Breakdown of the Cerebrovasculature and Blood-Brain Barrier: A Mechanistic Link Between Diabetes Mellitus and Alzheimer's Disease

Single nuclei transcriptomics in diabetic mice reveals altered brain hippocampal endothelial cell function, permeability, and behavior

Type 2 diabetes mellitus (T2DM) is a metabolic disorder with cerebrovascular and cardiovascular sequelae. Yet, a clear pattern of gene dysregulation by T2DM in dementia has yet to be defined. We used single nuclei RNA sequencing technology to profile the transcriptome of endothelial cells (EC) from anatomically defined hippocampus of db/db mice to identify differentially expressed (DE) genes, gene pathways and networks, predicted regulating transcription factors, and targets of DE long noncoding RNAs. We also applied gadolinium (Gd) enhanced magnetic resonance imaging (MRI) to assess blood brain barrier (BBB) permeability, and functionally assessed cognitive behavior. The murine gene expression profiles were then integrated with those of persons with Alzheimer's disease (AD) and vascular dementia (VaD). We reveal that the transcriptome of the diabetic hippocampal murine brain endothelium differs substantially from control wild types with molecular changes characterized by differential RNA coding and noncoding pathways enriched for EC signaling and for endothelial functions for neuroinflammation, endothelial barrier disruption, and neurodegeneration. Gd enhanced structural brain MRI linked endothelial molecular alterations to BBB dysfunction by neuroimaging. Integrated multiomics of hippocampal endothelial gene dysregulation associated with impairments in cognitive adaptive capacity. In addition, the diabetic transcriptome significantly and positively correlated with that of persons with AD and VaD. Taken together, our results from comprehensive, multilevel, integrated, single nuclei transcriptomics support the hypothesis of T2DM-mediated neuroinflammation and endothelial cell and barrier disruption as key mechanisms in cognitive decline in T2DM, thereby suggesting potential endothelial-specific molecular therapeutic targets.

A Chronic Increase in Blood-Brain Barrier Permeability Facilitates Intraneuronal Deposition of Exogenous Bloodborne Amyloid-Beta1-42 Peptide in the Brain and Leads to Alzheimer's Disease-Relevant Cognitive Changes in a Mouse Model

Background

Increased blood-brain barrier (BBB) permeability and amyloid-β (Aβ) peptides (especially Aβ1-42) (Aβ42) have been linked to Alzheimer's disease (AD) pathogenesis, but the nature of their involvement in AD-related neuropathological changes leading to cognitive changes remains poorly understood.

Objective

To test the hypothesis that chronic extravasation of bloodborne Aβ42 peptide and brain-reactive autoantibodies and their entry into the brain parenchyma via a permeable BBB contribute to AD-related pathological changes and cognitive changes in a mouse model.

Methods

The BBB was rendered chronically permeable through repeated injections of Pertussis toxin (PT), and soluble monomeric, fluorescein isothiocyanate (FITC)-labeled or unlabeled Aβ42 was injected into the tail-vein of 10-month-old male CD1 mice at designated intervals spanning ∼3 months. Acquisition of learned behaviors and long-term retention were assessed via a battery of cognitive and behavioral tests and linked to neuropathological changes.

Results

Mice injected with both PT and Aβ42 demonstrated a preferential deficit in the capacity for long-term retention and an increased susceptibility to interference in selective attention compared to mice exposed to PT or saline only. Immunohistochemical analyses revealed increased BBB permeability and entry of bloodborne Aβ42 and immunoglobulin G (IgG) into the brain parenchyma, selective neuronal binding of IgG and neuronal accumulation of Aβ42 in animals injected with both PT and Aβ42 compared to controls.

Conclusion

Results highlight the potential synergistic role of BBB compromise and the influx of bloodborne Aβ42 into the brain in both the initiation and progression of neuropathologic and cognitive changes associated with AD.

The Role of Insulin-like Growth Factor I in Mechanisms of Resilience and Vulnerability to Sporadic Alzheimer's Disease

Despite decades of intense research, disease-modifying therapeutic approaches for Alzheimer's disease (AD) are still very much needed. Apart from the extensively analyzed tau and amyloid pathological cascades, two promising avenues of research that may eventually identify new druggable targets for AD are based on a better understanding of the mechanisms of resilience and vulnerability to this condition. We argue that insulin-like growth factor I (IGF-I) activity in the brain provides a common substrate for the mechanisms of resilience and vulnerability to AD. We postulate that preserved brain IGF-I activity contributes to resilience to AD pathology as this growth factor intervenes in all the major pathological cascades considered to be involved in AD, including metabolic impairment, altered proteostasis, and inflammation, to name the three that are considered to be the most important ones. Conversely, disturbed IGF-I activity is found in many AD risk factors, such as old age, type 2 diabetes, imbalanced diet, sedentary life, sociality, stroke, stress, and low education, whereas the Apolipoprotein (Apo) E4 genotype and traumatic brain injury may also be influenced by brain IGF-I activity. Accordingly, IGF-I activity should be taken into consideration when analyzing these processes, while its preservation will predictably help prevent the progress of AD pathology. Thus, we need to define IGF-I activity in all these conditions and develop a means to preserve it. However, defining brain IGF-I activity cannot be solely based on humoral or tissue levels of this neurotrophic factor, and new functionally based assessments need to be developed.

The retina-brain axis and diabetic retinopathy

Diabetic retinopathy (DR) is a major contributor to permanent vision loss and blindness. Changes in retinal neurons, glia, and microvasculature have been the focus of intensive study in the quest to better understand DR. However, the impact of diabetes on the rest of the visual system has received less attention. There are reports of associations of changes in the visual system with preclinical and clinical manifestations of diabetes. Simultaneous investigation of the retina and the brain may shed light on the mechanisms underlying neurodegeneration in diabetics. Additionally, investigating the links between DR and other neurodegenerative disorders of the brain including Alzheimer's and Parkinson's disease may reveal shared mechanisms for neurodegeneration and potential therapy options.

Bibliometric and visual analysis of diabetes mellitus and pyroptosis from 2011 to 2022

OBJECTIVE

To visualize and analyze the published literature on diabetes mellitus and pyroptosis based on a bibliometric approach, so as to provide a comprehensive picture of the hot research directions and dynamic progress in this field.

METHODS

This study was based on the web of science core collection database to conduct a comprehensive search of the published literature in the field of diabetes mellitus and Pyroptosis from January 1985 to August 2022, including the published research literature in this field, as well as a visual analysis of the number of citations, year of publication, journal, author, research institution, country, and research topic.

