Receptor for Advanced Glycation End Products (RAGE) in Type 1 Diabetes Pathogenesis

Association between the soluble receptor for advanced glycation end products and diabetes mellitus: systematic review and meta-analysis

BACKGROUND AND AIMS

In both type 1 diabetes (T1DM) and type 2 diabetes (T2DM), previous studies have yielded inconsistent findings regarding whether the levels of the soluble receptor for advanced glycation end products (sRAGE) are significantly altered. This meta-analysis aims to systematically evaluate the changes of sRAGE levels in patients with T1DM and T2DM.

METHODS

PubMed, Embase, and Web of Science were systematically searched from inception until April 2024. We included studies reporting sRAGE levels in individuals with T1DM or T2DM, using non-diabetic healthy individuals as the control group. A random-effects model was applied to conduct a meta-analysis of effect measures (means and SDs).

RESULTS

49 datasets from 32 studies, involving 4948 subjects, met the inclusion criteria. A random-effects model meta-analysis showed that sRAGE levels in T1DM subjects (SMD 0.45, CI: 0.16-0.73, P = 0.002) and T2DM subjects with complications (SMD 1.59, CI: 0.77-2.41, P = 0.0001) were significantly higher than those in the control groups. No statistically significant change in sRAGE levels was observed in T2DM subjects without complications (SMD 0.01, CI: -0.61-0.64, P = 0.97). A decrease in sRAGE levels was observed in subjects with newly diagnosed T2DM (SMD-0.40, CI: -0.71- -0.09, P = 0.01).

CONCLUSION

This meta-analysis indicated that sRAGE levels increased in T1DM patients and T2DM patients with complications, while they decreased in newly diagnosed T2DM patients. No significant difference was observed in T2DM patients without complications. Clearly, changes in sRAGE levels in patients with T1DM or T2DM are not uniform, but depend on the different types and stages of the disease.

PROSPERO REGISTRATION NUMBER

CRD42024521252.

Associations of insulin sensitivity and immune inflammatory responses with child blood lead (Pb) and PM2.5 exposure at an e-waste recycling area during the COVID-19 lockdown

Fine particular matter (PM2.5) and lead (Pb) exposure can induce insulin resistance, elevating the likelihood of diabetes onset. Nonetheless, the underlying mechanism remains ambiguous. Consequently, we assessed the association of PM2.5 and Pb exposure with insulin resistance and inflammation biomarkers in children. A total of 235 children aged 3-7 years in a kindergarten in e-waste recycling areas were enrolled before and during the Corona Virus Disease 2019 (COVID-19) lockdown. Daily PM2.5 data was collected and used to calculate the individual PM2.5 daily exposure dose (DED-PM2.5). Concentrations of whole blood Pb, fasting blood glucose, serum insulin, and high mobility group box 1 (HMGB1) in serum were measured. Compared with that before COVID-19, the COVID-19 lockdown group had lower DED-PM2.5 and blood Pb, higher serum HMGB1, and lower blood glucose and homeostasis model assessment of insulin resistance (HOMA-IR) index. Decreased DED-PM2.5 and blood Pb levels were linked to decreased levels of fasting blood glucose and increased serum HMGB1 in all children. Increased serum HMGB1 levels were linked to reduced levels of blood glucose and HOMA-IR. Due to the implementation of COVID-19 prevention and control measures, e-waste dismantling activities and exposure levels of PM2.5 and Pb declined, which probably reduced the association of PM2.5 and Pb on insulin sensitivity and diabetes risk, but a high level of risk of chronic low-grade inflammation remained. Our findings add new evidence for the associations among PM2.5 and Pb exposure, systemic inflammation and insulin resistance, which could be a possible explanation for diabetes related to environmental exposure.

