Oral Delivery of Dmt1 siRNAs by Ginger Nanoparticle‐derived Lipid Vectors Mitigates Iron Loading in Hepcidin KO Mice
Authors: Wang Xiaoyu , Zhang Mingzhen , Flores Shireen R.L. , Woloshun Regina R. , Yang Chunhua , Yin Liangjie , Xiang Ping , Xu Xiaodong , Garrick Michael D. , Vidyasagar Sadasivan , Merlin Didier , Collins James F 
Published: June 2021

Introduction

Inappropriately increased intestinal iron absorption, leading to pathologic tissue iron accumulation, typifies a group of iron‐loading disorders collectively referred to as hereditary hemochromatosis (HH). HH is caused by genetic mutations that lead to inappropriately low (or absent) production of the iron‐regulatory hormone hepcidin, which functions to regulate intestinal iron absorption to match iron requirements (since no iron‐excretory mechanisms exist in mammals). Dietary iron assimilation relies principally on the enterocyte iron importer, divalent metal‐ion transporter 1 (Dmt1). Dmt1 may thus be a plausible therapeutic target to blunt iron absorption in HH. Furthermore, nanoparticles (NPs) have been utilized to deliver drugs to the intestinal epithelium in vivo, and NPs derived from edible plants are less toxic than synthetic NPs. Here, we utilized Ginger NP‐derived Lipid Vectors (GDLVs) to deliver functional siRNAs to the intestinal epithelium in a proof‐of‐concept investigation to test the hypothesis that inhibiting expression of Dmt1 would attenuate iron loading in murine HH.

Methods

The Ussing chamber technique was utilized to define the kinetics of duodenal iron transport in intestine‐specific, Dmt1 KO (Dmt1int/int) mice and littermate controls. Dmt1int/int mice were crossed with hepcidin KO mice (which model an early‐onset, severe form of HH). Functional Dmt1 siRNAs were developed in vitro. Additional experiments established a protocol to produce GDLVs carrying functional Dmt1 siRNAs, and target these gene‐delivery vehicles to the duodenal epithelium in vivo (by incorporating folic acid [FA]). Subsequently, GDLVs carrying functional Dmt1 siRNAs were administered by oral, intragastric gavage to weanling hepcidin KO mice in vivo (for 16 days) and iron loading was assessed.

Results

Initial experiments using duodenal organ cultures from Dmt1int/int mice in the Ussing chamber established that Dmt1 is the only active iron importer during iron‐deficiency anemia (when iron transport is enhanced). Further, when Dmt1int/int mice were crossed with hepcidin KO mice, iron loading was prevented. Hence, intestinal Dmt1 is required for the excessive iron absorption that typifies murine HH. When FA‐GDLVs carrying Dmt1 siRNA were administered to weanling Hepc−/− mice for 16 days, intestinal Dmt1 mRNA expression was attenuated and tissue iron accumulation was blunted.

Conclusions

Intestinal Dmt1 is: 1) the principal, regulated intestinal iron importer in mice; 2) responsible for iron accumulation in hepcidin KO mice; and 3) a bona fide therapeutic target in murine (and probably human) HH.

Support or Funding Information

This work was supported by NIH grants R01 DK074867 and R01 DK109717 (to JFC).

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.