An efficient synthesis of 7α,12α-dihydroxy-4-cholesten-3-one and its biological precursor 7α-hydroxy-4-cholesten-3-one: Key intermediates in bile acid biosynthesis

Farnesoid X receptor antagonizes macrophage-dependent licensing of effector T lymphocytes and progression of sclerosing cholangitis

Immune-mediated bile duct epithelial injury and toxicity of retained hydrophobic bile acids drive disease progression in fibrosing cholangiopathies such as biliary atresia or primary sclerosing cholangitis. Emerging therapies include pharmacological agonists to farnesoid X receptor (FXR), the master regulator of hepatic synthesis, excretion, and intestinal reuptake of bile acids. Unraveling the mechanisms of action of pharmacological FXR agonists in the treatment of sclerosing cholangitis (SC), we found that intestinally restricted FXR activation effectively reduced bile acid pool size but did not improve the SC phenotype in MDR2-/- mice. In contrast, systemic FXR activation not only lowered bile acid synthesis but also suppressed proinflammatory cytokine production by liver-infiltrating inflammatory cells and blocked progression of hepatobiliary injury. The hepatoprotective activity was linked to suppressed production of IL1β and TNFα by hepatic macrophages and inhibition of TH1/TH17 lymphocyte polarization. Deletion of FXR in myeloid cells caused aberrant TH1 and TH17 lymphocyte responses in diethoxycarbonyl-1,4-dihydrocollidine-induced SC and rendered these mice resistant to the anti-inflammatory and liver protective effects of systemic FXR agonist treatment. Pharmacological FXR activation reduced IL1β and IFNγ production by liver- and blood-derived mononuclear cells from patients with fibrosing cholangiopathies. In conclusion, we demonstrate FXR to control the macrophage-TH1/17 axis, which is critically important for the progression of SC. Hepatic macrophages are cellular targets of systemic FXR agonist therapy for cholestatic liver disease.

Chemical synthesis of 7α-hydroxycholest-4-en-3-one, a biomarker for irritable bowel syndrome and bile acid malabsorption

7α-Hydroxy-cholest-4-en-3-one is a biomarker for bile acid loss, irritable bowel syndrome, and other diseases associated with defective bile acid biosynthesis. Furthermore, 7α-hydroxy-cholest-4-en-3-one is the physiological substrate for cytochrome P450 8B1 (P450 8B1 or CYP8B1), the oxysterol 12α-hydroxylase enzyme implicated in obesity and cardiovascular health. We report the chemical synthesis of this physiologically important oxysterol beginning with cholesterol. The key feature of this synthesis involves a regioselective C3-allylic oxidation of a 3-desoxy-Δ⁴-7α-formate steroid precursor to form 7α-formyloxy-cholest-4-en-3-one, which was saponified to yield 7α-hydroxy-cholest-4-en-3-one.

Serum Metabolomics Reveals That Gut Microbiome Perturbation Mediates Metabolic Disruption Induced by Arsenic Exposure in Mice

Arsenic contamination in drinking water has been a worldwide health concern for decades. In addition to being a well-recognized carcinogen, arsenic exposure has also been linked to diabetes, neurological effects, and cardiovascular diseases. Recently, increasing evidence has indicated that gut microbiome is an important risk factor in modulating the development of diseases. We aim to investigate the role of gut microbiome perturbation in arsenic-induced diseases by coupling a mass-spectrometry-based metabolomics approach and an animal model with altered gut microbiome induced by bacterial infection. Serum metabolic profiling has revealed that gut microbiome perturbation and arsenic exposure induced the dramatic changes of numerous metabolite pathways, including fatty acid metabolism, phospholipids, sphingolipids, cholesterols, and tryptophan metabolism, which were not or were less disrupted when the gut microbiome stayed normal. In summary, this study suggests that gut microbiome perturbation can exacerbate or cause metabolic disorders induced by arsenic exposure.

One-pot efficient synthesis of 13(R),14(R)-epoxy-17β-methyl-20(S)-hydroxyl-18-nor-pregna-4-en-3-one via a tandem epoxidation-rearrangement-epoxidation reaction sequence

One-pot synthesis of an 18-norsteroid compound, 13(R),14(R)-epoxy-17β-methyl-20(S)-hydroxyl-18-nor-pregna-4-en-3-one has been achieved with peracetic acid/acetic acid under a mild condition, via a proved tandem epoxidation-rearrangement-epoxidation sequence. Its structure was designated on the basis of NMR and X-ray crystallography data.