Skin Microbiome

12 Key excerpts on "Skin Microbiome"

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  Skin Microbiome Handbook

  From Basic Research to Product Development

  • Nava Dayan(Author)
  • 2020(Publication Date)
  • Wiley-Scrivener

    (Publisher)

  These diverse communities of bacteria, fungi, mites and viruses can provide protection against disease and form dynamic, yet distinct niches on the skin [ 9 ]. Differences across these distinct niches are driven by topographical and physiological factors including pH, temperature, moisture, sebum and – and these influence the resident fungi [ 10 ] and bacteria [ 11, 12 ]. Site specificity may also exacerbate skin disorders, which often present in a skin-specific manner (such as atopic dermatitis or psoriasis) [ 13 ]. On top of topography and physiology, recent research has also uncovered the role of genetics in driving differences in the virome [ 14 ] and other microbiota [ 15 ]. Microbial communities are established early in life and play a critical role in establishing immune tolerance to skin microbes [ 16, 17 ]. There is a complex but critical role in the interaction between microbes and the cutaneous immune system in homeostasis, and a number of studies have associated altered microbial communities in the skin with cutaneous diseases [ 8, 18 ]. The term “dysbiosis” is poorly defined, but generally is described as an alteration of the microbiome away from steady-state conditions and is generally associated with disease states and shifts in microbial communities [ 19 ]. Specifically in the context of the Skin Microbiome, “dysbiosis” can refer to a reduced diversity or hyper-diversified microbial community compared to healthy individuals [ 20 ]. Associations between alterations in the Skin Microbiome and diseases have long been described; however, extensive studies over the past decade have teased out some of the complex relationships between host, environmental, and microbial factors in health and disease states. In this chapter, we describe microbial and immune interactions, their deviations, and their associations with different skin diseases

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  The Remarkable Life of the Skin

  An Intimate Journey Across Our Largest Organ

  • Monty Lyman(Author)
  • 2022(Publication Date)
  • Atlantic Monthly Press

    (Publisher)

  The lines are further blurred when it comes to ‘pathobionts’, a devious, two-faced type of bacteria that usually live harmlessly on the skin surface but, when circumstances change, can cause disease. This community of the good, the bad and the ugly that live with us is called the Skin Microbiome, and it is a complex and fascinating world. 2012 saw the publication of the first databases of the Human Microbiome Project, established to identify in detail the microorganisms inhabiting the human surfaces, namely the skin, gut, reproductive and respiratory tracts. 2 We now know that we have at least as many – and probably more – organisms living in and on us than we have of our own cells. Tallying up the total Skin Microbiome is like approximating sand on the seashore, the estimates ranging between thirty-nine and one hundred trillion microorganisms, compared to our 30 trillion body cells. 3, 4 The incoming results of the project are showing that the multitudes in and upon us influence our health, and manipulating and adjusting these populations has the potential to revolutionize medicine. In the same way that Earth has radically varied ecosystems and habitats, including oceans, deserts and rainforests, human skin has a number of habitats that support completely different populations of flora and fauna. The warm, swampy areas between the toes are utterly different from the dry, desert-like surfaces of legs. This geography is relevant to a number of diseases. For instance, the face and scalp are rich in lipid-secreting sebaceous glands – which is why they feel oily. This is a perfect habitat for the fat-loving fungus Malassezia and it is believed that an over-abundance of this microorganism is the cause of seborrheic dermatitis. This strange-sounding condition is actually very common, characterized by itchy, red and flaky skin around the nose and eyebrows and dandruff on the scalp

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  Microbiome, Immunity, Digestive Health and Nutrition

  Epidemiology, Pathophysiology, Prevention and Treatment

  • Debasis Bagchi, Bernard William Downs, Bernard W. Downs(Authors)
  • 2022(Publication Date)
  • Academic Press

    (Publisher)

  Meisel et al., 2018 ). Therefore, understanding how the skin microbiota colonizes different sites in the body may provide insight into the pathophysiology of cutaneous infections and could explain how the balance between skin health and disease can be modulated by the microbiota.

