Cytokine regulation of E-selectin in rat CNS microvascular endothelial cells: differential response of CNS and non-CNS vessels

FUCA1: An Underexplored p53 Target Gene Linking Glycosylation and Cancer Progression

Cancer is a difficult-to-cure disease with high worldwide incidence and mortality, in large part due to drug resistance and disease relapse. Glycosylation, which is a common modification of cellular biomolecules, was discovered decades ago and has been of interest in cancer research due to its ability to influence cellular function and to promote carcinogenesis. A variety of glycosylation types and structures regulate the function of biomolecules and are potential targets for investigating and treating cancer. The link between glycosylation and carcinogenesis has been more recently revealed by the role of p53 in energy metabolism, including the p53 target gene alpha-L-fucosidase 1 (FUCA1), which plays an essential role in fucosylation. In this review, we summarize roles of glycan structures and glycosylation-related enzymes to cancer development. The interplay between glycosylation and tumor microenvironmental factors is also discussed, together with involvement of glycosylation in well-characterized cancer-promoting mechanisms, such as the epidermal growth factor receptor (EGFR), phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) and p53-mediated pathways. Glycan structures also modulate cell-matrix interactions, cell-cell adhesion as well as cell migration and settlement, dysfunction of which can contribute to cancer. Thus, further investigation of the mechanistic relationships among glycosylation, related enzymes and cancer progression may provide insights into potential novel cancer treatments.

Psychoneuroimmunology and immunopsychiatry of zebrafish

Despite the high prevalence of neural and immune disorders, their etiology and molecular mechanisms remain poorly understood. As the zebrafish (Danio rerio) is increasingly utilized as a powerful model organism in biomedical research, mounting evidence suggests these fish as a useful tool to study neural and immune mechanisms and their interplay. Here, we discuss zebrafish neuro-immune mechanisms and their pharmacological and genetic modulation, the effect of stress on cytokines, as well as relevant models of microbiota-brain interplay. As many human brain diseases are based on complex interplay between the neural and the immune system, here we discuss zebrafish models, as well as recent successes and challenges, in this rapidly expanding field. We particularly emphasize the growing utility of zebrafish models in translational immunopsychiatry research, as they improve our understanding of pathogenetic neuro-immune interactions, thereby fostering future discovery of potential therapeutic agents.

Activation of AMP-Activated Protein Kinase by Adenine Alleviates TNF-Alpha-Induced Inflammation in Human Umbilical Vein Endothelial Cells

The AMP-activated protein kinase (AMPK) signaling system plays a key role in cellular stress by repressing the inflammatory responses induced by the nuclear factor-kappa B (NF-κB) system. Previous studies suggest that the anti-inflammatory role of AMPK involves activation by adenine, but the mechanism that allows adenine to produce these effects has not yet been elucidated. In human umbilical vein endothelial cells (HUVECs), adenine was observed to induce the phosphorylation of AMPK in both a time- and dose-dependent manner as well as its downstream target acetyl Co-A carboxylase (ACC). Adenine also attenuated NF-κB targeting of gene expression in a dose-dependent manner and decreased monocyte adhesion to HUVECs following tumor necrosis factor (TNF-α) treatment. The short hairpin RNA (shRNA) against AMPK α1 in HUVECs attenuated the adenine-induced inhibition of NF-κB activation in response to TNF-α, thereby suggesting that the anti-inflammatory role of adenine is mediated by AMPK. Following the knockdown of adenosyl phosphoribosyl transferase (APRT) in HUVECs, adenine supplementation failed to induce the phosphorylation of AMPK and ACC. Similarly, the expression of a shRNA against APRT nullified the anti-inflammatory effects of adenine in HUVECs. These results suggested that the role of adenine as an AMPK activator is related to catabolism by APRT, which increases the cellular AMP levels to activate AMPK.

The engagement of selectins and their ligands in colorectal cancer liver metastases

The colonization of the liver by colorectal cancer (CRC) cells is a complicated process which includes many stages, until macrometastases occur. The entrapment of malignant cells within the hepatic sinusoids and their interactions with resident non-parenchymal cells are considered very important for the whole metastatic sequence. In the sinusoids, cell connection and signalling is mediated by multiple cell adhesion molecules, such as the selectins. The three members of the selectin family, E-, P- and L-selectin, in conjunction with sialylated Lewis ligands and CD44 variants, regulate colorectal cell communication and adhesion with platelets, leucocytes, sinusoidal endothelial cells and stellate cells. Their role in CRC liver metastases has been investigated in animal models and human tissue, in vivo and in vitro, in static and shear flow conditions, and their key-function in several molecular pathways has been displayed. Therefore, trials have already commenced aiming to exploit selectins and their ligands in the treatment of benign and malignant diseases. Multiple pharmacological agents have been developed that are being tested for potential therapeutic applications.

