MetaBiom
Microbiome & Chronic Diseases

Evidence Based Medicine

Atopic Dermatitis {40000111}

Record Keys


Definition:
Atopic Dermatitis
Class:[  ]

Details


Other Terms:
Atopic eczema, AD, Infantile Eczema
Authoring date:
2020-09-06

Links


Meta Information


ICD:[  ]
Category:
Dermatology
MedDra ID:
10012438
MedDra Level:
4

Notes


- 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)

Shared Notes


  • [1.14
    - 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.
  • [1.15
    - 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.
  • [1.16
    - 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.
  • [1.17
    - AD subjects is characterized by reduced microbial richness, depletion of Cutibacterium acnes, Dermacoccus and Methylobacterium species.

Common References