The regulatory role and mechanism of TGFBI on Tregs in the immune microenvironment of clear cell renal cell carcinoma
Xuexue Hao, Li Liu, Song Li, Qihua Wang, Zhunan Xu, Xiaoqiang Liu
Abstract
BACKGROUND: Clear cell renal cell carcinoma (ccRCC) is marked by an immunosuppressive tumor microenvironment (TME) dominated by regulatory T cells (Tregs), which facilitate immune evasion. TGFBI, an extracellular matrix protein induced by TGF-β, has been implicated in Treg regulation; however, its role in ccRCC remains poorly understood. This study aimed to elucidate the mechanisms by which TGFBI modulates Treg-mediated immunosuppression and to explore its clinical relevance. MATERIALS AND METHODS: Molecular subtyping, immune infiltration, and TGFBI-Treg interactions were analyzed using data from TCGA and single-cell sequencing. In vitro experiments were conducted with TGFBI-knockdown (RENCA) and overexpression (A498) cell lines to assess migration and Treg chemotaxis. BALB/c mouse models were used to evaluate tumor growth and Treg infiltration. Western blotting, flow cytometry, ELISA, and CCL22-neutralizing antibody assays were employed for functional analysis. RESULTS: Immune subtyping revealed two ccRCC subgroups (G1/G2), with the G2 subgroup exhibiting higher TGFBI expression, poor prognosis, and reduced immune checkpoint activity. Single-cell analysis confirmed the enrichment of TGFBI in tumor epithelial cells and its interaction with Tregs. TGFBI knockdown suppressed both tumor cell migration and Treg recruitment in vitro, while in vivo silencing resulted in reduced tumor growth and Treg infiltration. Mechanistically, TGFBI upregulated CCL22 secretion, and neutralizing CCL22 reversed Treg chemotaxis. Clinical samples corroborated the correlation between TGFBI and FOXP3 + Tregs. CONCLUSION: TGFBI promotes immunosuppression in ccRCC by recruiting Tregs via CCL22, thereby fostering tumor progression and resistance to therapy. Targeting the TGFBI-CCL22 axis may enhance the efficacy of immunotherapy, offering a novel strategy to disrupt Treg-mediated immune evasion in ccRCC.