Type 2 Diabetes Mellitus Drugs for Alzheimer's Disease: Current Evidence and Therapeutic Opportunities

Hypoglycemic TCM formulas (Huangqi-Gegen drug pair) have the potential as an Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a neurological disorder. There is a considerable unmet medical need among those suffering from it.

HYPOTHESIS AND PURPOSE

Given the link between type-2 diabetes mellitus (T2DM) and AD, hypoglycemic traditional Chinese medicine formulas (TCMFs) may be a treatment for AD. We investigated the possibility of identifying anti-AD medicines in hypoglycemic TCMFs and presented another option for the screening of AD medications.

STUDY DESIGN AND METHODS

Paralysis of the transgenic Caenorhabditis elegans (C. elegans) strain CL4176 (caused by amyloid beta (Aβ)1-42 aggregates) was used to evaluate the anti-AD effect. The toxicity and neurodegeneration induced by neuronal expression of Aβ in the transgenic C. elegans strain CL2355 were determined using a 5-hydroxytryptamine (5-HT) assay. The transgenic Aβ-expressing strain CL 2006 and transgenic tau-expressing strain BR5270 were used to explore the effect of TCMFs on protein expression in C. elegans using ELISAs. Then, network pharmacology was used to determine the mechanism of action. The Traditional Chinese Medicine Inheritance Support System platform was used to investigate prescription patterns, core drugs, and optimum combinations of hypoglycemic TCMFs for AD.

RESULTS

Sixteen hypoglycemic TCMFs prolonged the PT50 (half paralysis time) of the CL4176 strain of C. elegans, reduced the percentage of worms paralyzed. The results of network pharmacology showed that prostaglandin-endoperoxide synthase 2 (PTGS2) and acetylcholine esterase (AChE) are main targets of hypoglycemic TCMFs. Enriched pathway analysis showed that the cholinergic receptor-related pathway was the core pathway of hypoglycemic TCMFs. According to the "four qi and five flavors" system of TCM theory, the main pharmacological qualities were "cold" and "sweet." Through the analysis by TCMISS, we found that Huangqi-Gegen drug pair as the significant Chinese herbs of hypoglycemic TCMFs. The Huangqi-Gegen pairing had the most robust therapeutic effect when delivered at a 2:1 (v/v) ratio. It reduced the paralysis caused by 5-HT, decreased protein expression of AChE and PTGS2, and reduced Aβ deposition in the brain of the CL2006 strain of C. elegans.

CONCLUSIONS

Huangqi-Gegen is a promising treatment of AD, and its mechanism may be induced by suppressing the protein production of AChE and PTGS2, reducing 5-HT intake, and then decreasing Aβ deposition.

Targeting VDAC: A potential therapeutic approach for mitochondrial dysfunction in Alzheimer's disease

Mitochondrial dysfunction has been implicated in the pathogenesis of Alzheimer's disease, a neurodegenerative disorder characterized by progressive cognitive decline. Voltage-dependent anion channel (VDAC), a protein located in the outer mitochondrial membrane, plays a critical role in regulating mitochondrial function and cellular energy metabolism. Recent studies have identified VDAC as a potential therapeutic target for Alzheimer's disease. This article aims to provide an overview of the role of VDAC in mitochondrial dysfunction, its association with Alzheimer's disease, and the potential of targeting VDAC for developing novel therapeutic interventions. Understanding the involvement of VDAC in Alzheimer's disease may pave the way for the development of effective treatments that can restore mitochondrial function and halt disease progression.

Investigations of Limeum Indicum Plant for Diabetes Mellitus and Alzheimer's Disease Dual Therapy: Phytochemical, GC-MS Chemical Profiling, Enzyme Inhibition, Molecular Docking and In-Vivo Studies

Limeum indicum has been widely utilized in traditional medicine but no experimental work has been done on this herb. The primary objective of this study was to conduct a phytochemical analysis and assess the multifunctional capabilities of aforementioned plant in dual therapy for Alzheimer's disease (AD) and Type 2 diabetes (T2D). The phytochemical screening of ethanol, methanol extract, and their derived fractions of Limeum indicum was conducted using GC-MS, HPLC, UV-analysis and FTIR. The antioxidant capacity was evaluated by DPPH method. The inhibitory potential of the extracts/fractions against α-, β-glucosidase acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and monoaminine oxidases (MAO-A & B) was evaluated. Results revealed that acetonitrile fraction has highest inhibitory potential against α-glucosidase (IC50=68.47±0.05 μg/mL), methanol extract against β-glucosidase (IC50=91.12±0.07 μg/mL), ethyl acetate fraction against AChE (IC50=59.0±0.02 μg/mL), ethanol extract against BChE (28.41±0.01 μg/mL), n-hexane fraction against MAO-A (IC50=150.5±0.31 μg/mL) and methanol extract for MAO-B (IC50=75.95±0.13 μg/mL). The docking analysis of extracts\fractions suggested the best binding scores within the active pocket of the respective enzymes. During the in-vivo investigation, ethanol extract produced hypoglycemic effect (134.52±2.79 and 119.38±1.40 mg/dl) after 21 days treatment at dose level of 250 and 500 mg/Kg. Histopathological findings further supported the in-vivo studies.

