AUTHOR=Asperti Michela , Naggi Annamaria , Esposito Emiliano , Ruzzenenti Paola , Di Somma Margherita , Gryzik Magdalena , Arosio Paolo , Poli Maura TITLE=High Sulfation and a High Molecular Weight Are Important for Anti-hepcidin Activity of Heparin JOURNAL=Frontiers in Pharmacology VOLUME=6 YEAR=2016 URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2015.00316 DOI=10.3389/fphar.2015.00316 ISSN=1663-9812 ABSTRACT=

Heparins are efficient inhibitors of hepcidin expression even in vivo, where they induce an increase of systemic iron availability. Heparins seem to act by interfering with BMP6 signaling pathways that control the expression of liver hepcidin, causing the suppression of SMAD1/5/8 phosphorylation. The anti-hepcidin activity persists also when the heparin anticoagulant property is abolished or reduced by chemical reactions of oxidation/reduction (glycol-split, Gs-Heparins) or by high sulfation (SS-Heparins), but the structural characteristics needed to optimize this inhibitory activity have not been studied in detail. To this aim we analyzed three different heparins (Mucosal Heparin, the Glycol split RO-82, the partially desulfated glycol-split RO-68 and the oversulfated SSLMWH) and separated them in fractions of molecular weight in the range 4–16 kD. Since the distribution of the negative charges in heparins contributes to the activity, we produced 2-O- and 6-O-desulfated heparins. These derivatives were analyzed for the capacity to inhibit hepcidin expression in hepatic HepG2 cells and in mice. The two approaches produced consistent results and showed that the anti-hepcidin activity strongly decreases with molecular weight below 7 kD, with high N-acetylation and after 2-O and 6-O desulfation. The high sulfation and high molecular weight properties for efficient anti-hepcidin activity suggest that heparin is involved in multiple binding sites.