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 and WT 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 marrow-derived macrophages and examined for hepatocyte fat deposition and proinflammatory responses.Results:After the feeding period,HFD-fed Pfkfb3+/-mice displayed increased severity of liver inflam-mation 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.