Distribution Of Monocyte Subsets And Its Association With The Condition In Patients With Systemic Lupus Erythematosus

Background:Systemic lupus erythematosus(SLE)is an autoimmune disease characterized by the production of a variety of autoimmune antibodies and immune complexes and induction an abnormal immune inflammatory response,which involve the skin,joints,,kidney,heart,nerve and blood and other multi-system damage.At present,the etiology of SLE remains to be understood.Recently,the pathogenesis of SLE has been attributed to the immune dysfunction of adaptive immune cells,especially T and B lymphocytes,and the imbalance of cytokine network.However,with the in-depth study of Toll-like receptors(TLRs)and interferon(interferon,IFN),it is found that the activation of innate immunity plays an important role in regulating adaptive immune response,inflammation and tissue repair.Furthermore,the abnormal innate immune response and its products are also crucial pathogenic factors of SLE.Notably,monocytes derived from bone marrow myeloid stem cells are an essential participator of innate immunity,and are mainly distributed in the blood circulatory system.Monocytes were highly heterogeneous and plastic.and were classified into three subgroups by the International Federation of Immunology in 2010:CD14++CD16-classical monocyte(CM),CD14++CD16+ intermediate monocyte(IM),and CD14+CD16++ non-classical monocyte(NCM).Studies had shown that monocyte subsets in autoimmune diseases such as rheumatoid arthritis(RA),systemic sclerosis(SSc),dermatomyositis(DM),inflammatory bowel disease(IBD)were significantly different from those in healthy individuals.However,there were few studies on SLE,and the results were controversial.The proportion of the three subsets of monocyte and their correlation with clinical indicators have not been reported.To this end,our study aim to investigate the distribution of peripheral blood monocyte subsets in patients with SLE and their correlation with clinical markers.Objectives:1.To study the differences in the distribution of peripheral blood monocyte subsets between SLE patients and healthy individuals,and to determine whether they are related to SLE.2.To analyze the proportion of monocyte subsets in peripheral blood from patients with SLE and the correlation between monocyte subsets and clinical indicators,and to clarify the monocyte subset associated with the patient condition.Methods:1.SLE patients(n=67)were recruited as experimental group,34 patients in remission group(SLEDAI<4)and 33 patients in active disease group(SLEDAI>4)according to Systemic Lupus Erythematosus Disease Activity Index(SLEDAI),and 46 healthy individuals matched in sex and age were included as control group.2.Fresh peripheral blood samples were collected from the experimental and control groups and mixed with EDTA anticoagulant.Subsequently,Flow cytometry was used to detect the percentage of monocyte and its subsets(including CM,IM,NCM).The differences between SLE patients and controls were analyzed.3.The proportions of monocyte subsets(CM,IM,NCM)in peripheral blood of 67 SLE patients and 46 healthy subjects were collected,and ROC curves were established to analyze their diagnostic efficacy for SLE.4.The clinical and laboratory data of SLE patients were collected,including erythrocyte sedimentation rate of monocytes,erythrocyte sedimentation rate(ESR),C-reactive protein(CRP),C3,C4,antinuclear antibody(ANA)and anti-double-stranded DNA(ds-DNA)antibody and SLEDAI.The correlation of monocyte and its subpopulation in peripheral blood with each index was analyzed.Results:1.The absolute value of monocytes in the peripheral blood of SLE patients was significantly elevated compared with the control group[0.37(0.30,0.52)vs 0.29(0.24,0.34),P<0.05].The proportion of monocytes(%)was significantly higher in SLE patients than in controls[7.97(6.20,9.72)vs 5.37(4.85,6.66),P<0.05].The proportion of CM(%)in the peripheral blood of SLE patients was significantly decreased compared with the control group[92.31(88.38,94.45)vs 95.81(94.06,97.05),P<0.05],and the proportion of IM(%)in the peripheral blood of SLE patients was significantly increased compared with the control group[5.79(3.47,8.33)vs 1.97(1.35,3.32),P<0.05].While the proportion of NCM(%)had no significant difference[1.93(1.02,2.71)vs 1.87(1.11,2.67),P=0.9970].2.The number of monocytes in peripheral blood in the SLE remission group was significantly elevated compared with the control.group[0.39(0.29,0.54)vs 0.29(0.24,0.34),P<0.05],The proportion of monocytes(%)was significantly higher in SLE patients than in controls[8.03(6.30,9.35)vs 5.37(4.85,6.66),P<0.05],The proportion of IM(%)in the peripheral blood of SLE patients was significantly increased compared with the control group[3.64(1.63,5.80)vs 1.97(1.35,3.32),P<0.05],and the proportion of CM(%)[94.26(92.30,97.05)vs 95.81(94.06,97.05),P=0.0584]and NCM(%)in the peripheral blood of SLE patients[1.42(0.93,2.83)vs 1.87(1.11),2.67),P=0.5117]were not significantly different.3.The number of monocytes[0.37(0.30,0.50)vs 0.39(0.29,0.54),P=0.8395]and the proportion of monocytes(%)[7.97(5.98,10.93)vs 8.03(6.30,9.35),P=0.972]in peripheral blood in the SLE active group were not significant difference compared with remission group,The proportion of CM(%)in the peripheral blood of SLE patients was significantly decreased compared with remission group[90.66(85.02,92.30)vs 94.26(92.30,97.05),P<0.05],The proportion of IM(%)in the peripheral blood of SLE patients was significantly increased compared with remission group[7.89(5.82,10.27)vs 3.64(1.63,5.80),P<0.05],The proportion of NCM(%)in the peripheral blood of SLE patients was not significantly different compared with remission group[2.12(1.26,2.60)vs 1.42(0.93,2.83),P=0.2730].4.The diagnostic efficacy of CM and IM for SLE was analyzed using ROC curves.The results showed that CM for SLE diagnosis had an AUC of 0.7852,the 95%confidence interval of 0.7014 to 0.8690,the cut-off value of 94.47%,the sensitivity of 76.12%,the specificity of 73.91%,the Youden index of 0.5003(P<0.0001).IM for SLE diagnosis had an AUC of 0.8272,the 95%confidence interval of 0.7517 to 0.9027,the cut-off value of 3.93%,the sensitivity of 70.15%,the specificity of 89.13%,and the Youden index.of 0.5928(P<0.0001).5.The absolute value of peripheral blood monocytes,the proportion of monocytes and the proportion of CM in the remission group were not related to ESR,CRP,C3,C4,anti-dsDNA antibody and ANA,and the proportion of IM was only positively correlated with ESR.There was no correlation between the absolute value of peripheral blood monocytes or the proportion of monocytes and the above indicators in the active disease group.However,the proportion of CM was negatively correlated with the CRP and anti-ds-DNA antibody,as well as positively correlated with C3 and C4,but not associated with ESR and ANA.The proportion of IM was positively correlated with ESR,CRP,and anti-ds-DNA antibody,and negatively correlated with C3 and C4,but not correlated with ANA.Conclusions:1.The distribution of monocyte and their subpopulation in peripheral blood of SLE patients was significantly different from that of healthy individuals,which indicates that monocytes may play an important role in the occurrence and development of SLE.2.CM and IM have good diagnostic performance for SLE,which suggests that CM and IM may become new biomarkers of SLE.3.There is a correlation between CM and IM with disease activity indicators(ESR,CRP,complement C3,complement C4,anti-ds-DNA antibody levels)in SLE patients,which infers that CM and IM may become new effective biological indicators for evaluation disease condition of SLE.