The Role of Estrogens in Pancreatic Islet Physiopathology

High Estradiol Environment After IVF Causes Increased Risk of Glucose Metabolic Dysfunction in Offspring

CONTEXT

Assisted reproductive technology (ART) is associated with increased metabolic risks in offspring. The effect of high maternal estradiol (E2) levels during early pregnancy on the glucose metabolism of offspring remains unclear.

OBJECTIVE

This work aimed to evaluate glucose metabolism in children conceived via in vitro fertilization (IVF) and to assess whether high E2 exposure during early pregnancy is associated with metabolic alterations.

METHODS

This retrospective analysis included 500 singletons aged 3 to 10 years born after fresh embryo transfer (ET) (n = 200), frozen ET (n = 100), and natural conception (NC) (n = 200) from a university hospital. Children underwent anthropometric measurements and examinations for fasting glucose, insulin, and lipid levels. A mouse model of high E2 exposure during early pregnancy was established to study glucose and insulin tolerance, and insulin secretion.

RESULTS

Compared with NC, children born after fresh ET showed higher fasting glucose/insulin levels, increased insulin resistance, and higher incidence of impaired fasting glucose, which might be associated with higher maternal E2 levels. Frozen ET showed intermediate results. In mice, offspring exposed to high E2 levels during gestation exhibited impaired glucose/insulin tolerance and defects in insulin secretion.

CONCLUSION

High maternal E2 levels in early pregnancy are associated with altered glucose metabolism and increased metabolic risks in IVF-conceived children. Further studies are needed to elucidate the underlying mechanisms.

Dissecting the mechanisms of velvet antler extract against diabetic osteoporosis via network pharmacology and proteomics

ETHNOPHARMACOLOGICAL RELEVANCE

Velvet antler (VAE) is a famous traditional Chinese medicine (TCM), which has been used for thousands of years to treat bone-related diseases. Nonetheless, whether VAE has anti-diabetic osteoporosis (DOP) properties remains to be elucidated.

AIM OF THE STUDY

The therapeutic mechanism of VAE on DOP is based on integrated proteomics of network pharmacology strategies to study related targets and pathways.

MATERIALS AND METHODS

Liquid chromatography-mass spectrometry (LC/MS) was used to analyze the main molecular components present in the VAE. The DOP mouse model was created by combining a high-fat diet with streptozotocin (STZ). High glucose (HG) induced MC3T3-E1 cells were used as a cell model to evaluate the therapeutic effect of VAE. The mechanisms of VAE in treating DOP were predicted through proteomics. Molecular docking, molecular dynamics simulations, DARTS and functional experiments were employed to further verify its mechanisms.

RESULTS

Altogether 30 components were identified by LC-MS. In vitro and in vivo results were confirmed that VAE had a protective effect on DOP. Combined with network pharmacology, proteomics and functional experiments revealed that TNF/PI3K-AKT signaling pathway may be the potential biochemical pathway for VAE in treating DOP.

CONCLUSIONS

The innovation of this study was investigating the effectiveness of VAE in treating DOP in vivo and in vitro and suggested that VAE might exert anti-DOP effects through the TNF/PI3K-AKT signaling pathway by network pharmacology and proteomics and found that ATK1 was the core target of VAE, which provided valuable insights for the clinical application of VAE in DOP.

The GHSR1a antagonist LEAP2 regulates islet hormone release in a sex-specific manner

