Anti-Apoptotic and Anti-Inflammatory Activities of Edible Fresh Water Algae <i>Prasiola japonica</i> in UVB-Irradiated Skin Keratinocytes

Abstract

Skin is the outer tissue layer and is a barrier protecting the body from various external stresses. The fresh water green edible algae <i>Prasiola japonica</i> has antiviral, antimicrobial, and anti-inflammatory properties; however, few studies of its effects on skin-protection have been reported. In this study, <i>Prasiola japonica</i> ethanol extract (Pj-EE) was prepared, and its skin-protective properties were investigated in skin keratinocytes. Pj-EE inhibited ROS production in UVB-irradiated HaCaT cells without cytotoxicity. Pj-EE also suppressed the apoptotic death of UVB-irradiated HaCaT cells by decreasing the generation of apoptotic bodies and the proteolytic activation of apoptosis caspase-3, -8, and -9. Moreover, Pj-EE downregulated the mRNA expression of the inflammatory gene cyclooxygenase-2 (COX-2), the pro-inflammatory cytokine genes interleukin (IL)-1<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math>, IL-8, IL-6, tumor necrosis factor (TNF)-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math>, and interferon (IFN)-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>γ</mml:mi></mml:math>, and the tissue remodeling genes matrix metalloproteinase (MMP)-1, -2, -3, and -9. The Pj-EE-induced anti-inflammatory effect was mediated by suppressing the activation of nuclear factor-kappa B (NF-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>κ</mml:mi></mml:math>B) signaling pathway in the UVB-irradiated HaCaT cells. Taken together, these results suggest that Pj-EE exerts skin-protective effects through anti-oxidant, anti-apoptotic, and anti-inflammatory activities in skin keratinocytes.