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Visfatin is regulated by rosiglitazone in type 2 diabetes mellitus and influenced by NFκB and JNK in human abdominal subcutaneous adipocytes.

McGee KC, Harte AL, da Silva NF, Al-Daghri N, Creely SJ, Kusminski CM, Tripathi G, Levick PL, Khanolkar M, Evans M, Chittari MV, Patel V, Kumar S, McTernan PG - PLoS ONE (2011)

Bottom Line: Firstly, we examined the effects of diabetic status on circulating visfatin levels, and several other adipocytokines, demonstrating that diabetic status increased visfatin*, TNF-α*** and IL-6*** compared with non-diabetic subjects (*p<0.05, **p<0.01, ***p<0.001, respectively).Following insulin (Ins) and RSG treatment, our in vitro findings highlighted that insulin (100 nM), alone, upregulated visfatin protein expression whereas, in combination with RSG (10 nM), it reduced visfatin*, IKKβ** and p-JNK1/2*.Furthermore, inhibition of JNK protein exacted a significant reduction in visfatin expression (**p<0.01), whilst NF-κB blockade increased visfatin (*p<0.05), thus identifying JNK as the more influential factor in visfatin regulation.

View Article: PubMed Central - PubMed

Affiliation: Unit for Diabetes & Metabolism, Clinical Sciences Research Institute, UHCW Trust, Walsgrave, Coventry, United Kingdom.

ABSTRACT
Visfatin has been proposed as an insulin-mimicking adipocytokine, predominantly secreted from adipose tissue and correlated with obesity. However, recent studies suggest visfatin may act as a proinflammatory cytokine. Our studies sought to determine the significance of this adipocytokine and its potential role in the pathogenesis of T2DM. Firstly, we examined the effects of diabetic status on circulating visfatin levels, and several other adipocytokines, demonstrating that diabetic status increased visfatin*, TNF-α*** and IL-6*** compared with non-diabetic subjects (*p<0.05, **p<0.01, ***p<0.001, respectively). We then assessed the effects of an insulin sensitizer, rosiglitazone (RSG), in treatment naïve T2DM subjects, on circulating visfatin levels. Our findings showed that visfatin was reduced post-RSG treatment [vs. pre-treatment (*p<0.05)] accompanied by a reduction in HOMA-IR**, thus implicating a role for insulin in visfatin regulation. Further studies addressed the intracellular mechanisms by which visfatin may be regulated, and may exert pro-inflammatory effects, in human abdominal subcutaneous (Abd Sc) adipocytes. Following insulin (Ins) and RSG treatment, our in vitro findings highlighted that insulin (100 nM), alone, upregulated visfatin protein expression whereas, in combination with RSG (10 nM), it reduced visfatin*, IKKβ** and p-JNK1/2*. Furthermore, inhibition of JNK protein exacted a significant reduction in visfatin expression (**p<0.01), whilst NF-κB blockade increased visfatin (*p<0.05), thus identifying JNK as the more influential factor in visfatin regulation. Additional in vitro analysis on adipokines regulating visfatin showed that only Abd Sc adipocytes treated with recombinant human (rh)IL-6 increased visfatin protein (*p<0.05), whilst rh visfatin treatment, itself, had no influence on TNF-α, IL-6 or resistin secretion from Sc adipocytes. These data highlight visfatin's regulation by insulin and RSG, potentially acting through NF-κB and JNK mechanisms, with only rh IL-6 modestly affecting visfatin regulation. Taken together, these findings suggest that visfatin may represent a pro-inflammatory cytokine that is influenced by insulin/insulin sensitivity via the NF-κB and JNK pathways.

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Visfatin Protein Expression in Relation to Adiposity and Depot Specificity.This figure shows the mean relative fold protein expression of visfatin in omental (Om) versus abdominal (Abd) adipose tissue depots in matched pairs, from a cohort of lean and obese subjects, where the Abd Sc depot has been standardized. The representative Western blots are shown above. Lean samples: n = 7 & Obese samples: n = 6; p-values: p<0.001.
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pone-0020287-g002: Visfatin Protein Expression in Relation to Adiposity and Depot Specificity.This figure shows the mean relative fold protein expression of visfatin in omental (Om) versus abdominal (Abd) adipose tissue depots in matched pairs, from a cohort of lean and obese subjects, where the Abd Sc depot has been standardized. The representative Western blots are shown above. Lean samples: n = 7 & Obese samples: n = 6; p-values: p<0.001.

Mentions: The investigation of visfatin protein expression in relation to depot specificity in human AT identified that visfatin protein was significantly higher in Om AT, when compared with paired Abd Sc AT, independent of BMI (Lean: n = 7; Obese: n = 6, total: n = 13, ***p<0.001, Figure 2). Furthermore, an association between increasing adiposity and visfatin expression in human Abd Sc adipocytes and AT was not observed at either protein or mRNA level (data not shown). Lastly, differentiated pre-adipocytes and mature isolated adipocytes (Om and Abd Sc) demonstrated the presence of visfatin mRNA in isolated adipocytes: differentiated adipocytes ΔCt = 5.7±1.35(SEM), Om adipocytes ΔCt = 11.02±0.125, Abd Sc adipocytes ΔCt = 11.16±0.077. The mRNA visfatin level in human macrophages was comparable to that of the mature Om and Abd Sc adipocytes (ΔCt = 10.93±0.074), whilst visfatin expression was significantly lower in Om and Sc stromal cells, respectively, ΔCt = 12.75±0.175, Sc stromal ΔCt = 16.1±0.08 (p<0.05).