LEAP2, a liver-derived antagonist for the ghrelin receptor, GHSR1a, counteracts the effects of ghrelin on appetite and energy balance. Less is known about its impact on blood glucose-regulating hormones from pancreatic islets. Here, we investigate whether acyl-ghrelin (AG) and LEAP2 regulate islet hormone release in a cell-type- and sex-specific manner. Hormone content from secretion experiments with isolated islets from male and female mice was measured by radioimmunoassay and mRNA expression by qPCR. LEAP2 enhanced insulin secretion in islets from males (P < 0.01) but not females (P > 0.2), whilst AG-stimulated somatostatin release was significantly reversed by LEAP2 in males (P < 0.001) but not females (P > 0.2). Glucagon release was not significantly affected by AG and LEAP2. Ghsr1a, Ghrelin, Leap2, Mrap2, Mboat4, and Sstr3 islet mRNA expression did not differ between sexes, whereas the SSTR3 antagonist MK4256 enhanced glucose-induced insulin secretion in islets from males only. In control male islets maintained without 17-beta oestradiol (E2), AG exerted an insulinostatic effect (P < 0.05), with a trend towards reversal by LEAP2 (P = 0.06). Both were abolished by 72 h E2 pre-treatment (10 nmol/L, P > 0.2). AG-stimulated somatostatin release was inhibited by LEAP2 from control (P < 0.001) but not E2-treated islets (P > 0.2). LEAP2 and AG did not modulate insulin secretion from MIN6 beta cells and Mrap2 was downregulated (P < 0.05) and Ghsr1a upregulated (P < 0.0001) in islets from Sst-/- mice. Our findings show that AG and LEAP2 regulate insulin and somatostatin release in an opposing and sex-dependent manner, which in males can be modulated by E2. We suggest that regulation of SST release is a key starting point for understanding the role of GHSR1a in islet function and glucose metabolism.

Sex differences in the development of experimental diabetic retinopathy

This study aimed to characterize the role of female sex in the pathogenesis of diabetic retinopathy. In the retinae of female Ins2Akita-diabetic mice (F-IA), ovariectomized female Ins2Akita-diabetic mice (F-IA/OVX), male Ins2Akita-diabetic mice (M-IA), and female STZ-diabetic mice (F-STZ), the formation of reactive metabolites and post-translational modifications, damage to the neurovascular unit, and expression of cellular stress response genes were analyzed. Compared to the male diabetic retina, the concentrations of the glycation adduct fructosyl-lysine, the Maillard product 3-deoxyglucosone, and the reactive metabolite methylglyoxal were significantly reduced in females. In females, there was also less evidence of diabetic damage to the neurovascular unit, as shown by decreased pericyte loss and reduced microglial activation. In the male diabetic retina, the expression of several members of the crystallin gene family (Cryab, Cryaa, Crybb2, Crybb1, and Cryba4) was increased. Clinical data from type 1 diabetic females showed that premenopausal women had a significantly lower prevalence of diabetic retinopathy compared to postmenopausal women stratified for disease duration and glycemic control. These data emphasize the importance of estradiol in protecting the diabetic retina and highlight the pathogenic relevance of sex in diabetic retinopathy.

Receptors and Signaling Pathways Controlling Beta-Cell Function and Survival as Targets for Anti-Diabetic Therapeutic Strategies

Preserving the function and survival of pancreatic beta-cells, in order to achieve long-term glycemic control and prevent complications, is an essential feature for an innovative drug to have clinical value in the treatment of diabetes. Innovative research is developing therapeutic strategies to prevent pathogenic mechanisms and protect beta-cells from the deleterious effects of inflammation and/or chronic hyperglycemia over time. A better understanding of receptors and signaling pathways, and of how they interact with each other in beta-cells, remains crucial and is a prerequisite for any strategy to develop therapeutic tools aimed at modulating beta-cell function and/or mass. Here, we present a comprehensive review of our knowledge on membrane and intracellular receptors and signaling pathways as targets of interest to protect beta-cells from dysfunction and apoptotic death, which opens or could open the way to the development of innovative therapies for diabetes.

Naringenin protects pancreatic β cells in diabetic rat through activation of estrogen receptor β

Naringenin is a citrus flavonoid that potently improves metabolic parameters in animal models of metabolic disorders, such as type 2 diabetes. Estrogen receptor (ER) activation promotes β cell function and survival, thereby improving systemic glucose metabolism. In this study, we used a luciferase reporter assay, isolated rat islets and a diabetic rat model to investigate the effects of naringenin on ER signaling and the underlying mechanism of naringenin-mediated improvement of islet function in diabetes. Naringenin specifically activated ERβ without affecting the activity of ERα, G protein-coupled estrogen receptor (GPER) or estrogen-related receptor (ERR) α/β/γ. Additionally, treatment with naringenin enhanced glucose-stimulated insulin secretion in isolated rat islets. This effect was abrogated by PHTPP, an ERβ antagonist. Transcriptomic analysis revealed that naringenin upregulated the expression of genes, such as Pdx1 and Mafa, which are closely linked to improved β-cell function. In consistence, single administration of naringenin to normal rats elevated plasma insulin levels and improved glucose responses. These beneficial effects were blocked by PHTPP. In streptozocin-nicotinamide induced diabetic rats, treatment for 2 weeks with naringenin alone, but not in combination with PHTPP, significantly restored pancreatic β cell mass and improved glucose metabolism. Collectively, these data support that naringenin specifically activate ERβ to improve insulin secretion in the primary rat islets. Furthermore, naringenin administration also protected β cell function and reversed glucose dysregulation in diabetic rats. These beneficial effects are at least partially dependent on the ERβ pathway.