A systematic review of astragaloside IV effects on animal models of diabetes mellitus and its complications

Context

Diabetes mellitus (DM) is one of the fastest-growing diseases worldwide; however, its pathogenesis remains unclear. Complications seriously affect the quality of life of patients in the later stages of diabetes, ultimately leading to suffering. Natural small molecules are an important source of antidiabetic agents.

Objective

Astragaloside IV (AS-IV) is an active ingredient of Astragalus mongholicus (Fisch.) Bunge. We reviewed the efficacy and mechanism of action of AS-IV in animal and cellular models of diabetes and the mechanism of action of AS-IV on diabetic complications in animal and cellular models. We also summarized the safety of AS-IV and provided ideas and rationales for its future clinical application.

Methods

Articles on the intervention in DM and its complications using AS-IV, such as those published in SCIENCE, PubMed, Springer, ACS, SCOPUS, and CNKI from the establishment of the database to February 2022, were reviewed. The following points were systematically summarized: dose/concentration, route of administration, potential mechanisms, and efficacy of AS-IV in animal models of DM and its complications.

Results

AS-IV has shown therapeutic effects in animal models of DM, such as alleviating gestational diabetes, delaying diabetic nephropathy, preventing myocardial cell apoptosis, and inhibiting vascular endothelial dysfunction; however, the potential effects of AS-IV on DM should be investigated.

Conclusion

AS-IV is a potential drug for the treatment of diabetes and its complications, including diabetic vascular disease, cardiomyopathy, retinopathy, peripheral neuropathy, and nephropathy. In addition, preclinical toxicity studies indicate that it appears to be safe, but the safe human dose limit is yet to be determined, and formal assessments of adverse drug reactions among humans need to be further investigated. However, additional formulations or structural modifications are required to improve the pharmacokinetic parameters and facilitate the clinical use of AS-IV.

Enhanced Nose-to-Brain Delivery of Combined Small Interfering RNAs Using Lesion-Recognizing Nanoparticles for the Synergistic Therapy of Alzheimer's Disease

Gene therapy has great potential in treating neurodegenerative diseases with complex pathologies. The combination of small interfering RNAs (siRNAs) targeting β-site amyloid precursor protein cleaving enzyme 1 (BACE1) and caspase-3 will provide an effective treatment option for Alzheimer's disease (AD). To overcome the multiple physiological barriers and improve the therapeutic efficacy of siRNAs, lesion-recognizing nanoparticles (NPs) are constructed in this study for the synergistic treatment of AD. The lesion-recognizing NPs contain rabies virus glycoprotein peptide-modified mesenchymal stem cell-derived exosomes as the shell and a reactive oxygen species (ROS)-responsive polymer loaded with siRNAs as the core. After intranasal administration, the lesion-recognizing NPs cross the nasal mucosa and migrate to the affected brain areas. Furthermore, the NPs recognize the target cells and fuse with the cell membranes of neurons. The cores of NPs directly enter into the cytoplasm and achieve the controlled release of siRNAs in a high-ROS environment to downregulate the level of BACE1 and caspase-3 to ameliorate neurologic injury. In addition, lesion-recognizing NPs can significantly reduce the number of reactive astrocytes. Lesion-recognizing NPs have a positive effect on regulating the phase of neurons and astrocytes, which results in better restoration of memory deficits in 3 × Tg-AD mice. Therefore, this work provides a promising platform for neurodegenerative disease treatment.

Crosstalk between Alzheimer's disease and diabetes: a focus on anti-diabetic drugs

Alzheimer's disease (AD) and Type 2 diabetes mellitus (T2DM) are two of the most common age-related diseases. There is accumulating evidence of an overlap in the pathophysiological mechanisms of these two diseases. Studies have demonstrated insulin pathway alternation may interact with amyloid-β protein deposition and tau protein phosphorylation, two essential factors in AD. So attention to the use of anti-diabetic drugs in AD treatment has increased in recent years. In vitro, in vivo, and clinical studies have evaluated possible neuroprotective effects of anti-diabetic different medicines in AD, with some promising results. Here we review the evidence on the therapeutic potential of insulin, metformin, Glucagon-like peptide-1 receptor agonist (GLP1R), thiazolidinediones (TZDs), Dipeptidyl Peptidase IV (DPP IV) Inhibitors, Sulfonylureas, Sodium-glucose Cotransporter-2 (SGLT2) Inhibitors, Alpha-glucosidase inhibitors, and Amylin analog against AD. Given that many questions remain unanswered, further studies are required to confirm the positive effects of anti-diabetic drugs in AD treatment. So to date, no particular anti-diabetic drugs can be recommended to treat AD.

