Effects of Weight Reduction on Serum Vaspin Concentrations in Obese Subjects: Modification by Insulin Resistance

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1 nture publishing group rticles Effects of Weight Reduction on Serum Vspin Concentrtions in Obese Subjects: Modifiction by Insulin Resistnce Hye M. Chng 1, He J. Lee 1, Hye S. Prk 1, Je H. Kng 2, Kyung S. Kim 3, Young S. Song 4 nd Yeon J. Jng 4 Viscerl dipose tissue-derived serpin (vspin) hs been regrded s novel dipokine with potentil insulin sensitizing properties. We investigted the chnges of serum vspin concentrtion in response to weight reduction, nd the ssocitions between chnges in serum vspin concentrtions nd chnges of nthropometric nd metbolic vribles in obese subjects fter weight reduction. We performed longitudinl clinicl intervention study on 63 obese persons enrolled in 12-week weight reduction progrm tht included lifestyle modifiction nd djuvnt tretment with the ntiobesity gent orlistt. Anthropometric vribles, lipid profiles, fsting glucose, fsting insulin, nd serum vspin concentrtions were mesured. Sttisticl nlyses were performed ccording to the homeostsis model ssessment of insulin resistnce ( ). Serum vspin concentrtions decresed significntly in responders ( 2% reduction in bseline weight), but not in nonresponders (<2% reduction in bseline weight). Chnges in serum vspin concentrtions were significntly correlted with body weight, BMI, wist circumference, nd hip circumference in the higher, but not in the lower, group. In multivrite liner regression nlysis, chnge in serum vspin concentrtions in the higher, but not in the lower, group ws positively correlted with chnge in BMI nd negtively correlted with initil level. The ssocitions between chnges in serum vspin concentrtions nd chnges in nthropometric nd metbolic prmeters differed ccording to insulin resistnce sttus in obese subjects. These reltionships were more prominent in the higher group. Insulin resistnce my influence the correltions between chnges in serum vspin concentrtion nd relted metbolic vribles. Obesity (2010) 18, doi: /oby Introduction Excess diposity is frequently ssocited with insulin resistnce, type 2 dibetes, dyslipidemi, nd hypertension (1,2). In ddition to storing excess energy, dipose tissue secretes severl bioctive peptides tht exert prcrine nd endocrine effects nd ply n importnt role in metbolic regultion (3,4). Thus, dysregultion of dipokine secretion my link obesity to its relted metbolic disorders (5,6). Viscerl dipose tissue-derived serpin (vspin) is novel dipokine originlly isolted from the viscerl dipose tissue of Otsuk Long-Evns Tokushim Ftty rts (7,8), n niml model of type 2 dibetes (9). In these rts, vspin ws highly expressed t the ge when obesity nd insulin resistnce peked (7). Recombinnt humn vspin dministered to obese, insulin-resistnt mice improved glucose tolernce nd insulin sensitivity (7), s well s reversing the ltered expression of genes relevnt to insulin resistnce in white dipose tissue. Thus, vspin my ntgonize the ction of s yet unknown proteses, derived from ft or other tissues, tht impir insulin ction (7). Vspin is lso expressed in humn dipose tissues nd its expression hs been shown to be higher in obese thn in nonobese subjects (10). Circulting vspin concentrtions hve been reported to be sex-dependent nd to be relted to BMI nd prmeters of insulin sensitivity nd glucose metbolism in humns (11). Elevted serum concentrtions of vspin re ssocited with obesity nd impired insulin sensitivity, wheres physicl trining in untrined individuls prdoxiclly cuses incresed serum vspin concentrtions with weight loss (11). Metformin tretment decreses serum vspin 1 Deprtment of Fmily Medicine, University of Ulsn College of Medicine, Seoul, Kore; 2 Deprtment of Fmily Medicine, College of Medicine, Inje University, Seoul, Kore; 3 Deprtment of Fmily Medicine, College of Medicine, Ctholic University, Seoul, Kore; 4 Deprtment of Physiology, University of Ulsn College of Medicine, Seoul, Kore. Correspondence: Hye S. Prk (hyesoon@mc.seoul.kr) or Yeon J. Jng (yjjng@mc.seoul.kr) Received 21 December 2009; ccepted 23 Februry 2010; published online 25 Mrch doi: /oby obesity VOLUME 18 NUMBER 11 November

