Early Type 1 Diabetes Mellitus Research Articles

RETINAL MICROVASCULOPATHY WITH DIFFERENT INSULIN INFUSION THERAPIES IN CHILDREN WITH TYPE 1 DIABETES MELLITUS WITHOUT CLINICAL DIABETIC RETINOPATHY.

To explore the characteristics and associated factors of retinal microvasculopathy and neurodegeneration with different insulin therapies in children with type 1 diabetes mellitus (T1DM) but without diabetic retinopathy. Forty-one children with T1DM with multiple daily insulin injections (MDI), 22 children with T1DM with continuous subcutaneous insulin infusion, and 62 age-matched normal control children were enrolled. SPECTRALIS Optical coherence tomography was used to scan 6×6 mm square area of posterior retina. The vessel density of superficial vascular plexus, intermediate capillary plexus, and deep capillary plexus in T1DM-MDI group were all significantly lower than those in the T1DM-CSII and control groups (0.39 ± 0.05 vs. 0.44 ± 0.04 and 0.42 ± 0.06, P < 0.001; 0.26 ± 0.04 vs. 0.30 ± 0.02 and 0.28 ± 0.04, P = 0.003; 0.30 ± 0.04 vs. 0.33 ± 0.04 and 0.32 ± 0.04, P = 0.027). In T1DM-MDI group, lower vessel density of superficial vascular plexus was associated with higher hemoglobin A1c (r = -0.377, P = 0.015). Foveal avascular zone morphology index in T1DM-MDI and T1DM-CSII groups were smaller than that in the control group (0.63 ± 0.11 and 0.63 ± 0.12 vs. 0.69 ± 0.15, P = 0.040). There was no statistically significant difference in the thickness of the retina among the three groups ( P > 0.05). The vessel density of posterior retina was lower in children with T1DM with MDI than in healthy control children and associated with higher hemoglobin A1c. There was a significant difference on vessel density betweenT1DM-MDI and T1DM-CSII, with the similar hemoglobin A1c. This study suggested that optical coherence tomography angiography could be beneficial for the detection of retinal abnormalities in children with early T1DM, and continuous subcutaneous insulin infusion may be a better choice than MDI for children with T1DM to prevent the retinal complication.

Renal Hemodynamic Function and RAAS Activation Over the Natural History of Type 1 Diabetes

The renin-angiotensin-aldosterone system (RAAS) is associated with renal and cardiovascular disease in diabetes. Unfortunately, early RAAS blockade in patients with type 1 diabetes mellitus (T1DM) does not prevent the development of complications. We sought to examine the role of hyperfiltration andRAAS activation across a wide range of T1DM duration to better understand renal hemodynamic status in patients with T1DM. Post hoc analysis of blood samples. 148 Canadian patients with T1DM: 28 adolescents (aged 16.2±2.0 years), 54 young adults (25.4±5.6 years), and 66 older adults (65.7±7.5 years) studied in a clinical investigation unit. Angiotensin II infusion (1ng/kg/min; a measure of RAAS activation) during a euglycemic clamp. Glomerular filtration rate measured using inulin clearance, effective renal plasma flow measured using para-aminohippurate, afferent (RA) and efferent (RE) arteriolar resistances, and glomerular hydrostatic pressure estimated using the Gomez equations. In a stepwise fashion, glomerular filtration rate, effective renal plasma flow, and glomerular hydrostatic pressure were higher, while renal vascular resistance and RA were lower in adolescents versus young adults versus older adults. RE was similar in adolescents versus young adults but was higher in older adults. Angiotensin II resulted in blunted renal hemodynamic responses in older adults (renal vascular resistance increase of 3.3% ± 1.6% vs 4.9% ± 1.9% in adolescents; P<0.001), suggesting a state of enhanced RAAS activation. Homogeneous study participants limit the generalizability of findings to other populations. Studying older adult participants with T1DM may be associated with a survivorship bias. A state of relatively low RAAS activity and predominant afferent dilation rather than efferent constriction characterize early adolescents and young adults with T1DM. This state of endogenous RAAS inactivity in early T1DM may explain why pharmacologic blockade of this neurohormonal system is often ineffective in reducing kidney disease progression in this setting. Older adults with long-standing T1DM who have predominant afferent constriction and RAAS activation may experience renoprotection from therapies that target the afferent arteriole. Further work is required to understand the potential role of non-RAAS pharmacologic agents that target RA in patients with early and long-standing T1DM.

