Lab ⇒ Natural Skin Microbiome {40000556}

Shared Reference Notes

• [1.1] 
  - The most dominant genus in the skin are Staphylococcus, Propionibacterium, Corynebacterium, and Streptococcus. - Furthermore, oilier sites have significant dominance of Propionibacterium species (lipophilic), whereas in humid niches, Staphylococcus and Corynebacterium species thrive
• - Skin microbiome > #Children have a marked profile of Ascomycetes and lower levels of Malassezia when compared to adults.
• [1.2] 
  - the moist sites of skin are primarily colonized by members of the genera #Staphylococcus and #Corynebacterium.
• - Members of the genus #Cutibacterium (previously known as #Propionibacterium), dominate the sebaceous (oily) sites of the human skin.
• [#Gender] - female genital tract is characterized by a predominance of #Lactobacillus.
• - The sebum produced by the sebaceous gland lubricates the hair and skin. - #Sapienic acid produced by the hydrolysis of sebum by commensal microbes acts alongside other antimicrobial peptides such as cathelicidin, beta-defensins, and antimicrobial histones to control microbial colonization. - Eccrine sweat secreted directly onto the skin surface creates unfavorable conditions for the survival and proliferation of microbes. - The highly colonized dermal appendage is home to a variety of microbes. This environment allows for ample interaction between microorganisms and host cells.
• [#Staphylococcus aureus] - Other Staphylococcus spp. that inhabit the skin of humans, for example #Staphylococcus hominis and #Staphylococcus lugdunensis, may produce antimicrobial peptides that specifically inhibit colonization by S. aureus.
• - #Staphylococcus epidermidis, can also interact with the host’s keratinocytes directly, thereby inducing the production of antimicrobial peptides via immune cell signaling.
• [1.3] [#Dry Skin] 
  - abundant skin commensal #Staphylococcus epidermidis contributes to skin barrier integrity. - S. epidermidis secretes a sphingomyelinase that acquires essential nutrients for the bacteria and assists the host in producing #Ceramides, the main constituent of the epithelial barrier that averts skin dehydration and aging. - In mouse models, S. epidermidis significantly increases skin ceramide levels and prevents water loss of damaged skin in a fashion entirely dependent on its sphingomyelinase.
• [1.4] [#Staphylococcus epidermidis] 
  - Skin barrier molecules such as filaggrin were downregulated by S. epidermidis.
• [1.5] [#Staphylococcus aureus] 
  - upon injury, adaptive responses to the microbiota directly promote sensory neuron regeneration. - At homeostasis, tissue-resident commensal-specific T cells colocalize with sensory nerve fibers within the dermis, express a transcriptional program associated with neuronal interaction and repair, and promote axon growth and local nerve regeneration following injury.
• [1.6] 
  - Skin wounds heal faster in humans who receive probiotics.
• [#Severe skin and soft tissue infection] [#Dermatologic Filler] - The control group had significantly higher levels of beneficial #Staphylococcus epidermidis than the study group. - Those with infections had significantly higher levels of pathogenic bacteria, including Staphylococcus aureus, Klebsiella pneumoniae , Klebsiella oxytoca , and Staphylococcus haemolyticus when compared with the control group. - The differences in nasal skin flora may predispose filler recipients to a late-onset biofilm infection.
• - age-related skin findings, specifically wrinkles, and spots, were associated with two #Corynebacteria taxa. - The Corynebacterium signal was especially consistent in older forehead skin and corresponded with wrinkles and spots.
• - #Probiotic #Lactobacillus johnsonii plus carotenoids reduced signs of UV-induced skin damage triggered by simulated or natural sun exposure.
• - #Probiotic #Lactobacillus plantarum > transepidermal water loss (TEWL) was much less in the #Probiotic group at Week 12. Wrinkle depth significantly decreased in the #Probiotic group by Week 12, along with significant improvement in skin gloss. - skin elasticity, improved 13.17% in the #Probiotic group after 4 weeks, and 21.73% after 12 weeks > facial skin anti-aging.
• - #Nitrosomonas eutropha, a non-pathogenic bacterium, oxidize ammonia in sweat to nitrite and #Nitric Oxide, which have anti-inflammatory effects > reduced the number of pathogenic bacteria on the skin and improved skin healing. - after 7 days of twice-daily facial high-dose mist use > improved Wrinkle depth and severity and Forehead and glabellar pigmentation.
• - High gut #Phenol levels are associated with reduced skin hydration and impaired keratinization. - phenols produced by gut bacteria also adversely affect keratinocyte differentiation.
• - The microbiome of healthy skin varies depending on age and body area, with differences in sebaceous, moist, and dry areas. - An age-related decrease in the #Propionibacterium may have also contributed to the increased bacterial diversity observed in the older subjects. - a positive correlation between sebum level and the abundance of #Propionibacterium in forehead skin.
• [#Ceramides] - probiotic lysate of the bacterium #Streptococcus thermophiles > sphingomyelinase, an enzyme that converts sphingomyelin to phosphocholine and ceramide, providing a means for ceramide production > treated areas had significant increases in hydration and in stratum corneum ceramide levels.