Geroprotective interventions in the 3xTg mouse model of Alzheimer's disease

Alzheimer's disease (AD) is an age-associated neurodegenerative disease. As the population ages, the increasing prevalence of AD threatens massive healthcare costs in the coming decades. Unfortunately, traditional drug development efforts for AD have proven largely unsuccessful. A geroscience approach to AD suggests that since aging is the main driver of AD, targeting aging itself may be an effective way to prevent or treat AD. Here, we discuss the effectiveness of geroprotective interventions on AD pathology and cognition in the widely utilized triple-transgenic mouse model of AD (3xTg-AD) which develops both β-amyloid and tau pathologies characteristic of human AD, as well as cognitive deficits. We discuss the beneficial impacts of calorie restriction (CR), the gold standard for geroprotective interventions, and the effects of other dietary interventions including protein restriction. We also discuss the promising preclinical results of geroprotective pharmaceuticals, including rapamycin and medications for type 2 diabetes. Though these interventions and treatments have beneficial effects in the 3xTg-AD model, there is no guarantee that they will be as effective in humans, and we discuss the need to examine these interventions in additional animal models as well as the urgent need to test if some of these approaches can be translated from the lab to the bedside for the treatment of humans with AD.

Thiazolidinedione use is associated with reduced risk of dementia in patients with type 2 diabetes mellitus: A retrospective cohort study

BACKGROUND

Type 2 diabetes mellitus (T2DM) and dementia cause heavy health burden in mainland China, where few studies have investigated the association between glucose-lowering agents and dementia risk. We aimed to assess the association between use of thiazolidinediones (TZDs) and dementia incidence in a mainland Chinese population with T2DM.

METHODS

A retrospective cohort of T2DM patients who were new users of TZDs or alpha glucosidase inhibitors (AGIs) was assembled using the Yinzhou Regional Health Care Database. A Cox model with inverse probability of treatment weighting (IPTW) for controlling potential founding was applied to estimate the hazard ratio (HR) of the association between use of TZDs and dementia risk.

RESULTS

A total of 49 823 new users of AGIs and 12 752 new users of TZDs were included in the final cohort. In the primary analysis, the incidence of dementia was 195.7 and 78.2 per 100 000 person-years in users of AGIs and TZDs respectively. TZD use was associated with a reduced risk of incident dementia after adjusting for potential confounding using IPTW, with a HR of 0.51 (95% CI, 0.38-0.67). The results in various subgroup analyses and sensitivity analyses were consistent with the findings of the primary analysis.

CONCLUSIONS

Use of TZDs is associated with a decreased risk of dementia incidence in a mainland Chinese population with T2DM.

Metabolic perspective of astrocyte dysfunction in Alzheimer's disease and type 2 diabetes brains

The term type III diabetes (T3DM) has been proposed for Alzheimer's disease (AD) due to the shared molecular and cellular features between type 2 diabetes (T2DM) and insulin resistance-associated memory deficits and cognitive decline in elderly individuals. Astrocytes elicit neuroprotective or deleterious effects in AD progression and severity. Patients with T2DM are at a high risk of cognitive impairment, and targeting astrocytes might be promising in alleviating neurodegeneration in the diabetic brain. Recent studies focusing on cell-specific activities in the brain have revealed the important role of astrocytes in brain metabolism (e.g., glucose metabolism, lipid metabolism), neurovascular coupling, synapses, and synaptic plasticity. In this review, we discuss how astrocytes and their dysfunction result in multiple pathological and clinical features of AD and T2DM from a metabolic perspective and the potential comorbid mechanism in these two diseases from the perspective of astrocytes.

Enhancement of Impaired Olfactory Neural Activation and Cognitive Capacity by Liraglutide, but Not Dapagliflozin or Acarbose, in Patients With Type 2 Diabetes: A 16-Week Randomized Parallel Comparative Study

OBJECTIVE

The comparative neuroprotective effects of different antidiabetes drugs have not been characterized in randomized controlled trials. Here, we investigated the therapeutic effects of liraglutide, dapagliflozin, or acarbose treatment on brain functional alterations and cognitive changes in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Thirty-six patients with type 2 diabetes inadequately controlled with metformin monotherapy were randomized to receive liraglutide, dapagliflozin, or acarbose treatment for 16 weeks. Brain functional MRI (fMRI) scan and a battery of cognitive assessments were evaluated pre- and postintervention in all subjects.

RESULTS

The 16-week treatment with liraglutide significantly enhanced the impaired odor-induced left hippocampal activation with Gaussian random field correction and improved cognitive subdomains of delayed memory, attention, and executive function (all P < 0.05), whereas dapagliflozin or acarbose did not. Structural equation modeling analysis demonstrated that such improvements of brain health and cognitive function could be partly ascribed to a direct effect of liraglutide on left hippocampal activation (β = 0.330, P = 0.022) and delayed memory (β = 0.410, P = 0.004) as well as to the metabolic ameliorations of reduced waist circumference, decreased body fat ratio, and elevated fasting insulin (all P < 0.05).

CONCLUSIONS

Our head-to-head study demonstrated that liraglutide enhanced impaired brain activation and restored impaired cognitive domains in patients with type 2 diabetes, whereas dapagliflozin and acarbose did not. The results expand the clinical application of liraglutide and provide a novel treatment strategy for individuals with diabetes and a high risk of cognitive decline.

