Diagnosis and prevention of atherosclerotic cerebral infarction

The role of the gut microbiome and its metabolites in cerebrovascular diseases

The gut microbiome is critically involved in maintaining normal physiological function in the host. Recent studies have revealed that alterations in the gut microbiome contribute to the development and progression of cerebrovascular disease via the microbiota-gut-brain axis (MGBA). As a broad communication network in the human body, MGBA has been demonstrated to have significant interactions with various factors, such as brain structure and function, nervous system diseases, etc. It is also believed that the species and composition of gut microbiota and its metabolites are intrinsically linked to vascular inflammation and immune responses. In fact, in fecal microbiota transplantation (FMT) research, specific gut microbiota and downstream-related metabolites have been proven to not only participate in various physiological processes of human body, but also affect the occurrence and development of cerebrovascular diseases directly or indirectly through systemic inflammatory immune response. Due to the high mortality and disability rate of cerebrovascular diseases, new treatments to improve intestinal dysbacteriosis have gradually attracted widespread attention to better ameliorate the poor prognosis of cerebrovascular diseases in a non-invasive way. This review summarizes the latest advances in the gut microbiome and cerebrovascular disease research and reveals the profound impact of gut microbiota dysbiosis and its metabolites on cerebrovascular diseases. At the same time, we elucidated molecular mechanisms whereby gut microbial metabolites regulate the expression of specific interleukins in inflammatory immune responses. Moreover, we further discuss the feasibility of novel therapeutic strategies targeting the gut microbiota to improve the outcome of patients with cerebrovascular diseases. Finally, we provide new insights for standardized diagnosis and treatment of cerebrovascular diseases.

Homocysteine might increase the risk of recurrence in patients presenting with primary cerebral infarction

PURPOSE

Although hyperhomocysteinemia (Hhcy) is a risk factor for cerebral infarction, its effect on recurrent cerebral infarction is less-defined. We aimed to investigate the association of Hhcy and increased risk of recurrent cerebral infarct.

MATERIALS AND METHODS

From 2011 to 2013, we recruited 231 primary cerebral infarct patients that were divided to a Hhcy group (n = 105) and a control group (n = 126) according to plasma homocysteinemia (Hcy) levels exceeding 15 μmol/L. In this prospective study, risk factors such as gender, age, blood lipid and glucose levels, history of diabetes, high blood pressure, smoking habits and plasma Hhcy levels were determined. A three-year follow-up compared differences in cerebral infarction recurrence rates. Statistical analyses identified whether plasma Hhcy levels were an independent risk factor for recurrent cerebral infarction.

RESULTS

Triglyceride and low-density lipoprotein (LDL) levels in the Hhcy group were significantly higher than controls, and cerebral infarct recurrence rates in the Hhcy group exceeded control subject rates through the three-year follow-up (p = .021, p = .036 and p = .025). Cox proportional hazards modeling showed that elevated Hhcy levels (hazard ratio [HR] = 3.062, p < .001), increased age (HR = 1.069, p < .01), circulating triglyceride levels (HR = 1.686, p = .048), and relative National Institutes of Health Stroke (NIHSS) score (HR = 1.068, p = .016) were risk factors for recurrent cerebral infarction.

CONCLUSIONS

Level of Hhcy was a risk factor for recurrent cerebral infarction. Further, particular demographic and clinical outcomes including age, relative NIHSS scores, and circulating triglyceride levels were markedly associated with the occurrence of cerebral infarction.

Hyperspectral imaging fluorescence excitation scanning spectral characteristics of remodeled mouse arteries

Coronary artery disease (CAD), or atherosclerosis, is responsible for nearly a third of all American deaths annually. Detection of plaques and differentiation of plaque stage remains a complicating factor for treatment. Classification of plaque before significant blockage or rupture could inform clinical decisions and prevent mortality. Current detection methods are either nonspecific, slow, or require the use of potentially harmful contrast agents. Recent advances in hyperspectral imaging could be used to detect changes in the autofluorescence of arteries associated with vessel remodeling and subsequent plaque formation and could detect and classify existing lesions. Here, we present data comparing spectral image characteristics of a mouse model designed to undergo vessel remodeling. C57Bl/6 mice underwent ligation of three of four caudal branches of the left common carotid artery (left external carotid, internal carotid, and occipital artery) with the superior thyroid artery left intact under IACUC approved protocol. Vessels were harvested at a variety of timepoints to compare degrees of remodeling, including 4 weeks and 5 months post-surgery. Immediately following harvest, vessels were prepared by longitudinal opening to expose the luminal surface to a 20X objective. A custom inverted microscope (TE-2000, Nikon Instruments) with a Xe arc lamp and thin film tunable filter arrary (Versachrome, Semrock, Inc.) were used to achieve spectral imaging. Excitation scans utilized wavelengths between 340 nm and 550 nm in 5 nm increments. Hyperspectral data were generated and analyzed with custom Matlab scripts and visualized in ENVI. Preliminary data suggest consistent spectral features associated with control and remodeled vessels.

