The Mechanism Of Abnormal Soluble Leptin Receptor Level In Adolescent Idiopathic Scoliosis And Clinical Studies About Spinal Deformities

Chapter 1 The mechanism of abnormal soluble leptin receptor level in adolescent idiopathic scoliosisBackground:Adolescent idiopathic scoliosis(AIS)is the most common three-dimensional spinal deformity which mainly affects the adolescent girls aged 10-16.If left untreated,the spinal deformity could develop continuously and the patient may die from respiratory and circulation failure.Despite decades of research,the etiology and pathogenesis of AIS remains largely unknown.Previous anthropometric studies have reported an abnormal growth pattern in AIS which was considered to play an important role in the pathogenesis of AIS.AIS patients are reported to have taller stature and peak height velocity,lower weight and body mass index(BMI)and systemic low bone mass.Many researchers put forward different theories to explain this abnormal growth pattern.Among them,the leptin theory has received wide concern.Leptin,a hormone excreted by adipose tissue,plays an important role in regulating energy expenditure,bone metabolism,body weight,and the hypothalamic-pituitary function.indicated that the abnormal leptin function may contribute to the development and progression of AIS.Soluble leptin receptor(sOB-R),generated by shedding of membrane-anchored leptin receptors,is the key to regulate the transmembrane transportation and the bioavailability of leptin.Previous studies showed that AIS girls have significantly higher serum sOB-R level and lower free leptin index(FLI,leptin/sOB-R,indicating the bioavailability of leptin)than age-matched healthy girls.These results highly indicated that the abnormal leptin bioavailability caused by abnormal sOB-R level may play an important role in the abnormal growth pattern and the pathogenesis of AIS.However,the mechanism of elevated sOB-R level in AIS remains unknown.As A Disintegrin and Metalloproteinase(ADAM)is the key enzyme regulating the generation of sOB-R,this study would further investigate the role of ADAM in the abnormal serum sOB-R level in AIS.Section 1 The mechanism of generation of soluble leptin receptorObjectives:To identify the ADAM family members that participate in the generation of sOB-RMaterials and Methods:We constructed stable cell lines overexpressing human leptin receptors(OB-Ra and OB-Rb)by constructing lentivirus vectors and transfecting them into 293T cells which express different ADAM family enzymes.Divide the cells into subgroups and add AD AM10 inhibitor GI254023X(GI),AD AM10 and AD AM17 inhibitor GW280264X(GW)into different subgroups.Identify the ADAM family members that participate in the generation of sOB-R by evaluating and comparing the sOB-R level of different subgroups.Results:1.The leptin receptor mRNA expression level was significantly higher in cell lines overexpressing human leptin receptors(OB-Ra and OB-Rb)than in controls.Stable cell lines overexpressing OB-Ra and OB-Rb were successfully constructed.2.In GI group and GW group of cell lines overexpressing OB-Ra,the leptin level decreased by 45.0%and 51.4%after incubation for 24h,and decreased by 52.1%and 61.0%after incubation for 48h.3.In GI group and GW group of cell lines overexpressing OB-Rb,the leptin level decreased by 38.5%and 36.8%after incubation for 24h,and decreased by 46.2%and 51.1%after incubation for 48h.Conclusion:The stable cell lines overexpressing OB-Ra and OB-Rb were successfully constructed.The generation of sOB-R mainly relies on ADAM 10 by shedding of membrane-anchored leptin receptors.Section 2 The relationship between ADAM level and abnormal soluble leptin receptor level in AISObjectives:To evaluate the ADAM 10 and ADAM17 levels in AIS patients and to clarify the mechanism of abnormal soluble leptin receptor level in AIS.Materials and Methods:OB-Ra,OB-Rb,AD AM10 and AD AM17 mRNA levels in white cells together with serum leptin,sOB-R,ADAM 10,and ADAM 17 concentrations were measured in 30 AIS girls and 30 age-matched healthy girls.AD AM10 and AD AM17 mRNA levels were measured by real-time PCR and serum sOB-R,AD AM10,and ADAM17 concentrations were measured by ELISA.Results:AIS girls had significantly lower leptin level and higher sOB-R level than healthy controls(7.3 ± 4.8 ng/ml vs,8.7 ± 4.2 ng/ml,P = 0.044;26.8 ± 6.9 ng/ml vs.22.5 ± 6.1 ng/ml,P = 0.012;respectively).The mRNA level and serum concentration of AD AM10 in AIS patients were significantly higher than in controls(P<0.05).The mRNA level and serum concentration of ADAM 17 was not significantly different between AIS patients and controls.Conclusion:The ADAM10 level and serum sOB-R concentration in AIS patients were significantly higher than in controls,indicating that elevated ADAM10 expression may be responsible for the high sOB-R level in AIS.Chapter 2 Clinical studies about spinal deformitiesSection 1 Predictors of ultimate postoperative cervical sagittal alignment in main thoracic adolescent idiopathic scoliosis:a long-term follow-up studObjectives:To access sagittal compensatory mechanism of the cervical spine in thoracic adolescent idiopathic scoliosis(T-AIS)before and after posterior spinal fusion and to identify preoperative or immediate postoperative radiographic parameters that can predict the ultimate cervical sagittal alignment(CSA)after long-term follow-up.Materials and Methods:A retrospective