Tumor-Associated Neutrophils Dampen Adaptive Immunity and Promote Cutaneous Squamous Cell Carcinoma Development

• Main Authors: Sokchea Khou, Alexandra Popa, Carmelo Luci, Franck Bihl, Aida Meghraoui-Kheddar, Pierre Bourdely, Emie Salavagione, Estelle Cosson, Alain Rubod, Julie Cazareth, Pascal Barbry, Bernard Mari, Roger Rezzonico, Fabienne Anjuère, Veronique M. Braud
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Cancers
• Subjects: neutrophils; cutaneous squamous cell carcinoma; PD-1; PD-L1; gene expression profile
• Online Access: https://www.mdpi.com/2072-6694/12/7/1860

Cutaneous squamous cell carcinoma (cSCC) development has been linked to immune dysfunctions but the mechanisms are still unclear. Here, we report a progressive infiltration of tumor-associated neutrophils (TANs) in precancerous and established cSCC lesions from chemically induced skin carcinogenesis. Comparative in-depth gene expression analyses identified a predominant protumor gene expression signature of TANs in lesions compared to their respective surrounding skin. In addition, in vivo depletion of neutrophils delayed tumor growth and significantly increased the frequency of proliferating IFN-γ (interferon-γ)-producing CD8+ T cells. Mechanisms that limited antitumor responses involved high arginase activity, production of reactive oxygen species (ROS) and nitrite (NO), and the expression of programmed death-ligand 1 (PD-L1) on TAN, concomitantly with an induction of PD-1 on CD8⁺ T cells, which correlated with tumor size. Our data highlight the relevance of targeting neutrophils and PD-L1-PD-1 (programmed death-1) interaction in the treatment of cSCC.