Metal deposition in calcific uremic arteriolopathy

The Role of Iron in Calciphylaxis—A Current Review

Calcific uraemic arteriolopathy (CUA), also known as calciphylaxis, is a rare and often fatal condition, frequently diagnosed in end-stage renal disease (ESRD) patients. Although exact pathogenesis remains unclear, iron supplementation is suggested as a potential risk factor. Iron and erythropoietin are the main stay of treatment for anaemia in ESRD patients. Few observational studies support the role of iron in the pathogenesis of calciphylaxis although data from the pivotal trial was not strongly supportive of this argument, i.e., no difference in incidence of calciphylaxis between the low-dose and high-dose iron treatment arms. Elevated levels of vascular cell adhesion molecules in association with iron excess were postulated to the pathogenesis of CUA by causing inflammation and calcification within the microvasculature. In-addition, oxidative stress generated because of iron deposition in cases of systemic inflammation, such as those seen in ESRD, may play a role in vascular calcification. Despite these arguments, a direct correlation between cumulative iron exposure with CUA incidence is not clearly demonstrated in the literature. Consequently, we do not have evidence to recommend iron reduction or cessation in ESRD patients that develop CUA.

Achieving Effective Multimodal Imaging with Rare-Earth Ion-Doped CaF2 Nanoparticles

Nowadays, cancer poses a significant hazard to humans. Limitations in early diagnosis techniques not only result in a waste of healthcare resources but can even lead to delays in diagnosis and treatment, consequently reducing cure rates. Therefore, it is crucial to develop an imaging probe that can provide diagnostic information precisely and rapidly. Here, we used a simple hydrothermal method to design a multimodal imaging probe based on the excellent properties of rare-earth ions. Calcium fluoride co-doped with ytterbium, gadolinium, and neodymium (CaF2:Y,Gd,Nd) nanoparticles (NPs) is highly crystalline, homogeneous in morphology, and displays a high biosafety profile. In addition, in vitro and ex vivo experiments explored the multimodal imaging capability of CaF2:Y,Gd,Nd and demonstrated the efficient performance of CaF2:Y,Gd,Nd during NIR-II fluorescence/photoacoustic/magnetic resonance imaging. Collectively, our novel diagnosis nanoparticle will generate new ideas for the development of multifunctional nanoplatforms for disease diagnosis and treatment.

Calcific Uremic Arteriolopathy: A Case Series and Review from an Inner-City Tertiary University Center in End-Stage Renal Disease Patients on Renal Replacement Therapy

Materials and Methods

24 patients with CUA and on RRT were evaluated at Detroit Medical Center from 2007 to 2016. Skin biopsy was used in almost all patients, along with the radiological and clinical findings. The patient's clinical and paraclinical data were retrieved from the electronic medical records. The effect of treatment modalities and the underlying hyperparathyroidism management were compared to the clinical outcomes using appropriate statistical tests.

Results

Twenty-one patients were on hemodialysis, two patients received renal transplants, and one patient was on peritoneal dialysis. Diabetes mellitus was the most prevalent cause of ESRD. The parathyroid hormone level (PTH) was elevated in 22 patients. Fifteen patients were diagnosed 2 weeks or more prior to skin lesion onset. Twenty-two and thirteen patients received sodium thiosulphate and cinacalcet, respectively. Patients with lower PTH and the calcium-phosphate product levels had a relatively better outcome of CUA.

Conclusions

A multifaceted approach may play a role in treating CUA. Referral to a nephrologist may aid in the early diagnosis and prompt management of CUA.

Localization, Morphologic Features, and Chemical Composition of Calciphylaxis-Related Skin Deposits in Patients With Calcific Uremic Arteriolopathy

Importance

Calcific uremic arteriolopathy (CUA), a rare, potentially fatal, disease with calcium deposits in skin, mostly affects patients with end-stage renal disease who are receiving dialysis. Chemical composition and structure of CUA calcifications have been poorly described.

Objectives

To describe the localization and morphologic features and determine the precise chemical composition of CUA-related calcium deposits in skin, and identify any mortality-associated factors.

