Gut vascular barrier impairment leads to intestinal bacteria dissemination and colorectal cancer metastasis to liver

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Upregulation of Shiga Toxin Receptor CD77/Gb3 and Interleukin‐1β Expression in the Brain of EHEC Patients with Hemolytic Uremic Syndrome and Neurologic Symptoms

In 2011, a large outbreak of Shiga toxin‐producing enterohemorrhagic Escherichia coli (EHEC) infections occurred in northern Germany, which mainly affected adults. Out of 3842 patients, 104 experienced a complicated course comprising hemolytic uremic syndrome and neurological complications, including cognitive impairment, aphasia, seizures and coma. T2 hyperintensities on magnet resonance imaging (MRI) bilateral in the thalami and in the dorsal pons were found suggestive of a metabolic toxic effect. Five of the 104 patients died because of toxic heart failure. In the present study, the post‐mortem neuropathological findings of the five EHEC patients are described. Histological investigation of 13 brain regions (frontal, temporal, occipital cortex, corpora mammillaria, thalamus, frontal operculum, corona radiata, gyrus angularis, pons, medulla oblongata, cerebellar vermis and cerebellar hemisphere) showed no thrombosis, ischemic changes or fresh infarctions. Further, no changes were found in electron microscopy. In comparison with five age‐matched controls, slightly increased activation of microglia and a higher neuronal expression of interleukin‐1β and of Shiga toxin receptor CD77/globotriaosylceramide 3 was observed. The findings were confirmed by Western blot analyses. It is suggested that CD77/globotriaosylceramide upregulation may be a consequence to Shiga toxin exposure, whereas increased interleukin‐1β expression may point to activation of inflammatory cascades.     

Wnt/Frizzled signaling in angiogenesis

The roles of growth factors such as angiopoietin (Ang) and vascular endothelial growth factor (VEGF) in angiogenesis have been known for some time, yet we have just an incipient appreciation for the contribution of Wnts to this process. Cellular proliferation and polarity, apoptosis, branching morphogenesis, inductive processes, and the maintenance of stem cells in an undifferentiated, proliferative state are all regulated by Wnt signaling. The development and maintenance of vascular structures are dependent on all these processes, and their orchestration has, to some extent, been revealed in studies of VEGF and Ang receptors. Recent evidence links the Wnt/Frizzled signaling pathway to proper vascular growth in mammals but our knowledge of Wnt function in the vasculature is rudimentary. Further insight into vascular development and the process of angiogenesis depends on evaluating the function of novel endothelial regulatory pathways such as Wnt/Frizzled signaling.     

Plexin-B2 promotes invasive growth of malignant glioma

Invasive growth is a major determinant of the high lethality of malignant gliomas. Plexin-B2, an axon guidance receptor important for mediating neural progenitor cell migration during development, is upregulated in gliomas, but its function therein remains poorly understood. Combining bioinformatic analyses, immunoblotting and immunohistochemistry of patient samples, we demonstrate that Plexin-B2 is consistently upregulated in all types of human gliomas and that its expression levels correlate with glioma grade and poor survival. Activation of Plexin-B2 by Sema4C ligand in glioblastoma cells induced actin-based cytoskeletal dynamics and invasive migration in vitro. This proinvasive effect was associated with activation of the cell motility mediators RhoA and Rac1. Furthermore, costimulation of Plexin-B2 and the receptor tyrosine kinase Met led to synergistic Met phosphorylation. In intracranial glioblastoma transplants, Plexin-B2 knockdown hindered invasive growth and perivascular spreading, and resulted in decreased tumor vascularity. Our results demonstrate that Plexin-B2 promotes glioma invasion and vascularization, and they identify Plexin-B2 as a potential novel prognostic marker for glioma malignancy. Targeting the Plexin-B2 pathway may represent a novel therapeutic approach to curtail invasive growth of glioblastoma.     

Resveratrol supplementation confers neuroprotection in cortical brain tissue of nonhuman primates fed a high-fat/sucrose diet

Previous studies have shown positive effects of long-term resveratrol (RSV) supplementation in preventing pancreatic beta cell dysfunction, arterial stiffening and metabolic decline induced by high-fat/high-sugar (HFS) diet in nonhuman primates. Here, the analysis was extended to examine whether RSV may reduce dietary stress toxicity in the cerebral cortex of the same cohort of treated animals. Middle-aged male rhesus monkeys were fed for 2 years with HFS alone or combined with RSV, after which whole-genome microarray analysis of cerebral cortex tissue was carried out along with ELISA, immunofluorescence, and biochemical analyses to examine markers of vascular health and inflammation in the cerebral cortices. A number of genes and pathways that were differentially modulated in these dietary interventions indicated an exacerbation of neuroinflammation (e.g., oxidative stress markers, apoptosis, NF-κB activation) in HFS-fed animals and protection by RSV treatment. The decreased expression of mitochondrial aldehyde dehydrogenase 2, dysregulation in endothelial nitric oxide synthase, and reduced capillary density induced by HFS stress were rescued by RSV supplementation. Our results suggest that long-term RSV treatment confers neuroprotection against cerebral vascular dysfunction during nutrient stress.     

Orbital Branch of the Infraorbital Artery: Further Characterization of an Important Surgical Landmark

The orbital branch of the infraorbital artery, a key vascular structure that is not universally noted in orbital textbooks and atlases, is clinically significant, since injury to it can result in perioperative hemorrhage. We conducted a cadaver dissection to document its presence, measure its location, and evaluate it histopathologically. It was present in 8 of 9 orbits and was a mean distance of 16.6?mm (range 10–23) from the inferior orbital rim. In half of the specimens, there were 2 separate structures seen. Histopathology confirmed these structures to be neurovascular bundles.     

Retinal vascular biomarkers for early detection and monitoring of Alzheimer's disease

The earliest detectable change in Alzheimer''s disease (AD) is the buildup of amyloid plaque in the brain. Early detection of AD, prior to irreversible neurological damage, is important for the efficacy of current interventions as well as for the development of new treatments. Although PiB-PET imaging and CSF amyloid are the gold standards for early AD diagnosis, there are practical limitations for population screening. AD-related pathology occurs primarily in the brain, but some of the hallmarks of the disease have also been shown to occur in other tissues, including the retina, which is more accessible for imaging. Retinal vascular changes and degeneration have previously been reported in AD using optical coherence tomography and laser Doppler techniques. This report presents results from analysis of retinal photographs from AD and healthy control participants from the Australian Imaging, Biomarkers and Lifestyle (AIBL) Flagship Study of Ageing. This is the first study to investigate retinal blood vessel changes with respect to amyloid plaque burden in the brain. We demonstrate relationships between retinal vascular parameters, neocortical brain amyloid plaque burden and AD. A number of RVPs were found to be different in AD. Two of these RVPs, venular branching asymmetry factor and arteriolar length-to-diameter ratio, were also higher in healthy individuals with high plaque burden (P=0.01 and P=0.02 respectively, after false discovery rate adjustment). Retinal photographic analysis shows potential as an adjunct for early detection of AD or monitoring of AD-progression or response to treatments.