The Determination And Clinical Significance Of Peripheral Monocyte Subsets In Patients With Idiopathic Inflammatory Myopathy

Objective:Idiopathic inflammatory disease（IIM）is a group of heterogeneous autoimmune diseases that predominantly involve the proximal muscles of the extremities or with characteristic cutaneous manifestations,and often be accompanied by organ involvement such as interstitial lung disease.IIM can be divided into different subtypes such as dermatomyositis（DM）,anti-synthetase syndrome（ASS）,and immune-mediated necrotizing myopathy（IMNM）.This study aims to explore the clinical significance and mechanism of action of monocytes subsets in IIM by comparing peripheral blood monocyte cell and its subsets:classical monocyte,CD14⁺⁺CD16^-（mon1）;intermediate monocyte,CD14⁺⁺CD16⁺（mon2）;non-classical monocyte,CD14⁺CD16⁺⁺（mon3）in the distribution level of IIM patients and healthy people,the difference in the distribution level of different subsets of IIM patients,and the correlation with clinical indicators.Methods:A total of 70 hospitalized patients（30 cases of DM,34 cases of ASS）diagnosed with idiopathic inflammatory myopathy from October 2021 to November2022 were enrolled,and clinical data such as general information,clinical manifestations,myositis antibody profile,myocardial enzyme profile,serum cytokines,inflammatory biomarkers,lymphocyte subsets,arterial oxygen partial pressure,pulmonary ventilation and diffusion function test,lung HRCT and other clinical data were collected.The blood routine results of 210 healthy people who were examined at the physical examination center during the same period were collected for the comparison in peripheral blood monocyte level.Peripheral blood monocyte subsets levels in 70 IIM patients,19 non-IIM CTD disease controls,and 21 healthy volunteers were measured by flow cytometry and the monocyte subsets of IIM patients were analyzed in relation to various clinical data.The independent sample t-test was used to compare the differences between the two groups of normally distributed data,and one-way analysis of differences（ANOVA）and Bonferroni correction were used to compare the differences between multiple groups.The non-normal distribution data was compared by Mann-Whitney U test for two groups and the Kruscal-Wallis H-test and Dunn test were used to compare the differences in multiple groups.The correlation between the two variables was assessed by Spearman’s rank correlation coefficient,and the counting data were compared by Chi-square test.P<0.05 was regarded as statistically significant.Results:1.Patients with idiopathic inflammatory myopathy have higher peripheral blood monocyte counts than healthy controls（P<0.05）.2.The mon1%was higher in IIM patients than in healthy controls and disease controls（90.95（87.33,94.10）%vs 86.60（83.00,90.20）%vs 87.90（78.85,89.40）%,all P<0.01）,and the mon3%was lower（1.18（0.51,2.72）%vs 4.16（2.84,5.11）%vs 4.68（3.26,7.61）%,all P<0.01）.Mon1%were higher in patients with DM and ASS than in healthy controls（92.40（87.08,94.22）%vs 90.70（87.10,93.60）%vs 87.90（78.85,89.40）%,all P<0.01）,and was higher in patients with DM than in disease controls（92.40（87.08,94.22）%vs 86.60（83.00,90.20）%,P<0.05）.Mon3%and the absolute count of mon3 in patients with DM and ASS were lower than those in the healthy controls and the disease controls（mon3%,DM 0.87（0.29,1.95）%,ASS 1.65（0.59,3.22）%vs HCs 4.68（3.26,7.61）%;DM 0.87（0.29,1.95）%,ASS 1.65（0.59,3.22）%vs CTDs 4.16（2.84,5.11）%,all P<0.01;absolute count of mon3,DM 5.10（1.19,10.86）M/L,ASS 9.95（31.95,18.04）M/L vs CTDs 27.63（13.99,38.07）M/L,all P<0.001）.3.The mon3%was positive correlated with CD4⁺T cell,CD3⁺T cell,CD8⁺T cell and eosinophil in DM patients（r=0.399,r=0.463,r=0.384,r=0.477,all P<0.05）and was negative correlated with Ig M,D-D dimer,ESR,CK,LDH,AST,ALT（r=-0.412,r=-0.552,r=-0.553,r=-0.421,r=-0.494,r=-0.498,r=-0.452,all P<0.05）.The absolute count of mon3 was negative correlated with Ig M,D-D dimer,ESR,CK,LDH,AST,ALT and Fg（r=-0.451,r=-0.452,r=-0.651,r=-0.409,r=-0.407,r=-0.502,r=-0.399,r=-0.424,all P<0.05）.Mon3%and the absolute count of mon3 in DM patients with serum ferritin≥500ug/L were lower（0.34（0.11,0.87）%vs 2.03（0.97,3.09）%;1.19（0.67,4.38）M/L vs 1.97（7.01,16.77）M/L,both P<0.01）.4.In ASS patients,mon1%was positive correlated with the count of neutrophils（r=0.414）and negative correlated with KL-6（r=-0.520）while mon2%positive correlated with KL-6（r=0.571）and mon3%negative correlated with neutrophil counts（r=-0.553）and positive correlated with eosinophil counts（r=0.373）,all P<0.05.The count of mon3in ASS patients with elevated serum ferritin was lower（3.09（1.51,6.88）M/L vs 10.97（10.04,28.66）M/L,P<0.05）.5.There were no statistically significant differences in the proportion and absolute count of peripheral blood monocyte subsets in the Ro-52-positive and negative group in IIM patients.Similarly,there was no statistical difference in the proportion and absolute count of peripheral blood monocyte subsets in the Ro-52 positive and negative group in ASS and DM patients.6.The mon3%in patients with swallowing muscle involvement in DM was lower（0.30（0.11,1.10）%vs 0.93（0.47,2.78）%,P<0.05）.Mon3%and the absolute count of mon3were lower in DM patients with shortness of breath or dyspnea（0.53（0.22,0.91）%vs1.53（0.51,3.00）%,P<0.05;1.70（0.73,5.18）M/L vs 10.14（1.79,16.45）M/L,P<0.01）and lower in DM patients with elevated CK（0.41（0.12,0.86）%vs 1.32（0.53,2.82）%,P<0.001;1.75（0.73,5.14）M/L vs 7.95（1.70,15.56）M/L,P<0.05）and DM patients with elevated LDH（0.69（0.25,1.27）%vs 3.00（2.75,5.92）%,P<0.01;2.01（0.91,8.76）M/L vs 16.37（14.25,26.32）M/L,P<0.01）.7.The mon1%was higher in ASS-ILD patients with moderate to severe pulmonary involvement and the mon3%was lower.Patients with moderate to severe involvement in MDA5-ILD had lower mon3%and lower absolute count of mon3 than that in ASS-ILD（0.53（0.23,1.25）%vs 1.39（0.53,2.50）%;1.70（0.70,8.00）M/L vs 6.90（3.10,11.30）M/L both P<0.05）.Conclusion:The number of peripheral blood monocyte in IIM patients increased,and the distribution of mon1 and mon3 was different from that of healthy and disease controls.The levels of monocyte subsets,especially mon3,were different in ASS and DM and associated with different clinical manifestations and laboratory biomarkers,especially mon3,in patients with DM was related to CD4 and CD8 T lymphocyte while in ASS patients was correlated with neutrophil count.The distribution of monocytes subsets was associated with the degree of lung involvement of ASS and the moderate to severe degree of MDA5-ILD,especially the reduction of mon3%,suggesting that moderate to severe IIM-ILD,especially MDA5-ILD,may be related to mon3 chemotaxis and can be used as a potential therapeutic target.No differences in myositis specific auto-antibodies were observed within the DM and ASS subgroups.