Non-obese Non-diabetic Research Articles

'Fat's chances': Loci for phenotypic dispersion in plasma leptin in mouse models of diabetes mellitus.

BackgroundLeptin, a critical mediator of feeding, metabolism and diabetes, is expressed on an incidental basis according to satiety. The genetic regulation of leptin should similarly be episodic.MethodologyData from three mouse cohorts hosted by the Jackson Laboratory– 402 (174F, 228M) F2 Dilute Brown non-Agouti (DBA/2)×DU6i intercrosses, 142 Non Obese Diabetic (NOD/ShiLtJ×(NOD/ShiLtJ×129S1/SvImJ.H2g7) N2 backcross females, and 204 male Nonobese Nondiabetic (NON)×New Zealand Obese (NZO/HlLtJ) reciprocal backcrosses–were used to test for loci associated with absolute residuals in plasma leptin and arcsin-transformed percent fat (‘phenotypic dispersion’; PDpLep and PDAFP). Individual data from 1,780 mice from 43 inbred strains was also used to estimate genetic variances and covariances for dispersion in each trait.Principal findingsSeveral loci for PDpLep were detected, including possibly syntenic Chr 17 loci, but there was only a single position on Chr 6 for PDAFP. Coding SNP in genes linked to the consensus Chr 17 PDpLep locus occurred in immunological and cancer genes, genes linked to diabetes and energy regulation, post-transcriptional processors and vomeronasal variants. There was evidence of intersexual differences in the genetic architecture of PDpLep. PDpLep had moderate heritability and PDAFP low heritability ; dispersion in these traits was highly genetically correlated r = 0.8).ConclusionsGreater genetic variance for dispersion in plasma leptin, a physiological trait, may reflect its more ephemeral nature compared to body fat, an accrued progressive character. Genetic effects on incidental phenotypes such as leptin might be effectively characterized with randomization-detection methodologies in addition to classical approaches, helping identify incipient or borderline cases or providing new therapeutic targets.

Hypoadiponectinemia in obese and diabetic subjects in the State of Qatar

Background: Obesity is commonly associated with insulin resistance (IR), and is a common cause of type 2 diabetes. Adiponectin is an adipose tissue protein that enhances insulin sensitivity and has anti-atherogenic properties. Objective: This study was done to determine the adiponectin level and its relations to key components of the metabolic syndrome in obese diabetic (OD), obese non-diabetic (OB) and control [non-obese, non-diabetic (NOND)] Qatari subjects. Research design and Methods: We examined 64 (OD), 61 (OB) and 72 (NOND) male and female subjects. After a 12 h overnight fasting, blood samples were withdrawn for determination of plasma glucose, insulin, adiponectin, HbA1C, uric acid, total cholesterol, triglycerides, HDL-C and LDL-C. Results: Plasma levels of adiponectin in OD (10.60 ± 3.64μg/mL) and OB (11.21 ± 3.41μg/mL) were significantly lower than NOND controls (14.73 ± 4.97μg/mL). Significant, inverse correlations were observed between adiponectin levels and BMI (r=-0.241, p<0.05), plasma glucose (r=-0.221, p<0.05), insulin (r=-0.280, p<0.05), C-peptide (r=-0.334, P<0.01), total cholesterol (r=-0.243, p<0.01,), triglycerides (r=-0.438, p<0.01), LDL-C (r=-0.214, p<0.05) and uric acid (r=-0.286, p<0.05). In addition, correlated positively with HDL-C(r=0.386, p<0.01). In multiple regression analysis, only TG was inversely associated with plasma level of adiponectin in all groups. Conclusion: This study provides the first evidence that adiponectin is reduced in Qatari obese subjects with and without diabetes. The measurement of circulating adiponectin among Qatari obese subjects is suggested to monitor cardiovascular disease (CVD) risks. Whether the plasma adiponectin level could be a suitable biomarker for following the clinical progress of CVD among Qatari obese and diabetic subjects warrants further investigation.

