Abstract
BACKGROUND: Chemokine (C-X-C motif) ligand 13 (CXCL13) was known as a selective chemotaxis for B cells, a product of follicular helper CD4(+)T cells (T(FH)) and a contributor to tertiary lymphoid structures (TLS). Although secretion and function of CXCL13 produced by T(FH) have been deeply explored, the immune function and prognostic significance of CXCL13 secreted by CD8(+)T cells still remain unrevealed. This study aims to investigate the clinical merit of CXCL13(+)CD8(+)T cells in clear cell renal cell carcinoma (ccRCC). METHODS: We analyzed prognostic value and immune contexture that associated with CXCL13(+)CD8(+)T cells infiltration level in a total of 755 patients from Zhongshan Hospital cohort (n=223) and The Cancer Genome Atlas cohort (n=532). In vitro analyses were conducted on 42 samples of resected tumor tissue from Zhongshan Hospital in order to detect the immune status of CXCL13(+)CD8(+)T cells and total CD8(+)T cells. Immunohistochemistry (IHC) and flow cytometry were applied to characterize immune cells and portray the tumor microenvironment (TME) in ccRCC. RESULTS: Intratumoral CXCL13(+)CD8(+)T cells abundance was associated with inferior overall survival and disease-free survival. CXCL13(+)CD8(+)T cells possessed higher level of immune checkpoints like programmed cell-death protein 1 (PD-1), T-cell immunoglobulin mucin 3 (Tim-3), T cell immunoreceptor with Ig and ITIM domains (TIGIT) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), higher Ki-67 expression and lower tumor necrosis factor α (TNF-α), interferon γ (IFN-γ) expression. Total CD8(+)T cells in high-level CXCL13(+)CD8(+)T cells infiltration subgroup exhibited elevated exhausted markers (PD-1, Tim-3, TIGIT) and descended activated markers (TNF-α, IFN-γ) without quantity variance. Furthermore, the abundance of intratumoral CXCL13(+)CD8(+)T cell was correlated with immunoevasive TME accompanied by increased T helper 2 cells, tumor-associated macrophages, Foxp3(+) regulatory T cells, TLS and decreased natural killer cells, GZMB(+) cells. CONCLUSIONS: Intratumoral CXCL13(+)CD8(+)T cells infiltration indicated inferior clinical outcome in patients with ccRCC. CXCL13(+)CD8(+)T cells possessed increased exhausted markers, decreased effector molecules and better proliferation ability. CXCL13(+)CD8(+)T cells abundance impaired total CD8(+)T cells' immune function. Intratumoral CXCL13(+)CD8(+)T cells abundance was associated with immunoevasive contexture. The abundance of CXCL13(+)CD8(+)T cells was an independent prognosticator and a potential immunotherapeutic target marker for ccRCC treatment.