The Anatomy of The Skin
Before we can begin to understand acne it is important that we know a little about the anatomy of the skin.
To begin with, contrary to what you may think, the skin is an organ and in fact, the largest organ of the human body covering an area of about 20 square feet. The skin has many functions some of the most important are to protect us from bacteria and environmental pollutants, help to regulate our body temperature and permits us to detect changes in our environment through the sensations of, touch, cold, and heat.
The skin is composed of three layers. The outermost layer, the epidermis, is a waterproof barrier that comes in constant contact with our environment. It is continuously exposed to and protects us from bacteria, viruses, dirt, and a myriad of contaminants that pollute the air around us. The epidermis also contains Melanocytes which are the pigment producing cells responsible for giving the skin its various colors.
The next layer beneath the epidermis is called the dermis and is composed of connective tissue, hair follicles and sweat glands. This combination of a hair follicle and a sweat gland is commonly referred to as the pilo-sebaceous unit and a disease of this unit is what we commonly refer to as acne. The many causes of the disease of this unit will be discussed later on under the section of the Causes of Acne.
The third layer of the skin is referred to as the hypodermis and
composed largely of connective tissue and fat.
Acne is a condition characterized by inflammation of the pilo-sebaceous unit consisting of the hair follicles and their associated sweat glands that produce an oily substance called sebum. As a result, acne can appear anywhere on the body that has a high concentration of these structures like the face, chest, and back.
Acne can be grouped into two categories, adolescent acne and adult acne. Acne is most prevalent among adolescents representing approximately 90% of the cases and is seen in both males and females. The remaining 10% of acne cases are seen in adults and is predominant in females between the ages of 40 and 50.
It is generally understood that acne is caused by a multiplicity of factors. One of the most important factors is that individuals who suffer from acne demonstrate an increase in sebum production. Inflammation of the follicle secondary to proliferation of the bacteria Propionibacterium acnes which becomes trapped within the follicle due to over- production of sebum combining with sloughed dead skin cells forming a plug that traps the bacteria. It is now believed that P acnes is not directly responsible for the infection but rather sets up an inflammatory response within the follicle.
Antibiotics, especially the tetracyclines have been used to kill the bacteria that are responsible for establishing the inflammatory conditions that can cause acne. The big problem with using antibiotics is that over time the bacteria become resistant and the antibiotic loses its effectiveness.
A relatively new treatment for acne. Azelaic acid is a nonodecanoic acid derived from grains and other plants like coconuts. It is effective against both acne vulgaris as well as rosacea. Unlike other acne treatments azelaic acid is not only active against the active inflammatory phase of acne but is also effective in reducing the appearance of the side effects of acne like hyperpigmentation and scarring.
Azelaic acid has a triple action in combating acne. Firstly, it is bacteriacidal against the bacteria responsible for acne Proprionbacillus acnes, but it has anti-tyrosinase activity. Tyrosinsase is the enzyme necessary to convert tyrosine into the skin pigment melanin. By blocking this enzyme abnormal amounts of melanin produced by chronic inflammation are prevented from forming the dark spots frequently seen following repeated acne eruptions.
Of all the acne treatments available, my personal favorite is the azelaic acid, because it is natural. It effectively deals with pimples and also addresses the complications frequently associated with acne, without excessive drying of the skin.
Benzoyl peroxide has been around since the 1920’s and was the first organic peroxide intentionally synthesized. It is the main component in many of today’s acne products.
Benzoyl peroxide breaks down when it comes in contact with skin into benzoic acid and oxygen. Although neither is particularly toxic it does not necessarily mean that BP is safe. Benzoyl peroxide’s action as an oxidizing agent can be corrosive to the skin as well as having bleaching properties.
Tretinoin is the acid form of Vitamin A. It is available as Retin-A, Atralin, Renova, Airol, Avita, and Retacnyl to name just a few. Salicylic Acid from the latin “salix”, willow tree, from whose bark the substance was originally obtained is a type of phenolic acid and a beta hydroxy acid. SA is a keratolytic agent that works by exfoliating the skin to unplug clogged pores where trapped dirt, skin oils, and bacteria reside. By allowing the pores to drain and eliminating the source of the inflammation pimples and blemishes can begin to heal.
The disadvantage to SA is that it is effective as a spot treatment and not well suited for use over wide areas of the face. It is also not effective in addressing the complications often associated with acne like scarring and post-inflammatory hyperpigmentation.