Oral administration of insulin to female nonobese diabetic mice inhibited diabetes and induced Fas ligand expression on islets of Langerhans

Objective To detect oral administration of recombinant human insulin to nonobese diabetic (NOD) mice for preventing them from diabetes and insulitis and to detect the effects of oral administration of insulin on Fas and Fas ligand expression on islet of Langerhans. Methods Sixty-four female NOD mice were divided into two groups.One group (34) was orally administered recombination human insulin 1 mg in 500 μl PBS and the other (30) 500 μl PBS only at age of 5 weeks old, twice a week for the first week, then weekly until 30 weeks of age. Results Oral administration of insulin to female NOD mice can significantly suppress diabetes and insulitis.The insulitis was less severe in the group fed with insulin than that in the control group (score of insulitis: 1.25±0.45 vs 3.0±0.76 at 16 weeks of age, P<0.01).We examined Fas ligand and Fas expression on islets of Langerhans in both groups of NOD mice by using immunohistochemical techniques.We find that Fas only expressed on islets when the mice suffered the diabetes, whereas Fas ligand expressed on islets of the mice fed with insulin at 16 and 20 week of ages.We did not find Fas ligand positive staining on the islet feeding with PBS. Conclusion We speculated that oral insulin may induce Fas ligand expression on the islets and plays a role in protecting the pancreatic β-cell from autoimmune destruction.These results show that oral insulin affected autoimmune diabetes and insulitis in NOD mice.The immune mechanism of oral tolerance is closely related to the change of Fas ligand and Fas system.     

Expression of monocyte chemoattractant protein-1 in the pancreas of mice

Background Type 1 diabetes has been recognized as an organ specific autoimmune disease owing to the immune destruction of pancreatic islet β cells in genetically susceptible individuals. In both human and rodent models of type 1 diabetes, such as nonobese diabetic (NOD) mice, biobreeding rats, the disease has a distinct stage characterized by immune cells infiltrating in the pancreas (insulitis). The major populations of infiltrating cells are macrophages and T lymphocytes. Therefore, immune cell infiltration of pancreatic islets may be a crucial step in the pathogenesis of type 1 diabetes. Monocyte chemoattractant protein-1 can specifically attract monocytes in vivo. Interferon induced protein-10 has chemoattractant effects on the activated lymphocytes. In this study, we analysed the expression of monocyte chemoattractant protein-1 in the pancreas of mice and interferon inducible protein-10 mRNA in the pancreas of NOD mice, and discussed their possible role in the pathogenesis of type 1 diabetes. Methods The immunohistochemical method and immunoelectronmicroscopy were used to evaluate the expression of monocyte chemoattractant protein-1 in the pancreas of NOD mice and BALB/c mice. RT-PCR was used to evaluate the expression of monocyte chemoattractant protein-1 and interferon inducible protein mRNA in NOD mice.Results Monocyte chemoattractant protein-1 was positive in the pancreas of NOD mice, whereas negative in the pancreas of BALB/C mice. RT-PCR showed that monocyte chemoattractant protein-1 and interferon inducible protein-10 mRNA could be found in the pancreas of NOD mice. Immunoelectronmicroscopy demonstrated that monocyte chemoattractant protein-1 was produced by β cells and stored in the cytoplasm of the cells.Conclusions Pancreatic islet β cells produce monocyte chemoattractantprotein-1 in NOD mice. Monocyte chemoattractant protein-1 may play an important part in the pathogenesis of type 1 diabetes by attracting monocytes/macrophages to infiltrate pancreatic islets.     

