The relation between body iron stores and adipose tissue function in patients with manifest vascular disease.

ABSTRACT

BACKGROUND: We investigated whether plasma ferritin levels through the pro-inflammatory effects of free iron are associated with adipose tissue dysfunction in a relevant population of patients with manifest vascular disease who would potentially benefit the most from further aetiological insights. MATERIALS AND METHODS: In a cohort of 355 patients with vascular diseases, the association between plasma ferritin and adiponectin levels was quantified using linear regression analysis. Interleukin-6 and adiponectin levels were measured in medium from pre-adipocytes and adipocytes after incubation with increasing concentrations of Fe(III)-citrate and after co-incubation with iron chelators or radical scavengers. RESULTS: Increasing ferritin plasma concentrations were not related to plasma adiponectin levels in patients without (ß -0·13; 95% CI -0·30 to 0·04) or with the metabolic syndrome (ß -0·04; 95% CI -0·17 to 0·10). Similar results were found in patients who developed a new cardiovascular event in the follow-up period. In vitro, incubation with increasing concentrations of Fe(III)-citrate-induced inflammation in pre-adipocyte cultures as witnessed by increased IL-6 secretion at 30 µm Fe(III)-citrate vs. control (500 ± 98 pg/mL vs. 194 ± 31 pg/mL, P = 0·03). Co-incubation of pre-adipocytes with iron chelators or radical scavengers prevented this inflammatory response. Incubation of adipocytes with 30 µm Fe(III)-citrate did not influence adiponectin secretion compared with control. CONCLUSIONS: In patients with vascular disease, there is no association between plasma ferritin and adiponectin levels. In vitro, free iron induces an inflammatory response in pre-adipocytes, but not in adipocytes. This response was blocked by co-incubation with iron chelators or radical scavengers. Adiponectin secretion by adipocytes was not influenced by free iron.