Lifespan effects in male UM-HET3 mice treated with sodium thiosulfate, 16-hydroxyestriol, and late-start canagliflozin.

Genetically heterogeneous UM-HET3 mice born in 2020 were used to test possible lifespan effects of alpha-ketoglutarate (AKG), 2,4-dinitrophenol (DNP), hydralazine (HYD), nebivolol (NEBI), 16α-hydroxyestriol (OH_Est), and sodium thiosulfate (THIO), and to evaluate the effects of canagliflozin (Cana) when started at 16 months of age. OH_Est produced a 15% increase (p = 0.0001) in median lifespan in males but led to a significant (7%) decline in female lifespan. Cana, started at 16 months, also led to a significant increase (14%, p = 0.004) in males and a significant decline (6%, p = 0.03) in females. Cana given to mice at 6 months led, as in our previous study, to an increase in male lifespan without any change in female lifespan, suggesting that this agent may lead to female-specific late-life harm. We found that blood levels of Cana were approximately 20-fold higher in aged females than in young males, suggesting a possible mechanism for the sex-specific disparities in its effects. NEBI was also found to produce a female-specific decline (4%, p = 0.03) in lifespan. None of the other tested drugs provided a lifespan benefit in either sex. These data bring to 7 the list of ITP-tested drugs that induce at least a 10% lifespan increase in one or both sexes, add a fourth drug with demonstrated mid-life benefits on lifespan, and provide a testable hypothesis that might explain the sexual dimorphism in lifespan effects of the SGLT2 inhibitor Cana.

Contributions of mouse genetic strain background to age-related phenotypes in physically active HET3 mice.

We assessed aging hallmarks in skin, muscle, and adipose in the genetically diverse HET3 mouse, and generated a broad dataset comparing these to individual animal diagnostic SNPs from the 4 founding inbred strains of the HET3 line. For middle- and old-aged HET3 mice, we provided running wheel exercise to ensure our observations were not purely representative of sedentary animals, but age-related phenotypes were not improved with running wheel activity. Adipose tissue fibrosis, peripheral neuropathy, and loss of neuromuscular junction integrity were consistent phenotypes in older-aged HET3 mice regardless of physical activity, but aspects of these phenotypes were moderated by the SNP% contributions of the founding strains for the HET3 line. Taken together, the genetic contribution of founder strain SNPs moderated age-related phenotypes in skin and muscle innervation and were dependent on biological sex and chronological age. However, there was not a single founder strain (BALB/cJ, C57BL/6J, C3H/HeJ, DBA/2J) that appeared to drive more protection or disease-risk across aging in this mouse line, but genetic diversity in general was more protective.

Astaxanthin and meclizine extend lifespan in UM-HET3 male mice; fisetin, SG1002 (hydrogen sulfide donor), dimethyl fumarate, mycophenolic acid, and 4-phenylbutyrate do not significantly affect lifespan in either sex at the doses and schedules used.

In genetically heterogeneous (UM-HET3) mice produced by the CByB6F1 × C3D2F1 cross, the Nrf2 activator astaxanthin (Asta) extended the median male lifespan by 12% (p = 0.003, log-rank test), while meclizine (Mec), an mTORC1 inhibitor, extended the male lifespan by 8% (p = 0.03). Asta was fed at 1840 ± 520 (9) ppm and Mec at 544 ± 48 (9) ppm, stated as mean ± SE (n) of independent diet preparations. Both were started at 12 months of age. The 90th percentile lifespan for both treatments was extended in absolute value by 6% in males, but neither was significant by the Wang-Allison test. Five other new agents were also tested as follows: fisetin, SG1002 (hydrogen sulfide donor), dimethyl fumarate, mycophenolic acid, and 4-phenylbutyrate. None of these increased lifespan significantly at the dose and method of administration tested in either sex. Amounts of dimethyl fumarate in the diet averaged 35% of the target dose, which may explain the absence of lifespan effects. Body weight was not significantly affected in males by any of the test agents. Late life weights were lower in females fed Asta and Mec, but lifespan was not significantly affected in these females. The male-specific lifespan benefits from Asta and Mec may provide insights into sex-specific aspects of aging.

Age-related changes to adipose tissue and peripheral neuropathy in genetically diverse HET3 mice differ by sex and are not mitigated by rapamycin longevity treatment.

