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Effects of intermittent parathyroid hormone treatment on osteoprogenitor cells in postmenopausal women.

ABSTRACT: Intermittent parathyroid hormone (PTH) 1-34 treatment stimulates bone formation, but the molecular mechanisms mediating this effect have not been previously studied in humans. Thus, we used magnetic activated cell sorting to isolate hematopoietic lineage negative (lin-)/alkaline phosphatase positive (AP+) osteoprogenitor cells from bone marrow of 20 postmenopausal women treated with PTH (1-34) for 14 days and 19 control subjects. Serum PINP and CTX increased in PTH-treated subjects (by 97% and 30%, respectively, P<0.001). Bone marrow lin-/AP+ cells from PTH-treated subjects showed an increase in the RANKL/OPG mRNA ratio (by 7.5-fold, P=0.011) and in the mRNAs for c-fos (a known PTH-responsive gene, by 42%, P=0.035) and VEGF-C (by 57%, P=0.046). Gene Set Enrichment Analysis (GSEA, testing for changes in pre-specified pathways) demonstrated that PTH had no effect on osteoblast proliferation, apoptosis, or differentiation markers. However, PTH treatment resulted in a significant decrease (GSEA P-value, 0.005) in a panel of BMP target genes in the lin-/AP+ cells. Our findings thus identify several future directions for studying mechanisms of PTH action in humans. First, given the increasing evidence that PTH induces angiogenesis, the role of increased VEGF-C production by bone marrow osteoprogenitor cells in mediating this effect and the anabolic response to PTH warrants further study. Second, while the observed inhibition of BMP target gene expression by PTH is not consistent with the anabolic effects of PTH on bone and requires further validation, these data do generate the hypothesis that an inhibition of BMP signaling by PTH may, over time, limit the availability of mature osteoblasts on bone surfaces and thereby contribute to the observed waning of the anabolic response to PTH.

SUBMITTER: Drake MT

PROVIDER: S-EPMC3143310 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature

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Effects of intermittent parathyroid hormone treatment on osteoprogenitor cells in postmenopausal women.

Drake Matthew T MT Srinivasan Bhuma B Mödder Ulrike I UI Ng Alvin C AC Undale Anita H AH Roforth Matthew M MM Peterson James M JM McCready Louise K LK Riggs B Lawrence BL Khosla Sundeep S

Bone 20110511 3

Intermittent parathyroid hormone (PTH) 1-34 treatment stimulates bone formation, but the molecular mechanisms mediating this effect have not been previously studied in humans. Thus, we used magnetic activated cell sorting to isolate hematopoietic lineage negative (lin-)/alkaline phosphatase positive (AP+) osteoprogenitor cells from bone marrow of 20 postmenopausal women treated with PTH (1-34) for 14 days and 19 control subjects. Serum PINP and CTX increased in PTH-treated subjects (by 97% and 3 ...[more]

PMID: 21600325

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Project description:Title: Transcriptome analysis of human endometrial tissues from healthy post-menoupausal women reflecting the endometrial response to 3-weeks treatment with tibolone, E2 and E2+MPA. In an observational, open, non-randomized, controlled study uterine tissues were collected in order to generate endometrial gene expression profiles. healthy postmenopausal women were enrolled into the following treatment groups: Control-group; Tibolone-group, 2,5 mg of tibolone (administered orally) every day, starting 21 days prior to surgery; Estradiol-group, 2 mg of estradiol (administered orally) every day, starting 21 days prior to surgery; Estradiol+progestagen-group, 2 mg of estradiol (administered orally) and 5 mg of MPA (Medroxy Progesteroneacetate, administered orally) every day, starting 21 days prior to surgery. Pure (100%) endometrium was isolated from the snap-frozen uterine tissues and used for RNA isolation. RNA was labeled and hybridized to whole genome Affymetrix U133plus2 GeneChips containing 54,614 probe sets, representing approximately 47,000 transcripts. Relative to the control group, 940 genes are regulated in the endometrium of E2 treated patients, whereas only 198 genes are significantly regulated in endometria from tibolone or E2+MPA treated patients. Furthermore, only 9% of E2 regulated genes are also regulated by tibolone (85 out of 940), only 5% are also regulated by E2+MPA treatment and the overlap between tibolone and E2+MPA treatment is about 10%. This indicated that tibolone-treatment results in a weak endometrial profile similarity to E2 treatment and no profile similarity to E2+MPA treatment. A more detailed analysis showed that down stream processes, such as regulation of the cell cycle, angiogenesis and cell proliferation are almost not affected by tibolone treatment but, in contrast, are significantly affected by E2. For example, upon staining with Ki67, a marker for mitotic activity, significantly increased stromal as well as glandular cell proliferation was observed in the endometria from the E2-only treated group, while tibolone treatment resulted only in a slight increase in stromal cell proliferation (and no increase in glandular cell proliferation). These results indicate that in contrast to long-term tibolone use, short-term (21-days) use results in some estrogenic stimulation of the endometrium, which is clearly far less and rather different from what is observed during E2 treatment. References: Klaassens et al., 2006 Hanifi-Moghaddam et al., 2007 Verheul et al., 2007

