FOXP3+ Cells Recruited by CCL22 into Breast Cancer Correlates with Less Tumor Nodal Infiltration

Abstract

Background: Regulatory T-cells (Tregs) are a T-cell subpopulation with suppressive capacities, which are specifically attracted by C-C motif chemokine 22 (CCL22). Treg infiltration of tumors is associated with a poor prognosis in many patients. We aimed to investigate whether CCL22 is expressed in human breast cancer and whether its presence is associated with Treg infiltration.

Materials and methods: Eighty paraffin-embedded human breast cancer samples were stained for CCL22 and for the Treg-specific transcription factor forkhead box P3 (FOXP3). Expression was evaluated in a semi-quantitative manner.

Results: FOXP3(+) cells infiltrated 50% of the breast tumors. Moreover, Treg infiltrated 93% of the tertiary lymphoid structures. CCL22 expression positively correlated with FOXP3(+) cell infiltration into the tertiary lymphoid structures.

Conclusion: Our results demonstrate that CCL22 expression correlates with infiltration by FOXP3(+) cells. Interestingly, Treg presence negatively correlated with positive nodal status. In addition to their unfavorable role as mediators of evasion from antitumor immune response, Tregs might also have a beneficial role by reducing inflammation thereby limiting early tumor growth and spreading.

Keywords: CCL22; FOXP3; Regulatory T-cells; breast cancer; immunohistochemistry; tertiary lymphoid structures.