Islet Lesions Research Articles

Conditioned Media from Deer Antler Stem Cells Effectively Alleviate Type 1 Diabetes Mellitus Possibly via Inhibiting the NF-κB Signaling Pathway.

Type 1 diabetes mellitus (T1D) represents a severe threat to human health. Persistent hyperglycemia and dyslipidemia can lead to damaged liver function, while effective interventions for these complications are currently lacking. Deer antler stem cells (AnSCs), a novel type of adult stem cells, significantly reduced liver injury, which was speculated to be achieved through the paracrine pathway. In this study, AnSC-conditioned medium (AnSC-CM) was used to treat C57BL/6 mice with T1D symptoms induced by streptozotocin (STZ). The therapeutic effects of AnSC-CM on T1D were evaluated, and the underlying mechanism was investigated. It was shown that AnSC-CM alleviated the T1D symptom: decreased body weight, increased blood glucose levels and islet lesions, and reduced insulin secretion. Moreover, AnSC-CM treatment improved liver function and mitigated liver injury in T1D mice. Impressively, the therapeutic effects of AnSC-CM on T1D were better than those of bone marrow mesenchymal stem cell-CM (BMSC-CM). The mechanistic study revealed that AnSC-CM significantly downregulated the NF-κB signaling pathway in both pancreatic and liver tissues. Therapeutic effects of AnSC-CM on STZ-induced T1D and liver injury may be achieved through targeting the NF-κB signaling pathway.

Antidiabetic activity of a Flavonoid-Rich extract from flowers of Wisteria sinensis in type 2 diabetic mice via activation of the IRS-1/PI3K/Akt/GLUT4 pathway

• WS-FRE ameliorated a series of diabetes-related indices. • WS-FRE promoted GLUT4 translocation and expression by activating PI3K/Akt pathway. • WS-FRE ameliorated pathological changes of insulin-sensitive tissues. • WS-FRE regulated glucose metabolism through IRS-1/PI3K/Akt/GLUT4 pathway. The present study aimed to investigate anti-diabetic activities of a flavonoid-rich extract from Wisteria sinensis (WS-FRE). In vitro , WS-FRE significantly promote the translocation of GLUT4 (Glucose transporter 4) to the plasma membrane. Mechanisms analysis revealed that WS-FRE enhanced glucose uptake via activation of Akt and GLUT4. In vivo , 4-week treatment of WS-FRE alleviated the typical symptoms including hyperglycemia, glucose intolerance, hyperinsulinemia and dyslipidemia. Histopathological examinations revealed that WS-FRE relieved hepatic steatosis, adipocyte hypertrophy and pancreatic islet lesion to a certain extent in diabetic mice. Western blot analysis indicated that WS-FRE resulted in the suppression of IRS-1 serine phosphorylation and an elevation of PI3K p85, Akt phosphorylation and GLUT4 expression in insulin target tissues, which contributes to improving insulin sensitivity in peripheral tissues and thereby ameliorating glucose metabolism in diabetic mice. Diverse anti-diabetic effects of WS-FRE may be attributed to regulation of GLUT4, IRS-1 serine phosphorylation, PI3K phosphorylation and Akt phosphorylation.

Functional and Morphological Characteristics of Pancreatic Islet Lesions Induced by Quinolone Antimicrobial Agent Gatifloxacin in Rats

We characterized pancreatic islet lesions induced by several quinolones using functional and morphological examinations of the pancreatic islets in male rats orally administered gatifloxacin, lomefloxacin, or levofloxacin at 300 mg/kg for 14 consecutive days. Consequently, in contrast to lomefloxacin or levofloxacin, gatifloxacin increased serum glucose and glycosylated albumin on day 14 and elevated serum glucose tended to decrease insulin in the intravenous glucose tolerance test. Microscopically, only gatifloxacin induced cytoplasmic vacuoles containing eosinophilic homogenous contents in islet cells. Immunohistochemical examination revealed that vacuolated islet cells were positively stained for insulin, demonstrating they were pancreatic β cells. Electron microscopy showed that the cytoplasmic vacuoles represented dilated cisterna of the rough endoplasmic reticulum filled with electron-lucent materials in pancreatic β cells. Moreover, insulin secretory granules were drastically decreased in vacuolated islet cells, suggesting impaired insulin synthesis and/or transport. This gatifloxacin-induced pancreatic toxicity in rats was considered to be associated with high pancreatic drug distribution. These results demonstrated that gatifloxacin provoked functional and morphological pancreatic β cell alteration associated with impaired insulin synthesis and/or transport, leading to hyperglycemia.

