Reversal of autoimmune diabetes by restoration of antigen-specific tolerance using genetically modified Lactococcus lactis in mice

Current interventions for arresting autoimmune diabetes have yet to strike the balance between sufficient efficacy, minimal side effects, and lack of generalized immunosuppression. Introduction of antigen via the gut represents an appealing method for induction of antigen-specific tolerance. Here, we developed a strategy for tolerance restoration using mucosal delivery in mice of biologically contained Lactococcus lactis genetically modified to secrete the whole proinsulin autoantigen along with the immunomodulatory cytokine IL-10. We show that combination therapy with low-dose systemic anti-CD3 stably reverted diabetes in NOD mice and increased frequencies of local Tregs, which not only accumulated in the pancreatic islets, but also suppressed immune response in an autoantigen-specific way. Cured mice remained responsive to disease-unrelated antigens, which argues against excessive immunosuppression. Application of this therapeutic tool achieved gut mucosal delivery of a diabetes-relevant autoantigen and a biologically active immunomodulatory cytokine, IL-10, and, when combined with a low dose of systemic anti-CD3, was well tolerated and induced autoantigen-specific long-term tolerance, allowing reversal of established autoimmune diabetes. Therefore, we believe this method could be an effective treatment strategy for type 1 diabetes in humans.     

Recovery from diabetes in mice by beta cell regeneration

The mechanisms that regulate pancreatic beta cell mass are poorly understood. While autoimmune and pharmacological destruction of insulin-producing beta cells is often irreversible, adult beta cell mass does fluctuate in response to physiological cues including pregnancy and insulin resistance. This plasticity points to the possibility of harnessing the regenerative capacity of the beta cell to treat diabetes. We developed a transgenic mouse model to study the dynamics of beta cell regeneration from a diabetic state. Following doxycycline administration, transgenic mice expressed diphtheria toxin in beta cells, resulting in apoptosis of 70%-80% of beta cells, destruction of islet architecture, and diabetes. Withdrawal of doxycycline resulted in a spontaneous normalization of blood glucose levels and islet architecture and a significant regeneration of beta cell mass with no apparent toxicity of transient hyperglycemia. Lineage tracing analysis indicated that enhanced proliferation of surviving beta cells played the major role in regeneration. Surprisingly, treatment with Sirolimus and Tacrolimus, immunosuppressants used in the Edmonton protocol for human islet transplantation, inhibited beta cell regeneration and prevented the normalization of glucose homeostasis. These results suggest that regenerative therapy for type 1 diabetes may be achieved if autoimmunity is halted using regeneration-compatible drugs.     

CD4+ beta islet cell-reactive T cell clones that suppress autoimmune diabetes in nonobese diabetic mice

We report the isolation of a panel of CD4+ T helper type 1 autoreactive T cell clones from the spleen of unprimed nonobese diabetic mice, a murine model of human insulin-dependent diabetes mellitus. The T cell clones express a diverse repertoire of T cell receptors, three of which recognize beta islet cell autoantigen(s). The islet cell-reactive T cell clones inhibit adoptive transfer of insulin-dependent diabetes mellitus and intraislet lymphocytic infiltration. The protective capacity of the T cell clones correlates with their ability to produce a novel immunoregulatory activity that potently inhibits in vitro allogeneic mixed lymphocyte reaction. The partially purified activity significantly inhibited the adoptive transfer of diabetes. Our work provides evidence in support of the existence of T helper type 1, CD4+ T cells reactive to beta islet cell autoantigens that have acquired a protective instead of a diabetogenic effector function. These T cells mediate their protective action in part by production of an immunoregulatory activity capable of down-regulating immune responses, and they are likely to represent a population of regulatory T cells that normally plays a role in maintaining peripheral tolerance.     

