Association of plasma osteoprotegerin levels with stroke severity and functional outcome in acute ischaemic stroke patients

Prognostic effect of osteoprotegerin in patients with ischemic stroke: A systematic review and meta-analysis

BACKGROUND

Osteoprotegerin (OPG) is supposed to participate in the development of atherosclerosis and cardio-cerebrovascular disease. However, the results of research on relationship between OPG and ischemic stroke (IS) are controversial. Therefore, we carried out the first systematic review and meta-analysis to evaluate prognostic effect of osteoprotegerin in patients with IS.

METHODS

We comprehensively searched databases of PubMed, Embase, and the Cochrane Library through 21 August 2023 to identify observational studies that evaluated effect of OPG on poor functional outcome (modified Rankin Scale [mRS] Score of 3-6) and mortality in patients with IS. Adjusted odds ratios (aOR) with a 95% confidence interval (CI) of each included study were used as much as possible to assess the pooled effect.

RESULTS

Five studies that enrolled 4,506 patients in total fulfilled our inclusion criteria. Three studies were included in the pooled analysis for each endpoint since one of the included studies had provided data on poor functional outcome as well as mortality. OPG was neither associated with poor functional outcome (aOR 1.29, 95% CI 0.90-1.85) nor with mortality (aOR 1.57, 95% CI 0.90-2.74) in patients with IS.

CONCLUSIONS

There is insufficient evidence to demonstrate the correlation between OPG and mortality or poor functional outcome in IS patients. OPG cannot be applied to predict worse neurological function in IS patients based on the current evidence.

Genetics of ischemic stroke functional outcome

Ischemic stroke, which accounts for 87% of cerebrovascular accidents, is responsible for massive global burden both in terms of economic cost and personal hardship. Many stroke survivors face long-term disability-a phenotype associated with an increasing number of genetic variants. While clinical variables such as stroke severity greatly impact recovery, genetic polymorphisms linked to functional outcome may offer physicians a unique opportunity to deliver personalized care based on their patient's genetic makeup, leading to improved outcomes. A comprehensive catalogue of the variants at play is required for such an approach. In this review, we compile and describe the polymorphisms associated with outcome scores such as modified Rankin Scale and Barthel Index. Our search identified 74 known genetic polymorphisms spread across 48 features associated with various poststroke disability metrics. The known variants span diverse biological systems and are related to inflammation, vascular homeostasis, growth factors, metabolism, the p53 regulatory pathway, and mitochondrial variation. Understanding how these variants influence functional outcome may be helpful in maximizing poststroke recovery.

The RANK-RANKL-OPG System: A Multifaceted Regulator of Homeostasis, Immunity, and Cancer

The RANK-RANKL-OPG system is a complex signaling pathway that plays a critical role in bone metabolism, mammary epithelial cell development, immune function, and cancer. RANKL is a ligand that binds to RANK, a receptor expressed on osteoclasts, dendritic cells, T cells, and other cells. RANKL signaling promotes osteoclast differentiation and activation, which leads to bone resorption. OPG is a decoy receptor that binds to RANKL and inhibits its signaling. In cancer cells, RANKL expression is often increased, which can lead to increased bone resorption and the development of bone metastases. RANKL-neutralizing antibodies, such as denosumab, have been shown to be effective in the treatment of skeletal-related events, including osteoporosis or bone metastases, and cancer. This review will provide a comprehensive overview of the functions of the RANK-RANKL-OPG system in bone metabolism, mammary epithelial cells, immune function, and cancer, together with the potential therapeutic implications of the RANK-RANKL pathway for cancer management.

The association of plasma osteoprotegerin levels and functional outcomes post endovascular thrombectomy in acute ischemic stroke patients: a retrospective observational study

Background

Osteoprotegerin (OPG), also known as osteoclastogenesis inhibitory factor, is a tumor necrosis factor receptor superfamily component. There is an established relationship between OPG and cardiovascular disease. We hypothesized that plasma OPG levels are associated with functional outcomes in acute ischemic stroke patients who have undergone endovascular thrombectomy (EVT).