The islet endothelial cell: a novel contributor to beta cell secretory dysfunction in diabetes

The pancreatic islet is highly vascularised, with an extensive capillary network. In addition to providing nutrients and oxygen to islet endocrine cells and transporting hormones to the peripheral circulation, islet capillaries (comprised primarily of islet endothelial cells) are an important source of signals that enhance survival and function of the islet beta cell. In type 2 diabetes, and animal models thereof, evidence exists of morphological and functional abnormalities in these islet endothelial cells. In diabetes, islet capillaries are thickened, dilated and fragmented, and islet endothelial cells express markers of inflammation and activation. In vitro data suggest that this dysfunctional islet endothelial phenotype may contribute to impaired insulin release from the beta cell. This review examines potential candidate molecules that may mediate the positive effects of islet endothelial cells on beta cell survival and function under normal conditions. Further, it explores possible mechanisms underlying the development of islet endothelial dysfunction in diabetes and reviews therapeutic options for ameliorating this aspect of the islet lesion in type 2 diabetes. Finally, considerations regarding differences between human and rodent islet vasculature and the potentially unforeseen negative consequences of strategies to expand the islet vasculature, particularly under diabetic conditions, are discussed.

Imagerie des récepteurs du GLP-1 dans l’exploration des sécrétions inappropriées d’insuline

Endogenous hyperinsulinemic hypoglycemia is a rare disorder (incidence 2–4/Mio/year). In adult patients, the differential diagnosis includes benign and malignant insulinoma, insulinoma in the context of MEN-1 and nesidioblastosis whereby benign insulinoma is the most frequent diagnosis. The preoperative localization of benign insulinomas is challenging using conventional imaging procedures since these lesions are small (0.5–2 cm). GLP-1R imaging (SPECT/CT and PET/CT) using 111 In-DOTA-exendin-4 and a 68 Ga-DOTA-exendin-4, respectively and is an emerging technique targeting the GLP-1R expressed in very high density on insulinomas. All patients included in the prospective studies had a confirmed endogenous hyperinsulinemic hypoglycemia with neurogylcopenic symptoms. GLP-1R imaging using SPECT/CT ( n = 30) showed a sensitivity of 95% in detecting insulinomas (gold standard: histology), whereas conventional imaging exhibited a sensitivity of 47%. The follow-up study that compared GLP-1R SPECT/CT with PET/CT technique (ongoing study) confirmed the high sensitivity of this imaging procedure with an advantage for the PET/CT technique. Patients with NEM-1 develop multicentric pancreatic islet tumors, the most common functional ones being gastrinomas and insulinomas. Surgery is the only treatment option. However, the surgical intervention should be limited as surgery cannot cure patients with MEN-1. It is therefore, mandatory to correctly localize tumor lesions. The experience with 6 patients suggests that adding GLP-1R imaging to conventional imaging is a helpful tool in differentiating insulinomas from other pancreatic islet lesions. Adding GLP-1R imaging to conventional imaging is a very useful technique in preoperatively localizing benign insulinomas and insulinomas in the context of MEN-1.

Common mechanisms involved in Alzheimer's disease and type 2 diabetes: a key role of chronic bacterial infection and inflammation.

