T细胞接种对环磷酰胺处理NOD小鼠糖尿病的影响

目的 探讨T细胞接种（TCV）对Ⅰ型糖尿病的预防作用。方法 将6周龄未发病的雌性NOD鼠用4周龄未发病、18周龄新近发病和32周龄发病时间长的NOD鼠脾细胞制得的T细胞疫苗接种,检测TCV对环磷酰胺处理的NOD鼠糖尿病发病率和胰岛炎程度的影响,以及接种后宿主淋巴细胞亚群的变化情况。结论 TCV可以降低糖尿病发病率、减轻胰岛单个核细胞的浸润程度,诱导宿主脾脏CD8^ T细胞百分比升高、CD4^＋／CD8^ 比值和IL－2R^ 细胞下降,胸腺CD4^- CD8^-单阳性细胞百分比升高。结论 TCV可降低宿主对自身免疫的反应性,这种作用可能与宿主脾脏、胸腺淋巴细胞亚群的变化和对糖尿病的预防效应有关。     

茶多糖对NOD小鼠1型糖尿病的预防作用

目的探讨茶多糖（TPS）对非肥胖糖尿病（NOD）小鼠1型糖尿病（DM）的预防作用。方法比较TPS预免疫组和生理盐水（NS）对照组NOD小鼠1型DM的发病率、血清C肽和谷氨酸脱羧酶抗体水平、胰岛组织病理学和免疫组化、脾脏T细胞亚群比例。结果TPS预免疫组与NS组比较，DM发病率显著降低，血清C肽水平显著增高，胰岛炎症程度减轻，CD8T细胞亚群比例显著增高，CD4／CD8比例显著降低。结论早期应用茶多糖预免疫可以预防或延缓NOD小鼠1型糖尿病的发生。     

己酮可可碱预防NOD鼠1型糖尿病的机理研究

目的 探讨己酮可可碱（Pentoxifylline,PTX)对非肥胖糖尿病（NOD）小鼠1型糖尿病发病率，胰岛素的影响及其机制。方法 采用动物模型NOD鼠，注射环磷酰胺（CP）加速其发病。给PTX药物后计算糖尿病发病率，HE染色观察胰岛炎，并用逆转录（RT）PCR法检测脾细胞干扰素γ（IFN－γ），肿瘤坏死因子α（TNF－α），白介素10（IL－10）mRNA的表达。结果 PTX组糖尿病发生率（30．00％）明显低于对照组（67．86％）（P＜0．1）；胰岛炎程度也明显减轻（P＜0．001）；脾细胞IFN－γ，TNF－αmRNA的表达较对照组明显降低（P＜0．05），IL－10mRNA的表达无明显改变。结论 PTX可预防NOD鼠发生糖尿病，其机制可能与纠正Th1与Th2型细胞因子比例失衡有关。     

系统性炎症是否与胰岛自身免疫相关

1型糖尿病（T1DM）是一种T细胞介导的自身免疫性疾病.在T1DM中,炎症反应的许多组分,包括CD4＋及CD8＋T细胞、巨噬细胞、树突状细胞、NK细胞、细胞因子、自由氧化基、一氧化氮分子等都参与了对β细胞的破坏.胰岛浸润性CD8＋T细胞出现表示存在胰岛炎,提示MHC-I类限制性T细胞可能是自身免疫糖尿病发展的重要原因.NOD鼠研究显示胰岛素是自身反应性CD8＋T细胞的主要靶抗原.此外,NOD鼠研究还提示经过一段约7周的前胰岛炎时期,局部炎症最终将发展成自身免疫糖尿病.     