Trichosanthin alleviates streptozotocin-induced type 1 diabetes mellitus in mice by regulating the balance between bone marrow-derived IL6+ and IL10+ MDSCs

Myeloid-derived suppressor cells (MDSCs) occupy a pivotal role in the intricate pathogenesis of the autoimmune disorder, Type 1 diabetes mellitus (T1DM). Since our previous work demonstrated that trichosanthin (TCS), an active compound of Chinese herb medicine Tian Hua Fen, regulated immune response, we aimed to clarify the efficacy and molecular mechanism of TCS in the treatment of T1DM. To this end, T1DM mouse model was established by streptozotocin (STZ) induction. The mice were randomly divided into normal control group (Ctl), T1DM group (STZ), TCS treated diabetic group (STZ + TCS) and insulin-treated diabetic group (STZ + insulin). Our comprehensive evaluation encompassed variables such as blood glucose, glycosylated hemoglobin, body weight, pertinent biochemical markers, pancreatic histopathology, and the distribution of immune cell populations. Furthermore, we meticulously isolated MDSCs from the bone marrow of T1DM mice, probing into the expressions of genes pertaining to the advanced glycation end product receptor (RAGE)/NF-κB signaling pathway through RT-qPCR. Evidently, TCS exhibited a substantial capacity to effectively counteract the T1DM-induced elevation in random blood glucose, glycosylated hemoglobin, and IL-6 levels in plasma. Pathological scrutiny underscored the ability of TCS to mitigate the damage incurred by islets. Intriguingly, TCS interventions engendered a reduction in the proportion of MDSCs within the bone marrow, particularly within the IL-6+ MDSC subset. In contrast, IL-10+ MDSCs exhibited an elevation following TCS treatment. Moreover, we observed a significant down-regulation of relative mRNA of pro-inflammatory genes, including arginase 1 (Arg1), inducible nitric oxide synthase (iNOS), RAGE and NF-κB, within MDSCs due to the influence of TCS. It decreases total MDSCs and regulates the balance between IL-6+ and IL-10+ MDSCs thus alleviating the symptoms of T1DM. TCS also down-regulates the RAGE/NF-κB signaling pathway, making it a promising alternative therapeutic treatment for T1DM. Collectively, our study offered novel insights into the underlying mechanism by which TCS serves as a promising therapeutic intervention for T1DM.

Potential of rosmarinic acid from Orthosiphon aristatus extract for inflammatory induced diseases and its mechanisms of action

Orthosiphon aristatus has been traditionally used as a medicinal herb for various illnesses in Southeast Asia and Europe. The most dominant bioactive compound of the herb is rosmarinic acid (RosA) which has been demonstrated for its remarkable anti-inflammatory properties. This review describes the recent progress of studies on multi-target molecular pathways of RosA in relation to targeted inflammatory-associated diseases. An inclusive literature search was conducted using electronic databases such as Google Scholar, Scopus, Springer Link, PubMed, Medline, Wiley and Science Direct for studies reporting on the anti-inflammatory actions of RosA from 2008 until 2023. The keywords of the search were RosA and anti-inflammatory in relation to hepatoprotective, chondroprotective, cardioprotective, neuroprotective and toxicity. Only publications that are written in English are included in this review. The inhibition and deactivation of pro-inflammatory biomolecules by RosA were explained based on the initial inflammation stimuli and their location in the body. The activation of Nrf2/HO-1 expression to inhibit NF-κB pathway is the key mechanism for hepatoprotection. Besides NF-κB inhibition, RosA activates PPARγ to alleviate ischemia/reperfusion (I/R)-induced myocardial injury for cardioprotection. The regulation of MAPK and T-cell activation is important for chondroprotection, whereas the anti-oxidant property of RosA is the main contributor of neuroprotection. Even though less studies on the anti-inflammation of RosA extracts from O. aristatus, but the effective pharmacological properties of RosA has promoted it as a natural potent lead for further investigation.

Alpha cell receptor for advanced glycation end products associate with glucagon expression in type 1 diabetes

Hypoglycemia in type 1 diabetes associates with changes in the pancreatic islet α cells, where the receptor for advanced glycation end products (RAGE) is highly expressed. This study compared islet RAGE expression in donors without diabetes, those at risk of, and those with type 1 diabetes. Laser-dissected islets were subject to RNA bioinformatics and adjacent pancreatic tissue were assessed by confocal microscopy. We found that islets from type 1 diabetes donors had differential expression of the RAGE gene (AGER) and its correlated genes, based on glucagon expression. Random forest machine learning revealed that AGER was the most important predictor for islet glucagon levels. Conversely, a generalized linear model identified that glucagon expression could be predicted by expression of RAGE signaling molecules, its ligands and enzymes that create or clear RAGE ligands. Confocal imaging co-localized RAGE, its ligands and signaling molecules to the α cells. Half of the type 1 diabetes cohort comprised of adolescents and a patient with history of hypoglycemia-all showed an inverse relationship between glucagon and RAGE. These data confirm an association between glucagon and islet RAGE, its ligands and signaling pathways in type 1 diabetes, which warrants functional investigation into a role for RAGE in hypoglycemia.

