Acute Hepatic Porphyrias: Review and Recent Progress.

The acute hepatic porphyrias (AHPs) are a group of four inherited diseases of heme biosynthesis that present with episodic, acute neurovisceral symptoms. The four types are 5-aminolevulinic acid (ALA) dehydratase deficiency porphyria, acute intermittent porphyria, hereditary coproporphyria, and variegate porphyria. Their diagnoses are often missed or delayed because the clinical symptoms mimic other more common disorders. Recent results indicate that acute intermittent porphyria, the most severe of the more common types of AHP, is more prevalent than previously thought, occurring in about 1 in 1600 Caucasians, but with low clinical penetrance (approximately 2%-3%). Here we provide an updated review of relevant literature and discuss recent and emerging advances in treatment of these disorders. Symptomatic attacks occur primarily in females between 14 and 45 years of age. AHP is diagnosed by finding significantly elevated levels of porphyrin precursors ALA and porphobilinogen in urine. Acute attacks should be treated promptly with intravenous heme therapy to avoid the development of potentially irreversible neurologic sequelae. All patients should be counseled about avoiding potential triggers for acute attacks and monitored regularly for the development of long-term complications. Their first-degree relatives should undergo targeted gene testing. Patients who suffer recurrent acute attacks can be particularly challenging to manage. Approximately 20% of patients with recurrent symptoms develop chronic and ongoing pain and other symptoms. We discuss newer treatment options in development, including small interfering RNA, to down-regulate ALA synthase-1 and/or wild-type messenger RNA of defective genes delivered selectively to hepatocytes for these patients. We expect that the newer treatments will diminish and perhaps obviate the need for liver transplantation as treatment of these inborn metabolic disorders

Gene therapy for monogenic liver diseases: clinical successes, current challenges and future prospects

Over the last decade, pioneering liver-directed gene therapy trials for haemophilia B have achieved sustained clinical improvement after a single systemic injection of adeno-associated virus (AAV) derived vectors encoding the human factor IX cDNA. These trials demonstrate the potential of AAV technology to provide long-lasting clinical benefit in the treatment of monogenic liver disorders. Indeed, with more than ten ongoing or planned clinical trials for haemophilia A and B and dozens of trials planned for other inherited genetic/metabolic liver diseases, clinical translation is expanding rapidly. Gene therapy is likely to become an option for routine care of a subset of severe inherited genetic/metabolic liver diseases in the relatively near term. In this review, we aim to summarise the milestones in the development of gene therapy, present the different vector tools and their clinical applications for liver-directed gene therapy. AAV-derived vectors are emerging as the leading candidates for clinical translation of gene delivery to the liver. Therefore, we focus on clinical applications of AAV vectors in providing the most recent update on clinical outcomes of completed and ongoing gene therapy trials and comment on the current challenges that the field is facing for large-scale clinical translation. There is clearly an urgent need for more efficient therapies in many severe monogenic liver disorders, which will require careful risk-benefit analysis for each indication, especially in paediatrics

Advances in Understanding of Metabolism of B-Cell Lymphoma: Implications for Therapy

There have been significant recent advances in the understanding of the role of metabolism in normal and malignant B-cell biology. Previous research has focused on the role of MYC and mammalian target of rapamycin (mTOR) and how these interact with B-cell receptor signaling and hypoxia to regulate glycolysis, glutaminolysis, oxidative phosphorylation (OXPHOS) and related metabolic pathways in germinal centers. Many of the commonest forms of lymphoma arise from germinal center B-cells, reflecting the physiological attenuation of normal DNA damage checkpoints to facilitate somatic hypermutation of the immunoglobulin genes. As a result, these lymphomas can inherit the metabolic state of their cell-of-origin. There is increasing interest in the potential of targeting metabolic pathways for anti-cancer therapy. Some metabolic inhibitors such as methotrexate have been used to treat lymphoma for decades, with several new agents being recently licensed such as inhibitors of phosphoinositide-3-kinase. Several other inhibitors are in development including those blocking mTOR, glutaminase, OXPHOS and monocarboxylate transporters. In addition, recent work has highlighted the importance of the interaction between diet and cancer, with particular focus on dietary modifications that restrict carbohydrates and specific amino acids. This article will review the current state of this field and discuss future developments