Neural communication between the brain and adipose tissues regulates energy expenditure and metabolism through modulation of adipose tissue functions. We have recently demonstrated that under pathophysiological conditions (obesity, diabetes, and aging), total subcutaneous white adipose tissue (scWAT) innervation is decreased ('adipose neuropathy'). With advanced age in the C57BL/6J mouse, small fiber peripheral nerve endings in adipose tissue die back, resulting in reduced contact with adipose-resident blood vessels and other cells. This vascular neuropathy and parenchymal neuropathy together likely pose a physiological challenge for tissue function. In the current work, we used the genetically diverse HET3 mouse model to investigate the incidence of peripheral neuropathy and adipose tissue dysregulation across several ages in both male and female mice. We also investigated the anti-aging treatment rapamycin, an mTOR inhibitor, as a means to prevent or reduce adipose neuropathy. We found that HET3 mice displayed a reduced neuropathy phenotype compared to inbred C56BL/6 J mice, indicating genetic contributions to this aging phenotype. Compared to female HET3 mice, male HET3 mice had worse neuropathic phenotypes by 62 weeks of age. Female HET3 mice appeared to have increased protection from neuropathy until advanced age (126 weeks), after reproductive senescence. We found that rapamycin overall had little impact on neuropathy measures, and actually worsened adipose tissue inflammation and fibrosis. Despite its success as a longevity treatment in mice, higher doses and longer delivery paradigms for rapamycin may lead to a disconnect between life span and beneficial health outcomes.

Lifespan benefits for the combination of rapamycin plus acarbose and for captopril in genetically heterogeneous mice.

Mice bred in 2017 and entered into the C2017 cohort were tested for possible lifespan benefits of (R/S)-1,3-butanediol (BD), captopril (Capt), leucine (Leu), the Nrf2-activating botanical mixture PB125, sulindac, syringaresinol, or the combination of rapamycin and acarbose started at 9 or 16 months of age (RaAc9, RaAc16). In male mice, the combination of Rapa and Aca started at 9 months and led to a longer lifespan than in either of the two prior cohorts of mice treated with Rapa only, suggesting that this drug combination was more potent than either of its components used alone. In females, lifespan in mice receiving both drugs was neither higher nor lower than that seen previously in Rapa only, perhaps reflecting the limited survival benefits seen in prior cohorts of females receiving Aca alone. Capt led to a significant, though small (4% or 5%), increase in female lifespan. Capt also showed some possible benefits in male mice, but the interpretation was complicated by the unusually low survival of controls at one of the three test sites. BD seemed to produce a small (2%) increase in females, but only if the analysis included data from the site with unusually short-lived controls. None of the other 4 tested agents led to any lifespan benefit. The C2017 ITP dataset shows that combinations of anti-aging drugs may have effects that surpass the benefits produced by either drug used alone, and that additional studies of captopril, over a wider range of doses, are likely to be rewarding.

Rapamycin/metformin co-treatment normalizes insulin sensitivity and reduces complications of metabolic syndrome in type 2 diabetic mice.

Rapamycin treatment has positive and negative effects on progression of type 2 diabetes (T2D) in a recombinant inbred polygenic mouse model, male NONcNZO10/LtJ (NcZ10). Here, we show that combination treatment with metformin ameliorates negative effects of rapamycin while maintaining its benefits. From 12 to 30 weeks of age, NcZ10 males were fed a control diet or diets supplemented with rapamycin, metformin, or a combination of both. Rapamycin alone reduced weight gain, adiposity, HOMA-IR, and inflammation, and prevented hyperinsulinemia and pre-steatotic hepatic lipidosis, but exacerbated hyperglycemia, hypertriglyceridemia, and pancreatic islet degranulation. Metformin alone reduced hyperinsulinemia and circulating c-reactive protein, but exacerbated nephropathy. Combination treatment retained the benefits of both while preventing many of the deleterious effects. Importantly, the combination treatment reversed effects of rapamycin on markers of hepatic insulin resistance and normalized systemic insulin sensitivity in this inherently insulin-resistant model. In adipose tissue, rapamycin attenuated the expression of genes associated with adipose tissue expansion (Mest, Gpam), inflammation (Itgam, Itgax, Hmox1, Lbp), and cell senescence (Serpine1). In liver, the addition of metformin counteracted rapamycin-induced alterations of G6pc, Ppara, and Ldlr expressions that promote hyperglycemia and hypertriglyceridemia. Both rapamycin and metformin treatment reduced hepatic Fasn expression, potentially preventing lipidosis. These results delineate a state of "insulin signaling restriction" that withdraws endocrine support for further adipogenesis, progression of the metabolic syndrome, and the development of its comorbidities. Our results are relevant for the treatment of T2D, the optimization of current rapamycin-based treatments for posttransplant rejection and various cancers, and for the development of treatments for healthy aging.

