Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 20 1 2021 02 11 88 97 EN Alireza Salah Department of Basic Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran Mohammad Hossein Karimi Organ Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran Javad Sajedianfard Department of Basic Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran Saeed Nazifi Department of Clinical Studies, School of Veterinary Medicine, Shiraz University, Shiraz, Iran Ramin Yaghobi Organ Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran 2020 05 14 2020 09 28 Ischemia/reperfusion (I/R) injury in cadaveric liver transplantation is not avoidable. Liver I/R injury is an important phenomenon in hepatic damage. MicroRNA-21 (miR-21) plays an important role in I/R injury. The present study aimed to determine the expression pattern of miR-21 in liver I/R injury/recovery and its correlation with the immunologic transmission signals pathways several days post-reperfusion. In an animal model for I/R in the liver, 40 male Balb/c mice were divided into 3 groups. The animals were monitored for 3 and 24 hours, and also for 4, 7, 14, and 28 days post-reperfusion. Liver tissue damage was assessed by histopathology. The plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total antioxidant capacity (TAC) levels were measured with enzymatic assays. MiR-21, programmed cell death 4 (PDCD4) mRNA, T-cell-restricted intracellular antigen 1 (TIA1) mRNA, and fas ligand (FASL) mRNA expression levels were measured; using reverse transcription-polymerase chain reaction (RT-PCR) at different times after the reperfusion in liver tissue and blood. Histopathology and plasma ALT, AST, ALP, and TAC levels confirmed liver damage induced by I/R injury. MiR-21 increased by twofold in the liver tissue and on the inflammatory phase after 24 hours of reperfusion; it then continued to decrease up to day 7 post-reperfusion. Afterward, it continued to rise slightly up to day 14 post-reperfusion. This trend was in parallel with the recovery of the liver damage. MiR-21 expression level in the liver and blood is a predictor of the extent of I/R injury. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/2828