The Effect Of MiR-92a-3p In Plasmic Exosomes On Systemic Lupus Erythematosus And Its Molecular Mechanism

Systemic lupus erythematosus(SLE)is characterized by the production of autoantibodies against self-antigens,which may cause inflammation and damage tissue function in multiple systems and organs throughout the body.Kidney is one of the most common affected organs of SLE.Previous studies have confirmed that the pathogenesis of SLE is associated with the abnormal cell apoptosis and dysfunction of apoptotic cell clearance.Increased apoptosis has been observed in T cells,B cells,NK cells,glomerular cells and other tissue cells of SLE patients.Exosomes play an important role in the physiological and pathological processes,by delivering their signal cargo across plasma membranes of target cells.Several studies have demonstrated that exosomes can affect protein clearance,antigen presentation,immune response,exchanging of genetic material and tumor metastasis.Exosome is crucial to the environmental homeostasis in their patiental cells,because cells can expel their proteins,nucleic acids and various metabolic wastes through releasing exosomes.In addition,exosomes can also transfer their genetic materials including mRNA,miRNA and IncRNA to the target cells,regulate the expression of target genes,and enhance the activity of specific signaling pathways in target cells.Recent studies have shown that exosomes are associated with the pathogenesis of various autoimmune diseases,including rheumatoid arthritis,sjogren's syndrome and systemic lupus erythematosus.Studies have reported abnormal expression of exosome miRNA in plasma of SLE patients compared with healthy people.Moreover,the level of these miRNAs may be related to SLE activity and nephritis.However,there are few reports on the mechanism of exosomes and the internal miRNA in SLE.It is unknown whether they can participate in SLE progress through regulating apoptosis of blood or tissue cell.In this study,we focused on the effect of exosomes in plasma on SLE and its potential mechanism.We found that,on the one hand,the plasma exosomes of SLE patients could promote the apoptosis of human peripheral blood monocytes(PBMC)and increase the expression of inflammatory cytokines.On the other hand,they could be absorbed by human renal tubular epithelial cells HK2 and promote apoptosis.In order to screen for exosome miRNAs related with SLE,we applied high-throughput miRNA sequencing combined with a validation by RT-PCR.The result showed that the level of miR-92a-3p was significantly decreased in plasma exosomes of SLE patients.When considering the results with clinical indicators of SLE,we found that the miR-92a-3p level was significantly lower in active patients than that in non-active patients,and had a significantly negative correlation with SLEDAI score.In addition,the level of miR-92a-3p was negatively correlated with 24-hour urinary protein of patients,but positively correlated with C3 and C4.No correlation was found between miR-92a-3p level and gender,age,disease duration,immunosuppressant or autoantibody level.These results suggest that miR-92a-3p may be a potential marker for the diagnosis of SLE,the estimate of disease activity and judging the risk of lupus nephritis.In order to explore the regulation mechanism of miR-92a-3p in plasma exosome on SLE,we predicted and verified the target gene of miR-92a-3p and the possible signaling pathways with miRNA database,double luciferase reporting system and Western Blot.The results showed that miR-92a-3p could inhibit LATS2 gene expression through incomplete complementation with its 3' UTR.Consequencely,it inhibits the phosphorylation of YAP/TAZ.Then,we wonder if miR-92a-3p could affect renal tissue cells through LATS2,and which kind of cells is the target.The result of imunohistochemical staining on renal tissues showed that the expression of LATS2 was highly expressed in renal tubular epithelial cells.LATS2 expression in glomeruli was significantly lower than that in renal tubular epithelial cells,which expressed weakly only in some glomerular cells.Based on the 16 samples we have detected,LATS2 level in renal tubules and glomeruli of SLE patients is slightly higher than that in normal renal tissues.In addition,we also found that miR-92a-3p and its target genes could affect the apoptosis of PBMC and HK2 cells,and the expression of inflammatory cytokines.In summary,we found that plasma exosomes in SLE patients can affect disease activity by regulating inflammatory response and apoptosis of PBMC and renal cells.In addition,the regulating effect of exosomes may be realized through miR-92a-3p and its target gene LATS2.This study provides new insights into the role of exosomes in SLE,which is conducive to an in-depth understanding of the pathogenesis of SLE.It also provides a new thought for seeking biomarkers of SLE,monitoring disease progress,and screening potential drug targets for SLE.