Novel bile acid biosynthetic pathways are enriched in the microbiome of centenarians.

Centenarians have a decreased susceptibility to ageing-associated illnesses, chronic inflammation and infectious diseases1-3. Here we show that centenarians have a distinct gut microbiome that is enriched in microorganisms that are capable of generating unique secondary bile acids, including various isoforms of lithocholic acid (LCA): iso-, 3-oxo-, allo-, 3-oxoallo- and isoallolithocholic acid. Among these bile acids, the biosynthetic pathway for isoalloLCA had not been described previously. By screening 68 bacterial isolates from the faecal microbiota of a centenarian, we identified Odoribacteraceae strains as effective producers of isoalloLCA both in vitro and in vivo. Furthermore, we found that the enzymes 5α-reductase (5AR) and 3ß-hydroxysteroid dehydrogenase (3ß-HSDH) were responsible for the production of isoalloLCA. IsoalloLCA exerted potent antimicrobial effects against Gram-positive (but not Gram-negative) multidrug-resistant pathogens, including Clostridioides difficile and Enterococcus faecium. These findings suggest that the metabolism of specific bile acids may be involved in reducing the risk of infection with pathobionts, thereby potentially contributing to the maintenance of intestinal homeostasis.

Insulin dysregulation drives mitochondrial cholesterol metabolite accumulation: initiating hepatic toxicity in nonalcoholic fatty liver disease.

CYP7B1 catalyzes mitochondria-derived cholesterol metabolites such as (25R)26-hydroxycholesterol (26HC) and 3ß-hydroxy-5-cholesten-(25R)26-oic acid (3ßHCA) and facilitates their conversion to bile acids. Disruption of 26HC/3ßHCA metabolism in the absence of CYP7B1 leads to neonatal liver failure. Disrupted 26HC/3ßHCA metabolism with reduced hepatic CYP7B1 expression is also found in nonalcoholic steatohepatitis (NASH). The current study aimed to understand the regulatory mechanism of mitochondrial cholesterol metabolites and their contribution to onset of NASH. We used Cyp7b1-/- mice fed a normal diet (ND), Western diet (WD), or high-cholesterol diet (HCD). Serum and liver cholesterol metabolites as well as hepatic gene expressions were comprehensively analyzed. Interestingly, 26HC/3ßHCA levels were maintained at basal levels in ND-fed Cyp7b1-/- mice livers by the reduced cholesterol transport to mitochondria, and the upregulated glucuronidation and sulfation. However, WD-fed Cyp7b1-/- mice developed insulin resistance (IR) with subsequent 26HC/3ßHCA accumulation due to overwhelmed glucuronidation/sulfation with facilitated mitochondrial cholesterol transport. Meanwhile, Cyp7b1-/- mice fed an HCD did not develop IR or subsequent evidence of liver toxicity. HCD-fed mice livers revealed marked cholesterol accumulation but no 26HC/3ßHCA accumulation. The results suggest 26HC/3ßHCA-induced cytotoxicity occurs when increased cholesterol transport into mitochondria is coupled to decreased 26HC/3ßHCA metabolism driven with IR. Supportive evidence for cholesterol metabolite-driven hepatotoxicity is provided in a diet-induced nonalcoholic fatty liver mouse model and by human specimen analyses. This study uncovers an insulin-mediated regulatory pathway that drives the formation and accumulation of toxic cholesterol metabolites within the hepatocyte mitochondria, mechanistically connecting IR to cholesterol metabolite-induced hepatocyte toxicity which drives nonalcoholic fatty liver disease.

Dried blood spot-based newborn screening for bile acid synthesis disorders, Zellweger spectrum disorder, and Niemann-Pick type C1 by detection of bile acid metabolites.

