Anti-Ly6G binding and trafficking mediate positive neutrophil selection to unleash the anti-tumor efficacy of radiation therapy.

ABSTRACT: The anti-Ly6G antibody is used to deplete Ly6G^pos neutrophils and study their role in diverse pathologies. However, depletion is never absolute, as Ly6G^low neutrophils resistant to depletion rapidly emerge. Studying the functionality of these residual neutrophils is necessary to interpret anti-Ly6G-based experimental designs. In vitro, we found anti-Ly6G binding induced Ly6G internalization, surface Ly6G paucity, and primed the oxidative burst of neutrophils upon TNF α co-stimulation. In vivo, we found neutrophils resistant to anti-Ly6G depletion exhibited anti-neutrophil-cytoplasmic-antibodies. In the pre-clinical Kras^{Lox-STOP-Lox-G12D/WT}; Trp53^Flox/Flox mouse lung tumor model, abnormal neutrophil accumulation and aging was accompanied with an N2-like SiglecF^pos polarization and ly6g downregulation. Consequently, SiglecF^pos neutrophils exposed to anti-Ly6G reverted to Ly6G^low and were resistant to depletion. Noting that anti-Ly6G mediated neutrophil depletion alone had no anti-tumor effect, we found a long-lasting rate of tumor regression (50%) by combining anti-Ly6G with radiation-therapy, in this model reputed to be refractory to standard anticancer therapies. Mechanistically, anti-Ly6G regulated neutrophil aging while radiation-therapy enhanced the homing of anti-Ly6G-boundSiglecF^neg neutrophils to tumors. This anti-tumor effect was recapitulated by G-CSF administration prior to RT and abrogated with an anti-TNFα antibody co-administration. In summary, we report that incomplete depletion of neutrophils using targeted antibodies can intrinsically promote their oxidative activity. This effect depends on antigen/antibody trafficking and can be harnessed locally using select delivery of radiation-therapy to impair tumor progression. This underutilized aspect of immune physiology may be adapted to expand the scope of neutrophil-related research.

SUBMITTER: Boivin G 

PROVIDER: S-EPMC7889163 | biostudies-literature |

REPOSITORIES: biostudies-literature