Improved Barrier Integrity Research Articles

Sphingosine-1-Phosphate Regulates the Expression of Adherens Junction Protein E-Cadherin and Enhances Intestinal Epithelial Cell Barrier Function

The regulation of intestinal barrier permeability is important in the maintenance of normal intestinal physiology. Sphingosine-1-phosphate (S1P) has been shown to play a pivotal role in enhancing barrier function in several non-intestinal tissues. The current study determined whether S1P regulated function of the intestinal epithelial barrier by altering expression of E-cadherin, an important protein in adherens junctions. Studies were performed upon cultured differentiated IECs (IEC-Cdx2L1 line) using standard techniques. S1P treatment significantly increased levels of E-cadherin protein and mRNA in intestinal epithelial cells (IECs) and also led to E-cadherin localizing strongly to the cell-cell border. S1P also improved the barrier function as indicated by a decrease in 14C-mannitol paracellular permeability and an increase in transepithelial electrical resistance (TEER) in vitro. These results indicate that S1P increases levels of E-cadherin, both in cellular amounts and at the cell-cell junctions, and leads to improved barrier integrity in cultured intestinal epithelial cells.

CD40 activation is angioproliferative in pulmonary microvascular endothelial cells

IntroductionEndothelial CD40 is important during inflammation as an angiogenic stimulus. We tested whether CD40 expression in PMVEC is associated with angioproliferative potential.MethodsWestern analysis for CD40 expression was performed. Growth curves, barrier measurements, and scratch‐wound assays were carried out using an ECIS apparatus (Applied Biophysics) and a digital image system composed of an inverted microscope.ResultsBasal CD40 expression was high in PMVEC, whereas expression was absent in rat pulmonary arterial‐derived EC (PAEC). CD40 expression could be up‐regulated in PAEC following over‐expression of NAP‐1, an endothelial progenitor cell‐associated protein. Exposure of PMVEC to sCD40L (1 μg/mL) for 1 ‐ 48 hours increased proliferation and improved barrier integrity. Exposure to sCD40L also produced an accelerated PMVEC migration response with decreased wound closure times. These effects were inhibited by pre‐treatment with anti‐CD40 antibodies.ConclusionsOur data indicate activation of PMVEC‐expressed CD40 results in angioproliferative responses. These responses may be inherent to cell phenotypes expressing NAP‐1. Identification of PMVEC expressing CD40 in situ may localize pulmonary resident endothelial progenitor cells. Support: Parker B. Francis Foundation and AHA (0765421B) to T.M.M.

Successful management of mild atopic dermatitis in adults with probiotics and emollients

AbstractAtopic dermatitis is characterized by impaired skin and mucous membrane barrier function. Measures improving barrier integrity decrease the influence of environmental factors that might exacerbate inflammation. Ten adult patients with mild-to-moderate atopic dermatitis consumed for three months fermented with potent antioxidative probiotic, L. fermentum ME-3 (DSM 14241) goat milk 200 mg/day. A control group consisted of six patients, not supplemented by probiotic. All patients used emollients regularly. Skin iron levels, glutathione redox ratios (GSSG/GSH), diene conjugate (DC) amounts, blood glutathione status, oxidized low-density lipoprotein (oxLDL), and total antioxidativity was measured at the baseline and after three months. A significant decrease in skin iron levels, DC amounts, and glutathione redox ratio occurred in the probiotic-supplemented group compared to the control group (P < 0.05 for all indices). In the same group, blood levels of oxLDL decreased (p < 0.05), and GSH levels increased (P < 0.001) with concomitant improvement in the GSSG/GSH ratio. Blood antioxidativity markers also showed an improvement. The results of our study demonstrate that regular use of probiotics with antioxidative properties coupled with the use of lipid-containing emollients considerably decreases inflammation and concomitant oxidative stress in adult patients with mild-to-moderate atopic dermatitis. This effect was observed both in the skin and in the blood.

Induction of Vascular Permeability by the Sphingosine-1-Phosphate Receptor–2 (S1P2R) and its Downstream Effectors ROCK and PTEN

S1P acts via the S1PR family of G protein-coupled receptors to regulate a variety of physiological responses. Whereas S1P1R activates G(i)- and PI-3-kinase-dependent signals to inhibit vascular permeability, the related S1P2R inhibits the PI-3-kinase pathway by coupling to the Rho-dependent activation of the PTEN phosphatase. However, cellular consequences of S1P2R signaling in the vascular cells are not well understood. Selective signaling of the S1P2R was achieved by adenoviral-mediated expression in endothelial cells. Secondly, endogenously expressed S1P2R was blocked by the specific pharmacological antagonist JTE013. Activation of S1P2R in endothelial cells resulted in Rho-ROCK- and PTEN-dependent disruption of adherens junctions, stimulation of stress fibers, and increased paracellular permeability. JTE013 treatment of naive endothelial cells potentiated the S1P1R-dependent effects such as formation of cortical actin, blockade of stress fibers, stimulation of adherens junction assembly, and improved barrier integrity. This observation was extended to the in vivo model of vascular permeability in the rat lung: the S1P2R antagonist JTE013 significantly inhibited H2O2-induced permeability in the rat lung perfused model. S1P2R activation in endothelial cells increases vascular permeability. The balance of S1P1 and S1P2 receptors in the endothelium may determine the regulation of vascular permeability by S1P.

Correlation between barrier integrity and TDDB performance of copper porous low-k interconnects

Time Dependent Dielectric Breakdown performance of a fully dense and a porous metal diffusion barrier was evaluated on a porous methyl-silsesquioxane low-k material. By changing the barrier deposition process, the barrier integrity on damascene sidewalls can be improved and sealing of the low-k sidewalls is achieved with a barrier thickness value of about 8 nm. A clear correlation between barrier integrity and interconnect reliability was evidenced and an improved barrier integrity leads to increased lifetimes.

Ti/TiN Barrier Improvement for VLSI Metallization

ABSTRACTIn this study deposition temperature and post-deposition treatments, such as vacuum break, furnace anneal and RTA, were coupled together to improve Ti/TiN barrier properties. Raising substrate temperature during deposition resulted in lower sheet resistance and stresses, but worse Sheet resistance (Rs) uniformity, suggesting larger-grain growth and non-uniform silicidation. The RTA treatment appeared to be the most effective one to improve barrier integrity due to high temperature densification and oxygen rich along grain boundaries. To include contact geometry effect, the barrier processes were incorporated with hot Al on the contact level of 0.6µm SRAM. After alloying at 430°C for 45 min, the yields turned out to be similar, although the RTA treatment resulted in lower P+ contact resistance, implying more complete activation, silicidation and less dopant segregation. The result suggests that it is feasible to deposit Ti/TiN insitu with hot Al process to enhance throughput. The yield result after a second alloying set at 500°C for 30 min showed that RTA treated Ti/TiN was the only one to survive.