1,4-Dihydroxyxanthone modulates the adhesive property of endothelial cells by inhibiting intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin

ICAM-1 regulates macrophage polarization by suppressing MCP-1 expression via miR-124 upregulation

Intercellular adhesion molecule-1 is the adhesion molecule mediating leukocyte firm adhesion to endothelial cells, plays a critical role in subsequent leukocyte transmigration. ICAM-1 is also expressed in other cells including macrophages; however, the role of this adhesion molecule in mediating macrophage functions remains enigmatic. We report that ICAM-1 regulates macrophage polarization by positively modulating miR-124 expression. We found higher expression levels of monocyte chemotactic protein-1 in lungs of mice lacking ICAM-1. Consistent with this result, siRNA mediated depletion of ICAM-1 in macrophage resulted in increased expression levels of MCP-1. Moreover, ICAM-1 controlled miR-124 expression and downregulated MCP-1 mRNA and protein expression by binding of miR-124 to MCP-1 3' untranslated region. ICAM-1 also induced the transcription factor Sp1 expression, which is important for miR-124 expressing in macrophages. Furthermore, ICAM-1 depletion led to M1 macrophage polarization, in contrast, miR-124 mimics promoted M2 macrophage polarization. Exogenous administration of miR-124 mimics into the lungs prevented lipopolysaccharide-induced myeloperoxidase activity in vivo, suggesting that miR-124 is important for dampening acute lung injury. These results collectively show that adhesion molecule ICAM-1 downregulates MCP-1 expression by controlling Sp1 mediated miR-124 levels, which in turn regulate M2 macrophage polarization. Targeting ICAM-1 and downstream miR-124 may present a new therapeutic strategy for acute lung injury.

A novel anti-inflammatory natural product from Sphaeranthus indicus inhibits expression of VCAM1 and ICAM1, and slows atherosclerosis progression independent of lipid changes

A large body of evidence suggests that atherosclerosis is an inflammatory disease, in which cytokines and growth factors play a major role in disease progression. The methanolic extracts of Sphaeranthus indicus as well as its active ingredient, 7-hydroxy frullanoide (7-HF), are shown to suppress LPS-induced cytokine production from mononuclear cells, and inhibit the expression of VCAM1, ICAM1 and E-selectin by TNF-α- stimulated HUVECs in a concentration-dependent manner. We tested the hypothesis that the inhibition of cytokines and adhesion molecules should attenuate the progression of atherosclerosis, independent of changes in the lipid profile. Studies were carried out in two animal models: a high fat-fed LDLr^-/- mouse and a high fat-fed hyperlipidemic hamster. Methanolic extract of S. indicus was dosed to hyperlipidemic LDLr^-/- at 100 and 300 mg (equivalent to 20 and 60 mg 7-HF)/kg body weight/ day for 8 weeks, and plasma lipids as well as aortic lesion area were quantitated. Hyperlipidemic hamsters were treated with one dose of 200 mg/kg/day. S. indicus extract treatment did not alter the lipid profile in both animal models, but reduced aortic lesion area in LDLr^-/- mice and hyperlipidemic hamsters by 22 % and 45 %, respectively. Fenofibrate, included as a reference agent, decreased aortic lesions by 26 % in LDLr ^-/- mice and 84 % in hyperlipidemic hamsters, respectively, which was driven by massive reductions in proatherogenic lipoproteins. The lipid-independent anti-atherosclerotic activity of S. indicus was associated with the reductions in the circulating levels of MCP-1, TNF-α, and IL-6 via phosphorylation and degradation of IkB-α that prevents translocation of NF-kB in the nucleus to induce proinflammatory cytokines. Our findings demonstrate that anti-inflammatory agents that lower pro-inflammatory proteins inhibit the progression of atherosclerosis. The methanolic extract of S. inducus, currently being used to treat psoriasis, offer promise to benefit individuals who have high circulating pro-inflammatory cytokines, and predisposed to coronary artery disease.