Design, Setting, and Participants

A retrospective, multicenter cohort study was conducted at 7 French hospitals including consecutive adults diagnosed with CUA between January 1, 2006, and January 1, 2017, confirmed according to Hayashi clinical and histologic criteria. Patients with normal renal function were excluded. For comparison, 5 skin samples from patients with arteriolosclerosis and 5 others from the negative margins of skin-carcinoma resection specimens were also analyzed.

Main Outcomes and Measures

Localization and morphologic features of the CUA-related cutaneous calcium deposits were assessed with optical microscopy and field-emission-scanning electron microscopy, and the chemical compositions of those deposits were evaluated with μ Fourier transform infrared spectroscopy, Raman spectroscopy, and energy dispersive radiographs.

Results

Thirty-six patients (median [range] age, 64 [33-89] years; 26 [72%] female) were included, and 29 cutaneous biopsies were analyzed. Calcific uremic arteriolopathy and arteriolosclerosis skin calcifications were composed of pure calcium-phosphate apatite. Calcific uremic arteriolopathy vascular calcifications were always circumferential, found in small to medium-sized vessels, with interstitial deposits in 22 (76%) of the samples. A thrombosis, most often in noncalcified capillary lumens in the superficial dermis, was seen in 5 samples from patients with CUA. Except for calcium deposits, the vessel structure of patients with CUA appeared normal, unlike thickened arteriolosclerotic vessel walls. Twelve (33%) patients died of CUA.

Conclusions and Relevance

Calcific uremic arteriolopathy-related skin calcifications were exclusively composed of pure calcium-phosphate apatite, localized circumferentially in small to medium-sized vessels and often associated with interstitial deposits, suggesting its pathogenesis differs from that of arteriolosclerosis. Although the chemical compositions of CUA and arteriolosclerosis calcifications were similar, the vessels' appearances and deposit localizations differed, suggesting different pathogenetic mechanisms.

Calciphylaxis: An Analysis of Concomitant Factors, Treatment Effectiveness and Prognosis in 30 Patients

Background

Calciphylaxis is a rare but severe complication mostly affecting patients with end-stage renal disease (ESRD) and is associated with high morbidity and mortality. The natural history, concomitant factors, pathogenesis, and treatment for calciphylaxis remain equivocal.

Methods

We conducted a retrospective study on patients diagnosed with calciphylaxis in a tertiary care center between January 1, 2012, and December 31, 2017. We describe demographics, co-morbidities, laboratory parameters, effectiveness of sodium thiosulfate treatment and outcomes.

Results

Of the 30 patients (age 65.6 ± 12.79 years, male:female = 8:22), 23 (76.67%) had ESRD and were either on hemodialysis (15 [65.22%], median duration 22.5 months [range 0.2–96 months]) or peritoneal dialysis (8 [34.78%], duration 29±10 months). Predisposing home medications: 8 (28%) had calcium supplements, 10 (36%) had warfarin, 16 (57%) had vitamin D and 5 (18%) had iron supplements. The median parathyroid hormone (PTH) level was 239.8 pg/mL (range 4.7–2922). Calciphylaxis was found on extremities in 21 (70%) and on torso in 6 (20%) patients. Sodium thiosulfate (STS) was given for treatment in 20 (67%) patients and 3 were cured in <2.25 months. One-year survival for all patients with calciphylaxis was 26% (29% for STS group and 20% for those that did not receive STS) and following any surgical treatment regardless of STS use was 14%.

Limitations

Retrospective design, absence of a control group and low power.

Conclusion

Calciphylaxis was more common among females with a predilection for extremities over the torso. Elevations in PTH and inflammatory markers were common. Treatment with STS did not show a statistically significant improvement in survival. Those who were cured, were treated with STS up to three months.