RESULTS

A total of 139 literature on research related to diabetes mellitus and cellular scorch from 2011 to 2022 were retrieved, with a total of 3009 citations and a maximum of 255 citations for a single article, which had a first author Schmid-Burgk, JL The first author of this article is from Germany; among 20 publishing countries, China leads with 100 articles; among 222 publishing institutions, Harbin Medical University leads with 18 articles and 184 citations; among 980 authors, Chen, X from China tops the list of high-impact authors with 5 articles and 29 citations. Among the 98 journals, "CELL DEATH DISEASE" ranked first in both volume and high-impact journals with 4 articles and 29 citations. Among 349 keywords, "pyroptosis" ranked first with a cumulative frequency of 65 times. The cluster analysis was divided into three categories, chronic complications of diabetes mellitus and pyroptosis (67 articles), diabetes mellitus and pyroptosis (60 articles), and diabetes mellitus combined with other diseases and pyroptosis (12 articles), and the number of articles related to diabetes mellitus and its chronic complications increased rapidly from 2019, among which, diabetic cardiomyopathy (27 articles) had the highest number of articles.

CONCLUSIONS

Based on a comprehensive analysis of published literature in the field of diabetes mellitus and pyroptosis from 2011 to 2022, this study achieved a visual analysis of studies with significant and outstanding contributions to the field, thus framing a picture showing the development and changes in the field. At the same time, this study provides research information and direction for clinicians and investigators to conduct diabetes mellitus and pyroptosis-related research in the future.

Novel insights into non-alcoholic fatty liver disease and dementia: insulin resistance, hyperammonemia, gut dysbiosis, vascular impairment, and inflammation

Non-alcoholic fatty liver disease (NAFLD) is a metabolic disease characterized by multiple pathologies. The progression of dementia with NAFLD may be affected by various risk factors, including brain insulin resistance, cerebrovascular dysfunction, gut dysbiosis, and neuroinflammation. Many recent studies have focused on the increasing prevalence of dementia in patients with NAFLD. Dementia is characterized by cognitive and memory deficits and has diverse subtypes, including vascular dementia, Alzheimer’s dementia, and diabetes mellitus-induced dementia. Considering the common pathological features of NAFLD and dementia, further studies on the association between them are needed to find appropriate therapeutic solutions for diseases. This review summarizes the common pathological characteristics and mechanisms of NAFLD and dementia. Additionally, it describes recent evidence on association between NAFLD and dementia progression and provides novel perspectives with regard to the treatment of patients with dementia secondary to NAFLD.

Identification and Experimental Validation of Marker Genes between Diabetes and Alzheimer’s Disease

Currently, Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) are widely prevalent in the elderly population, and accumulating evidence implies a strong link between them. For example, patients with T2DM have a higher risk of developing neurocognitive disorders, including AD, but the exact mechanisms are still unclear. This time, by combining bioinformatics analysis and in vivo experimental validation, we attempted to find a common biological link between AD and T2DM. We firstly downloaded the gene expression profiling (AD: GSE122063; T2DM: GSE161355) derived from the temporal cortex. To find the associations, differentially expressed genes (DEGs) of the two datasets were filtered and intersected. Based on them, enrichment analysis was carried out, and the least absolute shrinkage and selection operator (LASSO) logistic regression and support vector machine-recursive feature elimination (SVM-RFE) algorithms were used to identify the specific genes. After verifying in the external dataset and in the samples from the AD and type 2 diabetes animals, the shared targets of the two diseases were finally determined. Based on them, the ceRNA networks were constructed. Besides, the logistic regression and single-sample gene set enrichment analysis (ssGSEA) were performed. As a result, 62 DEGs were totally identified between AD and T2DM, and the enrichment analysis indicated that they were much related to the function of synaptic vesicle and MAPK signaling pathway. Based on the evidence from external dataset and RT-qPCR, CARTPT, EPHA5, and SERPINA3 were identified as the marker genes in both diseases, and their clinical significance and biological functions were further analyzed. In conclusion, discovering and exploring the marker genes that are dysregulated in both 2 diseases could help us better comprehend the intrinsic relationship between T2DM and AD, which may inspire us to develop new strategies for facing the dilemmas of clinical or basic research in cognitive dysfunction.

A Preliminary Report: The Hippocampus and Surrounding Temporal Cortex of Patients With Schizophrenia Have Impaired Blood-Brain Barrier

Though hippocampal volume reduction is a pathological hallmark of schizophrenia, the molecular pathway(s) responsible for this degeneration remains unknown. Recent reports have suggested the potential role of impaired blood-brain barrier (BBB) function in schizophrenia pathogenesis. However, direct evidence demonstrating an impaired BBB function is missing. In this preliminary study, we used immunohistochemistry and serum immunoglobulin G (IgG) antibodies to investigate the state of BBB function in formalin-fixed postmortem samples from the hippocampus and surrounding temporal cortex of patients with schizophrenia (n = 25) and controls without schizophrenia (n = 27) matched for age, sex, and race. Since a functional BBB prevents the extravasation of IgGs, detection of IgGs in the parenchyma is used as direct evidence of BBB breakdown. We also developed a semi-quantitative approach to quantify the extent of IgG leak and therein BBB breach. Analysis of our immunohistochemistry data demonstrated a significantly higher incidence of IgG leak in patients with schizophrenia compared to controls. Further, BBB permeability was significantly higher in advanced-age patients with schizophrenia than both advanced-age controls and middle-aged patients with schizophrenia. Male patients with schizophrenia also demonstrated a significant increase in IgG permeability compared to control males. Interestingly, the extravasated IgGs also demonstrated selective immunoreactivity for neurons. Based on these observations, we suggest that BBB dysfunction and IgG autoantibodies could be two key missing pathoetiological links underwriting schizophrenia hippocampal damage.

Deep phenotyping of Alzheimer's disease leveraging electronic medical records identifies sex-specific clinical associations

Alzheimer's Disease (AD) is a neurodegenerative disorder that is still not fully understood. Sex modifies AD vulnerability, but the reasons for this are largely unknown. We utilize two independent electronic medical record (EMR) systems across 44,288 patients to perform deep clinical phenotyping and network analysis to gain insight into clinical characteristics and sex-specific clinical associations in AD. Embeddings and network representation of patient diagnoses demonstrate greater comorbidity interactions in AD in comparison to matched controls. Enrichment analysis identifies multiple known and new diagnostic, medication, and lab result associations across the whole cohort and in a sex-stratified analysis. With this data-driven method of phenotyping, we can represent AD complexity and generate hypotheses of clinical factors that can be followed-up for further diagnostic and predictive analyses, mechanistic understanding, or drug repurposing and therapeutic approaches.