OBJECTIVE: To examine whether it is possible to screen for bile acid synthesis disorders (BASDs) including peroxisome biogenesis disorder 1a (PBD1A) and Niemann-Pick type C1 (NPC1) at the time of newborn mass screening by measuring the intermediary metabolites of bile acid (BA) synthesis. METHODS: Patients with 3ß-hydroxy-ΔSuchy et al. (2021)5-C27-steroid dehydrogenase/isomerase (HSD3B7) deficiency (n = 2), 3-oxo-ΔPandak and Kakiyama (n.d.)4-steroid 5ß-reductase (SRD5B1) deficiency (n = 1), oxysterol 7α-hydroxylase (CYP7B1) deficiency (n = 1), PBD1A (n = 1), and NPC1 (n = 2) with available dried blood spot (DBS) samples collected in the neonatal period were included. DBSs from healthy neonates at 4 days of age (n = 1055) were also collected for the control. Disease specific BAs were measured by newly optimized liquid chromatography-tandem mass spectrometry with short run cycle (5-min/run). The results were validated by comparing with those obtained by the conventional condition with longer run cycle (76-min/run). RESULTS: In healthy specimens, taurocholic acid and cholic acid were the two major BAs which constituted approximately 80% in the measured BAs. The disease marker BAs presented <10%. In BASDs, the following BAs were determined for the disease specific markers: Glyco/tauro 3ß,7α,12α-trihydroxy-5-cholenoic acid 3-sulfate for HSD3B7 deficiency (>70%); glyco/tauro 7α,12α-dihydroxy-3-oxo-4-cholenoic acid for SRD5B1 deficiency (54%); tauro 3ß-hydroxy-5-cholenoic acid 3-sulfate for CYP7B1 deficiency (94%); 3α,7α,12α-trihydroxy-5ß-cholestanoic acid for PBD1A (78%); and tauro 3ß,7ß-dihydroxy-5-cholenoic acid 3-sulfate for NPC1 (26%). *The % in the parenthesis indicates the portion found in the patient's specimen. CONCLUSIONS: Early postnatal screening for BASDs, PBD1A and NPC1 is feasible with the described DBS-based method by measuring disease specific BAs. The present method is a quick and affordable test for screening for these inherited diseases.

Inborn errors of bile acid metabolism in Japan.

Bile acids are a category of steroids biosynthesized from cholesterol in the liver. Inborn errors of their metabolism are inherited in an autosomal recessive manner, resulting in enzyme deficiencies affecting the bile acid biosynthetic pathway. These defects in the pathway cause accumulation of unusual bile acids or bile alcohols. Unusual bile acids are highly cytotoxic, causing injury to the liver. These unusual bile acids damage hepatocytes, resulting in cholestatic liver injury beginning in infancy. Except for cerebrotendinous xanthomatosis and some secondary defects, various inborn errors of bile acid metabolism (IEBAM) have been reported from Japan, affecting eight patients including three with 3ß-hydroxy-Δ5 -C27 -steroid dehydrogenase/isomerase deficiency, three with Δ4 -3-oxosteroid 5ß-reductase deficiency, one with oxysterol 7α-hydroxylase deficiency, and one with bile acid-CoA: amino acid N-acyltransferase deficiency. Distinctive laboratory findings in patients with 3ß-hydroxy-Δ5 -C27 -steroid dehydrogenase/isomerase deficiency, Δ4 -3-oxosteroid 5ß-reductase deficiency, and oxysterol 7α-hydroxylase deficiency include normal serum γ-glutamyltransferase and total bile acids concentrations despite presence of cholestasis (elevated serum direct bilirubin) from infancy. Pediatricians and pediatric surgeons who suspect a case of IEBAM should obtain urinary and serum bile acid analyses using gas or liquid chromatography-mass spectrometry as well as genetic analyses. Available treatments include oral cholic acid, chenodeoxycholic acid, glycocholic acid, and ursodeoxycholic acid; fat-soluble vitamin supplementation; and liver transplantation. Early diagnosis and treatment can offer a good outcome.

Characterization of long-chain fatty acid-linked bile acids: a major conjugation form of 3ß-hydroxy bile acids in feces.

Although most bile acids (BAs) in feces are present in noncovalent forms that can be extracted with ethanol, non-negligible amounts of saponifiable BAs are also present. It is a major concern that such saponifiable BAs are routinely omitted from fecal BA measurements. We compared the BA profiles of healthy stools that were obtained with/without alkaline hydrolysis and found that as much as 29.7% (2.1-67.7%) of total BAs were saponifiable. Specifically, alkaline treatment led to significant elevations of isodeoxycholic acid (isoDCA) and isolithocholic acid (isoLCA) concentrations, suggesting that considerable proportions of isoDCA and isoLCA were esterified. Precursor ion scan data from LC/MS suggested the presence of long-chain FA-linked BAs. We chemically synthesized a series of fatty acid 3ß-acyl conjugates of isoDCA and isoLCA as analytical standards and analyzed their fecal profiles from newborns to adults (n = 64) by LC/MS. FA-conjugated isobile acids (FA-isoBAs) were constantly present from 2 years of age to adulthood. C16- and C18-chain FA-isoBA esters were predominantly found regardless of age, but small amounts of acetic acid esters were also found. FA-isoBA concentrations were not correlated to fecal FA concentrations. Interestingly, there were some adults who did not have FA-isoBAs. Gut bacteria involved in the production of FA-isoBAs have not been identified yet. The present study provides insight into the establishment of early gut microbiota and the interactive development of esterified BAs.The contribution of FA-isoBAs to gut physiology and their role in pathophysiologic conditions such as inflammatory bowel disease are currently under investigation.

