Effects Of Hemgn On Hematopoietic Stem Cells And Immune System Induced By Listeria Monocytogenes Inflammation

Objective Infections are epidemiologically associated with multiple hematopoietic stem cell?HSC?malfunction,such as acute myeloid leukemia,myelodysplastic syndrome,and aplastic anemia.The above hematologic malignancies are usually treated with HSC transplantation clinically.It is of great significance to treat various blood diseases from the perspective of the mechanism of disease occurrence.EDAG is a hematopoietic tissue and cell-specific expression gene that plays an important role in regulating HSC proliferation,differentiation and maintaining HSC lineage balance.Hemgn is a homologous gene of EDAG in mice.This study used Hemgn knockout(Hemgn^-/-)mice to establish acute infection and repeated infections by Listeria monocytogenes?LM?.The model initially explored the effect of Hemgn on HSC and immune system in LM-induced inflammation.Methods The acute infection and repeated infection models of Listeria monocytogenes were established by intraperitoneal injection.The expression of Hemgn in wild-type mouse bone marrow was detected by Western Blot.The number and proportion of the hematopoietic stem/progenitor cells?HSPC?were analyzed by flow cytometry.The proliferation of HSC was analyzed by Brdu incorporation method.The colony forming ability of mouse bone marrow and spleen cells was compared by clone formation test.The survival of knockout and wild type mice at different doses were monitored.The amount of bacteria in liver and spleen were detected.HE staining was used to observe pathological changes of liver and spleen,Gram staining was used to observe the degree of bacterial invasion,TUNEL staining was used to observe the apoptosis of spleen cells.Enzyme-linked immunosorbent assay?ELISA?and CBA method were used to detect interferon gamma?IFN??and other inflammatory factors in serum and spleen tissue homogenate supernatant.Blood cell analyzer and flow cytometry analysis of mouse peripheral blood cell composition.The number and proportion of mouse spleen immune cells were analyzed by flow cytometry.Results The expression of Hemgn was up-regulated in the bone marrow of wild-type mice after infection with Listeria monocytogenes for24 hours.The proportion of LSK,long-term hematopoietic stem cells?LT-HSC?,short-term hematopoietic stem cells?ST-HSC?,Brdu⁺LT-HSC,Brdu⁺LSK,and ROS levels in bone marrow were significantly elevated,the proportion of hematopoietic progenitor cells?HPC?,common myeloid progenitor cells?CMP?,granulocyte-macrophage progenitor cells?GMP?,megakaryocyte-erythroid progenitor cells?MEP?were significantly decreased,the proportion and number of spleen LSK were increased,the colony forming ability of bone marrow and spleen cells was decreased.In the repeated infection model,the proportion of hematopoietic stem cells?LSK,LT-HSC,ST-HSC?in bone marrow and spleen of Hemgn^-/-mice were lower than those of wild-type mice.In the acute infection model,Hemgn^-/-mice were rapidly succumb to infection in lethal and medium dose.HE staining in spleen and liver showed that the inflammatory reaction of Hemgn^-/-mice was severe.The results of tissue bacterial count and Gram staining showed that the pathogen in liver and spleen of Hemgn^-/-mice were significantly higher than those in wild type mice.The levels of IFN?,IL6,TNF and chemokine MCP-1 in the spleen of Hemgn^-/-mice were significantly decreased after 24 hours of infection.The number and proportion of lymphocytes in peripheral blood of Hemgn^-/-mice decreased,the number and proportion of granulocytes increased,and NK cells,T lymphocytes,DC cells and CCR2⁺granulocytes were significantly decreased in spleen,and there was no difference in the ratio of granulocytes,macrophages,B lymphocytes,and NKT cells.Conclusion Hemgn deletion significantly affects HSPC composition and cell cycle of mouse bone marrow in acute infection and repeated infection.Mice that lack Hemgn have a markedly increased susceptibility to infection with Listeria monocytogenes.Hemgn deficiency does significantly affecting the composition of white blood cells in peripheral blood and of NK cells,lymphocytes in spleen.It indicates that Hemgn plays an important regulatory role in HSC and immune response in the inflammation induced by Listeria monocytogenes.