Undercarboxylated osteocalcin has no adverse effect on endothelial function in rabbit aorta or human vascular cells

Circulating Osteocalcin Fractions are Associated with Vascular Calcification and Mortality in Chronic Hemodialysis Patients

BACKGROUND

Vascular calcification, a component of chronic kidney disease-mineral and bone disorder (CKD-MBD), is prevalent in patients with end-stage kidney disease (ESKD) and contributes to high mortality. However, the association between the blood level of total osteocalcin (OC) and vascular calcification and mortality remains inconclusive. We, therefore, investigated whether different OC fractions can serve as biomarkers of vascular calcification and mortality in the ESKD population.

METHODS

This observational cohort study enrolled patients on maintenance hemodialysis. Plasma carboxylated OC (cOC), uncarboxylated OC (ucOC), and intact parathyroid hormone (PTH) were measured. The percentage of carboxylated OC (%cOC) was calculated as dividing cOC by total OC. The vascular calcification severity was defined by an aortic calcification grade. The patients were followed for three years and one month.

RESULTS

A total of 184 patients were enrolled. In the multivariable logistic regression, plasma %cOC, but not cOC or ucOC, was independently associated with the severity of vascular calcification (OR 1.019, p = 0.036). A significant U-shaped correlation was found between plasma %cOC and PTH (p = 0.002). In the multivariable Cox regression, patients with higher plasma %cOC had a higher risk of mortality (quartiles Q4 versus Q1-Q3, HR 1.991 [95% CI: 1.036-3.824], p = 0.039).

CONCLUSIONS

In patients undergoing chronic hemodialysis, plasma %cOC positively correlated with vascular calcification and exhibited a U-shaped correlation with PTH. Furthermore, a higher plasma %cOC was associated with increased mortality. These findings suggest that plasma %cOC may serve as a biomarker for CKD-MBD and a predictor of clinical outcomes in chronic hemodialysis patients.

Vitamin C modulates adrenaline-augmented gastric injury via cardiac troponin/creatine kinase pathway in Wistar rats

Objectives

Vitamin C has anti-oxidant benefits in the gastrointestinal tract and heart. This study investigated the effect of vitamin C on some gastric parameters in myocardial injury in rats.

Materials and Methods

Thirty Wistar rats were divided into five groups (n = 6). Group 1 was the control and Group 2 (ADR) received 1 mg/kg of adrenaline subcutaneously on days 13 and 14. Group 3 received vitamin C (200 mg/kg) orally for 14 days. Group 4 received adrenaline (1 mg/kg) on days 1 and 2 and vitamin C from days 1 to 14. Group 5 received vitamin C till day 14 and adrenaline on days 13 and 14. All animals were sacrificed after 2 hr of pyloric ligation. Gastric secretion parameters were assessed while a blood sample was obtained for biochemical analysis.

Results

Gastric juice volume, total gastric acidity, pepsin activity, cardiac troponin 1, creatine kinase-MB, and lactate dehydrogenase levels increased (P<0.05) in ADR only group relative to the control. Pre- and post-vitamin C treatment reduced (P<0.05) these markers to near normal. However, treatment with vitamin C reduced (P<0.05) ulcer score, and increased (P<0.05) pepsin activity, mucus weight, and serum vitamin C levels when compared with the ADR-only group. Pre-treatment with vitamin C resulted in a marked decrease (P<0.05) in gastric juice volume, pepsin activity, and total gastric acidity compared with post-treatment in the adrenaline-induced injury group.

Conclusion

Vitamin C pretreatment reduces excessive gastric secretions, ulcer scores, and attenuates cardio-inflammatory responses in adrenaline-augmented myocardial injury in rats.

Male subclinical hypogonadism and late-onset hypergonadotrophic hypogonadism: mechanisms, endothelial function, and interplay between reproductive hormones, undercarboxylated osteocalcin, and endothelial dysfunction

BACKGROUND

Pathogenesis and endothelial function in subclinical hypogonadism (SCH) remain unclear. Undercarboxylated osteocalcin (ucOC) participates in atherosclerosis and reproduction. We explored the underlying mechanisms and interplay of endothelial dysfunction, unOC and reproductive hormones in SCH and primary late-onset hypogonadism (LOH).

METHODS

In the SCH, LOH, and healthy eugonadal male groups, we measured serum unOC, calculated luteinizing hormone/testosterone (LH/T), LH.T product, and estradiol/T (E/T) as indicators of impaired Leydig cells, androgen sensitivity index (ASI), and aromatase activity, respectively (LH set-point regulators), and assessed flow-mediated dilation of the brachial artery (FMD%), carotid-intima media thickness (CIMT), and aortic stiffness (AS).

RESULTS

↑LH/T, ↑ASI, ↓aromatase activity, normal T, follicle-stimulating hormone (FSH) and sex hormone-binding globulin (SHBG) levels, ↑unOC, and enhanced atherosclerotic markers (↓FMD%, ↑CIMT, ↑AS) are characteristics of SCH. Testosterone was positively correlated with FMD% in SCH. The independent predictors were: SHBG and LH for FMD% and CIMT, respectively, and LH/T, ucOC, FSH, estradiol, and E/T ratio for AS in the LOH group; and LH for FMD% & AS and LH and LH/T for CIMT in all study subjects.

