Reverse-D-4F improves endothelial progenitor cell function and attenuates LPS-induced acute lung injury.

BACKGROUND: Patients with acute lung injury (ALI) have increased levels of pro-inflammatory mediators, which impair endothelial progenitor cell (EPC) function. Increasing the number of EPC and alleviating EPC dysfunction induced by pro-inflammatory mediators play important roles in suppressing ALI development. Because the high density lipoprotein reverse-D-4F (Rev-D4F) improves EPC function, we hypothesized that it might repair lipopolysaccharide (LPS)-induced lung damage by improving EPC numbers and function in an LPS-induced ALI mouse model. METHODS: LPS was used to induce ALI in mice, and then the mice received intraperitoneal injections of Rev-D4F. Immunohistochemical staining, flow cytometry, MTT, transwell, and western blotting were used to assess the effect of Rev-D4F on repairment of lung impairment, and improvement of EPC numbers and function, as well as the signaling pathways involved. RESULTS: Rev-D4F inhibits LPS-induced pulmonary edema and decreases plasma levels of the pro-inflammatory mediators TNF-α and ET-1 in ALI mice. Rev-D4F inhibited infiltration of red and white blood cells into the interstitial space, reduced lung injury-induced inflammation, and restored injured pulmonary capillary endothelial cells. In addition, Rev-D4F increased numbers of circulating EPC, stimulated EPC differentiation, and improved EPC function impaired by LPS. Rev-D4F also acted via a PI3-kinase-dependent mechanism to restore levels of phospho-AKT, eNOS, and phospho-eNOS suppressed by LPS. CONCLUSIONS: These findings indicate that Rev-D4F has an important vasculoprotective role in ALI by improving the EPC numbers and functions, and Rev-D4F reverses LPS-induced EPC dysfuncion partially through PI3K/AKT/eNOS signaling pathway.

Sphingosine-1-Phosphate Improves the Biological Features of Mouse Bone Marrow-Derived EPCs Partially through PI3K/AKT/eNOS/NO Pathway.

Sphingosine-1-phosphate (S1P), a bioactive sphingolipid, is recognized as a critical regulator in physiological and pathophysiological processes of atherosclerosis (AS). However, the underlying mechanism remains unclear. As the precursor cells of endothelial cells (ECs), endothelial progenitor cells (EPCs) can prevent AS development through repairing endothelial monolayer impaired by proatherogenic factors. The present study investigated the effects of S1P on the biological features of mouse bone marrow-derived EPCs and the underlying mechanism. The results showed that S1P improved cell viability, adhesion, and nitric oxide (NO) release of EPCs in a bell-shaped manner, and migration and tube formation dose-dependently. The aforementioned beneficial effects of S1P on EPCs could be inhibited by the phosphatidylinositol 3-kinase (PI3K) inhibitor of LY294002 and nitric oxide synthase (NOS) inhibitor of N'-nitro-L-arginine-methyl ester hydrochloride (L-NAME). The inhibitor of LY294002 inhibited S1P-stimulated activation of phosphorylated protein kinase B (AKT) (p-AKT) and endothelial nitric oxide synthase (eNOS) (p-eNOS), and down-regulated the level of eNOS significantly. The results suggest that S1P improves the biological features of EPCs partially through PI3K/AKT/eNOS/NO signaling pathway.