Often viewed negatively, inflammation is a biological response from the immune system designed to protect the body against intrusions. It is triggered as soon as an attack is detected: toxins, allergens, radiations, wounds, bacteria, etc. However, the skin is a living interface continuously subjected to numerous stimuli (mechanical, chemical, biological) and when pathogenic agents manage to breach this shield, an inflammatory reaction is triggered. The entirety of this process is clinically manifested as swelling (oedema), pain, redness, and heat in the affected region.
What exactly happens at the skin level?
When a potential threat (bacterial, fungal, viral intrusion, allergens, etc.) penetrates the body or we suffer a trauma (tissue damage, burn, etc.), the immune system springs into action by dispatching the first responders, the neutrophils, into the bloodstream to assess the pathogen or damage within the hour following the infection or injury.
The identification of the pathogen or damage by neutrophils initiates the inflammatory response and triggers the release of pro-inflammatory chemical mediators, such as cytokines, chemokines, etc., which call the immune system for additional support with the accumulation of other immune cells (mast cells, macrophages, helper T cells) at the site of the lesion. In parallel, an enlargement of the blood vessels adjacent to the affected area (vasodilation) and an increase in vascular permeability, causing redness and a sensation of heat, are initiated by other inflammatory signals (histamine). This significant blood influx allows the passage of other immune system cells from the bloodstream to the tissue.
However, in the event of continuous induction of chemical mediators, inflammation becomes "chronic". Indeed, although it is an essential defence mechanism of the body (acute inflammation), it often happens that the immune system overreacts. Moreover, some scientific studies associate chronic inflammation with skin conditions (psoriasis, rosacea, eczema, urticaria, etc). In this case, it means that inflammation should not be eliminated. On the contrary, it needs to be controlled in order to promote the body's healing capacity and to prevent the intrusion of pathogens into the body.