Source: Thailand Medical News Jan 27, 2020 4 years, 9 months, 3 weeks, 4 days, 14 hours, 19 minutes ago
According to a new study, published in the
Journal of Allergy and Clinical Immunology, exposure to
diesel exhaust particles (
DEPs) can increase an individual's susceptibility to
pneumococcal disease.
Typically, the bacterium
Streptococcus pneumoniae is the most common cause of
pneumonia and
meningitis and the leading cause of infectious disease deaths in under-5s and elderly groups worldwide. In the majority of healthy people, this bacterium lives harmlessly in the back of the nose and throat without causing any symptom. However, if the
pneumococcus gains access to normally sterile sites in the body, such as the lungs and blood, it has the potential to cause life-threatening diseases.
To explore more about the conditions that allow this ordinarily harmless bacterium to progress into such severe invasive diseases researchers from the University of Liverpool, Queen Mary's University, London and Trinity College Dublin, conducted a study examining the role of DEPs in the development of
pneumococcal disease.
The WHO or World Health Organisation estimates that
air pollution is responsible for 7 million deaths per year, with 7% of these attributable to pneumonia. An estimated 37% of the world's population live in areas where levels of
airborne pollution exceed WHO guideline limits.
Diesel exhaust particles or
DEPs, a major component of
air pollution worldwide, is the particulate component of diesel exhaust, which includes diesel soot and aerosols such as ash particulates, metallic abrasion particles, sulphates, and silicates.
The medical researchers, led by Professor Dr Aras Kadioglu from the University of Liverpool's Institute of Infection & Global Health, used a combination of mouse models and lab-based assays in both mouse and human cells to provide insight into the link between DEP exposure and
pneumococcal disease.
The medical researchers found that following exposure to
DEPs, airway macrophages, which are key immune cells for controlling bacterial infections and removing debris from the body, become congested with DEPs, reducing their ability to kill the
pneumococcus. This allows the bacteria to survive more easily in the airways, invade the lungs, and cause significant inflammation, which eventually leads to bacterial translocation into blood, thereby causing severe disease.
Dr Kadioglu, told
Thailand Medical News, "We know that exposure to air pollution is harmful, responsible for millions of deaths every year, of which a significant proportion is due to
pneumonia. What we did not know however, was how
air pollution, such as
diesel exhaust particles, actually causes airway disease. In this s
tudy, we have now discovered the cellular mechanisms behind this. Our study highlights an urgent need to tackle airway
pollution if we are to reduce life threatening respiratory diseases such as
pneumonia."
"Our study shows that exposure to
DEPs, which is a major airborne particulate pollutant both here in the UK and abroad, may be one of the key factors involved in the switch from harmless
pneumococcal colonisation of the nasal tissues to severe disease, such as
pneumonia." commented Dr. Rebecca Shears, who is first author of the study.”
She added,"Our data provides further insight to support previous observations of increased
pneumonia hospital admissions in countries such as China, where airborne
pollution levels are highest. The reduced ability of
DEP exposed airway macrophages to control the infection appears to be key in the increased number of cases of
pneumococcal disease. This study adds further impetus to reduce global
air pollution levels."
Reference : 'Exposure to diesel exhaust particles increases susceptibility to invasive pneumococcal disease', Journal of Allergy and Clinical Immunology (2020).,Rebecca K. Shears, PhD,Laura C. Jacques, PhD,Georgia Naylor, MBiol,Lisa Miyashita, PhD, Shadia Khandaker, PhD,Filipa Lebre, PhD, Ed C. Lavelle, PhD, Jonathan Grigg, MD FRCPCH,Neil French, PhD FRCP,Daniel R. Neill, PhD,Aras Kadioglu, PhD DOI: https://doi.org/10.1016/j.jaci.2019.11.039