17-a-estradiol late in life extends lifespan in aging UM-HET3 male mice; nicotinamide riboside and three other drugs do not affect lifespan in either sex.

In genetically heterogeneous mice produced by the CByB6F1 x C3D2F1 cross, the "non-feminizing" estrogen, 17-α-estradiol (17aE2), extended median male lifespan by 19% (p < 0.0001, log-rank test) and 11% (p = 0.007) when fed at 14.4 ppm starting at 16 and 20 months, respectively. 90th percentile lifespans were extended 7% (p = 0.004, Wang-Allison test) and 5% (p = 0.17). Body weights were reduced about 20% after starting the 17aE2 diets. Four other interventions were tested in males and females: nicotinamide riboside, candesartan cilexetil, geranylgeranylacetone, and MIF098. Despite some data suggesting that nicotinamide riboside would be effective, neither it nor the other three increased lifespans significantly at the doses tested. The 17aE2 results confirm and extend our original reports, with very similar results when started at 16 months compared with mice started at 10 months of age in a prior study. The consistently large lifespan benefit in males, even when treatment is started late in life, may provide information on sex-specific aspects of aging.

Rapamycin-mediated mouse lifespan extension: Late-life dosage regimes with sex-specific effects.

To see if variations in timing of rapamycin (Rapa), administered to middle aged mice starting at 20 months, would lead to different survival outcomes, we compared three dosing regimens. Initiation of Rapa at 42 ppm increased survival significantly in both male and female mice. Exposure to Rapa for a 3-month period led to significant longevity benefit in males only. Protocols in which each month of Rapa treatment was followed by a month without Rapa exposure were also effective in both sexes, though this approach was less effective than continuous exposure in female mice. Interpretation of these results is made more complicated by unanticipated variation in patterns of weight gain, prior to the initiation of the Rapa treatment, presumably due to the use of drug-free food from two different suppliers. The experimental design included tests of four other drugs, minocycline, ß-guanidinopropionic acid, MitoQ, and 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG), but none of these led to a change in survival in either sex.

Canagliflozin extends life span in genetically heterogeneous male but not female mice.

Canagliflozin (Cana) is an FDA-approved diabetes drug that protects against cardiovascular and kidney diseases. It also inhibits the sodium glucose transporter 2 by blocking renal reuptake and intestinal absorption of glucose. In the context of the mouse Interventions Testing Program, genetically heterogeneous mice were given chow containing Cana at 180 ppm at 7 months of age until their death. Cana extended median survival of male mice by 14%. Cana also increased by 9% the age for 90th percentile survival, with parallel effects seen at each of 3 test sites. Neither the distribution of inferred cause of death nor incidental pathology findings at end-of-life necropsies were altered by Cana. Moreover, although no life span benefits were seen in female mice, Cana led to lower fasting glucose and improved glucose tolerance in both sexes, diminishing fat mass in females only. Therefore, the life span benefit of Cana is likely to reflect blunting of peak glucose levels, because similar longevity effects are seen in male mice given acarbose, a diabetes drug that blocks glucose surges through a distinct mechanism, i.e., slowing breakdown of carbohydrate in the intestine. Interventions that control daily peak glucose levels deserve attention as possible preventive medicines to protect from a wide range of late-life neoplastic and degenerative diseases.

Differential Effects of Rapamycin on Glucose Metabolism in Nine Inbred Strains.

