Stattic Attenuates LPS- and CIRBP-Induced Inflammatory Signaling in THP-1 Macrophages

Extracellular cold-inducible RNA-binding protein (eCIRBP) is a key driver of sterile inflammation following ischemia/reperfusion (I/R) injury, such as during cardiac surgery. While eCIRBP’s interaction with the TLR4/MD2 complex is known to activate the NF-κB pathway, its role in activating the JAK/STAT3 pathway via the IL-6 receptor (IL-6R) is less understood. To investigate this, human THP-1-derived macrophage-like cells were stimu-lated with a recombinant human active peptide to CIRBP (rhCIRBP) with or without Stattic pre-treatment, a selective STAT3 phosphorylation (Y705) inhibitor. Activation of NF-κB and STAT3 was assessed by Western blotting, while gene expression of inflammatory markers (IL-6, IL-1β, TNF-α, MCP-1, ICAM, and SOCS3) was measured via RT-qPCR. We observed rhCIRBP stimulation significantly activated both signaling pathways, resulting in increased inflammatory gene expression. Notably, STAT3 inhibition with Stattic sup-pressed these effects, indicating STAT3’s critical role in eCIRBP-driven inflammation. Our findings confirm eCIRBP as a potent inflammatory mediator, corresponding with reported elevated concentrations of circulatory eCIRBP in patients after cardiac surgery and those suffering from hemorrhagic shock and sepsis. Additionally, targeting eCIRBP-induced ac-tivation of NF-κB and STAT3 may offer a novel therapeutic strategy for managing I/R-induced inflammation.