Bile Acids ⇒ Primary bile acids {90000329}

Shared Reference Notes

• [1.1] [#Bile Acids, #Secondary bile acids] 
  - Both primary BAs and secondary BAs have been shown to interact agonistically or antagonistically with a family of nuclear (FXR) and G-protein-coupled receptors, collectively known as BA-activated receptors (BAR), influencing cellular signaling as well as immunological response
• [1.2] [#Ulcerative Colitis] [#Secondary bile acids] 
  - colonic CD displayed a disease-severity-related association with #Bacteroides vulgatus. - Compared to colonic CD, ileal CD profiles displayed increased primary and secondary bile acid levels and concomitant shifts in taxa with noted sensitivities such as #Faecalibacterium prausnitzii or affinities for bile acid-rich environments, including #Gammaproteobacteria and #Blautia sp.
• [1.3] [#Bile Acids, #Secondary bile acids] 
  - Intestinal bacteria will deconjugate primary BAs that fail reabsorption in the terminal ileum and thereby convert them to secondary BAs by microbial biotransformation, including dehydroxylation, epimerization, and oxidation of hydroxyl groups. - Free BAs, such as cholic acid, deoxycholic acid, and chenodeoxycholic acid, can stimulate apoptosis and reduce interleukin 6 (IL-6) production, while conjugated BAs such as glycolic acid, glycodeoxycholic acid, and glycochenodeoxycholic acid promote cell growth and induce IL-6 production.
• [#Inflamatory bowel disease] [#Bile Acids, #Secondary bile acids] - Reduced BA deconjugation is associated with inflammatory bowel diseases (IBD) including #Ulcerative Colitis (UC) and #Crohn’s disease (CD), as well as #Irritable bowel syndrome (IBS).
• [1.4] [#Secondary bile acids] 
  - Primary #Bile Acids are conjugated in several different forms and secreted into the intestine. - a small portion (~5%) of the Primary #Bile Acids (about 200 to 800 mg daily in humans) escapes the reabsorption in Ileum and reaches the colon where gut bacteria convert them into secondary #Bile Acids (SBAs), such as #Deoxycholic acid (DCA), #Ursodeoxycholic acid (UDCA), and #Lithocholic acid (LCA). - majority (90% to 95%) of SBAs are reabsorbed into colonocytes to return to the liver for detoxification and recycling.
• [1.5] [#Inflamatory bowel disease] 
  - Bile acid and ceramide metabolites were more abundant in stool from patients with IBD, concomitant with a loss of bacteria genomically predicted to metabolize primary bile acids. - Bile-resistant pathobionts were increased in dysbiotic stool from IBD patients
• [1.6] [#Clostridium difficile associated disease] [#Tauro-cholic acid] 
  - #Bile Salt hydrolases (BSHs) comprise a diverse family of microbial enzymes that catalyse critical BA transformation. - Primary conjugated BAs synthesized in the liver, such as the tauro- and glycoconjugates of #Cholic acid (TCA, GCA), are deconjugated by BSHs to generate #Cholic acid (CA)
• [1.7] [#Short Chain Fatty Acid] [#Exercise training] 
  - SCFAs, in response to aerobic exercise, can decrease the luminal pH (colon) by decreasing the conversion of primary bile acids to #Secondary bile acids and promoting colonic acidification. - The environment created as a result of these changes is more favorable for the growth of healthy commensal bacteria

References Notes