HMGB1 plays an important role in pyroptosis induced blood brain barrier breakdown in diabetes-associated cognitive decline

Diabetes mellitus increases the risk of dementia, and evidence suggests hyperglycemia is a key contributor to neurodegeneration. However, our understanding of diabetes-associated cognitive decline, an important complication of diabetes mellitus, is lacking and the underlying mechanism is unclear. Blood brain barrier (BBB) breakdown is a possible cause of dementia in diabetes mellitus and Alzheimer's disease. Accumulating evidence shows BBB dysfunction caused by hyperglycemia contributes to cognitive decline. A specific type of inflammatory programmed cell death, called pyroptosis, has potential as a therapeutic target for BBB-associated diseases. Potential inducers of pyroptosis include inflammasomes such as NLRP3, whose activation relies on damage-associated molecular patterns. High mobility group box 1 (HMGB1) is a highly conserved, ubiquitous protein found in most cell types, and acts as a damage-associated molecular pattern when released from the nucleus. We propose that HMGB1 influences vascular inflammation by activating the NLRP3 inflammasome and thereby initiating pyroptosis in vascular cells. Moreover, HMGB1 plays a pivotal role in the pathogenesis of diabetes mellitus and diabetic complications. Here, we review the role of HMGB1 in BBB dysfunction induced by hyperglycemia and propose that HMGB1 is a promising therapeutic target for countering diabetes-associated cognitive decline.

A comprehensive review on RAGE-facilitated pathological pathways connecting Alzheimer’s disease, diabetes mellitus, and cardiovascular diseases

Background

Alzheimer’s disease (AD), cardiovascular disease (CVD), and diabetes are some of the most common causes of morbidity and mortality among the aging populations and cause a heavy burden on the worldwide healthcare system. In this review, we briefly highlighted cellular inflammation-based pathways of diabetes mellitus and CVD through receptor for advanced glycation end products AGEs or RAGE leading to Alzheimer’s disease and interrelation between these vascular and metabolic disorders. The articles were retrieved from Google Scholar, Science Direct, and PubMed databases using the following terms: Alzheimer’s; AGEs; RAGE; RAGE in Alzheimer’s; AGEs in Alzheimer’s; RAGE in diabetes; RAGE related pathways of CVD; RAGE in hypertension; RAGE and RAS system; RAGE and oxidative stress.

Main body of the abstract

AD is a neurodegenerative disease characterized by cognitive dysfunction and neuronal cell death. Vascular complications like hypertension, coronary artery disease, and atherosclerosis as well as metabolic syndromes like obesity and diabetes are related to the pathophysiology of AD. RAGE plays significant role in the onset and progression of AD. Amyloid plaques and neurofibrillary tangles (NFT) are two main markers of AD that regulates via RAGE and other RAGE/ligands interactions which also induces oxidative stress and a cascade of other cellular inflammation pathways leading to AD. Though AD and diabetes are two different disorders but may be inter-linked by AGEs and RAGE. In long-term hyperglycemia, upregulated AGEs interacts with RAGE and produces reactive oxygen species which induces further inflammation and vascular complications. Aging, hypercholesterolemia, atherosclerosis, hypertension, obesity, and inflammation are some of the main risk factors for both diabetes and dementia. Chronic hypertension and coronary artery disease disrupt the functions of the blood-brain barrier and are responsible for the accumulation of senile plaques and NFTs.

Short conclusion

RAGE plays a role in the etiology of Aβ and tau hyperphosphorylation, both of which contribute to cognitive impairment. So far, targeting RAGE may provide a potential sight to develop therapies against some metabolic disorders.

First clinical assessment of [18F]MC225, a novel fluorine-18 labelled PET tracer for measuring functional P-glycoprotein at the blood-brain barrier

OBJECTIVE

5-(1-(2-[¹⁸F]fluoroethoxy))-[3-(6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl)-propyl]-5,6,7,8-tetrahydronaphthalen ([¹⁸F]MC225) is a selective substrate for P-glycoprotein (P-gp), possessing suitable properties for measuring overexpression of P-gp in the brain. This is the first-in-human study to examine safety, radiation dosimetry and P-gp function at the blood-brain barrier (BBB) of [¹⁸F]MC225 in healthy subjects.

METHODS

[¹⁸F]MC225 biodistribution and dosimetry were determined in 3 healthy male subjects, using serial 2 h and intermittent 4 and 6 h whole-body PET scans acquired after [¹⁸F]MC225 injection. Dynamic [¹⁸F]MC225 brain PET (90 min) was obtained in 5 healthy male subjects. Arterial blood was sampled at various time intervals during scanning and the fraction of unchanged [¹⁸F]MC225 in plasma was determined. T1-weighted MRI was performed for anatomical coregistration. Total distribution volume (V_T) was estimated using 1- and 2-tissue-compartment models (1-TCM and 2-TCM, respectively). V_T was also estimated using the Logan graphical method (Logan plot) (t* = 20 min). Surrogate parameters without blood sampling (area-under the curve [AUC] of regional time-activity curves [TACs] and negative slope of calculated TACs) were compared with the V_T values.

RESULTS

No serious adverse events occurred throughout the study period. Although biodistribution implied hepatobiliary excretion, secretion of radioactivity from liver to small intestine through the gallbladder was very slow. Total renal excreted radioactivity recovered during 6 h after injection was < 2%ID. Absorbed dose was the highest in the pancreas (mean ± SD, 203 ± 45 μGy/MBq) followed by the liver (83 ± 11 μGy/MBq). Mean effective dose with and without urination was 17 ± 1 μSv/MBq. [¹⁸F]MC225 readily entered the brain, distributing homogeneously in grey matter regions. 2-TCM provided lower Akaike information criterion scores than did 1-TCM. V_T estimated by Logan plot was well correlated with that of 2-TCM (r² > 0.9). AUCs of TACs were positively correlated with V_T (2-TCM) values (r²: AUC_0-60 min = 0.61, AUC_0-30 min = 0.62, AUC_30-60 min = 0.59, p < 0.0001). Negative slope of SUV TACs was negatively correlated with V_T (2-TCM) values (r² = 0.53, p < 0.0001).

CONCLUSIONS

This initial evaluation indicated that [¹⁸F]MC225 is a suitable and safe PET tracer for measuring P-gp function at the BBB.

Metabolomics in Diabetic Retinopathy: A Systematic Review

Purpose

Diabetic retinopathy (DR), a common microvascular complication of diabetes, is the leading cause of acquired blindness in the working-age population. Individuals with diabetes still develop DR despite appropriate glycemic and blood pressure control, highlighting the pressing need to identify useful biomarkers for risk stratification. The purpose of this review is to systematically summarize potential metabolic biomarkers and pathways of DR, which could facilitate developing an understanding of the disease mechanisms, as well as new therapeutic measures.