己酮可可碱对NOD小鼠1型糖尿病的影响

目的 探讨己酮可可碱（pentoxifyline,PTX)对NOD（non-obese diabetic)小鼠1型糖尿病的影响及其机制。方法 采用动物模型NOD鼠，PTX处理后检测血糖、尿糖及糖尿病发病率，HE染色观察胰岛炎，并用RT－PCR法检测胰腺干扰素γ（IFN-γ）、肿瘤坏死因子α（TNF－α）、白介素10（IL－10）mRNA的表达。结果 PTX组糖尿病发生率(30%)低于对照组（67．9％），P＜0．01；胰岛炎程度也减轻P＜0．001；胰腺IFN－γ、TNF－α mRNA的表达较对照组降低，P＜0．05；3项变化均具显著性。而IL－10 mRNA的表达则无显著改变。结论 PTX可预防NOD小鼠发生糖尿病，其机制可能与纠正Th1与Th2型细胞因子比例失衡有关。     

吡格列酮对NOD鼠糖尿病的预防作用及其机制探讨

目的探讨吡格列酮（PIO）对NOD鼠糖尿病发病率和胰岛炎的影响及其作用机制。方法4周龄NOD雌鼠随机分为2组，分别摄食0．02％PIO混合饲料（PIO，n=26）和普通饲料（对照组，n=25），观察30周龄时的糖尿病累积发病率。各组另取12周龄未患病NOD鼠（n=15）胰腺H～E染色观察胰岛炎；ELISA法测血清、脾细胞培养上清干扰素γ（IFN-γ）和白细胞介素4（IL～4）水平；RT-PCR检测脾脏IL-4、IFN～γmRNA的表达水平。结果30周龄时，PIO组发病率较对照组明显降低（P〈0．05）。12周龄时，PIO组胰岛炎平均积分低于对照组（P〈0．05）；血清、脾上清IL～4水平，脾脏IL-4mRNA表达水平显著性高于对照组（P〈0．05）；PIO血清、脾上清IL-4／IFN-γ比值水平高于对照组（P〈0．05）。结论PIO通过上调IL～4水平，促使免疫平衡向Th2方向偏移，从而使NOD鼠胰岛炎减轻，而在一定程度上预防和延缓NOD鼠糖尿病的发生。     

NOD/Lt小鼠腹腔注射1,25-(OH)2D3诱发免疫耐受的机制

目的　探讨1, 25 (OH)2D3 阻断NOD/Lt小鼠发生1型糖尿病的免疫机制。方法　60只4周龄NOD/Lt小鼠(25g)分为2组,组1隔天腹腔注射1, 25 (OH)2D3 (5μg/kg),组2腹腔注射花生油作为对照。所有小鼠在第1天和第15天腹腔注射环磷酰胺以加速糖尿病的发生,第30天处死并观察。免疫组化检测Bcl 2,Bax在胰岛和T淋巴细胞的表达;流式细胞仪检测T淋巴细胞亚群分布及凋亡率;RT PCR检测Th1 /Th2 亚群的漂移。结果　1, 25 (OH)2D3 处理组糖尿病发病率下降,脾T淋巴细胞凋亡率增加〔(55. 8±5. 4)% vs(28. 9±3. 6)%,P<0. 05〕;CD4 Th2 亚群增加(IL 4和IL 10mRNA显著增加, P<0. 01)。结论　1, 25 (OH)2D3 通过加速T淋巴细胞的凋亡以减轻细胞免疫反应并最终延缓胰岛β细胞的凋亡,并使CD4 Th1 亚群向CD4 Th2 亚群漂移,导致NOL/Lt小鼠1型糖尿病发病率下降。     

成人隐匿性自身免疫性糖尿病患者外周血T细胞亚群变化及意义

目的探讨T细胞亚群变化在成人隐匿性自身免疫性糖尿病（LADA）发病中的作用。方法应用流式细胞技术测定24例LADA患者（LADA组）、18例速发性1型糖尿病（T1DM）者（T1DM组）及20例健康人（对照组）T细胞表面分子CD4^＋、CD8^＋,以百分比表示各表面分子阳性T细胞占外周血淋巴细胞的比例;测定胰岛功能相关指标[空腹C肽（FC-P）和糖负荷后2h C肽（2h—CP）、胰岛素释放指数（HOMA-IS）]的相关性。结果LADA与T1DM组C1MT细胞、CD4^＋／CD8^＋值明显高于对照组（P〈0．01）,LADA与T1DM元显著差异。CD4^＋T细胞2h-CP呈明显负相关。结论T淋巴细胞亚群失衡参与介导了胰岛β细胞的损伤和LADA的发生,     