Heat shock protein 60 elicits abnormal response in macrophages of diabetes-prone non-obese diabetic mice

Heat shock protein 60 (hsp60) is a target antigen in autoimmune diabetes and injections of human hsp60 for tolerance induction were found to protect non-obese diabetic (NOD) mice, an animal model of human type 1 diabetes, from disease development. We tested whether innate immune cells of NOD mice exhibit an abnormal response to extracellular hsp60. Bone marrow derived macrophages (BMM) were grown from NOD, C57BL/6J, non-obese non-diabetic (NON) mice, and NOD-related congenic variants differing in the Idd-3, Idd-10/18, or major histocompatibility complex (MHC) region. Hsp60-stimulated BMM of NOD mice were found to produce high levels of interleukin (IL)-12(p70). The addition of IL-10 downregulated, whereas cyclooxygenase inhibitors elevated, IL-12(p70) production of activated BMM. BMM of NON, NON–NOD- H-2 g7 as well as of NOD–NON- H-2 nbl mice produced significantly less IL-12(p70) than BMM of NOD mice, indicating that an interaction between the MHC haplotype and non-MHC genes of the NOD mouse is required for hyperresponsiveness to hsp60.

Maternal Environment and Genotype Interact to Establish Diabesity in Mice

Obesity, a major risk factor for type II diabetes, is becoming more prevalent in Western populations consuming high calorie diets while expending less energy both at the workplace and at home. Most human obesity, and probably most type II diabetes as well, reflects polygenic rather than monogenic inheritance. We have genetically dissected a polygenic mouse model of obesity-driven type II diabetes by outcrossing the obese, diabetes-prone, NZO (New Zealand Obese)/HlLt strain to the relatively lean NON (Nonobese Nondiabetic)/Lt strain, and then reciprocally backcrossing obese F1 mice to the lean NON/Lt parental strain. A continuous distribution of body weights was observed in a population of 203 first backcross males. The 22% of first backcross males developing overt diabetes showed highest peripubertal weight gains and earliest development of hyperinsulinemia. We report a complex diabetes-predisposing ("diabesity") QTL (Quantitative Trait Loci) on chromosome 1 contributing significant main effects to increases in body weight, plasma insulin, and plasma glucose. NZO contributed QTL with significant main effects on adiposity parameters on chromosomes 12 and 5. A NON QTL on chromosome 14 interacted epistatically with the NZO obesity QTL on chromosome 12 to increase adiposity. Although the main effect of the diabetogenic QTL on chromosome 1 was on rapid growth rather than adiposity, it interacted epistatically with the obesity QTL on chromosome 12 to increase plasma glucose levels. Additional complex epistatic interactions eliciting significant increases in body weight and/or plasma glucose were found between the NZO-contributed QTL on chromosome 1 and other NZO-contributed QTL on chromosomes 15 and 17, as well as with an NON-contributed QTL on chromosome 2. We further show that certain of these intergenic interactions are predicated on, or enhanced by, the maternal postparturitional environment. We show by cross-fostering experiments that the maternal environmental influence in part is because of the presence of early obesity-inducing factors in the milk of obese F1 dams. We also discuss a strategy for using recombinant congenic strains to separate and reassemble interacting QTL for future study.

Nicotinamide decreases MHC class II but not MHC class I expression and increases intercellular adhesion molecule-1 structures in non-obese diabetic mouse pancreas.

