Activation of ACE2/angiotensin (1-7) attenuates pancreatic β cell dedifferentiation in a high-fat-diet mouse model

The role of gut-islet axis in pancreatic islet function and glucose homeostasis

The gastrointestinal tract plays a vital role in the occurrence and treatment of metabolic diseases. Recent studies have convincingly demonstrated a bidirectional axis of communication between the gut and islets, enabling the gut to influence glucose metabolism and energy homeostasis in animals strongly. The 'gut-islet axis' is an essential endocrine signal axis that regulates islet function through the dialogue between intestinal microecology and endocrine metabolism. The discovery of glucagon-like peptide-1 (GLP-1), gastric inhibitory peptide (GIP) and other gut hormones has initially set up a bridge between gut and islet cells. However, the influence of other factors remains largely unknown, such as the homeostasis of the gut microbiota and the integrity of the gut barrier. Although gut microbiota primarily resides and affect intestinal function, they also affect extra-intestinal organs by absorbing and transferring metabolites derived from microorganisms. As a result of this transfer, islets may be continuously exposed to gut-derived metabolites and components. Changes in the composition of gut microbiota can damage the intestinal barrier function to varying degrees, resulting in increased intestinal permeability to bacteria and their derivatives. All these changes contribute to the severe disturbance of critical metabolic pathways in peripheral tissues and organs. In this review, we have outlined the different gut-islet axis signalling mechanisms associated with metabolism and summarized the latest progress in the complex signalling molecules of the gut and gut microbiota. In addition, we will discuss the impact of the gut renin-angiotensin system (RAS) on the various components of the gut-islet axis that regulate energy and glucose homeostasis. This work also indicates that therapeutic approaches aiming to restore gut microbial homeostasis, such as probiotics and faecal microbiota transplantation (FMT), have shown great potential in improving treatment outcomes, enhancing patient prognosis and slowing down disease progression. Future research should further uncover the molecular links between the gut-islet axis and the gut microbiota and explore individualized microbial treatment strategies, which will provide an innovative perspective and approach for the diagnosis and treatment of metabolic diseases.

Integrated analysis of genes shared between type 2 diabetes mellitus and osteoporosis

Background

The relationship between type 2 diabetes mellitus (T2DM) and osteoporosis (OP) has been widely recognized in recent years, but the mechanism of interaction remains unknown. The aim of this study was to investigate the genetic features and signaling pathways that are shared between T2DM and OP.

Methods

We analyzed the GSE76894 and GSE76895 datasets for T2DM and GSE56815 and GSE7429 for OP from the Gene Expression Omnibus (GEO) database to identify shared genes in T2DM and OP, and we constructed coexpression networks based on weighted gene coexpression network analysis (WGCNA). Shared genes were then further analyzed for functional pathway enrichment. We selected the best common biomarkers using the least absolute shrinkage and selection operator (LASSO) algorithm and validated the common biomarkers, followed by RT-PCR, immunofluorescence, Western blotting, and enzyme-linked immunosorbent assay (ELISA) to validate the expression of these hub genes in T2DM and OP mouse models and patients.

Results

We found 8,506 and 2,030 DEGs in T2DM and OP, respectively. Four modules were identified as significant for T2DM and OP using WGCNA. A total of 19 genes overlapped with the strongest positive and negative modules of T2DM and OP. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed these genes may be involved in pantothenate and CoA biosynthesis and the glycosaminoglycan biosynthesis-chondroitin sulfate/dermatan sulfate and renin-angiotensin system signaling pathway. The LASSO algorithm calculates the six optimal common biomarkers. RT-PCR results show that LTB, TPBG, and VNN1 were upregulated in T2DM and OP. Immunofluorescence and Western blot show that VNN1 is upregulated in the pancreas and bones of T2DM model mice and osteoporosis model mice. Similarly, the level of VNN1 in the sera of patients with T2DM, OP, and T2DM and OP was higher than that in the healthy group.

Conclusion

Based on the WGCNA and LASSO algorithms, we identified genes and pathways that were shared between T2DM and OP. Both pantothenate and CoA biosynthesis and the glycosaminoglycan biosynthesis-chondroitin sulfate/dermatan sulfate and renin-angiotensin systems may be associated with the pathogenesis of T2DM and OP. Moreover, VNN1 may be a potential diagnostic marker for patients with T2DM complicated by OP. This study provides a new perspective for the systematic study of possible mechanisms of combined OP and T2DM.

Small Intestinal Endocrine Cell Derived Exosomal ACE2 Protects Islet β-Cell Function by Inhibiting the Activation of NLRP3 Inflammasome and Reducing β-Cell Pyroptosis

Background

The "gut-islets axis" is an important endocrine signaling axis that regulates islets function by modulating the gut microbiota and endocrine metabolism within the gut. However, the specific mechanisms and roles of the intestine in islets regulation remain unclear. Recent studies investigated that exosomes derived from gut microbiota can transport signals to remotely regulate islets β-cell function, suggesting the possibility of novel signaling pathways mediated by gut exosomes in the regulation of the "gut-islet axis.".

Methods

The exosomes were isolated from the intestinal enteroendocrine cell-line STC-1cells culture supernatants treated with palmitate acid (PA) or BSA. Metabolic stress models were established by separately subjecting MIN6 cells to PA stimulation and feeding mice with a high-fat diet. Intervention with exosomes in vitro and in vivo to assess the biological effects of exosomes on islets β cells under metabolic stress. The Mas receptor antagonist A779 and ACE2ko mice were used to evaluate the role of exosomal ACE2.

Results

We found ACE2, a molecule that plays a crucial role in the regulation of islets function, is abundantly expressed in exosomes derived from STC-1 under physiological normal condition (NCEO). These exosomes cannot only be taken up by β-cells in vitro but also selectively transported to the islets in vivo. Following intervention with NCEXO, both Min6 cells in a lipotoxic environment and mice on a high-fat diet exhibited significant improvements in islets β-cell function and β-cell mass. Further investigations demonstrated that these protective effects are attributed to exosomal ACE2, as ACE2 inhibits NLRP3 inflammasome activation and reduces β-cell pyroptosis.

Conclusion

ACE2-enriched exosomes from the gut can selectively target islets, subsequently inhibiting NLRP3 inflammasome activation and β cell pyroptosis, thereby restoring islets β cell function under metabolic stress. This study provides novel insights into therapeutic strategies for the prevention and treatment of obesity and diabetes.

The Regulation Role of the Gut-Islets Axis in Diabetes

The gut-islets axis is an important endocrine signaling axis that regulates the function of islets by modulating the gut micro-environment and its endocrine metabolism. The discovery of intestinal hormones, such as GLP-1 and GIP, has established a preliminary link between the gut and the islet, paving the way for the development of GLP-1 receptor agonists based on the regulation theory of the gut-islets axis for diabetes treatment. This discovery has created a new paradigm for diabetes management and rapidly made the regulation theory of the gut-islets axis a focal point of research attention. Recent years, with in-depth study on gut microbiota and the discovery of intestinal-derived extracellular vesicles, the concept of gut endocrine and the regulation theory of the gut-islets axis have been further expanded and updated, offering tremendous research opportunities. The gut-islets axis refers to the complex interplay between the gut and the islet, which plays a crucial role in regulating glucose homeostasis and maintaining metabolic health. The axis involves various components, including gut microbiota, intestinal hormones, amino acids and ACE2, which contribute to the communication and coordination between the gut and the islet.

New Insights into the Effects of SARS-CoV-2 on Metabolic Organs: A Narrative Review of COVID-19 Induced Diabetes

Coronavirus disease 2019 (COVID-19)-induced new-onset diabetes has raised widespread concerns. Increased glucose concentration and insulin resistance levels were observed in the COVID-19 patients. COVID-19 patients with newly diagnosed diabetes may have worse clinical outcomes and can have serious consequences. The types and exact mechanisms of COVID-19-caused diabetes are not well understood. Understanding the direct effects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on pancreatic beta cells and insulin target metabolism organs, such as the liver, muscle, and adipose tissues, will provide new ideas for preventing and treating the new-onset diabetes induced by COVID-19.