小鼠胰岛α细胞的缺失对移植胰岛功能的影响

目的　探讨胰岛α细胞的丢失对胰岛素分泌功能的影响。方法　在人胰岛分离过程中 ,经胶原酶的过度消化造成胰岛周边α细胞缺失 ,用免疫组化及胰岛素 /胰高糖素含量分析予以证实。在体外 ,检测葡萄糖刺激引起的实验性糖尿病小鼠胰岛素的分泌 ;在体内 ,评价胰岛移植后对糖尿病小鼠血糖的调节 ,并研究胰高糖素对α细胞缺失胰岛功能的影响。结果　胶原酶的过度消化引起胰岛周边的α细胞丢失 ,使分离胰岛内胰岛素 /胰高糖素比值明显升高。与正常胰岛相比 ,α细胞缺失胰岛对葡萄糖刺激产生的胰岛素明显降低 ,胰岛素释放在正常胰岛和α细胞缺失胰岛分别为2 2 2 7uU/ml± 32 1uU/ml和 12 4 6uU/ml± 12 6uU/ml(P <0 0 1)。在体内 ,移植α细胞缺失的胰岛到糖尿病的C5 7/BL小鼠后不能有效地纠正动物的高血糖 ,胰岛移植后的平均血糖浓度在正常胰岛组和α细胞缺失胰岛组分别为 :8 9mmol/L± 1 98mmol/L和 2 1 3mmol/L± 2 2mmol/L(P <0 0 1) ,而给予外源性的胰高糖素可以在体外及体内明显改善α细胞缺失胰岛的胰岛素分泌功能。结论　胰岛α细胞的缺失明显降低胰岛的胰岛素分泌功能 ,用外源性的胰高糖素可以改善α细胞缺失胰岛的胰岛素分泌功能。     

人胚胎干细胞体外定向诱导分化胰腺前体细胞及胰岛细胞移植治疗NOD/SCID糖尿病小鼠

目的 探讨人胚胎干细胞（human embryonic stem cells,hESCs）体外定向诱导分化胰腺前体细胞及胰岛细胞移植治疗非肥胖糖尿病/严重联合免疫缺陷（non-obese diabetic/severe combined immunodeficient,NOD/SCID）小鼠的可行性.方法 体外分4阶段诱导hESCs定向分化为胰岛细胞：①诱导分化形成定型内胚层;②诱导胰腺细胞定向分化;③扩增胰腺前体细胞;④促进胰岛细胞成熟.观察诱导各阶段细胞形态变化、免疫荧光鉴定胰十二指肠同源异型盒基因（PDX-1）、胰高糖素（glucagon）、胰岛素（insulin）、C肽（C-peptide）、葡萄糖转运子2（Glut-2）的表达.3阶段及4阶段分化形成的细胞分别植入链脲菌素（streptozotocin,STZ）诱导形成的NOD/SCID糖尿病小鼠一侧附睾脂肪垫内,观察血糖变化.结果 hESCs诱导4阶段细胞表达胰高血糖素、胰岛素、Glut-2;共表达PDX-1和C肽;流式鉴定诱导4阶段胰岛素阳性细胞为17.1％;体外检测有葡萄糖刺激的胰岛素释放反应;3阶段及4阶段分化形成的细胞分别植入NOD/SCID 糖尿病小鼠体内可逆转其高血糖至少12周.结论 体外定向诱导hESCs分化形成的胰腺前体细胞及胰岛细胞分别植入NOD/SCID小鼠可逆转其高血糖.     

肠促胰岛素在1型糖尿病中的作用和应用前景

1型糖尿病是由于胰岛β细胞选择性破坏,而引起机体内胰岛素分泌绝对缺乏的一种自身免疫性疾病。肠促胰岛素在2型糖尿病的临床治疗中已经得到证实,但在1型糖尿病的临床应用仍有待评估,胰高血糖素样肽1(GLP-1)通过促进胰岛β细胞分泌胰岛素、抑制胰腺α细胞的胰高血糖素分泌、间接延缓胃排空和降低患者食欲来降低血糖水平,并且LP-1对胰岛β细胞有一定的保护作用。运用肠促胰岛素治疗非肥胖性糖尿病小鼠的研究中证实肠促胰岛素有免疫调节、抗炎性反应及促进胰岛β细胞再生能力,因此极有可能运用肠促胰岛素延缓1型糖尿病发病、阻止病情进展恶化、部分恢复胰岛β细胞分泌胰岛素能力。     

Glucose control of glucagon secretion—‘There’s a brand-new gimmick every year’

