Acute-on-chronic liver failure (ACLF) is a severe disease with a high mortality. Macrophage-related inflammation plays a crucial role in ACLF development. Mesenchymal stem cells (MSCs) treatment was demonstrated to be beneficial in ACLF in our previous study; however, the underlying mechanisms remain unknown. Therefore, mouse bone marrow-derived MSCs were used to treat an ACLF mouse model or cocultured with RAW264.7/J774A.1 macrophages that were stimulated with LPS. Histological and serological parameters and survival were analyzed to evaluate efficacy. We detected changes of Mer tyrosine kinase (Mertk), JAK1/STAT6, inflammatory cytokines, and markers of macrophage polarization in vitro and in vivo. In ACLF mice, MSCs improved liver function and 48-h survival of ACLF mice and alleviated inflammatory injury by promoting M2 macrophage polarization and elevated Mertk expression levels in macrophages. This is significant, as Mertk regulates M2 macrophage polarization via the JAK1/STAT6 signaling pathway.

Background: Acute-on-chronic liver failure (ACLF) is a major challenge in the field of hepatology. While mesenchymal stem cell (MSC) therapy can improve the prognosis of patients with ACLF, the molecular mechanisms through which MSCs attenuate ACLF remain poorly understood. We performed global miRNA and mRNA expression profiling via next-generation sequencing of liver tissues from MSC-treated ACLF mice to identify important signaling pathways and major factors implicated in ACLF alleviation by MSCs. Methods: Carbon tetrachloride-induced ACLF mice were treated with saline or mouse bone marrow-derived MSCs. Mouse livers were subjected to miRNA and mRNA sequencing. Related signal transduction pathways were obtained through Gene Set Enrichment Analysis. Functional enrichment, protein-protein interaction, and immune infiltration analyses were performed for the differentially expressed miRNA target genes (DETs). Hub miRNA and mRNA associated with liver injury were analyzed using LASSO regression. The expression levels of hub genes were subjected to Pearson's correlation analysis and verified using RT-qPCR. The biological functions of hub genes were verified in vitro. Results: The tricarboxylic acid cycle and peroxisome proliferator-activated receptor pathways were activated in the MSC-treated groups. The proportions of liver-infiltrating NK resting cells, M2 macrophages, follicular helper T cells, and other immune cells were altered after MSC treatment. The expression levels of six miRNAs and 10 transcripts correlated with the degree of liver injury. miR-27a-5p was downregulated in the mouse liver after MSC treatment, while its target gene E2f2 was upregulated. miR-27a-5p inhibited E2F2 expression, suppressed G1/S phase transition and proliferation of hepatocytes, in addition to promoting their apoptosis. Conclusions: This is the first comprehensive analysis of miRNA and mRNA expression in the liver tissue of ACLF mice after MSC treatment. The results revealed global changes in hepatic pathways and immune subpopulations. The miR-27a-5p/E2F2 axis emerged as a central regulator of the MSC-induced attenuation of ACLF. The current findings improve our understanding of the molecular mechanisms through which MSCs alleviate ACLF.

KRAS -driven metabolic reprogramming is a known peculiarity features of pancreatic ductal adenocarcinoma (PDAC) cells. However, the metabolic roles of other oncogenic genes, such as YY1 , in PDAC development are still unclear. In this study, we observed significantly elevated expression of YY1 in human PDAC tissues, which positively correlated with a poor disease progression. Furthermore, in vitro studies confirmed that YY1 deletion inhibited PDAC cell proliferation and tumorigenicity . Moreover, YY1 deletion led to impaired mitochondrial RNA expression, which further inhibited mitochondrial oxidative phosphorylation (OXPHOS) complex assembly and altered cellular nucleotide homeostasis. Mechanistically, the impairment of mitochondrial OXPHOS function reduced the generation of aspartate, an output of the tricarboxylic acid cycle (TCA), and resulted in the inhibition of cell proliferation owing to unavailability of aspartate-associated nucleotides. Conversely, exogenous supplementation with aspartate fully restored PDAC cell proliferation. Our findings suggest that YY1 promotes PDAC cell proliferation by enhancing mitochondrial respiration and the TCA, which favors aspartate-associated nucleotide synthesis. Thus, targeting nucleotide biosynthesis is a promising strategy for PDAC treatment.