Can microbiota modulate circadian oscillations to alter susceptibility to autoimmunity?

我们体内有一个生物钟，称为昼夜节律(CR)，每24小时重置一次。CR影响我们体内的所有细胞，包括组成我们免疫系统的白细胞，如T细胞。因此，免疫系统对“威胁”的反应可以通过CR改变。此外，胰腺中产生胰岛素的β细胞也受CRS控制。在1型糖尿病(T1D)中，一些T细胞通过识别称为多肽的小段蛋白质来攻击产生胰岛素的β细胞。目前尚不清楚是什么触发了这种攻击，但正在探索的一个领域与生活在我们体内的细菌有关。儿童的证据表明，那些最有可能患上T1D的人的肠道中存在不同的细菌，这可能会改变免疫系统，如T细胞，对它们的反应方式。最近，有研究表明细菌可以通过免疫系统改变体内的CR。因此，细菌可能是改变CR的有用靶点，以促进更健康的免疫系统，防止T1D的发展。这项研究以前从未被研究过。这项研究的目的是了解我们体内的细菌如何影响T细胞和靶向产生胰岛素的β细胞的CR。我假设细菌可以改变这两种细胞的CR，导致T细胞破坏β细胞的能力发生变化。我将使用非肥胖糖尿病(NOD)小鼠模型来研究这一点，该模型与人类类似，会发展为自发性T1D。这项研究将围绕三个主要目标展开：1.细菌是否改变了产生胰岛素的β细胞中的CR，使它们更容易成为T细胞的靶点？2.细菌是否改变了T细胞中的CR，从而更好地破坏了β细胞？3.破坏β细胞或CD8 T细胞中的CR是否会特别改变患T1D的风险？我将研究有细菌的NOD小鼠和没有任何细菌的NOD小鼠，称为无菌(GF)小鼠。这些小鼠将被用来鉴定细菌对β细胞和CD8 T细胞的CR所起的作用。将在两个不同的时间点对所有小鼠进行研究，以确定CRR引起的变化。将研究产生胰岛素的β细胞产生胰岛素的能力，并研究它们产生的多肽，这些多肽可能使它们成为CD8 T细胞的靶标。这将涉及对NOD小鼠进行成像，这些小鼠在产生胰岛素后有荧光(有色)信号，这使得它们能够被可视化。我还将把荧光细菌引入GF NOD小鼠，使我能够直观地看到细菌是否可以进入胰腺。我还将研究细菌产生的可能改变β细胞CR的产物。CD8 T细胞将被研究，因为它们是在患有T1D的人的胰腺中发现的最常见的T细胞。我将研究一种特定的CD8 T细胞，它可以识别由β细胞产生的多肽和由细菌产生的类似多肽。识别这两种多肽中的任何一种都会导致CD8T细胞破坏β细胞。CD8 T细胞将被研究与β细胞的相互作用，它们摧毁被多肽覆盖的靶细胞的能力，以及可能帮助细胞变得更具破坏性的能量使用的变化。我还将研究在CR的不同时间点对细菌的反应如何也影响CD8T细胞。最后，我将在β细胞或CD8T细胞中特异性地产生CR缺陷的NOD小鼠和GF NOD小鼠。如上所述，将对这些小鼠进行研究，并研究它们患自发性糖尿病的能力。这将有助于确定哪些细胞(β细胞或CD8T细胞)可能成为未来治疗的更好靶点。了解CR及其如何改变细胞可以确定特定的时间点，在这些时间点上可以最大化治疗成功。鉴于越来越多的人被诊断为T1D，而且缺乏成功的治疗方法，这是迫切需要的。

In our body exists an internal clock, known as the circadian rhythm (CR), which resets every 24 hours. The CR affects all cells in our body, including white blood cells, such as T cells, that make up our immune system. Thus, the immune system's response to "threats" can be altered by the CR. In addition, the beta cells that produce insulin in the pancreas are also controlled by CRs. In Type 1 diabetes (T1D), some T cells attack the insulin-producing beta cells by recognising small pieces of protein, called peptides, as foreign. It is currently unknown what triggers this attack but one area being explored relates to the germs (bacteria) that live in our body. Evidence in children suggests that those at greatest risk for developing T1D have different bacteria present in their intestine and that this can change how the immune system, such as T cells, respond to them. Recently, it has been shown that bacteria can change the CR in the body through the immune system. Thus, bacteria may be a useful target for altering the CR to promote a healthier immune system, preventing the development of T1D. This has not been studied before.This research aims to understand how the bacteria in our bodies affect the CR of both T cells and the targeted insulin-producing beta cells. I hypothesise that bacteria can change the CR of both cell types, resulting in changes to the T cell's ability to destroy the beta cells. I will investigate this using the Non-obese diabetic (NOD) mouse model, which develops spontaneous T1D similar to humans. This work will be studied in 3 main aims:1. Do bacteria change the CR in the insulin-producing beta cells making them more easily targeted by the T cells?2. Do bacteria change the CR in the T cells making them better at destroying the beta cells?3. Does disruption to the CR in the beta cells or CD8 T cells specifically alter the risk of developing T1D?I will study both NOD mice with bacteria and NOD mice that do not have any bacteria, called Germ-free (GF) mice. These mice will be used to identify the role bacteria have on the CR of both beta cells and CD8 T cells. All mice will be studied at two different time points to identify changes caused by the CR.Insulin-producing beta cells will be studied for their ability to produce insulin and will be investigated for the peptides they produce that may make them targets for the CD8 T cells. This will involve imaging NOD mice that have a fluorescent (coloured) signal after producing insulin, which allows them to be visualised. I will also introduce fluorescent bacteria into GF NOD mice allowing me to visualise whether the bacteria can enter the pancreas. I will also look at products bacteria produce that may alter the CR of the beta cells.CD8 T cells will be studied as they are the most common T cell found in the pancreas of humans with T1D. I will study a specific CD8 T cell that can recognise both a peptide produced by the beta cells and a similar peptide produced by bacteria. Recognition of either of these peptides will result in the CD8 T cells destroying the beta cells. CD8 T cells will be studied for their interactions with beta cells, their ability to destroy peptide-coated target cells and changes in energy usage that may help the cells become more damaging. I will also study how responses to bacteria at different time points of the CR can also affect the CD8 T cells.Finally, I will generate CR-deficient NOD mice and GF NOD mice in either beta cells or CD8 T cells specifically. These mice will be studied as mentioned above, as well as for their ability to develop spontaneous diabetes. This will help identify which cells (beta cells or CD8 T cells) may make better targets for future therapy. Understanding the CR and how it changes the cells may identify specific time points in which therapeutic success can be maximised. Given the increasing number of people diagnosed with T1D, and a lack of successful therapies, this is urgently needed.