Glucagon from the pancreatic α-cells is a major blood glucose-regulating hormone whose most important role is to prevent hypoglycaemia that can be life-threatening due to the brain’s strong dependence on glucose as energy source. Lack of blood glucose-lowering insulin after malfunction or autoimmune destruction of the pancreatic β-cells is the recognized cause of diabetes, but recent evidence indicates that diabetic hyperglycaemia would not develop unless lack of insulin was accompanied by hypersecretion of glucagon. Glucagon release has therefore become an increasingly important target in diabetes management. Despite decades of research, an understanding of how glucagon secretion is regulated remains elusive, and fundamentally different mechanisms continue to be proposed. The autonomous nervous system is an important determinant of glucagon release, but it is clear that secretion is also directly regulated within the pancreatic islets. The present review focuses on pancreatic islet mechanisms involved in glucose regulation of glucagon release. It will be argued that α-cell-intrinsic processes are most important for regulation of glucagon release during recovery from hypoglycaemia and that paracrine inhibition by somatostatin from the δ-cells shapes pulsatile glucagon release in hyperglycaemia. The electrically coupled β-cells ultimately determine islet hormone pulsatility by releasing synchronizing factors that affect the α- and δ-cells.     

STUDY ON INHIBITION OF PANCREATIC EXOCRINE SECRETION BY SOMATOSTATIN IN RATS

We used a potent and specific monocional antibody to somatostatin to test the physiologoic inhibitory role of the tetradecapeptide somatostation on pancreatic secretion, Somatostatlncreased both the total amylase and vofume of pancreatic sectetion. C.hoIecystokirfin-A receptor antagom smabolished the stimulatory ellect of somatostatin Jmmunoneutralization, We conclude that somatotation tccli-tally inhiblts pancreatic secretion in fasted rats via inhibition of the release or action of cholecystokinin.,Furthermore, the source of these paptides is likely islet delta cells and intrapancxeatie neurons, respectively.     

Somatostatin analogue treatment of neuroendocrine tumours.

The long-acting analogues of somatostatin have an established place in the medical treatment of patients with neuroendocrine tumours. They act through binding with specific, high-affinity membrane receptors. Somatostatin analogue therapy is an effective and safe treatment for most growth hormone and thyrothropin-secreting pituitary adenomas. The potential therapeutic consequences of the presence of somatostatin receptors on clinically ''nonfunctioning'' pituitary tumours are still uncertain. Somatostatin analogues are not useful in the treatment of patients with prolactinomas, or adrenocorticotropin (ACTH)-secreting adenomas. However, the somatostatin analogue octreotide suppressed pathological ACTH release in some patients with Nelson''s syndrome and ACTH and cortisol secretion in several patients with Cushing''s syndrome caused by ectopic ACTH secretion. Somatostatin analogues are effective in the sympatomatic treatment of most (metastatic) pancreatic islet cell tumours and most (metastatic) carcinoids. In some of these patients, they also induce tumour stabilisation or reduction. In some patients with (metastatic) medullary thyroid carcinomas, continuous treatment with very high doses of octreotide can be of temporary relief. The clinical effectiveness of somatostatin analogues in patients with small cell lung cancer is currently under investigation. Long-term therapy with somatostatin analogues of catecholamine-secreting (malignant) paragangliomas and phaeochromocytomas has not shown clinical benefits.     

胰腺局部肾素-血管紧张素系统的生理作用

全身肾素-血管紧张素系统(RAS)在调节血压及水、电解质平衡方面起重要作用。而最近发现多种组织、器官中存在局部独立的RAS,在局部自分泌、旁分泌等生理功能方面起不同程度的作用。目前发现在胰腺组织内,包括胰腺腺泡、导管、胰岛、上皮细胞以及星形细胞中存在局部RAS,在生理和包括低氧、胰腺炎、胰岛移植、糖尿病等病理刺激条件下,其表达发生相应改变。RAS在胰腺内、外分泌功能中起重要作用:调节局部血流、导管细胞分泌碳酸氢钠、腺泡细胞分泌消化酶、胰岛β细胞合成及释放胰岛素、δ细胞分泌生长抑素、胰腺细胞增殖和分化。此外,还可能介导氧化应激诱导的细胞炎症、凋亡和纤维化。通过上述影响,胰腺局部RAS在胰腺炎、糖尿病、囊性纤维化及胰腺肿瘤的形成中可能起一定的作用,本文就胰腺局部RAS的生理功能及临床意义进行综述。     

