Acne, the condition most associated with teenage years but also one that can affect adults of all ages, has long been associated with a specific bacterium – Cutibacterium acnes (or what was formerly named Propionibacterium acnes). C. acnes is one of the most common bacterial species on human skin and can promote the common disease acne vulgaris.
However, categorising all strains of this bacterium as likely to cause spots appears to be misleading. New research suggests that some variants can contribute to improving the health of human skin.
The research, performed at Osaka City University, comes from studies performed on Caenorhabditis elegans (a worm that is used as a common animal model). The findings reveal that shows that certain strains of the bacterium C. acnes actually prolong the nematode’s lifespan and help its innate immune system fight against the pathogen Staphylococcus aureus. Could there be the basis for a skin treatment?
The research problem is with assessing which strains of C. acnes are the beneficial ones. To unravel this molecular methods that probe an organisms phenotype are required.
The analysis finds there is a correlation between ribotype strains of C. acnes, which are found in human skin, and the lifespan of the nematode C. elegans. Specifically, strains RT4 and 8, which are associated with acne in human skin, shortened the lifespan of the nematode.
Another strain, coded RT6, which are predominantly found in healthy human skin, did not. Further, it was found that the healthy skin-related RT6 strain of C. acnes improved C. elegans resistance to the pathogenic organism S. aureus.
Further analysis reveals that the resistance factors to S. aureus are mediated by the TIR-1 and p38 MAPK pathways, which are responsible for the nematode’s innate immunity.
This means instead of C. acnes ‘hyperproliferation’, the cause of acne is the result of a loss of balance between the different C. acnes strains, together with a dysbiosis of the skin microbiome.
The research also means that strains of C. acnes maintain skin health by inhibiting common pathogens like S. aureus from invading skin tissue. This could provide the basis for developing a new form of probiotic for people with acne– perhaps one that is applied to the skin rather than the more common forms of probiotics that are ingested in order to help to modify the balance of intestinal bacteria.
The research appears in the journal Microbiology Spectrum, titled “Nonpathogenic Cutibacterium acnes Confers Host Resistance against Staphylococcus aureus.”