  Specific dermatological disorders manifest themselves at different skin sites. As was discussed earlier in the chapter, the skin provides many niches in which large populations of microbes are subjected to a variety of ecological pressures, including humidity, temperature, and pH (Fyhrquist et al., 2016 ; Grice and Segre, 2011 ; Nakatsuji et al., 2013 ; Schommer and Gallo, 2013 ). High temperature and high humidity are associated with increased quantities of bacteria and increased diversity (Knackstedt et al., 2020 ). These ecological factors contribute to the uniqueness of the various skin structures, such as the hair follicles and sebaceous, eccrine, and apocrine glands, which produce a variety of antimicrobial peptides and lipids that can chemically control and regulate the population of microbes on the skin. Competition between microbial species is important for the development and maintenance of a healthy microbiome (Gilbert et al., 2018 ; Kolarsick et al., 2011 ; Lunjani et al., 2019 ; Schommer and Gallo, 2013 ).

  The bacterial species that populate the different regions of the skin are directly related to the microenvironment (Knackstedt et al., 2020 ). Owing to the complexity of the microenvironment, the normal microbiota of the skin is very complex and likely developed through the cooperation of commensal bacteria and competitive exclusion of pathogens (Ouwehand et al., 2003 ). Major bacterial families that are present on the skin include Actinobacteria (51.8%), Firmicutes (24.4%), Proteobacteria (16.5%), and Bacteroidetes (6.3%) with Actinobacteria most abundant on the skin (Grice et al., 2009 ). Major bacterial contributors at the genera level to the skin microbiota are Corynebacterium , Propionibacterium , and Staphylococcus (Grice et al., 2009

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  Human Microbiota and Microbiome, The

  • Julian Marchesi, Julian R Marchesi(Authors)
  • 2014(Publication Date)
  • CAB International

    (Publisher)

  5 The Human Skin Microbiome

  Jia Tong and Huiying Li* University of California, Los Angeles, USA

  5.1 Introduction

  As the largest organ of the human body (Kanitakis, 2002), skin harbours diverse microbial communities at different sites with unique niches. The number of bacterial cells on the human skin is estimated to be approximately 1012 . The microorganisms form complex interactions within the communities and with the host, influencing the skin health of the host. Occurrences of skin diseases are often accompanied by changes in the composition, structure and function of the skin microbiota.

  This chapter describes the composition and variation of the microbial communities at different skin sites and their associations with skin diseases when altered. The content is based on several recent studies on the Skin Microbiome in health and disease using non-culture-based methods. Widely employed clinical and molecular methods in the study of the Skin Microbiome are also introduced.

  5.2 The Habitat – Human Skin

  Human skin is the soft outer covering and the largest organ of the human body. On average, it accounts for 16% of the body weight and an area of 1.6 m2 (woman)–1.8 m2 (man) in adults (Bender and Bender, 1995). It is an integumentary organ and is physically continuous but structurally distinct to mucus membrane, which is the inner surface of human cavities. Together with mucus membrane, the intact human skin protects the body from pathogen invasion and environmental changes.

  5.2.1 Structure of the human skin

  Human skin is composed of two main layers, the epidermis and the dermis (Fig. 5.1 ).

  The epidermis is the surface of the skin and is made up mainly of keratinocytes, which secrete keratin. The epidermis is a stratified structure in a dynamic state, as cells constantly transit from the inner area to the outer region. As moving outwards, keratinocytes mature to become fully keratinized and are ultimately shed from the skin. This cycle, known as the epidermal cell cycle or epidermal transit time, takes about 39 days (Weinstein et al

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  Atopic Dermatitis

  Disease Etiology and Clinical Management

  • Jorge Esparza-Gordillo, Itaru Dekio, Jorge Esparza-Gordillo, Itaru Dekio(Authors)
  • 2012(Publication Date)
  • IntechOpen

    (Publisher)

  Thus, it is appropriate to consider the microbiota as a ‘microbial community’. It is generally accepted that the microbiota become stabilised at different points of balance in AD patients. This altered balance relates to the pathogenesis of AD as will be discussed below. 2.1 Ecology of skin microbiota The microbiota of human skin differs largely according to skin sites. This is probably due to the fact that the structure and physiology of the surface of the skin differs at different sites of the body. This leads to the natural selection of certain species for particular sites. Thus, facial skin may be considered as a ‘swamp’ of sebum, soles could be considered as a ‘pond’ of sweat, axillae could be analogous to a ‘rain forest’, and forearms are ‘deserts’ which generally lack water and lipid. As a reflection of this, for example, healthy facial skin harbours about 10 8 microbial cells per square centimetre, which comprises up to 2 g of microorganisms per face. On the other hand, healthy forearm skin harbours only 10 3 microbes per square centimetre. Therefore, in some body sites, the population is large enough to consider that the microbiota has a certain Atopic Dermatitis – Disease Etiology and Clinical Management 108 physiological effects on the microecology of the skin. The scalp, face, neck, axilla, external genitalia, groin, and soles are examples of such sites. On the other hand, the microbiota seems to have little effect on the skin physiology at other sites with smaller populations, such as arms, hands, and legs. 2.2 Members of the normal skin microbiota Because the skin microbiota differs considerably across different sites of the human body, it is not possible to describe the microbiota of the entire body in a single entity. In general terms, however, the major population of the normal microbiota consists of coagulase-negative Staphylococcus species, Propionibacterium acnes , and Malassezia species.