肝源性糖尿病患者胰岛β细胞功能和胰岛素抵抗及临床意义

目的探讨肝源性糖尿病患者胰岛β细胞功能和胰岛素抵抗的特征。方法对肝源性糖尿病(HD)26例,2型糖尿病(T2DM)30例,正常对照(NC)22例,行口服葡萄糖耐量试验,测定0 min、30 min、60 min、120 min、180 min血糖及胰岛素水平。计算稳态模式评估法的胰岛β细胞基础分泌指数(HOMA-β)、早相胰岛素分泌指数(△I30/△G30)、晚相胰岛素分泌指数(AUCI30-120/AUCG30-120),评估胰岛β细胞功能;计算空腹血糖与空腹胰岛素比值(PFG/FINS)、稳态模式评估法的胰岛抵抗指数(HOMA-IR)、肝脏胰岛素抵抗指数(HIR)及Matsuda指数(MSI),评估胰岛素抵抗。结果 HD组的HOMA-β和AUCI30-120/AUCG30-120高于T2DM组(P<0.05),与NC组无差异(P>0.05);HD组和T2DM组的△I30/△G30低于NC组(P<0.05),HD组和T2DM组无差异(P>0.05);HD组和NC组的PFG/FINS低于T2DM组(P<0.05),HD组和NC组的PFG/FINS和HOMA-IR无差异(P>0.05);HD组和T2DM组的HIR高于NC组(P<0.05),HD组和T2DM组无差异(P>0.05);HD组和T2DM组的MSI低于NC组(P<0.05),HD组和T2DM组无差异(P>0.05)。结论 HD患者基础胰岛素分泌接近正常人,以早相胰岛素分泌损害及餐后胰岛素抵抗为主。     

T cell receptor beta chain gene rearrangement shared by murine T cell lines derived from a site of autoimmune inflammation.

Advances in our understanding of the structure and molecular biology of the T lymphocyte antigen-receptor have now made it feasible to study human autoimmune diseases using new approaches. One such approach involves cloning of T cells from sites of autoimmune pathology followed by identification of putative disease-related T cell oligoclonality at the level of the T cell receptor gene rearrangements. We have now tested the feasibility of this approach in an animal model of autoimmunity, murine experimental allergic encephalomyelitis (EAE). Spinal cord-derived, self (murine) myelin basic protein (MBP)-reactive T cell lines and sublines were analyzed at the level of their receptor beta chain rearrangements using Southern blots. We now report that the MBP-reactive T cell lines and sublines derived from the spinal cords of four of five SJL/J mice with EAE share a 14.5-kb rearranged T cell receptor beta 1 band on Southern blots. A spinal cord-derived T cell line that was reactive to purified protein derivative of tuberculin (PPD), several lymph node-derived ovalbumin- and PPD-reactive T cell lines, as well as one MBP-reactive spinal cord-derived T cell line did not share this 14.5-kb rearranged beta 1 band. These results suggest that analysis of the antigen receptors used by T cells cloned from sites of inflammation may be a useful initial approach for identifying pathogenetically relevant T cells in the study of certain human autoimmune diseases.     

GLUT-2 function in glucose-unresponsive beta cells of dexamethasone-induced diabetes in rats.

Spontaneous and dexamethasone-induced noninsulin-dependent diabetes mellitus (NIDDM) in rats is associated with loss of glucose-stimulated insulin secretion (GSIS) and a reduction in both GLUT-2-positive beta cells and high Km glucose transport. To determine if the chronology and correlation of these abnormalities is consistent with a causal relationship, Zucker (fa/fa) rats were studied longitudinally before and during 10 d of dexamethasone-induced (0.4 mg/kg per d i.p.) NIDDM. Within 24 h of dexamethasone treatment blood glucose rose and GSIS declined, becoming paradoxically negative (-87 +/- 12 microU/ml per min) on day 10. Blood glucose was negatively correlated with GSIS (r = -0.92; P < 0.001). 3-0-methyl-D-glucose (3MG) transport was unchanged at 12 h, 23% below normal on day 1, and declined further to a nadir 59% below normal. The GLUT-2-positive beta cell area did not decline until 48 h, reaching a nadir of 35% of normal at 10 d. The area of GLUT-2-positive beta cells was correlated with GSIS (r = 0.77; P < 0.005). We conclude that the chronology and correlation between GSIS loss and hyperglycemia is consistent with a cause-effect relationship, but that the subtotal impairment in glucose transport by itself cannot explain the total loss of GSIS if one assumes that normal beta cells are functionally homogenous.     