成人隐匿性自身免疫性糖尿病患者T细胞亚群变化与胰岛β细胞功能相关性研究

目的观察成人隐匿性自身免疫性糖尿病（LADA）患者T细胞亚群的变化,及其与胰岛β细胞功能的相关性。方法LADA组24例,经典1型糖尿病（T1DM）18例,健康对照（NC）组20例,应用流式细胞技术测定三组入选者T细胞表面分子CD4、CD8,以百分比表示各表面分子阳性T细胞占外周血淋巴细胞的比例。测空腹C肽（FC-P）和糖负荷后2h C肽（2hC-P）。测空腹血糖、空腹胰岛素、应用HOMA公式计算胰岛素敏感指数（HOMA-IS）。结果LADA与T1DM组CD4^＋T细胞、CD4^＋／CD8^＋比值明显高于NC组（P〈0．01）,LADA与TIDM对比无统计学差异。CD4^＋T细胞与反映胰岛功能2hC-P呈明显的负相关。结论T淋巴细胞亚群失衡参与并介导了胰岛β细胞的损伤和LADA的发生。     

百令胶囊对2型糖尿病肾病患者细胞免疫功能的影响

目的　探讨百令胶囊对2型糖尿病肾病患者外周血淋巴细胞亚群分布的影响。方法　108例患者随机分为治疗组和对照组,每组54例,另选择40例健康体检者作为健康组。对照组予常规治疗,治疗组加服百令胶囊,12周为一疗程。测定主要生物化学指标,流式细胞术检测患者T细胞（CD3＋、CD3＋CD4＋、CD3＋CD8＋）、B细胞（CD3－CD19＋）、NK细胞（CD3－CD16＋CD56＋）、NKT细胞（CD3＋CD16＋CD56＋）分布水平,并与健康组比较。结果　两组治疗后血清胱抑素C（CysC）、24　h尿蛋白定量显著降低（P<0.05）,且治疗组降低更为明显（P<0.05）。治疗前两组患者淋巴细胞亚群分布与健康组相比均有显著性差异（P<0.05）,即存在细胞免疫功能紊乱;治疗后,对照组淋巴细胞亚群分布无明显改变,治疗组CD3＋T细胞亚群、CD3＋CD4＋T细胞亚群和CD3＋CD8＋T细胞亚群、CD3－CD16＋CD56＋NK细胞亚群及CD3＋CD16＋CD56＋NKT细胞亚群比例上升,CD3－CD19＋B细胞亚群比例下降,CD4＋/CD8＋比值明显降低（P<0.05）,且与对照组相比均有显著性差异（P<0.05）。结论　百令胶囊可明显改善2型糖尿病肾病患者细胞免疫功能紊乱。     

Double deficiency in IL-17 and IFN-γ signalling significantly suppresses the development of diabetes in the NOD mouse

Aims/hypothesis

T helper type (Th) 17 cells have been shown to play important roles in mouse models of several autoimmune diseases that have been classified as Th1 diseases. In the NOD mouse, the relevance of Th1 and Th17 is controversial, because single-cytokine-deficient NOD mice develop diabetes similarly to wild-type NOD mice.

Methods

We studied the impact of IL-17/IFN-γ receptor double deficiency in NOD mice on the development of insulitis/diabetes compared with IL-17 single-deficient mice and wild-type mice by monitoring diabetes-related phenotypes. The lymphocyte phenotypes were determined by flow cytometric analysis.

