The etiology of arthritis has been sought for centuries, employing the art and science of the times to clarify, identify, and establish a cause and a cure. None other than Sir William Osler in his 1909 edition of Principles and Practice of Medicine stated that the etiology/origin of rheumatoid arthritis was related to “the nervous system or infections, with exciting causes that included age, gender, daily history, cold, damp, errors in diet, worry and care, and local injuries.”
To access to full article: The microbiome, autoimmunity, and arthritis: cause and effect: an historical perspective
Recent years’ investigations of the co-evolution and functional integration of the human body and its commensal microbiota have disclosed that themicrobiome has a major impact on physiological functions including protection against infections, reaction patterns in the immune system, and disposition for inflammation-mediated diseases.
To access to full article: Bacterial skin commensals and their role as host guardians (Image from the article)
Objectives: We investigated the facial skin microbiota of Japanese acne patients. Methods: Skin swab samples were obtained from 100 acne patients and 28 healthy controls to evaluate Propionibacterium and Staphylococcus spp. using a culture method. Malassezia spp. were evaluated using a nonculture method. Antibiotic resistance of Propionibacterium spp. was also examined.
To access to abstract: Analysis of Facial Skin-Resident Microbiota in Japanese Acne Patients
In the last decade, an extensive effort has been made to characterize the human microbiota, due to its clinical and economic interests. However, a metagenomic approach to the skin microbiota is hampered by the high proportion of host DNA that is recovered. In contrast with the burgeoning field of gut metagenomics, skin metagenomics has been hindered by the absence of an efficient method to avoid sequencing the host DNA. We present here a method for recovering microbial DNA from skin samples, based on a combination of molecular techniques.
To access to full article: A new method for extracting skin microbes allows metagenomic analysis of whole-deep skin (Image from the article)
The resident microbial community, harboured by humans in sites such as the skin and gastrointestinal tract, is enormous, representing a candidate environmental factor affecting susceptibility to complex diseases, where both genetic and environmental risk factors are important. The potential of microorganisms to influence the human immune system is considerable, given their ubiquity. The impact of the host-gene-microbe interaction on the maintenance of health and the development of disease has not yet been assessed robustly in chronic inflammatory conditions.
To access to abstract: The bacterial skin micro biome in psoriatic arthritis an unexplored link in pathogenesis: challenges and opportunities offered by recent technological advances (Image from http://arthritishelppc.blogspot.com/2012/04/psoriatic-arthritis-vs-psoriasis.html)
The skin is colonized by a plethora of microbes that include commensals and potential pathogens, but it is currently unknown how cutaneous host immune mechanisms influence the composition, diversity, and quantity of the skin microbiota. Here we reveal an interactive role for complement incutaneous host-microbiome interactions.
To access to abstract: Complement modulates the cutaneous microbiome and inflammatory milieu (Image adapted from http://www.pickyourdrugs.com/all-news/hand-bacteria-may-one-day-aid-forensic-identification-study)
Circumcision is associated with significant reductions in HIV, HSV-2 and HPV infections among men and significant reductions in bacterial vaginosis among their female partners.
Access to full article: The Effects of Circumcision on the Penis Microbiome (Image adapted from http://guardianlv.com/2013/09/does-circumcision-prevent-hiv/)
Recent years witnessed the birth of bioinformatics technologies, which greatly advanced biological research. These ‘omics’ technologies address comprehensively the entire genome, transcriptome, proteome, microbiome etc. A large impetus in development of bioinformatics was the introduction of DNA microarrays for transcriptional profiling. Because of its accessibility, skin was among the first organs analyzed using DNA microarrays, and dermatology among the first medical disciplines to embrace the approach. Here, DNA microarray methodologies and their application in dermatology and skin biology are reviewed.
To access to the full artice: Skinomics: Transcriptional Profiling in Dermatology and Skin Biology (Image adapted from http://boston.cityscienceclub.com/2012/09/21/pigment-mutation-a-likely-key-to-detecting-skin-cancer/)
Recent advances in sequencing technologies have enabled metagenomic analyses of many human body sites. Several studies have catalogued the composition of bacterial communities of the surface of human skin, mostly under static conditions in healthy volunteers. Skin injury will disturb the cutaneous homeostasis of the host tissue and its commensal microbiota, but the dynamics of this process have not been studied before. Here we analyzed the microbiota of the surface layer and the deeper layers of the stratum corneum of normal skin, and we investigated the dynamics of recolonization of skin microbiota following skin barrier disruption by tape stripping as a model of superficial injury.
