Calcium and 1,25-dihydroxyvitamin D3 regulation of adipokine expression.
OBJECTIVE
Obesity is associated with elevated oxidative stress and low-grade systemic inflammation. We have demonstrated recently that 1alpha,25-(OH)(2)-D(3) promotes reactive oxygen species production in cultured adipocytes, whereas suppression of 1alpha,25-(OH)(2)-D(3) by increasing dietary calcium down-regulates diet-induced oxidative stress in aP2-agouti transgenic mice. However, whether the anti-obesity effect of dietary calcium plays a role in regulation of obesity-associated inflammation is not clear.


METHODS
We investigated the role of dietary calcium in the regulation of inflammatory cytokine production in aP2-agouti transgenic mice fed low- and high-calcium obesigenic diets and in the modulation of cytokine production by 1alpha,25-(OH)(2)-D(3) in cultured murine and human adipocytes.


RESULTS
The high-calcium diet inhibited the expression of pro-inflammatory factors tumor necrosis factor alpha and interleukin (IL)-6 by 64% and 51%, respectively (p < 0.001), in visceral fat, stimulated the expression of the anti-inflammatory factors IL-15 and adiponectin by 52% (p = 0.001) and 54% (p = 0.025), respectively, in visceral fat, and induced a 2-fold increase in IL-15 expression in soleus muscle (p = 0.01) compared with litter mate controls on a low-calcium diet. 1alpha,25-(OH)(2)-D(3) also markedly stimulated the expression of tumor necrosis factor alpha (p < 0.001) and IL-6 (p = 0.016) in differentiated 3T3-L1 adipocytes and increased IL-6 (p = 0.004) and IL-8 (p < 0.001) production in differentiated human adipocytes. These effects were blocked by calcium channel antagonism with nifedipine.


CONCLUSIONS
These data demonstrate that 1alpha,25-(OH)(2)-D(3) favors inflammatory cytokine expression and inhibits anti-inflammatory cytokine expression; accordingly, suppression of 1alpha,25-(OH)(2)-D(3) by dietary calcium inhibits adipocyte-derived inflammation associated with obesity.
Sun
Xiaocun
X
Department of Nutrition, University of Tennessee, Knoxville, TN 37996-1900, USA.
Zemel
Michael B
MB
D041721:3T3-L1 Cells; D052242:Adiponectin / Q000235:genetics* / Q000378:metabolism; D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002136:Calcium, Dietary / Q000494:pharmacology*; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D019409:Interleukin-15 / Q000235:genetics* / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D018482:Muscle, Skeletal / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism
D052242:Adiponectin; D002136:Calcium, Dietary; D019409:Interleukin-15; D015850:Interleukin-6; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D002117:Calcitriol