Macrophage CCL22 expression in the tumor microenvironment and implications for survival in patients with squamous cell carcinoma of the tongue.

BACKGROUND

CCL22, mainly synthesized by monocyte-derived alternative (M2) macrophages, belongs to the CC family of chemokines. CCR4, the receptor for CCL22, is expressed in regulatory T cells (Tregs) and Th2 cells. The Yamamoto-Kohama (YK) mode of invasion has been associated with tumor prognosis. Herein, we investigated the role of CCL22 in the tumor microenvironment and its effect on the overall survival rate in patients with tongue squamous cell carcinoma (SCC).

METHODS

Tumor sections obtained from 92 patients with tongue SCC were graded based on the mode of invasion according to the YK classification. The expressions of several markers (CCL22, CD8, and Ki-67 by immunohistochemistry; CCR4 and FoxP3 by immunofluorescent staining) were evaluated. Student's t test and chi-square tests were used to compare differences between numerical variables and groups, respectively. Survival curves were plotted according to the Kaplan-Meier method and compared using a log-rank test. Hazard ratios and 95% confidence intervals were estimated using univariate or multivariate Cox proportional hazard models.

RESULTS

The expression of CCL22 was significantly correlated with YK classification, overall survival rate (P < 0.001), a decrease in the number of CD8-positive cells, and an increase in the tumor Ki-67 index. In addition, CCR4-positive cells were observed around CCL22-positive macrophages.

CONCLUSION

These findings indicate that the expression of CCL22 in the tumor microenvironment led to a deterioration in the prognosis of patients with tongue SCC by influencing the balance of M1- and M2-like macrophages.