The Ephrin tyrosine kinase a3 (EphA3) is a novel mediator of RAGE-prompted motility of breast cancer cells

BACKGROUND

The receptor for advanced glycation-end products (RAGE) and its ligands have been implicated in obesity and associated inflammatory processes as well as in metabolic alterations like diabetes. In addition, RAGE-mediated signaling has been reported to contribute to the metastatic progression of breast cancer (BC), although mechanistic insights are still required. Here, we provide novel findings regarding the transcriptomic landscape and the molecular events through which RAGE may prompt aggressive features in estrogen receptor (ER)-positive BC.

METHODS

MCF7 and T47D BC cells stably overexpressing human RAGE were used as a model system to evaluate important changes like cell protrusions, migration, invasion and colony formation both in vitro through scanning electron microscopy, clonogenic, migration and invasion assays and in vivo through zebrafish xenografts experiments. The whole transcriptome of RAGE-overexpressing BC cells was screened by high-throughput RNA sequencing. Thereafter, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses allowed the prediction of potential functions of differentially expressed genes (DEGs). Flow cytometry, real time-PCR, chromatin immunoprecipitation, immunofluorescence and western blot assays were performed to investigate the molecular network involved in the regulation of a novel RAGE target gene namely EphA3. The clinical significance of EphA3 was explored in the TCGA cohort of patients through the survivALL package, whereas the pro-migratory role of EphA3 signaling was ascertained in both BC cells and cancer-associated fibroblasts (CAFs). Statistical analysis was performed by t-tests.

RESULTS

RNA-seq findings and GSEA analysis revealed that RAGE overexpression leads to a motility-related gene signature in ER-positive BC cells. Accordingly, we found that RAGE-overexpressing BC cells exhibit long filopodia-like membrane protrusions as well as an enhanced dissemination potential, as determined by the diverse experimental assays. Mechanistically, we established for the first time that EphA3 signaling may act as a physical mediator of BC cells and CAFs motility through both homotypic and heterotypic interactions.

CONCLUSIONS

Our data demonstrate that RAGE up-regulation leads to migratory ability in ER-positive BC cells. Noteworthy, our findings suggest that EphA3 may be considered as a novel RAGE target gene facilitating BC invasion and scattering from the primary tumor mass. Overall, the current results may provide useful insights for more comprehensive therapeutic approaches in BC, particularly in obese and diabetic patients that are characterized by high RAGE levels.

The Role of Advanced Glycation End Products on Dyslipidemia

Disorders of lipoprotein metabolism and glucose homeostasis are common consequences of insulin resistance and usually co-segregate in patients with metabolic syndrome and type 2 diabetes mellitus (DM). Insulin-resistant subjects are characterized by atherogenic dyslipidemia, a specific lipid pattern which includes hypertriglyceridemia, reduced high-density lipoprotein cholesterol level, and increased proportion of small, dense low-density lipoprotein (LDL). Chronic hyperglycemia favors the processes of non-enzymatic glycation, leading to the increased production of advanced glycation end products (AGEs). Apart from direct harmful effects, AGEs are also potent inducers of oxidative stress and inflammation. In addition, increased AGEs' production may induce further qualitative modifications of small, dense LDL particles, converting them to glycated LDLs. These particles are even more atherogenic and may confer an increased cardiovascular risk. In this narrative review, we summarize the available evidence of the pathophysiological role and clinical importance of circulating AGEs and glycated LDLs in patients with dyslipidemia, particularly those with DM and related complications. In addition, we discuss recent advances and the issues that should be improved regarding laboratory assessment of AGEs and glycated LDLs, as well as the possibilities for their therapeutic modulation.

