Accelerated onset of diabetes in non-obese diabetic mice fed a refined high-fat diet.

AIM: Type 1 diabetes results from autoimmune events influenced by environmental variables, including changes in diet. This study investigated how feeding refined versus unrefined (aka 'chow') diets affects the onset and progression of hyperglycaemia in non-obese diabetic (NOD) mice. METHODS: Female NOD mice were fed either unrefined diets or matched refined low- and high-fat diets. The onset of hyperglycaemia, glucose tolerance, food intake, energy expenditure, circulating insulin, liver gene expression and microbiome changes were measured for each dietary group. RESULTS: NOD mice consuming unrefined (chow) diets developed hyperglycaemia at similar frequencies. By contrast, mice consuming the defined high-fat diet had an accelerated onset of hyperglycaemia compared to the matched low-fat diet. There was no change in food intake, energy expenditure, or physical activity within each respective dietary group. Microbiome changes were driven by diet type, with chow diets clustering similarly, while refined low- and high-fat bacterial diversity also grouped closely. In the defined dietary cohort, liver gene expression changes in high-fat-fed mice were consistent with a greater frequency of hyperglycaemia and impaired glucose tolerance. CONCLUSION: Glucose intolerance is associated with an enhanced frequency of hyperglycaemia in female NOD mice fed a defined high-fat diet. Using an appropriate matched control diet is an essential experimental variable when studying changes in microbiome composition and diet as a modifier of disease risk.

NOD mice have distinct metabolic and immunologic profiles when compared with genetically similar MHC-matched ICR mice.

Nonobese diabetic (NOD) mice are the most commonly used rodent model to study mechanisms relevant to the autoimmunity and immunology of type 1 diabetes. Although many different strains of mice have been used as controls for studies comparing nondiabetic lines to the NOD strain, we hypothesized that the parental strain that gave rise to the NOD line might be one of the best options. Therefore, we compared female ICR and NOD mice, which are matched at key major histocompatibility complex (MHC) loci, to understand their metabolic and immunologic similarities and differences. Several novel observations emerged: 1) NOD mice have greater circulating proinsulin when compared with ICR mice. 2) NOD mice display CD3+ and IBA1+ cell infiltration into and near pancreatic islets before hyperglycemia. 3) NOD mice show increased expression of the Il1b and Cxcl11 genes in islets when compared with islets from age-matched ICR mice. 4) NOD mice have a greater abundance of STAT1 and ICAM-1 protein in islets when compared with ICR mice. These data show that ICR mice, which are genetically similar to NOD mice, do not retain the same immunologic outcomes. Thus, ICR mice are an excellent choice as a genetically similar and MHC-matched control for NOD mice in studies designed to understand mechanisms relevant to autoimmune-mediated diabetes onset as well as novel therapeutic interventions.NEW & NOTEWORTHY Nonobese diabetic (NOD) mice have more proinsulin in circulation and STAT1 protein in islets compared with the major histocompatibility complex (MHC)-matched ICR line. NOD mice also display greater expression of cytokines and chemokines in pancreatic islets consistent with immune cell infiltration before hyperglycemia when compared with age-matched ICR mice. Thus, ICR mice represent an excellent control for autoimmunity and inflammation studies using the NOD line of mice.

Mouse Pancreatic Peptide Hormones Probed at the Sub-Single-Islet Level: The Effects of Acute Corticosterone Treatment.

We combine liquid chromatography coupled with ion mobility spectrometry-mass spectrometry to elucidate how short exposure to corticosterone (Cort) alters the output of mouse pancreatic islet hormones. The workflow enables the robust separation of mouse insulin 1 (Ins1) and insulin 2 (Ins2) and the detection of major islet hormones in a homogenate equivalent to 100-150 islet cells. We show that Ins2 has a unique structure and is degraded much faster than Ins1. Further investigation indicates that Ins2 may populate both T and R states, whereas Ins1 may not. The assemblies of Ins1's B-chain also introduce more structural heterogeneity than Ins2. Collectively, these features account for their unique degradation profiles, the diabetes risk associated with Ins1, and the protective effect of Ins2. In the same experiments, we observe that the ratio of amylin to Ins1 increased significantly in Cort-treated mice (15:1) compared to the control mice (42:1), correlating well with ß-cell proliferation observed in immunoassays on the same animal model. We observe no increase in intact full-length insulin levels but more of the truncated forms, indicating that enzymatic activity is accelerated. Our data provide a molecular basis for reduced insulin action induced by Cort and connections between insulin turnover and insulin resistance.