2 levels in overweight women with polycystic ovry syndrome concomitnt with improvement in insulin sensitivity (12). However, the chnges of serum vspin concentrtions ccording to weight chnge in obese subjects re still uncler. Therefore, we investigted the chnges of serum vspin concentrtion in response to weight reduction s well s the ssocitions between chnges in serum vspin concentrtions nd nthropometric nd metbolic prmeters, specificlly, strtified by insulin resistnce in obese subjects before nd fter weight reduction. Methods nd Procedures Study subjects We recruited obese subjects (BMI 30 kg/m 2 ; or BMI 27 kg/m 2 with comorbid hypertension or dyslipidemi), ged yers, who visited the obesity clinics t three hospitls in Seoul, Kore, between Jnury nd October All individuls were mediclly evluted by physicins who took full medicl histories nd conducted physicl exmintions. We excluded pregnnt or lctting women, subjects with secondry cuses of obesity, subjects with severe heptic or renl diseses, nd subjects tking medictions tht might ffect body weight or glucose metbolism. A totl of 63 subjects (25 men nd 38 women) were enrolled nd completed 12-week weight reduction progrm. All subjects underwent nthropometric mesurements nd blood smpling for biochemicl mesurements before nd fter the 12-week weight reduction progrm. The study design ws pproved by the institutionl review bord of Asn Medicl Center nd written informed consent ws obtined from ll prticipnts. Weight reduction progrm The 12-week weight reduction progrm consisted of individul intervention sessions designed to implement behviorl strtegies relted to eting nd physicl ctivity, with the gol of chieving nd mintining weight loss. Prticipnts were instructed to reduce their dily energy intke by 500 kcl. Throughout the progrm, prticipnts were expected to engge in regulr exercise (erobics, min/dy, 4 5 dys/week) nd to visit the clinic every month for consulttions with registered dietitin nd physicin. All prticipnts were lso dministered 120-mg orlistt three times dily. Anthropometric mesurements Anthropometric mesurements were tken with subjects in light clothing nd without shoes. Height nd weight were mesured by n utomtic height weight scle, to the nerest 0.1 cm nd 0.1 kg, respectively. BMI ws clculted by dividing weight (kg) by the squre of the height (m 2 ). Wist circumference ws mesured t the midpoint between the lower border of the rib cge nd the ilic crest nd hip circumference ws mesured t the widest prt of the hip region. Mesurements of metbolic vribles nd serum vspin concentrtions Blood smples were obtined in the morning fter 12-h overnight fst, nd serum nd plsm were immeditely seprted by centrifugtion. Totl cholesterol nd triglyceride levels were mesured by enzymtic procedures using n utonlyzer (Hitchi-747; Hitchi, Tokyo, Jpn). The high-density lipoprotein-cholesterol frction ws mesured enzymticlly fter precipittion of po-b contining lipoproteins with MnCl 2. Low-density lipoprotein-cholesterol ws clculted using the Friedewld eqution if the triglyceride concentrtion ws <400 mg/dl. Glucose ws mesured by the glucose oxidse method, hemoglobin A 1c by immunoturbidimetry (Roche, Bsel, Switzerlnd), nd insulin by rdioimmunossy (Dinbott, Tokyo, Jpn). Insulin resistnce ws determined by clculting the homeostsis model ssessment of insulin resistnce ( ) score, using the formul: fsting serum insulin (μu/ml) fsting plsm glucose (mg/dl)/405 (13). Serum vspin concentrtions were mesured using commercil ELISA kit (AdipoGen, Seoul, Kore) ccording to the mnufcturer s instructions. The