Arteriolar Wall Research Articles

Significance of intrarenal vascular lesions in Ig A nephropathy prognosis

BackgroundImmunoglobulin A nephropathy (IgAN) is the predominant primary glomerulonephritis globally and remains a subject of active research with a focus on understanding its course and prognosis. Although vascular lesions are associated with IgAN, the current histopathological grading systems do not consider intrarenal vascular lesions when predicting patient prognosis. Therefore, this retrospective study conducted at Kyungpook National University Hospital between October 2016 and December 2021, aimed to elucidate the significance of intrarenal vascular lesions in IgAN by comparing the clinical data of patients with and without such lesions.MethodsData of patients with biopsy-confirmed primary IgAN between October 2016 and June 2021 at Kyungpook National University Hospital (Daegu, South Korea) were collected, and their medical records were reviewed. All slides from these 138 cases were independently pathologically reviewed by two nephropathologists (Y. J. K. and M. S. K.) using light microscope. The vascular lesions included in this study were fibrous intimal thickening, arteriolar wall thickening, and arteriolar hyalinosis. All cases were reviewed according to the Oxford Classification of IgA Nephropathy (2016) and Haas classification.ResultsOf the 138 patients, 88 exhibited at least one intrarenal vascular lesion. Patients with arteriolar wall thickening demonstrated a reduced estimated glomerular filtration rate (eGFR), elevated serum creatinine level and urine protein-to-creatinine ratio, an increased proportion of global glomerulosclerosis, and a higher histologic grade of interstitial fibrosis and tubular atrophy at the time of biopsy.ConclusionArteriolar wall thickening in IgAN are associated with reduced eGFR and global glomerulosclerosis. Moreover, reduced eGFR and global glomerulosclerosis are correlated with the progression to end-stage renal disease. Although the direct correlation between vascular lesions and end-stage renal disease is not entirely clear, a marginally significant association (log-rank test, p = 0.06) was observed with arterial wall thickening. This study suggests the potential importance of vascular lesions in the prognosis of IgAN, encouraging further investigation using larger cohort studies to establish a clearer association.

Neurovascular coupling and CO2 interrogate distinct vascular regulations

Neurovascular coupling (NVC), which mediates rapid increases in cerebral blood flow in response to neuronal activation, is commonly used to map brain activation or dysfunction. Here we tested the reemerging hypothesis that CO2 generated by neuronal metabolism contributes to NVC. We combined functional ultrasound and two-photon imaging in the mouse barrel cortex to specifically examine the onsets of local changes in vessel diameter, blood flow dynamics, vascular/perivascular/intracellular pH, and intracellular calcium signals along the vascular arbor in response to a short and strong CO2 challenge (10 s, 20%) and whisker stimulation. We report that the brief hypercapnia reversibly acidifies all cells of the arteriole wall and the periarteriolar space 3–4 s prior to the arteriole dilation. During this prolonged lag period, NVC triggered by whisker stimulation is not affected by the acidification of the entire neurovascular unit. As it also persists under condition of continuous inflow of CO2, we conclude that CO2 is not involved in NVC.

Abstract P104: Kidney arteriolar responses to liver-targeted small interference RNA (siRNA) targeting angiotensinogen in diabetic rats: comparison with other renin-angiotensin system blockers

Objective: Inhibition of the renin-angiotensin system (RAS) with ACE inhibitors (ACEi) or angiotensin receptor blockers (ARB) is associated with concentric thickening of renal arteries and arterioles and parenchymal disease. Here we evaluated to what degree this also occurs during RAS inhibition with siRNA targeting hepatic angiotensinogen (AGT). Methods: Male hypertensive heterozygous transgenic rats overexpressing mouse renin (TGR(mRen2)27 rats), made diabetic with streptozotocin, were treated with the ARB valsartan (4 mg/kg/day), the ACEi captopril (6 mg/kg/day), AGT siRNA (30 mg/kg every 2 weeks), AGT siRNA + valsartan, or captopril + valsartan for 3 weeks, starting at 15 weeks after induction of diabetes. After 3 weeks of treatment, kidneys were removed, and immunocytochemistry was performed on Bouin’s fixed kidney sections using antibodies against renin or α-smooth muscle actin. Juxtaglomerular index and wall thickness were assessed using tiling pictures of both renin and α-smooth muscle actin sections from the slides. Tubular degeneration was scored by summing up scores for tubular atrophy, interstitial fibrosis, and tubulointerstitial inflammation. Concentric vascular hypertrophy was assessed in a blinded manner. Results: All treatments increased juxtaglomerular index, and the largest increases were observed in dual treatment groups, consistent with the highest degree of RAS blockade in these groups. Tubular scores increased after induction of diabetes, and the highest scores were seen in dual treatment groups, significance versus vehicle being reached in the valsartan + captopril group only (P<0.05). Afferent arteriole wall thickness increased in all treatment groups, and the greatest increases were observed during dual treatment. Finally, concentric vascular hypertrophy was observed in 1 of 7 (14%) diabetic Ren2 rats; this percentage increased during RAS blocker treatment of these rats, numerically reaching the highest values during dual treatment. Conclusions: Our data suggest that, in the hypertensive diabetic rat model, high levels of RAS blockade, irrespective of the type of blockade, may result in an increase in afferent arteriole thickness and concentric vascular hypertrophy. AGT siRNA in combination with RAS inhibitors should be further explored in clinical studies.

