Cutibacterium acnes, the bacteria that is known to cause acne, is also widely spread to people with healthy skin. Recent developments in gene sequencing have shown that differences in genetic background between strains of bacteria may lead to different roles in the skin. A new study, done without animal (mammal) testing, shows that a non-nervous strain of C. acnes improves skin resistance against bacteria that cause Staphylococcus aureus infection.
The report appears in the American Society for Microbiology’s Microbiology Spectrum.
“C. acnes is likely to maintain healthy skin by inhibiting common pathogens such as S. aureus from invading skin tissue,” said lead author Ayano Tsuru, a graduate student in the Graduate School of Human Life Sciences, Osaka City University. “Instead of using mammals, we explored this with the nematode Caenorhabditis, a 1mm nematode that contains essential animal parts such as the nervous system, muscle, and digestive system, as well as the body’s surface barrier equivalent to human skin.”
In this joint study between Osaka City University and Okayama University, researchers used C. elegans to investigate the biological effects of several strains of C. acnes isolated from human skin.
The results showed that ribotype (RT) 4 and 8 strains, a classification of bacteria strains based on rRNA polymorphisms, which are often detected in the skin of individuals with acne vulgaris, shortened the lifespan of nematodes, while RT6 strains that often Found in the skin of people who do not suffer from acne, it does not.
“And that means it,” explains supporting author Yumi Hamazaki, also a graduate student in the OCU Graduate School of Human Life Sciences, “the ribotype strains of C. acnes that cause acne in humans are associated with virulence, or shortening the lifespan of C. elegans.”
The team further explained this finding by investigating the effect of healthy skin-associated strains of C. acnes on nematode susceptibility to S. Oreos. The results showed that the survival period of nematodes infected with the pathogen was longer than that of the control group.
Also, RNA-sequencing analysis of changes in gene expression revealed that strains of C. acnes beyond healthy skin activate a set of genes related to innate immunity and biological defense responses in C. elegans. “Further analysis of the nematode gene mutants” states Professor Shota Tomida of the Center for Comprehensive Genomic Medicine at Okayama University Hospital, “suggesting that this resistance to S. aureus was mediated by TIR-1 and p38 MAPK pathways that are responsible for innate immunity rather than by suppressing Growth of the pathogen S. aureus.
The implications of this study are broad and exciting.
By focusing on the rhotic patterns associated with the absence of acne, this study demonstrated that there are beneficial aspects to acne bacteria, which generally had a negative profile.
As advisor to the study, Eriko Kaji Nakadai, a professor in the OCU Graduate School of Human Life Sciences, says: “This reminds us that when evaluating the biological effects of some bacteria, a strain-level discussion is required.” The fact that we were able to detect traces of native bacteria in the epidermis using C. ligands demonstrates the usefulness of these nematodes as an alternative model in the field of epidemiology.”
Finally, in a landscape of probiotic research currently dominated by Bifidobacterium and Lactobacillus, the team was excited to anticipate that this study might lead to the application of healthy skin-associated strains of C.
Materials provided by Osaka City University.
Ayano Tsuru, Yumi Hamazaki, Shota Tomida, Muhammad Shokat Ali, Tomomi Komura, Yoshikazu Nishikawa, Eriko Kaji Nakadai. Non-exercise acne bacteria confer resistance to the host against Staphylococcus aureus. Spectrum Microbiology, 2021; DOI: 10.1128 / Spectrum.00562-21