Results

IL-17 single-deficient NOD mice showed delayed onset of diabetes and reduced severity of insulitis, but the cumulative incidence of longstanding diabetes in the IL-17-deficient mice was similar to that in wild-type mice. The IL-17/IFN-γ receptor double-deficient NOD mice showed an apparent decline in longstanding diabetes onset, but not in insulitis compared with that in the IL-17 single-deficient mice. We also found that double-deficient NOD mice had a severe lymphopenic phenotype and preferential increase in regulatory T cells among CD4⁺ T cells compared with the IL-17 single-deficient mice and wild-type NOD mice. An adoptive transfer study with CD4⁺CD25^? T cells from young non-diabetic IL-17 single-deficient NOD mice, but not those from older mice, showed significantly delayed disease onset in immune-deficient hosts compared with the corresponding wild-type mice.

Conclusions/interpretation

These results indicate that IL-17/Th17 participates in the development of insulitis and that both IL-17 and IFN-γ signalling may synergistically contribute to the development of diabetes in NOD mice.     

联合注射自身胰岛细胞瘤相关抗原2基因疫苗预防NOD小鼠自身免疫性糖尿病

目的 探讨自身抗原基因疫苗胰岛素瘤相关蛋白-2（pIA-2）以及分子免疫佐剂白细胞介素-4/单核细胞趋化因子-1（pIL-4/MCP-1）对糖尿病前期NOD小鼠发生自身免疫性糖尿病的预防作用.方法 利用分子克隆技术构建pIA-2自身抗原基因疫苗,将4～5周龄NOD小鼠分为pIA-2治疗组（n=5）、pIL-4/MCP-1治疗组（n=5）、联合治疗组（n=5）及对照组（n=5）,分别注射pIA-2、pIL-4/MCP-1、pIA-2联合pIL-4/MCP-1、增强型绿色荧光蛋白（pEGFP）,免疫结束后观察24周,比较各组糖尿病发病情况和胰岛炎的程度,并用RT-PCR方法和免疫组化法检测质粒在注射部位和胰岛的表达.两样本间均数的比较用t检验,率的比较用x2检验进行统计.结果 单用pIA2或pIL-4/MCP-1治疗的NOD小鼠发病与对照组相比无显著改善;联合应用该两种质粒的NOD小鼠在观察期内未发病.RT-PCR检测结果显示免疫结束后2周,注射部位肌细胞中均有胰岛细胞瘤相关抗原2（IA-2）及白细胞介素-4（IL-4）表达.免疫组化法发现,免疫结束后2周,pIA-2注射组小鼠胰岛的IA-2表达量增加;IL-4在胰岛上可见少量表达.免疫结束后观察24周,检测各组的胰岛炎发生率,对照组、pIA2组、pIL-4/MCP-1组、pIA2＋pIL-4/MCP-1组中无胰岛炎的发生率分别为4.2%（1/24）、5%（1/20）、0（0.0）、62.5%（15/24）,外周性胰岛炎发生率分别为12.5%（3/24）、10%（2/20）、5%（1/20）、29%（7/24）,中心性胰岛炎发生率（＜50%、＞50%）分别为[50%（12/24）,33.3%（8/24）]、[40%（8/20）,45%（9/20）]、[45%（9/20）,50%（10/20）]、[4.2%（1/24）,4.2%（1/24）].和对照组相比,联合治疗组中不发生胰岛炎的比率显著升高（x^2=18.38,P＜0.01）,发生中心性胰岛炎的比率显著降低（x^2=11.68,P＜0.001）,其余各组和对照组相比胰岛炎的发生比率无显著差异.以免疫组化法检测NOD小鼠胰岛内IA-2、IL-4的表达,显示免疫注射组IA-2、IL-4表达较对照组增强.结论 联合应用pIA-2及pIL-4/MCP-1基因疫苗提前免疫胰岛炎前期的NOD小鼠可抑制和延缓糖尿病的发生.     