Methods

From April 2014 through December 2020, a total of 360 acute ischemic stroke patients who underwent EVT were prospectively included in this retrospective observational study. Plasma OPG was measured after fasting for 12 postoperative hours after EVT. A modified Rankin Scale (mRS) was used to assess functional outcomes 3 months after index stroke occurrence. Univariate and multivariate binary logistic regression and ordinal logistic regression analyses were performed to investigate the association of plasma OPG levels with poor functional outcomes.

Results

Overall, 145 (40.2%) patients had poor (mRS > 2) outcomes. The mean ± standard deviation plasma OPG level was 200.2 ± 74.4 pg/mL. Multivariate analysis after adjusting for sex, body mass index, and variables with p < 0.1 in the preceding univariate analysis revealed high plasma OPG levels were independently associated with poor functional outcomes (highest tertile vs. lowest tertile of OPG; odds ratios (OR) 2.121, 95% confidence interval (CI) [1.089-4.191], p = 0.037 in binary logistic regression, OR 2.102, 95% CI [1.301-3.412], p = 0.002 in ordinal logistic regression analysis).

Conclusions

This study demonstrated that higher plasma OPG levels were associated with poor functional outcomes in acute ischemic stroke patients who underwent EVT.

RANKL Impairs the TLR4 Pathway by Increasing TRAF6 and RANK Interaction in Macrophages

High serum levels of osteoprotegerin (OPG) are found in patients with obesity, type 2 diabetes, sepsis, or septic shock and are associated with a high mortality rate in stroke. The primary known function of OPG is to bind to the receptor activator of NF-κB ligand (RANKL), and by doing so, it inhibits the binding between RANKL and its receptor (RANK). TLR4 signaling in macrophages involves TRAF6 recruitment and contributes to low-grade chronic inflammation in adipose tissue. LPS is a classical activator of the TLR4 pathway and induces the expression of inflammatory cytokines in macrophages. We have previously observed that in the presence of RANKL, there is no LPS-induced activation of TLR4 in macrophages. In this study, we investigated the crosstalk between RANK and TLR4 pathways in macrophages stimulated with both RANKL and LPS to unveil the role of OPG in inflammatory processes. We found that RANKL inhibits TLR4 activation by binding to RANK, promoting the binding between TRAF6 and RANK, lowering TLR4 activation and the expression of proinflammatory mediators. Furthermore, high OPG levels aggravate inflammation by inhibiting RANKL. Our findings elect RANKL as a candidate for drug development as a way to mitigate the impact of obesity-induced inflammation in patients.

Plasma osteoprotegerin levels are associated with the presence and burden of cerebral small vessel disease in patients with acute ischemic stroke

BACKGROUND AND PURPOSE

Osteoprotegerin (OPG) is a component of the tumor necrosis factor receptor superfamily. Several studies have shown a relationship between OPG and cardiovascular diseases. We hypothesized that there is a relationship between plasma OPG levels and cerebral small vessel disease (SVD).

METHODS

Patients diagnosed with their first cerebral ischemic infarction between April 2014 and March 2017 were enrolled. All the enrolled patients were evaluated through the hospital stroke protocol, including routine blood tests, brain imaging, and measuring the plasma OPG levels. The presence and burden of cerebral SVD [cerebral microbleeds (CMBs), asymptomatic lacunar infarction (ALI), high-grade perivascular space (HPVS), high-grade white matter hyperintensity (HWMH)], and total SVD score were assessed through brain magnetic resonance imaging.