O52 KIDNEY ARTERIOLAR RESPONSES TO LIVER-TARGETED SMALL INTERFERENCE RNA (SIRNA) TARGETING ANGIOTENSINOGEN IN DIABETIC RATS: COMPARISON WITH OTHER RENIN-ANGIOTENSIN SYSTEM BLOCKERS

Objective: Inhibition of the renin-angiotensin system (RAS) with ACE inhibitors (ACEi) or angiotensin receptor blockers (ARB) is associated with concentric thickening of renal arteries and arterioles and parenchymal disease. Here we evaluated to what degree this also occurs during RAS inhibition with siRNA targeting hepatic angiotensinogen (AGT). Methods: Male hypertensive heterozygous transgenic rats overexpressing mouse renin (TGR(mRen2)27 rats), made diabetic with streptozotocin, were treated with the ARB valsartan (4 mg/kg/day), the ACEi captopril (6 mg/kg/day), AGT siRNA (30 mg/kg every 2 weeks), AGT siRNA + valsartan, or captopril+valsartan for 3 weeks, starting at 15 weeks after induction of diabetes. After 3 weeks of treatment, kidneys were removed, and immunocytochemistry was performed on Bouin's fixed kidney sections using antibodies against renin or α-smooth muscle actin. Juxtaglomerular index and wall thickness were assessed using tiling pictures of both renin and α-smooth muscle actin sections from the slides. Tubular degeneration was scored by summing up scores for tubular atrophy, interstitial fibrosis, and tubulointerstitial inflammation. Concentric vascular hypertrophy was assessed in a blinded manner. Results: All treatments increased juxtaglomerular index, and the largest increases were observed in dual treatment groups, consistent with the highest degree of RAS blockade in these groups. Tubular scores increased after induction of diabetes, and the highest scores were seen in dual treatment groups, significance versus vehicle being reached in the valsartan+captopril group only (P<0.05). Afferent arteriole wall thickness increased in all treatment groups, and the greatest increases were observed during dual treatment. Finally, concentric vascular hypertrophy was observed in 1 of 7 diabetic Ren2 rats; this percentage increased during RAS blocker treatment of these rats, numerically reaching the highest values during dual treatment. Conclusions: Our data suggest that, in the hypertensive diabetic rat model, high levels of RAS blockade, irrespective of the type of blockade, may result in an increase in afferent arteriole thickness and concentric vascular hypertrophy. AGT siRNA in combination with RAS inhibitors should be further explored in clinical studies.

Association between Hemoglobin A1c and Renal Arteriolar Sclerosis in Subjects Presenting without any Apparent Kidney Dysfunction.

Diabetic kidney disease is a major vascular complication in patients with diabetes mellitus (DM). However, the association between the hemoglobin (Hb)A1c levels, notably the prediabetic levels, and renal pathological changes remains unclear. We investigated the association between the HbA1c levels and renal arteriolar lesions in subjects without any apparent kidney dysfunction using a living kidney donor cohort. Between January 2006 and May 2016, 393 living kidney donors underwent a "zero-time" biopsy at Kyushu University Hospital. The patients were divided into four groups (HbA1c levels ＜5.6%, 5.6%-5.7%, 5.8%-6.4%, and ≥ 6.5%, or diagnosed with DM [DM group]). Renal arteriolar hyalinization and wall thickening were assessed using semi-quantitative grading. We then investigated the association between the HbA1c levels and renal pathological changes. 158 (40.2%) patients had arteriolar hyalinization and 148 (37.6%) showed wall thickening. A significant correlation was observed between the HbA1c levels and wall thickening (p for trend ＜0.001). An elevated HbA1c level was significantly associated with wall thickening according to a multivariable logistic analysis in subjects with HbA1c levels of 5.6%-5.7% and 5.8%-6.4%, and the DM group, compared with those with HbA1c levels of ＜5.6% (odds ratio [OR], 1.91; 95% confidence interval [CI]: [1.03-3.54] for 5.6%-5.7%, OR, 1.96; 95% CI: [1.09-3.53] for 5.8%-6.4%, and OR, 2.86; 95% CI: [0.91-9.01] for the DM group), whereas arteriolar hyalinization did not increase within the nondiabetic HbA1c levels. Elevated high-normal HbA1c levels are considered to be independent risk factors for arteriolar wall thickening. Subclinical renal arteriolar sclerosis may develop in patients with prediabetic HbA1c levels.

