No abstract

Oxidative stress plays an important role in the progression of various neuronal diseases including ischemia. Heat shock protein 22 (HSP22) is known to protect cells against oxidative stress. However, the protective effects and mechanisms of HSP22 in hippocampal neuronal cells under oxidative stress remain unknown. In this study, we determined whether HSP22 protects against hydrogen peroxide (H2O2)-induced oxidative stress in HT-22 using Tat-HSP22 fusion protein. We found that Tat-HSP22 transduced into HT-22 cells and that H2O2-induced cell death, oxidative stress, and DNA damage were significantly reduced by Tat-HSP22. In addition, Tat-HSP22 markedly inhibited H2O2-induced mitochondrial membrane potential, cytochrome c release, cleaved caspase-3, and Bax expression levels, while Bcl-2 expression levels were increased in HT-22 cells. Further, we showed that Tat-HSP22 transduced into animal brain and inhibited cleaved-caspase-3 expression levels as well as significantly inhibited hippocampal neuronal cell death in the CA1 region of animals in the ischemic animal model. In the present study, we demonstrated that transduced Tat-HSP22 attenuates oxidative stress-induced hippocampal neuronal cell death through the mitochondrial signaling pathway and plays a crucial role in inhibiting neuronal cell death, suggesting that Tat-HSP22 protein may be used to prevent oxidative stress-related brain diseases including ischemia.

In this study, the anti-inflammatory and antisepticemic activities of a water extract of aged black garlic (AGE), which is not pungent, were compared with those of raw garlic extract (RGE). The methyl thiazolyl tetrazolium (MTT) assay showed that AGE was not toxic up to 1000 μg/mL and was at least four times less cytotoxic than RGE. AGE significantly suppressed the production of nitric oxide (NO), tumor-necrosis factor-α (TNF-α), and prostaglandin (PG)-E2 in a dose-dependent manner in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Furthermore, the inhibitory effect of AGE on LPS-induced inflammation was confirmed by downregulation of inducible NO synthase and TNF-α mRNA expression, as well as cyclooxygenase-2 protein expression. The anti-inflammatory activities of AGE were similar to those of RGE at nontoxic concentrations up to 250 μg/mL. Signal transduction pathway studies further indicated that both garlic extracts inhibited activation of mitogen-activated protein kinase and nuclear factor-κB induced by LPS stimulation. Treatment with both AGE and RGE in an in vivo experiment of LPS-induced endotoxemia significantly reduced the level of TNF-α and interleukin-6 in serum and completely protected against LPS-induced lethal shock in C57BL/6 mice. The results suggest that AGE is a more promising nutraceutical or medicinal agent to prevent or cure inflammation-related diseases for safety aspects compared with RGE.