Association between hypertension and neurovascular inflammation in both normal-appearing white matter and white matter hyperintensities

More severe vascular remodeling in deep brain regions caused by hemodynamic differences is a potential mechanism of hypertensive cerebral small vessel disease

In hypertension-associated arteriolosclerosis cerebral small vessel disease (CSVD), various studies have shown that MRI-detected lesions-such as lacunes, white matter hyperintensities, enlarged perivascular spaces, and cerebral microbleeds-are more prevalent in deep brain regions (DBR) than in the cortex. However, the underlying mechanisms remain poorly understood. We propose that differential vascular remodeling between DBR small vessels and superficial cortical branches contributes to this heterogeneity. Using a stroke-prone renovascular hypertensive rat (RHRsp) model, we observed pronounced changes in vessel density, diameter, extracellular matrix deposition, and smooth muscle cell alterations in DBR small arteries compared to that of the cortex. These findings were further confirmed in human brain tissue of our study. Additionally, our mathematical modeling indicated greater hemodynamic alterations in DBR vessels, with increased shear and circumferential stress under hypertension conditions. Overall, our study highlights more severe vascular remodeling and hemodynamic changes in the deep brain regions, where CSVD-associated MRI lesions are frequently detected.

Impact of Peripheral Inflammation on Blood-Brain Barrier Dysfunction and Its Role in Neurodegenerative Diseases

The blood-brain barrier (BBB) is essential for maintaining brain homeostasis by regulating molecular exchange between the systemic circulation and the central nervous system. However, its dysfunction, often driven by peripheral inflammatory processes, has been increasingly linked to the development and progression of neurodegenerative diseases such as Alzheimer's and Parkinson's. Emerging evidence suggests that the gut-brain axis plays a key role in BBB integrity, with intestinal dysbiosis and chronic inflammation contributing to barrier disruption through immune and metabolic pathways. Furthermore, the selective vulnerability of specific brain regions to BBB dysfunction appears to be influenced by regional differences in vascularization, metabolic activity, and permeability, making certain areas more susceptible to neurodegenerative processes. This review explored the molecular mechanisms linking peripheral inflammation, gut microbiota, and BBB dysfunction, emphasizing their role in neurodegeneration. A comprehensive literature review was conducted using Web of Science, PubMed, Scopus, Wiley, ScienceDirect, and Medline, covering publications from 2015 to 2025. The findings highlight a complex interplay between gut microbiota-derived metabolites, immune signaling, and BBB permeability, underscoring the need for targeted interventions such as microbiome modulation, anti-inflammatory therapies, and advanced drug delivery systems. The heterogeneity of the BBB across different brain regions necessitates the development of region-specific therapeutic strategies. Despite advancements, critical knowledge gaps persist regarding the precise mechanisms underlying BBB dysfunction. Future research should leverage cutting-edge methodologies such as single-cell transcriptomics and organ-on-chip models to translate preclinical findings into effective clinical applications. Addressing these challenges will be crucial for developing personalized therapeutic approaches to mitigate the impact of BBB dysfunction in neurodegenerative diseases.

Deep learning-based segmentation in MRI-(immuno)histological examination of myelin and axonal damage in normal-appearing white matter and white matter hyperintensities

The major vascular cause of dementia is cerebral small vessel disease (SVD). Its diagnosis relies on imaging hallmarks, such as white matter hyperintensities (WMH). WMH present a heterogenous pathology, including myelin and axonal loss. Yet, these might be only the "tip of the iceberg." Imaging modalities imply that microstructural alterations underlie still normal-appearing white matter (NAWM), preceding the conversion to WMH. Unfortunately, direct pathological characterization of these microstructural alterations affecting myelinated axonal fibers in WMH, and especially NAWM, is still missing. Given that there are no treatments to significantly reduce WMH progression, it is important to extend our knowledge on pathological processes that might already be occurring within NAWM. Staining of myelin with Luxol Fast Blue, while valuable, fails to assess subtle alterations in white matter microstructure. Therefore, we aimed to quantify myelin surrounding axonal fibers and axonal- and microstructural damage in detail by combining (immuno)histochemistry with polarized light imaging (PLI). To study the extent (of early) microstructural damage from periventricular NAWM to the center of WMH, we refined current analysis techniques by using deep learning to define smaller segments of white matter, capturing increasing fluid-attenuated inversion recovery signal. Integration of (immuno)histochemistry and PLI with post-mortem imaging of the brains of individuals with hypertension and normotensive controls enables voxel-wise assessment of the pathology throughout periventricular WMH and NAWM. Myelin loss, axonal integrity, and white matter microstructural damage are not limited to WMH but already occur within NAWM. Notably, we found that axonal damage is higher in individuals with hypertension, particularly in NAWM. These findings highlight the added value of advanced segmentation techniques to visualize subtle changes occurring already in NAWM preceding WMH. By using quantitative MRI and advanced diffusion MRI, future studies may elucidate these very early mechanisms leading to neurodegeneration, which ultimately contribute to the conversion of NAWM to WMH.