Coffee modulates insulin-hepatocyte nuclear factor-4α-Cyp7b1 pathway and reduces oxysterol-driven liver toxicity in a nonalcoholic fatty liver disease mouse model.

Oxysterol 7α-hydroxylase (CYP7B1) controls the levels of intracellular regulatory oxysterols generated by the "acidic pathway" of cholesterol metabolism. Previously, we demonstrated that an inability to upregulate CYP7B1 in the setting of insulin resistance leads to the accumulation of cholesterol metabolites such as (25R)26-hydroxycholesterol (26HC) that initiate and promote hepatocyte injury; followed by an inflammatory response. The current study demonstrates that dietary coffee improves insulin resistance and restores Cyp7b1 levels in a well-characterized Western diet (WD)-induced nonalcoholic fatty liver disease (NAFLD) mouse model. Ingestion of a WD containing caffeinated (regular) coffee or decaffeinated coffee markedly reduced the serum ALT level and improved insulin resistance. Cyp7b1 mRNA and protein levels were preserved at normal levels in mice fed the coffee containing WD. Additionally, coffee led to upregulated steroid sulfotransferase 2b1 (Sult2b1) mRNA expression. In accordance with the response in these oxysterol metabolic genes, hepatocellular 26HC levels were maintained at physiologically low levels. Moreover, the current study provided evidence that hepatic Cyp7b1 and Sult2b1 responses to insulin signaling can be mediated through a transcriptional factor, hepatocyte nuclear factor (HNF)-4α. We conclude coffee achieves its beneficial effects through the modulation of insulin resistance. Both decaffeinated and caffeinated coffee had beneficial effects, demonstrating caffeine is not fundamental to this effect. The effects of coffee feeding on the insulin-HNF4α-Cyp7b1 signaling pathway, whose dysregulation initiates and contributes to the onset and progression of NASH as triggered by insulin resistance, offer mechanistic insight into approaches for the treatment of NAFLD.NEW & NOTEWORTHY This study demonstrated dietary coffee prevented the accumulation of hepatic oxysterols by maintaining Cyp7b1/Sult2b1 expression in a diet-induced NAFLD mice model. Lowering liver oxysterols markedly reduced inflammation in the coffee-ingested mice. Caffeine is not fundamental to this effect. In addition, this study showed Cyp7b1/Sult2b1 responses to insulin signaling can be mediated through a transcriptional factor, HNF4α. The insulin-HNF4α-Cyp7b1/Sult2b1 signaling pathway, which directly correlates to the onset of NASH triggered by insulin resistance, offers insight into approaches for NAFLD treatment.

Berberine alters gut microbial function through modulation of bile acids.

BACKGROUND: Berberine (BBR) is a plant-based nutraceutical that has been used for millennia to treat diarrheal infections and in contemporary medicine to improve patient lipid profiles. Reduction in lipids, particularly cholesterol, is achieved partly through up-regulation of bile acid synthesis and excretion into the gastrointestinal tract (GI). The efficacy of BBR is also thought to be dependent on structural and functional alterations of the gut microbiome. However, knowledge of the effects of BBR on gut microbiome communities is currently lacking. Distinguishing indirect effects of BBR on bacteria through altered bile acid profiles is particularly important in understanding how dietary nutraceuticals alter the microbiome. RESULTS: Germfree mice were colonized with a defined minimal gut bacterial consortium capable of functional bile acid metabolism (Bacteroides vulgatus, Bacteroides uniformis, Parabacteroides distasonis, Bilophila wadsworthia, Clostridium hylemonae, Clostridium hiranonis, Blautia producta; B4PC2). Multi-omics (bile acid metabolomics, 16S rDNA sequencing, cecal metatranscriptomics) were performed in order to provide a simple in vivo model from which to identify network-based correlations between bile acids and bacterial transcripts in the presence and absence of dietary BBR. Significant alterations in network topology and connectivity in function were observed, despite similarity in gut microbial alpha diversity (P = 0.30) and beta-diversity (P = 0.123) between control and BBR treatment. BBR increased cecal bile acid concentrations, (P < 0.05), most notably deoxycholic acid (DCA) (P < 0.001). Overall, analysis of transcriptomes and correlation networks indicates both bacterial species-specific responses to BBR, as well as functional commonalities among species, such as up-regulation of Na+/H+ antiporter, cell wall synthesis/repair, carbohydrate metabolism and amino acid metabolism. Bile acid concentrations in the GI tract increased significantly during BBR treatment and developed extensive correlation networks with expressed genes in the B4PC2 community. CONCLUSIONS: This work has important implications for interpreting the effects of BBR on structure and function of the complex gut microbiome, which may lead to targeted pharmaceutical interventions aimed to achieve the positive physiological effects previously observed with BBR supplementation.

