ABSTRACT

The current level of knowledge on transcriptome responses triggered by endotoxins and glucocorticoids in immune cells in pigs is limited. Therefore, in the present study, we treated porcine peripheral blood mononuclear cells (PBMCs) with lipopolysaccharide (LPS) and dexamethasone (DEX) separately or combined for 2 hours. The resultant transcriptional responses were examined by mRNA sequencing. We found that the LPS treatment triggered pronounced inflammatory responses as evidenced by upregulation of pro-inflammatory cytokines, chemokines, and related signaling pathways like NF-κB. Concurrently, a series of downregulated pro-inflammatory and upregulated anti-inflammatory molecules were identified. These are involved in the inhibition of TLR, NF-κB, and MAPK cascades and activation of signaling mediated by Tregs and STAT3, respectively. These findings suggested that LPS initiated also an anti-inflammatory process to prevent an overwhelming inflammatory response. The transcriptome responses further revealed substantial crosstalk of immune responses and glucocorticoid receptor (GR) signaling. This was apparent in four aspects: constitutive inhibition of T cell signaling by DEX through a subset of genes showing no response to LPS; inhibition of LPS-induced inflammatory genes by DEX; attenuation of DEX action by LPS paralleled by the regulation of genes implicated in cytokine and calcium signaling; and DEX-induced changes in genes associated with the activation of pro-inflammatory TLR, NF-κB, iNOS, and IL-1 signaling. Consequently, our study provides novel insights into inflammatory and GR signaling in pigs, as well as an understanding of the application of glucocorticoid drugs for the treatment of inflammatory disorders.

摘要

目前对猪免疫细胞中内毒素和糖皮质激素引发的转录组反应的认识水平有限。因此，在本研究中，我们分别用脂多糖 (LPS) 和地塞米松 (DEX) 处理猪外周血单个核细胞 (PBMC) 或联合处理 2 小时。通过mRNA测序检查所得的转录反应。我们发现 LPS 治疗引发了明显的炎症反应，这可以通过促炎细胞因子、趋化因子和相关信号通路如 NF-κB 的上调来证明。同时，鉴定了一系列下调的促炎分子和上调的抗炎分子。它们分别参与 TLR、NF-κB 和 MAPK 级联的抑制以及由 Tregs 和 STAT3 介导的信号传导的激活。这些发现表明，LPS 还启动了一个抗炎过程，以防止过度的炎症反应。转录组反应进一步揭示了免疫反应和糖皮质激素受体 (GR) 信号的大量串扰。这在四个方面很明显： DEX 通过对 LPS 无反应的基因子集对 T 细胞信号传导的组成性抑制；DEX 抑制 LPS 诱导的炎症基因；LPS 减弱 DEX 作用，同时调节与细胞因子和钙信号有关的基因；和 DEX 诱导的与促炎 TLR、NF-κB、iNOS 和 IL-1 信号通路激活相关的基因变化。因此，我们的研究为猪的炎症和 GR 信号传导提供了新的见解，