Expression of the peroxisome proliferator-activated receptor alpha gene is stimulated by stress and follows a diurnal rhythm.

Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that can be activated by fatty acids and peroxisome proliferators. The PPAR alpha subtype mediates the pleiotropic effects of these activators in liver and regulates several target genes involved in fatty acid catabolism. In primary hepatocytes cultured in vitro, the PPAR alpha gene is regulated at the transcriptional level by glucocorticoids. We investigated if this hormonal regulation also occurs in the whole animal in physiological situations leading to increased plasma corticosterone levels in rats. We show here that an immobilization stress is a potent and rapid stimulator of PPAR alpha expression in liver but not in hippocampus. The injection of the synthetic glucocorticoid dexamethasone into adult rats produces a similar increase in PPAR alpha expression in liver, whereas the administration of the antiglucocorticoid RU 486 inhibits the stress-dependent stimulation. We conclude that glucocorticoids are major mediators of the stress response. Consistent with this hormonal regulation, hepatic PPAR alpha mRNA and protein levels follow a diurnal rhythm, which parallels that of circulating corticosterone. To test the effects of variations in PPAR alpha expression on PPAR alpha target gene activity, high glucocorticoid-dependent PPAR alpha expression was mimicked in cultured primary hepatocytes. Under these conditions, hormonal stimulation of receptor expression synergizes with receptor activation by WY-14,643 to induce the expression of the PPAR alpha target gene acyl-CoA oxidase. Together, these results show that regulation of the PPAR alpha expression levels efficiently modulates PPAR activator signaling and thus may affect downstream metabolic pathways involved in lipid homeostasis.

La maladie de Fabry chez l'adulte: aspects cliniques et progrès thérapeutiques [Fabry disease in adulthood: clinical aspects and therapeutic progress].

INTRODUCTION: Fabry disease is an X-linked recessive abnormality of glycosphingolipid metabolism that is due to deficiency of the lysosomal enzyme alpha-galactosidase A. CURRENT KNOWLEDGE AND KEY POINTS: A majority of hemizygous men develop severe multisystemic disease (classic form), dominated by renal failure, progressive neurological and cardiac involvement. Nevertheless, some affected men retain sufficient enzyme activity and long remain asymptomatic (atypical form); their main manifestation is hypertrophic cardiomyopathy. Female heterozygous carriers are usually asymptomatic; 15% of them, however, have severe involvement of one or several organs. Laboratory, histologic and molecular diagnosis identifies 100% of hemizygous and over 80% of heterozygous subjects. FUTURE PROSPECTS AND PROJECTS: With developments in molecular genetics, it is now possible to produce the human recombinant enzyme alpha-galactosidase A. Two recent studies had proven that this therapeutic approach was able to be clinically and histologically effective in men. In addition, the results of a trial of gene therapy in a Fabry gene knocked-out mouse appear promising.

Periphere okklusive Vaskulopathie bei einer Patientin mit kombinierter Präeklampsie und Alpha-Thalassämie minor [Peripheral occlusive retinal vasculopathy in a woman with combined preeclampsia and alpha thalassemia minor].

Normalerweise eine Störung der ersten Schwangerschaft, ist die Präeklampsie charakterisiert durch eine arterielle Hypertonie (> 140 mmHg systolisch oder > 90 mmHg diastolisch), die in der Regel nach der 20. Schwangerschaftswoche auftritt und von einer Proteinurie begleitet wird [1]. Die Präeklampsie wird als ,,schwer" bezeichnet, wenn sie mit einer wesentlichen Erhöhung des Blutdrucks (> 160 mmHg systolisch oder > 110 mmHg diastolisch), schwerer Proteinurie, Oligurie, Lungenödem, abdominalen Schmerzen, Leberfunktionsstörungen, Thrombozytopenie und visuellen oder zerebralen Symptomen einhergeht. Eine Eklampsie wiederum ist durch die Entwicklung von tonisch-klonischen Anfällen bei einer präeklamptischen Patientin charakterisiert. Bei der Alpha-Thalassämie tritt ein Defekt von 2 oder mehr der 4 Alpha-Globin-Gene auf. Von einer Alpha-Thalassämie minor spricht man, wenn 2 Alpha-Ketten-Gene deletiert sind. Sie tritt häufig bei Menschen aus Afrika, Südostasien, dem westindischen und mediterranen Raum auf. Die Alpha-Thalassämie minor verursacht eine milde bis moderate mikrozytäre Anämie. Wir berichten über eine Patientin mit peripherer okklusiver Vaskulopathie im Rahmen einer kombinierten Präeklampsie und Alpha-Thalassämie minor.

