A Study of the Immune Responses to Therapeutic Inhaled Nanoparticles by Lung Alveolar Macrophages

Abstract

The robustness and versatility of lipid nanoparticles (LNP) have attracted attention in the research field as they can be engineered to transport drugs via the enteral and the parenteral routes, to diseased target organs. Administration by inhalation allows direct access to the lungs therefore lipid nanoparticles serve as good candidates for delivering nanomedicines to treat chronic pulmonary diseases. As the most abundant resident immune cell in the lung, alveolar macrophages (AM) play an important role in patrolling and protecting the lung. Inhaled LNP encapsulating therapeutics would be perceived as non-self by AMs that would internalize the LNP. To be considered as a viable medicine, LNP would have to evade macrophage uptake, however little is known about the molecular features that dictate their uptake. The aim of this study is to understand the properties of LNP that determine their uptake as a means to improve LNP formulation, to suppress internalization by macrophages. The imortalised macrophage cell line ,THP-1, were first used to understand the general response of phagocytes to LNP. We then move onto MH-S cells, a murine alveolar macrophage cell line, that are a better representation of macrophages in the lung. We show that LNP labelled with the hydrophobic, lipophilic fluorescent dye DiD are internalised by both THP-1 and MH-S cells. We further show, using flow cytometry, that LNP internalisation into THP-1 and MH-S cells occurs at 37°C and not at 4°C. Furthermore, internalization of LNP was linear: the longer the incubation time of THP-1 and MH-S with LNP, the more LNP internalized. In this thesis we describe the impact LNP have on macrophage activation. As a gene delivery device, LNP successfully enter cells linearly over time but results showing activation following uptake warrant further investigation on the safety and efficacy of LNP to assess their competency as a therapeutic in humans.

Date of Award	31 Jan 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Jeremy Derrick (Main Supervisor), Jian Lu (Co Supervisor) & Tracy Hussell (Co Supervisor)