Euglena gracilis, a type of microalgae, contains several nutrients and accumulates paramylon, a β-1,3-glucan. In recent studies, paramylon has shown to exhibit various activities including immunomoduratory and hepatoprotective effects. In the present study, using an in vitro cell culture system, we aimed to determine whether paramylon derived from the E. gracilis EOD-1 strain, which produces large amounts of paramylon, can augment SIRT1 expression in epidermal cells via activating gut–skin interactions. Results showed that paramylon augmented the expression of SIRT1 in Caco-2 cells, a human intestinal cell line. Furthermore, microarray analysis of Caco-2 cells treated with paramylon showed that paramylon activates epidermal cells through inducing the secretion of factors from intestinal cells. Then, we focused on skin cells as target cells of paramylon-activated intestinal cells. Results showed that secretory factors from Caco-2 cells treated with paramylon augmented the expression of SIRT1 in HaCaT cells, a human keratinocyte cell line, and that expression level of genes related to the growth and maintenance of epidermal cells were significantly changed in Caco-2 cells treated with paramylon as evidenced by microarray analysis. All these results suggest that paramylon can activate epidermal cells by inducing the production of secretory factors from intestinal cells.

Euglena gracilis是一种微藻，含有多种营养物质并积累副淀粉质，一种 β-1,3-葡聚糖。在最近的研究中，副淀粉显示出多种活性，包括免疫调节和保肝作用。在本研究中，使用体外细胞培养系统，我们的目的是确定副淀粉质是否来自E. gracilisEOD-1 菌株可产生大量副淀粉，可通过激活肠道-皮肤相互作用来增加表皮细胞中 SIRT1 的表达。结果表明，副淀粉增强了 SIRT1 在 Caco-2 细胞（一种人类肠道细胞系）中的表达。此外，用副淀粉处理的 Caco-2 细胞的微阵列分析表明，副淀粉通过诱导肠道细胞分泌因子来激活表皮细胞。然后，我们将皮肤细胞作为副淀粉激活肠细胞的靶细胞。结果表明，用副淀粉酶处理的 Caco-2 细胞的分泌因子增加了 SIRT1 在 HaCaT 细胞中的表达，HaCaT 细胞是一种人角质形成细胞系，微阵列分析证明，在用副淀粉处理的 Caco-2 细胞中，与表皮细胞生长和维持相关的基因表达水平发生了显着变化。所有这些结果表明，副淀粉可以通过诱导肠细胞产生分泌因子来激活表皮细胞。