T cell receptor beta chain gene rearrangements and V beta gene usage in horse cytochrome c-specific T cell hybridomas.

Comparison of T cell receptor alpha and beta-chain genes in murine major histocompatibility complex (MHC) class I and class II-restricted T cell clones and hybridomas recognizing different antigens indicates that no simple correlation exists between the observed antigen/MHC specificity and the expression of certain alpha and beta-chain heterodimers. We have attempted to establish a possible correlation by analyzing T cell receptor beta chain gene rearrangements and V beta gene usage in five T cell hybridomas with identical antigen/MHC specificity and another hybridoma recognizing a different antigenic determinant in association with the same restriction molecule. We report here that in each of the five clones a uniquely rearranged beta chain gene is expressed in combination with at least two different V beta gene segments. The presence of the differently rearranged T cell receptor beta chain genes correlated with the finding of distinct fine specificity pattern of antigen recognition in each of the hybridomas. Interestingly, two hybridomas specific for different epitopes showed identical beta chain D-J rearrangements indicating that the differences might be encoded by the alpha chain gene or/and the V beta gene element.

Premature replacement of mu with alpha immunoglobulin chains impairs lymphopoiesis and mucosal homing but promotes plasma cell maturation.

Sequentially along B cell differentiation, the different classes of membrane Ig heavy chains associate with the Ig alpha/Ig beta heterodimer within the B cell receptor (BCR). Whether each Ig class conveys specific signals adapted to the corresponding differentiation stage remains debated. We investigated the impact of the forced expression of an IgA-class receptor throughout murine B cell differentiation by knocking in the human C alpha Ig gene in place of the S mu region. Despite expression of a functional BCR, homozygous mutant mice showed a partial developmental blockade at the pro-B/pre-BI and large pre-BII cell stages, with decreased numbers of small pre-BII cells. Beyond this stage, peripheral B cell compartments of reduced size developed and allowed specific antibody responses, whereas mature cells showed constitutive activation and a strong commitment to plasma cell differentiation. Secreted IgA correctly assembled into polymers, associated with the murine J chain, and was transported into secretions. In heterozygous mutants, cells expressing the IgA allele competed poorly with those expressing IgM from the wild-type allele and were almost undetectable among peripheral B lymphocytes, notably in gut-associated lymphoid tissues. Our data indicate that the IgM BCR is more efficient in driving early B cell education and in mucosal site targeting, whereas the IgA BCR appears particularly suited to promoting activation and differentiation of effector plasma cells.

Amphibian albumins as members of the albumin, alpha-fetoprotein, vitamin D-binding protein multigene family.

The Xenopus laevis 68-kd and 74-kd albumin amino acid sequences are examined with respect to their relationship to the other known members of the albumin/alpha-fetoprotein/vitamin D-binding protein gene family. Each of the three members of this family presents a unique pattern of conserved regions indicating a differential selective pressure related to specific functional characteristics. Furthermore, an evolutionary tree of these genes was deduced from the divergence times calculated from direct nucleotide sequence comparisons of individual gene pairs. These calculations indicate that the vitamin D-binding protein/albumin separation occurred 560-600 million years (Myr) ago and the albumin/alpha-fetoprotein divergence 280 Myr ago. This observation leads to the hypothesis according to which the albumin/alpha-fetoprotein gene duplication occurred shortly after the amphibian/reptile separation. Consequently, and unlike mammals, amphibians and fishes should lack an alpha-fetoprotein in their serum at larval stages, which is consistent with a recent analysis of serum proteins in Xenopus laevis larvae. This hypothesis now will have to be tested further in additional lower vertebrates.