A 71-Year-Old Female with Myocardial Infarction and Long-Standing Ulcers on the Thigh

Calciphylaxis is most commonly encountered in patients with end-stage renal disease; however, it is increasingly observed in nonuremic patients as well. It is important to consider and diagnose nonuremic calciphylaxis early, as prompt treatment and mitigation of associated risk factors is essential to improve long-term outcomes for these patients. Here, we present the case of a 71-year-old woman with atrial fibrillation on warfarin, but without renal disease, who presented with two long-standing ulcers on her thigh and was diagnosed with the aid of biopsy with calciphylaxis. We review the existing literature on the subject and offer this case as a representative report of a clinicopathologic correlation for this disorder.

Synthesis of Multicolor Core/Shell NaLuF₄:Yb3+/Ln3+@CaF₂ Upconversion Nanocrystals

The ability to synthesize high-quality hierarchical core/shell nanocrystals from an efficient host lattice is important to realize efficacious photon upconversion for applications ranging from bioimaging to solar cells. Here, we describe a strategy to fabricate multicolor core @ shell α-NaLuF₄:Yb³⁺/Ln³⁺@CaF₂ (Ln = Er, Ho, Tm) upconversion nanocrystals (UCNCs) based on the newly established host lattice of sodium lutetium fluoride (NaLuF₄). We exploited the liquid-solid-solution method to synthesize the NaLuF₄ core of pure cubic phase and the thermal decomposition approach to expitaxially grow the calcium fluoride (CaF₂) shell onto the core UCNCs, yielding cubic core/shell nanocrystals with a size of 15.6 ± 1.2 nm (the core ~9 ± 0.9 nm, the shell ~3.3 ± 0.3 nm). We showed that those core/shell UCNCs could emit activator-defined multicolor emissions up to about 772 times more efficient than the core nanocrystals due to effective suppression of surface-related quenching effects. Our results provide a new paradigm on heterogeneous core/shell structure for enhanced multicolor upconversion photoluminescence from colloidal nanocrystals.

Localized chrysiasis, aluminum salt deposition and dystrophic calcification a decade after gold injections

Localized chrysiasis is rare and can occur in two settings: after localized or traumatic implantation of elemental gold or gold salts or after localized laser or light therapy in someone who has been previously exposed to systemic gold therapy. We report a unique case of localized chrysiasis with associated aluminum salt deposition and sclerosing lipogranulomas because of previous injections of aurothioglucose (Solganal®). The unique histopathologic findings seen in this case have not been previously reported.

Facile synthesis of β-NaGdF4:Yb/Er@CaF2 nanoparticles with enhanced upconversion fluorescence and stability via a sequential growth process

β-NaGdF₄:Yb,Er@CaF₂ core–shell nanoparticles: β-NaGdF₄:Yb/Er nanoparticles coated with an ultrathin layer of CaF₂ have been achieved via a sequential growth process.

Dissolution of upconverting fluoride nanoparticles in aqueous suspensions

The partial dissolution of selected nanoparticles (NaYF₄, LaF₃ and GdF₃) co-doped with Yb³⁺ and Tm³⁺ was detected and compared with respect to their size, chemical composition and structure.

Gadolinium contrast agent-induced CD163+ ferroportin+ osteogenic cells in nephrogenic systemic fibrosis

Gadolinium-based contrast agents are linked to nephrogenic systemic fibrosis in patients with renal insufficiency. The pathology of nephrogenic systemic fibrosis is characterized by abnormal tissue repair: fibrosis and ectopic ossification. The mechanisms by which gadolinium could induce fibrosis and ossification are not known. We examined in vitro the effect of a gadolinium-based contrast agent on human peripheral blood mononuclear cells for phenotype and function relevant to the pathology of nephrogenic systemic fibrosis using immunofluorescence, flow cytometry, real-time PCR, and osteogenic assays. We also examined tissues from patients with nephrogenic systemic fibrosis, using IHC to identify the presence of cells with phenotype induced by gadolinium. Gadolinium contrast induced differentiation of human peripheral blood mononuclear cells into a unique cellular phenotype--CD163(+) cells expressing proteins involved in fibrosis and bone formation. These cells express fibroblast growth factor (FGF)23, osteoblast transcription factors Runt-related transcription factor 2, and osterix, and show an osteogenic phenotype in in vitro assays. We show in vivo the presence of CD163(+)/procollagen-1(+)/osteocalcin(+) cells in the fibrotic and calcified tissues of nephrogenic systemic fibrosis patients. Gadolinium contrast-induced CD163(+)/ferroportin(+)/FGF23(+) cells with osteogenic potential may play a role in systemic fibrosis and ectopic ossification in nephrogenic systemic fibrosis.

