介白素 15 調控腸道介白素 17A 及干擾素-γ的產生

Regulation of intestine interleukin-17A and interferon-γ production by interleukin-15

黃思華(Tzu-Hua Huang)

指導教授 ： 呂思潔

共同指導教授 ： 廖南詩

臺北醫學大學/醫學院/醫學科學研究所/碩士(2014年)

https://doi.org/10.6831/TMU.2014.00087

摘要

介白素 15(Interleukin-15, IL-15)參與多種淋巴細胞的發育及存活,其表現於多種型態細胞上,包括腸道上皮細胞(intestinal epithelial cell, IEC)。為了瞭解 IL-15 對於腸道免疫系統的影響,我利用本實驗室製造的腸道上皮細胞 IL-15 基因剔除 (Il15 f/f Vil-Cre)小鼠來研究 IEC 產生的 IL-15 在腸道免疫的功能。我發現不同於 IL-15 基因剔除(Il15-/-)小鼠,Il15 f/f Vil-Cre 小鼠的自然殺手細胞(natural killer cells, NK cells),自然殺手 T 細胞(Natural killer T cells, NKT cells)及 TCRβ+CD8+ T 細 胞(memory CD8+ T cells)在腸道黏膜固有層(lamina propria; LP)或非腸道淋巴 器官正常,但在小腸 LP 中 TCRγδ+NK1.1-CD8+ T 細胞數目卻減少,跟 Il15-/-小鼠一 樣。IEC 產生的 IL-15 似乎足以支持 TCRγδ+NK1.1-CD8+ T 細胞在小腸 LP 中的恆 定性。對於腸道上皮淋巴細胞(intestinal intraepithelial lymphocytes, iIELs),Il15-/- 小鼠之小腸及大腸的 TCRβ+和 TCRγδ+的 CD8αα single positive(SP, CD4-CD8+) 和 CD4+CD8-(double negative, DN)iIELs 及小腸的 TCRβ+和 TCRγδ+的 CD8αβ SP iIELs 數目減少。IEC 產生的 IL-15 足以支持小腸及大腸的 TCRβ+CD8αα SP iIELs 和小腸的 TCRγδ+ CD8αα SP 及 CD8αβ SP iIELs 恆定性。然而 IEC 產生的 IL-15 部 分支持大腸的 TCRβ+ DN iIELs 和小腸及大腸的 TCRγδ+ DN iIELs 中的恆定性。但 不支持小腸的 TCRβ+CD8αβ SP 和 TCRβ+DN iIELs 及大腸的 TCRγδ+ CD8αα SP iIELs 恆定性。
在腸道免疫中,介白素17(Interleukin-17, IL-17)及干擾素-(γ interferon-γ, IFN-γ) 分別對於腸道防禦及屏障的功能相當重要。然而,對於腸道的 IL-17 及 IFN-γ調控仍不清楚。我發現 Il15-/-小鼠在小腸及大腸 LP 中 TCRβ+和 TCRγδ+ DN,及小腸 LP 之 CD4+的 IL-17A+細胞比例增加。然而,Il15 f/f Vil-Cre 小鼠的小腸 LP 中 TCRβ+DN 和 CD4+的 IL-17A+細胞比例增加。但 IL-15 並不去影響 iIELs 的 IL-17A 製造。因此,IL-15 負向調控小腸及大腸 LP 中 TCRβ+和 TCRγδ+DN cell,及小腸 LP 中 CD4+ T cells 的 IL-17A 製造。
我發現 IL-15 也會去調控腸道 IFN-γ的製造。在 LP 中,Il15-/-小鼠小腸及大腸 LP 之 TCRγδ+DN 和小腸 LP 之 TCRβ+DN 的 IFN-γ+細胞減少,但在大腸 LP 之 TCRβ+CD4+和 CD8+的 IFN-γ+細胞增加。另一方面,IEC 產生的 IL-15 正向調控小 腸之 TCRγδ+DN T cell 的 IFN-γ產生。在 iIELs 中,Il15-/-小鼠小腸及大腸之 TCRβ+CD8αα SP 和 TCRβ+DN iIELs,和小腸之 TCRβ+CD4+CD8+ (double-positive; DP) iIELs 及大腸之 TCRβ+CD8αβ SP iIELs 中 IFN-γ+細胞增加,但在小腸之 TCRγδ+DN iIELs 中 IIFN-γ+細胞卻減少。另一方面,Il15 f/f Vil-Cre 小鼠小腸之 TCRβ+CD8αα SP 和大腸之 TCRβ+CD8αβ SP iIELs 的 IFN-γ+細胞增加,但在小腸 之 TCRγδ+DN iIELs 的 IIFN-γ+細胞卻減少。這些研究結果顯示 IL-15 負向調控腸道 之 TCRβ+CD8αα SP 和 TCRβ+DN iIELs,及大腸的 TCRβ+CD8αβ SP iIELs 的 IFN-γ 製造,但正向調控於小腸之 TCRγδ+DN iIELs 的 IFN-γ製造。
除此之外,我也發現在 Il15-/-小鼠身上小腸的調節性 T 細胞(regulatory T cells, Treg)減少。然而,IL-15 對於口服耐受性的產生並不重要。本篇研究指出 IL-15 調控腸道的 IL-17A 及 IFN-γ產生。


