August 17, 2017

expert reaction to study reporting that air pollution nanoparticles can affect peptides in the immune system

Researchers publishing in The Journal of Immunology report that air pollution nanoparticles can affect peptides in the immune system and they suggest they could potentially lead to an increased susceptibility to infection.

Prof. Anthony Frew, Professor of Allergy & Respiratory Medicine, Royal Sussex County Hospital, said:

“The work itself has been done well, but readers should note that this is a pretty artificial model using carbon particles, not working with real pollution. The target mechanism is just one of a number of ways that the body fights off bacteria. So the data are interesting but they have no direct relevance to current discussions about the health effects of particulate pollution.”

Dr Sheena Cruickshank, Senior Lecturer in Immunology, University of Manchester, & British Society for Immunology spokesperson, said:

“This interesting study shows that incubation of carbon nanomaterials can inhibit the function of one of our anti-bacterial peptides. However it is not clear how the carbon nanomaterials reflect our physiological exposure to the complex cocktail of pollutants (which include particulate matter (PM2.5 and PM10) such as sulphur dioxide, nitrogen oxide particles and carbon monoxide) as the work was purely done in cell model systems.

“Furthermore, the immune system has multiple layers of defence, including other anti-bacterial products and a variety of effector cells, and only one anti-bacterial product is assessed in this paper; therefore much more work needs to be done to assess the significance of this finding. However, this is an interesting, albeit relatively preliminary, study that suggests this is an important research area which should be investigated further.”

Prof. Kevin McConway, Emeritus Professor of Applied Statistics, The Open University, said:

“My main expertise is in statistics. As usual, there are statistical aspects of the laboratory science in this research. I’ve looked at those, and I see no problem with them.

“It’s very important to be clear, though, about what these researchers actually found. In their lab, they investigated interactions between artificially synthesised molecules a type of antimicrobial peptide, that have the same chemical and physical structure as certain molecules in the human immune system, and tiny carbon nanoparticles. The nanoparticles they used were not directly “found in traffic fumes”, as the press release perhaps implies – there are carbon nanoparticles, alongside a lot of other things, in traffic fumes, but those used in this research came from a chemical supplier.  I am not an immunologist or lab scientist, but I believe they found good evidence that, in this laboratory situation, the nanoparticles can interfere with the properties of the molecules and with their biological actions against microbes. But that’s a long way from saying that the same mechanisms work in the same way in real human bodies exposed to real, complex, traffic fumes, and even further from showing that they can actually cause illness. In the actual research paper, the researchers, rightly in my view, go no further than saying that their results suggest that this kind of interaction between the antimicrobial peptides and nanoparticles “could result in an increased susceptibility to infection”, and they call for further research on other nanomaterials and other molecules in the human immune system. That’s fine, but it’s a long way from the top line “Pollution can make you ill, say researchers” in the press release. A more accurate top line might have been something like “A substance present in air pollution interferes with a chemical present in the human immune system,” but that probably just shows why I’m a statistician.”

* ‘Carbon Nanoparticles Inhibit the Antimicrobial Activities of the Human Cathelicidin LL-37 through Structural Alteration’ by Findlay et al. was published in The Journal of Immunology.

All our previous output on this subject can be seen at this weblink: http://www.sciencemediacentre.org/?s=air%20pollution&cat

Declared interests

Prof. Anthony Frew: “No relevant interests to declare.”

Dr Sheena Cruickshank: No conflicts of interest.

Prof. Kevin McConway: No conflicts of interest.