Strong epidemiologic evidence and common molecular mechanisms support an association between Alzheimer's disease (AD) and type 2-diabetes. Local inflammation and amyloidosis occur in both diseases and are associated with periodontitis and various infectious agents. This article reviews the evidence for the presence of local inflammation and bacteria in type 2 diabetes and discusses host pathogen interactions in chronic inflammatory disorders. Chlamydophyla pneumoniae, Helicobacter pylori and spirochetes are demonstrated in association with dementia and brain lesions in AD and islet lesions in type 2 diabetes. The presence of pathogens in host tissues activates immune responses through Toll-like receptor signaling pathways. Evasion of pathogens from complement-mediated attack results in persistent infection, inflammation and amyloidosis. Amyloid beta and the pancreatic amyloid called amylin bind to lipid bilayers and produce Ca(2+) influx and bacteriolysis. Similarly to AD, accumulation of amylin deposits in type 2 diabetes may result from an innate immune response to chronic bacterial infections, which are known to be associated with amyloidosis. Further research based on an infectious origin of both AD and type 2 diabetes may lead to novel treatment strategies.

Endocrine Pancreas in Cats With Diabetes Mellitus.

Pancreatic amyloidosis and loss of α and β cells have been shown to occur in cats with diabetes mellitus, although the number of studies currently available is very limited. Furthermore, it is not known whether pancreatic islet inflammation is a common feature. The aims of the present study were to characterize islet lesions and to investigate whether diabetic cats have inflammation of the pancreatic islets. Samples of pancreas were collected postmortem from 37 diabetic and 20 control cats matched for age, sex, breed, and body weight. Histologic sections were stained with hematoxylin and eosin and Congo red; double labeled for insulin/CD3, insulin/CD20, insulin/myeloperoxidase, insulin/proliferating cell nuclear antigen, and glucagon/Ki67; and single labeled for amylin and Iba1. Mean insulin-positive cross-sectional area was approximately 65% lower in diabetic than control cats (P = .009), while that of amylin and glucagon was similar. Surprisingly, amyloid deposition was similar between groups (P = .408). Proliferation of insulin- and glucagon-positive cells and the number of neutrophils, macrophages, and T (CD3) and B (CD20) lymphocytes in the islets did not differ. The presence of T and B lymphocytes combined tended to be more frequent in diabetic cats (n = 8 of 37; 21.6%) than control cats (n = 1 of 20; 5.0%). The results confirm previous observations that loss of β cells but not α cells occurs in diabetic cats. Islet amyloidosis was present in diabetic cats but was not greater than in controls. A subset of diabetic cats had lymphocytic infiltration of the islets, which might be associated with β-cell loss.

Plasticity of Schwann cells and pericytes in response to islet injury in mice

Islet Schwann (glial) cells and pericytes are the microorgan's accessory cells positioned at the external and internal boundaries facing the exocrine pancreas and endothelium, respectively, adjacent to the endocrine cells. Plasticity of glial cells and pericytes is shown in the glial scar formation after injury to the central nervous system. It remains unclear whether similar reactive cellular responses occur in insulitis. We applied three-dimensional (3D) histology to perform qualitative and quantitative analyses of the islet Schwann cell network and pericytes in normal, streptozotocin-injected (positive control of gliosis) and NOD mouse models. Vessel painting paired with immunostaining of mouse pancreatic tissue was used to reveal the islet Schwann cells and pericytes and their association with vasculature. Transparent islet specimens were prepared by optical clearing to facilitate 3D confocal microscopy for panoramic visualisation of the tissue networks. In-depth microscopy showed that the islet Schwann cell network extends from the peri-islet domain into the core. One week after streptozotocin injection, we observed intra-islet perivascular gliosis and an increase in pericyte density. In early/moderate insulitis in the NOD mice, perilesional gliosis occurred at the front of the lymphocytic infiltration with atypical islet Schwann cell morphologies, including excessive branching and perivascular gliosis. Meanwhile, pericytes aggregated on the walls of the feeding arteriole at the peri- and intralesional domains with a marked increase in surface marker density. The reactive cellular responses demonstrate plasticity and suggest a stop-gap mechanism consisting of the Schwann cells and pericytes in association with the islet lesion and vasculature when injury occurs.