Glucometabolic Perturbations in Type 2 Diabetes Mellitus and Coronavirus Disease 2019: Causes, Consequences, and How to Counter Them Using Novel Antidiabetic Drugs - The CAPISCO International Expert Panel

The growing amount of evidence suggests the existence of a bidirectional relation between coronavirus disease 2019 (COVID-19) and type 2 diabetes mellitus (T2DM), as these two conditions exacerbate each other, causing a significant healthcare and socioeconomic burden. The alterations in innate and adaptive cellular immunity, adipose tissue, alveolar and endothelial dysfunction, hypercoagulation, the propensity to an increased viral load, and chronic diabetic complications are all associated with glucometabolic perturbations of T2DM patients that predispose them to severe forms of COVID-19 and mortality. Severe acute respiratory syndrome coronavirus 2 infection negatively impacts glucose homeostasis due to its effects on insulin sensitivity and β-cell function, further aggravating the preexisting glucometabolic perturbations in individuals with T2DM. Thus, the most effective ways are urgently needed for countering these glucometabolic disturbances occurring during acute COVID-19 illness in T2DM patients. The novel classes of antidiabetic medications (dipeptidyl peptidase 4 inhibitors (DPP-4is), glucagon-like peptide-1 receptor agonists (GLP-1 RAs), and sodium-glucose co-transporter-2 inhibitors (SGLT-2is) are considered candidate drugs for this purpose. This review article summarizes current knowledge regarding glucometabolic disturbances during acute COVID-19 illness in T2DM patients and the potential ways to tackle them using novel antidiabetic medications. Recent observational data suggest that preadmission use of GLP-1 RAs and SGLT-2is are associated with decreased patient mortality, while DPP-4is is associated with increased in-hospital mortality of T2DM patients with COVID-19. Although these results provide further evidence for the widespread use of these two classes of medications in this COVID-19 era, dedicated randomized controlled trials analyzing the effects of in-hospital use of novel antidiabetic agents in T2DM patients with COVID-19 are needed.

Case report: Fulminant type 1 diabetes following paucisymptomatic SARS-CoV-2 infection during late pregnancy

Background

Dysregulation of glucose metabolism has been linked to SARS-CoV-2 infection. In addition, the occurrence of new onset diabetes mellitus, including fulminant type 1 diabetes, has been reported after SARS-CoV-2 infection or vaccination.

Methods and results

A young Chinese woman in her last trimester of pregnancy presented with an abrupt progression of hyperglycemia and ketoacidosis, but with a near-normal glycohemoglobin level following paucisymptomatic SARS-CoV-2 infection. The low C peptide levels, both fasting and postprandial, reflected profound insulin deficiency in the setting of negative islet autoantibody testing, consistent with a diagnosis of fulminant type 1 diabetes. Ketoacidosis and hyperglycemia quickly improved following the introduction of insulin therapy, but not the β cell function. The patient received treatment with insulin pump therapy after being discharged, and the first follow-up revealed a well-controlled glucose profile.

Conclusions

New-onset FT1D can occur after SARS-CoV-2 infection. Our report raises awareness of this rare but serious situation, promoting early recognition and management of FT1D during the COVID-19 pandemic.

Single-cell RNA sequencing combined with single-cell proteomics identifies the metabolic adaptation of islet cell subpopulations to high-fat diet in mice

AIMS/HYPOTHESIS

Islets have complex heterogeneity and subpopulations. Cell surface markers representing alpha, beta and delta cell subpopulations are urgently needed for investigations to explore the compositional changes of each subpopulation in obesity progress and diabetes onset, and the adaptation mechanism of islet metabolism induced by a high-fat diet (HFD).

METHODS

Single-cell RNA sequencing (scRNA-seq) was applied to identify alpha, beta and delta cell subpopulation markers in an HFD-induced mouse model of glucose intolerance. Flow cytometry and immunostaining were used to sort and assess the proportion of each subpopulation. Single-cell proteomics was performed on sorted cells, and the functional status of each alpha, beta and delta cell subpopulation in glucose intolerance was deeply elucidated based on protein expression.

RESULTS

A total of 33,999 cells were analysed by scRNA-seq and clustered into eight populations, including alpha, beta and delta cells. For alpha cells, scRNA-seq revealed that the Ace2^low subpopulation had downregulated expression of genes related to alpha cell function and upregulated expression of genes associated with beta cell characteristics in comparison with the Ace2^high subpopulation. The impaired function and increased fragility of ACE2^low alpha cells exposure to HFD was further suggested by single-cell proteomics. As for beta cells, the CD81^high subpopulation may indicate an immature signature of beta cells compared with the CD81^low subpopulation, which had robust function. We also found differential expression of Slc2a2 in delta cells and a potentially stronger cellular function and metabolism in GLUT2^low delta cells than GLUT2^high delta cells. Moreover, an increased proportion of ACE2^low alpha cells and CD81^low beta cells, with a constant proportion of GLUT2^low delta cells, were observed in HFD-induced glucose intolerance.

CONCLUSIONS/INTERPRETATION

We identified ACE2, CD81 and GLUT2 as surface markers to distinguish, respectively, alpha, beta and delta cell subpopulations with heterogeneous maturation and function. The changes in the proportion and functional status of islet endocrine subpopulations reflect the metabolic adaptation of islets to high-fat stress, which weakened the function of alpha cells and enhanced the function of beta and delta cells to bring about glycaemic homeostasis. Our findings provide a fundamental resource for exploring the mechanisms maintaining each islet endocrine subpopulation's fate and function in health and disease.

DATA AVAILABILITY

The scRNA-seq analysis datasets from the current study are available in the Gene Expression Omnibus (GEO) repository under the accession number GSE203376.

A Review on COVID-19: Primary Receptor, Endothelial Dysfunction, Related Comorbidities, and Therapeutics

Since December 2019, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused a global pandemic named coronavirus disease-19 (COVID-19) and resulted in a worldwide economic crisis. Utilizing the spike-like protein on its surface, the SARS-CoV-2 binds to the receptor angiotensin-converting enzyme 2 (ACE2), which highly expresses on the surface of many cell types. Given the crucial role of ACE2 in the renin–angiotensin system, its engagement by SARS-CoV-2 could potentially result in endothelial cell perturbation. This is supported by the observation that one of the most common consequences of COVID-19 infection is endothelial dysfunction and subsequent vascular damage. Furthermore, endothelial dysfunction is the shared denominator among previous comorbidities, including hypertension, kidney disease, cardiovascular diseases, etc., which are associated with an increased risk of severe disease and mortality in COVID-19 patients. Several vaccines and therapeutics have been developed and suggested for COVID-19 therapy. The present review summarizes the relationship between ACE2 and endothelial dysfunction and COVID-19, also reviews the most common comorbidities associated with COVID-19, and finally reviews several categories of potential therapies against COVID-19.

Exploring novel targets of sitagliptin for type 2 diabetes mellitus: Network pharmacology, molecular docking, molecular dynamics simulation, and SPR approaches

BACKGROUND

Diabetes has become a serious global public health problem. With the increasing prevalence of type 2 diabetes mellitus (T2DM), the incidence of complications of T2DM is also on the rise. Sitagliptin, as a targeted drug of DPP4, has good therapeutic effect for T2DM. It is well known that sitagliptin can specifically inhibit the activity of DPP4 to promote insulin secretion, inhibit islet β cell apoptosis and reduce blood glucose levels, while other pharmacological mechanisms are still unclear, such as improving insulin resistance, anti-inflammatory, anti-oxidative stress, and anti-fibrosis. The aim of this study was to explore novel targets and potential signaling pathways of sitagliptin for T2DM.

METHODS

Firstly, network pharmacology was applied to find the novel target most closely related to DPP4. Semi-flexible molecular docking was performed to confirm the binding ability between sitagliptin and the novel target, and molecular dynamics simulation (MD) was carried to verify the stability of the complex formed by sitagliptin and the novel target. Furthermore, surface-plasmon resonance (SPR) was used to explored the affinity and kinetic characteristics of sitagliptin with the novel target. Finally, the molecular mechanism of sitagliptin for T2DM was predicted by the enrichment analysis of GO function and KEGG pathway.

RESULTS

In this study, we found the cell surface receptor-angiotensin-converting enzyme 2 (ACE2) most closely related to DPP4. Then, we confirmed that sitagliptin had strong binding ability with ACE2 from a static perspective, and the stability of sitagliptin-ACE2 complex had better stability and longer binding time than BAR708-ACE2 in simulated aqueous solution within 50 ns. Significantly, we have demonstrated a strong affinity between sitagliptin and ACE2 on SPR biosensor, and their kinetic characteristics were "fast binding/fast dissociation". The guiding significance of clinical administration: low dose can reach saturation, but repeated administration was needed. Finally, there was certain relationship between COVID-19 and T2DM, and ACE2/Ang-(1-7)/Mas receptor (MasR) axis may be the important pathway of sitagliptin targeting ACE2 for T2DM.

CONCLUSION

This study used different methods to prove that ACE2 may be another novel target of sitagliptin for T2DM, which extended the application of ACE2 in improving diabetes mellitus.

