Different post-pancreatectomy glucagon responses to a meal test between surgical approaches

Residual pancreatic endocrine function is important for maintaining metabolic status after pancreatectomy and is closely related to patient nutritional status and prognosis. In contrast to insulin secretion, the significance of glucagon secretion following pancreatectomy remains unclear. In this study, we assessed the changes in pancreatic glucagon secretion during pancreatectomy to determine their pathophysiological significance. We evaluated glucagon and insulin secretion using a liquid meal tolerance test before and after pancreatectomy in patients scheduled to undergo pancreaticoduodenectomy (PD) or distal pancreatectomy (DP). After pancreatectomy, fasting plasma glucagon levels were significantly decreased in both the PD (n = 10) and DP (n = 5) groups (PD: from 18.4 to 10.5 pg/mL, p = 0.037; DP: from 21.0 to 12.1 pg/mL, p = 0.043), whereas postprandial plasma glucagon levels were not changed. In the liquid meal tolerance test after pancreatectomy, 60-min plasma glucagon levels and the area under the curve (AUC) for 0-120 min of PD were significantly higher than those for DP (60-min plasma glucagon: PD 49.0 vs. DP 21.7 pg/mL, p = 0.040; AUC0-120min: PD 4,749 vs. DP 3,564 μg min/mL, p = 0.028). Postoperative plasma glucose, serum insulin, and serum C-peptide levels during the liquid meal tolerance test were not significantly different between the two groups. Although fasting plasma glucagon levels decreased, postprandial glucagon responses were maintained after both PD and DP. The difference in residual meal-stimulated glucagon response between PD and DP suggests that a relative excess of postprandial glucagon is involved in the postoperative nutritional status after PD through its impact on systemic metabolic status.

Newly discovered knowledge pertaining to glucagon and its clinical applications

Glucagon has been defined as an 'insulin counteracting hormone', which raises blood glucose levels. Recent progress in basic research has shown that glucagon is closely involved in glucose and amino acid metabolism. Additionally, its secretion is intricately, but precisely, regulated by various mechanisms involving molecules in addition to glucose, thus showing its critical role in systemic nutrient metabolism. An innovative dual-antibody-linked immunosorbent assay for glucagon that improves measurement accuracy has been developed, and substantial clinical findings have been obtained using this new system. This discovery expanded the pathophysiological significance of glucagon and accelerated the development of its clinical applications in diabetes.

Change in pharmacodynamic variables following once-weekly tirzepatide treatment versus dulaglutide in Japanese patients with type 2 diabetes (SURPASS J-mono substudy)

AIM

To evaluate the pharmacodynamic effects of tirzepatide, a novel dual glucagon-like peptide-1 receptor and glucose-dependent insulinotropic polypeptide receptor agonist, compared with dulaglutide in patients with type 2 diabetes.

MATERIALS AND METHODS

SURPASS J-mono was a 52-week, multicentre, randomized, double-blind, parallel, active-controlled, Phase 3 study, conducted in Japan. This substudy of SURPASS J-mono evaluated postprandial metabolic variables and appetite after a meal tolerance test, and body composition measured by bioelectrical impedance analysis.

RESULTS

Of 636 participants in SURPASS J-mono, 48 were included in this substudy and assigned to tirzepatide 5 mg (n = 9), tirzepatide 10 mg (n = 11), tirzepatide 15 mg (n = 9), or dulaglutide 0.75 mg (n = 19). Participants had a mean (standard deviation) age of 58.6 (7.5) years, duration of diabetes of 6.0 (6.3) years, and body mass index of 27.5 (3.5) kg/m² . Mean glycated haemoglobin at baseline was 66 mmol/mol (8.22%). Following a standardized meal test, statistically significant differences in change from baseline in area under the concentration versus time curve from time zero to 6 h after dose for glucose, insulin, glucagon, C-peptide and triglycerides were observed in all tirzepatide treatment arms, except triglycerides at 10 mg, compared with dulaglutide at Week 32. For body composition, tirzepatide 10 mg and 15 mg resulted in a significant reduction in body weight, and all doses of tirzepatide resulted in a significant reduction in body fat mass at Week 52.

CONCLUSIONS

Compared with dulaglutide, tirzepatide showed greater potential for normalizing metabolic factors after a standardized meal. Tirzepatide reduced body weight and body fat mass.

Characteristic changes in plasma glutamate levels and free amino acid profiles in Japanese patients with type 1 diabetes mellitus

AIMS/INTRODUCTION

In addition to absolute insulin deficiency, dysregulated glucagon in type 1 diabetes is considered pathophysiologically important. Previously, we confirmed the presence of dysregulated glucagon in Japanese patients with type 1 diabetes, and found a significant correlation between plasma glucagon and blood urea nitrogen levels, suggesting an association between glucagon and amino acid metabolism. In this study, we evaluated plasma amino acid levels in Japanese patients with type 1 diabetes in the context of their functional relationship with glucagon.

MATERIALS AND METHODS

We assessed plasma free amino acid levels using liquid chromatography-mass spectrometry in 77 Japanese patients with type 1 diabetes, and statistically analyzed their characteristics and relationships with clinical parameters, including glucagon.

RESULTS

Participants with type 1 diabetes showed a large decrease in glutamate levels together with a characteristic change in plasma free amino acid profiles. The network structural prediction analyses showed correlations between each amino acid and glucagon in type 1 diabetes.

CONCLUSIONS

Participants with type 1 diabetes showed characteristic changes in plasma glutamate levels and free amino acid profiles compared with controls and type 2 diabetes patients. Glucagon showed a closer correlation with amino acids than with parameters of glucose metabolism, suggesting that type 1 diabetes includes dysregulation in amino acids through dysregulated glucagon from remaining pancreatic α-cells, together with that in glucose by insulin deficiency.

Beginning of a new era in glucagon research: Breakthrough by the new glucagon assay

There is a new concept of diabetes as a "comprehensive nutrition disorder", caused due to both insulin and glucagon dysregulation. Dysregulated glucagon secretion in α-cells exacerbates multiple metabolic disorders: glycemic control and amino acid metabolism, together with insulin deficiency.