ICAM-1 Abundance Is Increased in Pancreatic Islets of Hyperglycemic Female NOD Mice and Is Rapidly Upregulated by NF-κB in Pancreatic ß-Cells.

Type 1 diabetes (T1D) is classified as an autoimmune disease where pancreatic ß-cells are specifically targeted by cells of the immune system. The molecular mechanisms underlying this process are not completely understood. Herein, we identified that the Icam1 gene and ICAM-1 protein were selectively elevated in female NOD mice relative to male mice, fitting with the sexual dimorphism of diabetes onset in this key mouse model of T1D. In addition, ICAM-1 abundance was greater in hyperglycemic female NOD mice than in age-matched normoglycemic female NOD mice. Moreover, we discovered that the Icam1 gene was rapidly upregulated in response to IL-1ß in mouse, rat, and human islets and in 832/13 rat insulinoma cells. This early temporal genetic regulation requires key components of the NF-κB pathway and was associated with rapid recruitment of the p65 transcriptional subunit of NF-κB to corresponding κB elements within the Icam1 gene promoter. In addition, RNA polymerase II recruitment to the Icam1 gene promoter in response to IL-1ß was consistent with p65 occupancy at κB elements, histone chemical modifications, and increased mRNA abundance. Thus, we conclude that ß-cells undergo rapid genetic reprogramming by IL-1ß to enhance expression of the Icam1 gene and that elevations in ICAM-1 are associated with hyperglycemia in NOD mice. These findings are highly relevant to, and highlight the importance of, pancreatic ß-cell communication with the immune system. Collectively, these observations reveal a portion of the complex molecular events associated with onset and progression of T1D.

Pioglitazone Reverses Markers of Islet Beta-Cell De-Differentiation in db/db Mice While Modulating Expression of Genes Controlling Inflammation and Browning in White Adipose Tissue from Insulin-Resistant Mice and Humans.

Obesity, insulin resistance, and type 2 diabetes contribute to increased morbidity and mortality in humans. The db/db mouse is an important mouse model that displays many key features of the human disease. Herein, we used the drug pioglitazone, a thiazolidinedione with insulin-sensitizing properties, to investigate blood glucose levels, indicators of islet ß-cell health and maturity, and gene expression in adipose tissue. Oral administration of pioglitazone lowered blood glucose levels in db/db mice with a corresponding increase in respiratory quotient, which indicates improved whole-body carbohydrate utilization. In addition, white adipose tissue from db/db mice and from humans treated with pioglitazone showed increased expression of glycerol kinase. Both db/db mice and humans given pioglitazone displayed increased expression of UCP-1, a marker typically associated with brown adipose tissue. Moreover, pancreatic ß-cells from db/db mice treated with pioglitazone had greater expression of insulin and Nkx6.1 as well as reduced abundance of the de-differentiation marker Aldh1a3. Collectively, these findings indicate that four weeks of pioglitazone therapy improved overall metabolic health in db/db mice. Our data are consistent with published reports of human subjects administered pioglitazone and with analysis of human adipose tissue taken from subjects treated with pioglitazone. In conclusion, the current study provides evidence that pioglitazone restores key markers of metabolic health and also showcases the utility of the db/db mouse to understand mechanisms associated with human metabolic disease and interventions that provide therapeutic benefit.

α-CGRP disrupts amylin fibrillization and regulates insulin secretion: implications on diabetes and migraine.

