Cellular and molecular mechanisms for the initiation and progression of beta cell destruction resulting from the collaboration between macrophages and T cells

Modulation of lncRNA NEAT1 overturns the macrophages based immune response in M. tuberculosis infected patients via miR-373 regulation

There is a lack of studies which explore and clarify the interactions that occur between host macrophage and Mycobacterium tuberculosis with regard to microRNA such as LNCNEAT1 and miR-373. The current study determines the mechanisms involved in the control of M. tuberculosis infection by macrophage using LNCNEAT1 and miR-373. The researchers collected different samples from healthy individuals, pulmonary TB patients, and samples like hMDMs cells and H37Rv infected MTB to determine the concentrations of inflammatory factors. The impact of NEAT1 and miR-373 upon macrophages was analyzed in NEAT1-specific siRNA (si-NEAT1), NEAT1 over-expression vector (pcDNA3.1-NEAT1), miR-373 mimic, miR-373 inhibitor (anti-miR-373), and negative control, and macrophages infected with H37Ra. The results inferred that among pulmonary TB patients, NEAT1 got heavily expressed while the expression level of miR-373 was poor. The number of inflammatory factors with pulmonary TB was notably higher. This got further amplified in macrophages after being infected with H37Ra, while no such observations found for miR-373. During post-transfection, low concentration of inflammatory factors was observed while the cells in si-NEAT1 group got proliferated in low volume compared to both pcDNA3.1-NEAT1 group and NEAT1 negative control group. However, the capability of apoptosis was higher compared to the other two groups (p < 0.05). There was an increase observed in inflammatory factors as well as proliferation in anti-miR-373 group compared to miR-373 mimics and miR-373-negative control group while a significant decline was observed in apoptosis. LNCNEAT1 aggravated the number of inflammatory factors in macrophages that got infected with MTB while on the other end, it mitigated both phagocytosis as well as the cellular immunity of macrophages. In addition to this, it enhanced the proliferation of infected cells and inhibited apoptosis via targeted regulation of miR-373, thus resulting in the development of TB.

Heterogeneity of T cells in periapical lesions and in vitro validation of the proangiogenic effect of GZMA on HUVECs

AIM

T cells are key immunomodulatory cells in periapical lesions. This study aimed to explore the roles of T cells in chronic apical periodontitis (CAP) using single-cell RNA sequencing and to further investigate Granzyme A (GZMA) in angiogenesis regulation.

METHODOLOGY

A total of five CAP samples were collected for single-cell RNA sequencing. We performed subcluster and lineage-tracing analyses for T cells. According to differential gene expression, distinct biological functions enriched in T cells of CAP were presented by gene set enrichment analysis (GSEA) and compared with healthy gingiva (data obtained from the GEO database). CellChat was used to explore potential ligand-receptor interactions between T cells and endothelial cells in CAP. The coculture of primary human umbilical vein endothelial cells (HUVECs) and Jurkat T cells, as well as the addition of GZMA recombinant protein, was used to validate the predicted pair of GZMA and coagulation factor II thrombin receptor (F2R) by RT-PCR, angiogenesis and migration assays.

RESULTS

A transcriptomic atlas of 44 746 individual cells was constructed from the periapical lesions of five patients with CAP by single-cell RNA-seq, and eight cell types were identified. We identified nine subsets of T cells and deciphered the cellular heterogeneity of T cells in CAP at the functional level by subclustering and GSEA. Lineage tracing revealed a distinct lineage of T cells in CAP and predicted the transition of the T cellular state upon CAP. GSEA revealed multiple biological processes and relevant angiogenesis genes upregulated in CAP T cells. GZMA-F2R pairs were predicted by cell-cell interactions in CAP. High expression of GZMA and F2R was observed in the coculture of HUVECs and Jurkat T cells, and the proangiogenic capacity of the GZMA recombinant protein was emphasized by in vitro experiments.

CONCLUSIONS

Our study provides novel insights into the heterogeneity of T cells in periapical lesions and reveals the potential role of GZMA in T cells in regulating angiogenesis in HUVECs.

Multivalent mannose-conjugated siRNA causes robust gene silencing in pancreatic macrophages in vivo

Nucleic acid therapeutics have been utilized for gene regulation, and their recent advancement has led to approval of novel drugs for liver-related disorders. However, systemic extrahepatic delivery remains challenging. Here, we report newly designed mannose-conjugated oligonucleotides for delivering oligonucleotides to macrophages by leveraging the mannose receptor, C-type 1 (MRC1, CD206), which is abundantly expressed in macrophages. We investigated the relationship between cellular uptake and multivalency (mono to tetra) of mannose ligands or linker length and selected a trivalent-mannose ligand. Trivalent-mannose (Man3)-conjugated siRNA induced concentration-dependent gene silencing in both human CD206-overexpressing cells and human macrophages in vitro. After subcutaneous injection into mice, we observed a high distribution of Man3-conjugated oligonucleotides in the liver and pancreata as well as cellular uptake into Kupffer cells and pancreatic macrophages. A single subcutaneous injection of Man3-conjugated siRNA (10 mg/kg) targeting β₂-microglobulin (B2M) silenced B2m mRNA expression by ∼50% and decreased its protein levels in mouse pancreatic macrophages compared to those in saline-treated mice. Of note, multiple subcutaneous injections decreased B2m gene expression and B2M protein levels by ∼80% and ∼85%, respectively. These results show that mannose-conjugation with oligonucleotides is expected to help deliver oligonucleotides to macrophages and regulate gene expression in vivo, particularly in the pancreas.

Small Molecule Inhibitors of Lymphocyte Perforin as Focused Immunosuppressants for Infection and Autoimmunity

New drugs that precisely target the immune mechanisms critical for cytotoxic T lymphocyte (CTL) and natural killer (NK) cell driven pathologies are desperately needed. In this perspective, we explore the cytolytic protein perforin as a target for therapeutic intervention. Perforin plays an indispensable role in CTL/NK killing and controls a range of immune pathologies, while being encoded by a single copy gene with no redundancy of function. An immunosuppressant targeting this protein would provide the first-ever therapy focused specifically on one of the principal cell death pathways contributing to allotransplant rejection and underpinning multiple autoimmune and postinfectious diseases. No drugs that selectively block perforin-dependent cell death are currently in clinical use, so this perspective will review published novel small molecule inhibitors, concluding with in vivo proof-of-concept experiments performed in mouse models of perforin-mediated immune pathologies that provide a potential pathway toward a clinically useful therapeutic agent.

Resveratrol inhibits macrophage infiltration of pancreatic islets in streptozotocin-induced type 1 diabetic mice via attenuation of the CXCL16/NF-κΒ p65 signaling pathway

AIM

Despite CXC chemokine ligand 16 (CXCL16) contributes to the pathogenesis of many inflammatory disorders, the mechanism by which CXCL16 is involved in T1DM remains unclear. In this study, we examined the role of the CXCL16/NF-κΒ p65 signaling pathway in the progression of this disease and the possible protective effect of resveratrol (RES) on streptozotocin (STZ)-induced T1DM.