Intraislet release of interleukin 1 inhibits beta cell function by inducing beta cell expression of inducible nitric oxide synthase

Cytokines, released in and around pancreatic islets during insulitis, have been proposed to participate in beta-cell destruction associated with autoimmune diabetes. In this study we have evaluated the hypothesis that local release of the cytokine interleukin 1 (IL-1) by nonendocrine cells of the islet induce the expression of inducible nitric oxide synthase (iNOS) by beta cells which results in the inhibition of beta cell function. Treatment of rat islets with a combination of tumor necrosis factor (TNF) and lipopolysaccharide (LPS), conditions known to activate macrophages, stimulate the expression of iNOS and the formation of nitrite. Although TNF+LPS induce iNOS expression and inhibit insulin secretion by intact islets, this combination does not induce the expression of iNOS by beta or alpha cells purified by fluorescence activated cell sorting (Facs). In contrast, IL-1 beta induces the expression of iNOS and also inhibits insulin secretion by both intact islets and Facs-purified beta cells, whereas TNF+LPS have no inhibitory effects on insulin secretion by purified beta cells. Evidence suggests that TNF+LPS inhibit insulin secretion from islets by stimulating the release of IL-1 which subsequently induces the expression of iNOS by beta cells. The IL-1 receptor antagonist protein completely prevents TNF+LPS-induced inhibition of insulin secretion and attenuates nitrite formation from islets, and neutralization of IL-1 with antisera specific for IL-1 alpha and IL-1 beta attenuates TNF+LPS-induced nitrite formation by islets. Immunohistochemical localization of iNOS and insulin confirm that TNF+LPS induce the expression of iNOS by islet beta cells, and that a small percentage of noninsulin-containing cells also express iNOS. Local release of IL-1 within islets appears to be required for TNF+LPS-induced inhibition of insulin secretion because TNF+LPS do not stimulate nitrite formation from islets physically separated into individual cells. These findings provide the first evidence that a limited number of nonendocrine cells can release sufficient quantities of IL-1 in islets to induce iNOS expression and inhibit the function of the beta cell, which is selectively destroyed during the development of autoimmune diabetes.     

Islet beta cell failure in type 2 diabetes

The major focus of this Review is on the mechanisms of islet beta cell failure in the pathogenesis of obesity-associated type 2 diabetes (T2D). As this demise occurs within the context of beta cell compensation for insulin resistance, consideration is also given to the mechanisms involved in the compensation process, including mechanisms for expansion of beta cell mass and for enhanced beta cell performance. The importance of genetic, intrauterine, and environmental factors in the determination of "susceptible" islets and overall risk for T2D is reviewed. The likely mechanisms of beta cell failure are discussed within the two broad categories: those with initiation and those with progression roles.     

Depletion of alpha/beta T cells by a monoclonal antibody against the alpha/beta T cell receptor suppresses established adjuvant arthritis, but not established collagen-induced arthritis in rats

The effects of treatment with a monoclonal antibody (R73 mAb) against T cell receptor alpha/beta (TCR-alpha/beta) on both established adjuvant arthritis (EAA) and established collagen-induced arthritis (ECIA) in rats have been investigated. Rats were treated with R73 mAb when arthritis reached a peak. Treatment with the anti-TCR-alpha/beta mAb markedly suppressed EAA, whereas ECIA was not affected by the mAb treatment. Histologically, R73 mAb-treated rats with EAA showed mild hyperplasia of synovial tissues, sparse infiltration of inflammatory cells, and minimal erosion of cartilage, whereas arthritic rats treated with PBS and an irrelevant control mAb against Giardia had marked hyperplasia of synovium with pannus, massive inflammatory cell infiltrate, and severe destruction of cartilage and subchondral bone. R73 mAb-treated rats with ECIA exhibited pronounced formation of pannus containing many inflammatory cells and marked cartilage and subchondral damage similar to those in arthritic rats that received the control treatments. Treatment with R73 mAb depleted markedly alpha/beta+ T cells in both peripheral blood and synovial tissues of rats with EAA and ECIA. R73 mAb treatment was associated with marked reduction in arthritogen-specific delayed-type hypersensitivity responses in both EAA and ECIA. The titers of antibodies against type II collagen produced in rats with ECIA were not affected by the mAb. Thus, alpha/beta+ T cells appear to have a central role in EAA, but not in chronic ECIA.     

Oral insulin treatment suppresses virus-induced antigen-specific destruction of beta cells and prevents autoimmune diabetes in transgenic mice.

