A Plasma Pyrophosphate Cutoff Value for Diagnosing Pseudoxanthoma Elasticum.

Pseudoxanthoma elasticum (PXE) is a rare inherited systemic disease responsible for a juvenile peripheral arterial calcification disease. The clinical diagnosis of PXE is only based on a complex multi-organ phenotypic score and/or genetical analysis. Reduced plasma inorganic pyrophosphate concentration [PPi]p has been linked to PXE. In this study, we used a novel and accurate method to measure [PPi]p in one of the largest cohorts of PXE patients, and we reported the valuable contribution of a cutoff value to PXE diagnosis. Plasma samples and clinical records from two French reference centers for PXE (PXE Consultation Center, Angers, and FAVA-MULTI South Competent Center, Nice) were assessed. Plasma PPi were measured in 153 PXE and 46 non-PXE patients. The PPi concentrations in the plasma samples were determined by a new method combining enzymatic and ion chromatography approaches. The best match between the sensitivity and specificity (Youden index) for diagnosing PXE was determined by ROC analysis. [PPi]p were lower in PXE patients (0.92 ± 0.30 µmol/L) than in non-PXE patients (1.61 ± 0.33 µmol/L, p < 0.0001), corresponding to a mean reduction of 43 ± 19% (SD). The PPi cutoff value for diagnosing PXE in all patients was 1.2 µmol/L, with a sensitivity of 83.3% and a specificity of 91.1% (AUC = 0.93), without sex differences. In patients aged <50 years (i.e., the age period for PXE diagnosis), the cutoff PPi was 1.2 µmol/L (sensitivity, specificity, and AUC of 93%, 96%, and 0.97, respectively). The [PPi]p shows high accuracy for diagnosing PXE; thus, quantifying plasma PPi represents the first blood assay for diagnosing PXE.

Oral pyrophosphate protects Abcc6-/- mice against vascular calcification induced by chronic kidney disease.

One of the hallmarks of chronic kidney disease (CKD) is the development of vascular calcification. Inorganic pyrophosphate is a potent inhibitor of calcification, and previous studies have reported low plasma pyrophosphate levels in hemodialysis patients. A long-term mouse model of CKD-accelerated vascular calcification was developed to study pyrophosphate metabolism and to test whether oral pyrophosphate supplementation attenuates the propensity for arterial calcification. CKD was induced by repeated injections of aristolochic acid in wild-type and Abcc6-/- mice, which tend to develop vascular calcifications. CKD accelerated the development of vascular calcifications in Abcc6-/- mice, in the aorta and small renal arteries, and decreased circulating pyrophosphate levels. Oral pyrophosphate supplementation for 6 months attenuated CKD-induced vascular calcification in this model. These results show that oral pyrophosphate may be of interest in preventing vascular calcification in patients with CKD. KEY MESSAGES: Chronic kidney disease accelerates the development of vascular calcification in pyrophosphate-deficient mice. Oral pyrophosphate supplementation for 6 months attenuates chronic kidney disease-induced vascular calcification in a mouse model. Oral pyrophosphate may be of interest in preventing vascular calcification in patients with chronic kidney disease.

The 32nd Ion Channels Meeting, 17th-20th September 2023, Sète, France.

The 32nd Ion Channel Meetings were organized by the Ion Channels Association from September 17 to 20, 2023 in the Occitanie region (Sète). Researchers, post-docs and students from France, Europe and non-European countries came together to present and discuss their work on various themes covering the field of neuroscience, stem cells, hypoxia and pathophysiology cardiac. Through the plenary conference given by Professor Emilio Carbone and the 5 conferences organized by the scientific committee, attention was paid this year to autism, neuromotor and cardiac disorders and tumor aggressive processes. The scientific exchanges were enriched by two general conferences on the biometric analysis of publications related to ion channels and a retrospective presentation of proven cases of scientific fraud. These presentations are summarized in this meeting report.