Vaping: A sticky situation

E-cigarettes: Public Health England suggests they should be available on prescription; some people are taking them up for fun, while others are using it to help them quit smoking. In all cases there’s a strong belief that vaping is the healthier alternative to cigarettes. But a study out this week suggests that the inhaled vapour from e-cigarettes can make the cells that line our airways much stickier and increase the odds that bacteria like the pneumococcus - that can cause chest and other infections - can gain a foothold. Chris Smith spoke to Jonathan Grigg, a respiratory consultant at Queen Mary University of London.

Jonathan - Vaping is increasingly popular as a smoking cessation aid, and youngsters are taking up vaping itself, so it’s important that we understand the effects on the lung. What we’re looking at is the risk of developing a serious infection, that’s with a bug called the pneumococcus, and that causes pneumonia. We know that if you smoke cigarettes, you’re at a significantly increased risk of pneumonia, and the mechanism is that bugs just stick more to the airways and they can get a little niche and they can get a foothold in the airway and cause infection.

What we did is we put vape onto the human airway cells. We sort of expected not to see very much but, in fact, the cigarette vapour significantly increased the stickiness of the bugs to the cells in the same way as cigarette smoke.

Chris - Do you know how it makes them stickier?

Jonathan - The mechanism is really interesting. What the bug does is it hijacks a normal substance that’s expressed on the cells as a receptor so it uses it a trojan horse. It sort of sticks to that receptor and then as the receptor normally gets into the cell, the bug just moves across into the cells, so it’s like a hijack literally. What we saw was that vaping increased the amount of receptor on the cell and more bugs stuck to that receptor.

Chris - That’s in cells in a dish. But how confident are you that that represents what’s going on in one of your patients?

Jonathan - To address that, what we took was a group of vapers. We took little scrapes of the cells from their nose before they vaped during their normal vaping session and one hour after that. We looked for the expression of this receptor that the bugs can hijack and we found that the receptor was significantly increased at least a two or threefold increase after vaping.

Chris - Does that end up reflecting an increased risk of infection? Obviously you can’t do that with human patients, it would be unethical. Because, at the moment, all you can say is that it appears the cells get stickier, it appears that this is secondary to the vaping, but can you put the whole puzzle together and say vaping causes more infections?

Jonathan - You’re quite right. We haven’t translated that into a risk. It really needs large scale what we call epidemiological surveys to be able to do that in the same way as smoking. But what we did do is, in an animal model, we exposed animals to vape and infected them with the pneumococcus, and we found increased amounts of pneumococcus in the nose of vape exposed animals. So, at least in that situation, we saw an effect.

Chris - What about, I’ve classically heard it said if you go and wander round in London you may as well have smoked a packet of cigarettes if you walk down some streets because the traffic pollution is so significant, how do you quantify, qualify and standardise what you call vaping and the infection risk arising from it, and compare it to say just occupational exposure or day to day exposure to pollution?

Jonathan - I think that’s a very very important point. We’ve looked at various other exposures in our model which are known to be increased risk of pneumococcal infection and, as you say, diesel exhaust particles increase the risk, especially in young children, of bacterial pneumonia. Welding is an occupational exposure that increases that and in our model we see those effects. I think yes, just walking around a polluted environment is increasing your risk, as we know, but that doesn’t of course mean that vaping can be dismissed. This would be an additional risk to what is an unacceptable level of pollution we have in our cities.

Chris - Do you think it makes a difference what the composition of the vape fluid is because they come in lots of different flavours don’t they?

Jonathan - It potentially does. And what we can do now with our model is to play around, if you like, with the vape composition. We can make our own vape, we can look at the effect of just a major component which is propylene glycol, which is like a food additive on its own. We can add in the flavourings and, as you say, there are many hundreds of thousands of flavourings. So we can start doing these sort of experiments to scale and really nail down what are the components which are causing it. As yet, we think nicotine isn’t the major player although it has some effect, but what it is in the nicotine-free vape is unclear.