Calciphylaxis in end-stage kidney disease: outcome data from the United Kingdom Calciphylaxis Study.

BACKGROUND AND AIMS: Calciphylaxis is a rare condition associated with very high mortality in patients with end-stage kidney disease. Data from country-based registries have been an invaluable resource for a better understanding of the natural history and management for this condition. This study aimed to investigate the current management strategies and outcomes of patients enrolled in the United Kingdom Calciphylaxis study (UKCS). METHODS: The study was conducted on 89 patients registered in the UKCS since 2012. The initial analysis included a description of the baseline characteristics, management strategies and outcomes on follow-up until May 2020. Further analysis included a comparison of the mortality outcome of the UKCS patients who were receiving haemodialysis with a propensity score matched cohort of haemodialysis patients from the Chronic Renal Insufficiency Standards Implementation Study- Haemodialysis (CRISIS-HD). RESULTS: Median age of the cohort was 59 years, with a predominance of females (61%) and Caucasian (95%) ethnicity. About 54% of the patients were diabetic and 70% were receiving haemodialysis at study entry. The skin lesions were mostly distributed in the lower extremities (48%). Sodium thiosulphate and calcimimetic were the most widely used management strategies. The mortality rate was 72 deaths per hundred patient-years (50 deaths observed in 69.5 patient years). Complete wound healing was noted in 17% and bacteraemia was reported in 26% of patients. In a comparative analysis of the matched haemodialysis patients, the presence of calciphylaxis in 62 patients showed a strong association with all-cause mortality (HR 6.96; p < 0.001), with annual mortality 67% versus 10.2% in haemodialysis patients without calciphylaxis. CONCLUSIONS: This UK wide study strengthens the evidence that calciphylaxis is a strong and independent risk factor associated with all-cause mortality; no significant benefit was shown with any individual treatment modality. Until further evidence becomes available, a multifaceted approach would be the appropriate treatment strategy in the management of this extremely serious condition.

Vinculin is required to maintain glomerular barrier integrity.

Cell-matrix interactions and podocyte intercellular junctions are key for maintaining the glomerular filtration barrier. Vinculin, a cytoplasmic protein, couples actin filaments to integrin-mediated cell-matrix adhesions and to cadherin-based intercellular junctions. Here, we examined the role of vinculin in podocytes by the generation of a podocyte-specific knockout mouse. Mice lacking podocyte vinculin had increased albuminuria and foot process effacement following injury in vivo. Analysis of primary podocytes isolated from the mutant mice revealed defects in cell protrusions, altered focal adhesion size and signaling, as well as impaired cell migration. Furthermore, we found a marked mislocalization of the intercellular junction protein zonula occludens-1. In kidney sections from patients with focal segmental glomerulosclerosis, minimal change disease and membranous nephropathy, we observed dramatic differences in the expression levels and localization of vinculin. Thus, our results suggest that vinculin is necessary to maintain the integrity of the glomerular filtration barrier by modulating podocyte foot processes and stabilizing intercellular junctions.