Hepcidin (25-aa peptide, 4 disulfide bonds) is produced as an 84-aa preprohormone, processed by furin, and acts by binding ferroportin on enterocytes, macrophages, and hepatocytes, triggering endocytosis and lysosomal degradation . Regulation is layered: BMP-6/SMAD signaling responds to hepatic iron; IL-6/JAK2/STAT3 responds to inflammation; erythropoietic signals (TWSG1, GDF15, erythroferone) suppress hepcidin . The authors candidly note that the exact mechanism linking TfR1/TfR2/HFE to SMAD remains unknownβa welcome epistemic honesty.
The review's strongest contribution is its systematic taxonomy of hepcidin-modulating approaches. For hepcidin excess (anemia of inflammation, IRIDA, CKD): anti-hepcidin monoclonal antibodies (e.g., 12B9m), the spiegelmer NOX-H94/lexaptepid pegol, anti-hemojuvelin antibodies (ABT-207, h5F9-AM8), and BMP receptor inhibitors (LDN-193189, TP-0184). For hepcidin deficiency (hemochromatosis, Ξ²-thalassemia): minihepcidins (PR65, PR73), BMP-6 supplementation, and TMPRSS6/matriptase-2 inhibition via siRNA .
The review correctly identifies that no gold-standard hepcidin assay exists; inter-assay variability spans ~10-fold, precluding universal reference intervals . This is a major translational bottleneck the review appropriately flags. However, several blindspots merit scrutiny: (1) hepcidin-independent iron regulation: LPS-induced hypoferremia persists in hepcidin-knockout mice via direct ferroportin/transporter downregulation, suggesting anti-hepcidin therapies may be incomplete . (2) Novel non-canonical roles: hepatocyte-derived hepcidin acts as an antifibrotic hepatokine inhibiting HSC Smad3 phosphorylation via ferroportin-dependent Akt signalingβraising concerns that chronic hepcidin suppression could promote fibrosis . The review does not discuss this antifibrotic axisβa significant omission given proposed minihepcidin therapies. (3) Clinical translation risk: most cited data derive from mouse models; the only phase 2 pilot (NOX-H94 in hematologic malignancies) showed hemoglobin increase in just 5/12 (43%) patients . (4) Assay confounders: RBC transfusions acutely raise serum hepcidin by 31.5% (44.3β58.0 ng/mL) in preterm infants, complicating monitoring .
The review is scientifically sound and comprehensive for its time but inevitably dated (published 2016/2017). It accurately predicts the therapeutic potential later validated by emerging clinical trials. Its main limitations: heavy reliance on animal data, omission of hepcidin's antifibrotic paracrine role, and underweighting of hepcidin-independent inflammatory iron sequestration. Confidence: high for mechanistic claims (multiple converging sources); moderate for clinical translation predictions (limited human data at time of writing).
What would change this conclusion: (1) Large RCTs showing minihepcidin or anti-hepcidin antibody failure despite adequate hepcidin modulation would falsify the causal model; (2) consistent demonstration that hepcidin suppression accelerates fibrosis in patients with pre-existing liver disease would reframe the therapeutic calculus; (3) identification of a dominant hepcidin-independent iron-regulatory pathway would reduce the therapeutic ceiling.
Simulation assumes first-order hepcidin clearance, acute transfusion-driven rise of 31.5% at peak, and exponential decay to baseline; uncertainty bands reflect observed inter-individual CI (30.8β63.8 ng/mL at baseline). Values are modeled, not observed beyond the 10-hour timepoint.
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