GPER involvement in inflammatory pain

Chronic pain is a worldwide refractory health disease that causes major financial and emotional burdens and that is devastating for individuals and society. One primary source of pain is inflammation. Current treatments for inflammatory pain are weakly effective, although they usually replace analgesics, such as opioids and non-steroidal anti-inflammatory drugs, which display serious side effects. Emerging evidence indicates that the membrane G protein-coupled estrogen receptor (GPER) may play an important role in the regulation of inflammation and pain. Herein, we focus on the consequences of pharmacological and genetic GPER modulation in different animal models of inflammatory pain. We also provide a brief overview of the putative mechanisms including the direct action of GPER on pain transmission and inflammation.

Stromal Interaction Molecule 1 Maintains β-Cell Identity and Function in Female Mice Through Preservation of G-Protein-Coupled Estrogen Receptor 1 Signaling

Altered endoplasmic reticulum (ER) Ca2+ signaling has been linked with β-cell dysfunction and diabetes development. Store-operated Ca2+ entry replenishes ER Ca2+ through reversible gating of plasma membrane Ca2+ channels by the ER Ca2+ sensor, stromal interaction molecule 1 (STIM1). For characterization of the in vivo impact of STIM1 loss, mice with β-cell-specific STIM1 deletion (STIM1Δβ mice) were generated and challenged with high-fat diet. Interestingly, β-cell dysfunction was observed in female, but not male, mice. Female STIM1Δβ mice displayed reductions in β-cell mass, a concomitant increase in α-cell mass, and reduced expression of markers of β-cell maturity, including MafA and UCN3. Consistent with these findings, STIM1 expression was inversely correlated with HbA1c levels in islets from female, but not male, human organ donors. Mechanistic assays demonstrated that the sexually dimorphic phenotype observed in STIM1Δβ mice was due, in part, to loss of signaling through the noncanonical 17-β estradiol receptor (GPER1), as GPER1 knockdown and inhibition led to a similar loss of expression of β-cell maturity genes in INS-1 cells. Together, these data suggest that STIM1 orchestrates pancreatic β-cell function and identity through GPER1-mediated estradiol signaling.

ARTICLE HIGHLIGHTS

Store-operated Ca2+ entry replenishes endoplasmic reticulum (ER) Ca2+ through reversible gating of plasma membrane Ca2+ channels by the ER Ca2+ sensor, stromal interaction molecule 1 (STIM1). β-Cell-specific deletion of STIM1 results in a sexually dimorphic phenotype, with β-cell dysfunction and loss of identity in female but not male mice. Expression of the noncanonical 17-β estradiol receptor (GPER1) is decreased in islets of female STIM1Δβ mice, and modulation of GPER1 levels leads to alterations in expression of β-cell maturity genes in INS-1 cells.

