Abstract

Acne vulgaris is one of the most common skin diseases causing inflammation in sebaceous areas of the skin. Acne-causing Cutibacterium acnes bacteria occurs abundantly in healthy and acne-displaying skin, with the difference caused by the loss of C. acnes subtype diversity and higher virulence. Skin bacteria play an important role in protecting skin from pathogens and producing antioxidants that bind free radicals from the environment. Changes in microbiota can give rise to C. acnes due to the loss of other Cutibacterium-inhibiting bacteria. C. acnes has many different subtypes that belong to the healthy commensal microbiota. When the microbiota balance is disrupted, one subtype, IA1, may become dominant and can produce acne by producing proinflammatory porphyrins.
Research has also demonstrated a link  between the gut and skin microbiomes. Intestine epithelial barrier dysfunction causes bacteria and metabolites from the gut to migrate via the bloodstream to the skin and accumulate, causing inflammation. In acne patients, gut dysbiosis and digestion related symptoms are more common than in healthy subjects. Therefore, treatment with oral probiotics may provide a therapeutic effect in acne patients as demonstrated by limited studies.