• [1.7] 
• [1.8] 
• [1.9] [#Atopic Dermatitis] 
  - 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.
• [#Infants] - Infant skin > 21 bacterial phyla with #Proteobacteria, #Firmicutes, #Actinobacteria, and #Bacteroidetes being the most abundant. - the relative abundance of #Burkholderiaceae and #Staphylococcus, highly abundant after birth, decreased progressively, to the benefit of newly colonizing taxa such as #Streptococcus, #Veillonella, and #Enhydrobacter aerosaccus
• [#Infants] - Infant Skin > #Lactobacillus iners were most abundant at day 1 after birth and dropped afterward.
• [#Human breast milk, #Infants] - Infant Skin > Breastfeeding > at 3 and 6 months, respectively > lower abundances and frequencies of members of the #Prevotellaceae family at both timepoints
• - Skin microbes secrete enzymes involved in skin homeostasis; protease enzymes play a role in stratum corneum renewal, lipase enzyme is involved in lipidic film surface breakdown; and urease enzyme is implicated in urea degradation.
• - #Aging > significant increase in #Corynebacterium on the cheeks and forehead and #Acinetobacter on the scalp in the older group.
• [#Aging] - a decrease in #Acinetobacter and an increase in #Proteobacteria on older skin.
• - Skin #Aging is characterized by a decrease in sebum, sweat, and immune function, resulting in significant alternations in the skin surface’s physiology, including lipid composition, sebum secretion, and pH. - These affect skin dryness, collagen fragmentation, reduction in the total amount of collagen and elastin, as well as influencing the skin ecology, possibly shaping the skin microbiome
• [#Corynbacterium kroppenstedtiin, #Corynebacterium amycolatum] [#Aging] - increased abundance of Corynbacterial taxa, including C. kroppenstedtiin and C. amycolatum in the forehead area
• [#Aging] - At the genus level, old-aged skin exhibited an increase in #Corynebacterium and a decrease in #Cutibacterium relative abundance
• - #Aging > #Cutibacterium decreased in the cheeks, forehead, and forearms
• [#Teenager] - Gemmatimonadetes, #Planctomycetes, and Nitrospirae are more prevalent in healthy teenagers skin.
• - The generation of #Reactive Oxygen Species secondary to normal aerobic metabolism, and exogenous factors, such as #UV radiation, is the main cause of skin #Aging
• [1.11] [#Antimicrobial peptides, #Cathelicidin] 
  - Host-derived AMPs, also known as host defence peptides (HDP)s are either constitutively produced by keratinocytes and immune cells or induced in response to stimuli such as pathogen-associated molecular patterns (PAMPs) or inflammatory cytokines. Some important classes of HDPs include RNases, defensins, cathelicidins, dermcidin, and S100 class peptides. - Some important classes of HDPs include RNases, defensins, cathelicidins, dermcidin, and S100 class peptides.
• - #Cutibacterium acnes associated with healthy skin were shown to activate the release of extracellular traps from specialized Th17 subsets
• - #Roseomonas mucosa secretes #Glycerophospholipids which induce host epithelial repair by enhancing the cholinergic activation via TNFR2 signalling
• - Coagulase negative Staphylococci (CoNS) such as #Staphylococcus cohnii activate the host steroid pathway and promote immunosuppression.
• [1.12] [#Staphylococcus epidermidis] 
  - tarIJLM (#Staphylococcus aureus-type wall teichoic acid) alters the lifestyle of S. epidermidis from commensal to pathogenic
• [1.13] 
  - viable skin-associated bacteria are predominantly located in hair follicles and other cutaneous invaginations. - the skin microbiome has a uniquely low fraction of viable bacteria compared to other human microbiome sites, indicating that most bacterial DNA on the skin surface is not associated with viable cells. - the skin microbiome is remarkably stable even in the wake of aggressive perturbation, repopulation of the skin surface is driven by the underlying viable population.
• [1.14] 
  - #Firmicutes, #Proteobacteria, and #Actinobacteria as the primary active microbial phyla in Chamliyal #Clay. - These resemble those abundant in a healthy human skin microbiome. - This is significant as lower levels of these phyla in the skin are linked to inflammatory skin conditions like #Psoriasis.
• - pathogenic microbes actively metabolizing in the #Clay were absent. Importantly, 6% of the transcripts annotated to #Sulfur and iron metabolism, which are known to play a major role in skin disease management.
• [1.15] [#Actinobacteria] 
  - Belly button (BB) and between toes (BT) (moist microenvironment) were mainly comprised of Actinobacteriota and #Firmicutes; behind ears (BE) (oily microenvironment) was dominated by #Firmicutes; and calves (CA) and forearms (FA) (dry microenvironment) included a combination of those three phyla. - BB and BT (moist microenvironment) were dominated by #Staphylococcus and #Corynebacterium, BE (oily microenvironment) by #Staphylococcus and #Anaerococcus, while CA and FA (dry microenvironment) showed a high proportion of #Staphylococcus and #Corynebacterium, but also of #Streptococcus and #Escherichia-#Shigella. #Anaerococcus was also highly abundant in BB.

References Notes