Relationship between glycemic control and OPG gene polymorphisms with lower bone mineral density in patients with type 1 Diabetes mellitus

<div><p>ABSTRACT The aim of the present study was to investigate the bone mineral density (BMD) of patients with type 1 Diabetes mellitus (T1DM). We also assessed the association between osteoprotegerin (OPG) genetic polymorphisms and BMD. Genotyping was performed for 1181G>C and 163A>G OPG polymorphisms by allelic discrimination in 119 patients with T1DM and 161 normoglycemic (NG) individuals, aged 6 to 20 years old. Glycemic control, serum parameters of bone metabolism and BMD were evaluated. T1DM patients showed low BMD, poor glycemic control and decreased total calcium values when compared to controls (p < 0.05). For all the polymorphisms studied, the genotype and allele frequencies in patients with T1DM were not significantly different from the controls. In patients with T1DM, carriers of OPG 1181CC showed higher concentrations of ionized calcium compared to patients with GG+GC genotypes. These results suggest that low BMD is associated with poor glycemic control in T1DM. Despite the lack of a detected association between OPG polymorphisms and BMD in these patients, the increased ionized calcium in those carrying OPG 1181CC suggests a possible increase in osteoclastogenesis, a conclusion that may be supported by the lower BMD observed in these subjects.</p></div

Relative mRNA expression quantification.

<p><i>RANKL</i> (A), <i>OPG</i> (B), <i>OC</i> (C), <i>COL1A</i> (D), <i>MMP-2</i> (E), and <i>MMP-9</i> (F) mRNA expression in bone tissue of control, type 1 diabetes mellitus (T1DM), and T1DM plus zinc supplementation (T1DMS) rats. All data are expressed as fold-change vs. control group values, normalized to <i>GAPDH</i>. Comparisons between groups were analyzed with Kruskal-Wallis ANOVA on Ranks and Dunn’s post-hoc. <i>p</i> < 0.05*^/# vs. control group; <i>p</i> < 0.01*^/## vs. control group.</p

Assessment of collagen deposition by picrosirius red staining.

<p>Tibia staining for collagen content (picrosirius red). Total collagen (A), collagen type I (B), and collagen type III (C) contents of the control, type 1 diabetes mellitus (T1DM), and T1DM plus zinc supplementation (T1DMS) groups. All data are shown as means ± SEM. Comparisons between groups were analyzed with Kruskal-Wallis ANOVA on Ranks and Dunn’s post-hoc. <i>p</i> < 0.05 *^/# vs. control group.</p

Histological analyses of the right tibias.

<p>Hematoxylin and eosin staining of longitudinal sections of tibias of the control (A), type 1 diabetes mellitus (T1DM) (B), and T1DM plus zinc supplementation (T1DMS) (C) groups. TB, trabecular bone; MS, medullary space; magnification 20X, scale bar: 50 μm.</p

Histomorphometric analyses of structural bone architecture.

<p>Trabecular separation (TbSP, μm) (A), trabecular width (TbWi, μm) (B), and trabecular bone area (BAr, %) (C) of control, type 1 diabetes mellitus (T1DM), and T1DM plus zinc supplementation (T1DMS) rats. All data are shown as means ± SEM. Comparisons between groups were analyzed with Kruskal-Wallis ANOVA on Ranks and Dunn’s post-hoc. <i>p</i> < 0.01*^/## vs. control group; <i>p</i> < 0.001*^/### vs. control group; <i>p</i> < 0.05 **^/# vs. T1DM group; <i>p</i> < 0.001**^/### vs. T1DM group.</p

Tibia biomechanical parameters of control, diabetic, and diabetic plus zinc supplementation groups.

<p>T1DM, type 1 diabetes mellitus; T1DMS, T1DM plus zinc supplementation. All data are shown as means ± SEM. Comparisons between groups were analyzed with Kruskal-Wallis ANOVA on Ranks and Dunn’s post-hoc.</p><p>*^/#<i>p</i> < 0.05 vs. control group;</p><p>*^/##<i>p</i> < 0.01 vs. control group.</p><p>Tibia biomechanical parameters of control, diabetic, and diabetic plus zinc supplementation groups.</p

Biochemical analyses and body weight of control, diabetic, and diabetic plus zinc supplementation groups.

<p>T1DM, type 1 diabetes mellitus; T1DMS, T1DM plus zinc supplementation; ALP, alkaline phosphatase. All data are shown as means ± SEM. Comparisons between groups were analyzed with Kruskal-Wallis ANOVA on Ranks and Dunn’s post-hoc.</p><p>*^/#<i>p</i> < 0.05 vs. control group;</p><p>*^/##<i>p</i> < 0.01 vs. control group;</p><p>*^/###<i>p</i> < 0.001 vs. control group;</p><p>**^/##<i>p</i> < 0.01 vs. T1DM group.</p><p>Biochemical analyses and body weight of control, diabetic, and diabetic plus zinc supplementation groups.</p