Recurrent AKR1D1 c.580-13T>A Variant: A Cause of Δ4-3-Oxosteroid-5β-Reductase Deficiency

Phylogenetic and transcriptomic study of aldo-keto reductases in Haemonchus contortus and their inducibility by flubendazole

Aldo-keto reductases (AKRs), a superfamily of NADP(H)-dependent oxidoreductases, catalyze the oxidoreduction of a wide variety of eobiotic and xenobiotic aldehydes and ketones. In mammals, AKRs play essential roles in hormone and xenobiotic metabolism, oxidative stress, and drug resistance, but little is known about these enzymes in the parasitic nematode Haemonchus contortus. In the present study, 22 AKR genes existing in the H. contortus genome were investigated and a phylogenetic analysis with comparison to AKRs in Caenorhabditis elegans, sheep and humans was conducted. The constitutive transcription levels of all AKRs were measured in eggs, larvae, and adults of H. contortus, and their expression was compared in a drug-sensitive strain (ISE) and a benzimidazole-resistant strain (IRE) previously derived from the sensitive strain by imposing benzimidazole selection pressure. In addition, the inducibility of AKRs by exposure of H. contortus adults to benzimidazole anthelmintic flubendazole in vitro was tested. Phylogenetic analysis demonstrated that the majority of AKR genes in H. contortus lack orthologues in the sheep genome, which is a favorable finding for considering AKRs as potential drug targets. Large differences in the expression levels of individual AKRs were observed, with AKR1, AKR3, AKR8, and AKR10 being the most highly expressed at most developmental stages. Significant changes in the expression of AKRs during the life cycle and pronounced sex differences were found. Comparing the IRE and ISE strains, three AKRs were upregulated, and seven AKRs were downregulated in adults. In addition, the expression of three AKRs was induced by flubendazole exposure in adults of the ISE strain. Based on these results, AKR1, AKR2, AKR3, AKR5, AKR10 and AKR19 in particular merit further investigation and functional characterization with respect to their potential involvement in drug biotransformation and anthelmintic resistance in H. contortus.

∆4-3-oxo-5β-reductase deficiency: favorable outcome in 16 patients treated with cholic acid

BACKGROUND

Oral cholic acid therapy is an effective therapy in children with primary bile acid synthesis deficiencies. Most reported patients with this treatment have 3β-hydroxy-Δ5-C27-steroid oxidoreductase deficiency. The aim of the study was the evaluation of cholic acid therapy in a cohort of patients with the rarer Δ4-3-oxosteroid 5β-reductase (Δ4-3-oxo-R) deficiency.

METHODS

Sixteen patients with Δ4-3-oxo-R deficiency confirmed by AKR1D1 gene sequencing who received oral cholic acid were retrospectively analyzed.

RESULTS

First symptoms were reported early in life (median 2 months of age), with 14 and 3 patients having cholestatic jaundice and severe bleeding respectively. Fifteen patients received ursodeoxycholic acid before diagnosis, with partial improvement in 8 patients. Four patients had liver failure at the time of cholic acid initiation. All 16 patients received cholic acid from a median age of 8.1 months (range 3.1-159) and serum liver tests normalized in all within 6-12 months of treatment. After a median cholic acid therapy of 4.5 years (range 1.1-24), all patients were alive with their native liver. Median daily cholic acid dose at last follow-up was 8.3 mg/kg of body weight. All patients, but one, had normal physical examination and all had normal serum liver tests. Fibrosis, evaluated using liver biopsy (n = 4) or liver elastography (n = 9), had stabilized or improved. Cholic acid therapy enabled a 12-fold decrease of 3-oxo-∆4 derivatives in urine. Patients had normal growth and quality of life. The treatment was well tolerated without serious adverse events and signs of hepatotoxicity.

CONCLUSIONS

Oral cholic acid therapy is a safe and effective treatment for patients with Δ4-3-oxo-R deficiency.