Immunohistochemical Investigation of F344/N Rat Islet Cell Tumors from National Toxicology Program Studies

In this study, we have investigated the immunoexpression of peptide hormones and mediators associated with human islet cell tumors in a group of proliferative islet cell lesions in F344 rats including islet cell hyperplasias, adenomas, and carcinomas, as defined by conventional histopathologic criteria. All proliferative islets expressed synaptophysin, although decreased expression intensity was observed in hyperplasias and adenomas. Most of the proliferative lesions expressed insulin, which generally decreased as lesions progressed toward malignancy. The distribution of glucagon, somatostatin, and gastrin-expressing cells was altered in proliferative islet lesions but did not comprise a large proportion of cells. Islet cell tumors were associated with increased nuclear expression of cyclin-dependent kinase 4 as well as increased proliferating cell nuclear antigen and decreased β-catenin expression. c-Myelocytomatosis oncogene expression was variable. This is the first study to describe the immunophenotype of islet cell tumors in the F344 rat and to show that islet cell tumors in the F344 rat exhibit similarities in protein expression to the human counterpart.

Protective Role of Estrogen-induced miRNA-29 Expression in Carbon Tetrachloride-induced Mouse Liver Injury

Previous studies have indicated that female animals are more resistant to carbon tetrachloride (CCl(4))-induced liver fibrosis than male animals, and that estradiol (E(2)) treatment can inhibit CCl(4)-induced animal hepatic fibrosis. The underlying mechanism governing these phenomena, however, has not been fully elucidated. Here we reported the role of estrogen-induced miRNA-29 (miR-29) expression in CCl(4)-induced mouse liver injury. Hepatic miR-29 levels were differentially regulated in female and male mice during CCl(4) treatment. Specifically, the levels of miR-29a and miR-29b expression were significantly decreased in the livers of male, but not female, mice following 4 weeks of CCl(4) treatment. The down-regulation of miR-29a and miR-29b in male mouse livers correlated with the early development of liver fibrosis, as indicated by increased expressions of fibrotic markers in male mice relative to female mice. In addition, E(2) was maintained at a higher level in female mice than in male mice. In contrast to TGF-β1 that decreased miR-29a/b expression in murine hepatoma IAR20 cells and normal hepatocytes, E(2) enhanced the expression of miR-29a/b through suppression of the nuclear factor-κB (NF-κB) signal pathway, which negatively regulates miR-29 expression. Furthermore, both E(2) treatment and intravenous injection of the recombinant adenovirus expressing miR-29a/b markedly increased the miR-29a/b level and attenuated the expression of fibrotic markers in mouse livers during CCl(4) treatment, supporting the protective role of E(2)-induced miR-29 in CCl(4)-induced hepatic injury. In conclusion, our results collectively demonstrate that estrogen can inhibit CCl(4)-induced hepatic injury through the induction of hepatic miR-29.

An Atypical Case of Islet Cell Hyperplasia in a Wistar Rat

The present article describes an unusual proliferative islet finding observed incidentally in a young male Wistar rat in a 2-week toxicity study. Histologically, the islet lesion was characterized by diffuse enlargement of the islets, which consisted of peripheral proliferation of non-insulin-containing islet cells surrounding normal-appearing insulin-containing cells in the center. To the authors' knowledge, this is the first report of spontaneous proliferative islet lesion composed of non-insulin-containing cells in young rats.

Viruses and Cytotoxic T Lymphocytes in Type 1 Diabetes

Histopathological studies on pancreas tissues from individuals with recent-onset type 1 diabetes (T1D) consistently find that CD8 T cells substantially contribute to the formation of islet lesions. CD8 T cells reactive against islet-associated antigens can also be found in blood samples from T1D patients. Mechanistic studies on the pathogenic role of this T cell subset have mostly focused on two animal models, i.e., the non-obese diabetic mouse and the virally induced rat insulin promoter-lymphocytic choriomeningitis virus model. Data were obtained in support of a role for viral infection in expanding a population of diabetogenic cytotoxic T lymphocytes. In view of the theorized association of viral infection with initiation of islet autoimmunity and progression to clinically overt disease, CD8 T cells thus represent an attractive target for immunotherapy. We will review here arguments in favor of a pivotal role for CD8 T cells in driving T1D development and speculate on etiologic agents that may provoke their aberrant activation.