Retinal arterial macroaneurysm during hypertension and hypercholesterolemia: About a case at the CHU-IOTA

Arterial macroaneurysms are acquired ecstasies of the wall of a retinal arteriole, most often dependent on the superior temporal arch. We have carried out a description of the clinical appearance and management of a retinal arterial macro-aneurysm; A cardiovascular and diabetic check-up in collaboration with internists; The ophthalmological explorations focused on: Fluorescein angiography, Ocular ultrasound mode B, OCT. There was a subretinal hematoma on the path of the superior temporal artery surrounded by dry exudates, macular atrophy in the right eye. Fasting blood glucose at 10.90 mmol/l (1.96 g/l), total cholesterol 238.50 mg/dl (TN<200), arteriosclerosis index of 6.64 (TN<3.3), triglycerides 304.20 mg/l (TN<150). After 5 years of follow-up, visual acuity rose to 4/10 in the right eye with healing of the lesion, but the assessment remained slightly disturbed. Cardiovascular pathologies are the main causes of retinal arterial macroaneurysms. Macular involvement is responsible for AVB, which can be permanent in the absence of adequate and early treatment. Keywords: Arterial macro-aneurysm, encysted hematoma, ectasia.

The hereditary vessel disease CADASIL

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) is a hereditary small vessel disease of the brain characterized by progressive white matter lesions, subcortical infarcts, and cognitive decline. This autosomal dominant disorder is caused by mutations in the NOTCH3 gene located on chromosome 19, resulting in the accumulation of granular osmiophilic material within the walls of small arteries and arterioles. Clinically, CADASIL typically manifests in mid-adulthood with recurrent ischemic events, migraine with aura, mood disturbances, and cognitive impairment. Neuroimaging plays a crucial role in the diagnosis of CADASIL, with characteristic findings including white matter hyperintensities particularly in the anterior temporal lobe and external capsule.

Hypertension Likely Drives Arteriolar Wall Thickening in Preclinical Diabetic Retinopathy While Diabetes Drives Wall Thickness in Clinical Retinopathy.

Both hypertension and diabetes are known to increase the wall-to-lumen ratio (WLR) of retinal arterioles, but the differential effects are unknown. Here, we study the timing and relative impact of hypertension versus diabetes on the WLR in diabetic retinopathy (DR) to address this unresolved question. This prospective cross-sectional study compared the retinal arteriolar WLR in 17 healthy eyes, 15 with diabetes but no apparent DR (DM no DR), and 8 with diabetic macular edema (DME) and either nonproliferative or proliferative DR. We imaged each arteriole using adaptive optics scanning laser ophthalmoscopy and measured the WLR using ImageJ. Multiple linear regression (MLR) was performed to estimate the effects of hypertension, diabetes, and age on the WLR. Both subjects with DM no DR and subjects with DME had significantly higher WLR than healthy subjects (0.36 ± 0.08 and 0.42 ± 0.08 vs. 0.29 ± 0.07, 1-way ANOVA P = 0.0009). MLR in healthy subjects and subjects with DM no DR showed hypertension had the strongest effect (regression coefficient=0.08, P = 0.009), whereas age and diabetes were not significantly correlated with WLR. MLR in all three groups together (healthy, DM no DR, and DME) showed diabetes had the strongest effect (regression coefficient=0.05, P = 0.02), whereas age and hypertension were not significantly correlated with WLR. Hypertension may be an early driver of retinal arteriolar wall thickening in preclinical DR, independent of age or diabetes, whereas changes specific to DR may drive wall thickening in DME and later DR stages. We offer a framework for understanding the relative contributions of hypertension and diabetes on the vascular wall, and emphasize the importance of hypertension control early in diabetes even before DR onset.

#1189 Сorrelations between laser doppler flowmetry spectral indicators and glycated hemoglobin level in patients with diabetic nephropathy

Abstract Background and Aims Diabetic microangiopathy is a specific vascular complication of diabetes mellitus type 2, which matters to patients' mortality and individual prognosis. Therefore, an important problem is the development of non-invasive methods for the diagnosis of diabetic microangiopathy, such as laser Doppler flowmetry (LDF). This work aimed to analyze some correlations between LDF spectral indicators and the level of glycated hemoglobin in patients with chronic kidney disease and type 2 diabetes. Method The study included 55 patients (26 men and 29 women) with type 2 diabetes mellitus. The age of patients was 58-77 years. The duration of diabetes was more than 5 years. All patients had chronic kidney disease (stage C3-C4) caused by diabetic nephropathy. For Laser Doppler flowmetry we used the “LDF 100C” system (“Biopac Instruments”, USA). Each patient had a 10-minute LDF registration on the skin of the rear of the foot. Using the special software, we have assessed slow, respiratory and pulse flux motion contribution and flux motion index. The next step was a correlation analysis with the glycated hemoglobin level. Results There were several correlations of the spectral LDF indicators with the level of glycated hemoglobin (Table 1). Thus, a negative correlation with the level of glycated hemoglobin was observed for the flux motion index (p=0.04) and the contribution of slow flux motion (p=0.03). On the contrary, for the contribution of pulse flux motion, there was detected a positive correlation with the level of glycated hemoglobin (p<0.01) (Fig. 1). Conclusion Correlations of LDF indicators with the level of glycated hemoglobin can be explained with the correlation of the diabetic microangiopathy progression with the effectiveness of glycemic control. Hyperglycemia is a key pathogenic factor of type 2 diabetes mellitus and its complications. Consequently, in patients with ineffective or less effective glycemic control, a more significant development of diabetic microangiopathy should be expected. An increase in the contribution of pulse flux motion in the laser Doppler flowmetry use guidelines is regarded as an increase in the role of the pulse wave in microcirculatory blood flow modulation. The cause of the latter is most likely a more intensive remodeling of the walls of arterioles against the background of a higher frequency of hyperglycemia episodes. The negative correlation of the contribution of slow flux motion can be explained by a violation of the local mechanisms of microcirculation modulation. The cause of this disorder is the morphofunctional restructuring of the microvessels themselves, the defeat of smooth myocytes in the wall of arterioles and venules, including pacemaker cells, with a violation of the automatic contractile activity of smooth myocytes, as well as endothelial. These factors lead to a shift in the balance of regulation towards systemic factors, which is reflected in the decrease of the flux motion index. A decrease in the flux motion index is regarded as a microcirculation deficiency, which was detected in all patients with type 2 diabetes mellitus. Thus, correlations of the spectral LDF indicators with the level of glycated hemoglobin corresponds to modern ideas about the pathogenesis of diabetic microangiopathy in type 2 diabetes mellitus. These data can be an additional argument in favor of the further development of improving laser Doppler flowmetry using for the tasks of non-invasive diagnosis of microvascular disorders in patients with type 2 diabetes mellitus. The reported study was funded by RFBR, project number 19-315-90080.