Methods

We searched PubMed and Web of Science for relevant metabolomics studies on humans published before September 30, 2020. Information regarding authors, title, publication date, study subjects, analytical platforms, methods of statistical analysis, biological samples, directions of change of potential metabolic biomarkers, and predictive values of metabolic biomarker panels was extracted, and the quality of the studies was assessed. Pathway analysis, including enrichment analysis and topology analysis, was derived from integrating differential metabolites using MetaboAnalyst 3.0, based on the Kyoto Encyclopedia of Genes and Genomes and Human Metabolome Database.

Results

We found nine studies focused on the identification of potential biomarkers. Repeatedly identified metabolites including l-glutamine, l-lactic acid, pyruvic acid, acetic acid, l-glutamic acid, d-glucose, l-alanine, l-threonine, citrulline, l-lysine, and succinic acid were found to be potential biomarkers of DR. It was observed that l-glutamine and citrulline changed in all biological samples. Dysregulation of metabolic pathways involved amino acid and energy metabolism.

Conclusions

This review summarizes potential biomarkers and metabolic pathways, providing insights into new pathogenic pathways for this microvascular complication of diabetes.

Microvascular basis of cognitive impairment in type 1 diabetes

The complex computations of the brain require a constant supply of blood flow to meet its immense metabolic needs. Perturbations in blood supply, even in the smallest vascular networks, can have a profound effect on neuronal function and cognition. Type 1 diabetes is a prevalent and insidious metabolic disorder that progressively and heterogeneously disrupts vascular signalling and function in the brain. As a result, it is associated with an array of adverse vascular changes such as impaired regulation of vascular tone, pathological neovascularization and vasoregression, capillary plugging and blood brain barrier disruption. In this review, we highlight the link between microvascular dysfunction and cognitive impairment that is commonly associated with type 1 diabetes, with the aim of synthesizing current knowledge in this field.

Additive interaction of mid- to late-life depression and cerebrovascular disease on the risk of dementia: a nationwide population-based cohort study

Background

Dementia is a progressive neurocognitive disease with a substantial social burden. No apparent breakthroughs in treatment options have emerged so far; thus, disease prevention is essential for at-risk populations. Depression and cerebrovascular disease (CVD) are independent risk factors for dementia, but no studies have examined their interaction effect on dementia risk. This study aimed to identify the association of depression and CVD with the risk of dementia and evaluate whether dementia risk among patients with comorbid depression and CVD is higher than the sum of the individual risk due to each condition.

Methods

A population-based cohort study was conducted to analyze the Korean National Health Insurance Service-National Sample Cohort data of all individuals over 50 years of age. Individuals who had not been diagnosed with dementia at baseline were included and followed up from January 1, 2005, to December 31, 2013. A time-varying Cox proportional hazard regression model adjusted for potential confounding factors was used for the analysis. The interaction between depression and CVD was estimated based on the attributable proportion (AP), relative excess risk due to interaction (RERI), synergy index (SI), and multiplicative-scale interaction.

Results

A total of 242,237 participants were included in the analytical sample, of which 12,735 (5.3%) developed dementia. Compared to that for participants without depression or CVD, the adjusted hazard ratio for the incidence of dementia for those with depression alone was 2.35 (95% confidence interval [CI] 2.21–2.49), CVD alone was 3.25 (95% CI 3.11–3.39), and comorbid depression and CVD was 5.02 (95% CI 4.66–5.42). The additive interaction between depression and CVD was statistically significant (AP—0.08, 95% CI 0.01–0.16; RERI—0.42, 95% CI 0.03–0.82; SI—1.12, 95% CI 1.01–1.24). The multiplicative interaction was significant too, but the effect was negative (0.66, 95% CI 0.60–0.73).

Conclusions

In this population-based nationwide cohort with long-term follow-up, depression and CVD were associated with an increased risk of dementia, and their coexistence additively increased dementia risk more than the sum of the individual risks.

Impact of diabetes mellitus and cardiometabolic syndrome on the risk of Alzheimer’s disease among postmenopausal women

BACKGROUND

In spite of an increase in the incidence and prevalence of diabetes mellitus (DM) and Alzheimer’s disease (AD) in the aging population worldwide, limited attention has been paid to their potential association.

AIM

To investigate the association of DM and cardiometabolic syndrome (CMS, a precursor to DM) with risk of incident AD among postmenopausal women.

METHODS

Postmenopausal women aged 50-79 (n = 63117) who participated in the U.S. Women’s Health Initiative Observational Study (WHIOS), recruited in 1993-1998, without baseline AD and followed up through March 1, 2019, were analyzed. AD was classified by participant-reported history of doctor-diagnosis of incident AD in the WHIOS. DM was defined by participant-report or treated because of diabetes or serum glucose concentrations ≥ 126 mg/dL. CMS was defined as having ≥ 3 of five CMS components: large waist circumference, high blood pressure, elevated triglycerides, elevated glucose, and low high-density lipoprotein cholesterol. The associations of DM and CMS with AD were analyzed using Cox’s proportional hazards regression analysis.

RESULTS

During a median follow-up of 20 years (range: 3.36 to 23.36 years), of 63117 participants, 8340 developed incident AD. Women with DM had significantly higher incidence of AD [8.5, 95% confidence interval (CI): 8.0-9.0 per 1000 person-years (PY)] than those without DM (7.1, 95%CI: 6.9-7.2 per 1000 PY). Multivariate Cox’s regression analysis indicated that women with DM or CMS had a significantly higher risk of AD than those without DM or CMS. The corresponding hazard ratios [HR (95%CI)] were 1.22 (1.13-1.31, P < 0.001) in subjects with DM, and 1.18 (1.09-1.27, P < 0.001) in subjects with CMS. The HRs diminished with age and became non-significant in the oldest age group.

CONCLUSION

During a median follow-up of 20 years, DM and CMS were significantly associated with the risk of AD among postmenopausal women. More specifically, women aged 50-69 with DM or CMS vs those without these conditions had significantly higher relative risks of AD than the relative risks of AD in those aged 70-79 with DM or CMS vs those without DM or CMS.

Aggregation of Vascular Risk Factors Modulates the Amplitude of Low-Frequency Fluctuation in Mild Cognitive Impairment Patients

Background: Several vascular risk factors, including hypertension, diabetes, body mass index, and smoking status are found to be associated with cognitive decline and the risk of Alzheimer's disease (AD). We aimed to investigate whether an aggregation of vascular risk factors modulates the amplitude of low-frequency fluctuation (ALFF) in patients with mild cognitive impairment (MCI).

Methods: Forty-three MCI patients and twenty-nine healthy controls (HCs) underwent resting-state functional MRI scans, and spontaneous brain activity was measured by the ALFF technique. The vascular risk profile was represented with the Framingham Heart Study general cardiovascular disease (FHS-CVD) risk score, and each group was further divided into high and low risk subgroups. Two-way ANOVA was performed to explore the main effects of diagnosis and vascular risk and their interaction on ALFF.