Oral administration of self-antigens has been proposed as a therapy to prevent and treat autoimmune diseases. Here we report that oral treatment with insulin prevents virus-induced insulin-dependent diabetes mellitus (IDDM) in a transgenic (tg) mouse model. Such mice express the viral nucleoprotein (NP) of lymphocytic choriomeningitis virus (LCMV) under control of the rat insulin promoter in their pancreatic beta cells and < 2% spontaneously develop diabetes. However, 2 mo after challenge with LCMV, IDDM occurs in > 95% of tg mice but not in controls. Oral treatment with 1 mg of insulin twice per week for 2 mo starting either 1 wk before or 10 d after initiating LCMV infection prevents IDDM in > 50% of the tg mice (observation time 8 mo). Thus, insulin therapy is effective in preventing progression to overt IDDM in prediabetic tg mice with ongoing islet infiltration. Oral administration of insulin does not affect the generation of LCMV-NP-specific anti-self cytotoxic T lymphocytes nor the infiltration of lymphocytes into the pancreas. However, less beta cells are destroyed in insulin-treated mice, upregulation of MHC class I and II molecules does not occur, and antiviral (self) cytotoxic T lymphocytes are not found in the islets, events present in tg mice developing IDDM. The majority of lymphocytes in the islets of insulin-treated tg mice without IDDM produces IL-4, IL-10, and TGF-beta. In contrast, lymphocytes from islets of tg mice developing IDDM mainly make gamma-IFN.     

Phosphodiesterase-5 inhibition augments endogenous antitumor immunity by reducing myeloid-derived suppressor cell function

Phosphodiesterase-5 (PDE5) inhibitors (sildenafil, tadalafil, and vardenafil) are agents currently in clinical use for nonmalignant conditions. We report the use of PDE5 inhibitors as modulators of the antitumor immune response. In several mouse tumor models, PDE5 inhibition reverses tumor-induced immunosuppressive mechanisms and enables a measurable antitumor immune response to be generated that substantially delays tumor progression. In particular, sildenafil, down-regulates arginase 1 and nitric oxide synthase-2 expression, thereby reducing the suppressive machinery of CD11b+/Gr-1+ myeloid-derived suppressor cells (MDSCs) recruited by growing tumors. By removing these tumor escape mechanisms, sildenafil enhances intratumoral T cell infiltration and activation, reduces tumor outgrowth, and improves the antitumor efficacy of adoptive T cell therapy. Sildenafil also restores in vitro T cell proliferation of peripheral blood mononuclear cells from multiple myeloma and head and neck cancer patients. In light of the recent data that enzymes mediating MDSC-dependent immunosuppression in mice are active also in humans, these findings demonstrate a potentially novel use of PDE5 inhibitors as adjuncts to tumor-specific immune therapy.     

非肥胖2型糖尿病一级亲属胰岛β细胞功能和胰岛素抵抗的评价

目的:测定非肥胖的2型糖尿病的一级亲属的胰岛素敏感性、胰岛β细胞分泌功能及胰岛素的早期分泌。方法:选取59例正常对照组、58例糖耐量正常的糖尿病一级亲属及38例2型糖尿病的个体进入研究,他们的体质量指数均小于25kg/m2。所有研究对象均分别完成口服葡萄糖耐量试验。分析各组稳态模式评估法(homeostasismodelassessment,HOMA)模型胰岛素抵抗指数(HOMA-IR)、β细胞功能指数(HOMA-β)及胰岛初期分泌指数(ΔI30/ΔG30)。结果:无论用免疫反应胰岛素还是用真胰岛素计算的非肥胖的糖耐量正常的一级亲属的HOMA-IR4.93±1.55和2.39±0.72及1.83±0.64和1.33±0.53均高于正常对照组(P<0.05),但低于2型糖尿病组(13.37±12.40及3.28±2.24,P均<0.01);而由真胰岛素计算的Homa-BTI,一级亲属组低于对照组(103.90±51.79和38.45±24.25,P<0.01);由真胰岛素计算的△I30/△G30显示一级亲属组低于对照组(11.78±8.77和4.54±3.14,P<0.05),但高于2型糖尿病组(4.54±3.14,P<0.05)。结论:非肥胖2型糖尿病一级亲属在糖耐量正常时就已经存在胰岛β细胞功能的受损、胰岛素抵抗及胰岛素早期分泌指数减低,胰岛素抵抗的存在并非继发于肥胖和高血糖。     

