Blandino-Rosano M, Perez-Arana G, Mellado-Gil J M, Segundo C, Aguilar-Diosdado M
Investigation Unit and Endocrinology and Nutrition Service, Puerta del Mar Hospital, Ana de Viya, 21, Cadiz 11009, Spain.
J Mol Endocrinol. 2008 Jul;41(1):35-44. doi: 10.1677/JME-07-0154. Epub 2008 May 16.
Pancreatic beta-cell homeostasis is a balance between programmed cell death (apoptosis) and regeneration. Although autoimmune diabetes mellitus type 1 (DM1) is the most-studied cause of beta-cell mass loss by pro-inflammatory cytokine-induced apoptosis, influences of a pro-inflammatory environment on beta-cell regenerative response have been poorly studied. In this study, we assess the anti-proliferative effect of pro-inflammatory cytokines and glucose concentration on rat pancreatic beta cells and the potential protective role of glucagon-like peptide (GLP-1). Apoptotic and proliferating islet cells were stained using the DeadEnd Fluorimetric TUNEL System and 5-bromo-2'-deoxyuridine label respectively, in the presence-absence of varying concentrations of glucose, pro-inflammatory cytokines, and GLP-1. The potential signaling pathways involved were evaluated by western blot. Considerable anti-proliferative effects of pro-inflammatory cytokines interleukin (IL)-1beta, interferon (IFN)-gamma, and tumour necrosis factor-alpha (TNF-alpha) were observed. The effects were synergistic and independent of glucose concentration, and appeared to be mediated by the inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) activation, the signaling pathway involved in beta-cell replication. GLP-1 completely reversed the cytokine-induced inhibition of ERK phosphorylation and increased beta-cell proliferation threefold in cytokine-treated cultures. While pro-inflammatory cytokines reduced islet cell ERK1/2 activation and beta-cell proliferation in pancreatic islet culture, GLP-1 was capable of reversing this effect. These data suggest a possible pharmacological application of GLP-1 in the treatment of early stage DM1, to prevent the loss of pancreatic beta cells as well as to delay the development of overt diabetes.
胰腺β细胞稳态是程序性细胞死亡（凋亡）与再生之间的平衡。尽管自身免疫性1型糖尿病（DM1）是促炎细胞因子诱导的凋亡导致β细胞数量减少的研究最为深入的原因，但促炎环境对β细胞再生反应的影响却鲜有研究。在本研究中，我们评估了促炎细胞因子和葡萄糖浓度对大鼠胰腺β细胞的抗增殖作用以及胰高血糖素样肽（GLP-1）的潜在保护作用。在存在或不存在不同浓度的葡萄糖、促炎细胞因子和GLP-1的情况下，分别使用DeadEnd荧光定量TUNEL系统和5-溴-2'-脱氧尿苷标记对凋亡和增殖的胰岛细胞进行染色。通过蛋白质印迹法评估相关的潜在信号通路。观察到促炎细胞因子白细胞介素（IL）-1β、干扰素（IFN）-γ和肿瘤坏死因子-α（TNF-α）具有显著的抗增殖作用。这些作用具有协同性且与葡萄糖浓度无关，似乎是通过抑制细胞外信号调节激酶1/2（ERK1/2）的激活介导的，ERK1/2激活是参与β细胞复制的信号通路。GLP-1完全逆转了细胞因子诱导的ERK磷酸化抑制，并使细胞因子处理的培养物中的β细胞增殖增加了三倍。虽然促炎细胞因子降低了胰岛培养物中胰岛细胞的ERK1/2激活和β细胞增殖，但GLP-1能够逆转这种作用。这些数据表明GLP-1在治疗早期DM1方面可能具有药理学应用，以防止胰腺β细胞的丢失并延缓显性糖尿病的发展。