Structural and functional brain correlates of the neutrophil- and monocyte-to-lymphocyte ratio in neuropsychiatric disorders

Skews in the neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR) increasingly demonstrate prognostic capability in a range of acute and chronic mental health conditions. There has been a recent uptick in structural and functional magnetic responance imaging data corroborating the role of NLR and MLR in a cluster of neuropsychiatric disorders that are characterized by cognitive, affective, and psychomotor dysfunction. Moreover, these deficits are mostly evident in setting of acute and chronic disease comorbidity implicating aging and immunosenescent processes in the manifestation of these geriatric syndromes. The studies reviewed in this special edition implicate neutrophil and monocyte expansion relative to lymphocytopenia in the sequelae of depression, cognitive and functional decline, as well as provide support from a range of neuroimaging techniques that identify brain alteartions concommitant with expansion of the NLR or MLR and the sequelae of depression, dementia, and functional decline.

The Robustness of White Matter Brain Networks Decreases with Aging

BACKGROUND

White matter (WM) is a principal component of the human brain, forming the structural basis for neural transmission between cortico-cortical and subcortical structures. The impairment of WM integrity is closely associated with the aging process, manifesting as the reorganization of brain networks based on graph theoretical analysis of complex networks and increased volume of white matter hyperintensities (WMHs) in imaging studies.

METHODS

This study investigated changes in the robustness of WM brain networks during aging and assessed their correlation with WMHs. We constructed WM brain networks for 159 volunteers from a community sample dataset using diffusion tensor imaging (DTI). We then calculated the robustness of these networks by simulating neurodegeneration based on network attack analysis, and studied the correlations between WM network robustness, age, and the proportion of WMHs.

RESULTS

The analysis revealed a moderate, negative correlation between WM network robustness and age, and a weak and negative correlation between WM network robustness and the proportion of WMHs.

CONCLUSIONS

These findings suggest that WM pathologies are associated with aging and offer new insights into the imaging characteristics of the aging brain.

The immunology of stroke and dementia

Ischemic stroke and vascular cognitive impairment, caused by a sudden arterial occlusion or more subtle but protracted vascular insufficiency, respectively, are leading causes of morbidity and mortality worldwide with limited therapeutic options. Innate and adaptive immunity have long been implicated in neurovascular injury, but recent advances in methodology and new experimental approaches have shed new light on their contributions. A previously unappreciated dynamic interplay of brain-resident, meningeal, and systemic immune cells with the ischemic brain and its vasculature has emerged, and new insights into the frequent overlap between vascular and Alzheimer pathology have been provided. Here, we critically review these recent findings, place them in the context of current concepts on neurovascular pathologies and Alzheimer's disease, and highlight their impact on recent stroke and Alzheimer therapies.

Association of systemic inflammatory markers with white matter hyperintensities and microstructural injury: an analysis of UK Biobank data

BACKGROUND

White matter damage is closely associated with cognitive and psychiatric symptoms and is prevalent in cerebral small vessel disease (CSVD); although the pathophysiological mechanisms involved in CSVD remain elusive, inflammation plays a crucial role. We sought to investigate the relationship between systemic inflammation markers and imaging markers of CVSD, namely white matter hyperintensity (WMH) and microstructural injury.

METHODS

We conducted a study involving both cross-sectional and longitudinal data from the UK Biobank Cohort. We performed multiple linear regression analyses, adjusted for potential confounders, to explore the associations between systemic inflammation markers (e.g., systemic immune-inflammation index [SII], neutrophil-to-lymphocyte ratio [NLR], C-reactive protein [CRP] levels, monocyte count, neutrophil count) and macro- and microstructural white matter injury, as markers of CSVD. We performed Mendelian randomization analysis to investigate the genetically predictive effect of monocytes on WMH, as well as mediation analysis to clarify whether inflammatory markers affected cognitive function via white matter injury.

RESULTS

We included 36 411 participants (mean age 54.8 ± 7.5 yr, 51.9% female) from the UK Biobank Cohort. We found that SII was significantly associated with both WMH and microstructural injury markers (fractional anisotropy, mean diffusivity, intracellular volume fraction, and isotropic compartment volume fraction [ISOVF]), and the neutrophil-to-lymphocyte ratio was significantly associated with WMH and some markers of microstructural injury (mean diffusivity and ISOVF). Our analysis revealed that the CRP level was significantly associated with WMH and WMH progression but not with microstructural injury. We also demonstrated that monocyte count was significantly associated with WMH and ISOVF, and that neutrophil count was significantly associated with WMH, mean diffusivity, and ISOVF. In 2-sample Mendelian randomization analyses, we found positive associations between genetic determinants of monocytes and WMH. The mediating role of WMH suggested that a higher SII value and monocyte count could contribute to cognitive impairment through white matter injury.

LIMITATIONS

Although the study includes both cross-sectional and longitudinal components, the sample size for the longitudinal aspect is limited, and the use of blood biomarkers from a single timepoint is also a limitation of this research.