Despite being relatively benign and not an indicative signature of toxicity, fibril formation and fibrillar structures continue to be key factors in assessing the structure-function relationship in protein aggregation diseases. The inability to capture molecular cross-talk among key players at the tissue level before fibril formation greatly accounts for the missing link toward the development of an efficacious therapeutic intervention for Type II diabetes mellitus (T2DM). We show that human α-calcitonin gene-related peptide (α-CGRP) remodeled amylin fibrillization. Furthermore, while CGRP and/or amylin monomers reduce the secretion of both mouse Ins1 and Ins2 proteins, CGRP oligomers have a reverse effect on Ins1. Genetically reduced Ins2, the orthologous version of human insulin, has been shown to enhance insulin sensitivity and extend the life-span in old female mice. Beyond the mechanistic insights, our data suggest that CGRP regulates insulin secretion and lowers the risk of T2DM. Our result rationalizes how migraine might be protective against T2DM. We envision the new paradigm of CGRP : amylin interactions as a pivotal aspect for T2DM diagnostics and therapeutics. Maintaining a low level of amylin while increasing the level of CGRP could become a viable approach toward T2DM prevention and treatment.

Pancreatic, but not myeloid-cell, expression of interleukin-1alpha is required for maintenance of insulin secretion and whole body glucose homeostasis.

OBJECTIVE: The expression of the interleukin-1 receptor type I (IL-1R) is enriched in pancreatic islet ß-cells, signifying that ligands activating this pathway are important for the health and function of the insulin-secreting cell. Using isolated mouse, rat, and human islets, we identified the cytokine IL-1α as a highly inducible gene in response to IL-1R activation. In addition, IL-1α is elevated in mouse and rat models of obesity and Type 2 diabetes. Since less is known about the biology of IL-1α relative to IL-1ß in pancreatic tissue, our objective was to investigate the contribution of IL-1α to pancreatic ß-cell function and overall glucose homeostasis in vivo. METHODS: We generated a novel mouse line with conditional IL-1α alleles and subsequently produced mice with either pancreatic- or myeloid lineage-specific deletion of IL-1α. RESULTS: Using this in vivo approach, we discovered that pancreatic (IL-1αPdx1-/-), but not myeloid-cell, expression of IL-1α (IL-1αLysM-/-) was required for the maintenance of whole body glucose homeostasis in both male and female mice. Moreover, pancreatic deletion of IL-1α led to impaired glucose tolerance with no change in insulin sensitivity. This observation was consistent with our finding that glucose-stimulated insulin secretion was reduced in islets isolated from IL-1αPdx1-/- mice. Alternatively, IL-1αLysM-/- mice (male and female) did not have any detectable changes in glucose tolerance, respiratory quotient, physical activity, or food intake when compared with littermate controls. CONCLUSIONS: Taken together, we conclude that there is an important physiological role for pancreatic IL-1α to promote glucose homeostasis by supporting glucose-stimulated insulin secretion and islet ß-cell mass in vivo.

Indirect, Non-Thermal Atmospheric Plasma Promotes Bacterial Killing in vitro and Wound Disinfection in vivo Using Monogenic and Polygenic Models of Type 2 Diabetes (Without Adverse Metabolic Complications).

A novel atmospheric plasma device that uses indirect, non-thermal plasma generated from room air is being studied for its effects on wound disinfection in animal wounds of monogenic and polygenic murine models of type 2 diabetes. As a proof-of-concept report, the goal of this study was to demonstrate the efficacy and safety of the indirect non-thermal plasma (INTP) device in disinfecting polycarbonate filters established with Pseudomonas aeruginosa (PAO1) biofilms as well as wound disinfection in diabetic murine wounds. Dorsal excisional wounds in BALB/c, polygenic TALLYHO, and monogenic db/db mice established with PAO1 infection all demonstrated a 3-log colony-forming unit (CFU) reduction when subjected to a course of 20-min INTP treatments. Importantly, blood glucose and body weights in these animals were not significantly impacted by plasma treatment over the study period. Plasma safety was also analyzed via complete blood count and comprehensive metabolic panels, showing no deleterious systemic effects after 3 consecutive days of 20-min plasma applications. Therefore, the results obtained demonstrated the Pseudomonas aeruginosa isolates were highly sensitive to INTP in vitro, CFU reduction of infectious Pseudomonas in wounds of diabetic mice after INTP treatment is far superior to that of non-treated infected wounds, and the application of INTP shows no indication of toxic effects. Our results are consistent with indirect non-thermal atmospheric plasma as a promising adjunct to disinfecting wounds.

