To understand acne, we must first know all the components of our skin and how hormones work.

We remind you that acne is a multifactorial dermatitis whose dependence on hormones is undeniable and that it involves an overproduction of sebum, a keratinization of the excretory canal of the sebaceous glands and an inflammation linked to the proliferation of the Propionibacterium acnes bacteria.

How does our skin work and what is its role in acne?

The skin is a complex protective organ with multiple functions and a complex structure.

It is composed of superimposed layers: epidermis, dermis and hypodermis.

At the level of the dermis and hypodermis, we have the annexes of the skin:

• Sweat glands that produce sweat
• Sebaceous glands that secrete sebum
• Hair follicles associated with a sebaceous gland

The sebaceous glands produce cells called sebocytes which produce sebum by a phenomenon of hydrolysis of their membrane and cellular differentiation.

Sebum is a fluid fat composed mainly of lipids (triglycerides and squalenes) and waxes which are fatty acids. Sebum and cellular debris are excreted by the sebaceous glands on the surface of the skin via the pilary canal: sebum travels up the hairs to the surface of the skin. It then spreads over the surface of the skin, mixing with other surface lipids and the aqueous phase (water, sweat) to form the hydrolipidic film.

The increase in sebum secretion is explained by hyperactivity of 5 alpha dihydrotestosterone (DHT), which is a biologically active metabolite of testosterone, formed in the prostate, testes, hair follicles and adrenal glands by the action of an enzyme, 5-α- reductase. Its affinity for the androgen receptor is about 3 times higher than that of testosterone. These mechanisms are at the origin of the hyperseborrhea process.

After this sebaceous hypersecretion, bacterial proliferation and inflammation follow. Propionibacterium acnes is a commensal germ involved in the genesis of acne. This is why allopathic treatments also consist in administering antibiotics or retinoids applied locally to fight against this bacterium.

It is important to know that the role of sebum is very important because it participates in the cohesion of the stratum corneum, allows the survival of the commensal flora, protects the skin against UV rays and contains bactericidal substances that prevent the bacteria present on the surface of the skin from penetrating deeply. Our epidermis normally has a pH level between 5.4 and 5.6. This pH level is very important to keep our skin healthy.

So by combining, for example, retinoids and benzoyl peroxide, our epidermis is attacked, our hydrolipidic film is disrupted, we end up with dry skin to reduce sebum and so our sebaceous glands become hyperactive to produce more sebum to protect our skin.