iPLA2在人胰岛β细胞的表达和对胰岛素分泌功能的影响

目的 探讨Ca2+-非依赖性磷酸脂酶A2(iPLA2)在人胰岛的表达及在胰岛素分泌功能中的作用.方法 正常人胰腺组织切片免疫组织化学染色及人胰岛Western印迹方法检测,观察iPLA2在人胰岛中的表达情况;随机分组对照研究iPLA2选择性抑制剂溴烯醇内酯(BEL)对离体人胰岛的葡萄糖刺激引起胰岛素分泌反应的影响.结果 在人胰岛iPLA2高表达,与抗胰岛素染色分布一致,而外分泌腺很少表达;与对照组相比,BEL处理组胰岛素分泌反应明显减弱(P＜0.01),BEL通过抑制iPLA2活性抑制了葡萄糖刺激引起的离体人胰岛胰岛素分泌.结论 iPLA2在人胰岛β细胞高表达并在葡萄糖刺激胰岛β细胞胰岛素分泌过程起到重要的作用.     

ISLET FORMATION AND REGENERATION

INSULIN DEPENDENTdiabetesmellitus(ID DM)occurredinhumanwhenamajorityofβcellsaredestroyed.Itisreportedthatpancreaticstemcellsofpancreaticductintheadultareabletodiffer entiatetoisletcellsafterlong termculture.Pancreaticstem cells,agroupofpluripotentcells,h…     

糖尿病小鼠左肾被膜下胰岛细胞与胰腺外分泌细胞共同移植动物模型的建立

目的：建立糖尿病小鼠左肾被膜下同种异体胰岛细胞与胰腺外分泌细胞共同移植动物模型及探讨胰腺外分泌细胞对胰岛移植物的损伤作用.方法：（1）体内实验：采用胆总管内逆行灌注胶原酶联合淋巴细胞分离液的方法来分离纯化胰岛,人工挑取胰岛细胞并收集胰腺外分泌细胞.链脲佐菌素腹腔注射诱导BALB/C小鼠成为糖尿病小鼠.单纯移植组（n=10）每只小鼠于左肾被膜上极移植胰岛细胞250个,共同移植组（n =10）每只小鼠于左肾被膜上下极同时移植胰岛细胞250个和等体积的胰腺外分泌细胞,持续观测血糖及生命体征变化,1个月后切除左肾并继续检测血糖.（2）体外实验：利用双硫腙对胰岛进行特异性染色来计算胰岛产量及纯度,利用台盼蓝染色鉴定胰岛细胞的活性,以及用葡萄糖刺激胰岛素释放实验来检测胰岛功能.结果：（1）胰岛移植后,单纯移植组及共同移植组血糖均逐步降至正常,共同移植组较单纯移植组血糖恢复正常时间延迟,移植术后第2,3,4,5天,单纯移植组受鼠血糖低于共同移植组,差异有统计学意义（P＜0.05）.切除两组受鼠左肾3d后,两组受鼠血糖均＞21 mmol/L.（2）每只小鼠可获得150～200个高质量胰岛,纯度及活性均高于90％,葡萄糖刺激后胰岛素释放量明显增加（SI=2.90）.结论：（1）成功建立糖尿病小鼠左肾被膜下同种异体胰岛细胞与胰腺外分泌细胞共同移植动物模型.（2）胰腺外分泌细胞与胰岛细胞同时移植会延迟植入胰岛功能恢复正常的时间.     

