Department of Pathology and Hepatology, the 5th Medical Centre, Chinese PLA General Hospital, No. 100, Xisi Ring Middle Road, Beijing, 100039, China; Liver Transplantation and Research Center, the 5th Medical Centre, Chinese PLA General Hospital, No. 100, Xisi Ring Middle Road, Beijing, 100039, China.
Department of Pathology and Hepatology, the 5th Medical Centre, Chinese PLA General Hospital, No. 100, Xisi Ring Middle Road, Beijing, 100039, China.
Dig Liver Dis. 2020 Jun;52(6):637-643. doi: 10.1016/j.dld.2020.03.021. Epub 2020 Apr 29.
In the present study, we propose that lipotoxicity induces the release of mitochondrial DNA (mtDNA) from hepatocytes, which in turn upregulates IL-33 expression in macrophages.
The mtDNA levels of plasma were determined in methionine- and mholine-deficient diet (MCD)-fed mice and NASH patients. Cultured hepatocytes were pre-incubated with Mito-TEMPO or rapamycin and were then stimulated with palmitic acid. The mtDNA levels in the cytosol were measured. The mtDNA from hepatocytes of mice was added to bone marrow-derived macrophages (BMDMs) in the presence of IRS (TLR9 antagonist). The expression of IL-33 in BMDMs was measured.
Levels of mtDNA were higher in NASH patients and MCD-fed mice. Treatment of hepatocytes with palmitic acid in vitro induced mtDNA release into cytosol, which was attenuated by mito-TEMPO or rapamycin, and aggravated by inhibition of autophagy. Treatment of BMDMs with mtDNA enhanced IL-33 expression, which was attenuated by knockdown of TLR9. Treatment of BMDMs with mtDNA enhanced lipopolysaccharide (LPS)-induced production of IL-1β and TNF-α, which was attenuated by pretreatment with soluble ST2.
mtDNA released from injured hepatocytes under lipid overload induced the upregulation of IL-33 expression in macrophages via TLR9, and enhanced LPS-induced inflammatory cytokine production.
在本研究中，我们提出脂毒性诱导肝细胞释放线粒体 DNA（mtDNA），进而上调巨噬细胞中 IL-33 的表达。
检测蛋氨酸和胆碱缺乏饮食（MCD）喂养的小鼠和 NASH 患者血浆中的 mtDNA 水平。培养的肝细胞先用 Mito-TEMPO 或雷帕霉素预处理，然后用棕榈酸刺激。测量细胞质中的 mtDNA 水平。在 IRS（TLR9 拮抗剂）存在的情况下，将来自小鼠肝细胞的 mtDNA 添加到骨髓来源的巨噬细胞（BMDM）中。测量 BMDM 中 IL-33 的表达。
NASH 患者和 MCD 喂养的小鼠 mtDNA 水平更高。体外用棕榈酸处理肝细胞诱导 mtDNA 释放到细胞质中，该过程被 mito-TEMPO 或雷帕霉素减弱，被自噬抑制加重。用 mtDNA 处理 BMDM 增强了 IL-33 的表达，该过程被 TLR9 的敲低减弱。用 mtDNA 处理 BMDM 增强了脂多糖（LPS）诱导的 IL-1β 和 TNF-α 的产生，该过程被可溶性 ST2 的预处理减弱。
脂质过载下受损肝细胞释放的 mtDNA 通过 TLR9 诱导巨噬细胞中 IL-33 的表达上调，并增强 LPS 诱导的炎症细胞因子产生。
