MIF cytokine polymorphism linked to bone loss in elderly women
MedWire News: A variant haplotype of the cytokine macrophage migration inhibitory factor (MIF) gene is associated with an elevated rate of bone loss in elderly women, study results show.
"Our preliminary results suggest that combining information on MIF haplotype and bone turnover markers may provide additional useful information in the prediction of bone loss and fracture risk," say Kristina Åkesson (Malmö University Hospital, Sweden) and colleagues in the journal Bone.
MIF has been shown to be highly expressed in osteoblasts in mouse models of osteoporosis, and in humans, increased levels of MIF have been found in the joints of rheumatoid arthritis patients, explain the researchers.
To determine the association of polymorphisms in the gene with bone loss over a 5-year period, the researchers genotyped for MIF in 1002 postmenopausal women aged over 75 years.
They focused on the promoter polymorphisms MIF-CATT5-8 (a microsatellite repeat) and the single nucleotide polymorphism rs755622 (G/C) located at -794 and -173 bp, respectively.
The average rate of bone loss for individuals carrying the MIF-CATT7/ rs755622(C) haplotype (which represented 14.8% of all haplotypes) was 28% higher for the femoral neck, and 29% higher for the total hip, compared with the mean rate of bone loss for non-carriers of this haplotype.
In addition, carriers of the MIF-CATT7/rs755622(C) haplotype had higher levels of the bone turnover marker serum C-terminal cross-linking telopeptide of type I collagen (S-CTX-I).
"The consistency between the measurements of bone loss point in the same direction - that MIF-CATT7/rs755622(C) haplotype increases the extent of bone resorption, leading to bone loss in elderly women," Åkesson and colleagues comment.
The researchers note that several MIF inhibitors have been developed for inflammatory conditions, but add that "their potential clinical use in osteoporosis can currently only be speculated upon, and requires more knowledge on the biological function of MIF in relation to bone."
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By Andrew Czyzewski