ssy sensitivity ws 12 pg/ml, nd the intr- nd interssy coefficients of vrince were nd %, respectively. Sttisticl nlysis Dt re presented s men ± s.e. Prior to sttisticl nlysis, nonnormlly distributed prmeters were logrithmiclly trnsformed to pproximte norml distribution. Pired Student s t-tests were used to compre vribles before nd fter weight reduction. To compre chnges of vribles ccording to weight reduction, prticipnts were divided into two groups: responders, defined s those who lost 2% of bseline weight t the end of the 12-week intervention progrm, nd nonresponders. Unpired two-tiled Student s t-tests were used to compre the chnges in vribles between the responder nd nonresponder groups. Subjects ws lso divided into those with higher (n = 32) nd lower (n = 31) scores. We defined the higher group s subjects with initil vlues over the 50th percentile (vlue = 2.80). Correltions nlyses were performed using Spermn s method, strtified by, to exmine the simple reltionships between serum vspin concentrtion nd selected vribles. To djust for covrite effects nd to identify independent reltionships, multivrite liner regression nlyses were performed. P vlues <0.05 were considered sttisticlly significnt in ll tests. All sttisticl nlyses were performed using SPSS 12.0 for Windows (SPSS, Chicgo, IL). Results Anthropometric nd metbolic prmeters in study subjects before nd fter the weight reduction progrm Tble 1 shows nthropometric nd metbolic pr meters in the 63 subjects before nd fter tretment. After completion of the progrm, body weight, BMI, wist nd Tble 1 Anthropometric nd metbolic prmeters in 63 subjects before nd fter the 12-week weight reduction progrm Before Men ± s.e. Men/women 25/38 Age (yers) 38.2 ± 1.3 After Men ± s.e. P vlue Body weight (kg) 86.7 ± ± 1.4 <0.01 BMI (kg/m 2 ) 31.9 ± ± 0.3 <0.01 Wist circumference (cm) 99.1 ± ± 1.0 <0.01 Hip circumference (cm) ± ± 0.8 <0.01 Totl cholesterol (mg/dl) ± ± Triglycerides (mg/dl) ± ± HDL-cholesterol (mg/dl) 52.4 ± ± 1.3 <0.01 LDL-cholesterol (mg/dl) ± ± Fsting glucose (mg/dl) 99.4 ± ± (%) 5.6 ± ± Fsting insulin (μu/ml) 12.4 ± ± ± ± Vspin (pg/ml) 616 ± ± BMI clculted by dividing weight (kg) by height squred (m 2 )., hemoglobin A 1c ; HDL, high-density lipoprotein;, homeostsis model ssessment of insulin resistnce; LDL, low-density lipoprotein. P vlue clculted by pired t-test compring to bseline VOLUME 18 NUMBER 11 November

3 hip circumferences, totl cholesterol, nd high-density lipoprotein-cholesterol were significntly reduced compred with bseline mesurements. Men fsting plsm insulin,, nd serum vspin concentrtions decresed, but the differences were not sttisticlly significnt. There ws little difference in triglyceride, low-density lipoproteincholesterol, fsting glucose, nd hemoglobin A 1c before nd fter weight reduction. Chnges of nthropometric nd metbolic prmeters in responders nd nonresponders fter weight reduction progrm We found tht the weight reduction progrm ws not effective in ll prticipnts. Thus, to compre chnges in vribles ccording to weight reduction, we divided the subjects into responders, defined s prticipnts who lost 2% of bseline weight, nd nonresponders, defined s prticipnts who lost <2% of bseline weight (Tble 2). Body weight, BMI, wist nd hip circumferences, totl cholesterol, nd high-density lipoprotein-cholesterol were decresed significntly in responders. In ddition, fsting glucose, fsting insulin, nd decresed significntly in responders. However, in nonresponder group, few of the nthropometric nd metbolic prmeters showed ny significnt chnges except highdensity lipoprotein-cholesterol. Serum vspin concentrtions decresed significntly in responders ( 12.8 ± 7.4%, P = 0.04), but incresed in nonresponders (33.0 ± 21.0%, P = 0.69). The differences in the chnges of triglyceride, fsting glucose,, nd serum vspin concentrtions in the responders nd nonresponders were