CONCLUSION

The SII and neutrophil-to-lymphocyte ratio may be early detection markers for white matter damage in patients with CSVD, whereas the CRP level is more closely associated with disease severity and progression. Our findings highlight the clinical relevance of systemic inflammation markers with white matter macro- and microstructural injuries, revealing that systemic inflammation is likely involved in the mechanism of early white matter injury among patients with CSVD.

Immune system activation and cognitive impairment in arterial hypertension

Chronic arterial hypertension disrupts the integrity of the cerebral microvasculature, doubling the risk of age-related dementia. Despite sufficient antihypertensive therapy in still a significant proportion of individuals blood pressure lowering alone does not preserve cognitive health. Accumulating evidence highlights the role of inflammatory mechanisms in the pathogenesis of hypertension. In this review, we introduce a temporal framework to explore how early immune system activation and interactions at neurovascular-immune interfaces pave the way to cognitive impairment. The overall paradigm suggests that prohypertensive stimuli induce mechanical stress and systemic inflammatory responses that shift peripheral and meningeal immune effector mechanisms toward a proinflammatory state. Neurovascular-immune interfaces in the brain include a dysfunctional blood-brain barrier, crossed by peripheral immune cells; the perivascular space, in which macrophages respond to cerebrospinal fluid- and blood-derived immune regulators; and the meningeal immune reservoir, particularly T cells. Immune responses at these interfaces bridge peripheral and neurovascular unit inflammation, directly contributing to impaired brain perfusion, clearance of toxic metabolites, and synaptic function. We propose that deep immunophenotyping in biofluids together with advanced neuroimaging could aid in the translational determination of sequential immune and brain endotypes specific to arterial hypertension. This could close knowledge gaps on how and when immune system activation transits into neurovascular dysfunction and cognitive impairment. In the future, targeting specific immune mechanisms could prevent and halt hypertension disease progression before clinical symptoms arise, addressing the need for new interventions against one of the leading threats to cognitive health.

Characterizing the role of the microbiota-gut-brain axis in cerebral small vessel disease: An integrative multi‑omics study

BACKGROUND

Prior efforts have revealed changes in gut microbiome, circulating metabolome, and multimodal neuroimaging features in cerebral small vessel disease (CSVD). However, there is a paucity of research integrating the multi-omic information to characterize the role of the microbiota-gut-brain axis in CSVD.

METHODS

We collected gut microbiome, fecal and blood metabolome, multimodal magnetic resonance imaging data from 37 CSVD patients with white matter hyperintensities and 46 healthy controls. Between-group comparison was performed to identify the differential gut microbial taxa, followed by performance of multi-stage microbiome-metabolome-neuroimaging-neuropsychology correlation analyses in CSVD patients.

RESULTS

Our data showed both depleted and enriched gut microbes in CSVD patients. Among the differential microbes, Haemophilus and Akkermansia were associated with a range of metabolites enriched for Aminoacyl-tRNA biosynthesis pathway. Furthermore, the affected metabolites were associated with neuroimaging measures involving gray matter morphology, spontaneous intrinsic brain activity, white matter integrity, and global structural network topology, which were in turn related to cognition and emotion in CSVD patients.

CONCLUSION

Our findings provide an integrative framework to understand the pathophysiological mechanisms underlying the interplay between gut microbiota dysbiosis and CSVD, highlighting the potential of targeting the microbiota-gut-brain axis as a therapeutic strategy in CSVD patients.

Correlation between matrix metalloproteinase-2, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinases-1 and white matter hyperintensities in patients with cerebral small vessel disease based on cranial magnetic resonance 3D imaging

OBJECTIVE

The objective of this study was to investigate the correlation between serum levels of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinases-1 (TIMP-1) levels and their ratios with the severity of white matter hyperintensities (WMHs) in patients with cerebral small vessel disease (CSVD).

METHODS

This cross-sectional study was done on a prospective cohort of patients with CSVD. Qualitative and quantitative analyses of WMHs were performed using Fazekas grading and lesion prediction algorithm (LPA) methods. Biomarkers MMP-2, MMP-9, and TIMP-1 were measured to explore their correlation with the severity of WMHs.

RESULTS

The sample consisted of 144 patients with CSVD. There were 63 male and 81 female patients, with an average age of 67.604 ± 8.727 years. Among these, 58.33% presented with white matter hyperintensities at Fazekas grading level 1, with an average total template volume of WMHs of 4.305 mL. MMP-2 (P = 0.025), MMP-9 (P = 0.008), TIMP-1 (P = 0.026), and age (P = 0.007) were identified as independent correlates of WMHs based on Fazekas grading. Independent correlates of the total template volume of WMHs included MMP-2 (P = 0.023), TIMP-1 (P = 0.046), age (P = 0.047), systolic blood pressure (P = 0.047), and homocysteine (Hcy) (P = 0.014). In addition, age (P = 0.003; P < 0.001), interleukin-6 (IL-6) (P < 0.001; P = 0.044), Hcy (P < 0.001; P < 0.001), glycated hemoglobin (HbA1c) (P = 0.016; P = 0.043), and chronic kidney disease (P < 0.001; P < 0.001) were associated with both WMHs Fazekas grading and the total template volume of WMHs.

