Background

Accumulating evidence suggests a regulatory role of Wnt proteins in innate immune responses. However, the effects of Wnt3a signaling on TLR4-mediated inflammatory responses are controversial and the signaling crosstalk between TLR4 and Wnt3a remains uncertain.

Methods

Gain- and Loss- of function approaches were utilized to determine the function of Wnt3a signaling in TLR4-mediated inflammatory responses. Cytokine production at protein and mRNA levels and phosphorylation of signaling molecules were measured by ELISA, qRT-PCR, and Western Blot, respectively. Endotoxemia mouse model was employed to assess the effect of Wnt3a on systemic inflammatory cytokine levels and neutrophil infiltration.

Results

LPS stimulation leads to an increase of Wnt3a expression and its downstream molecule, Dvl3, in primary monocytes. Inhibition or silence of Wnt3a or Dvl3 significantly increases the production of pro-inflammatory cytokines (IL-12, IL-6, TNFα), robustly reduces β-catenin accumulation, and enhances the phosphorylation of NF-κB P65 and its DNA binding activity. These results were confirmed by multiple gain- and loss- of function approaches including specific siRNA and ectopic expression of Dvl3, GSK3β, and β-catenin in monocytes. Moreover, in vivo relevance was established in a murine endotoxin model, in which Wnt3a inhibition enhances the inflammatory responses by augmenting the systemic pro-inflammatory cytokine levels and neutrophil infiltration.

Conclusions

TLR4 activation promotes Wnt3a-Dvl3 signaling, which acts as rheostats to restrain the intensity of inflammation through regulating GSK3β-β-catenin signaling and NF-κB activity.

General significance

Wnt3a-Dvl3-β-catenin signaling axis could be a potential interventional target for manipulating the direction and intensity of inflammatory responses.

中文翻译：

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TLR4 诱导的 Wnt3a-Dvl3 通过 GSK3β/β-catenin 信号传导抑制炎症强度并防止内毒素驱动的器官衰竭

背景

越来越多的证据表明 Wnt 蛋白在先天免疫反应中发挥调节作用。然而，Wnt3a 信号传导对 TLR4 介导的炎症反应的影响存在争议，并且 TLR4 和 Wnt3a 之间的信号传导串扰仍不确定。

方法

利用功能获得和丧失方法来确定 Wnt3a 信号在 TLR4 介导的炎症反应中的功能。分别通过 ELISA、qRT-PCR 和 Western Blot 测量蛋白质和 mRNA 水平的细胞因子产生以及信号分子的磷酸化。采用内毒素血症小鼠模型来评估 Wnt3a 对全身炎症细胞因子水平和中性粒细胞浸润的影响。

结果

LPS 刺激导致原代单核细胞中 Wnt3a 及其下游分子 Dvl3 表达增加。抑制或沉默 Wnt3a 或 Dvl3 可显着增加促炎细胞因子（IL-12、IL-6、TNFα）的产生，显着减少 β-catenin 积累，并增强 NF-κB P65 的磷酸化及其 DNA 结合活性。这些结果通过多种功能获得和丧失方法得到证实，包括特异性 siRNA 和单核细胞中 Dvl3、GSK3β 和 β-连环蛋白的异位表达。此外，在小鼠内毒素模型中建立了体内相关性，其中 Wnt3a 抑制通过增加全身促炎细胞因子水平和中性粒细胞浸润来增强炎症反应。

结论

TLR4 激活促进 Wnt3a-Dvl3 信号传导，该信号传导充当变阻器，通过调节 GSK3β-β-catenin 信号传导和 NF-κB 活性来抑制炎症强度。

一般意义

Wnt3a-Dvl3-β-连环蛋白信号轴可能是操纵炎症反应方向和强度的潜在干预靶点。