Visfatin is regulated by rosiglitazone in type 2 diabetes mellitus and influenced by NFκB and JNK in human abdominal subcutaneous adipocytes.

McGee KC, Harte AL, da Silva NF, Al-Daghri N, Creely SJ, Kusminski CM, Tripathi G, Levick PL, Khanolkar M, Evans M, Chittari MV, Patel V, Kumar S, McTernan PG - PLoS ONE (2011)

Visfatin Protein Expression in Relation to Adiposity and Depot Specificity.This figure shows the mean relative fold protein expression of visfatin in omental (Om) versus abdominal (Abd) adipose tissue depots in matched pairs, from a cohort of lean and obese subjects, where the Abd Sc depot has been standardized. The representative Western blots are shown above. Lean samples: n = 7 & Obese samples: n = 6; p-values: p<0.001.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3111427&req=5

pone-0020287-g002: Visfatin Protein Expression in Relation to Adiposity and Depot Specificity.This figure shows the mean relative fold protein expression of visfatin in omental (Om) versus abdominal (Abd) adipose tissue depots in matched pairs, from a cohort of lean and obese subjects, where the Abd Sc depot has been standardized. The representative Western blots are shown above. Lean samples: n = 7 & Obese samples: n = 6; p-values: p<0.001.
Mentions: The investigation of visfatin protein expression in relation to depot specificity in human AT identified that visfatin protein was significantly higher in Om AT, when compared with paired Abd Sc AT, independent of BMI (Lean: n = 7; Obese: n = 6, total: n = 13, ***p<0.001, Figure 2). Furthermore, an association between increasing adiposity and visfatin expression in human Abd Sc adipocytes and AT was not observed at either protein or mRNA level (data not shown). Lastly, differentiated pre-adipocytes and mature isolated adipocytes (Om and Abd Sc) demonstrated the presence of visfatin mRNA in isolated adipocytes: differentiated adipocytes ΔCt = 5.7±1.35(SEM), Om adipocytes ΔCt = 11.02±0.125, Abd Sc adipocytes ΔCt = 11.16±0.077. The mRNA visfatin level in human macrophages was comparable to that of the mature Om and Abd Sc adipocytes (ΔCt = 10.93±0.074), whilst visfatin expression was significantly lower in Om and Sc stromal cells, respectively, ΔCt = 12.75±0.175, Sc stromal ΔCt = 16.1±0.08 (p<0.05).

Bottom Line: Firstly, we examined the effects of diabetic status on circulating visfatin levels, and several other adipocytokines, demonstrating that diabetic status increased visfatin*, TNF-α*** and IL-6*** compared with non-diabetic subjects (*p<0.05, **p<0.01, ***p<0.001, respectively).Following insulin (Ins) and RSG treatment, our in vitro findings highlighted that insulin (100 nM), alone, upregulated visfatin protein expression whereas, in combination with RSG (10 nM), it reduced visfatin*, IKKβ** and p-JNK1/2*.Furthermore, inhibition of JNK protein exacted a significant reduction in visfatin expression (**p<0.01), whilst NF-κB blockade increased visfatin (*p<0.05), thus identifying JNK as the more influential factor in visfatin regulation.

View Article: PubMed Central - PubMed

Affiliation: Unit for Diabetes & Metabolism, Clinical Sciences Research Institute, UHCW Trust, Walsgrave, Coventry, United Kingdom.

ABSTRACT
Visfatin has been proposed as an insulin-mimicking adipocytokine, predominantly secreted from adipose tissue and correlated with obesity. However, recent studies suggest visfatin may act as a proinflammatory cytokine. Our studies sought to determine the significance of this adipocytokine and its potential role in the pathogenesis of T2DM. Firstly, we examined the effects of diabetic status on circulating visfatin levels, and several other adipocytokines, demonstrating that diabetic status increased visfatin*, TNF-α*** and IL-6*** compared with non-diabetic subjects (*p<0.05, **p<0.01, ***p<0.001, respectively). We then assessed the effects of an insulin sensitizer, rosiglitazone (RSG), in treatment naïve T2DM subjects, on circulating visfatin levels. Our findings showed that visfatin was reduced post-RSG treatment [vs. pre-treatment (*p<0.05)] accompanied by a reduction in HOMA-IR**, thus implicating a role for insulin in visfatin regulation. Further studies addressed the intracellular mechanisms by which visfatin may be regulated, and may exert pro-inflammatory effects, in human abdominal subcutaneous (Abd Sc) adipocytes. Following insulin (Ins) and RSG treatment, our in vitro findings highlighted that insulin (100 nM), alone, upregulated visfatin protein expression whereas, in combination with RSG (10 nM), it reduced visfatin*, IKKβ** and p-JNK1/2*. Furthermore, inhibition of JNK protein exacted a significant reduction in visfatin expression (**p<0.01), whilst NF-κB blockade increased visfatin (*p<0.05), thus identifying JNK as the more influential factor in visfatin regulation. Additional in vitro analysis on adipokines regulating visfatin showed that only Abd Sc adipocytes treated with recombinant human (rh)IL-6 increased visfatin protein (*p<0.05), whilst rh visfatin treatment, itself, had no influence on TNF-α, IL-6 or resistin secretion from Sc adipocytes. These data highlight visfatin's regulation by insulin and RSG, potentially acting through NF-κB and JNK mechanisms, with only rh IL-6 modestly affecting visfatin regulation. Taken together, these findings suggest that visfatin may represent a pro-inflammatory cytokine that is influenced by insulin/insulin sensitivity via the NF-κB and JNK pathways.

Show MeSH
Related in: MedlinePlus