CONCLUSION

Serum levels of MMP-9, MMP-2, and TIMP-1 were independently associated with the Fazekas grading, while serum TIMP-1 and MMP-2 levels were independently related to the total template volume of WMHs. The association of TIMP-1 and MMP-2 with the severity of CSVD-related WMHs suggests their potential role as disease-related biomarkers. However, further research is required to uncover the specific mechanisms underlying these interactions.

Metabolic dysfunction-associated steatotic liver disease is associated with effects on cerebral perfusion and white matter integrity

It is unclear whether early metabolic and inflammatory aberrations in the liver are associated with detrimental changes in brain structure and cognitive function. This cross-sectional study examines putative associations between metabolic dysfunction-associated steatotic liver disease (MASLD) and brain health in 36-55 year-old participants with obesity (n = 70) from the BARICO study (BAriatric surgery Rijnstate and Radboudumc neuroImaging and Cognition in Obesity). The participants underwent brain magnetic resonance imaging to study brain volumes and cortical thickness (3T MRI including T1-weighted magnetization-prepared rapid gradient-echo sequence), cerebral blood perfusion (arterial spin labeling) and white matter integrity (diffusion weighted imaging to assess mean-skeletonized mean diffusivity and fluid-attenuated inversion recovery to detect the presence of white matter hyperintensities (WMH)). The participants additionally performed neuropsychological tests to assess global cognition, working and episodic memory, verbal fluency and the ability to shift attention. Liver biopsies were collected and liver dysfunction was examined with histopathological, biochemical, and gene expression analyses. Linear regression analyses were performed between liver and brain parameters and the influence of body-mass index, diabetes and hypertension was explored. Early stages of liver disease were not associated with cognitive status but with cerebrovascular changes independently of age, sex, BMI, diabetes and hypertension: hepatic fibrosis development was associated with higher spatial coefficient of variation (sCoV) in the nucleus accumbens (NAcc), reflecting greater variations in cerebral perfusion and reduced vascular efficiency. Elevated hepatic levels of free cholesterol and cholesteryl esters were associated with increased WMH, indicating cerebral small vessel disease. RNA-seq and pathway analyses identified associations between sCoV in NAcc and WMH and the expression of hepatic genes involved in inflammation and cellular stress. Additionally, sCoV in NAcc correlated with plasma IL-6 levels suggesting that systemic-low grade inflammation may, at least partly, mediate this relationship. In conclusion, this study demonstrates that specific features of liver dysfunction (e.g. free cholesterol, onset of fibrosis) are associated with subtle cerebrovascular impairments, when changes in cognitive performance are not yet noticeable. These findings highlight the need for future research on therapeutic strategies that normalize metabolic-inflammatory aberrations in the liver to reduce the risk of cognitive decline.

White Matter Hyperintensities and Microstructural Alterations in Contact Sport Athletes from Adolescence to Early Midlife

Studies have demonstrated associations between cumulative concussion and repetitive head impact exposure (RHI) through contact sports with white matter (WM) alterations later in life. The course of WM changes associated with exposure earlier in the lifespan is unclear. This study investigated alterations in white matter (WM hyperintensity [WMH] volume and microstructural changes) associated with concussion and RHI exposure from adolescence to early midlife, as well as the interaction between exposure and age cohort (i.e., adolescent/young adult compared with early midlife athlete cohorts) on WM outcomes. Participating football players included an adolescent/young adulthood cohort (n = 82; Mage = 18.4 ± 1.7) and an early midlife cohort (37 former collegiate players approximately 15 years removed from sport; Mage = 37.7 ± 1.4). Years of football participation and number of prior concussions were exposures of interest. White matter outcomes included log-transformed manually segmented total WMH volume and neurite orientation dispersion and density imaging metrics of microstructure/organization (isotropic volume fraction [Viso], intracellular volume fraction [Vic], and orientation dispersion [OD]). Regression models were fit to test the effects of concussion history, years of football participation, and age cohort by years of football participation with WM outcomes. Spearman's correlations assessed associations between significant WM metrics and measures of cognitive and psychological function. A significant age cohort by years of participation effect was observed for whole brain white matter OD, B = -0.002, SE = 0.001, p = 0.001. The interaction was driven by a negative association between years of participation and OD within the younger cohort, B = -0.001, SE = 0.0004, p = 0.008, whereas a positive association between participation and OD in the early midlife cohort, B = 0.001, SE = 0.0003, p = 0.039, was observed. Follow-up ROI analyses showed significant interaction effects for OD in the body of the corpus callosum, genu of the corpus callosum, cingulum, inferior fronto-occipital fasciculus, superior longitudinal fasciculus, and posterior thalamic radiation (p values <0.05). Greater concussion history was significantly associated with greater Viso in the early midlife cohort, B = 0.001, SE = 0.0002, p = 0.010. Years of participation and concussion history were not associated with WMH volume, p values >0.05. Performance on a measure of executive function was significantly associated with years of participation, ρ = 0.34, p = 0.04, and a trend was observed for OD, ρ = 0.28, p = 0.09 in the early midlife cohort only. The global characterization of white matter changes associated with years of football participation were broadly similar and stable from adolescence through early midlife (i.e., microstructural alterations, but not macroscopic lesions). An inverse association between years of participation and orientation dispersion across age cohorts may represent a process of initial recovery/reorganization proximal to sport, followed by later reduction of white matter coherence.