Enhancing expression of Nrf2-driven genes protects the blood brain barrier after brain injury

The integrity of the blood-brain barrier (BBB) is critical for normal brain function, and its compromise contributes to the pathophysiology of a number of CNS diseases and injuries. Using a rodent model of brain injury, the present study examines the pathophysiology of BBB disruption. Western blot and immunohistochemical analyses indicate that brain injury causes a loss of capillary endothelial cells and tight junction proteins, two critical components of the BBB. Activation of the transcription factor NF-E2-related factor-2 (Nrf2) by sulforaphane, a naturally occurring compound present in high levels in cruciferous vegetables, significantly increased the expression of endogenous cytoprotective genes in brain tissue and microvessels as indicated by real-time PCR analysis. Postinjury administration of sulforaphane reduced the loss of endothelial cell markers and tight junction proteins and preserved BBB function. These protective effects were dependent on the activity of Nrf2. Injured rats pretreated with decoy oligonucleotides containing the binding site of Nrf2, and mice lacking the nrf2 gene, did not benefit from sulforaphane administration. These findings indicate a potential therapeutic usefulness for Nrf2-activating molecules to improve the function of the neurovascular unit after injury.

Acutely increased cyclophilin a expression after brain injury: A role in blood-brain barrier function and tissue preservation

Blood-brain barrier (BBB) compromise is a significant pathologic event that manifests early following traumatic brain injury (TBI). Because many signaling cascades are initiated immediately after the traumatic event, we were interested in examining acute differential protein expression that may be involved in BBB function. At acute time points postinjury, altered protein expression may result from altered translation efficiency or turnover rate rather than from a genomic response. The application of tandem 2-D gel electrophoresis and mass spectrometry analysis is a powerful approach for directly screening differential protein expression following TBI. Using comparative 2-D gel analysis, we selected candidate protein spots with apparent altered expression and identified them by mass spectrometry. Cyclophilin A was selected for further analysis because it has been implicated in endothelial cell activation and inflammation, and studies have suggested cyclosporine A, an inhibitor of all cyclophilin isoforms, might be beneficial after TBI. We examined if altered expression of cyclophilin A in the brain vasculature might play a role in BBB function. We found significantly increased cyclophilin A levels in isolated brain microvessels 30 min following injury. Postinjury administration of cyclosporine A significantly attenuated BBB permeability measured 24 hr postinjury, suggesting cyclophilin activity after TBI may be detrimental. However, direct injection of purified recombinant cyclophilin A attenuated both BBB permeability and tissue damage in a stab wound model of injury. These findings suggest that increased expression of cyclophilin A may play a protective role after TBI, whereas other cyclophilin isoforms may be detrimental.

Activation of cerebral endothelium is required for mononuclear cell recruitment in a novel in vitro model of brain inflammation

Brain inflammation is a common event in the pathogenesis of several neurological diseases. It is unknown whether leukocyte/endothelium interactions are sufficient to promote homing of blood-borne cells into the brain compartment. The role of mononuclear cells and endothelium was analyzed in a new experimental model, the isolated guinea-pig brain maintained in vitro by arterial perfusion. This preparation allows one to investigate early steps of brain inflammation that are impracticable in vivo. We demonstrate by confocal microscopy analysis that in vitro co-perfusion of pro-inflammatory agents and pre-activated fluorescent mononuclear cells induced endothelial expression of selectins and intracellular adhesion molecule-1 in correspondence of arrested mononuclear cells, and correlates with a moderate increase in blood-brain barrier permeability. Separate perfusion of pro-inflammatory agents and mononuclear cells induced neither mononuclear cell adhesion nor adhesion molecule expression. We demonstrate that co-activation of mononuclear cells and cerebral endothelium is an essential requirement for cell arrest and adhesion in the early stages of experimental cerebral inflammation.

Differential expression of selectins by mouse brain capillary endothelial cells in vitro in response to distinct inflammatory stimuli

Increased lymphocyte trafficking across blood-brain barrier (BBB) is a prominent and early event in inflammatory and immune-mediated CNS diseases. The adhesion molecules that control the entry of leukocytes into the brain have not been fully elucidated. Although the role of ICAM-1 and VCAM-1 has been well documented, the expression and role of selectins is still a matter of controversy. In a mouse syngenic in vitro BBB model, highly relevant for examining immunological events, mouse brain capillary endothelial cells (MBCECs) do not express selectins. Treatment of MBCECs with LPS, induced E- and P-selectin expression, whereas TNF-alpha or IFN-gamma treatments did not. Finally, P-selectin but not E-selectin expression was induced in IL-1beta treated MBCECs. Thus, our study suggests that diverse inflammatory stimuli could differentially regulate selectin expression at the BBB.

Experimental approaches to lymphocyte migration in dermatology in vitro and in vivo

Lymphocyte trafficking through the dermal compartment is part of the physiological surveillance process of the adaptive immune system. On the other hand, persistent or recurrent lymphocyte infiltrates are hallmarks of both types of chronic inflammatory skin diseases, Th1-type such as psoriasis or Th2/allergic-type like atopic dermatitis. A better understanding of the mechanisms underlying lymphocyte movements is one of the key prerequisites for developing more effective therapies. In this review, we introduce a range of simple-to-sophisticated experimental in vitro and in vivo approaches to analyze lymphocyte migration. These methods start from static in vitro adhesion and chemotaxis assays, include dynamic endothelial flow chamber, intravital dual photon, and transcutaneous live-video microscopy, and finally encompass specific genetically deficient or engineered animal models. Discussing pros and cons of these assay systems hopefully generates both state-of-the-art knowledge about the factors involved in most common chronic skin diseases as well as an improved understanding of the limitations and chances of new biologic pharmaceuticals that are currently introduced into clinical practice.