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RNAi-mediated silencing of hepatic Alas1 effectively prevents and treats the induced acute attacks in acute intermittent porphyria mice.

ABSTRACT: The acute hepatic porphyrias are inherited disorders of heme biosynthesis characterized by life-threatening acute neurovisceral attacks. Factors that induce the expression of hepatic 5-aminolevulinic acid synthase 1 (ALAS1) result in the accumulation of the neurotoxic porphyrin precursors 5-aminolevulinic acid (ALA) and porphobilinogen (PBG), which recent studies indicate are primarily responsible for the acute attacks. Current treatment of these attacks involves i.v. administration of hemin, but a faster-acting, more effective, and safer therapy is needed. Here, we describe preclinical studies of liver-directed small interfering RNAs (siRNAs) targeting Alas1 (Alas1-siRNAs) in a mouse model of acute intermittent porphyria, the most common acute hepatic porphyria. A single i.v. dose of Alas1-siRNA prevented the phenobarbital-induced biochemical acute attacks for approximately 2 wk. Injection of Alas1-siRNA during an induced acute attack significantly decreased plasma ALA and PBG levels within 8 h, more rapidly and effectively than a single hemin infusion. Alas1-siRNA was well tolerated and a therapeutic dose did not cause hepatic heme deficiency. These studies provide proof-of-concept for the clinical development of RNA interference therapy for the prevention and treatment of the acute attacks of the acute hepatic porphyrias.

SUBMITTER: Yasuda M

PROVIDER: S-EPMC4040563 | biostudies-literature | 2014 May

REPOSITORIES: biostudies-literature

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RNAi-mediated silencing of hepatic Alas1 effectively prevents and treats the induced acute attacks in acute intermittent porphyria mice.

Yasuda Makiko M Gan Lin L Chen Brenden B Kadirvel Senkottuvelan S Yu Chunli C Phillips John D JD New Maria I MI Liebow Abigail A Fitzgerald Kevin K Querbes William W Desnick Robert J RJ

Proceedings of the National Academy of Sciences of the United States of America 20140512 21

The acute hepatic porphyrias are inherited disorders of heme biosynthesis characterized by life-threatening acute neurovisceral attacks. Factors that induce the expression of hepatic 5-aminolevulinic acid synthase 1 (ALAS1) result in the accumulation of the neurotoxic porphyrin precursors 5-aminolevulinic acid (ALA) and porphobilinogen (PBG), which recent studies indicate are primarily responsible for the acute attacks. Current treatment of these attacks involves i.v. administration of hemin, bu ...[more]

PMID: 24821812

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Project description:ObjectiveAcute intermittent porphyria is a rare metabolic disorder that affects heme synthesis. Patients with acute intermittent porphyria may experience acute debilitating neurovisceral attacks that require frequent hospitalizations and negatively impact quality of life. Although clinical aspects of acute intermittent porphyria attacks have been documented, the experience of patients is not well known, particularly for those more severely affected patients who experience frequent attacks. The aim of the present study was to qualitatively characterize the experience of patients with acute intermittent porphyria who have frequent attacks, as well as the impact of the disease on daily living.MethodsPatients with acute intermittent porphyria who experience frequent attacks were recruited and took part in 2-h qualitative one-on-one interviews with a semi-structured guide. Interviews were anonymized, transcribed, and coded. The inductive coding approach targeted textual data related to acute intermittent porphyria attack symptoms, chronic symptoms, and the impact of the disease. Saturation analysis was conducted to assess whether the research elicited an adequate account of patients' experiences.ResultsIn total, 19 patients with acute intermittent porphyria were interviewed (mean age 40 years; 79% female). Eighteen patients (95%) experienced both attack and chronic symptoms. Patients described attacks as the onset of unmanageable symptoms that generally lasted 3-5 days requiring hospitalization and/or treatment. Pain, nausea, and vomiting were considered key attack symptoms; pain, nausea, fatigue, and aspects of neuropathy (e.g., tingling and numbness) were considered key chronic symptoms.ConclusionsIn this study population of acute intermittent porphyria with frequent attacks, most patients had symptoms during and between attacks. In these patients, acute intermittent porphyria appears to have acute exacerbations as well as chronic day-to-day manifestations, and is not just intermittent as its name implies. As a result, patients reported limitations in their ability to function across multiple domains of their lives on a regular basis and not just during acute attacks.

Project description:In the inherited metabolic disorder acute intermittent porphyria (AIP), high sugar intake prevents porphyric attacks due to the glucose effect and the following high insulin levels that may lower AIP disease activity. Insulin resistance is a known risk factor for periodontitis and sugar changes diabetogenic hormones and affects dental health. We hypothesized differences in homeostasis model assessment (HOMA) scores for insulin resistance in AIP cases vs. controls and in those with periodontitis. Our aim was to systematically study dental health in AIP as poor dental health was previously only described in case reports. Further, we aimed to examine if poor dental health and kidney failure might worsen AIP as chronic inflammation and kidney failure might increase disease activity. In 47 AIP cases and 47 matched controls, X-rays and physical examination of clinical attachment loss (CAL), probing pocket depth (PPD), and decayed missing filled teeth (DMFT) were performed. Dietary intake was evaluated through a diet logbook. Plasma cytokines and diabetogenic hormones were measured using multiplex technology and urine porphobilinogen and kidney and liver function by routine methods. An excel spreadsheet from the University of Oxford was used to estimate HOMA scores; beta cell function, HOMA%B (%B), insulin sensitivity, HOMA%S (%S), and insulin resistance HOMA-IR (IR), based on glucose and plasma (P) C-peptide. The Wilcoxon matched-pairs signed rank test, the Mann−Whitney U-test, and Spearman’s non-parametric correlation were used. Insulin (p = 0.007) and C-peptide (p = 0.006) were higher in the AIP cases with periodontitis versus those without. In AIP patients, the liver fibrosis index 4 correlated with DMFT (p < 0.001) and CAL ≥4 mm (p = 0.006); the estimated glomerular filtration rate correlated with DMFT (p < 0.001) and CAL ≥4 mm (p = 0.02). CAL ≥4 mm was correlated with chemokine ligand 11 and interleukin (IL)-13 (p = 0.04 for both), and PPD >5 mm was correlated with plasminogen activator inhibitor-1 (p = 0.003) and complement component 3 (p = 0.02). In conclusion, dental health in AIP cases was correlated with insulin resistance, inflammatory markers, and biomarkers of kidney and liver function, demonstrating that organ damage in the kidney and liver are associated with poorer dental health.

Dataset Information

RNAi-mediated silencing of hepatic Alas1 effectively prevents and treats the induced acute attacks in acute intermittent porphyria mice.

Publications

RNAi-mediated silencing of hepatic Alas1 effectively prevents and treats the induced acute attacks in acute intermittent porphyria mice.

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