Genetic and environmental factors affect the onset of type 1 diabetes mellitus.

Type 1 diabetes mellitus (T1DM) is influenced by genetic as well as environmental factors. Its incidence has risen considerably since the 1950s. This study investigates T1DM time trends from 1989 to 2008 and tries to establish whether breast/bottle feeding, a family history of diabetes, and childhood infectious diseases influence age at onset. The study used the population-based registry of childhood diabetes of Abruzzo (central Italy), which includes incident cases of patients aged less than 15 yr. The pooled 1989-2008 global ascertainment of the registry was 95%. The trend was estimated using age-period-cohort models RESULTS: Overall standardized incidence rates (SIR) increased by 73.38% from 8.94 (1989-1993) to 15.50 (2004-2008). A rising trend was found in all age groups; annual rises were significant for the overall population (3.40%, p < 0.01) and for 5-9 yr olds (5.48%, p < 0.01). SIR increased in males by 106.26%, from 9.26 in 1989-1993 to 19.10 in 2004-2008. Early T1DM onset was related to mixed feeding (6.80 yr ± 3.58 vs 8.20 ± 3.81 yr; p = 0.002), and a family history of T1DM (6.71 ± 3.96 yr vs. 8.09 ± 3.77 yr; p = 0.014), whereas multiple infections delayed age at onset (9.71 ± 2.37 yr vs 7.71 ± 2.82 yr; p = 0.03). T1DM incidence exhibits a rising time trend that is particularly evident in males and in middle age group; mixed feeding and a family history of diabetes are associated with early onset, multiple bacterial infections contracted before diabetes are associated with a significant delay.

Alteration of the bone tissue material properties in type 1 diabetes mellitus: A Fourier transform infrared microspectroscopy study

Type 1 diabetes mellitus (T1DM) is a severe disorder characterized by hyperglycemia and hypoinsulinemia. A higher occurrence of bone fractures has been reported in T1DM, and although bone mineral density is reduced in this disorder, it is also thought that bone quality may be altered in this chronic pathology. Vibrational microscopies such as Fourier transform infrared microspectroscopy (FTIRM) represent an interesting approach to study bone quality as they allow investigation of the collagen and mineral compartment of the extracellular matrix in a specific bone location. However, as spectral feature arising from the mineral may overlap with those of the organic component, the demineralization of bone sections should be performed for a full investigation of the organic matrix. The aims of the present study were to (i) develop a new approach, based on the demineralization of thin bone tissue section to allow a better characterization of the bone organic component by FTIRM, (ii) to validate collagen glycation and collagen integrity in bone tissue and (iii) to better understand what alterations of tissue material properties in newly forming bone occur in T1DM.The streptozotocin-injected mouse (150mg/kg body weight, injected at 8weeks old) was used as T1DM model. Animals were randomly allocated to control (n=8) or diabetic (n=10) groups and were sacrificed 4weeks post-STZ injection. Bones were collected at necropsy, embedded in polymethylmethacrylate and sectioned prior to examination by FTIRM. FTIRM collagen parameters were collagen maturity (area ratio between 1660 and 1690cm−1 subbands), collagen glycation (area ratio between the 1032cm−1 subband and amide I) and collagen integrity (area ratio between the 1338cm−1 subband and amide II).No significant differences in the mineral compartment of the bone matrix could be observed between controls and STZ-injected animals. On the other hand, as compared with controls, STZ-injected animals presented with significant higher value for collagen maturity (17%, p=0.0048) and collagen glycation (99%, p=0.0121), while collagen integrity was significantly lower by 170% (p=0.0121).This study demonstrated the profound effect of early T1DM on the organic compartment of the bone matrix in newly forming bone. Further studies in humans are required to ascertain whether T1DM also lead to similar effect on the quality of the bone matrix.