Bile Acid Synthesis Disorders in Japan: Long-Term Outcome and Chenodeoxycholic Acid Treatment.

BACKGROUND: We encountered 7 Japanese patients with bile acid synthesis disorders (BASD) including 3ß-hydroxy-Δ5-C27-steroid dehydrogenase/isomerase (3ß-HSD) deficiency (n = 3), Δ4-3-oxosteroid 5ß-reductase (5ß-reductase) deficiency (n = 3), and oxysterol 7α-hydroxylase deficiency (n = 1) over 21 years between 1996 and 2017. AIM: We aimed to clarify long-term outcome in the 7 patients with BASD as well as long-term efficacy of chenodeoxycholic acid (CDCA) treatment in the 5 patients with 3ß-HSD deficiency or 5ß-reductase deficiency. METHODS: Diagnoses were made from bile acid and genetic analyses. Bile acid analysis in serum and urine was performed using gas chromatography-mass spectrometry. Clinical and laboratory findings and bile acid profiles at diagnosis and most recent visit were retrospectively obtained from medical records. Long-term outcome included follow-up duration, treatments, growth, education/employment, complications of treatment, and other problems. RESULTS: Medians with ranges of current patient ages and duration of CDCA treatment are 10 years (8 to 43) and 10 years (8 to 21), respectively. All 7 patients, who had homozygous or compound heterozygous mutations in the HSD3B7, SRD5B1, or CYP7B1 gene, are currently in good health without liver dysfunction. In the 5 patients with CDCA treatment, hepatic function gradually improved following initiation. No adverse effects were noted. CONCLUSIONS: We concluded that CDCA treatment is effective in 3ß-HSD deficiency and 5ß-reductase deficiency, as cholic acid has been in other countries. BASD carry a good prognosis following early diagnosis and initiation of long-term CDCA treatment.

Insulin resistance dysregulates CYP7B1 leading to oxysterol accumulation: a pathway for NAFL to NASH transition.

NAFLD is an important public health issue closely associated with the pervasive epidemics of diabetes and obesity. Yet, despite NAFLD being among the most common of chronic liver diseases, the biological factors responsible for its transition from benign nonalcoholic fatty liver (NAFL) to NASH remain unclear. This lack of knowledge leads to a decreased ability to find relevant animal models, predict disease progression, or develop clinical treatments. In the current study, we used multiple mouse models of NAFLD, human correlation data, and selective gene overexpression of steroidogenic acute regulatory protein (StarD1) in mice to elucidate a plausible mechanistic pathway for promoting the transition from NAFL to NASH. We show that oxysterol 7α-hydroxylase (CYP7B1) controls the levels of intracellular regulatory oxysterols generated by the "acidic/alternative" pathway of cholesterol metabolism. Specifically, we report data showing that an inability to upregulate CYP7B1, in the setting of insulin resistance, results in the accumulation of toxic intracellular cholesterol metabolites that promote inflammation and hepatocyte injury. This metabolic pathway, initiated and exacerbated by insulin resistance, offers insight into approaches for the treatment of NAFLD.

Antibiotic-Associated Disruption of Microbiota Composition and Function in Cirrhosis Is Restored by Fecal Transplant.

Patients with cirrhosis are often exposed to antibiotics that can lead to resistance and fungal overgrowth. The role of fecal microbial transplant (FMT) in restoring gut microbial function is unclear in cirrhosis. In a Food and Drug Administration-monitored phase 1 clinical safety trial, patients with decompensated cirrhosis on standard therapies (lactulose and rifaximin) were randomized to standard-of-care (SOC, no antibiotics/FMT) or 5 days of broad-spectrum antibiotics followed by FMT from a donor enriched in Lachnospiraceae and Ruminococcaceae. Microbial composition (diversity, family-level relative abundances), function (fecal bile acid [BA] deconjugation, 7α-dehydroxylation, short-chain fatty acids [SCFAs]), and correlations between Lachnospiraceae, Ruminococcaceae, and clinical variables were analyzed at baseline, postantibiotics, and 15 days post-FMT. FMT was well tolerated. Postantibiotics, there was a reduced microbial diversity and autochthonous taxa relative abundance. This was associated with an altered fecal SCFA and BA profile. Correlation linkage changes from beneficial at baseline to negative after antibiotics. All of these parameters became statistically similar post-FMT to baseline levels. No changes were seen in the SOC group. CONCLUSION: In patients with advanced cirrhosis on lactulose and rifaximin, FMT restored antibiotic-associated disruption in microbial diversity and function. (Hepatology 2018; 00:000-000).