Germ line deletion of the CD1 locus exacerbates diabetes in the NOD mouse

Quantitative and qualitative defects in CD1-restricted natural killer T cells have been reported in several autoimmune-prone strains of mice, including the nonobese diabetic (NOD) mouse. These defects are believed to be associated with the emergence of spontaneous autoimmunity. Here we demonstrate that both CD1d-null NOD and CD1d-null NOD/BDC2.5 T cell receptor transgenic mice have an accelerated onset and increased incidence of diabetes when compared with CD1d(+/-) and CD1d(+/+) littermates. The acceleration of disease did not seem to result from changes in the T helper (Th)1/Th2 balance because lymphocytes purified from lymphoid organs and pancreatic islets of wild-type and CD1d-null mice secreted equivalent amounts of IFN-gamma and IL-4 after stimulation. In contrast, the pancreata of CD1d-null mice harbored significantly higher numbers of activated memory T cells expressing the chemokine receptor CCR4. Notably, the presence of these T cells was associated with immunohistochemical evidence of increased destructive insulitis. Thus, CD1d-restricted T cells are critically important for regulation of the spontaneous disease process in NOD mice.     

Beta cells cannot directly prime diabetogenic CD8 T cells in nonobese diabetic mice

Type 1 diabetes (T1D) is caused by the destruction of insulin-producing islet beta cells. CD8 T cells are prevalent in the islets of T1D patients and are the major effectors of beta cell destruction in nonobese diabetic (NOD) mice. In addition to their critical involvement in the late stages of diabetes, CD8 T cells are implicated in the initiation of disease. NOD mice, in which the beta2-microglobulin gene has been inactivated by gene targeting (NOD.beta2M-/-), have a deficiency in CD8 T cells and do not develop insulitis, which suggests that CD8 T cells are required for the initiation of T1D. However, neither in humans nor in NOD mice have the immunological requirements for diabetogenic CD8 T cells been precisely defined. In particular, it is not known in which cell type MHC class I expression is required for recruitment and activation of CD8 T cells. Here we have generated transgenic NOD mice, which lack MHC class I on mature professional antigen-presenting cells (pAPCs). These "class I APC-bald" mice developed periislet insulitis but not invasive intraislet insulitis, and they never became diabetic. Recruitment to the islet milieu does not therefore require cognate interaction between CD8 T cells and MHC class I on mature pAPCs. Conversely, such an interaction is critically essential to allow the crucial shift from periislet insulitis to invasive insulitis. Importantly, our findings demonstrate unequivocally that CD8 T cells cannot be primed to become diabetogenic by islet beta cells alone.     

Functional deficiencies of granulocyte-macrophage colony stimulating factor and interleukin-3 contribute to insulitis and destruction of beta cells

The pathogenesis of type 1 diabetes (T1D) involves the immune-mediated destruction of insulin-producing beta cells in the pancreatic islets of Langerhans. Genetic analysis of families with a high incidence of T1D and nonobese diabetic (NOD) mice, a prototypical model of the disorder, uncovered multiple susceptibility loci, although most of the underlying immune defects remain to be delineated. Here we report that aged mice doubly deficient in granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) manifest insulitis, destruction of insulin-producing beta cells, and compromised glucose homeostasis. Macrophages from mutant mice produce increased levels of p40 after LPS stimulation, whereas concurrent ablation of interferon-gamma (IFN-gamma) ameliorates the disease. The administration of antibodies that block cytotoxic T lymphocyte associated antigen-4 (CTLA-4) to young mutant mice precipitates the onset of insulitis and hyperglycemia. These results, together with previous reports of impaired hematopoietic responses to GM-CSF and IL-3 in patients with T1D and in NOD mice, indicate that functional deficiencies of these cytokines contribute to diabetes.     

The CD19 signalling molecule is elevated in NOD mice and controls type 1 diabetes development

Aims/hypothesis

Type 1 diabetes is characterised by early peri-islet insulitis and insulin autoantibodies, followed by invasive insulitis and beta cell destruction. The immunological events that precipitate invasive insulitis are not well understood. We tested the hypothesis that B cells in diabetes-prone NOD mice drive invasive insulitis through elevated expression of CD19 and consequent enhanced uptake and presentation of beta cell membrane-bound antigens to islet invasive T cells.

