The Role of the Skin Microbiota in Acne Pathophysiology

S. Ramasamy; E. Barnard; T.L. Dawson Jr; H. Li

Disclosures

The British Journal of Dermatology. 2019;181(4):691-699. 

In This Article

Abstract and Introduction

Abstract

Background: The role of skin microbiota in acne remains to be fully elucidated. Initial culture-based investigations were hampered by growth rate and selective media bias. Even with less biased genomic methods, sampling, lysis and methodology, the task of describing acne pathophysiology remains challenging. Acne occurs in sites dominated by Cutibacterium acnes (formerly Propionibacterium acnes) and Malassezia species, both of which can function either as commensal or pathogen.

Objectives: This article aims to review the current state of the art of the microbiome and acne.

Methods: The literature regarding the microbiome and acne was reviewed.

Results: It remains unclear whether there is a quantitative difference in microbial community distribution, making it challenging to understand any community shift from commensal to pathogenic nature. It is plausible that acne involves (i) change in the distribution of species/strains, (ii) stable distribution with pathogenic alteration in response to internal (intermicrobe) or external stimuli (host physiology or environmental) or (iii) a combination of these factors.

Conclusions: Understanding physiological changes in bacterial species and strains will be required to define their specific roles, and identify any potential intervention points, in acne pathogenesis and treatment. It will also be necessary to determine whether any fungal species are involved, and establish whether they play a significant role. Further investigation using robust, modern analytic tools in longitudinal studies with a large number of participants, may make it possible to determine whether the microbiota plays a causal role, is primarily involved in exacerbation, or is merely a bystander. It is likely that the final outcome will show that acne is the result of complex microbe–microbe and community–host interplay.

Introduction

It is now widely accepted that the human microbiota, the plethora of microorganisms that reside on and in the body, plays an essential role in the maintenance of health and the onset or progression of disease. Skin microbiota provide the first line of protection against environmental factors and pathogens. The microbiota consists of both 'resident' and 'transient' microbes, and is constantly in flux, changing alongside environmental and host factors such as ultraviolet exposure, environmental microbes, personal hygiene and consumer care products, host hormone levels, sebum and sweat. The rapid development of high-throughput sequencing technologies led the U.S. National Institutes of Health to launch the Human Microbiome Project (HMP) in 2007 in order to investigate the role of the human-associated microbial communities in health and disease. For the sake of clarity, throughout this review we comply with the convention that 'microbiota' refers to microorganisms on the skin, and the 'microbiome' represents the total genomic component, measured by DNA analysis. Acne vulgaris is a prevalent skin disease in which skin microbes are implicated, but their role and level of contribution remain controversial. In this review, we highlight recent studies following the pioneering HMP, which investigate the role of the skin microbiome in cutaneous health and acne.

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