RESULTS

Of the 270 patients included in our study, 158 (58.5%) were men. The mean age of the patients was 63.8 ± 11.6 years. In multivariable analysis, plasma OPG levels were positively associated with the presence and burden of each cerebral SVD. The odds ratios (OR) of CMBs, ALI, HPVS, and HWMH for the association of OPG per standard deviation (SD) increase were 1.58 [95% confidence interval (CI), 1.09-2.27], 1.40 (95% CI, 1.04-1.88), 1.88 (95% CI, 1.27-2.78), and 1.47 (95% CI, 1.04-2.08), respectively. Plasma OPG levels were positively correlated with total SVD score (beta = 0.211, standard error = 0.061, p-value = 0.009, R² = 0.275).

CONCLUSIONS

Plasma OPG levels correlate with the presence and burden of cerebral SVD in patients with acute ischemic stroke.

Biomarkers Predictive of Long-Term Outcome After Ischemic Stroke: A Meta-Analysis

BACKGROUND AND PURPOSE

The goal of this study was to systematically review the utility of serum biomarkers in the setting of ischemic stroke (IS) to predict long-term outcome.

METHODS

A systematic literature review was performed using the PubMed and MEDLINE databases for studies published between 1986-2018. All studies assessing long-term functional outcome (defined as 30 days or greater) following IS with respect to serum biomarkers were included. Data were extracted and pooled using a meta-analysis of odds ratios.

RESULTS

Of the total 2928 articles in the original literature search, 183 studies were ultimately selected. A total of 127 serum biomarkers were included. Biomarkers were grouped into several categories: inflammatory (32), peptide/enzymatic (30), oxidative/metabolic (28), hormone/steroid based (23), and hematologic/vascular (14). The most commonly studied biomarkers in each category were found to be CRP, S100β, albumin, copeptin, and D-dimer. With the exception of S100β, all were found to be statistically associated with >30-day outcome after ischemic stroke.

CONCLUSIONS

Serum-based biomarkers have the potential to predict functional outcome in IS patients. This meta-analysis has identified CRP, albumin, copeptin, and D-dimer to be significantly associated with long-term outcome after IS. These biomarkers have the potential to serve as a platform for prognosticating stroke outcomes after 30 days. These serum biomarkers, some of which are routinely ordered, can be combined with imaging biomarkers and used in artificial intelligence algorithms to provide refined predictive outcomes after injury. Ultimately these tools will assist physicians in providing guidance to families with regards to long-term independence of patients.

The role of the RANKL/RANK/OPG system in the central nervous systems (CNS)

The receptor-activator of NF-κB ligand (RANKL) and its specific receptor RANK have essential roles in regulating bone metabolism and the immune system. Besides, the RANKL/RANK system plays important roles in multiple physiological and pathophysiological processes such as mammary gland development during pregnancy, cancer development, and bone metastasis. While it has long been known that RANKL and RANK are expressed in the central nervous system (CNS), the physiological roles of RANKL/RANK system in the CNS and the underlying molecular mechanisms have been elucidated recently. Over the last decade, several reports showed that the central RANKL/RANK system plays important roles in regulating body temperature, brain ischemia, autoimmune encephalopathy, feeding behavior, and energy metabolism. In this review, it is provided an updated information regarding the roles of RANKL/RANK system in the CNS.

Plasma Fibroblast Growth Factor 23 Concentration Is Associated with Intracranial Cerebral Atherosclerosis in Acute Ischemic Stroke Patients

BACKGROUND AND PURPOSE

Fibroblast growth factor 23 (FGF23) is associated with atherosclerosis via nitric-oxide-associated endothelial dysfunction and calcium-phosphate-related bone mineralization. This study aimed to determine the association of the plasma FGF23 concentration with intracranial cerebral atherosclerosis (ICAS) and extracranial cerebral atherosclerosis (ECAS).

METHODS

We prospectively enrolled 262 first-ever ischemic stroke patients in whom brain magnetic resonance was performed and a blood sample acquired within 24 h after admission. Plasma FGF23 concentrations were measured using an enzyme-linked immunosorbent assay. The presence of ICAS or ECAS was defined as a ≥50% decrease in arterial diameter in magnetic resonance angiography. The burden of cerebral atherosclerosis was calculated by adding the total number of vessels defined as ICAS or ECAS.