THE ROLE OF LATE-ONSET HYPOGONADISM IN THE PATHOGENESIS OF MORPHO-FUNCTIONAL CHANGES IN THE URINARY BLADDER DUE TO BENIGN PROSTATIC HYPERPLASIA

Introduction. One of the key characteristics of the lower urinary tract is its hormone dependence. Pathophysiological mechanisms of lower urinary tract symptoms in patients with benign prostatic hyperplasia include infravesical obstruction, formation of a fibrous framework in the urinary bladder, disruption of the urothelial barrier, and changes in the nervous and vascular networks of the pelvis. However, to date, there is a lack of data on the pathophysiological relationship between testosterone deficiency and morpho-functional changes of the bladder. The purpose of this study is to investigate the role of age-related hypogonadism in the pathogenesis of morpho-functional changes in the urinary bladder among patients with benign prostatic hyperplasia. The results of the examination of 70 patients with benign prostatic hyperplasia, aged from 47 to 83 years (mean age 67.94 ± 7.42 years), were analyzed. The first group consisted of 20 patients, whose disease duration was 4 ± 1.8 years. They had an International Prostate Symptom Score (IPSS) of 16 ± 4.5 points, a maximum flow rate (Qmax ) of 15.8 ± 2.4 ml/s, an average flow rate (Qave) of 12.8 ± 2.8 ml/s, and no post-void residual. The second group included 20 patients with incomplete bladder emptying, with a disease duration of 5.8 ± 3.5 years. Their IPSS was 26 ± 3.9 points, Qmax was 10.8 ± 2.5 ml/s, Qave was 4.4 ± 1.4 ml/s, and post-void residual was 150.1 ± 80.8 ml. The third group comprised 30 patients who had undergone cystostomy, with a disease duration of 10.6 ± 3.3 years. Before cystostomy, their IPSS was 33.1 ± 1.88 points, and post-void residual was 1093.3 ± 458.8 ml. During surgery, all patients with benign prostatic hyperplasia were taken a biopsy from the anterior wall of the bladder. In benign prostatic hyperplasia patients in the stage of bladder compensation, the level of testosterone was 15.39±1.44 nmol/l, the Aging Males Symptoms indicator was 24.80±5.78 points. Morphometric analysis of bladder tissue demonstrated the following: the diameter of the lumen of arterioles was 27.96±2.14 μm, the thickness of the arteriole wall was 16.03±1.83 μm, the Kernoghan index for arterioles was 1.22±0.17, the specific gravity of connective tissue made 4.48±0.82%, the diameter of SMCs was 7.46±1.66 μm. In benign prostatic hyperplasia patients in the stage of bladder subcompensation, the level of testosterone was 10.92±2.24 nmol/l, the Aging Males Symptoms index was 37.9±8.0 points. Morphometric analysis of bladder tissue revealed the following: the diameter of the arteriole lumen was 23.78±1.62 μm, the thickness of the arteriole wall was 18.30±1.32 μm, the Kernoghan index for arterioles was q1.65±0.18, the specific gravity of the connective tissue made up 11.80±1.22%, the diameter of SMCs was 7.07±1.93 μm. In benign prostatic hyperplasia patients in the stage of bladder decompensation, the level of testosterone is 9.66±2.13 nmol/l, the Aging Males Symptoms index is 55.80±6.69 points. Morphometric analysis of bladder tissue showed the following: the diameter of the arteriole lumen was 19.0±2.08 μm, the thickness of the arteriole wall – 21.01±1.57 μm, the Kernoghan index for arterioles was 2.41±0.32, the specific gravity of the connective tissue made up 29. 46±1.35%, the diameter of SMCs was 4.75±1.87 μm. The obstructive component is not the only causal factor of bladder decompensation in patients with benign prostatic hyperplasia. A decrease in the level of testosterone triggers a cascade of pathological processes that negatively affect the morpho-functional state of the prostate gland and worsen the results of surgical treatment of patients with benign prostatic obstruction.

