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Suppressive effects of iron overloading on vascular calcification in uremic rats
Takuya Seto1, Chieko Hamada, Yasuhiko Tomino
1Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
Insights
Iron administration surprisingly suppressed medial vascular calcification in chronic kidney disease (CKD) rats. This finding suggests iron may protect against vascular calcification by reducing phosphate transporter (Pit)-1 expression.
Area of Science:
- Nephrology
- Cardiovascular Biology
- Biochemistry
Background:
- Medial vascular calcification is a common complication in chronic kidney disease (CKD) patients.
- The underlying mechanisms of vascular calcification in CKD remain unclear.
- Iron (Fe) administration, used for anemia in CKD, can induce oxidative stress.
Purpose of the Study:
- To investigate the effect of iron loading on vascular calcification in a rat model of uremia.
- To elucidate the potential mechanisms by which iron influences vascular calcification.
Main Methods:
- Thirty-two rats were divided into control, iron-treated, uremic, and uremic plus iron-treated groups.
- Uremia was induced using an adenine-enriched diet.
- Iron dextran was administered weekly for five weeks; aortic walls were analyzed for calcification and related factors.
Main Results:
- Uremic rats exhibited severe aortic calcification, which was suppressed by iron administration.
- Iron loading reduced the expression of runt-related transcription factor 2 (Runx2) and phosphate transporter (Pit)-1 in uremic rats.
- Single-strand DNA (ssDNA) expression was not affected by iron in uremic rats.
Conclusions:
- Iron administration effectively suppressed the development of medial vascular calcification in uremic rats.
- Iron's protective effect is linked to the downregulation of Pit-1 and the prevention of vascular smooth muscle cell osteoblastic transdifferentiation.
Background:
Medial vascular calcification is a specific complication in chronic kidney disease (CKD) patients although its pathogenesis is poorly understood. The administration of iron (Fe), generally used for the treatment of anemia in CKD patients, induces oxidative stress. Fe loading possibly affects the progress of vascular calcification in uremia. We investigated the effect of Fe on vascular calcification and its mechanism in uremic rats.
Method:
Thirty-two rats were divided into four groups: untreated rats (controls), rats fed a standard diet with Fe administration (Fe group), rats fed an adenine-enriched diet (uremic group), and rats fed an adenine-enriched diet with Fe administration (uremic + Fe group). Iron dextran was administered once a week for 5 weeks intraperitoneally. Morphological alterations and vascular calcification-associated factors in the aortic wall were evaluated.
Results:
No aortic calcification was observed in the control group although uremic rats developed severe vascular calcification. Fe loading suppressed vascular calcification in the uremic groups. Expressions of runt-related transcription factor 2 (Runx2), single-strand (ss)DNA and phosphate transporter (Pit)-1 were increased in the uremic rats compared to the control rats. In the uremic group, Fe administration did not show any effect on ssDNA expression, but reduced Runx2 and Pit-1 expressions.
Conclusion:
Fe suppressed the development of vascular calcification through the prevention of Pit-1 and vascular smooth muscle cell osteoblastic transdifferentiation.