Soluble RAGE Prevents Type 1 Diabetes Expanding Functional Regulatory T Cells

Type 1 diabetes is an autoimmune disease with no cure, where clinical translation of promising therapeutics has been hampered by the reproducibility crisis. Here, short-term administration of an antagonist to the receptor for advanced glycation end products (sRAGE) protected against murine diabetes at two independent research centers. Treatment with sRAGE increased regulatory T cells (Tregs) within the islets, pancreatic lymph nodes, and spleen, increasing islet insulin expression and function. Diabetes protection was abrogated by Treg depletion and shown to be dependent on antagonizing RAGE with use of knockout mice. Human Tregs treated with a RAGE ligand downregulated genes for suppression, migration, and Treg homeostasis (FOXP3, IL7R, TIGIT, JAK1, STAT3, STAT5b, CCR4). Loss of suppressive function was reversed by sRAGE, where Tregs increased proliferation and suppressed conventional T-cell division, confirming that sRAGE expands functional human Tregs. These results highlight sRAGE as an attractive treatment to prevent diabetes, showing efficacy and reproducibility at multiple research centers and in human T cells.

Advanced Glycation End-Products (AGEs) of Lysine and Effects of Anti-TCR/Anti-TNF-α Antibody-Based Therapy in the LEW.1AR1-iddm Rat, an Animal Model of Human Type 1 Diabetes

The LEW.1AR1-iddm rat is an animal model of human type 1 diabetes (T1D). Previously, we have shown that combination with anti-TCR/anti-TNF-α antibody-based therapy re-established normoglycemia and increased proteinic arginine-dimethylation in the spleen, yet not in the pancreas. High blood glucose is often associated with elevated formation of advanced glycation end-products (AGEs) which act via their receptor (RAGE). Both anti-TCR and anti-TNF-α are inhibitors of RAGE. The aim of the present work was to investigate potential biochemical changes of anti-TCR/anti-TNF-α therapy in the LEW.1AR1-iddm rat. We determined by stable-isotope dilution gas chromatography-mass spectrometry (GC-MS) the content of free and proteinic AGEs and the N^ε-monomethylation of lysine (Lys) residues in proteins of pancreas, kidney, liver, spleen and lymph nodes of normoglycemic control (ngCo, n = 6), acute diabetic (acT1D, n = 6), chronic diabetic (chT1D, n = 4), and cured (cuT1D, n = 4) rats after anti-TCR/anti-TNF-α therapy. Analyzed biomarkers included Lys and its metabolites N^ε-carboxymethyl lysine (CML), furosine and N^ε-monomethyl lysine (MML). Other amino acids were also determined. Statistical methods including ANOVA, principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to evaluate the effects. Most statistical differences between the study groups were observed for spleen, pancreas and kidney, with liver and lymph nodes showing no such differences. In the pancreas, the groups differed with respect to proteinic furosine (p = 0.0289) and free CML (p = 0.0023). In the kidneys, the groups differed with respect to proteinic furosine (p = 0.0076) and CML (p = 0.0270). In the spleen, group differences were found for proteinic furosine (p = 0.0114) and free furosine (p = 0.0368), as well as for proteinic CML (p = 0.0502) and proteinic MML (p = 0.0191). The acT1D rats had lower furosine, CML and MML levels in the spleen than the rats in all other groups. This observation corresponds to the lower citrullination levels previously measured in these rats. PCA revealed diametric associations between PC1 and PC2 for spleen (r = −0.8271, p < 0.0001) compared to pancreas (r = 0.5805, p = 0.0073) and kidney (r = 0.8692, p < 0.0001). These findings underscore the importance of the spleen in this animal model of human T1D. OPLS-DA showed that in total sixteen amino acids differed in the experimental groups.