關鍵字

介白素 15 ； 介白素 17A ； 干擾素-γ ； 腸道

並列摘要

Interleukin-15 (IL-15) is essential for the development and survival of several lineages of lymphocyte and is expressed by many cell types, including intestinal epithelial cell (IEC). To understand the function of IL-15 in the intestinal immune system, I used Il15f/f Vil-Cre mice generated in our lab to investigate the function of IEC-derived IL-15. I found that, unlike Il15-/- mice, Il15f/f Vil-Cre mice had no deficiency of NK cells, NKT cells and TCRβ+CD8+ T cells in the intestine lamina propria (LP) or in non-intestinal lymphoid organs, but showed similar level of reduction of TCRγδ+NK1.1-CD8+ cells in the small intestine LP (siLP) as Il15-/- mice. Therefore, IEC-derived IL-15 was likely sufficient to support for the homeostasis of TCRγδ+NK1.1-CD8+ siLP cells. For intestinal intraepithelial lymphocytes (iIELs), Il15-/- mice showed reduction in the CD8αα single positive (SP, CD4-CD8+) and CD4+CD8- (double negative, DN) subsets of TCRβ+ and TCRγδ+ iIELs in the small intestine and colon, and reduction of CD8αβ SP subset of TCRβ+ and TCRγδ+ siIELs. IEC-derived IL-15 was sufficient to support the homeostasis of TCRβ+CD8αα SP siIELs and cIELs, and the homeostasis of TCRγδ+ CD8αα SP and CD8αβ SP siIELs. Whereas IEC-derived IL-15 partially supported the homeostasis of TCRβ+ DN cIELs and of TCRγδ+ DN siIELs and cIELs but did not support the homeostasis of TCRβ+CD8αβ SP and TCRβ+DN siIELs, and TCRγδ+ CD8αα SP cIELs.
Interleukin-17 (IL-17) and interferon-γ (IFN-γ) are critical for mucosal defense and epithelial barrier function in the intestine, respectively. The regulation of intestinal IL-17 and IFN-γ production is not fully understood. I found that Il15-/- mice displayed elevated IL-17A+ cell frequency in TCRβ+ and TCRγδ+ DN cells of the siLP and colon LP (cLP), and in TCRβ+CD4+ cells of the siLP; whereas, Il15f/f Vil-Cre mice displayed elevated IL-17A+ cell frequency in TCRβ+ DN and CD4+ cells of the siLP. However, IL-15 does not affect IL-17A production by iIELs. Thus, IL-15 negatively regulates intestinal IL-17A production by TCRβ+ and TCRγδ+ DN cells in the siLP and cLP, and TCRβ+ CD4+ cells in the siLP.
I also found that IL-15 regulates intestinal IFN-γ production. In the LP, Il15-/- mice showed decreased IFN-γ+ cells in TCRγδ+DN siLP and cLP cells and in TCRβ+DN siLP cells, but increased IFN-γ+ cells in TCRβ+ CD4+ and CD8+ cLP cells. On the other hand, IEC-derived IL-15 positively regulated IFN-γ production in TCRγδ+DN siLP cells. In the IEL compartment, Il15-/- mice had increased IFN-γ+ cells in TCRβ+CD8αα SP and DN siIELs and cIELs, in TCRβ+CD4+CD8+ (double positive, DP) siIELs, and in TCRβ+CD8αβ SP cIELs, but decreased IFN-γ+ cells in TCRγδ+DN siIELs. On the other hand, Il15f/f Vil-Cre mice had increased IFN-γ+ cells in TCRβ+CD8αα SP siIEL and TCRβ+CD8αβ+ cIEL, but decreased IFN-γ+ cells in TCRγδ+DN siIELs. Thus, IL-15 negatively regulates intestinal IFN-γ production by TCRβ+CD8αα SP and DN iIELs and by TCRβ+CD8αβ SP cIELs, while positively regulates IFN-γ production by TCRγδ+DN siIELs.
In addition to cytokine production, I also found that Il15-/- mice had reduced regulatory T cells (Treg) cells in the siLP. However, IL-15 is not essential for induction of oral tolerance. Taken together, this study reveals the regulation of intestinal IL-17A and IFN-γ production by IL-15.

並列關鍵字

IL-15 ； IL-17A ； IFN-γ ； intestine

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