Β-cell Insulin Research Articles

Apolipoprotein A-I priming via SR-BI and ABCA1 receptor binding upregulates mitochondrial metabolism to promote insulin secretion in INS-1E cells.

Apolipoprotein A-I (ApoA-I), the primary component of high-density lipoprotein (HDL) cholesterol primes β-cells to increase insulin secretion, however, the mechanisms involved are not fully defined. Here, we aimed to confirm ApoA-I receptors in β-cells and delineate ApoA-I-receptor pathways in β-cell insulin output. An LRC-TriCEPS experiment was performed using the INS-1E rat β-cell model and ApoA-I for unbiased identification of ApoA-I receptors. Identified targets, alongside ATP binding cassette transporter A1 (ABCA1) (included control) were silenced in the same cells, and insulin secretion (ELISA) and mitochondrial metabolism (seahorse) were assessed with/without ApoA-I priming. Human β-cell expression data was used to investigate ApoA-I receptor pathways in type 2 diabetes (T2D). Scavenger receptor B1 (SR-BI) and regulator of microtubule dynamics 1 were identified as ApoA-I targets. SR-BI or ABCA1 silencing abolished ApoA-I induced increases in insulin secretion. ApoA-I priming increased mitochondrial OXPHOS, however this was greatly attenuated with SR-BI or ABCA1 silencing. Supporting this, human β-cell expression data investigations found SR-BI and ABCA1 to be correlated with genes associated with mitochondrial pathways. In all, SR-BI and ABCA1 correlated with 73 and 3 genes differentially expressed in T2D, respectively. We confirm that SR-BI and ABCA1 are the primary β-cell ApoA-I receptors and demonstrate that ApoA-I priming enhances β-cell insulin secretion via the upregulation of mitochondrial metabolism through ApoA-I-SR-BI and ApoA-I-ABCA1 pathways. We propose that SR-BI relies on mitochondrial and exocytotic pathways, while ABCA1 depends solely on mitochondrial pathways. Our findings uncover new targets in ApoA-I β-cell mechanism for T2D therapies.

Associations of physiologic subtypes based on HOMA2 indices of β-cell function and insulin sensitivity with the risk of kidney function decline, cardiovascular disease, and all-cause mortality from the 4C study

BackgroundPrevious studies have been limited by their inability to differentiate between the effects of insulin sensitivity and β-cell function on the risk of kidney function decline, cardiovascular disease (CVD), and all-cause mortality. To address this knowledge gap, we aimed to investigate whether the physiological subtypes based on homeostasis model assessment-2 (HOMA2) indices of β-cell function (HOMA2-B) and insulin sensitivity (HOMA2-S) could be used to identify individuals with subsequently high or low of clinical outcome risk.MethodsThis retrospective cohort study included 7,317 participants with a follow-up of up to 5 years. Based on HOMA2 indices, participants were categorized into four physiologic subtypes: the normal phenotype (high insulin sensitivity and high β-cell function), the insulinopenic phenotype (high insulin sensitivity and low β-cell function), the hyperinsulinaemic phenotype (low insulin sensitivity and high β-cell function), and the classical phenotype (low insulin sensitivity and low β-cell function). The outcomes included kidney function decline, CVD events (fatal and nonfatal), and all-cause mortality. Cox regression models were used to calculate hazard ratios (HRs) for outcomes, and spline models were used to examine the dose-dependent associations of HOMA2-B and HOMA2-S with outcomes.ResultsA total of 1,488 (20.3%) were classified as normal, 2,179 (29.8%) as insulinopenic, 2,173 (29.7%) as hyperinsulinemic, and 1,477 (20.2%) as classical subtypes. Compared with other physiological subtypes, the classical subtype presented the highest risk of kidney function decline (classical vs. normal HR 11.50, 95% CI 4.31–30.67). The hyperinsulinemic subtype had the highest risk of CVD and all-cause mortality (hyperinsulinemic vs. normal: fatal CVD, HR 6.56, 95% CI 3.09–13.92; all-cause mortality, HR 4.56, 95% CI 2.97–7.00). Spline analyses indicated the dose-dependent associations of HOMA2-B and HOMA2-S with outcomes.ConclusionsThe classical subtype had the strongest correlation with the risk of kidney function decline, and the hyperinsulinemic subtype had the highest risk of CVD and all-cause mortality, which should be considered for interventions with precision medicine.Graphical abstract

Visceral Adipocyte-Derived Extracellular Vesicle miR-27a-5p Elicits Glucose Intolerance by Inhibiting Pancreatic β-Cell Insulin Secretion.