Review of mendelian randomization studies on age at natural menopause

Menopause marks the end of the reproductive phase of life. Based on epidemiological studies, abnormal age at natural menopause (ANM) is thought to contribute to a number of adverse outcomes, such as osteoporosis, cardiovascular disease, and cancer. However, the causality of these associations remains unclear. A powerful epidemiological method known as Mendelian randomization (MR) can be used to clarify the causality between ANM and other diseases or traits. The present review describes MR studies that included ANM as an exposure, outcome and mediator. The findings of MR analyses on ANM have revealed that higher body mass index, poor educational level, early age at menarche, early age at first live birth, early age at first sexual intercourse, and autoimmune thyroid disease appear to be involved in early ANM etiology. The etiology of late ANM appears to be influenced by higher free thyroxine 4 and methylene tetrahydrofolate reductase gene mutations. Furthermore, early ANM has been found to be causally associated with an increased risk of osteoporosis, fracture, type 2 diabetes mellitus, glycosylated hemoglobin, and the homeostasis model of insulin resistance level. In addition, late ANM has been found to be causally associated with an increased systolic blood pressure, higher risk of breast cancer, endometrial cancer, endometrioid ovarian carcinoma, lung cancer, longevity, airflow obstruction, and lower risk of Parkinson's disease. ANM is also a mediator for breast cancer caused by birth weight and childhood body size. However, due to the different instrumental variables used, some results of studies are inconsistent. Future studies with more valid genetic variants are needed for traits with discrepancies between MRs or between MR and other types of epidemiological studies.

Protective effect of phytoestrogens on nonalcoholic fatty liver disease in postmenopausal women

Non-alcoholic fatty liver disease (NAFLD) is a progressive metabolic disease characterized by hepatic steatosis, inflammation, and fibrosis that seriously endangers global public health. Epidemiological studies have shown that the incidence of non-alcoholic fatty liver disease in postmenopausal women has significantly increased. Studies have shown that estrogen deficiency is the main reason for this situation, and supplementing estrogen has become a new direction for preventing the occurrence of postmenopausal fatty liver. However, although classical estrogen replacement therapy can reduce the incidence of postmenopausal NAFLD, it has the risk of increasing stroke and cardiovascular diseases, so it is not suitable for the treatment of postmenopausal NAFLD. More and more recent studies have provided evidence that phytoestrogens are a promising method for the treatment of postmenopausal NAFLD. However, the mechanism of phytoestrogens in preventing and treating postmenopausal NAFLD is still unclear. This paper summarizes the clinical and basic research evidence of phytoestrogens and reviews the potential therapeutic effects of phytoestrogens in postmenopausal NAFLD from six angles: enhancing lipid metabolism in liver and adipose tissue, enhancing glucose metabolism, reducing oxidative stress, reducing the inflammatory response, regulating intestinal flora, and blocking liver fibrosis (Graphical Abstract).

Genetic prediction of age at menarche, age at natural menopause and type 2 diabetes: A Mendelian randomization study

BACKGROUND AND AIMS

The relationship between reproductive factors and type 2 diabetes (T2D) is controversial; therefore, we explored the causal relationship of age at menarche (AAM), age at natural menopause (ANM), with the risk of T2D and glycemic traits using two-sample Mendelian randomization.

METHODS AND RESULTS

We used publicly available data at the summary level of genome-wide association studies, where AAM (N = 329,345), ANM (N = 69,360), T2D (N = 464,389). The inverse variance weighting (IVW) method was employed as the primary method. To demonstrate the robustness of the results, we also conducted various sensitivity analysis methods including the MR-Egger regression, the weighted median (WM) and the MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) test. After excluding IVs associated with confounders, we found a causal association between later AAM and reduced risk of T2D (OR 0.81 [95% CI 0.75, 0.87]; P = 2.20 × 10^-8), lower levels of FI (β -0.04 [95% CI -0.06, -0.01]; P = 2.19 × 10^-3), FPG (β -0.03 [95% CI -0.05, -0.007]; P = 9.67 × 10^-5) and HOMA-IR (β -0.04 [95% CI -0.06, -0.01]; P = 4,95 × 10^-3). As for ANM, we only found a causal effect with HOMA-IR (β -0.01 [95% CI -0.02, -0.005]; P = 1.77 × 10^-3), but not with T2D.

CONCLUSIONS

Our MR study showed a causal relationship between later AAM and lower risk of developing T2D, lower FI, FPG and HOMA-IR levels. This may provide new insights into the prevention of T2D in women.

