L-lactic acid enhances type I interferon immune response and inhibits virus infection by promoting IRF9 L-lactylation

Y Ying Miao (Hefei National Research Center for Physical Sciences at the Microscale, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, Biomedical Sciences and Health Laboratory of Anhui Province, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China) Q Qun Cui (Institutes of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University) T Tingting Zhang (State Key Laboratory of Bioinspired Interfacial Materials Science, Innovation Center for Chemical Science, College of Chemistry Chemical Engineering and Materials Science) R Renxia Zhang (Institutes of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University) Q Qian Zhao (Zhejiang University , , ,) H Haiyan Zhou (Department of Chemistry, State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR 999077, P. R. China) Y Yibo Zuo (Department of Laboratory Medicine, Institute of Laboratory Medicine, Translational Clinical Immunology Key Laboratory of Sichuan Province, Sichuan Provincial People’s Hospital, School of Medicine, University of Electronic Science and Technology of China) Q Qin Wang Y Yuerong Zhang (Department of Laboratory Medicine, Institute of Laboratory Medicine, Translational Clinical Immunology Key Laboratory of Sichuan Province, Sichuan Provincial People’s Hospital, School of Medicine, University of Electronic Science and Technology of China) Z Zhijin Zheng (Institutes of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University) W Wei He C Chunyan Liu (Laboratory of Advanced Materials, College of Smart Materials and Future Energy (iCOME)) Y Yukang Yuan (Department of Laboratory Medicine, Institute of Laboratory Medicine, Translational Clinical Immunology Key Laboratory of Sichuan Province, Sichuan Provincial People’s Hospital, School of Medicine, University of Electronic Science and Technology of China) H Hui Zheng (Department of Clinical Laboratory, Centre for Leading Medicine and Advanced Technologies of Institute of Health and Medicine, The First Affiliated Hospital of University of Science and Technology of China, Division of Life Sciences and Medicine, University of Science and Technology of China)

Abstract

Lysine lactylation is a crucial posttranslational modification (PTM) that regulates protein function. Here, this study revealed that L-lactic acid promotes host immune response and inhibits viral infection by inducing Interferon Regulatory Factor 9 (IRF9) L-lactylation. We first found L-lactylation modification (L-Kla) of IRF9 mediated by AARS1. Further studies demonstrated that IRF9 L-lactylation potentiates type I interferon (IFN-I) signaling by promoting IRF9–STAT2 interaction, thereby boosting antiviral immune response. Intriguingly, L-lactic acid exhibits dual effects on viral infection: L-lactic acid exhibits antiviral effects at physiological and moderately elevated levels but proviral effects at high levels. Furthermore, we found that the viruses can achieve immune evasion by promoting SIRT1-mediated delactylation of IRF9. Interestingly, we uncovered that metformin promotes IRF9 L-lactylation by both accumulating lactic acid and disrupting virus-induced IRF9–SIRT1 interaction. These findings renew the understanding of the roles of lactic acid in antiviral immune response and determine metformin’s immunomodulatory effects on antiviral immunity through regulating IRF9 L-lactylation.

Article Details

Volume / Issue Vol. 123, Issue 1
Published January 06, 2026
ISSN 0027-8424
Publisher National Academy of Sciences

Authors (14)

Y

Ying Miao

Hefei National Research Center for Physical Sciences at the Microscale, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, Biomedical Sciences and Health Laboratory of Anhui Province, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China

Q

Qun Cui

Institutes of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University

T

Tingting Zhang

State Key Laboratory of Bioinspired Interfacial Materials Science, Innovation Center for Chemical Science, College of Chemistry Chemical Engineering and Materials Science

R

Renxia Zhang

Institutes of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University

Q

Qian Zhao

Zhejiang University , , ,

H

Haiyan Zhou

Department of Chemistry, State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR 999077, P. R. China

Y

Yibo Zuo

Department of Laboratory Medicine, Institute of Laboratory Medicine, Translational Clinical Immunology Key Laboratory of Sichuan Province, Sichuan Provincial People’s Hospital, School of Medicine, University of Electronic Science and Technology of China

Q

Qin Wang

Y

Yuerong Zhang

Department of Laboratory Medicine, Institute of Laboratory Medicine, Translational Clinical Immunology Key Laboratory of Sichuan Province, Sichuan Provincial People’s Hospital, School of Medicine, University of Electronic Science and Technology of China

Z

Zhijin Zheng

Institutes of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University

W

Wei He

C

Chunyan Liu

Laboratory of Advanced Materials, College of Smart Materials and Future Energy (iCOME)

Y

Yukang Yuan

Department of Laboratory Medicine, Institute of Laboratory Medicine, Translational Clinical Immunology Key Laboratory of Sichuan Province, Sichuan Provincial People’s Hospital, School of Medicine, University of Electronic Science and Technology of China

H

Hui Zheng

Department of Clinical Laboratory, Centre for Leading Medicine and Advanced Technologies of Institute of Health and Medicine, The First Affiliated Hospital of University of Science and Technology of China, Division of Life Sciences and Medicine, University of Science and Technology of China