Effects of Estradiol Treatment and/or Ovariectomy on Spontaneous Hemorrhagic Lesions in the Pancreatic Islets of Sprague-Dawley Rats

The present study was conducted to investigate the effect of estradiol treatment and/or ovariectomy (OVX) on non-neoplastic lesions in the pancreatic islets of Sprague-Dawley rats. Males were divided into non-treatment (naïve) and beta-estradiol 3-benzoate (EB) treatment groups and females into naïve, sham-operation, OVX, and OVX plus EB treatment groups. EB was subcutaneously administered once a week from seven to twenty-six weeks of age. The animals were euthanized at twelve, eighteen, and twenty-six weeks of age, and the serum estradiol concentrations were measured in conjunction with the pancreatic islet histopathology. The histological stages of pancreatic findings were classified into three groups, hemorrhagic, fibrotic, and inflammatory lesions, and the incidence of each type of lesion was enumerated. In males, both the total and individual incidence of pancreatic lesions increased age dependently in the naïve group. EB treatment significantly decreased the total incidence at twenty-six weeks. This alteration consisted of fibrotic and inflammatory lesions, but not hemorrhagic lesions. Additionally, the incidence of hemorrhagic lesions was at the same level between male naïve and male EB groups at twelve weeks, despite a markedly higher concentration of serum estradiol in the EB group. In females, a similar tendency was seen, and the total incidence was generally low in the naïve group, whereas it was increased by OVX. OVX plus EB treatment tended to decrease the incidence accompanied by a marked increase in estradiol concentrations. In conclusion, estrogen was shown to inhibit the development of pancreatic islet lesions toward inflammation and fibrosis but did not inhibit the occurrence of hemorrhagic lesions.

Role of Bv8 in neutrophil-dependent angiogenesis in a transgenic model of cancer progression

The secreted Bv8 protein has been recently characterized as a regulator of myeloid cell mobilization and a neutrophil-derived mediator of tumor angiogenesis in several xenografts, but its role in tumor progression in an endogenous setting was unknown. The rat insulin promoter (RIP)-T-antigen (Tag) is a well characterized transgenic mouse model of multistage pancreatic beta-cell tumorigenesis. Also, the role of neutrophils in RIP-Tag angiogenic switching, as assessed by systemic ablation using anti-Gr1 antibodies at different stages of tumor progression, has been recently described. Here, we show that early treatment of RIP-Tag mice with anti-Bv8 antibodies resulted in a significant reduction in the number of angiogenic islets relative to control antibody-treated mice, implicating Bv8 in the angiogenic switch during neoplasia. Histological analysis showed a significant reduction in vascular surface areas in hyperplastic and angiogenic lesions in pancreatic islets from anti-Bv8-treated mice. Anti-Bv8 treatment also inhibited the mobilization and homing of CD11b+Gr1+ cells to the peripheral blood and the emerging neoplastic lesions. However, anti-Bv8 treatment had no effect on tumor vascularization or burden when initiated at later stages of tumor progression. The stage-dependent efficacy of anti-Bv8 treatment appears remarkably similar to that reported after neutrophil ablation, suggesting that Bv8 is an important mediator of neutrophil-dependent angiogenesis in this transgenic model. In summary, our studies verify a role for Bv8 in the mobilization and recruitment of myeloid cells and in the induction of tumor angiogenesis in the early stages of neoplastic progression.