MAIN METHODS

Mice were classified into four groups of 10 animals each. The control group received citrate buffer. The RES group received 50 mg/kg i.p. RES for 12 days beginning on day 4 of citrate buffer. The STZ group received 55 mg/kg i.p. STZ once a day for 5 consecutive days. The fourth group injected with RES (50 mg/kg) for 12 days starting on day 4 of STZ injection. Biochemical, physical and oxidative stress parameters were measured in all groups. Moreover, expression of CXCL16 and CD45 was measured in pancreatic islets and spleen. Additionally, NF-κΒ p65 was investigated in isolated islets.

KEY FINDINGS

Our results showed a significant elevation of CXCL16, NF-κΒ p65 and CD45 in islets of diabetic (DM) mice. Intriguingly, RES significantly restored distorted biochemical, physical and oxidative stress parameters after STZ treatment as well as inhibited the expression of CXCL16/NF-κΒ p65 in pancreatic islets. Moreover, RES normalized CXCL16 and CD45 expression in islets and spleen.

SIGNIFICANCE

This study demonstrates first evidence that CXCL16/NF-κΒ p65 signaling pathway is associated with macrophage infiltration to pancreatic islet in T1DM and that RES successfully improved T1DM may be at least via inhibiting this pathway.

Macrophage inflammatory state in Type 1 diabetes: triggered by NLRP3/iNOS pathway and attenuated by docosahexaenoic acid

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease characterized by insulin-producing pancreatic β-cell destruction and hyperglycemia. While monocytes and NOD-like receptor family-pyrin domain containing 3 (NLRP3) are associated with T1D onset and development, the specific receptors and factors involved in NLRP3 inflammasome activation remain unknown. Herein, we evaluated the inflammatory state of resident peritoneal macrophages (PMs) from genetically modified non-obese diabetic (NOD), NLRP3-KO, wild-type (WT) mice and in peripheral blood mononuclear cells (PBMCs) from human T1D patients. We also assessed the effect of docosahexaenoic acid (DHA) on the inflammatory status. Macrophages from STZ-induced T1D mice exhibited increased inflammatory cytokine/chemokine levels, nitric oxide (NO) secretion, NLRP3 and iNOS protein levels, and augmented glycolytic activity compared to control animals. In PMs from NOD and STZ-induced T1D mice, DHA reduced NO production and attenuated the inflammatory state. Furthermore, iNOS and IL-1β protein expression levels and NO production were lower in the PMs from diabetic NLRP3-KO mice than from WT mice. We also observed increased IL-1β secretion in PBMCs from T1D patients and immortalized murine macrophages treated with advanced glycation end products and palmitic acid. The present study demonstrated that the resident PMs are in a proinflammatory state characterized by increased NLRP3/iNOS pathway-mediated NO production, up-regulated proinflammatory cytokine/chemokine receptor expression and altered glycolytic activity. Notably, ex vivo treatment with DHA reverted the diabetes-induced changes and attenuated the macrophage inflammatory state. It is plausible that DHA supplementation could be employed as adjuvant therapy for treating individuals with T1D.

Therapeutic potential of mesenchymal stem cells in treating both types of diabetes mellitus and associated diseases

Diabetes mellitus is a common lifestyle disease which can be classified into type 1 diabetes mellitus and type 2 diabetes mellitus. While both result in hyperglycemia due to lack of insulin action and further associated chronic ailments, there is a marked distinction in the cause for each type due to which both require a different prophylaxis. As observed, type 1 diabetes is caused due to the autoimmune action of the body resulting in the destruction of pancreatic islet cells. On the other hand, type 2 diabetes is caused either due to insulin resistance of target cells or lack of insulin production as per physiological requirements. Attempts to cure the disease have been made by bringing drastic changes in the patients' lifestyle; parenteral administration of insulin; prescription of drugs such as biguanides, meglitinides, and amylin; pancreatic transplantation; and immunotherapy. While these attempts cause a certain degree of relief to the patient, none of these can cure diabetes mellitus. However, a new treatment strategy led by the discovery of mesenchymal stem cells and their unique immunomodulatory and multipotent properties has inspired therapies to treat diabetes by essentially reversing the conditions causing the disease. The current review aims to enumerate the role of various mesenchymal stem cells and the different approaches to treat both types of diabetes and its associated diseases as well.

Crosstalk Between Immunity System Cells and Pancreas. Transformation of Stem Cells Used in the 3D Bioprinting Process as a Personalized Treatment Method for Type 1 Diabetes

Interactions between the immune system and the pancreas are pivotal in understanding how and why β cells' damage causes problems with pancreas functioning. Pancreatic islets are crucial in maintaining glucose homeostasis in organs, tissue and cells. Autoimmune aggression towards pancreatic islets, mainly β cells, leads to type 1 diabetes-one of the most prevalent autoimmune disease in the world, being a worldwide risk to health of many people. In this review, we highlight the role of immune cells and its influence in the development of autoimmunity in Langerhans islets. Moreover, we discuss the impact of the immunological factors on future understanding possible recurrence of autoimmunity on 3D-bioprinted bionic pancreas.

Mitochondrial Reactive Oxygen Species and Type 1 Diabetes

SIGNIFICANCE

The complex etiology of type 1 diabetes (T1D) is the outcome of failures in regulating immunity in combination with beta cell perturbations. Mitochondrial dysfunction in beta cells and immune cells may be involved in T1D pathogenesis. Mitochondrial energy production is essential for the major task of beta cells (the secretion of insulin in response to glucose). Mitochondria are a major site of reactive oxygen species (ROS) production. Under immune attack, mitochondrial ROS (mtROS) participate in beta cell damage. Similarly, T cell fate during immune responses is tightly regulated by mitochondrial physiology, morphology, and metabolism. Production of mtROS is essential for signaling in antigen-specific T cell activation. Mitochondrial dysfunction in T cells has been noted as a feature of some human autoimmune diseases. Recent Advances: Preclinical and clinical studies indicate that mitochondrial dysfunction in beta cells sensitizes these cells to immune-mediated destruction via direct or indirect mechanisms. Sensitivity of beta cells to mtROS is associated with genetic T1D risk loci in human and the T1D-prone nonobese diabetic (NOD) mouse. Mitochondrial dysfunction and altered metabolism have also been observed in immune cells of NOD mice and patients with T1D. This immune cell mitochondrial dysfunction has been linked to deleterious functional changes.

CRITICAL ISSUES

It remains unclear how mitochondria control T cell receptor signaling and downstream events, including calcium flux and activation of transcription factors during autoimmunity.

