 on the immune function of neutrophils against bacteria.Methods: In this study,we used Cre/Loxp technique to construct conditional neutrophil HMGN2 knockout mice.The effects of HMGN2 on the bacterial clearance and neutrophil recruitment ability of neutrophil were investigated through bacterial infection model.In vitro,the effects of HMGN2 on neutrophils phagocytosis,LPS induced expression of inflammatory cytokines and chemokines were detected by flow cytometry and RT-q PCR.Cut&Tag and transcriptome sequencing,as well as molecular biological technique were used to analyze the potential downstream mechanism of HMGN2 in regulating the anti-bacterial immune function of neutrophils.Results: Compared with control mice,bacteria load was increased in organs of HMGN2 conditional knockout mice upon infection,and the local recruitment of neutrophil in HMGN2 conditional knockout mice was decreased.In vitro,HMGN2 knockout showed reduced neutrophil phagocytosis and reduced expression of inflammatory cytokines and chemokines compared with controls.Transcriptomic sequencing analysis revealed that HMGN2 knockout caused changes in the transcription profile of neutrophils induced by LPS.Through differential gene analysis,hierarchical clustering of gene expression and pathway enrichment analysis,it was found that differential genes were mainly enriched in immune-related pathways,including NF-κB,MAPK and cytokine expression regulation.Association analysis of Cut&Tag and transcriptome sequencing showed that 47 genes in LPS-activated neutrophils were directly regulated by HMGN2,and Ezh2 expression was significantly enhanced after HMGN2 knockout.Conclusion: HMGN2 is involved in the regulation of anti-bacterial immune response of neutrophils,which may promote the expression of immune-related genes by reducing Ezh2 expression,and ultimately enhance and maintain the neutrophilmediated anti-bacterial immunity.