Pancreases of untreated and nicotinamide (NIC)-treated pre-diabetic (10-week-old) and overtly diabetic (25-week-old) female NOD (non-obese diabetic) mice and of NON (non-obese non-diabetic) control mice were studied, with the following results. (1) Islets and ducts of overtly diabetic untreated NOD mice (25-week-old) were found to express low levels of MHC class I and II molecules, like NON controls, and high levels of adhesive molecules. (2) NIC was able to slightly affect glycaemia and insulitis, slowing down diabetes progression. Moreover it significantly decreased MHC class II expression (but not class I) in vivo by week 10, and significantly enhanced intercellular adhesion molecule-1 (ICAM-1) expression, mainly by week 25, within the pancreas, where 5-bromo-2'-deoxyuridine positive nuclei and insulin positive cells were present, demonstrating that a stimulation of endocrine cell proliferation occurs. (3) In addition, NIC partly counteracted the fall of superoxide dismutase levels, observed in untreated diabetic NOD animals. (4) In vitro studies demonstrated that NIC: (i) was able to significantly reduce nitrite accumulation and to increase NAD+NADH content significantly, and (ii) was able to increase the levels of interleukin-4, a T helper 2 lymphocyte (Th2) protective cytokine, and of interferon-alpha (IFN-alpha), which is known to be able to induce MHC class I and ICAM-1 but not MHC class II expression, as well as IFN-gamma, which is also known to be able to induce MHC class I and ICAM-1 expression. The latter, although known to be a proinflammatory Th1 cytokine, has also recently been found to exert an anti-diabetogenic role. This study therefore clearly shows that adhesive mechanisms are ongoing during the later periods of diabetes in pancreatic ducts of NOD mice, and suggests they may be involved in a persistence of the immune mechanisms of recognition, adhesion and cytolysis and/or endocrine regeneration or differentiation processes, as both NIC-increased ICAM-1 expression and 5-bromo-2'-deoxyuridine positivity imply. The effects of NIC on MHC class II (i.e. a reduction) but not class I, and, mainly, on ICAM-1 expression (i.e. an increase), together with the increase in Th2 protective cytokine levels are very interesting, and could help to explain its mechanism of action and the reasons for alternate success or failure in protecting against type 1 diabetes development.

METFORMIN INCREASES CIRCULATING TUMOUR NECROSIS FACTOR α LEVELS IN NON-OBESE NON-DIABETIC PATIENTS WITH CORONARY HEART DISEASE

Metformin reduces insulin resistance and hyperinsulinaemia, as well as lipid levels and body weight. The mechanisms behind these effects are likely to involve intracellular insulin signalling. Recent evidence implicates tumour necrosis factor α (TNF-α) as a modulatory factor on insulin resistance. The present investigation was undertaken to clarify whether metformin affects TNF-α and soluble TNF receptor levels. Sixty non-diabetic men with coronary heart disease were treated with diet and lifestyle advice and lovastatin 40 mg/day during a 4-week run-in period. During this period TNF-α and soluble TNF receptor p75 remained unchanged, whereas soluble TNF receptor p55 increased by 8% (P<0.05). Twelve weeks of metformin treatment increased TNF-α by 33% (P<0.05). This effect was restricted to non-obese patients in whom TNF-α increased by 68% (P<0.01). Soluble TNF receptors p55 and p75 remained unchanged in the whole group, whereas soluble TNF receptor p55 increased by 11% (P<0.05) in non-obese patients. Since metformin reduces insulin resistance both in obese and non-obese subjects but increases TNF-α levels only in the latter, it is concluded that the drug does not exert its effect on insulin resistance through regulation of circulating TNF-α levels.

Effects of sex hormone on the dilatation of urinary tubule and acidophil body in NON mice

The influences of sex hormones on the dilatation of the urinary tubules and acidophil bodies were histologically investigated in NON (Non-Obese Non-diabetic) mice. Although the dilatation of the proximal tubules and acidophil bodies in NON mice were observed only in female but not in male, a slight dilatation and a few bodies were also observed in castrated male NON mice. Moreover, in ovariectomized female NON mice the dilatation and bodies were less compared with intact female NON mice. Estradiol administration induced prominent dilatation and numerous acidophil bodies, while the administration of testosterone showed a complete preventive effect. Therefore, it is suggested that the dilatation of the tubules and the acidophil bodies can be profoundly influenced by sex hormones.

Polymorphism in the mouse Tap-1 gene. Association with abnormal CD8+ T cell development in the nonobese nondiabetic mouse.

