探討乾癬表皮中角質細胞的異常分化與增生

Aberrant Differentiation and Proliferation of Keratinocytes in Psoriatic Epidermis

呂紹祁(Shao-Qi Lu)

指導教授 ： 林頌然

國立臺灣大學/工學院/醫學工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201801515

摘要

表皮作為人體跟外界的第一道防線，而維持表皮恆定主要是透過坐落在基底層的表皮幹細胞產生子代的幹細胞或短暫分裂細胞來更新老舊的表皮細胞。若表皮幹細胞的增生與分化出現異常，則可能導致疾病的產生。乾癬是一種常見的皮膚發炎疾病，特徵包含表皮增生、脫屑、紅腫的現象。然而至今因無法在時間與空間上連續觀察表皮幹細胞的行為，因此尚未釐清在乾癬疾病中的表皮幹細胞之動態。本實驗透過小鼠乾癬模型與雙光子顯微鏡的技術，來研究乾癬表皮中幹細胞的動態，藉此釐清乾癬症狀產生的機制為何。根據實驗結果，我們發現在小鼠乾癬模型中，基底層增加許多BrdU-positive的細胞，而透過活體影像觀察K14-H2B-EGFP的小鼠表皮，也發現基底層有增加許多對稱性細胞分裂，且無任何細胞分裂出現在上基底層中。由組織染色的結果來看，我們發現Keratin-5的表現有顯著地增加，位置由基底層異常延伸至最外層，而Keratin-10的表現也有增加，但仍侷限在上基底層中。最後，我們透過利用Keratin-5CreERT2; mTmG; K14-H2B-EGFP與低劑量的Tamoxifen 來追蹤單一顆細胞，發現到在小鼠乾癬模型中，表皮細胞由基底層分化到角質層後脫落的時間比正常情況增快許多。綜合以上結果，乾癬造成的表皮增厚與基底層幹細胞的快速分裂、延遲分化還有細胞快速由基底層向上轉換並脫離表皮有非常大的關係。在未來若我們可以著手在治療乾癬環境下失調的表皮細胞動態，使其回復正常，將可作為一種有效治療慢性乾癬的方法。

關鍵字

乾癬 ； 樂得美乳膏5% ； 增生 ； 分化 ； 細胞動態 ； 雙光子顯微鏡 ； 長時間活體影像 ； 幹細胞

並列摘要

The epidermis acts as the first line of defense against the external insults. Homeostasis of the epidermis is maintained by the epidermal stem cells located in the basal layer that replenish the cells lost due to continuous cell shedding. Defected epidermal stem cell proliferation and differentiation may lead to epidermal diseases. Psoriasis, a common inflammatory skin disease, is characterized by erythematous, thick and scaling plaques. Up to date, the dynamics of epidermal stem cells in psoriatic skin is still unclear due to a lack of tempo-spatial characterization of their behavior. In this study, we used the two-photon microscope and the imiquimod-induced psoriasis-like skin inflammation mouse model to dissect the epidermal stem cell dynamics of psoriasis. Compared with control mice, we found increased pulse BrdU-labeled cells in the basal layer. Through live two-photon imaging in K14-H2B-EGFP transgenic mice, we observed accelerated symmetric cell division in the basal layer in the psoriasis-like lesions and no cell division was observed in the suprabasal layers. Immunofluorescence analysis showed that the expression of keratin-5 was significantly increased with aberrant extension from the basal layer to the outer layers and that keratin-10 was also increased but confined to the thickened suprabasal layers. Finally, we traced single cell in keratin-5CreERT2; mTmG; K14-H2B-EGFP transgenic mice by low dose tamoxifen induction and found that the cell extrusion rate was prominently increased in the psoriasis-like skin. Taken together, these findings suggest that epidermal hyperplasia in psoriasis is contributed by increased proliferation, delayed differentiation and a higher rate of extrusion of basal stem cell. The results provide insight in the development of new therapeutic strategies to target the disordered epidermal dynamics in psoriasis.

並列關鍵字

psoriasis ； imiquimod (IMQ) ； proliferation ； differentiation ； cell dynamics ； two-photon microscopy ； time-lapse live imaging ； stem cell

參考文獻

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