GM-CSF induces proinflammatory macrophages, but the underlying mechanisms have not been studied thus far. In this study, we investigated the mechanisms of how GM-CSF induces inflammatory macrophages. First, we observed that GM-CSF increased the extent of LPS-induced acute glycolysis in murine bone marrow-derived macrophages. This directly correlates with an inflammatory phenotype because glycolysis inhibition by 2-deoxyglucose abolished GM-CSF-mediated increase of TNF-α, IL-1β, IL-6, and IL-12p70 synthesis upon LPS stimulation. Increased glycolytic capacity is due to de novo synthesis of glucose transporter (GLUT)-1, -3, and -4, as well as c-myc. Meanwhile, GM-CSF increased 3-hydroxy-3-methyl-glutaryl-CoA reductase, which is the rate-limiting enzyme of the mevalonate pathway. Inhibition of acute glycolysis or 3-hydroxy-3-methyl-glutaryl-CoA reductase abrogated the inflammatory effects of GM-CSF priming in macrophages. Finally, mice with inflamed colons exposed to dextran sodium sulfate containing GLUT-1 macrophages led to massive uptake of [F]-fluorodeoxyglucose, but GM-CSF neutralization reduced the positron-emission tomography signal in the intestine and also decreased GLUT-1 expression in colonic macrophages. Collectively, our results reveal glycolysis and lipid metabolism created by GM-CSF as the underlying metabolic constructs for the function of inflammatory macrophages.

Granulocyte-macrophage colony stimulating factor (GM-CSF) has a role in inducing emergency hematopoiesis upon exposure to inflammatory stimuli. Although GM-CSF generated murine bone marrow derived cells have been widely used as macrophages or dendritic cells in research, the exact characteristics of each cell population have not yet been defined. Here we discriminated GM-CSF grown bone marrow derived macrophages (GM-BMMs) from dendritic cells (GM-BMDCs) in several criteria. After C57BL/6J mice bone marrow cell culture for 7 days with GM-CSF supplementation, two main populations were observed in the attached cells based on MHCII and F4/80 marker expressions. GM-BMMs had MHCIIlowF4/80high as well as CD11c+CD11bhighCD80−CD64+MerTK+ phenotypes. In contrast, GM-BMDCs had MHCIIhighF4/80low and CD11chighCD8α− CD11b+CD80+CD64−MerTKlow phenotypes. Interestingly, the GM-BMM population increased but GM-BMDCs decreased in a GM-CSF dose-dependent manner. Functionally, GM-BMMs showed extremely high phagocytic abilities and produced higher IL-10 upon LPS stimulation. GM-BMDCs, however, could not phagocytose as well, but were efficient at producing TNFα, IL-1β, IL-12p70 and IL-6 as well as inducing T cell proliferation. Finally, whole transcriptome analysis revealed that GM-BMMs and GM-BMDCs are overlap with in vivo resident macrophages and dendritic cells, respectively. Taken together, our study shows the heterogeneicity of GM-CSF derived cell populations, and specifically characterizes GM-CSF derived macrophages compared to dendritic cells.

Macrophages have important functions in tissue homeostasis, but the exact mechanisms regarding wide spectrum of macrophage phenotype remain unresolved. In this study, we report that mouse bone marrow derived naïve macrophages produce prostaglandin E 2 (PGE 2 ) endogenously, resulting in anti-inflammatory gene expression upon differentiation induced by macrophage colony stimulating factor (M-CSF). Cyclooxygenase (COX) inhibition by indomethacin reduced endogenous PGE 2 production of macrophages and subsequently reduced arg1, IL10 and Mrc1, YmI and FizzI gene expressions. Of note, PGE 2 phosphorylates CREB via EP2 and EP4 receptor ligation, thereby transcriptionally increasing C/EBP-β expression in BALB/c bone marrow derived macrophages. Activated CREB directly binds to the CREB-responsive element of the C/EBP-β promoter, such that PGE 2 ultimately reinforces arg1, IL10 and Mrc1 gene expression. Cyclic AMP activator forskolin also phosphorylated CREB and induced the C/EBP-β cascade, but this was completely blocked by the PKA inhibitor, H89. Consequently, M-CSF grown macrophages inhibited T-cell proliferation but the inhibition ability was reduced when the COX is inhibited by indomethacin or macrophage C/EBP-β expression was decreased by siRNA transduction. Our results collectively describe the molecular basis for homeostatic macrophage differentiation by endogenous PGE 2 .Keywords: C/EBP-β r CREB r Homeostasis r Macrophages r Prostaglandin E 2 Additional supporting information may be found in the online version of this article at the publisher's web-site Macrophages play a pivotal role in the innate immune system by sensing and killing microbes. Moreover, macrophages have important roles in almost every aspect of an organism's biology including development, tissue repair, and homeostasis [1]. TisCorrespondence: Prof. Seung Hyeok Seok e-mail: lamseok@snu.ac.kr sue macrophages are highly heterogenous in terms of their functions and phenotypes as a consequence of adapting to different tissue environments, where they monitor the local environment and maintain homeostasis [2]. * Both authors contributed equally. Eur. J. Immunol. 2015Immunol. . 45: 2661Immunol. -2671 Historically, all tissue macrophages were considered to be derived from circulating monocytes that originate from hematopoietic stem cells [3]. Recent studies revealed that a substantial portion of tissue macrophages arise from the yolk sac during embryogenesis, and are maintained by local proliferation [4]. Regardless of their origin, macrophages acquire unique characteristics depending on their tissue-specific microenvironment [5]. Macrophage colony-stimulating factor (M-CSF) generally differentiates macrophages with homeostatic function in vivo [6]. Likewise, tissue-specific factors such as GM-CSF in lung alveoli and fat-cell-derived adipokines in adipose tissue also affect macrophage phenotypes. Infections greatly change local tissue microenvironments, particularly when blood-derived monocytes infiltrate infected areas and differentiate into macrophag...

BackgroundFor proper recovery from craniofacial fracture, it is necessary to establish guidelines based on trends. This study aimed to analyze the patterns and causes of craniofacial fractures.MethodsThis retrospective study analyzed patients who underwent surgery for craniofacial fractures between 2010 and 2017 at a single center. Several parameters, including time of injury, region and cause of fracture, alcohol intoxication, time from injury to surgery, hospitalization period, and postoperative complications, were evaluated.ResultsThis study analyzed 2708 fracture lesions of 2076 patients, among whom males aged 10 to 39 years were the most numerous. The number of patients was significantly higher in the middle of a month. The most common fractures were a nasal bone fracture. The most common causes of fracture were ground accidents and personal assault, which tended to frequently cause more nasal bone fracture than other fractures. Traffic accidents and high falls tended to cause zygomatic arch and maxillary wall fractures more frequently. Postoperative complications—observed in 126 patients—had a significant relationship with the end of a month, mandible or panfacial fracture, and traffic accidents.ConclusionsThe present findings on long-term craniofacial fracture trends should be considered by clinicians dealing with fractures and could be useful for policy decisions.Electronic supplementary materialThe online version of this article (10.1186/s40902-018-0168-y) contains supplementary material, which is available to authorized users.