A Microbe You May Not Know

On this episode of the podcast “This Week in Microbiology” Vincent Racaniello, Elio Schaechter, Michele Swanson, and Michael Schmidt discussed the research paper from the National Institute of Allergy and Infectious Disease (NIAID) by Myles et al. titled “Therapeutic responses to Roseomonas mucosa in atopic dermatitis may involve lipid-mediated TNF-related epithelial repair” which discussed the skin microbiome and atopic dermatitis. Michael Schmidt remarked how impactful a probiotic treatment for atopic dermatitis can be for an individual’s physical health and their psyche. The clinical data were followed by a mechanistic exploration of how R. mucosa affects the epithelium. Contrary to the organization of most scientific papers, this paper begins with a discussion of the clinical data followed by the basic research that lead to the clinical trial.

Myles et al. explored the utilization of R. mucosa obtained from healthy individuals as a topical probiotic for individuals suffering from atopic dermatitis. Individuals with this disease contain R. mucosa in their skin microbiota; however, the R. mucosa varies from that of healthy individuals. This variation in the skin microbiota causes skin inflammation resulting in irritation and in some instances, lesions. Participants in the clinical trial were scored before and after application of cultured R. mucosa using existing clinical scales (SCORAD and EASI). Additionally, the authors used dose escalation in the trial which increased the concentration of R. mucosa over time. There was significant improvement in all patients compared to the placebo and an FDA approved drug Tacrolimus (Myles et al., 2020). This represents a great alternative to Tacrolimus and other immunosuppressive medication. Michele Swanson mentioned that the primary author involved in the clinical trial noticed a change in patient behavior. Specifically, R. mucosa probiotic treatment improved children’s self-confidence, which was observed by changes in behavior such as wearing short-sleeve shirts.

Following the results of the clinical investigation, the hosts discussed the mechanistic success of the probiotic described by the authors of the study. The microbiome of the skin was tracked over time during the clinical trial. Application of R. mucosa resulted in an increase in Alphaproteobacteria and a subsequent decrease in Staphylococcaceae abundance. The altered microbial populations resemble that of the skin found in healthy individuals. Cytokine levels from the skin showed anti-inflammatory properties such as IL-13 and TNFa (Myles et al., 2020). Following molecular characterization of patients’ healing tissue, the authors assessed tissue repair in cell culture. A scratch was mimicked in co-culture with keratinocytes and R. mucosa from either healthy or atopic dermatitis individuals. Keratinocytes co-cultured with R. mucosa from healthy individuals proliferated and “healed” the scratch faster, whereas co-cultures with R. mucosa from atopic dermatitis individuals did not affect keratinocyte growth. Exploring transcriptomics, quantitative enzymatic comparison, and metabolomics between R. mucosa from individuals with and without atopic dermatitis, the authors found differences in each experimental approach regarding glycerophospholipid production. In cell culture, keratinocytes were treated with lipids isolated from R. mucosa of healthy individuals. Similar increases in keratinocyte growth were observed when cells were treated with lipids or cultured with R. mucosa from healthy individuals. However, when keratinocytes were treated with a lipase after lipid addition, the increase in growth was ablated (Myles et al., 2020). The podcast hosts presented a very unique and impactful study detailing basic research and clinical trial data in a fun and interactive format for all audiences.


Myles, I. A., Castillo, C. R., Barbian, K. D., Kanakabandi, K., Virtaneva, K., Fitzmeyer, E., ... & Datta, S. K. (2020). Therapeutic responses to Roseomonas mucosa in atopic dermatitis may involve lipid-mediated TNF-related epithelial repair. Science translational medicine, 12(560).

Schmidt, M., Swanson, M., Schaechter, E., Racaniello, V. (2020). Two microbes you might not know (No. 226). https://www.microbe.tv/twim/twim-226/