Cyclosporine A Ameliorates Immune-mediated Aplastic Anemia By Inhibiting The Fatty Acid Metabolism Of T Cells

Aplastic anemia(AA)is a serious blood system disease threatening human health.At present,it is believed that the main cause of this disease is immune hyperfunction.The activation of lymphocyte must be accompanied by energy metabolism reprogramming of cells.However,the specific metabolic mode involved in the occurrence of AA is still unknown.In addition,cyclosporine A(Cs A),as a first-line treatment for it,can significantly inhibit the proliferation of lymphocytes in bone marrow(BM).Apart from the traditional classical pathway,it is also unclear whether it plays a therapeutic role by inhibiting lymphocyte metabolism.In order to solve the above scientific problems,the following three aspects are studied in this paper,aiming at providing potential drug targets and therapeutic strategies for the treatment of AA.Firstly,the phenotypic changes of AA and the efficacy evaluation of Cs A in the treatment of it were discussed.We used classical immunomediated method to construct aplastic AA mice model and treated with Cs A.On the 13 th day of onset,The body weight,peripheral blood,BM morphology,total number nucleated cells,HSC ratio and survival interval of mice were significantly decreased,accompanied by high expression of inflammatory factors inside and outside of BM.These indicators improved in varying degrees after intervention with Cs A,indicating that drug treatment was effective,which was consistent with clinical conclusions.Then we analyzed the BM niche associated with AA and found that MSC,vascular endothelial cells and megakaryocytes were damaged in varying degrees,accompanied by increased adipocyte production.This phenomenon can be partially reversed after treatment with Cs A,suggesting that Cs A has the function of protecting BM niche.Secondly,the proliferation and metabolic pathway of BM lymphocytes in AA and the effect of Cs A on this process were discussed.We examined the proportion and cycle status of lymphocytes,and found that T cells diffusely infiltrated BM and mainly in G1 phase,while after Cs A treatment,the proportion of lymphocytes decreased significantly with the cycle changing from G1 to G0 phase.Then the results of RNA-seq and flow pattern analysis showed that oxidative phosphorylation of mitochondria was the main metabolic pathway of T cells in AA,while the function of mitochondria decreased after the intervention of Cs A,indicating that it could inhibit oxidative phosphorylation of T cells.Finally,the specific energy-supplying materials involved in the metabolic reprogramming of BM lymphocyte in AA and the mechanism of Cs A on this process were discussed.We examined the absorptive capacity of T cells to glucose,and the results showed no difference,suggesting that the metabolic reprogramming mode of lymphocyte in AA was different from that in other diseases.Then the results of RNA-seq and flow pattern analysis confirmed that free fatty acids participated in metabolic reprogramming of lymphocyte,while the ability to absorb fatty acids increased than AA model after the intervention of Cs A,suggesting that Cs A may play a role by inhibiting fatty acid oxidation rather than fatty acid absorption,and subsequently confirmed that the key enzyme of Cpt-1a is its target.After that,we used Cpt-1a inhibitor to verify its function,and found that it is better than Cs A in improving AA.In conclusion,we firstly confirmed that free fatty acids are involved in the metabolic reprogramming of lymphocytes in AA and further extended the mechanism of Cs A in treating AA by inhibiting fatty acid metabolism of lymphocytes.This viewpoint could provide a new therapeutic idea for clinic.