Effects of Micronutrients on Oxidative Stress and Islet Function in Type 1 Diabetes Mellitus Rats: Relationships to Th2 Type Cytokines, Interleukin-4, and Interluekin-10

To observe the effects of the micronutrients on oxidative and autoimmune destruction of islets so as to prevent a person from the onset and development of type 1 Diabetes Mellitus (T1DM), the interleukin-4 and interleukin-10 expressions of lymphocytes in peripheral blood and spleen of T1DM rats were determined by flow cytometry. GSH-Px activity and MDA level in the rats' pancreas were measured using biochemical methods. The insulin contents in serum and β cell insulin secret storage were tested by RIA and IHC, respectively. There was an increase in the percentages of IL-4 and IL-10 positive lymphocytes in the peripheral blood and spleen of the groups of rats supplemented with various combinations of micronutrients (p <0.01 and p <0.05, respectively); the blood glucose concentration decreased (p <0.05); both the functional β cell in islets and the insulin content in pancreatic tissue increased (p <0.05 and p <0.01); the GSH-Px activity and MDA level of pancreas in the rats enhanced and decreased respectively (p <0.01 and p <0.05). The results suggest that micronutrients may alleviate the islet lesions by upregulating the expressions of IL-4 and IL-10 and lowering oxidative stress in diabetic rats.

Analysis of p27Kip1 Expression in Insulinomas Developed in Pancreatic β-cell Specific Men1 Mutant Mice

Multiple Endocrine Neoplasia type 1 (MEN1) is a hereditary disease characterised by the occurrence of multiple endocrine tumours. The biological functions of the responsible gene, MEN1, and its encoded protein, menin, remain so far largely elusive. The recent generation of Men1 mutant mice by our group and other laboratories provides powerful tools allowing for the identification of cellular and molecular events that occur after gene disruption. Interestingly, it has been recently reported that p27(Kip1) expression is regulated by menin and that decreased p27(Kip1) expression can be found in MEN1 insulinomas and parathyroid adenomas. In order to address whether and when p27(Kip1) expression alters during insulinoma development in pancreatic beta-cell-specific Men1 mutant mice, we analysed p27(Kip1) expression in islet lesions from mutant mice at different ages. Our data revealed that p27(Kip1) protein expression was reduced in 40 out of 52 (77%) insulinomas analysed, whereas the remaining 12 insulinomas (23%) did not show altered p27(Kip1) expression. No difference between the insulinomas with and without decreased p27(Kip1) expression could be observed in terms of histological features or menin inactivation. Furthermore, our analysis on hyperplastic and dysplastic islets developed in young mutant mice showed the lack of detectable alteration in p27(Kip1) expression, despite evident loss of menin expression in a substantial proportion of islet cells. Our work confirms the altered p27(Kip1) expression reported in tumours from MEN1 patients, whereas it suggests that other molecular events may also participate in the tumorigenesis process initiated by the Men1 gene inactivation.

Noninvasive imaging of pancreatic inflammation and its reversal in type 1 diabetes

A major stumbling block for research on and treatment of type 1 diabetes is the inability to directly, but noninvasively, visualize the lymphocytic/inflammatory lesions in the pancreatic islets. One potential approach to surmounting this impediment is to exploit MRI of magnetic nanoparticles (MNP) to visualize changes in the microvasculature that invariably accompany inflammation. MNP-MRI did indeed detect vascular leakage in association with insulitis in murine models of type 1 diabetes, permitting noninvasive visualization of the inflammatory lesions in vivo in real time. We demonstrate, in proof-of-principle experiments, that this strategy allows one to predict, within 3 days of completing treatment with an anti-CD3 monoclonal antibody, which NOD mice with recent-onset diabetes are responding to therapy and may eventually be cured. Importantly, an essentially identical MNP-MRI strategy has previously been used with great success to image lymph node metastases in prostate cancer patients. This success strongly argues for rapid translation of these preclinical observations to prediction and/or stratification of type 1 diabetes and treatment of individuals with the disease; this would provide a crucially needed early predictor of response to therapy.

Islet amyloid: a critical entity in the pathogenesis of type 2 diabetes.