Use of dried urine spots for screening of inborn errors of bile acid synthesis.

BACKGROUND: In pediatric patients with cholestasis of unknown cause, inborn errors of bile acid (BA) synthesis (IEBAS) may be considered. For the initial screening for IEBAS, clarification of the urine BA profile is essential. The transportation of urine in a frozen state via air delivery, however, is laborious and costly. This study assessed the feasibility of using dried urine spots (DUS) to establish a more convenient and affordable method of IEBAS screening. METHODS: We created DUS using urine samples from patients with 3ß-hydroxy-Δ5-C27-steroid dehydrogenase/isomerase deficiency (3ß-HSD) and Δ4-3-oxo-steroid 5ß-reductase deficiency as standard preparations. We started accepting DUS specimens by regular mail. RESULTS: The ratio of unusual to usual BA is essential for the initial detection of IEBAS, and the recovery rates of abnormal BA were acceptable. The recovery rate of Δ4-BA on day 28 decreased to 31.8% at 25°C, and to 19.6% at 37°C. Therefore, the sending of DUS should be avoided under conditions of high temperature. Of a total of 49 children with cholestasis, eight new patients were diagnosed with IEBAS using this screening method. CONCLUSION: The mailing screening system is expected to facilitate the shipment, from regions outside of Japan, of samples for IEBAS screening.

Alterations in gut microbial function following liver transplant.

Liver transplantation (LT) improves daily function and ameliorates gut microbial composition. However, the effect of LT on microbial functionality, which can be related to overall patient benefit, is unclear and could affect the post-LT course. The aims were to determine the effect of LT on gut microbial functionality focusing on endotoxemia, bile acid (BA), ammonia metabolism, and lipidomics. We enrolled outpatient patients with cirrhosis on the LT list and followed them until 6 months after LT. Microbiota composition (Shannon diversity and individual taxa) and function analysis (serum endotoxin, urinary metabolomics and serum lipidomics, and stool BA profile) and cognitive tests were performed at both visits. We enrolled 40 patients (age, 56 ± 7 years; mean Model for End-Stage Liver Disease score, 22.6). They received LT 6 ± 3 months after enrollment and were re-evaluated 7 ± 3 months after LT with a stable course. A significant improvement in cognition with increase in microbial diversity, increase in autochthonous and decrease in potentially pathogenic taxa, and reduced endotoxemia were seen after LT compared with baseline. Stool BAs increased significantly after LT, and there was evidence of greater bacterial action (higher secondary, oxo and iso-BAs) after LT although the levels of conjugated BAs remained similar. There was a reduced serum ammonia and corresponding rise in urinary phenylacetylglutamine after LT. There was an increase in urinary trimethylamine-N-oxide, which was correlated with specific changes in serum lipids related to cell membrane products. The ultimate post-LT lipidomic profile appeared beneficial compared with the profile before LT. In conclusion, LT improves gut microbiota diversity and dysbiosis, which is accompanied by favorable changes in gut microbial functionality corresponding to BAs, ammonia, endotoxemia, lipidomic, and metabolomic profiles. Liver Transplantation 24 752-761 2018 AASLD.

Continued Alcohol Misuse in Human Cirrhosis is Associated with an Impaired Gut-Liver Axis.