RESULTS

Our study population included 152 (58.0%) males. The mean age was 64.7 years, and the plasma FGF23 concentration was 347.5±549.6 pg/mL (mean±SD). ICAS only, ECAS only, and both ICAS and ECAS were present in 31.2% (n=82), 4.9% (n=13), and 6.8% (n=18) of the subjects, respectively. In multivariate binary and ordinal logistic analyses, after adjusting for sex, age, and variables for which p<0.1 in the univariate analysis, the plasma FGF23 concentration (per 100 pg/mL) was positively correlated with the presence of ICAS [odds ratio (OR)=1.07, 95% CI=1.00-1.15, p=0.039], burden of ICAS (OR=1.09, 95% CI=1.04-1.15, p=0.001), and burden of ECAS (OR=1.06, 95% CI=1.00-1.12, p=0.038), but it was not significantly related to the presence of ECAS (OR=1.05, 95% CI=0.99-1.12, p=0.073).

CONCLUSIONS

The plasma FGF23 may be a potential biomarker for cerebral atherosclerosis, particularly the presence and burden of ICAS in stroke patients.

Plasma Klotho concentration is associated with the presence, burden and progression of cerebral small vessel disease in patients with acute ischaemic stroke

Klotho is a soluble or membrane-bound anti-aging protein, whose protective actions are important for a prudential function of many organs. Because Klotho and cerebral small vessel disease (SVD) are associated with ageing process and endothelial dysfunction, it is possible that Klotho has an association with cerebral SVD. We aimed to investigate the association of plasma Klotho concentration with the presence, burden and progression of cerebral SVD. We prospectively enrolled 262 patients with first-ever acute cerebral infarction, performed brain MRI and collected their blood samples within 24 hours of admission. An enzyme-linked immunosorbent assay was used for evaluating plasma Klotho concentration. We estimated the total SVD score of each patient after determining the presence and burden of high-grade white matter hyperintensities (HWMHs), cerebral microbleeds (CMBs), high-grade perivascular spaces (HPVSs) and asymptomatic lacunar infarctions (ALIs). Univariate and multivariate analyses were conducted to investigate association of Klotho with cerebral SVD and the total SVD score. Of the 262 patients, 152 (58.0%) were men. The mean age of these patients was 64.7 years. The mean ± standard deviation of plasma Klotho concentration was 329.8 ± 194.1 pg/mL. In multivariate analysis, plasma Klotho concentration was negatively associated with the presence of HWMHs [Odds ratio (OR): 0.13, p = 0.047], HPVSs (OR: 0.22, p = 0.024) and ALIs (OR: 0.53, p = 0.021) but not associated with the presence of CMBs (OR: 0.39, p = 0.404). Plasma Klotho concentration was also negatively related to the total SVD score (unstandardized coefficients beta: −0.895, standard error = 0.317, p = 0.005, R² = 0.239). Furthermore, plasma Klotho concentration was negatively related to the presence (OR: 0.75, 95% CI: 0.59–0.96, p = 0.025) and severity of cerebral SVD progression (OR: 0.72, 95% CI: 0.56–0.92, p = 0.009). In conclusion, plasma Klotho concentration was negatively associated with the presence, burden and progression of cerebral SVD.

Plasma Osteoprotegerin Correlates with Stroke Severity and the Occurrence of Microembolic Signals in Patients with Acute Ischemic Stroke

Background

Instability of atherosclerotic plaques is associated with the occurrence of stroke. Microembolic signals (MESs) are an indicator of unstable plaque. A relationship between plasma osteoprotegerin (OPG) and ischemic stroke has already been identified. The aim of this study was to investigate whether plasma OPG levels have a relationship with MESs and to evaluate the feasibility of OPG as a biomarker of stroke severity and occurrence of MESs.

