Sun Zhen, Li Lihua, Yan Zhixin, Zhang Lili, Zang Guangyao, Qian Yongjiang, Wang Zhongqun
Department of Cardiology, Affiliated Hospital of Jiangsu University, Zhenjiang, China.
Department of Pathology, Affiliated Hospital of Jiangsu University, Zhenjiang, China.
Physiol Behav. 2022 May 15;249:113772. doi: 10.1016/j.physbeh.2022.113772. Epub 2022 Mar 2.
Circadian rhythm disorders are severe threats to human health. The negative impact of circadian rhythm disorders on tissues/organs has not been systematically analyzed. Therefore, there is an urgent need to evaluate the damage caused by circadian rhythm disorders and explore the possible mechanisms.
Six-week-old male mice were divided into the control (Con) group (normal circadian rhythm), L24 group (constant light), D12L12 group (weekly shift light/dark cycle), and D24 group (constant dark). Body weight was recorded every 10 days. Ninety days after model construction, the serum lipid and cytokine level, liver function, fat accumulation, carotid artery stenosis, and cardiomyopathological changes were detected in mice. Macrophages in the liver, subscapular fat, and heart tissues were labeled with immunofluorescence staining. Mouse peritoneal macrophages were then isolated. Inflammatory cytokine levels were measured in the macrophage supernatant. The ability of macrophages to form foam cells was also tested. The supernatant from macrophages in different groups was added to AML12 (hepatocytes), 3T3-L1 (preadipocytes), or HL-1 (cardiomyocytes). Effects of conditioned media on recipient cells were determined.
Body weight, serum lipids and cytokines, subscapular fat accumulation, liver enzymes, carotid artery stenosis, and myocardial fibrosis levels of the L24, D12L12, and D24 groups mice were significantly higher than those in the Con group. Macrophages were significantly increased in the liver, heart, and subscapular fat of mice with circadian rhythmdisorders. Cytokine secretion by peritoneal macrophages was enhanced in the L24, D12L12, and D24 groups. Under oxidized low density lipoprotein (oxLDL) stimulation, macrophages with circadian rhythm disorders are more likely to form foam cells. Conditioned media from the L24, D12L12, and D24 groups significantly promoted AML12 apoptosis and lipid intake, accelerated the adipogenic differentiation of 3T3-L1, and up-regulated collagen I in HL-1.
These findings reveal that macrophages are increased in the tissues/organs under circadian rhythm disorders, and these macrophages could aggravate obesity, promote liver disease, accelerate atherosclerosis, and increase myocardial fibrosis through the paracrine effect.
昼夜节律紊乱对人类健康构成严重威胁。昼夜节律紊乱对组织/器官的负面影响尚未得到系统分析。因此，迫切需要评估昼夜节律紊乱造成的损害并探索其可能的机制。
将6周龄雄性小鼠分为对照组（Con组，正常昼夜节律）、L24组（持续光照）、D12L12组（每周改变明暗周期）和D24组（持续黑暗）。每10天记录一次体重。模型构建90天后，检测小鼠的血脂和细胞因子水平、肝功能、脂肪堆积、颈动脉狭窄和心肌病理变化。用免疫荧光染色标记肝脏、肩胛下脂肪和心脏组织中的巨噬细胞。然后分离小鼠腹腔巨噬细胞。检测巨噬细胞上清液中的炎性细胞因子水平。还测试了巨噬细胞形成泡沫细胞的能力。将不同组巨噬细胞的上清液加入AML12细胞（肝细胞）、3T3-L1细胞（前脂肪细胞）或HL-1细胞（心肌细胞）中。测定条件培养基对受体细胞的影响。
L24组、D12L12组和D24组小鼠的体重、血脂和细胞因子、肩胛下脂肪堆积、肝酶、颈动脉狭窄和心肌纤维化水平均显著高于Con组。昼夜节律紊乱小鼠的肝脏、心脏和肩胛下脂肪中的巨噬细胞显著增加。L24组、D12L12组和D24组中腹腔巨噬细胞的细胞因子分泌增强。在氧化型低密度脂蛋白（oxLDL）刺激下，昼夜节律紊乱的巨噬细胞更易形成泡沫细胞。L24组、D12L12组和D24组的条件培养基显著促进AML12细胞凋亡和脂质摄取，加速3T3-L1细胞的成脂分化，并上调HL-1细胞中的I型胶原。
这些研究结果表明，昼夜节律紊乱时组织/器官中的巨噬细胞增多，这些巨噬细胞可通过旁分泌作用加重肥胖、促进肝脏疾病、加速动脉粥样硬化并增加心肌纤维化。
