Metabolomic profiling in small vessel disease identifies multiple associations with disease severity

Causal relationship of inflammatory cytokines and serum metabolites in cerebral small vessel disease: a two-step Mendelian randomization study

BACKGROUND AND PURPOSE

The aim was to investigate the causal relationships of inflammatory cytokines and serum metabolites in cerebral small vessel disease (CSVD).

METHODS

Bidirectional Mendelian randomization was first conducted to screen inflammatory cytokines and serum metabolites that were associated with imaging features of CSVD, including white matter hyperintensities, recent small subcortical infarcts, cortical cerebral microinfarcts, cerebral microbleeds, lacunes and enlarged perivascular spaces. Sensitivity analyses were performed to evaluate the robustness and pleiotropy of these results. Subsequently, inflammatory cytokines and serum metabolites that were associated with CSVD were subjected to functional enrichment. Finally, mediation analysis was employed to investigate whether inflammatory cytokines or serum metabolites acted as an intermediary for the other in their causal relationship with CSVD.

RESULTS

Of the inflammatory cytokines, five were risk factors (e.g., tumour-necrosis-factor-related apoptosis-inducing ligand) and five (e.g., fibroblast growth factor 19) were protective factors for CSVD. Eleven serum metabolites that increased CSVD risk and 13 metabolites that decreased CSVD risk were also identified. The majority of these markers of CSVD susceptibility were lipid metabolites. Natural killer cell receptor sub-type 2B4 was determined to act as a mediating factor of an unidentified metabolite for the enlargement of perivascular spaces.

CONCLUSION

Several inflammatory cytokines and serum metabolites had causal relationships with imaging features of CSVD. A natural killer cell receptor mediated in part the promotional effect of a metabolite on perivascular space enlargement.

Vascular cognitive impairment: Advances in clinical research and management

ABSTRACT

Vascular cognitive impairment (VCI) encompasses a wide spectrum of cognitive disorders, ranging from mild cognitive impairment to vascular dementia. Its diagnosis relies on thorough clinical evaluations and neuroimaging. VCI predominately arises from vascular risk factors (VRFs) and cerebrovascular disease, either independently or in conjunction with neurodegeneration. Growing evidence underscores the prevalence of VRFs, highlighting their potential for early prediction of cognitive impairment and dementia in later life. The precise mechanisms linking vascular pathologies to cognitive deficits remain elusive. Chronic cerebrovascular pathology is the most common neuropathological feature of VCI, often interacting synergistically with neurodegenerative processes. Current research efforts are focused on developing and validating reliable biomarkers to unravel the etiology of vascular brain changes in VCI. The collaborative integration of these biomarkers into clinical practice, alongside routine incorporation into neuropathological assessments, presents a promising strategy for predicting and stratifying VCI. The cornerstone of VCI prevention remains the control of VRFs, which includes multi-domain lifestyle modifications. Identifying appropriate pharmacological approaches is also of paramount importance. In this review, we synthesize recent advancements in the field of VCI, including its definition, determinants of vascular risk, pathophysiology, neuroimaging and fluid-correlated biomarkers, predictive methodologies, and current intervention strategies. Increasingly evident is the notion that more rigorous research for VCI, which arises from a complex interplay of physiological events, is still needed to pave the way for better clinical outcomes and enhanced quality of life for affected individuals.

Intersecting Pathways: The Role of Metabolic Dysregulation, Gastrointestinal Microbiome, and Inflammation in Acute Ischemic Stroke Pathogenesis and Outcomes

Acute ischemic stroke (AIS) remains a major cause of mortality and long-term disability worldwide, driven by complex and multifaceted etiological factors. Metabolic dysregulation, gastrointestinal microbiome alterations, and systemic inflammation are emerging as significant contributors to AIS pathogenesis. This review addresses the critical need to understand how these factors interact to influence AIS risk and outcomes. We aim to elucidate the roles of dysregulated adipokines in obesity, the impact of gut microbiota disruptions, and the neuroinflammatory cascade initiated by lipopolysaccharides (LPS) in AIS. Dysregulated adipokines in obesity exacerbate inflammatory responses, increasing AIS risk and severity. Disruptions in the gut microbiota and subsequent LPS-induced neuroinflammation further link systemic inflammation to AIS. Advances in neuroimaging and biomarker development have improved diagnostic precision. Here, we highlight the need for a multifaceted approach to AIS management, integrating metabolic, microbiota, and inflammatory insights. Potential therapeutic strategies targeting these pathways could significantly improve AIS prevention and treatment. Future research should focus on further elucidating these pathways and developing targeted interventions to mitigate the impacts of metabolic dysregulation, microbiome imbalances, and inflammation on AIS.