Causal association evaluation of diabetes with Alzheimer's disease and genetic analysis of antidiabetic drugs against Alzheimer's disease

Background

Despite accumulating epidemiological studies support that diabetes increases the risk of Alzheimer’s disease (AD), the causal associations between diabetes and AD remain inconclusive. The present study aimed to explore: i) whether diabetes is causally related to the increased risk of AD; ii) and if so, which diabetes-related physiological parameter is associated with AD; iii) why diabetes drugs can be used as candidates for the treatment of AD. Two-sample Mendelian randomization (2SMR) was employed to perform the analysis.

Results

Firstly, the 2SMR analysis provided a suggestive association between genetically predicted type 1 diabetes (T1D) and a slightly increased AD risk (OR = 1.04, 95% CI = [1.01, 1.06]), and type 2 diabetes (T2D) showed a much stronger association with AD risk (OR = 1.34, 95% CI = [1.05, 1.70]). Secondly, further 2SMR analysis revealed that diabetes-related physiological parameters like fasting blood glucose and total cholesterol levels might have a detrimental role in the development of AD. Thirdly, we obtained 74 antidiabetic drugs and identified SNPs to proxy the targets of antidiabetic drugs. 2SMR analysis indicated the expression of three target genes, ETFDH, GANC, and MGAM, were associated with the increased risk of AD, while CPE could be a protective factor for AD. Besides, further PPI network found that GANC interacted with MGAM, and further interacted with CD33, a strong genetic locus related to AD.

Conclusions

In conclusion, the present study provides evidence of a causal association between diabetes and increased risk of AD, and also useful genetic clues for drug development.

Targeting whole body metabolism and mitochondrial bioenergetics in the drug development for Alzheimer's disease

Aging is by far the most prominent risk factor for Alzheimer's disease (AD), and both aging and AD are associated with apparent metabolic alterations. As developing effective therapeutic interventions to treat AD is clearly in urgent need, the impact of modulating whole-body and intracellular metabolism in preclinical models and in human patients, on disease pathogenesis, have been explored. There is also an increasing awareness of differential risk and potential targeting strategies related to biological sex, microbiome, and circadian regulation. As a major part of intracellular metabolism, mitochondrial bioenergetics, mitochondrial quality-control mechanisms, and mitochondria-linked inflammatory responses have been considered for AD therapeutic interventions. This review summarizes and highlights these efforts.

The Cause of Alzheimer's Disease: The Theory of Multipathology Convergence to Chronic Neuronal Stress

The field of Alzheimer's disease (AD) research critically lacks an all-inclusive etiology theory that would integrate existing hypotheses and explain the heterogeneity of disease trajectory and pathologies observed in each individual patient. Here, we propose a novel comprehensive theory that we named: the multipathology convergence to chronic neuronal stress. Our new theory reconsiders long-standing dogmas advanced by previous incomplete theories. Firstly, while it is undeniable that amyloid beta (Aβ) is involved in AD, in the seminal stage of the disease Aβ is unlikely pathogenic. Instead, we hypothesize that the root cause of AD is neuronal stress in the central nervous system (CNS), and Aβ is expressed as part of the physiological response to protect CNS neurons from stress. If there is no return to homeostasis, then Aβ becomes overexpressed, and this includes the generation of longer forms that are more toxic and prone to oligomerization. Secondly, AD etiology is plausibly not strictly compartmentalized within the CNS but may also result from the dysfunction of other physiological systems in the entire body. This view implies that AD may not have a single cause, but rather needs to be considered as a spectrum of multiple chronic pathological modalities converging to the persistent stressing of CNS neurons. These chronic pathological modalities, which include cardiovascular disease, metabolic disorders, and CNS structural changes, often start individually, and over time combine with other chronic modalities to incrementally escalate the amount of stress applied to CNS neurons. We present the case for considering Aβ as a marker of neuronal stress in response to hypoxic, toxic, and starvation events, rather than solely a marker of AD. We also detail numerous human chronic conditions that can lead to neuronal stress in the CNS, making the link with co-morbidities encountered in daily clinical AD practice. Finally, we explain how our theory could be leveraged to improve clinical care for AD and related dementia in personalized medicine paradigms in the near future.

Ultra-stable dextran conjugated prodrug micelles for oxidative stress and glycometabolic abnormality combination treatment of Alzheimer's disease

Sophisticated nanomedicines are continually being developed, but big obstacles remain before they finish the drug release mission. The first challenge is rupture possibility of structure when infinite dilution, competitive reaction of electrolytes and protein in blood circulation. In addition, low responsive drug release efficiency in the lesion site remains the major challenge for clinical application of nanomedicine combination treatment. In this study, we discussed the opportunities for Alzheimer's disease (AD) combination therapy based on the thermodynamically ultra-stable dextran conjugated prodrug micelles. Dextran-nateglinide conjugated prodrug micelles (NA) and dextran-vitamin E succinate conjugated prodrug micelles (VES) presented ultra-low critical micelle concentration of ~10^-5 mM and high physiological stability when challenged by NaCl, sodium dodecyl sulphate (SDS), dodecyl dimethyl benzyl ammonium chloride (DDBAC) and no rupture of structure happened. The NA/insulin polymer-drug conjugate micelles (NA/INS PDC) and VES/insulin polymer-drug conjugate micelles (VES/INS PDC) efficiently cleaved by reactive oxygen species (ROS), leading to over 80% release of the encapsulated and conjugated drugs. The combination of nateglinide and insulin, vitamin E succinate and insulin improved the glucose metabolism, reduced oxidative stress, improved the mitochondrial function and recovered the cognitive capacity of mice. This work demonstrated a paradigm for specific and high efficacy AD combination therapy.

