PPAR-γ拮抗剂GW9662可诱导M2c样细胞分化并上调MerTK/Gas6轴：PPAR-γ在人类巨噬细胞极化中的关键作用
The PPAR-γ antagonist GW9662 elicits differentiation of M2c-like cells and upregulation of the MerTK/Gas6 axis: a key role for PPAR-γ in human macrophage polarization.
作者信息
Zizzo Gaetano, Cohen Philip L
机构信息
Temple Autoimmunity Center, Temple University, 3500 N. Broad Street, 19140 Philadelphia, PA USA ; Department of Medicine, Section of Rheumatology, Temple University, 3322 N. Broad Street, 19140 Philadelphia, PA USA.
出版信息
J Inflamm (Lond). 2015 May 3;12:36. doi: 10.1186/s12950-015-0081-4. eCollection 2015.
BACKGROUND
The nuclear receptors PPAR-γ and LXRs regulate macrophage lipid metabolism and macrophage mediated inflammation. We examined the influence of these molecules on macrophage alternative activation, with particular focus on differentiation of "M2c" anti-inflammatory cells.
METHODS
We cultured human monocytes in M0, M1, M2a or M2c macrophage differentiating conditions, in the presence or absence of PPAR-γ and LXR ligands. Flow cytometry was used to analyze membrane expression of phenotypic markers. Basal and LPS-stimulated production of soluble mediators was measured by ELISA. Efferocytosis assays were performed by coincubating monocytes/macrophages with apoptotic neutrophils.
RESULTS
We found that PPAR-γ inhibition, using the PPAR-γ antagonist GW9662, elicits differentiation of M2c-like (CD206(+) CD163(+) CD16(+)) cells and upregulation of the MerTK/Gas6 axis. Exposure of differentiating macrophages to IFN-γ, GM-CSF or LPS (M1 conditions), however, hampers GW9662 induction of MerTK and Gas6. When macrophages are differentiated with IL-4 (M2a conditions), addition of GW9662 results into an M2a (CD206(+) CD209(+) CD163(-) MerTK(-)) to M2c (CD206(high) CD209(-) CD163(+) MerTK(+)) polarization shift. Conversely, in the presence of dexamethasone (M2c conditions), the PPAR-γ agonist rosiglitazone attenuates CD163 and MerTK upregulation. The LXR agonist T0901317 induces MerTK independently of M2c polarization; indeed, CD206, CD163 and CD16 are downregulated. GW9662-differentiated M2c-like cells secrete high levels of Gas6 and low amounts of TNF-α and IL-10, mimicking dexamethasone effects in vitro. However, unlike conventional M2c cells, GW9662-differentiated cells do not show enhanced efferocytic ability.
CONCLUSIONS
Our results provide new insights into the role of PPAR-γ and LXR receptors in human macrophage activation and reveal the existence of different patterns regulating MerTK expression. Unexpectedly, PPAR-γ appears to negatively control the expansion of a discrete subset of M2c-like anti-inflammatory macrophages.
背景
核受体PPAR-γ和肝X受体（LXRs）调节巨噬细胞脂质代谢和巨噬细胞介导的炎症反应。我们研究了这些分子对巨噬细胞替代性活化的影响，尤其关注“M2c”抗炎细胞的分化。
方法
我们在有或无PPAR-γ和LXR配体的情况下，于M0、M1、M2a或M2c巨噬细胞分化条件下培养人单核细胞。采用流式细胞术分析表型标志物的膜表达情况。通过酶联免疫吸附测定法（ELISA）检测基础状态和脂多糖（LPS）刺激下可溶性介质的产生。通过将单核细胞/巨噬细胞与凋亡中性粒细胞共同孵育进行噬菌作用分析。
结果
我们发现，使用PPAR-γ拮抗剂GW9662抑制PPAR-γ可诱导M2c样（CD206(+) CD163(+) CD16(+)）细胞的分化，并上调MerTK/Gas6轴。然而，将分化中的巨噬细胞暴露于干扰素-γ（IFN-γ）、粒细胞-巨噬细胞集落刺激因子（GM-CSF）或LPS（M1条件）下会阻碍GW9662对MerTK和Gas6的诱导。当巨噬细胞在白细胞介素-4（IL-4）作用下分化（M2a条件）时，添加GW9662会导致从M2a（CD206(+) CD209(+) CD163(-) MerTK(-)）向M2c（CD206(高) CD209(-) CD163(+) MerTK(+)）的极化转变。相反，在存在地塞米松的情况下（M2c条件），PPAR-γ激动剂罗格列酮会减弱CD163和MerTK的上调。LXR激动剂T0901317独立于M2c极化诱导MerTK；实际上，CD206、CD163和CD16会下调。GW9662分化的M2c样细胞分泌高水平的Gas6和低水平的肿瘤坏死因子-α（TNF-α）及白细胞介素-10（IL-10），在体外模拟了地塞米松的作用。然而，与传统的M2c细胞不同，GW9662分化的细胞未显示出增强的噬菌能力。
结论
我们的结果为PPAR-γ和LXR受体在人类巨噬细胞活化中的作用提供了新的见解，并揭示了调节MerTK表达的不同模式的存在。出乎意料的是，PPAR-γ似乎对离散的M2c样抗炎巨噬细胞亚群的扩增起负向控制作用。
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