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Cadmium (Cd) is a highly toxic environmental pollutant released from the smelting and refining of metals and cigarette smoking. Oral exposure to cadmium may result in adverse effects on a number of tissues, including the central nervous system (CNS). In fact, its toxicity has been related to neurological disorders, as well as neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Under normal conditions, Cd barely reaches the brain in adults because of the presence of the blood-brain barrier (BBB); however, it has been demonstrated that Cd-dependent BBB alteration contributes to pathogenesis of neurodegeneration. However, the mechanism underlying Cd-dependent BBB alteration remain obscure. Here, we investigated the signaling pathway of Cd-induced tight junction (TJ), F-actin, and vimentin protein disassembly in a rat brain endothelial cell line (RBE4). RBE4 cells treated with 10 μM cadmium chloride (CdCl 2 ) showed a dose- and time-dependent significant increase in reactive oxygen species (ROS) production. This phenomenon was coincident with the alteration of the TJ zonula occludens-1 (ZO-1), F-actin, and vimentin proteins. The Cd-dependent ROS increase elicited the upregulation of GRP78 expression levels, a chaperone involved in endoplasmic reticulum (ER) stress that induces caspase-3 activation. Further signal profiling by the pannexin-1 (PANX1) specific inhibitor 10 Panx revealed a PANX1-independent increase in ATP spillage in Cd-treated endothelial cells. Our results point out that a ROS-dependent ER stress-mediated signaling pathway involving caspase-3 activation and ATP release is behind the BBB morphological alterations induced by Cd.

With the recent advances in medicine, human life expectancy is increasing; however, the extra years of life are not necessarily spent in good health or free from disability, resulting in a significantly higher incidence of age-associated pathologies. Among these disorders, neurodegenerative diseases have a significant impact. To this end, the presence of the protective blood–brain barrier (BBB) represents a formidable obstacle to the delivery of therapeutics. Thus, this makes it imperative to define strategies to bypass the BBB in order to successfully target the brain with the appropriate drugs. It has been demonstrated that targeting the BBB by ultrasound (US) can transiently make this anatomical barrier permeable and in so doing, allow the delivery of therapeutics. Thus, our aim was to carry out an in depth in vitro molecular and morphological study on the effects of US treatment on the BBB. The rat brain endothelial (RBE4) cell line was challenged with exposure to 12 MHz diagnostic US treatment for 10, 20, and 30 min. Cell viability assays, Western blotting analysis on the endoplasmic reticulum (ER), and oxidative stress marker evaluation were then performed, along with cytological and immunofluorescence staining, in order to evaluate the effects of US on the intercellular spaces and tight junction distribution of the brain endothelial cells. We observed that the US treatment exerted no toxic effects on either RBE4 cell viability or the upregulation/dislocation of the ER and oxidative stress marker (GRP78 and cytochrome C, respectively). Further, we observed that the application of US induced an increase in the intercellular spaces, as shown by Papanicolaou staining, mainly due to the altered distribution of the tight junction protein zonula occludens-1 (ZO-1). This latter US-dependent effect was transient and disappeared 20 min after the removal of the stimulus. In conclusion, our results show that US induces a transient alteration of the BBB, without altering the intracellular signaling pathways such as the ER and oxidative stress that could potentially be toxic for endothelial cells. These results suggested that US treatment could represent a potential strategy for improving drug delivery to the brain. [ABSTRACT FROM AUTHOR]

The article focuses on studying the blood-brain barrier (BBB) and the crucial role of astrocytes in its formation and function, highlighting their influence on the expression and correct distribution of tight junction proteins like claudin 5 in brain endothelial cells.

C Cadmium is a toxic heavy metal known as environmental pollutant world-wide distributed. Its toxicity, predominantly due to its long half-life of 15-20 years, affects many organs and tissues including kidney, lung, liver, heart, bone, muscles and the central nervous system (CNS) as well [1]. Our research group previously demonstrated that cadmium is able to alter the blood-brain barrier by modifying the tight junction sealing morphology and to induce oxidative stress, thus leading to neuronal degeneration mainly by oxidative stress [2]. Among the cellular population of the CNS, glial cells own a pivotal role in maintaining the physiological brain homeostasis and their alteration has been demonstrated to indirectly affect neurons [3]. The aim of the present research is to evaluate cadmium toxicity in two glial cell lines (astrocyte DITNC1 and microglia BV-2), at different time and increasing concentration of metal exposure. Cadmium increasing concentrations (0.1-100 µM) were administered in starvation medium for 8, 24 and 48 hours. Cell viability assay, western blotting analysis, and immunofluorescent staining were employed in order to evaluate the molecular and morphological alterations induced by the heavy metal. Our results clearly demonstrated that Cd is able to affect the cell viability even at the lowest concentrations and in a time-dependent manner, by altering the oxidative balance (ROS production, cytochrome C expression) and inducing an endoplasmic reticulum stress (GRP78 upregulation). Moreover, Cd is able to induce glial morphological alterations as well as an overexpression of activation glial markers, such as GFAP, S100ß, CD86, and Iba1. In conclusion, the data obtained clearly demonstrated that Cd toxicity occurs even at low doses and for very short exposure times Further experiments should be performed in order to evaluate the mechanisms underlying the Cd-dependent activation of glial cells and how this, in turn, induces a neuronal homeostasis alteration. [ABSTRACT FROM AUTHOR]

• The intestinal epithelial barrier is critical to maintain health. • Aging affects all the components of the intestinal barrier. • The intestinal barrier is a potential strategic target to improve health during aging. The intestinal epithelial barrier protects the mucosa of the gastrointestinal (GI)-tract and plays a key role in maintaining the host homeostasis. It encompasses several elements that include the intestinal epithelium and biochemical and immunological products, such as the mucus layer, antimicrobial peptides (AMPs) and secretory immunologlobulin A (sIgA). These components are interlinked with the large microbial community inhabiting the gut to form a highly sophisticated biological system that plays an important role on many aspects of human health both locally and systemically. Like any other organ and tissue, the intestinal epithelial barrier is affected by the ageing process. New insights have surfaced showing that critical functions, including intestinal stem cell regeneration and regulation of the intestinal crypt homeostasis, barrier integrity, production of regulatory cytokines, and epithelial innate immunity to pathogenic antigens change across life. Here we review the age-associated changes of the various components of the intestinal epithelial barrier and we highlight the necessity to elucidate further the mechanisms underlying these changes. Expanding our knowledge in this area is a goal of high medical relevance and it will help to define intervention strategies to ameliorate the quality of life of the ever-expanding elderly population. [ABSTRACT FROM AUTHOR]