While summer days bring more hours of welcome daylight, longer exposure to the sun’s ultraviolet radiation (UVR) can damage the skin. Sunburn, inflammation, photoaging, skin cancer, and/or immune modulation can result. New research suggests that the skin microbiome may be a feasible target for novel strategies using probiotics and prebiotics for protection against UVR-induced skin damage.
Skin microbiome, in brief
The harsh landscape of skin — nutrient-poor and acidic —acts as a physical barrier to prevent the invasion of foreign pathogens while still providing a home to diverse commensal microbiota. The healthy human skin provides a variety of environments; some may be dry, humid, or oily, some warm or cold. Hence, the human skin harbors a multitude of diverse and complex communities of bacteria, fungi, viruses, archaea, and mites— collectively called the skin microbiome. To survive in a hostile environment, the resident microbes utilize resources present in the stratum corneum (horny outer layer), sweat (moisture secreted through pores), and sebum (oily secretion from sebaceous glands). In addition, the skin microbiome must maintain a healthy interplay with the skin’s immune system for its survival.
The skin microbiome is involved in a broad range of molecular and cellular processes within the skin and beyond which contribute to health and disease.
Ultraviolet radiation (UVR)
UVR, especially types UV-A and UV-B, can cause various local effects in the skin as well as systemic changes. Many effects are harmful such as cellular DNA damage but others are beneficial such as positive behavioral impacts as the result of endorphin production. In addition, Vitamin D3 (cholecalciferol) is mainly generated in the skin as a response to UVR. In its biologically active form, Vitamin D3 is an important nutrient for optimal health and wellbeing. A recent study shows a striking correlation between serum concentrations of 25(OH) D levels and the abundance of various microbes in the gut, suggesting an interaction between UVR exposure and the gut-skin axis.
Microbes & mechanisms of action in UVR skin effects
Melanin production and antioxidant effects
Skin pigmentation is protective against UVR. Melanin, a broad term for a group of natural pigments, absorbs as much as 50-70% of UVR and also possesses antioxidant properties.
Although darker skin has more protection from the sun’s harmful rays because it contains higher levels of melanin, people of all skin types can burn if they don’t wear sunscreen.
Specific microbial strains may produce compounds that could potentially be used to protect the skin from UVR and/or antioxidants that may improve skin health. In one example, the topical use of Lactobacillus helveticus supernatant on the skin had antioxidant effects on rodents.
Protection from photoaging
UVR exposure accounts for an estimated 80% of the visible signs of skin aging. This so-called “photoaging” is known to correlate with cancer risk. It is known that the skin microbiome is influenced by chronological and physiological skin aging. In addition to causing local (skin) changes in the microbiome, UVR can also lead to intestinal changes.
Many studies involving humans have supported the role of probiotics in attenuating UV-induced skin damage. Strains of probiotic bacteria including Lactobacillus johnsonii, Lactiplantibacillus plantarum, and Bifidobacterium breve have been shown to have beneficial effects on photoaging in humans or mice. A review of research testing the effects of probiotics in photoaging is available in this Table.
Prebiotics such as galactooligosaccharides orally administeredhave been shownto prevent trans-epidermal water loss and prevent skin damage in hairless mice.
Anti-tumor effects of the microbiome
UVR exposure is linked with the development of different types of skin cancers including squamous cell carcinoma (SCC). SCC can develop from an actinic keratosis, which is a typical lesion of UVR- damaged skin. In recent studies, skin with lesions was observed to host different commensal strains than skin without lesions. An altered microbial landscape in cancerous skin may play a role in disease pathogenesis and/or progression.
In one study, oral intake of lipoteichoic acid from Lacticaseibacillus rhamnosus decreased the number of UV-induced skin tumors in hairless mice.
While these results with selected probiotics and prebiotics are promising, we should interpret them with caution and look forward to further study results.
Enhancement of the UVR-induced immune suppression
UVR has a profound effect on the skin’s immune system. The skin microbiome may have a role in UVR-induced immune suppression. For example, in a study using germ-free mice, the absence of a microbiome enhanced UVR-induced immune suppression. In contrast, mice with a microbiome showed diminished UVR-induced immune suppression.