Methods

CD19 expression and signalling pathways in B cells from NOD and control mice were compared. Expansion of CD8⁺ T cells specific for insulin and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP) were compared in CD19-deficient and wild-type NOD mice and this was correlated with insulitis severity. The therapeutic potential of anti-CD19 treatment during the period of T cell activation was assessed for its ability to block invasive insulitis.

Results

CD19 expression and signalling in B cells was increased in NOD mice. CD19 deficiency significantly diminished the expansion of CD8⁺ T cells with specificity for the membrane-bound beta cell antigen, IGRP. Conversely the reduction in CD8⁺ T cells with specificity for the soluble beta cell antigen, insulin, was relatively small and not significant.

Conclusions/interpretation

Elevated CD19 on NOD B cells promotes presentation of the membrane-bound antigen, IGRP, mediating the expansion of autoreactive T cells specific for antigens integral to beta cells, which are critical for invasive insulitis and diabetes. Downregulating the CD19 signalling pathway in insulin autoantibody-positive individuals before the development of type 1 diabetes may prevent expansion of islet-invasive T cells and preserve beta cell mass.     

An update on cytokines in the pathogenesis of insulin-dependent diabetes mellitus

Correlation studies between cytokines expressed in islets and autoimmune diabetes development in NOD mice and BB rats have demonstrated that β-cell destructive insulitis is associated with increased expression of proinflammatory cytokines (IL-1, TNFα, and IFNα) and type 1 cytokines (IFNγ, TNFβ, IL-2 and IL-12), whereas non-destructive (benign) insulitis is associated with increased expression of type 2 cytokines (IL-4 and IL-10) and the type 3 cytokine (TGFβ). Cytokines (IL-1, TNFα, TNFβ and IFNγ) may be directly cytotoxic to β-cells by inducing nitric oxide and oxygen free radicals in the β-cells. In addition, cytokines may sensitize β-cells to T-cell-mediated cytotoxicity in vivo by upregulating MHC class I expression on the β-cells (an action of IFNγ), and inducing Fas (CD95) expression on β-cells (actions of IL-1, and possibly TNFα and IFNγ). Transgenic expression of cytokines in β-cells of non-diabetes-prone mice and NOD mice has suggested pathogenic roles for IFNα, IFNγ, IL-2 and IL-10 in insulin-dependent diabetes mellitus (IDDM) development, and protective roles for IL-4, IL-6 and TNFα. Systemic administrations of a wide variety of cytokines can prevent IDDM development in NOD mice and/or BB rats; however, a given cytokine may retard or accelerate IDDM development, depending on the dose and frequency of administration, and the age and the diabetes-prone animal model studied (NOD mouse or BB rat). Islet-reactive CD4⁺ T-cell lines and clones that adoptively transfer IDDM into young NOD mice have a Th1 phenotype (IFNγ-producing), but other islet-specific Th1 clones that produce TGFβ can adoptively transfer protection against IDDM in NOD mice. NOD mice with targeted deletions of IL-12 and IFNγ genes still develop IDDM, albeit delayed and slightly less often. In contrast, post-natal deletions of IL-12 and IFNγ, also IL-1, TNFα, IL-2, and IL-6—by systemic administrations of neutralizing antibodies, soluble receptors and receptor antagonists, and receptor-targeted cytotoxic drugs—significantly decrease IDDM incidence in NOD mice and/or BB rats. These cytokine deletion studies have provided the best evidence for pathologic roles for proinflammatory cytokines (IL-1, TNFα, and IL-6) and type 1 cytokines (IFNγ, IL-2 and IL-12) in IDDM development. © 1998 John Wiley & Sons, Ltd.     

