Mulder Petra, van den Hoek Anita M, Kleemann Robert
Department of Metabolic Health Research, Netherlands Organization for Applied Scientific Research (TNO), Zernikedreef 9, Leiden, The Netherlands.
Department of Vascular Surgery, Leiden University Medical Center, Leiden, The Netherlands.
PLoS One. 2017 Jan 11;12(1):e0169740. doi: 10.1371/journal.pone.0169740. eCollection 2017.
Obese patients with chronic inflammation in white adipose tissue (WAT) have an increased risk of developing non-alcoholic steatohepatitis (NASH). The C-C chemokine receptor-2 (CCR2) has a crucial role in the recruitment of immune cells to WAT and liver, thereby promoting the inflammatory component of the disease. Herein, we examined whether intervention with propagermanium, an inhibitor of CCR2, would attenuate tissue inflammation and NASH development.
Male C57BL/6J mice received a high-fat diet (HFD) for 0, 6, 12 and 24 weeks to characterize the development of early disease symptoms of NASH, i.e. insulin resistance and WAT inflammation (by hyperinsulinemic-euglycemic clamp and histology, respectively) and to define the optimal time point for intervention. In a separate study, mice were pretreated with HFD followed by propagermanium treatment (0.05% w/w) after 6 weeks (early intervention) or 12 weeks (late intervention). NASH was analyzed after 24 weeks of diet feeding.
Insulin resistance in WAT developed after 6 weeks of HFD, which was paralleled by modest WAT inflammation. Insulin resistance and inflammation in WAT intensified after 12 weeks of HFD, and preceded NASH development. The subsequent CCR2 intervention experiment showed that early, but not late, propagermanium treatment attenuated insulin resistance. Only the early treatment significantly decreased Mcp-1 and CD11c gene expression in WAT, indicating reduced WAT inflammation. Histopathological analysis of liver demonstrated that propagermanium treatment decreased macrovesicular steatosis and tended to reduce lobular inflammation, with more pronounced effects in the early intervention group. Propagermanium improved the ratio between pro-inflammatory (M1) and anti-inflammatory (M2) macrophages, quantified by CD11c and Arginase-1 gene expression in both intervention groups.
Overall, early propagermanium administration was more effective to improve insulin resistance, WAT inflammation and NASH compared to late intervention. These data suggest that therapeutic interventions for NASH directed at the MCP-1/CCR2 pathway should be initiated early.
白色脂肪组织（WAT）存在慢性炎症的肥胖患者发生非酒精性脂肪性肝炎（NASH）的风险增加。C-C趋化因子受体2（CCR2）在免疫细胞募集至WAT和肝脏的过程中起关键作用，从而促进该疾病的炎症成分。在此，我们研究了使用CCR2抑制剂丙帕锗进行干预是否会减轻组织炎症和NASH的发展。
雄性C57BL/6J小鼠分别接受0、6、12和24周的高脂饮食（HFD），以表征NASH早期疾病症状的发展，即胰岛素抵抗和WAT炎症（分别通过高胰岛素-正糖钳夹试验和组织学检查），并确定干预的最佳时间点。在另一项研究中，小鼠先接受HFD预处理，然后在6周（早期干预）或12周（晚期干预）后给予丙帕锗治疗（0.05% w/w）。饮食喂养24周后分析NASH情况。
HFD喂养6周后WAT出现胰岛素抵抗，同时伴有轻度WAT炎症。HFD喂养12周后WAT的胰岛素抵抗和炎症加剧，并先于NASH的发展。随后的CCR2干预实验表明，早期而非晚期给予丙帕锗治疗可减轻胰岛素抵抗。只有早期治疗显著降低了WAT中Mcp-1和CD11c基因的表达，表明WAT炎症减轻。肝脏组织病理学分析表明，丙帕锗治疗可减少大泡性脂肪变性，并倾向于减轻小叶炎症，在早期干预组中效果更明显。通过两个干预组中CD11c和精氨酸酶-1基因表达定量分析，丙帕锗改善了促炎（M1）和抗炎（M2）巨噬细胞的比例。
总体而言，与晚期干预相比，早期给予丙帕锗在改善胰岛素抵抗、WAT炎症和NASH方面更有效。这些数据表明，针对MCP-1/CCR2途径的NASH治疗干预应尽早开始。