Protection in UVR-induced skin inflammation
Inflammatory skin diseases such as systemic lupus erythematosus (SLE) and polymorphic light eruption (PLE) are linked to UVR exposures. While the mechanisms are not clear, recent research suggests that UVR-induced changes in microbial communities of the skin may be involved in their pathogenesis.
The use of topical anti-inflammatory probiotics could be beneficial.
In one study, Limosilactobacillus reuteri showed anti-inflammatory properties on reconstructed human skin models upon UVR-induced inflammation.
The use of probiotics and prebiotics to modulate the intestinal microbiota that support the skin immune response or the skin microbiota is promising in protecting the skin against UVR-induced skin damage. The number of human studies is, however, still limited and formulations that promote a commensal microbiome that can protect against UVR and suppress the growth of pathogens should be further explored.
In the meantime, slather on your high-SPF sunscreen this summer.
Bosman, Else S et al. “Skin Exposure to Narrow Band Ultraviolet (UVB) Light Modulates the Human Intestinal Microbiome.” Frontiers in microbiology vol. 10 2410. 24 Oct. 2019, doi:10.3389/fmicb.2019.02410
Brenner, Michaela, and Vincent J Hearing. “The protective role of melanin against UV damage in human skin.” Photochemistry and photobiology vol. 84,3 (2008): 539-49. doi:10.1111/j.1751-1097.2007.00226.x
Burns, Erin M et al. “Ultraviolet radiation, both UVA and UVB, influences the composition of the skin microbiome.” Experimental dermatology vol. 28,2 (2019): 136-141. doi:10.1111/exd.13854
Byrd, Allyson L et al. “The human skin microbiome.” Nature reviews. Microbiology vol. 16,3 (2018): 143-155. doi:10.1038/nrmicro.2017.157
De Pessemier, Britta et al. “Gut-Skin Axis: Current Knowledge of the Interrelationship between Microbial Dysbiosis and Skin Conditions.” Microorganisms vol. 9,2 353. 11 Feb. 2021, doi:10.3390/microorganisms9020353
Everard, Amandine et al. “Cross-talk between Akkermansia muciniphila and intestinal epithelium controls diet-induced obesity.” Proceedings of the National Academy of Sciences of the United States of America vol. 110,22 (2013): 9066-71. doi:10.1073/pnas.1219451110
Fehlbaum, Sophie et al. “In Vitro Fermentation of Selected Prebiotics and Their Effects on the Composition and Activity of the Adult Gut Microbiota.” International journal of molecular sciences vol. 19,10 3097. 10 Oct. 2018, doi:10.3390/ijms19103097
Friedrich, Adrián D et al. “Oral administration of lipoteichoic acid from Lactobacillus rhamnosus GG overcomes UVB-induced immunosuppression and impairs skin tumor growth in mice.” European journal of immunology vol. 49,11 (2019): 2095-2102. doi:10.1002/eji.201848024
Grice, Elizabeth A. “The skin microbiome: potential for novel diagnostic and therapeutic approaches to cutaneous disease.” Seminars in cutaneous medicine and surgery vol. 33,2 (2014): 98-103. doi:10.12788/j.sder.0087
Guéniche, Audrey et al. “Probiotics for photoprotection.” Dermato-endocrinology vol. 1,5 (2009): 275-9. doi:10.4161/derm.1.5.9849
Halder, R M, and K M Bang. “Skin cancer in blacks in the United States.” Dermatologic clinics vol. 6,3 (1988): 397-405.
