ABSTRACT

Maladaptive inflammatory and immune responses are responsible for intestinal barrier integrity and function dysregulation. Proline/serine-rich coiled-coil protein 1 (PSRC1) critically contributes to the immune system, but direct data on the gut microbiota and the microbial metabolite trimethylamine N-oxide (TMAO) are lacking. Here, we investigated the impact of PSRC1 deletion on TMAO generation and atherosclerosis. We first found that PSRC1 deletion in apoE^−/− mice accelerated atherosclerotic plaque formation, and then the gut microbiota and metabolites were detected using metagenomics and untargeted metabolomics. Our results showed that PSRC1 deficiency enriched trimethylamine (TMA)-producing bacteria and functional potential for TMA synthesis and accordingly enhanced plasma betaine and TMAO production. Furthermore, PSRC1 deficiency resulted in a proinflammatory colonic phenotype that was significantly associated with the dysregulated bacteria. Unexpectedly, hepatic RNA-seq indicated upregulated flavin monooxygenase 3 (FMO3) expression following PSRC1 knockout. Mechanistically, PSRC1 overexpression inhibited FMO3 expression in vitro, while an ERα inhibitor rescued the downregulation. Consistently, PSRC1-knockout mice exhibited higher plasma TMAO levels with a choline-supplemented diet, which was gut microbiota dependent, as evidenced by antibiotic treatment. To investigate the role of dysbiosis induced by PSRC1 deletion in atherogenesis, apoE^−/− mice were transplanted with the fecal microbiota from either apoE^−/− or PSRC1^−/−apoE^−/− donor mice. Mice that received PSRC1-knockout mouse feces showed an elevation in TMAO levels, as well as plaque lipid deposition and macrophage accumulation, which were accompanied by increased plasma lipid levels and impaired hepatic cholesterol transport. Overall, we identified PSRC1 as an atherosclerosis-protective factor, at least in part, attributable to its regulation of TMAO generation via a multistep pathway. Thus, PSRC1 holds great potential for manipulating the gut microbiome and alleviating atherosclerosis.

摘要

适应不良的炎症和免疫反应是导致肠道屏障完整性和功能失调的原因。富含脯氨酸/丝氨酸的卷曲螺旋蛋白 1 (PSRC1) 对免疫系统有重要贡献，但缺乏关于肠道微生物群和微生物代谢物三甲胺 N-氧化物 (TMAO) 的直接数据。在这里，我们研究了 PSRC1 缺失对 TMAO 生成和动脉粥样硬化的影响。我们首先发现 apoE 中的 PSRC1 缺失^-/-小鼠加速动脉粥样硬化斑块形成，然后使用宏基因组学和非靶向代谢组学检测肠道微生物群和代谢物。我们的研究结果表明，PSRC1 缺陷会丰富产生三甲胺 (TMA) 的细菌和 TMA 合成的功能潜力，并相应地增强血浆甜菜碱和 TMAO 的产生。此外，PSRC1 缺陷导致促炎性结肠表型，该表型与失调的细菌显着相关。出乎意料的是，肝 RNA-seq 表明在 PSRC1 敲除后黄素单加氧酶 3 (FMO3) 表达上调。从机制上讲，PSRC1 过表达在体外抑制了 FMO3 的表达, 而 ERα 抑制剂挽救了下调。一致地，PSRC1 基因敲除小鼠在补充胆碱的饮食中表现出更高的血浆 TMAO 水平，这是肠道微生物群依赖性的，抗生素治疗证明了这一点。为了研究 PSRC1 缺失诱导的生态失调在动脉粥样硬化形成中的作用，将来自 apoE ^-/-或 PSRC1 ^-/- apoE ^-/-的粪便微生物群移植到apoE ^-/-小鼠中供体小鼠。接受 PSRC1 敲除小鼠粪便的小鼠表现出 TMAO 水平升高，斑块脂质沉积和巨噬细胞积聚，并伴有血浆脂质水平升高和肝脏胆固醇转运受损。总的来说，我们将 PSRC1 确定为动脉粥样硬化保护因子，至少部分归因于它通过多步途径调节 TMAO 的产生。因此，PSRC1 在调控肠道微生物组和缓解动脉粥样硬化方面具有巨大潜力。