To access to the full article: Microbiome dynamics of human epidermis following skin barrier disruption (Image adapted from the article)
This article reviews recent findings on the skin microbiome. It provides an update on the current understanding of the role of microbiota in healthy skin and in inflammatory and allergic skin diseases.
To access to abstract of the full article: Microbiome and skin diseases (Image adapted from http://bioloskiblog.wordpress.com)
Complex communities of bacteria, fungi, and viruses thrive on our skin. The composition of these communities depends on skin characteristics, such as sebaceous gland concentration, moisture content, and temperature, as well as on host genetics and exogenous environmental factors. Recent metagenomic studies have uncovered a surprising diversity within these ecosystems and have fostered a new view of commensal organisms as playing a much larger role in immune modulation and epithelial health than previously expected. Understanding microbe-host interactions and discovering the factors that drive microbial colonization will help us understand the pathogenesis of skin diseases and develop new promicrobial and antimicrobial therapeutics
To access to abstract of the full article: The skin microbiome: Current perspectives and future challenges (Image adapted from the article)
Scabies is a worldwide disease and a major public health problem in many developing countries, related primarily to poverty and overcrowding. In remote Aboriginal communities in northern Australia, prevalences of up to 50% among children have been described, despite the availability of effective chemotherapy. Sarcoptic mange is also an important veterinary disease engendering significant morbidity and mortality in wild, domestic, and farmed animals. Scabies is caused by the ectoparasitic mite Sarcoptes scabiei burrowing into the host epidermis. Clinical symptoms include intensely itchy lesions that often are a precursor to secondary bacterial pyoderma, septicemia, and, in humans, poststreptococcal glomerulonephritis.
To access to the full article: Problems in Diagnosing Scabies, a Global Disease in Human and Animal Populations (Image adapted from the article)
Scabies is a serious disease of both humans and other animals caused by infestation of the skin with the ectoparasitic mite Sarcoptes scabiei. Our current understanding of scabies mite biology and disease processes is far outweighed by the significant, worldwide impact of the disease. This review summarizes the recent data which furthers our knowledge of mite biology, host specificity and parasite host evasion mechanisms.
To access to abstract of the article: Novel insights into an old disease: recent developments in scabies mite biology
Atopic dermatitis (AD) has long been associated with Staphylococcus aureus skin colonization or infection and is typically managed with regimens that include antimicrobial therapies. However, the role of microbial communities in the pathogenesis of AD is incompletely characterized. To assess the relationship between skin microbiota and disease progression, 16S ribosomal RNA bacterial gene sequencing was performed on DNA obtained directly from serial skin sampling of children with AD. The composition of bacterial communities was analyzed during AD disease states to identify characteristics associated with AD flares and improvement post-treatment. We found that microbial community structures at sites of diseasepredilection were dramatically different in AD patients compared with controls. Microbial diversity during AD flares was dependent on the presence or absence of recent AD treatments, with even intermittent treatment linked to greater bacterial diversity than no recent treatment.
To access to the full article: Temporal shifts in the skin microbiome associated with disease flares and treatment in children with atopic dermatitis (Image from the article)
The recent era of exploring the human microbiome has provided valuable information on microbial inhabitants, beneficials and pathogens. Screening efforts based on DNA sequencing identified thousands of bacterial lineages associated with human skin but provided only incomplete and crude information on Archaea. Here, we report for the first time the quantification and visualization of Archaea from human skin. Based on 16 S rRNA gene copies Archaea comprised up to 4.2% of the prokaryotic skin microbiome. Most of the gene signatures analyzed belonged to the Thaumarchaeota, a group of Archaea we also found in hospitals and clean room facilities. The metabolic potential for ammonia oxidation of the skin-associated Archaea was supported by the successful detection of thaumarchaeal amoA genes in human skin samples. However, the activity and possible interaction with human epithelial cells of these associated Archaea remains an open question. Nevertheless, in this study we provide evidence that Archaea are part of the human skin microbiome and discuss their potential for ammonia turnover on human skin
To access to the full article: Archaea on human skin (Image adapted from http://archaea.u-psud.fr)
Bacterial interference creates an ecological competition between commensal and pathogenic bacteria. Through fermentation of milk with gut-friendly bacteria, yogurt is an excellent aid to balance the bacteriological ecosystem in the human intestine. Here, we demonstrate that fermentation of glycerol with Propionibacterium acnes (P. acnes), a skin commensal bacterium, can function as a skin probiotic for in vitro and in vivo growth suppression of USA300, the most prevalent community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). We also promote the notion that inappropriate use of antibiotics may eliminate the skin commensals, making it more difficult to fight pathogen infection. This study warrants further investigation to better understand the role of fermentation of skin commensals in infectious disease and the importance of the human skin microbiome in skin health.
