Determining the effects of airborne particulates on immune and barrier epithelial cell function

Theme: Aerosols and Health

Start date: Cohort 1: 2019

Supervisors: Prof. Sheena Cruickshank (Manchester) and Dr. Alberto Gambaruto (Bristol)

Airborne pollution is a complex mixture of biological and chemical sources but their specific effects on immune function are relatively poorly understood. This exciting cross disciplinary project will define the components of pollutants and explore their impact on immune cells


Approximately 24%of the particulate matter that humans breathe in each day consists of biological substances such as bacteria and fungi. These biological particulates make up the earth’s microbiome. The microbiome plays important roles in human health and spread of disease as well as environmental processes, such as the water cycle. The microbiome is highly susceptive to the environment and has been shown to be significantly different depending on the environment and bioaerosols sources present. Most research in to bioaerosols is on non-biological components, or of infectious agents in high risk environments. Whereas this study, will focus mainly on non-pathogenic bacteria and fungi. Although, the exact extent of how airborne biological pollutants impacts human health is unknown. Recent studies have shown that there are significant health risks associated with particulate matter, as both biological and non-biological airborne particulates can trigger damage response pathways and lead to an immune response. 

The immune response is comprised of extensive mechanisms that protect the host from infectious agents. Two major components of the innate immune response are epithelial cells that provide a physical barrier against microorganisms and macrophages, that aid in killing of pathogens, as well as the initiation of a greater more specific immune response. When these cells come into contact with pathogenic organisms, it triggers a damage response and leads to the activation of the inflammasome. The inflammasome is a multimeric protein complex that is formed due to the presences of foreign or damage associated molecules. This leads to the activation of proteins within the macrophages and epithelial cells that combine in order to, secrete pro-inflammatory cytokines and cause pyroptosis, a form of inflammatory cell death, leading to the release of inflammatory mediators and the subsequent death of the invading microorganism. It has been shown in the previous studies that pathogenic bacteria, fungi and viruses can induce inflammasome activation. However, it is unknown whether non-2pathogenic bacteria and other airborne biological particulates can initiate the activation of the inflammasome and lead to an inflammatory state within the host. Therefore, determining what is present within the air with breathe in and how it affects the immune response is crucial and will be the aim of this project. 

In order to examine the microbiome and its effect on immune cells and epithelial cells. Particulate matter samples will be recorded in different environments, during different seasons, where the biological component of the samples will be collected onto a filter. Anovel technique will be developed in order to remove the biological contents from the filters, so identification of what is present can occur. With the extracted biological material examined using sequencing techniques such as 18s/16s and illumina. This will used to identify what is present within the atmosphere. Macrophages and epithelial cells will then be cultured with the biological components that have been collected. Expression of proteins associated with formation of the inflammasome will be examined by immunofluorescence and wester blotting, and expression of cell surface markers by flow cytometry. Whilst expression of cytokines associated with production of the inflammasome and are known mediators of an inflammatory immune response will be examined by ELISA. These tests will allow for the analysis of the immune response in relation to the airborne particulates and will act as an indicator as to how the environment is affecting our health.