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  Small Animal Microbiomes and Nutrition

  • Robin Saar, Sarah Dodd(Authors)
  • 2023(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  1 Section I Understanding a Microbiome 3 Small Animal Microbiomes and Nutrition, First Edition. Robin Saar and Sarah Dodd. © 2024 John Wiley & Sons, Inc. Published 2024 by John Wiley & Sons, Inc. Companion website: www.wiley.com/go/saar/1e 1 Common Definitions 1.1 Microbiome There are multiple functional definitions of the term “microbiome.” According to the Human Microbiome Consortium, the microbiome is considered as the community of all microbes recovered from a particular habitat or ecosystem [1]. These microscopic communities, including bacteria, fungi, and viruses, can be found in all living things, including plants, and are found in every different imaginable habitat, from life- forms to soils and bodies of water [2, 3]. Microbiomes can be found on outer surfaces, particularly as biofilms, and within several body systems of animals including the respiratory tract, reproductive organs, integu- mentary, oral cavity, urinary tract, neurological pathways via the brain- gut axis, and the gastrointestinal (GI) tract. Over 30 trillion microbes may reside within the GI system alone [4, 5]. This list is not exhaustive, as this area of knowledge is relatively novel, and innovations allow us to discover microbiomes in organs and systems once thought to be sterile. The total cumulative microbiomes in a human host may weigh as much as 1–3% body mass [4]. While some common trends are being observed in current research, microbiomes are unique for each individual with their diversity and density affected by several intrinsic (genetics, age, sex) and extrinsic (environment, physiological state, antibiotic therapy, health and nutri- tion) factors [6]. These incredibly diverse communities shape the health of the host and influence its physiology, through multiple complex 1 Common Definitions 4 pathways, including influencing remote organ and immune responses.

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  Translational Systems Medicine and Oral Disease

  • Stephen T. Sonis, Alessandro Villa, Stephen Sonis(Authors)
  • 2019(Publication Date)
  • Academic Press

    (Publisher)

  6

  Microbiomics

  Caitlin S.L. Parello      Biomodels, LLC, Watertown, MA, United States

  Abstract

  Microbial cells—including bacteria, fungi, protozoa, and viruses—colonize the epithelial surfaces of humans (and other multicellular eukaryotes), such as the gut, oral cavity, skin, and hair. Collectively, these microbes and their genetic material are called the microbiome. Humans and their microbiomes have coevolved over the course of millennia, and under homeostasis, coexist in a symbiotic relationship. Perturbations to the human microbiome, however, can result in imbalance, potential dysbiosis, and disease. The oral cavity and its contiguous extensions are home to the second most diverse microbial population in the human body. Referred to as the oral microbiome, these microbes interact with host cells of the mouth, and these interactions have been demonstrated to play critical roles in not only dental health and disease but also in systemic health and disease.

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  Microbiology of Wounds

  • Steven Percival, Keith Cutting(Authors)
  • 2010(Publication Date)
  • CRC Press

    (Publisher)

  Other Factors Other factors that affect the diversity of skin microbiota have included body location, hospitalization, illness, medications, sex, race, occupation, and the use of topical Human Skin and Microbial Flora 65 preparations such as soaps, cosmetics, and disinfectants. In general, the low moisture content, the acidic environment (pH of 5.5), the presence of antimicrobial peptides, high salt content, lipids and fatty acids, immunoglobulins, and lysozyme, together with the continual shedding of squames from the surface of the body, create an envi-ronment in skin that is not conducive to extensive microbial proliferation. I NVESTIGATIONS INTO THE N ORMAL F LORA OF THE S KIN OF H EALTHY A DULTS Price 15 reported that microorganisms found on the skin can be divided into resident flora, which are irreversibly attached to the skin or transient flora that do not grow on skin and usually remain dormant, die, or detach after a short period of time. The resident flora of the skin are referred to as the indigenous microbiota considered to exist as a biofilm and has largely been viewed as harmless being composed of com-mensals that rarely damage the host. The transient flora reflects the host’s level of personal hygiene, lifestyle, and personal activities and level of environmental con-tamination. Transient organisms are generally not attached to skin and do not persist and are considered to be more associated with exposed areas of the skin. A third, more occasional category of skin flora has been described as temporary or nomadic flora. A normadic flora represents microorganisms that attach to skin and are able to multiply but only persist for relatively short periods. 16 Much of the research into the indigenous microbiota of human skin was under-taken during the past 50 years.