To access to the full article: Fermentation of Propionibacterium acnes, a commensl bacterium in the human skin microbiome, as skin probiotics against methicillin-resistant Staphylococcus aureus (Image adapted from http://www.acpinternist.org/archives/2006/12/mrsa.htm)
Traditional culture-based methods have incompletely defined the microbial landscape of common recalcitrant human fungal skin diseases, including athlete’s foot and toenail infections. Skin protects humans from invasion by pathogenic microorganisms and provides a home for diverse commensal microbiota. Bacterial genomic sequence data have generated novel hypotheses about species and community structures underlying humandisorders. However, microbial diversity is not limited to bacteria; microorganisms such as fungi also have major roles in microbial community stability, human health and disease. Genomic methodologies to identify fungal species and communities have been limited compared with those that are available for bacteria.
To access to abstract of the article: Topographic diversity of fungal and bacterial communities in human skin (Image adapted from http://www.eviberoammicol.com)
In a healthy host, a balance exists between members of the microbiota, such that potential pathogenic and non-pathogenic organisms can be found in apparent harmony. During infection, this balance can become disturbed, leading to often dramatic changes in the composition of the microbiota. For most bacterial infections, nonspecific antibiotics are used, killing the non-pathogenic members of the microbiota as well as the pathogens and leading to a substantial delay in the restoration of a healthy microbiota. However, in some cases, infections can self-resolve without the intervention of antibiotics. In this Review, we explore the mechanisms underlying microbiota restoration following insult (antibiotic or otherwise) to the skin, oral cavity, and gastrointestinal and urogenital tracts, highlighting recovery by natural processes and after probiotic administration.
To access to abstract of the article: Microbiota restoration: natural and supplemented recovery of human microbial communities (Image from the article)
Commensal microbes on the skin surface influence the behavior of cells below the epidermis. We hypothesized that bacteria or their products exist below the surface epithelium and thus permit physical interaction between microbes and dermal cells. Here, to test this hypothesis, we employed multiple independent detection techniques for bacteria including qPCR, Gram-staining, immunofluorescence, and in situ hybridization. Bacteria were consistently detectable within the dermis and dermal adipose of normal human skin. Sequencing of DNA from dermis and dermal adipose tissue identified bacterial 16S rRNA reflective of a diverse and partially distinct microbial community in each skin compartment. These results show the microbiota extends within the dermis, therefore enabling physical contact between bacteria and various cells below the basement membrane. These observations show that normal commensal bacterial communities directly communicate with the host in a tissue previously thought to be sterile.
To access to the full article: The microbiome extends to subepidermal compartments of normal skin
Psoriasis is a common chronic inflammatory disease of the skin. We sought to use bacterial community abundance data to assess the feasibility of developing multivariate molecular signatures for differentiation of cutaneous psoriatic lesions, clinically unaffected contralateral skin from psoriatic patients, and similar cutaneous loci in matched healthy control subjects.
To access to abstract of the article: Microbiomic signatures of psoriasis: feasibility and methodology comparison
The human skin microbiome has important roles in skin health and disease. However, bacterial population structure and diversity at the strain level is poorly understood. We compared the skin microbiome at the strain level and genome level of Propionibacterium acnes, a dominant skincommensal, between 49 acne patients and 52 healthy individuals by sampling the pilosebaceous units on their noses. Metagenomic analysis demonstrated that although the relative abundances of P. acnes were similar, the strain population structures were significantly different in the two cohorts. Certain strains were highly associated with acne, and other strains were enriched in healthy skin.
