Mieczkowska Aleksandra, Mansur Sity Aishah, Irwin Nigel, Flatt Peter R, Chappard Daniel, Mabilleau Guillaume
LUNAM Université, GEROM-LHEA, Institut de Biologie en Santé, Angers, France.
School of Biomedical Sciences, University of Ulster, Coleraine, United Kingdom; University Tun Hussein Onn Malaysia, Johor, Malaysia.
Bone. 2015 Jul;76:31-9. doi: 10.1016/j.bone.2015.03.010. Epub 2015 Mar 23.
Type 1 diabetes mellitus (T1DM) is a severe disorder characterized by hyperglycemia and hypoinsulinemia. A higher occurrence of bone fractures has been reported in T1DM, and although bone mineral density is reduced in this disorder, it is also thought that bone quality may be altered in this chronic pathology. Vibrational microscopies such as Fourier transform infrared microspectroscopy (FTIRM) represent an interesting approach to study bone quality as they allow investigation of the collagen and mineral compartment of the extracellular matrix in a specific bone location. However, as spectral feature arising from the mineral may overlap with those of the organic component, the demineralization of bone sections should be performed for a full investigation of the organic matrix. The aims of the present study were to (i) develop a new approach, based on the demineralization of thin bone tissue section to allow a better characterization of the bone organic component by FTIRM, (ii) to validate collagen glycation and collagen integrity in bone tissue and (iii) to better understand what alterations of tissue material properties in newly forming bone occur in T1DM. The streptozotocin-injected mouse (150 mg/kg body weight, injected at 8 weeks old) was used as T1DM model. Animals were randomly allocated to control (n = 8) or diabetic (n = 10) groups and were sacrificed 4 weeks post-STZ injection. Bones were collected at necropsy, embedded in polymethylmethacrylate and sectioned prior to examination by FTIRM. FTIRM collagen parameters were collagen maturity (area ratio between 1660 and 1690 cm(-1) subbands), collagen glycation (area ratio between the 1032 cm(-1) subband and amide I) and collagen integrity (area ratio between the 1338 cm(-1) subband and amide II). No significant differences in the mineral compartment of the bone matrix could be observed between controls and STZ-injected animals. On the other hand, as compared with controls, STZ-injected animals presented with significant higher value for collagen maturity (17%, p = 0.0048) and collagen glycation (99%, p = 0.0121), while collagen integrity was significantly lower by 170% (p = 0.0121). This study demonstrated the profound effect of early T1DM on the organic compartment of the bone matrix in newly forming bone. Further studies in humans are required to ascertain whether T1DM also lead to similar effect on the quality of the bone matrix.
1型糖尿病（T1DM）是一种以高血糖和低胰岛素血症为特征的严重疾病。据报道，T1DM患者骨折发生率较高，尽管该疾病中骨矿物质密度降低，但也有人认为在这种慢性病理状态下骨质量可能会发生改变。诸如傅里叶变换红外显微光谱（FTIRM）等振动显微镜技术是研究骨质量的一种有趣方法，因为它们能够在特定骨位置研究细胞外基质的胶原蛋白和矿物质成分。然而，由于矿物质产生的光谱特征可能与有机成分的光谱特征重叠，因此应进行骨切片脱矿处理以全面研究有机基质。本研究的目的是：（i）开发一种基于薄骨组织切片脱矿的新方法，以便通过FTIRM更好地表征骨有机成分；（ii）验证骨组织中的胶原糖基化和胶原完整性；（iii）更好地了解T1DM中新形成骨的组织材料特性发生了哪些改变。将注射链脲佐菌素的小鼠（150mg/kg体重，8周龄时注射）用作T1DM模型。动物被随机分为对照组（n = 8）或糖尿病组（n = 10），并在注射链脲佐菌素后4周处死。在尸检时收集骨骼，嵌入聚甲基丙烯酸甲酯中，并在通过FTIRM检查之前进行切片。FTIRM胶原参数包括胶原成熟度（1660至1690cm(-1)子带之间的面积比）、胶原糖基化（1032cm(-1)子带与酰胺I之间的面积比）和胶原完整性（1338cm(-1)子带与酰胺II之间的面积比）。在对照组和注射链脲佐菌素的动物之间，未观察到骨基质矿物质成分的显著差异。另一方面，与对照组相比，注射链脲佐菌素的动物的胶原成熟度（17%，p = 0.0048）和胶原糖基化（99%，p = 0.0121）的值显著更高，而胶原完整性显著降低了170%（p = 0.0121）。本研究证明了早期TIDM对新形成骨的骨基质有机成分有深远影响。需要在人类中进行进一步研究，以确定T1DM是否也会对骨基质质量产生类似影响。