Novel IL-6-secreting γδT cells increased in patients with atherosclerotic cerebral infarction

Mounting evidence has suggested that inflammation associated with interleukin (IL)‑6 and T‑helper (Th)17 cells, has a role in the development of atherosclerotic cerebral infarction (ACI). However, it remains unclear which population of cells determines the levels of IL‑6, and the role of IL‑6‑secreting cells in inducing Th17 cell production. In the present study, IL‑6 levels were determined in patients with ACI, by ELISA. The percentage of CD3+T, CD4+T, CD8+T, CD11c+ dendritic cells and γδT cells were determined by flow cytometry, and the correlation between cytokine IL‑6 and γδT cells was determined by statistical analysis. An in vitro culture assay was used to determine whether γδT cells secreted high levels of IL‑6, and induced production of Th17 cells. The patients with ACI had significantly higher levels of IL‑6 and γδT cells. Furthermore, γδT cells were associated with the secretion of a high level of IL‑6 in patients with ACI. These results indicate that γδT cells are novel IL‑6‑secreting cells, which from then on were known as γδT6 cells. In addition, the novel γδT6 cells induced Th17‑cell production, and this induction was dependent on IL‑6. Novel γδT6 cells increased the induction of Th17‑cell production in patients with ACI. The results of the present study suggest that novel γδT6 cells may be a target for strategic therapies of ACI.

Multimodality imaging of carotid atherosclerotic plaque: Going beyond stenosis

Apart from the degree of stenosis, the morphology of carotid atherosclerotic plaques and presence of neovascularization are important factors that may help to evaluate the risk and ‘vulnerability’ of plaques and may also influence the choice of treatment. In this article, we aim to describe the techniques and imaging findings on CTA, high resolution MRI and contrast enhanced ultrasound in the evaluation of carotid atherosclerotic plaques. We also discuss a few representative cases from our institute with the related clinical implications.

Elastin haploinsufficiency induces alternative aging processes in the aorta

Elastin, the main component of elastic fibers, is synthesized only in early life and provides the blood vessels with their elastic properties. With aging, elastin is progressively degraded, leading to arterial enlargement, stiffening, and dysfunction. Also, elastin is a key regulator of vascular smooth muscle cell proliferation and migration during development since heterozygous mutations in its gene (Eln) are responsible for a severe obstructive vascular disease, supravalvular aortic stenosis, isolated or associated to Williams syndrome. Here, we have studied whether early elastin synthesis could also influence the aging processes, by comparing the structure and function of ascending aorta from 6- and 24-month-old Eln+/- and Eln+/+ mice. Eln+/- animals have high blood pressure and arteries with smaller diameters and more rigid walls containing additional although thinner elastic lamellas. Nevertheless, longevity of these animals is unaffected. In young adult Eln+/- mice, some features resemble vascular aging of wild-type animals: cardiac hypertrophy, loss of elasticity of the arterial wall through enhanced fragmentation of the elastic fibers, and extracellular matrix accumulation in the aortic wall, in particular in the intima. In Eln+/- animals, we also observed an age-dependent alteration of endothelial vasorelaxant function. On the contrary, Eln+/- mice were protected from several classical consequences of aging visible in aged Eln+/+ mice, such as arterial wall thickening and alteration of alpha(1)-adrenoceptor-mediated vasoconstriction. Our results suggest that early elastin expression and organization modify arterial aging through their impact on both vascular cell physiology and structure and mechanics of blood vessels.

The vulnerable, or high-risk, atherosclerotic plaque: noninvasive MR imaging for characterization and assessment

"Vulnerable" plaques are atherosclerotic plaques that have a high likelihood to cause thrombotic complications, such as myocardial infarction or stroke. Plaques that tend to progress rapidly are also considered to be vulnerable. Besides luminal stenosis, plaque composition and morphology are key determinants of the likelihood that a plaque will cause cardiovascular events. Noninvasive magnetic resonance (MR) imaging has great potential to enable characterization of atherosclerotic plaque composition and morphology and thus to help assess plaque vulnerability. A classification for clinical, as well as pathologic, evaluation of vulnerable plaques was recently put forward in which five major and five minor criteria to define vulnerable plaques were proposed. The purpose of this review is to summarize the status of MR imaging with regard to depiction of the criteria that define vulnerable plaques by using existing MR techniques. The use of MR imaging in animal models and in human disease in various vascular beds, particularly the carotid arteries, is presented.

Clinical experience and applications of drug-eluting stents in the noncoronary vasculature, bile duct and esophagus

OBJECTIVE

To review the use of drug-eluting stents outside the coronary artery.

FINDINGS

The vast majority of research and clinical data on drug-eluting stents are from their use in coronary artery atherosclerosis; however, these devices can be used outside the coronary circulation in both vascular and nonvascular structures. In noncoronary arteries the principle indication for drug-eluting vascular stents is the same as in the coronary circulation, prevention of restenosis. Human experience has been essentially limited to trials or compassionate use; two small controlled studies and a number of small observational single center reports have been published, and there are trials in progress. To date the data have not been as compelling as in the coronary circulation. The physical characteristics of each vascular bed such as external compressive forces, blood flow rates, wall thickness relative to lumen size, and vessel wall composition differ significantly from the coronary circulation and each presents unique challenges to local drug delivery. Outside the vascular bed, the principle expected use is the prevention of tissue ingrowth after stent insertion in tubular structures such as the trachea, esophagus or bile ducts.

CONCLUSIONS

Considerable further study of drug-eluting stents will be required in each anatomic region to determine the ideal stent/drug combination and clinical appropriateness.