Zixin Zhu,1,* Yifan Liao,2,* Qiuju Mou,1 Hongjie Liu,2 Yuxue Shen,2 Lili Zhu,1 Shuo Cong1 

1Department of Blood Transfusion, The Affiliated Hospital of Guizhou Medical University, Guiyang, 550004, People’s Republic of China; 2School of Clinical Laboratory Science, Guizhou Medical University, Guiyang, 550004, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Shuo Cong, Email 2022120040826@stu.gmc.edu.cn

Introduction: Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis, insulin resistance, and systemic pro-inflammatory response. Thymosin β 4 (Tβ 4) is a bioactive polypeptide that inhibits extracellular matrix (ECM) deposition and protects the liver. It can achieve immune homeostasis by regulating the polarization of liver macrophages and is a potential treatment for NAFLD.
Methods: A dataset was used to evaluate the expression of Tβ 4 in fatty and non-fatty adjacent tissues of primary hepatocellular carcinoma. NAFLD was induced in C57 mice with methionine and choline-deficient diet (MCD), siRNATβ 4 was injected into the tail vein to reduce liver Tβ 4, and the therapeutic effect of Tβ 4 was observed by phagocytosis of macrophages with clodronate liposomes. Hematoxylin and Eosin staining (HE) staining was used to observe the inflammation of mice in each group, and oil red O staining was used to determine the lipid accumulation. Macrophage polarization was detected by immunofluorescence assay. In the extrachromosomal experiment of oil red O, human myeloid leukemia mononuclear (THP-1) cells was co-cultured with human hepatic (LO2) constructed with oleic acid to detect the changes of aspartate transaminase (AST) and alanine transaminase (ALT) in supernatant and the apoptosis of LO2 under the intervention of different concentrations of Tβ 4.
Results: Tβ 4 allowed the mice to recover from NAFLD and reduce liver inflammation more effectively. Liver steatosis was more severe in sirnat4 mice. Macrophages are involved in Tβ 4 treatment of NAFLD. The expression level of M1 phenotype in macrophages treated with Tβ 4 decreased, and the apoptosis of hepatocytes decreased. At the same time, Tβ 4 down-regulates signal transduction and activator of transcription1 (STAT1) phosphorylation and increases suppressor of cytokine signaling1/3 (SOCS1/3) expression in hepatocytes.
Discussion: This study revealed the molecular mechanism of the effective effect of Tβ 4 on the polarization of liver macrophages, suggesting that Tβ 4 may be a potential therapeutic measure for NAFLD.

Keywords: thymosin beta 4, NAFLD, macrophage, inflammation