One week of continuous corticosterone exposure impairs hepatic metabolic flexibility, promotes islet ß-cell proliferation, and reduces physical activity in male C57BL/6 J mice.

Clinical glucocorticoid use, and diseases that produce elevated circulating glucocorticoids, promote drastic changes in body composition and reduction in whole body insulin sensitivity. Because steroid-induced diabetes is the most common form of drug-induced hyperglycemia, we investigated mechanisms underlying the recognized phenotypes associated with glucocorticoid excess. Male C57BL/6 J mice were exposed to either 100ug/mL corticosterone (cort) or vehicle in their drinking water. Body composition measurements revealed an increase in fat mass with drastically reduced lean mass during the first week (i.e., seven days) of cort exposure. Relative to the vehicle control group, mice receiving cort had a significant reduction in insulin sensitivity (measured by insulin tolerance test) five days after drug intervention. The increase in insulin resistance significantly correlated with an increase in the number of Ki-67 positive ß-cells. Moreover, the ability to switch between fuel sources in liver tissue homogenate substrate oxidation assays revealed reduced metabolic flexibility. Furthermore, metabolomics analyses revealed a decrease in liver glycolytic metabolites, suggesting reduced glucose utilization, a finding consistent with onset of systemic insulin resistance. Physical activity was reduced, while respiratory quotient was increased, in mice receiving corticosterone. The majority of metabolic changes were reversed upon cessation of the drug regimen. Collectively, we conclude that changes in body composition and tissue level substrate metabolism are key components influencing the reductions in whole body insulin sensitivity observed during glucocorticoid administration.

Sleep fragmentation delays wound healing in a mouse model of type 2 diabetes.

Study Objectives: This study tested the hypothesis that sleep fragmentation (SF) delays wound healing in obese B6.BKS(D)-Leprdb/J (db/db) mice with impaired leptin signaling and type 2 diabetes compared with wild-type C57BL/6J (B6) mice. Methods: Adult male mice (n = 34) were anesthetized and bilateral full-thickness excisional wounds were created on the back of each mouse. Half of the db/db and B6 mice were housed in SF cages equipped with a bar that moved across the cage floor every 2 min, 12 hr/day for 23 days. The other half of each group of mice was housed in the same room and did not experience SF. The dependent measures were number of days required to achieve wound closure, mRNA expression of four inflammatory mediators, blood glucose, insulin, and corticosterone. Results: SF in the db/db mice caused a significant delay in wound healing relative to db/db mice with no SF. Days to achieve 50 per cent wound healing were 13.3 ± 0.4 with SF compared with 10.3 ± 0.7 without SF. All B6 mice achieved 50 per cent wound healing within 6 days and complete healing after 16 days. SF caused a significant increase in wound levels of TNF-α mRNA only in the db/db mice and an increase in corticosterone only in the B6 mice. Conclusions: The delayed wound healing in obese, diabetic mice caused by SF is homologous to delayed wound healing in some patients with type 2 diabetes. The results support the interpretation that altered leptinergic signaling and inflammatory proteins contribute to delayed wound healing.

Pancreatic deletion of the interleukin-1 receptor disrupts whole body glucose homeostasis and promotes islet ß-cell de-differentiation.