Methods

Our study consisted of 127 patients with large artery atherosclerosis stroke and 56 controls. Patients were classified into subgroups based on stroke severity and the occurrence of MESs. MES-monitoring was performed for 60 min using transcranial Doppler within 72 h of stroke onset. Stroke severity at admission was assessed by the National Institutes of Health Stroke Scale.

Results

Plasma OPG levels were significantly associated with stroke, MESs, and stroke severity at admission (adjusted OR [95% CI]: 1.002 [1.001–1.003] p < 0.001; 1.002 [1.001–1.003] p = 0.001; 1.001 [1.000–1.002] p = 0.028). When plasma OPG levels were used to determine the stroke severity, the area under the receiver-operating characteristic curve (AUC) was 0.734 (95% CI: 0.625-0.843) based on a cutoff value of 1998.44 pg/ml; the sensitivity and specificity of this test were 80.6% and 65.6%, respectively. Furthermore, when the levels of OPG were used to distinguish the presence of MESs, the AUC was 0.766 (95% CI: 0.672-0.860); the cutoff value was 2107.91 pg/ml. The sensitivity of this cutoff value was 68.8% and the specificity was 73.7%.

Conclusions

Plasma OPG levels correlate with stroke severity and the occurrence of MESs.

Plasma Klotho concentrations predict functional outcome at three months after acute ischemic stroke patients

Background: The Klotho protects the cardiovascular system by protecting against cell apoptosis, inhibiting the production of reactive oxygen species, and modulating inflammation. We aimed to investigate relationship of plasma Klotho concentrations with functional outcome at 3 months after acute cerebral infarction. Methods: We prospectively enrolled 262 first-ever acute cerebral infarction patients from whom a blood sample was acquired within 24 h of admission. An enzyme-linked immunosorbent assay was used for evaluating plasma Klotho concentration. Functional outcome on admission and three months was evaluated. Results: Of the 262 patients, 152 (58.0%) were men. The mean age of these patients was 64.7 years. The mean ± standard deviation of plasma Klotho concentrations was 312.7 ± 153.3 pg/mL. As opposed to patients with good outcome, plasma Klotho levels were lower in the poor outcome group (207.8 ± 96.2 vs. 342.5 ± 153.5 pg/mL, p = .001). In multivariate analysis, increased plasma Klotho concentrations were independently associated with good functional outcome (Odds ratio: 2.42, 95% confidence interval: 1.45-4.04, p < .001). Conclusions: Increased plasma Klotho concentrations were associated with good functional outcome in patients with acute ischemic stroke. We attribute these associations to the pleiotropic effects of Klotho in stroke and vascular diseases. Key message Increased plasma Klotho concentrations were associated with good functional outcome in patients with acute ischemic stroke.

[Osteoprotegerin is a new marker of cardiovascular diseases]

Osteoprotegerin (OPG) is a glycoprotein that is a representative of the tumor necrosis factor-α receptor superfamily. Information about the possible role of OPG in the development of cardiovascular diseases has begun to appear in the literature in recent years. This review discusses the role of increasing the level of OPG in the development and progression of atherosclerosis and as a consequence of coronary heart disease and chronic heart failure.

Alterations in bone turnover markers in patients with noncardio-embolic ischemic stroke

Background

The major cause of ischemic stroke is unstable or thrombogenic atherosclerotic plaques. Vascular calcification, a process that appears crucial for plaque stability, shares common features with bone formation. Many bone turnover proteins exhibit metabolic properties, but the evidence is conflicting regarding their possible involvement in vascular disease. Antibodies against sclerostin and dickkopf-1 are currently being evaluated as potential therapy for treating bone disorders. It is important to carefully assess the cardiovascular and metabolic effects of these proteins. The aim of the present study was to explore serum levels of bone turnover markers in patients with acute noncardio-embolic ischemic stroke in comparison with healthy controls.

Methods

In a cross-sectional study, we compared 48 patients aged ≥75 years with noncardio-embolic ischemic stroke and 46 healthy controls. Serum levels of dickkopf-1, sclerostin, osteoprotegerin, osteopontin and osteocalcin were determined by Luminex technique.

