Tetrahydrobiopterin Inhibits PDGF-stimulated Migration and Proliferation in Rat Aortic Smooth Muscle Cells via the Nitric Oxide Synthase-independent Pathway

Neopterin derivatives - a novel therapeutic target rather than biomarker for atherosclerosis and related diseases

This review provides an updated overview of the emerging roles of neopterin derivatives in atherosclerosis. Neopterin, a metabolite of guanosine triphosphate, is produced by interferon-γ-activated macrophages and is expressed at high levels in atheromatous plaques within the human carotid and coronary arteries as well as in the aorta. Plasma concentrations of neopterin are higher in patients with carotid, cerebral, and coronary artery diseases as well as aortic aneurysm. The concentration of neopterin is positively correlated with the severity of coronary artery disease. However, a prospective cohort study showed that neopterin contributes to protection against plaque formation in carotid arteries in patients with atherosclerosis. Moreover, using both in vitro and in vivo experiments, a recent study has shown the atheroprotective effects of neopterin. Neopterin suppresses the expression of monocyte chemotactic protein-1, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1 in endothelial cells, and thereby suppresses the adhesion of monocytes to endothelial cells. It also suppresses the inflammatory phenotype of monocyte-derived macrophages. In addition, neopterin suppresses oxidized low-density lipoprotein-induced foam cell formation in macrophages and the migration and proliferation of vascular smooth muscle cells. Neopterin injection into apolipoprotein E-deficient (Apoe^-/-) mice suppresses the development of atherosclerotic lesions. A neopterin derivative tetrahydroneopterin (BH4), also known as a cofactor for nitric oxide (NO) synthases, suppresses atherosclerosis and vascular injury-induced neointimal hyperplasia in Apoe^-/- mice. BH4 administration improves endothelial dysfunction in patients with coronary artery disease. These findings suggest that neopterin production may increase to counteract the progression of atherosclerosis, as neopterin contributes to atheroprotection. Otherwise, the increased neopterin levels in atherosclerosis may reflect a compensatory mechanism associated with inducible NO synthase upregulation in macrophages to supply BH4 for high output NO production caused by decreased endothelial NO synthase in atherosclerosis. Therefore, neopterin derivatives are a novel therapeutic target for atherosclerosis and related diseases.

Analeptic agent from microbes upon cyanide degradation

Microbes being the initial form of life and ubiquitous in occurrence, they adapt to the environment quickly. The microbial metabolism undergoes alteration to ensure conducive environment either by degrading the toxic substances or producing toxins to protect themselves. The presence of cyanide waste triggers the cyanide degrading enzymes in the microbes which facilitate the microbes to utilize the cyanide for its growth. To enable the degradation of cyanide, the microbes also produce the necessary cofactors and enhancers catalyzing the degradation pathways. Pterin, a cofactor of the enzyme cyanide monooxygenase catalyzing the oxidation of cyanide, is considered to be a potentially bioactive compound. Besides that, the pterins also act as cofactor for the enzymes involved in neurotransmitter metabolism. The therapeutic values of pterin as neuromodulating agent validate the necessity to pursue the commercial production of pterin. Even though chemical synthesis is possible, the non-toxic methods of pterin production need to be given greater attention in future.

Chrysanthemum boreale flower floral water inhibits platelet-derived growth factor-stimulated migration and proliferation in vascular smooth muscle cells

CONTEXT

Chrysanthemum boreale Makino (Compositae) (CBM) is a traditional medicine that has been used for the prevention or treatment of various disorders; it has various properties including antioxidation, anti-inflammation, and antitumor.

OBJECTIVE

The present study was designed to explore the in vitro effect of CBM flower floral water (CBMFF) on atherosclerosis-related responses in rat aortic smooth muscle cells (RASMCs).

MATERIALS AND METHODS

CBMFF was extracted from CBM flower by steam distillation and analyzed using gas chromatography-mass spectrometry. The anti-atherosclerosis activity of CBMFF was tested by estimating platelet-derived growth factor (PDGF)-BB (10 ng/mL)-induced proliferation and migration levels and intracellular kinase pathways in RASMCs at CBMFF concentrations of 0.01-100 μM and analyzing ex vivo aortic ring assay.

RESULTS

Gas chromatography-mass spectrometry showed that the CBMFF contained a total of seven components. The CBMFF inhibits PDGF-BB-stimulated RASMC migration and proliferation (IC50: 0.010 μg/mL). Treatment of RASMCs with PDGF-BB induced PDGFR-β phosphorylation and increased the phosphorylations of MAPK p38 and ERK1/2. CBMFF addition prevented PDGF-BB-induced phosphorylation of these kinases (IC50: 008 and 0.018 μg/mL, for p38 MAPK and ERK1/2, respectively), as well as PDGFR-β (IC50: 0.046 μg/mL). Treatment with inhibitors of PDGFR, P38 MAPK, and ERK1/2 decreased PDGF-BB-increased migration and proliferation in RASMCs. Moreover, the CBMFF suppressed PDGF-BB-increased sprout outgrowth of aortic rings (IC50: 0.047 μg/mL).

DISCUSSION AND CONCLUSION

These results demonstrate that CBMFF may inhibit PDGF-BB-induced vascular migration and proliferation, most likely through inhibition of the PDGFR-β-mediated MAPK pathway; therefore, the CBMFF may be promising candidate for the development of herbal remedies for vascular disorders.