BACKGROUND: Cirrhosis and alcohol can independently affect the gut-liver axis with systemic inflammation. However, their concurrent impact in humans is unclear. METHODS: Our aim was to determine the effect of continued alcohol misuse on the gut-liver axis in cirrhotic patients. Age- and MELD-balanced cirrhotic patients who were currently drinking (Alc) or abstinent (NAlc) and healthy controls underwent serum and stool collection. A subset underwent upper endoscopy and colonoscopy for biopsies and duodenal fluid collection. The groups were compared regarding (i) inflammation/intestinal barrier: systemic tumor necrosis factor levels, intestinal inflammatory cytokine (duodenum, ileum, sigmoid), and ileal antimicrobial peptide expression; (ii) microbiota composition: 16SrRNA sequencing of duodenal, ileal, and colonic mucosal and fecal microbiota; and (iii) microbial functionality: duodenal fluid and fecal bile acid (BA) profile (conjugation and dehydroxylation status), intestinal BA transporter (ASBT, FXR, FGF-19, SHP) expression, and stool metabolomics using gas chromatography/mass spectrometry. RESULTS: Alc patients demonstrated a significant duodenal, ileal, and colonic mucosal and fecal dysbiosis, compared to NAlc and controls with lower autochthonous bacterial taxa. BA profile skewed toward a potentially toxic profile (higher secondary and glycine-conjugated BAs) in duodenal fluid and stool in Alc patients. Duodenal fluid demonstrated conjugated secondary BAs only in the Alc group. There was a greater expression of all ileal BA transporters in Alc patients. This group also showed higher endotoxemia, systemic and ileal inflammatory expression, and lower amino acid and bioenergetic-associated metabolites, without change in antimicrobial peptide expression. CONCLUSIONS: Despite cirrhosis, continued alcohol misuse predisposes patients to widespread dysbiosis with alterations in microbial functionality such as a toxic BA profile, which can lead to intestinal and systemic inflammation.

Distinguishing primary from secondary Δ(4) -3-oxosteroid 5ß-reductase (SRD5B1, AKR1D1) deficiency by urinary steroid analysis.

OBJECTIVE: Deficiency of Δ(4) -3-oxosteroid 5ß-reductase (5ß-reductase), a bile acid synthesis disorder, presents findings of neonatal cholestasis and hyper-3-oxo-Δ(4) bile aciduria. The 5ß-reductase enzyme participates in not only bile acid synthesis but also hepatic steroid metabolism. Deficiency of 5ß-reductase includes 2 types: primary deficiency, with an SRD5B1 gene mutation; and secondary deficiency, lacking a mutation. Secondary deficiency is caused by fulminant liver failure from various aetiologies including neonatal hemochromatosis (NH). Distinguishing primary from secondary deficiency based on γ-glutamyltransferase (GGT), serum total bile acids (TBA), and urinary bile acid analysis using gas chromatography-mass spectroscopy (GC-MS) is very difficult. SRD5B1 gene analysis is the only reliable method. We examined urinary steroid analysis as a way to distinguish primary from secondary 5ß-reductase deficiency. DESIGN, PATIENTS AND MEASUREMENTS: We examined 12 patients with cholestatic jaundice, normal or slightly elevated GGT, and hyper-3-oxo-Δ(4) bile aciduria using urinary steroid analysis by GC-MS of both cortisol and cortisone compounds, such as 5ß-tetrahydrocortisol (5ß-THF) and 5ß-tetrahydrocortisone (5ß-THE). Patients previously were diagnosed with primary 5ß-reductase deficiency (n = 3), deficiency secondary to NH (n = 3) and deficiency secondary to other liver disorders (n = 6). RESULTS: Urinary steroid analysis in 3 primary deficiency and 3 NH patients showed low 5ß-THE and elevated 5α/5ß-THE ratios, making distinction difficult without also considering the clinical course and abdominal magnetic resonance imaging (MRI) findings, such as a very low signal intensity in liver and/or pancreas, especially in T2 -weighted images. In the six patients with other secondary deficiencies, urinary 5ß-THF and 5α/5ß-THF differed from those in primary deficiency (P < 0·05). CONCLUSIONS: Urinary steroid analysis can distinguish primary and NH-related deficiencies from other secondary deficiencies.

A simple and accurate HPLC method for fecal bile acid profile in healthy and cirrhotic subjects: validation by GC-MS and LC-MS.

We have developed a simple and accurate HPLC method for measurement of fecal bile acids using phenacyl derivatives of unconjugated bile acids, and applied it to the measurement of fecal bile acids in cirrhotic patients. The HPLC method has the following steps: 1) lyophilization of the stool sample; 2) reconstitution in buffer and enzymatic deconjugation using cholylglycine hydrolase/sulfatase; 3) incubation with 0.1 N NaOH in 50% isopropanol at 60°C to hydrolyze esterified bile acids; 4) extraction of bile acids from particulate material using 0.1 N NaOH; 5) isolation of deconjugated bile acids by solid phase extraction; 6) formation of phenacyl esters by derivatization using phenacyl bromide; and 7) HPLC separation measuring eluted peaks at 254 nm. The method was validated by showing that results obtained by HPLC agreed with those obtained by LC-MS/MS and GC-MS. We then applied the method to measuring total fecal bile acid (concentration) and bile acid profile in samples from 38 patients with cirrhosis (17 early, 21 advanced) and 10 healthy subjects. Bile acid concentrations were significantly lower in patients with advanced cirrhosis, suggesting impaired bile acid synthesis.