Studies in mice suggest that rapamycin has a negative impact on glucose homeostasis by inducing insulin resistance. However, results have been inconsistent and difficult to assess because the strains, methods of treatment, and analysis vary among studies. Using a consistent protocol, we surveyed nine inbred strains of mice for the effect of rapamycin on various aspects of glucose metabolism. Across all strains, rapamycin significantly delayed glucose clearance after challenge. However, rapamycin showed no main effect on systemic insulin sensitivity. Analysis of individual strains shows that rapamycin induced higher glucose values at 15 minutes post-challenge in 7/9 strains. However, only three strains show rapamycin-induced reduction in glucose clearance from 15 to 120 minutes. Although pancreatic insulin content was reduced by rapamycin in seven strains, none showed reduced serum insulin values. Although one strain showed no effects of rapamycin on glucose metabolism (129), another showed increased systemic insulin sensitivity (B6). We suggest that rapamycin likely inhibits insulin production and secretion in most strains while having strain-specific effects on glucose clearance without altering systemic insulin sensitivity. This strain survey indicates that genetic differences greatly influence the metabolic response to rapamycin.

Cardioprotective effects of dietary rapamycin on adult female C57BLKS/J-Leprdb mice.

Rapamycin (RAPA), an inhibitor of mTORC signaling, has been shown to extend life span in mice and other organisms. Recently, animal and human studies have suggested that inhibition of mTORC signaling can alleviate or prevent the development of cardiomyopathy. In view of this, we used a murine model of type 2 diabetes (T2D), BKS-Leprdb , to determine whether RAPA treatment can mitigate the development of T2D-induced cardiomyopathy in adult mice. Female BKS-Leprdb mice fed diet supplemented with RAPA from 11 to 27 weeks of age showed reduced weight gain and significant reductions of fat and lean mass compared with untreated mice. No differences in plasma glucose or insulin levels were observed between groups; however, RAPA-treated mice were more insulin sensitive (P < 0.01) than untreated mice. Urine albumin/creatinine ratio was lower in RAPA-treated mice, suggesting reduced diabetic nephropathy and improved kidney function. Echocardiography showed significantly reduced left ventricular wall thickness in mice treated with RAPA compared with untreated mice (P = 0.02) that was consistent with reduced heart weight/tibia length ratios, reduced myocyte size and cardiac fibrosis measured by histomorphology, and reduced mRNA expression of Col1a1, a marker for cardiomyopathy. Our results suggest that inhibition of mTORC signaling is a plausible strategy for ameliorating complications of obesity and T2D, including cardiomyopathy.

Rapamycin treatment benefits glucose metabolism in mouse models of type 2 diabetes.

Numerous studies suggest that rapamycin treatment promotes insulin resistance, implying that rapamycin could have negative effects on patients with, or at risk for, type 2 diabetes (T2D). New evidence, however, indicates that rapamycin treatment produces some benefits to energy metabolism, even in the context of T2D. Here, we survey 5 mouse models of T2D (KK, KK-Ay, NONcNZO10, BKS-db/db, TALLYHO) to quantify effects of rapamycin on well-recognized markers of glucose homeostasis within a wide range of T2D environments. Interestingly, dietary rapamycin treatment did not exacerbate impaired glucose or insulin tolerance, or elevate circulating lipids as T2D progressed. In fact, rapamycin increased insulin sensitivity and reduced weight gain in 3 models, and decreased hyperinsulinemia in 2 models. A key covariate of this genetically-based, differential response was pancreatic insulin content (PIC): Models with low PIC exhibited more beneficial effects than models with high PIC. However, a minimal PIC threshold may exist, below which hypoinsulinemic hyperglycemia develops, as it did in TALLYHO. Our results, along with other studies, indicate that beneficial or detrimental metabolic effects of rapamycin treatment, in a diabetic or pre-diabetic context, are driven by the interaction of rapamycin with the individual model's pancreatic physiology.

Rapamycin ameliorates nephropathy despite elevating hyperglycemia in a polygenic mouse model of type 2 diabetes, NONcNZO10/LtJ.

