The rising number of obese individuals has become a major burden to the healthcare systems worldwide. Obesity includes not only the increase of adipose tissue mass but importantly also the altered cellular functions that collectively lead to a chronic state of adipose tissue inflammation, insulin resistance and impaired wound healing. Adipose tissue undergoing chronic inflammation shows altered cytokine expression and an accumulation of adipose tissue macrophages (ATM). The macrophage migration inhibitory factor (MIF) superfamily consists of MIF and the recently identified homolog D-dopachrome tautomerase (D-DT or MIF-2). MIF and D-DT, which both bind to the CD74/CD44 receptor complex, are differentially expressed in adipose tissue and have distinct roles in adipogenesis. MIF positively correlates with obesity as well as insulin resistance and contributes to adipose tissue inflammation by modulating ATM functions. D-DT, however, is negatively correlated with obesity and reverses glucose intolerance. In this review, their respective roles in adipose tissue homeostasis, adipose tissue inflammation, insulin resistance and impaired wound healing will be reviewed.
Adipose Tissue/*immunology/pathology ; Animals ; Diabetes Mellitus/immunology/pathology ; Humans ; Inflammation/*immunology/pathology ; Insulin Resistance ; Intramolecular Oxidoreductases/analysis/*immunology ; Macrophage Migration-Inhibitory Factors/analysis/*immunology ; Macrophages/immunology/pathology ; Obesity/*immunology/pathology ; *Wound Healing

The rising number of obese individuals has become a major burden to the healthcare systems worldwide. Obesity includes not only the increase of adipose tissue mass but importantly also the altered cellular functions that collectively lead to a chronic state of adipose tissue inflammation, insulin resistance and impaired wound healing. Adipose tissue undergoing chronic inflammation shows altered cytokine expression and an accumulation of adipose tissue macrophages (ATM). The macrophage migration inhibitory factor (MIF) superfamily consists of MIF and the recently identified homolog D-dopachrome tautomerase (D-DT or MIF-2). MIF and D-DT, which both bind to the CD74/CD44 receptor complex, are differentially expressed in adipose tissue and have distinct roles in adipogenesis. MIF positively correlates with obesity as well as insulin resistance and contributes to adipose tissue inflammation by modulating ATM functions. D-DT, however, is negatively correlated with obesity and reverses glucose intolerance. In this review, their respective roles in adipose tissue homeostasis, adipose tissue inflammation, insulin resistance and impaired wound healing will be reviewed.
Adipose Tissue/*immunology/pathology ; Animals ; Diabetes Mellitus/immunology/pathology ; Humans ; Inflammation/*immunology/pathology ; Insulin Resistance ; Intramolecular Oxidoreductases/analysis/*immunology ; Macrophage Migration-Inhibitory Factors/analysis/*immunology ; Macrophages/immunology/pathology ; Obesity/*immunology/pathology ; *Wound Healing

Autoimmune diabetes is a T cell-mediated disease characterized by the autoimmune destruction of pancreatic β-cells and insulin deficiency. It is related to multiple genes. The IDDM1 locus, which lies within the human leukocyte antigen (HLA) and the IDDM2 locus, which is located to the insulin gene region, are two major genetic contributors of susceptibility. Many other loci conferring susceptibility to autoimmune diabetes are being discovered, including PTPN22, CTLA4, IL2RA and IFIH1. In this article, these loci and their possible immunologic mechanisms involved in the pathogenesis of this disease will be reviewed.
Animals ; Diabetes Mellitus, Type 1 ; genetics ; immunology ; pathology ; Genetic Predisposition to Disease ; Humans

OBJECTIVETo investigate the role of T cell and its subsets in the induction of insulitis and type 1 diabetes mellitus (T1DM) in BALB/c mice.

METHODSAutoimmune diabetes mellitus was developed by intraperitoneal injection of 40 mg/kg streptozotocin (STZ) daily for 5 consecutive days in BALB/c mice as sources of donor cells. Spleen cells from diabetic mice were then cultured for 7 days in the stimulation of interleukin-2 (IL-2) to harvest diabetogenic T cells, which were subsequently transferred into normal BALB/c mice recipients. MTT, ELISA, and HE staining were used to analyze the lymphocyte proliferation, cytokine (IL-2, interferon-gamma, IL-4, and IL-10) levels, and pathological changes in pancreatic islets.

