Glucagon-like peptide-1(1-37) inhibits chemokine-induced migration of human CD4-positive lymphocytes.

The present study examined the effect of GLP-1(1-37) on chemokine-induced CD4-positive lymphocyte migration as an early and critical step in atherogenesis. Pretreatment with GLP-1(1-37) reduced the SDF-induced migration of isolated human CD4-positive lymphocytes in a concentration-dependent manner. Similar effects were seen when RANTES was used as a chemokine. GLP-1(1-37)'s effect on CD4-positive lymphocyte migration was mediated through an early inhibition of chemokine-induced PI-3 kinase activity. Downstream, GLP-1(1-37) inhibited SDF-induced phosphorylation of MLC and cofilin and limited f-actin formation as well as ICAM3 translocation. Furthermore, exendin-4 inhibited SDF-induced migration of CD4-positive lymphocytes similarly to GLP-1(1-37), and transfection of these cells with GLP-1 receptor siRNA abolished GLP-1(1-37)'s action on chemokine-induced ICAM3 translocation, suggesting an effect mediated via the GLP-1 receptor. Thus, GLP-1(1-37) inhibits chemokine-induced CD4-positive lymphocyte migration by inhibition of the PI3-kinase pathway and via the GLP-1 receptor. This effect provides a potential novel mechanism for how GLP-1(1-37) may modulate vascular disease.

LXR activation inhibits chemokine-induced CD4-positive lymphocyte migration.

Migration of CD4-positive lymphocytes into the vessel wall is a critical step in atherogenesis. Recent data suggest that CD4-positive lymphocytes express the nuclear transcription factors Liver-X-Receptor (LXR) alpha and beta with an effect of LXR activators on TH1-cytokine release from these cells. However, the role of LXR in lymphocyte migration remains currently unexplored. Therefore, the present study investigated whether LXR activation might modulate chemokine-induced migration of these cells. Stimulation of CD4-positive lymphocytes with SDF-1 leads to a 2.5 +/- 0.8-fold increase in cell migration (P < 0.05; n = 12). Pretreatment of cells with the LXR activator T0901317 reduces this effect in a concentration-dependent manner to a maximal 0.9 +/- 0.4-fold induction at 1 micromol/L T0901317 (P < 0.05 compared to SDF-1-treated cells; n = 12). Similar results were obtained with the LXR activator GW3965. The effect of LXR activators on CD4-positive lymphocyte migration was mediated through an early inhibition of chemokine-induced PI-3 kinase activity as determined by PI-3 kinase activity assays. Downstream, T0901317 inhibited activation of the small GTPase Rac and phosphorylation of the myosin light chain (MLC). Moreover, LXR activator treatment reduced f-actin formation as well as ICAM3 translocation to the uropod of the cell, thus interfering with two important steps in T cell migration. Transfection of CD4-positive lymphocytes with LXRalpha/beta siRNA abolished T0901317 inhibitory effect on MLC phosphorylation and ICAM3 translocation. LXR activation by T0901317 or GW3965 inhibits chemokine-induced migration of CD4-positive lymphocytes. Given the crucial importance of chemokine-induced T cell migration in early atherogenesis, LXR activators may be promising tools to modulate this effect.

Epstein-barr virus-induced gene-3 is expressed in human atheroma plaques.

Atherosclerosis is characterized by a complex immune response in the vessel wall, involving both inflammation and autoimmune processes. Epstein-Barr virus-induced gene 3 (Ebi3) is a member of the interleukin (IL)-12 heterodimeric cytokine family, which has important immunomodulatory functions. To date, little is known about the role of Ebi3 in vascular disease. We examined the expression of Ebi3 in human atheromatous lesions and analyzed its transcriptional regulation in vascular cells. The in situ expression of Ebi3 in human endarterectomy specimens was analyzed by immunohistochemistry. In these lesions, smooth muscle cells expressed Ebi3 as well as the IL-27alpha/p28 and IL-12alpha/p35 subunits. Primary aortic smooth muscle cells up-regulated Ebi3 in response to proinflammatory stimuli like tumor necrosis factor-alpha and interferon-gamma. Interestingly, pretreatment of these cells with the peroxisome proliferator-activated receptor-gamma agonist rosiglitazone strongly reduced Ebi3 induction. Chromatin immunoprecipitation experiments revealed that this inhibition is due to interference with p65/RelA recruitment to the Ebi3 promoter. Our data support a possible role of Ebi3 in atherogenesis either as homodimer or as IL-27/IL-35 heterodimer, and suggest that Ebi3 could be an interesting target for therapeutic manipulation in atherosclerosis.

Characterization and Quantitation of Steryl Glycosides in Solanum melongena.

Glycosylated plant sterols or steryl glycosides (SGs) are a small group of glycolipids occurring ubiquitously in plants. In contrast to free sterols, they are insufficiently characterized concerning structural variety, quantity, and biological function. In particular, the type of sugar usually attached to the C-3 hydroxy function of the respective sterol is poorly studied. Eggplants ( Solanum melongena) are rich in phytochemicals including SGs. In the present work, the unique glycosylation pattern was investigated by a highly selective LC-MS/MS method that allowed quantitation of the glucosides and galactosides of the most common sterols: cholesterol, ß-sitosterol, campesterol, and stigmasterol. The quantitatively most important structure was ß-sitosteryl ß-d-glucopyranoside, with 54.5 mg/kg fresh weight of total fruit (365.3 mg/kg dry weight) followed by stigmasteryl ß-d-glucopyranoside and campesteryl ß-d-glucopyranoside. Analyses were performed in different tissues of eggplants (i.e., exocarp and outer mesocarp vs the remaining inner part). Steryl galactosides were determined in eggplants for the first time at significantly lower concentrations by a factor of 100. Furthermore, the rare SG ß-sitosteryl ß-d-cellobioside (3-ß-sitosteryl ß-d-glucopyranosyl-(1→4)-ß-d-glucopyranoside) was detected in eggplants for the first time. Finally, UV irradiation induced the formation of the vitamin D glucosides 7-dehydrocholesteryl ß-d-glucopyranoside and cholecalciferyl ß-d-glucopyranoside at very low levels.