Results

We found clearly increased serum levels of osteoprotegerin, sclerostin, dickkopf-1 and osteopontin in patients with stroke compared with healthy controls. No difference was seen in serum levels of osteocalcin between the two groups.

Conclusion

Our findings strengthen the hypothesis of bone turnover markers being involved in vascular disease. Whether these proteins can be used as candidate markers for increased stroke risk or prognostic biomarkers remains to be further elucidated.

Interdependence between osteoprotegerin and active von Willebrand factor in long-term cardiovascular mortality prediction in patients undergoing percutaneous coronary intervention

The interdependence of the predictive accuracy of serum osteoprotegerin (OPG) and von Willebrand factor (vWF) levels for long-term cardiovascular outcomes has not been investigated so far. This was a prospective observational cohort study in 361 patients with coronary artery disease undergoing percutaneous coronary intervention (PCI). Baseline levels of OPG, vWF, active vWF (act vWF) and ristocetin cofactor activity (vWF:RICO) were measured. Cardiovascular mortality was recorded over a median of five years. OPG concentrations >3.7 µg/ml emerged as the strongest predictor of cardiovascular (CV) death: 30 % of patients died during the five-year follow-up in this group, as compared to 10 % in patients with OPG ≤3.7 µg/ml (p<0.001). Act vWF had a significant prognostic impact on CV mortality when OPG levels were low (≤3.7 µg/ml): patients with act vWF concentration >1 µg/ml died in 14 %, whereas those with act vWF values ≤1 µg/ml had a mortality rate of 1 % (p=0.015). We stratified patients into three groups: high OPG, low OPG/high act vWF and low OPG/low act vWF. Patients with high OPG values had a 13-fold higher risk for CV death than those with low OPG/low act vWF concentrations (adj. HR: 12.6; 95 %CI: 1.7–94.7; p=0.014), and a two-fold higher risk as compared to those patients with low OPG/high act vWF concentrations (adj. HR: 2.0; 95 %CI: 1.1–3.7; p=0.03) in the adjusted Cox regression analysis. In conclusion, elevated OPG at the time of PCI was a strong independent predictor of five-years cardiovascular mortality, whereas act vWF had a significant prognostic impact on CV mortality when OPG levels were low.

Prospective of ischemic stroke biomarkers

Methods currently used in brain vascular disorder diagnostics are neither fast enough nor clear-out; thus, there exists a necessity of finding new types of testing which could enlarge and complete the actual panel of diagnostics or be an alternative to current methods. The discovery of sensitive and specific biomarkers of ischemic brain stroke will improve the effects of treatment and will help to assess the progress or complications of the disease. The relevant diagnosis of ischemic stroke (IS) within the first 4.5 hours after the initial symptoms allows for the initiation of treatment with recombinant tissue plasminogen activators which limits the magnitude of negative changes in the brain and which enhance the final effectiveness of therapy. The potential biomarkers which are under investigation are substances involved in the processes of coagulation and fibrinolysis, and are of molecules released from damaged vascular endothelial cells and from nerves and cardiac tissue. The analyzed substances are typical of oxidative stress, apoptosis, excitotoxicity and damage of the blood brain barrier.

Values of vanillylmandelic acid and homovanillic acid in the urine as potential prognostic biomarkers in ischaemic stroke patients

BACKGROUND

Suitable biomarkers that have prognostic values are one of the key points of interest in ischaemic stroke. Increased sympathetic nervous system activity in ischaemic stroke causes multiple local and systemic effects that can be detrimental to the outcome. The mechanism of action is increased secretion and activity of catecholamines, whose end metabolic products are vanillylmandelic acid and homovanilic acid. Aim of our study was to determine whether these compounds can be used as potential prognostic biomarkers in ischaemic stroke, as a unique insight into the activity of the sympathetic nervous system.

