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Disease ⇒ Atopy ⇒ Atopic Dermatitis {40000111}

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Atopic Dermatitis


Initialisation date:
Other Terms:
Atopic eczema, AD, Infantile Eczema


Meta Information

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MedDra Level:
ICD:[  ]
Mechanism:[  ]


- Sufferers of AD tend to have higher proportions of Clostridia (including Clostridium difficile), Escherichia coli, and Staphylococcus aureus than do healthy controls, as well as lower numbers of healthy Bifidobacteria, Bacteroidetes, and Bacteroides.
- The bacterium Roseomonas mucosa reduced the severity of atopic dermatitis in adults and children.
- Most children in the study experienced substantial improvements in their skin and overall wellbeing following R. mucosa therapy. Encouragingly, the therapeutic bacteria stayed on the skin and continued to provide benefit after therapy stopped.
- Seventeen of the 20 children experienced a greater than 50% improvement in eczema severity following treatment. Improvement occurred on all treated skin sites, including the inner elbows, inner knees, hands, trunk and neck. The scientists also observed increases in the skin’s barrier function—its ability to seal in moisture and keep out allergen.(3)

- A specific set of lipids produced by R. mucosa strains isolated from healthy skin can induce skin repair processes and promote turnover of skin tissue. Study participants had increased levels of these lipids on their skin after treatment with R. mucosa. (4)

- The abundance of S. aureus is greater in lesional than in non-lesional skin in AD, in a dose-dependent manner - with higher colonisation rates in severe eczema.
- 62% of lesional skin samples produced at least one identifiable exotoxin. Exotoxins from S. aureus strains isolated from AD patients often have superantigenic properties and stimulate T-lymphocytes directly.
- Children and young adults with AD had significantly lower gut concentrations of Bifidobacteria than controls (measured by stool sample analysis), and the concentration was inversely correlated with AD disease severity.
- Low total gut and Bacteroidetes diversity at 1 month has been associated with the development of AD at 2 years of age. (5)
- Faeclibacerium prausnitzii and Ruminococcus gnavus are increased in patients with AD, whereas Bacteroides fragilis and Streptococcus salivaris, are less abundant