Results: The main effect of diagnosis on ALFF was found in left middle temporal gyrus (LMTG) and left superior parietal gyrus (LSPG), and the main effect of risk on ALFF was detected in left fusiform gyrus (LFFG), left precuneus (LPCUN), and left cerebellum posterior lobe (LCPL). Patients with MCI exhibited increased ALFF in the LMTG and LSPG than HCs, and participants with high vascular risk showed increased ALFF in the LFFG and LCPL, while decreased ALFF in the LPCUN. An interaction between diagnosis (MCI vs. HC) and FHS-CVD risk (high vs. low) regarding ALFF was observed in the left hippocampus (LHIP). HCs with high vascular risk showed significantly increased ALFF in the LHIP than those with low vascular risk, while MCI patients with high vascular risk showed decreased ALFF in the LHIP than HCs with high vascular risk. Interestingly, the mean ALFF of LHIP positively correlated with word recall test in HCs with high vascular risk (rho = 0.630, P = 0.016), while negatively correlated with the same test in MCI patients with high vascular risk (rho = −0.607, P = 0.001).

Conclusions: This study provides preliminary evidence highlighting that the aggregation of vascular risk factors modulates the spontaneous brain activity in MCI patients, and this may serve as a potential imaging mechanism underlying vascular contribution to AD.

Ophthalmology-Based Neuropathology Risk Factors: Diabetic Retinopathy is Associated with Deep Microinfarcts in a Community-Based Autopsy Study

BACKGROUND

The aging eye offers unique opportunities to study and understand the aging brain, in particular related to Alzheimer's disease (AD) and dementia. However, little is known about relationships between eye diseases and dementia-related neurodegeneration.

OBJECTIVE

To determine the potential association between three age-related eye diseases and AD and dementia-related neuropathology.

METHODS

We reviewed autopsy data from the prospective longitudinal Adult Changes in Thought (ACT) cohort. ICD-9 codes were used to identify diagnoses of diabetic retinopathy, glaucoma, and age-related macular degeneration. Multivariate regression models were used to determine odds ratios (OR) of neuropathology features associated with dementia, including Braak stage, Consortium to Establish a Registry for AD (CERAD score), Lewy bodies, hippocampal sclerosis, and microvascular brain injury, in addition to quantitative paired helical filament (PHF)-tau levels for people with and without each eye condition. We also evaluated interactions between eye conditions and dementia related neuropathologic findings were evaluated.

RESULTS

676 autopsies were included. Diabetic retinopathy was significantly associated with increased risk of deep cerebral microinfarcts (OR = 1.91 [95% confidence interval (CI) 1.11, 3.27], p = 0.02). No other significant association or interaction between eye diseases and neuropathology was found. When PHF-tau quantity was evaluated in 124 decedents, the OR for the association between PHF-tau in the occipital cortex and glaucoma was 1.36 (95% CI 0.91, 2.03, p = 0.13). No statistical correction was made for multiple comparisons.

CONCLUSION

Increased risk of deep cerebral microinfarcts was found in participants diagnosed with diabetic retinopathy. Eye diseases such as glaucoma may increase susceptibility to neurofibrillary tangles in the occipital cortex.

Understanding multifactorial brain changes in type 2 diabetes: a biomarker perspective

People with type 2 diabetes are at an increased risk of cognitive impairment and dementia (including Alzheimer's disease), as well as subtle forms of cognitive dysfunction. Current diabetes guidelines recommend screening for cognitive impairment in groups at high risk and providing guidance for diabetes management in patients with diabetes and cognitive impairment. Yet, no disease-modifying treatment is available and important questions remain about the mechanisms underlying diabetes-associated cognitive dysfunction. These mechanisms are likely to be multifactorial and different for subtle and more severe forms of diabetes-associated cognitive dysfunction. Over the past years, research on dementia, brain ageing, diabetes, and vascular disease has identified novel biomarkers of specific dementia aetiologies, brain parenchymal injury, and cerebral blood flow and metabolism. These markers shed light on the processes underlying diabetes-associated cognitive dysfunction, have clear applications in current research and increasingly in clinical diagnosis, and might ultimately guide targeted treatment.

Hyperglycemia and advanced glycation end products disrupt BBB and promote occludin and claudin-5 protein secretion on extracellular microvesicles

Cognitive impairment is a well-known complication of diabetes mellitus (DM). Microvascular compromise was described one DM complication. Recently we showed blood brain barrier (BBB) permeability and memory loss are associated with diminution of tight junctions (TJ) in brain endothelium and pericyte coverage and inflammation in cerebral microvessels and brain tissue paralleling hyperglycemia in mice of both DM types. The current study demonstrates that exposure of brain microvessels to hyperglycemic conditions or advanced glycation end products (AGEs) ex vivo resulted in significant abnormalities in membranous distribution of TJ proteins. We found significant increase in the amount of extracellular vesicles (EVs) isolated from DM mice and enhanced presence of TJ proteins, occludin and claudin-5, on EVs. Exposure of BMVECs to high glucose and AGEs led to significant augmentation of ICAM and VCAM expression, elevated leukocyte adhesion to and migration across BMVEC monolayers, and increased BBB permeability in vitro. Pericytes exposed to hyperglycemia and AGEs displayed diminished expression of integrin α1, PDGF-R1β and connexin-43. Our findings indicate BBB compromise in DM ex vivo, in vitro and in vivo models in association with BMVEC/pericyte dysfunction and inflammation. Prevention of BBB injury may be a new therapeutic approach to avert cognitive demise in DM.

Biomimetic Nanocarrier Targeting Drug(s) to Upstream-Receptor Mechanisms in Dementia: Focusing on Linking Pathogenic Cascades

Past published studies have already documented that, subsequent to the intravenous injection of colloidal lipid nanocarriers, apolipoprotein (apo)A-I is adsorbed from the blood onto the nanoparticle surface. The adsorbed apoA-I mediates the interaction of the nanoparticle with scavenger receptors on the blood-brain barrier (BBB), followed by receptor-mediated endocytosis and subsequent transcytosis across the BBB. By incorporating the appropriate drug(s) into biomimetic (lipid cubic phase) nanocarriers, one obtains a multitasking combination therapeutic which targets certain cell-surface scavenger receptors, mainly class B type I (i.e., SR-BI), and crosses the BBB. Documented similarities in lipid composition between naturally occurring high-density lipoproteins (HDL) and the artificial biomimetic (nanoemulsion) nanocarrier particles can partially simulate or mimic the known heterogeneity (i.e., subpopulations or subspecies) of HDL particles. Such biomedical application of colloidal drug-nanocarriers can potentially be extended to the treatment of complex medical disorders like dementia. The risk factors for dementia trigger widespread inflammation and oxidative stress; these two processes involve pathophysiological cascades which lead to neuronal Ca2+ increase, neurodegeneration, gradual cognitive/memory decline, and eventually (late-onset) dementia. In particular, more recent research indicates that chronic inflammatory stimulus in the gut may induce (e.g., via serum amyloid A (SAA)) the release of proinflammatory cytokines. Hence, an effective preventive and therapeutic strategy could be based upon drug targeting toward a major SAA receptor responsible for the SAA-mediated cell signaling events leading to cognitive decline and eventually Alzheimer's disease or (late-onset) dementia.