While rapamycin treatment has been reported to have a putatively negative effect on glucose homeostasis in mammals, it has not been tested in polygenic models of type 2 diabetes. One such mouse model, NONcNZO10/LtJ, was treated chronically with rapamycin (14 ppm encapsulated in diet) and monitored for the development of diabetes. As expected, rapamycin treatment accelerated the onset and severity of hyperglycemia. However, development of nephropathy was ameliorated, as both glomerulonephritis and IgG deposition in the subendothelial tuft were markedly reduced. Insulin production and secretion appeared to be inhibited, suppressing the developing hyperinsulinemia present in untreated controls. Rapamycin treatment also reduced body weight gain. Thus, rapamycin reduced some of the complications of diabetes despite elevating hyperglycemia. These results suggest that multiple factors must be evaluated when assessing the benefit vs. hazard of rapamycin treatment in patients that have overt, or are at risk for, type 2 diabetes. Testing of rapamycin in combination with insulin sensitizers is warranted, as such compounds may ameliorate the putative negative effects of rapamycin in the type 2 diabetes environment.

Comparison of Two New Mouse Models of Polygenic Type 2 Diabetes at the Jackson Laboratory, NONcNZO10Lt/J and TALLYHO/JngJ.

This review compares two novel polygenic mouse models of type 2 diabetes (T2D), TALLYHO/JngJ and NONcNZO10/LtJ, and contrasts both with the well-known C57BLKS/J-Lepr(db) (db/db) monogenic diabesity model. We posit that the new polygenic models are more representative of the "garden variety" obesity underlying human T2D in terms of their polygenetic rather than monogenic etiology. Moreover, the clinical phenotypes in these new models are less extreme, for example, more moderated development of obesity coupled with less extreme endocrine disturbances. The more progressive development of obesity produces a maturity-onset development of hyperglycemia in contrast to the juvenile-onset diabetes observed in the morbidly obese db/db model. Unlike the leptin receptor-deficient db/db models with central leptin resistance, the new models develop a progressive peripheral leptin resistance and are able to maintain reproductive function. Although the T2D pathophysiology in both TALLYHO/JngJ and NONcNZO10/LtJ is remarkably similar, their genetic etiologies are clearly different, underscoring the genetic heterogeneity underlying T2D in humans.

Testing the role of P2X7 receptors in the development of type 1 diabetes in nonobese diabetic mice.

Although P2rx7 has been proposed as a type 1 diabetes (T1D) susceptibility gene in NOD mice, its potential pathogenic role has not been directly determined. To test this possibility, we generated a new NOD stock deficient in P2X(7) receptors. T1D development was not altered by P2X(7) ablation. Previous studies found CD38 knockout (KO) NOD mice developed accelerated T1D partly because of a loss of CD4(+) invariant NKT (iNKT) cells and Foxp3(+) regulatory T cells (Tregs). These immunoregulatory T cell populations are highly sensitive to NAD-induced cell death activated by ADP ribosyltransferase-2 (ART2)-mediated ADP ribosylation of P2X(7) receptors. Therefore, we asked whether T1D acceleration was suppressed in a double-KO NOD stock lacking both P2X(7) and CD38 by rescuing CD4(+) iNKT cells and Tregs from NAD-induced cell death. We demonstrated that P2X(7) was required for T1D acceleration induced by CD38 deficiency. The CD38 KO-induced defects in homeostasis of CD4(+) iNKT cells and Tregs were corrected by coablation of P2X(7). T1D acceleration in CD38-deficient NOD mice also requires ART2 expression. If increased ADP ribosylation of P2X(7) in CD38-deficient NOD mice underlies disease acceleration, then a comparable T1D incidence should be induced by coablation of both CD38 and ART2, or CD38 and P2X(7). However, a previously established NOD stock deficient in both CD38 and ART2 expression is T1D resistant. This study demonstrated the presence of a T1D resistance gene closely linked to the ablated Cd38 allele in the previously reported NOD stock also lacking ART2, but not in the newly generated CD38/P2X(7) double-KO line.

Diet-induced obesity in two C57BL/6 substrains with intact or mutant nicotinamide nucleotide transhydrogenase (Nnt) gene.

