Hyperthermia by Near Infrared Radiation Induced Immune Cells Activation and Infiltration in Breast Tumor

Abstract

Breast cancer is the most common cancer that causes death in women. Conventional therapies, including surgery and chemotherapy, have different therapeutic effects and are commonly associated with risks and side effects. Near infrared radiation is a technique with few side effects that is used for local hyperthermia, typically as an adjuvant to other cancer therapies. The understanding of the use of near NIR as a monotherapy, and its effects on the anti-tumour immune response, is limited. In this study we investigate the effects of HT treatment using NIR on tumor regression and on the anti-tumor immune response in breast tumors. Results demonstrated that local HT by NIR at 43oC reduced tumor progression and prolonged the survival of tumor-bearing mice. Immunohistochemical analysis revealed a significant reduction in proliferation in treated tumor, which was accompanied by an abundance of heat shock protein 70 (Hsp70). Increased numbers of activated dendritic cells were observed in the draining lymph nodes of the mice, along with infiltration of T cells, NK cells and B cells into the tumor. In contrast, tumor-infiltrated regulatory T cells were largely diminished from the tumor. In addition, higher IFN-γ and lower IL-10 secretion was observed in blood of treated mice. Overall, this present study extends the understanding of using local HT by NIR to stimulate a favourable anti-tumor immune response against breast cancer.