Vitamin B12 Alleviates Hepatic Ischemia–Reperfusion Injury with Restoration of Propanoate Metabolism and Mitochondrial Function

Simeng Lei,1,2,* Zhenyu Zheng,3,* Hao Wang,2,4,* Hanwen Yang,1,2 Yuepeng Wang,5 Bo Zhang,1,2 Yangkai Fu,1,2 Zhen Li,6 Zhili Ji1,21Division of Hepatobiliary and Pancreaticosplenic Surgery, Department of General Surgery, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, 100020, People’s Republic of China; 2Beijing Organ Transplant Center, Beijing, 100020, People’s Republic of China; 3Department of Radiation Oncology, Clinical Oncology School of Fujian Medical University, Fujian Cancer Hospital, Fuzhou, People’s Republic of China; 4Department of Urology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, 100020, People’s Republic of China; 5School of Medicine, Nankai University, Tianjin, 300071, People’s Republic of China; 6Department of Urology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221000, People’s Republic of China*These authors contributed equally to this workCorrespondence: Zhili Ji, Email anzhenjzl@mail.ccmu.edu.cn Zhen Li, Email zhenli1025@163.comBackground: Hepatic ischemia-reperfusion injury (HIRI) is a major cause of liver dysfunction after hepatectomy and liver transplantation and involves inflammatory, oxidative, mitochondrial, and metabolic disturbances. Although inflammatory and oxidative mechanisms have been extensively studied, metabolic alterations during HIRI remain less well characterized. This study investigated changes in propanoate metabolism during HIRI and evaluated the effects of vitamin B12 (VB12).Methods: Transcriptomic and single-cell transcriptomic data from mouse HIRI models and human liver transplantation were integrated with in vivo experiments and hypoxia/reoxygenation (H/R) experiments in AML12 cells to examine changes in propanoate metabolism and the effects of VB12 treatment.Results: Propanoate metabolism was markedly suppressed during HIRI, with a similar reduction observed in hepatocytes from human liver transplantation data. VB12 treatment reduced H/R and HIRI induced injury and inflammatory responses in vitro and in vivo. Transcriptomic analysis showed recovery of propanoate metabolism-related pathways after VB12 treatment. Among the candidate genes identified within this pathway, Mmut was consistently reduced after H/R or HIRI and increased following VB12 treatment. VB12 also attenuated H/R-induced mitochondrial membrane depolarization and improved mitochondrial function-related changes.Conclusion: Hepatocyte propanoate metabolism is markedly suppressed during HIRI. VB12 restores propanoate metabolism and Mmut expression, improves mitochondrial function, and alleviates HIRI. These findings identify Mmut as a potential key gene associated with the metabolic response to VB12 and support VB12 as a potential metabolic intervention for HIRI.Keywords: hepatic ischemia-reperfusion injury, vitamin B12, propanoate metabolism, mitochondrial function, Mmut