Inflammation-related pathways involved in damaged articular cartilage of rats exposed to T-2 toxin based on RNA-sequencing analysis

Many studies have shown that ingestion of the T-2 toxin is harmful to articular cartilage. However, the mechanisms underlying damaged articular cartilage induced by T-2 toxin have not been elucidated. Twenty-four SD rats were randomly divided into T-2 toxin and control groups. In the control group, the 12 rats were administered 4% absolute ethanol by gavage, and in the T-2 toxin group, the 12 rats were administered T-2 toxin (100 ng/g, BW/day) by gavage. After the rats were sacrificed, the knee joints were collected, and RNA was extracted using TRIzol reagent for RNA sequencing (RNA-seq). Differentially expressed mRNA was identified based on p < 0.05 and | log(2) (fold change) | > 1. The T-2 toxin-related genes were obtained from the GeneCards database. An online tool (https://www.bioinformatics.com.cn) was used for enrichment analysis. Hematoxylin and eosin (H&E) staining was used to observe damaged articular cartilage, and immunohistochemical (IHC) staining was used to validate differentially expressed proteins. The H&E staining shows the number of cells decreased significantly, and the arrangement of chondrocytes became disordered in the T-2 toxin group. RNA-seq analysis identified 195 upregulated and 89 downregulated mRNAs in the T-2 toxin group. The top immune-related biological processes (Gene Ontology) were regulation of hormone secretion, regulation of peptide hormone secretion, and regulation of transcription involved in cell fate commitment. KEGG pathway enrichment analysis revealed that the IL-17 and tumor necrosis factor signaling pathways were significantly expressed, and the IL-17 signaling pathway was also identified in the enrichment analysis of T-2 toxin-related genes. Also, Mmp3, Tnf, Mapk10, Ccl11, Creb5, Cxcl2, and Cebpb were significantly enriched in the two pathways. The immunohistochemical staining showed that the levels of Mmp3 and Tnf proteins were significantly increased in the T-2 toxin group, which was consistent with the RNA-seq results. This study revealed the critical roles of IL-17 and TNF signaling pathways in damaged cartilage induced by T-2 toxin.