A Clinical Study Of Iron Overload And Ferroptosis In Acquired Aplastic Anemia

Bone marrow failure(BMF)is a group of syndromes that cause low hematopoietic function or failure of hematopoietic stem/progenitor cells due to various reasons,and are manifested as reduction of one or more lines of blood cells.According to the causes,BMF is divided into two categories:hereditary and acquired.Hereditary bone marrow failure mainly includes fanconi anemia(FA),congenital dyskeratosis,shwachman-diamond and other diseases.It is a group of rare genetic heterogeneous diseases,Patients are often characterized by congenital malformations,marked reduction of whole blood cells and susceptibility to malignancy.Aplastic anemia(AA)is the most common form of acquired bone marrow failure,mainly performance with different degrees of anemia,bleeding and infection.Because of advances in molecular genetics in diagnosing the causes of bone marrow failure,the differentiation between heritability and availability is the key to comprehensive treatment,and the cause of disease significantly affects the treatment choice.Patients with bone marrow failure(BMF)rely on blood transfusion in order to maintain basic quality of life for a long time,but not the body excrete excess iron metabolism,the longer it will cause the body load of iron overload,excessive iron deposition to organ or tissue parenchyma cells,the affected organ extensive fibrosis,which degrades viscera function[1-5].Acquired AA is a disease of the blood system that,under the action of many harmful factors,causes a decrease in the hematopoietic tissue of the bone marrow,which makes it difficult for the remaining bone marrow hematopoietic stem cells to compensate effectively,and then leads to peripheral hemopenia.It is more common in acquired bone marrow failure.According to statistics,the incidence of AA was two of one million in European and American countries,the incidence of Asian countries was 2-3 times than European and American countries,about 3.9-5.0 of one million.the incidence of our country is 7.4 of one million[6],seriously affect the patients quality of life and life safety,how to further improve the clinical curative effect is always the research hot spot and the difficulty.It has been observed that patients with acquired AA often have abnormal iron metabolism and iron overload,accompanied by increased lipid reactive oxygen species and iron chelating agents can improve bone marrow hematopoiesis,but the specific mechanism is still unclear.Ferroptosis[7]is newly discovered in recent years,a kind of iron dependencies,lipid active oxygen increased as the characteristic mode of cell death,can be inhibited by iron chelating agents,this is consistent with the clinical observation of acquired AA patients,so it can be speculated that ferroptosis may be involved in the process of bone marrow hematopoietic cell injury of acquired AA.ferroptosis inhibitors may improve the function of bone marrow hematopoietic,enhance the role of clinical efficacy.To confirm this speculation,we design the study,include the 71 subjects are based on the acquired AA patients,the changes of iron overload index in peripheral blood,lipid peroxidation correlation index and ferroptosis metabolic index in bone marrow fluid were detected,to confirm that iron overload and its induced ferroptosis through lipid peroxidation pathway were involved in bone marrow hematopoietic stem cell injury in acquired AA patients.for subsequent research on acquired AA bone marrow hematopoietic stem cell damage mechanism,and the optimization of acquired AA treatment strategies to lay the foundation.PurposeBy measuring acquired AA patients with different bone marrow failure degree group and the control group the levels change of the iron overload indexes serum iron(SI)and serum ferritin(SF),and bone marrow supernatant total glutathione(GSH),glutathione peroxidase 4(GPX4),malondialdehyde(MDA)of lipid peroxidation correlation indexes,and ferroptosis metabolic index prostaglandin-endoperoxide synthase 2 mRNA.To confirm that iron overload and its induced ferroptosis by lipid peroxidation pathway are involved in the injury process of bone marrow hematopoietic stem cells.Materials and MethodsRetrospective collected clinical data of 71 acquired AA patients with 2ml peripheral blood and 8ml bone marrow fluid(including the first diagnosis of severe aplastic anemia and non-severe aplastic anemia and reexamination after treatment)in our hospital from February 2018 to October 2019.There were 35 males(49.3%)and 36 females(50.7%),with a median age of 31(9-61)years.AA classification was conducted according to the consensus of Chinese experts on the diagnosis and treatment of aplastic anemia(2017 edition)and the international Camitta standard[6],Among them,there were 26 cases of non-severe aplastic anemia(NSAA,36.6%),34 cases of severe aplastic anemia(SAA,47.9%),and 11 cases of very severe aplastic anemia(VSAA,15.5%).In addition,peripheral blood(2ml)and bone marrow fluid(8ml)from 25 normal subjects were taken as the normal control group,including 12 males and 13 females,with a median age of 35(12-65)years.Bone marrow biopsies were performed on 71 AA patients after admission to hospital,the patients with congenital bone marrow exhaustion were screened and excluded.According to the degree of bone marrow hematopoietic stem cell proliferation was divided into four groups,Normal recovery group:the degree of bone marrow hematopoietic stem cell proliferation?50%accounted for 11.3%(8/71);Mild failure group:the degree of hematopoietic stem cell proliferation?30%of normal,but<50%accounted for 32.4%(23/71);Moderate failure group:the degree of hematopoietic stem cell proliferation?10%of normal,but<30%accounted for 32.4%(23/71);Severe failure group:the degree of hematopoietic stem cell proliferation<10%accounted for 23.9%(17/71).Moreover.The contents of SI and SF in peripheral blood and the levels of bone marrow supernatant total GSH,GPX4 and MDA in bone marrow fluid in patients of each group and the normal control group were detected with each kit.In addition,PCR method was used to detect the expression levels of PTGS2 mRNA in bone marrow fluid of patients in each group and the normal control group.Results1.By observing the test results of 71 cases of acquired AA patients,it was found that patients with Severe bone marrow failure group the levels of SI,SF,lipid peroxidation products MDA,and PTGS2 mRNA were the highest,but the bone marrow supernatant total GSH,GPX4 content is the lowest;The moderate bone failure group was next;The bone marrow returned to normal group the contents of SI,SF,MDA,and PTGS2 mRNA is the lowest,but the bone marrow supernatant total GSH,GPX4 is the highest,and there were statistical differences among each group(P<0.05).2.The comparison between the normal control group and the normal bone marrow recovery group showed a statistically significant difference in SF contents(P<0.01),but there was no statistical differences in SI,bone marrow supernatant total GSH,GPX4,MDA and PTGS2 mRNA(P>0.05).The comparison between the normal control group and the mild or above bone marrow failure group showed that there were significant statistical differences among the indexes(P<0.01).Conclusion3.This study starts from iron overload and its induced ferroptosis by lipid peroxidation,to expound the correlation between the damage degree of bone marrow hematopoietic stem cells and iron overload index,lipid peroxidation correlation index and ferroptosis metabolism index,thus confirming that the damage degree of bone marrow hematopoietic stem cells in acquired AA is closely related to iron overload and its induced ferroptosis.4.For acquired AA patients with significant iron overload,on the basis of immunosuppression and hematopoietic therapy,combined with the changes of iron overload,ferroptosis and other related indexes,as well as the unique ferroptosis form characteristics of hematopoietic stem cells under fluorescence microscope,early combined with iron chelating agent and antioxidant treatment.This provides a new pathway for the treatment of acquired AA.