OBJECTIVE: Pancreatic tissue, and islets in particular, are enriched in expression of the interleukin-1 receptor type I (IL-1R). Because of this enrichment, islet ß-cells are exquisitely sensitive to the IL-1R ligands IL-1α and IL-1ß, suggesting that signaling through this pathway regulates health and function of islet ß-cells. METHODS: Herein, we report a targeted deletion of IL-1R in pancreatic tissue (IL-1RPdx1-/-) in C57BL/6J mice and in db/db mice on the C57 genetic background. Islet morphology, ß-cell transcription factor abundance, and expression of the de-differentiation marker Aldh1a3 were analyzed by immunofluorescent staining. Glucose and insulin tolerance tests were used to examine metabolic status of these genetic manipulations. Glucose-stimulated insulin secretion was evaluated in vivo and in isolated islets ex vivo by perifusion. RESULTS: Pancreatic deletion of IL-1R leads to impaired glucose tolerance, a phenotype that is exacerbated by age. Crossing the IL-1RPdx1-/- with db/db mice worsened glucose tolerance without altering body weight. There were no detectable alterations in insulin tolerance between IL-1RPdx1-/- mice and littermate controls. However, glucose-stimulated insulin secretion was reduced in islets isolated from IL-1RPdx1-/- relative to control islets. Insulin output in vivo after a glucose challenge was also markedly reduced in IL-1RPdx1-/- mice when compared with littermate controls. Pancreatic islets from IL-1RPdx1-/- mice displayed elevations in Aldh1a3, a marker of de-differentiation, and reduction in nuclear abundance of the ß-cell transcription factor MafA. Nkx6.1 abundance was unaltered. CONCLUSIONS: There is an important physiological role for pancreatic IL-1R to promote glucose homeostasis by suppressing expression of Aldh1a3, sustaining MafA abundance, and supporting glucose-stimulated insulin secretion in vivo.

Liquid Sucrose Consumption Promotes Obesity and Impairs Glucose Tolerance Without Altering Circulating Insulin Levels.

OBJECTIVE: Multiple factors contribute to the rising rates of obesity and to difficulties in weight reduction that exist in the worldwide population. Caloric intake via sugar-sweetened beverages may be influential. This study tested the hypothesis that liquid sucrose intake promotes obesity by increasing serum insulin levels and tissue lipid accumulation. METHODS: C57BL/6J mice were given 30% sucrose in liquid form. Changes in weight gain, body composition, energy expenditure (EE), and tissue lipid content were measured. RESULTS: Mice drinking sucrose gained more total body mass (TBM), had greater fat mass, and displayed impaired glucose tolerance relative to control mice. These metabolic changes occurred without alterations in circulating insulin levels and despite increases in whole body EE. Lipid accrued in liver, but not skeletal muscle, of sucrose-consuming mice. Oxygen consumption (VO2 ) correlated with fat-free mass and moderately with TBM, but not with fat mass. ANCOVA for treatment effects on EE, with TBM, VO2 , lean body mass, and fat-free mass taken as potential covariates for EE, revealed VO2 as the most significant correlation. CONCLUSIONS: Weight gain induced by intake of liquid sucrose in mice is associated with lipid accrual in liver, but not skeletal muscle, and occurs without an increase in circulating insulin.

db/db Mice Exhibit Features of Human Type 2 Diabetes That Are Not Present in Weight-Matched C57BL/6J Mice Fed a Western Diet.

To understand features of human obesity and type 2 diabetes mellitus (T2D) that can be recapitulated in the mouse, we compared C57BL/6J mice fed a Western-style diet (WD) to weight-matched genetically obese leptin receptor-deficient mice (db/db). All mice were monitored for changes in body composition, glycemia, and total body mass. To objectively compare diet-induced and genetic models of obesity, tissue analyses were conducted using mice with similar body mass. We found that adipose tissue inflammation was present in both models of obesity. In addition, distinct alterations in metabolic flexibility were evident between WD-fed mice and db/db mice. Circulating insulin levels are elevated in each model of obesity, while glucagon was increased only in the db/db mice. Although both WD-fed and db/db mice exhibited adaptive increases in islet size, the db/db mice also displayed augmented islet expression of the dedifferentiation marker Aldh1a3 and reduced nuclear presence of the transcription factor Nkx6.1. Based on the collective results put forth herein, we conclude that db/db mice capture key features of human T2D that do not occur in WD-fed C57BL/6J mice of comparable body mass.