Nanotargeting of Drug(s) for Delaying Dementia: Relevance of Covid-19 Impact on Dementia

By incorporating appropriate drug(s) into lipid (biobased) nanocarriers, one obtains a combination therapeutic for dementia treatment that targets certain cell-surface scavenger receptors (mainly class B type I, or "SR-BI") and thereby crosses the blood-brain barrier. The cardiovascular risk factors for dementia trigger widespread inflammation -- which lead to neurodegeneration, gradual cognitive/memory decline, and eventually (late-onset) dementia. Accordingly, one useful strategy to delay dementia could be based upon nanotargeting drug(s), using lipid nanocarriers, toward a major receptor class responsible for inflammation-associated (cytokine-mediated) cell signaling events. At the same time, the immune response and excessive inflammation, commonly observed in the very recent human coronavirus (COVID-19) pandemic, may accelerate the progression of brain inflammatory neurodegeneration-which increases the probability of post-infection memory impairment and accelerating progression of Alzheimer's disease. Hence, the proposed multitasking combination therapeutic, using a (biobased) lipid nanocarrier, may also display greater effectiveness at different stages of dementia.

High levels of plasma fibrinogen are related to post-stroke cognitive impairment

INTRODUCTION

Studies have shown that high levels of the fibrinogen (FIB) are related to cognitive deficits. However, the relationship between fibrinogen and cognitive deficit after stroke remains unclear. Therefore, we explored the relationship between plasma fibrinogen and post-stroke cognitive impairment (PSCI).

METHODS

This study is carried out in the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, China. A total of 210 patients with acute ischemic stroke were enrolled in this study. Ultimately, 134 patients completed 3-month follow-up. Blood samples were collected at hospital admission. Cognitive function was evaluated 3 months after stroke. All patients underwent the Mini-Mental State Examination (MMSE) after 3 months.

RESULTS

Higher levels of fibrinogen were observed in patients with post-stroke cognitive impairment compared with the non-PSCI group (p < .001). Additionally, elevated plasma fibrinogen levels were independently associated with PSCI (odds ratio [OR] = 2.000, 95% CI 1.062-3.770 p = .032). The plasma fibrinogen levels were negatively correlated with the 3-month MMSE scores (r = -.171, p = .048). In a multivariate linear regression, FIB was negatively associated with the 3-month MMSE scores after adjustment for the other variables (β = -0.782, p = .035).

CONCLUSION

High levels of plasma fibrinogen were associated with the presence and severity of PSCI.

Relationships between objectives sleep parameters and brain amyloid load in subjects at risk for Alzheimer’s disease: the INSIGHT-preAD Study

Study Objectives

Sleep changes have been associated with increased risks of developing cognitive disturbances and Alzheimer’s disease (AD). A bidirectional relation is underlined between amyloid-beta (Aß) and sleep disruptions. The sleep profile in participants at risk to develop AD is not fully deciphered. We aim to investigate sleep–wake changes with objective sleep measurements in elderly participants without cognitive impairment depending on their brain amyloid status, positive (Aß+) or negative (Aß−) based on standard absorption ratios (SUVr) positron emission tomography-florbetapir imaging.

Methods

Sixty-eight participants without cognitive impairment who have accepted to be involved in the sleep ancillary study from the InveStIGation of Alzheimer’s Predictors in Subjective Memory Complainers (INSIGHT-pre AD) cohort, aiming to record sleep profile based on the analyses of an ambulatory accelerometer-based assessment (seven consecutive 24-hour periods). Neuropsychological tests were performed and sleep parameters have been individualized by actigraph. Participants also underwent a magnetic resonance imaging scan to assess their hippocampal volume. Based on SUVr PET-florbetapir imaging, two groups Aß+ and Aß− were compared.

Results

Participants were divided into two groups: Aß+ (n = 24) and Aß− (n = 44). Except for the SUVr, the two subgroups were comparable. When looking to sleep parameters, increased sleep latency, sleep fragmentation (wake after sleep onset [WASO] score and awakenings) and worst sleep efficiency were associated with cortical brain amyloid load.

Conclusion

Actigraphic sleep parameters were associated with cortical brain amyloid load in participants at risk to develop AD. The detection of sleep abnormalities in those participants may be of interest to propose some preventive strategies.

1H Nuclear Magnetic Resonance (NMR)-Based Cerebrospinal Fluid and Plasma Metabolomic Analysis in Type 2 Diabetic Patients and Risk Prediction for Diabetic Microangiopathy

Insulin resistance and metabolic derangement are present in patients with type 2 diabetes mellitus (T2DM). However, the metabolomic signature of T2DM in cerebrospinal fluid (CSF) has not been investigated thus far. In this prospective metabolomic study, fasting CSF and plasma samples from 40 T2DM patients to 36 control subjects undergoing elective surgery with spinal anesthesia were analyzed by ¹H nuclear magnetic resonance (NMR) spectroscopy. NMR spectra of CSF and plasma metabolites were analyzed and correlated with the presence of T2DM and diabetic microangiopathy (retinopathy, nephropathy, and neuropathy) using an area under the curve (AUC) estimation. CSF metabolomic profiles in T2DM patients vs. controls revealed significantly increased levels of alanine, leucine, valine, tyrosine, lactate, pyruvate, and decreased levels of histidine. In addition, a combination of alanine, histidine, leucine, pyruvate, tyrosine, and valine in CSF showed a superior correlation with the presence of T2DM (AUC:0.951), diabetic retinopathy (AUC:0.858), nephropathy (AUC:0.811), and neuropathy (AUC:0.691). Similar correlations also appeared in plasma profiling. These metabolic alterations in CSF suggest decreasing aerobic metabolism and increasing anaerobic glycolysis in cerebral circulation of patients with T2DM. In conclusion, our results provide clues for the metabolic derangements in diabetic central neuropathy among T2DM patients; however, their clinical significance requires further exploration.

