Daxing Cai,1,* Weitao Hu,1,* Yanliang Cai,2,* Taiyong Fang,1 Xiaoqing Chen3 

1Department of Gastroenterology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian, 362000, People’s Republic of China; 2Department of Pediatrics, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian, 362000, People’s Republic of China; 3Department of Rheumatology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian, 362000, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Xiaoqing Chen, Department of Rheumatology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian, 362000, People’s Republic of China, Email chenxiaoqing202203@163.com Taiyong Fang, Department of Gastroenterology, The Second Affiliated Hospital of Fujian Medical University, 34 North Zhongshan Road, Licheng District, Quanzhou, Fujian, 362000, People’s Republic of China, Email fangtaiyong122@126.com

Introduction: Ulcerative colitis (UC) is an inflammatory bowel disease influenced by genetic, immune, and environmental factors. This study investigates the link between ferroptosis, a cell death process related to oxidative stress and iron metabolism, and immune infiltration in UC.
Materials and Methods: We analyzed UC patient transcription data from the Gene Expression Omnibus (GEO) and identified ferroptosis-related genes using FerrDB. Using STRING and Cytoscape, we analyzed protein-protein interactions to identify hub UC Differentially Expressed Genes (UCDEGs) and performed functional enrichment with GO and KEGG pathways. Machine learning helped further identify key UC Differentially Expressed Ferroptosis-related genes (UCDE-FRGs), which were validated using additional GEO datasets and immunohistochemical staining.
Results: A total of 11 hub UCDEGs (CCL2, ICAM1, TLR2, CXCL9, MMP9, CXCL10, IL1B, CXCL8, PTPRC, FCGR3A, and IL1A) and 3 key UCDE-FRGs (DUOX2, LCN2 and IDO1) were identified. GO and KEGG functional enrichment indicates that these genes play a role in immunity and ferroptosis. Analysis of immune cell infiltration showed that there were a large number of Plasma cells, Monocytes, M0/M1 Macrophages and Neutrophils in the UC. Correlation analysis revealed 3 key UCDE-FRGs associated with immune-infiltrated cells in UC. IHC results showed that the expression levels of 3 key UCDE-FRGs in UC were all higher than that in the healthy controls.
Conclusion: In summary, this study identified three key genes related to UC ferroptosis and immunity, namely DUOX2, IDO1 and LCN2. These findings suggest that immune infiltration plays an important role in UC caused by ferroptosis, and that there is mutual regulation between UC and immune-infiltrated cells. Our research revealed the potential application of immune and ferroptosis in the diagnosis, treatment and prognosis of UC, providing new strategies for clinical management.

Keywords: ulcerative colitis (UC), inflammatory bowel disease (IBD), machine learning, immune-infiltrated cells, bioinformatics