RESULTSAs few as 3 x 10(6) diabetogenic T cells successfully induced diabetes mellitus in recipients pretreated with STZ twice, whereas transfer of equal amount of normal splenocytes, T cell-depleted diabetogenic splenocytes, or diabetogenic CD4+ T cells alone in recipients receiving STZ twice pretreatment was proved not to induce diabetes mellitus either. A markedly increased lymphocyte proliferation, high levels of interferon-gamma and IL-2 in the supernatants of diabetogenic T cells were observed. In addition, a markedly enhanced lymphocyte proliferation, a high level of interferon-gamma secretion in serum, and numerous lymphocytes infiltration in pancreatic islets were detected in the diabetic mice induced by diabetogenic T cells transfer.

CONCLUSIONSA novel T1DM murine model is established in STZ-pretreated BALB/c mice by adoptive transfer of diabetogenic T cells. CD4+ T cells with interferon-gamma may promote the onset of diabetes mellitus.

Animals ; Blood Glucose ; metabolism ; Cytokines ; immunology ; Diabetes Mellitus, Experimental ; metabolism ; pathology ; Diabetes Mellitus, Type 1 ; immunology ; pathology ; Disease Models, Animal ; Islets of Langerhans ; cytology ; metabolism ; pathology ; Male ; Mice ; Mice, Inbred BALB C ; T-Lymphocytes ; cytology ; immunology

OBJECTIVETo investigate the autoimmune injuries of diabetic macrovascular disease (aorta) and the protective effects of immunosuppressive agent (cyclosporine A, CsA) on aortic injuries in streptozotocin (STZ)-induced diabetic rats.

METHODSSTZ-induced diabetic rats were assigned randomly to 6 groups which received low (BML or AML, 1 mgxkg(-1)xd(-1)), middle (BMM or AMM, 4 mgxkg(-1)xd(-1)) or high (BMH or AMH, 8 mgxkg(-1)xd(-1)) dose of CsA from 1 week before or after STZ for 8 weeks. Diabetic rats without any treatment, insulin-treated diabetic rats and normal rats were also monitored simultaneously and served as control groups. The pathologic abnormalities of the aorta were verified by HE, Masson staining and electronmicroscopy. The depositions of immunoglobulins (IgG, IgM and IgA) were determined by immunohistochemistry and immunofluorescence methods.

RESULTSAt the end of study, lymphocytes infiltration and collagen content (26 582 +/- 6901) were significantly higher in diabetic aorta than those in non-diabetic aorta (Collagen: 7482 +/- 3491, P < 0.01). The deposited IgG and IgA were also significantly increased in diabetic aorta compared with non-diabetic aorta (IgG: 11 789 +/- 2491 vs. 2518 +/- 1066, P < 0.01; IgA: 17 430 +/- 3159 vs. 1135 +/- 758, P < 0.01). These changes were not affected by insulin while CsA intervention significantly reduced aortic collagen content (BMH: 13 518 +/- 5440, P < 0.01 vs. STZ) and immunoglobulin deposition (BMH: IgG: 7584 +/- 4462; IgA: 6176 +/- 1900, all P < 0.01 vs. STZ). These immunoglobulin deposition changes were confirmed by results of immunofluorescence. Aortic collagen accumulation was positively correlated to aortic immunoglobulin deposition (IgG, r = 0.556, P < 0.01; IgA, r = 0.661, P < 0.01).

CONCLUSIONSOur data suggest that the autoimmune injuries might be a promoting factor in the pathogenesis of the diabetic macrovascular disease which could lead to the development of macrovascular disease. Immunosuppressive agent, such as CsA, could inhibit the abnormal deposition of immunoglobulins and therefore, delay the development of diabetic macrovascular disease in this model.

Animals ; Aorta ; immunology ; pathology ; Aortic Diseases ; etiology ; Cyclosporine ; pharmacology ; Diabetes Mellitus, Experimental ; immunology ; pathology ; Endothelium, Vascular ; drug effects ; pathology ; Immunosuppressive Agents ; pharmacology ; Rats ; Rats, Sprague-Dawley

