Effects Of Thyrotropin On Expression Levels Of Complement-C1q/tumor Necrosis Factor-related Proteins In Adipose Tissues

Introduction: Metabolic syndrome(Met S)is a cluster of metabolic diseases,including central obesity,hypertension,dyslipidemia and abnormal glucose metabolism.Adiposity-induced insulin resistance is the core of the occurrence and development of Met S.Previous studies have confirmed that adipose tissue could play vital role in glucose and lipid metabolism by secreting a variety of bioactive peptides such as leptin,TNFalpha and so on.The Complement-C1q/tumor necrosis factor-related proteins(CTRPs)family is a newly discovered class of adipocykines.Various studies have reported an association of CTRPs with obesity or type 2 diabetes,but some other results are not consistent.Therefore,this prospective study was performed to investigate the correlation between the baseline serum CTRPs levels and the incident risk of Met S and its components.Methods: In 2010,a total of 763 residents,between 40 and 65 years old,accepted a full health examination.The Met S was diagnosed according to the International Diabetes Association criterion in 2009,and those without Met S were followed up.In the end,210 participants were included in the follow-up cohort.After 5.5 years,the cohort was divided into the newly-Met S group and the non-Met S group according to whether they suffered from Met S or not.The baseline serum levels of CTRP1,CTRP3 and CTRP9 were compared between the newly-Met S group and the non-Met S.Moreover,receiver operating characteristic curves(ROC)were drawn,and the area under curves(AUC)were calculated.Results: Compared with non-Met S group,baseline serum CTRP1 levels were decreased in newly-Met S(145.22±28.70 vs 162.68±52.53,P=0.002),while CTRP3 and CTRP9 levels were increased significantly(145.22 + 28.70 vs 162.68 + 52.53,P=0.002).After multivariate adjustment,Logistics regression analysis showed that CTRP3 and CTRP9 were positively correlated with incident risk of Met S [CTRP3,1.80(1.37-2.38),P<0.001;CTRP9,1.08(1.04-1.12),P<0.001].ROC analysis indicated that the AUCs for CTRP1,CTRP3,and CTRP9 were 0.61±0.04(P=0.010),0.70±0.04(P<0.001),and 0.74±0.04(P<0.001),respectively.Compared with waist circumference,AUC of CTRP1 wasdecreased significantly,while CTRP3 and CTRP9 have shown no significant difference between their AUCs and waist circumference,suggesting that the predictive ability of CTRP3 and CTRP9 for Met S is similar to that of waist circumference.ConclusionFirst,subjects with newly-MetS have decreased serum levels of CTRP1 and increased levels of CTRP3 and CTRP9 at baseline.Secondly,CTRP1,CTRP3 and CTRP9 can predict the risk of Met S,but the predictive ability of CTRP1 is lower than that of classical indicators(waist circumference),while CTRP3 and CTRP9 have no significant difference from waist circumference.Therefore,CTRP3 and CTRP9 can be considered as a better biomarker in predicting Met S.Introduction: Thyroid disease is a common endocrine disease,and the total prevalence is 3%-13.5%.Various studies have observed that the overt and subclinical hypothyroidism,or even elevated thyroid-stimulating hormone(TSH)within normal range,could be correlated with the occurrence of metabolic diseases.Previous studies suggested that TSH can directly bind with TSH receptor on adipocyte and change the levels of adipokines such as leptin,adiponectin,fibroblast growth factor and so on,inducing the occurrence and development of insulin resistance and metabolic diseases.Complement-C1q/tumor necrosis factor related proteins(CTRPs)family is a group of adipokines with highly conserved structure,including 15 members.This superfamily has a highly similar structure to adiponectin,so it is considered to be involved in many physiological and pathological processes such as energy metabolism,immune response and so on.However,whether CTRPs is involved in TSH-mediated metabolic abnormalities remained unclear.Therefore,the aim of this study is to investigate serum CTRP1,CTRP3 and CTRP9 levels in patients with overt and subclinical hypothyroidism by a case-control study,exploring the possible mechanisms of TSH-mediated metabolic diseases.Methods: From June 2015 to December 2016,a total of 240 subject was enrolled from the Department of Endocrinology and Metabolism of the First Affiliated Hospital of China Medical University,and received a comprehensive physical examination.Finally,100 age,gender and BMI matched subjects were selected according to their thyroid function,including overt hypothyroidism group(OH),subclinical hypothyroidism group(SCH),Isolated TPOAb positivity group(Isolated TPOAb)and healthy controls(HC).The serum levels of CTRP1,CTRP3,and CTRP9 were determined by ELISA method.Results: Compared with the HC,the fasting insulin,homeostasis model assessment of insulin resistance,and triglyceride in the OH group were significantly increased.The serum levels of CTRPs were further compared.Firstly,there was no significant difference in CTRP1 