Phenotype Analysis Of Hematopoietic Stem Cell S100A8 Knockout Mice And The Effect Of S100A8 Knockout On Erythroid Development

Background:Anemia is a common complication of cancer patients.Up to 40%of cancer patients have been combined with anemia before treatment,namely cancerous anemia.Numerous studies have confirmed that the prognosis of patients with cancerous anemia is poor.The ability of anti-infection and anti-tumor immune response is significantly lower,which is an important factor affecting the poor prognosis of tumor patients.Therefore,an in-depth understanding of anemia caused by malignant tumors is of great significance to improve the anti-tumor efficacy and prolong the survival prognosis of patients.Our team has previously found that there is a new immunosuppressive cell population:CD45 positive erythroid progenitor cells(CD45~+EPCs),which cannot normally differentiate into mature erythrocytes,but play a similar immunosuppressive role as myeloid cells.It is not only one of the important factors for the deficiency of anti-tumor immune response,but also one of the important causes of anemia in advanced tumor-bearing body.This group of cells can significantly inhibit the anti-tumor immune response of CD8~+T cells,and its mature differentiation ability is significantly reduced.Therefore,in-depth study on the causes and mechanisms of EPCs differentiation obstruction is the key to remove host anemia.Earlier studies reported that the loss of Rps14 caused an increase in the expression of S100A8 in myeloid cells and further induced the activation of the P53 signaling pathway,which is the molecular mechanism of erythroid differentiation in patients with megaloblastic anemia.Addition of exogenous recombinant S100A8 to treat normal mouse-derived hematopoietic progenitor cells(HPCs)can replicate the blocked erythroid differentiation caused by the loss of Rps14,suggesting that S100A8 activation of the P53 pathway plays an important role in hindering erythroid differentiation.However,the specific effect of S100A8on erythroid differentiation under tumor-bearing conditions is unclear.More importantly,the level of S100A8 in the spleen and peripheral blood of the body was significantly increased in the tumor-bearing state.For this reason,this study intends to explore its possible role in the development of erythroid precursor cells under tumor-bearing conditions.In this study,we studied the expression of S100A8 and its receptor in CD45~+EPCs,constructed hematopoietic stem cell S100A8 gene specific knockout mice,preliminarily analyzed the phenotype and studied the differentiation and development of EPCs.Through this study,we explore the role of S100A8 in erythroid differentiation and provide a theoretical basis for subsequent research.Methods:1 Analyze the expression of S100A8 and its receptors in CD45~+EPCs2 Construction hematopoietic stem cell S100A8 specific knockout mice3 The effects of hematopoietic stem cells S100A8 specific knockout on erythroid differentiation in natural and anemia state were studied4 The effects of hematopoietic stem cells S100A8 specific knockout on erythroid differentiation in tumor model were studiedResults:1 The differentiation of CD45~+EPCs was impaired and CD45~+EPCs expresses S100A8and RAGE receptor1.1 The differentiation of CD45~+EPCs was blocked in tumor-bearing mice;1.2 CD45~+EPCs in tumor-bearing mice highly expressed S100A8 and receptor of advanced glycation endproducts(RAGE)receptor;1.3 CD45~+EPCs overexpressed S100A8 and RAGE receptors in patients with cancerous anemia.2 The specific knockout of hematopoietic stem cell S100A8 was successfully constructed2.1 The hematopoietic stem cell S100A8 specific knockout mice were successfully constructed by Beijing Biocytogen company;2.2 S100A8 specific knockout of hematopoietic stem cells can affect some phenotypes of offspring mice.3 In the natural and anemia state,S100A8 specific knockout of hematopoietic stem cells had no significant effect on erythroid differentiation3.1 In the natural state,there was no significant difference in the proportion of peripheral blood EPCs in flow cytometry;3.2 In the natural state,there was no significant difference in the proportion of spleen EPCs in flow cytometry;3.3 In the natural state,there was no significant difference in HGB,RBC,MCV,MCH,MCHC and HCT in tail vein blood;3.4 Normal development of organ cell morphology and structure in natural state;3.5 In the anemia state,there was no significant difference in the proportion of peripheral blood EPCs;3.6 In the anemia state,there was no significant difference in HGB,RBC,MCV,MCH,MCHC and HCT in tail vein blood;4 In the tumor microenvironment,S100A8 specific knockout of hematopoietic stem cells had no significant effect on erythroid differentiation4.1 The tumor volume of knock out(KO)mice was larger than that of wild type(WT)mice;4.2 In the tumor model,there was no significant difference in the proportion of peripheral blood EPCs in flow cytometry;4.3 In the tumor model,there was no significant difference in HGB and RBC in tail vein blood.Conclusion:1 Hematopoietic stem cell S100A8 specific knockout mice were successfully constructed for the first time;2 S100A8 specific knockout of hematopoietic stem cells had no significant effect on erythrocyte differentiation and development;3 Hematopoietic stem cell S100A8 specific knockout can affect hair and body weight of mice and the tumor volume of KO mice was larger than that of WT mice.