ProstaglandinE2刺激巨噬細胞移行和TNF-alpha釋放機轉之探討

巨噬細胞之COX-2會受到LPS活化而誘發表現，這會增加前列腺素E2 (PGE2) 的濃度。PGE2是一個pro-inflammatory factor，可以引起免疫反應如:紅、腫、熱、痛及發燒。由本實驗室之前發現c-Src的表現量與巨噬細胞活化有關，伴隨著的生理現象為移行能力增加及TNF-a量上升。本文研究發現，對動物的腹腔巨噬細胞處理COX-2 inhibitor (NS-398)，可以抑制LPS-induced TNF-a secretion及migration，究其原因在於PGE2，藉由誘增巨噬細胞的c-Src表現量而增加其移行能力及TNF-a的分泌。而在此同時，已知三個在巨噬細胞高表現的Src family kinase: Lyn、Fgr、及Hck，其蛋白量則不會受到影響。此外，我們在老鼠腹腔注射PGE2 48小時後的thioglycolate-elicited peritoneal macrophages (PEMs)，也看得到一致的結果。由於dibutyryladenosine 3´:5´-cyclic對巨噬細胞的影響與PGE2相同，且H-89 (PKA抑制劑)會抑制PGE2-induced macrophage activation，故說明了cAMP與PKA於其間角色之重要。最後，我們利用不同的訊息傳遞抑制劑，證明NF-kB、MEK、PI3K在PGE2活化巨噬細胞的過程中，可能也參與其中。

Accumulated evidence indicates that LPS-treated macrophage-induced COX-2 expression results in increased generation of prostaglandin E2 (PGE2). As a pro-inflammatory factor, PGE2 will ultimately leads to redness, swelling, heat, and pain. Previously, our laboratory has discovered the induction of c-Src in macrophages upon LPS exposure, which might contribute to macrophage migration and the secretion of TNFa. In this study, we demonstrated that LPS-mediated c-Src induction and migration were both abrogated in macrophage pre-treated with NS-398 (COX-2 inhibitor), implicating the involvement of PGE2 in macrophage activation. Intriguingly, while there was no alteration of the expression of the myeloid-specific SFKs (Hck, Lyn, and Fgr), upregulation of Src was detected in PGE2-stimulated Raw264.7 and rat peritoneal macrophage (PEMs). Elevated Src expression was participated in PGE2-induced macrophage mobility and TNFa secretion since PP2 could abolish all these effects. Remarkably, macrophages stimulated with dibutyryl adenosine (db-cAMP, a cAMP analogue) exhibited the similar results as those treated with PGE2, suggesting that cAMP was the second messenger in the signaling pathways initiated by PGE2. Notably, c-Src induction could also be detected in PEMs recovered from rats challenged with PGE2 and db-cAMP. Since H-89 (PKA inhibitor) could suppress PGE2-mediated c-Src induction and the concomitant macrophage migration and TNFa secretion, indicating the pathway: PGE2→AC→cAMP→PKA→Src. Due to LY294002 (PI3K inhibitor), PDTC (NF-kB inhibitor), PP2 (SFK inhibitor) could attenuate PGE2-mediated Src induction, it was likely that PI3K, NF-kB and SFK were also involved in this process.