Cognition mediates the relationship between white matter hyperintensity and motor function in patients with cerebral small vessel disease: a cross-sectional study

Background

White matter hyperintensity (WMH) is a common neuroimaging marker of cerebral small vessel disease (SVD) and a critical independent predictor of motor dysfunction, which increases the risk of disability, morbidity, and mortality. However, the mechanism underlying the relationship between WMH and motor function has not yet been fully clarified. It was hypothesized that cognitive impairment mediates the relationship between WMH and motor dysfunction in patients with SVD, which were considered predictor and outcome variables, respectively.

Methods

A total of 221 patients with SVD were enrolled in this study, and their magnetic resonance imaging (MRI), neuropsychological, and motor function data were collected. The MRI data were visually assessed to determine the WMH burden using the Fazekas scale. Cognition was evaluated using the Montreal Cognitive Assessment (MoCA). Motor function was assessed using the Tinetti Gait and Balance Scale and the Short Physical Performance Battery (SPPB). Finally, a bootstrap analysis was performed to determine whether cognition mediated the relationship between WMH and motor function.

Results

Of all the patients, 30.3% had mild WMH, 37.6% had moderate WMH, and 32.1% had severe WMH. Patients' cognition and motor function decreased as the WMH burden increased (P<0.01). The MoCA scores were associated with the Tinetti scale (r=0.545, P<0.01) and SPPB scores (r=0.365, P<0.01). Finally, multi-categorical mediation models confirmed our research hypothesis; the coefficients for the indirect effects had 95% confidence intervals (CIs) that excluded zero, indicating statistically significant mediation effects.

Conclusions

WMH is associated with motor dysfunction, and this association is mediated by cognition in patients with SVD. This finding highlights the importance of early interventions targeting cognitive function to reduce the risk of motor dysfunction.

Predictors of white matter hyperintensities in the elderly Congolese population

Background

White matter hyperintensities (WMHs) are strongly linked to cardiovascular risk factors and other health conditions such as Alzheimer's disease. However, there is a dearth of research on this topic in low-income countries and underserved populations, especially in the Democratic Republic of Congo (DRC) where the population is aging rapidly with increasing cardiovascular risk factors and dementia-related diseases. This study evaluates health factors associated with WMH in the elderly Sub-Saharan Africa (SSA), specifically Congolese adults.

Methods

In a cross-sectional study of 77 people from the DRC, participants underwent neuroimaging to analyze WMH volume and completed clinical evaluation, laboratory-based blood exams, self-reported questionnaires, and interviews. A simple linear regression model was conducted to test the association between WMH and potential predictors (neurological status, age, sex, hypertension, diabetes, tobacco abuse, stroke, high cholesterol, cardiovascular medication, and alcohol abuse). Stepwise selection and backward elimination analyses were performed to obtain the final model. Finally, a multiple linear regression model was conducted to assess the association between WMH and variables retained in the final model (neurological status, sex, and age).

Results

Of the 77 individuals, 47 (61%) had dementia, 40 (52.6%) were males, and the mean age was 73 years (± 8.0 years standard deviation). In simple linear regression models, WMH was significantly associated with dementia (expβ1=1.75, 95% CI=1.14 - 2.71, p-value=0.01) though it had a weak association with age (expβ1=1.03, 95% CI=1.00 - 1.05, p-value=0.05) and sex (male) (expβ1=0.66, 95% CI=0.43 - 1.01, p-value=0.05). In multiple linear regression models, WMH was statistically significantly associated with dementia (expβ1=1.97, 95% CI=1.31 - 2.95, p-value =0.001), male sex (expβ2=0.54, 95% CI=0.36 - 0.80, p-value=0.003), and age (expβ3=1.03, 95% CI=1.00 - 1.06, p-value=0.03). However, WMH was not significantly associated with common cardiovascular risk factors, such as high blood pressure, diabetes, tobacco use, obesity, and high cholesterol levels.

Conclusion

WMH is significantly associated with neurological status, sex, and age in the Congolese population. Understanding these predictors may improve our ability to diagnose, assess, and develop preventative treatments for white matter disease in SSA/DRC populations, where neuroimaging is difficult to obtain.

