半乳糖凝集素-8在乾癬致病機轉中於角質細胞的影響

Abstract

乾癬是一種慢性皮膚發炎性疾病，主要特徵為非常明顯的發炎反應與顯著增厚的表皮層，它的產生受到介白質23與輔助型T細胞17的調控。在本研究中，我們發現半乳糖凝集素8在乾癬病人皮膚病灶的表皮層顯著增加，於皮內注射介白質23的乾癬小鼠模型也有觀察到半乳糖凝集素8的增加，以介白質17A刺激人類角質細胞也可以誘導半乳糖凝集素8呈現與刺激強度相對應地增加。在乾癬動物模型中，半乳糖凝集素8基因剔除鼠的角質細胞增生較不明顯。角質細胞中的半乳糖凝集素8多寡與細胞的增生能力呈現正相關，半乳糖凝集素8基因剔除的角質細胞於細胞同步實驗中，從有絲分裂期進展到生長期的速度較緩慢。細胞免疫螢光染色與細胞裂解液轉染都顯示半乳糖凝集素8會表現在有絲分裂器上。藉由免疫沈澱法與蛋白質質譜法分析，我們發現半乳糖凝集素8於有絲分裂時會與α微管蛋白有交互作用，進而於免疫螢光染色下發現半乳糖凝集素8缺乏的細胞其有絲分裂器上的中心粒周圍蛋白的結構較鬆散且有絲分裂微管束較短。綜合上述發現，我們結論認為在乾癬的皮膚角質細胞中，半乳糖凝集素8會被調控增加，於有絲分裂時經由與α微管蛋白的交互作用，維持有絲分裂器上中心粒結構的完整，進而正向調控角質細胞的增生。

Psoriasis is a chronic inflammatory skin disease that develops under the influence of the interleukin-23/Th17 axis and is characterized by intense inflammation and prominent epidermal hyperplasia. Here, we demonstrate that galectin-8, a β–galactoside-binding lectin, is upregulated in the epidermis of human psoriatic skin lesions, as well as a mouse model of psoriasis induced by intradermal IL-23 injections, and in IL-17A-treated keratinocytes. We show keratinocyte proliferation is less prominent in galectin-8-knockout mice following intradermal IL-23 treatment compared to wild type mice. In addition, we show that galectin-8 levels in keratinocytes are positively correlated with the ability of cells to proliferate, and that transition from mitosis into G1 phase is delayed in galectin-8-knockout HaCaT cells after cell cycle synchronization and release. We demonstrate by immunofluorescence staining and immunoblotting the presence of galectin-8 within the mitotic apparatus. We reveal by co-immunoprecipitation and mass spectrometry analysis that α-tubulin interacts with galectin-8 during mitosis. Finally, we show, in the absence of galectin-8, pericentrin compactness is lessened and mitotic microtubule length is shortened, as demonstrated by immunofluorescence staining. We conclude that galectin-8 is upregulated in psoriasis and contributes to the hyperproliferation of keratinocytes by maintaining centrosome integrity during mitosis through interacting with α-tubulin.