Cilostazol Protects Endothelial Cells Against Lipopolysaccharide-Induced Apoptosis Through ERK1/2- and P38 MAPK-Dependent Pathways

BACKGROUND/AIMS: We examined the effects of cilostazol on mitogen-activated protein kinase (MAPK) activity and its relationship with cilostazol-mediated protection against apoptosis in lipopolysaccharide (LPS)-treated endothelial cells. METHODS: Human umbilical vein endothelial cells (HUVECs) were exposed to LPS and cilostazol with and without specific inhibitors of MAPKs; changes in MAPK activity in association with cell viability and apoptotic signaling were investigated. RESULTS: Cilostazol protected HUVECs against LPS-induced apoptosis by suppressing the mitochondrial permeability transition, cytosolic release of cytochrome c, and subsequent activation of caspases, stimulating extracellullar signal-regulated kinase (ERK1/2) and p38 MAPK signaling, and increasing phosphorylated cAMPresponsive element-binding protein (CREB) and Bcl-2 expression, while suppressing Bax expression. These cilostazol-mediated cellular events were effectively blocked by MAPK/ERK kinase (MEK1/2) and p38 MAPK inhibitors. CONCLUSIONS: Cilostazol protects HUVECs against LPS-induced apoptosis by suppressing mitochondriadependent apoptotic signaling. Activation of ERK1/2 and p38 MAPKs, and subsequent stimulation of CREB phosphorylation and Bcl-2 expression, may be responsible for the cellular signaling mechanism of cilostazolmediated protection.

Toll-like receptor 9 dependent activation of MAPK and NF-kB is required for the CpG ODN-induced matrix metalloproteinase-9 expression

Unmethylated CpG oligodeoxynucleotides (CpG ODNs) activate immune cells to produce immune mediators. This study demonstrates that in murine macrophage RAW 264.7 cells, CpG ODN-mediated matrix metalloproteinase-9 (MMP-9) expression is regulated at transcriptional level and requires de novo protein synthesis. Inhibition of ERK and p38 MAPK, but not JNK, results in significant decrease of CpG ODN-induced MMP-9 expression. We found that endosomal maturation inhibitors, chloroquine and bafilomycin A, block CpG ODN-induced ERK and p38 MAPK activation and the subsequent MMP-9 expression. We also observed that CpG ODN induces NF-kappa B activation and NF-kappa B is a downstream target of p38 MAPK. Taken together, our data demonstrate that CpG ODN triggers MMP-9 expression via TLR-9 dependent ERK and p38 MAPK activation followed by NF-kappa B activation.

Inhibitory effect of Hsp70 on angiotensin II-induced vascular smooth muscle cell hypertrophy

Angiotensin II (Ang II), which is an important mediator of both vascular responsiveness and growth, has been shown to induce vascular smooth muscle cell (VSMC) hypertrophy via the activation of a complex series of intracellular signaling events. Heat shock protein 70 (Hsp70) has recently been shown to protect against Ang II-induced hypertension. In this study, we tested the hypothesis that Hsp70 can protect VSMC from Ang II-induced hypertrophy. We treated VSMCs with Ang II to induce hypertrophy and to activate MAPK signaling pathway. We observed that the augmentation of Hsp70 expression inhibited Ang II-stimulated VSMC hypertrophy. This inhibitory effect of Hsp70 appears to be partly due to extracellular signal-regulated kinase (ERK1/2) inactivation, which in turn, may possibly result from the accumulation of MAP kinase phosphatase-1 (MKP-1).