significnt. Correltions between chnges in serum vspin concentrtions nd nthropometric nd metbolic prmeters fter the weight reduction progrm in the higher nd lower groups We exmined the correltion between chnges in serum vspin concentrtions nd chnges in other prmeters fter the intervention strtified by (Tble 3). In the higher group, the chnges in serum vspin concentrtion correlted positively with chnges in body weight (r = 0.477, P < 0.01), BMI (r = 0.456, P < 0.01), wist circumference (r = 0.525, P < 0.01), nd hip circumference (r = 0.376, P = 0.03). However, in the lower group, chnges in serum vspin concentrtion were not significntly correlted with chnges in other prmeters. Independent predictors for chnges of serum vspin concentrtions fter the weight reduction progrm ccording to Results of multiple liner regression nlyses for chnges in serum vspin concentrtion s dependent vrible nd ge, sex, initil BMI, chnges in BMI, initil, nd chnges in s independent vribles re shown in Tble 4. In the higher group, chnges in serum vspin concentrtions correlted positively with the chnges in BMI nd inversely with initil fter djusting for confounding vribles. However, in the lower group, no significnt reltionships were observed. Discussion We hve shown here tht, in obese subjects, serum vspin concentrtions decresed significntly following modest weight Tble 2 Chnges in nthropometric nd metbolic prmeters in responders nd nonresponders fter weight reduction progrm Responders (n = 38) Nonresponders (n = 25) Men ± s.e. P vlue Men ± s.e. P vlue Men/women 18/20 7/18 P vlue b ΔBody weight (kg) 4.1 ± 0.3 < ± <0.01 ΔBMI (kg/m 2 ) 1.5 ± 0.1 < ± <0.01 ΔWist circumference (cm) 4.4 ± 0.4 < ± <0.01 ΔHip circumference (cm) 2.7 ± 0.3 < ± <0.01 ΔTotl cholesterol (mg/dl) 10.0 ± ± ΔTriglyceride (mg/dl) 16.1 ± ± ΔHDL-cholesterol (mg/dl) 3.3 ± ± 1.3 < ΔLDL-cholesterol (mg/dl) 6.5 ± ± ΔFsting glucose (mg/dl) 4.5 ± ± Δ (%) 0.01 ± ± ΔFsting insulin (μiu/ml) 2.3 ± 0.7 < ± Δ 0.7 ± 0.2 < ± ΔVspin (%) 12.8 ± ± BMI clculted by dividing weight (kg) by height squred (m 2 ). ΔVspin (%) = (vspin level fter the intervention bseline vspin level)/bseline vspin level 100. Responders re who lost their weight over 2% of bseline weight fter intervention progrm. Responders (n = 38) include 18 men nd 20 women; nonresponders (n = 20) include 7 men nd 18 women., hemoglobin A 1c ; HDL, high-density lipoprotein;, homeostsis model ssessment of insulin resistnce; LDL, low-density lipoprotein. P vlue clculted by pired t-test compring to bseline. b P vlue clculted by Student s t-test between responders nd nonresponders. obesity VOLUME 18 NUMBER 11 November

4 Tble 3 Spermn correltion coefficients between chnge in serum vspin concentrtion nd chnges in nthropometric nd metbolic prmeters fter weight reduction ccording to Vribles Higher (n = 32) Lower (n = 31) r P vlue r P vlue Men/women 16/16 9/22 ΔBody weight (kg) < ΔBMI (kg/m 2 ) < ΔWist circumference (cm) < ΔHip circumference (cm) ΔTotl cholesterol (mg/dl) ΔTriglyceride (mg/dl) ΔHDL-cholesterol (mg/dl) ΔLDL-cholesterol (mg/dl) ΔFsting glucose (mg/dl) Δ (%) ΔFsting insulin (μiu/ml) Δ BMI clculted by dividing weight (kg) by height squred (m 2 ). Lower group nd higher group were divided using cutoff of 50th percentile of vlue in our subjects. Dt were log trnsformed to chieve norml distribution., hemoglobin A 1c ; HDL, high-density lipoprotein;, homeostsis model ssessment of insulin resistnce; LDL, low-density lipoprotein. P vlue clculted by Spermn s correltion coefficients. loss nd tht this ws ccompnied by improvements in prmeters relevnt to insulin resistnce. Furthermore, reltionships between chnges in serum vspin nd chnges in nthropometric prmeters during the weight reduction progrm were modified by insulin resistnce. Tht is, we observed strong significnt correltions in the higher, but not in the lower, group. Those findings support previous our results