FUTURE DIRECTIONS

Mechanistic studies are needed to investigate the mitochondrial pathways involved in autoimmunity, including T1D. These studies should seek to identify the role of mitochondria in regulating innate and adaptive immune cell activity and beta cell failure.

Neutralization Versus Reinforcement of Proinflammatory Cytokines to Arrest Autoimmunity in Type 1 Diabetes

As physiological pathways of intercellular communication produced by all cells, cytokines are involved in the pathogenesis of inflammatory insulitis as well as pivotal mediators of immune homeostasis. Proinflammatory cytokines including interleukins, interferons, transforming growth factor-β, tumor necrosis factor-α, and nitric oxide promote destructive insulitis in type 1 diabetes through amplification of the autoimmune reaction, direct toxicity to β-cells, and sensitization of islets to apoptosis. The concept that neutralization of cytokines may be of therapeutic benefit has been tested in few clinical studies, which fell short of inducing sustained remission or achieving disease arrest. Therapeutic failure is explained by the redundant activities of individual cytokines and their combinations, which are rather dispensable in the process of destructive insulitis because other cytolytic pathways efficiently compensate their deficiency. Proinflammatory cytokines are less redundant in regulation of the inflammatory reaction, displaying protective effects through restriction of effector cell activity, reinforcement of suppressor cell function, and participation in islet recovery from injury. Our analysis suggests that the role of cytokines in immune homeostasis overrides their contribution to β-cell death and may be used as potent immunomodulatory agents for therapeutic purposes rather than neutralized.

Modulating the immune system through nanotechnology

Nowadays, nanotechnology-based modulation of the immune system is presented as a cutting-edge strategy, which may lead to significant improvements in the treatment of severe diseases. In particular, efforts have been focused on the development of nanotechnology-based vaccines, which could be used for immunization or generation of tolerance. In this review, we highlight how different immune responses can be elicited by tuning nanosystems properties. In addition, we discuss specific formulation approaches designed for the development of anti-infectious and anti-autoimmune vaccines, as well as those intended to prevent the formation of antibodies against biologicals.

TGF-β engineered mesenchymal stem cells (TGF-β/MSCs) for treatment of Type 1 diabetes (T1D) mice model

OBJECTIVE

Mesenchymal stem cells (MSCs) are advantageous candidates for cell therapy of Type 1 diabetes (T1D). Considering immunomodulatory effect of MSC, in this study, we engineered MSCs with TGF-β gene to increase MSC potency for T1D therapy in mouse model.

MATERIALS AND METHODS

Two plans were designed for prevention and treatment of diabetes, respectively. In both of them, MSCs were injected i.v. and then, the diabetes features including serum insulin, blood glucose, glucose tolerance, splenocytes proliferation, and IL-4/IFN-γ production were evaluated.

RESULTS

TGF-β/MSCs treatment program resulted in the restoration of serum glucose after 3weeks, while prevention program could delay diabetes progression for two weeks. TGF-β/MSCs treatment elevated the levels of serum insulin and Th2 cytokine shift on 5th week after start of treatment. TGF-β/MSCs (and MSCs alone) could also diminish body weight and enhance mice survival comparing to untreated diabetic mice.

CONCLUSION

Engineered TGF-β/MSCs could restore some T1D features, including the regulation of adverse immune responses and could be potent tools for cell therapy of T1D comparing MSCs alone.

Novel model of double transgenic mouse results in autoimmune diabetes in males

Identifying the type of diabetogenic CD8⁺ T cells that initiate autoimmune diabetes (AID) is a critical step in designing appropriate strategies for the early detection of beta cell-directed autoimmunity and its progression to diabetes. We generated a novel double transgenic (Tg) mouse model on the naturally diabetes resistant C57Bl/6 background, co-expressing two transgenes including a specific TCR anti-lymphocytic choriomeningitis virus nucleoprotein (LCMV-NP) carried by CD8⁺ T cells and LCMV-NP (as neo-self antigen) expressed by pancreatic beta cells. The resulting double Tg mouse showed partial thymic deletion of the NP-specific CD8⁺ T cells. The escaping autoreactive NP-specific CD8⁺ T cells joining the periphery were activated and gained effector functions. Both male and female mice mounted anti-NP antibodies, but only one-fourth adult males spontaneously developed AID. Significant upregulation of the CD44 and CD122 markers as compared to healthy male and female mice characterized the phenotype of diabetogenic CD8⁺ T cells in diabetic male mice. We also show that only 10% of these CD8⁺T cells expressed programmed death 1 receptor (PD-1). Together, these results suggest that in our double Tg mouse model, Ag-specific effector CD44⁺CD122⁺PD-1^-CD8⁺ T cell subpopulation is associated with the pathogenesis of AID.

Mechanisms of autoimmunity in the non-obese diabetic mouse: effector/regulatory cell equilibrium during peak inflammation

Immune imbalance in autoimmune disorders such as type 1 diabetes may originate from aberrant activities of effector cells or dysfunction of suppressor cells. All possible defective mechanisms have been proposed for diabetes-prone species: (i) quantitative dominance of diabetogenic cells and decreased numbers of regulatory T cells, (ii) excessive aggression of effectors and defective function of suppressors, (iii) perturbed interaction between effector and suppressor cells, and (iv) variations in sensitivity to negative regulation. The experimental evidence available to date presents conflicting information on these mechanisms, with identification of perturbed equilibrium on the one hand and negation of critical role of each mechanism in propagation of diabetic autoimmunity on the other hand. In our analysis, there is no evidence that inherent abnormalities in numbers and function of effector and suppressor T cells are responsible for the immune imbalance responsible for propagation of type 1 diabetes as a chronic inflammatory process. Possibly, the experimental tools for investigation of these features of immune activity are still underdeveloped and lack sufficient resolution, in the presence of the extensive biological viability and functional versatility of effector and suppressor elements.

P2X7 receptor knockout prevents streptozotocin-induced type 1 diabetes in mice

Type 1 diabetes (T1D) is caused by autoimmune destruction of islet of Langerhans β-cells. P2X7 receptors (P2X7R) modulate proinflammatory immune responses by binding extracellular ATP, a classic 'danger signal'. Here, we evaluated whether the P2X7R has a role in T1D development. P2X7(-/-) mice are resistant to TD1 induction by streptozotocin (STZ) treatment, with no increase in blood glucose, decrease in insulin-positive cells, and pancreatic islet reduction, compared to WT (C57BL/6) mice. Also, the levels of proinflammatory mediators (IL-1β, IFN-γ and NO) did not increase after STZ treatment in P2X7(-/-) animals, with reduced infiltration of CD4(+), CD8(+), B220(+), CD11b(+) and CD11c(+) cells in the pancreatic lymph nodes. Treatment with a P2X7 antagonist mimicked the effect of P2X7 knockout, preventing STZ-induced diabetes. Our results show that the absence of the P2X7R provides resistance in the induction of diabetes in this model, and suggest that therapy targeting the P2X7R may be useful against clinical T1D.

