Heine Lauren K, Nault Rance, Jackson Jalen, Anderson Ashley N, Harkema Jack R, Olive Andrew J, Pestka James J, McDonald Olivia F
bioRxiv. 2025 Jun 17:2025.06.12.658906. doi: 10.1101/2025.06.12.658906.
Systemic lupus erythematosus (SLE) is a complex autoimmune disorder characterized by aberrant inflammation, type I IFN-stimulated gene (ISG) expression, and autoantibody production. Glucocorticoids (GCs) like dexamethasone (DEX) are standard long-term SLE treatments but cause significant side effects, highlighting the need for safer steroid-sparing options. Preclinical and clinical studies suggest that dietary supplementation with omega-3 fatty acids (O3FAs), particularly docosahexaenoic acid (DHA), suppress inflammation and autoimmunity associated with SLE disease progression. We explored the steroid-sparing potential of DHA to influence suppressive effects of DEX on pathogenic gene expression.
Macrophages from SLE-prone NZBWF1 mice were first subjected to DHA (5, 10, or 25 µM), DEX (1, 10, 100, or 1000 nM), or DHA+DEX cotreatment. Following pretreatment, cells were exposed to lipopolysaccharide (LPS; 20 ng/mL) to model SLE hyperinflammation. Effects on gene expression were analyzed by qRT-PCR and RNA-seq.
qRT-PCR indicated that subinhibitory concentrations of DHA (5-10 µM) potentiated the efficacy of low-dose DEX (1-100 nM) in suppressing LPS-induced ISG expression (e.g., , , ), amplifying the effects of DEX monotherapy by 10- to 100-fold. SynergyFinder analysis confirmed that DHA and DEX interacted synergistically in suppressing ISG expression, with significant inhibition observed at concentrations as low as 1 nM DEX and 5 µM DHA. RNA-seq revealed that combining suboptimal DHA (10 μM) and DEX (100 nM) induced 247 differentially expressed genes (DEGs) at 4 hr and 347 DEGs at 8 hr post-LPS, dramatically surpassing the effects of each treatment alone. Functional enrichment analysis indicated that DHA+DEX cotreatment robustly suppressed immune and inflammatory pathways while promoting proliferative and metabolic processes, reflecting a shift from inflammatory (M1) to pro-resolving (M2) macrophage phenotypes. DHA and DEX countered LPS effects by i) downregulating common transcription factors (TFs) canonically associated with inflammation (e.g., NF-κB, AP-1, STATs, and IRF1), ii) upregulating shared regulatory factors involved in inflammation resolution (e.g., YBX1, EGR1, and BCL6), and iii) selectively influencing other regulatory factors.
Altogether, DHA and DEX synergistically suppress inflammation by targeting common and unique molecular pathways in SLE macrophages, favoring the pro-resolving M2 phenotype. O3FA-GC cotreatment might facilitate reducing requisite steroid dosages for SLE management.
系统性红斑狼疮（SLE）是一种复杂的自身免疫性疾病，其特征为异常炎症、I型干扰素刺激基因（ISG）表达以及自身抗体产生。像地塞米松（DEX）这样的糖皮质激素（GCs）是SLE的标准长期治疗药物，但会引起显著的副作用，这凸显了对更安全的类固醇替代方案的需求。临床前和临床研究表明，饮食中补充ω-3脂肪酸（O3FAs），尤其是二十二碳六烯酸（DHA），可抑制与SLE疾病进展相关的炎症和自身免疫。我们探讨了DHA的类固醇替代潜力，以影响DEX对致病基因表达的抑制作用。
首先将来自易患SLE的NZBWF1小鼠的巨噬细胞用DHA（5、10或25μM）、DEX（1、10、100或1000 nM）或DHA + DEX联合处理。预处理后，将细胞暴露于脂多糖（LPS；20 ng/mL）以模拟SLE的过度炎症。通过qRT-PCR和RNA测序分析对基因表达的影响。
qRT-PCR表明，亚抑制浓度的DHA（5 - 10μM）增强了低剂量DEX（1 - 100 nM）抑制LPS诱导的ISG表达的功效（例如， 、 、 ），将DEX单药治疗的效果放大了10至100倍。SynergyFinder分析证实，DHA和DEX在抑制ISG表达方面具有协同作用，在低至1 nM DEX和5μM DHA的浓度下就观察到了显著抑制。RNA测序显示，将次优剂量的DHA（10μM）和DEX（100 nM）联合使用在LPS处理后4小时诱导了247个差异表达基因（DEGs），8小时诱导了347个DEGs，大大超过了每种治疗单独的效果。功能富集分析表明，DHA + DEX联合处理强烈抑制免疫和炎症途径，同时促进增殖和代谢过程，反映了从炎症（M1）向促解决（M2）巨噬细胞表型的转变。DHA和DEX通过以下方式对抗LPS的作用：i）下调通常与炎症相关的常见转录因子（TFs）（例如NF-κB、AP-1、STATs和IRF1），ii）上调参与炎症解决的共享调节因子（例如YBX1、EGR1和BCL6），以及iii）选择性地影响其他调节因子。
总之，DHA和DEX通过靶向SLE巨噬细胞中的共同和独特分子途径协同抑制炎症，有利于促解决的M2表型。O3FA - GC联合处理可能有助于减少SLE管理所需的类固醇剂量。