Diet and Obesity-Induced Methylglyoxal Production and Links to Metabolic Disease

The obesity rate in the United States is 42.4% and has become a national epidemic. Obesity is a complex condition that is influenced by socioeconomic status, ethnicity, genetics, age, and diet. Increased consumption of a Western diet, one that is high in processed foods, red meat, and sugar content, is associated with elevated obesity rates. Factors that increase obesity risk, such as socioeconomic status, also increase consumption of a Western diet because of a limited access to healthier options and greater affordability of processed foods. Obesity is a public health threat because it increases the risk of several pathologies, including atherosclerosis, diabetes, and cancer. The molecular mechanisms linking obesity to disease onset and progression are not well understood, but a proposed mechanism is physiological changes caused by altered lipid peroxidation, glycolysis, and protein metabolism. These metabolic pathways give rise to reactive molecules such as the abundant electrophile methylglyoxal (MG), which covalently modifies nucleic acids and proteins. MG-adducts are associated with obesity-linked pathologies and may have potential for biomonitoring to determine the risk of disease onset and progression. MG-adducts may also play a role in disease progression because they are mutagenic and directly impact protein stability and function. In this review, we discuss how obesity drives metabolic alterations, how these alterations lead to MG production, the association of MG-adducts with disease, and the potential impact of MG-adducts on cellular function.

Cognitive Deficits in Type-1 Diabetes: Aspects of Glucose, Cerebrovascular and Amyloid Involvement

The evidence shows that individuals with type-1 diabetes mellitus (T1DM) are at greater risk of accelerated cognitive impairment and dementia. Although, to date the mechanisms are largely unknown. An emerging body of literature indicates that dysfunction of cerebral neurovascular network and plasma dyshomeostasis of soluble amyloid-β in association with impaired lipid metabolism are central to the onset and progression of cognitive deficits and dementia. However, the latter has not been extensively considered in T1DM. Therefore, in this review, we summarised the literature concerning altered lipid metabolism and cerebrovascular function in T1DM as an implication for potential pathways leading to cognitive decline and dementia.

Transport of oxytocin to the brain after peripheral administration by membrane-bound or soluble forms of receptors for advanced glycation end-products

Oxytocin (OT) is a neuropeptide hormone. Single and repetitive administration of OT increases social interaction and maternal behaviour in humans and mammals. Recently, it was found that the receptor for advanced glycation end-products (RAGE) is an OT-binding protein and plays a critical role in the uptake of OT to the brain after peripheral OT administration. Here, we address some unanswered questions on RAGE-dependent OT transport. First, we found that, after intranasal OT administration, the OT concentration increased in the extracellular space of the medial prefrontal cortex (mPFC) of wild-type male mice, as measured by push-pull microperfusion. No increase of OT in the mPFC was observed in RAGE knockout male mice. Second, in a reconstituted in vitro blood-brain barrier system, inclusion of the soluble form of RAGE (endogenous secretory RAGE [esRAGE]), an alternative splicing variant, in the luminal (blood) side had no effect on the transport of OT to the abluminal (brain) chamber. Third, OT concentrations in the cerebrospinal fluid after i.p. OT injection were slightly higher in male mice overexpressing esRAGE (esRAGE transgenic) compared to those in wild-type male mice, although this did not reach statistical significance. Although more extensive confirmation is necessary because of the small number of experiments in the present study, the reported data support the hypothesis that RAGE may be involved in the transport of OT to the mPFC from the circulation. These results suggest that the soluble form of RAGE in the plasma does not function as a decoy in vitro.

Association of RAGE with acute ischemic stroke prognosis in type 2 diabetes

BACKGROUND

In experimental models, the receptor for advanced glycation end products (RAGE) has been reported as a key mediator in cerebral ischemia. In this study, the clinical significance of serum RAGE levels in acute ischemic stroke patients with type 2 diabetes was determined.

METHOD

Three hundred seven patients (165 patients without diabetes and 142 patients with diabetes) with acute cerebral infarction (ACI) were enrolled over 3 consecutive months. On admission, their National Institute of Health Stroke Scale (NIHSS) scores were recorded. The clinical laboratory data of all subjects were collected, and their serum levels of RAGE were assayed using enzyme-linked immunosorbent assay (ELISA). On admission and 3 months after stroke, the clinical outcomes were assessed using the Barthel index (BI) and modified Rankin scale (mRS).