Pancreatic β-cell dysfunction caused by obesity can be associated with alterations in the levels of microRNAs (miRNAs). However, the role of miRNAs in such processes remains elusive. Here, we show that pancreatic islet miR-27a-5p, which is markedly increased in obese mice and impairs insulin secretion, is mainly delivered by visceral adipocyte-derived extracellular vesicles (EVs). Depleting miR-27a-5p significantly improves insulin secretion and glucose intolerance in db/db mice. Supporting the function of EVs' miR-27a-5p as a key pathogenic factor, intravenous injection of miR-27a-5p-containing EVs shows their distribution in mouse pancreatic islets. Tracing the injected AAV-miR-27a-5p (AAV-miR-27a) or AAV-FABP4-miR-27a-5p (AAV-FABP4-miR-27a) in visceral fat results in upregulating miR-27a-5p in EVs and serum, and elicits mouse pancreatic β-cell dysfunction. Mechanistically, miR-27a-5p directly targets L-type Ca2+ channel subtype CaV1.2 (Cacna1c) and reduces insulin secretion in β-cells. Overexpressing mouse CaV1.2 largely abolishes the insulin secretion injury induced by miR-27a-5p. These findings reveal a causative role of EVs' miR-27a-5p in visceral adipocyte-mediated pancreatic β-cell dysfunction in obesity-associated type 2 diabetes mellitus.

Identification of new phenotypes in type 2 diabetes with acute myocardial infarction: toward a precision medicine?

Abstract Background Type 2 diabetes mellitus (T2DM) is a highly heterogeneous entity, with multiple subgroups differing by clinic presentation, disease progression and risk of complications such as myocardial infarction (MI). A new T2DM phenotyping classification has been recently proposed to help to improve treatment tailoring and target early treatments, and we aimed to identify the prevalence and characteristics of the new phenotypes. Methods All consecutive adults with a history T2DM hospitalized in a french Coronary Intensive Care Unit for an acute MI between February 1st, 2021 and January 31st, 2023 were included. Clusters were based on six variables (glutamate decarboxylase antibodies, age at diagnosis, BMI, HbA1c, and homoeostatic model assessment 2 estimates of β-cell function and insulin resistance). We stratified patients into five subgroups : 1/ SAID=severe autoimmune diabetes; 2/ SIDD=severe insulin-deficient diabetes; 3/ SIRD=severe insulin-resistant diabetes; 4/ MOD=mild obesity-related diabetes; and 5/ MARD=mild age-related diabetes. Results Among the 266 patients included, characteristics according to diabetes phenotypes are summarized in the Table. Conclusions Our prospective study showed that in real-world T2DM patients with acute MI, unclassical phenotypes, i.e. hyperinsulinaemic and insulinopaenic were common. Given the large discrepancies in characteristics, our findings suggest the relevance of the new substratification. However, its clinical utlity and translation in tailored treatment strategies and prognosis remains to be determined.Table.

Chronic late gestation fetal hyperglucagonaemia results in lower insulin secretion, pancreatic mass, islet area and beta- and α-cell proliferation.

Fetal glucagon concentrations are elevated in the presence of a compromised intrauterine environment, as in cases of placental insufficiency and perinatal acidaemia. Our objective was to investigate the impact of late gestation fetal hyperglucagonaemia on in vivo insulin secretion and pancreatic islet structure. Chronically catheterized late gestation fetal sheep received an intravenous infusion of glucagon at low (5ng/kg/min; GCG-5) or high (50ng/kg/min; GCG-50) concentrations or a vehicle control (CON) for 8-10days.Glucose-stimulated fetal insulin secretion (GSIS) was measured following 3h (acute response) and 8-10days (chronic response) of experimental infusions. Insulin, glucose and amino acid concentrations were measured longitudinally. The pancreas was collected at the study end for histology and gene expression analysis. Acute exposure (3h) to GCG-50 induced a 3-fold increase in basal insulin concentrations with greater GSIS. Meanwhile, chronic exposure to both GCG-5 and GCG-50 decreased basal insulin concentrations 2-fold by day 8-10. Chronic GCG-50 also blunted GSIS at the study end. Fetal amino acid concentrations were decreased within 24h of GCG-5 and GCG-50, while there were no differences in fetal glucose. Histologically, GCG-5 and GCG-50 had lower β- and α-cell proliferation, as well as lower α-cell mass and pancreas weight, while GCG-50 had lower islet area. This study demonstrates that chronic glucagon elevation in late gestation fetuses impairs β-cell proliferation and insulin secretion, which has the potential to contribute to later-life diabetes risk. We speculate that the action of glucagon in lower circulating fetal amino acid concentrations may have a suppressive effect on insulin secretion. KEY POINTS: We have previously demonstrated in a chronically catheterized fetal sheep model that experimentally elevated glucagon in the fetus impairs placental function, reduces fetal protein accretion and lowers fetal weight. In the present study, we further characterized the effects of elevated fetal glucagon on fetal physiology with a focus on pancreatic development and β-cell function. We show that experimentally elevated fetal glucagon results in lower β- and α-cell proliferation, as well as decreased insulin secretion after 8-10days of glucagon infusion. These results have important implications for β-cell reserve and later-life predisposition to diabetes.

