Connexin43 gap junction protein is expressed in astrocytes and the vascular endothelium in the central nervous system. It is upregulated following central nervous system injury and is recognized as playing an important role in modulating the extent of damage. Studies that have transiently blocked connexin43 in spinal cord injury and central nervous system epileptic models have reported neuronal rescue. The purpose of this study was to investigate neuronal rescue following retinal ischaemia-reperfusion by transiently blocking connexin43 activity using a connexin43 mimetic peptide. A further aim was to evaluate the effect of transiently blocking connexin43 on vascular permeability as this is known to increase following central nervous system ischaemia. Adult male Wistar rats were exposed to 60 min of retinal ischaemia. Treatment groups consisted of no treatment, connexin43 mimetic peptide and scrambled peptide. Retinas were then evaluated at 1-2, 4, 8 and 24 h, and 7 and 21 days post-ischaemia. Evans blue dye leak from retinal blood vessels was used to assess vascular leakage. Blood vessel integrity was examined using isolectin-B4 labelling. Connexin43 levels and astrocyte activation (glial fibrillary acidic protein) were assessed using immunohistochemistry and western blot analysis. Retinal whole mounts and retinal ganglion cell counts were used to quantify neurodegeneration. An in vitro cell culture model of endothelial cell ischaemia was used to assess the effect of connexin43 mimetic peptide on endothelial cell survival and connexin43 hemichannel opening using propidium iodide dye uptake. We found that retinal ischaemia-reperfusion induced significant vascular leakage and disruption at 1-2, 4 and 24 h following injury with a peak at 4 h. Connexin43 immunoreactivity was significantly increased at 1-2, 4, 8 and 24 h post ischaemia-reperfusion injury co-localizing with activated astrocytes, Muller cells and vascular endothelial cells. Connexin43 mimetic peptide significantly reduced dye leak at 4 and 24 h. In vitro studies on endothelial cells demonstrate that endothelial cell death following hypoxia can be mediated directly by opening of connexin43 hemichannels in endothelial cells. Blocking connexin43 mediated vascular leakage using a connexin43 mimetic peptide led to increased retinal ganglion cell survival at 7 and 21 days to levels of uninjured retinas. Treatment with scrambled peptide did not result in retinal ganglion cell rescue. Pharmacological targeting of connexin43 gap junction protein by transiently blocking gap junction hemichannels following injury provides new opportunities for treatment of central nervous system ischaemia.

BackgroundLeukocyte adhesion to the vascular endothelium and subsequent transendothelial migration play essential roles in the pathogenesis of cardiovascular diseases such as atherosclerosis. The leukocyte adhesion is mediated by localized activation of the endothelium through the action of inflammatory cytokines. The exact proinflammatory factors, however, that activate the endothelium and their cellular sources remain incompletely defined.Methods and ResultsUsing bone marrow-derived mast cells from wild-type, Tnf−/−, Ifng−/−, Il6−/− mice, we demonstrated that all three of these pro-inflammatory cytokines from mast cells induced the expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), P-selectin, and E-selectin in murine heart endothelial cells (MHEC) at both mRNA and protein levels. Compared with TNF-α and IL6, IFN-γ appeared weaker in the induction of the mRNA levels, but at protein levels, both IL6 and IFN-γ were weaker inducers than TNF-α. Under physiological shear flow conditions, mast cell-derived TNF-α and IL6 were more potent than IFN-γ in activating MHEC and in promoting neutrophil adhesion. Similar observations were made when neutrophils or macrophages were used. Neutrophils and macrophages produced the same sets of pro-inflammatory cytokines as did mast cells to induce MHEC adhesion molecule expression, with the exception that macrophage-derived IFN-γ showed negligible effect in inducing VCAM-1 expression in MHEC.ConclusionMast cells, neutrophils, and macrophages release pro-inflammatory cytokines such as TNF-α, IFN-γ, and IL6 that induce expression of adhesion molecules in endothelium and recruit of leukocytes, which is essential to the pathogenesis of vascular inflammatory diseases.

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The cis benzopyran compound tonabersat (SB-220453) has previously been reported to inhibit connexin26 expression in the brain by attenuating the p38-mitogen-activated protein kinase pathway. We show here that tonabersat directly inhibits connexin43 hemichannel opening. Connexin43 hemichannels have been called "pathological pores" based upon their role in secondary lesion spread, edema, inflammation, and neuronal loss following central nervous system injuries, as well as in chronic inflammatory disease. Both connexin43 hemichannels and pannexin channels released adenosine triphosphate (ATP) during ischemia in an in vitro ischemia model, but only connexin43 hemichannels contributed to ATP release during reperfusion. Tonabersat inhibited connexin43 hemichannel-mediated ATP release during both ischemia and reperfusion phases, with direct channel block confirmed using electrophysiology. Tonabersat also reduced connexin43 gap junction coupling in vitro, but only at higher concentrations, with junctional plaques internalized and degraded via the lysosomal pathway. Systemic delivery of tonabersat in a rat bright-light retinal damage model (a model for dry age-related macular degeneration) resulted in significantly improved functional outcomes assessed using electroretinography. Tonabersat also prevented thinning of the retina, especially the outer nuclear layer and choroid, assessed using optical coherence tomography. We conclude that tonabersat, already given orally to over 1000 humans in clinical trials (as a potential treatment for, and prophylactic treatment of, migraine because it was thought to inhibit cortical spreading depression), is a connexin hemichannel inhibitor and may have the potential to be a novel treatment of central nervous system injury and chronic neuroinflammatory disease.

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BackgroundGestational diabetes mellitus (GDM) is common all over the world. GDM women are with inflammatory and metabolisms abnormalities. However, few studies have focused on the association of IL-65–72C/G and TNF-α-857C/T single nucleotide polymorphisms (SNPs), inflammatory biomarkers, and metabolic indexes in women with GDM, especially in the Inner Mongolia population. The aim of this study was to investigate the associations of IL-65–72C/G and TNF-α-857C/T SNPs, and inflammation and metabolic biomarkers in women with GDM pregnancies.Material/MethodsBlood samples and placentas from 140 women with GDM and 140 women with healthy pregnancies were collected. Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) and MassARRAY-IPLEX were performed to analyze IL-65–72C/G and TNF-α-857C/T SNPs. Enzyme linked immunosorbent assay (ELISA) was performed to analyze inflammatory biomarkers and adipokines.ResultsDistribution frequency of TNF-α-857CT (OR=3.316, 95% CI=1.092–8.304, p=0.025) in women with GDM pregnancies were obviously higher than that in women with healthy pregnancies. Women with GDM were of older maternal age, had higher BMI, were more nulliparous, and had T2DM and GDM history, compared to women with healthy pregnancies (p<0.05). Inflammatory biomarkers in serum (hs-CRP, IL-6, IL-8, IL-6/IL-10 ratio) and placental (NF-κB, IL-6, IL-8, IL-6/IL-10 ratio, IL-1β, TNF-α) were significantly different (p<0.05) between women with GDM and women with healthy pregnancies. Differences were found for serum FBG, FINS, HOMA-IR, and HOMA-β, and placental IRS-1, IRS-2, leptin, adiponectin, visfatin, RBP-4, chemerin, nesfatin-1, FATP-4, EL, LPL, FABP-1, FABP-3, FABP-4, and FABP-5.ConclusionsTNF-α-857C/T SNP, hs-CRP, IL-6, IL-8, and IL-6/IL-10 were associated with GDM in women from Inner Mongolia, as was serious inflammation and disordered lipid and glucose metabolisms.

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