The C57BL/6J (B6/J) male mouse represents a standard for diet-induced obesity (DIO) and is unique in expressing a loss-of-function nicotinamide nucleotide transhydrogenase (Nnt) gene. This mutation was associated with a marked reduction in glucose-stimulated insulin secretion from B6/J islets in vitro and moderately impaired glucose clearance in vivo. To assess the contribution of this Nnt mutation, we compared DIO responsiveness of Nnt-mutant B6/J males to Nnt wild-type C57BL/6NJ (B6/NJ) males over a 14-week period of feeding a high-fat (60% of calories) diet. Initial mean body weights at 6 weeks did not distinguish the substrains and both substrains were DIO-sensitive. However, B6/J males outgained the B6/NJ males, with a significant 3 g higher mean body weight at 20 weeks accompanied by significant increases in both lean and fat mass. Mean nonfasting serum glucose over time was also significantly higher in B6/J males, as was impairment of glucose tolerance assessed at 8 and 20 weeks of age. Serum leptin, but not insulin, was significantly higher in B6/J males over time. Potential contributions of the wild-type Nnt gene were demonstrable on a lower fat diet (10% of calories) where a significantly greater weight gain over time by B6/NJ males was correlated with a significantly higher serum insulin. In conclusion, DIO developed in response to 60% fat feeding regardless of Nnt allele status. Contribution of the B6/J-unique Nnt mutation was most evident in response to 10% fat feeding that resulted in reduced serum insulin and weight gain compared to B6/NJ males.

NOD x 129.H2(g7) backcross delineates 129S1/SvImJ-derived genomic regions modulating type 1 diabetes development in mice.

OBJECTIVE: Introduction of genes targeted in 129/Sv embryonic stem (ES) cells into NOD mice brings about linked genes that may modulate type 1 diabetes. Our objective was to identify 129S1/SvJ non-MHC regions contributing type 1 diabetes resistance or susceptibility in backcross to NOD/LtJ. RESEARCH DESIGN AND METHODS: After congenic transfer of the NOD H2(g7) haplotype onto 129S1/Sv, 310 females were produced by NOD x (NOD x 129.H2(g7))F1 backcross (N2). A genome scan for quantitative trait locus (QTL) affecting clinical diabetes, age of diabetes onset, and insulitis severity was performed using subphenotype characteristics to improve power and resolution for detection of diabetes susceptibility loci. RESULTS: Thirty-six of 310 (11.6%) N2 females developed type 1 diabetes between 14 and 40 weeks. Significant evidence of linkage for only a single previously reported Idd complex locus (Idd10/17/18, chromosome [Chr] 3) was indicated for clinical diabetes. The quantitative traits of insulitis either alone or combined with age at type 1 diabetes onset were significantly linked to known Idd regions on Chr 1 (Idd5 region), Chr 4 (Idd9 region), Chr 8 (Idd22), Chr 11 (Idd4.3), and proximal Chr 17 (Idd16 region). Significant 129S1/Sv resistance contributions were identified on Chr 1, 15 (two loci), and 19, with suggestive evidence for additional novel 129/Sv resistance QTL on Chr 5 and 17 and susceptibility on Chr 2. CONCLUSIONS: The 129S1/SvJ genome harbors collections of both known and potentially novel non-MHC Idd loci. Investigators targeting 129/Sv genes mapping within chromosomal regions reported herein or elsewhere in the genome need to exclude potential contributions from linked Idd loci by generating a NOD.129 control strain expressing the nontargeted allele.

Bone marrow expressing a diabetes resistance MHC class II allele: diabetes deviation by chronic immune stimulation.

The major histocompatibility complex (MHC) of the type 1 diabetes-prone NOD mouse lacks a functional class II H2-Ea gene such that antigen presenting cells (APCs) are I-E null. Transgenic expression of Ea in NOD mice both restores I-E expression and confers complete protection from diabetes progression. Non-myeloablative neonatal transplantation of bone marrow cells from such I-E+ transgenic donors into NOD recipients resulted in low-level but long-term haematopoietic stem cell (HSC) engraftment. Despite low levels of I-E antigen expression in blood (averaging 0.4-3.8% of total MHC class II-positive population), chimeric recipients were protected from overt diabetes, although not insulitis development. Adoptive transfer of diabetes into immunodeficient NOD-Rag recipients that received chimeric splenocytes from primary recipients confirmed the presence of an autoreactive T cell repertoire. The demonstration that purified T cells from these weak chimeras were not tolerant to irradiated transgenic I-E+ splenocytes indicated that I-E+ donor cells provide a constant, low-level immune stimulation capable of up-regulating nominally deficient immunoregulatory networks. This study raises the possibility that cord blood HSCs from infants with high risk HLA haplotypes and a family history of type 1 diabetes might be re-introduced without myoablative treatments following transfection with a single HLA class II allele associated with diabetes resistance.