Colonic inflammation and secondary bile acids in alcoholic cirrhosis.

Alcohol abuse with/without cirrhosis is associated with an impaired gut barrier and inflammation. Gut microbiota can transform primary bile acids (BA) to secondary BAs, which can adversely impact the gut barrier. The purpose of this study was to define the effect of active alcohol intake on fecal BA levels and ileal and colonic inflammation in cirrhosis. Five age-matched groups {two noncirrhotic (control and drinkers) and three cirrhotic [nondrinkers/nonalcoholics (NAlc), abstinent alcoholic for >3 mo (AbsAlc), currently drinking (CurrAlc)]} were included. Fecal and serum BA analysis, serum endotoxin, and stool microbiota using pyrosequencing were performed. A subgroup of controls, NAlc, and CurrAlc underwent ileal and sigmoid colonic biopsies on which mRNA expression of TNF-α, IL-1ß, IL-6, and cyclooxygenase-2 (Cox-2) were performed. One hundred three patients (19 healthy, 6 noncirrhotic drinkers, 10 CurrAlc, 38 AbsAlc, and 30 NAlc, age 56 yr, median MELD: 10.5) were included. Five each of healthy, CurrAlc, and NAlc underwent ileal/colonic biopsies. Endotoxin, serum-conjugated DCA and stool total BAs, and secondary-to-primary BA ratios were highest in current drinkers. On biopsies, a significantly higher mRNA expression of TNF-α, IL-1ß, IL-6, and Cox-2 in colon but not ileum was seen in CurrAlc compared with NAlc and controls. Active alcohol use in cirrhosis is associated with a significant increase in the secondary BA formation compared with abstinent alcoholic cirrhotics and nonalcoholic cirrhotics. This increase in secondary BAs is associated with a significant increase in expression of inflammatory cytokines in colonic mucosa but not ileal mucosa, which may contribute to alcohol-induced gut barrier injury.

Rapid in vivo evaluation system for cholestasis-related genes in mice with humanized bile acid profiles.

BACKGROUND: Pediatric cholestatic liver diseases (Ped-CLD) comprise many ultrarare disorders with a genetic basis. Pharmacologic therapy for severe cases of Ped-CLD has not been established. Species differences in bile acid (BA) metabolism between humans and rodents contribute to the lack of phenocopy of patients with Ped-CLD in rodents and hinder the development of therapeutic strategies. We aimed to establish an efficient in vivo system to understand BA-related pathogenesis, such as Ped-CLD. METHODS: We generated mice that express spCas9 specifically in the liver (L-Cas9Tg/Tg [liver-specific Cas9Tg/Tg] mice) and designed recombinant adeno-associated virus serotype 8 encoding small-guide RNA (AAV8 sgRNA) targeting Abcc2, Abcb11, and Cyp2c70. In humans, ABCC2 and ABCB11 deficiencies cause constitutional hyperbilirubinemia and most severe Ped-CLD, respectively. Cyp2c70 encodes an enzyme responsible for the rodent-specific BA profile. Six-week-old L-Cas9Tg/Tg mice were injected with this AAV8 sgRNA and subjected to biochemical and histological analysis. RESULTS: Fourteen days after the injection with AAV8 sgRNA targeting Abcc2, L-Cas9Tg/Tg mice exhibited jaundice and phenocopied patients with ABCC2 deficiency. L-Cas9Tg/Tg mice injected with AAV8 sgRNA targeting Abcb11 showed hepatomegaly and cholestasis without histological evidence of liver injury. Compared to Abcb11 alone, simultaneous injection of AAV8 sgRNA for Abcb11 and Cyp2c70 humanized the BA profile and caused higher transaminase levels and parenchymal necrosis, resembling phenotypes with ABCB11 deficiency. CONCLUSIONS: This study provides proof of concept for efficient in vivo assessment of cholestasis-related genes in humanized bile acid profiles. Our platform offers a more time- and cost-effective alternative to conventional genetically engineered mice, increasing our understanding of BA-related pathogenesis such as Ped-CLD and expanding the potential for translational research.

Bile acid profiles in adult patients with biliary atresia who achieve native liver survival after portoenterostomy.