METHODS

Urine samples of 96 patients with ischaemic stroke and transitory ischaemic attacks were analysed. Values of vanillylmandelic and homovanillic acids in urine were tested using liquid chromatography on the first and third day post-stroke. Severity of stroke was determined using the NIHSS scale, while functional outcome was determined using the Modified Rankin Scale.

RESULTS

Values of vanillylmandelic and homovanillic acids positively correlated with functional outcome of ischaemic stroke. Favorable outcomes correlated with decreased values, on contrary to increased values, which were associated with unfavourable outcomes.

CONCLUSION

Determining the values of these compounds in the urine is an easily available prognostic tool for the ischaemic stroke outcome, while also influencing potential therapeutic changes.

Relationships of OPG Genetic Polymorphisms with Susceptibility to Cardiovascular Disease: A Meta-Analysis

Background

The aim of this meta-analysis was to determine whether genetic polymorphisms in the osteoprotegerin (OPG) gene contribute to increased risk of cardiovascular disease (CVD).

Material/Methods

Electronic databases were searched carefully without any language restriction. Analyses of data were conducted using STATA software. Odds ratios (OR) and 95% confidence intervals (95%CI) were also calculated.

Results

Seven clinical case-control studies that enrolled 1170 CVD patients and 1194 healthy subjects were included. The results indicated that OPG gene polymorphism might be closely associated with susceptibility to CVD, especially for rs2073617 T>C and rs2073618 G>C polymorphisms. Ethnicity-stratified analysis indicated that genetic polymorphism in the OPG were closely related with the pathogenesis of CVD among Asians (all P<0.001), but no obvious relationship was found among Caucasians (all P>0.05).

Conclusions

Our meta-analysis provided quantitative evidence that OPG gene polymorphism may be closely related to an increased risk of CVD, especially for rs2073617 T>C and rs2073618 G>C polymorphisms.

Serum osteopontin levels are upregulated and predict disability after an ischaemic stroke

BACKGROUND

After an acute ischaemic stroke (AIS), several inflammatory biomarkers have been investigated, but their predictive role on functional recovery remains to be validated. Here, we investigated the prognostic relevance of biomarkers related to atherosclerotic plaque calcification, such as osteopontin (OPN), osteoprotegerin (OPG) and the receptor activator of nuclear factor kappa-B ligand (RANKL) in a cohort of patients with AIS (n = 90) during 90-day follow-up.

MATERIALS AND METHODS

Radiological and clinical examinations as well as blood sampling were performed at admission and at days 1, 7 and 90 from the event. Validated scores [such as modified Rankin scale (mRS) and the National Institutes of Health Stroke Scale (NIHSS)] were used to assess poststroke outcome. Serum levels of OPN, OPG and RANKL were measured by colorimetric enzyme-linked immunosorbent assay (ELISA).

RESULTS

When compared to the admission, OPN serum levels increased at day 7. Serum OPN levels at this time point were positively correlated with both ischaemic lesion volume and NIHSS at days 7 and 90. A cut-off of 30.53 ng/mL was identified for serum OPN by receiver operating characteristic (ROC) curve analysis. Adjusted logistic regression showed that serum OPN levels at day 7 predicted worse mRS at day 90 [OR 4.13 (95% CI 1.64-10.36); P = 0.002] and NIHSS [1.49 (95% CI 1.16-1.99); P = 0.007], independently of age, gender, hypertension and thrombolysis.

CONCLUSIONS

Serum levels of OPN, but not OPG and RANKL, peaked at day 7 after AIS and predicted worse neurological scores. Therefore, OPN might have a pathophysiological and clinical relevance after AIS.