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  Epigenetics of the Immune System

  • Dieter Kabelitz, Jaydeep Bhat(Authors)
  • 2020(Publication Date)
  • Academic Press

    (Publisher)

  Microbiota, the community of microorganisms inhabiting the body, are integrated part of the host's biology. The human body provides rich in nutrition, firm, and stable environment for microorganisms to settle, while microorganisms help to prevent from colonization by potentially dangerous microbial species and provide the host with essential nutrients for proper functioning. For example, the intestinal flora can synthetize several vitamins including folic acid (vitamin B 9), cobalamin (vitamin B 12), niacin (vitamin B 3), pyridoxal phosphate (the active form of vitamin B 6), pantothenic acid (vitamin B 5), biotin, tetrahydrofolate, and vitamin K. It can also affect absorption of certain minerals such as iron or can help to digest unabsorbed complex carbohydrates into short-chain fatty acids (SCFAs). This mutualistic relationship is a result of millennia of coevolution. Apart from the gastrointestinal tract, the most preferable habitats for indigenous microbiota are oral cavity, oropharynx, vagina, and skin (Fig. 1). As a matter of fact, there are more microorganisms residing inside and on the human body than the number of cells composing the body [1]. They have an enormous impact on our health and progress of diseases and may even influence the host response to vaccines [2]. Microbiota imbalance, termed dysbiosis, has been associated with a risk of developing various disorders such as cancer, inflammatory bowel disease, celiac disease, type 1 (insulin-dependent) diabetes mellitus, obesity, chronic fatigue syndrome, bacterial vaginosis or allergy, and many more [3]. Moreover, mice reared in germ-free conditions exhibit an abnormal development of the immune system including defects in the development of gut-associated lymphoid tissues, aberrant antibody production, and reduction in size and number of Peyer's patches, and mesenteric lymph nodes [4] suggesting a direct effect of microbiota on immune cells

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  Visualizing Human Biology

  • Kathleen A. Ireland(Author)
  • 2018(Publication Date)
  • Wiley

    (Publisher)

  TABLE 11.1 Our Microbiome Helps Maintain Homeostasis 235 Some bacteria produce chemicals that prevent colonization of patho- gens, some secrete toxins that kill specific microbes, and others secrete acids that alter the pH of the area (Figure 11.11). In every case, the core microbiome will provide competition for space and resources, limiting the ability of new bacterial species to settle in and take over. This is important from a disease standpoint. It is difficult for the bacterial spe- cies that causes acne to invade the facial skin when there are already healthy colonies of Staphylococcus sp. happily growing and using most of the available resources of that area. See What a Scientist Sees: Acne, for another look at acne. Our Gut Microbiome Has Far-Reaching Effects Despite there being five separate areas of interest for the HMP and five additional aims for the project, it seems that most of the recent research activity has been focused on understanding the gut microbi- ome. There are hundreds of species of bacteria normally present in the gastrointestinal tract microbiome, and these bacteria do more than just protect our gut lining from further bacterial infection. The bacteria in our intestine help digest compounds that we cannot digest on our own. They provide us with several B vitamins, Vitamin K 2 , folate, and short-chain fatty acids. Some members of this microbiome detoxify compounds we ingested, while others actively protect against patho- gens. Additionally, these bacteria are anaerobic and undergo fermen- tation constantly while in our gut. This excess digestion provides us with up to 10% of our daily energy needs. Perhaps the most far-reaching activity the gut microbiome pro- vides is in regulating our immune system. As our gut microbiome develops, so too does our immune system.

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  The Microbiome Master Key

  How to Harness Microbes—Inside and Out—for Lifelong Health

  • B. Brett Finlay OC, PhD, Jessica M. Finlay PhD(Authors)
  • 2019(Publication Date)
  • Douglas & McIntyre

    (Publisher)

  S. aureus (the pathogen) decreased. The takeaway from all this seems to be that we can actually benefit from this ongoing microbial warfare on our skin. But if we lose the beneficial microbes, we also lose their protection.