Shared Reference Notes

  • [1.1
    - Skin dysbiosis in AD is characterized by increased abundance of Staphylococcus aureus. In the presence of this dysbiosis and barrier dysfunction, external stimuli such as infection, allergens, and mechanical injury lead to activation of skin keratinocytes to produce interleukin (IL)-33, IL-25, and thymic stromal lymphopoietin (TSLP), inducing differentiation of T helper type 2 (Th2) cells that secrete IL-4, IL-5, and IL-13 and resulting in Th2 inflammation. This inflammation can in turn activate keratinocytes, forming a vicious cycle that maintains skin inflammation in AD. - Skin dysbiosis in AD is characterized by increased abundance of Staphylococcus aureus.
  • [1.2
    - Corynebacterium simulans and Prevotella melaninogenica are positively and negatively correlated with AD severity, respectively. - The abundance of Prevotella melaninogenica decreased gradually with an increase in disease severity and increased after treatment.
  • [1.3
    - AD subjects is characterized by reduced microbial richness, depletion of #Cutibacterium acnes, #Dermacoccus and #Methylobacterium species.
  • [1.4] [#Multiple Sclerosis
    - Orally administered EDP1867, a gamma-irradiated strain of #Veillonella parvula, rapidly transits through the murine gut without colonization or alteration of the background microbiome flora. - In murine models of inflammatory disease including delayed-type hypersensitivity (DTH), atopic dermatitis, #Psoriasis, and experimental autoimmune encephalomyelitis (EAE), treatment with EDP1867 resulted in significant reduction in inflammation and immunopathology.
  • [1.5
    - #Malassezia spp. colonization increases with AD severity and has been detected in up to 90% of skin lesions.
  • [#Staphylococcus aureus, #Staphylococcus lugdunensis] - #Staphylococcus hominis, S. lugdunensis and S. epidermidis produce several molecules capable of synergizing the innate antimicrobial response against S. aureus
  • [#Staphylococcus epidermidis, #Staphylococcus aureus] - increased abundance of S. aureus with depletion of S. epidermidis and #Corynebacterium spp. among AD patients. - S. epidermidis, a commensal present on non–inflamed skin, appears to be S. aureus best antagonist. - less severe flares of AD had higher counts of S. epidermidis whereas the more severe flares were associated with S. aureus
  • [1.6] [#Staphylococcus aureus
    - samples where S. aureus was highly abundant, lower abundances of S. hominis and Cutibacterium acnes were observed. M. osloensis and M. luteus were more abundant in AD. - The flexures exhibited lower alpha-diversity and were colonized by S. aureus, accompanied by S. epidermidis in lesions. Malassezia species were absent on the neck in AD.
  • [1.7
    - #Vitamin D-associated 3-hydroxyisobutyric acid and glutamine were positively correlated with atopic disease-associated succinic acid and alanine, respectively. - hippuric acid was negatively correlated with atopic disease-associated formic acid, which was positively correlated with #Vitamin D level. - Absolute eosinophil count (AEC) was positively correlated with serum D. pteronyssinus- and D. farinae -specific IgE level
  • [1.8] [#Staphylococcus aureus
    - S. aureus, a dominant species among the family of Staphylococcae, can be 100 times more abundant in AD skin compared to normal healthy skin. - AD is associated with a depletion in the coagulase-negative staphylococcal species (CoNS), such as S. epidermidis, S. hominis, and other skin commensal bacterial communities, including Streptococcus salivarius, Propionibacterium, Streptococcus, Acinetobacter, Corynebacterium, Prevotella and Proteobacteria. - AD patients exhibit abundant S. aureus in their gut microbiota
  • [1.9] [#Allergy] [#High-fiber diet
    - Epidemiological evidence indicates that children suffering from allergies have lower levels of dietary fibre-derived short-chain fatty acids (SCFA). Using an experimental model of AD-like skin inflammation, - a fermentable fibre-rich diet alleviates systemic allergen sensitization and disease severity. - particularly butyrate, which strengthens skin barrier function by altering mitochondrial metabolism of epidermal keratinocytes and the production of key structural components.
  • - children and infants suffering from AD, or prone to develop allergic sensitization later in childhood43, exhibit a gut microbiota characterized by a reduced capacity to produce SCFA, particularly #Butyrate.
  • - the skin of patients with atopic dermatitis is characterized by a higher prevalence of S. aureus
  • [1.11
    - Supplement #Lactobacillus rhamnosus > increase #Butyrate production > reduce atopic symptoms
  • [1.12] [#Staphylococcus epidermidis
    - S. epidermidis is also frequently detectable in the skin of patients with the inflammatory skin disease atopic dermatitis (AD) and some studies reported a significantly higher presence of S. epidermidis in severe AD as compared to mild AD. - Various S. epidermidis skin-derived isolates activated the proinflammatory transcription factor NF-kappaB and induced expression of AD-associated proinflammatory cytokines in human primary keratinocytes and 3D skin equivalents.
  • [1.13
    - Increased richness and abundance of #Staphylococcus, Lactococcus, and #Alternaria were found in atopics. - #Staphylococcus and #Alternaria formed robust mixed-species biofilms (based on XTT and SEM) that were resistant to antifungals/antimicrobials. - their biofilm supernatant was capable of influencing keratinocytes biology (pro-inflammatory cytokines and structural proteins), suggesting an additive effect on AD-associated host response.
  • [1.14] [#Natural Skin Microbiome
    - skin colonization by commensal #Staphylococci species has been associated with lower incidence of AD in babies, suggesting these bacteria may also play a role in the disease development.
  • - in #Infants > #Staphylococcus epidermidis was found protective against AD as well as in older populations
  • [1.15
    - Allergic infants are more frequently colonised that those who are not allergic by adult-like Bifidobacterium (such as B. adolescentis), while in healthy infants the Bifidobacterium population was dominated by B. bifidum. - The antimicrobial activity was identified as previously unknown antimicrobial peptides (AMPs) produced by CoNS species including Staphylococcus epidermidis and Staphylococcus homini. These AMPs were strain-specific, highly potent, selectively killed S. aureus, and synergized with the human AMP LL-37.

References Notes

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Common References