Acne vulgaris is a skin disease associated with the proliferation of Cutibacterium acnes (formerly known as Propionibacterium acnes), a symbiotic microbe of the skin, which activates an immune response. Indeed, C. acnes stimulates the secretion of cytokines and chemokines (TNF-α, interleukins, etc.), causing chronic inflammation. Excess sebum production also causes acne by inducing an inflammatory reaction under the proliferating skin microflora and by modifying its composition. This breakdown produces substances that fuel the inflammation and lead to the formation of acne pimples (pustules and papules).
In addition to inactivating the growth of Cutibacterium acnes, a cell-based study demonstrated that hemp seed hexane extract inhibits the secretion of pro-inflammatory molecules, such as TNF-α, IL-1β and IL-8, through the expression of inflammatory enzymes in keratinocytes infected with C. acnes. It also regulates the NF-kB (Nuclear factor kappa B) signaling process, which induces the transcription of genes involved in inflammatory responses. Moreover, hemp extract also inhibits the expression level of 5-lipoxygenase, thus regulating the production of intracellular lipids in sebocytes (epithelial cells involved in sebum production) and therefore inflammation. Indeed, the latter promotes lipid synthesis in the sebaceous glands by releasing leukotriene B4 (LTB4), a pro-inflammatory lipid.
In addition, inflammation induces damage to the extracellular matrix by inhibiting collagen production in dermal fibroblasts and activating the activity of specific enzymes (elastase, collagenase, gelatinase, etc.), which leads to the suppression of skin regeneration in the case of inflamed acne lesions. A study has shown that hemp can increase the biosynthesis of collagen, which shows its potential to improve the healing and regeneration processes of the skin, in addition to inhibiting the activity of metalloproteinase. Thus, essential oil of hemp can decrease extracellular matrix damage caused by C. acnes infection. However, studies conducted with in vivo models are needed to reinforce these findings on hemp as an anti-acne agent.