Tap-1 and Tap-2 genes code for a heterodimeric peptide transporter required for the normal maturation and surface expression of class I molecules. Polymorphic variants of these MHC encoded genes occur in rats and humans. After failing to amplify a 3' polymerase chain reaction (PCR) product from thymic and splenic cDNA of the nonobese nondiabetic (NON) strain, we considered it possible that Tap-1 polymorphism was present, since cDNA from CBA/J, C57BL/6, BALB/c, and NOD (nonobese diabetic) mice all yielded Tap-1 3' products. Overlapping PCR fragments spanning the highly conserved ATP-binding cassette (ABC) were generated for purposes of restriction endonuclease analysis, studies of IFN-gamma regulation, and sequencing. To avoid amplifying other members of the transporter family, we used a gel-purified 1670-bp Tap-1 PCR "long product" as template for nested PCR. Sequencing revealed three polymorphic alleles. The most divergent was for the NON strain and involved two non-conserved amino acid substitutions (Arg-->Cys397 and Leu-->Arg491) and three silent mutations. NON mice show an abnormal pattern of class I (Kb) expression and a sizeable reduction in the percentage of CD8+ cells in the blood and thymus. In F2 segregants, the low CD8 phenotype mapped to the MHC. Tap-1 genes of NON and C57BL/6 mice were equally sensitive to up-regulation by IFN-gamma. We conclude that the mouse Tap-1 transporter gene, like the Tap-2 of the rat and the Tap-1 and Tap-2 of the human, is polymorphic. The extensive variation and specific codon changes of Tap-1 in the NON mouse raise the possibility that this gene is the MHC locus responsible for altering the intrathymic development of CD8+ T cells.

RFLP analysis of the MHC class III region defines unique haplotypes for the non-obese diabetic, cataract Shionogi and the non-obese non-diabetic mouse strains

The non-obese diabetic (NOD) mouse strain which spontaneously develops diabetes is a model for human Type 1 (insulin-dependent) diabetes mellitus. At least one of several genes controlling diabetes in the NOD mouse has been mapped to the MHC. Although previous experiments have implicated the MHC class II genes in the development of the disease, the existence of other MHC linked susceptibility genes has not been ruled out. In order to identify these susceptibility genes we have further characterized the MHC haplotype of the NOD mouse and two non-diabetic sister strains, the non-obese non-diabetic (NON) and cataract Shionogi (CTS). We have examined the mouse MHC class III region for the presence of homologous genes to 17 newly isolated human MHC class III region genes (G1, G2, G4, G6, G7a/valyl-tRNA synthetase, HSP70, G8, G9, G10, G12, G13, G14, G15, G16, G17 and G18). We detect unique hybridizing DNA fragments for 16 of the 17 genes in six inbred mouse strains (NOD, NON, CTS, B10, BALB/c and CBA/J) indicating that this part of the H-2 region is similar to the human MHC class III region. Using a panel of restriction enzymes we have defined RFLPs for 6 (G2, G6, HSP70, G12, G16, G18) of the 16 cross-hybridizing probes. The RFLPs demonstrate that NOD, NON and CTS mouse strains each have a distinct MHC haplotype in the MHC class III region.

High Susceptibility of Cataract Shionogi (CTS) Mice to Passive Anaphylactic Shock Mediated by Allogeneic IgE and IgG1Monoclonal Antibodies

The susceptibility of cataract Shionogi (CTS) mice as young as 8 to 10 weeks of age to passive anaphylactic shock mediated by anti-benzylpenicilloyl IgE and IgG1 monoclonal antibodies was compared with those of other strains of the same age including sister strains such as nonobese-diabetic (NOD) and nonobese-nondiabetic (NON). When the animals had been treated with killed Bordetella pertussis organisms, potent sensitization, enough to cause lethal shock, was produced by either monoclonal antibody preparation in CTS, NOD, C57BL/6J and DS/Shi strains, but not at all in C3H/He, DBA/2 and BALB/c strains. In the NON strain, lethal shock was elicited in the animals sensitized with the IgG1 antibody but not in those sensitized with the IgE antibody. Without the pertussis pretreatment, sensitization sufficient to cause lethal shock was produced at a high frequency by the IgG1 antibody in CTS and NOD mice but not in the other strains. When the IgE antibody was used, lethal shock was not observed in any of the mouse strains tested except for one CTS mouse. These results indicate that CTS as well as NOD are highly susceptible strains, and that IgG1 antibody is more effective than IgE antibody for producing systemic sensitization for anaphylactic shock. In addition to these findings, the results revealed an age-dependent potentiation of anaphylactic shock in CTS mice. The IgE antibody-mediated lethal shock was produced in all the aged animals of this mouse strain tested without the Bp treatment, but not in aged NOD and NON mice.

