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Researchers think they've finally figured out why bacteria only causes acne in some people

And how to stop it.

FIONA MACDONALD
31 OCT 2016
 

Despite the fact that up to 80 percent of us will experience the living nightmare that is acne at some point in our lives, scientists still don't really understand what causes the condition, and more importantly, how to stop it. 

But a new study might have finally figured out why skin bacteria only causes inflammation in some people and not others - and the discovery could lead to new acne treatments in as little as two years.

 

Right now, doctors treat severe acne with either antibiotics, hormone regulators (such as the contraceptive pill), or isoretinoin - better known as Roaccutane.

All of these come with side effects (some more severe than others), and worst of all, most of them don't offer long-term relief, or in some cases, they don't work at all

It's been years since any new types of acne treatments have been added - so new insight into the condition is long overdue.

The new study focussed on the fact that pretty much all of our skin is covered in bacteria all of the time - after all, it's the first line of defence against invading germs.

But despite this constant coating of bacteria, many people never experience breakouts, while others can't get rid of them no matter what they try.

"It's a big puzzle as to why we tolerate all these bacteria on our skin," lead researcher Richard Gallo from the University of California, San Diego, told MedicalXpress. "Usually, we walk around at peace with them. But at certain times, that detente breaks down and you get an infection."

 

Now, for the first time, the team thinks they've discovered what causes this crucial difference.

Gallo and his colleagues showed that a usually harmless bacterium that lives on our skin starts triggering inflammation and breakouts when it finds itself trapped in airless, oily conditions, such as hair follicles.

But not everyone's hair follicles are created equal, and that could explain why not everyone gets acne - some people might simply have hair follicles that are more suffocating than others.

This might not only explain the root causes of acne - it could also reveal a whole new pathway through which bacteria trigger inflammation, and that could help scientists understand a range of different infections.

The researchers specifically looked at a type of bacterium known as Propionibacterium acneswhich - as the name suggests - can cause acne breakouts.

Most of us have P. acnes on our face all the time, but it doesn't always cause breakouts. So the team tested the bacteria under a range of conditions on the skin of mice to try and figure out what was going on.

They showed that when trapped in airless environments alongside hair and skin cells, P. acnes turned sebum - the oil found on our skin - into fatty acids that activate inflammation in nearby skin cells.

Usually this inflammation is switched off by enzymes called histone deacetylases, but the fatty acids produced by the bacteria deactivated that brake, so inflammation continued unchecked - going on to cause red, itchy breakouts.

So far, the research has only been done on mice, but the team is now looking to replicate their results in humans, and they're hopeful that the inflammation pathway involved will be the same.

"For the first time, it shows how fatty acids derived from P. acnes act on skin cells to induce inflammation," Holger Brüggemann, an expert on skin bacterium from Aarhus University in Denmark, who wasn't involved in the study, told Andy Coghlan at New Scientist.

Brüggemann added that the new findings could also explain why teenagers are so prone to breakouts, because their sex hormones during puberty put their sebum production into overdrive, giving P. acnes more fuel.

The bad news is that cleaning your face regularly isn't the answer, because the team showed that the bacteria clump together to form structures called biofilms, which effectively locks them onto your skin.

And, when this type of bacterium isn't causing havoc inside suffocating hair follicles, P. acnes is actually beneficial to skin health, which explains why antibiotic treatments don't work for many people - and in some cases, can actually make things worse.

But now that the team understands the root cause of the inflammation, they're confident they'll be able to come up with new treatments for acne.

“We can either inhibit these fatty acids, or block their impact on the skin," Gallo told New Scientist. "We're working on how to do this ... If we get lucky, it could lead to new medications in two to five years."

The researchers now want to investigate what it is specifically that makes some people's faces more susceptible to acne. In addition to having particularly suffocating hair follicles, they might also be genetically disposed to being more vulnerable to the inflammation triggered by P. acnes fatty acids.

Or maybe the strains of bacteria they have on their skin make excessive amounts of fatty acids compared to other people's strains. "I think all of these aspects probably play a role," said Gallo. 

Once they've figured this out, they'll be a step closer to not only treating, but potentially preventing acne in the first place. Which would be a huge relief for all of us who've suffered the debilitating self-consciousness and pain of having breakouts. 

The research has been published in Science Inflammation.

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