Peroxisome Proliferator-Activated Receptor-γ Modulates the Response of Macrophages to Lipopolysaccharide and Glucocorticoids.
Peroxisome Proliferator-Activated Receptor-γ Modulates the Response of Macrophages to Lipopolysaccharide and Glucocorticoids.
复制标题
DOI：
10.3389/fimmu.2018.00893
复制
发表时间：
2018
影响因子：
7.3
通讯作者：
Barczyk-Kahlert K
中科院分区：
文献类型：
--
作者：
Heming M;Gran S;Jauch SL;Fischer-Riepe L;Russo A;Klotz L;Hermann S;Schäfers M;Roth J;Barczyk-Kahlert K
虽然糖皮质激素(GC)是最常用的免疫抑制药物，但其作用仍不清楚。在我们以前的研究中，我们已经表明，GC处理单核细胞并不会导致单核细胞效应器功能的整体抑制，而是诱导特定抗炎表型的分化。近年来，过氧化物酶体增殖物激活受体-γ的抗炎作用已被广泛研究。然而，到目前为止，GC处理与巨噬细胞中PPAR-γ表达之间的关系还没有得到研究。使用PPAR-γ缺陷小鼠的研究经常提供有争议的结果。一个潜在的原因是使用了原代细胞，这通常代表着不同的群体，背负着副作用，并受到旁观者细胞的影响。为了克服这一限制，我们在本研究中建立了Ppargfl/fl和LysM-Cre Ppargfl/fl小鼠的ER-Hoxb8永生化骨髓来源的巨噬细胞。与初级巨噬细胞不同，ER-Hoxb8系统允许产生同质的和定义明确的静息巨噬细胞群。我们可以证明，PPAR-γ的缺失导致了单核细胞向巨噬细胞分化的动力学延迟，如F4/80降低，但在分化早期Ly6C的表达增加。正如预期的那样，与PPAR-γWT细胞相比，PPAR-α缺陷的巨噬细胞在长期的脂多糖刺激下表现出更多的促炎表型，其特征是促炎细胞因子TNF-β、IL-1-γ、IL-6、IL-12的产生增加，而抗炎细胞因子IL-10的产生减少。此外，PPAR-γ缺陷的巨噬细胞显示吞噬功能受损。巨噬细胞经GC处理后，PPAR-γ表达上调。然而，在GC诱导的细胞因子抑制方面，两种细胞类型之间没有差异，暗示了PPAR-γ非依赖的机制。有趣的是，GC处理只导致PPAR-γ缺陷的巨噬细胞的体外迁移增加。进行一项新开发的体内细胞跟踪实验，我们可以证实GC诱导PPAR-γKO的募集增加，但不能诱导PPAR-γWT巨噬细胞到炎症部位。我们的发现提示了PPAR-γ在GC诱导的巨噬细胞迁移中的特殊作用。综上所述，我们可以证明PPAR-γ具有抗炎活性和形成巨噬细胞的功能。此外，我们确定了GC和PPAR-γ之间的分子联系，并首次表明PPAR-γ调控GC诱导的巨噬细胞的迁移。
Although glucocorticoids (GC) represent the most frequently used immunosuppressive drugs, their effects are still not well understood. In our previous studies, we have shown that treatment of monocytes with GC does not cause a global suppression of monocytic effector functions, but rather induces differentiation of a specific anti-inflammatory phenotype. The anti-inflammatory role of peroxisome proliferator-activated receptor (PPAR)-γ has been extensively studied during recent years. However, a relationship between GC treatment and PPAR-γ expression in macrophages has not been investigated so far. Studies using PPAR-γ-deficient mice have frequently provided controversial results. A potential reason is the use of primary cells, which commonly represent inhomogeneous populations burdened with side effects and influenced by bystander cells. To overcome this constraint, we established ER-Hoxb8-immortalized bone marrow-derived macrophages from Ppargfl/fl and LysM-Cre Ppargfl/fl mice in this study. In contrast to primary macrophages, the ER-Hoxb8 system allows the generation of a homogeneous and well-defined population of resting macrophages. We could show that the loss of PPAR-γ resulted in delayed kinetic of differentiation of monocytes into macrophages as assessed by reduced F4/80, but increased Ly6C expression in early phases of differentiation. As expected, PPAR-γ-deficient macrophages displayed an increased pro-inflammatory phenotype upon long-term LPS stimulation characterized by an elevated production of pro-inflammatory cytokines TNF-α, IL1-β, IL-6, IL-12 and a reduced production of anti-inflammatory cytokine IL-10 compared to PPAR-γ WT cells. Moreover, PPAR-γ-deficient macrophages showed impaired phagocytosis. GC treatment of macrophages led to the upregulation of PPAR-γ expression. However, there were no differences in GC-induced suppression of cytokines between both cell types, implicating a PPAR-γ-independent mechanism. Intriguingly, GC treatment resulted in an increased in vitro migration only in PPAR-γ-deficient macrophages. Performing a newly developed in vivo cell-tracking experiment, we could confirm that GC induces an increased recruitment of PPAR-γ KO, but not PPAR-γ WT macrophages to the site of inflammation. Our findings suggest a specific effect of PPAR-γ on GC-induced migration in macrophages. In conclusion, we could demonstrate that PPAR-γ exerts anti-inflammatory activities and shapes macrophage functions. Moreover, we identified a molecular link between GC and PPAR-γ and could show for the first time that PPAR-γ modulates GC-induced migration in macrophages.