To investigate whether BCG, lymphtoxin (LT) or bee venom (BV) can prevent insulitis and development of diabetes in non-obese diabetic (NOD) mice, we measured the degree of insulitis and incidence of diabetes in 24 ICR and 96 female NOD mice. NOD mice were randomly assigned to control, BCG-, LT-, and BV-treated groups. The BCG was given once at 6 weeks of age, and LT was given in 3 weekly doses from the age of 4 to 10 weeks. The BV was injected in 2 weekly doses from the age of 4 to 10 weeks. Diabetes started in control group at 18 weeks of age, in BCG group at 24 weeks of age, and in LT- or BV-treated group at 23 weeks of age. Cumulative incidences of diabetes at 25 weeks of age in control, BCG-, LT-, and BV-treated NOD mice are 58, 17, 25, and 21%, respectively. Incidence and severity of insulitis were reduced by BCG, LT and BV treatment. In conclusion, these results suggest that BCG, LT or BV treatment in NOD mice at early age inhibit insulitis, onset and cumulative incidence of diabetes.
Adjuvants, Immunologic/pharmacology* ; Age Factors ; Animal ; Bee Venoms/pharmacology* ; Cholesterol/blood ; Diabetes Mellitus/prevention & control* ; Diabetes Mellitus/immunology ; Diabetes Mellitus, Insulin-Dependent/prevention & control* ; Diabetes Mellitus, Insulin-Dependent/immunology ; Disease Models, Animal ; Female ; Islets of Langerhans/pathology* ; Islets of Langerhans/drug effects ; Lymphotoxin/pharmacology* ; Mice ; Mice, Inbred NOD ; Mycobacterium bovis/immunology* ; Triglycerides/blood

OBJECTIVE: To investigate the effects of subcutaneous administration of insulin on insulitis,beta cell apoptosis and diabetes in non-obese diabetic (NOD) mice, and to explore the mechanism of immune tolerance induced by insulin. METHODS: Sixty female NOD mice were randomly divided into insulin group (n=32) and phosphate buffered saline (PBS) group (PBS group, n=28). Insulin was subcutaneously injected with humulin N (60 microL, 6U)+IFA (60 microL) at 4, 12, 20, and 28 weeks respectively, while the PBS group received PBS (60 microL) + IFA (60 microL). Insulitis and beta cell apoptosis of islets were observed at 12 weeks. IL-4 and IFN-gamma in the sera were measured by enzyme linked immunosorbent assay (ELISA). The expression levels of I-Abeta(g7), IL-4, IFN-gamma, IL-1beta, and Fas mRNA of islets were measured by reverse transcription-polymerase chain reaction (RT-PCR) at 12 weeks. RESULTS: The incidences in the insulin group were significantly lower than those in the PBS group (21.4% vs 71.4% at 30 weeks, 28.6% vs 85.7% at 52 weeks, P<0.05). The insulitis scores in the insulin group were lower than those in the PBS group, but there was no statistical significance. Fas expression on islets and apoptotic beta cell rates in the insulin group were lower than those in the PBS group (P<0.05). In the insulin group, serum IL-4 levels were higher, but IFN-gamma levels were lower than those in the PBS group (P<0.05). The levels of I-Abeta g7, IFN-gamma, IL-1beta and Fas mRNA transcription in islets were lower in insulin group, but IL-4 mRNA levels were higher than those in the PBS group (P<0.05). CONCLUSION The specific autoantigen insulin may induce immune tolerance and prevent diabetes in NOD mice, but it can't block the progression of insulitis. Subcutaneous administration of insulin can induce the regulatory T cells, and make Th1 to Th2 cytokine shifts in system and islets, thus preventing the Fas-mediated beta-cell apoptosis and diabetes.
Animals ; Apoptosis ; drug effects ; Diabetes Mellitus, Experimental ; prevention & control ; Diabetes Mellitus, Type 1 ; prevention & control ; Female ; Injections, Subcutaneous ; Insulin ; administration & dosage ; pharmacology ; Islets of Langerhans ; immunology ; pathology ; Mice ; Mice, Inbred NOD ; Pancreatitis ; prevention & control ; Random Allocation

Due to their high immunostimulatory ability as well as the critical role they play in the maintenance of self-tolerance, dendritic cells have been implicated in the pathogenesis of autoimmune diseases. The non-obese diabetic (NOD) mouse is an animal model of autoimmune type 1 diabetes, in which pancreatic beta cells are selectively destroyed mainly by T cell-mediated immune responses. To elucidate initiation mechanisms of beta cell-specific autoimmunity, we attempted to generate bone marrow-derived dendritic cells from NOD mice. However, our results showed low proliferative response of NOD bone marrow cells and some defects in the differentiation into the myeloid dendritic cells. NOD dendritic cells showed lower expressions of MHC class II, B7-1, B7-2 and CD40, compared with C57BL/6 dendritic cells. In mixed lymphocyte reactions, stimulatory activities of NOD dendritic cells were also weak. Treatment with LPS, INF-gamma and anti-CD40 stimulated NOD dendritic cells to produce IL-12p70. The amount of IL-12, however, appeared to be lower than that of C57BL/6. Results of the present study indicated that there may be some defects in the development of NOD dendritic cells in the bone marrow, which might have an impact on the breakdown of self tolerance.
Animal ; Autoimmune Diseases/pathology ; Autoimmune Diseases/immunology ; Bone Marrow Cells/pathology* ; Bone Marrow Cells/immunology* ; Bone Marrow Cells/chemistry ; Cell Differentiation/immunology ; Cell Differentiation/drug effects ; Dendritic Cells/pathology* ; Dendritic Cells/immunology* ; Dendritic Cells/chemistry ; Diabetes Mellitus, Insulin-Dependent/pathology* ; Diabetes Mellitus, Insulin-Dependent/immunology ; Enzyme-Linked Immunosorbent Assay ; Granulocyte-Macrophage Colony-Stimulating Factor/pharmacology ; Interleukin-12/analysis ; Interleukin-4/pharmacology ; Lipopolysaccharides/pharmacology ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Mice, Inbred NOD ; Obesity

