Hyperhomocysteinemia and cardiovascular risk in postmenopausal women: the role of folate supplementation

Retinol-binding protein 4 is associated with arterial stiffness in early postmenopausal women

OBJECTIVE

Recent evidence in postmenopausal women suggested lack of association between serum levels of retinol-binding protein 4 (RBP4) and subclinical atherosclerosis; however, associations with arterial stiffness in this population remain unexplored. We evaluated the association among RBP4 and cardiovascular risk factors, including homocysteine, a marker involved in retinoic acid synthesis, and indices of arterial stiffness, in a sample of apparently healthy postmenopausal women.

METHODS

This cross-sectional study included 123 healthy postmenopausal women, not on hormone therapy, antihypertensive, or hypolipidemic treatment and with a menopausal age 10 years or less. We performed biochemical/hormonal assessment and sonographic evaluation, including carotid-femoral pulse wave velocity (PWV) and carotid artery stiffness index (SI).

RESULTS

Univariate analysis showed that RBP4 values correlated with age, low-density lipoprotein-cholesterol and estradiol levels. There was a trend of association of SI and PWV with homocysteine and triglycerides. RBP4 differed according to PWV, using the median PWV value as cut-off (RBP4, PWV ≤8.1 vs >8.1 m/s: 10.09 ± 2.05 vs 10.85 ± 1.91 ng/mL, analysis of covariance P value 0.014 adjusted for age, menopausal age, estradiol, pulse pressure). Linear regression analysis showed that PWV was independently associated with RBP4, age, and pulse pressure, whereas SI was independently associated with RBP4. An increase of one standard deviation in RBP4 levels (2.54 ng/mL) was associated with an increase of 0.577 m/s in PWV.

CONCLUSIONS

RBP4 serum levels are associated with arterial stiffness, in a sample of healthy postmenopausal women. If this association is causative, serum RBP4 levels could serve as a marker of arterial stiffness. Prospective studies are required to investigate the significance of our findings. : Video Summary:http://links.lww.com/MENO/A621.

Compositional and functional features of the female premenopausal and postmenopausal gut microbiota

Endogenous estrogen deficiency accelerates many diseases in postmenopausal women, and gut microbes contribute to estrogen level modulation. However, the compositional alterations and influences of the gut microbiota in postmenopausal women remain uncertain. A metagenome-wide association study was performed to compare the gut microbiota of 24 premenopausal and 24 postmenopausal women. Firmicutes and Roseburia spp. are depleted, while Bacteroidetes and the toluene-producing genus Tolumonas are overrepresented in fecal samples from postmenopausal women. The pentose phosphate pathway is enriched in premenopausal women. Homocysteine synthesis-related processes are enriched in postmenopausal women. The gut microbiomes of premenopausal and postmenopausal women differ and produce different metabolites. The gut microbiome may be a therapeutic target to reduce risks and improve the quality of life in postmenopausal women.

(1)H NMR metabolic profiling analysis offers evaluation of Nilestriol treatment in ovariectomised rats

Nilestriol (NIL) has been applied to treat menopausal dysfunctions, yet its mechanism has remained unknown. To understand the relationship between the changes in homeostatic metabolites and ovarian oestrogen deficiency syndromes after NIL treatment, proton Nuclear Magnetic Resonance ((1)H NMR)-based metabonomic technologies were used to analyse a rat model of oestrogen deficiency. An orthogonal partial least-squares regression (OPLS) differentiation model was used on 12-week metabolic analyses of ovariectomised (OVX) rats treated or mock treated with NIL. Furthermore, data analysis using Chenomx software quantified results to identify the most significantly altered metabolite concentrations, allowing for metabolic explanations of the effects of NIL therapies. In this study, PLS results revealed that there are considerably distinct differences between treatment groups. Additionally, a total of 45 metabolites shown to have a high variation between groups were selected for target quantification. Using a one-way LSD ANOVA analysis, 32 metabolite concentrations were significantly altered in the OVX group. A total of 21 metabolites were altered significantly in the NIL-treatment group but later returned to normal. According to the OPLS VIP calculation, the metabolites most affected by NIL treatment were mostly involved in insulin resistance. In addition, abnormal concentration changes in lactate in the NIL-treatment group and 3-indoxylsulfate in the OVX group were observed. To our knowledge, this study is the first to address the molecular mechanism of NIL from a metabonomic perspective, and, more specifically, to establish a catalogue of endo-molecular changes effected by NIL in the regulation of oestrogen deficiency disorder.

Homocysteine induces serum amyloid A3 in osteoblasts via unlocking RGD-motifs in collagen

Hyperhomocysteinemia is a risk factor for osteoporotic fractures. Homocysteine (Hcys) inhibits collagen cross-linking and consequently decreases bone extracellular matrix (ECM) quality. Serum amyloid A (A-SAA), an acute-phase protein family, plays an important role in chronic and inflammatory diseases and up-regulates MMP13, which plays an important role in bone development and remodeling. Here, we investigate the effect of Hcys on expression of SAA3, a member of the A-SAA gene family, in osteoblasts characterizing underlying mechanisms and possible consequences on bone metabolism. MC3T3-E1 osteoblast-like cells were cultured up to 21 d with Hcys (low millimolar range) or reseeded onto ECM resulting from untreated or Hcys-treated MC3T3-E1 cells. Fourier-transformed infrared spectroscopy and a discriminative antibody were used to characterize the resulting ECM. Gene expression and signaling pathways were analyzed by gene chip, quantitative RT-PCR, and immunoblotting. Transcriptional regulation of Saa3 was studied by promoter transfection assays, chromatin immunoprecipitation, and immunofluorescence microscopy. Hcys treatment resulted in reduced collagen cross-linking, uncovering of RGD-motifs, and activation of the PTK2-PXN-CTNNB1 pathway followed by RELA activation. These signaling events led to increased SAA3 expression followed by the production of MMP13 and several chemokines, including Ccl5, Ccl2, Cxcl10, and Il6. Our data suggest Saa3 as link between hyperhomocysteinemia and development of osteoporosis.