A novel DPP-4 inhibitor Gramcyclin A attenuates cognitive deficits in APP/PS1/tau triple transgenic mice via enhancing brain GLP-1-dependent glucose uptake

Enhancing glucagon-like peptide 1 (GLP-1) signaling with a dipeptidyl peptidase IV (DPP-4) inhibitor might exert protective effects on Alzheimer's disease (AD). We found that intragastric administration of Gramcyclin A (10, 20 and 40 mg/kg), a novel DPP-4 inhibitor, for 3 months significantly reversed cognitive decline in APP/PS1/tau triple transgenic mice in a dose-dependent manner. Gramcyclin A treatment markedly reduced Aβ plaques as well as the insoluble and soluble forms of Aβ40 and Aβ42 in the hippocampus of APP/PS1/tau mice. Treatment with Gramcyclin A remarkedly decreased the level of microglia and suppressed neuroinflammation in the hippocampus of APP/PS1/tau mice. Moreover, Gramcyclin A treatment could increase brain glucose uptake in APP/PS1/tau mice, as detected by 18-fluoro-2-deoxyglucose (¹⁸ F-FDG) micro-positron emission tomography (micro-PET) imaging. Furthermore, Gramcyclin A significantly increased expression of glucagon-like peptide-1 (GLP-1), GLP-1R, proliferator-activated receptor gamma coactivator (PGC)-1α and glucose transporter 4 (GLUT4), and inhibited insulin receptor (IRS)-1 phosphorylation and tau hyperphosphorylation in the hippocampus of APP/PS1/tau mice. Collectively, Gramcyclin A conferred protective effects against AD via enhancing brain GLP-1-dependent glucose uptake. The DPP-4 inhibitor Gramcyclin A might be a potential therapeutic drug for AD.

New treatment approaches for Alzheimer's disease: preclinical studies and clinical trials centered on antidiabetic drugs

INTRODUCTION

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) represent two major chronic diseases that affect a large percentage of the population and share common pathogenetic mechanisms, including oxidative stress and inflammation. Considering their common mechanistic aspects, and given the current lack of effective therapies for AD, accumulating research has focused on the therapeutic potential of antidiabetic drugs in the treatment or prevention of AD.

AREAS COVERED

This review examines the latest preclinical and clinical evidence on the potential of antidiabetic drugs as candidates for AD treatment. Numerous approved drugs for T2DM, including insulin, metformin, glucagon-like peptide-1 receptor agonists (GLP-1 RA), and sodium glucose cotransporter 2 inhibitors (SGLT2i), are in the spotlight and may constitute novel approaches for AD treatment.

EXPERT OPINION

Among other pharmacologic agents, GLP-1 RA and SGLT2i have so far exhibited promising results as novel treatment approaches for AD, while current research has centered on deciphering their action on the central nervous system (CNS). Further investigation is crucial to reveal the most effective pharmacological agents and their optimal combinations, maximize their beneficial effects on neurons, and find ways to increase their distribution to the CNS.

Metformin and cyanidin 3-O-galactoside from Aronia melanocarpa synergistically alleviate cognitive impairment in SAMP8 mice

Cyanidin 3-O-galactoside (Cy3Gal) from Aronia melanocarpa has been reported to alleviate cognitive impairment. Metformin for preventing the neurodegenerative disease is attracting increasing attention. However, the neuroprotective and metabolic health promoting both of their effects are not clear. We chose the senescence accelerated mouse prone 8 (SAMP8) as a model of spontaneous learning and memory impairment. This study aimed to investigate the synergistic neuroprotective effect of metformin and Cy3Gal by behavioral and histopathological assays and metabolite analysis in SAMP8 mice. The SAMR1 mice were the normal group, and the SAMP8 mice were divided into five groups, including the SAMP8 model group, the donepezil (1 mg kg^-1, ig) group, the metformin (100 mg kg^-1, ig) group, the Cy3Gal (25 mg kg^-1, ig) group, and the combination of metformin plus Cy3Gal (Met + Cy3Gal, 100 mg kg^-1, 25 mg kg^-1, ig) group. The behavior experiments showed that the SAMP8 mice treated with metformin and Cy3Gal showed improved spatial learning and memory compared to the SAMP8 model group. The number of neurons in the Met + Cy3Gal group was significantly higher than that in the SAMP8 group and the Met + Cy3Gal group showed significantly reduced Aβ aggregation in the brain, which was elevated in SAMP8 mice. Compared with SAMP8 mice, the Met + Cy3Gal group showed decreased indole, methyl esters and ketones and increased short-chain fatty acids and alcohols in feces and urine by regulating the fatty acid biosynthesis and degradation. This study confirmed the neuroprotective effects of coadministration of metformin and cyanidin 3-O-galactoside in the SAMP8 mice, and suggested its positive effect on postponing the progression of Alzheimer's disease.