Enzyme replacement therapy with agalsidase alfa in patients with Fabry's disease: an analysis of registry data.

BACKGROUND: We analysed 5-year treatment with agalsidase alfa enzyme replacement therapy in patients with Fabry's disease who were enrolled in the Fabry Outcome Survey observational database (FOS). METHODS: Baseline and 5-year data were available for up to 181 adults (126 men) in FOS. Serial data for cardiac mass and function, renal function, pain, and quality of life were assessed. Safety and sensitivity analyses were done in patients with baseline and at least one relevant follow-up measurement during the 5 years (n=555 and n=475, respectively). FINDINGS: In patients with baseline cardiac hypertrophy, treatment resulted in a sustained reduction in left ventricular mass (LVM) index after 5 years (from 71.4 [SD 22.5] g/m(2.7) to 64.1 [18.7] g/m(2.7), p=0.0111) and a significant increase in midwall fractional shortening (MFS) from 14.3% (2.3) to 16.0% (3.8) after 3 years (p=0.02). In patients without baseline hypertrophy, LVM index and MFS remained stable. Mean yearly fall in estimated glomerular filtration rate versus baseline after 5 years of enzyme replacement therapy was -3.17 mL/min per 1.73 m(2) for men and -0.89 mL/min per 1.73 m(2) for women. Average pain, measured by Brief Pain Inventory score, improved significantly, from 3.7 (2.3) at baseline to 2.5 (2.4) after 5 years (p=0.0023). Quality of life, measured by deviation scores from normal EuroQol values, improved significantly, from -0.24 (0.3) at baseline to -0.17 (0.3) after 5 years (p=0.0483). Findings were confirmed by sensitivity analysis. No unexpected safety concerns were identified. INTERPRETATION: By comparison with historical natural history data for patients with Fabry's disease who were not treated with enzyme replacement therapy, long-term treatment with agalsidase alfa leads to substantial and sustained clinical benefits. FUNDING: Shire Human Genetic Therapies AB.

The role of ceramide trihexoside (globotriaosylceramide) in the diagnosis and follow-up of the efficacy of treatment of Fabry disease: a review of the literature.

Fabry disease is caused by a deficiency of a-galactosidase A which leads to the progressive intra-lysosomal accumulation of ceramide trihexoside (CTH), also known as globotriaosylceramide (Gb3), in different cell types and body fluids. The clinical manifestations are multisystemic and predominantly affect the heart, kidney and central nervous system. The role of CTH in the pathophysiological process of Fabry disease is not established, and the link between the degree of accumulation and disease manifestations is not systematic. The use of CTH as a diagnostic tool has been proposed for several decades. The recent introduction of a specific treatment for Fabry disease in the form of enzyme replacement therapy (ERT) has led to the need for a biological marker, in place of a clinical sign, for evaluating the efficacy of treatment and also as a tool for following the long term effects of treatment. The ideal biomarker must adhere to strict criteria, and there should be a correlation between the degree of clinical efficacy of treatment and a change in its concentration. This review of the literature assesses the utility of CTH as a diagnostic tool and as a marker of the efficacy of ERT in patients with Fabry disease. Several techniques have been developed for measuring CTH; the principles and the sensitivity thresholds of these methods and the units used to express the results should be taken into consideration when interpreting data. The use of CTH measurement in Fabry disease should be re-evaluated in light of recent published data.

