Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing University, No. 321 Zhongshan Road, Nanjing, 210008, China.
Beijing Key Laboratory of Hypertension, Beijing Chaoyang Hospital, Heart Center, Capital Medical University, 8th Gongtinanlu Rd, Chaoyang District, Beijing, 100020, China.
Eur J Med Res. 2024 Apr 15;29(1):233. doi: 10.1186/s40001-024-01825-4.
Atrial fibrillation (AF) is associated with circulating inflammation. Short-chain fatty acids (SCFAs) derived from gut microbiota (GM) regulate leukocyte function and inhibit the release of inflammatory cytokines, which are partly mediated by the G-protein-coupled receptor 43 (GPR43) signaling. This study aimed to investigate the expression of GPR43/NOD-like receptors family pyrin domain containing 3 (NLRP3) in leukocytes and the interaction with intestinal SCFAs levels in AF patients.
Expressions of GPR43 and NLRP3 mRNA in peripheral blood leukocytes from 23 AF patients and 25 non-AF controls were detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Expressions of leukocyte GPR43 and NLRP3 protein were evaluated by western blot analysis. The levels of plasma IL-1β were measured by enzyme-linked immunosorbent assay (ELISA). The fecal SCFAs levels based on GC/MS metabolome of corresponding 21 controls and 14 AF patients were acquired from our published dataset. To evaluate the expression of NLRP3 and GPR43 and the release of IL-1β, human THP-1 cells were stimulated with or without SCFAs (acetate, propionate, and butyrate), lipopolysaccharide (LPS), and nigericin in vitro, respectively.
Compared to the controls, the mRNA expression in peripheral leukocytes was significantly reduced in AF patients (P = 0.011) coupled with the increase in downstream leukocyte NLRP3 mRNA expression (P = 0.007) and plasma IL-1β levels (P < 0.001), consistent with changes in GPR43 and NLRP3 protein expression. Furthermore, leukocyte GPR43 mRNA levels were positively correlated with fecal GM-derived acetic acid (P = 0.046) and negatively correlated with NLRP3 mRNA expression (P = 0.024). In contrast to the negative correlation between left atrial diameter (LAD) and GPR43 (P = 0.008), LAD was positively correlated with the leukocyte NLRP3 mRNA levels (P = 0.024). Subsequent mediation analysis showed that 68.88% of the total effect of intestinal acetic acid on AF might be mediated by leukocyte GPR43/NLRP3. The constructed GPR43-NLRP3 score might have a predictive potential for AF detection (AUC = 0.81, P < 0.001). Moreover, SCFAs treatment increased GPR43 expression and remarkably reduced LPS/nigericin-induced NLRP3 expression and IL-1β release in human THP-1 cells in vitro.
Disrupted interactions between GPR43 and NLRP3 expression in peripheral blood leukocytes, associated with reduced intestinal GM-derived SCFAs, especially acetic acid, may be involved in AF development and left atrial enlargement by enhancing circulating inflammation.
房颤（AF）与循环炎症有关。肠道微生物群（GM）衍生的短链脂肪酸（SCFAs）调节白细胞功能并抑制炎症细胞因子的释放，这部分是通过 G 蛋白偶联受体 43（GPR43）信号传导介导的。本研究旨在探讨 AF 患者白细胞中 GPR43/NOD 样受体家族富含吡啶结构域 3（NLRP3）的表达及其与肠道 SCFAs 水平的相互作用。
采用实时定量聚合酶链反应（qRT-PCR）检测 23 例 AF 患者和 25 例非 AF 对照者外周血白细胞中 GPR43 和 NLRP3 mRNA 的表达。采用 Western blot 分析白细胞 GPR43 和 NLRP3 蛋白的表达。采用酶联免疫吸附试验（ELISA）测定血浆 IL-1β 水平。从我们发表的数据集获得了相应的 21 例对照者和 14 例 AF 患者的粪便 SCFAs 水平基于 GC/MS 代谢组学。为了评估 NLRP3 和 GPR43 的表达和 IL-1β 的释放，分别用 SCFAs（乙酸盐、丙酸盐和丁酸盐）、脂多糖（LPS）和 Nigericin 体外刺激人 THP-1 细胞。
与对照组相比，AF 患者外周血白细胞中的 mRNA 表达明显降低（P=0.011），下游白细胞 NLRP3 mRNA 表达（P=0.007）和血浆 IL-1β 水平（P<0.001）增加，与 GPR43 和 NLRP3 蛋白表达的变化一致。此外，白细胞 GPR43 mRNA 水平与粪便 GM 衍生的乙酸呈正相关（P=0.046），与 NLRP3 mRNA 表达呈负相关（P=0.024）。与左心房直径（LAD）与 GPR43 的负相关（P=0.008）相反，LAD 与白细胞 NLRP3 mRNA 水平呈正相关（P=0.024）。随后的中介分析表明，肠道乙酸对 AF 的总效应的 68.88%可能通过白细胞 GPR43/NLRP3 介导。构建的 GPR43-NLRP3 评分可能具有预测 AF 检测的潜力（AUC=0.81，P<0.001）。此外，SCFAs 处理可增加人 THP-1 细胞中 GPR43 的表达，并显著降低 LPS/Nigericin 诱导的 NLRP3 表达和 IL-1β 释放。
外周血白细胞中 GPR43 和 NLRP3 表达的相互作用紊乱，与肠道 GM 衍生的 SCFAs 减少有关，特别是乙酸，可能通过增强循环炎症参与 AF 的发生和左心房扩大。