Novel insights into osteogenesis and matrix remodelling associated with calcific uraemic arteriolopathy

BACKGROUND

Calcific uraemic arteriolopathy (CUA) or calciphylaxis is a rare, life-threatening disease predominantly occurring in patients with end-stage renal disease. Its pathogenesis has been suggested to include ectopic osteogenesis in soft tissue and the vasculature associated with extracellular matrix (ECM) remodelling.

METHODS

To gain further insights into the pathogenesis of CUA, we performed systematic analyses of skin specimens obtained from seven CUA patients including histology, immunohistochemistry, electron microscopy, electron dispersive X-ray analysis (EDX) and quantitative real-time RT-PCR. Skin specimens of (i) seven patients without chronic kidney disease and without CUA and (ii) seven dialysis patients without CUA served as controls.

RESULTS

In the CUA skin lesions, we observed a significant upregulation of bone morphogenic protein 2 (BMP-2), its target gene Runx2 and its indirect antagonist sclerostin. Furthermore, we detected an increased expression of inactive uncarboxylated matrix Gla protein (Glu-MGP). The upregulation of osteogenesis-associated markers was accompanied by an increased expression of osteopontin, fibronectin, laminin and collagen I indicating an extensive remodelling of the subcutaneous ECM. EDX analysis revealed calcium/phosphate accumulations in the subcutis of all CUA patients with a molar ratio of 1.68 ± 0.06 matching that of hydroxyapatite mineral. Widespread media calcification in cutaneous arterioles was associated with destruction of the endothelial layer and partial exfoliation of the endothelial cells (ECs). CD31 immunostaining revealed aggregates of ECs contributing to intraluminal obstruction and consecutive malperfusion resulting in the clinical picture of ulcerative necrosis in all seven patients.

CONCLUSIONS

Our data indicate that CUA is an active osteogenic process including the upregulation of BMP-2 signalling, hydroxyapatite deposition and extensive matrix remodelling of the subcutis.

Rare-Earth nanoparticles with enhanced upconversion emission and suppressed rare-Earth-ion leakage

Upconversion emissions from rare-earth nanoparticles have attracted much interest as potential biolabels, for which small particle size and high emission intensity are both desired. Herein we report a facile way to achieve NaYF(4):Yb,Er@CaF(2) nanoparticles (NPs) with a small size (10-13 nm) and highly enhanced (ca. 300 times) upconversion emission compared with the pristine NPs. The CaF(2) shell protects the rare-earth ions from leaking, when the nanoparticles are exposed to buffer solution, and ensures biological safety for the potential bioprobe applications. With the upconversion emission from NaYF(4):Yb,Er@CaF(2) NPs, HeLa cells were imaged with low background interference.

[Cutaneous calciphylaxis]

Calciphylaxis represents a dermatological emergency with a mortality of up to 80%. The disease is characterized by a triad of arteriolar medial calcification, thrombotic cutaneous ischemia and necrotic ulcerations. Recently several mechanisms of vascular calcification have been identified. This may led to preventive measures in the future. Early diagnosis is important to avoid complications such as sepsis. The dermatologist plays an important role in early diagnosis based on the recognition of clinical presentation and histopathology. Patients with end-stage renal disease are most commonly affected by calciphylaxis. The most frequent non-uremic predisposing conditions are primary hyperparathyroidism, malignancies, alcohol-induced liver disease, and autoimmune connective tissue diseases. Medical treatment aims to normalize mineral metabolism to reduce the serum concentration of sodium phosphate and thus to prevent precipitation and calcification. Newer compounds are bisphosphonates, non-sodium/non-aluminium phosphate binders, cinacalcet, paricalcitrol, and sodium thiosulfate. Among the surgical procedures parathyroidectomy did not result in a significant survival benefit. An aggressive surgical debridement of necrotic ulcerations, on the other hand, improved survival. Early diagnosis and a multidisciplinary treatment approach including re-vascularization by the vascular surgeon, repeated surgical debridement and split skin transplantation support wound healing and insure limb conservation.