Kidney transplantation in patients with Fabry disease

Introduction and Aims: Fabry disease is an X-linked lysosomal storage disorder caused by absence or deficient activity of the lysosomal enzyme alpha-galactosidase A. Renal manifestations occur early in life in a significant proportion of children, in many women and in almost all men with Fabry disease. These manifestations ultimately progress to end-stage renal disease in nearly all males and in some female patients. Data on kidney transplantation in patients with Fabry disease who are receiving enzyme replacement therapy (ERT), however, are scarce. Methods: We examined the clinical characteristics of kidney transplant recipients (KTRs) in the Fabry Outcome Survey (FOS) - a European database of patients with Fabry disease that was established to monitor the safety and outcome of ERT. Results: Of the 752 patients enrolled in FOS up to October 2005, 34 (4.5%) were reported to be KTRs. The mean age of these 32 male and 2 female patients was 45 ± 9 years, the median time since the transplant was 9 years, the median estimated glomerular filtration rate (eGFR) was 46 mL/min/1.73 m2 and the median level of proteinuria was 180 mg/24 hours. ERT was well tolerated, with mild infusion-related reactions reported in only one patient. Amongst these patients, 53% were reported to have hypertension, 71% left ventricular hypertrophy, 27% cardiac valve disease and 27% arrhythmia. A total of 23 (68%) of the patients (1 female, 22 males) were receiving ERT with agalsidase alfa (Replagal; Shire Human Genetic Therapies, UK), with a median duration of treatment of 2.5 years. There were no differences in age or time since transplantation between treated and untreated patients. The median eGFRs were 46 and 49 mL/min/1.73 m2 and the median levels of proteinuria were 200 and 160 mg/24 hours, respectively. Conclusions: KTRs represent a significant minority of individuals enrolled in a large international registry of patients with Fabry disease (FOS). Approximately two-thirds of KTRs with Fabry disease enrolled in FOS receive ERT with agalsidase alfa, which is well tolerated. Comparison of treated and untreated patients has the potential to examine effects of ERT on the progression of renal and cardiovascular disease.

Mitofusins 1/2 and ERRalpha expression are increased in human skeletal muscle after physical exercise

Mitochondrial impairment is hypothesized to contribute to the pathogenesis of insulin resistance. Mitofusin (Mfn) proteins regulate the biogenesis and maintenance of the mitochondrial network, and when inactivated, cause a failure in the mitochondrial architecture and decreases in oxidative capacity and glucose oxidation. Exercise increases muscle mitochondrial content, size, oxidative capacity and aerobic glucose oxidation. To address if Mfn proteins are implicated in these exercise-induced responses, we measured Mfn1 and Mfn2 mRNA levels, pre-, post-, 2 and 24 h post-exercise. Additionally, we measured the expression levels of transcriptional regulators that control mitochondrial biogenesis and functions, including PGC-1alpha, NRF-1, NRF-2 and the recently implicated ERRalpha. We show that Mfn1, Mfn2, NRF-2 and COX IV mRNA were increased 24 h post-exercise, while PGC-1alpha and ERRalpha mRNA increased 2 h post-exercise. Finally, using in vitro cellular assays, we demonstrate that Mfn2 gene expression is driven by a PGC-1alpha programme dependent on ERRalpha. The PGC-1alpha/ERRalpha-mediated induction of Mfn2 suggests a role of these two factors in mitochondrial fusion. Our results provide evidence that PGC-1alpha not only mediates the increased expression of oxidative phosphorylation genes but also mediates alterations in mitochondrial architecture in response to aerobic exercise in humans

Maladie de Fabry: du diagnostic a l'enzymotherapie substitutive. [Fabry disease: diagnostic due of substitutive enzyme-therapy]

Fabry disease is a X-linked sphingolipid storage disorder resulting from the defective activity of the lysosomal enzyme, alpha-galactosidase A. Hemizygotes develop severe multisystemic disease, dominated by renal failure and progressive neurological and cardiac involvement, causing premature death. Thirty percent of heterozygotes have severe involvement of one or several organs. With developments in molecular biology, it is now possible to produce the human recombinant enzyme alpha-galactosidase A. More than 20 patients are now treated in Switzerland.