Outbred Mice with Streptozotocin-Induced Diabetes Show Sex Differences in Glucose Metabolism

Outbred mice (ICR) with different genotypes and phenotypes have been reported to be more suitable for scientific testing than inbred mice because they are more similar to humans. To investigate whether the sex and genetic background of the mice are important factors in the development of hyperglycemia, we used ICR mice and divided them into male, female, and ovariectomized female (FOVX) groups and treated them with streptozotocin (STZ) for five consecutive days to induce diabetes. Our results show that fasting blood glucose and hemoglobin A1c (HbA1c) levels were significantly higher in diabetes-induced males (M-DM) and ovariectomized diabetes-induced females (FOVX-DM) than in diabetes-induced females (F-DM) at 3 and 6 weeks after STZ treatment. Furthermore, the M-DM group showed the most severe glucose tolerance, followed by the FOVX-DM and F-DM groups, suggesting that ovariectomy affects glucose tolerance in female mice. The size of pancreatic islets in the M-DM and FOVX-DM groups was significantly different from that of the F-DM group. The M-DM and FOVX-DM groups had pancreatic beta-cell dysfunction 6 weeks after STZ treatment. Urocortin 3 and somatostatin inhibited insulin secretion in the M-DM and FOVX-DM groups. Overall, our results suggest that glucose metabolism in mice is dependent on sex and/or genetic background.

Comprehensive Network Analysis Reveals the Targets and Potential Multitarget Drugs of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a metabolic disease with increasing prevalence and mortality year by year. The purpose of this study was to explore new therapeutic targets and candidate drugs for multitargets by single-cell RNA expression profile analysis, network pharmacology, and molecular docking. Single-cell RNA expression profiling of islet β cell samples between T2DM patients and nondiabetic controls was conducted to identify important subpopulations and the marker genes. The potential therapeutic targets of T2DM were identified by the overlap analysis of insulin-related genes and diabetes-related genes, the construction of protein-protein interaction network, and the molecular complex detection (MCODE) algorithm. The network distance method was employed to determine the potential drugs of the target. Molecular docking and molecular dynamic simulations were carried out using AutoDock Vina and Gromacs2019, respectively. Eleven cell clusters were identified by single-cell RNA sequencing (scRNA-seq) data, and three of them (C2, C8, and C10) showed significant differences between T2DM samples and normal samples. Eight genes from differential cell clusters were found from differential cell clusters to be associated with insulin activity and T2DM. The MCODE algorithm built six key subnetworks, with five of them correlating with inflammatory pathways and immune cell infiltration. Importantly, CCR5 was a gene within the key subnetworks and was differentially expressed between normal samples and T2DM samples, with the highest area under the ROC curve (AUC) of 82.5% for the diagnosis model. A total of 49 CCR5-related genes were screened, and DB05494 was identified as the most potential drug with the shortest distance to CCR5-related genes. Molecular docking illustrated that DB05494 stably bound with CCR5 (-8.0 kcal/mol) through multiple hydrogen bonds (LYS26, TYR37, TYR89, CYS178, and GLN280) and hydrophobic bonds (TRP86, PHE112, ILE198, TRP248, and TYR251). This study identified CCR5 as a potential therapeutic target and screened DB05494 as a potential drug for T2DM treatment.

Prenatal exposure to a mixture of PAHs causes the dysfunction of islet cells in adult male mice: Association with type 1 diabetes mellitus

Polycyclic aromatic hydrocarbons (PAHs) have been detected throughout the human body. Whether exposure to PAHs is associated with the incidence of type 1 diabetes mellitus should be investigated. To this end, pregnant mice were exposed to mixed PAHs (5, 50, or 500 μg/kg) once every other day during gestation. The adult male offspring displayed impaired glucose tolerance and reduced serum levels of glucagon and insulin. Immunohistochemical staining revealed increased numbers of apoptotic β-cells and a reduced β-cell mass in these males. The downregulated expression of pancreatic estrogen receptor α, androgen receptor, and transcription factor PDX1 was responsible for impacting β-cell development. The relatively reduced α-cell area was associated with downregulated ARX expression. The transcription of Isn2 and Gcg in pancreatic tissue was downregulated, which indicated that the function of β-cells and α-cells was impaired. Methylation levels in the Isn2 promotor were significantly elevated in mice prenatally exposed to 500 µg/kg PAHs, which was consistent with the change in its mRNA levels. The number of macrophages infiltrating islets was significantly increased, indicating that prenatal PAH exposure might reduce islet cell numbers in an autoimmune manner. This study shows that prenatal exposure to PAHs may promote the pathogenesis of type 1 diabetes mellitus.

