Department of Physiology & Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.
Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) theme, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada.
Front Endocrinol (Lausanne). 2022 Oct 7;13:932516. doi: 10.3389/fendo.2022.932516. eCollection 2022.
Type 1 Diabetes (T1D) is caused by insulin deficiency, due to progressive autoimmune destruction of pancreatic β cells. Glucagon-secreting α cells become dysfunctional in T1D and contribute to pathophysiology, however, the mechanisms involved are unclear. While the majority of β cells are destroyed in T1D, some β cells escape this fate and become senescent but whether α cell dysfunction involves a senescence program has not been explored. Here we addressed the question of whether α cells become senescent during the natural history of T1D in the non-obese diabetic (NOD) mouse model and humans. NOD mice had several distinct subpopulations of α cells, but none were defined by markers of senescence at the transcriptional or protein level. Similarly, α cells of human T1D donors did not express senescence markers. Despite the lack of senescence in α cells , using a human islet culture model, we observed that DNA damage-induced senescence led to alterations in islet glucagon secretion, which could be rescued by inhibiting the senescence-associated secretory phenotype (SASP). Together our results suggest that α cell dysfunction in T1D is not due to activation of a senescence program, however, senescent β cell accumulation in the islet microenvironment may have a negative effect on α cell function.
1 型糖尿病(T1D)是由胰岛素缺乏引起的,这是由于胰腺β细胞进行性自身免疫破坏所致。在 T1D 中,分泌胰高血糖素的α细胞功能失调,并有助于病理生理学发生,但涉及的机制尚不清楚。虽然大多数β细胞在 T1D 中被破坏,但一些β细胞逃脱了这种命运并衰老,但α细胞功能障碍是否涉及衰老程序尚未得到探索。在这里,我们研究了在非肥胖型糖尿病(NOD)小鼠模型和人类中,T1D 的自然病史中α细胞是否会衰老的问题。NOD 小鼠的α细胞有几个不同的亚群,但在转录或蛋白质水平上没有一个亚群是由衰老标志物定义的。同样,人类 T1D 供体的α细胞也不表达衰老标志物。尽管α细胞中没有衰老,但在人类胰岛培养模型中,我们观察到 DNA 损伤诱导的衰老会导致胰岛胰高血糖素分泌的改变,而抑制衰老相关分泌表型(SASP)可以挽救这种改变。总之,我们的结果表明,T1D 中α细胞功能障碍不是由于衰老程序的激活引起的,但是衰老的β细胞在胰岛微环境中的积累可能对α细胞功能产生负面影响。