Plasma lipopolysaccharide binding protein level statistically mediates between body mass index and chronic microinflammation in Japanese patients with type 1 diabetes

Recently, it is widely recognized that microinflammation plays important roles in the pathophysiology of metabolic diseases, especially obesity-related disorders, diabetes and their complications. Lipopolysaccharide-binding protein (LBP) is a liver-derived acute-phase protein responsive to lipopolysaccharides (LPS) produced by gram-negative bacteria, thus reflects the systemic inflammation caused by the infection of those bacteria including gut dysbiosis. In this study, we evaluated the plasma LBP levels and investigated its clinical significance in 67 Japanese patients with type 1 diabetes. Univariable analysis showed that LBP levels were significantly associated with body mass index (BMI; r = 0.43, p < 0.01) and serum high-sensitivity C-reactive protein (hs-CRP; r = 0.64, p < 0.001) levels. However, there was no significant association between plasma LBP levels and diabetic complications. Mediation analysis revealed that LBP had significant mediation effects on the association between hs-CRP and BMI (0.27 [95% confidence interval 0.10-0.48]). These results suggest that the systemic condition where the LBP level increases, such as gut dysbiosis, at least partly, impacts on chronic microinflammation in patients with type 1 diabetes.

Consistency of plasma glucagon levels in patients with type 1 diabetes after a 1-year period

Recent progress in research on glucagon and α-cells highlights their pathophysiological roles in diabetes. We previously showed that plasma glucagon levels measured by newly developed enzyme-linked immunosorbent assay were dysregulated in patients with type 1 diabetes with respect to plasma glucose levels, suggesting dysregulated secretion. In the current study, the annual change in plasma glucagon levels was assessed in these same patients. We found that the plasma glucagon levels in the 66 Japanese patients involved in the study were significantly correlated between both years. In addition, they were significantly associated with serum blood urea nitrogen levels in a multivariate linear regression analysis, as reported in our previous study. The statistical correlation in glucagon levels between annual checkups and the sustained significant correlation between glucagon and blood urea nitrogen suggest a constant dysregulation of glucagon in association with altered amino acid metabolism in patients with type 1 diabetes.

Positive correlation between fasting plasma glucagon and serum C-peptide in Japanese patients with diabetes

Aims

Glucagon plays pivotal roles in systemic glucose homeostasis mainly by promoting hepatic glucose output. Using a sandwich enzyme-linked immunosorbent assay (ELISA), we evaluated fasting plasma glucagon levels in hospitalized patients with type 1 or type 2 diabetes, and assessed the relationships between glucagon levels and various clinical parameters.

Methods

We enrolled adult Japanese diabetes patients admitted to Osaka University Medical Hospital for glycemic control between July 2017 and May 2018 in this study. After patients had fasted for 12 h, blood samples were obtained and plasma glucagon levels were measured using a sandwich ELISA.

Results

Total 107 patients participated in the study. The mean fasting plasma glucagon level of patients with acute onset type 1 diabetes was significantly lower than that of patients with type 2 diabetes (p < 0.05). Plasma glucagon levels were not significantly correlated with plasma glucose levels in patients with type 1 diabetes or in patients with type 2 diabetes. Multiple regression analysis indicated that fasting glucagon levels were independently and significantly correlated with fasting serum C-peptide levels in patients with type 2 diabetes.

Conclusions

Our results suggest that insulin and glucagon secretion are balanced in the fasting state in patients with type 2 diabetes.

Alpha the versatile: Guardians of the islets

Recent progress in α-cell research has newly revealed its versatility including secretion of multiple hormones, trans-differentiation, and abundant proliferation. A recent report from the Kushner laboratory further provided direct evidence of active proliferation of α-cells in both T1D and non-diabetic control donors. α-cells are suggested to maintain both quality and quantity of islets by serving as 'guardians' of the islets.

Dysregulated plasma glucagon levels in Japanese young adult type 1 diabetes patients

Currently, the clinical dynamics of glucagon need to be revised based on previous data obtained from conventional glucagon radioimmunoassays. In the present study, we evaluated plasma glucagon levels in type 1 diabetes patients using a newly-developed sandwich enzyme-linked immunosorbent assay, and its association with clinical parameters and markers of diabetes complications were statistically assessed. The plasma glucagon level in 77 Japanese type 1 diabetes patients was 28.1 ± 17.7 pg/mL, and comparable with that reported previously for type 2 diabetes patients. However, the values were widely spread and did not correlate with plasma glucose values. Additionally, the average glucagon levels in patients in a hypoglycemic state (glucose level <80 mg/dL) did not increase (21.7 ± 12.2 pg/mL). The average glucagon level of patients experiencing hypoglycemia unawareness was significantly lower. Plasma glucagon levels evaluated using the new enzyme-linked immunosorbent assay were dysregulated in type 1 diabetes patients in respect to plasma glucose levels, suggesting dysregulation of secretion.

Skin autofluorescence is associated with vascular complications in patients with type 2 diabetes

AIMS

Tissue accumulatedadvanced glycation end products (AGEs) can be evaluated non-invasively by an autofluorescence reader as skin autofluorescence (skin AF)·The present study investigated whether skin AF is associated with diabetic micro- and macroangiopathies in Japanese patients with type 2 diabetes mellitus (T2DM).

METHODS

Skin AF was measured in 193 enrolled Japanese patients with T2DM and 24 enrolled healthy non-diabetic subjects by using the AGE reader®. Diabetic micro- and macroangiopathies were evaluated in the T2DM patients.

RESULTS

Skin AF was significantly increased in patients with T2DM than in age- and sex-matched non-diabetic controls (2.35 ± 0.51 [mean ± SD] and 1.91 ± 0.29, respectively, p = 0.001). In subjects with T2DM, skin AF was associated with age, pack-years of smoking, and eGFR (estimated glomerular filtration rate) independently. Skin AF was significantly increased in patients with diabetic retinopathy, neuropathy, nephropathy, and macroangiopathy than in those without them, and significantly associated with the number of diabetic complications. Moreover, skin AF was an independent predictor for diabetic retinopathy, neuropathy, and nephropathy but not macroangiopathy, after adjusting for major traditional risk factors.

CONCLUSIONS

Skin AF is an independent predictor for diabetic retinopathy, neuropathy and nephropathy in Japanese patients with T2DM.

Association between Subclinical Atherosclerosis Markers and the Level of Accumulated Advanced Glycation End-Products in the Skin of Patients with Diabetes

Aim: The level of accumulated advanced glycation end-products (AGEs) in the skin has been shown to predict the risk of complications in patients with diabetes mellitus (DM). Recently, the level of accumulated fluorescent AGEs in the skin has become measurable as skin autofluorescence (skin AF) using a non-invasive apparatus, autofluorescence reader. The purpose of this study was to evaluate the association between skin AF and the subclinical atherosclerosis markers, especially endothelial dysfunction, in patients with DM.