Tumor-activatable biomineralized nanotherapeutics for integrative glucose starvation and sensitized metformin therapy

Metformin is a clinically-approved anti-diabetic drug with emerging antitumor potential, but its antitumor activity is highly susceptible to local glucose abundance. Herein, we construct a nanotherapeutic platform based on biocompatible constituents to sensitize tumor cells for metformin therapy via cooperative glucose starvation. The nanoplatform was synthesized through the spontaneous biomineralization of glucose oxidase (GOx) and metformin in amorphous calcium phosphate nanosubstrate, which was further modified with polyethylene glycol and cRGD ligands. This biomineralized nanosystem could efficiently deliver the therapeutic payloads to tumor cells in a targeted and bioresponsive manner. Here GOx could catalyze the oxidation of glucose into gluconic acid and H₂O₂, thus depleting the glucose in tumor intracellular compartment while accelerating the release of the entrapped therapeutic payloads. The selective glucose deprivation would not only disrupt tumor energy metabolism, but also upregulate the PP2A regulatory subunit B56δ and sensitize tumor cells to the metformin-induced CIP2A inhibition, leading to efficient apoptosis induction via PP2A-GSK3β-MCL-1 axis with negligible side effects. This study may offer new avenues for targeted tumor therapy in the clinical context.

Role of DPP-4 and SGLT2 Inhibitors Connected to Alzheimer Disease in Type 2 Diabetes Mellitus

Alzheimer's disease (AD) is characterized by memory loss and cognitive decline. Additionally, abnormal extracellular amyloid plaques accumulation and nerve damage caused by intracellular neurofibrillary tangles, and tau protein are characteristic of AD. Furthermore, AD is associated with oxidative stress, impaired mitochondrial structure and function, denormalization, and inflammatory responses. Recently, besides the amyloid β hypothesis, another hypothesis linking AD to systemic diseases has been put forth by multiple studies as a probable cause for AD. Particularly, type 2 diabetes mellitus (T2DM) and its features, including hyperinsulinemia, and chronic hyperglycemia with an inflammatory response, have been shown to be closely related to AD through insulin resistance. The brain cannot synthesize or store glucose, but it does require glucose, and the use of glucose in the brain is higher than that in any other organ in the mammalian body. One of the therapeutic drugs for T2DM, dipeptidyl peptidase-4 (DPP-4) inhibitor, suppresses the degradation of incretins, glucagon-like peptides and glucose-dependent insulinotropic peptide. Sodium-glucose cotransporter 2 (SGLT2) inhibitors, recently used in T2DM treatment, have a unique mechanism of action via inhibition of renal glucose reabsorption, and which is different from the mechanisms of previously used medications. This manuscript reviews the pathophysiological relationship between the two diseases, AD and T2DM, and the pharmacological effects of therapeutic T2DM drugs, especially DPP-4 inhibitors, and SGLT2 inhibitors.

Insulin Resistance as a Common Link Between Current Alzheimer's Disease Hypotheses

Almost 115 years ago, Alois Alzheimer described Alzheimer's disease (AD) for the first time. Since then, many hypotheses have been proposed. However, AD remains a severe health public problem. The current medical approaches for AD are limited to symptomatic interventions and the complexity of this disease has led to a failure rate of approximately 99.6%in AD clinical trials. In fact, no new drug has been approved for AD treatment since 2003. These failures indicate that we are failing in mimicking this disease in experimental models. Although most studies have focused on the amyloid cascade hypothesis of AD, the literature has made clear that AD is rather a multifactorial disorder. Therefore, the persistence in a single theory has resulted in lost opportunities. In this review, we aim to present the striking points of the long scientific path followed since the description of the first AD case and the main AD hypotheses discussed over the last decades. We also propose insulin resistance as a common link between many other hypotheses.

Metabolism and Chronic Inflammation: The Links Between Chronic Heart Failure and Comorbidities

