Nephrogenic systemic fibrosis is associated with hypophosphataemia: a case-control study

Carbonate and phosphite encaged in frameworks constructed from square lanthanum aminopolycarboxylates and sodium chloride

Novel additives of lanthanum aminopolycarboxylates with inorganic anions, Na12n[La(edta)L]4n·8nNaCl·4nH2O (1: L = HPO32-; 2: L = CO32-) and K12n[La(cdta)(CO3)]4n·35nH2O (3) (H4edta = ethylenediaminetetraacetic acid; H4cdta = cyclohexanediaminetetraacetic acid), were obtained in alkaline solution. Structural analyses reveal that 1 and 2 are isomorphous and contain interesting square structures. HPO32- (CO32-) was encaged in the constructed tetranuclear frameworks. Tetranuclear lanthanum ethylenediaminetetraacetate was further encaged in superstructures of sodium chloride. 3 has a similar square structure, in which edta is replaced by cdta. All complexes are fully characterized via elemental, FT-IR, NMR, thermogravimetric and structural analyses. Solution 13C NMR spectra show that 1 and 2 dissociate into mononuclear units in water. Interestingly, 2 possesses 3.7 Å diameter holes inside its crystals, which can adsorb a small amount of O2 or CO2 selectively. The amounts of O2 and CO2 adsorbed increase gradually from 0.32 and 0.38 mg g-1 at 0.4 bar to 15.90 and 10.54 mg g-1 at 29.9 bar, respectively.

Gadolinium-Induced Fibrosis

Gadolinium-based contrast agents (GBCAs), once believed to be safe for patients with renal disease, have been strongly associated with nephrogenic systemic fibrosis (NSF), a severe systemic fibrosing disorder that predominantly afflicts individuals with advanced renal dysfunction. We provide a historical perspective on the appearance and disappearance of NSF, including its initial recognition as a discrete clinical entity, its association with GBCA exposure, and the data supporting a causative relationship between GBCA exposure and NSF. On the basis of this body of evidence, we propose that the name gadolinium-induced fibrosis (GIF) more accurately reflects the totality of knowledge regarding this disease. Use of high-risk GBCAs, such as formulated gadodiamide, should be avoided in patients with renal disease. Restriction of GBCA use in this population has almost completely eradicated new cases of this debilitating condition. Emerging antifibrotic therapies may be useful for patients who suffer from GIF.

Interaction of Gd-DTPA with phosphate and phosphite: toward the reaction intermediate in nephrogenic systemic fibrosis

A commercially used gadolinium based contrast agent Gd-DTPA was substituted by phosphate and phosphite to form K₆[Gd₂(DTPA)₂(HPO₄)]·10H₂O and K₆[Gd₂(DTPA)₂(HPO₃)]·7H₂O respectively. Their analogous lanthanum complies are compared. These results are related to NSF formation.

Do ASARM peptides play a role in nephrogenic systemic fibrosis?

Nephrogenic systemic fibrosis (NSF) is a devastating condition associated with gadolinium (Gd3+)-based contrast agents (GBCAs) in patients with kidney disease. The release of toxic Gd3+ from GBCAs likely plays a major role in NSF pathophysiology. The cause and etiology of Gd3+ release from GBCAs is unknown. Increased Acidic Serine Aspartate Rich MEPE-associated peptides (ASARM peptides) induce bone mineralization abnormalities and contribute to renal phosphate-handling defects in inherited hypophosphatemic rickets and tumor-induced osteomalacia. The proteolytic cleavage of related bone matrix proteins with ASARM motifs results in release of ASARM peptide into bone and circulation. ASARM peptides are acidic, reactive, phosphorylated inhibitors of mineralization that bind Ca2+ and hydroxyapatite. Since the ionic radius of Gd3+ is close to that of Ca2+, we hypothesized that ASARM peptides increase the risk of NSF by inducing release of Gd3+ from GBCAs. Here, we show 1) ASARM peptides bind and induce release of Gd3+ from GBCAs in vitro and in vivo; 2) A bioengineered peptide (SPR4) stabilizes the Gd3+-GBCA complex by specifically binding to ASARM peptide in vitro and in vivo; and 3) SPR4 peptide infusion prevents GBCA-induced NSF-like pathology in a murine model with increased ASARM peptide (Hyp mouse). We conclude ASARM peptides may play a role in NSF and SPR4 peptide is a candidate adjuvant for preventing or reducing risk of disease.