Case Reports That Illustrate the Efficacy of SGLT2 Inhibitors in the Type 1 Diabetic Patient

SGLT2 inhibitors are only approved for use in adults with type 2 diabetes. However, because SGLT2 inhibitors have a mechanism of action that does not require the presence of endogenous insulin, these drugs should also be efficacious in type 1 diabetes where endogenous insulin production is greatly reduced or absent. Herein, I present five cases which illustrate the benefits of utilizing an SGLT2 inhibitor with type 1 diabetes. In these cases the use of SGLT2 inhibitors resulted not only in better glycemic control in most patients but also in some patients' less hypoglycemia, weight loss, and decreased doses of insulin. In type 1 diabetes Candida albicans vaginitis and balanitis may occur more frequently than in type 2 diabetes. These cases show that a large randomized clinical trial of SGLT2 inhibitors in type 1 diabetes needs to be performed.

Treating type-1 diabetes with an epigenetic drug

A single drug treats type-1 diabetes in mice by dampening inflammation and enhancing insulin production.

Young porcine endocrine pancreatic islets cultured in fibrin and alginate gels show improved resistance towards human monocytes

AIM

To investigate the protective function of alginate and fibrin gels used to embed porcine endocrine pancreatic islets towards human monocytes.

METHODS

Groups of 200 islet equivalents from young pigs were embedded in either a fibrin or in an alginate gel, and as a control seeded in tissue culture polystyrene (TCPS) well plates. The islet cultures were incubated with 2×10(5) human monocytes for 24h. In addition, both islets and monocytes were separately cultured in TCPS, fibrin and alginate. Islet morphology, viability and function were investigated as well as the secretion of cytokines TNFα, IL-6, and IL-1β.

RESULTS

When freely-floating in TCPS, non-encapsulated islets were surrounded by monocytes and started to disperse after 24h. In fibrin, monocytes could be found in close proximity to embedded islets, indicating monocyte migration through the gel. In contrast, after 24h, few monocytes were found close to islets in alginate. Immunofluorescence staining and manual counting showed that integrin expression was higher in fibrin-embedded islet cultures. A TUNEL assay revealed elevated numbers of apoptotic cells for islets in TCPS wells compared to fibrin and alginate cultures. Insulin secretion was higher with islets embedded in fibrin and alginate when compared to non-encapsulated islets. TNFα, IL-6 and IL-1β were found in high concentrations in the media of co-cultures and monocyte mono-culture in fibrin.

CONCLUSION

Both alginate and fibrin provide key structural support and offer some protection for the islets towards human monocytes. Fibrin itself triggers the cytokine secretion from monocytes.

Role of immune system in type 1 diabetes mellitus pathogenesis

The immune system is the body's natural defense system against invading pathogens. It protects the body from infection and works to communicate an individual's well-being through a complex network of interconnected cells and cytokines. This system is an associated host defense. An uncontrolled immune system has the potential to trigger negative complications in the host. Type 1 diabetes results from the destruction of pancreatic β-cells by a β-cell-specific autoimmune process. Examples of β-cell autoantigens are insulin, glutamic acid decarboxylase, tyrosine phosphatase, and insulinoma antigen. There are many autoimmune diseases, but type 1 diabetes mellitus is one of the well-characterized autoimmune diseases. The mechanisms involved in the β-cell destruction are still not clear; it is generally believed that β-cell autoantigens, macrophages, dendritic cells, B lymphocytes, and T lymphocytes are involved in the β-cell-specific autoimmune process. It is necessary to determine what exact factors are causing the immune system to become unregulated in such a manner as to promote an autoimmune response.

Stem cell therapy to cure type 1 diabetes: from hype to hope

Type 1 diabetes mellitus (T1D) is a chronic, multifactorial autoimmune disease that involves the progressive destruction of pancreatic β-cells, ultimately resulting in the loss of insulin production and secretion. The goal of clinical intervention is to prevent or arrest the onset and progression of autoimmunity, reverse β-cell destruction, and restore glycometabolic and immune homeostasis. Despite promising outcomes observed with islet transplantation and advancements in immunomodulatory therapies, the need for an effective cell replacement strategy for curing T1D still persists. Stem cell therapy offers a solution to the cited challenges of islet transplantation. While the regenerative potential of stem cells can be harnessed to make available a self-replenishing supply of glucose-responsive insulin-producing cells, their immunomodulatory properties may potentially be used to prevent, arrest, or reverse autoimmunity, ameliorate innate/alloimmune graft rejection, and prevent recurrence of the disease. Herein, we discuss the therapeutic potential of stem cells derived from a variety of sources for the cure of T1D, for example, embryonic stem cells, induced pluripotent stem cells, bone marrow-derived hematopoietic stem cells, and multipotent mesenchymal stromal cells derived from bone marrow, umbilical cord blood, and adipose tissue. The benefits of combinatorial approaches designed to ensure the successful clinical translation of stem cell therapeutic strategies, such as approaches combining effective stem cell strategies with islet transplantation, immunomodulatory drug regimens, and/or novel bioengineering techniques, are also discussed. To conclude, the application of stem cell therapy in the cure for T1D appears extremely promising.

Animal models of diabetes mellitus for islet transplantation

Due to current improvements in techniques for islet isolation and transplantation and protocols for immunosuppressants, islet transplantation has become an effective treatment for severe diabetes patients. Many diabetic animal models have contributed to such improvements. In this paper, we focus on 3 types of models with different mechanisms for inducing diabetes mellitus (DM): models induced by drugs including streptozotocin (STZ), pancreatomized models, and spontaneous models due to autoimmunity. STZ-induced diabetes is one of the most commonly used experimental diabetic models and is employed using many specimens including rodents, pigs or monkeys. The management of STZ models is well established for islet studies. Pancreatomized models reveal different aspects compared to STZ-induced models in terms of loss of function in the increase and decrease of blood glucose and therefore are useful for evaluating the condition in total pancreatomized patients. Spontaneous models are useful for preclinical studies including the assessment of immunosuppressants because such models involve the same mechanisms as type 1 DM in the clinical setting. In conclusion, islet researchers should select suitable diabetic animal models according to the aim of the study.

Effect of Sanqi Oral Liquid on the expressions of CD4⁺, CD8⁺ and CD68⁺ cells in 5/6 nephrectomized rats with chronic renal failure

OBJECTIVE

To explore the mechanisms of Chinese herbal medicine Sanqi Oral Liquid, composed of Astragalus membranaceus and Panpax notoginseng, in alleviating renal injury by observing its effect on the expressions of CD4(+), CD8(+) and CD68(+) cells in 5/6 nephrectomized rats with chronic renal failure.

