大麻二酚對小鼠Th1/Th2免疫平衡及遲發性過敏反應之免疫調節作用

Effects of cannabidiol on Th1/Th2 immunobalance and delayed-type hypersensitivity in ovalbumin-sensitized BALB/c mice

胡潔民(Chieh-Min Hu)

指導教授 ： 詹東榮

國立臺灣大學/獸醫專業學院/獸醫學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.03198

摘要

Cannabidiol (CBD)已證實具有免疫抑制及免疫調節的效果，然而CBD 是否對Th1/Th2 免疫平衡具調節作用，目前未有定論。遲發性過敏反應（delayed-type hypersensitivity; DTH）為一抗原專一性T 細胞所媒介之免疫反應，其動物模式適合使用於研究CBD 對抗原專一性免疫反應及抗發炎反應的效果及機制。舉例而言，以一T 細胞抗原卵白蛋白（ovalbumin; OVA）免疫並使BALB/c 鼠致敏，觀察腳掌腫脹反應之遲發性過敏反應動物模式已廣泛用於研究專一性抗原所引起之免疫反應。本研究之目的為研究CBD 對Th1/Th2 免疫平衡及遲發性過敏反應之調節作用。本論文實驗結果指出，離體模式（in vitro）中，CBD 抑制小鼠脾臟細胞OVA 專一性IFN-γ的產量，對OVA 專一性之IL-4 則無影響。進一步於DTH 活體模式（in vivo）中，證實低劑量CBD（1 mg/kg）抑制小鼠脾臟細胞中OVA 專一性之IFN-γ的產量，對Th2 細胞激素無影響；高劑量CBD（10 mg/kg）則會促進Th2 為主之OVA 專一性IL-10 的產量。綜合以上，本研究同時於離體及活體模式中證實CBD 於Th1/Th2 之免疫調節效用為以抑制Th1 為主的細胞激素產量，進而將平衡導向Th2。進一步研究CBD 對各細胞激素上游之訊息RNA（mRNA）表現量的影響，於離體實驗中觀察到CBD 抑制IFN-γ 、促進IL-4 訊息RNA 的表現量；在活體實驗中則觀察到CBD 抑制IFN-γ 及IL-12 訊息RNA 的表現量。此外，於局部免疫反應中發現給予CBD 能抑制小鼠足墊腫脹（footpad swelling），以免疫組織化學染色之方法（immunohistochemistry stain；IHC）觀察到CBD 抑制足墊中CD3+ T 細胞及巨噬細胞的數量，同時抑制T 細胞分泌IFN-γ的功能。進一步研究CBD 調節Th1/Th2 免疫反應之機制，文獻指出抗原呈現細胞內之抗氧化劑glutathione（GSH）下降會抑制其分泌IL-12 的能力，進而抑制Th1 免疫反應使平衡朝向Th2。本實驗室先前發表之期刊論文則指出，CBD 造成免疫細胞凋亡可能與細胞內GSH 下降有關。基於此論述及本實驗結果中觀察到CBD 抑制IL-12 之訊息RNA 表現量，假設CBD 是藉由抑制抗原呈現細胞中GSH下降進而抑制Th1 免疫反應。初步實驗結果顯示抗原呈現細胞內抗氧化劑glutathione（GSH）並未受到CBD 的影響，可能與偵測GSH 下降的時間點有關，或是藉由其他機制尚待進一步釐清。

關鍵字

大麻二酚 ； 免疫調節 ； 抗原專一性 ； T 細胞 ； 細胞激素 ； 抗氧化劑

並列摘要

Cannabidiol (CBD) has been shown to exhibit immunosuppressive and immunomodulatory effects. However, the effect of CBD on Th1/Th2 immunobalance remains to be fully elucidated.
As delayed-type hypersensitivity (DTH) reaction is an antigen-specific T cell-mediated immune response, DTH animal models are appropriate for studying the underlying mechanisms of CBD actions on both antigen-specific immune response and anti-inflammatory effects. For example, the foot pad swelling assessment of mice sensitized and challenged with a T-cell dependent protein antigen, ovalbumin (OVA) is a suitable animal model to investigate the underlying mechanisms of CBD-mediated effects on DTH. The present study aimed to investigate the effect of CBD on the Th1/Th2 immunobalance and DTH. The results of the present in vitro study indicated that direct CBD treatment attenuated OVA-induced IFN-γ produced by murine splenocytes, whereas OVA-induced IL-4 was not affected. Further, we showed that CBD administration induced a marked attenuation in the degree of food pad edema in a murine DTH model. Concordantly, the production of OVA-specific IFN-γ by splenocytes was significantly suppressed by CBD (1 mg/kg) administration; while CBD (10 mg/kg) increased OVA-induced IL-10 production. Collectively both in vitro and in
vivo results suggest a marked suppression of CBD on Th1 immune responses, whereas the Th2 profile was relatively unaffected. Moreover, direct CBD treatment decreased
IFN-γ mRNA expression, whereas IL-4 was relatively unaffected. CBD (1 mg/kg) administration showed a diminishment in IFN-γ and IL-12 mRNA expression. On the
other hand, we showed that CBD diminished CD3+ T cell and F4/80+ macrophage infiltration in foot pads and inhibited the secreting of IFN-γ by T cells. Recent reports have shown that glutathione (GSH) depletion in dendritic cells shift Th1 immune response toward Th2 direction by inhibiting their ability to secret IL-12. Moreover, we
previously reported that lymphocytes are sensitive to CBD-induced apoptosis possibly through the oxidative stress in parallel with GSH diminishment. Based on these reports
and decreased IL-12 mRNA by CBD treatment in the present study, we further hypothesized that CBD inhibited Th1 immune response through diminishing GSH level in dendritic cells. However, CBD administration did not affect GSH level in APCs in the present study. The mechanisms of CBD immunomodulatory effect shifting Th1 immune response toward Th2 remain to be further investigated.

並列關鍵字

cannabidiol ； immunomodulatory ； antigen-specific ； T cell ； cytokine ； glutathione

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