Deciphering early development of complex diseases by progressive module network

There is no effective cure nowadays for many complex diseases, and thus it is crucial to detect and further treat diseases in earlier stages. Generally, the development and progression of complex diseases include three stages: normal stage, pre-disease stage, and disease stage. For diagnosis and treatment, it is necessary to reveal dynamical organizations of molecular modules during the early development of the disease from the pre-disease stage to the disease stage. Thus, we develop a new framework, i.e. we identify the modules presenting at the pre-disease stage (pre-disease module) based on dynamical network biomarkers (DNBs), detect the modules observed at the advanced stage (disease-responsive module) by cross-tissue gene expression analysis, and finally find the modules related to early development (progressive module) by progressive module network (PMN). As an application example, we used this new method to analyze the gene expression data for NOD mouse model of Type 1 diabetes mellitus (T1DM). After the comprehensive comparison with the previously reported milestone molecules, we found by PMN: (1) the critical transition point was identified and confirmed by the tissue-specific modules or DNBs relevant to the pre-disease stage, which is considered as an earlier event during disease development and progression; (2) several key tissues-common modules related to the disease stage were significantly enriched on known T1DM associated genes with the rewired association networks, which are marks of later events during T1DM development and progression; (3) the tissue-specific modules associated with early development revealed several common essential progressive genes, and a few of pathways representing the effect of environmental factors during the early T1DM development. Totally, we developed a new method to detect the critical stage and the key modules during the disease occurrence and progression, and show that the pre-disease modules can serve as warning signals for the pre-disease state (e.g. T1DM early diagnosis) whereas the progressive modules can be used as the therapy targets for the disease state (e.g. advanced T1DM), which were also validated by experimental data.

Development of a Quantitative Methylation-Specific Polymerase Chain Reaction Method for Monitoring Beta Cell Death in Type 1 Diabetes

DNA methylation is a mechanism by which cells control gene expression, and cell-specific genes often exhibit unique patterns of DNA methylation. We previously reported that the mouse insulin-2 gene (Ins2) promoter has three potential methylation (CpG) sites, all of which are unmethylated in insulin-producing cells but methylated in other tissues. In this study we examined Ins2 exon 2 and found a similar tissue-specific methylation pattern. These methylation patterns can differentiate between DNA from insulin-producing beta cells and other tissues. We hypothesized that damaged beta cells release their DNA into circulation at the onset of type 1 diabetes mellitus (T1DM) and sought to develop a quantitative methylation-specific polymerase chain reaction (qMSP) assay for circulating beta cell DNA to monitor the loss of beta cells. Methylation-specific primers were designed to interrogate two or more CpG in the same assay. The cloned mouse Ins2 gene was methylated in vitro and used for development of the qMSP assay. We found the qMSP method to be sensitive and specific to differentiate between insulin-producing cells and other tissues with a detection limit of 10 copies in the presence of non-specific genomic DNA background. We also compared different methods for data analysis and found that the Relative Expression Ratio method is the most robust method since it incorporates both a reference value to normalize day-to-day variability as well as PCR reaction efficiencies to normalize between the methylation-specific and bisulfite-specific components of the calculations. The assay was applied in the streptozotocin-treated diabetic mouse model and detected a significant increase in circulating beta cell DNA before the rise in blood glucose level. These results demonstrate that this qMSP assay can be used for monitoring circulating DNA from insulin-producing cells, which will provide the basis for development of assays to detect beta cell destruction in early T1DM.

Dynamic alteration of adiponectin/adiponectin receptor expression and its impact on myocardial ischemia/reperfusion in type 1 diabetic mice

The present study determined the dynamic change of adiponectin (APN, a cardioprotective adipokine), its receptor expression, and their impact upon myocardial ischemia/reperfusion (MI/R) injury during type 1 diabetes mellitus (T1DM) progression, and involved underlying mechanisms. Diabetic state was induced in mice via multiple intraperitoneal injections of low-dose streptozotocin. The dynamic change of plasma APN concentration and cardiac APN receptor-1 and -2 (AdipoR1/2) expression were assessed immediately after diabetes onset (0 wk) and 1, 3, 5, and 7 wk thereafter. Indicators of MI/R injury (infarct size, apoptosis, and LDH release) were determined at 0, 1, and 7 wk of DM duration. The effect of APN on MI/R injury was determined in mice subjected to different diabetic durations. Plasma APN levels (total and HMW form) increased, whereas cardiac AdipoR1 expression decreased early after T1DM onset. With T1DM progression, APN levels were reduced and cardiac AdipoR1 expression increased. MI/R injury was exacerbated with T1DM progression in a time-dependent manner. Administration of globular APN (gAD) failed to attenuate MI/R injury in 1-wk T1DM mice, while an AMP-activated protein kinase (AMPK) activator (AICAR) reduced MI/R injury. However, administration of gAD (and AICAR) reduced infarct size and cardiomyocyte apoptosis in 7-wk T1DM mice. In conclusion, our results demonstrate a dynamic dysfunction of APN/AdipoR1 during T1DM progression. Reduced cardiac AdipoR1 expression and APN concentration may be responsible for increased I/R injury susceptibility at early and late T1DM stages, respectively. Interventions bolstering AdipoR1 expression during early T1DM stages and APN supplementation during advanced T1DM stages may potentially reduce the myocardial ischemic injury in diabetic patients.