levels between groups.Moreover,serum CTRP3 and CTRP9 levels were significantly increased in OH and SCH compared with HC,while no significantdifference was observed between HC and Isolated TPOAb.Furthermore,serum CTRP3 levels of OH was higher than SCH [1064.62(1022.86-1137.72)ng/m L vs 974.43(913.79-1016.42)ng/m L,P<0.001],while no significant difference was observed in serum levels of CTRP9 [346.62(280.73-430.23)ng/m L vs 306.13(251.69-378.08)ng/m L,P=0.138].After multivariate adjustment,the positive associations of TSH with CTRP3 and CTRP9 were remained,and FT4 showed a negative correlation with CTRP9.However,no significant association of CTRP1 with TSH,FT3,or FT4 was observed.Conclusion: The serum levels of CTRP3 and CTRP9 in patients with overt and/or subclinical hypothyroidism were significantly increased compared with their healthy control,but there were no significant changes in CTRP1.After multivariate adjustment,the serum TSH levels was still positively associated with CTRP3 and CTRP9,suggesting that TSH could be the predictor of increased serum levels of CTRP3 and CTRP9.Introduction: Subclinical hypothyroidism(SCH)is defined as a subclinical state with increased thyroid stimulating hormone(TSH)and normal thyroxine.It is one of the most common endocrine diseases.Previous studies have indicated that SCH is closely related to the occurrence and development of metabolic diseases such as obesity,dyslipidemia and type 2 diabetes.However,the molecular mechanism of TSH-mediated insulin resistance remained unclear.Adipose tissue plays an important role in maintaining energy homeostasis and regulating glycolipid metabolism.On the other hand,TSH receptors(TSHR)were expressed in adipocytes.Hence,elevated TSH could act directly on adipocytes,and induced expressions of various adipokines,resulting in insulin resistance of adipose tissue.In this study,we determined the changes in expression levels of CTRP1,CTRP3,and CTRP9 in adipose tissue and adipocytes under elevated TSH status by experiments in vivo and in vitro.Methods: Forty Wistar rats were randomly divided into four groups(10 for every goup):(1)Overt hypothyroidism group(OH): total thyroidectomy was performed and 0.9% sodium chloride solution was injected subcutaneously.(2)Subclinical hypothyroidism group(SCH): total thyroidectomy was performed and levothyroxine solution was injected subcutaneously.(3)High fat diet-feeding group(HF): pseudothyroidectomy was performed,0.9% sodium chloride solution was injected subcutaneously,and a high-fat diet was given.(4)Control group(CG): pseudothyroidectomy was performed and 0.9% sodium chloride solution was injected subcutaneously.The subcutaneous and visceral adipose tissue around epididymis was retained.Serum levels of CTRP1,CTRP3,and CTRP9 were determined by ELISA method,and m RNA expression of CTRP1,CTRP3,and CTRP9 were determined by Realtime q PCR.3T3-L1 cells were differentiated into mature adipocytes using the classical method,and were stimulated by exogenous TSH in different stimulation concentration and time.The stimulated concentrations were 0m IU/m L,0.01 m IU/m L,0.1m IU/m L,and 10 m IU/m L.The stimulation time were 0h,2h,6h,12 h,and 24 h.Levels of CTRP1,CTRP3,andCTRP9 in the supernatant were determined by ELISA,and the m RNA expression of CTRP1 CTRP3 and CTRP9 were determined by Realtime q PCR.Result: OH and SCH showed significant increased insulin resistance.Compared with CG,the levels of CTRP3 and CTRP9 m RNA were increased significantly in OH and SCH epididymal fat,while no significant difference in expression level of CTRP1 m RNA was observed between them.Levels of CTRP1 m RNA in subcutaneous were increased in OH and SCH,compared with CG.After treatment with different TSH concentrations and time,CTRP1 mRNA in 3T3-L1 adipocytes showed no significant change.Compared with the blank control,level of CTRP3 m RNA was up-regulated with TSH concentration increased significantly,and the peak was reached at the time of stimulation of 6h.In the medium,the concentration of CTRP3 was up-regulated with the increase of TSH concentration,and up-regulated with the increase of stimulation time.The process tends to be stable after 6h.These results suggested that TSH stimulates the secretion of CTRP3 in a dose-time dependent manner.Compared with the blank control,levels of CTRP9 m RNA was up-regulated with TSH concentration increased significantly,and the peak was reached at the time of stimulation of 6h.In the medium,the concentration of CTRP9 was up-regulated with the increase of TSH concentration,and up-regulated with the increase of stimulation time.The process tends to be stable after 12 h.These results suggested that TSH stimulates the secretion of CTRP9 in a dose-time dependent manner.Conclusion: TSH induced the expression of CTRP3 and CTRP9 in adipocytes in a dose-time dependent manner,suggesting that elevated TSH could participate in the regulation of glycose and lipid metabolism through mediating the change of CTRPs profile in adipose tissue.