Abstract
Acne is a highly prevalent inflammatory skin condition involving sebaceous sties. Although it clearly develops from an interplay of multiple factors, the exact cause of acne remains elusive. It is increasingly believed that the interaction between skin microbes and host immunity plays an important role in this disease, with perturbed microbial composition and activity found in acne patients. Cutibacterium acnes (C. acnes; formerly called Propionibacterium acnes) is commonly found in sebum-rich areas and its over-proliferation has long been thought to contribute to the disease. However, information provided by advanced metagenomic sequencing has indicated that the cutaneous microbiota in acne patients and acne-free individuals differ at the virulent-specific lineage level. Acne also has close connections with the gastrointestinal tract, and many argue that the gut microbiota could be involved in the pathogenic process of acne. The emotions of stress (e.g., depression and anxiety), for instance, have been hypothesized to aggravate acne by altering the gut microbiota and increasing intestinal permeability, potentially contributing to skin inflammation. Over the years, an expanding body of research has highlighted the presence of a gut–brain–skin axis that connects gut microbes, oral probiotics, and diet, currently an area of intense scrutiny, to acne severity. This review concentrates on the skin and gut microbes in acne, the role that the gut–brain–skin axis plays in the immunobiology of acne, and newly emerging microbiome-based therapies that can be applied to treat acne.
Highlights
The term ‘microbiome’ covers a whole range of micro-organisms, including bacteria, viruses, and fungi, their genes and metabolites, and the environment surrounding them
The findings suggest that the microbiota plays an important role in acne pathogenesis and can be modulated for clinical improvement, but efforts should be made to identify the exact mechanisms and therapeutic effects of oral/topical probiotics in acne (Table 4)
Researchers have increased what is known about the human microbiome
Summary
The term ‘microbiome’ covers a whole range of micro-organisms, including bacteria, viruses, and fungi, their genes and metabolites, and the environment surrounding them. Inflammatory mediators of the skin, and follicular keratinization of the pilosebaceous ducts are believed to contribute to acne development. Emerging data suggest that dietary factors (i.e., the Western diet) may influence acne development. A typical Western pattern diet which includes foods with complex mixture of fat (i.e., red meat), high glycemic index, and dairy may aggravate acne by raising the levels of insulin-like growth factor-1 (IGF-1) and insulin [3,4,5,6]. A large body of evidence indicates that a low fiber-high fat Western diet causes fundamental changes in the intestinal microbiota, producing metabolic and inflammatory skin diseases [7]. We discuss host–microbe interactions in acne to clarify understanding of the disease and enable better treatments
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