Methods: We enrolled 140 Japanese subjects with DM who attended Osaka University Hospital, and measured the skin level of AGEs by skin AF and three subclinical atherosclerosis markers: endothelial function by flow-mediated vasodilation, FMD; carotid intima-media thickness, IMT; and brachial-ankle pulse wave velocity, baPWV.

Results: FMD was significantly associated with skin AF (r = −0.259, p = 0.002). Furthermore, a stepwise multivariate regression analysis revealed that skin AF was an independent determinant of FMD (β = −0.180, p = 0.038). Although there were significant associations between skin AF and maximum carotid intima-media thickness (max-IMT)(r = 0.298, p < 0.001) as well as baPWV (r = 0.284, p = 0.001) in univariate analysis, skin AF was not an independent determinant of either carotid max-IMT or baPWV after adjustment for conventional cardiovascular risk factors. Receiver-operating characteristic curve analysis revealed that skin AF can identify the subjects whose FMD, max-IMT, and baPWV were completely within the normal range (C-statistics, 0.73; 95% confidence interval, 0.61–0.84; p < 0.001).

Conclusions: Skin AF was independently associated with FMD as an indicator of endothelial dysfunction, and can be utilized as a screening marker of atherosclerosis in Japanese patients with DM.

Exploring the molecular mechanisms underlying α- and β-cell dysfunction in diabetes

Pancreatic islet dysfunction, including impaired insulin secretion in β cells and dysregulated glucagon secretion in α cells, is the chief pathology of diabetes. In β cells, oxidative stress, evoked by chronic hyperglycemia, was found to induce dysfunction of a critical transcription factor, PDX1, caused by its nucleocytoplasmic translocation via interactions with the insulin and JNK signaling pathways and another transcription factor, FOXO1. The significance of α-cell insulin signaling in the physiological and pathological regulation of α-cell biology was demonstrated in α-cell-specific insulin receptor knockout mice, which exhibited dysregulated glucagon secretion. Moreover, a high-glucose load directly induced excessive glucagon secretion in a glucagon-secreting cell line and isolated islets, together with impairment of insulin signaling. These findings indicate that disordered insulin signaling is central to the pathophysiology of islet dysfunction in both α and β cells. On the other hand, certain beneficial effects of GLP-1 on dysfunctional α and β cells indicate that it has therapeutic potential for diabetes patients who exhibit insulin resistance in islets. These studies, involving basic medical research approaches, have-at least in part-clarified the molecular mechanisms underlying α- and β-cell dysfunction in diabetes, and offer important clues that should aid the development of future therapeutic approaches to the disease.

GLP-1 signalling compensates for impaired insulin signalling in regulating beta cell proliferation in βIRKO mice

AIMS/HYPOTHESIS

We aimed to investigate potential interactions between insulin and glucagon-like peptide (GLP)-1 signalling pathways in the regulation of beta cell-cycle dynamics in vivo, in the context of the therapeutic potential of GLP-1 to modulate impaired beta cell function.

METHODS

Beta cell-specific insulin receptor knockout (βIRKO) mice, which exhibit beta cell dysfunction and an age-dependent decrease in beta cell mass, were treated with the dipeptidyl peptidase-4 inhibitor vildagliptin. Following this, glucose homeostasis and beta cell proliferation were evaluated and underlying molecular mechanisms were investigated.

RESULTS

The sustained elevation in circulating GLP-1 levels, caused by treatment of the knockout mice with vildagliptin for 6 weeks, significantly improved glucose tolerance secondary to enhanced insulin secretion and proliferation of beta cells. Treating βIRKO beta cell lines with the GLP-1 analogue, exendin-4, promoted Akt phosphorylation and protein expression of cyclins A, D1 and E two- to threefold, in addition to cyclin D2. Pancreases from the vildagliptin-treated βIRKO mice exhibited increased cyclin D1 expression, while cyclin D2 expression was impaired.

CONCLUSIONS/INTERPRETATION

Activation of GLP-1 signalling compensates for impaired growth factor (insulin) signalling and enhances expression of cyclins to promote beta cell proliferation. Together, these data indicate the potential of GLP-1-related therapies to enhance beta cell proliferation and promote beneficial outcomes in models with dysfunctional beta cells.

Mafa Enables Pdx1 to Effectively Convert Pancreatic Islet Progenitors and Committed Islet α-Cells Into β-Cells In Vivo

Among the therapeutic avenues being explored for replacement of the functional islet β-cell mass lost in type 1 diabetes (T1D), reprogramming of adult cell types into new β-cells has been actively pursued. Notably, mouse islet α-cells will transdifferentiate into β-cells under conditions of near β-cell loss, a condition similar to T1D. Moreover, human islet α-cells also appear to poised for reprogramming into insulin-positive cells. Here we have generated transgenic mice conditionally expressing the islet β-cell-enriched Mafa and/or Pdx1 transcription factors to examine their potential to transdifferentiate embryonic pan-islet cell Ngn3-positive progenitors and the later glucagon-positive α-cell population into β-cells. Mafa was found to both potentiate the ability of Pdx1 to induce β-cell formation from Ngn3-positive endocrine precursors and enable Pdx1 to produce β-cells from α-cells. These results provide valuable insight into the fundamental mechanisms influencing islet cell plasticity in vivo.

Skin Autofluorescence is Associated with Early-stage Atherosclerosis in Patients with Type 1 Diabetes

AIM

Accumulation level of fluorescent advanced glycation end products (AGEs) in the skin can be measured non-invasively as skin autofluorescence (skin AF) by autofluorescence reader. The aim of this study was to assess possible associations between skin AF and diabetic complications, especially early-stage atherosclerosis, in Japanese type 1 diabetic patients.

METHODS

Skin AF was measured by AGE reader® in 105 Japanese type 1 diabetic patients (34 men and 71 women, aged 37.4±12.4 years (±SD)) and 23 age-matched healthy non-diabetic subjects. Ultrasonic carotid intima-media thickness (IMT), ankle-brachial index (ABI), and brachial ankle pulse wave velocity (baPWV) were evaluated as indices of early-stage diabetic macroangiopathy. Urinary albumin-to-creatinine ratio (UACR), the coefficient of variation of R-R intervals (CVR-R), and presence of retinopathy were also evaluated.