Prolonged Islet Allograft Function is Associated With Female Sex in Patients After Islet Transplantation

BACKGROUND

Islet transplantation (ITx) has proved to be effective in preventing severe hypoglycemia and improving metabolic control in selected subjects with type 1 diabetes. Long-term graft function remains a challenge. Estrogens have been shown to protect β cells from metabolic stresses and improve revascularization of transplanted human islets in the mouse. We aimed to evaluate the influence of sex in allograft survival of ITx recipients.

METHODS

We analyzed a retrospective cohort of ITx recipients (n = 56) followed-up for up to 20 years. Allograft failure was defined as a stimulated C-peptide <0.3 ng/mL during a mixed-meal tolerance test. Subjects were divided into recipients of at least 1 female donor (group 1) and recipients of male donors only (group 2).

RESULTS

Group 1 subjects (n = 25) were aged 41.5 ± 8.4 years and group 2 subjects (n = 22) 45.9 ± 7.3 years (P = 0.062). Female recipient frequency was 44.8% (n = 13) in group 1 and 55.2% (n = 16) in group 2 (P = 0.145). Group 2 developed graft failure earlier than group 1 (680 [286-1624] vs 1906 [756-3256] days, P = 0.038). We performed additional analyses on female recipients only from each group (group 1, n = 16; group 2, n = 20). Female recipients in group 1 exhibited prolonged allograft function compared with group 2, after adjustment for confounders (odds ratio, 28.6; 95% CI, 1.3-619.1; P < 0.05).

CONCLUSION

Recipients of islets from at least 1 female donor exhibited prolonged graft survival compared with recipients of islets from exclusively male donors. In addition, female recipients exhibited prolonged survival compared with male recipients following ITx of at least 1 female donor.

Regenerative approaches to preserve pancreatic β-cell mass and function in diabetes pathogenesis

In both type 1 diabetes (T1D) and type 2 diabetes (T2D), there is a substantial β-cell mass loss. Residual β-cell mass is susceptible to cellular damage because of specific pancreatic β-cell characteristics. β cells have a low proliferation rate, being in human adults almost zero and a low antioxidant system that makes β cells susceptible to oxidative stress and increases their vulnerability to cell destruction. Different strategies have been addressed to preserve pancreatic β-cell residual mass and function in patients with diabetes. However, the effect of many compounds proposed in rodent models to trigger β-cell replication has different results in human β cells. In this review, scientific evidence of β-cell of two major regenerative approaches has been gathered. Regeneration proceedings for pancreatic β cells are promising and could improve β-cell proliferation capacity and contribute to the conservation of mature β-cell phenotypic characteristics. This evidence supports the notion that regenerative medicine could be a helpful strategy to yield amelioration of T1D and T2D pathogenesis.

Gonadal hormonal factors before menopause and incident type 2 diabetes in women: A 22-year follow-up of 83 799 women from the E3N cohort study

BACKGROUND

In many populations the incidence of type 2 diabetes is higher in men than in women. This may be explained by exposure to female gonadal hormones, but so far, there is no consensus on their role over the life course in type 2 diabetes etiology.

METHODS

Data are from 83 799 French women from the E3N (Etude Épidémiologique de Femmes de la Mutuelle Générale de l'Education Nationale) cohort study, followed for 22 years. Multivariable Cox models including classical risk factors were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) between gonadal hormonal factors and incident type 2 diabetes.

RESULTS

Older age at menarche, more menstrual cycles, older age at menopause, longer duration of exposure to gonadal hormones and breastfeeding were inversely associated with incident type 2 diabetes cases (n = 4806). While a longer duration of menstrual cycles (HR = 1.23 [95% CI: 1.07-1.41] comparing ≥32 vs ≤24 days) and use of contraceptive pills (HR = 1.33 [1.25-1.42]) were associated with a greater risk of type 2 diabetes.