Effect of estrogen receptor α on cardiopulmonary adaptation to chronic developmental hypoxia in a rat model.

Humans living at high-altitude (HA) have adapted to this environment by increasing pulmonary vascular and alveolar growth. RNA sequencing data from a novel murine model that mimics this phenotypical response to HA suggested estrogen signaling via estrogen receptor alpha (ERα) may be involved in this adaptation. We hypothesized ERα was a key mediator in the cardiopulmonary adaptation to chronic hypoxia and sought to delineate the mechanistic role ERα contributes to this process by exposing novel loss-of-function ERα mutant (ERαMut) rats to simulated HA. ERα mutant or wild-type (wt) rats were exposed to normoxia or hypoxia starting at conception and continued postnatally until 6 wk of age. Both wt and ERαMut animals born and raised in hypoxia exhibited lower body mass and higher hematocrits, total alveolar volumes (Va), diffusion capacities of carbon monoxide (DLCO), pulmonary arteriole (PA) wall thickness, and Fulton indices than normoxia animals. Right ventricle adaptation was maintained in the setting of hypoxia. Although no major physiologic differences were seen between wt and ERαMut animals at either exposure, ERαMut animals exhibited smaller mean linear intercepts (MLI) and increased PA total and lumen areas. Hypoxia exposure or ERα loss-of-function did not affect lung mRNA abundance of vascular endothelial growth factor, angiopoietin 2, or apelin. Sexual dimorphisms were noted in PA wall thickness and PA lumen area in ERαMut rats. In summary, in room air-exposed rats and rats with peri- and postnatal hypoxia exposure, ERα loss-of-function was associated with decreased alveolar size (primarily driven by hypoxic animals) and increased PA remodeling.NEW & NOTEWORTHY By exposing novel loss-of-function estrogen receptor alpha (Erα) mutant rats to a novel model of human high-altitude exposure, we demonstrate that ERα has subtle but inconsistent effects on endpoints relevant to cardiopulmonary adaptation to chronic hypoxia. Given that we observed some histologic, sex, and genotype differences, further research into cell-specific effects of ERα during hypoxia-induced cardiopulmonary adaptation is warranted.

CORRELATION BETWEEN RETINAL MICROCIRCULATION, ECHOCARDIOGRAPHIC PARAMETERS AND MYOCARDIAL CORONARY FLOW RESERVE

Objective: Arterial hypertension causes cardiac functional and structural alterations. In hypertensive patients without flow-limiting epicardial coronary artery disease, we investigated the possible relationship between retinal microcirculation, positron emission tomography myocardial blood flow (MBF) and echocardiographic parameters of left ventricular (LV) performance, including mechano-energetic efficiency indexed for myocardial mass (MEEi) Design and method: Nineteen hypertensive patients (mean age 65 ± 11, 10 F) without flow-limiting epicardial coronary artery disease underwent patients wall-to-lumen ratio (WLR) and the cross-sectional area of the vascular wall (WCSA) of retinal arterioles by an Adaptive Optics (AO) retinal camera, echocardiography, including MEEi computation, and cardiac 13NH3 positron emission tomography (13NH3 PET) with assessment of myocardial coronary flow reserve (CFR). A positive 13NH3 PET was defined as a ratio of stress (regadenoson) myocardial blood flow (MBF)/mass and resting MBF/mass lower than 2. Results: No significant differences of demographic parameters were observed between patients with positive (n=6) vs negative (n=13) 13NH3 PET. In all patients WLR was significantly related to BMI (0,50, p=0.02), age (r=0.49, p=0.03)and LVMi (r=0.48, p=0.03) at univariate analysis. A negative correlation was also observed between WLR and total CFR (-0.64, p=0.003) and MMEi (-0.35, p=0.13). The relationship between WLR and CFR remained significant after adjustment for age and BMI (r=-0.49, p=0.047). Conclusions: In hypertensive patients without flow-limiting epicardial coronary artery disease, retinal WLR could reflect the presence of structural alterations in coronary microcirculation, possibly contributing to an impairment of CFR and to early LV dysfunction, as detected by low values of MEEi.

