Most of the time, we live in peaceful coexistence with the numerous bacteria that live on our skin. But sometimes we live through the indignity of acne, particularly when we were adolescents. Despite being such a common condition, we really do not have a good understanding what triggers acne. We also don’t know why the skin bacteria can suddenly cause the inflammation responsible for acne in some people but not others.
Acne can affect all people, regardless of race or age. It is estimated that 80 percent of people aged 11 to 30 will experience an acne outbreak and it is most common among teenagers. Acne arises in the oil glands of the skin that produce an oily substance called sebum. Pores connect the oil glands to the surface of the skin by a canal called a follicle through which a thin hair also grows. When the skin follicle becomes plugged, inflammation starts a swelling that eventually develops into a pimple.
The causes of acne are not well understood but several factors might be responsible, including increases in hormone levels in the teenage years, hormone changes during pregnancy, starting or stopping birth control pills, heredity, some medications and greasy makeup. There are also many myths about the causes of acne that are simply not true including dirty skin, stress, chocolate and greasy foods.
Researchers discovered that when a normally harmless skin bacterium called Propionibacterium acnes ends up trapped in airless, oily conditions deep in a hair follicle, it can trigger inflammation leading to acne. Under airless conditions, the bacteria converts the sebum into fatty acids. The fatty acids in turn inactivate enzymes called histone deacetylases that normally reduce inflammation. Without that control, a cascade of molecules is released that increases inflammation leading ultimately to acne.
So why are some people more prone to getting acne? It might be that their follicles are more likely to get plugged or they are more sensitive to the effects of the fatty acids produced by the trapped bacteria. Another possibility is that some people carry different types of Propionibacterium acnes that make excessive amounts of the fatty acids or a combination of these reasons. Teenagers are more vulnerable to acne because the hormones trigger increased production of sebum that leads to more fatty acid production.
There are a variety of over-the-counter acne treatments that can be effective. Prescription topical or oral medications can also be given. These include topical treatments such as retinoids, derivatives of vitamin A that prevent the plugging of pores or antibiotics that kill bacteria. Oral medications also include antibiotics, or hormone regulators such as birth control pills. For those whose acne is severe or does not respond to other treatments, isoretinoin is used which decreases oil production. Unfortunately, many of these treatments have significant side effects.
These results could lead to the development of novel acne treatments that might have fewer side effects. This could make the teenage years of acne more manageable and save future teens the embarrassment of the pimple that invariably appears the day before the prom.