Changes of plasma concentration of osteoprotegerin and its association with endothelial dysfunction before and after hypouricemic therapy in patients with hyperuricemia

Serum Osteoprotegerin Levels and the Vascular Reactivity Index in Patients with Hypertension

Background and Objectives: Osteoprotegerin (OPG), a soluble glycoprotein found in serum, has been associated with both the presence and severity of atherosclerosis. OPG is regarded as the mediator in the process of vascular endothelial dysfunction. Impaired endothelial function has an intimate link with hypertension (HTN) and is associated with significant morbidity and mortality. This study was to investigate the connection between OPG and endothelial dysfunction in patients having HTN. Materials and Methods: There are 102 patients with HTN included. For the purpose of determining the levels of OPG, a commercial enzyme-linked immunosorbent test kit was applied. The vascular reactivity index (VRI), which is assessed via the digital thermal monitoring, provides information on endothelial function. Results: Ten patients with HTN (9.8%) were classified as having poor vascular reactivity (VRI < 1.0), 46 HTN patients (45.1%) as having intermediate vascular reactivity (1.0 ≤ VRI < 2.0), and 46 HTN patients (45.1%) were classified as having high vascular reactivity (VRI ≥ 2.0). A greater serum OPG level (p < 0.001) and older age (p = 0.022) were linked to impaired vascular reactivity. The estimated glomerular filtration rate (r = 0.196, p = 0.048) was positively correlated with VRI values in hypertensive participants, while advanced age (r = -0.222, p = 0.025) and the log-transformed OPG level (log-OPG, r = -0.357, p < 0.001) were negatively correlated with VRI. Serum log-OPG level was shown to be strongly and independently correlated with VRI values in HTN individuals after multivariable forward stepwise linear regression analysis (β = -0.357, adjusted R2 change = 0.119, p < 0.001). Conclusions: In patients with HTN, serum OPG levels were adversely correlated with VRI and probably had a role in endothelial dysfunction.

The impact of cholecalciferol on markers of vascular calcification in hemodialysis patients: A randomized placebo controlled study

BACKGROUND AND AIM

Vascular calcification is an independent risk factor for cardiovascular diseases and all-cause mortality in end stage renal disease, and particularly in hemodialysis patients. Vitamin D deficiency has been shown to be associated with vascular calcification among this category of patients. Cholecalciferol or vitamin D3; the native inactivated 25-hydroxy vitamin D [25(OH)D], has been proposed to have a good impact on vascular calcification and vitamin D deficiency. However, clinical data is still limited.

METHODS AND RESULTS

A prospective, randomized, placebo-controlled study was carried out to evaluate the effect of oral cholecalciferol on vascular calcification and 25(OH)D levels in hemodialysis patients. A total of sixty eligible hemodialysis patients were randomly assigned to either a treatment group (Oral 200.000IU Cholecalciferol per month) or a placebo group, for 3 months. Serum 25-hydroxy vitamin D (25(OH)D), fetuin-A, fibroblast growth factor (FGF-23), osteoprotegerin (OPG), calcium, phosphorus, their product (CaXP) and intact parathyroid hormone (iPTH) levels, were all assessed at baseline and at the end of the study. ClinicalTrials.gov registration number: NCT03602430. Cholecalciferol significantly increased serum levels of 25(OH)D and fetuin-A in the treatment group (p-value < 0.001), while no significant difference was observed in the placebo group. Cholecalciferol administration showed no effect on either FGF-23 or OPG. None of the treatment group patients experienced any adverse effects.

CONCLUSION

Cholecalciferol was shown to be an effective, tolerable, inexpensive pharmacotherapeutic option to overcome vitamin D deficiency, with a possible modulating effect on fetuin-A, among hemodialysis patients. CLINICALTRIALS.

GOV REGISTRATION NUMBER

NCT03602430.