Angiotensin-converting enzyme 2 improves hepatic insulin resistance by regulating GABAergic signaling in the liver

The angiotensin-converting enzyme 2 (ACE2)/angiotensin 1-7/MAS axis and the gamma-aminobutyric acid (GABA)ergic signaling system have both been shown to have the dual potential to improve insulin resistance (IR) and hepatic steatosis associated with obesity in the liver. Recent studies have demonstrated that ACE2 can regulate the GABA signal in various tissues. Notwithstanding this evidence, the functional relationship between ACE2 and GABA signal in the liver under IR remains elusive. Here, we used high-fat diet-induced models of IR in C57BL/6 mice as well as ACE2KO and adeno-associated virus-mediated ACE2 overexpression mouse models to address this knowledge gap. Our analysis showed that glutamate decarboxylase (GAD)67/GABA signaling was weakened in the liver during IR, whereas the expression of GAD67 and GABA decreased significantly in ACE2KO mice. Furthermore, exogenous administration of angiotensin 1-7 and adeno-associated virus- or lentivirus-mediated overexpression of ACE2 significantly increased hepatic GABA signaling in models of IR both in vivo and in vitro. We found that this treatment prevented lipid accumulation and promoted fatty acid β oxidation in hepatocytes as well as inhibited the expression of gluconeogenesis- and inflammation-related genes, which could be reversed by allylglycine, a specific GAD67 inhibitor. Collectively, our findings show that signaling via the ACE2/A1-7/MAS axis can improve hepatic IR by regulating hepatic GABA signaling. We propose that this research might indicate a potential strategy for the management of diabetes.

Changes of ACE2 in different glucose metabolites and its relationship with COVID-19

BACKGROUND

To study the changes and effects of angiotensin-converting enzyme 2 (ACE2)/angiotensin 1-7 (Ang1-7) and ACE/AngII in people with different glucose metabolisms and to explore the possible mechanisms underlying the severity of COVID-19 infection in diabetic patients.

METHODS

A total of 88 patients with type 2 diabetes, 72 patients with prediabetes (impaired fasting glucose, 30 patients; impaired glucose regulation, 42 patients), and 50 controls were selected. Changes and correlations of ACE2, Ang1-7 and other indicators were detected among the three groups. Patients were divided into four groups according to the course of diabetes: <1 year, 1-5 years, 5-10 years, and >10 years. ACE2 and Ang1-7 levels were compared and analyzed.

RESULTS

ACE2 and Ang1-7 increased with the severity of diabetes (P0 < .05 or P < .01). The levels of ACE2 and Ang1-7 in the longer course group were lower than those in the shorter course group, whereas the levels of ACE, Ang II, and interleukin-6 (IL-6) gradually increased (P < .05). Pearson correlation analysis showed that ACE2 was positively correlated with IL-6, FBG, and 2hPBG levels in the prediabetes group. In the diabetic group, ACE2 was positively correlated with Ang1-7 and negatively correlated with ACE, AngII, IL-6, and C-reactive protein levels. Multiple linear regression analysis showed that IL-6 and ACE were the main factors influencing ACE2 in the diabetic group.

CONCLUSION SUBSECTIONS

ACE2/Ang1-7 and ACE/AngII systems are activated, and inflammatory cytokine release increases in prediabetes. With the prolongation of the disease course, the effect of ACE2/Ang1-7 decreased gradually, while the effect of ACE/AngII increased significantly. Dysfunctions of ACE2/Ang1-7 may be one of the important mechanisms underlying the severity of COVID-19 infection in patients with diabetes.

Adipose Tissue Secretion Pattern Influences β-Cell Wellness in the Transition from Obesity to Type 2 Diabetes

The dysregulation of the β-cell functional mass, which is a reduction in the number of β-cells and their ability to secure adequate insulin secretion, represents a key mechanistic factor leading to the onset of type 2 diabetes (T2D). Obesity is recognised as a leading cause of β-cell loss and dysfunction and a risk factor for T2D. The natural history of β-cell failure in obesity-induced T2D can be divided into three steps: (1) β-cell compensatory hyperplasia and insulin hypersecretion, (2) insulin secretory dysfunction, and (3) loss of β-cell mass. Adipose tissue (AT) secretes many hormones/cytokines (adipokines) and fatty acids that can directly influence β-cell function and viability. As this secretory pattern is altered in obese and diabetic patients, it is expected that the cross-talk between AT and pancreatic β-cells could drive the maintenance of the β-cell integrity under physiological conditions and contribute to the reduction in the β-cell functional mass in a dysmetabolic state. In the current review, we summarise the evidence of the ability of the AT secretome to influence each step of β-cell failure, and attempt to draw a timeline of the alterations in the adipokine secretion pattern in the transition from obesity to T2D that reflects the progressive deterioration of the β-cell functional mass.

Association of ACE2 Polymorphisms and Derived Haplotypes With Obesity and Hyperlipidemia in Female Spanish Adolescents

Background

In the cardiovascular (CV) system, overactivation of the angiotensin converting enzyme (ACE) may trigger deleterious responses derived from angiotensin (Ang)-II, which can be attenuated by stimulation of ACE2 and subsequent Ang-(1-7) metabolite. However, ACE2 exhibits a high degree of genetic polymorphism that may affect its structure and stability, interfering with these cardioprotective actions. The aim of this study was to analyse the relationship of ACE2 polymorphisms with cardiovascular risk factors in children.

Methodology

Five ACE2-single nucleotide polymorphisms (SNP), rs4646188, rs2158083, rs233575, rs879922, and rs2074192, previously related to CV risk factors, were analyzed in a representative sample of 12–16-year-old children and tested for their potential association with anthropometric parameters, insulin levels and the lipid profile.

Results

Girls (N = 461) exhibited lower rates of overweight, obesity, blood pressure, and glycemia than boys (N = 412), though increased plasma lipids. The triglycerides (TG)/HDL-C ratio was, however, lower in females. Interestingly, only in girls, the occurrence of overweight/obesity was associated with the SNPs rs879922 [OR 1.67 (1.02–2.75)], rs233575 [OR 1.98 (1.21- 3.22)] and rs2158083 [OR 1.67 (1.04–2.68)]. Also, TG levels were linked to the rs879922, rs233575, and rs2158083 SNPs, and the TG/HDL-C ratio was associated with rs879922 and rs233575. Levels of TC and LDL-C were associated with rs2074192 and rs2158083. Furthermore, the established cut-off level for TG ≥ 90 mg/dL was related to rs879922 [OR 1.78 (1.06–2.96)], rs2158083 [OR 1.75 (1.08–2.82)], and rs233575 [OR 1.62 (1.00–2.61)]. The cut-off level for TC ≥ 170 mg/dL was associated with rs2074192 OR 1.54 (1.04–2.28) and rs2158083 [OR 1.53 (1.04–2.25)]. Additionally, the haplotype (C-G-C) derived from rs879922-rs2158083-rs233575 was related to higher prevalence of overweight/obesity and TG elevation.

Conclusion

The expression and activity of ACE2 may be essential for CV homeostasis. Interestingly, the ACE2-SNPs rs879922, rs233575, rs2158083 and rs2074192, and the haplotype (C-G-C) of the three former could induce vulnerability to obesity and hyperlipidemia in women. Thus, these SNPs might be used as predictive biomarkers for CV diseases and as molecular targets for CV therapy.

An insight into the mechanisms of COVID-19, SARS-CoV2 infection severity concerning β-cell survival and cardiovascular conditions in diabetic patients

A significantly high percentage of hospitalized COVID-19 patients with diabetes mellitus (DM) had severe conditions and were admitted to ICU. In this review, we have delineated the plausible molecular mechanisms that could explain why there are increased clinical complications in patients with DM that become critically ill when infected with SARS-CoV2. RNA viruses have been classically implicated in manifestation of new onset diabetes. SARS-CoV2 infection through cytokine storm leads to elevated levels of pro-inflammatory cytokines creating an imbalance in the functioning of T helper cells affecting multiple organs. Inflammation and Th1/Th2 cell imbalance along with Th17 have been associated with DM, which can exacerbate SARS-CoV2 infection severity. ACE-2-Ang-(1-7)-Mas axis positively modulates β-cell and cardiac tissue function and survival. However, ACE-2 receptors dock SARS-CoV2, which internalize and deplete ACE-2 and activate Renin-angiotensin system (RAS) pathway. This induces inflammation promoting insulin resistance that has positive effect on RAS pathway, causes β-cell dysfunction, promotes inflammation and increases the risk of cardiovascular complications. Further, hyperglycemic state could upregulate ACE-2 receptors for viral infection thereby increasing the severity of the diabetic condition. SARS-CoV2 infection in diabetic patients with heart conditions are linked to worse outcomes. SARS-CoV2 can directly affect cardiac tissue or inflammatory response during diabetic condition and worsen the underlying heart conditions.