RESULTS

Patients with diabetes (PwD) had significantly higher levels of triglycerides (TGs), RAGE, fasting blood glucose (FBG), glycosylated hemoglobin A1c (HbA1c), and worse stroke prognosis than patients without diabetes (p < 0.05). Hypertension history, RAGE, and FBG in patients without diabetes in ischemic stroke were increased, relative to stroke prognosis. Weight, RAGE, and FBG data showed significant correlation with stroke outcome in PwD (p < 0.05). Multiple logistic regression analysis indicated that the RAGE level was an independent risk factor for poor prognosis of stroke, especially in PwD with ACI (p < 0.05).

CONCLUSION

Acute ischemic stroke is associated with elevated serum RAGE level, which, at admission, is an independent predictor of poor outcome for stroke in type 2 diabetes.

Diabetes affects endothelial cell function and alters fibrin clot formation in a microvascular flow model: A pilot study

Diabetes is a proinflammatory and prothrombotic condition that increases the risk of vascular complications. The aim of this study was to develop a diabetic microvascular flow model that allows to study the complex interactions between endothelial cells, blood cells and plasma proteins and their effects on clot formation. Primary human cardiac microvascular endothelial cells from donors without diabetes or donors with diabetes (type 1 or type 2) were grown in a microfluidic chip, perfused with non-diabetic or diabetic whole blood, and clot formation was assessed by measuring fibrin deposition in real time by confocal microscopy. Clot formation in non-diabetic whole blood was significantly increased in the presence of endothelial cells from donors with type 2 diabetes compared with cells from donors without diabetes. There was no significant difference in clot formation between non-diabetic and diabetic whole blood. We present for the first time a diabetic microvascular flow model as a new tool to study clot formation as a result of the complex interactions between endothelial cells, blood cells and plasma proteins in a diabetes setting. We show that endothelial cells affect clot formation in whole blood, attributing an important role to the endothelium in the development of atherothrombotic complications.

Role of Blood-Brain Barrier in Alzheimer's Disease

The blood-brain barrier (BBB) is involved in the pathogenesis of Alzheimer's disease (AD). BBB is a highly selective semipermeable structural and chemical barrier which ensures a stable internal environment of the brain and prevents foreign objects invading the brain tissue. BBB dysfunction induces the failure of Aβ transport from brain to the peripheral circulation across the BBB. Especially, decreased levels of LRP-1 (low density lipoprotein receptor-related protein 1) and increased levels of RAGE (receptor for advanced glycation endproducts) at the BBB can cause the failure of Aβ transport. The pathogenesis of AD is related to the BBB structural components, including pericytes, astrocytes, vascular endothelial cells, and tight junctions. BBB dysfunction will trigger neuroinflammation and oxidative stress, then enhance the activity of β-secretase and γ-secretase, and finally promote Aβ generation. A progressive accumulation of Aβ in brain and BBB dysfunction may become a feedback loop that gives rise to cognitive impairment and the onset of dementia. The correlation between BBB dysfunction and tau pathology has been well-reported. Therefore, regulating BBB function may be a new therapeutic target for treating AD.

C. elegans-An Emerging Model to Study Metal-Induced RAGE-Related Pathologies

The receptor for advanced glycation end products (RAGE), a multi-ligand receptor, is mostly associated with promoting inflammation and oxidative stress. In addition to advanced glycation end products (AGEs), its ligands include High mobility group box 1 protein (HMGB-1), S-100 proteins and beta-sheet fibrils. The effects of several metals and metalloids on RAGE expression and activation have been recently studied: in vivo and in vitro exposure to methylmercury, selenium, zinc, manganese, and arsenic was associated with a variety of RAGE-related alterations and behavioral impairments, which are mostly dependent upon the administration procedure (local vs. systemic) and age during exposure. Recently, C. elegans has been proposed as a potential novel model for studying RAGE-related pathologies; preliminary data regarding such model and its potential contribution to the study of metal-induced RAGE-related pathologies are discussed.

