Genetically-Proxied Levels of Vitamin D and Risk of Intracerebral Hemorrhage

Background The evidence linking vitamin D (VitD) levels and spontaneous intracerebral hemorrhage (ICH) remains inconclusive. We tested the hypothesis that lower genetically determined VitD levels are associated with higher risk of ICH. Methods and Results We conducted a 2 sample Mendelian Randomization (MR) study using publicly available summary statistics from published genome-wide association studies of VitD levels (417 580 study participants) and ICH (1545 ICH cases and 1481 matched controls). We used the inverse-variance weighted approach to generate causal estimates and the MR Pleiotropy Residual Sum and Outlier and MR-Egger approaches to assess for horizontal pleiotropy. To account for known differences in their underlying mechanism, we implemented stratified analysis based on the location of the hemorrhage within the brain (lobar or nonlobar). Our primary analysis indicated that each SD decrease in genetically instrumented VitD levels was associated with a 60% increased risk of ICH (odds ratio [OR], 1.60; [95% CI, 1.05-2.43]; P=0.029). We found no evidence of horizontal pleiotropy (MR-Egger intercept and MR Pleiotropy Residual Sum and Outlier global test with P>0.05). Stratified analyses indicated that the association was stronger for nonlobar ICH (OR, 1.87; [95% CI, 1.18-2.97]; P=0.007) compared with lobar ICH (OR, 1.43; [95% CI, 0.86-2.38]; P=0.17). Conclusions Lower levels of genetically proxied VitD levels are associated with higher ICH risk. These results provide evidence for a causal role of VitD metabolism in ICH.

Obesity, Galectin-3, and Incident Heart Failure: The ARIC Study

Background Laboratory data suggest obesity is linked to myocardial inflammation and fibrosis, but clinical data are limited. We aimed to examine the association of obesity with galectin-3, a biomarker of cardiac inflammation and fibrosis, and the related implications for heart failure (HF) risk. Methods and Results We evaluated 8687 participants (mean age 63 years; 21% Black) at ARIC (Atherosclerosis Risk in Communities) Visit 4 (1996-1998) who were free of heart disease. We used adjusted logistic regression to estimate the association of body mass index (BMI) categories with elevated galectin-3 (≥75th sex-specific percentile) overall and across demographic subgroups, with tests for interaction. We used Cox proportional hazards models to assess the combined associations of galectin-3 and BMI with incident HF (through December 31, 2019). Higher BMI was associated with higher odds of elevated galectin-3 (odds ratio [OR], 2.32; 95% CI, 1.88-2.86) for severe obesity ([BMI ≥35 kg/m2] versus normal weight [BMI 18.5-<25 kg/m2]). There were stronger associations of BMI with elevated galectin-3 among women versus men and White versus Black participants (both P-for-interaction <0.05). Elevated galectin-3 was similarly associated with incident HF among people with and without obesity (HR, 1.49; 95% CI, 1.18-1.88; and HR, 1.71; 95% CI, 1.38-2.11, respectively). People with severe obesity and elevated galectin-3 had >4-fold higher risk of HF (HR, 4.19; 95% CI, 2.98-5.88) than those with normal weight and galectin-3 <25th percentile. Conclusions Obesity is strongly associated with elevated galectin-3. Additionally, the combination of obesity and elevated galectin-3 is associated with marked HF risk, underscoring the importance of elucidating pathways linking obesity with cardiac inflammation and fibrosis.

An electron paramagnetic resonance time-course study of oxidative stress in the plasma of electronic cigarette exposed rats

The long-term consequences of electronic cigarette (Ecig) use in humans are not yet known, but it is known that Ecig aerosols contain many toxic compounds of concern. We have recently shown that Ecig exposure impairs middle cerebral artery (MCA) endothelial function and that it takes 3 days for MCA reactivity to return to normal. However, the sources contributing to impairment of the endothelium were not investigated. We hypothesized that the increased levels of oxidative stress markers in the blood are correlated with impaired MCA reactivity. We used electron paramagnetic resonance (EPR) spectroscopy to examine plasma from 4-month-old male Sprague-Dawley rats that were exposed to either air (n = 5) or 1 h Ecig exposure, after which blood samples were collected at varying times after exposure (i.e., 1-4, 24, 48 and 72 h postexposure, n = 4 or 5 in each time group). The EPR analyses were performed using the redox-sensitive hydroxylamine spin probe 1-hydroxy-3-carboxymethyl-2,2,5,5-tetramethyl-pyrrolidine (CMH) to measure the level of reactive oxidant species in the plasma samples. We found that EPR signal intensity from the CM• radical was significantly increased in plasma at 1-4, 24 and 48 h (P < 0.05, respectively) and returned to control (air) levels by 72 h. When evaluating the EPR results with MCA reactivity, we found a significant negative correlation (Pearson's P = 0.0027). These data indicate that impaired cerebrovascular reactivity resulting from vaping is associated with the oxidative stress level (measured by EPR from plasma) and indicate that a single 1 h vaping session can negatively influence vascular health for up to 3 days after vaping. HIGHLIGHTS: What is the central question of this study? Does the time course of oxidative stress triggered by electronic cigarette exposure follow the cerebral vascular dysfunction? What is the main finding and its importance? Electron paramagnetic resonance analysis shows that the oxidative stress induced after a single 1 h exposure to electronic cigarette aerosol takes ≤72 h to return to normal, which mirrors the time course for vascular dysfunction in the middle cerebral artery that we have reported previously.

The Cells of the Vasculature: Advances in the Regulation of Vascular Tone in the Brain and Periphery

The vasculature is a complex tissue in which multiple cell types coordinate the regulation of tissue perfusion in response to hemodynamic and biochemical signals. Advances in this field are continuing to deepen our understanding of the relative importance of these cell types through the body. In the peripheral vasculature, tone is generated primarily by smooth muscle cells and regulated by endothelial cells, and neurons. In the brain parenchyma, unique cell types including pericytes, perivascular astrocytes and microglia, also contribute to the regulation of arterial and capillary tone. Here, we provide a cell-by-cell review of the regulation of vascular tone and highlight recent advances in the regulation of vascular tone in both the periphery and cerebral vasculature.