Proteogenomics in cerebrospinal fluid and plasma reveals new biological fingerprint of cerebral small vessel disease

Cerebral small vessel disease (cSVD) is a leading cause of stroke and dementia with no specific mechanism-based treatment. We used Mendelian randomization to combine a unique cerebrospinal fluid (CSF) and plasma pQTL resource with the latest European-ancestry GWAS of MRI-markers of cSVD (white matter hyperintensities, perivascular spaces). We describe a new biological fingerprint of 49 protein-cSVD associations, predominantly in the CSF. We implemented a multipronged follow-up, across fluids, platforms, and ancestries (Europeans and East-Asian), including testing associations of direct plasma protein measurements with MRI-cSVD. We highlight 16 proteins robustly associated in both CSF and plasma, with 24/4 proteins identified in CSF/plasma only. cSVD-proteins were enriched in extracellular matrix and immune response pathways, and in genes enriched in microglia and specific microglial states (integration with single-nucleus RNA sequencing). Immune-related proteins were associated with MRI-cSVD already at age twenty. Half of cSVD-proteins were associated with stroke, dementia, or both, and seven cSVD-proteins are targets for known drugs (used for other indications in directions compatible with beneficial therapeutic effects. This first cSVD proteogenomic signature opens new avenues for biomarker and therapeutic developments.

Progressive Disruption of Sphingosine-1-Phosphate Receptor 1 Correlates with Blood-Brain Barrier Leakage in A Rat Model of Chronic Hypoxic Hypoperfusion

Endothelial dysfunction and blood-brain barrier (BBB) leakage have been suggested as a fundamental role in the development of cerebral small vessel disease (SVD) pathology. However, the molecular and cellular mechanisms that link cerebral hypoxic hypoperfusion and BBB disruption remain elusive. Sphingosine-1-phosphate (S1P) regulates the BBB integrity by binding to its receptor isoform 1 (S1PR1) on endothelial cells. This study tested the hypothesis that hypoxic hypoperfusion triggers capillary endothelial S1PR1 disruption, which compromises BBB integrity and leads to SVD-related neuropathological changes, using a chronic hypoxic hypoperfusion model with BBB dysfunction. Spontaneously hypertensive rat stroke-prone underwent unilateral carotid artery occlusion (UCAO) followed by a Japanese permissive diet (JPD) for up to 9 weeks. Selective S1PR1 agonist SEW2871 was used to activate S1PR1. Significant progressive reduction of S1PR1 was detected in rat brains from 4 to 9 weeks following UCAO/JPD onset, which was also detected in cerebral vasculature in human SVD. S1PR1 activation by SEW2871 significantly reduced lesions in both white and grey matter and ameliorated cerebral blood flow. SEW2871 reversed the loss of endothelial S1PR1 and tight junction proteins, and significantly attenuated UCAO/JPD induced accumulation of neuronal phosphorylated tau. This protective role of SEW2871 is associated with promotion of Akt phosphorylation and inhibition of S1PR2/Erk1/2 activation. Our data suggest S1PR1 signalling as a potential molecular mechanistic basis that links hypoxic hypoperfusion with BBB damage in the neuropathological cascades in SVD. The reversal of BBB disruption through pharmacological intervention of S1PR1 signalling likely reveals a novel therapeutic target for SVD.

Three-dimensional identification of microvascular pathology and neurovascular inflammation in severe white matter hyperintensity: a case report

White matter hyperintensities (WMH) are the most prevalent markers of cerebral small vessel disease (SVD), which is the major vascular risk factor for dementia. Microvascular pathology and neuroinflammation are suggested to drive the transition from normal-appearing white matter (NAWM) to WMH, particularly in individuals with hypertension. However, current imaging techniques cannot capture ongoing NAWM changes. The transition from NAWM into WMH is a continuous process, yet white matter lesions are often examined dichotomously, which may explain their underlying heterogeneity. Therefore, we examined microvascular and neurovascular inflammation pathology in NAWM and severe WMH three-dimensionally, along with gradual magnetic resonance imaging (MRI) fluid-attenuated inversion recovery (FLAIR) signal (sub-)segmentation. In WMH, the vascular network exhibited reduced length and complexity compared to NAWM. Neuroinflammation was more severe in WMH. Vascular inflammation was more pronounced in NAWM, suggesting its potential significance in converting NAWM into WMH. Moreover, the (sub-)segmentation of FLAIR signal displayed varying degrees of vascular pathology, particularly within WMH regions. These findings highlight the intricate interplay between microvascular pathology and neuroinflammation in the transition from NAWM to WMH. Further examination of neurovascular inflammation across MRI-visible alterations could aid deepening our understanding on WMH conversion, and therewith how to improve the prognosis of SVD.

The Role of the Vascular System in Degenerative Diseases: Mechanisms and Implications