METHODS

A total of 102 SD rats were randomly divided into six groups: three treatment groups were administrated with high, medium and low dosage of Sanqi Oral Liquid respectively by gavage; a normal group, a 5/6 nephrectomized model group, and a group treated with coated aldehyde oxygenstarch were used as controls. Following oral administration of Sanqi Oral Liquid for 12 weeks, the general condition and renal pathological changes were observed, and the renal function, platelet count (PLT) and the expressions of CD4(+), CD8(+) and CD68(+) cells were determined for each group.

RESULTS

There were proliferation of mesangial matrix, renaltubularnecrosis and obvious tubulointerstitial fibrosis in the model group, and they were much milder in the treatment groups. Compared with the model group, the amounts of blood urea nitrogen (BUN), serum creatinine (Scr) and PLT in the treatment groups decreased (P<0.05 for all); and in the group administrated of medium dosage of Sanqi Oral Liquid, the expression of CD4(+) cells was up-regulated and those of CD8(+) and CD68(+) cells were down-regulated (P<0.05 for all), leading to an increased ratio of CD4(+)/CD8(+)(P<0.01).

CONCLUSION

Sanqi Oral Liquid has a significant effect on regulating lymphocyte subsets, reducing the infiltration of macrophages in renal tissues and alleviating tubulointerstitial fibrosis, and this may be one of mechanisms of Sanqi Oral Liquid in delaying the progression of chronic kidney diseases.

Immunoregulation of follicular renewal, selection, POF, and menopause in vivo, vs. neo-oogenesis in vitro, POF and ovarian infertility treatment, and a clinical trial

The immune system plays an important role in the regulation of tissue homeostasis ("tissue immune physiology"). Function of distinct tissues during adulthood, including the ovary, requires (1) Renewal from stem cells, (2) Preservation of tissue-specific cells in a proper differentiated state, which differs among distinct tissues, and (3) Regulation of tissue quantity. Such morphostasis can be executed by the tissue control system, consisting of immune system-related components, vascular pericytes, and autonomic innervation. Morphostasis is established epigenetically, during morphogenetic (developmental) immune adaptation, i.e., during the critical developmental period. Subsequently, the tissues are maintained in a state of differentiation reached during the adaptation by a "stop effect" of resident and self renewing monocyte-derived cells. The later normal tissue is programmed to emerge (e.g., late emergence of ovarian granulosa cells), the earlier its function ceases. Alteration of certain tissue differentiation during the critical developmental period causes persistent alteration of that tissue function, including premature ovarian failure (POF) and primary amenorrhea. In fetal and adult human ovaries the ovarian surface epithelium cells called ovarian stem cells (OSC) are bipotent stem cells for the formation of ovarian germ and granulosa cells. Recently termed oogonial stem cells are, in reality, not stem but already germ cells which have the ability to divide. Immune system-related cells and molecules accompany asymmetric division of OSC resulting in the emergence of secondary germ cells, symmetric division, and migration of secondary germ cells, formation of new granulosa cells and fetal and adult primordial follicles (follicular renewal), and selection and growth of primary/preantral, and dominant follicles. The number of selected follicles during each ovarian cycle is determined by autonomic innervation. Morphostasis is altered with advancing age, due to degenerative changes of the immune system. This causes cessation of oocyte and follicular renewal at 38 +/-2 years of age due to the lack of formation of new granulosa cells. Oocytes in primordial follicles persisting after the end of the prime reproductive period accumulate genetic alterations resulting in an exponentially growing incidence of fetal trisomies and other genetic abnormalities with advanced maternal age. The secondary germ cells also develop in the OSC cultures derived from POF and aging ovaries. In vitro conditions are free of immune mechanisms, which prevent neo-oogenesis in vivo. Such germ cells are capable of differentiating in vitro into functional oocytes. This may provide fresh oocytes and genetically related children to women lacking the ability to produce their own follicular oocytes. Further study of "immune physiology" may help us to better understand ovarian physiology and pathology, including ovarian infertility caused by POF or by a lack of ovarian follicles with functional oocytes in aging ovaries. The observations indicating involvement of immunoregulation in physiological neo-oogenesis and follicular renewal from OSC during the fetal and prime reproductive periods are reviewed as well as immune system and age-independent neo-oogenesis and oocyte maturation in OSC cultures, perimenopausal alteration of homeostasis causing disorders of many tissues, and the first OSC culture clinical trial.

Macrophages from nonobese diabetic mouse have a selective defect in IFN-γ but not IFN-α/β receptor pathway

PURPOSE

Aberrant regulation of innate immune cells such as macrophages has been implicated in the onset and progression of type 1 diabetes (T1D). Macrophages from nonobese diabetic (NOD) mouse, an animal model of T1D, entail developmental and functional defects that are often associated with hypo-responsiveness to interferon (IFN)-γ. We aimed to uncover a mechanism underlying this phenomenon.

METHODS

We analyzed the receptor pathway along with the response of macrophages exposed to IFN-γ and the related IFNs such as IFN-α/β.

RESULTS

We found that NOD macrophages failed to fully respond to IFN-γ but not to IFN-α for the production of inflammatory cytokines (e.g. TNF-α and IL-12). NOD macrophages were also resistant to apoptotic pathway induced by IFN-γ and LPS. Analyses of receptor pathway revealed that STAT1 pathway of intracellular signaling was selectively impaired in NOD macrophages exposed to IFN-γ but not to IFN-α/β. Further, these defects correlated with a low phosphorylation level of JAK2, and were related to impaired up-regulation of surface IFN-γ receptor 2 (IFN-γR2) by IFN-γ.

CONCLUSION

Taken together, our results suggest that NOD macrophages have a selective defect in IFN-γ but not IFN-α/β receptor pathway. As IFN-γ and IFN-α have been implicated in the development of autoimmunity towards β-cells, such an unanticipated selectivity in IFN responsiveness may provide a new insight into the pathogenesis of T1D.

A defect in cell death of macrophages is a conserved feature of nonobese diabetic mouse

Impaired apoptosis in immune effector cells such as macrophages has been implicated in the development of autoimmune disease by promoting the breakdown of self-tolerance and the sustained production of cytotoxic molecules. Macrophages from nonobese diabetic (NOD) mouse, an animal model of human autoimmune diabetes, exhibit several defects that are causally linked to the onset and progression of the disease. In this context, we investigated whether NOD macrophages have a defect in a cell death pathway, and if that is the case, the mechanism underlying such dysregulation of cell death. We found that NOD macrophages were resistant to treatment with a broad spectrum of cell death stimuli, triggering both apoptotic and non-apoptotic death. Through analysis of intracellular signaling pathways along with the expression of apoptosis-related proteins, we found that atypical resistance to cell death was associated with an elevated expression of anti-apoptotic Bcl-X(L) but not the NF-κB signaling pathway in NOD macrophages. Further, ABT-737, which can inhibit Bcl-X(L) function, sensitized NOD macrophages to apoptosis induced by diverse apoptotic stimuli, thus restoring sensitivity to cell death. Taken together, our results suggest a macrophage-intrinsic defect in cell death as a potential mechanism that promotes an immune attack towards pancreatic β-cells and the development of autoimmune diabetes in NOD mice.