Imatinib and methazolamide ameliorate COVID-19-induced metabolic complications via elevating ACE2 enzymatic activity and inhibiting viral entry

Coronavirus disease 2019 (COVID-19) represents a systemic disease that may cause severe metabolic complications in multiple tissues including liver, kidney, and cardiovascular system. However, the underlying mechanisms and optimal treatment remain elusive. Our study shows that impairment of ACE2 pathway is a key factor linking virus infection to its secondary metabolic sequelae. By using structure-based high-throughput virtual screening and connectivity map database, followed with experimental validations, we identify imatinib, methazolamide, and harpagoside as direct enzymatic activators of ACE2. Imatinib and methazolamide remarkably improve metabolic perturbations in vivo in an ACE2-dependent manner under the insulin-resistant state and SARS-CoV-2-infected state. Moreover, viral entry is directly inhibited by these three compounds due to allosteric inhibition of ACE2 binding to spike protein on SARS-CoV-2. Taken together, our study shows that enzymatic activation of ACE2 via imatinib, methazolamide, or harpagoside may be a conceptually new strategy to treat metabolic sequelae of COVID-19.

Diabetes and COVID-19; A Bidirectional Interplay

There seems to be a bidirectional interplay between Diabetes mellitus (DM) and coronavirus disease 2019 (COVID-19). On the one hand, people with diabetes are at higher risk of fatal or critical care unit-treated COVID-19 as well as COVID-19 related health complications compared to individuals without diabetes. On the other hand, clinical data so far suggest that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may result in metabolic dysregulation and in impaired glucose homeostasis. In addition, emerging data on new onset DM in previously infected with SARS-CoV-2 patients, reinforce the hypothesis of a direct effect of SARS-CoV-2 on glucose metabolism. Attempting to find the culprit, we currently know that the pancreas and the endothelium have been found to express Angiotensin-converting enzyme 2 (ACE2) receptors, the main binding site of the virus. To move from bench to bedside, understanding the effects of COVID-19 on metabolism and glucose homeostasis is crucial to prevent and manage complications related to COVID-19 and support recovering patients. In this article we review the potential underlying pathophysiological mechanisms between COVID-19 and glucose dysregulation as well as the effects of antidiabetic treatment in patients with diabetes and COVID-19.

Children With Short Stature Display Reduced ACE2 Expression in Peripheral Blood Mononuclear Cells

BACKGROUND

The cause of short stature remains often unknown. The renin-angiotensin system contributes to growth regulation. Several groups reported that angiotensin-converting enzyme 2 (ACE2)-knockout mice weighed less than controls. Our case-control study aimed to investigate if children with short stature had reduced ACE2 expression as compared to controls, and its significance.

MATERIALS AND METHODS

children aged between 2 and 14 years were consecutively recruited in a University Hospital pediatric tertiary care center. Cases were children with short stature defined as height SD ≤ -2 diagnosed with growth hormone deficiency (GHD) or idiopathic short stature (ISS), before any treatment. Exclusion criteria were: acute diseases, kidney disease, endocrine or autoimmune disorders, precocious puberty, genetic syndromes, SGA history. ACE and ACE2 expression were measured in peripheral blood mononuclear cells, angiotensins were measured by ELISA.

RESULTS

Children with short stature displayed significantly lower ACE2 expression, being 0.40 fold induction (0.01-2.27) as compared to controls, and higher ACE/ACE2, with no differences between GHD and ISS. ACE2 expression was significantly and inversely associated with the risk of short stature, OR 0.26 (0.07-0.82), and it had a moderate accuracy to predict it, with an AUC of 0.73 (0.61-0.84). The cutoff of 0.45 fold induction of ACE2 expression was the value best predicting short stature, identifying correctly 70% of the children.

CONCLUSIONS

Our study confirms the association between the reduction of ACE2 expression and growth retardation. Further studies are needed to determine its diagnostic implications.

The role of laboratory biomarkers in diagnostics and management of COVID-19 patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of a highly transmittable and heterogenic infection of the respiratory tract, characterized by a broad spectrum of clinical manifestations with a different degree of severity. Medical laboratories play an important role in early diagnosis and management of Coronavirus Disease 2019 (COVID-19) patients. Indeed, the results of several laboratory tests are essential for assessing the severity of the disease, selecting appropriate therapeutic procedures and monitoring treatment response. Routine laboratory testing in COVID-19 patients includes biomarkers of acute phase reaction, hematological and biochemical parameters that indicate tissue injury. The aim of this review paper is to describe the role of these biomarkers in the diagnostics and management of adult and pediatric COVID-19 patients.

ACE2 function in the pancreatic islet: Implications for relationship between SARS-CoV-2 and diabetes

The molecular link between SARS-CoV-2 infection and susceptibility is not well understood. Nonetheless, a bi-directional relationship between SARS-CoV-2 and diabetes has been proposed. The angiotensin-converting enzyme 2 (ACE2) is considered as the primary protein facilitating SARS-CoV and SARS-CoV-2 attachment and entry into the host cells. Studies suggested that ACE2 is expressed in the endocrine cells of the pancreas including beta cells, in addition to the lungs and other organs; however, its expression in the islets, particularly beta cells, has been met with some contradiction. Importantly, ACE2 plays a crucial role in glucose homoeostasis and insulin secretion by regulating beta cell physiology. Given the ability of SARS-CoV-2 to infect human pluripotent stem cell-derived pancreatic cells in vitro and the presence of SARS-CoV-2 in pancreatic samples from COVID-19 patients strongly hints that SARS-CoV-2 can invade the pancreas and directly cause pancreatic injury and diabetes. However, more studies are required to dissect the underpinning molecular mechanisms triggered in SARS-CoV-2-infected islets that lead to aggravation of diabetes. Regardless, it is important to understand the function of ACE2 in the pancreatic islets to design relevant therapeutic interventions in combatting the effects of SARS-CoV-2 on diabetes pathophysiology. Herein, we detail the function of ACE2 in pancreatic beta cells crucial for regulating insulin sensitivity, secretion, and glucose metabolism. Also, we discuss the potential role played by ACE2 in aiding SARS-COV-2 entry into the pancreas and the possibility of ACE2 cooperation with alternative entry factors as well as how that may be linked to diabetes pathogenesis.

Early and late endocrine complications of COVID-19

Endocrine system plays a vital role in controlling human homeostasis. Understanding the possible effects of COVID-19 on endocrine glands is crucial to prevent and manage endocrine disorders before and during hospitalization in COVID-19-infected patients as well as to follow them up properly upon recovery. Many endocrine glands such as pancreas, hypothalamus and pituitary, thyroid, adrenal glands, testes, and ovaries have been found to express angiotensin-converting enzyme 2 receptors, the main binding site of the virus. Since the pandemic outbreak, various publications focus on the aggravation of preexisting endocrine diseases by COVID-19 infection or the adverse prognosis of the disease in endocrine patients. However, data on endocrine disorders both during the phase of the infection (early complications) and upon recovery (late complications) are scarce. The aim of this review is to identify and discuss early and late endocrine complications of COVID-19. The majority of the available data refer to glucose dysregulation and its reciprocal effect on COVID-19 infection with the main interest focusing on the presentation of new onset of diabetes mellitus. Thyroid dysfunction with low triiodothyronine, low thyroid stimulating hormone, or subacute thyroiditis has been reported. Adrenal dysregulation and impaired spermatogenesis in affected men have been also reported. Complications of other endocrine glands are still not clear. Considering the recent onset of COVID-19 infection, the available follow-up data are limited, and therefore, long-term studies are required to evaluate certain effects of COVID-19 on the endocrine glands.

Early and late endocrine complications of COVID-19

Endocrine system plays a vital role in controlling human homeostasis. Understanding the possible effects of COVID-19 on endocrine glands is crucial to prevent and manage endocrine disorders before and during hospitalization in COVID-19-infected patients as well as to follow them up properly upon recovery. Many endocrine glands such as pancreas, hypothalamus and pituitary, thyroid, adrenal glands, testes, and ovaries have been found to express angiotensin-converting enzyme 2 receptors, the main binding site of the virus. Since the pandemic outbreak, various publications focus on the aggravation of preexisting endocrine diseases by COVID-19 infection or the adverse prognosis of the disease in endocrine patients. However, data on endocrine disorders both during the phase of the infection (early complications) and upon recovery (late complications) are scarce. The aim of this review is to identify and discuss early and late endocrine complications of COVID-19. The majority of the available data refer to glucose dysregulation and its reciprocal effect on COVID-19 infection with the main interest focusing on the presentation of new onset of diabetes mellitus. Thyroid dysfunction with low triiodothyronine, low thyroid stimulating hormone, or subacute thyroiditis has been reported. Adrenal dysregulation and impaired spermatogenesis in affected men have been also reported. Complications of other endocrine glands are still not clear. Considering the recent onset of COVID-19 infection, the available follow-up data are limited, and therefore, long-term studies are required to evaluate certain effects of COVID-19 on the endocrine glands.

Expression of SARS-CoV-2 receptor "ACE2" in human pancreatic β cells: to be or not to be!