胰岛素不同输注方式对新初断2型糖尿病患者胰岛B细胞功能的影响

目的比较短期胰岛素泵连续皮下输注(CSII)与多次皮下胰岛素(MSII)注射强化治疗对新诊断的2型糖尿病(T2DM)患者胰岛B细胞功能的影响。方法对60例新诊断的2型糖尿病住院患者随机分为两组,分别给予CSII和MSII进行短期强化治疗,比较两组治疗前后的血糖、血脂及两组间血糖达标天数、达标时每日胰岛素总剂量、强化治疗两周时每日胰岛素总剂量、胰岛B细胞功能变化的差异。结果 CSII组与MSII组治疗后静脉血糖和血脂均较治疗前下降,差异有统计学意义(P<0.05)。CSII组血糖达标时间显著短于MSII组,CSII组在血糖达标时和治疗第14天时胰岛素日剂量均显著少于MSII组(P<0.05)。CSII组胰岛B细胞功能及胰岛素抵抗改善更明显,差异有统计学意义(P<0.05)。结论与MSII治疗相比,CSII治疗能够缩短血糖达标时间,减少胰岛素用量,更好地改善胰岛B细胞功能及胰岛素抵抗。     

Reversal of experimental autoimmune encephalomyelitis with a hydroxamate inhibitor of matrix metalloproteases.

Gelatinases, belonging to the matrix metalloproteases, contribute to tissue destruction in inflammatory demyelinating disorders of the central nervous system such as multiple sclerosis. We used experimental autoimmune encephalomyelitis (EAE) as an animal model to evaluate the effect of a hydroxamate matrix metalloprotease inhibitor (GM 6001) on inflammatory demyelination. A single dose of the inhibitor, given intraperitoneally, provided sufficient levels in the cerebrospinal fluid of animals with EAE to induce at least a partial inhibition of the gelatinase activity in the cerebrospinal fluid. When administered daily either from the time of disease induction or from the onset of clinical signs, GM 6001 suppressed the development or reversed clinical EAE in a dose-dependent way, respectively. Animals returned to the same clinical course as the nontreated group after cessation of treatment. Animals treated from the onset of clinical signs had normal permeability of the blood-brain barrier, compared with the enhanced permeability in nontreated animals. These results indicate that matrix metalloprotease inhibition can reverse ongoing EAE. This effect appears to be mediated mainly through restoration of the damaged blood-brain barrier in the inflammatory phase of the disease, since, the degree of demyelination and inflammation did not differ between the treatment groups.     

Alternative sources of beta cells for cell therapy of diabetes

Type 1 and type 2 diabetes affect 150 million people worldwide. This is a result of the incapacity of pancreatic beta cells to produce and secrete enough insulin. Transplantation of pancreatic beta cells represents a potential therapeutic approach for type 1 diabetes. However, one limitation is the insufficient amount of beta cells available for grafts. Alternative sources of beta cells have yet to be defined. During the past years, progress has been made in the definition of new strategies to produce mature pancreatic beta cells. Different cell sources are currently tested for their capacity to differentiate into mature beta cells. In this review, I will summarize the status of our knowledge in the field of cell therapy for diabetes.     

Reversal of spontaneous autoimmune insulitis in nonobese diabetic mice by soluble lymphotoxin receptor

One striking feature of spontaneous autoimmune diabetes is the prototypic formation of lymphoid follicular structures within the pancreas. Lymphotoxin (LT) has been shown to play an important role in the formation of lymphoid follicles in the spleen. To explore the potential role of LT-mediated microenvironment in the pathogenesis of insulin-dependent diabetes mellitus (IDDM), an LTbeta receptor-immunoglobulin fusion protein (LTbetaR-Ig) was administered to nonobese diabetic mice. Early treatment with LTbetaR-Ig prevented insulitis and IDDM, suggesting that LT plays a critical role in the insulitis development. LTbetaR-Ig treatment at a late stage of the disease also dramatically reversed insulitis and prevented diabetes. Moreover, LTbetaR-Ig treatment prevented the development of IDDM by diabetogenic T cells in an adoptive transfer model. Thus, LTbetaR-Ig can disassemble the well established lymphoid microenvironment in the islets, which is required for the development and progression of IDDM.