SGLT1 and SGLT2 inhibition, circulating metabolites, and cerebral small vessel disease: a mediation Mendelian Randomization study

BACKGROUND

Sodium-glucose cotransporter 2 (SGLT2) and SGLT1 inhibitors may have additional beneficial metabolic effects on circulating metabolites beyond glucose regulation, which could contribute to a reduction in the burden of cerebral small vessel disease (CSVD). Accordingly, we used Mendelian Randomization (MR) to examine the role of circulating metabolites in mediating SGLT2 and SGLT1 inhibition in CSVD.

METHODS

Genetic instruments for SGLT1/2 inhibition were identified as genetic variants, which were both associated with the expression of encoding genes of SGLT1/2 inhibitors and glycated hemoglobin A1c (HbA1c) level. A two-sample two-step MR was used to determine the causal effects of SGLT1/2 inhibition on CSVD manifestations and the mediating effects of 1400 circulating metabolites linking SGLT1/2 inhibition with CSVD manifestations.

RESULTS

A lower risk of deep cerebral microbleeds (CMBs) and small vessel stroke (SVS) was linked to genetically predicted SGLT2 inhibition. Better white matter structure integrity was also achieved, as evidenced by decreased mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), as well as lower deep (DWMH) and periventrivular white matter hyperintensity (PWMH) volume. Inhibiting SGLT2 could also lessen the incidence of severe enlarged perivascular spaces (EPVS) located at white matter, basal ganglia (BG) and hippocampus (HIP). SGLT1 inhibition could preserve white matter integrity, shown as decreased MD of white matter and DWMH volume. The effect of SGLT2 inhibition on SVS and MD of white matter through the concentration of 4-acetamidobutanoate and the cholesterol to oleoyl-linoleoyl-glycerol (18:1 to 18:2) ratio, with a mediated proportion of 30.3% and 35.5% of the total effect, respectively.

CONCLUSIONS

SGLT2 and SGLT1 inhibition play protective roles in CSVD development. The SGLT2 inhibition could lower the risk of SVS and improve the integrity of white matter microstructure via modulating the level of 4-acetamidobutanoate and cholesterol metabolism. Further mechanistic and clinical studies research are needed to validate our findings.

Large-Scale Population-Based Studies of Blood Metabolome and Brain Health

Metabolomics technologies enable the quantification of multiple metabolomic measures simultaneously, which provides novel insights into molecular aspects of human health and disease. In large-scale, population-based studies, blood is often the preferred biospecimen. Circulating metabolome may relate to brain health either by affecting or reflecting brain metabolism. Peripheral metabolites may act at or cross the blood-brain barrier and, subsequently, influence brain metabolism, or they may reflect brain metabolism if similar pathways are engaged. Peripheral metabolites may also include those penetrating the circulation from the brain, indicating, for example, brain damage. Most brain health-related metabolomics studies have been conducted in the context of neurodegenerative disorders and cognition, but some studies have also focused on neuroimaging markers of these disorders. Moreover, several metabolomics studies of neurodevelopmental disorders have been performed. Here, we provide a brief background on the types of blood metabolites commonly assessed, and we review the literature describing the relationships between human blood metabolome (n > 50 metabolites) and brain health reported in large-scale studies (n > 500 individuals).

Metabolomics and Risk of Dementia: A Systematic Review of Prospective Studies

BACKGROUND

The projected increase in the prevalence of dementia has sparked interest in understanding the pathophysiology and underlying causal factors in its development and progression. Identifying novel biomarkers in the preclinical or prodromal phase of dementia may be important for predicting early disease risk. Applying metabolomic techniques to prediagnostic samples in prospective studies provides the opportunity to identify potential disease biomarkers.

OBJECTIVE

The objective of this systematic review was to summarize the evidence on the associations between metabolite markers and risk of dementia and related dementia subtypes in human studies with a prospective design.