The current COVID-19 pandemic, which continues to spread across the globe, is caused by severe acute respiratory syndrome coronavirus (SARS-Cov-2). Soon after the pandemic emerged in China, it became clear that the receptor-binding domain (RBD) of angiotensin-converting enzyme 2 (ACE2) serves as the primary cell surface receptor for SARS-Cov-2. Subsequent work has shown that diabetes and hyperglycemia are major risk factors for morbidity and mortality in COVID-19 patients. However, data on the pattern of expression of ACE2 on human pancreatic β cells remain contradictory. Additionally, there is no consensus on whether the virus can directly infect and damage pancreatic islets and hence exacerbate diabetes. In this mini-review, we highlight the role of ACE2 receptor and summarize the current state of knowledge regarding its expression/co-localization in human pancreatic endocrine cells. We also discuss recent data on the permissiveness of human pancreatic β cells to SARS-Cov-2 infection.

Mesenchymal stem cell-derived exosomal miR-146a reverses diabetic β-cell dedifferentiation

Background

Mesenchymal stem cells (MSCs) show promising therapeutic potential in treating type 2 diabetes mellitus (T2DM) in clinical studies. Accumulating evidence has suggested that the therapeutic effects of MSCs are not due to their direct differentiation into functional β-cells but are instead mediated by their paracrine functions. Among them, exosomes, nano-sized extracellular vesicles, are important substances that exert paracrine functions. However, the underlying mechanisms of exosomes in ameliorating T2DM remain largely unknown.

Methods

Bone marrow mesenchymal stem cell (bmMSC)-derived exosomes (bmMDEs) were administrated to T2DM rats and high-glucose-treated primary islets in order to detect their effects on β-cell dedifferentiation. Differential miRNAs were then screened via miRNA sequencing, and miR-146a was isolated after functional verification. TargetScan, reporter gene detection, insulin secretion assays, and qPCR validation were used to predict downstream target genes and involved signaling pathways of miR-146a.

Results

Our results showed that bmMDEs reversed diabetic β-cell dedifferentiation and improved β-cell insulin secretion both in vitro and in vivo. Results of miRNA sequencing in bmMDEs and subsequent functional screening demonstrated that miR-146a, a highly conserved miRNA, improved β-cell function. We further found that miR-146a directly targeted Numb, a membrane-bound protein involved in cell fate determination, leading to activation of β-catenin signaling in β-cells. Exosomes derived from miR-146a-knockdown bmMSCs lost the ability to improve β-cell function.

Conclusions

These findings demonstrate that bmMSC-derived exosomal miR-146a protects against diabetic β-cell dysfunction by acting on the NUMB/β-catenin signaling pathway, which may represent a novel therapeutic strategy for T2DM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02371-0.

Berberine Reshapes the Balance of the Local Renin-Angiotensin System by Modulating Autophagy under Metabolic Stress in Pancreatic Islets

Results

Prolonged exposure to palmitate increased the expression of ACE and AngII type 1 receptor (ATR1) and decreased the ACE2 expression, which was partly offset by berberine. In ob/ob mice, berberine increased in tolerance to glucose, improved abnormal β-cell and α-cell distributions, upregulated ACE2 expression, and decreased autophagosomes and the expression of LC3 and SQSTM1/p62. Autophagosomes and expression of LC3 and SQSTM1/p62 were increased in ACE2KO mice.

Conclusions

We demonstrated that berberine may improve the pancreatic islet function by regulating local RAS-mediated autophagy under metabolic stress.

Factors Behind the Higher COVID-19 Risk in Diabetes: A Critical Review

Diabetes mellitus (DM) and coronavirus disease 2019 (COVID-19) are public health issues worldwide, and their comorbidities trigger the progress to severe disease and even death in such patients. Globally, DM has affected an estimated 9.3% adults, and as of April 18, 2021, the World Health Organization (WHO) has confirmed 141,727,940 COVID-19 confirmed cases. The virus is spread via droplets, aerosols, and direct touch with others. Numerous predictive factors have been linked to COVID-19 severity, including impaired immune response and increased inflammatory response, among others. Angiotensin receptor blockers and angiotensin converting enzyme 2 have also been identified as playing a boosting role in both susceptibility and severity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Specifically, in DM patients, both their control and management during this pandemic is herculean as the restriction periods have markedly hampered the maintenance of means to control glycemia, hypertension, and neuroendocrine and kidney diseases. In addition, as a result of the underlyin cardio-metabolic and immunological disorders, DM patients are at a higher risk of developing the severe form of COVID-19 despite other comorbidities, such as hypertension, also potentially boosting the development of higher COVID-19 severity. However, even in non-DM patients, SARS-CoV-2 may also cause transient hyperglycemia through induction of insulin resistance and/or pancreatic β-cell injury. Therefore, a strict glucose monitoring of DM patients with COVID-19 is mandatory to prevent life-threatening complications.

SARS-CoV-2 Host Receptor ACE2 Protein Expression Atlas in Human Gastrointestinal Tract

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects host cells through interactions with its receptor, Angiotensin-converting enzyme 2 (ACE2), causing severe acute respiratory syndrome and death in a considerable proportion of people. Patients infected with SARS-CoV-2 experience digestive symptoms. However, the precise protein expression atlas of ACE2 in the gastrointestinal tract remains unclear. In this study, we aimed to explore the ACE2 protein expression pattern and the underlying function of ACE2 in the gastrointestinal tract, including the colon, stomach, liver, and pancreas.

Methods

We measured the protein expression of ACE2 in the gastrointestinal tract using immunohistochemical (IHC) staining with an ACE2-specific antibody of paraffin-embedded colon, stomach, liver, and pancreatic tissues. The correlation between the protein expression of ACE2 and the prognosis of patients with gastrointestinal cancers was analyzed by the log-rank (Mantel–Cox) test. The influence of ACE2 on colon, stomach, liver, and pancreatic tumor cell line proliferation was tested using a Cell Counting Kit 8 (CCK-8) assay.

Results

ACE2 presented heterogeneous expression patterns in the gastrointestinal tract, and it showed a punctate distribution in hepatic cells. Compared to that in parallel adjacent non-tumor tissues, the protein expression of ACE2 was significantly increased in colon cancer, stomach cancer, and pancreatic cancer tissues but dramatically decreased in liver cancer tissues. However, the expression level of the ACE2 protein was not correlated with the survival of patients with gastrointestinal cancers. Consistently, ACE2 did not affect the proliferation of gastrointestinal cancer cells in vitro.

Conclusion

The ACE2 protein is widely expressed in the gastrointestinal tract, and its expression is significantly altered in gastrointestinal tumor tissues. ACE2 is not an independent prognostic marker of gastrointestinal cancers.

Dysregulation of the Pdx1/Ovol2/Zeb2 axis in dedifferentiated β-cells triggers the induction of genes associated with epithelial-mesenchymal transition in diabetes

OBJECTIVE

β-cell dedifferentiation has been revealed as a pathological mechanism underlying pancreatic dysfunction in diabetes. We previously showed that increased miR-7 levels trigger β-cell dedifferentiation and diabetes. We used β-cell-specific miR-7 overexpressing mice (Tg7) to test the hypothesis that loss of β-cell identity triggered by miR-7 overexpression alters islet gene expression and islet microenvironment in diabetes.

METHODS

We performed bulk and single-cell RNA sequencing (RNA-seq) in islets obtained from β-cell-specific miR-7 overexpressing mice (Tg7). We carried out loss- and gain-of-function experiments in MIN6 and EndoC-bH1 cell lines. We analysed previously published mouse and human T2D data sets.

RESULTS

Bulk RNA-seq revealed that β-cell dedifferentiation is associated with the induction of genes associated with epithelial-to-mesenchymal transition (EMT) in prediabetic (2-week-old) and diabetic (12-week-old) Tg7 mice. Single-cell RNA-seq (scRNA-seq) indicated that this EMT signature is enriched specifically in β-cells. These molecular changes are associated with a weakening of β-cell: β-cell contacts, increased extracellular matrix (ECM) deposition, and TGFβ-dependent islet fibrosis. We found that the mesenchymal reprogramming of β-cells is explained in part by the downregulation of Pdx1 and its inability to regulate a myriad of epithelial-specific genes expressed in β-cells. Notable among genes transactivated by Pdx1 is Ovol2, which encodes a transcriptional repressor of the EMT transcription factor Zeb2. Following compromised β-cell identity, the reduction in Pdx1 gene expression causes a decrease in Ovol2 protein, triggering mesenchymal reprogramming of β-cells through the induction of Zeb2. We provided evidence that EMT signalling associated with the upregulation of Zeb2 expression is a molecular feature of islets in T2D subjects.

CONCLUSIONS

Our study indicates that miR-7-mediated β-cell dedifferentiation induces EMT signalling and a chronic response to tissue injury, which alters the islet microenvironment and predisposes to fibrosis. This research suggests that regulators of EMT signalling may represent novel therapeutic targets for treating β-cell dysfunction and fibrosis in T2D.