Perinatal exposure to high dietary advanced glycation end products in transgenic NOD8.3 mice leads to pancreatic beta cell dysfunction

The contribution of environmental factors to pancreatic islet damage in type 1 diabetes remains poorly understood. In this study, we crossed mice susceptible to type 1 diabetes, where parental male (CD8+ T cells specific for IGRP206-214; NOD8.3) and female (NOD/ShiLt) mice were randomized to a diet either low or high in AGE content and maintained on this diet throughout pregnancy and lactation. After weaning, NOD8.3+ female offspring were identified and maintained on the same parental feeding regimen for until day 28 of life. A low AGE diet, from conception to early postnatal life, decreased circulating AGE concentrations in the female offspring when compared to a high AGE diet. Insulin, proinsulin and glucagon secretion were greater in islets isolated from offspring in the low AGE diet group, which was akin to age matched non-diabetic C57BL/6 mice. Pancreatic islet expression of Ins2 gene was also higher in offspring from the low AGE diet group. Islet expression of glucagon, AGEs and the AGE receptor RAGE, were each reduced in low AGE fed offspring. Islet immune cell infiltration was also decreased in offspring exposed to a low AGE diet. Within pancreatic lymph nodes and spleen, the proportions of CD4+ and CD8+ T cells did not differ between groups. There were no significant changes in body weight, fasting glucose or glycemic hormones. This study demonstrates that reducing exposure to dietary AGEs throughout gestation, lactation and early postnatal life may benefit pancreatic islet secretion and immune infiltration in the type 1 diabetic susceptible mouse strain, NOD8.3.

The anti-inflammatory and anti-glycative effects of rosmarinic acid in the livers of type 1 diabetic mice

Background: Rosmarinic acid (RA) is a polyphenol present in members of the Lamiaceae family. In this study, yhe anti-inflammatory and anti-glycative effects of RA in the livers of type 1 diabetic mice were examined.

Methods: The diabetic mice were divided into three groups: diabetic mice with 0, low dose RA (25 mg/ml), and high dose RA (50 mg/ml). One group of non-diabetic mice was used as a control for comparison. RA was supplied via daily 200 μL oral injections for 9 weeks. The level of interleukin (IL)-6, the tumor necrosis factor (TNF)-alpha, the prostaglandin E₂ (PGE₂), and the activity of cyclooxygenase (COX)-2 in the livers were measured. The hepatic receptor of advanced glycative endproduct (RAGE), the sorbitol levels, and the glyoxalase 1 (GLO-1) activity were also determined.

Results: Compared with diabetic group that received no RA, the groups with RA supplements at both levels of dosages had increased body weight and had both decreased water intake and feed intake (p < 0.05). RA intake was found to reduce plasma glucose level and elevate plasma insulin level when compared with the diabetic group that received no RA (p < 0.05). RA treatments lowered the hepatic level of IL-6, TNF-alpha, and PGE₂, as well as the activity of COX-2 (p < 0.05). RA administration also decreased hepatic RAGE and sorbitol levels, and GLO-1 activity when compared with the diabetic group that received no RA (P < 0.05).

Conclusion: These findings support the conclusion that rosmarinic acid (RA) could be a potent protective agent for the liver against diabetic injury.

Arterial Calcification in Diabetes Mellitus: Preclinical Models and Translational Implications

Diabetes mellitus increasingly afflicts our aging and dysmetabolic population. Type 2 diabetes mellitus and the antecedent metabolic syndrome represent the vast majority of the disease burden-increasingly prevalent in children and older adults. However, type 1 diabetes mellitus is also advancing in preadolescent children. As such, a crushing wave of cardiometabolic disease burden now faces our society. Arteriosclerotic calcification is increased in metabolic syndrome, type 2 diabetes mellitus, and type 1 diabetes mellitus-impairing conduit vessel compliance and function, thereby increasing the risk for dementia, stroke, heart attack, limb ischemia, renal insufficiency, and lower extremity amputation. Preclinical models of these dysmetabolic settings have provided insights into the pathobiology of arterial calcification. Osteochondrogenic morphogens in the BMP-Wnt signaling relay and transcriptional regulatory programs driven by Msx and Runx gene families are entrained to innate immune responses-responses activated by the dysmetabolic state-to direct arterial matrix deposition and mineralization. Recent studies implicate the endothelial-mesenchymal transition in contributing to the phenotypic drift of mineralizing vascular progenitors. In this brief overview, we discuss preclinical disease models that provide mechanistic insights-and point to challenges and opportunities to translate these insights into new therapeutic strategies for our patients afflicted with diabetes mellitus and its arteriosclerotic complications.