Hong, Ki-Bae et al. “Photoprotective effects of galacto-oligosaccharide and/or Bifidobacterium longum supplementation against skin damage induced by ultraviolet irradiation in hairless mice.” International journal of food sciences and nutrition vol. 66,8 (2015): 923-30. doi:10.3109/09637486.2015.1088823
Huang, Cancan et al. “Disordered cutaneous microbiota in systemic lupus erythematosus.” Journal of autoimmunity vol. 108 (2020): 102391. doi:10.1016/j.jaut.2019.102391
Khmaladze, Ia et al. “Lactobacillus reuteri DSM 17938-A comparative study on the effect of probiotics and lysates on human skin.” Experimental dermatology vol. 28,7 (2019): 822-828. doi:10.1111/exd.13950
Kim, Hyun Mee et al. “Oral administration of Lactobacillus plantarum HY7714 protects hairless mouse against ultraviolet B-induced photoaging.” Journal of microbiology and biotechnology vol. 24,11 (2014): 1583-91. doi:10.4014/jmb.1406.06038
Kober, Mary-Margaret, and Whitney P Bowe. “The effect of probiotics on immune regulation, acne, and photoaging.” International journal of women’s dermatology vol. 1,2 85-89. 6 Apr. 2015, doi:10.1016/j.ijwd.2015.02.001
Kripke, M L, and M S Fisher. “Immunologic aspects of tumor induction by ultraviolet radiation.” National Cancer Institute monograph ,50 (1978): 179-83.
Li, Yan et al. “Gut microbiota dependent anti-tumor immunity restricts melanoma growth in Rnf5-/- mice.” Nature communications vol. 10,1 1492. 2 Apr. 2019, doi:10.1038/s41467-019-09525-y
Meisel, Jacquelyn S et al. “Commensal microbiota modulate gene expression in the skin.” Microbiome vol. 6,1 20. 30 Jan. 2018, doi:10.1186/s40168-018-0404-9
Ouwehand A.C., Tiihonen K., Lahtinen S. The Potential of Probiotics and Prebiotics for Skin Health. In: Farage M.A., Miller K.W., Maibach H.I., editors. Textbook of Aging Skin. Springer; Berlin/Heidelberg, Germany: 2010. pp. 799–809.
Patra, VijayKumar et al. “Potential of Skin Microbiome, Pro- and/or Pre-Biotics to Affect Local Cutaneous Responses to UV Exposure.” Nutrients vol. 12,6 1795. 17 Jun. 2020, doi:10.3390/nu12061795
Patra, VijayKumar et al. “Skin Microbiome Modulates the Effect of Ultraviolet Radiation on Cellular Response and Immune Function.” iScience vol. 15 (2019): 211-222. doi:10.1016/j.isci.2019.04.026
Patra, VijayKumar, and Peter Wolf. “Microbial elements as the initial triggers in the pathogenesis of polymorphic light eruption?.” Experimental dermatology vol. 25,12 (2016): 999-1001. doi:10.1111/exd.13162
Peyrat, Laure-Anne et al. “Terrestrial Microorganisms: Cell Factories of Bioactive Molecules with Skin Protecting Applications.” Molecules (Basel, Switzerland) vol. 24,9 1836. 13 May. 2019, doi:10.3390/molecules24091836
Rastogi, Rajesh P, and Aran Incharoensakdi. “Analysis of UV-absorbing photoprotectant mycosporine-like amino acid (MAA) in the cyanobacterium Arthrospira sp. CU2556.” Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology vol. 13,7 (2014): 1016-24. doi:10.1039/c4pp00013g
Rong, J et al. “Skin resistance to UVB-induced oxidative stress and hyperpigmentation by the topical use of Lactobacillus helveticus NS8-fermented milk supernatant.” Journal of applied microbiology vol. 123,2 (2017): 511-523. doi:10.1111/jam.13506
Shibagaki, Nakako et al. “Aging-related changes in the diversity of women’s skin microbiomes associated with oral bacteria.” Scientific reports vol. 7,1 10567. 5 Sep. 2017, doi:10.1038/s41598-017-10834-9
Slominski, Andrzej T et al. “How UV Light Touches the Brain and Endocrine System Through Skin, and Why.” Endocrinology vol. 159,5 (2018): 1992-2007. doi:10.1210/en.2017-03230
Sugimoto, Saho et al. “Photoprotective effects of Bifidobacterium breve supplementation against skin damage induced by ultraviolet irradiation in hairless mice.” Photodermatology, photoimmunology & photomedicine vol. 28,6 (2012): 312-9. doi:10.1111/phpp.12006
Wendt, Judith et al. “Site-dependent actinic skin damage as risk factor for melanoma in a central European population.” Pigment cell & melanoma research vol. 25,2 (2012): 234-42. doi:10.1111/j.1755-148X.2011.00946.x