Acute hepatic porphyria and maternal health: Clinical and biochemical follow-up of 44 pregnancies.

BACKGROUND: Pregnancy in women with acute hepatic porphyria (AHP) has historically been associated with significant morbidity. Clinical outcomes have been the focus of previous reports on porphyria and maternal health, with little data available on the levels of heme precursors during pregnancy. We present the results of a follow-up program for women with AHP in the Swedish cohort who were pregnant between 2001 and 2020. METHODS: Thirty-three women with AHP were monitored during 44 pregnancies resulting in 44 single births. Seven of 33 women had a clinical history of acute attacks that required hospitalization. RESULTS: Four women experienced acute porphyria attacks during pregnancy and one during the puerperium. Seven women developed hypertension and four pregnancies ended with pre-eclampsia. There were no maternal or fetal pre- or postnatal deaths. One infant had a congenital cardiac anomaly. In 32 of the 38 pregnancies in which we measured heme precursors in the urine during pregnancy, the levels increased. CONCLUSION: Our observations align with contemporary reports that pregnancy in patients with AHP is frequently uncomplicated. Excretion of heme precursors increased during pregnancy, but this did not manifest as a higher frequency of clinical porphyria manifestations. The involvement of porphyria specialists in the patients' maternal care is recommended for reducing risk and improving the probability of good pregnancy outcomes.

RNAi therapy with givosiran significantly reduces attack rates in acute intermittent porphyria.

Acute hepatic porphyria (AHP) is a group of inherited metabolic disorders that affect hepatic heme biosynthesis. They are associated with attacks of neurovisceral manifestations that can be life threatening and constitute what is considered an acute porphyria attack. Until recently, the sole specific treatment for acute porphyria attacks consisted of the intravenous administration of hemin. Although attacks are often sporadic, some patients develop recurrent acute attacks, with devastating effects on quality of life. Liver transplantation has historically been the sole curative treatment option. The clinical manifestations of AHP are attributed to the accumulation of the heme precursor 5-aminolevulinic acid (ALA) and porphobilinogen (PBG). Advances in molecular engineering have provided new therapeutic possibilities for modifying the heme synthetic pathway. We reviewed the background and current status of AHP treatment using liver-directed small interfering RNA targeting ALAS1. The therapeutic aim was to normalize the levels of ALAS1, which is highly upregulated during acute porphyria attacks. Givosiran is now an approved drug for use in adults and adolescents aged 12 years and older. The results of clinical trials have shown that givosiran treatment leads to a rapid and sustained reduction of ALAS1 mRNA, decreased heme precursor levels, and a decreased rate of acute attacks compared with placebo. The clinical trials (phases I, II, and III) were all randomized and placebo controlled. Many patients enrolled in the initial clinical trials have continued treatment in open label extension and extended/compassionate-use programs in countries where givosiran is not yet commercially available.

Biomarkers of exposure and effect in a working population exposed to lead, manganese and arsenic.

Lead (Pb), manganese (Mn) and arsenic (As) are among the major toxicants in mining environments. Miners are commonly and repeatedly exposed to this toxic mixture. Some adverse effects may appear at concentrations below environmental quality guidelines for individual mixture components. Further, Pb, Mn, and As induce common adverse outcomes, such as interferences in the cholinergic system and heme synthesis. It is thus vital to monitor miners through biomarkers (BM), such that subclinical effects may be identified at an early stage. The main objectives of this study were to evaluate the exposure of a mining population to these three metals and determine alterations in cholinergic and heme synthesis parameters. Blood and urine samples of workers (n = 60) were obtained from a Portuguese mining industry and compared with a control population (n = 80). The levels of the metals were determined in biological samples, as well as urinary heme precursor levels, delta aminolevulinic acid (ALA) and porphyrins, and blood acetylcholinesterase (AChE) activity. The miners exhibited significantly higher values of Pb and As in blood and urine compared to control. In the case of Mn near or slightly higher than limit values were found. Our data show that heme precursors may be used simultaneously with metal levels as BMs for multiple metal exposures on an individual basis, resulting in 94.3% and 95.7% accuracy, respectively, in blood and urine, for subjects correctly identified with respect to occupation. This study also revealed that biological monitoring of this working population regarding metal body burden and heme precursor accumulation is advisable.

Optimization of heme precursors for the expression of human cytochrome P450 2A13 and its co-expression with oxidoreductase in baculovirus/sf9 system.

Human cytochrome P450 2A13 (CYP2A13), mainly expressed in respiratory tract, is active towards numerous toxicants. To establish the metabolism in vitro, we expressed CYP2A13 and NADPH-CYP450 oxidoreductase (POR) in a baculovirus/sf9 system. Due to the deficiency of sf9 cells in heme incorporation, we investigated the effects of different heme precursors on the expression of CYP2A13, POR and their co-expression. The present results showed that both CYP2A13 and POR were presented the highest expression levels or activity with 0.2 mM δ-aminolaevulinic acid (5-ALA), 0.02 mM Fe(3+) and 0.5-1.0 µg/ml hemin. The combination of 0.2 mM 5-ALA and 0.02 mM Fe(3+) significantly improved CYP2A13 expression and content compared with heme precursors alone, so was POR activity. A multiplicity of infection (MOI) value of 5 pfu/cell for CYP2A13 baculovirus particles induced very high CYP2A13 expression. When co-infected with different POR MOI values, a viral ratio of 5 : 2 was associated with the highest CYP2A13 activity, whereas POR activity dose dependently increased with POR MOI. Furthermore, the expressed CYP2A13 in the optimized conduction could eliminate its substrate aflatoxin B1 at a significantly higher than those in other condition (P < 0.01). Our results provide an efficient approach for expressing functionally characterized, highly active and homogeneous CYP2A13 proteins.

Effects of heme precursors on CYP1A2 and POR expression in the baculovirus/Spodoptera frugiperda system.

OBJECTIVE: CYP1A2 and NADPH-CYP450 oxidoreductase (POR) were expressed in the baculovirus/Spodoptera frugiperda (sf9) system. The aim of this study was to investigate the effects of heme precursors on the expression of CYP1A2 and POR. METHODS: The heme precursors [δ-Aminolaevulinic Acid (5-ALA), Fe(3+) and hemin] were introduced into the system to evaluate their effects on the expression of CYP1A2, POR and their co-expression. All the proteins were identified using immunoblotting, CO-difference spectroscopy, or cytochrome c assay. RESULTS: In the present study, functional CYP1A2 and POR were successfully expressed in the baculovirus/sf9 system, and both of them showed high activities. Co-addition of 5-ALA and Fe(3+) significantly improved expression of CYP1A2 by about 50% compared with the addition of 5-ALA, Fe(3+) or hemin alone. Either co-addition of 5-ALA and Fe(3+) or addition of 5-ALA or Fe(3+) alone improved the POR expression level 2 fold and its activity 7-10 fold compared with control (no addition). However, unlike CYP1A2, there was no difference between the co-addition and addition of these heme precursors alone. Different ratios of BvCYP1A2 to BvPOR also affected the co-expression of CYP1A2 and POR, with a 3:1 ratio of BvCYP1A2 / BvPOR significantly increasing their co-expression. Surprisingly, the addition of 0.1 mM 5-ALA or Fe(3+) alone, but not their co-addition, could significantly improve the CYP1A2 and POR co-expression (P < 0.05). CONCLUSION: 5-ALA and Fe(3+) increased the expression of CYP1A2 and POR in a baculovirus/sf9 system, but the pattern of their expression was different between their expression alone and co-expression.