To access to abstract of the article: Propionibacterium acnes Strain Populations in the Human Skin Microbiome Associated with Acne
Chronic mucocutaneous candidiasis (CMC) and hyper-IgE syndrome (HIES) are primary immunodeficiencies mainly caused by mutations in STAT1 and STAT3, respectively. CMC and HIES patients have an increased risk for skin and mucosal infections with fungal pathogens and Staphylococcus aureus. However, it is unknown whether the genetic defects in these patients also affect the skin and mucosal microbiome, which in turn may influence host defense mechanisms
To access to abstract of the article: Skin Microbiome Imbalance in Patients with STAT1/STAT3 Defects Impairs Innate Host Defense Responses
Probiotics may reduce the risk of atopy and asthma in children. However, results from clinical trials have been conflicting, and several of them may have been underpowered. We performed a meta-analysis of randomized, placebo-controlled trials to assess the effects of probiotic supplementation on atopic sensitization and asthma/wheeze prevention in children
To access to abstract of the article: Probiotic Administration in Early Life, Atopy, and Asthma: A Meta-analysis of Clinical Trials
Rosacea is a skin condition of abnormal inflammation and vascular dysfunction. The active contribution of a microbial agent in the development or progression of rosacea continues to be debated. Research supports the presence of commensal Demodex folliculorum mites at increased density in the skin and associates Helicobacter pylori infection of the gut with rosacea. Fewer studies implicate Staphylococcus epidermidis, Chlamydophila pneumoniae, and the Demodex-associated bacteria Bacillus oleronius. No research, however, provides a mechanism by which colonization by a microorganism translates to manifestation of the condition. Prevailing and emerging principles in the biology of the microbiome and the pathophysiology of rosacea may help to reconcile these lingering questions. Here the microorganisms implicated in rosacea are reviewed and the reaction of the microbiome to inflammation and to changes in microenvironments and macroenvironments are discussed to explain potential roles for microorganisms in rosacea pathophysiology
To access to abstract of the article: Potential role of microorganisms in the pathogenesis of rosacea
Rosacea is a common dermatological condition that predominantly affects the central regions of the face. Rosacea affects up to 3 % of the world’s population and a number of subtypes are recognized. Rosacea can be treated with a variety of antibiotics (e.g. tetracycline or metronidazole) yet no role for bacteria or microbes in its aetiology has been conclusively established. The density of Demodex mites in the skin of rosacea patients is higher than in controls, suggesting a possible role for these mites in the induction of this condition. In addition, Bacillus oleronius, known to be sensitive to the antibiotics used to treat rosacea, has been isolated from a Demodex mite from a patient with papulopustular rosacea and a potential role for this bacterium in the induction of rosacea has been proposed. Staphylococcus epidermidis has been isolated predominantly from the pustules of rosacea patients but not from unaffected skin and may be transported around the face by Demodex mites. These findings raise the possibility that rosacea is fundamentally a bacterial disease resulting from the over-proliferation of Demodex mites living in skin damaged as a result of adverse weathering, age or the production of sebum with an altered fatty acid content. This review surveys the literature relating to the role of Demodex mites and their associated bacteria in the induction and persistence of rosacea and highlights possible therapeutic options.
To access to abstract of the article: Potential role of Demodex mites and bacteria in the induction of rosacea
The skin is the human body’s largest organ, colonized by a diverse milieu of microorganisms, most of which are harmless or even beneficial to their host. Colonization is driven by the ecology of the skin surface, which is highly variable depending on topographical location, endogenous host factors and exogenous environmental factors. The cutaneous innate and adaptive immune responses can modulate the skin microbiota, but the microbiota also functions in educating the immune system. The development of molecular methods to identify microorganisms has led to an emerging view of the resident skin bacteria as highly diverse and variable. An enhanced understanding of the skin microbiome is necessary to gain insight into microbial involvement in human skin disorders and to enable novel promicrobial and antimicrobial therapeutic approaches for their treatment. For the complete article, please visit “The skin microbiome” by Dr. Julie Segre and Elizabeth Grice.
Recent advances in DNA sequencing methodology have enabled studies of human skin microbes that circumvent difficulties in isolating and characterizing fastidious microbes. Sequence-based approaches have identified greater diversity of cutaneous bacteria than studies using traditional cultivation techniques. However, improved sequencing technologies and analytical methods are needed to study all skin microbes, including bacteria, archaea, fungi, viruses, and mites, and how they interact with each other and their human hosts. This review discusses current skin microbiome research, with a primary focus on bacteria, and the challenges facing investigators striving to understand how skin micro-organisms contribute to health and disease.
Please visit “Skin microbiome: genomics-based insights into the diversity and role of skin micribes” for a full article.
Intestinal commensal bacteria induce protective and regulatory responses that maintain host-microbial mutualism. However, the contribution of tissue-resident commensals to immunity and inflammation at other barrier sites has not been addressed. We found that in mice, the skin microbiota have an autonomous role in controlling the local inflammatory milieu and tuning resident T lymphocyte function. Protective immunity to a cutaneous pathogen was found to be critically dependent on the skin microbiota but not the gut microbiota. Furthermore, skin commensals tuned the function of local T cells in a manner dependent on signaling downstream of the interleukin-1 receptor. These findings underscore the importance of the microbiota as a distinctive feature of tissue compartmentalization, and provide insight into mechanisms of immune system regulation by resident commensal niches in health and disease.
To access to the full article, please visit “Compartmentalized control of skin immunity by resident commensals“