CURRENT OVERVIEW OF CLINICAL AND RADIOLOGICAL FINDINGS ASSOCIATED WITH CEREBRAL AMYLOID ANGIOPATHY

Cerebral amyloid angipopathy (CAA), the second most common cause of spontaneous acute intracerebral hemorrhage after hypertension in the elderly population is characterized by brain parenchymal damage secondary to hemorrhage and ischemia caused by the accumulation of Aβ protein in the walls of small arteries and arterioles. Advanced age is the most significant risk factor for CAA. While the definitive diagnosis requires histopathological examination through autopsy/biopsy, the probable or possible diagnosis of CAA is based on clinical features as well as characteristic neuroimaging findings. With the increasing elderly population and the growing prevalence of succesibility-weighted magnetic resonance imaging sequences in routine, it becomes imperative to have a thorough understanding of the imaging spectrum associated with CAA. Early diagnosis is extremely critical in patients with CAA who have not yet developed intracranial hemorrhage. Furthermore, patients with CAA may present clinically transient focal neurological episodes or cognitive impairment, which can be mistaken for transient ischemic attacks caused by convexity subarachnoid hemorrhage. Additionally, before initiating newly introduced anti-amyloid monoclonal antibody drugs in Alzheimer's disease, it is necessary to exclude signs of CAA. Moreover, the anticipated side effects of these drugs often manifest imaging abnormalities resembling inflammation or bleeding associated with CAA, necessitating familiarity with the imaging findings of CAA. In this review, the pathophysiology, clinical manifestations, and radiological findings of sporadic CAA will be detailed.

A computational model predicts sex-specific responses to calcium channel blockers in mammalian mesenteric vascular smooth muscle

The function of the smooth muscle cells lining the walls of mammalian systemic arteries and arterioles is to regulate the diameter of the vessels to control blood flow and blood pressure. Here, we describe an in silico model, which we call the ‘Hernandez–Hernandez model’, of electrical and Ca2+ signaling in arterial myocytes based on new experimental data indicating sex-specific differences in male and female arterial myocytes from murine resistance arteries. The model suggests the fundamental ionic mechanisms underlying membrane potential and intracellular Ca2+ signaling during the development of myogenic tone in arterial blood vessels. Although experimental data suggest that KV1.5 channel currents have similar amplitudes, kinetics, and voltage dependencies in male and female myocytes, simulations suggest that the KV1.5 current is the dominant current regulating membrane potential in male myocytes. In female cells, which have larger KV2.1 channel expression and longer time constants for activation than male myocytes, predictions from simulated female myocytes suggest that KV2.1 plays a primary role in the control of membrane potential. Over the physiological range of membrane potentials, the gating of a small number of voltage-gated K+ channels and L-type Ca2+ channels are predicted to drive sex-specific differences in intracellular Ca2+ and excitability. We also show that in an idealized computational model of a vessel, female arterial smooth muscle exhibits heightened sensitivity to commonly used Ca2+ channel blockers compared to male. In summary, we present a new model framework to investigate the potential sex-specific impact of antihypertensive drugs.

A computational model predicts sex-specific responses to calcium channel blockers in mammalian mesenteric vascular smooth muscle.

The function of the smooth muscle cells lining the walls of mammalian systemic arteries and arterioles is to regulate the diameter of the vessels to control blood flow and blood pressure. Here, we describe an in silico model, which we call the 'Hernandez-Hernandez model', of electrical and Ca2+ signaling in arterial myocytes based on new experimental data indicating sex-specific differences in male and female arterial myocytes from murine resistance arteries. The model suggests the fundamental ionic mechanisms underlying membrane potential and intracellular Ca2+ signaling during the development of myogenic tone in arterial blood vessels. Although experimental data suggest that KV1.5 channel currents have similar amplitudes, kinetics, and voltage dependencies in male and female myocytes, simulations suggest that the KV1.5 current is the dominant current regulating membrane potential in male myocytes. In female cells, which have larger KV2.1 channel expression and longer time constants for activation than male myocytes, predictions from simulated female myocytes suggest that KV2.1 plays a primary role in the control of membrane potential. Over the physiological range of membrane potentials, the gating of a small number of voltage-gated K+ channels and L-type Ca2+ channels are predicted to drive sex-specific differences in intracellular Ca2+ and excitability. We also show that in an idealized computational model of a vessel, female arterial smooth muscle exhibits heightened sensitivity to commonly used Ca2+ channel blockers compared to male. In summary, we present a new model framework to investigate the potential sex-specific impact of antihypertensive drugs.

PKCε activator protects hippocampal microvascular disruption and memory defect in 3×Tg-Alzheimer's disease mice with cerebral microinfarcts.

