Hepcidin modulation in human diseases: From research to clinic

Table 1 Positive and negative regulators of hepcidin production, signalling pathways involved and human diseases either caused by defective function of the regulatory protein (Hemochromatosis, IRIDA) or inducing activation or suppression of the regulatory pathway

Positive regulators	Signalling pathway	Human disease	Negative regulators	Signalling pathway	Human disease
Inflammation [IL-6, IL-1α]	STAT-3	Anemia of chronic disease	Hypoxia [HIF1, sHJV, ROS]	HIF-1, BMPs/SMAD Oxygenases inhibition	--
Iron stores [mHJV]	BMPs/ SMAD4	Hemochromatosis	Iron stores [Matriptase2, s-HJV, GDF15]	BMPs/SMAD inhibition	IRIDA, iron deficiency
Iron stores [HFE, TfR2]	BMPs/ SMAD4	Hemochromatosis	Erythropoiesis [GDF15, others?]	BMPs/SMAD inhibition others?	Thalassemia, CDA1
Liver metabolic activities	C/EBPα		Erythropoietin?	C/EBPα block
Oxygenases	?		Oxidative stress [ROS]	C/EBPα, STAT3 block; Oxygenases inhibition HDAC activation	Hepatitis C viral and alcoholic liver disease

IRIDA: Iron refractory iron deficiency anemia; CDA1: Congenital dyserythropoietic anemia type 1; Oxygenases: Family of 2-oxoglutarate-dependent oxygenases including prolyl and aspariginyl hydroxilases, PHDs and FIH. References: Andrews[6], De Domenico et al[7], Braliou et al[42], Choi et al[43], Nemeth[38] , Pinto et al[39], Pak et al[40], Tanno et al[41], Lakhal et al[54], Tamary et al[55], Silvestri et al[57], Silvestri et al[59], Miura et al[101], Harrison-Findik[46].

Table 2 Recently published methods for hepcidin quantification in biological fluids

Method	Reported normal range in serum (No. of controls)	Intra-assay precision (CV1) (%)	Internal standard	Note	LLOD2	Reference
C-ELISA	29-254 ng/mL (males) 17-286 ng/mL (females) (n = 114)	5-19	n.a.	Also used to quantify hepcidin in urine	5 ng/mL	Ganz[76], 2008
Quantitative SELDI-TOF-MS	9-45 ng/mL (males) 7-15 ng/mL (females) (n = 23)	5.7-11.7	Des-Asp Hepcidin-24 (deletion of aspartate residue at position 25)	Also used to quantify hepcidin in urine	3 ng/mL	Swinkels[77], 2008
Quantitative SELDI-TOF-MS	50 ng/mL (average in females) (n = 24)	8-9	Stable isotope labelled hepcidin (13C/15N phenylalanine at position 9)		10 ng/mL	Ward[79], 2008
Micro-HPLC tandem tandem MS	1-19.5 ng/mL (males) 1-6.5 ng/mL (females) (n = 10)	4.8-21	Stable isotope labelled hepcidin (13C/15N isoleucines at position 6-8)		1 ng/mL	Kobold[78], 2008
Liquid Cromatography tandem MS	n.a.	8.7-12.5	Stable isotope labelled hepcidin (13C/15N glycines at position 12-20)	Only used in urine for the moment	n.a.	Bansal[75], 2008
Hepcidin binding domain based test	39-88 ng/mL (n = 40)	< 5	n.a.	Potential for measuring true biologically active hepcidin (e.g. able to bind ferroportin)	n.r.	De Domenico[1], 2008

n.a.: Not applicable; n.r.: Not reported;

¹Coefficient of variation. CV ranges refer to samples with different hepcidin concentrations. With all methods, variations in repeated assays were higher at the lower hepcidin concentration;

²Lower limit of detection.