Degenerative diseases, encompassing a wide range of conditions affecting various organ systems, pose significant challenges to global healthcare systems. This comprehensive review explores the intricate interplay between the vascular system and degenerative diseases, shedding light on the underlying mechanisms and profound implications for disease progression and management. The pivotal role of the vascular system in maintaining tissue homeostasis is highlighted, as it serves as the conduit for oxygen, nutrients, and immune cells to vital organs and tissues. Due to the vital role of the vascular system in maintaining homeostasis, its dysfunction, characterized by impaired blood flow, endothelial dysfunction, and vascular inflammation, emerges as a common denominator of degenerative diseases across multiple systems. In the nervous system, we explored the influence of vascular factors on neurodegenerative diseases such as Alzheimer's and Parkinson's, emphasizing the critical role of cerebral blood flow regulation and the blood-brain barrier. Within the kidney system, the intricate relationship between vascular health and chronic kidney disease is scrutinized, unraveling the mechanisms by which hypertension and other vascular factors contribute to renal dysfunction. Throughout this review, we emphasize the clinical significance of understanding vascular involvement in degenerative diseases and potential therapeutic interventions targeting vascular health, highlighting emerging treatments and prevention strategies. In conclusion, a profound appreciation of the role of the vascular system in degenerative diseases is essential for advancing our understanding of degenerative disease pathogenesis and developing innovative approaches for prevention and treatment. This review provides a comprehensive foundation for researchers, clinicians, and policymakers seeking to address the intricate relationship between vascular health and degenerative diseases in pursuit of improved patient outcomes and enhanced public health.

Thirty Risk Factors for Alzheimer's Disease Unified by a Common Neuroimmune-Neuroinflammation Mechanism

One of the major obstacles confronting the formulation of a mechanistic understanding for Alzheimer's disease (AD) is its immense complexity-a complexity that traverses the full structural and phenomenological spectrum, including molecular, macromolecular, cellular, neurological and behavioural processes. This complexity is reflected by the equally complex diversity of risk factors associated with AD. However, more than merely mirroring disease complexity, risk factors also provide fundamental insights into the aetiology and pathogenesis of AD as a neurodegenerative disorder since they are central to disease initiation and subsequent propagation. Based on a systematic literature assessment, this review identified 30 risk factors for AD and then extended the analysis to further identify neuroinflammation as a unifying mechanism present in all 30 risk factors. Although other mechanisms (e.g., vasculopathy, proteopathy) were present in multiple risk factors, dysfunction of the neuroimmune-neuroinflammation axis was uniquely central to all 30 identified risk factors. Though the nature of the neuroinflammatory involvement varied, the activation of microglia and the release of pro-inflammatory cytokines were a common pathway shared by all risk factors. This observation provides further evidence for the importance of immunopathic mechanisms in the aetiopathogenesis of AD.

Spatio-temporal dynamics of microglia phenotype in human and murine cSVD: impact of acute and chronic hypertensive states

Vascular risk factors such as chronic hypertension are well-established major modifiable factors for the development of cerebral small vessel disease (cSVD). In the present study, our focus was the investigation of cSVD-related phenotypic changes in microglia in human disease and in the spontaneously hypertensive stroke-prone rat (SHRSP) model of cSVD. Our examination of cortical microglia in human post-mortem cSVD cortical tissue revealed distinct morphological microglial features specific to cSVD. We identified enlarged somata, an increase in the territory occupied by thickened microglial processes, and an expansion in the number of vascular-associated microglia. In parallel, we characterized microglia in a rodent model of hypertensive cSVD along different durations of arterial hypertension, i.e., early chronic and late chronic hypertension. Microglial somata were already enlarged in early hypertension. In contrast, at late-stage chronic hypertension, they further exhibited elongated branches, thickened processes, and a reduced ramification index, mirroring the findings in human cSVD. An unbiased multidimensional flow cytometric analysis revealed phenotypic heterogeneity among microglia cells within the hippocampus and cortex. At early-stage hypertension, hippocampal microglia exhibited upregulated CD11b/c, P2Y12R, CD200R, and CD86 surface expression. Detailed analysis of cell subpopulations revealed a unique microglial subset expressing CD11b/c, CD163, and CD86 exclusively in early hypertension. Notably, even at early-stage hypertension, microglia displayed a higher association with cerebral blood vessels. We identified several profound clusters of microglia expressing distinct marker profiles at late chronic hypertensive states. In summary, our findings demonstrate a higher vulnerability of the hippocampus, stage-specific microglial signatures based on morphological features, and cell surface protein expression in response to chronic arterial hypertension. These results indicate the diversity within microglia sub-populations and implicate the subtle involvement of microglia in cSVD pathogenesis.

Optimal systolic and diastolic blood pressure threshold that associated with lower risk of white matter hyperintensity progression

Background

The optimal control thresholds for systolic blood pressure (SBP) and diastolic blood pressure (DBP) in patients with white matter hyperintensity (WMH) are still unclear.

Method

A longitudinal retrospective study of patients with brain magnetic resonance imaging (MRI) scans with intervals of more than 3  years was conducted. Blood pressure records during hospitalization and from outpatient visits between baseline and the last MRI scan were collected. The outcome was the change in total WMH from baseline to the final visit.

Results

Among the 965 patients with MRI scans, 457 patients with detailed longitudinal blood pressure records were ultimately included and classified into the WMH absent group (n = 121), mild WMH group (n = 126), and moderate to severe WMH group (n = 210). Both baseline and longitudinal mean SBP, DBP, and SBP SD were significantly associated with WMH severity (p < 0.05). An average SBP of 130-140 mmHg [vs. <130 mmHg, aOR, 1.80, (95% CI, 1.05-3.07), p = 0.03] was associated with a higher risk of WMH progression. DBP ≥ 90 mmHg [vs. <80 mmHg, OR, 1.81, (95% CI, 0.88-3.74), p = 0.02, aOR, 1.54, (95% CI, 0.66-3.53), p = 0.32] was associated with a higher risk of WMH progression, but was not after adjusted for other covariates. Longitudinal BP variability was not significantly associated with WMH progression.

