Table 1 |.

Knowledge gaps in skin microbiome research

Topics	Gaps
Microbial interactions	How do different species of microorganisms influence each other’s colonization and function? How do the different species of microorganisms collaborate to maintain a host’s homeostasis? What are the mechanisms that contribute to skin dysbiosis? How does the skin microbiome reestablish new homeostasis once some commensals are removed or changed?
Interaction between microbiome and host	What are the age-, sex-, location-, or hormone-specific commensals? What are the underlying mechanisms? What is the role of the host immune system during a change of commensals’ colonization? How do commensals interact with the innate and adaptive immune components? How does a human body sense different commensal antigens? What are the receptors, the antigens, the antigen-presenting cells and the key signaling pathways?
Microbiome transmission and dynamics	How are commensals shared between family members, roommates, or between humans and pets? What are the benefits and potential harms? What roles do the host and environmental factors have during this process? How does microbiome transmission affect the dynamics and stability of microbiota?
Microorganisms and skin conditions	How do changes in cutaneous microbiota alter the skin microenvironment? How does fungal or parasitic skin microorganisms modulate skin inflammatory diseases? Would antibiotic treatment be a useful additional therapy for skin inflammatory, parasitic or fungal infectious diseases?
Implementing integration of strains in vivo	How can we induce sufficient production and directional diffusion of a microbial product of interest with the proper size and function? What is the composition of the different microbial species colonizing the human bodysp;? Why do they colonize different areas? How can specific commensals be colonized in areas of interest? How can colonization resistance of the skin microbiome be overcome at a sufficient density and reproducibly while heeding strain diversity? Can we use components of the skin microbiome as therapeutic strategies to decolonize pathogens?