Heart failure (HF) patients often suffer from multiple comorbidities, such as diabetes, atrial fibrillation, depression, chronic obstructive pulmonary disease, and chronic kidney disease. The coexistance of comorbidities usually leads to multi morbidity and poor prognosis. Treatments for HF patients with multi morbidity are still an unmet clinical need, and finding an effective therapy strategy is of great value. HF can lead to comorbidity, and in return, comorbidity may promote the progression of HF, creating a vicious cycle. This reciprocal correlation indicates there may be some common causes and biological mechanisms. Metabolism remodeling and chronic inflammation play a vital role in the pathophysiological processes of HF and comorbidities, indicating metabolism and inflammation may be the links between HF and comorbidities. In this review, we comprehensively discuss the major underlying mechanisms and therapeutic implications for comorbidities of HF. We first summarize the potential role of metabolism and inflammation in HF. Then, we give an overview of the linkage between common comorbidities and HF, from the perspective of epidemiological evidence to the underlying metabolism and inflammation mechanisms. Moreover, with the help of bioinformatics, we summarize the shared risk factors, signal pathways, and therapeutic targets between HF and comorbidities. Metabolic syndrome, aging, deleterious lifestyles (sedentary behavior, poor dietary patterns, smoking, etc.), and other risk factors common to HF and comorbidities are all associated with common mechanisms. Impaired mitochondrial biogenesis, autophagy, insulin resistance, and oxidative stress, are among the major mechanisms of both HF and comorbidities. Gene enrichment analysis showed the PI3K/AKT pathway may probably play a central role in multi morbidity. Additionally, drug targets common to HF and several common comorbidities were found by network analysis. Such analysis has already been instrumental in drug repurposing to treat HF and comorbidity. And the result suggests sodium-glucose transporter-2 (SGLT-2) inhibitors, IL-1β inhibitors, and metformin may be promising drugs for repurposing to treat multi morbidity. We propose that targeting the metabolic and inflammatory pathways that are common to HF and comorbidities may provide a promising therapeutic strategy.

In silico Analysis of Polymorphisms in microRNAs Deregulated in Alzheimer Disease

BACKGROUND

Alzheimer's disease (AD) is a degenerative condition characterized by progressive cognitive impairment and dementia. Findings have revolutionized current knowledge of miRNA in the neurological conditions. Two regulatory mechanisms determine the level of mature miRNA expression; one is miRNA precursor processing, and the other is gene expression regulation by transcription factors. This study is allocated to the in-silico investigation of miRNA's SNPs and their effect on other cell mechanisms.

METHODS

We used databases which annotate the functional effect of SNPs on mRNA-miRNA and miRNA-RBP interaction. Also, we investigated SNPs which are located on the promoter or UTR region.

RESULTS

miRNA SNP3.0 database indicated several SNPs in miR-339 and miR-34a in the upstream and downstream of pre-miRNA and mature miRNAs. While, for some miRNAs miR-124, and miR-125, no polymorphism was observed, and also miR-101 with ΔG -3.1 and mir-328 with ΔG 5.8 had the highest and lowest potencies to produce mature microRNA. SNP2TFBS web-server presented several SNPs which altered the Transcription Factor Binding Sites (TFBS) or generated novel TFBS in the promoter regions of related miRNA. At last, RBP-Var database provided a list of SNPs which alter miRNA-RBP interaction pattern and can also influence other miRNAs' expression.

DISCUSSION

The results indicated that SNPs microRNA affects both miRNA function and miRNA expression. Our study expands molecular insight into how SNPs in different parts of miRNA, including the regulatory (promoter), the precursor (pre-miRNA), functional regions (seed region of mature miRNA), and RBP-binding motifs, which theoretically may be correlated to the Alzheimer's disease.

Poly ethylene glycol (PEG)-Related controllable and sustainable antidiabetic drug delivery systems

Diabetes mellitus is one of the most challenging threats to global public health. To improve the therapy efficacy of antidiabetic drugs, numerous drug delivery systems have been developed. Polyethylene glycol (PEG) is a polymeric family sharing the same skeleton but with different molecular weights which is considered as a promising material for drug delivery. In the delivery of antidiabetic drugs, PEG captures much attention in the designing and preparation of sustainable and controllable release systems due to its unique features including hydrophilicity, biocompatibility and biodegradability. Due to the unique architecture, PEG molecules are also able to shelter delivery systems to decrease their immunogenicity and avoid undesirable enzymolysis. PEG has been applied in plenty of delivery systems such as micelles, vesicles, nanoparticles and hydrogels. In this review, we summarized several commonly used PEG-contained antidiabetic drug delivery systems and emphasized the advantages of stimuli-responsive function in these sustainable and controllable formations.

Screening Traditional Chinese Medicine Combination for Cotreatment of Alzheimer's Disease and Type 2 Diabetes Mellitus by Network Pharmacology

BACKGROUND

In recent years, the efficacy of type 2 diabetes mellitus (T2DM) drugs in the treatment of Alzheimer's disease (AD) has attracted extensive interest owing to the close associations between the two diseases.

OBJECTIVE

Here, we screened traditional Chinese medicine (TCM) and multi-target ingredients that may have potential therapeutic effects on both T2DM and AD from T2DM prescriptions.

METHODS

Network pharmacology and molecular docking were used.