RESULTS

Skin AF values were significantly higher in type 1 diabetic patients than in healthy controls (2.07±0.50 (mean±SD) and 1.90±0.26, respectively, p=0.024). Skin AF was associated with carotid IMT (r=0.446, p＜0.001) and baPWV (r=0.450, p＜0.001), but not with ABI (r=－0.019, p=0.8488). Notably, skin AF was an independent risk factor for IMT thickening. Similarly, skin AF was associated with log (UACR) (r=0.194, p=0.049) and was an independent risk factor for UACR. Furthermore, skin AF values were significantly higher in patients with diabetic retinopathy than in those without (2.21±0.08 and 1.97±0.06, respectively, p=0.020).

CONCLUSIONS

Skin AF was significantly associated with the presence and/or severity of diabetic complications and was an independent risk factor for carotid atherosclerosis.

Significant elevation of serum dipeptidyl peptidase-4 activity in young-adult type 1 diabetes

AIMS

Currently, inhibition of dipeptidyl peptidase-4 (DPP-4) is widely used in the treatment of type 2 diabetes. Application of this strategy is awaited as a new therapeutic approach for type 1 diabetes, but the scientific basis is still lacking. This report describes the evaluation of serum DPP-4 activity in type 1 diabetes compared with control subjects, and assessment of relationships between DPP-4 activity and diabetic complication markers and metabolic variables in type 1 diabetes.

METHODS

We examined serum DPP-4 activity in Japanese young-adult type 1 diabetes (n=76, females 69.7%, age 30.9 ± 6.2 years, duration of diabetes 16.5 ± 11.1 years; mean ± SD) and healthy controls (n=22). Association of the enzymatic activity with diabetic micro- and macro- vascular complication markers and clinical parameters was also assessed.

RESULTS

Subjects with type 1 diabetes displayed significantly higher serum DPP-4 activity than healthy controls (relative value, control: 1.00 ± 0.28, T1D, 1.29 ± 0.38; p=0.0011) independent of other clinical parameters. In type 1 diabetes, DPP-4 activity was positively correlated with duration of diabetes (r=0.248, p=0.031), while not correlated with HbA1c level. In univariate correlation analysis of diabetic complication markers and other metabolic parameters, coefficient of variation of R-R intervals (CVR-R) and gamma (γ)-glutamyltransferase (GGT) levels were correlated with DPP-4 activity. GGT was extracted as an independent variable of DPP-4 activity in multivariate analysis (β=0.213, p=0.035).

CONCLUSIONS

Serum DPP-4 activity is significantly elevated in Japanese type 1 diabetes, suggesting pathophysiological significance of the enzyme in type 1 diabetes.

Association between new onset diabetic retinopathy and monocyte chemoattractant protein-1 (MCP-1) polymorphism in Japanese type 2 diabetes

We longitudinally evaluated the association between monocyte chemoattractant protein-1 (MCP-1) A-2518G polymorphism and new onset of diabetic retinopathy in 758 type 2 diabetic patients. The new onset of retinopathy increased with the increase of the number of G alleles, even after adjustment for age, HbA1c levels, and duration of diabetes.

Vitamin D deficiency is significantly associated with retinopathy in young Japanese type 1 diabetic patients

The aim of this study was to examine the possible association of vitamin D deficiency with diabetic retinopathy in 75 young Japanese type 1 diabetic patients. A multivariate regression analysis, duration of diabetes and vitamin D deficiency were independent determinants of diabetic retinopathy.

Soluble factors secreted by T cells promote β-cell proliferation

Type 1 diabetes is characterized by infiltration of pancreatic islets with immune cells, leading to insulin deficiency. Although infiltrating immune cells are traditionally considered to negatively impact β-cells by promoting their death, their contribution to proliferation is not fully understood. Here we report that islets exhibiting insulitis also manifested proliferation of β-cells that positively correlated with the extent of lymphocyte infiltration. Adoptive transfer of diabetogenic CD4(+) and CD8(+) T cells, but not B cells, selectively promoted β-cell proliferation in vivo independent from the effects of blood glucose or circulating insulin or by modulating apoptosis. Complementary to our in vivo approach, coculture of diabetogenic CD4(+) and CD8(+) T cells with NOD.RAG1(-/-) islets in an in vitro transwell system led to a dose-dependent secretion of candidate cytokines/chemokines (interleukin-2 [IL-2], IL-6, IL-10, MIP-1α, and RANTES) that together enhanced β-cell proliferation. These data suggest that soluble factors secreted from T cells are potential therapeutic candidates to enhance β-cell proliferation in efforts to prevent and/or delay the onset of type 1 diabetes.

Absence of diabetes and pancreatic exocrine dysfunction in a transgenic model of carboxyl-ester lipase-MODY (maturity-onset diabetes of the young)

Background

CEL-MODY is a monogenic form of diabetes with exocrine pancreatic insufficiency caused by mutations in CARBOXYL-ESTER LIPASE (CEL). The pathogenic processes underlying CEL-MODY are poorly understood, and the global knockout mouse model of the CEL gene (CELKO) did not recapitulate the disease. We therefore aimed to create and phenotype a mouse model specifically over-expressing mutated CEL in the pancreas.

Methods

We established a monotransgenic floxed (flanking LOX sequences) mouse line carrying the human CEL mutation c.1686delT and crossed it with an elastase-Cre mouse to derive a bitransgenic mouse line with pancreas-specific over-expression of CEL carrying this disease-associated mutation (TgCEL). Following confirmation of murine pancreatic expression of the human transgene by real-time quantitative PCR, we phenotyped the mouse model fed a normal chow and compared it with mice fed a 60% high fat diet (HFD) as well as the effects of short-term and long-term cerulein exposure.

Results

Pancreatic exocrine function was normal in TgCEL mice on normal chow as assessed by serum lipid and lipid-soluble vitamin levels, fecal elastase and fecal fat absorption, and the normoglycemic mice exhibited normal pancreatic morphology. On 60% HFD, the mice gained weight to the same extent as controls, had normal pancreatic exocrine function and comparable glucose tolerance even after resuming normal diet and follow up up to 22 months of age. The cerulein-exposed TgCEL mice gained weight and remained glucose tolerant, and there were no detectable mutation-specific differences in serum amylase, islet hormones or the extent of pancreatic tissue inflammation.

Conclusions

In this murine model of human CEL-MODY diabetes, we did not detect mutation-specific endocrine or exocrine pancreatic phenotypes, in response to altered diets or exposure to cerulein.