Differential impact of unrecognised brain infarction on stroke outcome in non-valvular atrial fibrillation

There has been little information regarding the impact of unrecognised brain infarctions (UBIs) on stroke outcome in patients with non-valvular atrial fibrillation (NVAF). By using volumetric analysis of ischaemic lesions, we evaluated the potential impact of UBIs on clinical outcome according to their presence and categorised type. This study enrolled 631 patients with NVAF having no clinical stroke history. UBIs were categorised into three types as territorial, lacunar, or subcortical. We collected stroke severity, functional outcome at three months, and the total volume of UBIs and acute infarction lesions. We investigated the association between clinical outcome and the type or volume of UBI, using a linear mixed model and logistic regression analysis. UBIs were detected in 285 (45.2 %) patients; territorial UBIs were observed in 24.4 % of patients (154/631), lacunar UBIs in 25 % (158/631), and subcortical UBIs in 15.7 % (99/631). Although initial stroke severity was not different between patients with UBIs and those without, those with UBIs had less improvement during hospitalisation, leading to poorer outcome at three months. Among the three types of UBIs, only territorial UBIs were associated with poor outcome, especially in patients with relatively smaller acute infarction volume. UBIs, in particular, territorial UBIs, may be considered as predictors for poor outcome after ischaemic stroke in patients with NVAF. Our results suggest that the impact of UBIs on clinical outcome differs according to the type of UBIs and the acute stroke severity.

OPG/RANKL/RANK axis is a critical inflammatory signaling system in ischemic brain in mice

Osteoprotegerin (OPG) is a soluble secreted protein and a decoy receptor, which inhibits a receptor activator of nuclear factor κB (NF-κB) ligand (RANKL)/the receptor activator of NF-κB (RANK) signaling. Recent clinical studies have shown that a high-serum-OPG level is associated with unfavorable outcome in ischemic stroke, but it is unclear whether OPG is a culprit or an innocent bystander. Here we demonstrate that enhanced RANKL/RANK signaling in OPG(-/-) mice or recombinant RANKL-treated mice contributed to the reduction of infarct volume and brain edema via reduced postischemic inflammation. On the contrary, infarct volume was increased by reduced RANKL/RANK signaling in OPG(-/-) mice and WT mice treated with anti-RANKL neutralizing antibody. OPG, RANKL, and RANK mRNA were increased in the acute stage and were expressed in activated microglia and macrophages. Although enhanced RANKL/RANK signaling had no effects in glutamate, CoCl2, or H2O2-stimulated neuronal culture, enhanced RANKL/RANK signaling showed neuroprotective effects with reduced expression in inflammatory cytokines in LPS-stimulated neuron-glia mixed culture, suggesting that RANKL/RANK signaling can attenuate inflammation through a Toll-like receptor signaling pathway in microglia. Our findings propose that increased OPG could be a causal factor of reducing RANKL/RANK signaling and increasing postischemic inflammation. Thus, the OPG/RANKL/RANK axis plays critical roles in controlling inflammation in ischemic brains.

Association between osteoprotegerin gene polymorphisms and cardiovascular disease in type 2 diabetic patients

Osteoprotegerin (OPG) gene polymorphisms (T245G, T950C and G1181C) have been associated with osteoporosis and early predictors of cardiovascular disease. The aim of this study was to evaluate whether these polymorphisms contribute to cardiovascular disease (CVD) in type 2 diabetic patients. We performed a case-control study with 178 CVD subjects with diabetes and 312 diabetic patients without CVD to assess the impact of variants of the OPG gene on the risk of CVD. The OPG gene polymorphisms were analyzed by using the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). There was no significant association between the T245G and G1181C polymorphisms and CVD in the additive genetic model (OR = 0.96, 95% CI 0.64–1.45, p = 0.79; OR = 1.06, 95% CI 0.81–1.39, p = 0.65, respectively). However, the C allele of the T950C polymorphism was independently associated with a risk of CVD in type 2 diabetic patients in this genetic model (OR = 1.38, 95% CI 1.07–1.80, p = 0.01). This study provides evidence that the C allele of the T950C polymorphism is associated with increased risk of CVD in diabetic patients. However, well-designed prospective studies with a larger sample size are needed to validate these results.