Characterization of tertiary lymphoid structure identifies competitive binding of CD40 and STING with TRAF2 driving IRF4-mediated B cell activation in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is a highly aggressive malignancy with a dismal prognosis. Hitherto, little has been known regarding the clinical implications of tertiary lymphoid structures (TLS) and its biological mechanisms of antitumor effect on treatment-naïve ESCC. We herein identified the presence of TLS as an independent factor for favorable survival. By characterizing the immune infiltration and genomic profiles based on transcriptomic datasets, we found TLS abundant in enriched B cells with IRF4 as a signature gene. Increased expression of IRF4 and its positive correlation with STING in activating tumor-infiltrating B cells were also investigated using a single-cell RNA sequencing dataset. CD40 as a co-regulator of IRF4 and TLS formation, in vitro experiments were conducted to further demonstrate the competitive binding relationships between CD40 and STING with TRAF2 in promoting IRF4 expression and B cell activation via the non-canonical NF-kB signaling pathway, in which CD40 reduced STING ubiquitination while promoting its phosphorylation. Our data provided deeper insights into the potential role of activated B cells and TLS in ESCC, with implications for the development of biomarkers and therapeutic targets.