Blocking of TGFβ Signaling Using a Novel Platform for Neutrophil Specific Targeting Prevents Metastasis

Introduction

In recent years, our understanding of neutrophil function in health and disease is rapidly expanding. However, neutrophils were never regarded as an attractive therapeutic target due to their short half-life. Here we present a novel in-vivo platform for neutrophil-specific drug delivery which may be exploited therapeutically.

Material and Method

We used a phage display library to screen for short peptides binding specifically to mouse and human neutrophils. The selected peptides were used to decorate PLGA nanoparticles (NP) containing SB431542 (TGFβ inhibitor). We then tested the therapeutic effect of neutrophil specific nanoparticles containing SB431542 in a preclinical model of metastatic breast cancer.

Results and Discussion

Using phage display screen combined with next generation sequencing, we identified several peptides specifically binding to mouse and human neutrophils. We identified the binding partner of the peptides as the neutrophil-specific surface protein CD177 and show co-localization of peptide and receptor by super resolution microscopy (STORM). Further, we employ these peptides to decorate biodegradable PLGA NP and achieve highly specific NP uptake by neutrophils ex vivo and in vivo. We then used SB431542 containing NP to inhibit TGFβ signaling in murine neutrophils to preserve their anti-tumor properties in context of cancer. SB431542 containing NP effectively blocked TGFβ induced phosphorylation of Smad2 in neutrophils ex vivo. Importantly, we show that treatment of tumor-bearing mice with SB431542 containing neutrophil-specific PLGA NP prevents metastatic outgrowth.

Conclusion

We have generated a novel platform for neutrophil-specific drug delivery employing peptide-decorated PLGA NP. These NP can be loaded with any drug of choice and may be used for manipulating neutrophil activity in cancer and other inflammatory diseases. Thus far neutrophils were rarely considered as a valid target for immunotherapy. This novel platform allows the modification of neutrophil function, in a specific manner in vivo, and may revolutionize immunotherapy by adding neutrophils to the therapeutic arsenal.