Rosiglitazone promotes PPARγ-dependent and -independent alterations in gene expression in mouse islets

The glitazone class of insulin-sensitizing agents act, in part, by the activation of peroxisome proliferator-activated receptor (PPAR)-γ in adipocytes. However, it is unclear whether the expression of PPARγ in the islets is essential for their potential β-cell-sparing properties. To investigate the in vivo effects of rosiglitazone on β-cell biology, we used an inducible, pancreatic and duodenal homeobox-1 enhancer element-driven, Cre recombinase to knockout PPARγ expression specifically in adult β-cells (PPARgKO). Subjecting the PPARgKO mice to a chow diet led to virtually undetectable changes in glucose or insulin sensitivity, which was paralleled by minimal changes in islet gene expression. Similarly, challenging the mutant mice with a high-fat diet and treatment with rosiglitazone did not alter insulin sensitivity, glucose-stimulated insulin secretion, islet size, or proliferation in the knockout mice despite PPARγ-dependent and -independent changes in islet gene expression. These data suggest that PPARγ expression in the β-cells is unlikely to be directly essential for normal β-cell function or the insulin-sensitizing actions of rosiglitazone.

Large adrenal ganglioneuroma

We herein report the case of a 41-year-old male patient with an incidentally identified large adrenal ganglioneuroma (GN). His endocrine examinations were normal except for one episode of elevated urinary dopamine and noradrenaline levels. Abdominal computed tomography (CT) and magnetic resonance imaging (MRI) showed a large solid tumor with calcifications and a slightly lobular edge in the right adrenal gland. We performed open tumor excision and diagnosed it as adrenal ganglioneuroma. Adrenal GN is a rare benign tumor, and its hormonal activity and imaging characteristics are occasionally very similar to those of other adrenal tumors. Therefore, it needs careful evaluation by endocrine examinations and multiple imaging procedures to rule out other types of tumors.

Growth factor signalling in the regulation of α-cell fate

Glucagon plays critical roles in regulating glucose homeostasis, mainly by counteracting the effects of insulin. Consequently, the dysregulated glucagon secretion that is evident in type 2 diabetes has significant implications in the pathophysiology of the disease. Glucagon secretion from pancreatic α-cells has been suggested to be modulated by blood glucose, signals from the nervous system and endocrine components. In addition to these regulators, intraislet factors acting in a paracrine manner from neighbouring β-cells are emerging as central modulator(s) of α-cell biology. One of the most important of these paracrine factors, insulin, modulates glucagon secretion. Indeed, the α-cell-specific insulin receptor knockout (αIRKO) mouse manifests hypersecretion of glucagon in the postprandial stage and exhibits defective secretion in fasting-induced hypoglycaemia, together mimicking the α-cell defects observed in type 2 diabetes. Interestingly, αIRKO mice display a progressive increase in β-cell mass and a concomitant decrease in α-cells. Lineage trace analyses reveal that the new β-cells originate, in part, from the insulin receptor-deficient α-cells indicating a critical role for α-cell insulin signalling in determining β-cell origin. Our studies also reveal that glucagon-like peptide-1 (GLP-1) treatment of αIRKO mice suppresses glucagon secretion despite absence of functional insulin receptors precluding a role for insulin in GLP-1 action on α-cells in this model. These findings highlight the significance of insulin signalling in the regulation of α-cell biology.

[Effects of incretins on the regulation of beta-cell mass, proliferation and survival]

Incretins including GLP-1 and GIP have pleiotropic effects on islet biology especially on beta-cell function. Not only enhancing glucose-stimulated insulin secretion, but incretins exert beta-cell mass maintaining effects by upregulation of proliferation and prevention of cell death (apoptosis). Recent research data revealed detailed molecular mechanisms underlying these effects of incretin on beta-cell biology. These beneficial effects of incretins on the regulation of beta-cell mass could contribute to future therapeutic approaches to diabetes focusing on preservation and upregulation of beta-cell mass as well as function.

Δ40 Isoform of p53 controls β-cell proliferation and glucose homeostasis in mice

OBJECTIVE

Investigating the dynamics of pancreatic β-cell mass is critical for developing strategies to treat both type 1 and type 2 diabetes. p53, a key regulator of the cell cycle and apoptosis, has mostly been a focus of investigation as a tumor suppressor. Although p53 alternative transcripts can modulate p53 activity, their functions are not fully understood. We hypothesized that β-cell proliferation and glucose homeostasis were controlled by Δ40p53, a p53 isoform lacking the transactivation domain of the full-length protein that modulates total p53 activity and regulates organ size and life span in mice.

RESEARCH DESIGN AND METHODS

We phenotyped metabolic parameters in Δ40p53 transgenic (p44tg) mice and used quantitative RT-PCR, Western blotting, and immunohistochemistry to examine β-cell proliferation.

RESULTS

Transgenic mice with an ectopic p53 gene encoding Δ40p53 developed hypoinsulinemia and glucose intolerance by 3 months of age, which worsened in older mice and led to overt diabetes and premature death from ∼14 months of age. Consistent with a dramatic decrease in β-cell mass and reduced β-cell proliferation, lower expression of cyclin D2 and pancreatic duodenal homeobox-1, two key regulators of proliferation, was observed, whereas expression of the cell cycle inhibitor p21, a p53 target gene, was increased.

CONCLUSIONS

These data indicate a significant and novel role for Δ40p53 in β-cell proliferation with implications for the development of age-dependent diabetes.

Pancreatic function in carboxyl-ester lipase knockout mice

BACKGROUND/AIMS

CEL-MODY is a monogenic form of diabetes and exocrine pancreatic insufficiency due to mutations in the carboxyl-ester lipase (CEL) gene. We aimed to investigate endocrine and exocrine pancreatic function in CEL knockout mice (CELKO).

METHODS

A knockout mouse model with global targeted deletion of CEL was investigated physiologically and histopathologically, and compared to littermate control CEL+/+ mice at 7 and 12 months on normal chow and high-fat diets (HFD), i.e. 42 and 60% fat by calories.

RESULTS

CELKO+/+ and -/- mice showed normal growth and development and normal glucose metabolism on a chow diet. Female CEL-/- mice on 60% HFD, on the other hand, had increased random blood glucose compared to littermate controls (p = 0.02), and this was accompanied by a reduction in glucose tolerance that did not reach statistical significance. In these mice there was also islet hyperplasia, however, α- and β-islet cells appeared morphologically normal and pancreatic exocrine function was also normal.