CONCLUSIONS

SCH is a distinct clinical entity characterized by impaired androgen sensitivity and aromatase activity, compensatory elevated unOC, endothelial dysfunction, and anti-atherogenic role of testosterone.

Osteocalcin association with vascular function in chronic kidney disease

Osteocalcin (OCN) is a bone‐derived and vitamin K dependent hormone that affects energy metabolism and vascular calcification. The relationship between serum OCN and vascular function in patients with chronic kidney disease (CKD) is uncertain. This study investigated the association between serum OCN and vascular function as expressed with reactive hyperemia index (RHI) and augmentation index (AIx) measured by Endo‐PAT 2000 device. This cross‐sectional analysis was based on 256 pre‐dialysis CKD patients who had completed the Endo‐PAT 2000 test and serum OCN at the First Center of Chinese PLA Hospital from November 2017 to December 2019. Based on whether the RHI was less than 1.67, the patients were divided into endothelial dysfunction and normal endothelial function groups. Multiple logistic and linear regression were used to analyze the association between OCN and vascular function. Subgroup analyses were performed to examine the effects of OCN on vascular function in different CKD populations. After multivariate adjustment, CKD with low OCN were more likely to have endothelial dysfunction (OR: 0.794; 95%CI: 0.674‐0.934; P = .006); on the contrary, patients with high OCN had a higher degree of arterial stiffness (standardized β: 0.174; P = .003). Subgroup analyses showed that higher OCN was associated with severe arterial stiffness but a better endothelial function in young (age < 65 years, P_RHI/P_AIx@75 = .027/.011), male (P_RHI/P_AIx@75 = .040/.016), patients with a history of hypertension (P_RHI/P_AIx@75 = .004/.009) or diabetes (P_RHI/P_AIx@75 = .005/.005), and in early CKD (P_RHI/P_AIx@75 = .014/.015). In conclusion, serum OCN correlates with vascular function in CKD patients: beneficial for endothelial function but detrimental to arterial stiffness.

Osteocalcin-expressing endothelial progenitor cells and serum osteocalcin forms are independent biomarkers of coronary atherosclerotic disease severity in male and female patients

PURPOSE

Osteocalcin (OC), an osteoblast-derived regulator of metabolic processes, and circulating early endothelial progenitor cells (EPC, CD34 - /CD133 + /KDR +) expressing OC (OC +) are potential candidates linking bone metabolism and the vasculature and might be involved in vascular atherosclerotic calcification. This study aimed at assessing the association of circulating levels of different OC forms and of EPCs count with disease severity in patients with documented coronary atherosclerosis (CAD).

METHODS

Patients (n = 59) undergoing coronary angiography were divided, according to stenosis severity, into (1) early coronary atherosclerosis (ECA) (n = 22), and (2) late coronary atherosclerosis (LCA) (n = 37). Total OC (TOC), carboxylated OC (cOC), undercarboxylated OC (unOC) were quantified by ELISA. EPC OC + count was assessed by flow cytometry.

RESULTS

EPC OC + counts showed significant differences between ECA and LCA groups. unOC and unOC/TOC ratio were inversely correlated with EPC OC + count. A significant decrease in TOC and unOC plasma levels was associated with higher cardiovascular risk factors (CVRFs) number. EPC OC + count was correlated with LDL-C, total cholesterol, and triglycerides, with a greater significance in the LCA group. No association between the different forms of circulating OC (TOC, ucOC, cOC) and severity of CAD was found.

CONCLUSION

This study showed a significant association between EPCs (CD34 - /CD133 + /KDR + /OC +), CAD severity and CVRFs, suggesting an active role for EPC OC + in the development of CAD. An inverse correlation between TOC, ucOC, and number of CVRFs was observed, suggesting that OC, regardless of its carboxylation status, may be developed as a further cardiovascular risk biomarker.

Antidepressant-like effect of rosmarinic acid during LPS-induced neuroinflammatory model: The potential role of cannabinoid receptors/PPAR-γ signaling pathway

Rosmarinic acid (RA), an ester of caffeic acid and 3, 4-dihydroxyphenyllactic acid, has anti-inflammatory and neuroprotective activities. Herein, this study investigated in silico the drug-likeness and the potential molecular targets to RA. Moreover, it tested the antidepressant-like potential of RA in the lipopolysaccharide (LPS)-induced depression model. RA (MW = 360.31 g/mol) meets the criteria of both Lipinski's rule of five and the Ghose filter. It also attends to relevant pharmacokinetic parameters. Target prediction analysis identified RA's potential targets and biological activities, including the peroxisome proliferator-activated receptor (PPAR) and the cannabinoid receptors CB1 and CB2 . In vivo, RA's acute, repetitive, and therapeutic administration showed antidepressant-like effect since it significantly reduced the immobility time in the tail suspension test and increased grooming time in the splash test. Further, the pretreatment with antagonists of CB1 , CB2 , and PPAR-γ receptors significantly blocked the antidepressant-like effect of RA. Altogether, our findings suggest that cannabinoid receptors/PPAR-γ signaling pathways are involved with the antidepressant-like effect of RA. Moreover, this molecule meets important physicochemical and pharmacokinetic parameters that favor its bioavailability. RA constitutes a promising, innovative, and safe molecule for the pharmacotherapy of major depressive disorder.