Role of Blood-Brain Barrier in Alzheimer's Disease

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

Osteopathic Cranial Manipulative Medicine and the Blood-Brain Barrier: A Mechanistic Approach to Alzheimer Prevention

Recent studies have demonstrated that blood-brain barrier (BBB) dysfunction may be implicated in the pathogenesis of Alzheimer disease, thus establishing a link between disease manifestation and compromised neurovasculature. The authors identify relationships between Alzheimer disease and BBB breakdown, the response of the BBB to increased cerebral blood flow and shear stress, and the impact of osteopathic cranial manipulative medicine on cerebrovascular hemodynamics. They propose and review a rationale for future research to evaluate osteopathic cranial manipulative medicine as a preventive treatment for patients with illnesses of neurovascular origin.

Age-Associated Changes in the Immune System and Blood⁻Brain Barrier Functions

Age is associated with altered immune functions that may affect the brain. Brain barriers, including the blood-brain barrier (BBB) and blood-CSF barrier (BCSFB), are important interfaces for neuroimmune communication, and are affected by aging. In this review, we explore novel mechanisms by which the aging immune system alters central nervous system functions and neuroimmune responses, with a focus on brain barriers. Specific emphasis will be on recent works that have identified novel mechanisms by which BBB/BCSFB functions change with age, interactions of the BBB with age-associated immune factors, and contributions of the BBB to age-associated neurological disorders. Understanding how age alters BBB functions and responses to pathological insults could provide important insight on the role of the BBB in the progression of cognitive decline and neurodegenerative disease.

Hyperglycemia-Driven Neuroinflammation Compromises BBB Leading to Memory Loss in Both Diabetes Mellitus (DM) Type 1 and Type 2 Mouse Models

End organ injury in diabetes mellitus (DM) is driven by microvascular compromise (including diabetic retinopathy and nephropathy). Cognitive impairment is a well-known complication of DM types 1 and 2; however, its mechanism(s) is(are) not known. We hypothesized that blood-brain barrier (BBB) compromise plays a key role in cognitive decline in DM. Using a DM type 1 model (streptozotocin injected C57BL/6 mice) and type 2 model (leptin knockout obese db/db mice), we showed enhanced BBB permeability and memory loss (Y maze, water maze) that are associated with hyperglycemia. Gene profiling in isolated microvessels from DM type 1 animals demonstrated deregulated expression of 54 genes related to angiogenesis, inflammation, vasoconstriction/vasodilation, and platelet activation pathways by at least 2-fold (including eNOS, TNFα, TGFβ1, VCAM-1, E-selectin, several chemokines, and MMP9). Further, the magnitude of gene expression was linked to degree of cognitive decline in DM type 1 animals. Gene analysis in brain microvessels of DM type 2 db/db animals showed alterations of similar genes as in DM 1 model, some to an even greater extent. Neuropathologic analyses of brain tissue derived from DM mice showed microglial activation, expression of ICAM-1, and attenuated coverage of pericytes compared to controls. There was a significant upregulation of inflammatory genes in brain tissue in both DM models. Taken together, our findings indicate that BBB compromise in DM in vivo models and its association with memory deficits, gene alterations in brain endothelium, and neuroinflammation. Prevention of BBB injury may be a new therapeutic approach to prevent cognitive demise in DM.

Acute glucose fluctuation impacts microglial activity, leading to inflammatory activation or self-degradation

Diabetes mellitus is associated with an increased risk of Alzheimer’s dementia and cognitive decline. The cause of neurodegeneration in chronic diabetic patients remains unclear. Changes in brain microglial activity due to glycemic fluctuations may be an etiological factor. Here, we examined the impact of acute ambient glucose fluctuations on BV-2 microglial activity. Biochemical parameters were assayed and showed that the shift from normal glucose (NG; 5.5 mM) to high glucose (HG; 25 mM) promoted cell growth and induced oxidative/inflammatory stress and microglial activation, as evidenced by increased MTT reduction, elevated pro-inflammatory factor secretion (i.e., TNF-α and oxygen free radicals), and upregulated expression of stress/inflammatory proteins (i.e., HSP70, HO-1, iNOS, and COX-2). Also, LPS-induced inflammation was enlarged by an NG-to-HG shift. In contrast, the HG-to-NG shift trapped microglia in a state of metabolic stress, which led to apoptosis and autophagy, as evidenced by decreased Bcl-2 and increased cleaved caspase-3, TUNEL staining, and LC3B-II expression. These stress episodes were primarily mediated through MAPKs, PI3K/Akt, and NF-κB cascades. Our study demonstrates that acute glucose fluctuation forms the stress that alters microglial activity (e.g., inflammatory activation or self-degradation), representing a novel pathogenic mechanism for the continued deterioration of neurological function in diabetic patients.

Insulin Peptides as Mediators of the Impact of Life Style in Alzheimer's disease

The search for the cause of Alzheimer's disease (AD), that affects millions of people worldwide, is currently one of the most important scientific endeavors from a clinical perspective. There are so many mechanisms proposed, and so disparate changes observed, that it is becoming a challenging task to provide a comprehensive view of possible pathogenic processes in AD. Tauopathy (intracellular neurofibrillary tangles) and amyloidosis (extracellular amyloid plaques) are the anatomical hallmarks of the disease, and the formation of these proteinaceous aggregates in specific brain areas is widely held as the ultimate pathogenic mechanism. However, the triggers of this dysproteostasis process remain unknown. Further, neurofibrillary tangles and plaques may only constitute the last stages of a process of still uncertain origin. Thus, without an established knowledge of its etiology, and no cure in the horizon, prevention - or merely delaying its development, has become a last-resort goal in AD research. As with other success stories in preventive medicine, epidemiological studies have provided basic knowledge of risk factors in AD that may contribute to understand its etiology. Disregarding old age, gender, and ApoE4 genotype as non preventable risk factors, there are diverse life-style traits - many of them closely related to cardiovascular health, that have been associated to AD risk. Most prominent among them are diet, physical and mental activity, exposure to stress, and sleep/wake patterns. We argue that all these life-style factors engage insulinergic pathways that affect brain function, providing a potentially unifying thread for life-style and AD risk. Although further studies are needed to firmly establish a link between faulty insulinergic function and AD, we herein summarize the evidence that this link should be thoroughly considered.

Consequences of diabetes mellitus on neuronal connectivity in limbic regions

Diabetes mellitus (DM) is characterized by high levels of blood glucose. In recent years, its prevalence has increased, which was 422 million in the world in 2014. In elderly patients, DM is associated with deficits in memory and learning processes. The cognitive deficits lead to dementia. With the development of animal models in DM, it has been possible to better understand quantitative morphological changes in numerous neuronal structures belonging to the limbic system, such as the prefrontal cortex (PFC), the hippocampus and basolateral amygdala (BLA). These structures are in close relationship with processes of memory and learning. Several reports have demonstrated that chronic hyperglycemia reduces spinogenesis and dendritic arborization in the aforementioned regions along with a decline in memory and learning processes, especially in streptozotocin (STZ)-induced diabetic rats. In the present review, we discuss animal models, the effects of chronic hyperglycemia on dendritic morphology of limbic regions and memory and learning processes, the effect on neural transmission in these regions, the pathologic mechanisms involved, and the relevance of dendritic morphology in diabetes. All of this information can help us to have a better understanding of dementia in diabetes mellitus and propose strategies for its prevention and treatment.