study was performed on 44 T-AIS patients treated with posterior spinal fusion and with at least 5 years of follow-up.Preoperative,immediate postoperative and latest follow-up radiographs were reviewed measuring main thoracic curve(MTC),main thoracic curve(MTC),cervical lordosis(CL),cervical sagittal vertical axis(CSVA),upper thoracic kyphosis(UTK),main thoracic kyphosis(MTK),global thoracic kyphosis(GTK),lumbar lordosis(LL),pelvic incidence(PI),pelvic tilt(PT),and sacral slope(SS).Pearson correlation analysis,stepwise multilinear regression analysis,and ROC curve were performed to define the relationship between ultimate CL and preoperative or immediate postoperative radiographic parameters.Results:CL significantly improved from 6.6°t8.8° kyphosis preoperatively to 3.8°±8.7°kyphosis immediate postoperatively and to 0.5°±7.3° lordosis at the latest follow-up.Pre-and postoperative CSVA showed no significant difference.Pearson correlation coefficient test showed that CL was only correlated to T1 slope and UTK before surgery,while it was correlated to T1 slope,UTK,and GTK after surgery.The following equation was developed to estimate the ultimate CL:ultimate CL =-2.80 + 0.51× Preop CL + 0.53 × Postop T1 slope.Furthermore,ROC curve showed that preoperative CL ?-4.5° was strongly predictive and postoperative T1 slope ? 11.3° was moderately predictive of lordotic cervical spine after long-term follow-up.Conclusion:For Lenke type 1 AIS patients,cervical lordosis significantly increased after surgery with the restoration of the global and regional sagittal profile.The sagittal compensatory mechanism of the cervical spine before surgery is different from that after surgery.In these patients,preoperative CL and immediate postoperative T1 slope,could be predictors of the ultimate CSA after long-term follow-up.Section 2 Spinal epidural lipomatosis-an easily ignored secondary intraspinal disorder in spinal kyphotic deformitiesBackground:A previous study reported a high prevalence of spinal epidural lipomatosis(SEL)in patients with Scheuermann kyphosis(SK)and suggested that it may play a role in the pathogenesis of this disease.According to our observation,however,SEL occurs in other spinal kyphotic deformities as well.The aim of this study was to test the hypothesis that SEL commonly occurs in patients with different types of kyphotic deformities as a secondary intraspinal disorder.Materials and Methods:MR images of 16 patients with congenital kyphosis(CK),40 patients with SK,13 patients with tuberculotic kyphosis(TK),and 69 age-and sex-matched controls were retrospectively evaluated.The body mass index(BMI),kyphosis Cobb angle,and sagittal diameters of spinal epidural fat(EF)and the dural sac(DS)in the apical region(EFA,DSA)and non-kyphotic region(EFN,DSN)were measured.The EF ratios at the apical vertebral level(EFRA)and in the non-kyphotic region(EFRN)were calculated as EF/(EF + DS).Results:EFA and EFRA were significantly higher among patients with CK,SK,and TK than among controls(P<0.05).Seven CK patients(43.8%),8 SK patients(20.0%),and 11 TK patients(84.6%)fulfilled the diagnostic criteria for SEL,while only 6.3%,2.5%,and 0%of patients in the control groups did(P = 0.019,0.014,and<0.001,respectively).Spearman's correlation analysis showed statistically significant correlations between the kyphosis Cobb angle and the amount of EF in all three patient groups.Conclusions:SEL is a common secondary intraspinal disorder in different types of kyphotic deformities,and surgeons should pay increased attention to this intraspinal anomaly because excessive EF may compress the spinal cord and cause neurological deficits.Section 3 Remodeling of the cervical spinal canal in patients with Chiari malformation type I after posterior fossa decompressionObjective:Previous research reported milder taper ratios of cervical spinal canals in patients with Chiari malformation type I(CMI)with distended syringes compared to those with nondistended syringes,indicating a reciprocal interaction between the cervical spine anatomy and the syrinx.This study aimed to determine whether the cervical spinal canal remodels in patients with CMI after posterior fossa decompression(PFD).Materials and methods:Thirty-nine patients with CMI-associated syringomyelia were divided into two groups:30 with an improved syrinx after PFD and 9 with unimproved syrinx after PFD.On a midline T2-weighted MR image,the anteroposterior diameters of the spinal canal were measured at C2-7 cervical levels,and a trend line was fitted by least squares regression.The slope of this line was recorded as the taper ratio.The diameters and the taper ratios were compared between the pre-and post-operative settings and between the two groups.Results:In the syrinx-improved group(group SI),the average diameter of the spinal canal at C2,C3,C4,and C7 levels significantly decreased after surgery(P = 0.001,0.011,0.028,and 0.045 respectively).Meanwhile,the taper ratios for C2-4 became milder from-1.38 ± 0.78 to-1.13 ± 0.95(P = 0.024).In contrast,neither the diameters nor the taper ratios changed significantly after PFD in the syrinx-unimproved group(group SU).Conclusions:The cervical spinal canal becomes narrower in CMI patients with an improved syrinx after PFD,indicating a remodeling of the cervical spinal canal.Furthermore,this remodeling process induces milder taper ratios of the cervical spinal canal.