Skowera Ania, Ellis Richard J, Varela-Calviño Ruben, Arif Sefina, Huang Guo Cai, Van-Krinks Cassie, Zaremba Anna, Rackham Chloe, Allen Jennifer S, Tree Timothy I M, Zhao Min, Dayan Colin M, Sewell Andrew K, Unger Wendy W, Drijfhout Jan W, Ossendorp Ferry, Roep Bart O, Peakman Mark
Department of Immunobiology, King's College London, London, United Kingdom.
J Clin Invest. 2008 Oct;118(10):3390-402. doi: 10.1172/JCI35449.
The final pathway of beta cell destruction leading to insulin deficiency, hyperglycemia, and clinical type 1 diabetes is unknown. Here we show that circulating CTLs can kill beta cells via recognition of a glucose-regulated epitope. First, we identified 2 naturally processed epitopes from the human preproinsulin signal peptide by elution from HLA-A2 (specifically, the protein encoded by the A*0201 allele) molecules. Processing of these was unconventional, requiring neither the proteasome nor transporter associated with processing (TAP). However, both epitopes were major targets for circulating effector CD8+ T cells from HLA-A2+ patients with type 1 diabetes. Moreover, cloned preproinsulin signal peptide-specific CD8+ T cells killed human beta cells in vitro. Critically, at high glucose concentration, beta cell presentation of preproinsulin signal epitope increased, as did CTL killing. This study provides direct evidence that autoreactive CTLs are present in the circulation of patients with type 1 diabetes and that they can kill human beta cells. These results also identify a mechanism of self-antigen presentation that is under pathophysiological regulation and could expose insulin-producing beta cells to increasing cytotoxicity at the later stages of the development of clinical diabetes. Our findings suggest that autoreactive CTLs are important targets for immune-based interventions in type 1 diabetes and argue for early, aggressive insulin therapy to preserve remaining beta cells.
导致胰岛素缺乏、高血糖和临床1型糖尿病的β细胞破坏的最终途径尚不清楚。在此，我们表明循环中的细胞毒性T淋巴细胞（CTL）可通过识别一种葡萄糖调节表位来杀死β细胞。首先，我们通过从HLA - A2（具体而言，由A*0201等位基因编码的蛋白质）分子上洗脱，鉴定出了来自人胰岛素原信号肽的2个天然加工表位。这些表位的加工方式是非传统的，既不需要蛋白酶体也不需要与加工相关的转运体（TAP）。然而，这两个表位都是来自HLA - A2 +的1型糖尿病患者循环效应性CD8 + T细胞的主要靶标。此外，克隆的胰岛素原信号肽特异性CD8 + T细胞在体外可杀死人β细胞。至关重要的是，在高葡萄糖浓度下，β细胞对胰岛素原信号表位的呈递增加，CTL杀伤作用也增强。本研究提供了直接证据，表明自身反应性CTL存在于1型糖尿病患者的循环中，并且它们可以杀死人β细胞。这些结果还确定了一种受病理生理调节的自身抗原呈递机制，该机制可能会使产生胰岛素的β细胞在临床糖尿病发展的后期阶段面临越来越大的细胞毒性。我们的研究结果表明，自身反应性CTL是1型糖尿病基于免疫干预的重要靶标，并支持早期积极的胰岛素治疗以保护剩余的β细胞。
