Characteristics of Tumor Immune Gene and Immune Cell Infiltration during Keloid Formation

Background: Keloids are benign fibroproliferative skin tumors that can cause disfigurement and disability. Although current research has sought to examine keloids from the perspectives of genetics, inflammation, immunity, and tumorigenesis, their pathological mechanisms remain unclear. Methods: In this study, we used three datasets of tumor immune gene expression profiling from the normal skin tissue of keloid patients (N group), inflammation tissue of keloid patients (I group), and keloid tissue of keloid patients (K group) to describe the occurrence and characteristics of keloid development. Tumor immune-related genes were analyzed, and the differentially expressed genes (DEGs) between the three groups were compared. Gene Ontology (GO) categories and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were carried out to determine the main functions of the differentially expressed genes and keloid-related pathways. Results: We identified several genes that may play an important role in keloid development. These genes are CCR1, SELL, CCR7, CD40LG, CD69, CXCL8, ITGAM, ITGAX, CD86, and CXCL9. GO analysis revealed that there were variations in biological processes (BP) between I group and N group, including regulation of lymphocyte activation and T-cell activation. Similar variations were also found between I group and K group, which may play an important role in keloid initiation and formation. Variations in molecular function (MF) were markedly enriched in cytokine receptor binding and receptor ligand activity. Analysis of the KEGG pathway between I group and N group revealed that DEGs were primarily enriched in cytokine−cytokine receptor interaction and viral protein interaction with cytokine and cytokine receptor. We identified a higher proportion of M2 macrophages in N group than in I group, although the difference was not obvious. M1 macrophage production differed significantly between I group and K group. The proportions of CD8+T cells varied significantly between N group and K group. We traced multiple tumor immune-related hub genes from keloid formation and analyzed immune cell subsets in keloid development. Possible molecular mechanisms were described in this study using bioinformatics. Conclusions: These results provide another possibility to elucidate keloid pathogenesis and therapeutic targets in terms of tumor immune gene expression.