Transcriptional coactivator MED15 is required for beta cell maturation

Mediator, a co-regulator complex required for RNA Polymerase II activity, interacts with tissue-specific transcription factors to regulate development and maintain homeostasis. We observe reduced Mediator subunit MED15 expression in endocrine hormone-producing pancreatic islets isolated from people living with type 2 diabetes and sought to understand how MED15 and Mediator control gene expression programs important for the function of insulin-producing β-cells. Here we show that Med15 is expressed during mouse β-cell development and maturation. Knockout of Med15 in mouse β-cells causes defects in β-cell maturation without affecting β-cell mass or insulin expression. ChIP-seq and co-immunoprecipitation analyses found that Med15 binds β-cell transcription factors Nkx6-1 and NeuroD1 to regulate key β-cell maturation genes. In support of a conserved role during human development, human embryonic stem cell-derived β-like cells, genetically engineered to express high levels of MED15, express increased levels of maturation markers. We provide evidence of a conserved role for Mediator in β-cell maturation and demonstrate an additional layer of control that tunes β-cell transcription factor function.

9250 carRNA m6A methylation regulates transcription state and chromatin accessibility in human islets in normal physiology and type 2 diabetes

Abstract Disclosure: N. Shukla: None. C. Ju: None. H. Li: None. C. He: None. R. Kulkarni: Advisory Board Member; Self; Novo Nordisk, Biomea Fusion Inc, REDD Pharma. Grant Recipient; Self; Inversago. Chromatin-associated regulatory RNAs (carRNA), which include promoter- and enhancer-associated RNAs as well as several non-coding repeat elements have been established in the literature as important regulators of global gene transcription. However, the regulation of carRNAs themselves has been an enigma. Recent publications from the He Lab at UChicago have shown the role of RNA N6-methyladenosine (m6A) in regulating carRNA stability and function. m6A is among the most abundant mRNA modifications in mammals. Seminal work from our lab has reported that the “writers” of m6A (e.g. methyltransferase-like [METTL3] and METTL14) are significantly downregulated in islets of humans with type 2 diabetes (T2D). Consequently, the global m6A landscape in the islets segregates the T2D from the control group significantly better than the transcriptome (n=7 for Control and n=8 for T2D islets). Hypomethylation of key transcripts in the insulin/IGF-1-AKT-PDX1 pathway led to impaired insulin secretion and decreased β-cell proliferation. We now show this decreased m6A on RNA is not limited to the mRNA but also affects chromatin-associated regulatory RNAs (carRNA). Intriguingly, downregulation of METTL3 and METTL14 in human β-cell line EndoC-βH1 differentially regulates these regulatory versus protein-coding transcripts. We observe that while METTL14 KD causes global downregulation of transcripts belonging to pathways important for β-cell identity and function (including calcium signaling, PI3K-AKT/MAPK signaling pathway, pancreatic secretion etc.), it leads to an upregulation of pathways involved in RNA processing and global gene transcription (Transcription by RNA Pol II, metabolism and splicing of mRNA, chromatin organization and modification etc.) {false discovery rate (FDR) < 0.05}. Considering carRNAs have been previously reported to regulate global chromatin accessibility and transcription, our observations on their ability to get differentially regulated m6A writer proteins provide novel insights into the epigenetic regulation of human islet cells. These findings provide opportunities to develop therapeutic approaches to regulate β-cell identity and/or insulin secretion in T2D. Presentation: 6/3/2024

