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TNF-α gene expression is increased following zinc supplementation in type 2 diabetes mellitus

Chu, Anna, Foster, Meika, Hancock, Dale, Bell-Anderson, Kim, Petocz, Peter, Samman, Samir
Genes & nutrition 2015 v.10 no.1 pp. 440
dietary mineral supplements, gene expression, genes, homeostasis, inflammation, interleukin-1beta, interleukin-6, metabolism, metallothionein, mononuclear leukocytes, noninsulin-dependent diabetes mellitus, randomized clinical trials, regression analysis, transporters, tumor necrosis factor-alpha, women, zinc
Chronic low-grade inflammation in type 2 diabetes mellitus (DM) can elicit changes in whole-body zinc metabolism. The interaction among the expression of inflammatory cytokines, zinc transporter and metallothionein (MT) genes in peripheral blood mononuclear cells in type 2 DM remains unclear. In a 12-week randomized controlled trial, the effects of zinc (40 mg/day) supplementation on the gene expression of cytokines, zinc transporters and MT in women with type 2 DM were examined. In the zinc-supplemented group, gene expression of tumour necrosis factor (TNF)-α tended to be upregulated by 27 ± 10 % at week 12 compared to baseline (P = 0.053). TNF-α fold change in the zinc-treated group was higher than in those without zinc supplementation (P < 0.05). No significant changes were observed in the expression or fold change of interleukin (IL)-1β or IL-6. Numerous bivariate relationships were observed between the fold changes of cytokines and zinc transporters, including ZnT7 with IL-1β (P < 0.01), IL-6 (P < 0.01) and TNF-α (P < 0.01). In multiple regression analysis, IL-1β expression was predicted by the expression of all zinc transporters and MT measured at baseline (r ² = 0.495, P < 0.05) and at week 12 (r ² = 0.532, P < 0.03). The current study presents preliminary evidence that zinc supplementation increases cytokine gene expression in type 2 DM. The relationships found among zinc transporters, MT and cytokines suggest close interactions between zinc homeostasis and inflammation.