Increased Serum Netrin-1 Is Associated With Improved Prognosis of Ischemic Stroke

Insights from the neural guidance factor Netrin-1 into neurodegeneration and other diseases

Netrin-1 was initially discovered as a neuronal growth cue for axonal guidance, and its functions have later been identified in inflammation, tumorigenesis, neurodegeneration, and other disorders. We have recently found its alterations in the brains with Alzheimer's disease, which might provide important clues to the mechanisms of some unique pathologies. To provide better understanding of this promising molecule, we here summarize research progresses in genetics, pathology, biochemistry, cell biology and other studies of Netrin-1 about its mechanistic roles and biomarker potentials with an emphasis on clinical neurodegenerative disorders in order to expand understanding of this promising molecular player in human diseases.

Association of Chinese visceral adiposity index with clinical outcome in patients after endovascular thrombectomy

BACKGROUND AND PURPOSE

The Chinese Visceral Adiposity Index (CVAI) is a reliable indicator of visceral adiposity dysfunction in the Chinese population. We aimed to evaluate the association between CVAI and clinical outcome in Chinese ischemic stroke patients who received endovascular thrombectomy (EVT).

METHODS

This study retrospectively included patients with large vessel occlusive stroke receiving EVT treatment in 2 China stroke centers. Baseline CVAI was calculated after admission. Patients with a modified Rankin scale score ≥ 3 at 3 months after ischemic stroke were defined as poor outcome. Binary multivariate logistic regression models were utilized to explore the association between CVAI and the risk of 90-day unfavorable outcome.

RESULTS

A total of 453 patients (mean age, 70.4  ± 12.1 years; 280 male) were included. During the 90-day follow-up, 236 (52.1 %) patients experienced poor outcome. After multivariable adjustment for potential confounders, increasing CVAI was associated with an increased risk of 90-day poor outcome (odds ratios, per-standard deviation increase: 1.521; 95 % confidence interval, 1.127-2.052; P = 0.006). Similar significant results were observed when the CVAI was analyzed as a categorical variable. Furthermore, the multiple-adjusted spline regression model showed an inverted J-shape association between CVAI and risk of unfavorable outcome (P = 0.048 for non-linearity).

CONCLUSIONS

This study demonstrated that CVAI is positively correlated with 90-day poor outcome in Chinese ischemic stroke patients after EVT.

Netrin-1 and RGMa: Novel Regulators of Atherosclerosis-Related Diseases

BACKGROUNDS

Neuronal guidance proteins (NGPs) have been demonstrated to guide the elongation of neuronal axonal growth cones in the developing central nervous system. Non-neuronal functions of NGPs have also been described, especially in relation to atherosclerosis.

FINDINGS

Netrin-1 and repulsive guidance molecule a (RGMa) are NGPs that have been shown to regulate endothelial cell adhesion and angiogenesis, macrophage migration and apoptosis, smooth muscle cells (SMCs) phenotypic dedifferentiation and mobility, chemokine activities, and inflammatory responses during atherosclerosis initiation and progression.

PURPOSES

However, mechanistic studies have generated controversy about the specific role of Netrin-1 in atherosclerosis due to the diversity of its structure, receptors and cell sources, and the actions of RGMa in atherosclerosis have not been reported in previous reviews. Therefore, the current work reviews the evidence for roles of Netrin-1 and RGMa in the initiation and progression of atherosclerosis and discusses potential therapeutic targets in the future.

Netrin-1 in Post-stroke Neuroprotection: Beyond Axon Guidance Cue

BACKGROUND

Stroke, especially ischemic stroke, is a leading disease associated with death and long-term disability with limited therapeutic options. Neuronal death caused by vascular impairment, programmed cell death and neuroinflammation has been proven to be associated with increased stroke severity and poor stroke recovery. In light of this, a development of neuroprotective drugs targeting injured neurons is urgently needed for stroke treatment. Netrin-1, known as a bifunctional molecule, was originally described to mediate the repulsion or attraction of axonal growth by interacting with its different receptors. Importantly, accumulating evidence has shown that netrin-1 can manifest its beneficial functions to brain tissue repair and neural regeneration in different neurological disease models.

OBJECTIVE

In this review, we focus on the implications of netrin-1 and its possibly involved pathways on neuroprotection after ischemic stroke, through which a better understanding of the underlying mechanisms of netrin-1 may pave the way to novel treatments.

METHODS

Peer-reviewed literature was recruited by searching databases of PubMed, Scopus, Embase, and Web of Science till the year 2021.

CONCLUSION

There has been certain evidence to support the neuroprotective function of netrin-1 by regulating angiogenesis, autophagy, apoptosis and neuroinflammation after stroke. Netrin-1 may be a promising drug candidate in reducing stroke severity and improving outcomes.

Association between serum netrin-1 levels and early neurological deterioration after acute ischemic stroke

Background and purposes

Experimental studies demonstrated that netrin-1 (NT-1) has anti-inflammatory, tissue regeneration, and immune modulation properties. We aimed to discern the utility of NT-1 as a biomarker for assessing the risk of early neurological deterioration (END) after ischemic stroke.