12331 Overcoming Limitations Of Identifying Proliferating β-cells In Dispersed Primary Islets Culture For Drug Discovery

Abstract Disclosure: H. Xu: None. S. Rebecca: None. S. Lee: None. J.P. Annes: None. Tremendous efforts have been made with screening platforms to identify islet β-cell mitogens that may be used to treat diabetes. However, promising compounds induce profound proliferation of islet non-β-cells in available screening platforms, calling for both β-cell targeted drug discovery and rigorous identification of β-cell identity to reduce false positivity. First, we used an established drug discovery dispersed islet cell-based platform(2D) to test the replication-promoting activity of GNF2133, a selective DYRK1A inhibitor that promotes β-cell proliferation, in isolated islets from human, rat and mouse. After 72 h in vitro culture, replication of non-β cells (PDX/Insulin negative) contributed to over 60% of the total replicating cells (Ki67+) in all species (human: 64%, rat: 71%, mouse: 67%). Mouse islets, which exhibit the greatest non-β-cell replication response upon GNF2133 treatment (4-fold above baseline, [50 nM]), were selected for subsequent studies. Next, we evaluated identification efficiency of β cell markers in this image-based platform. β cells, selected by the quantification value of insulin intensity, comprised 60-70% of total cell population at 48 h, 50-60% at 72 h and 20-30% at 96 h (p< 0.0001 for both comparisons: 48 h vs 72 h, 72 h vs 96 h). Basal replication of β-cells (Insulin+Ki67+) was 2.80%, 2.32%, 0.85% at 48 h, 72 h and 96 h, respectively. By comparison, the proportion of non-β cells showed an increasing trend as 2.48%, 6.49%, 8.68%, correspondingly. Identification with PDX1, another β cell marker, exhibited the same findings. Prolonged culture of dispersed islet cells, as these results indicate, favors growth of non-β-cells over β-cells. In addition, proliferating β-cells express lower levels of differentiation markers makes their discernment from replicating non-β cells more challenging. 窗体顶端 To minimize the duration of monolayer culture, replication induction was measured using intact islets with addition of BrdU during the last 24 h of culture. Then, islets were either directly fixed (3D) or dispersed and cultured for an additional 36 hour before being fixed (3D+2D). Immunostaining showed 70-80% PDX1 positive cells from both methods, which resembles in vivo β cell distribution within primary mouse islets. Basal β-cell replication in 3D+2D method was 0.30%, similar to in vivo BrdU labelling level. Upon mitogen treatment, PDX1+BrdU+ cells increased to 6.57% in 3D+2D method, slightly lower than 10.02% in 3D assay (p<0.05) yet significantly higher than 1.15% in 2D assay (<0.01). In summary, we developed a 3D+2D assay that enhances β-cell survival and the β-cell replication-induction response. This platform, while offering reduced throughput, provides a robust platform for discovery of β-cell replication-promoting compounds. Further validation with human islets is needed. Presentation: 6/2/2024

Obese have comparable ankle brachial pressure index but higher β-cell function and insulin resistance as compared to normal-weight type 2 diabetes mellitus patients.

To compare ankle brachial pressure index (ABPI) in normal weight and obese/overweight type 2 diabetes mellitus patients (T2DM) to see the impact of obesity on the occurrence of peripheral artery disease (PAD) in T2DM patients. Secondly to investigate the relationship between ABPI, insulin resistance, and beta cell function and between adipocytokines and obesity parameters. A total of 120 BMI-categorized Normal weight (NW) T2DM (n = 53) patients and obese/overweight T2DM (n = 67) patients were recruited in this study. ABPI measurements were performed for the assessment of PAD. The anthropometry and body composition of the patients were measured. Plasma fasting insulin, adiponectin, and IL-6 levels were measured by ELISA kits. ABPI scores were found to be comparable between both groups of patients (p = 0.787). A significant positive correlation was observed between ABPI and beta cell function. Insulin resistance was found to correlate positively while adiponectin negatively with obesity parameters. The ABPI score was comparable between both groups of patients, suggesting that vascular complications may occur at the same rate in NW as well as in obese/overweight diabetic patients. The positive association of insulin resistance as well as the negative association of adiponectin with obesity parameters, are suggestive of the importance of body fat distribution in predicting insulin resistance and the inflammatory status of the cells.

8052 carRNA m6A methylation regulates transcription state and chromatin accessibility in human islets in normal physiology and type 2 diabetes

