Serum prohepcidin is associated with soluble transferrin receptor-1 but not ferritin in healthy post-menopausal women

Genetic influences on hand osteoarthritis in Finnish women--a replication study of candidate genes

Objectives

Our aims were to replicate some previously reported associations of single nucleotide polymorphisms (SNPs) in five genes (A2BP1, COG5, GDF5, HFE, ESR1) with hand osteoarthritis (OA), and to examine whether genes (BCAP29, DIO2, DUS4L, DVWA, HLA, PTGS2, PARD3B, TGFB1 and TRIB1) associated with OA at other joint sites were associated with hand OA among Finnish women.

Design

We examined the bilateral hand radiographs of 542 occupationally active Finnish female dentists and teachers aged 45 to 63 and classified them according to the presence of OA by using reference images. Data regarding finger joint pain and other risk factors were collected using a questionnaire. We defined two hand OA phenotypes: radiographic OA in at least three joints (ROA) and symptomatic DIP OA. The genotypes were determined by PCR-based methods. In statistical analysis, we used SNPStats software, the chi-square test and logistic regression.

Results

Of the SNPs, rs716508 in A2BP1 was associated with ROA (OR = 0.7, 95% CI 0.5–0.9) and rs1800470 in TGFB1 with symptomatic DIP OA (1.8, 1.2–2.9). We found an interaction between ESR1 (rs9340799) and occupation: teachers with the minor allele were at an increased risk of symptomatic DIP OA (2.8, 1.3–6.5). We saw no association among the dentists. We also found that the carriage of the COG5 rs3757713 C allele increased the risk of ROA only among women with the BCAP29 rs10953541 CC genotype (2.6; 1.1–6.1). There was also a suggestive interaction between the HFE rs179945 and the ESR1 rs9340799, and the carriage of the minor allele of either of these SNPs was associated with an increased risk of symptomatic DIP OA (2.1, 1.3–2.5).

Conclusions

Our results support the earlier findings of A2BP1 and TBGF1 being OA susceptibility genes and provide evidence of a possible gene-gene interaction in the genetic influence on hand OA predisposition.

Serum hepcidin measured with an improved ELISA correlates with parameters of iron metabolism in patients with myelodysplastic syndrome

Patients with myelodysplastic syndromes (MDS) often show elevated serum ferritin levels at diagnosis, probably caused by increased intestinal iron uptake attributable to ineffective erythropoiesis. Many patients also develop transfusional iron overload. Hepcidin, a pivotal regulator of iron homeostasis, controls iron uptake in the duodenum as well as iron release from macrophages and is potentially involved in iron distribution to different organs. We measured serum hepcidin, together with other laboratory parameters related to iron metabolism and hematopoiesis (ferritin, transferrin, transferrin saturation, soluble transferrin receptor, erythropoietin, and hemoglobin), and C-reactive protein as marker of inflammation, in 89 MDS patients. Hepcidin levels were measured with two different competitive ELISAs: (a) EIA-4705 as described by Schwarz et al. (J Gastroenterol 46:648-656; 2011) and (b) Hepcidin 25 bioactive ELISA (EIA-5258), which was develop by DRG Diagnostics, Marburg, in 2012. Median hepcidin levels with EIA-5258 were as follows: entire cohort 17.5 ng/ml (n = 89), RA/RARS 5.9 ng/ml (n = 5), RCMD 17.8 ng/ml (n = 38), RS-RCMD 8.7 ng/ml (n = 7), RAEB I/II 29.1 ng/ml (n = 22), CMML I/II 16.9 ng/ml (n = 10), and MDS with del(5q) 26.3 ng/ml (n = 7). Hepcidin levels of the RA/RARS patients were significantly lower than in the other groups except RS-RCMD. RS-RCMD had significantly lower levels than RAEB and 5q- patients. There was a positive correlation between hepcidin levels and serum ferritin and transferrin saturation, and a negative correlation between hepcidin and hemoglobin and transferrin. Malcovati et al. (Blood 112:2676a, 2008), Santini et al. (PLoS One 6:e23109, 2011), and Ambaglio et al. (Haematologica 98:420-423, 2013), using mass spectrometry, reported similar results. We further assessed transfusional status and could show that patients who had been transfused have significantly higher hepcidin levels (median 33.3 versus 8.8 ng/ml (p < 0.001)). A dichotomized hepcidin level correlated with worse survival. EIA-4705 as described by Schwarz showed no correlation with markers of iron metabolism. Measurement of serum hepcidin with an improved ELISA yield results that correlate with other parameters of iron metabolism as well as survival and transfusion needs.