Clinical results of enzyme replacement therapy in Fabry disease: a comprehensive review of literature.

Enzyme replacement therapy (ERT) has been used to treat Fabry disease - a progressive lysosomal storage disorder - since 2001. Two preparations of the enzyme alpha-galactosidase A are available in Europe: agalsidase alpha, produced in a human cell line, and agalsidase beta, produced in Chinese hamster ovary cells. To review critically the published evidence for the clinical efficacy of these two enzyme preparations. A systematic literature search was undertaken to identify open or randomised controlled trials published on Fabry disease since 2001. Eleven trials fulfilled the criteria for inclusion in this review, of a total of 586 references on Fabry disease. To date, no direct comparisons exists between the two available enzyme preparations. Significant clinical benefits compared with placebo, however, have been demonstrated with ERT, with positive effects on the heart, kidneys, nervous system and quality of life. The quality of most of these publications was less than optimal. Further prospective studies are required to confirm the long-term clinical benefits of ERT. More studies are also needed on the effects of ERT in women and on the use of ERT early in the course of Fabry disease, to prevent organ damage. Large national and international outcomes databases will also be invaluable in evaluating treatment effects and safety.

Maladie de Fabry. Analyse sémiologique de 17 familles en France et en Suisse

Etude de cohorte en France et en Suisse (7 centres). Analyse sémiologique des cas de maladie de Fabry (MF). Les cas index étaient 12 H, 5 F : âgemoyen au diagnostic 30 (9-58) et 34 ans (10-49), resp. Chez les H, le 1er symptôme était : acroparesthésies (acroP) (n=9) en moyenne à 8 ans (4-19). Le délai moyen premier symptôme-MF était de 17 ans (0-51), plus court en cas d'acroP qu'en cas d'autre symptôme révélateur (12.3 vs 19.6 ans). Les acroP « négligées » retardaient le diagnostic : angiokératomes (n=1, délai 28 ans), AVC du sujet jeune (n=2, délais 20 et 24 ans), insuffisance rénale terminale (n=1, délai 51 ans). Deux patients avaient une sémiologie complète : acroP, angiokératomes, hypohidrose, cornée verticillée, atteinte cérébrale, rénale (2 transplantations), cardiaque. Une hypoacousie était fréquente (n=6). Les errances diagnostiques ont été : SEP, neurobrucellose, PAN, cardiomyopathie hypertensive malgré l'absence d'HTA. Chez les F, le 1er symptôme était : acroP (n=3), cornée verticillée (n=1), angiokératomes (n=1). Le délai premier symptôme-MF était en moyenne de 15.6 ans (0-37). Tous les patients, à l'exception d'1 F, sont sous traitement enzymatique. Dans leurs familles, 47 autres cas (27H/20F) ont été diagnostiqués. La MF est à transmission dominante liée à l'X, avec expressivité variable. Elle atteint l'homme et la femme. Le diagnostic est trop tardif : l'interniste doit connaître la MF pour laquelle existe un traitement par alpha-galactosidase.

Cystatin C as a marker of early changes of renal function in Fabry nephropathy.

BACKGROUND: A sensitive, feasible and reproducible marker for renal function is necessary to evaluate the clinical efficacy of enzyme replacement therapy (ERT) in Fabry nephropathy. Serum creatinine has some limitations and cystatin C has been proposed, in other nephropathies, as a useful marker of renal function. The use of cystatin C as a marker of glomerular filtration rate (GFR) was investigated in Fabry patients receiving ERT. METHODS: Renal function was evaluated with serum creatinine, serum cystatin C and estimated GFR (through Modification of Diet in Renal Disease [MDRD], Cockcroft-Gault [C&G] and Hoek formulae) in 21 Fabry patients receiving ERT with agalsidase alfa for 3 years and in 13 Fabry patients receiving agalsidase alfa for 4 years. RESULTS: During years of ERT while serum creatinine remained stable, cystatin C values showed a significant, increasing trend right from the first year of ERT. CONCLUSIONS: In Fabry disease, cystatin C is a sensitive and reliable marker of renal function, and it should be taken into account when evaluating GFR trends during ERT.