DESIGN

We searched PubMed, PsycINFO, and Web of Science databases from inception through December 8, 2023. Thirteen studies (mean/median follow-up years: 2.1-21.0 y) were included in the review.

RESULTS

Several metabolites detected in biological samples, including amino acids, fatty acids, acylcarnitines, lipid and lipoprotein variations, hormones, and other related metabolites, were associated with risk of developing dementia. Our systematic review summarized the adjusted associations between metabolites and dementia risk; however, our findings should be interpreted with caution because of the heterogeneity across the included studies and potential sources of bias. Further studies are warranted with well-designed prospective cohort studies that have defined study populations, longer follow-up durations, the inclusion of additional diverse biological samples, standardization of techniques in metabolomics and ascertainment methods for diagnosing dementia, and inclusion of other related dementia subtypes.

CONCLUSIONS

This study contributes to the limited systematic reviews on metabolomics and dementia by summarizing the prospective associations between metabolites in prediagnostic biological samples with dementia risk. Our review discovered additional metabolite markers associated with the onset of developing dementia and may help aid in the understanding of dementia etiology. The protocol is registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (https://www.crd.york.ac.uk/prospero/; registration ID: CRD42022357521).

Advances in Cerebral Small Vessel Disease: Sandra E. Black Lecture to the Canadian Neurological Sciences Federation

Cerebral small vessel diseases (CSVDs) are among the most common age-related pathologies of the brain. Arteriolosclerosis and cerebral amyloid angiopathy (CAA) are the most common CSVDs. In addition to causing stroke and dementia, CSVDs can have diverse covert radiological manifestations on computed tomography and magnetic resonance imaging including lacunes, T2-weighted white matter hyperintensities, increased density of visible perivascular spaces, microbleeds and cortical superficial siderosis. Because they cannot be visualized directly, research on the pathophysiology of CSVD has been difficult. However, advances in quantitative imaging methods, including physiological imaging such as measurement of cerebrovascular reactivity and increased vascular permeability, are beginning to allow investigation of the early effects of CSVD in living people. Furthermore, genomics, metabolomics and proteomics have the potential to illuminate previously unrecognized pathways to CSVD that could be important targets for new clinical trials.

Multi-omics reveal neuroprotection of Acer truncatum Bunge Seed extract on hypoxic-ischemia encephalopathy rats under high-altitude

Hypoxic-ischemic encephalopathy (HIE) at high-altitudes leads to neonatal mortality and long-term neurological complications without effective treatment. Acer truncatum Bunge Seed extract (ASO) is reported to have effect on cognitive improvement, but its molecular mechanisms on HIE are unclear. In this study, ASO administration contributed to reduced neuronal cell edema and improved motor ability in HIE rats at a simulated 4500-meter altitude. Transcriptomics and WGCNA analysis showed genes associated with lipid biosynthesis, redox homeostasis, neuronal growth, and synaptic plasticity regulated in the ASO group. Targeted and untargeted-lipidomics revealed decreased free fatty acids and increased phospholipids with favorable ω-3/ω-6/ω-9 fatty acid ratios, as well as reduced oxidized glycerophospholipids (OxGPs) in the ASO group. Combining multi-omics analysis demonstrated FA to FA-CoA, phospholipids metabolism, and lipid peroxidation were regulated by ASO treatment. Our results illuminated preliminary metabolism mechanism of ASO ingesting in rats, implying ASO administration as potential intervention strategy for HIE under high-altitude.

Association of Baseline Metabolomic Profiles With Incident Stroke and Dementia and With Imaging Markers of Cerebral Small Vessel Disease

BACKGROUND AND OBJECTIVES

Cerebral small vessel disease is a major cause of stroke and dementia. Metabolomics can help identify novel risk factors to better understand pathogenesis and predict disease progression and severity.

METHODS

We analyzed baseline metabolomic profiles from 118,021 UK Biobank participants. We examined cross-sectional associations of 325 metabolites with MRI markers of small vessel disease, evaluated longitudinal associations with incident stroke and dementia, and ascertained causal relationships using Mendelian randomization.