Methods

This was a prospective study enrolling ischemic stroke patients with symptoms onset <24 h. Serum NT-1 concentrations were measured at admission. The National Institutes of Health Stroke Scale increased by ≥2 points and ≥4 points during the first 72 h after admission and was defined as END2 and END4, respectively.

Results

The study included 268 patients (146 men and 122 women) with a mean age of 63.0 ± 9.6 years. The median NT-1 concentrations were 466.4 pg/ml (interquartile range, 341.4–589.2 pg/ml). During the initial 72 h after admission, END2 was found in 83 (31.0%) patients, and END4 was observed in 48 (17.9%) subjects. After adjusted for potential confounders, multivariate analysis indicated that decreased NT-1 levels is an independent predictor for END2 [odds ratio (OR) 0.62, 95% confidence interval (CI) 0.46–0.84, p < 0.001) and END4 (OR 0.53, 95% CI 0.36–0.76, p < 0.001). Similar results were found when the NT-1 levels were analyzed as a categorical variable. Furthermore, restricted cubic spline analysis showed a linear association between NT-1 concentrations and the risk of END (END2, p = 0.006 for linearity; END4, p < 0.001 for linearity).

Conclusions

Our results suggest that decreased NT-1 levels were significantly associated with a higher risk of END after ischemic stroke.

Oxidative Injury in Ischemic Stroke: A Focus on NADPH Oxidase 4

Ischemic stroke is a leading cause of disability and mortality worldwide. Thus, it is urgent to explore its pathophysiological mechanisms and find new therapeutic strategies for its successful treatment. The relationship between oxidative stress and ischemic stroke is increasingly appreciated and attracting considerable attention. ROS serves as a source of oxidative stress. It is a byproduct of mitochondrial metabolism but primarily a functional product of NADPH oxidases (NOX) family members. Nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) is most closely related to the formation of ROS during ischemic stroke. Its expression is significantly upregulated after cerebral ischemia, making it a promising target for treating ischemic stroke. Several drugs targeting NOX4, such as SCM-198, Iso, G-Rb1, betulinic acid, and electroacupuncture, have shown efficacy as treatments of ischemic stroke. MTfp-NOX4 POC provides a novel insight for the treatment of stroke. Combinations of these therapies also provide new approaches for the therapy of ischemic stroke. In this review, we summarize the subcellular location, expression, and pathophysiological mechanisms of NOX4 in the occurrence and development of ischemic stroke. We also discuss the therapeutic strategies and related regulatory mechanisms for treating ischemic stroke. We further comment on the shortcomings of current NOX4-targeted therapy studies and the direction for improvement.

The Incremental Prognostic Value of Hepatocyte Growth Factor in First-Ever Acute Ischemic Stroke: An Early Link Between Growth Factor and Interleukins

Hepatocyte growth factor (HGF) is a potential prognostic factor for acute ischemic stroke (AIS). In this study, we sought to validate its earlier predictive accuracy within 24 h for first-ever AIS. Moreover, as HGF interacts with interleukins, their associations may lead to novel immunomodulatory therapeutic strategies. Patients with first-ever AIS (n = 202) within 24 h were recruited. Plasma HGF and related interleukin concentrations were measured by multiplex immunoassays. The primary and secondary outcomes were major disability (modified Rankin scale score ≥3) at 3 months after AIS and death, respectively. Elastic net regression was applied to screen variables associated with stroke outcome; binary multivariable logistic analysis was then used to explore the relationship between HGF level and stroke outcome. After multivariate adjustment, upregulated HGF levels were associated with an increased risk of the primary outcome (odds ratio, 7.606; 95% confidence interval, 3.090–18.726; p < 0.001). Adding HGF to conventional risk factors significantly improved the predictive power for unfavorable outcomes (continuous net reclassification improvement 37.13%, p < 0.001; integrated discrimination improvement 8.71%, p < 0.001). The area under the receiver operating characteristic curve value of the traditional model was 0.8896 and reached 0.9210 when HGF was introduced into the model. An elevated HGF level may also be a risk factor for mortality within 3 months poststroke. The HGF level was also positively correlated with IL-10 and IL-16 levels, and HGF before interaction with all interleukins was markedly negatively correlated with the lymphocyte/neutrophil ratio. HGF within 24 h may have prognostic potential for AIS. Our findings reinforce the link between HGF and interleukins.

Protective effects of the knockdown of lncRNA AK139328 against oxygen glucose deprivation/reoxygenation-induced injury in PC12 cells