Positive association between serum uric acid and bone mineral density in Chinese type 2 diabetes mellitus stratified by gender and BMI

Accumulating evidence has demonstrated that serum uric acid (UA), a natural powerful antioxidant, plays a beneficial role in bone health in the general population. However, few reports are available on the association between serum UA and bone in patients with type 2 diabetes mellitus (T2DM). We therefore investigated whether the benefit of serum UA for bone health was still present in those patients. 626 males and 609 postmenopausal females with T2DM were enrolled in this cross-sectional study. Serum UA concentrations and bone mineral density (BMD) measured at lumbar spine, femoral neck and total hip by dual-energy X-ray absorptiometry were obtained from all subjects. Meanwhile, data on osteoporosis prevalence, glucose metabolism, bone turnover markers and other serum biochemical indexes were collected. After adjustment for potential confounders, the results suggested that serum UA was positively associated with BMD in patients with normal weight, but this positive association varied by gender and skeletal sites in overweight T2DM patients [body mass index (BMI) ≥ 25 kg/m²]. Moreover, significantly lower odds ratios (ORs) for osteoporosis were found in postmenopausal patients with the highest UA tertile and male patients with medium UA tertile [adjusted OR 0.315, 95% confidence interval (CI) 0.170-0.581 for postmenopausal patients; adjusted OR 0.464, 95% CI 0.225-0.955 for male patients]. The positive association between serum UA and BMD found in Chinese T2DM patients may imply that relatively high UA is a protective factor for bone in these patients. Large intervention studies are needed to further confirm the outcomes and provide possible explanations.

Intravascular haemolysis in severe Plasmodium knowlesi malaria: association with endothelial activation, microvascular dysfunction, and acute kidney injury

Plasmodium knowlesi occurs throughout Southeast Asia, and is the most common cause of human malaria in Malaysia. Severe disease in humans is characterised by high parasite biomass, reduced red blood cell deformability, endothelial activation and microvascular dysfunction. However, the roles of intravascular haemolysis and nitric oxide (NO)-dependent endothelial dysfunction, important features of severe falciparum malaria, have not been evaluated, nor their role in acute kidney injury (AKI). In hospitalised Malaysian adults with severe (n = 48) and non-severe (n = 154) knowlesi malaria, and in healthy controls (n = 50), we measured cell-free haemoglobin (CFHb) and assessed associations with the endothelial Weibel–Palade body (WPB) constituents, angiopoietin-2 and osteoprotegerin, endothelial and microvascular function, and other markers of disease severity. CFHb was increased in knowlesi malaria in proportion to disease severity, and to a greater extent than previously reported in severe falciparum malaria patients from the same study cohort. In knowlesi malaria, CFHb was associated with parasitaemia, and independently associated with angiopoietin-2 and osteoprotegerin. As with angiopoietin-2, osteoprotegerin was increased in proportion to disease severity, and independently associated with severity markers including creatinine, lactate, interleukin-6, endothelial cell adhesion molecules ICAM-1 and E-selectin, and impaired microvascular reactivity. Osteoprotegerin was also independently associated with NO-dependent endothelial dysfunction. AKI was found in 88% of those with severe knowlesi malaria. Angiopoietin-2 and osteoprotegerin were both independent risk factors for acute kidney injury. Our findings suggest that haemolysis-mediated endothelial activation and release of WPB constituents is likely a key contributor to end-organ dysfunction, including AKI, in severe knowlesi malaria.

Low vaspin levels are related to endothelial dysfunction in patients with ankylosing spondylitis

