CBD, the anti-inflammatory effects of this non-psychoactive compound from cannabis.

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.

There are currently several reports on the multifunctional role of CBD and some studies have proposed or provided a molecular justification for the beneficial properties of this phyto-compound. Numerous studies suggest that CBD may be an effective anti-inflammatory. Indeed, it has been observed that it is capable of alleviating inflammation through several pathways.

• CBD reduces the expression of pro-inflammatory cytokines (IL-6, IL-4, TNF-α) by acting as direct or indirect agonists of adenosine A2A receptors, peroxisome proliferator-activated receptors (PPARγ), and transient receptor potential vanilloid (TRPV) receptors or channels, and as an antagonist of GPR55 receptors.

• CBD inhibits the production of an eicosanoid enzyme, cyclooxygenase-2 (COX-2), a signalling molecule that triggers the inflammatory response.

• CBD alleviates pain through its analgesic action. It is believed to act as an agonist on TRPV1 receptors, elements known for mediating sensory perception and pain. According to a 2018 study, CBD would activate these receptors to desensitise them to any new stimulation, thus reducing chronic inflammatory pain.

• Some immune cells (macrophages) generate free radicals through an enzyme, NADPH oxidase, in order to destroy pathogens by oxidising their vital proteins, stimulated by tissue damage, disease or infection. However, in the case of chronic inflammatory diseases, this endogenous production of free radicals can become detrimental by amplifying oxidative stress, thereby maintaining the inflammatory state. Yet, with its specific molecular structure (hydroxyl groups), CBD has demonstrated that it can regulate the redox state and contribute to modulating immunity.

• CBD is also capable of reducing inflammation by increasing the levels of IL-10, an anti-inflammatory cytokine, through the GPR55 receptors.

Numerous studies have demonstrated that CBD can soothe skin inflammation following topical application. Indeed, CBD can be recommended to alleviate pain and reduce all types of redness.