Pancreatic islet inflammation: an emerging role for chemokines.

Both type 1 and type 2 diabetes exhibit features of inflammation associated with alterations in pancreatic islet function and mass. These immunological disruptions, if unresolved, contribute to the overall pathogenesis of disease onset. This review presents the emerging role of pancreatic islet chemokine production as a critical factor regulating immune cell entry into pancreatic tissue as well as an important facilitator of changes in tissue resident leukocyte activity. Signaling through two specific chemokine receptors (i.e., CXCR2 and CXCR3) is presented to illustrate key points regarding ligand-mediated regulation of innate and adaptive immune cell responses. The prospective roles of chemokine ligands and their corresponding chemokine receptors to influence the onset and progression of autoimmune- and obesity-associated forms of diabetes are discussed.

Oral Corticosterone Administration Reduces Insulitis but Promotes Insulin Resistance and Hyperglycemia in Male Nonobese Diabetic Mice.

Steroid-induced diabetes is the most common form of drug-induced hyperglycemia. Therefore, metabolic and immunological alterations associated with chronic oral corticosterone were investigated using male nonobese diabetic mice. Three weeks after corticosterone delivery, there was reduced sensitivity to insulin action measured by insulin tolerance test. Body composition measurements revealed increased fat mass and decreased lean mass. Overt hyperglycemia (>250 mg/dL) manifested 6 weeks after the start of glucocorticoid administration, whereas 100% of the mice receiving the vehicle control remained normoglycemic. This phenotype was fully reversed during the washout phase and readily reproducible across institutions. Relative to the vehicle control group, mice receiving corticosterone had a significant enhancement in pancreatic insulin-positive area, but a marked decrease in CD3+ cell infiltration. In addition, there were striking increases in both citrate synthase gene expression and enzymatic activity in skeletal muscle of mice in the corticosterone group relative to vehicle control. Moreover, glycogen synthase expression was greatly enhanced, consistent with elevations in muscle glycogen storage in mice receiving corticosterone. Corticosterone-induced hyperglycemia, insulin resistance, and changes in muscle gene expression were all reversed by the end of the washout phase, indicating that the metabolic alterations were not permanent. Thus, male nonobese diabetic mice allow for translational studies on the metabolic and immunological consequences of glucocorticoid-associated interventions in a mouse model with genetic susceptibility to autoimmune disease.

Pancreatic ß-Cell production of CXCR3 ligands precedes diabetes onset.

Type 1 diabetes mellitus (T1DM) results from immune cell-mediated reductions in function and mass of the insulin-producing ß-cells within the pancreatic islets. While the initial trigger(s) that initiates the autoimmune process is unknown, there is a leukocytic infiltration that precedes islet ß-cell death and dysfunction. Herein, we demonstrate that genes encoding the chemokines CXCL9, 10, and 11 are primary response genes in pancreatic ß-cells and are also elevated as part of the inflammatory response in mouse, rat, and human islets. We further established that STAT1 participates in the transcriptional control of these genes in response to the pro-inflammatory cytokines IL-1ß and IFN-γ. STAT1 is phosphorylated within five minutes after ß-cell exposure to IFN-γ, with subsequent occupancy at proximal and distal response elements within the Cxcl9 and Cxcl11 gene promoters. This increase in STAT1 binding is coupled to the rapid appearance of chemokine transcript. Moreover, circulating levels of chemokines that activate CXCR3 are elevated in non-obese diabetic (NOD) mice, consistent with clinical findings in human diabetes. We also report herein that mice with genetic deletion of CXCR3 (receptor for ligands CXCL9, 10, and 11) exhibit a delay in diabetes development after being injected with multiple low doses of streptozotocin. Therefore, we conclude that production of CXCL9, 10, and 11 from islet ß-cells controls leukocyte migration and activity into pancreatic tissue, which ultimately influences islet ß-cell mass and function. © 2016 BioFactors, 42(6):703-715, 2016.

