Massively recruited sTLR9+ neutrophils in rapidly formed nodules at the site of tumor cell inoculation and their contribution to a pro-tumor microenvironment

In this study, we unexpectedly found a subcutaneous nodule in the groin areas of mice inoculated with tumor cells. The nodule was developed 24  h after the inoculation, filled with tumor cells and massively recruited neutrophils, being designated as tumor nodules. 22% of the neutrophils in tumor nodules are surface TLR9 (sTLR9) expressing neutrophils (sTLR9+ neutrophils). With tumor progression, sTLR9+ neutrophils were sustainably increased in tumor nodules/tumor tissues, reaching to 90.8% on day 13 after inoculation, with increased expression of IL-10 and decreased or no expression of TNF α. In vivo administration of CpG 5805 significantly reduced sTLR9 expression of the sTLR9+ neutrophils. The reduction of sTLR9 on neutrophils in tumor nodules contributed to the induction of an anti-tumor microenvironment conductive to the inhibition of tumor growth. Overall, the study provides insights for understanding the role of sTLR9+ neutrophils in the tumor development, especially in the early stage.Graphical abstract
Source: Cancer Immunology, Immunotherapy - Category: Cancer & Oncology Source Type: research