tht serum vspin concentrtion ws indepen dently correlted with viscerl dipose tissue re in the higher group, but not in the lower group (14). Circulting levels of vspin, s well s its expression in dipose tissues, hve been reported to be elevted in obese nimls (7) nd humns (10,11,15). In obese men nd women who responded to the weight reduction progrm, we observed significnt decreses in serum vspin level concomitnt with meliortions of insulin resistnce. This observtion is consistent with the hypothesis tht incresed vspin my be compenstory response to ntgonize the ction of unknown proteses tht re upregulted in sttes of insulin resistnce (7). Alterntively, vspin concentrtion my simply be surrogte prmeter of obesity, becuse vspin is minly produced by dipose tissues nd no mrna trnscript hs yet been observed in nondipose tissues of humn nd mouse orgns (7). In previous intervention study, 4 weeks of n intensive physicl trining progrm led to increses in serum vspin concentrtions concomitnt with decresed BMI nd improved insulin sensitivity (11). Conversely, competitive sportsmen Tble 4 Multivrite liner regression nlysis for chnge in serum vspin concentrtions s dependent vrible nd nthropometric nd metbolic prmeters s independent vribles fter the weight reduction progrm ccording to Stndrdized β-coefficient P vlue Higher group Age (yers) Sex Initil BMI (kg/m 2 ) ΔBMI (kg/m 2 ) Initil Δ (Adjusted R 2 = 0.231) Lower group Age (yers) Sex Initil BMI (kg/m 2 ) ΔBMI (kg/m 2 ) Initil Δ (Adjusted R 2 = 0.224) BMI clculted by dividing weight (kg) by height squred (m 2 ). Lower group nd higher group were divided using cutoff of 50th percentile of vlue in our subjects. Dt were log trnsformed to chieve norml distribution., homeostsis model ssessment of insulin resistnce. P vlue clculted by multiple liner regression nlysis. with long-term physicl trining hd significntly lower vspin serum concentrtions thn untrined ge- nd BMI-mtched control subjects. This prdox ws explined tht serum concentrtion of vspin ws differentilly regulted in the resting stte nd fter exercise (11). Elevted vspin concentrtions fter the intensive physicl trining my represent trnsient dpttion mechnism nd tht vspin my contribute to the insulin-sensitizing effects of physicl ctivity (11). In our study, weight reduction led to decrese in serum vspin concentrtions with decresed BMI nd improved insulin sensitivity. Tht discrepncy might be due to the differences of durtion (short-term vs. long-term) or mode (exercise dominnt vs. lifestyle modifiction) of weight reduction s well s exercise intensity (submximl vs. moderte). Our study shows tht significnt decreses in serum vspin level were concomitnt with reductions in wist circumference in responder group. Wist circumference is useful index of centrl obesity (16) nd modest weight loss hs been ssocited with the preferentil loss of viscerl rther thn subcutneous ft (17,18). Hence, the decresed wist circumference observed in our responders my reflect the reduction in the ccumultion of bdominl, prticulrly viscerl ft. Thus, decresed vspin concentrtions in the responder group my be ssocited with the reduction of viscerl ft during the weight reduction progrm VOLUME 18 NUMBER 11 November

5 Interestingly, strong correltions between chnges in serum vspin concentrtions nd chnges in body weight, BMI, wist circumferences, nd hip circumferences during the intervention were observed only in insulin resistnt subjects. Previously, we observed tht the reltionship between serum vspin concentrtion nd viscerl ft ccumultion ws modified by the presence of insulin resistnce (14). In ddition, multivrite regression nlysis reveled tht, in the presence of insulin resistnce, chnges in serum vspin levels correlted positively with chnges in BMI nd negtively with initil fter djusting for confounding vribles. Modifiction of the ssocition with insulin resistnce my be ccounted