CONCLUSION

Although we observed mild glucose intolerance in female mice with whole-body knockout of CEL, the full phenotype of human CEL-MODY was not reproduced, suggesting that the pathogenic mechanisms involved are more complex than a simple loss of CEL function. and IAP.

The pseudokinase tribbles homolog 3 interacts with ATF4 to negatively regulate insulin exocytosis in human and mouse beta cells

Insufficient insulin secretion and reduced pancreatic beta cell mass are hallmarks of type 2 diabetes (T2DM). Here, we confirm that a previously identified polymorphism (rs2295490/Q84R) in exon 2 of the pseudokinase-encoding gene tribbles 3 (TRB3) is associated with an increased risk for T2DM in 2 populations of people of mixed European descent. Carriers of the 84R allele had substantially reduced plasma levels of C-peptide, the product of proinsulin processing to insulin, suggesting a role for TRB3 in beta cell function. Overexpression of TRB3 84R in mouse beta cells, human islet cells, and the murine beta cell line MIN6 revealed reduced insulin exocytosis, associated with a marked reduction in docked insulin granules visualized by electron microscopy. Conversely, knockdown of TRB3 in MIN6 cells restored insulin secretion and expression of exocytosis genes. Further analysis in MIN6 cells demonstrated that TRB3 interacted with the transcription factor ATF4 and that this complex acted as a competitive inhibitor of cAMP response element-binding (CREB) transcription factor in the regulation of key exocytosis genes. In addition, the 84R TRB3 variant exhibited greater protein stability than wild-type TRB3 and increased binding affinity to Akt. Mice overexpressing TRB3 84R in beta cells displayed decreased beta cell mass, associated with reduced proliferation and enhanced apoptosis rates. These data link a missense polymorphism in human TRB3 to impaired insulin exocytosis and thus increased risk for T2DM.

Cyclin D2 is essential for the compensatory beta-cell hyperplastic response to insulin resistance in rodents

OBJECTIVE

A major determinant of the progression from insulin resistance to the development of overt type 2 diabetes is a failure to mount an appropriate compensatory beta-cell hyperplastic response to maintain normoglycemia. We undertook the present study to directly explore the significance of the cell cycle protein cyclin D2 in the expansion of beta-cell mass in two different models of insulin resistance.

RESEARCH DESIGN AND METHODS

We created compound knockouts by crossing mice deficient in cyclin D2 (D2KO) with either the insulin receptor substrate 1 knockout (IRS1KO) mice or the insulin receptor liver-specific knockout mice (LIRKO), neither of which develops overt diabetes on its own because of robust compensatory beta-cell hyperplasia. We phenotyped the double knockouts and used RT-qPCR and immunohistochemistry to examine beta-cell mass.

RESULTS

Both compound knockouts, D2KO/LIRKO and D2KO/IRS1KO, exhibited insulin resistance and hyperinsulinemia and an absence of compensatory beta-cell hyperplasia. However, the diabetic D2KO/LIRKO group rapidly succumbed early compared with a relatively normal lifespan in the glucose-intolerant D2KO/IRS1KO mice.

CONCLUSIONS

This study provides direct genetic evidence that cyclin D2 is essential for the expansion of beta-cell mass in response to a spectrum of insulin resistance and points to the cell-cycle protein as a potential therapeutic target that can be harnessed for preventing and curing type 2 diabetes.

Glucagon-like peptide-1 increases beta-cell glucose competence and proliferation by translational induction of insulin-like growth factor-1 receptor expression

Glucagon-like peptide-1 (GLP-1) protects beta-cells against apoptosis, increases their glucose competence, and induces their proliferation. We previously demonstrated that the anti-apoptotic effect was mediated by an increase in insulin-like growth factor-1 receptor (IGF-1R) expression and signaling, which was dependent on autocrine secretion of insulin-like growth factor 2 (IGF-2). Here, we further investigated how GLP-1 induces IGF-1R expression and whether the IGF-2/IGF-1R autocrine loop is also involved in mediating GLP-1-increase in glucose competence and proliferation. We show that GLP-1 up-regulated IGF-1R expression by a protein kinase A-dependent translational control mechanism, whereas isobutylmethylxanthine, which led to higher intracellular accumulation of cAMP than GLP-1, increased both IGF-1R transcription and translation. We then demonstrated, using MIN6 cells and primary islets, that the glucose competence of these cells was dependent on the level of IGF-1R expression and on IGF-2 secretion. We showed that GLP-1-induced primary beta-cell proliferation was suppressed by Igf-1r gene inactivation and by IGF-2 immunoneutralization or knockdown. Together our data show that regulation of beta-cell number and function by GLP-1 depends on the cAMP/protein kinase A mediated-induction of IGF-1R expression and the increased activity of an IGF-2/IGF-1R autocrine loop.

Insulin modulation of glucagon secretion: the role of insulin and other factors in the regulation of glucagon secretion

Glucagon plays a critical counter-regulatory role to insulin to maintain optimal glucose homeostasis. Glucagon secretion from pancreatic α-cells is regulated by glycemia, neural input, and secretion from neighboring β-cells. Recently, we provided direct genetic evidence of a critical role for insulin signaling in the regulation of glucagon secretion in vivo. Pancreatic α-cell targeted disruption of insulin receptor expression in mice resulted in glucose intolerance, hyperglycemia and hyperglucagonemia coupled with an abnormal glucagon response to hypoglycemia. Furthermore, streptozotocin treated mice exhibited paradoxically increased plasma glucagon suggesting a dominant role for insulin in the regulation of glucagon secretion compared with glucose. In fact, normalization of hyperglycemia by phrolidzin treatment decreased plasma glucagon levels suggesting a stimulatory effect of glucose on glucagon secretion and also revealed the significance of insulin in hyperglycemic states. Together these studies provide novel insights into intra-islet regulatory pathways in the modulation of glucagon secretion and provide potential opportunities to develop therapeutic approaches for the correction of α-cell dysfunction in diabetes.

PDX-1 functions as a master factor in the pancreas

Various pancreatic transcription factors are involved in pancreas development and beta-cell differentiation. Among them, pancreatic and duodenal homeobox factor-1 (PDX-1) plays a crucial role in pancreas development and beta-cell differentiation, and maintaining mature beta-cell function. MafA is a recently isolated beta-cell-specific transcription factor and functions as a potent activator of insulin gene transcription. These pancreatic transcription factors also play a crucial role in inducing surrogate beta-cells from non-beta-cells and thus could be therapeutic targets for diabetes. On the other hand, under diabetic conditions, expression and/or activities of PDX-1 and MafA in beta-cells are reduced, which leads to suppression of insulin biosynthesis and secretion. Thus, it is likely that alteration of such transcription factors explains, at least in part, the molecular mechanism for beta-cell glucose toxicity found in diabetes.