Current evidence suggests that microvessel disease is involved in Alzheimer's disease (AD). Cerebrovascular disease correlates with cardiovascular disease and is complicated in ≈40% of AD patients. The protein kinase C (PKC) ε activator DCPLA can stimulate human antigen (Hu) R that prevents degradation and promotes the translation of mitochondrial Mn-superoxide dismutase (MnSOD) and vascular endothelial growth factor-A (VEGF) mRNAs. To induce brain microinfarcts, we injected triple transgenic (3×Tg) and wild-type (WT) control mice with microbeads (20 μm caliber) into common carotid arteries, with or without the DCPLA-ME (methyl-ester) for 2 weeks. After water maze training, mice at 16 months old were examined for confocal immunohistochemistry at a single cell or microvessel level in the hippocampal CA1 area, important for spatial memory storage, and in the dorsal hippocampus by western blots. In 3×Tg mice without cerebral microinfarcts, an accelerating age-related increase in (mild) oxidative stress and hypoxia inducible factor (HIF)-1α, but a reduction in VEGF, mitochondrial transcription factor A (TFAM), and MnSOD were associated with capillary loss. The change was less pronounced in arterioles. However, in 3×Tg mice with cerebral microinfarcts, increasing arteriolar diameter and their wall cells were related with the strong oxidative DNA damage 8-hydroxy-2'-deoxyguanosine (8-OHdG), apoptosis (cleaved caspase 3), and sustained hypoxia (increased HIF-1α and VEGF/PKCε/extracellular signal regulated kinase or ERK pathway). Microocclusion enhanced the loss of the synaptic marker spinophilin, astrocytic number, and astrocyte-vascular coupling areas and demyelination of axons. DCPLA-ME prevented spatial memory defect; strong oxidative stress-related apoptosis; sustained hypoxia (by reducing HIF-1α and VEGF); and exaggerated cell repair in arteriolar walls, pericapillary space dilation, neuro-glial-vascular disruption, and demyelination. In conclusion, in 3×Tg mice with cerebral microinfarcts, sustained hypoxia (increased HIF-1α and VEGF signals) is dominant with arteriolar wall thickening, and DCPLA has a protective effect on sustained hypoxia.

Prenatal treprostinil improves pulmonary arteriolar hypermuscularization in the rabbit model of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a congenital malformation characterized by pulmonary hypoplasia, pulmonary hypertension, and cardiac dysfunction. Pulmonary hypertension represents the major cause of neonatal mortality and morbidity. Prenatal diagnosis allows assessment of severity and selection of foetal surgery candidates. We have shown that treprostinil, a prostacyclin analogue with an anti-remodelling effect, attenuates the relative hypermuscularization of the pulmonary vasculature in rats with nitrofen-induced CDH. Here we confirm these observations in a large animal model of surgically-created CDH. In the rabbit model, subcutaneous maternal administration of treprostinil at 150 ng/kg/min consistently reached target foetal concentrations without demonstrable detrimental foetal or maternal adverse effects. In pups with CDH, prenatal treprostinil reduced pulmonary arteriolar proportional medial wall thickness and downregulated inflammation and myogenesis pathways. No effect on alveolar morphometry or lung mechanics was observed. These findings provide further support towards clinical translation of prenatal treprostinil for CDH.

Brain MRI diffusion abnormalities associated with arteriolosclerosis pathology

AbstractBackgroundBrain arteriolosclerosis is one of the main pathologies of cerebral small vessel disease. It involves the thickening of the vessel wall and stenosis of arterioles causing lower cognitive and motor function, and higher odds of dementia. This work intends to explore the independent association of brain arteriolosclerosis with diffusion abnormalities in the white matter (WM) of community‐based older adults.MethodParticipants comprised community‐dwelling older adults (N = 175) from four studies of aging (Rush Memory and Aging Project, Religious Orders Study, Minority Aging Research Study, and Clinical Core of the Rush Alzheimer’s Disease Research Center) (Fig.1A). Whole brain 3D T1w MPRAGE, T2w FLAIR, and diffusion‐weighted MRI (2×2×2mm3, b = 1,000s/mm2 for 40 diffusion gradient directions, and 6 b = 0s/mm2 volumes) data were acquired in‐vivo using 3T MRI scanners. The fractional anisotropy (FA) and trace maps were transformed to the space of the IIT Human Brain Atlas v.5.0 and projected onto the WM skeleton of the IIT atlas. Following a participant’s death, the extracted brain underwent a detailed evaluation by a neuropathologist. Assessed neuropathologies included arteriolosclerosis, Alzheimer’s pathology, LATE‐NC, gross and microscopic infarcts, atherosclerosis, and cerebral amyloid angiopathy (Fig.1B). Linear regression was used in voxels of the WM skeleton to test the association of FA or trace with the severity of arteriolosclerosis controlling for all other neuropathologies, white matter hyperintensities (WMH), demographic variables (age at scan, sex, years of education), antemortem interval to imaging, and scanner. The statistical analyses were carried out using FSL’s PALM tool with 5,000 permutations and threshold‐free cluster enhancement. The significance level was set at p<0.05, after family‐wise error rate (FWER) correction for multiple testing.ResultArteriolosclerosis score was associated with lower FA (Fig.2) and higher trace (Fig.3) of the diffusion tensor throughout the brain in multiple WM regions, even in areas typically free of WMH. Other neuropathologies or the effects of WMH on diffusion characteristics had no impact on these relationships.ConclusionThe current study showed that, regardless of the impact of other neuropathologies or visible WMH, brain arteriolosclerosis in older persons is associated with diffusion abnormalities that extend throughout the WM.