for by the ft depot-specific regultion of vspin production (10), together with the preferentil loss of viscerl ft, the ccumultion of which is primry risk fctor for insulin resistnce. A recent report, demonstrting significnt ssocition between vspin single-nucleotide polymorphisms nd type 2 dibetes (19), supports the potentil insulin-sensitizing properties of vspin. Moreover, secretomes of primry cultures of humn dipose-derived stem cells showed tht dipocyte differentition modultes the levels of expression of the serpin fmily of protese inhibitors (20), indicting tht these molecules ply significnt role in obesity nd its relted metbolic ltertions. Previous studies reported sexul dimorphism in serum vspin concentrtions with higher levels in norml glucosetolernt women compred with men (11,21), however, these sex differences were not observed in type 2 dibetic ptients (11). Sexul dimorphism in serum vspin levels could be influenced by glucose tolernce or insulin sensitivity (11). In our study, initil serum vspin levels were not significnt different between women nd men ( ± vs ± pg/ml, P = 0.274) (dt not shown). Furthermore, the chnge of serum vspin concentrtions fter weight reduction between women nd men were not different regrdless of the degree of weight loss or insulin resistnce stte. Since our study subjects were obese, we could not exclude the possibility tht our subjects might hve bnorml glucose metbolism or insulin resistnce nd those conditions led to the bsence of sexul dimorphism in our study. The present study hs severl limittions. First, we defined insulin resistnce by the HOMA method, insted of the glucose clmp method, the stndrd method used to define insulin resistnce. However, estimtes by the homeostsis model correlte firly well with those by the euglycemic hyperinsulinemic clmp (r = 0.83, P < 0.01) nd hve cceptble degree of reproducibility (22). We lso defined insulin resistnce using n rbitrry criterion. Although cut-off vlues of my differ mong study subjects nd ethnic groups, the index hs been widely used s surrogte mrker for insulin sensitivity fter therpeutic lifestyle chnges (23). Second, we could not mesure bdominl ft distribution. If we hd ssessed viscerl nd subcutneous dipose tissue in the study subjects before nd fter the weight reduction progrm, we would hve been ble to nlyze the decrese in serum vspin concentrtions reltive to the reduction in viscerl dipose tissues. Since wist circumference hs been highly ssocited with viscerl ft ccumultion, we utilized wist circumference s simple proxy nthropometric indictor of bdominl obesity (24,25). The chnge in wist circumference might reflect chnge in viscerl ft ccumultion. Third, we could not nlyze chnges in serum vspin concentrtions ccording to the therpeutic modlity of weight reduction, becuse we educted ll subjects bout lifestyle modifiction nd prescribed lipid bsorption inhibitor (orlistt). Orlistt potently inhibits gstric nd pncretic lipses, thus limiting the hydrolysis nd systemic bsorption of ingested ft, nd my therefore led to chnges in cholesterol nd/or low-density lipoprotein-cholesterol concentrtion (26). However, the previous study reported tht no differences in dipokine concentrtions hve been observed between individuls on hypocloric diet, with or without orlistt tretment (27). In conclusion, we found tht modest weight loss in obese subjects resulted in significnt decrese in serum vspin concentrtions concomitnt with the meliortion of insulin resistnce. The ssocitions between chnges in serum vspin concentrtions nd chnges in nthropometric nd metbolic prmeters differed ccording to insulin resistnce sttus in obese subjects. Insulin resistnce my influence the correltions between chnges in serum vspin concentrtion nd relted metbolic vribles. Acknowledgments We thnk Hyun Moon for contribution to dt nlysis. 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