RESULTS

In cross-sectional analyses, lower levels of apolipoproteins, free cholesterol, cholesteryl esters, fatty acids, lipoprotein particle concentrations, phospholipids, and triglycerides were associated with increased white matter microstructural damage on diffusion tensor MRI. In longitudinal analyses, lipoprotein subclasses of very large high-density lipoprotein cholesterol (HDL) were associated with an increased risk of stroke, and acetate and 3-hydroxybutyrate were associated with an increased risk of dementia. Mendelian randomization analyses identified strong evidence supporting causal relationships for many findings. A few metabolites had consistent associations across multiple analysis types. Increased total lipids in very large HDL and increased HDL particle size were associated with increased white matter damage (lower fractional anisotropy: OR: 1.44, 95% CI 1.07-1.95, and OR: 1.19, 95% CI 1.06-1.34, respectively; mean diffusivity: OR: 1.49, 95% CI 1.11-2.01, and OR: 1.24, 95% CI 1.11-1.40, respectively) and an increased risk of incident all stroke (HR: 4.04, 95% CI 2.13-7.64, and HR: 1.54, 95% CI 1.20-1.98, respectively) and ischemic stroke (HR: 3.12, 95% CI 1.53-6.38; HR: 1.37, 95% CI 1.04-1.81). Valine was associated with decreased mean diffusivity (OR: 0.51, 95% CI 0.30-0.88) and had a protective association with all-cause dementia (HR: 0.008, 95% CI 0.002-0.035). Increased levels of cholesterol in small HDL were associated with a decreased risk of incident all stroke (HR: 0.17, 95% CI 0.08-0.39) and ischemic stroke (HR: 0.19, 95% CI 0.08-0.46) and were supported by evidence of a causal association with MRI-confirmed lacunar stroke (OR: 0.96, 95% CI 0.93-0.99).

DISCUSSION

In this large-scale metabolomics study, we found multiple metabolites associated with stroke, dementia, and MRI markers of small vessel disease. Further studies may help inform the development of personalized prediction models and provide insights into mechanistic pathways and future treatment approaches.

Negative correlation between serum pyruvate kinase M2 and cognitive function in patients with cerebral small vessel disease

OBJECTIVE

Cerebral small vessel disease (CSVD) is one of the main contributing factors to vascular cognitive impairment (VCI), with an increasing incidence rate. However, the genesis of CSVD cognitive impairment remains unknown. Inflammation and metabolic disorders are considered important pathogenesis of CSVD. In addition to acting as the key regulator of aerobic glycolysis, pyruvate kinase muscle isozyme 2 (PKM2) is a proinflammatory mediator transcriptional activator that can promote an inflammatory response. This study explored whether serum PKM2 is associated with cognitive impairment in CSVD patients.

METHODS

The demographic data, history of risk factors, laboratory data, and cognitive function scale assessment of 219 CSVD patients were analyzed, and the correlation between the CSVD clinical data and neuroimaging parameters with serum PKM2 was further explored. The serum PKM2 level was determined by enzyme-linked immunosorbent assay using the collected serum samples. Insulin resistance (IR) was assessed with reference to the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR). HOMA-IR was calculated using the formula HOMA-IR = fasting plasma glucose (FPG, mmol/L) × fasting insulin (FINS, μU/mL)/22.5. A binomial logistic regression model was referred to infer the risk factors for VCI, and the ability of serum PKM2 to diagnose VCI was assessed by using a ROC curve.

RESULTS

Serum PKM2 level was positively correlated with HOMA-IR (r = 0.206, P = 0.002), negatively correlated with MMSE and MOCA on the cognitive scale in CSVD patients, and higher in CSVD patients with white matter hyperintensities (WMH) (P < 0.001). When compared with patients without cognitive impairment, the serum PKM2 levels were elevated in cases with suspected dementia, mild dementia, mild to moderate dementia, and moderate to severe dementia, and the differences were statistically significant (P < 0.05). Serum PKM2 levels were correlated with cognitive screening test scores in CSVD.

CONCLUSION

The present findings indicated that the serum PKM2 level was positively correlated with HOMA-IR, WMH, and enlarged perivascular spaces and negatively correlated with cognitive function in CSVD patients.

Association between abnormal plasma metabolism and brain atrophy in alcohol-dependent patients

Objective

In this study, we aimed to characterize the plasma metabolic profiles of brain atrophy and alcohol dependence (s) and to identify the underlying pathogenesis of brain atrophy related to alcohol dependence.

