Sphingolipid ⇒ Ceramides {90000256}

Shared Reference Notes

• [1.1] [#Chronic fatigue syndrome] 
  - MC/CFS > increased levels of ceramides, one of the three types of sphingolipids
• [1.2] [#Sphingolipid] 
  - High ceramide levels > associated with insulin resistance, hypercholesterolemia, liver steatosis, and the formation of lipid rafts. - Some classes of ceramides in the blood increase the risk for late-onset #Alzheimer’s disease, as they are neurotoxic and induce apoptosis . - #Bacteroidetes phylum can synthesize sphingolipids > human epithelial cells > Ceramides
• [1.3] [#Dry Skin, #Natural Skin Microbiome] 
  - 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] [#Natural Skin Microbiome] 
  - 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.
• [1.5] [#Diabetes Type 2, #Irritable bowel syndrome] 
  - Increased levels of ceramides were reported in mucosal samples from IBS patients as well as in plasma and tissue samples in diabetes, cardiomyopathy, insulin resistance, #Atherosclerosis and #Steatohepatitis.
• [#Lipopolysaccharide, #Sphingomyelin] - Increased levels of lipopolysaccharides (LPS) associated with an altered gut microbiome may trigger the activation of sphingomyelinases (SMAse) and the hydrolysis of SM to produce ceramides.
• [#Chronic fatigue syndrome, #Irritable bowel syndrome] - patients with ME/CFS and IBS have increased plasma levels of ceramide.
• [#Chronic fatigue syndrome] [#Alistipes putredinis] - Decreased PC 30:0 correlated with decreased A. putredinis, , a bacterium known to produce #Sulfonolipids - unusual #Sphingolipids structurally related to ceramide. #Sphingolipids are known to maintain bacterial survival and promote stress resistance.
• [#Chronic fatigue syndrome] - Ceramides were associated with increased physical fatigue.
• [1.6] [#CVD, #Hearth attack] 
• [1.7] [#Para-cresol] [#Aging] 
  - Among metabolites that were positively associated with age, seven were common in all four groups (aconitic acid, #Choline, #Citrulline, #Cysteine, cystine, #kynurenine, and symmetric dimethylarginine (SDMA)) and 10 were common in three out of four groups (aspartic acid, asymmetric dimethylarginine (ADMA), butyrylcarnitine, ceramide d18:1/24:1, ceramide d18:1/25:0, ceramide d18:2/24:1, hippuric acid, homocysteine, methionine sulfoxide, and p-cresol #Sulfate)
• [1.8] [#Atopic Dermatitis] [#Staphylococcus aureus] 
  - The lesional skin of AD patients shows higher prevalence of S.aureus (up to 70%) than nonlesional skin of the same patients (39%) - The enzyme ceramidase secreted by S. aureus lowers lipid and fatty acid levels and makes the skin permeable to allergens. - Lower fatty acid levels also lead to decreased formation of phospholipid hydrolysis products in sebum and sweat, which increase skin surface pH and further promote S. aureus growth. - Alpha toxin secreted by S. aureus is cytotoxic to keratinocytes and alters the integrity of E-cadherin, compromising barrier function
• [1.9] [#Sphingolipid, #Sphingolipids] 
• - breakdown of TAG to provide fatty acids required for the synthesis of ceramide, a crucial lipid for function of the permeability barrier.
• - #Cutibacterium acnes induced a large increase in essential lipids including triglycerides, ceramides, #Cholesterol, and free fatty acids. - C. acnes can mediate this effect through its production of #Propionic acid and subsequent activation of keratinocyte PPARα. - This increase in lipids was mediated by short-chain fatty acids produced by #Cutibacterium acnes and was dependent on increased expression of several lipid synthesis genes including glycerol-3-phosphate-acyltransferase-3. - Inhibition or RNA silencing of peroxisome proliferator–activated receptor–α (PPARα), but not PPARβ and PPARγ, blocked this response.

References Notes