Early glycation products of collagen: a solid-state NMR spectrscopy and ultrastructural study of biological and health implications

胶原蛋白是人体组织的主要成分。像体内的许多蛋白质一样，它是糖基化的，也就是说，它是用糖分子装饰的。它们的功能尚不清楚，尽管有证据表明它们有助于排列胶原蛋白分子，形成组织结构完整性所需的强大网络。在人的一生中，人体的胶原蛋白会积累更多的糖分子，这些糖分子会发生各种化学反应，导致胶原蛋白分子之间产生永久性的交联——即所谓的晚期糖基化终产物（AGEs）。它们使胶原蛋白基质变硬，至少在一定程度上导致动脉硬化（进而导致高血压和其他各种血管问题）。它们对皮肤和其他组织的老化也很重要，如果一个人的血糖水平往往高于正常水平，比如糖尿病患者，它们积累得更快，它们是糖尿病患者遭受的许多慢性问题的原因，比如肾功能下降。人们对胶原蛋白中糖积累的早期阶段及其对组织健康的影响知之甚少。它不仅可能影响组织的材料强度和完整性，还可能影响组织中生活和生长的细胞的行为，例如，这些细胞可能会引起组织中的慢性炎症。因此，虽然目前的研究重点是逆转交联过程的药物，但有重要证据表明，去除交联本身并不能恢复组织的健康。尽管AGE交联无疑会对组织造成损害，但目前尚不清楚有多少损害是由AGE本身引起的，有多少是由最初的糖结合引起的，以及在AGE形成后仍保持结合的糖。这个项目将使用最先进的方法来确定最初与胶原蛋白结合的糖实际上是如何与胶原蛋白结合的，以及它对组织强度和细胞行为的影响。我们将使用一种称为固态核磁共振（NMR）的光谱学形式来确定胶原蛋白和胶原蛋白结合糖的详细结构，并使用电子显微镜来确定糖如何影响胶原蛋白分子排列的方式。我们将使用类似的技术来发现糖结合是否会影响骨矿化的方式，这与骨质疏松症等疾病有关，或者它是否会促进动脉钙化，这是一个导致动脉严重硬化的过程，以及由此带来的所有健康影响。确定早期阶段糖结合对胶原蛋白的影响将最终转化为对糖尿病患者等高危人群的早期检测方法，并将使我们确定找到预防或逆转这种早期阶段糖结合以及最终阶段的方法的重要性。该项目的一部分内容将包括开发模拟体内糖结合过程的细胞培养物，这些培养物可用于评估预防或逆转糖结合的潜在疗法。这个项目的成果将特别有利于糖尿病患者，因为它最终将允许预防或减轻这种疾病使人衰弱的慢性影响的治疗方法，但也将有助于为所有人制定健康的老龄化战略。

Collagen is the principal component of the body's tissues. Like many proteins in the body, it is glycosylated, that is, it is decorated with sugar molecules. The function of these is not clear, although there is evidence that they assist in lining up the collagen molecules to form the strong network that is needed for the structural integrity of a tissue. Over a lifetime, the body's collagen accumulates more sugar molecules and these can and do undergo various chemical reactions that result in permanent cross links between collagen molecules - so-called advanced glycation endproducts (AGEs). These stiffen the collagen matrix and are, at least in part, responsible for hardening of the arteries (which in turn causes high blood pressure and various other vascular issues). They are also important in ageing of skin and other tissues and they accumulate much faster if a person's blood sugar level tends to be higher than normal, i.e. in diabetic patients, where they are responsible for many of the chronic issues that diabetics suffer, such as reduced kidney function. Little is known about the early stages of sugar accumulation in collagen and the effects it may have on the health of a tissue. Not only is it likely to affect the material strength and integrity of the tissue, it is likely to affect how the cells that live and grow in the tissue behave, so that for instance, the cells may act to cause chronic inflammation in the tissue. Thus while the current focus is on drugs to reverse the cross linking process, there is significant evidence that removing the cross links does not of itself restore the tissue's health. Although the AGE cross links undoubtedly do damage in tissues, it is not clear how much of the damage is caused by the AGEs themselves and how much by the initial sugar binding, and the sugar which remains bound even after AGEs have formed. This project will use state-of-the-art methods to determine how the sugar that initially binds to collagen is actually bound to the collagen and the effect it has on the tissue strength and the behaviour of cells. We will use a form of spectroscopy known as solid-state nuclear magnetic resonance (NMR) to determine detailed structures of the collagen and collagen-bound sugar and electron microscopy to determine how the sugar affects the way collagen molecules align themselves together. We will use similar techniques to find out if the sugar binding affects the way that bone mineralises, which is relevant to diseases such as osteoporosis or whether it might encourage calcification of arteries, a process that causes very significant hardening of the arteries and all the health implications that that has.Determining the effect of the early stages of sugar binding on collagen will eventually translate into early detection methods for those at risk, such as diabetic patients, and will allow us to determine how important it is to find methods to prevent or reverse this early stage sugar binding as well as the endstages. Part of the project will involve developing cell cultures which mimic the sugar binding process that happens in the body and these can be used to assess potential therapies for preventing or reversing the sugar binding.The results of this project will particularly benefit diabetic patients, in eventually allowing therapies which will prevent or alleviate the debilitating chronic effects of the disease, but will also assist in devising healthy ageing strategies for all.