Background and objectives:Hepatic steatosis and inflammation are key characteristics of non-alcoholic fatty liver disease(NAFLD).However,whether and how hepatic steatosis and liver inflammation are differentially regu...Background and objectives:Hepatic steatosis and inflammation are key characteristics of non-alcoholic fatty liver disease(NAFLD).However,whether and how hepatic steatosis and liver inflammation are differentially regulated remains to be elucidated.Considering that disruption of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3(Pfkfb3/iPfk2)dissociates fat deposition and inflammation,the present study examined a role for Pfkfb3/iPfk2 in hematopoietic cells in regulating hepatic steatosis and inflammation in mice.Methods:Pfkfb3-disrupted(Pfkfb3^(+/-))mice and wild-type(WT)littermates were fed a high-fat diet(HFD)and examined for NAFLD phenotype.Also,bone marrow cells isolated from Pfkfb3^(+/-)mice andWT mice were differentiated into macrophages for analysis of macrophage activation status and for bone marrow transplantation(BMT)to generate chimeric(WT/BMT-Pfkfb3^(+/-))mice in which Pfkfb3 was disrupted only in hematopoietic cells and control chimeric(WT/BMT-WT)mice.The latter were also fed an HFD and examined for NAFLD phenotype.In vitro,hepatocytes were co-cultured with bone marrowderived macrophages and examined for hepatocyte fat deposition and proinflammatory responses.Results:After the feeding period,HFD-fed Pfkfb3^(+/-)mice displayed increased severity of liver inflammation in the absence of hepatic steatosis compared with HFD-fed WT mice.When inflammatory activation was analyzed,Pfkfb3^(+/-)macrophages revealed increased proinflammatory activation and decreased anti-proinflammatory activation.When NAFLD phenotype was analyzed in the chimeric mice,WT/BMT-Pfkfb3^(+/-) mice displayed increases in the severity of HFD-induced hepatic steatosis and inflammation compared with WT/BMT-WT mice.At the cellular level,hepatocytes co-cultured with Pfkfb3^(+/-) macrophages revealed increased fat deposition and proinflammatory responses compared with hepatocytes co-cultured with WT macrophages.Conclusions:Pfkfb3 disruption only in hematopoietic cells exacerbates HFD-induced hepatic steatosis and inflammation whereas the Pfkfb3/iPfk2 in nonhematopoietic cells appeared to be needed for HFD feeding to induce hepatic steatosis.As such,the Pfkfb3/iPfk2 plays a unique role in regulating NAFLD pathophysiology.展开更多
基金This work was supported in part by the Hickam Endowed Chair,Gastroenterology,Medicine,Indiana University and the Indiana University Health e Indiana University School of Medicine Strategic Research Initiative,the Research Career Scientist to Dr.Alpini from the United States Department of Veteran’s Affairs,Biomedical Laboratory Research and Development Service and National Institutes of Health(NIH)grants DK054811,DK110035,and DK076898 to Drs.G.Alpini and S.Glaser.In addition,this work was supported in whole or in part by grants from the American Diabetes Association(ADA)(1-10-BS-76 to C.Wu)the National Institutes of Health(DK095828 and DK124854 to C.Wu).
文摘Background and objectives:Hepatic steatosis and inflammation are key characteristics of non-alcoholic fatty liver disease(NAFLD).However,whether and how hepatic steatosis and liver inflammation are differentially regulated remains to be elucidated.Considering that disruption of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3(Pfkfb3/iPfk2)dissociates fat deposition and inflammation,the present study examined a role for Pfkfb3/iPfk2 in hematopoietic cells in regulating hepatic steatosis and inflammation in mice.Methods:Pfkfb3-disrupted(Pfkfb3^(+/-))mice and wild-type(WT)littermates were fed a high-fat diet(HFD)and examined for NAFLD phenotype.Also,bone marrow cells isolated from Pfkfb3^(+/-)mice andWT mice were differentiated into macrophages for analysis of macrophage activation status and for bone marrow transplantation(BMT)to generate chimeric(WT/BMT-Pfkfb3^(+/-))mice in which Pfkfb3 was disrupted only in hematopoietic cells and control chimeric(WT/BMT-WT)mice.The latter were also fed an HFD and examined for NAFLD phenotype.In vitro,hepatocytes were co-cultured with bone marrowderived macrophages and examined for hepatocyte fat deposition and proinflammatory responses.Results:After the feeding period,HFD-fed Pfkfb3^(+/-)mice displayed increased severity of liver inflammation in the absence of hepatic steatosis compared with HFD-fed WT mice.When inflammatory activation was analyzed,Pfkfb3^(+/-)macrophages revealed increased proinflammatory activation and decreased anti-proinflammatory activation.When NAFLD phenotype was analyzed in the chimeric mice,WT/BMT-Pfkfb3^(+/-) mice displayed increases in the severity of HFD-induced hepatic steatosis and inflammation compared with WT/BMT-WT mice.At the cellular level,hepatocytes co-cultured with Pfkfb3^(+/-) macrophages revealed increased fat deposition and proinflammatory responses compared with hepatocytes co-cultured with WT macrophages.Conclusions:Pfkfb3 disruption only in hematopoietic cells exacerbates HFD-induced hepatic steatosis and inflammation whereas the Pfkfb3/iPfk2 in nonhematopoietic cells appeared to be needed for HFD feeding to induce hepatic steatosis.As such,the Pfkfb3/iPfk2 plays a unique role in regulating NAFLD pathophysiology.
