Clean Yourself with Dirt!

Inside a Boston lab, scientists from AOBiome are doing away with conventional personal hygiene practices in an effort to help sufferers of inflammatory skin conditions. Founded in 2015, AOBiome offers ways to repair our skin, not with soap and ointment, but instead by washing regularly with bacteria—don’t worry, its far less crazy than it sounds.
Our skin is our barrier to the world, and it takes a beating every day from airborne chemicals, surfactants, aerosols, and countless potential pathogens. Keratinocytes are the soldiers making up 90% of your skin’s defenses. Their job is to protect your more vulnerable tissues from potential harm by UV radiation, heat damage and desiccation.


Your skin cells are 90% keratinocytes – which defend you from external damage.

If a pathogen breaches your keratinocyte’s defenses, they send the first alarm signals to your body’s immune system, attracting leukocytes and activating the inflammatory response.
Our skin’s microbiota is like a soldier’s body armor—protection from attack. We are colonized by trillions of microbes. Some are inert, just coming along for the ride, some actively benefit us by bolstering our immune defenses, and others are the disease-causing nasties (although they tend to exist in a ‘disarmed’ state).
For one of these potentially harmful colonizers to begin causing damage, they need an environment that allows their population to reach a critical mass, or an opportunity to access the softer tissues beneath your skin. Fortunately for us, their numbers are kept in check by competition with the harmless bacteria for niche space. Direct, destructive warfare between the harmless and harmful populations also significantly thins the disease-causing bacteria’s populations. For example, bacteria inside your nose secrete antibiotics that kill other bacteria you breathe in. Others will train the immune system so it becomes more focused on killing just the pathogenic bacteria. Unfortunately for us, many modern hygiene regimens are actually detrimental to our microbiome, and can compromise the health of our skin.
Propionibacterium acnes is a commensal bacterium that resides in your skin’s pores. It eats cellular debris and skin oils, and usually doesn’t cause any trouble. As the name suggests, it is also the causative agent of the painful, and potentially disfiguring skin condition, acne vulgaris.
In the US alone, over $3B a year is spent treating acne.  It is most often caused by a perfect storm of teenage hormones increasing skin oil production and a genetic propensity to increased skin shedding that blocks pores. A blocked oily pore becomes the perfect niche environment for P. acnes to grow rapidly in isolation, uncontested.


Progression of acne (image from OpenStax College – Anatomy & Physiology, Connexions – WikiCommons)
 
As P. acnes feeds, it secretes enzymes to break its food into smaller chunks. Usually this has no effect on your skin, however when the population is high, these enzymes begin to destabilize and damage the keratinocyte’s cell walls. Keratinocytes signal to immune cells that they are under attack by a pathogen, and also signal to start the inflammatory response. Leukocytes arrive at the site of infection, and all-out war begins. This manifests as a large, painful swelling.
As immune cells die, they release a large number of alarm signals attracting more immune cells. When a significant number of immune cells die, the swelling becomes a white-headed pustule. There is often an urge to pick these pustules, but doing so can cause severe scarring.


Popping acne is often hard to resist, but can seriously damage the skin.

AOBiome treats acne by blocking P. acnes from unintentionally activating an immune response. They do so by introducing a new beneficial colonizer to your skin microbiome, in the same way as probiotic yogurt will introduce microbiome-enhancing cultures to help your gut. The colonizer AOBiome uses is called Nitrosomonas eutropha. N. eutrophacomes from a family of ammonia-oxidizing bacteria (AOB), that are unable to cause disease, and characteristically feed on nitrogen-containing compounds like ammonia and urea (found in your sweat), metabolizing it into to the chemical nitric oxide.
On their website AOBiome explain that like any other animals, our bodies were once likely colonized by AOB. However, the nature of this bacteria’s metabolism makes it highly vulnerable to surfactants like those found in shower soaps. When these products became commonplace, populations of AOB were completely wiped out, leaving our skin surface starved of nitric oxide.
Nitric oxide is already created within your cells to regulate the immune response. Its precise function is complex, up- or down-regulating various parts of immune signaling depending on stimulus or location within the body. According to research that used nitric oxide attached to nanoparticles to study its effect on P. acnes infection, nitric oxide can directly quell the specific immune alarms that the damaged keratinocytes send out. Nitric oxide was also shown to directly kill P. acnes, while being harmless to human cells.
By allowing N. eutropha to colonize your skin, they will metabolize compounds that your body naturally secretes, and in turn secrete a compound that fights inflammation and infection induced by P. acnes.
Midway through 2016, AOBiome are at phase 3 testing for their acne treatment, but N. eutropha colonization could also aid with a swath of additional of skin conditions. AOBiome are already in phase two for a AOB treatment for rosacea (an immune disorder that causes a permanent flush-like redness of the face) and pediatric dermatitis (an immune disorder that is the most common cause of skin eczema). They are in phase one testing for allergic rhinitis (an inflammation of the nasal passages from pollen, commonly known as hayfever), and in the preclinical phase for a number of other disorders as well.
AOBiome’s sister company Mother Dirt is based upon the same AOB principles, and offers microbiome-friendly cosmetics, and probiotics to boost your skin microbiome.
We are only beginning to understand the impacts our microbiological army has on our health. It is a relationship that has evolved over millions of years, and we are beginning to realize negative effects that modern lifestyles have on these important members of our immune system. Modern solutions like AOBiome can repair some of the damage done. At SynBioBeta London 2016, a number of talks discussed microbiomes and health, and microbiome enhancement is becoming a very potent practice to improve everyday health. Engineering our microbiome with synthetic biology is also in the early stages of investigation (see our article “You are only 50% you” for more information), as there is a potential to treat difficult diseases that drugs cannot reach using an enhanced bacterial population.
In the near future, expect to see great, promising advances in the microbiome enhancement field as our understanding of this tiny, complex and health-vital world improves. For now, consider your bacterial armies as a part of you. We spend so much effort and money keeping ourselves healthy – we should pay equal attention to keeping our friendly hitchhikers healthy too!