The Skin Microbiome: Is It Affected by UV-induced Immune Suppression?

Vijaykumar Patra,Peter Wolf,Scott N Byrne

doi:10.3389/fmicb.2016.01235

Vijaykumar Patra, Peter Wolf + Show 1 more

Open Access

https://doi.org/10.3389/fmicb.2016.01235

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Abstract

Human skin apart from functioning as a physical barricade to stop the entry of pathogens, also hosts innumerable commensal organisms. The skin cells and the immune system constantly interact with microbes, to maintain cutaneous homeostasis, despite the challenges offered by various environmental factors. A major environmental factor affecting the skin is ultraviolet radiation (UV-R) from sunlight. UV-R is well known to modulate the immune system, which can be both beneficial and deleterious. By targeting the cells and molecules within skin, UV-R can trigger the production and release of antimicrobial peptides, affect the innate immune system and ultimately suppress the adaptive cellular immune response. This can contribute to skin carcinogenesis and the promotion of infectious agents such as herpes simplex virus and possibly others. On the other hand, a UV-established immunosuppressive environment may protect against the induction of immunologically mediated skin diseases including some of photodermatoses such as polymorphic light eruption. In this article, we share our perspective about the possibility that UV-induced immune suppression may alter the landscape of the skin’s microbiome and its components. Alternatively, or in concert with this, direct UV-induced DNA and membrane damage to the microbiome may result in pathogen associated molecular patterns (PAMPs) that interfere with UV-induced immune suppression.

Highlights

The human skin is the largest organ of the body with a diverse physical, chemical, and biological ecosystem over a surface of 1.8 m2
Around 1 million bacteria reside per square centimeter of skin surface, making up an estimated total of 1010 bacterial cells growing on the entire skin of the human body (Grice et al, 2008; Hannigan and Grice, 2013)
It is known that caspase-14 controls the proteolysis of fillagrin and patients with fillagrin mutations are more likely to develop atopic dermatitis (AD), which in turn is associated with alterations of microbial load on the skin (McAleer and Irvine, 2013)

Summary

Introduction

The human skin is the largest organ of the body with a diverse physical, chemical, and biological ecosystem over a surface of 1.8 m2. Recent studies indicate that specific bacterial communities are associated with moist, dry or sebaceous microenvironments of the skin Moist areas such as umbilicus, the axillary vault, inguinal crease, gluteal crease, foot, popliteal fossa, and the antecubital fossa have an abundance of Staphylococcus and Corynebacterium spp. and these organisms are well known to prefer skin sites with high humidity. Studies done by Findley et al (2013) described fungal communities residing in the skin by sequencing 18s rRNA (phylogenetic marker within ribosomal RNA region) and ITS1 (internal transcribed spacer 1 region) They observed that the genus Malassezia predominated across the 11 core body and arm sites of their study (back, occiput, external auditory canal, inguinal crease, retroauricular crease, glabella, manubrium, nare, anticubital fossa, volar forearm, hypothenar palm, plantar heel, toe nail, and toe-web space). Demodex mites are associated with cutaneous conditions of rosacea-like appearance, commonly clubbed as demodicosis or demodicidosis, though their presence on the skin most commonly remains asymptomatic

Factors Affecting Skin

Antimicrobial Peptides

CONCLUSION

Findings

AUTHOR CONTRIBUTIONS