HLA Class I Epitope Discovery in Type 1 Diabetes

Type 1 diabetes mellitus (T1DM) results from the destruction of beta cells by autoantigen-specific T cells. In the non-obese diabetic (NOD) mouse model, CD8+ T cells play an essential role in both the initial triggering of insulitis and its destructive phase, and proinsulin (PI) is one of the dominant target antigens (Ags). However, little is known about the beta cell epitopes presented by HLA class I molecules and recognized by human CD8+ T cells. We and other groups recently applied reverse immunology approaches to identify HLA class I-restricted PI epitopes. To establish an inventory of potential naturally processed epitopes, whole human PI or the transitional region between the B-chain and C-peptide were digested with purified proteasome complexes. By combining proteasome digestion data with epitope prediction algorithms, candidate epitopes restricted by HLA-A2.1 and other HLA class I molecules were identified. We validated immunogenicity and natural processing of the identified PI epitopes in HLA-A2.1-transgenic mice, while others demonstrated recognition of multiple PI epitopes by CD8+ T cells from T1DM and healthy subjects in the context of different HLA class I molecules. These results demonstrate the power of reverse immunology strategies for epitope discovery. DNA vaccination of HLA-transgenic mice may be another rapid and efficient reverse immunology approach to map additional epitopes derived from other T1DM Ags, such as IA-2 and glutamic acid decarboxylase 65 (GAD 65). Transfer of this information to Elispot- and MHC tetramer-based assay formats should allow to reliably detect and characterize autoreactive CD8+ T cell responses in T1DM, and may open new avenues for early T1DM diagnosis and immune intervention.

Double-stranded ribonucleic acid (RNA) induces beta-cell Fas messenger RNA expression and increases cytokine-induced beta-cell apoptosis.

Type 1 diabetes mellitus (T1DM) is an autoimmune disease caused by progressive destruction of insulin-producing pancreatic beta-cells. Both viral infections and the cytokines interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma) have been suggested as potential mediators of beta-cell death in early T1DM. We presently investigated whether the viral replicative intermediate double stranded RNA [here used as synthetic polyinosinic-polycytidylic acid (PIC)] modifies the effects of IL-1beta and IFN-gamma on gene expression and viability of rat pancreatic beta-cells. For this purpose, fluorescence-activated cell sorting-purified rat beta-cells were exposed for 6-16 h (study of gene expression by RT-PCR) or 6-9 days (study of viability by nuclear dyes) to PIC and/or IL-1beta and IFN-gamma. PIC increased the expression of Fas and Mn superoxide dismutase messenger RNAs by 5- to 10-fold. IL-1beta and a combination of PIC and IFN-gamma (but not PIC or IFN-gamma alone) induced expression of inducible nitric oxide (NO) synthase (iNOS) and consequent NO production. Induction of iNOS expression by PIC and IFN-gamma requires nuclear factor-kappaB activation, as suggested by transfection experiments with iNOS promoter-luciferase reporter constructs into primary beta-cells. Combinations of IL-1beta plus IFN-gamma, PIC plus IFN-gamma, or PIC plus IL-1beta induced a 2- to 3-fold increase in the number of apoptotic beta-cells. Blocking of iNOS activity significantly decreased PIC- plus IL-1beta-induced, but not PIC- plus IFN-gamma-induced, apoptosis. In conclusion, PIC alone or in combination with cytokines modifies the expression of several genes in pancreatic beta-cells. Two of these genes, Fas and iNOS, may contribute to beta-cell death. The transcription factor nuclear factor-kappaB is required for PIC-induced iNOS expression. PIC has an additive effect on cytokine-induced beta-cell death by both NO-dependent (in the case of IL-1beta) and NO-independent (in the case of IFN-gamma) mechanisms. These findings suggest that viral intermediates in synergism with local cytokine production may play an important role in beta-cell apoptosis in early T1DM.