Prep1 (pKnox1) Regulates Mouse Embryonic HSC Cycling and Self-Renewal Affecting the Stat1-Sca1 IFN-Dependent Pathway

<div><p>A hypomorphic <i>Prep1</i> mutation results in embryonic lethality at late gestation with a pleiotropic embryonic phenotype that includes defects in all hematopoietic lineages. Reduced functionality of the hematopoietic stem cells (HSCs) compartment might be responsible for the hematopoietic phenotype observed at mid-gestation. In this paper we demonstrate that Prep1 regulates the number of HSCs in fetal livers (FLs), their clonogenic potential and their ability to <i>de novo</i> generate the hematopoietic system in ablated hosts. Furthermore, we show that Prep1 controls the self-renewal ability of the FL HSC compartment as demonstrated by serial transplantation experiments. The premature exhaustion of Prep1 mutant HSCs correlates with the reduced quiescent stem cell pool thus suggesting that Prep1 regulates the self-renewal ability by controlling the quiescence/proliferation balance. Finally, we show that in FL HSCs Prep1 absence induces the interferon signaling pathway leading to premature cycling and exhaustion of fetal HSCs.</p></div

Prep1 influences HSC quiescent pool rather than HSCs apoptosis.

<p>(A) Representative FACS contour plots to identify apoptotic <i>Prep1^+/+</i> and <i>Prep1^i/i</i> HSCs are shown on the left. The represented plots refer to L⁻S⁺K⁺CD150⁺ gate and numbers in the FACS plots indicate the percentage of cells in parental gates. On the right, the graph represents the mean of apoptotic HSCs (Annexin⁺ DAPI⁻) (n = 3; p = not significant). (B) Representative FACS contour plots to identify the cell cycle distribution of <i>Prep1^+/+</i> and <i>Prep1^i/i</i> HSCs are shown on the left. The represented plots refer to L⁻S⁺K⁺CD150⁺ gate and numbers in the FACS plots indicate the percentage of cells in parental gates. On the right, the graph represents the mean of G0 (Ki67⁻Hoechst^l°^w), G1 (Ki67⁺Hoechst^l°^w) and S/G2/M (Ki67⁺Hoechst^hi) HSCs (n = 3; p = not significant) (n = 3; G0 p = 0.02; G1 and S/G2/M p = not significant).</p

Prep1 controls the number and the functionality of HSCs in E14.5 FLs.

<p>(A) 50, 100 or 200 HSCs sorted from <i>Prep1^+/+</i> and <i>Prep1^i/i</i> FLs were transplanted into lethally irradiated mice in competition with 2×10⁵ CD45.1 BM cells. Mice showing more than 2% CD45.2⁺ cells in the PB were considered as positively repopulated. HSCs are identified as CD45.2⁺ L⁻S⁺K⁺CD150⁺CD48⁻CD41⁻cells. The graph represents the percentage of positively repopulated mice 16 weeks after transplantation (n = 4 for each genotype) (B) The graph indicates the mean chimerism shown by transplanted mice at each cell dosage in the PB 16 weeks after transplantation. (C) 2000 LSK cells purified form <i>Prep1^+/+</i> or <i>Prep1^i/i</i> FLs were transplanted in competition with 1×10⁶ BM cells into lethally irradiated CD45.1 recipients. (D) PB analyses to detect donor-derived (CD45.2⁺) cells performed at 7, 12,16 and 20 weeks after transplantation. In the graph, black bars represent the mean of CD45.2⁺ cells in the PB of <i>Prep1^+/+</i> or <i>Prep1^i/i</i> reconstituted mice (n = 4 for each genotype; p<0.001). (E–F) RUs (on the left) were calculated on FACS data (on the right) obtained from BMs of repopulated mice 20 weeks after transplantation. (E) Mean of RUs in Prep1^+/+ or Prep1^i/i-transplanted mice; p = 0.05. (F) Mean of HSCs RUs in <i>Prep1^+/+</i> or <i>Prep1^i/i</i>-transplanted mice; p = 0.01. HSCs are identified as CD45.2⁺ L⁻S⁺K⁺CD150⁺CD48⁻CD41⁻cells.</p