於巨噬細胞中探討 1-nitropyrene 經由 Bcl-2 家族誘發細胞凋亡之機制

空氣汙染是一個重要的環境議題，大氣懸浮微粒是一種長期存在於空氣中的環境汙染物，如多環芳香烴及硝基多環芳香烴。硝基多環芳香烴中又以 1-Nitropyrene (1-NP) 最具代表性。有文獻總結出，硝基多環芳香烴會藉由促使人體內的單核細胞、淋巴細胞與巨噬細胞產生氧化壓力，以致於 DNA 受損。巨噬細胞在諸多免疫反應過程中扮演相當重要的角色。但是至今為止，尚無文獻研究 1-NP 對於巨噬細胞的細胞毒性及死亡過程有何影響。在我們之前的研究中，發現 1-NP 會誘使小鼠巨噬細胞 RAW264.7 產生細胞毒性及基因毒性。1-NP 會藉由增加 ROS 的產生量以及 caspase-3、-8 及 -9 的活性來誘發細胞毒性。本研究發現，隨著 ROS 的產生，1-NP 會增加細胞內的 p38 MAPK、JNK 及 p53磷酸化的表現量。進而藉由調控 Bcl-2 家族，致使粒線體外膜電位下降，釋放 cytochrome c 及 AIF 至細胞質。Cytochrome c 會與 Apaf-1 及 caspases-9 結合形成凋亡體，活化 caspases-3 並切割 PARP-1，引發細胞凋亡；AIF 會轉位至細胞核中，造成 DNA 受損。本研究有助於瞭解 1-NP 誘發巨噬細胞 ROS 藉由 caspases 路徑導致細胞凋亡的現象。另一方面，1-NP 所誘發巨噬細胞凋亡也會被ROS抑制劑解除。

Air pollution is a major environmental issue, airborne particles such as polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs, are main source of persistent environmental contaminants. 1-Nitropyrene (1-NP) is considered as a representative and plays a major role in nitro-PAHs. Previous studies have shown that nitro-PAHs could cause DNA damage by inducing oxidative stress and inflammatory response in monocytes, lymphocytes and macrophages within the blood of human body. Up to date, there are no evidence have demonstrated that it effects on cytotoxicity and cell death processes with macrophages. Since macrophages play a critical role in the immune system, it is important to know how 1-NP cause macrophage death. Our previous studies have shown that cytotoxicity and genotoxicity are induced by 1-NP.We also demonstrated that 1-NP-induced cytotoxicity might be up-regulated by the generation of reactive oxygen free radicals (ROS) and activation of caspase-3, -8 and -9. Therefore, in this study, we further demonstrated that 1-NP enhances the expression of p38 MAPK, JNK and p53 phosphorylation through upregulating the generation of ROS. There is a decrease in mitochondria membrane pontential （ΔΨm） via regulation of Bcl-2 family, causing release of cytochrome c then combined with apaf-1 and caspase-9 to form an apoptosome, followed by activating caspase-3 and cleaved PARP-1 which resulted in apoptosis. We also showed that AIF was translocated into nuclear and causing DNA damage. Our data suggest that caspase-3, -8, -9 are activated by 1-NP-induced ROS and DNA damage in RAW264.7 macrophages. Furthermore, 1-NP-induced ROS can be inhibited by ROS inhibitor (NAC).