Ferroportin mRNA is down-regulated in granulosa and cervical cells from infertile women.

OBJECTIVE: To explore the relationship between iron and infertility by investigating iron-related gene expression in granulosa and uterine cervical cells. DESIGN: Case-control study. SETTING: Two tertiary hospitals. PATIENT(S): Two independent cohorts of fertile (n = 18 and n = 17) and infertile (n = 31 and n = 35) women. INTERVENTION(S): In vitro fertilization. MAIN OUTCOME MEASURE(S): Gene expression levels of ferritin light chain (FTL), ferritin heavy chain (FTH), transferrin receptor (TFRC), and ferroportin (SLC40A1) mRNA were analyzed in granulosa and cervical cells. RESULT(S): In the first cohort, fertile and infertile women were similar in body mass index. Ferroportin mRNA levels were decreased in granulosa cells from infertile women in parallel with increased serum hepcidin levels. A positive association between ferroportin and TFRC mRNA, a gene associated with intracellular iron deficiency, was observed only in granulosa cells from fertile women. The major findings were replicated in a second independent cohort. CONCLUSION(S): Ferroportin mRNAs and circulating hepcidin identify a subset of infertile women and may constitute a target for therapy.

Iron and obesity status-associated insulin resistance influence circulating fibroblast-growth factor-23 concentrations.

Fibroblast growth factor 23 (FGF-23) is known to be produced by the bone and linked to metabolic risk. We aimed to explore circulating FGF-23 in association with fatness and insulin sensitivity, atherosclerosis and bone mineral density (BMD). Circulating intact FGF-23 (iFGF-23) and C-terminal (CtFGF-23) concentrations (ELISA) were measured in 133 middle aged men from the general population in association with insulin sensitivity (Cohort 1); and in association with fat mass and bone mineral density (DEXA) and atherosclerosis (intima media thickness, IMT) in 78 subjects (52 women) with a wide range of adiposity (Cohort 2). Circulating iFGF-23 was also measured before and after weight loss. In all subjects as a whole, serum intact and C-terminal concentrations were linearly and positively associated with BMI. In cohort 1, both serum iFGF-23 and CtFGF-23 concentrations increased with insulin resistance. Serum creatinine contributed to iFGF-23 variance, while serum ferritin and insulin sensitivity (but not BMI, age or serum creatinine) contributed to 17% of CtFGF-23 variance. In cohort 2, CtFGF-23 levels were higher in women vs. men, and increased with BMI, fat mass, fasting and post-load serum glucose, insulin, HOMA-IR and PTH, being negatively associated with circulating vitamin D and ferritin levels. The associations of CtFGF-23 with bone density in the radius, lumbar spine and carotid IMT were no longer significant after controlling for BMI. Weight loss led to decreased iFGF-23 concentrations. In summary, the associations of circulating FGF-23 concentration with parameters of glucose metabolism, bone density and atherosclerosis are dependent on iron and obesity status-associated insulin resistance.