  While you wouldn’t want to go around guessing people’s ages by their faces, from a microbial perspective it’s completely possible to do so. Because microbes are our essential companions as we age, and respond to our ever-changing internal and external environments, we can tell someone’s age within a decade just from analyzing a microbial swab of the forehead. Remarkably, people over the age of fifty have distinctly different microbial signatures than younger adults. Scientists are just beginning to uncover exactly how and why the skin’s microbiome shifts and loses diversity as we age. No matter the reason, this phenomenon speaks to the critical need to enhance and maintain your skin microbiota as a robust ecosystem throughout life.

  Cosmetic companies have picked up on this fact: You can now find commercial skincare products that incorporate emerging microbial scientific discoveries into topical applications. At the time of writing, L’Oréal, for example, patented several bacterial treatments for dry and sensitive skin; Estée Lauder patented a skin application with Lactobacillus plantarum; and Clinique sells a foundation with Lactobacillus ferment. Products such as La Roche Lipikar Baume AP, used to treat eczema and other dry skin issues, likewise include bacterial additives to help restore a healthy Skin Microbiome and to stop itching. Keep an eye out for these and more emerging microbial skincare lines.

  Despite this progress, Dr. Greg Hillebrand, a senior skin scientist at Amway, a major health and beauty corporation, believes there is still a serious need for new methods and treatments for aging skin. “The pace of innovation in the anti-aging category is slowing. Conventional topical products like moisturizers, serums, and essences contain active ingredients aimed at preventing or reversing the signs of aging. Retinoids [a class of active ingredients] remain the gold standard, yet they have been around since the 1980s. The skin microbiota represents an exciting new focus area for us, and it’s the next best opportunity to solve many of the challenges associated with aging skin.” Dr. Hillebrand’s enthusiasm for the use of microbes goes back to 1995. He was sent to Japan by his former employer, Procter and Gamble, to figure out exactly how it worked by studying a prestige skincare line that consisted of a concentrated fungi ferment cultivated, processed, and filtered down into an essence product. “Many of my colleagues at the time did not actually believe it did anything; they all thought it was ‘foo-foo dust.’ I was only there for a few months when my director from the US came over to see how I was doing. I was excited to share my progress and ideas and met with him and my VP. I told them that I thought it might be possible that the fermented filtrate worked in part by favourably modulating the bacteria on the face in a way that we didn’t yet understand. Basically, I was proposing that the use of the product might shift the bacterial composition, perhaps maintaining the good ones and not the bad ones on the face.” In 1995, we didn’t yet appreciate the concept of “good” and “bad” bacteria on the skin—it simply wasn’t conceivable that the skin microflora were important; we certainly didn’t culture bacteria specifically

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  Topical Antimicrobials Testing and Evaluation

  • Daryl Paulson, Daryl S. Paulson(Authors)
  • 2014(Publication Date)
  • CRC Press

    (Publisher)

  31 3 Skin Microbiology The second leg of the skin–antimicrobial triangle deals with microorganisms. Bacteria, fungi, and viruses are the causative agents of disease. In evaluating topical antimicrobial products such as surgical scrubs, preoperative prepping solu-tions, and healthcare personnel handwashes, bacteria, fungi, and viruses are also the indices for estimating antimicrobial effectiveness (see Figure 3.1). I. ETIOLOGY OF INFECTIOUS DISEASES For an infectious disease to spread, the following events must occur [28]: 1. Encounter: The host must be exposed to the microorganism (bacteria, fungi, viruses). 2. Entry: The microorganism must enter the host. For example, a fungus can attach itself to skin, nails, or hair. This is a superficial or cutaneous infection, where the fungus has been taken from its normal reservoir or soil. Other types of fungi can change from multicellular conidia-bearing mycelium into single-cell yeasts (dimorphisms) that can live in a parasitic form at 37°C. 3. Spread: The microorganism must spread from the entry site. 4. Multiplication: The microorganism must multiply within the host. 5. Damage: The microorganism and its metabolites and/or the host’s immu-nological response cause light to extensive tissue damage in the host. All five of these steps are required in breaching the host’s defenses. The actual dis-ease produced by the microorganism depends upon the entry conditions, the host’s response, and the species and strain of microorganism [29]. A. E NCOUNTER AND E NTRY A host is exposed to the microorganism (bacteria, fungi, viruses) in a variety of situations relevant to the user and type of topical antimicrobial compound [14].

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