RESULTS

Firstly, the top 10 frequently used herbs and corresponding 275 active ingredients were identified from 263 T2DM-related TCM prescriptions. Secondly, through the comparative analysis of 208 potential targets of ingredients, 1,740 T2DM-related targets, and 2,060 AD-related targets, 61 common targets were identified to be shared. Thirdly, by constructing pharmacological network, 26 key targets and 154 representative ingredients were identified. Further enrichment analysis showed that common targets were involved in regulating multiple pathways related to T2DM and AD, while network analysis also found that the combination of Danshen (Radix Salviae)-Gancao (Licorice)-Shanyao (Rhizoma Dioscoreae) contained the vast majority of the representative ingredients and might be potential for the cotreatment of the two diseases. Fourthly, MAPK1, PPARG, GSK3B, BACE1, and NR3C1 were selected as potential targets for virtual screening of multi-target ingredients. Further docking studies showed that multiple natural compounds, including salvianolic acid J, gancaonin H, gadelaidic acid, icos-5-enoic acid, and sigmoidin-B, exhibited high binding affinities with the five targets.

CONCLUSION

To summarize, the present study provides a potential TCM combination that might possess the potential advantage of cotreatment of AD and T2DM.

Accelerated MRI-predicted brain ageing and its associations with cardiometabolic and brain disorders

Brain structure in later life reflects both influences of intrinsic aging and those of lifestyle, environment and disease. We developed a deep neural network model trained on brain MRI scans of healthy people to predict "healthy" brain age. Brain regions most informative for the prediction included the cerebellum, hippocampus, amygdala and insular cortex. We then applied this model to data from an independent group of people not stratified for health. A phenome-wide association analysis of over 1,410 traits in the UK Biobank with differences between the predicted and chronological ages for the second group identified significant associations with over 40 traits including diseases (e.g., type I and type II diabetes), disease risk factors (e.g., increased diastolic blood pressure and body mass index), and poorer cognitive function. These observations highlight relationships between brain and systemic health and have implications for understanding contributions of the latter to late life dementia risk.

Insulin resistance and bioenergetic manifestations: Targets and approaches in Alzheimer's disease

AIM

Insulin has a well-established role in cognition, neuronal detoxification and synaptic plasticity. Insulin transduction affect neurotransmitter functions, influence bioenergetics and regulate neuronal survival through regulating glucose energy metabolism and downward pathways.

METHODS

A systematic literature review of PubMed, Medline, Bentham, Scopus and EMBASE (Elsevier) databases was carried out with the help of the keywords like "Alzheimer's disease; Hypometabolism; Oxidative stress; energy failure in AD, Insulin; Insulin resistance; Bioenergetics" till June 2020. The review was conducted using the above keywords to collect the latest articles and to understand the nature of the extensive work carried out on insulin resistance and bioenergetic manifestations in Alzheimer's disease.

KEY FINDINGS

The article sheds light on insulin resistance mediated hypometabolic state on pathological progression of AD. The disrupted insulin signaling has pathological outcome in form of disturbed glucose homeostasis, altered bioenergetic state which increases build-up of senile plaques (Aβ), neurofibrillary tangles (τ), decline in transportation of glucose and activation of inflammatory pathways. The mechanistic link of insulin resistant state with therapeutically explorable potential transduction pathways is the focus of the reviewed work.

SIGNIFICANCE

The present work opines that the mechanism by which the insulin resistance mediates dysregulation of bioenergetics and progresses to neurodegenerative state holds the tangible potential to succeed in the development of novel dementia therapies. Further, hypometabolic complications and altered insulin signaling may be explored as a mechanistic relation between bioenergetic deficits and AD.

Evaluation of the neuroprotective effect of donepezil in type 2 diabetic rats

Recent studies raise the possibility that donepezil can delay the progression of Alzheimer's disease (AD). This research evaluated the efficacy of donepezil in an animal model with brain insulin resistance and AD-like alterations. Rats were fed with high-fat/high-fructose (HF/Hfr) diet during the study period (17 weeks) and received one injection of streptozotocin (STZ) (25 mg/kg) after 8 weeks of starting the study. Diabetic (T2D) rats were treated with donepezil (4 mg/kg; p.o.) or vehicle for 8 weeks after STZ injection. The influence of donepezil on AD-related behavioral, biochemical, and neuropathological changes was investigated in T2D rats. Treatment of diabetic rats with donepezil led to a significant decrease in both amyloid-β deposition and the raised hippocampal activity of cholinesterase (ChE). It significantly increased the suppressed glutamate receptor expression (AMPA GluR1 subunit and NMDA receptor subunits NR1, NR2A, NR2B). It also improved cognitive dysfunction in the passive avoidance and the Morris water maze tests. However, donepezil treatment did not significantly decrease the elevated levels of P-tau, caspase-3, GSK-3β, MDA, TNF-α, and IL-1β in the hippocampus of diabetic rats. Also, it did not restore the suppressed levels of glutathione and superoxide dismutase in the brain of these rats. Moreover, donepezil did not alter the elevated serum level of glucose, insulin, and total cholesterol. These findings suggest that donepezil treatment could ameliorate learning and memory impairment in T2D rats through reversal of some of the AD-related alterations, including reduction of amyloid-β burden and ChE activity as well as restoration of glutamate receptor expression. However, lack of any significant effect on P-tau load, oxidative stress, neuroinflammation, and insulin resistance raises the question about the ability of donepezil to delay the development or arrest the progression of T2D-induced AD and it is still a matter of debate that requires further studies.