CONCLUSIONS

In women, a longer exposure to endogenous gonadal hormones with a later menopause as well as breastfeeding were associated with a lower risk of developing type 2 diabetes, independently of classical diabetes risk factors. In contrast, the use of contraceptive agents was associated with incident diabetes, but the influence of each type of contraception and of exposure duration remain to be investigated.

The Role of Oxidative Stress in Pancreatic β Cell Dysfunction in Diabetes

Diabetes is a chronic metabolic disorder characterized by inappropriately elevated glucose levels as a result of impaired pancreatic β cell function and insulin resistance. Extensive studies have been conducted to elucidate the mechanism involved in the development of β cell failure and death under diabetic conditions such as hyperglycemia, hyperlipidemia, and inflammation. Of the plethora of proposed mechanisms, endoplasmic reticulum (ER) stress, mitochondrial dysfunction, and oxidative stress have been shown to play a central role in promoting β cell dysfunction. It has become more evident in recent years that these 3 factors are closely interrelated and importantly aggravate each other. Oxidative stress in particular is of great interest to β cell health and survival as it has been shown that β cells exhibit lower antioxidative capacity. Therefore, this review will focus on discussing factors that contribute to the development of oxidative stress in pancreatic β cells and explore the downstream effects of oxidative stress on β cell function and health. Furthermore, antioxidative capacity of β cells to counteract these effects will be discussed along with new approaches focused on preserving β cells under oxidative conditions.

Human and molecular genetics shed lights on fatty liver disease and diabetes conundrum

The causal role of abdominal overweight/obesity, insulin resistance and type 2 diabetes (T2D) on the risk of fatty liver disease (FLD) has robustly been proven. A consensus of experts has recently proposed the novel definition of 'metabolic dysfunction-associated fatty liver disease, MAFLD' instead of 'nonalcoholic fatty liver disease, NAFLD', emphasizing the central role of dysmetabolism in the disease pathogenesis. Conversely, a direct and independent contribution of FLD per se on risk of developing T2D is still a controversial topic. When dealing with FLD as a potential risk factor for T2D, it is straightforward to think of hepatic insulin resistance as the most relevant underlying mechanism. Emerging evidence supports genetic determinants of FLD (eg PNPLA3, TM6SF2, MBOAT7, GCKR, HSD17B13) as determinants of insulin resistance and T2D. However, recent studies highlighted that the key molecular mechanism of dysmetabolism is not fat accumulation per se but the degree of hepatic fibrosis (excess liver fat content-lipotoxicity), leading to reduced insulin clearance, insulin resistance and T2D. A consequence of these findings is that drugs that will ameliorate liver fat accumulation and fibrosis in principle may also exert a beneficial effect on insulin resistance and risk of T2D in individuals with FLD. Finally, initial findings show that these genetic factors might be directly implicated in modulating pancreatic beta-cell function, although future studies are needed to fully understand this relationship.

Sex Differences Across the Lifespan: A Focus on Cardiometabolism

Women's health and sex differences research remain understudied. In 2016, to address the topic of sex differences, the Center for Women' s Health Research (CWHR) at the University of Colorado (cwhr@ucdenver.edu) held its inaugural National Conference, "Sex Differences Across the Lifespan: A Focus on Metabolism" and published a report summarizing the presentations. Two years later, in 2018, CWHR organized the 2nd National Conference. The research presentations and discussions from the 2018 conference also addressed sex differences across the lifespan with a focus on cardiometabolism and expanded the focus by including circadian physiology and effects of sleep on cardiometabolic health. Over 100 participants, including basic scientists, clinicians, policymakers, advocacy group leaders, and federal agency leadership participated. The meeting proceedings reveal that although exciting advances in the area of sex differences have taken place, significant questions and gaps remain about women's health and sex differences in critical areas of health. Identifying these gaps and the subsequent research that will result may lead to important breakthroughs.