Les biomarqueurs dans la maladie de Fabry: relation entre Sphingosine-1 phosphate et Lyso-Gb3

Problématique : La maladie de Fabry est une maladie métabolique à stockage lysosomal. C'est une maladie héreditaire à transmission récessive qui concerne l'enzyme alpha-Galactosidase A. Le gène de l'alpha-Galactosidase A (GLA) se trouve au niveau du bras long du chromosome X «carté en Xq21.33-Xq22 ». L'enzyme muté ne recouvre plus son rôle catabolisateur et il ne métabolise pas le substrat globotriaosylceramide (Gb3). Par conséquence le Gb3 s'accumule dans tous les tissus. Dans les parois des vaisseaux sanguins le Gb3 s'accumule dans l'endothelium, la tunique interne des vaisseaux sanguins. Ce déficit métabolique se traduit par l'épaississement de la paroi vasculaire, des processus d'infarctus et ischémies du tissu cardiaque, rénal et cérébral. L'implication cardiaque de la maladie de Fabry est décrite chez plus de 78% des patients affectés par la maladie et se manifeste par une hypertrophie cardiaque du ventricule gauche. Toutefois, il n'existe pas de relation étroite entre hypertrophie cardiaque et le Gb3. La sphingosine 1-phosphate à été identifiée dans notre laboratoire et proposée comme facteur de croissance à l'origine du remodelage cardiovasculaire. De plus, la Globotriaosylsphingosine (Lyso-Gb3) à été aussi proposée comme facteur vasoactif chez les patients Fabry. Objectif : L'identification d'un biomarqueur pour le diagnostic et le suivi thérapeutique de la maladie de Fabry représente une domaine d'investigation active en recherche scientifique. Le Gb3 plasmatique ou dans les urines, la biopsie rénale ou cardiaque qui est mis en évidence grâce à la microscopie électronique sous forme de corps concentrique lamellaires, constituent les biomarqueurs classiques de la maladie de Fabry. Dernièrement, le Lyso-Gb3 et le Sphingosine-1 phosphate (S1P) ont été proposés comme marqueurs du remodelage cardiovasculaire. Le but de ce travail est de rassembler et de discuter la littérature concernant ces nouveaux marqueurs et, d'étudier une possible interaction entre Lyso-Gb3 et le S1P. Méthodologie : Rassembler la littérature scientifique et analyser l'implication de ces marqueurs dans la maladie de Fabry et leur effets cardiovasculaires. De plus, un travail expérimental est effectué. Ce travail consiste en l'identification d'une relation possible entre le Lyso-Gb3 et le S1P. Résultats : Avec ce travail on a cherché à actualiser et mettre à jour les notions concernant les biomarqueurs qui prennent place dans cette pathologie et les connaissances qu'on possède à ce jour sur les manifestations cardiovasculaires et neurologiques.La recherche d'un biomarqueur prime par le fait qu'un nombre considerable de patients est sous-diagnostiqués pour la maladie de Fabry et que entre les taux de substrat enzymatique accumulé dans les tissus et l'hypertrophie cardiaque, on peut constater une discordance. Grâce à ce travail expérimental, on a exclue la possibilité d'un effet précurseur du lyso-Gb3 pour le S1P. Nous avons montré que le Lyso-Gb3 est reconnu par les récepteurs du S1P avec des effets commun pour les S1P1-3 et différents pour le S1P2. Les taux du Lyso-Gb3 et du S1P doivent être mesuré chez les patients Fabry et une stratégie thérapeutique doit prendre en compte le rapport S1P/Lyso-Gb3.