Hyperphosphatemia is associated with increased cardiovascular risk in patients with renal disease and in healthy individuals. Here we tested whether high phosphate has a role in the pathophysiology of cardiovascular events by interfering with endothelial function, thereby impairing microvascular function and angiogenesis. Protein expression analysis found downregulation of annexin II in human coronary artery endothelial cells, an effect associated with exacerbated shedding of annexin II-positive microparticles by the cells exposed to high phosphate media. EAhy926 endothelial cells exposed to sera from hyperphosphatemic patients also display decreased annexin II, suggesting a negative correlation between serum phosphate and annexin II expression. By using endothelial cell-based assays in vitro and the chicken chorioallantoic membrane assay in vivo, we found that angiogenesis, vessel wall morphology, endothelial cell migration, capillary tube formation, and endothelial survival were impaired in a hyperphosphatemic milieu. Blockade of membrane-bound extracellular annexin II with a specific antibody mimicked the effects of high phosphate. In addition, high phosphate stiffened endothelial cells in vitro and in rats in vivo. Thus, our results link phosphate and adverse clinical outcomes involving the endothelium in both healthy individuals and patients with renal disease.

Because of the shortage of agalsidase-beta in 2009, many patients with Fabry disease were treated with lower doses or were switched to agalsidase-alfa. This observational study assessed end-organ damage and clinical symptoms during dose reduction or switch to agalsidase-alfa. A total of 105 adult patients with Fabry disease who had received agalsidase-beta (1.0 mg/kg body weight) for $1 year were nonrandomly assigned to continue this treatment regimen (regular-dose group, n=38), receive a reduced dose of 0.3-0.5 mg/kg (dose-reduction group, n=29), or switch to 0.2 mg/kg agalsidase-alfa (switch group) and were followed prospectively for 1 year. We assessed clinical events (death, myocardial infarction, severe arrhythmia, stroke, progression to ESRD); changes in cardiac, renal, and neurologic function; and Fabryrelated symptoms (neuropathic pain, hypohidrosis, diarrhea, and disease severity scores). Organ function and Fabry-related symptoms remained stable in the regular-dose group. In contrast, estimated GFR decreased by about 3 ml/min per 1.73 m 2 (P=0.01) in the dose-reduction group, and the median albuminto-creatinine ratio increased from 114 (0-606) mg/g to 216 (0-2062) mg/g (P=0.03) in the switch group. Furthermore, mean Mainz Severity Score Index scores and frequencies of pain attacks, chronic pain, gastrointestinal pain, and diarrhea increased significantly in the dose-reduction and switch groups. In conclusion, patients receiving regular agalsidase-beta dose had a stable disease course, but dose reduction led to worsening of renal function and symptoms. Switching to agalsidase-alfa is safe, but microalbuminuria may progress and Fabry-related symptoms may deteriorate.

BackgroundFabry disease (FD) is an X-linked multisystemic disorder with a heterogeneous phenotype. Especially atypical or late-onset type 2 phenotypes present a therapeutical dilemma.MethodsTo determine the clinical impact of the alpha-Galactosidase A (GLA) p.A143T/ c.427G > A variation, we retrospectively analyzed 25 p.A143T patients in comparison to 58 FD patients with other missense mutations.Resultsp.A143T patients suffering from stroke/ transient ischemic attacks had slightly decreased residual GLA activities, and/or increased lyso-Gb3 levels, suspecting FD. However, most male p.A143T patients presented with significant residual GLA activity (~50 % of reference), which was associated with normal lyso-Gb3 levels. Additionally, p.A143T patients showed less severe FD-typical symptoms and absent FD-typical renal and cardiac involvement in comparison to FD patients with other missense mutations. Two tested female p.A143T patients with stroke/TIA did not show skewed X chromosome inactivation. No accumulation of neurologic events in family members of p.A143T patients with stroke/transient ischemic attacks was observed.ConclusionsWe conclude that GLA p.A143T seems to be most likely a neutral variant or a possible modifier instead of a disease-causing mutation. Therefore, we suggest that p.A143T patients with stroke/transient ischemic attacks of unknown etiology should be further evaluated, since the diagnosis of FD is not probable and subsequent ERT or chaperone treatment should not be an unreflected option.Electronic supplementary materialThe online version of this article (doi:10.1186/s13023-016-0441-z) contains supplementary material, which is available to authorized users.

Because of the shortage of agalsidase-b supply between 2009 and 2012, patients with Fabry disease either were treated with reduced doses or were switched to agalsidase-a. In this observational study, we assessed end organ damage and clinical symptoms with special focus on renal outcome after 2 years of dose-reduction and/or switch to agalsidase-a.Atotalof89adultpatientswithFabrydiseasewhohadreceivedagalsidase-b (1.0mg/kgbodywt)for.1 yearwerenonrandomlyassignedtocontinuethistreatmentregimen(regular-dosegroup,n=24),toreceiveareduced dose of 0.3-0.5 mg/kg and a subsequent switch to 0.2 mg/kg agalsidase-a (dose-reduction-switch group, n=28), or to directly switch to 0.2 mg/kg agalsidase-a (switch group, n=37) and were followed-up for 2 years. We assessed clinical events (death, myocardial infarction, severe arrhythmia, stroke, progression to ESRD), changes in cardiac and renal function, Fabry-related symptoms (pain, hypohidrosis, diarrhea), and disease severity scores. Determination of renal functionbycreatinineandcystatinC-basedeGFRrevealeddecreasingeGFRsinthedose-reduction-switchgroupand the switch group. The Mainz Severity Score Index increased significantly in these two groups (P=0.02 and P,0.001, respectively), and higher frequencies of gastrointestinal pain occurred during follow-up. In conclusion, after 2 years of observation,allgroupsshowedastableclinicaldiseasecoursewithrespecttoseriousclinicalevents.However,patients under agalsidase-b dose-reduction and switch or a direct switch to agalsidase-a showed a decline of renal function independent of the eGFR formula used.

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