Type 1 diabetes mellitus is caused by the autoimmune destruction of beta cells within the islets. In recent years, innate immunity has been proposed to play a key role in this process. High-mobility group box 1 (HMGB1), an inflammatory trigger in a number of autoimmune diseases, activates proinflammatory responses following its release from necrotic cells. Our aim was to determine the significance of HMGB1 in the natural history of diabetes in non-obese diabetic (NOD) mice. We observed that the rate of HMGB1 expression in the cytoplasm of islets was much greater in diabetic mice compared with non-diabetic mice. The majority of cells positively stained for toll-like receptor 4 (TLR4) were beta cells; few alpha cells were stained for TLR4. Thus, we examined the effects of anti-TLR4 antibodies on HMGB1 cell surface binding, which confirmed that HMGB1 interacts with TLR4 in isolated islets. Expression changes in HMGB1 and TLR4 were detected throughout the course of diabetes. Our findings indicate that TLR4 is the main receptor on beta cells and that HMGB1 may signal via TLR4 to selectively damage beta cells rather than alpha cells during the development of type 1 diabetes mellitus.
Animals ; Diabetes Mellitus, Type 1/immunology/*metabolism/pathology ; Female ; Gene Expression Regulation ; Glucagon-Secreting Cells/immunology/metabolism/pathology ; HMGB1 Protein/*genetics/metabolism ; Humans ; Immunity, Innate ; Insulin-Secreting Cells/immunology/metabolism/*pathology ; Macrophages/immunology/pathology ; Mice ; Mice, Inbred C57BL ; Mice, Inbred NOD ; Necrosis ; Protein Binding ; Signal Transduction ; Toll-Like Receptor 4/*antagonists & inhibitors/genetics/immunology

Nonspecific inflammatory response is the major cause for failure of islet grafts at the early phase of intraportal islet transplantation (IPIT). Bilirubin, a natural product of heme catabolism, has displayed anti-oxidative and anti-inflammatory activities. The present study has demonstrated that bilirubin protected islet grafts by inhibiting nonspecific inflammatory response in a syngeneic rat model of IPIT. The inflammation-induced cell injury was mimicked by exposing cultured rat insulinoma INS-1 cells to cytokines (IL-1beta, TNF-alpha and IFN-gamma) in in vitro assays. At appropriate lower concentrations, bilirubin significantly attenuated the reduced cell viability and enhanced cell apoptosis induced by cytokines, and protected the insulin secretory function of INS-1 cells. Diabetic inbred male Lewis rats induced by streptozotocin underwent IPIT at different islet equivalents (IEQs) (optimal dose of 1000, and suboptimal doses of 750 or 500), and bilirubin was administered to the recipients every 12 h, starting from one day before transplantation until 5 days after transplantation. Administration of bilirubin improved glucose control and enhanced glucose tolerance in diabetic recipients, and reduced the serum levels of inflammatory mediators including IL-1beta, TNF-alpha, soluble intercellular adhesion molecule 1, monocyte chemoattractant protein-1 and NO, and inhibited the infiltration of Kupffer cells into the islet grafts, and restored insulin-producing ability of transplanted islets.
Animals ; Apoptosis/drug effects/immunology ; Bilirubin/*administration & dosage/pharmacology ; Cell Line, Tumor ; Cytokines/immunology/metabolism ; Diabetes Mellitus, Experimental/*drug therapy/*immunology ; Inflammation ; Inflammation Mediators/immunology/metabolism ; Islets of Langerhans/drug effects/*immunology/injuries/pathology ; *Islets of Langerhans Transplantation ; Male ; Oxidative Stress/drug effects/immunology ; Rats ; Rats, Inbred Lew ; Transplantation, I