Abstract: BACKGROUND: Allicin, the main active ingredient in garlic, has anti-inflammatory and antioxidant effects, but the role and mechanism of allicin in ameliorating rheumatoid arthritis remain unclear.
OBJECTIVE: To analyze differentially expressed genes in rheumatoid arthritis using gene expression data and explore the regulatory role of alliin in rheumatoid arthritis.
METHODS: Gene expression data for rheumatoid arthritis were collected from the GSE45291 and GSE93777 datasets, and differential expression analysis was then performed. Co-expression network analysis was conducted on the common differentially expressed genes identified in both datasets to identify the module genes most closely related to rheumatoid arthritis, followed by functional enrichment analysis. The SwissTargetPrediction database was used to predict the target genes of allicin in the differentially expressed genes. The area under the receiver operator characteristic curve (AUC) of the differentially expressed target genes was calculated. Human immortalized rheumatoid arthritis fibroblast-like synoviocytes were seeded onto pore plates and cultured for 24 hours, and the cells were then divided into five groups. The control group was not treated; methotrexate was added to the positive drug group; and 20, 80, and 160 μg/mL 
allicin was added to the low-, medium-, and high-dose allicin groups, respectively. After 48 hours of treatment, cell activity was assessed using cell counting kit-8 assay and cell apoptosis was detected using TUNEL assay. Levels of oxidative stress and inflammatory factors were measured by ELISA. Changes in mitochondrial membrane potential were detected by JC-1 staining. The expression levels of target genes and related signaling pathways were detected by RT-qPCR and western blot.
RESULTS AND CONCLUSION: A total of 6 487 common differentially expressed genes were identified in the GSE45291 and GSE93777 datasets, and 12 co-expression modules were obtained. The magenta module had the highest correlation with rheumatoid arthritis, with module genes primarily enriched in the phosphatidylinositol 3-kinase/protein kinase B signaling pathway. Database predictions revealed that seven differentially expressed genes were targeted by allicin, with epidermal growth factor receptor having the highest AUC value in the GSE45291 dataset and kynureninase having the highest AUC value in the GSE93777 dataset. Treatment of human immortalized rheumatoid arthritis fibroblast-like synoviocytes with allicin significantly inhibited cell activity, promoted cell apoptosis, decreased the levels of reactive oxygen species, malondialdehyde, interleukin-6, interleukin-1β, increased the expression of mitochondrial membrane potential, decreased the mRNA and protein expression of epidermal growth factor receptor, kynureninase, mitochondrial dynamin-related protein 1, elevated the mRNA and protein expression of mitochondrial fusion protein 2, and increased the protein expression of p-AKT and p-PI3K. To conclude, allicin plays the potential therapeutic effects on rheumatoid arthritis through the regulation of target genes such as epidermal growth factor receptor and kynureninase. 

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

Key words: rheumatoid arthritis, allicin, epidermal growth factor receptor, kynureninase, target gene, engineered tissue construction