Vaspin is a novel adipocytokine associated with glucose tolerance and chronic inflammation. Some studies reveal that vaspin may be involved in cardiovascular diseases. Our objective was to investigate the relationship between serum vaspin levels and endothelial function in patients with ankylosing spondylitis. One hundred and twenty patients with newly diagnosed ankylosing spondylitis and 100 healthy subjects were studied. Serum vaspin levels were measured with enzyme-linked immunosorbent assay. High resolution ultrasound was used to measure brachial artery diameter at rest, after reactive hyperemia (flow-mediated dilation, FMD) and after sublingual glyceryltrinitrate. Serum vaspin level in patients was 1.92±1.03 ng/mL, which was significantly lower than that in healthy subjects (2.88±0.81 ng/mL). By dividing the distribution of serum vaspin levels into quartiles, FMD levels increased gradually with the increase of serum vaspin levels in patients (P<0.01). Univariate analysis showed a correlation between vaspin and FMD (r=0.73, P=0.003), low-density lipoprotein cholesterol (r=-0.45, P=0.033), high-density lipoprotein cholesterol (r=0.63, P=0.025), fasting blood glucose (r=-0.79, P=0.006), triglycerides (TG) (r=-0.68, P=0.036), systolic blood pressure (r=-0.35, P=0.021), C-reactive protein (r=-0.67, P=0.011), homeostatic model assessment of insulin resistance (HOMA-IR) (r=-0.77, P=0.023) and erythrocyte sedimentation rate (r=-0.88, P=0.039) in patients. Multivariate analysis indicated that serum vaspin levels were independently associated with FMD, HOMA-IR and TG in patients. Our study found that serum vaspin levels were decreased in patients with ankylosing spondylitis and were associated with FMD levels. Vaspin may serve as an independent marker for detecting early stage atherosclerosis in patients with ankylosing spondylitis.

Serum Osteoprotegerin Is a Potential Biomarker of Insulin Resistance in Chinese Postmenopausal Women with Prediabetes and Type 2 Diabetes

The aim of this study is to investigate the circulating OPG levels in postmenopausal women with diabetes and prediabetes and explore the relationships between serum OPG and insulin resistance. A total of 271 unrelated Chinese postmenopausal women were recruited in this study. The subjects were divided into type 2 diabetes mellitus (T2DM) group (n = 93), impaired glucose regulation (IGR) (n = 90), and normal glucose regulation group (NGR) (n = 88), according to different glucose regulation categories. Serum OPG levels were measured by enzyme-linked immunosorbent assay. The serum OPG concentration in NGR group, 151.00 ± 45.72 pg/mL, was significantly lower than that in IGR group (169.28 ± 64.91 pg/mL) (p = 0.031) and T2DM group (183.20 ± 56.53 pg/mL) (p < 0.01), respectively. In multiple linear regression analysis, HOMA-IR, age, 2hPG, AST, ALP, and eGFR were found to be independent predictors of OPG. Increased serum OPG levels (OR = 1.009, p = 0.006) may be a risk factor for insulin resistance. The present study suggests that OPG might be implicated in the pathogenesis of diabetes and is a potential biomarker of insulin resistance in subjects with diabetes and prediabetes.

Endothelial Dysfunction in Rheumatoid Arthritis: Mechanistic Insights and Correlation with Circulating Markers of Systemic Inflammation

Objectives

To determine mechanisms involved in endothelial dysfunction (ED) during the course of arthritis and to investigate the link between cytokines, chemokines and osteoprotegerin.

Approach and Results

Experiments were conducted on aortic rings at day 4 (preclinical), day 11 (onset of disease), day 33 (acute disease) and day 90 (chronic disease) after adjuvant-induced arthritis (AIA) in Lewis rats. At day 4, the unique vascular abnormality was a reduced norepinephrine-induced constriction. At day 11, endothelial function assessed by the relaxation to acetylcholine was normal despite increased cyclo-oxygenase-2 activity (COX-2) and overproduction of superoxide anions that was compensated by increased nitric oxide synthase (NOS) activity. At day 33, ED apparition coincides with the normalization of NOS activity. At day 90, ED was only observed in rats with a persisting imbalance between endothelial NOS and COX-2 pathways and higher plasma levels of IL-1β and TNFα. Plasma levels of IL-1β, TNFα and MIP-1α negatively correlated with Ach-induced relaxation throughout the course of AIA.

Conclusions

Our data identified increased endothelial NOS activity as an important compensatory response that opposes the ED in the early arthritis. Thereafter, a cross-talk between endothelial COX-2/NOS pathways appears as an important element for the occurrence of ED. Our results encourage determining the clinical value of IL-1β, TNFα and MIP-1α as biomarkers of ED in RA.