Abstract Disclosure: N. Shukla: None. C. Ju: None. H. Li: None. C. He: None. R. Kulkarni: Advisory Board Member; Self; Novo Nordisk, Biomea Fusion Inc, REDD Pharma. Grant Recipient; Self; Inversago. Chromatin-associated regulatory RNAs (carRNA), which include promoter- and enhancer-associated RNAs as well as several non-coding repeat elements have been established in the literature as important regulators of global gene transcription. However, the regulation of carRNAs themselves has been an enigma. Recent publications from the He Lab at UChicago have shown the role of RNA N6-methyladenosine (m6A) in regulating carRNA stability and function. m6A is among the most abundant mRNA modifications in mammals. Seminal work from our lab has reported that the “writers” of m6A (e.g. methyltransferase-like [METTL3] and METTL14) are significantly downregulated in islets of humans with type 2 diabetes (T2D). Consequently, the global m6A landscape in the islets segregates the T2D from the control group significantly better than the transcriptome (n=7 for Control and n=8 for T2D islets). Hypomethylation of key transcripts in the insulin/IGF-1-AKT-PDX1 pathway led to impaired insulin secretion and decreased β-cell proliferation. We now show this decreased m6A on RNA is not limited to the mRNA but also affects chromatin-associated regulatory RNAs (carRNA). Intriguingly, downregulation of METTL3 and METTL14 in human β-cell line EndoC-βH1 differentially regulates these regulatory versus protein-coding transcripts. We observe that while METTL14 KD causes global downregulation of transcripts belonging to pathways important for β-cell identity and function (including calcium signaling, PI3K-AKT/MAPK signaling pathway, pancreatic secretion etc.), it leads to an upregulation of pathways involved in RNA processing and global gene transcription (Transcription by RNA Pol II, metabolism and splicing of mRNA, chromatin organization and modification etc.) {false discovery rate (FDR) < 0.05}. Considering carRNAs have been previously reported to regulate global chromatin accessibility and transcription, our observations on their ability to get differentially regulated m6A writer proteins provide novel insights into the epigenetic regulation of human islet cells. These findings provide opportunities to develop therapeutic approaches to regulate β-cell identity and/or insulin secretion in T2D. Presentation: 6/3/2024

The Role of Nitric Oxide, Lipocalin-2, and Proinflammatory Cytokines on Proteinuria and Insulin Resistance in Type 2 Diabetes Mellitus Subgroups.

Nitric oxide (NO) is a bioactive signaling molecule that mediates various physiological and biological processes. Type 2 diabetes mellitus (T2DM) can be categorized into several subgroups according to fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) levels. Few studies have closely examined the effect of NO and lipocalin-2 on albuminuria and insulin resistance in T2DM subgroups. This study investigated the role of NO, lipocalin-2, and proinflammatory cytokines on the development of proteinuria and insulin resistance in patients with T2DM subgroups. A total of 256 subjects, including 191 patients with T2DM and 65 non-diabetic healthy individuals, were evaluated. NO metabolites (NOx), lipocalin-2, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels were measured. Patients with T2DM were classified into three subgroups: patients with FPG-defined diabetes (PG-DM), those with HbA1c-defined diabetes (HA-DM), and those who met the criteria for both FPG and HbA1c (PG/HA-DM). The albumin-to-creatinine ratio (ACR) and the homeostasis model assessment of β-cell function (HOMA-B) and insulin resistance (HOMA-IR) were calculated. NOx, lipocalin-2, and TNF-α levels were significantly higher in patients with T2DM than in healthy individuals. Patients with PG/HA-DM had significantly higher NOx levels than those with PG-DM or HA-DM. Of the patients with high NOx levels, patients with lipocalin-2 elevation exhibited higher ACR and HOMA-IR than those without lipocalin-2 elevation. NOx was positively correlated with lipocalin-2, ACR, HOMA-IR, and TNF-α but not with HOMA-B and IL-6. The upper quartile of NOx levels led to a 1.2-fold increase in the risk of albuminuria (odds ratio: 1.215; 95% CI: 1.012-2.418; p < 0.001). NO plays a crucial role in proteinuria and insulin resistance by collaborating with lipocalin-2 and TNF-α, showing significantly higher levels in patients with PG/HA-DM than in those with PG-DM or HA-DM.

Association Between Mycobacterium tuberculosis Sensitization and Insulin Resistance Among US Adults Screened for Type 2 Diabetes Mellitus.

Type 2 diabetes mellitus (T2DM) may be a long-term sequela of infection with Mycobacterium tuberculosis (Mtb) by mechanisms that remain to be fully explained. We evaluated the association between Mtb sensitization and T2DM and, via mediation analysis, the extent to which it is mediated by insulin resistance and/or β-cell failure. Adults were assessed for T2DM by fasting plasma glucose, 2-hour oral glucose tolerance testing, and hemoglobin A1c; β-cell dysfunction and insulin resistance by homoeostasis model assessment 2; and Mtb sensitization by tuberculin skin testing. Associations between Mtb sensitization and T2DM were modeled with probit regression and decomposed into indirect effects of β-cell dysfunction and insulin resistance. Analyses were adjusted for sociodemographic, behavioral, and clinical characteristics. We included 1843 adults. Individuals with Mtb sensitization were older than those without Mtb (median [IQR], 54 [39-64] vs 47 [33-62] years). As compared with being uninfected, Mtb sensitization was associated with T2DM (adjusted absolute risk difference, 9.34% [95% CI, 2.38%-15.0%]; P < .001) and increased insulin resistance (adjusted median difference, 0.16 [95% CI, .03-.29]; P = .014) but not β-cell dysfunction (adjusted median difference, -3.1 [95% CI, -10.4 to 4.3]; P = .42). In mediation analyses, insulin resistance mediated 18.3% (95% CI, 3.29%-36.0%; P = .020) of the total effect of the association between Mtb sensitization and T2DM. Definitive prospective studies examining incident T2DM following tuberculosis are warranted. Notwithstanding, our findings suggest that exposure to Mtb may be a novel risk factor for T2DM, likely driven by an increase in insulin resistance.