PDX-1 and MafA play a crucial role in pancreatic beta-cell differentiation and maintenance of mature beta-cell function

Pancreatic and duodenal homeobox factor-1 (PDX-1) plays a crucial role in pancreas development, beta-cell differentiation, and maintenance of mature beta-cell function. PDX-1 expression is maintained in pancreatic precursor cells during pancreas development but becomes restricted to beta-cells in mature pancreas. In mature beta-cells, PDX-1 transactivates the insulin and other genes involved in glucose sensing and metabolism such as GLUT2 and glucokinase. MafA is a recently isolated beta-cell-specific transcription factor which functions as a potent activator of insulin gene transcription. Furthermore, these transcription factors play an important role in induction of insulin-producing cells in various non-beta-cells and thus could be therapeutic targets for diabetes. On the other hand, under diabetic conditions, expression and/or activities of PDX-1 and MafA in beta-cells are reduced, which leads to suppression of insulin biosynthesis and secretion. It is likely that alteration of such transcription factors explains, at least in part, the molecular mechanism for beta-cell glucose toxicity found in diabetes.

Abnormal glucose homeostasis in skeletal muscle-specific PGC-1alpha knockout mice reveals skeletal muscle-pancreatic beta cell crosstalk

The transcriptional coactivator PPARgamma coactivator 1alpha (PGC-1alpha) is a strong activator of mitochondrial biogenesis and oxidative metabolism. While expression of PGC-1alpha and many of its mitochondrial target genes are decreased in the skeletal muscle of patients with type 2 diabetes, no causal relationship between decreased PGC-1alpha expression and abnormal glucose metabolism has been established. To address this question, we generated skeletal muscle-specific PGC-1alpha knockout mice (MKOs), which developed significantly impaired glucose tolerance but showed normal peripheral insulin sensitivity. Surprisingly, MKOs had expanded pancreatic beta cell mass, but markedly reduced plasma insulin levels, in both fed and fasted conditions. Muscle tissue from MKOs showed increased expression of several proinflammatory genes, and these mice also had elevated levels of the circulating IL-6. We further demonstrated that IL-6 treatment of isolated mouse islets suppressed glucose-stimulated insulin secretion. These data clearly illustrate a causal role for muscle PGC-1alpha in maintenance of glucose homeostasis and highlight an unexpected cytokine-mediated crosstalk between skeletal muscle and pancreatic islets.

Oxidative stress and the JNK pathway are involved in the development of type 1 and type 2 diabetes

Failure of pancreatic beta-cells is the common characteristic of type 1 and type 2 diabetes. Type 1 diabetes mellitus is induced by destruction of pancreatic beta-cells which is mediated by an autoimmune mechanism and consequent inflammatory process. Various inflammatory cytokines and oxidative stress are produced during this process, which has been proposed to play an important role in mediating beta-cell destruction. The JNK pathway is also activated by such cytokines and oxidative stress, and is involved in beta-cell destruction. Type 2 diabetes is the most prevalent and serious metabolic disease, and beta-cell dysfunction and insulin resistance are the hallmark of type 2 diabetes. Under diabetic conditions, chronic hyperglycemia gradually deteriorates beta-cell function and aggravates insulin resistance. This process is called "glucose toxicity". Under such conditions, oxidative stress is provoked and the JNK pathway is activated, which is likely involved in pancreatic beta-cells dysfunction and insulin resistance. In addition, oxidative stress and activation of the JNK pathway are also involved in the progression of atherosclerosis which is often observed under diabetic conditions. Taken together, it is likely that oxidative stress and subsequent activation of the JNK pathway are involved in the pathogenesis of type 1 and type 2 diabetes.

Pleiotropic Roles of PDX-1 in the Pancreas

It is well known that pancreatic and duodenal homeobox factor-1 (PDX-1) plays a pleiotropic role in the pancreas. In the developing pancreas, PDX-1 is involved in both pancreas formation and beta-cell differentiation. In mature beta-cells, PDX-1 transactivates insulin and other beta-cell-related genes such as GLUT2 and glucokinase. Furthermore, PDX-1 plays an important role in the induction of insulin-producing cells in various non-beta-cells and is thereby a possible therapeutic target for diabetes. On the other hand, under diabetic conditions, expression and/or activity of PDX-1 in beta-cells is reduced, which leads to suppression of insulin biosynthesis and secretion. It is likely that PDX-1 inactivation explains, at least in part, the molecular mechanism for beta-cell glucose toxicity found in diabetes.

MafA regulates expression of genes important to islet beta-cell function

Insulin transcription factor MafA is unique in being exclusively expressed at the secondary and principal phase of insulin-expressing cell production during pancreas organogenesis and is the only transcriptional activator present exclusively in islet beta-cells. Here we show that ectopic expression of MafA is sufficient to induce a small amount of endogenous insulin expression in a variety of non-beta-cell lines. Insulin mRNA and protein expression was induced to a much higher level when MafA was provided with two other key insulin activators, pancreatic and duodenal homeobox (PDX-1) and BETA2. Potentiation by PDX-1 and BETA2 was entirely dependent upon MafA, and MafA binding to the insulin enhancer region was increased by PDX-1 and BETA2. Treatment with activin A and hepatocyte growth factor induced even larger amounts of insulin in AR42J pancreatic acinar cells, compared with other non-beta endodermal cells. The combination of PDX-1, BETA2, and MafA also induced the expression of other important regulators of islet beta-cell activity. These results support a critical role of MafA in islet beta-cell function.

Involvement of oxidative stress in the pathogenesis of diabetes

Pancreatic beta-cell failure is the common characteristic of type 1 and type 2 diabetes. Type 1 diabetes is induced by pancreatic beta-cell destruction, which is mediated by an autoimmune mechanism and consequent inflammatory process. Various inflammatory cytokines and oxidative stress produced by islet-infiltrating immune cells have been proposed to play an important role in mediating the destruction of beta cells. The JNK pathway is also activated by such cytokines and oxidative stress and is involved in beta-cell destruction. Type 2 diabetes is the most prevalent and serious metabolic disease affecting people all over the world. Pancreatic beta-cell dysfunction and insulin resistance are the hallmark of type 2 diabetes. Once hyperglycemia becomes apparent, beta-cell function gradually deteriorates, and insulin resistance is aggravated. This process is called "glucose toxicity." Under such conditions, oxidative stress is provoked, and the JNK pathway is activated, which is likely involved in pancreatic beta-cell dysfunction and insulin resistance. In addition, oxidative stress and activation of the JNK pathway are involved in the progression of atherosclerosis, which is often observed under diabetic conditions. Taken together, it is likely that oxidative stress and subsequent activation of the JNK pathway are involved in the pathogenesis of type 1 and type 2 diabetes.

