Acne - pathogenetic mechanism. First article

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I named this article this way because there is so much to write about acne that I thought about creating a separate section on the disease. First of all, I want to say that acne is not "dirty" skin. People with acne take a good care of their skin to avoid acne. Their daily struggle in front of the mirror is hard enough for the self-esteem and they do not need unwanted advice such as: "why don't you try these cosmetics". These are usually people with a huge arsenal of products on their nightstands. Almost everyone goes through some of the stages of acne during puberty. With this first article I will try to explain the mechanism by which this dermatosis affects the skin.

Why the skin of the face and which structures are affected?

Acne is a disease of the hair follicles, and their concentration is greatest in the face, behind the ears, shoulders, upper chest and back. Sebum production is high in newborns, after which it gradually decreases until a new peak is reached at the beginning of puberty. At the end of this age period follows a relatively constant level of sebum production without expected peaks. This explains to some extent the frequency of the disease in adolescence. About acne in adulthood I will tell in another blog article.

The secretion of sebaceous glands is controlled by androgenic hormones (mainly testosterone, but also by adrenal hormones - andronstenedione and dehydroepiandrosterone sulfate). The sebaceous glands have receptors for androgenic hormones on their surface, through which the "communication" of hormones with the gland takes place. When the "hormone-receptor" contact is made, a signal is given that "commands" the production of more than the required amount of sebum.

Mechanisms by which the hair follicle is damaged

Proliferation of the follicular epidermis (ie thickening and respectively narrowing of the duct through which the gland must evacuate sebum on the surface of the epidermis).

Increased sebum production

Increased activity of Cutibacterium acnes,which is a normal bacterium in our skin (it was soon renamed by Propionibacterium acnes).

Inflammation

The exact sequence of these events is not entirely clear, but it is assumed that the thickening of the follicular epidermis occurs first, leading to its obstruction (partially or completely). Clinically, this is expressed by microcomedone or comedones. The other key point is the increased production of sebum due to stimulation by androgenic hormones. In prepubertal girls without signs of puberty, acne is mostly due to adrenal dehydroepiandrosterone sulfate. Both growth hormone and Insulin-like growth factor 1 (IGF-1) affect the sebaceous glands. The last hero or more correctly to say anti-hero will be the subject of a separate topic, as it is assumed that he is at the root of acne, exacerbated by eating a certain type of food. And "acne and diet" deserve a very in-depth additional analysis.

Cutibacterium acnes is an anaerobic microorganism that is a normal inhabitant of our skin and inhabits the hair-fat follicle. The increased amount of sebum and the formation of a plug from hyperkeratosis lead to the proliferation (increased number and spread) of the bacterium. Cutibacterium produces an enzyme called lipase that transforms sebum triglycerides into free fatty acids. The latter event leads to an inflammatory response that further attracts leukocytes. As a result of this whole cascade, the follicle ruptures, which provokes a new inflammatory reaction. Clinically, this is manifested by papules, pustules and cysts.

#OurSkinWithinTips

This interactions of the mechanisms determines the need for more than one drug to be involved in the treatment of acne. Both the narrowed or blocked follicular canal and the sebum must be treated to prevent a favorable environment for bacterial proliferation. You can read more about the therapeutic approach in the different stages of acne in a separate topic.

Finally, I want to debunk a few myths. One is that acne is not a disease and will just go away. Yes, it is possible to pass only after years, but scars will remain, and this is preventable. The second is that people with acne do not take care of their skin. They take great care, they are just not always the right one for them. There are no ready-made learned formulas for successful acne treatment. For me, it is a systemic disease and the diagnosis begins with an assessment of the general condition, the presence of concomitant diseases, levels of hormones, vitamins, micro-and macronutrients in each patient.

Baldwin H, Tan J. Effects of Diet on Acne and Its Response to Treatment. Am J Clin Dermatol. 2020 Aug 3. doi: 10.1007/s40257-020-00542-y. Epub ahead of print. PMID: 32748305.

Sutaria AH, Masood S, Schlessinger J. Acne Vulgaris. 2020 Aug 8. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan–. PMID: 29083670.

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