Methods

We acquired the plasma samples of alcohol-dependent patients and performed non-targeted metabolomic profiling analysis to identify alterations of key metabolites in the plasma of BA-ADPs. Machine learning algorithms and bioinformatic analysis were also used to identify predictive biomarkers and investigate their possible roles in brain atrophy related to alcohol dependence.

Results

A total of 26 plasma metabolites were significantly altered in the BA-ADPs group when compared with a group featuring alcohol-dependent patients without brain atrophy (NBA-ADPs). Nine of these differential metabolites were further identified as potential biomarkers for BA-ADPs. Receiver operating characteristic curves demonstrated that these potential biomarkers exhibited good sensitivity and specificity for distinguishing BA-ADPs from NBA-ADPs. Moreover, metabolic pathway analysis suggested that glycerophospholipid metabolism may be highly involved in the pathogenesis of alcohol-induced brain atrophy.

Conclusion

This plasma metabolomic study provides a valuable resource for enhancing our understanding of alcohol-induced brain atrophy and offers potential targets for therapeutic intervention.

Cerebral Small Vessel Disease: A Bibliometric Analysis

Cerebral small vessel disease is a common neurological disease, and its incidence is increasing year by year worldwide. In recent years, research on cerebral small vessel disease has gained more and more attention. Our research aims to visualize publications to identify the hotspots and frontiers of cerebral small vessel disease research, and to provide reference and guidance for further research. Publications related to cerebral small vessel disease were searched from the Web of Science Core Collection and screened according to inclusion criteria. CiteSpace 5.8.R3 was used to evaluate and visualize results, including generating web maps and analyzing annual publications, countries, institutions, bibliographic and co-cited references, and keywords; in this article, we use CiteSpace and VOSviewer for the 2012 Cerebral small vessel disease and bibliometric analysis from January 1, 2022 to April 30, 2022. A total of 3037 papers related to cerebral small vessel disease were retrieved, and the number of published papers showed a steady upward trend. Among them, Neuroimaging standards for research into small vessel disease and its contribution to ageing and neurodegeneration, the most symbolic references in the field of cerebral small vessel disease have been cited a total of 438 times. Stroke is the most active journal (227 articles) and USA publishes up to 800 articles. Harvard Med SchUniv Edinburgh (133 papers) and Charidimou (85 papers) are the institutions and authors who have made the most contributions in this field, respectively. Among the keywords, most of them are related to the pathogenesis of cerebral small vessel disease. After 2018, gut-brain axis and cortex are the keywords with the strongest number of cited outbreaks. There is increasing evidence that cerebral small vessel disease is a research frontier and may remain a research hotspot in the future.

Nonalcoholic Fatty Liver Disease and Altered Neuropsychological Functions in Patients with Subcortical Vascular Dementia

NAFLD is the most common cause of abnormality in liver function tests. NAFLD is considered a potential cardiovascular risk factor and is linked to cardiovascular risk factors such as obesity, hypertension, type 2 diabetes, and dyslipidemia. Few previous studies have investigated whether NAFLD could be independently associated with cognitive impairment. The current study aims to find a possible role of NAFLD in the development of subcortical vascular dementia (sVaD). We considered NAFLD as a possible independent vascular risk factor or, considering its metabolic role, associated with other commonly accepted sVaD risk factors, i.e., lack of folate, vitamin B12, and vitamin D-OH25, and increased levels of homocysteine. We studied 319 patients diagnosed with sVaD. All patients underwent an abdominal ultrasound examination to classify steatosis into four levels (1-none up to 4-severe). sVaD patients were divided into two groups according to the presence or absence of NAFLD. Our results demonstrated a strong correlation between NAFLD and sVaD. Patients with the two comorbidities had worse neuropsychological outcomes and a worse metabolic profile. We also found a robust relationship between NAFLD and severe vitamin B12, folate, vitamin D hypovitaminosis, and higher hyperhomocysteinemia levels. This way, it is evident that NAFLD contributes to a more severe metabolic pathway. However, the strong relationship with the three parameters (B12, folate and vitamin D, and homocysteinemia) suggests that NAFLD can contribute to a proinflammatory condition.