A single recessive non-MHC diabetogenic gene determines the development of insulitis in the presence of an MHC-linked diabetogenic gene in NOD mice

To study the genetic control of insulitis in non-obese diabetic (NOD) mice, we performed breeding studies in crosses of NOD with non-diabetic strains, ICR-L-line Ishibe (ILI), non-obese non-diabetic (NON) and C3H/He mice. The ILI mouse serologically shared the same MHC Class I and Class II as the NOD mouse. Insulitis was defined as islets invaded by lymphoid cells. Periductular, perivascular and peri-insular lymphoid cell infiltrations were often observed in NOD mice and appear to be the initial lesion leading to insulitis. Such lesions, however, were found in 1-year-old ICR, ILI, NON and Cataract Shionogi (CTS) mice of the NOD's sister strain. The lymphoid cells did not invade the islets in ICR, ILI, NON and CTS mice. The incidence of insulitis was 0% in F1 generations and 40% in female backcrosses (BC) [(ILI × NOD)F1 × NOD] at 9 weeks of age, 48 and 50% in BC[(NON × NOD)F1 × NOD] and BC[( C3H He × NOD)F1 × NOD] at 1 year of age, respectively. Backcross animals were typed for the MHC to investigate correlation between the development of insulitis and MHC haplotypes. Among the backcross females with insulitis, approximately half the animals were heterozygous for MHC( non nod ) in BC[(NON × NOD)F1 × NOD] and MHC( k nod ) in BC[(C3H × NOD)F1 × NOD]. Among the backcross females with no insulitis, approximately half the animals were homozygous for MHC( nod nod ) in BC[(NON × NOD)F1 × NOD] and in BC[(C3H × NOD)F1 × NOD]. The results suggest that a single recessive non-MHC diabetogenic gene determines the development of insulitis regardless of NOD MHC homozygosity or heterozygosity.

Suppressor T-cell abnormality in NOD mice before onset of diabetes

To investigate the pathological role of suppressor T-cells in non-obese diabetic (NOD) mice, we stimulated splenic T-lymphocytes from diabetes-prone NOD mice with concanavalin A (ConA) and then evaluated their ability to suppress the lymphocyte-proliferative responses to mitogen and allogenic cells. Lymphocytes from NOD mice showed significantly less suppressor ability than did those from BALB c mice and non-obese non-diabetic (NON) mice, the corresponding non-diabetic sister strain of the NOD mouse, both in the mitogen response and in the mixed lymphocyte reaction (MLR). We used monoclonal antibodies and flow cytometry to analyze the lymphocytic surface phenotypes, and found markedly fewer Lyt2 + T-lymphocytes (suppressor/cytotoxic T-lymphocyte) in the NOD mice than in both controls after exposure to ConA. These results suggest that suppressor T-cell activity is already depressed in NOD mice before diabetes begins and that a substantial decrease in the number of suppressor T-cells induced by ConA may explain this depressed suppressor activity. This impairment may contribute to the pathogenesis of type 1 diabetes in NOD mice.

Cell infiltration in various organ and dilatation of the urinary tubule in NON mice

The non-obese non-diabetic (NON) mouse, which shows no glycosuria, is a subline of the non-obese diabetic (NOD) mouse. Cellular infiltrations in various organs were observed by light and electron microscopy in both sexes from 30 to 300 days after birth. These infiltrations were found in the kidney, pancreas, mandibular gland, parotid gland, exorbital lacrimal gland, and thyroid gland, but not in the adrenal gland, sublingual gland, testis and ovary. The infiltrating cells were mononuclear cells, mostly small lymphocytes. The population and frequency of these cellular infiltrations were weak generally; especially the infiltration into the pancreatic islet, which was very weak compared with that in NOD mice. Dilation of the proximal tubule occurred only in the females at 60 days or more after birth and it gradually increased with age. Numerous acidophil bodies appeared in the epithelial cells and the lumen of these dilated urinary tubules. These bodies were PAS-positive and stained with MT, and They had electron-dense complex structures.