CD163-Positive Macrophages Within the Tumor Stroma Are Associated With Lymphangiogenesis and Lymph Node Metastasis in Oral Squamous Cell Carcinoma

Abstract

Increasing evidence shows that tumor stromal components, particularly tumor-associated macrophages (TAMs), play an important role in the tumor progression of various solid malignant tumor types. However, their roles in oral squamous cell carcinoma (OSCC) have not been fully elucidated. Seventy human tongue OSCC samples were analyzed in the present study. Immunohistochemistry was used to investigate the correlations between the densities of CD68-, CD163-, and CD204-positive TAMs and clinicopathologic parameters. Lymphatic vessel density (LVD) was estimated using the D2-40 antibody. Invitro studies also were conducted to investigate the effect of conditioned medium (CM) derived from OSCC cell lines on cytokine and chemokine expression in RAW264.7 mouse monocytic leukemia cells. Increased densities of CD68-, CD163-, and CD204-positive TAMs were significantly correlated with lymph node metastasis (P=.035, .0082, and .038, respectively). Higher LVD occurred considerably more frequently in patients with nodal metastasis than in those without such metastasis. Moreover, LVD was considerably increased in patients with higher CD163-positive TAM densities. Studies using immunofluorescence showed that vascular endothelial growth factor (VEGF)-C was expressed in 52 of 70 patients with CD163-positive TAMs (74.2%). Moreover, CM derived from OSCC cell lines stimulated the expression of Il-10, Ccl22, Vegf-a, and Vegf-c in RAW264.7cells; however, Il-12p35 expression levels were not changed. CD163-positive TAMs promote lymphangiogenesis through VEGF-C expression, which contributes to regional lymph node metastasis in OSCC.