PARN Maintains RNA Stability to Regulate Insulin Maturation and GSIS in Pancreatic β Cells.

Diabetes, a metabolic disorder characterized by hyperglycemia, underscores the importance of normal pancreatic β-cell development and function in maintaining glucose homeostasis. Poly(A)-specific ribonuclease (PARN) serves as the principal regulator of messenger RNA (mRNA) stability, yet its specific role in pancreatic β cells remains unclear. This study utilizes mice with targeted PARN deficiency in β cells to elucidate this role. Notably, Parn conditional knockout mice present unaltered β-cell development and insulin sensitivity but reduced glucose-stimulated insulin secretion (GSIS). The observed outcomes are corroborated in NIT-1 cells. Furthermore, transcriptomic analyses reveal aberrant mRNA expression of genes crucial for insulin secretion in PARN-deficient β cells. Insights from linear amplification of complementary DNA ends and sequencing and coimmunoprecipitation experiments reveal an interaction between PARN and polypyrimidine tract-binding protein 1 (PTBP1), regulating the RNA stability of solute carrier family 30, member 8 (Slc30a8) and carbohydrate sulfotransferase 3 (Chst3). Interference with either PARN or PTBP1 disrupts this stability. These data indicate that PARN deficiency hampers GSIS and insulin maturation by destabilizing Slc30a8 and Chst3 RNAs. These findings provide compelling evidence indicating that PARN is a potential therapeutic target for enhancing insulin maturation and secretion.

Supplementation with cysteine improved metabolic syndrome in rats by increasing antioxidant potential in the liver and adipose tissue, as well as decreasing hepatic NF-κB expression

Insulin resistance is a key characteristic of metabolic syndrome (MetS). The hepatic nuclear factor- κB (NF-κB) signaling pathway plays a crucial role in insulin resistance and the development of type 2 diabetes. Our study aimed to examine the impact of cysteine (Cys) on various biochemical and histopathological parameters in the liver and kidney, hepatic NF-kβ expression, oxidative stress, inflammation, glycation, carbonyl stress markers, and insulin resistance. The study involved four groups of rats, each consisting of seven rats: a control group, a MetS group, and two similar groups receiving Cys treatment. Metabolic syndrome was induced in rats by administering a 40% sucrose solution, while, the treated groups received 50 mg/L Cys in their drinking water. Various factors, including body weight, hepatic NF-kβ expression, levels of antioxidants, anti-glycation, oxidative stress, carbonyl stress, inflammatory, anti-glycation, and glycation markers were assessed in blood and tissues. Liver and kidney function parameters and metabolic profiles were measured. Finally, liver tissue was also evaluated by a pathologist. The results showed that Cys reduced hepatic NF-kβ expression, oxidative stress, inflammation, glycation and carbonyl stress markers, as well as liver fatty content, blood sugar levels, insulin resistance, cardiovascular risk index, and body weight. The treatment also mitigated histopathological liver changes and acute hepatitis (p < 0.001). Cysteine exhibited anti-obesity and anti-atherosclerotic effects, improved β-cell function, insulin sensitivity, and lipid metabolism, and enhanced liver and kidney function, as well as prevented acute hepatitis by restoring the GSH/GSSG ratio, hepatic NF-kβ signaling, and carbonyl stress.

