A Synthetic Poly(A) Tail Targeting Extracellular CIRP Inhibits Sepsis.

Sepsis is an infectious inflammatory disease that often results in acute lung injury (ALI). Cold-inducible RNA-binding protein (CIRP) is an intracellular RNA chaperon that binds to mRNA's poly(A) tail. However, CIRP can be released in sepsis, and extracellular CIRP (eCIRP) is a damage-associated molecular pattern, exaggerating inflammation, ALI, and mortality. In this study, we developed an engineered poly(A) mRNA mimic, AAAAAAAAAAAA, named A12, with 2'-O-methyl ribose modification and terminal phosphorothioate linkages to protect it from RNase degradation, exhibiting an increased half-life. A12 selectively and strongly interacted with the RNA-binding motif of eCIRP, thereby preventing eCIRP's binding to its receptor, TLR4. In vitro treatment with A12 significantly decreased eCIRP-induced macrophage MAPK and NF-κB activation and inflammatory transcription factor upregulation. A12 also attenuated proinflammatory cytokine production induced by eCIRP in vitro and in vivo in macrophages and mice, respectively. We revealed that treating cecal ligation and puncture-induced sepsis with A12 significantly reduced serum organ injury markers and cytokine levels and ALI, and it decreased bacterial loads in the blood and peritoneal fluid, ultimately improving their survival. Thus, A12's ability to attenuate the clinical models of sepsis sheds lights on inflammatory disease pathophysiology and prevention of the disease progress.