白细胞介素17介导致糖尿病性T细胞诱导的NOD小鼠糖尿病的发生

目的 研究白细胞介素17(IL-17)在致糖尿病性BDC2.5 T细胞转移性糖尿病发病中的作用.方法 通过注射转基因IL-17 BDC2.5 T细胞(IL-17组,n=6)、IL-17 siRNA BDC2.5 T细胞(silL-17组,n=5),观察高表达和低/无表达IL-17转基因BDC2.5 T细胞对NOD.scid小鼠转移性糖尿病的影响,进行小鼠胰岛组织学鉴定、脾脏和胰腺淋巴结染色和血浆细胞因子测定.非转基因BDC2.5 T细胞注射为对照组(n=8).结果 在观察期内,IL-17组小鼠全部发生糖尿病,而silL-17组和对照组则无一例发病.胰腺病理HE染色显示IL-17组小鼠出现严重的胰岛炎,胰岛受到破坏,结构模糊不清;而silL-17组小鼠胰腺仅表现为轻、中度胰岛炎,可见胰岛内散在的细胞浸润,胰岛组织结构基本完整,细胞形态正常.小鼠脾脏和淋巴结染色显示,IL-17组小鼠脾脏和胰腺淋巴结中CD11c+/CD11b+的树突细胞增殖显著高于silL-17组和对照组(均P＜0.01),且胰腺淋巴结中该细胞增殖显著高于脾脏.IL-17组小鼠血浆IL-17、肿瘤坏死因子α、γ-干扰素和白细胞介素6水平均显著高于siIL-17组和对照组(均P＜0.01),后两组间差异无统计学意义(P＞0.05).结论 BDC2.5 T细胞的IL-17高表达可显著加速NOD.scid小鼠发生转移性糖尿病,且与宿主树突细胞增殖和在胰腺淋巴结局部的聚集以及多种细胞因子作用有密切关系.     

Prevention of cyclophosphamide-induced accelerated diabetes in the NOD mouse by nicotinamide or a soy protein-based infant formula

Spontaneous diabetes in the NOD mouse can be prevented by nicotinamide or by an infant formula diet in which the protein source is replaced with casein hydrolysate (Pregestimil) or soy protein (Prosobee). NOD mice maintained on the standard diet (chow and water) and given cyclophosphamide (Cy) at day 95 develop accelerated and synchronised diabetes within 14 days. Here, we compared the ability of oral nicotinamide or Prosobee, either given alone or concurrently, from weaning, in preventing diabetes in the Cy model. The resulting insulitis and the expression of intra-islet inducible nitric oxide synthase (iNOS) were examined at days 0, 4, 7, 11 and 14 following Cy administration. Intra-islet CD4 and CD8 cells and macrophages were also enumerated at day 11. In mice given the standard diet and injected with Cy at day 95 (group 5), diabetes developed in 7/11 mice, 14 days later. Mice exposed to oral nicotinamide (group 2), Prosobee (group 3) or both (group 4), did not develop the disease during this period and until a further 30 days (p = 0.03). In mice exposed to the standard diet and without Cy treatment (group 1) the insulitis scores increased slowly until day 11 and then declined slightly at day 14 whereas mice exposed to the same diet but given Cy at day 95, showed a sharp decline at day 4 followed by a rapid increase between day 7-14. However, in mice given either nicotinamide, Prosobee or both, the insulitis scores at most time-points were generally lower than in Cy-treated animals on the standard diet. In the latter group, CD4 and CD8 cells and macrophages were also higher at day 11 than all other 4 groups (CD4: p < 0.05; CD8: p< 0.05; macrophages: p<0.0001). The number of iNOS labelled cells increased progressively in mice on the standard diet and given Cy and were significantly higher at days 4, 7 and 11 than in the 3 dietary groups. Thus, oral nicotinamide or Prosobee, either alone or together, prevents Cy induced diabetes in the NOD mouse. The protective diets suppress Cy-induced intra-islet immune cell influx and iNOS expression.