Islet amyloid deposition is a pathogenic feature of type 2 diabetes, and these deposits contain the unique amyloidogenic peptide islet amyloid polypeptide. Autopsy studies in humans have demonstrated that islet amyloid is associated with loss of beta-cell mass, but a direct role for amyloid in the pathogenesis of type 2 diabetes cannot be inferred from such studies. Animal studies in both spontaneous and transgenic models of islet amyloid formation have shown that amyloid forms in islets before fasting hyperglycemia and therefore does not arise merely as a result of the diabetic state. Furthermore, the extent of amyloid deposition is associated with both loss of beta-cell mass and impairment in insulin secretion and glucose metabolism, suggesting a causative role for islet amyloid in the islet lesion of type 2 diabetes. These animal studies have also shown that beta-cell dysfunction seems to be an important prerequisite for islet amyloid formation, with increased secretory demand from obesity and/or insulin resistance acting to further increase islet amyloid deposition. Recent in vitro studies suggest that the cytotoxic species responsible for islet amyloid-induced beta-cell death are formed during the very early stages of islet amyloid formation, when islet amyloid polypeptide aggregation commences. Interventions to prevent islet amyloid formation are emerging, with peptide and small molecule inhibitors being developed. These agents could thus lead to a preservation of beta-cell mass and amelioration of the islet lesion in type 2 diabetes.

Protective effects of probucol treatment on pancreatic beta-cell function of SZ-induced diabetic APA hamsters.

To clarify whether oxidative stress is involved in the pathogenesis of islet lesions of diabetic animals, the effects of probucol (PB), an antioxidant and anti-hyperlipidemia agent, on the islets in streptozotocin (SZ)-induced diabetic APA hamsters in the acute and chronic phases of diabetes were examined. The control (CB group) and diabetic (SZ group) hamsters were treated with PB (1% in the diet) for 4 weeks from several days after SZ injection as the acute diabetic group, or 8 weeks from 6 weeks after SZ injection as the chronic diabetic group. Glucose tolerance test revealed that PB treatment decreased the high serum glucose level after glucose injection in the diabetic APA hamsters in the acute diabetic phase. Immunohistochemistry revealed that PB treatment significantly increased the percentage of the insulin positive area in the diabetic hamsters pancreata in both the acute and chronic phases. In addition, 4-hydroxy-2-nonenal (4HNE; an oxidative stress marker) positive cells were slightly reduced by PB treatment in the acute diabetic phase. Double-immunostaining for insulin and PCNA (proliferating cell nuclear antigen) revealed that elevation of the percentage of insulin and PCNA double-positive cells against insulin-positive cells was seen in the islets of PB-treated diabetic hamsters, but the difference was not significant compared with untreated diabetic hamsters (p = 0.07). In semi-quantitative RT-PCR, the expression of two genes, Reg (Regenerating gene) and INGAP (islet neogenesis associated protein), in the diabetic APA hamsters was significantly increased compared to the control groups in both diabetic phases. PB treatment significantly reduced Reg expression in the chronic diabetic phase. These data suggest that PB treatment in SZ-injected diabetic hamsters partially restored beta-cell function through acting as an antioxidant and induced higher expression of Reg and INGAP genes in the pancreas of hamsters.

Purified allogeneic hematopoietic stem cell transplantation blocks diabetes pathogenesis in NOD mice.

Purified hematopoietic stem cells (HSCs) were transplanted into NOD mice to test whether development of hyperglycemia could be prevented. Engraftment of major histocompatibility complex-mismatched HSCs was compared with bone marrow (BM) grafts. HSCs differed from BM because HSCs were more strongly resisted and HSC recipients retained significant levels of NOD T-cells, whereas BM recipients were full donor chimeras. Despite persistent NOD T-cells, all HSC chimeras were protected from hyperglycemia, and attenuation of islet lesions was observed. T-cell selection was altered in allogeneic HSC recipients as demonstrated by deletion of both donor and host superantigen-specific T-cells. Syngeneic and congenic hematopoietic cell transplants were also performed to differentiate the influence of the preparative regimen(s) versus the allografts. Unlike the allogeneic HSC transplantations, syngeneic or congenic grafts did not retard diabetes development. In a pilot study, overtly diabetic NOD mice were cured by co-transplantation of allogeneic HSCs and donor-matched islets. We conclude that allogeneic HSC transplants block allo- and autoimmunity, despite residual host T-cell presence. These data demonstrate for the first time that purified HSC grafts block development of autoimmune diabetes and illuminate how HSC grafts alter thymic and peripheral T-cell responses against auto- and alloantigens.