Amylin and Leptin interaction: Role During Pregnancy, Lactation and Neonatal Development

Amylin is co-secreted with insulin by pancreatic β-cells in response to a meal and produced by neurons in discrete hypothalamic brain areas. Leptin is proportionally secreted by the adipose tissue. Both hormones control food intake and energy homeostasis post-weaning in rodents. While amylin's main site of action is located in the area postrema (AP) and leptin's is located in the mediobasal hypothalamus, both hormones can also influence the other's signaling pathway; amylin has been shown enhance hypothalamic leptin signaling, and amylin signaling in the AP may rely on functional leptin receptors to modulate its effects. These two hormones also play major roles during other life periods. During pregnancy, leptin levels rise as a result of an increase in fat depot resulting in gestational leptin-resistance to prepare the maternal body for the metabolic needs during fetal development. The role of amylin is far less studied during pregnancy and lactation, though amylin levels seem to be elevated during pregnancy relative to insulin. Whether amylin and leptin interact during pregnancy and lactation remains to be assessed. Lastly, during brain development, amylin and leptin are major regulators of cell birth during embryogenesis and act as neurotrophic factors in the neonatal period. This review will highlight the role of amylin and leptin, and their possible interaction, during these dynamic time periods of pregnancy, lactation, and early development.

Hepatic enzyme ALT as a marker of glucose abnormality in men with cystic fibrosis

AIM

Cystic fibrosis (CF) patients are at high risk of developing CF-related diabetes (CFRD). In non-CF patients, liver disease, specifically steatosis and non-alcoholic fatty liver disease (NAFLD), is strongly associated with type 2 diabetes. We compared glycemic status and metabolic profiles in CF patients according to a biomarker of hepatic injury, alanine aminotransferase (ALT).

METHODS

We conducted a cross-sectional study among 273 adult CF patients recruited from the Montreal CF Cohort. A 2-hour oral glucose tolerance test (OGTT) was performed to collect glucose and insulin measures every 30 minutes. Fasting ALT levels and anthropometric measures were also obtained. Patients were categorized into 2 groups based on ALT cut-off of 25 U/L.

RESULTS

Patients in the high ALT group were mostly men (83%), had higher mean weight and BMI (p<0.001) and showed elevated glucose levels throughout OGTT (p≤0.01). When stratified by sex, only men with high ALT showed significantly higher weight (p<0.001), higher glycemic values at 60, 90 and 120 minutes of OGTT (p≤0.01), higher frequency of de novo CFRD (20.5% vs 8.2%, p = 0.04) as well as lower insulin sensitivity than men with normal ALT (p = 0.03). ALT levels were strongly associated with HOMA-IR in CFRD patients (p = 0.001, r2 = 0.28).

CONCLUSIONS

Adult CF men with higher ALT show an increased frequency of dysglycemia and de novo CFRD, lower insulin sensitivity and higher eight. Our data suggests that ALT levels could be an interesting tool to guide targeted diabetes screening, particularly among CF men. Prospective studies are needed to confirm these observations.

Sex Differences in Age-Associated Type 2 Diabetes in Rats-Role of Estrogens and Oxidative Stress

Females live longer than males, and the estrogens are one of the reasons for this difference. We reported some years ago that estrogens are able to protect rats against oxidative stress, by inducing antioxidant genes. Type 2 diabetes is an age-associated disease in which oxidative stress is involved, and moreover, some studies show that the prevalence is higher in men than in women, and therefore there are sex-associated differences. Thus, the aim of this study was to evaluate the role of estrogens in protecting against oxidative stress in type 2 diabetic males and females. For this purpose, we used Goto-Kakizaki rats, which develop type 2 diabetes with age. We found that female diabetic rats showed lower glycaemia levels with age than did diabetic males and that estrogens enhanced insulin sensitivity in diabetic females. Moreover, glucose uptake, measured by positron emission tomography, was higher in the female brain, cerebellum, and heart than in those from male diabetic rats. There were also sex-associated differences in the plasma metabolic profile as determined by metabolomics. The metabolic profile was similar between estrogen-replaced and control diabetic rats and different from ovariectomized diabetic rats. Oxidative stress is involved in these differences. We showed that hepatic mitochondria from females produced less hydrogen peroxide levels and exhibited lower xanthine oxidase activity. We also found that hepatic mitochondrial glutathione oxidation and lipid oxidation levels were lower in diabetic females when compared with diabetic males. Ovariectomy induced oxidative stress, and estrogen replacement therapy prevented it. These findings provide evidence for estrogen beneficial effects in type 2 diabetes and should be considered when prescribing estrogen replacement therapy to menopausal women.