Lycopene inhibits the isomerization of ß-carotene during quenching of singlet oxygen and free radicals.

The present study aimed to investigate the influence of singlet oxygen and radical species on the isomerization of carotenoids. On the one hand, lycopene and ß-carotene standards were incubated with 1,4-dimethylnaphthalene-1,4-endoperoxide that produced singlet oxygen in situ. (13Z)- and (15Z)-ß-carotene were preferentially generated at low concentrations of singlet oxygen, while high concentrations resulted in formation of (9Z)-ß-carotene. The addition of different concentrations of lycopene led to the same isomerization progress of ß-carotene, but resulted in a decreased formation of (9Z)-ß-carotene and retarded degradation of (all-E)-ß-carotene. On the other hand, isomerization of ß-carotene and lycopene was induced by ABTS-radicals, too. As expected from the literature, chemical quenching was observed especially for lycopene, while physical quenching was preferred for ß-carotene. Mixtures of ß-carotene and lycopene resulted in a different isomerization progress compared to the separate ß-carotene model. As long as lycopene was present, almost no isomerization of ß-carotene was triggered; after that, strong formation of (13Z)-, (9Z)-, and (15Z)-ß-carotene was initiated. In summary, lycopene protected ß-carotene against isomerization during reactions with singlet oxygen and radicals. These findings can explain the pattern of carotenoid isomers analyzed in fruits and vegetables, where lycopene containing samples showed higher (all-E)/(9Z)-ß-carotene ratios, and also in in vivo samples such as human blood plasma.

Clusters for alkyne-azide click reactions.

The clusters Ti(6)O(4)(OPr)(8)(OOC(CH(2))(2)C[triple bond]CH)(8) and [Zr(6)O(4)(OH)(4)(OOC(CH(2))(3)C[triple bond]CH)(12)](2) with acetylenic carboxylate ligands were prepared and structurally characterized in solution and in the crystalline state. Model reactions showed that they are suitable candidates for the formation of cluster-based inorganic-organic hybrid materials by alkyne-azide click reactions.

Resistin: a newly identified chemokine for human CD4-positive lymphocytes.

AIMS: Increased levels of resistin, a peptide secreted by adipocytes and inflammatory cells, circulate in patients with insulin resistance and early type 2 diabetes, a high-risk population for the development of a diffuse and extensive pattern of arteriosclerosis. Recent data suggest that resistin may activate vascular cells such as smooth muscle cells and endothelial cells, but hitherto nothing is known about the role of resistin in CD4-positive lymphocytes. Therefore, the present study examined the effect of resistin on CD4-positive lymphocyte migration, an important process in early atherogenesis. METHODS AND RESULTS: Resistin stimulated CD4-positive cell chemotaxis in a concentration-dependent manner with a maximal induction of 2.25 +/- 0.54 at 100 ng/mL (P < 0.05, n = 7). This process involves pertussis toxin-sensitive G-proteins as well as activation of Src- and phosphoinositide 3-kinase (PI 3-K). Biochemical analysis showed that resistin induces phosphorylation of Src and PI 3-K activation in human CD4-positive cells. In addition, resistin activates RhoA, Rac-1, and Cdc42 in these cells as shown by affinity precipitation experiments. Finally, resistin-induced phosphorylation of myosin light chain was inhibited by Src short interference RNA transfection, underscoring the importance of the upstream signalling molecule Src in resistin-induced migration. CONCLUSION: These data support an active role of resistin in CD4-positive lymphocyte chemotaxis and elucidate molecular mechanisms in resistin-induced cell migration.

Telmisartan inhibits CD4-positive lymphocyte migration independent of the angiotensin type 1 receptor via peroxisome proliferator-activated receptor-gamma.

Migration of CD4-positive lymphocytes into the vessel wall represents an important step in early atherogenesis. Telmisartan is an angiotensin type 1 receptor (AT1R) blocker with peroxisome proliferator-activated receptor (PPAR)-gamma-activating properties. The present study examined the effect of telmisartan on CD4-positive cell migration and the role of PPARgamma in this context. CD4-positive lymphocytes express both the AT1R and PPARgamma. Stimulation of CD4-positive lymphocytes with stromal cell-derived factor (SDF)-1 leads to a 4.1+/-3.1-fold increase in cell migration. Pretreatment of cells with telmisartan reduces this effect in a concentration-dependent manner to a maximal 1.6+/-0.7-fold induction at 10 mumol/L of telmisartan (P<0.01 compared with SDF-1-treated cells; n=22). Three different PPARgamma activators, rosiglitazone, pioglitazone, and GW1929, had similar effects, whereas eprosartan, a non-PPARgamma-activating AT1R blocker, did not affect chemokine-induced lymphocyte migration. Telmisartan's effect on CD4-positive lymphocyte migration was mediated through an early inhibition of chemokine-induced phosphatidylinositol 3-kinase activity. Downstream, telmisartan inhibited F-actin formation, as well as intercellular adhesion molecule-3 translocation. Transfection of CD4-positive lymphocytes with PPARgamma small interfering RNA abolished telmisartan's effect on migration, whereas blockade of the AT1R had no such effect. Telmisartan inhibits chemokine-induced CD4-positive cell migration independent of the AT1R via PPARgamma. These data provide a novel mechanism to explain how telmisartan modulates lymphocyte activation by its PPARgamma-activating properties.