Osteocalcin and vascular function: is there a cross-talk?

Background

The bone-derived protein osteocalcin (OC), in its undercarboxylated (ucOC) form, has a beneficial effect on energy metabolism and may be a future therapeutic target for metabolic diseases. Increasing evidence suggests a link between ucOC and cardiovascular disease (CVD) development; however, the exact relationship is conflicting and unclear.

Scope of review

The aim of this review was to summarise the current research examining the interaction between OC and vascular dysfunction, the initiating stage in the development of atherosclerosis and CVD.

Major conclusions

In humans, the association between OC and vascular function is inconsistent. Several studies report that total OC (tOC) is associated with adverse function or beneficial function, whereas others report that tOC and ucOC has no effect on vascular function. The conflicting data are likely due to several methodological inconsistencies, in particular the lack of studies reporting circulating ucOC levels. In animal models, the direct administration of ucOC to isolated blood vessels ex vivo produced minimal changes in endothelial function, but importantly, no adverse responses. Finally, in human endothelial and vascular smooth muscle cells, ucOC treatment did not influence classical markers of cellular function, including endothelin-1, vascular adhesion molecule-1 and monocyte chemoattractant protein-1 after exposure to high glucose and inflammatory conditions. The lack of adverse effects in ex vivo and in vitro studies suggests that ucOC may be targeted as a future therapeutic for metabolic diseases, without the risk of detrimental effects in the vasculature. However, further studies are needed to confirm these findings and to investigate whether there is a direct beneficial influence of ucOC.

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ucOC is implicated in the regulation of glucose homeostasis; but its role in the vasculature has been minimally reported.

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Studies which examine the association between ucOC and vascular function in humans often report inconsistent outcomes.

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In addition, ex vivo and in vitro studies have reported that ucOC likely does not directly regulate endothelial function.

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ucOC may be targeted as a therapeutic treatment for metabolic diseases without a risk of adverse effects in the vasculature.

Undercarboxylated osteocalcin is associated with vascular function in female older adults but does not influence vascular function in male rabbit carotid artery ex vivo

Background

There are conflicting reports on the association of undercarboxylated osteocalcin (ucOC) in cardiovascular disease development, including endothelial function and hypertension. We tested whether ucOC is related to blood pressure and endothelial function in older adults, and if ucOC directly affects endothelial-mediated vasodilation in the carotid artery of rabbits.

Methods

In older adults, ucOC, blood pressure, pulse wave velocity (PWV) and brachial artery flow-mediated dilation (BAFMD) were measured (n = 38, 26 post-menopausal women and 12 men, mean age 73 ± 0.96). The vasoactivity of the carotid artery was assessed in male New Zealand White rabbits following a four-week normal or atherogenic diet using perfusion myography. An ucOC dose response curve (0.3–45 ng/ml) was generated following incubation of the arteries for 2-hours in either normal or high glucose conditions.

Results

ucOC levels were higher in normotensive older adults compared to those with stage 2 hypertension (p < 0.05), particularly in women (p < 0.01). In all participants, higher ucOC was associated with lower PWV (p < 0.05), but not BAFMD (p > 0.05). In rabbits, ucOC at any dose did not alter vasoactivity of the carotid artery, either following a normal or an atherogenic diet (p > 0.05).

Conclusion

Increased ucOC is associated with lower blood pressure and increased arterial stiffness, particularly in post-menopausal women. However, ucOC administration has no direct short-term effect on endothelial function in rabbit arteries. Future studies should explore whether treatment with ucOC, in vivo, has direct or indirect effects on blood vessel function.

Undercarboxylated osteocalcin has no adverse effect on endothelial function in rabbit aorta or human vascular cells

Undercarboxylated osteocalcin (ucOC) improves glucose metabolism; however, its effects on endothelial cell function are unclear. We examined the biological effect of ucOC on endothelial function in animal models ex vivo and human cells in vitro. Isometric tension and immunohistochemistry techniques were used on the aorta of male New Zealand white rabbits and cell culture techniques were used on human aortic endothelial cells (HAECs) to assess the effect of ucOC in normal and high-glucose environments. Overall, ucOC, both 10 and 30 ng/ml, did not significantly alter acetylcholine-induced blood vessel relaxation in rabbits (p > .05). UcOC treatment did not cause any significant changes in the immunoreactivity of cellular signalling markers (p > .05). In HAEC, ucOC did not change any of the assessed outcomes (p > .05). UcOC has no negative effects on endothelial function which is important to reduce the risks of off target adverse effects if it will be used as a therapeutic option for metabolic disease in the future.