Dihydroartemisinin Can Improve The Symptoms Of SLE By Delaying The Senescence Of MDSCs

Systemic lupus erythematosus(SLE)is a typical autoimmune disease.Its main pathological features are dysfunctional B and T lymphocytes,multiple autoantibodies,and multiple systems and multiple systems.The disease progress is slow and the duration is long.SLE has high morbidity and high mortality high morbidity and high mortality.It is generally believed that the occurrence of SLE may involve genetic factors and environmental factors,and the body's immune tolerance against self-generated nuclear antigens makes the body produce a large number of anti-nuclear antigen antibodies,and then produce chronic inflammation,resulting in varying degrees of damage to tissues and organs.Lupus nephritis is one of the more serious manifestations of the secondary response to this disease,but the specific pathogenesis is not yet clear.In recent years,researchers have found that innate immunity may play an extremely important role in autoimmune diseases.In the autoimmune response,myeloid cells plays important role in immune response to the endogenous molecules released by self cell death,endogenous dangerous signal-damage related molecular patterns(DAMPs),suggesting that the abnormal immune regulation may be the cause of the development of SLE.Myeloid-derived suppressor cells(MDSCs)are a population of immature and heterogeneous cell populations that differ significantly from myeloid-derived mature cells(macrophages,dendritic cells,and neutrophils).This group of cells is usually amplified in a large number of pathological conditions such as tumors,chronic inflammation and obesity,and plays an important immunosuppressive function.Some studies have shown that the accumulation and differentiation of MDSCs affect the course of SLE.Our group's previous study also found that MDSCs have a role in promoting the occurrence and development of lupus in the MRL/lpr mouse model of lupus,and female SLE patients have higher levels of MDSCs in peripheral blood than men.However,the functional status of MDSCs in SLE patients and lupus mice is not fully understood.Recently,it has been reported that not only SLE is closely related to aging,but also MDSCs have a certain correlation with aging.In elderly SLE patients,aging may promote the inflammatory response by affecting the function of immune cells;the number of MDSCs cells in elderly patients and mice changes significantly with age.However,studies have not yet been reported on whether aging of MDSCs can affect the course of SLE.Some studies have reported that the aging-associated nuclear transcription factor E2-associated factor 2(Nrf2)pathway can exert an antioxidant effect,which in turn regulates cellular senescence and inhibits the inflammatory response to some extent.Studies have shown that artemisinin can activate the Nrf2 pathway and reduce inflammation.Dihydroartemisinin(DHA),the derivative of artemisinin,its antimalarial efficacy is 10 times higher than artemisinin,and it is quick-acting and low-toxic.Among them,DHA has been found to significantly relieve SLE,but the relationship between DHA and Nrf2 and how it affects MDSCs are specific.The mechanism of action is unclear.Therefore,this study(1)examined the effects of DHA on SLE symptoms and changes in the number of MDSCs;(2)analyzed the aging of MDSCs in lupus mice 'and the delayed effects of DHA on the aging of MDSCs and its mechanisms.1.DHA can improve the symptoms of lupus mouse model and delay the senescence of MDSCs:We first divided the mice into five groups:normal group,normal dosing group,onset group,low dose treatment group,and high dose treatment group.Samples of 26-week-old mice were analyzed.It was found that the spleen tissues in the diseased mice were significantly swollen and the weight was significantly increased.The HE sections of the kidney showed significant infiltration of glomerular inflammatory cells,and renal pathological indicators such as ur:inary protein and blood urea nitrogen were similar.autoantibody IgM levels and renal tissue inflammatory factor gene levels also increased;electron microscopy showed that podocyte injury.In the high-dose DHA treatment group,the spleen morphology of the lupus model mice became significantly smaller,the weight was significantly reduced,the infiltration of glomerular inflammatory cells,urinary protein,urea nitrogen,IgM,podocyte injury,and inflammatory factors.Levels and other pathological indicators have improved.The effects of DHA on the aging of MDSCs in lupus mice were further analyzed.The detection indexes of cell senescence include:?-galactosidase staining was used to detect the number of senescent cells,and RT-PCR and WB methods were used to detect the gene expression and protein expression levels of senescence proteins P53 and P21,respectively.It was found that the aging of MDSCs in lupus mouse disease group was more obvious,but the senescence of MDSCs in DHA high-dose treatment group was slowed down.In order to detect the aging of MDSCs in the process of lupus pathogenesis,and the changes of the aggregation of MDSCs in different tissues,we used flow cytometry to detect the total MDSCs in bone marrow,kidney and spleen of different groups of mice.The results showed that the number of MDSCs in the diseased mice increased significantly,while the number of MDSCs in the treated group decreased.These results suggest that DHA may affect the aggregation of MDSCs and thus improve the symptoms of lupus.2.DHA delays the senescence of MDSCs by activating the NRF2/HO-1 pathway in lupus mice:To investigate the mechanism of DHA affecting the aggregation of MDSCs,we examined the gene and protein expression of antioxidant-associated Nrf2 and its downstream molecule,HO-1,both at the gene level and at the protein level.The results showed that in the diseased mice,the expression of Nrf2 and HO-1 was down-regulated with the aging of MDSCs,while the MDSCs of the treated mice showed an improvement in MDSCs senescence,and the expression of Nrf2 and HO-1 was up-regulated.It suggests that the improvement of MDSCs senescence by DHA is related to the activation of the antioxidant pathway Nrf2/HO-1.3.DHA delays aging of TLR7 agonists-R848-stimulated MDSCs:To further explore the mechanism of aging in MDSCs in lupus,we simulated the microenvironment of lupus somatostatin MDSCs in vivo,that is,stimulation of in vitro induced MDSCs with R848 which is the agonist of TLR7 and analysis of changes in MDSCs.The results showed that R848 could significantly induce the senescence of MDSCs,and the expression level of Nrf2/HO-1 gene and protein were down-regulated.Compared with R848 group,the aging of MDSCs was weakened,and expression of Nrf2/HO-1 was decreased.The protein expression of NRF2/HO-1 was increased.These results confirm that DHA can delay the senescence of MDSCs by activating the Nrf2/HO-1 pathway.In summary,dihydroartemisinin(DHA)can improve the symptoms of lupus mouse model,and can delay the senescence of MDSCs by activating the Nrf2/HO-1 pathway,thereby improving the course of lupus.