Abstract
Although the importance of the tumor immune environment for the modulation of tumorigenesis and tumor regression is becoming increasingly clear, most of the research related to tumor-immune therapies has focused on adaptive immune cells, while the role and regulation of innate leukocytes such as neutrophils remains controversial and less defined. Here we observed that the selective deletion of Tollip, a key innate immune-cell modulator, led to enhanced tumor immune surveillance in a chemically induced colorectal cancer model. Tollip-deficient neutrophils significantly elevated T cell activation through enhanced expression of the costimulatory molecule CD80, and reduced expression of the inhibitory molecule PD-L1. Mechanistically, Tollip deficiency increased STAT5 and reduced STAT1, the transcription factors responsible for the expression of CD80 and PD-L1, respectively. Through adoptive transfer, we demonstrate that Tollip-deficient neutrophils, but not Tollip-deficient monocytes, are sufficient to drive enhanced tumor immune surveillance and reduced colorectal cancer burden in vivo. Our data reveal a strategy for the reprogramming of neutrophil functions conducive for the enhancement of the antitumor immune environment.