Retinal and Choroidal Phenotypes Across Novel Subtypes of Type 2 Diabetes Mellitus

PurposeThis study aimed to investigate longitudinal changes in choroidal thickness (CT) and ganglion cell-inner plexiform layer thickness (GC-IPLT) across distinct phenotypes of type 2 diabetes mellitus (T2DM) patients. DesignProspective observational cohort study. MethodsT2DM patients were categorized into five groups (SAID, SIDD, SIRD, MOD, and MARD) using K-means clustering based on β-cell function and insulin resistance. Swept-source optical coherence tomography measured baseline and 4-year follow-up CT and GC-IPLT. Linear mixed-effects models assessed absolute and relative changes in CT and GC-IPLT across subtypes. ResultsOver a median 4.11-year follow-up, CT and GC-IPLT decreased significantly across all groups. Choroidal thinning rates were most pronounced in SIDD (-6.5±0.53 µm/year and -3.5±0.24%/year) and SAID (-6.27±0.8 µm/year and -3.19±0.37%/year), while MARD showed the slowest thinning (-3.63±0.34 µm/year and -1.98±0.25%/year). SIRD exhibited the greatest GC-IPLT loss (-0.66±0.05 µm/year and -0.91±0.07%/year), with the least in SIDD (-0.36±0.05 µm/year and -0.49±0.07%/year), all statistically significant (Ps < 0.001). Adjusted for variables, SIDD and SAID groups showed faster CT thinning than MARD [-2.57 µm/year (95% CI: -4.16 to -0.97; P=0.002) and -2.89 µm/year (95% CI: -4.12 to -1.66; P<0.001), respectively]. GC-IPLT thinning was notably accelerated in SIRD versus MARD, but slowed in SIDD relative to MARD [differences of -0.16 µm/year (95% CI: -0.3 to -0.03; P=0.015) and 0.15 µm/year (95% CI: 0.03 to 0.27; P=0.015), respectively]. Stratified analysis revealed significant differences among non-DR groups. ConclusionsMicrovascular damage in the choroid is associated with SIDD patients, whereas early signs of retinal neurodegeneration are evident in SIRD patients. All these changes may precede the onset of DR.

PERIAPICAL INFLAMMATORY LESIONS AND DIABETES MELLITUS TYPE II– A REVIEW

Periapical periodontitis is a chronic inflammatory disease, caused by endodontic infection, and its development is regulated by the host immune/inflammatory response. Metabolic disorders, which are largely dependent on life style such as eating habits, have been interpreted as a “metabolically-triggered” low-grade systemic inflammation and may interact with periapical periodontitis by triggering immune modulation. Diabetes mellitus (DM) is a group of complex multisystem metabolic disorders due to a deficiency in insulin secretion caused by pancreatic β-cell dysfunction and/or insulin resistance in liver and muscle. Objective: In this paper, the current status of knowledge regarding the relationship between periapical inflammation and diabetes mellitus type II is reviewed. Material and method: Research was conducted on scientific papers published on Medline - Pub med in the past 10 years (from 2012-2022). The search was performed using the Mesh (Medical Subject Headings) key words: periapical inflammatory lesions, periapical periodontitis and diabetes mellitus type II. Results: Several studies have analyzed the possible association between periapical inflammatory lesions and diabetes mellitus type II. The results of studies carried mainly in animal models, less in humans suggested association between endodontic variables such as apical periodontitis, root canal treatment and diabetes mellitus type 2.The demonstration of association does not prove by itself the existence of a cause-effect relationship. Conclusion: A review of the literature showed connection between periapical inflammatory lesions and diabetes mellitus type II, but prospective case control clinical studies are needed for further clarifying this relation.

Mitochondrial Dysfunction and Imeglimin: A New Ray of Hope for the Treatment of Type-2 Diabetes Mellitus.

Diabetes is a rapidly growing health challenge and epidemic in many developing countries, including India. India, being the diabetes capital of the world, has the dubious dual distinction of being the leading nations for both undernutrition and overnutrition. Diabetes prevalence has increased in both rural and urban areas, affected the younger population and increased the risk of complications and economic burden. These alarming statistics ring an alarm bell to achieve glycemic targets in the affected population in order to decrease diabetes-related morbidity and mortality. In the recent years, diabetes pathophysiology has been extended from an ominous triad through octet and dirty dozen etc. There is a new scope to target multiple pathways at the molecular level to achieve a better glycemic target and further prevent micro- and macrovascular complications. Mitochondrial dysfunction has a pivotal role in both β-cell failure and insulin resistance. Hence, targeting this molecular pathway may help with both insulin secretion and peripheral tissue sensitization to insulin. Imeglimin is the latest addition to our anti-diabetic armamentarium. As imeglimin targets, this root cause of defective energy metabolism and insulin resistance makes it a new add-on therapy in different diabetic regimes to achieve the proper glycemic targets. Its good tolerability and efficacy profiles in recent studies shows a new ray of hope in the journey to curtail diabetes-related morbidity.

