A citrullinated histone H3 monoclonal antibody for immune modulation in sepsis
Wenlu Ouyang, Yuchen Chen, Tao Tan, Yujing Song, Tao Dong, Xin Yu, Kyung Eun Lee, Xinyu Zhou, Zoe Tetz, Seok Hyeon Go, Xindi Zeng, Liu-Jia-Zi Shao, Chao Quan, Ting Zhao, Yuzi Tian, Katsuo Kurabayashi, Hua Jin, Jichun Ma, Jingdong Qin, Brandon Williams, Qingtian Li, Gui‐Dong Zhu, Hasan B. Alam, Kathleen A. Stringer, Yongqing Li, Jianjie Ma, Jianjie Ma, Jianjie Ma
Abstract
Citrullinated histone H3 (CitH3), released from immune cells during early sepsis, drives a vicious cycle of inflammation through excessive NETosis and pyroptosis, causing immune dysfunction and tissue damage. To regulate this process, we develop a humanized CitH3 monoclonal antibody (hCitH3-mAb) with high affinity and specificity to target this process. In murine models, hCitH3-mAb reduces cytokine production, mortality and acute lung injury (ALI) caused by LPS and Pseudomonas aeruginosa while enhancing bacteria phagocytosis in the lungs, spleen, and liver. Using pre-equilibrium digital ELISA (PEdELISA), we identify an optimal therapeutic window for hCitH3-mAb in sepsis-induced ALI. In parallel, we explore the molecular mechanism underlying CitH3-driven inflammation. We find that in macrophages, CitH3 activates Toll-like receptor 2 (TLR2), triggering Ca2+-dependent PAD2 auto-citrullination and nuclear translocation, amplifying CitH3 production via a harmful feedback loop. The hCitH3-mAb treatment effectively disrupts this cycle and restores macrophage function under septic conditions. Together, these findings highlight both the therapeutic potential of hCitH3-mAb and provide a deep mechanistic insight into the CitH3–PAD2 axis in sepsis, supporting its further development for treating immune-mediated diseases. This study reports the development and preclinical evaluation of a humanized citrullinated histone H3 (CitH3) monoclonal antibody that mitigates inflammation, restores macrophage function, and protects against sepsis-induced pulmonary injury.