The Imbalance Of Paravertebral Muscle And Its Mechanism In Adolescent Idiopathic Scoliosis

ObjectiveTo study the imbalance of paravertebral muscle volume and fatty infiltration rate in patients with adolescent idiopathic scoliosis(AIS)with primary thoracic scoliosis and the mechanism associated with microRNA.Methods1.Imaging measurementWe measured and calculated the muscle volume and fatty infiltration rate of deep paravertebral muscles on both sides at the level of the apical vertebra,upper end vertebra,and lower end vertebra through MRI on 34 consecutive AIS patients with primary thoracic scoliosis(Lenke I–IV).Then the relationship between the degree of imbalance and several radiographic parameters,such as the apical vertebral translation and coronal Cobb angle was analyzed.2.Identification of microRNAs profilesWe used paravertebral muscles tissues from 3 AIS patients who shared almost the same demographic and radiographic information such as Lenke classification,age at surgery,and conducted RNA sequencing to screen the differentially expressed miRNAs on two sides.Bioinformatics analysis was carried out to predict their function and roles in the imbalance of paravertebral muscles.3.Verification of the differentially expressedmicroRNAsWe confirmed 6 miRNAs’ expression in 22 AIS patients on two sides at the level of the apical vertebra,upper end vertebra,and lower end vertebra by qRT-PCR.Then the relationship between the expression ratio of miRNAs and several demographic and radiographic parameters,such as age at surgery and coronal Cobb angle was analyzed.4.Promoter CpG methylation profiling of C19MCWe used paravertebral muscles tissues from 4 AIS patients whose expression ratio of hsa-miR-516a-5p and hsa-miR-517a-3p on two sides was the highest and the results were consistent with the sequencing results,and conducted methylation sequencing.Results1.MRI measurement revealed significant asymmetry in muscle volume and fatty infiltration with larger volume on the convexity of the scoliotic curves and higher fatty infiltration rate on the concave side.Correlation test suggested that the difference index of muscle volume correlated significantly with apex vertebra translation(r=-0.749,p=0.032),while the difference index of fatty involution correlated significantly with apex vertebra translation and the Cobb angle(r=0.727,p=0.041;r=0.866,p=0.005).2.We screened out 18 differentially expressed miRNAs in paravertebral muscles of AIS patients on two sides,including 12 upregulated in the concave side and 6 upregulated in the convex side.Some of these differentially expressed mi RNAs are closely associated with the regeneration and fibrosis of skeletal muscle.3.Differentially expression of hsa-miR-495-3p 、 hsa-miR-516a-5p and hsa-miR-517a-3p was verified by qRT-PCR at the level of the apical vertebral in AIS patients,but not at the level of upper or lower end vertebrate.Correlation test suggested that the expression ratio of hsa-miR-516a-5pcorrelated significantly with age at surgery(r=-0.342,p=0.026),while the expression ratio of hsa-miR-517a-3pcorrelated significantly with the Cobb angle(r=-0.340,p=0.023).4.Methylation sequencing data showed significantly different methylation level of 2 detected CpG loci of C19 MC.Conclusion1.Our findings demonstrated a significant asymmetry in muscle volume and fatty infiltration in AIS patients.2.The mi RNA expression profiles in 2 sides of deep paravertebral muscles showed statistical significance.3.Differentially expression of 3 miRNA(miRNA-517,516,495)were verified in 22 AIS patients.4.The expression of miRNA-516,517 may be regulated by the promoter methylation of C19 MC.In conclusion,we illustrated the imbalance of the paravertebral muscle in AIS patients through MRI mearsurement and miRNA sequencing.The results of Methylation sequencing also implicated that epigenetics factors contributed to the muscle imbalance.