Effect of bovine beta-casomorphins on rat pancreatic beta cells (RIN-5F) under glucotoxic stress

Beta-casomorphins (BCMs) are the bio-active peptides having opioid properties which are formed by the proteolytic digestion of β-caseins in milk. BCM-7 forms when A1 milk is digested in the small intestine due to a histidine at the 67th position in β-casein, unlike A2 milk, which has proline at this position and produces BCM-9. BCM-7 has further degraded into BCM-5 by the dipeptidyl peptidase-IV (DPP-IV) enzyme in the intestine. The opioid-like activity of BCM-7 is responsible for eliciting signaling pathways which enable a wide range of physiological effects. The aim of our study was to find out the differential role of BCMs (BCM-7, BCM-9 and BCM-5) on pancreatic β-cell proliferation, insulin secretion, and opioid peptide binding receptors from β-cells (RIN-5F cell line) in normal (5.5 mM) and high glucose (27.5 mM) concentrations. Our results showed that BCM-7/9/5 did not affect β-cell viability, proliferation, and insulin secretion at normal glucose level. However, at higher glucose concentration, BCMs significantly protected β-cells from glucotoxicity but did not affect the insulin secretion. Interestingly, in the presence of Mu-opioid peptide receptor antagonist CTOP, BCMs did not protect β-cells from glucotoxicity. The results suggest that BCMs protect β-cells from glucotoxicity via non-opioid mediated pathways because BCMs did not modulate the gene expression of the mu, kappa and delta opioid peptide receptors.

The Role of Dietary Anthocyanins for Managing Diabetes Mellitus-Associated Complications.

Diabetes mellitus (DM) is an intricate metabolic disorder marked by persistent hyperglycemia, arising from disruptions in glucose metabolism, with two main forms, type 1 and type 2, involving distinct etiologies affecting β-cell destruction or insulin levels and sensitivity. The islets of Langerhans, particularly β-cells and α-cells, play a pivotal role in glucose regulation, and both DM types lead to severe complications, including retinopathy, nephropathy, and neuropathy. Plant-derived anthocyanins, rich in anti-inflammatory and antioxidant properties, show promise in mitigating DM-related complications, providing a potential avenue for prevention and treatment. Medicinal herbs, fruits, and vegetables, abundant in bioactive compounds like phenolics, offer diverse benefits, including glucose regulation and anti-inflammatory, antioxidant, anticancer, anti-mutagenic, and neuroprotective properties. Anthocyanins, a subgroup of polyphenols, exhibit diverse isoforms and biosynthesis involving glycosylation, making them potential natural replacements for synthetic food colorants. Clinical trials demonstrate the efficacy and safety of anthocyanins in controlling glucose, reducing oxidative stress, and enhancing insulin sensitivity in diabetic patients, emphasizing their therapeutic potential. Preclinical studies revealed their multifaceted mechanisms, positioning anthocyanins as promising bioactive compounds for managing diabetes and its associated complications, including retinopathy, nephropathy, and neuropathy.

β-cell function and long-term glycemic control in patients newly diagnosed with type 2 diabetes with moderate hyperglycemia after a 6-month course of basal insulin therapy

AimsTo evaluate whether treatment with insulin is advantageous compared with oral anti-diabetic drugs (OAD) for patients newly diagnosed with type 2 diabetes with moderate hyperglycemia. MethodsPatients newly diagnosed with type 2 diabetes with moderate hyperglycemia were recruited and randomized to receive insulin, metformin or sitagliptin treatment. The oral glucose tolerance test (OGTT) was performed before treatment and 6 months thereafter. The primary outcome was the glycohemoglobin (HbA1c) level change. For the secondary efficacy analysis, the β-cell function and insulin sensitivity were calculated from the OGTT, as was the proportion of subjects who reached the treatment target (HbA1c level < 7.0 % or < 6.5 %) at 6 months. ResultsWe randomized 50 patients to the three groups and 32 patients who received the allocated treatment were analyzed. The change of HbA1c level in the insulin, metformin, and sitagliptin groups was − 2.06 ± 1.37 %, −0.43 ± 0.32 %, and − 1.62 ± 0.92 %, respectively. This change was smallest in the metformin group. There was no significant difference in the changes or final HbA1c levels between the insulin and sitagliptin groups. The treat-to-target (HbA1c level < 7.0 %) rates in the insulin, metformin and sitagliptin were 75 %, 50 % and 100 %, respectively. The treat-to-target rates were not significantly different among the three groups. The insulin secretion indices, including the Matsuda index and HOMA-IR, indicated that the groups did not differ after 6 months of therapy. ConclusionA 6-month course of basal insulin therapy did not benefit patients newly diagnosed with diabetes with moderate hyperglycemia in terms of insulin sensitivity or insulin secretion.