Pancreatic Islet Responses to Metabolic Trauma.

Carbohydrate, lipid, and protein metabolism are largely controlled by the interplay of various hormones, which includes those secreted by the pancreatic islets of Langerhans. While typically representing only 1% to 2% of the total pancreatic mass, the islets have a remarkable ability to adapt to disparate situations demanding a change in hormone release, such as peripheral insulin resistance. There are many different routes to the onset of insulin resistance, including obesity, lipodystrophy, glucocorticoid excess, and the chronic usage of atypical antipsychotic drugs. All of these situations are coupled to an increase in pancreatic islet size, often with a corresponding increase in insulin production. These adaptive responses within the islets are ultimately intended to maintain glycemic control and to promote macronutrient homeostasis during times of stress. Herein, we review the consequences of specific metabolic trauma that lead to insulin resistance and the corresponding adaptive alterations within the pancreatic islets.

IL-1ß reciprocally regulates chemokine and insulin secretion in pancreatic ß-cells via NF-κB.

Proinflammatory cytokines impact islet ß-cell mass and function by altering the transcriptional activity within pancreatic ß-cells, producing increases in intracellular nitric oxide abundance and the synthesis and secretion of immunomodulatory proteins such as chemokines. Herein, we report that IL-1ß, a major mediator of inflammatory responses associated with diabetes development, coordinately and reciprocally regulates chemokine and insulin secretion. We discovered that NF-κB controls the increase in chemokine transcription and secretion as well as the decrease in both insulin secretion and proliferation in response to IL-1ß. Nitric oxide production, which is markedly elevated in pancreatic ß-cells exposed to IL-1ß, is a negative regulator of both glucose-stimulated insulin secretion and glucose-induced increases in intracellular calcium levels. By contrast, the IL-1ß-mediated production of the chemokines CCL2 and CCL20 was not influenced by either nitric oxide levels or glucose concentration. Instead, the synthesis and secretion of CCL2 and CCL20 in response to IL-1ß were dependent on NF-κB transcriptional activity. We conclude that IL-1ß-induced transcriptional reprogramming via NF-κB reciprocally regulates chemokine and insulin secretion while also negatively regulating ß-cell proliferation. These findings are consistent with NF-κB as a major regulatory node controlling inflammation-associated alterations in islet ß-cell function and mass.

Thiobenzothiazole-modified Hydrocortisones Display Anti-inflammatory Activity with Reduced Impact on Islet ß-Cell Function.

Glucocorticoids signal through the glucocorticoid receptor (GR) and are administered clinically for a variety of situations, including inflammatory disorders, specific cancers, rheumatoid arthritis, and organ/tissue transplantation. However, glucocorticoid therapy is also associated with additional complications, including steroid-induced diabetes. We hypothesized that modification of the steroid backbone is one strategy to enhance the therapeutic potential of GR activation. Toward this goal, two commercially unavailable, thiobenzothiazole-containing derivatives of hydrocortisone (termed MS4 and MS6) were examined using 832/13 rat insulinoma cells as well as rodent and human islets. We found that MS4 had transrepression properties but lacked transactivation ability, whereas MS6 retained both transactivation and transrepression activities. In addition, MS4 and MS6 both displayed anti-inflammatory activity. Furthermore, MS4 displayed reduced impact on islet ß-cell function in both rodent and human islets. Similar to dexamethasone, MS6 promoted adipocyte development in vitro, whereas MS4 did not. Moreover, neither MS4 nor MS6 activated the Pck1 (Pepck) gene in primary rat hepatocytes. We conclude that modification of the functional groups attached to the D-ring of the hydrocortisone steroid molecule produces compounds with altered structure-function GR agonist activity with decreased impact on insulin secretion and reduced adipogenic potential but with preservation of anti-inflammatory activity.