Quantitative analysis of toxic and essential elements in human hair. Clinical validity of results

Over the last three decades, there has been an increasing awareness of environmental and occupational exposures to toxic or potentially toxic trace elements. The evolution of biological monitoring includes knowledge of kinetics of toxic and/or essential elements and adverse health effects related to their exposure. The debate whether a hair is a valid sample for biomonitoring or not is still attracting the attention of analysts, health care professionals, and environmentalists. Although researchers have found many correlations of essential elements to diseases, metabolic disorders, environmental exposures, and nutritional status, opponents of the concept of hair analysis object that hair samples are unreliable due to the influence of external factors. This review discusses validity of hair as a sample for biomonitoring of essential and toxic elements, with emphasis on pre-analytical, analytical, and post-analytical factors influencing results.

Iron and vascular calcification. Is there a link?

Iron deficiency is frequently seen in patients with end-stage renal disease, particularly in those treated by dialysis, this is because of an impairment in gastrointestinal absorption and ongoing blood losses or alternatively, due to an impaired capacity to mobilize iron from its stores, called functional iron deficiency. Therefore, these patients may require intravenous iron to sustain adequate treatment with erythropoietin-stimulating agents. Aside from this, they are also prone to vascular calcification, which has been reported a major contributing factor in the development of cardiovascular disease and the increased mortality associated herewith. Several factors and mechanisms underlying the development of vascular calcification in chronic kidney diseased patients have been put forward during recent years. In view of the ability of iron to exert direct toxic effects and to induce oxidative stress on the one hand versus its essential role in various cellular processes on the other hand, the possible role of iron in the development of vascular calcification should be considered.

Calciphylaxis in the current era: emerging 'ironic' features?

BACKGROUND

Calcific uraemic arteriolopathy (CUA), previously known as calciphylaxis, is a condition of microvascular calcification and thrombosis with resultant tissue necrosis. Due to the rarity of this disease, our understanding of its pathogenesis remains speculative. Iron has emerged as a potential pathogenic contributor to the development of CUA, but investigation into this link is lacking. The purpose of our study was to explore the clinical characteristics of patients diagnosed with CUA at our institution to allow for comparison to available literature. In addition, we wanted to pursue the possibility of iron being a pathogenic contributor to CUA development. We hypothesized that iron would have to be present in areas of microvascular calcification in order to play a contributing pathogenic role and, therefore, wished to establish whether iron deposition was present within available diagnostic CUA skin biopsy specimens.

METHODS

This study included all patients diagnosed with CUA at our institution between 1997 and 2009 whose tissue was available for further analysis. All available diagnostic skin biopsy specimens were reviewed and further analysed by a dermatopathologist. As the goal was to explore the potential pathogenic role of iron, staining for iron deposition within biopsy specimens was undertaken. All available medical and biochemical information about patients was also collated for analytic purposes and related to the biopsy specimen findings.

RESULTS

Tissue blocks from 12 patients diagnosed with CUA at our institution were available for further analysis. In this CUA cohort, the average age at diagnosis was 61 years (range, 36-83 years), with six (50%) patients being female. Of these patients, 8 (67%) had diabetes, 8 (67%) had coronary artery disease and 10 (83%) had dyslipidaemia. At the time of diagnosis, eight (67%) were on peritoneal dialysis, two (17%) on haemodialysis and two (17%) were pre-dialysis. Our patients had short dialysis vintage times prior to diagnosis (average, 2.1 years). Iron deposition was detected in areas of microvascular calcification in all diagnostic specimens and was absent in unaffected microvasculature within the same biopsy specimens.

CONCLUSIONS

The findings of iron deposition in affected microvasculature lend support to the potential role of iron in the complex pathophysiologic cascade of CUA. The implications for iron therapy in high-risk patients and the possible rationale for the use of sodium thiosulphate, a metal chelator, in the treatment of CUA are explored.