Current status of immunomodulatory and cellular therapies in preclinical and clinical islet transplantation

Clinical islet transplantation is a β-cell replacement strategy that represents a possible definitive intervention for patients with type 1 diabetes, offering substantial benefits in terms of lowering daily insulin requirements and reducing incidences of debilitating hypoglycemic episodes and unawareness. Despite impressive advances in this field, a limiting supply of islets, inadequate means for preventing islet rejection, and the deleterious diabetogenic and nephrotoxic side effects associated with chronic immunosuppressive therapy preclude its wide-spread applicability. Islet transplantation however allows a window of opportunity for attempting various therapeutic manipulations of islets prior to transplantation aimed at achieving superior transplant outcomes. In this paper, we will focus on the current status of various immunosuppressive and cellular therapies that promote graft function and survival in preclinical and clinical islet transplantation with special emphasis on the tolerance-inducing capacity of regulatory T cells as well as the β-cells regenerative capacity of stem cells.

Autoimmune-mediated vascular injury occurs prior to sustained hyperglycemia in a murine model of type I diabetes mellitus

BACKGROUND

Accelerated cardiovascular disease in patients with type I diabetes (TID) is a well-described condition and serious clinical obstacle. At present, the notion that early atherogenesis is largely dependent on sustained hyperglycemia remains in question. We hypothesize that an alteration in T lymphocyte homeostasis may result in early vascular inflammation, which might amplify subsequent blood vessel injury in euglycemia.

METHODS

A murine model of carotid arterial ligation was employed to induce neointimal hyperplasia (NIH) in C57/Bl6 (non-autoimmune) and non-obese diabetic (NOD) mice. Additionally, adoptive transfer of NOD splenocytes into immunodeficient NOD mice (NOD.scid) was undertaken to evaluate the influence of restored autoimmunity on NIH development.

RESULTS

Interestingly, compared with C57/Bl6 mice, the NOD demonstrate a significant increase in neointimal area. Conversely, the NOD.scid mice (immunodeficient control) reveal almost no evidence of vascular injury. While evidence of early vascular inflammation can be detected in the injured NOD vasculature, uninjured contralateral vessels and those of the NOD.scid have minimal T cell infiltration. Following reconstitution of autoimmune responses via NOD splenocyte adoptive transfer, accelerated vascular pathology is restored.

CONCLUSIONS

These observations suggest that autoimmunity, in the setting of impending hyperglycemia, may contribute to accelerated vascular inflammation and subsequent pathology.

Activation of peritoneal macrophages during the evolution of type 1 diabetes (insulitis) in streptozotocin-treated mice

The effects of lipopolysaccharide (LPS) and desArg9Bradykinin (DBK) on the release of nitric oxide (NO) from macrophages of mice 8, 12 and 18 days after having been treated with low doses of streptozotocin (STZ; 5 × 45 mg/kg) were studied. The results showed that LPS stimulated the release of NO from macrophages of untreated animals by 50% whereas the bradykinin B(1) agonist desArg9Bradykinin (DBK) increased the level of NO by 20%. This increased NO production was totally abolished by incubating the cells with R-954, a selective bradykinin B(1) antagonist. The release of NO from macrophages of STZ-treated mice incubated in the presence of LPS was more marked and reached approximately 220, 300 and 270% respectively from cells collected 8, 12 and 18 days after the STZ treatment. These significant increases were completely blocked by R-954 and were even below control values. Similarly the results showed that DBK stimulated by 50-75% the release of NO from macrophages of STZ-treated mice. The most marked stimulation was noted when the cells were collected 18 days after the treatment of the animals with STZ. Again in this set of experiments the B(1) antagonist completely blocked the release of NO which went even below control values. The results clearly suggest the upregulation of bradykinin B(1) receptors in mouse macrophages in the early phase of STZ-induced diabetes, an event that could even precede the onset of the diabetic hyperglycemia.

Autoantigens plus interleukin-10 suppress diabetes autoimmunity

BACKGROUND

Recombinant vaccinia virus (rVV) strains expressing the immunomodulatory cholera toxin B subunit (CTB) fused to the autoantigen glutamic acid decarboxylase (GAD) or the immunosuppressive cytokine interleukin-10 (IL-10) were independently able to generate only low levels of immune suppression of type 1 diabetes mellitus (T1DM). Here we suggest that a vaccinia virus (VV)-mediated combination of CTB::GAD fusion and IL-10 proteins promises a effective and durable immunotherapeutic strategy for T1DM.

METHODS

To explore this hypothesis, a CTB::GAD fusion gene was co-delivered with a gene encoding IL-10 by rVV infection (rVV-CTB::GAD + rVV-IL10) into 5-7-week-old non-obese diabetic (NOD) mice. The mice were assessed for vaccine protection against development of hyperglycemia from 12 to 64 weeks of age by assessment of pancreatic inflammation (insulitis) and splenocyte-secreted interferon-gamma and IL-10 cytokine levels.

RESULTS

By 36 weeks of age, from 54% to 80% of the mice in the negative control animal groups (either mock-infected or inoculated with unrelated plasmid or VV) had developed hyperglycemia. Similarly, no statistically significant improvement in protection against diabetes onset was achieved by inoculation with VV expressing CTB::GAD or IL-10 independently. Surprisingly, only 20% of mice co-inoculated with rVV-CTB::GAD + rVV-IL10 developed hyperglycemia by 28 weeks of age. Other treatment groups developed hyperglycemia by 32-36 weeks. After 36 weeks, diabetes incidence no longer increased in any groups until the end of experiment at 64 weeks of age. Histological analysis of pancreatic tissues of hyperglycemic mice revealed high levels of intra-islet insulitis. Analysis of insulitis at termination of the experiment showed that euglycemic mice co-inoculated with VV expressing CTB::GAD and IL-10 had more effectively reduced inflammation in comparison with the other groups.

CONCLUSIONS

A combinatorial vaccination strategy based on VV co-delivery of genes encoding the immunoenhanced autoantigen CTB::GAD and the anti-inflammatory cytokine IL-10 can maintain effective and durable euglycemia and immunological homeostasis in NOD mice with prediabetes.

