Xu Menghui, Zhuo Ruhao, Tao Shengxiang, Liang Yaxu, Liu Chunru, Liu Qingyang, Wang Tian, Zhong Xiang
College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
Antioxidants (Basel). 2022 Sep 30;11(10):1954. doi: 10.3390/antiox11101954.
N-methyladenosine (mA) is the most abundant internal modification that widely participates in various immune and inflammatory responses; however, its regulatory mechanisms in the inflammation of liver induced by lipopolysaccharide in piglets remain largely unknown. In the present study, piglets were intraperitoneally injected with 80 μg/kg LPS or an equal dose of sterile saline. Results indicated that LPS administration increased activities of serum alanine aminotransferase (ALT), induced M1 macrophage polarization and promoted secretion of inflammatory cytokines, and finally led to hepatic lesions in piglets. The NOD1/NF-κB signaling pathway was activated in the livers of the LPS group. Moreover, the total mA level was significantly elevated after LPS treatment. MeRIP-seq showed that 1166 and 1344 transcripts contained mA methylation in control and LPS groups, respectively. The mA methylation sites of these transcripts mainly distributes in the 5' untranslated region (5'UTR), the coding sequence (CDS), and the 3' untranslated region (3'UTR). Interestingly, these genes were mostly enriched in the NF-κB signaling pathway, and LPS treatment significantly changed the mA modification in NOD1, RIPK2, NFKBIA, NFKBIB, and TNFAIP3 mRNAs. In addition, knockdown of METTL3 or overexpression of FTO both changed gene levels in the NOD1/NF-κB pathway, suggesting that activation of this pathway was regulated by mA RNA methylation. Moreover, the alteration of mA RNA methylation profile may be associated with the increase of reactive oxygen species (ROS), HIF-1α, and MAT2A. In conclusion, LPS activated the NOD1/NF-κB pathway at post-transcriptional regulation through changing mA RNA methylation, and then promoted the overproduction of proinflammatory cytokines, ultimately resulting in liver inflammation and damage.
N-甲基腺苷（mA）是最丰富的内部修饰，广泛参与各种免疫和炎症反应；然而，其在仔猪脂多糖诱导的肝脏炎症中的调节机制仍 largely 未知。在本研究中，给仔猪腹腔注射 80 μg/kg LPS 或等量的无菌生理盐水。结果表明，给予 LPS 增加了血清丙氨酸转氨酶（ALT）的活性，诱导了 M1 巨噬细胞极化并促进了炎症细胞因子的分泌，最终导致仔猪肝脏损伤。LPS 组肝脏中 NOD1/NF-κB 信号通路被激活。此外，LPS 处理后总 mA 水平显著升高。MeRIP-seq 显示，对照组和 LPS 组分别有 1166 和 1344 个转录本含有 mA 甲基化。这些转录本的 mA 甲基化位点主要分布在 5'非翻译区（5'UTR）、编码序列（CDS）和 3'非翻译区（3'UTR）。有趣的是，这些基因大多富集在 NF-κB 信号通路中，LPS 处理显著改变了 NOD1、RIPK2、NFKBIA、NFKBIB 和 TNFAIP3 mRNA 中的 mA 修饰。此外，敲低 METTL3 或过表达 FTO 均改变了 NOD1/NF-κB 通路中的基因水平，表明该通路的激活受 mA RNA 甲基化调节。此外，mA RNA 甲基化谱的改变可能与活性氧（ROS）、HIF-1α 和 MAT2A 的增加有关。总之，LPS 通过改变 mA RNA 甲基化在转录后调控中激活了 NOD1/NF-κB 通路，进而促进促炎细胞因子的过量产生，最终导致肝脏炎症和损伤。