Project description:Parathyroid hormone-related protein (PTHrP)(1-36) increases lumbar spine (LS) bone mineral density (BMD), acting as an anabolic agent when injected intermittently, but it has not been directly compared with parathyroid hormone (PTH)(1-34). We performed a 3-month randomized, prospective study in 105 postmenopausal women with low bone density or osteoporosis, comparing daily subcutaneous injections of PTHrP(1-36) to PTH(1-34). Thirty-five women were randomized to each of three groups: PTHrP(1-36) 400?µg/day; PTHrP(1-36) 600?µg/day; and PTH(1-34) 20?µg/day. The primary outcome measures were changes in amino-terminal telopeptides of procollagen 1 (PINP) and carboxy-terminal telopeptides of collagen 1 (CTX). Secondary measures included safety parameters, 1,25(OH)2 vitamin D, and BMD. The increase in bone resorption (CTX) by PTH(1-34) (92%) (p?<?0.005) was greater than for PTHrP(1-36) (30%) (p?<?0.05). PTH(1-34) also increased bone formation (PINP) (171%) (p?<?0.0005) more than either dose of PTHrP(1-36) (46% and 87%). The increase in PINP was earlier (day 15) and greater than the increase in CTX for all three groups. LS BMD increased equivalently in each group (p?<?0.05 for all). Total hip (TH) and femoral neck (FN) BMD increased equivalently in each group but were only significant for the two doses of PTHrP(1-36) (p?<?0.05) at the TH and for PTHrP(1-36) 400 (p?<?0.05) at the FN. PTHrP(1-36) 400 induced mild, transient (day 15) hypercalcemia. PTHrP(1-36) 600 required a dose reduction for hypercalcemia in three subjects. PTH(1-34) was not associated with hypercalcemia. Each peptide induced a marked biphasic increase in 1,25(OH)2 D. Adverse events (AE) were similar among the three groups. This study demonstrates that PTHrP(1-36) and PTH(1-34) cause similar increases in LS BMD. PTHrP(1-36) also increased hip BMD. PTH(1-34) induced greater changes in bone turnover than PTHrP(1-36). PTHrP(1-36) was associated with mild transient hypercalcemia. Longer-term studies using lower doses of PTHrP(1-36) are needed to define both the optimal dose and full clinical benefits of PTHrP. © 2013 American Society for Bone and Mineral Research.

Project description:BackgroundConcentrations of 25-hydroxyvitamin D [25(OH)D] tend to be lower in African Americans than in non-Hispanic whites, but whether adding information on parathyroid hormone (PTH) can help explain the higher cardiometabolic risk among African Americans is unknown.ObjectivesThis study examined race (black/white)-specific independent and joint associations of 25(OH)D and PTH with cardiometabolic biomarkers including high-sensitivity C-reactive protein (hs-CRP), estimated glomerular filtration rate (eGFR), and homeostasis model assessment of insulin resistance (HOMA-IR) and β-cell function (HOMA-B).MethodsAmong 1500 white and 1300 black postmenopausal women without cardiovascular disease from the Women's Health Initiative Observational Study, a weighted linear regression analysis and a novel penalized spline-based semiparametric model with contour plots, accounting for possible nonlinear relations and interactions simultaneously, were used to investigate the race-specific independent and joint associations of 25(OH)D and PTH with each biomarker.ResultsBlack women had lower concentrations of 25(OH)D and higher PTH, HOMA-IR, HOMA-B, hs-CRP, and eGFR than white women (all P values < 0.0001). Lower 25(OH)D and higher PTH were each independently and jointly associated with higher HOMA-IR in both white and black women, whereas a similar joint relation with HOMA-B was observed in white women only. In contrast, PTH was nonlinearly associated with HOMA-B in black women and positively associated with hs-CRP in white women, independently of 25(OH)D. Whereas there was an inverse linear relation between PTH and eGFR in white women after accounting for 25(OH)D, PTH and 25(OH)D were jointly and nonlinearly associated with eGFR in black women.ConclusionsWe found that the joint association of 25(OH)D and PTH with β-cell function, systemic inflammation, and kidney function apparently differed between white and black women. Further studies are needed to determine whether differences in the vitamin D-PTH endocrine system contribute to racial disparities in cardiovascular health.

Dataset Information

Effects of intermittent parathyroid hormone treatment on osteoprogenitor cells in postmenopausal women.

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Effects of intermittent parathyroid hormone treatment on osteoprogenitor cells in postmenopausal women.

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