Molecular targeting of islet autoantigens

Type 1 diabetes of man and animal models results from immune-mediated specific beta cell destruction. Multiple islet antigens are targets of autoimmunity and most of these are not beta cell specific. Immune responses to insulin appear to be essential for the development of diabetes of the NOD mouse. In this review, we will emphasize the unusual manner in which selected autoantigenic peptides (particularly the recently discovered target of BDC2.5 T cells [chromagranin A]) are presented and recognized by autoreactive CD4(+) T cell receptors. We hypothesize that "unusual" structural interactions of specific trimolecular complexes (MHC class II, peptide, and T cell receptors) are fundamental to the escape from the thymus of autoreactive T cells able to cause type 1 diabetes.

Antidiabetic efficacy of bradykinin antagonist R-954 on glucose tolerance test in diabetic type 1 mice

Insulin-dependent diabetes mellitus (type 1 diabetes) is an inflammatory autoimmune disease associated with many complications including nephropathy, retinopathy, neuropathy and hyperalgesia. Experimental evidence has shown that the bradykinin B1 receptor (BKB1-R) is involved in the development of type 1 diabetes and found to be upregulated alongside the disease. In the present study the effects of the selective BKB1-R antagonist the R-954 (Ac-Orn-[Oic(2), alpha-MePhe(5), D-beta Nal(7), Ile(8) ]des-Arg(9)-BK and the BKB1-R agonist des Arg(9)-BK (DBK) were studied on diabetic hyperglycemia. Diabetic type 1 was induced in C57 BL/KsJ mdb male mice by five consecutives doses of STZ (45mg/kg i.p.). A glucose tolerance test (GTT) was performed by an intraperitoneal administration of glucose, 8, 12 and 18days after the diabetes induction. The induction of type 1 diabetes provoked a significant hyperglycemia levels in diabetic mice at 12 and 18days after STZ. The administration of R-954 (400microg/kg i.p.) at 12 and 18days after STZ returned the glycemia levels of this animals to normal values. In addition the administration of DKB (300microg/kg i.p.) significantly potentiated the diabetes-induced hyperglycemia; this effect that was totally reversed by R-954. These results provide further evidence for the implication of BKB1-R in the type 1 diabetes mellitus (insulitis).

A case of WHIM syndrome associated with diabetes and hypothyroidism

The WHIM syndrome is a rare immunological disorder characterized by warts, hypogammaglobulinemia, infections, and myelokathexis. We hypothesized that immunological or genetic mechanisms may link WHIM syndrome and type 1 diabetes. We report that the young girl with WHIM syndrome developed diabetes and transient hypothyroidism. A nonsense mutation (C-->T) truncating the CXC chemokine receptor 4 (CXCR4) C-terminal cytoplasmic tail domain occurred at nucleotide position 1000(R334X) of the CXCR4 gene in one allele of the patient was identified, and the person was diagnosed as having WHIM syndrome. Recent observation suggested that the CXCR4, a G-protein-coupled receptor with a unique ligand, CXCL12, might be involved in the pathogenesis for type 1 diabetes. Taken into consideration the concurrent prevalence of the two disorders and the speculated common pathogenesis associated with the CXCR4, our patient may enable us to understand the genetic damage related to accelerated apoptosis.

Regulatory T cells enter the pancreas during suppression of type 1 diabetes and inhibit effector T cells and macrophages in a TGF-beta-dependent manner

Treg can suppress autoimmune diseases such as type 1 diabetes, but their in vivo activity during suppression remains poorly characterized. In type 1 diabetes, Treg activity has been demonstrated in the pancreatic lymph node, but little has been studied in the pancreas, the site of autoimmune islet destruction. In this study we induced islet-specific Treg from the BDC-6.9 TCR transgenic mouse by activation of T cells in the presence of TGF-beta. These Treg can suppress spontaneous diabetes as well as transfer of diabetes into NOD.scid mice by diabetic NOD spleen cells or activated BDC-2.5 TCR transgenic Th1 effector T cells. In the latter transfer model, we observed infiltration of the pancreas by both effector T cells and Treg, suggesting that Treg are active in the inflammatory site and are not just restricted to the draining lymph node. Within the pancreas, we demonstrate that Treg transfer causes a reduction in the number of effector Th1 T cells and macrophages, and also inhibits effector T-cell cytokine and chemokine production. Although we found no role for TGF-beta in vitro, transfection of effector T cells with a dominant-negative TGF-beta receptor demonstrated that in vivo suppression of diabetes by TGF-beta-induced Treg is TGF-beta-dependent.

Differential transcriptional expression of PPARalpha, PPARgamma1, and PPARgamma2 in the peritoneal macrophages and T-cell subsets of non-obese diabetic mice

BACKGROUND

The peroxisome proliferator-activated receptors (PPARs) have been implicated in immune regulation. We determined the transcriptional expression of the three isoforms, PPARalpha, PPARgamma1, and PPARgamma2 in the peritoneal macrophages, CD4- and CD8-positive lymphocytes in non-obese diabetic (NOD) mice at 5 and 10 weeks of age as well as at diabetic stage.

RESULTS

Compared to the non-obese diabetic resistant (NOR) mice, the peritoneal macrophages of NOD mice expressed increased levels of PPARalpha but reduced levels of PPARgamma2, while PPARgamma1 expression was unchanged in all age groups. CD4-positive lymphocytes expressed low levels of PPARalpha in diabetic NOD mice and greatly reduced expression of PPARgamma2 in all age groups. Unlike peritoneal macrophages and CD4-positive cells, the CD8-positive cells expressed low levels of PPARgamma1 in diabetic NOD mice but no difference in PPARalpha and PPARgamma2 expression was observed compared to NOR mice.

CONCLUSION

The current findings may suggest an important regulatory role of PPARs in the pathogenesis of autoimmune diabetes.

Interleukin-21 is required for the development of type 1 diabetes in NOD mice

OBJECTIVE

Interleukin (IL)-21 is a type 1 cytokine that has been implicated in the pathogenesis of type 1 diabetes via the unique biology of the nonobese diabetic (NOD) mouse strain. The aim of this study was to investigate a causal role for IL-21 in type 1 diabetes.

RESEARCH DESIGN AND METHODS

We generated IL-21R-deficient NOD mice and C57Bl/6 mice expressing IL-21 in pancreatic beta-cells, allowing the determination of the role of insufficient and excessive IL-21 signaling in type 1 diabetes.

RESULTS

Deficiency in IL-21R expression renders NOD mice resistant to insulitis, production of insulin autoantibodies, and onset of type 1 diabetes. The lymphoid compartment in IL-21R-/- NOD is normal and does not contain an increased regulatory T-cell fraction or diminished effector cytokine responses. However, we observed a clear defect in autoreactive effector T-cells in IL-21R-/- NOD by transfer experiments. Conversely, overexpression of IL-21 in pancreatic beta-cells induced inflammatory cytokine and chemokines, including IL-17A, IL17F, IFN-gamma, monocyte chemoattractant protein (MCP)-1, MCP-2, and interferon-inducible protein-10 in the pancreas. The ensuing leukocytic infiltration in the islets resulted in destruction of beta-cells and spontaneous type 1 diabetes in the normally diabetes-resistant C57Bl/6 and NOD x C57Bl/6 backgrounds.