Adipokine and insulin profiles distinguish diabetogenic and non-diabetogenic obesities in mice.

OBJECTIVE: To use longitudinal profiling of plasma adipokines to distinguish diabetogenic vs. non-diabetogenic obesity syndrome in two new mouse models of polygenic obesity. RESEARCH METHODS AND PROCEDURES: Male mice of the NONcNZO5 strain develop a polygenic obesity syndrome uncomplicated by diabetes, whereas NONcNZO10 males develop a comparable polygenic obesity that precipitates type 2 diabetes. A multiplex immunoassay for simultaneous measurement of insulin and a panel of mouse adipokines (leptin, resistin, adiponectin, interleukin-6, tumor necrosis factor alpha, macrophage chemoattractant protein-1, plasminogen activator inhibitor-1) were used to profile longitudinal changes in these strains between 4 and 16 weeks of age that might distinguish the non-diabetogenic vs. diabetogenic obesity (diabesity). RESULTS: Both strains became adipose, with NONcNZO5 males attaining a higher mean body weight with a higher percentage fat content. Weight gain in NONcNZO5 was accompanied by a transient peak in plasma insulin (PI) at 8 weeks followed by a decline into normal range, with normoglycemia maintained throughout. In contrast, NONcNZO10 showed no early PI secretory response because both body weight and plasma glucose increased between 4 and 8 weeks. Only after 12 weeks, with hyperglycemia established, was a delayed PI secretory response observed. Neither plasma leptin nor adiponectin concentrations significantly differentiated the two syndromes over time. However, repeated measures ANOVA showed that NONcNZO10 males maintained significantly higher plasma concentrations of two adipokines, resistin and plasminogen activator inhibitor-1, and the pro-inflammatory cytokine/adipokine macrophage chemoattractant protein-1. DISCUSSION: Longitudinal profiling of PI and adipokines in two new mouse models developing moderate obesity demonstrated that specific marker signatures differentiated a non-diabetogenic obesity from a diabetogenic obesity.

Targeted disruption of CD38 accelerates autoimmune diabetes in NOD/Lt mice by enhancing autoimmunity in an ADP-ribosyltransferase 2-dependent fashion.

Ubiquitously expressed CD38 and T cell-expressed ADP-ribosyltransferase 2 (ART2) are ectoenzymes competing for NAD substrate. CD38 exerts pleiotropic actions in hemopoietic and nonhemopoietic compartments via effects on calcium mobilization. ART2 is an ADP-ribosyltransferase on naive CD4+ and CD8+ T cells. ART2-catalyzed ADP-ribosylation of the P2X7 purinoreceptor elicits apoptosis. Transfer of a genetically disrupted CD38 allele into the autoimmune diabetes-prone NOD/Lt background accelerated diabetes onset in both sexes, whereas transfer of a disrupted ART2 complex had no effect. However, the fact that the accelerated pathogenesis mediated by CD38 deficiency required ART2 activity was demonstrated by combining both ART2 and CD38 deficiencies. Reciprocal bone marrow reconstitution studies demonstrated accelerated diabetes only when CD38-deficient bone marrow was transferred into CD38-deficient recipients. Neither decreases in beta cell function nor viability were indicated. Rather, the balance between T-effectors and T-regulatory cells was disturbed in CD38-deficient but ART2-intact NOD mice. In these mice, significant reductions in total viable CD8+ T cells were observed. This was accompanied by an age-dependent increase in a diabetogenic CD8 clonotype. This in turn correlated with impaired T-regulatory development (10-fold reduction in Foxp3 mRNA expression). These changes were corrected when CD38 deficiency was combined with ART2 deficiency. Both ART2-deficient and CD38/ART2 combined deficient T cells were resistant to NAD-induced killing in vitro, whereas CD38-deficient but ART2-intact T cells showed increased sensitivity, particularly the CD4+ CD25+ subset. Unexpectedly, diabetes development in the combined CD38/ART2 stock was strongly suppressed, possibly through epistatic interactions between genes linked to the targeted CD38 on Chromosome 5 and the ART2 complex on Chromosome 7.