MECHANISMS THEME

Jonathan Grigg

Professor of Paediatric Respiratory and Environmental Medicine, Queen Mary University of London and BREATHE, Mechanisms Theme Leader.

The mechanism theme of the BREATHE-Africa consortium is led by Jonathan Grigg (Professor of Paediatric Respiratory and Environmental Medicine, Queen Mary University of London. A major focus of this theme is to identify the effects of sooty particles from biomass smoke on lower airway cells. The first question we have looked at is whether the cleaner cookstove used in the Cooking and Pneumonia study (CAPS) reduces the amount of sooty particles reaching the lungs of women. To do this, we measured the amount of soot in airway macrophages –cells that sit in the lower airway and can be sampled using “induced sputum” – and technique that involved women breathing a salty mist a coughing up cells for analysis. The picture shows an airway macrophage that has taken up inhaled soot – the area of blackness is an indicator of the amount of inhaled soot. In 2016, the Queen Mary research team (Dr Abi Whitehouse, and Lisa Miyashita) visited the CPAS study site in Chikwawa, and with the invaluable help and support of the local investigators, sampled airway macrophages from women using open fires for cooking and women cooking using the CAPS cleaner cookstove. The study threw up challenges, but obtaining sputum samples and transporting them each day to Blantyre worked well (pictures). The study is currently being submitted for publication.

Airways Microphages

Airways Microphages

The mechanisms theme also addresses the effect of biomass smoke particles on human airway cells cultured in in the laboratory. Richard van Zyl-Smit (Head of the Lung Clinical Research Unit, University of Cape Town) and Rosa Chang (his PhD student), have shown that combining the individual components of inhaled toxins, at levels that do not individually damage airway cells, cause cell damage. They are now looking at the effects of smoke extracts on infection (both pneumococcal and mycobacterial). Data from their study will be presented at the 2017 American Thoracic Society Annual meeting(ID 5180 The Differential Toxicity of Inhaled Household Air Pollutants: Wood Smoke, Tobacco and Electronic Cigarettes).


Rosa Chang

PhD student for Mechanisms Theme at the University of Cape Town

A comparative study on the effects of smoke exposure on host immunity in response to bacterial infection

Carbon black particles

Carbon black particles

The overarching aim of our project is to understand the effects of indoor air pollution on respiratory health by characterising the relative effects of air pollutants, such as particulate matter from wood smoke, carbon black, cigarette smoke and electronic cigarette vapour, using in vitro cell models appropriate to the susceptibility of pneumococcal and mycobacterial infection. Our aims include evaluating the toxicity of the various components of air pollutants on the cells and determining if the uptake of Mycobacterium tuberculosis or Streptococcus pneumonia is impaired by the air pollutants. We will then investigate the immunological response and the ability of the cells to contain or kill the bacteria in response to infection and exposure to the air pollutants. The in vitro models we will be using in this study includes the epithelial cell line, A549; and human monocyte-derived macrophages (MDMs). Last year, we successfully optimised the protocol to generate classically activated (M1) MDMs from monocytes isolated from human blood. We then used flow cytometry to confirm that the majority of the macrophages were indeed the M1 phenotype. We subsequently proceeded to look at the cytotoxicity of cells in response to the air pollutants. Toxicity was determined spectrophotometrically using the lactate dehydrogenase (LDH) assay.  We have completed the cytotoxicity assays using various concentrations of nicotine, pure carbon black, cigarette smoke extract, electronic cigarette smoke extract and particulate matter; and are now at the stage of completing the cytotoxicity experiments of the additive/combination exposures in the 2 cell models.Following this, we will decide on the specific concentrations to use for future experiments; and study the effects of the various components of air pollution on the bacterial uptake by our in vitro models.