Dimethylarginine dimethylaminohydrolase regulation: a novel therapeutic target in cardiovascular disease

Asymmetric dimethylarginine (ADMA), an endogenous methylated form of the amino acid L-arginine, inhibits the activity of the enzyme endothelial nitric oxide synthase, with consequent reduced synthesis of nitric oxide. ADMA is metabolised to L-citrulline and dimethylamine by the enzyme dimethylarginine dimethylaminohydrolase (DDAH). The modulation of DDAH activity and expression plays a pivotal role in regulating intracellular ADMA concentrations, with important effects on vascular homeostasis. For example, impairment in DDAH activity, resulting in elevated ADMA concentrations and reduced nitric oxide synthesis, can promote the onset and progression of atherosclerosis in experimental models. This review discusses the current role of ADMA and DDAH in vascular health and disease, the techniques used to assess DDAH activity and expression, and the results of recent studies on pharmacological and biological agents modulating DDAH activity and expression. Suggestions for future basic and clinical research directions are also discussed.

A chromone analog inhibits TNF-alpha induced expression of cell adhesion molecules on human endothelial cells via blocking NF-kappaB activation

The interaction between leukocytes and the vascular endothelial cells (EC) via cellular adhesion molecules plays an important role in various inflammatory and immune diseases. The molecules that block these interactions have been targeted as potential therapeutic targets for acute and chronic inflammatory diseases. In an effort to develop potent cell adhesion molecule inhibitors, a series of chromone derivatives bearing alkoxycarbonylvinyl unit at the C-3 position, that is, the chromones 8a-d and 9a-d, were designed and synthesized, and evaluated for their ICAM-1 inhibitory activity on human endothelial cells as well as their effect on NADPH-catalyzed rat microsomal lipid peroxidation. A structure-activity relationship was established and we found that length of the alkyl moiety of the chromone-3-yl-acrylate is important for this activity. Further, we found that incorporation of unsaturation in the alcohol moiety increases the potential of the compound for the inhibition of TNF-alpha induced expression of ICAM-1 and also for the inhibition of lipid peroxidation. Out of the screened compounds, the most potent compound ethyl trans-3-(4-oxo-4H-1-benzopyran-3-yl)-acrylate (8a) was taken for further study. We have found that compound 8a also significantly inhibited the TNF-alpha induced expression of VCAM-1 and E-selectin, which play key roles in various inflammatory diseases. This inhibition was found to be concentration dependent. The functional consequences of inhibiting cell adhesion molecules were studied by performing cell-adhesion assay. We found that compound 8a significantly blocks the adhesion of neutrophils to endothelial monolayer. To elucidate the molecular mechanism of inhibition of cell adhesion molecules, we investigated the status of nuclear transcription factor-kappaB (NF-kappaB) and were able to establish that compound 8a significantly blocked the TNF-alpha induced activation of NF-kappaB.

Effects of thalidomide on the expression of adhesion molecules in rat liver cirrhosis

This study was to evaluate the effects of thalidomide on expression of adhesion molecules in liver cirrhosis. The cirrhosis was induced in Wistar rats by intraperitoneal injection of CCl(4), and thalidomide (10 mg/kg/day or 100 mg/kg/day) was given by intragastric administration for 8 weeks. Liver histopathology and immunohistochemistry were significantly improved and the expressions of ICAM-1, VCAM-1, E-selectin, and TNF-alpha mRNA and protein were decreased significantly in rats treated with a high dose of thalidomide. Close positive correlation was observed in the expression of the TNF-alpha mRNA and that of ICAM-1, VCAM-1, and E-selectin mRNA, respectively. These results indicate that thalidomide exerts its effect on the downregulation of adhesion molecules via TNF-alpha signaling pathway to inhibit liver fibrosis.

Characterization of a Computerized Assay for Rapid and Easy Determination of Leukocyte Adhesion to Endothelial Cells

We report on a facile and rapid computerized in-vitro assay for the quantification of leukocyte adhesion to endothelial cells under static conditions using bovine polymorphonuclear neutrophils (PMN) or human leukaemic Mono Mac 6 cells (MM6) and bovine aorta endothelial cells (BAEC). Images of leukocytes adherent to BAEC monolayers grown in microtiter plates were obtained by a digital camera attached to a conventional microscope and transferred to the public domain NIH ImageJ program for analysis. Using individually adapted program routines adherent leukocytes are easily discriminated and reproducibly quantified. The results obtained with our assay correspond to previous findings and demonstrate the suitability of the described procedure, which can easily be adapted to further standards as proven by the use of two different leukocyte species. This assay lends itself to the screening of pharmacological substances with different mechanism of action that might act on either leukocytes or endothelial cells.