CONCLUSIONS

This work provides demonstration of the essential prodiabetogenic activities of IL-21 on diverse genetic backgrounds (NOD and C57BL/6) and indicates that IL-21 blockade could be a promising strategy for interventions in human type 1 diabetes.

Immunology and genetics of type 1 diabetes

Type 1 diabetes is one of the most well-characterized autoimmune diseases. Type 1 diabetes compromises an individual's insulin production through the autoimmune destruction of pancreatic beta-cells. Although much is understood about the mechanisms of this disease, multiple potential contributing factors are thought to play distinct parts in triggering type 1 diabetes. The immunological diagnosis of type 1 diabetes relies primarily on the detection of autoantibodies against islet antigens in the serum of type 1 diabetes mellitus patients. Genetic analyses of type 1 diabetes have linked human leukocyte antigen, specifically class II alleles, to susceptibility to disease onset. Environmental catalysts include various possible factors, such as viral infections, although the evidence linking infections with type 1 diabetes remains inconclusive. Imbalances within the immune system's system of checks and balances may promote immune activation, while undermining immune regulation. A lack of proper regulation and overactive pathogenic responses provide a framework for the development of autoimmune abnormalities. Type 1 diabetes is a predictable and potentially treatable disease that still requires much research to fully understand and pinpoint the exact triggering events leading to autoimmune activation. In silico research can aid the comprehension of the etiology of complex disease pathways, including Type I diabetes, in order to and help predict the outcome of therapeutic strategies aimed at preserving beta-cell function.

The chemokine-binding protein M3 as a tool to understand the chemokine network in vivo

Murine herpesvirus 68 (MHV-68) codes for a secreted chemokine-binding protein, termed M3, which interacts with a broad range of chemokines with very high affinity, inhibiting chemokine function both in vitro and in vivo. Here we describe the transgenic methodology used to study the role of M3 as an immune modulator in vivo.

Cytokine related therapies for autoimmune disease

In short, manipulation of cytokine pathways shows promise as a mean to tilt the balance of immunity toward tolerance. Effective and regulatory T cells vary in their response to a variety of cytokines. In particular, the ability of certain cytokines, for example, IL-2, to provide vital survival signals to regulatory cells and to trigger death of effector T cells or impede IL-15 driven expansion of memory cells has spurred several trials. The ability of IFNgamma, IL-4, TNFalpha, and lymphotoxin to exert selective effects upon crucial lymphocyte subset populations in vivo may also enable translation into potent therapies.

Reestablishment of microenvironment is necessary to maintain in vitro and in vivo human islet function

Islet transplantation is associated with an elevated rate of early graft failure. The isolation process leads to structural and functional abnormalities. The reestablishment of the cell-matrix relationship is important to modulate the survival and function of islets. Thus, we evaluated the effect of human fibronectin (hFN) and self-assembling peptide nanofiber (SAPNF) in the ability to support islet function in vitro and after transplantation into streptozotocin (STZ)-induced diabetic severe combined immunodeficiency (SCID) mice. Human isolated islets were cultured with hFN or SAPNF for 7 days. Their ability to maintain insulin production/glucose responsiveness over time was evaluated. Islets embedded in hFN, SAPNF, or alone were transplanted into STZ-induced diabetic SCID mice. Islet grafts were removed after 14 days to evaluate insulin content, insulin expression, and apoptosis. SAPNF-entrapped islets maintained satisfactory morphology/viability and capability of glucose-dependent insulin secretion for over 7 days, whereas islets cultured in hFN underwent widespread deterioration. In vivo grafts containing human islets in SAPNF showed remarkably higher insulin content and expression when compared with human islets in hFn or alone. RT-PCR revealed lower caspase-3 expression in SAPNF islets grafts. These studies indicate that the reestablishment of the cell-matrix interactions by a synthetic matrix in the immediate postisolation period is a useful tool to maintain islet functions in vitro and in vivo.

Differential contributions of APC subsets to T cell activation in nonobese diabetic mice

Despite the pivotal role of dendritic cells (DC) in shaping immunity, little is known about their functionality in type 1 diabetes. Moreover, due to the paucity of DC in vivo, functional studies have relied largely upon in vitro-expanded cells to elucidate type 1 diabetes-associated functional abnormalities. In this study, we provide a comprehensive analysis of the functional capabilities of in vivo-derived DC subsets from NOD mice by comparing DC to other NOD APC types and to DC from autoimmune-resistant strains. NOD DC closely resemble those from nonautoimmune strains with respect to costimulation and cytokine production. The exception is the CD8alpha(+)CD11b(-)DC subset which is numerically reduced in NOD spleens, but not in the pancreatic lymph nodes, while DC from both tissues produce little IL-12 in this strain. This defect results in unusual deferral toward macrophage-derived IL-12 in NOD mice; NOD macrophages produce aberrantly high IL-12 levels that can overcompensate for the DC defect in Th1 polarization. APC subset use for autoantigen presentation also differs in NOD mice. NOD B cells overshadow DC at activating islet-reactive T cells, whereas DC and B cells in NOD-resistant mice are functionally comparable. Differential involvement of APC subsets in T cell activation and tolerance induction may prove to be a crucial factor in the selection and expansion of autoreactive T cells.

Antigen presentation of detergent-free glutamate decarboxylase (GAD65) is affected by human serum albumin as carrier protein

The smaller isoform of glutamate decarboxylase (GAD65) is a major autoantigen in type 1 diabetes (TID). Its hydrophobic character requires detergent to keep the protein in solution, which complicates studies of antigen processing and presentation. In this study an attempt was made to replace detergent with human serum albumin (HSA) for in vitro antigen presentation. Different preparations of recombinant human GAD65 solubilized by HSA were incubated with Priess B cells (HLA DRB1*0401) and antigen presentation was tested with HLA DRB1*0401-restricted and epitope-specific T33.1 (GAD65 epitope 274-286) and T35 (GAD65 epitope 115-127) T-cell hybridomas. Specific epitope recognition by T33.1 (274-286) and T35 (115-127) cells varied between the different GAD65/HSA preparations, and a reverse pattern of antigen presentation was detected by the two hybridoma. The HSA-specific T-cell hybridoma 17.9 response to the different GAD65/HSA preparations followed the same pattern as that observed for the T33.1 cells. The content of immunoreactive GAD65 measured with four GAD65 antibodies indicated that the lowest GAD65 concentration resulted in the highest 274-286, but the lowest 115-127 presentation. This suggests that HSA-GAD65 interactions qualitatively affect the epitope specificity of GAD65 presentation. HSA may enhance the 274-286 epitope presentation, while suppressing the 115-127 epitope.