Conclusion

Both SBP and DBP had a stronger relationship with the severity of WMH. A target mean SBP of <130 mmHg and mean DBP of <80 mmHg was associated with a lower risk of WMH progression.

Edaravone dexborneol ameliorates cognitive impairment by regulating the NF-κB pathway through AHR and promoting microglial polarization towards the M2 phenotype in mice with bilateral carotid artery stenosis (BCAS)

Cerebral small vessel disease (CSVD) is one of the most important causes of stroke and vascular dementia, so exploring effective treatment modalities for CSVD is warranted. This study aimed to explore the anti-inflammatory effects of Edaravone dexborneol (C.EDA) in a CSVD model. Mice with CSVD showed distinct cognitive decline, as assessed by the Morris water maze (MWM). Pathological staining verified leakage across the blood‒brain barrier (BBB), microglial proliferation, neuronal loss and demyelination. Western blot analysis demonstrated that M1 microglia dominated prophase and released proinflammatory molecules; the aryl hydrocarbon receptor (AHR) was found to participate in modulating nuclear factor-kappa B (NF-κB) signalling activation through tumour necrosis factor receptor-associated factor-6 (TRAF6). C.EDA treatment resulted in the polarization of microglia from the M1 to the M2 phenotype. Mice sequentially treated with C.EDA exhibited a significant improvement in cognitive function; expression of the anti-inflammatory cytokines and modulatory proteins AHR and TRAF6 was upregulated, while the levels of pNF-κBp65 and pIΚBα were downregulated. C.EDA promoted microglial activation towards the M2 phenotype by upregulating AHR expression, which prevented TRAF6 ubiquitination, promoted NF-κB RelA/p65 protein degradation and inhibited subsequent NF-κB phosphorylation. Mechanistically, the anti-inflammatory effect of C.EDA alleviated neuronal loss and myelin damage, while at the functional level, C.EDA improved cognitive function and thus showed good application prospects.

The importance of microvascular inflammation in ageing and age-related diseases: a position paper from the ESH working group on small arteries, section of microvascular inflammation

Microcirculation is pervasive and orchestrates a profound regulatory cross-talk with the surrounding tissue and organs. Similarly, it is one of the earliest biological systems targeted by environmental stressors and consequently involved in the development and progression of ageing and age-related disease. Microvascular dysfunction, if not targeted, leads to a steady derangement of the phenotype, which cumulates comorbidities and eventually results in a nonrescuable, very high-cardiovascular risk. Along the broad spectrum of pathologies, both shared and distinct molecular pathways and pathophysiological alteration are involved in the disruption of microvascular homeostasis, all pointing to microvascular inflammation as the putative primary culprit. This position paper explores the presence and the detrimental contribution of microvascular inflammation across the whole spectrum of chronic age-related diseases, which characterise the 21st-century healthcare landscape. The manuscript aims to strongly affirm the centrality of microvascular inflammation by recapitulating the current evidence and providing a clear synoptic view of the whole cardiometabolic derangement. Indeed, there is an urgent need for further mechanistic exploration to identify clear, very early or disease-specific molecular targets to provide an effective therapeutic strategy against the otherwise unstoppable rising prevalence of age-related diseases.

The Preventive Effect of Exercise and Oral Branched-Chain Amino Acid Supplementation on Obesity-Induced Brain Changes in Ldlr−/−.Leiden Mice

Exercise and dietary interventions are promising approaches to tackle obesity and its obesogenic effects on the brain. We investigated the impact of exercise and possible synergistic effects of exercise and branched-chain amino acids (BCAA) supplementation on the brain and behavior in high-fat-diet (HFD)-induced obese Ldlr−/−.Leiden mice. Baseline measurements were performed in chow-fed Ldlr−/−.Leiden mice to assess metabolic risk factors, cognition, and brain structure using magnetic resonance imaging. Thereafter, a subgroup was sacrificed, serving as a healthy reference. The remaining mice were fed an HFD and divided into three groups: (i) no exercise, (ii) exercise, or (iii) exercise and dietary BCAA. Mice were followed for 6 months and aforementioned tests were repeated. We found that exercise alone changed cerebral blood flow, attenuated white matter loss, and reduced neuroinflammation compared to non-exercising HFD-fed mice. Contrarily, no favorable effects of exercise on the brain were found in combination with BCAA, and neuroinflammation was increased. However, cognition was slightly improved in exercising mice on BCAA. Moreover, BCAA and exercise increased the percentage of epididymal white adipose tissue and muscle weight, decreased body weight and fasting insulin levels, improved the circadian rhythm, and transiently improved grip strength. In conclusion, BCAA should be supplemented with caution, although beneficial effects on metabolism, behavior, and cognition were observed.