Fig 1.
Iron deposition is tissue specific.
A) Gross pictures of eAT from NI and HI groups. B) eAT iron was significantly elevated in HI group. C) Common iron deposition tissues such as liver, pancreas and heart had elevated iron levels in HI. However, iron deposition in duodenum or other adipose tissue depots (i.e. subcutaneous and brown adipose tissue) was not elevated in HI group. D) Serum testosterone and estradiol levels were not significantly different between NI and HI groups. Abbreviations: eAT, epididymal adipose tissue; SubQ, subcutaneous adipose tissue; BAT, brown adipose tissue; Pan, pancreas; Duo, duodenum. **p<0.01 NI (open bar) vs HI (filled bar).
Table 1.
Primers sequences for gene expression.
Fig 2.
A robust tissue remodeling in the HI mice epididymal fat pads.
A) Representitive adipose tissue histology from both NI (left) and HI (right) groups. H&E staining revealed robust adipose tissue cellularity changes in the HI group. A high number of non-adipocytes were observed residing between the adipocytes, Prussian blue staining also showed a robust iron overload in the eAT of HI group. Masson's trichrome stain revealed a significant amount of collagen fibers present among adipocytes in HI compared with NI. Caspase 3 staining suggested greater apoptosis in the HI group. B) Quantification for Prussian blue, Thricrome and caspase 3 staining. Colors: F4/80, brown; Trichrome, blue; Caspase 3, brown; Prussian blue, blue. Scale bars represent 100μm. **p<0.01 NI (open bar) vs HI (filled bar).
Table 2.
Mouse tissue weights.
Fig 3.
No systemic change despite local eAT remodeling and iron change.
A) Serum iron levels between the NI and HI groups. B) Representative H&E staining for liver in NI and HI groups. C) Liver iron-related and inflammatory gene expression. Abbreviations: DcytB, Duodenal cytochrome b; Fpn, ferroportin; Hamp, hepcidin; Vegfa, Vascular endothelial growth factor A; Tnfα, tumor necrosis factor; NI (open bar, n = 6) v.s. HI (filled bar, n = 6). *p< 0.05.
Fig 4.
The elevated iron deposition in the eAT is associated with increased HIF-2α accumulation.
A) eAT gene expression with iron-regulating gene markers. B)&C) adipose tissue iron-regulating protein levels and the quantifaction after normalizing with GAPDH. D) immunoflorescent staining for HIF-2α in NI and HI eAT. Abbreviations: DMT1-IRE, Divalent metal transporter 1-Iron response element, DcytB, Duodenal cytochrome b; TfR1, Fpn, ferroportin; Hamp, hepcidin; Hif-2α, hypoxia inducible factor 2α. *p< 0.05.
Fig 5.
Iron deposition is associated with increased adipose tissue inflammation.
A) Representative adipose tissue F4/80 inmmunoflorescent staining from both NI (left) and HI (right) groups. Quantification for F4/80 antibody staining revealed macrophage clustering among the adipocytes in HI group. B) eAT gene expression with inflammatory gene markers. Abbreviations: Tnfα, tumor necrosis factor; Ccl2, C-C Motif Chemokine Ligand 2; Cxcl1, C-X-C Motif Chemokine Ligand 1, Il10, interlukin 10; Vegfα, Vascular endothelial growth factor A. *p< 0.05.
Fig 6.
Local glucose homeostasis was impaired with increased adipose tissue iron accumulation.
A) Insulin resistance index HOMA-IR, glucose tolerance test (GTT) and the area under the curve (AUC) in both NI and HI groups. B)Serum adiponectin and leptin in NI (n = 6) and HI (n = 4) mice. C) adipose tissiue gene expression with adipokine markers in NI and HI groups. D&E) adipose tissue insulin signaling protein levels and the quantification after normalizing with GAPDH. *p< 0.05.