Changes in iron measures over menopause and associations with insulin resistance

OBJECTIVES

No longitudinal studies have examined how iron measures change over menopause. Our objectives were to examine iron measures in individual women at premenopause and at postmenopause and, secondarily, to determine if any changes contributed to insulin resistance.

METHODS

In a subset of participants (n=70) in a longitudinal study of menopause, we measured ferritin, transferrin, and soluble transferrin receptor (sTfR) once in the premenopause and once in the postmenopause. We also examined associations between menopausal status and change in iron markers after adjustment for age at menopause, race/ethnicity, and waist circumference. In linear regression models, we examined associations between premenopause iron measures and changes in iron markers over menopause with homeostasis model assessment of insulin resistance (HOMA-IR) changes over menopause, before and after adjustment for age at menopause, race/ethnicity, changes in waist circumference, C-reactive protein (CRP), and sex hormone-binding globulin (SHBG) levels.

RESULTS

Women had lower ferritin (p<0.01), higher sTfR:ferritin levels (p<0.01), lower HOMA-IR (p=0.022), and lower glucose (p=0.05) in premenopause compared to postmenopause. After adjustment, lower premenopausal iron levels (sTfR:ferritin levels β=11.0, 95% confidence interval [CI] 0.017-22.0) and larger increases in iron over menopause (changes in sTfR:ferritin β=13.6, 95% CI 0.93-26.3) were associated with larger increases in HOMA-IR.

CONCLUSIONS

From premenopause to postmenopause, women on average have increases in measures of iron stores. Women who had the greatest changes in iron over menopause (lower measures of premenopausal iron and greater increases in iron measures over the menopause) had the strongest associations between changes in iron and changes in insulin resistance.

Hepcidin assay in serum by SELDI-TOF-MS and other approaches

Hepcidin, a liver peptide hormone, is the central regulator of iron homeostasis. Hepcidin synthesis is modulated by iron stores, so that iron repletion increases its levels to prevent pathological overload, while iron deficiency strongly inhibits hepcidin to allow an increase in iron absorption from duodenal cells. The emerging pivotal role of hepcidin in iron homeostasis, along with its important links with basic pathways like inflammation, makes the availability of an accurate hepcidin assay as a potentially powerful investigative tool to improve our understanding as well as our diagnostic/prognostic capabilities in many human diseases. There has been a great interest worldwide in developing a reliable and widely applicable assay of the hormone in biological fluids. Being optimal for low-molecular-weight biomarkers, SELDI-TOF-MS has emerged as a valid tool for hepcidin assay. Here we review recent results obtained with this technique, as well as with other Mass Spectrometry-based and immunological methods.

Hepcidin modulation in human diseases: from research to clinic

By modulating hepcidin production, an organism controls intestinal iron absorption, iron uptake and mobilization from stores to meet body iron need. In recent years there has been important advancement in our knowledge of hepcidin regulation that also has implications for understanding the physiopathology of some human disorders. Since the discovery of hepcidin and the demonstration of its pivotal role in iron homeostasis, there has been a substantial interest in developing a reliable assay of the hormone in biological fluids. Measurement of hepcidin in biological fluids can improve our understanding of iron diseases and be a useful tool for diagnosis and clinical management of these disorders. We reviewed the literature and our own research on hepcidin to give an updated status of the situation in this rapidly evolving field.