Pulsatility of insulin release – a clinically important phenomenon

Abstract

The mechanisms and clinical importance of pulsatile insulin release are presented against the background of more than half a century of companionship with the islets of Langerhans. The insulin-secreting β-cells are oscillators with intrinsic variations of cytoplasmic ATP and Ca²⁺. Within the islets the β-cells are mutually entrained into a common rhythm by gap junctions and diffusible factors (ATP). Synchronization of the different islets in the pancreas is supposed to be due to adjustment of the oscillations to the same phase by neural output of acetylcholine and ATP. Studies of hormone secretion from the perfused pancreas of rats and mice revealed that glucose induces pulses of glucagon anti-synchronous with pulses of insulin and somatostatin. The anti-synchrony may result from a paracrine action of somatostatin on the glucagon-producing α-cells. Purinoceptors have a key function for pulsatile release of islet hormones. It was possible to remove the glucagon and somatostatin pulses with maintenance of those of insulin with an inhibitor of the P2Y₁ receptors. Knock-out of the adenosine A₁ receptor prolonged the pulses of glucagon and somatostatin without affecting the duration of the insulin pulses. Studies of isolated human islets indicate similar relations between pulses of insulin, glucagon, and somatostatin as found during perfusion of the rodent pancreas. The observation of reversed cycles of insulin and glucagon adds to the understanding how the islets regulate hepatic glucose production. Current protocols for pulsatile intravenous infusion therapy (PIVIT) should be modified to mimic the anti-synchrony between insulin and glucagon normally seen in the portal blood.     

Abnormal pancreatic glucagon secretion and postprandial hyperglycemia in diabetes mellitus.

Plasma glucose and glucagon responses to standard meals containing carbohydrate, fat, and protein as in normal diets were studied in 12 subjects with insulin-dependent diabetes and 12 normal subjects. Diabetics had two to three times greater glucagon responses than did normal subjects. Fifteen units of insulin injection did not normalize these excessive glucagon responses, although postprandial hyperglycemia was reduced. Infusion of somatostatin at a dosage of 500 mug/hr prevented glucagon responses and diminished postprandial hyperglycemia by 60%. The combination of insulin and somatostatin caused a progressive fall in plasma glucose levels despite meal ingestion. Somatostatin and insulin, administered subcutaneously in the same syringe, also abolished postprandial hyperglycemia. These studies indicate that excessive glucagon secretion participates in the genesis of diabetic postprandial hyperglycemia. Somatostatin, an inhibitor of glucagon secretion, may thus prove useful as an adjunct to insulin in the treatment of diabetes mellitus.     

小鼠实验性糖尿病免疫组织化学观察

用HRP-SPA免疫组织化学方法观察了四氧嘧啶所致小鼠实验性糖尿病胰岛A、B细胞的变化.结果表明,实验性糖尿病小鼠部分胰岛有改变.主要为胰岛形态不规则,边缘不整齐,胰岛细胞排列紊乱,胰岛内有较大空虚部分与胰岛细胞极明显的离散现象,有改变的胰岛中部分胰岛细胞境界不清、边缘不整齐与免疫反应颗粒缺失与消失等变化.     

环孢素A对正常及自发性糖尿病仓鼠胰岛细胞分泌功能的短期影响

目的　探讨环孢素 A( Cs A )对胰岛α、β细胞的作用 ,为临床合理用药提供理论依据。方法　采用改良Kanatsuna及 knudsen柱细胞表面灌注系统 ,动态观察低浓度 ( 2 5～ 10 0 ng/ml) Cs A对正常及自发性糖尿病 ( DM)中国短尾黑线仓鼠离体胰岛α、β细胞分泌功能的短期影响。结果　 DM仓鼠胰岛β细胞无论在静态时或 16.7mm ol/L D-葡萄糖 ( G)刺激下胰岛素 ( Ins)的分泌量均较正常仓鼠明显降低 ( P<0 .0 5 ) ,而静态胰高糖素 ( Glc)分泌量则较正常仓鼠明显增高 ( P<0 .0 5 )。将小剂量 ( 2 5～ 10 0 ng/ml) Cs A加入胰岛细胞中培养 2 4h后 ,培养液 Ins和Glc含量与对照组 (未加 Cs A)相比无统计学差异 ( P>0 .0 5 ) ,但 Cs A处理 2 4h后的正常仓鼠胰岛β细胞对 16.7mm ol/L D-葡萄糖刺激的反应减弱。结论　 DM仓鼠发病可能与胰岛细胞分泌功能异常有关。小剂量 ( 2 5～ 10 0 ng/ml) Cs A对正常及 DM仓鼠离体胰岛α、β细胞分泌功能无明显直接影响。胰岛细胞与 Cs A作用 2 4h后β细胞储备功能降低。 Cs A在体外对 Ins释放的影响 ,除剂量因素外 ,还与作用时间有关     

