Blockade of mIL-6R alleviated lipopolysaccharide-induced systemic inflammatory response syndrome by suppressing NF-κB-mediated Ccl2 expression and inflammasome activation.

Systemic inflammatory response syndrome (SIRS) is characterized by dysregulated cytokine release, immune responses and is associated with organ dysfunction. IL-6R blockade indicates promising therapeutic effects in cytokine release storm but still remains unknown in SIRS. To address the issue, we generated the human knock-in mice and a defined epitope murine anti-human membrane-bound IL-6R (mIL-6R) mAb named h-mIL-6R mAb. We found that the h-mIL-6R and the commercial IL-6R mAb Tocilizumab significantly improved the survival rate, reduced the levels of TNF-α, IL-6, IL-1β, IFN-γ, transaminases and blood urea nitrogen of LPS-induced SIRS mice. Besides, the h-mIL-6R mAb could also dramatically reduce the levels of inflammatory cytokines in LPS-treated THP-1 cells in vitro. RNA-seq analysis indicated that the h-mIL-6R mAb could regulate LPS-induced activation of NF-κB/Ccl2 and NOD-like receptor signaling pathways. Furthermore, we found that the h-mIL-6R mAb could forwardly inhibit Ccl2 expression and NLRP3-mediated pyroptosis by suppressing NF-κB in combination with the NF-κB inhibitor. Collectively, mIL-6R mAbs suppressed NF-κB/Ccl2 signaling and inflammasome activation. IL-6R mAbs are potential alternative therapeutics for suppressing excessive cytokine release, over-activated inflammatory responses and alleviating organ injuries in SIRS.