COVID-19 May Increase the Risk of Insulin Resistance in Adult Patients Without Diabetes: A 6-Month Prospective Study

OBJECTIVE

During the coronavirus disease 2019 (COVID-19) pandemic, exploring insulin resistance and beta-cell activity is important for understanding COVID-19‒associated new-onset diabetes. We assessed insulin sensitivity and fasting insulin secretion in patients with COVID-19 without diabetes on admission and at 3 and 6 months after discharge.

METHODS

This 6-month prospective study assessed data from the records of 64 patients without diabetes diagnosed with COVID-19 at Wenzhou Central Hospital, China. Each patient was followed up at 3 and 6 months after discharge. Repeated measures analysis of variance was used to investigate differences in multiple measurements of the same variable at different times. Linear regression analysis was performed to analyze the contributor for changes in the triglyceride-glucose (TyG) index.

RESULTS

Fasting C-peptide levels in patients at baseline were lower than the normal range. Compared with the baseline results, patients had significantly elevated fasting C-peptide levels (0.35 ± 0.24 vs 2.36 ± 0.98 vs 2.52 ± 1.11 μg/L; P < .001), homeostasis model assessment for beta-cell function (0.42, interquartile range [IQR] 0.36-0.62 vs 2.54, IQR 1.95-3.42 vs 2.90, IQR 2.02-4.23; P < .001), and TyG indices (8.57 ± 0.47 vs 8.73 ± 0.60 vs 8.82 ± 0.62; P = .006) and decreased fasting glucose levels (5.84 ± 1.21 vs 4.95 ± 0.76 vs 5.40 ± 0.68 mmol/L; P = .003) at the 3- and 6-month follow-up. Male gender, age, interferon-alfa treatment during hospitalization, and changes in total cholesterol and high-density lipoprotein levels were significantly associated with changes in the TyG index.

CONCLUSION

Our study provided the first evidence that COVID-19 may increase the risk of insulin resistance in patients without diabetes.

The Plasticity of Pancreatic β-Cells

Type 2 diabetes is caused by impaired insulin secretion and/or insulin resistance. Loss of pancreatic β-cell mass detected in human diabetic patients has been considered to be a major cause of impaired insulin secretion. Additionally, apoptosis is found in pancreatic β-cells; β-cell mass loss is induced when cell death exceeds proliferation. Recently, however, β-cell dedifferentiation to pancreatic endocrine progenitor cells and β-cell transdifferentiation to α-cell was reported in human islets, which led to a new underlying molecular mechanism. Hyperglycemia inhibits nuclear translocation and expression of forkhead box-O1 (FoxO1) and induces the expression of neurogenin-3 (Ngn3), which is required for the development and maintenance of pancreatic endocrine progenitor cells. This new hypothesis (Foxology) is attracting attention because it explains molecular mechanism(s) underlying β-cell plasticity. The lineage tracing technique revealed that the contribution of dedifferentiation is higher than that of β-cell apoptosis retaining to β-cell mass loss. In addition, islet cells transdifferentiate each other, such as transdifferentiation of pancreatic β-cell to α-cell and vice versa. Islet cells can exhibit plasticity, and they may have the ability to redifferentiate into any cell type. This review describes recent findings in the dedifferentiation and transdifferentiation of β-cells. We outline novel treatment(s) for diabetes targeting islet cell plasticity.

ACE2 and energy metabolism: the connection between COVID-19 and chronic metabolic disorders

The renin-angiotensin system (RAS) has currently attracted increasing attention due to its potential function in regulating energy homeostasis, other than the actions on cellular growth, blood pressure, fluid, and electrolyte balance. The existence of RAS is well established in metabolic organs, including pancreas, liver, skeletal muscle, and adipose tissue, where activation of angiotensin-converting enzyme (ACE) - angiotensin II pathway contributes to the impairment of insulin secretion, glucose transport, fat distribution, and adipokines production. However, the activation of angiotensin-converting enzyme 2 (ACE2) - angiotensin (1-7) pathway, a novel branch of the RAS, plays an opposite role in the ACE pathway, which could reverse these consequences by improving local microcirculation, inflammation, stress state, structure remolding, and insulin signaling pathway. In addition, new studies indicate the protective RAS arm possesses extraordinary ability to enhance brown adipose tissue (BAT) activity and induces browning of white adipose tissue, and consequently, it leads to increased energy expenditure in the form of heat instead of ATP synthesis. Interestingly, ACE2 is the receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is threating public health worldwide. The main complications of SARS-CoV-2 infected death patients include many energy metabolism-related chronic diseases, such as diabetes. The specific mechanism leading to this phenomenon is largely unknown. Here, we summarize the latest pharmacological and genetic tools on regulating ACE/ACE2 balance and highlight the beneficial effects of the ACE2 pathway axis hyperactivity on glycolipid metabolism, as well as the thermogenic modulation.

Novel Molecular Evidence Related to COVID-19 in Patients with Diabetes Mellitus

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly evolved into a global pandemic. The hyperglycemia in patients with diabetes mellitus (DM) substantially compromises their innate immune system. SARS-CoV-2 uses human angiotensin-converting enzyme 2 (ACE2) receptors to enter the affected cell. Uncontrolled hyperglycemia-induced glycosylation of ACE2 and the S protein of SARS-CoV-2 could facilitate the binding of S protein to ACE2, enabling viral entry. Downregulation of ACE2 activity secondary to SARS-CoV-2 infection, with consequent accumulation of angiotensin II and metabolites, eventually leads to poor outcomes. The altered binding of ACE2 with SARS-CoV-2 and the compromised innate immunity of patients with DM increase their susceptibility to COVID-19; COVID-19 induces pancreatic β-cell injury and poor glycemic control, which further compromises the immune response and aggravates hyperglycemia and COVID-19 progression, forming a vicious cycle. Sequential cleavage of viral S protein by furin and transmembrane serine protease 2 (TMPRSS2) triggers viral entry to release the viral genome into the target cell. Hence, TMPRSS2 and furin are possible drug targets. As type 1 DM exhibits a Th1-driven autoimmune process, the relatively lower mortality of COVID-19 in type 1 DM compared to type 2 DM might be attributed to an imbalance between Th1 and Th2 immunity. The anti-inflammatory effects of dipeptidyl peptidase-4 inhibitor may benefit patients with DM and COVID-19. The potential protective effects of sodium-glucose cotransporter-2 inhibitor (SGLT2i), including reduction in lactate level, prevention of lowering of cytosolic pH and reduction in pro-inflammatory cytokine levels may justify the provision of SGLT2i to patients with DM and mild or asymptomatic COVID-19. For patients with DM and COVID-19 who require hospitalization, insulin-based treatment is recommended with cessation of metformin and SGLT2i. Further evidence from randomized or case-control clinical trials is necessary to elucidate the effectiveness and pitfalls of different types of medication for DM.

Body Localization of ACE-2: On the Trail of the Keyhole of SARS-CoV-2

The explosion of the new coronavirus (SARS-CoV-2) pandemic has brought the role of the angiotensin converting enzyme 2 (ACE2) back into the scientific limelight. Since SARS-CoV-2 must bind the ACE2 for entering the host cells in humans, its expression and body localization are critical to track the potential target organ of this infection and to outline disease progression and clinical outcomes. Here, we mapped the physiological body distribution, expression, and activities of ACE2 and discussed its potential correlations and mutal interactions with the disparate symptoms present in SARS-CoV-2 patients at the level of different organs. We highlighted that despite during SARS-CoV-2 infection ACE2-expressing organs may become direct targets, leading to severe pathological manifestations, and subsequent multiple organ failures, the exact mechanism and the potential interactions through which ACE2 acts in these organs is still heavily debated. Further scientific efforts, also considering a personalized approach aimed to consider specific patient differences in the mutual interactions ACE2-SARS-CoV-2 and the long-term health effects associated with COVID-19 are currently mandatory.

The impact of type 2 diabetes and its management on the prognosis of patients with severe COVID-19

BACKGROUND

Although type 2 diabetes mellitus (T2DM) patients with coronavirus disease 2019 (COVID-19) develop a more severe condition compared to those without diabetes, the mechanisms for this are unknown. Moreover, the impact of treatment with antihyperglycemic drugs and glucocorticoids is unclear.

METHODS

From 1584 COVID-19 patients, 364 severe/critical COVID-19 patients with clinical outcome were enrolled for the final analysis, and patients without preexisting T2DM but elevated glucose levels were excluded. Epidemiological data were obtained and clinical status evaluation carried out to assess the impact of T2DM and its management on clinical outcomes.