NOD 小鼠胰岛的分离及其在体内外的生物学特性

目的 建立分离纯化非肥胖性糖尿病(NOD)小鼠胰岛的方法,并对其体内外生物学特性进行研究?方法 采用改良的胶原酶消化结合Ficoll 密度梯度离心方法,分离纯化NOD 小鼠胰岛?应用体外糖刺激实验检测分离纯化的胰岛功能,以及通过监测移植小鼠的血糖?体重变化及糖耐量实验对移植胰岛的体内生物学功能进行分析,并通过HE 染色和免疫荧光染色检测肾被膜下移植胰岛的存活情况?结果 胰岛产率为(116 ±12)个胰岛/胰腺,纯度>90%?体外糖刺激实验结果显示,NOD 小鼠胰岛的糖刺激胰岛素释放水平明显低于KM 小鼠胰岛?胰岛移植实验显示,移植胰岛能有效改善糖尿病小鼠的血糖?体重和糖耐量,但改善作用一般仅能维持2 周左右?HE 染色和免疫荧光染色结果显示,肾被膜下可见胰岛素阳性的胰岛细胞团,并且在残存的移植胰岛细胞团周围存在大量淋巴细胞浸润?结论 通过改良的小鼠胰岛分离方法可由NOD 小鼠分离得到大量较高纯度的胰岛,可用于今后探索如何阻断自身免疫损伤保护移植胰岛的研究?     

单核细胞趋化蛋白-1在非肥胖糖尿病小鼠胰腺中的表达

目的 通过观察单核细胞趋化蛋白-1（Monocyte Chemoattractant Protein-1）在1型糖尿病动物模型NOD小鼠胰腺中的表达，探讨其在1型糖尿病胰岛炎发病机制中的作用。方法 应用免疫组化SABC法和免疫电镜评价MCP-1在NOD小鼠和BALB／C小鼠胰腺中的表达，应用H＆E染色光镜下评价胰岛免疫细胞浸润。结果 免疫组化结果表明：NOD小鼠胰腺中MCP-1呈阳性表达，而对照组无MCP-1表达。免疫电镜进一步显示：MCP-1由胰岛β细胞产生并存在于细胞质中。结论 MCP-1主要由胰岛β细胞产生。MCP-1通过招募单核／巨噬细胞浸润胰岛而在1型糖尿病发病机制中起重要作用。     

Fas-FasL在NOD小鼠胰岛炎中的作用

目的分析Fas-FasL在NOD小鼠胰岛炎中的作用。方法取32只分属不同周龄的雌性NOD小鼠,观察其血糖、胰岛HE染色、免疫组织化学染色———检测胰岛素、CD8、Fas、FasL的表达。在分析NOD小鼠胰岛炎中以胰岛或相关细胞为研究单位,从而减少了混杂因素的影响。结果雌性NOD小鼠自6周龄起出现胰岛炎,其评分逐渐增加(P<0.0005),14周龄出现糖尿病。随着胰岛炎的加重:胰岛素阳性细胞减少(P<0.0005),与胰岛炎评分呈负相关(P<0.05);Fas 胰岛细胞增加(P<0.0005),与评分呈正相关(P<0.01);FasL 胰岛细胞出现并逐渐增加(P<0.0005),与评分呈正相关(P<0.01);浸润细胞表达FasL、CD8,均逐渐增加(P<0.0005)。胰岛细胞的Fas与胰岛素表达之间呈负相关、胰岛素与FasL呈负相关、Fas与FasL呈正相关,浸润细胞的CD8与FasL表达呈正相关,P值均小于0.01。结论在NOD小鼠胰岛炎中,Fas-FasL可能参与β细胞损伤及自身免疫负调节。