Targeting Early Dementia: Using Lipid Cubic Phase Nanocarriers to Cross the Blood⁻Brain Barrier

Over the past decades, a frequent co-morbidity of cerebrovascular pathology and Alzheimer's disease has been observed. Numerous published studies indicate that the preservation of a healthy cerebrovascular endothelium can be an important therapeutic target. By incorporating the appropriate drug(s) into biomimetic (lipid cubic phase) nanocarriers, one obtains a multitasking combination therapeutic, which targets certain cell surface scavenger receptors, mainly class B type I (i.e., SR-BI), and crosses the blood⁻brain barrier. This targeting allows for various cell types related to Alzheimer's to be simultaneously searched out for localized drug treatment in vivo.

Nanotherapy for Alzheimer's disease and vascular dementia: Targeting senile endothelium

Due to the complexity of Alzheimer's disease, multiple cellular types need to be targeted simultaneously in order for a given therapy to demonstrate any major effectiveness. Ultrasound-sensitive coated microbubbles (in a targeted lipid nanoemulsion) are available. Versatile small molecule drug(s) targeting multiple pathways of Alzheimer's disease pathogenesis are known. By incorporating such drug(s) into the targeted "lipid-coated microbubble" [LCM]/"nanoparticle-derived" [ND] (or LCM/ND) nanoemulsion type, one obtains a multitasking combination therapeutic for translational medicine. This multitasking therapeutic targets cell-surface scavenger receptors (mainly class B type I), or SR-BI, making possible for various Alzheimer's-related cell types to be simultaneously searched out for localized drug treatment in vivo. Besides targeting cell-surface SR-BI, the proposed LCM/ND-nanoemulsion combination therapeutic(s) include a characteristic lipid-coated microbubble [LCM] subpopulation (i.e., a stable LCM suspension); such film-stabilized microbubbles are well known to substantially reduce the acoustic power levels needed for accomplishing temporary noninvasive (transcranial) ultrasound treatment, or sonoporation, if additionally desired for the Alzheimer's patient.

Alzheimer’s Disease, Brain Injury, and C.N.S. Nanotherapy in Humans: Sonoporation Augmenting Drug Targeting

Owing to the complexity of neurodegenerative diseases, multiple cellular types need to be targeted simultaneously in order for a given therapy to demonstrate any major effectiveness. Ultrasound-sensitive coated microbubbles (in a targeted nanoemulsion) are available. Versatile small-molecule drug(s) targeting multiple pathways of Alzheimer’s disease pathogenesis are known. By incorporating such drug(s) into the targeted lipid-coated microbubble/nanoparticle-derived (LCM/ND) lipid nanoemulsion type, one obtains a multitasking combination therapeutic for translational medicine. This multitasking therapeutic targets cell-surface scavenger receptors (mainly scavenger receptor class B type I (SR-BI)), making it possible for various Alzheimer’s-related cell types to be simultaneously sought for localized drug treatment in vivo. Besides targeting cell-surface SR-BI, the proposed LCM/ND-nanoemulsion combination therapeutic(s) include a characteristic lipid-coated microbubble (LCM) subpopulation (i.e., a stable LCM suspension); such LCM substantially reduce the acoustic power levels needed for accomplishing temporary noninvasive (transcranial) ultrasound treatment, or sonoporation, if additionally desired for the Alzheimer’s patient.

Blood-brain barrier disruption in diabetic mice is linked to Nrf2 signaling deficits: Role of ABCB10?

Blood-brain barrier (BBB) damage is a critical neurovascular complication of diabetes mellitus that adversely affects the CNS health and function. Previously, we showed the protective role of NF-E2 related factor-2 (Nrf2), a redox sensitive transcription factor, in regulation of BBB integrity. Given the pathogenic role of mitochondrial oxidative stress in diabetes-related microvascular complications, we focused on assessing: 1) the impact of diabetes on brain Nrf2 in correlation with BBB permeability and 2) Nrf2-dependent regulation of the mitochondrial transporter ABCB10, an essential player in mitochondrial function and redox balance at BBB endothelium. Using live animal fluorescence imaging, we demonstrated a strong increase in BBB permeability to 70kDa dextran in db/db diabetic mice that correlated with significant down-regulation of brain Nrf2 protein. Further, Nrf2 gene silencing in human BBB endothelial cells markedly suppressed ABCB10 protein, while Nrf2 activation by sulforaphane up-regulated ABCB10 expression. Interestingly, ABCB10 knockdown resulted in a strong-induction of Nrf2 driven anti-oxidant responses as evidenced by increased expression of Nrf2 and its downstream targets. Nrf2 or ABCB10 silencing elevated endothelial-monocyte adhesion suggesting an activated inflammatory cascade. Thus, our results demonstrate a novel mechanism of ABCB10 regulation driven by Nrf2. In summary, Nrf2 dysregulation and ABCB10 suppression could likely mediate endothelial oxidative/inflammatory stress and BBB disruption in diabetic subjects.

Clinical Aspects of Glucose Metabolism and Chronic Disease

The burden of chronic disease is an emerging world health problem. Advances made in the treatment of individual disease states often fail to consider multimorbidity patterns in clinical research models. Adjusting for age as a confounder ignores its contribution as a powerful risk factor for most chronic diseases. Sarcopenia is an age-related loss of skeletal muscle mass, which is accelerated by chronic inflammation and its resulting cascade of cytokines. Skeletal muscle loss results in insulin resistance, hyperglycemia, and altered mitochondrial glucose signaling pathways. Vascular disease in the brain may alter blood-brain barrier function, allowing transport of substances into the brain which adversely affect the "astrocyte-centric" subunit. Neurogenesis that provides neuronal plasticity is impaired in the diabetic brain, while insulin resistance markers such as insulin-like growth factor (IGF-1) and insulin receptor substrate (IRS-1) are associated with poor cognitive performance. Advanced glycation end products generated by chronic hyperglycemia are found in postmortem AD brain. Intranasal insulin administration, a preferential route for CNS delivery, improved cognitive function in healthy adults, without affecting circulating levels of insulin or glucose. Exercise has demonstrated a neuroprotective effect through induction of antioxidative enzymes, neurotrophic, and vascular endothelial growth factors. Sarcopenia appears to be a dynamic process and is potentially reversible with attention to nutrition and cardiovascular fitness. Early detection and intervention may slow the progression of multimortality disease states and should be a focus of worldwide health systems.