RESULTS

Of 364 enrolled severe COVID-19 inpatients, 114 (31.3%) had a history of T2DM. Twenty-seven (23.7%) T2DM patients died, who had more severe inflammation, coagulation activation, myocardia injury, hepatic injury, and kidney injury compared with non-DM patients. In severe COVID-19 patients with T2DM, we demonstrated a higher risk of all-cause fatality with glucocorticoid treatment (adjusted hazard ratio [HR], 3.61; 95% CI, 1.14-11.46; P = .029) and severe hyperglycemia (fasting plasma glucose ≥11.1 mmol/L; adjusted HR, 11.86; 95% CI, 1.21-116.44; P = .034).

CONCLUSIONS

T2DM status aggravated the clinical condition of COVID-19 patients and increased their critical illness risk. Poor fasting blood glucose (≥ 11.1 mmol/L) and glucocorticoid treatment are associated with poor prognosis for T2DM patients with severe COVID-19.

SARS-CoV-2 Receptor Angiotensin I-Converting Enzyme Type 2 (ACE2) Is Expressed in Human Pancreatic β-Cells and in the Human Pancreas Microvasculature

Increasing evidence demonstrated that the expression of Angiotensin I-Converting Enzyme type 2 (ACE2) is a necessary step for SARS-CoV-2 infection permissiveness. In light of the recent data highlighting an association between COVID-19 and diabetes, a detailed analysis aimed at evaluating ACE2 expression pattern distribution in human pancreas is still lacking. Here, we took advantage of INNODIA network EUnPOD biobank collection to thoroughly analyze ACE2, both at mRNA and protein level, in multiple human pancreatic tissues and using several methodologies. Using multiple reagents and antibodies, we showed that ACE2 is expressed in human pancreatic islets, where it is preferentially expressed in subsets of insulin producing β-cells. ACE2 is also highly expressed in pancreas microvasculature pericytes and moderately expressed in rare scattered ductal cells. By using different ACE2 antibodies we showed that a recently described short-ACE2 isoform is also prevalently expressed in human β-cells. Finally, using RT-qPCR, RNA-seq and High-Content imaging screening analysis, we demonstrated that pro-inflammatory cytokines, but not palmitate, increase ACE2 expression in the β-cell line EndoC-βH1 and in primary human pancreatic islets. Taken together, our data indicate a potential link between SARS-CoV-2 and diabetes through putative infection of pancreatic microvasculature and/or ductal cells and/or through direct β-cell virus tropism.

ACE2 mouse models: a toolbox for cardiovascular and pulmonary research

Angiotensin-converting enzyme 2 (ACE2) has been identified as the host entry receptor for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) responsible for the COVID-19 pandemic. ACE2 is a regulatory enzyme of the renin-angiotensin system and has protective functions in many cardiovascular, pulmonary and metabolic diseases. This review summarizes available murine models with systemic or organ-specific deletion of ACE2, or with overexpression of murine or human ACE2. The purpose of this review is to provide researchers with the genetic tools available for further understanding of ACE2 biology and for the investigation of ACE2 in the pathogenesis and treatment of COVID-19.

Prevention and Management of Type 2 Diabetes and Metabolic Syndrome in the Time of COVID-19: Should We Add a Cup of Coffee?

Recent evidence shows that COVID-19 patients with existing metabolic disorders, such as diabetes and metabolic syndrome, are exposed to a high risk of morbidity and mortality. At the same time, in order to manage the pandemic, the health authorities around the world are advising people to stay at home. This results in decreased physical activity and an increased consumption of an unhealthy diet, which often leads to an increase in body weight, risk for diabetes, insulin resistance, and metabolic syndrome, and thus, paradoxically, to a high risk of morbidity and mortality due to COVID-19 complications. Here we summarize the evidence demonstrating that the promotion of a healthy life style, including physical activity and a dietary intake of natural polyphenols present in coffee and tea, has the potential to improve the prevention and management of insulin resistance and diabetes in the time of COVID-19 pandemic. Particularly, it would be pertinent to evaluate further the potential positive effects of coffee beverages, rich in natural polyphenols, as an adjuvant therapy for COVID-19, which appear not to be studied sufficiently.

Autoantibody-negative insulin-dependent diabetes mellitus after SARS-CoV-2 infection: a case report

Here we report a case where the manifestations of insulin-dependent diabetes occurred following SARS-CoV-2 infection in a young individual in the absence of autoantibodies typical for type 1 diabetes mellitus. Specifically, a 19-year-old white male presented at our emergency department with diabetic ketoacidosis, C-peptide level of 0.62 µg l^-1, blood glucose concentration of 30.6 mmol l^-1 (552 mg dl^-1) and haemoglobin A1c of 16.8%. The patient´s case history revealed probable COVID-19 infection 5-7 weeks before admission, based on a positive test for antibodies against SARS-CoV-2 proteins as determined by enzyme-linked immunosorbent assay. Interestingly, the patient carried a human leukocyte antigen genotype (HLA DR1-DR3-DQ2) considered to provide only a slightly elevated risk of developing autoimmune type 1 diabetes mellitus. However, as noted, no serum autoantibodies were observed against islet cells, glutamic acid decarboxylase, tyrosine phosphatase, insulin and zinc-transporter 8. Although our report cannot fully establish causality between COVID-19 and the development of diabetes in this patient, considering that SARS-CoV-2 entry receptors, including angiotensin-converting enzyme 2, are expressed on pancreatic β-cells and, given the circumstances of this case, we suggest that SARS-CoV-2 infection, or COVID-19, might negatively affect pancreatic function, perhaps through direct cytolytic effects of the virus on β-cells.

Hypertension, Thrombosis, Kidney Failure, and Diabetes: Is COVID-19 an Endothelial Disease? A Comprehensive Evaluation of Clinical and Basic Evidence

The symptoms most commonly reported by patients affected by coronavirus disease (COVID-19) include cough, fever, and shortness of breath. However, other major events usually observed in COVID-19 patients (e.g., high blood pressure, arterial and venous thromboembolism, kidney disease, neurologic disorders, and diabetes mellitus) indicate that the virus is targeting the endothelium, one of the largest organs in the human body. Herein, we report a systematic and comprehensive evaluation of both clinical and preclinical evidence supporting the hypothesis that the endothelium is a key target organ in COVID-19, providing a mechanistic rationale behind its systemic manifestations.

Analysis of Mortality in Patients With COVID-19: Clinical and Laboratory Parameters

BACKGROUND

Several reports on epidemiological and clinical features of the 2019 coronavirus disease (COVID-19) have been published. However, mortality and morbidity analyses, important for better understanding the pathogenesis of this disease, are scarce. We examine the clinical and laboratory features of 14 patients who died of COVID-19.

METHODS

The cohort consisted of 11 male and 3 female patients, with 9 patients aged 70 years or above, and nearly all had underlying diseases.

RESULTS

Fever with bilateral pneumonia was the main manifestation. Most patients had consolidations combined with ground glass opacity (GGO) on chest computed tomography scan. Laboratory tests showed lymphocytopenia in 10 patients, high blood glucose in 11, GGT in 5 of the 14 patients, and high LDH in 5 of 6 patients tested. In addition, this cohort had high level of cytokines such as interleukin-6 in all 8 patients tested.

CONCLUSIONS

The clinical and laboratory parameters in the cohort of fatal cases may be incorporated into future clinical prognosis models and will be of help in understanding the pathogenesis of this disease.

Liraglutide Attenuates Non-Alcoholic Fatty Liver Disease in Mice by Regulating the Local Renin-Angiotensin System

The renin-angiotensin system (RAS) is involved in the pathogenesis of non-alcoholic fatty liver disease (NAFLD) and represents a potential therapeutic target for NAFLD. Glucagon-like peptide-1 (GLP-1) signaling has been shown to regulate the RAS within various local tissues. In this study, we aimed to investigate the functional relationship between GLP-1 and the local RAS in the liver during NAFLD. Wild-type and ACE2 knockout mice were used to establish a high-fat-induced NAFLD model. After the mice were treated with liraglutide (a GLP-1 analogue) for 4 weeks, the key RAS component genes were up-regulated in the liver of NAFLD mice. Liraglutide treatment regulated the RAS balance, preventing a reduction in fatty acid oxidation gene expression and increasing gluconeogenesis and the expression of inflammation-related genes caused by NAFLD, which were impaired in ACE2 knockout mice. Liraglutide-treated HepG2 cells exhibited activation of the ACE2/Ang1-7/Mas axis, increased fatty acid oxidation gene expression, and decreased inflammation, which could be reversed by A779 and AngII. These results indicate that the local RAS in the liver becomes overactivated in response to NAFLD. Moreover, ACE2 knockout increases the severity of liver steatosis. Liraglutide has a negative and antagonistic effect on the ACE/AngII/AT1R axis, a positive impact on the ACE2/Ang1-7/Mas axis, and is mediated through the PI3K/AKT pathway. This may represent a potential new mechanism by which liraglutide improves NAFLD.

