How to Address the Adjuvant Effects of Nanoparticles on the Immune System.

Alexia Feray,Emilie Brun,Armelle Biola-Vidamment,Natacha Szely,Eléonore Guillet,Marie Hullo,François-Xavier Legrand,Marc Pallardy

doi:10.3390/nano10030425

Abstract

As the nanotechnology market expands and the prevalence of allergic diseases keeps increasing, the knowledge gap on the capacity of nanomaterials to cause or exacerbate allergic outcomes needs more than ever to be filled. Engineered nanoparticles (NP) could have an adjuvant effect on the immune system as previously demonstrated for particulate air pollution. This effect would be the consequence of the recognition of NP as immune danger signals by dendritic cells (DCs). The aim of this work was to set up an in vitro method to functionally assess this effect using amorphous silica NP as a prototype. Most studies in this field are restricted to the evaluation of DCs maturation, generally of murine origin, through a limited phenotypic analysis. As it is essential to also consider the functional consequences of NP-induced DC altered phenotype on T-cells biology, we developed an allogeneic co-culture model of human monocyte-derived DCs (MoDCs) and CD4+ T-cells. We demonstrated that DC: T-cell ratios were a critical parameter to correctly measure the influence of NP danger signals through allogeneic co-culture. Moreover, to better visualize the effect of NP while minimizing the basal proliferation inherent to the model, we recommend testing three different ratios, preferably after five days of co-culture.

Highlights

With the widespread production and use of nanomaterials, the growing exposure of workers and of consumers in everyday life raises concerns about potential health risks [1], strengthening the need for relevant methods to evaluate their immunosafety [2]
We showed that amorphous silica nanoparticles (aSNP) (12.5 μg·mL−1 and 25 μg·mL−1) increased the expression of CD83, CD86 and CXCR4 markers on human dendritic cells (DCs) in a concentration-dependent manner, suggesting that these aSNP significantly affected monocyte-derived DCs (MoDCs) maturation (Feray et al, in preparation)
We showed that the DC:T-cell ratios and the duration of the co-culture are critical parameters to correctly measure the influence of danger signals induced by NP in an allogeneic co-culture

Summary

Introduction

With the widespread production and use of nanomaterials, the growing exposure of workers and of consumers in everyday life raises concerns about potential health risks [1], strengthening the need for relevant methods to evaluate their immunosafety [2]. The challenge is to select the most relevant cells and endpoints using a simple, robust and representative model. Most of the work regarding NP-induced immunomodulation has been focused on the activation of key immune cells [6,7,8]. Innate immune cells such as macrophages and dendritic cells (DCs) are predominantly exposed to nanomaterials due to their phagocytic properties and to their relative abundance at the entry sites such as skin, airways or the gastrointestinal tract [9]. DCs patrolling the blood or residing in peripheral tissues actively capture NP [10]

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