Bile acids have received increasing attention as a marker of the long-term prognosis and a potential therapeutic target in patients with biliary atresia, which is a progressive disease of the hepatobiliary system. A detailed analysis of serum and urinary bile acid compositions was conducted to assess the characteristics of bile acid profiles and the correlation between bile acid profiles and liver fibrosis markers in adult patients with biliary atresia who achieved bilirubin normalization. Serum total bile acids and glucuronide-conjugated (glyco- and tauro-) cholic acids (GCA and TCA) and chenodeoxycholic acids (GCDCA and TCDCA) were significantly higher in patients with biliary atresia than in healthy controls, whereas unconjugated CA and CDCA showed no significant difference. There were no significant differences in CA to CDCA ratios and glycine-to-taurine-conjugated ratios. Urinary glycocholic acid 3-sulfate (GCA-3S) was significantly higher in patients with biliary atresia. Serum GCDCA showed a strong positive correlation with Mac-2 binding protein glycosylation isomer (M2BPGi). These results demonstrate that bile acid congestion persists into adulthood in patients with biliary atresia, even after cholestasis has completely improved after Kasai portoenterostomy. These fundamental data on bile acid profiles also suggest the potential value of investigating bile acid profiles in patients with biliary atresia.

Navigating cholestasis: identifying inborn errors of bile acid metabolism for precision diagnosis.

Inborn errors of bile acid metabolism (IEBAM) cause cholestasis during the neonatal period, and 8 types of IEBAM have been reported to date. IEBAM accounts for approximately 2% of cases of cholestasis of unknown cause. As only 10 patients have been identified in Japan, IEBAM presents diagnostic challenges due to the similarity of clinical symptoms with biliary atresia, thus necessitating precise differentiation to avoid unnecessary invasive procedures. Laboratory tests in IEBAM are characterized by normal γ-glutamyltransferase (GGT) and serum total bile acid (STBA) levels despite the presence of cholestasis; therefore, measuring STBA and GGT is essential to distinguishing biliary atresia from IEBAM. With suspected IEBAM, liquid chromatography-mass spectrometry (LC/MS) analysis of urinary bile acids is needed to optimize diagnostic and therapeutic efficacy and avoid open cholangiography and initiate treatment for primary bile acids such as cholic acid or chenodeoxycholic acid. This prospective report aims to increase awareness of IEBAM by highlighting the characteristics of general blood test and bile acid profiles from LC/MS analyses of blood, urine, and stool samples.

Modulation of the fecal bile acid profile by gut microbiota in cirrhosis.

BACKGROUND & AIMS: The 7α-dehydroxylation of primary bile acids (BAs), chenodeoxycholic (CDCA) and cholic acid (CA) into the secondary BAs, lithocholic (LCA) and deoxycholic acid (DCA), is a key function of the gut microbiota. We aimed at studying the linkage between fecal BAs and gut microbiota in cirrhosis since this could help understand cirrhosis progression. METHODS: Fecal microbiota were analyzed by culture-independent multitagged-pyrosequencing, fecal BAs using HPLC and serum BAs using LC-MS in controls, early (Child A) and advanced cirrhotics (Child B/C). A subgroup of early cirrhotics underwent BA and microbiota analysis before/after eight weeks of rifaximin. RESULTS: Cross-sectional: 47 cirrhotics (24 advanced) and 14 controls were included. In feces, advanced cirrhotics had the lowest total, secondary, secondary/primary BA ratios, and the highest primary BAs compared to early cirrhotics and controls. Secondary fecal BAs were detectable in all controls but in a significantly lower proportion of cirrhotics (p<0.002). Serum primary BAs were higher in advanced cirrhotics compared to the rest. Cirrhotics, compared to controls, had a higher Enterobacteriaceae (potentially pathogenic) but lower Lachonospiraceae, Ruminococcaceae and Blautia (7α-dehydroxylating bacteria) abundance. CDCA was positively correlated with Enterobacteriaceae (r=0.57, p<0.008) while Ruminococcaceae were positively correlated with DCA (r=0.4, p<0.05). A positive correlation between Ruminococcaceae and DCA/CA (r=0.82, p<0.012) and Blautia with LCA/CDCA (r=0.61, p<0.03) was also seen. Prospective study: post-rifaximin, six early cirrhotics had reduction in Veillonellaceae and in secondary/primary BA ratios. CONCLUSIONS: Cirrhosis, especially advanced disease, is associated with a decreased conversion of primary to secondary fecal BAs, which is linked to abundance of key gut microbiome taxa.