Brain MRI diffusion abnormalities associated with arteriolosclerosis pathology

AbstractBackgroundBrain arteriolosclerosis is one of the main pathologies of cerebral small vessel disease. It involves the thickening of the vessel wall and stenosis of arterioles causing lower cognitive and motor function, and higher odds of dementia. This work intends to explore the independent association of brain arteriolosclerosis with diffusion abnormalities in the white matter (WM) of community‐based older adults.MethodParticipants comprised community‐dwelling older adults (N = 175) from four studies of aging (Rush Memory and Aging Project, Religious Orders Study, Minority Aging Research Study, and Clinical Core of the Rush Alzheimer’s Disease Research Center) (Fig.1A). Whole brain 3D T1w MPRAGE, T2w FLAIR, and diffusion‐weighted MRI (2×2×2mm3, b = 1,000s/mm2 for 40 diffusion gradient directions, and 6 b = 0s/mm2 volumes) data were acquired in‐vivo using 3T MRI scanners. The fractional anisotropy (FA) and trace maps were transformed to the space of the IIT Human Brain Atlas v.5.0 and projected onto the WM skeleton of the IIT atlas. Following a participant’s death, the extracted brain underwent a detailed evaluation by a neuropathologist. Assessed neuropathologies included arteriolosclerosis, Alzheimer’s pathology, LATE‐NC, gross and microscopic infarcts, atherosclerosis, and cerebral amyloid angiopathy (Fig.1B).Linear regression was used in voxels of the WM skeleton to test the association of FA or trace with the severity of arteriolosclerosis controlling for all other neuropathologies, white matter hyperintensities (WMH), demographic variables (age at scan, sex, years of education), antemortem interval to imaging, and scanner. The statistical analyses were carried out using FSL’s PALM tool with 5,000 permutations and threshold‐free cluster enhancement. The significance level was set at p<0.05, after family‐wise error rate (FWER) correction for multiple testing.ResultArteriolosclerosis score was associated with lower FA (Fig.2) and higher trace (Fig.3) of the diffusion tensor throughout the brain in multiple WM regions, even in areas typically free of WMH. Other neuropathologies or the effects of WMH on diffusion characteristics had no impact on these relationships.ConclusionThe current study showed that, regardless of the impact of other neuropathologies or visible WMH, brain arteriolosclerosis in older persons is associated with diffusion abnormalities that extend throughout the WM.

High-Density Lipoprotein Inhibits Microvascular and Arterial Thrombosis in Mice By Attenuating VWF Self-Association

Background: Von Willebrand factor (VWF) mediates platelet adhesion and aggregation in primary hemostasis and thrombosis. The thrombogenicity of VWF depends on its self-association into fibers and its ability to efficiently capture platelets under high shear stress. We have shown that high shear promotes self-association of VWF into hyperadhesive strands and fibers, and that this process can be enhanced by low density lipoprotein (LDL) and attenuated by high density lipoprotein (HDL). In a model of thrombotic microangiopathy induced by VWF infusion into ADAMTS13-deficient mice, HDL attenuated the thrombocytopenia induced by the VWF challenge, suggesting that HDL may attenuate other types of thrombosis. Aims: To study the effect of HDL on microvascular and arterial thrombosis in mice by intravital microscopy. Methods: Microvascular thrombosis was induced in ADAMTS13-deficient mice by (1) local stimulation of mesenteric venules with calcium ionophore, and (2) infusion of high doses of recombinant human VWF (rVWF). The effect of HDL on VWF-platelet thrombus formation and deposition in the microvasculature was monitored microscopically. Arterial thrombosis was induced in wild-type (WT) mice by (1) laser-induced cremaster injury, and (2) FeCl 3-induced carotid artery injury. The effect of HDL on arterial thrombosis was also monitored microscopically. Results: When we induced microvascular thrombosis with ionophore, ADAMTS13-deficient mice evinced robust local platelet adhesion, platelet string formation, and thrombus embolization. Time to thrombus resolution was significantly prolonged (about 15 min) compared to that in WT mice (< 5 min). In mice pretreated with HDL (100 mg/kg), platelet deposition was largely prevented, with only occasional single platelets adhering. The differences in the extent of thrombi deposition and time to thrombus resolution between HDL-treated and untreated mice were both statistically significant. In the VWF challenge microvascular thrombosis model, rVWF infusion into ADAMTS13-deficient mice induced platelet adhesion to endothelium-associated VWF fibers in the cremaster microcirculation, forming long strings on the walls of arterioles and venules. Many microvessels became completely occluded. The prothrombotic effect persisted over 90 minutes. In contrast, pretreatment with HDL (100 mg/kg) led to significantly reduced platelet adhesion and string formation. Vessel occlusion was almost completely prevented. When thrombosis was induced in the cremaster arterioles of WT mice, HDL pretreatment resulted in notably decreased platelet accumulation and fibrin deposition in growing thrombi. HDL pretreatment also destabilized the thrombi and led to frequent embolization. In the FeCl 3-induced carotid artery injury model, HDL pretreatment slowed thrombus growth, enhanced thrombus embolization, and delayed vessel occlusion. Conclusion(s): The results demonstrate that VWF self-association is an important mechanism promoting thrombosis in large and small vessels. Our results show that HDL possesses a novel antithrombotic effect by inhibiting VWF self-association, preventing thrombosis in both small and large vessels. These results suggest that increasing the plasma HDL level can be exploited to prevent and treat thrombotic microangiopathies and arterial thrombosis.