PO-420 Harnessing chitosan/Poly(Y)-glutamic acid nanoparticles for immunomodulation at the tumour microenvironment

Abstract

IntroductionThe tumour microenvironment is a complex and dynamic niche that has a fundamental role in tumour cell proliferation, angiogenesis, invasion and metastasis. Macrophages (Mac) are described as having a central role in tumour progression and dendritic cells (DC) as having an immature/immunosuppressive profile, which limits T cells activity. Therapeutic strategies targeting these cells have been emerging as adjuvants to anticancer conventional treatments, aiming at their recruitment and repolarization towards an immunostimulatory phenotype favouring cancer cell elimination. Here, we focused on the potential of Chitosan/Poly(γ-glutamic acid) nanoparticles (NPs) to modulate cellular immunity and, consequently, to affect cancer-cell related activities.Material and methodsNPs were prepared by co-acervation method. Primary human monocyte-derived M2 Mac (obtained by stimulation with IL-10) were incubated with NPs. Control experiments with unstimulated Mac and LPS-stimulated Mac (M1 phenotype) were performed. After 72 hour, cell metabolic activity, cell phenotype and cytokine production were evaluated. Mac ability to induce T cell proliferation/activation and tumour cell invasion were also assessed. The same studies were performed with human-monocyte derived DC. For in vivo models, 1 × 106 E0771 cells were injected in the mammary fat pad of C57BL/6 mice. After 10 days of tumour implantation, animals were treated every two days with NPs. Tumour growth was assessed by calliper every two days.Results and discussionsNPs re-educated IL-10-stimulated Mac towards a pro-inflammatory profile, decreasing CD163 expression and promoting IL-12p40 and TNF-α secretion. NPs also induced an immunostimulatory phenotype on DC, enhancing the expression of the co-stimulatory molecules CD86, CD40 and HLA-DR, and secretion of the pro-inflammatory cytokines TNF-α, IL-12 and IL-6. Interestingly, these phenotypic alterations induced both CD4+ and CD8+ T cell activation/proliferation and counteracted cancer cell invasion, in vitro. Regarding the in vivotumour model, we observed a decrease in tumour growth in NPs-treated animals comparing to the control, after 23 days of E0771 cell implantation. Additional experiments with other tumour models are currently being explored.ConclusionOverall, our findings open new perspectives on the use of NPs as an immunomodulatory therapy for tumour microenvironment reprogramming, providing a new tool for anticancer therapies.