Identification and Verification of FABP4 Regulate Ferroptosis in Ulcerative Colitis

Background: Ferroptosis has garnered increasing attention; however, relevant researches are insufficient. Methods: We incorporated two microarray datasets from Gene Expression Omnibus (GEO) and utilized the FerrDb website to identify ferroptosis genes. Differential expression analysis of ferroptosis-related genes and functional enrichment analysis were performed using R software. Machine learning technique was employed to screen for core genes and evaluate their correlation with immune cells, ultimately identifying core genes with diagnostic value. In vivo and in vitro experiments were conducted to confirm the relationship between the core gene and ulcerative colitis (UC) ferroptosis. We conducted a UC mouse model using 3% dextran sodium sulfate (DSS) free drinking water method. We detected the expression of Fatty Acid Biding Protein-4 (Fabp4), glutathione peroxidase 4 (Gpx4), ferritin heavy chain (Fth), protein kinase B (PKB, also named as Akt), Phosphatidylinositide 3-kinases (Pi3k), and interleukin-1 beta (IL-1 beta) in the mouse colon through quantitative real-time PCR (qPCR) and western blot (WB) analysis. Additionally, we performed an in vitro experiment using the THP-1 cell line. The cells were pretreated with Ferrostatin-1 (Fer-1) and FABP4 inhibitor (BMS 3094033) for 1 hour, followed by the addition of Erastin. We then measured the intracellular expression of FABP4, GPX4, FTH, AKT, PI3K, and IL-1 beta using qPCR and immunofluorescence. Results: FABP4 is a crucial gene in ulcerative colitis (UC). It is associated with the infiltration of immune cells like macrophages, dendritic cells, and neutrophils, as well as Phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) signaling pathway. In vivo experiments have demonstrated that the expressions of Fabp4, Fth, Pi3k, Akt, and Il-1 beta were elevated in the colon of UC mice, while the Gpx4 was reduced. In vitro experiments found that after adding FABP4 inhibitors, the expressions of FTH, PI3K, AKT, and IL-1 beta decreased, while GPX4 increased. Conclusions: FABP4 has been identified as a pivotal gene in the ferroptosis process in UC. It is suggested that FABP4 regulates the PI3K/AKT signaling pathway, thereby playing a crucial role in UC's ferroptosis development.