NR1H4 and cystic fibrosis: Other factors could be attributed to the complex etiology of the impaired BA metabolism in the enterohepatic circuit in CF, such as: (A) an impaired microflora (due to increased acidity, antibiotic use, and swallowed contaminated saliva) promoting BA deconjugation, more toxic secondary BAs (LCA, DCA) [20], and increased BA elimination; (B) a thickened bowel wall decreasing BA resorption in the terminal ileum; (C) increased BA excretion (BA losses); and (D) impaired FXR-FGF19 signaling by a defective feedback control regulating BA synthesis and, consequently, promoting BA accumulation.