PDX-1 and MafA in β-cell differentiation and dysfunction

Pancreatic and duodenal homeobox factor-1 (PDX-1) plays crucial roles in pancreas development and β-cell differentiation, and in maintaining mature β-cell function. MafA is a recently isolated β-cell-specific transcription factor that functions as a potent activator of insulin gene transcription. Also, these pancreatic transcription factors play a crucial role in inducing surrogate β-cells from non-β-cells and, thus, could be therapeutic targets for diabetes. Conversely, expression and/or activities of PDX-1 and MafA in β-cells are reduced under diabetic conditions, which leads to suppression of insulin biosynthesis and secretion. It is likely that alteration of such transcription factors explains, at least in part, the molecular mechanism for β-cell glucose toxicity.

Association of soluble CD40 ligand with carotid atherosclerosis in Japanese type 1 diabetic patients

AIMS/HYPOTHESIS

It has recently been shown that the soluble form of CD40 ligand (sCD40L) interacts with CD40 on vascular cells, leading to a variety of proinflammatory responses, and that serum sCD40L levels can be a predictive marker of cardiovascular events. The aim of this study was to estimate sCD40L levels in type 1 diabetic patients to examine a possible association with carotid atherosclerosis.

SUBJECTS AND METHODS

Human sCD40L levels in serum and intima-media thickness (IMT) of carotid artery were examined in 80 Japanese type 1 diabetic patients (27 men and 53 women, age 22.8+/-3.4 years (mean+/-SD), duration of diabetes 13.2+/-6.1 years) and 20 healthy age-matched non-diabetic individuals.

RESULTS

Serum sCD40L levels were significantly (p=0.0185) higher in subjects with type 1 diabetes (2.10+/-1.33 ng/ml) compared with non-diabetic subjects (1.35+/-0.88 ng/ml). The greatest IMT (Max-IMT) and averaged IMT (Mean-IMT) were also significantly greater in patients with type 1 diabetes than in control subjects (0.73+/-0.14 vs 0.64+/-0.07 mm, p=0.0041, 0.63+/-0.09 vs 0.57+/-0.06 mm, p=0.0066, respectively). Levels of sCD40L were statistically significantly associated with Max-IMT (r=0.383, p<0.001) and Mean-IMT (r=0.275, p=0.0058). Furthermore, stepwise multivariate regression analyses demonstrated that sCD40L is a determinant of both Max- and Mean-IMT, independently of conventional risk factors.

CONCLUSIONS/INTERPRETATION

It is suggested that increased levels of serum sCD40L are associated with accelerated atherosclerotic change observed in young patients with type 1 diabetes.

Role of oxidative stress, endoplasmic reticulum stress, and c-Jun N-terminal kinase in pancreatic β-cell dysfunction and insulin resistance

Type 2 diabetes is the most prevalent and serious metabolic disease affecting people all over the world. Pancreatic beta-cell dysfunction and insulin resistance are the hallmark of type 2 diabetes. Normal beta-cells can compensate for insulin resistance by increasing insulin secretion and/or beta-cell mass, but insufficient compensation leads to the onset of glucose intolerance. Once hyperglycemia becomes apparent, beta-cell function gradually deteriorates and insulin resistance aggravates. Under diabetic conditions, oxidative stress and endoplasmic reticulum stress are induced in various tissues, leading to activation of the c-Jun N-terminal kinase pathway. The activation of c-Jun N-terminal kinase suppresses insulin biosynthesis and interferes with insulin action. Indeed, suppression of c-Jun N-terminal kinase in diabetic mice improves insulin resistance and ameliorates glucose tolerance. Thus, the c-Jun N-terminal kinase pathway plays a central role in pathogenesis of type 2 diabetes and could be a potential target for diabetes therapy.

Beneficial effects of nateglinide on insulin resistance in type 2 diabetes

Nateglinide, a rapid insulin secretagogue, is known to facilitate the early phase of insulin secretion and has been used for the treatment of type 2 diabetic patients with postprandial hyperglycemia. The aim of this study is to evaluate the effect of nateglinide on insulin resistance as well as insulin secretory defects in type 2 diabetic patients. Insulin secretion ability was evaluated by the hyperglycemic clamp test, and insulin sensitivity was evaluated by the euglycemic hyperinsulinemic clamp test, using an artificial pancreas. The hyperglycemic clamp test showed that a 7-day treatment with nateglinide significantly increased insulin secretion in response to high glucose. Interestingly, although nateglinide is known to facilitate insulin secretion, daily urinary C-peptide excretion was decreased after nateglinide treatment. Moreover, in the euglycemic hyperinsulinemic clamp test, glucose infusion rate was significantly increased by nateglinide treatment, indicating that nateglinide functions to decrease insulin resistance. Nateglinide ameliorates insulin resistance as well as insulin secretory defects in type 2 diabetic patients.

Increased stress protein ORP150 autoantibody production in Type 1 diabetic patients

AIMS

Various genetic and environmental stresses interfere with protein folding in the endoplasmic reticulum (ER), which leads to the induction of ER stress. It has recently been reported that ER stress is involved in the development of diabetes in diabetic animal models. The aim of this study is to estimate ER stress levels in Type 1 diabetic patients.

METHODS

We recruited Type 1 diabetic patients undergoing periodic follow-up examinations (n = 91) and healthy non-diabetic individuals (n = 37), and measured their serum anti-oxygen-related protein (ORP)150 autoantibody levels.

RESULTS

Anti-ORP150 autoantibody levels in Type 1 diabetic patients were significantly higher compared with those in healthy non-diabetic subjects. Furthermore, the serum autoantibody levels in Type 1 diabetic patients correlated with HbA(1c) (F > 3.0, P = 0.079), indicating that hyperglycaemia itself induces ER stress in diabetes.

CONCLUSIONS

Anti-ORP150 autoantibody levels in Type 1 diabetic patients are higher compared with non-diabetic subjects, suggesting that ER stress is increased in Type 1 diabetes.