Long-Term Liraglutide Administration Induces Pancreas Neogenesis in Adult T2DM Mice

In vivo beta-cell neogenesis may be one way to treat diabetes. We aimed to investigate the effect of glucagon-like peptide-1 (GLP-1) on beta-cell neogenesis in type 2 diabetes mellitus (T2DM). Male C57BL/6J mice, 6 wk old, were randomly divided into three groups: Control, T2DM, and T2DM + Lira. T2DM was induced using high-fat diet and intraperitoneal injection of streptozotocin (40 mg/kg/d for 3 d). At 8 wk after streptozotocin injection, T2DM + Lira group was injected intraperitoneally with GLP-1 analog liraglutide (0.8 mg/kg/d) for 4 wk. Apparently for the first time, we report the appearance of a primitive bud connected to pancreas in all adult mice from each group. The primitive bud was characterized by scattered single monohormonal cells expressing insulin, GLP-1, somatostatin, or pancreatic polypeptide, and four-hormonal cells, but no acinar cells and ductal epithelial cells. Monohormonal cells in it were small, newborn, immature cells that rapidly proliferated and expressed cell markers indicative of immaturity. In parallel, Ngn3+ endocrine progenitors and Nestin+ cells existed in the primitive bud. Liraglutide facilitated neogenesis and rapid growth of acinar cells, pancreatic ducts, and blood vessels in the primitive bud. Meanwhile, scattered hormonal cells aggregated into cell clusters and grew into larger islets; polyhormonal cells differentiated into monohormonal cells. Extensive growth of exocrine and endocrine glands resulted in the neogenesis of immature pancreatic lobes in adult mice of T2DM + Lira group. Contrary to predominant acinar cells in mature pancreatic lobes, there were still a substantial number of mesenchymal cells around acinar cells in immature pancreatic lobes, which resulted in the loose appearance. Our results suggest that adult mice preserve the capacity of pancreatic neogenesis from the primitive bud, which liraglutide facilitates in adult T2DM mice. To our knowledge, this is the first time such a phenomenon has been reported.

The Impact of COVID-19 on Blood Glucose: A Systematic Review and Meta-Analysis

Background: Diabetes mellitus is considered a common comorbidity of COVID-19, which has a wide spectrum of clinical manifestations ranging from asymptomatic infection to severe respiratory symptoms and even death. However, the impact of COVID-19 on blood glucose has not been fully understood. This meta-analysis aimed to summarize available data on the association between glycemic parameters and severity of COVID-19. Methods: PubMed, EMBASE, and Cochrane Library were searched from December 1, 2019 to May 15, 2020. Observational studies investigating blood glucose or glycated hemoglobin A1c (HbA1c) according to the severity of COVID-19 were considered for inclusion. Two independent researchers extracted data from eligible studies using a standardized data extraction sheet and then proceeded to cross check the results. Data were pooled using a fixed- or random-effects model to calculate the weighted mean differences (WMDs) and 95% confidence intervals (CIs). Results: Three studies reported blood glucose and HbA1c according to the severity of COVID-19 and were included in this meta-analysis. The combined results showed that severe COVID-19 was associated with higher blood glucose (WMD 2.21, 95% CI: 1.30-3.13, P < 0.001). In addition, HbA1c was slightly higher in patients with severe COVID-19 than those with mild COVID-19, yet this difference did not reach significance (WMD 0.29, 95% CI: -0.59 to 1.16, P = 0.52). Conclusions: This meta-analysis provides evidence that severe COVID-19 is associated with increased blood glucose. This highlights the need to effectively monitor blood glucose to improve prognosis in patients infected with COVID-19.

Death versus dedifferentiation: The molecular bases of beta cell mass reduction in type 2 diabetes

Diabetes Mellitus is currently affecting more than 425 million people worldwide, among which over 90 % of the cases belong to type 2 diabetes. The number is growing quickly every year. Together with its many complications, the disease is causing tremendous social and economic burden and is classified as one of the leading causes of high morbidity and mortality rate. Residing in the islets of Langerhans, pancreatic beta cell serves as a central mediator in glucose homeostasis through secreting insulin, the only hormone that could reduce glucose level in the body, into the blood. Abnormality in pancreatic beta cell is generally considered as the fundamental reason which is responsible for the development of diabetes. Evidence shows that beta cell mass is greatly reduced in the biopsy of type 2 diabetic patients. Since then, large amount of research was conducted in order to decipher the molecular mechanisms behind the phenotype above and enormous progression has been made. The aim of this review is to summarize and provide a rudimentary molecular road map for beta cell mass reduction from the aspects of apoptosis and dedifferentiation based on recent research advances. Hopefully, this review could give the community some enlightenment for the next-step research and, more importantly, could provide avenues for developing novel and effective therapies to restrain or reverse beta cell loss in type 2 diabetes in the clinic.

Sex differences in metabolic effects of angiotensin-(1-7) treatment in obese mice

Background

Angiotensin-(1-7) is a beneficial hormone of the renin-angiotensin system known to play a positive role in regulation of blood pressure and glucose homeostasis. Previous studies have shown that in high-fat diet (HFD)-induced obese male mice, circulating angiotensin-(1-7) levels are reduced and chronic restoration of this hormone reverses diet-induced insulin resistance; however, this has yet to be examined in female mice. We hypothesized angiotensin-(1-7) would improve insulin sensitivity and glucose tolerance in obese female mice, to a similar extent as previously observed in male mice.

Methods

Five-week-old male and female C57BL/6J mice (8–12/group) were placed on control diet or HFD (16% or 59% kcal from fat, respectively) for 11 weeks. After 8 weeks of diet, mice were implanted with an osmotic pump for 3-week subcutaneous delivery of angiotensin-(1-7) (400 ng/kg/min) or saline vehicle. During the last week of treatment, body mass and composition were measured and intraperitoneal insulin and glucose tolerance tests were performed to assess insulin sensitivity and glucose tolerance, respectively. Mice were euthanized at the end of the study for blood and tissue collection.

Results

HFD increased body mass and adiposity in both sexes. Chronic angiotensin-(1-7) infusion significantly decreased body mass and adiposity and increased lean mass in obese mice of both sexes. While both sexes tended to develop mild hyperglycemia in response to HFD, female mice developed less marked hyperinsulinemia. There was no effect of angiotensin-(1-7) on fasting glucose or insulin levels among diet and sex groups. Male and female mice similarly developed insulin resistance and glucose intolerance in response to HFD feeding. Angiotensin-(1-7) improved insulin sensitivity in both sexes but corrected glucose intolerance only in obese female mice. There were no effects of sex or angiotensin-(1-7) treatment on any of the study outcomes in control diet-fed mice.

Conclusions

This study provides new evidence for sex differences in the impact of chronic angiotensin-(1-7) in obese mice, with females having greater changes in glucose tolerance with treatment. These findings improve understanding of sex differences in renin-angiotensin mechanisms in obesity and illustrate the potential for targeting angiotensin-(1-7) for treatment of this condition.

Sex differences in the metabolic effects of the renin-angiotensin system

Obesity is a global epidemic that greatly increases risk for developing cardiovascular disease and type II diabetes. Sex differences in the obese phenotype are well established in experimental animal models and clinical populations. While having higher adiposity and obesity prevalence, females are generally protected from obesity-related metabolic and cardiovascular complications. This protection is, at least in part, attributed to sex differences in metabolic effects of hormonal mediators such as the renin-angiotensin system (RAS). Previous literature has predominantly focused on the vasoconstrictor arm of the RAS and shown that, in contrast to male rodent models of obesity and diabetes, females are protected from metabolic and cardiovascular derangements produced by angiotensinogen, renin, and angiotensin II. A vasodilator arm of the RAS has more recently emerged which includes angiotensin-(1-7), angiotensin-converting enzyme 2 (ACE2), mas receptors, and alamandine. While accumulating evidence suggests that activation of components of this counter-regulatory axis produces positive effects on glucose homeostasis, lipid metabolism, and energy balance in male animal models, female comparison studies and clinical data related to metabolic outcomes are lacking. This review will summarize current knowledge of sex differences in metabolic effects of the RAS, focusing on interactions with gonadal hormones and potential clinical implications.

Genetic Models

Genetically altered rat and mouse models have been instrumental in the functional analysis of genes in a physiological context. In particular, studies on the renin-angiotensin system (RAS) have profited from this technology in the past. In this review, we summarize the existing animal models for the protective axis of the RAS consisting of angiotensin-converting enzyme 2 (ACE2), angiotensin-(1-7)(Ang-(1-7), and its receptor Mas. With the help of models with altered expression of the components of this axis in the brain and cardiovascular organs, its physiological and pathophysiological functions have been elucidated. Thus, novel opportunities for therapeutic interventions in cardiovascular diseases were revealed targeting ACE2 or Mas.