Cerebral ischemic stroke is a major cause of adult morbidity and mortality worldwide. Several long non-coding RNAs (lncRNAs) have been reported to participate in cerebral ischemia/reperfusion injury (IRI). However, to the best of our knowledge, the role of lncRNA AK139328 in cerebral ischemic stroke remains poorly understood. The present study aimed to determine the expression and function of lncRNA AK139328 in the progression of IRI. PC12 cells were injured by oxygen glucose deprivation/reoxygenation (OGD/R) to establish an in vitro ischemic stroke model. An MTT assay was performed to determine cell viability. Reverse transcription-quantitative PCR was used to analyze the expression levels of AK139328 and Netrin-1 in blood samples from patients who had suffered a cerebral ischemic stroke and healthy individuals or OGD/R PC12 cells. ELISAs were used to determine the levels of inflammatory cytokines. In addition, oxidative stress levels and the levels of cell apoptosis were evaluated by reactive oxygen species (ROS) kits, flow cytometry and western blotting. Immunofluorescence staining was used for the detection of cell neurite outgrowth. The results of the present study revealed that AK139328 expression levels were upregulated in patients who had suffered a cerebral ischemic stroke and in PC12 cells following stimulation with OGD/R. The knockdown of AK139328 alleviated OGD/R-induced decreases in cell viability, downregulation in Netrin-1 expression and increases in inflammatory cytokines levels, including TNF-α, IL-1β and IL-6. Moreover, AK139328 silencing suppressed oxidative stress and cell apoptosis in OGD/R-treated PC12 cells. Furthermore, the expression levels of microtubule associated protein 2 and growth associated protein 43 in OGD/R-injured PC12 cells were upregulated following the knockdown of AK139328 expression. In conclusion, these findings suggested that the knockdown of AK139328 expression may protect PC12 cells against OGD/R injury by regulating inflammatory responses, oxidative stress and cell apoptosis. The data suggested a potential therapeutic target for the diagnosis and treatment of cerebral ischemic stroke.

A Novel Netrin-1-Derived Peptide Enhances Protection against Neuronal Death and Mitigates of Intracerebral Hemorrhage in Mice

It has been reported that Netrin-1 is involved in neuroprotection following injury to the central nervous system. However, the minimal functional domain of Netrin-1 which can preserve the neuroprotection but avoid the major side effects of Netrin remains elusive. Here, we investigated the neuroprotective effect of a peptide E1 derived from Netrin-1′s EGF3 domain (residues 407–422). We found that it interacts with deleted colorectal carcinoma (DCC) to activate focal adhesion kinase phosphorylation exhibiting neuroprotection. The administration of the peptide E1 was able to improve functional recovery through reduced apoptosis in an experimental murine model of intracerebral hemorrhage (ICH). In summary, we reveal a functional sequence of Netrin-1 that is involved in the recovery process after ICH and identify a candidate peptide for the treatment of ICH.

Serum netrin-1 as a potential biomarker for functional outcome of traumatic brain injury

BACKGROUND

Decreased serum netrin-1 concentrations have been found after acute brain injury. We investigated the role of serum netrin in prognosis of traumatic brain injury (TBI).

METHODS

In this prospective and observational study, enzyme-linked immunosorbent assay was used to detect serum netrin-1 concentrations in 50 mild TBI patients (Glasgow coma scale (GCS) score, 13-15), 83 moderate TBI patients (GCS score, 9-12), 69 severe TBI patients (GCS score, 3-8) and 50 healthy controls. Glasgow outcome scale score of 1-3 at 6 months after trauma was defined as poor outcome.

RESULTS

Serum netrin-1 concentrations were significantly lower in moderate or severe TBI patients than in controls and in severe TBI patients than in moderate TBI patients, while not in mild TBI patients than in controls. GCS score and Rotterdam computed tomography classification were closely correlated with serum netrin-1 concentrations among TBI patients. Forty-two (20.8%) patients had poor outcome. Receiver operating characteristic curve analysis revealed that serum netrin-1 concentrations could distinguish patients with poor outcome from the other remainders significantly. In addition, serum netrin-1 concentrations were independently associated with poor outcome.

CONCLUSIONS

Serum netrin-1 might serve as a potential biomarker for prognosis of TBI.

Association between serum netrin-1 and prognosis of ischemic stroke: The role of lipid component levels

BACKGROUND AND AIMS

High serum netrin-1 levels decrease the risk of ischemic stroke and are negatively associated with outcomes after ischemic stroke. However, it remains unclear whether the association between netrin-1 and ischemic stroke prognosis is modified by lipid component levels.

METHODS AND RESULTS

We measured baseline serum netrin-1 levels in 3065 ischemic stroke patients from China Antihypertensive Trial in Acute Ischemic Stroke (CATIS). The primary outcome was a combination of death and major disability (modified Rankin Scale score≥3) at 3 months after ischemic stroke. Total cholesterol (TC) levels could modify the association between netrin-1 and prognosis of ischemic stroke (P_interaction = 0.040). After multivariate adjustment, the odds ratios of the primary outcome associated with the highest quartile of netrin-1 were 0.39 (95%CI, 0.17-0.90; P_trend = 0.004) for the patients with high TC levels and 0.82 (95%CI, 0.61-1.11; P_trend = 0.149) for those with normal TC levels. Adding netrin-1 to conventional risk factors improved risk prediction for the primary outcome in the patients with high TC levels (net reclassification improvement: 26.8%, P = 0.015; integrated discrimination index: 1.6%, P = 0.028) but not in those with normal TC levels.

CONCLUSIONS

Elevated netrin-1 is associated with improved prognosis at 3 months after ischemic stroke in the patients with high TC levels but not in those with normal TC levels. Further prospective studies from other populations and randomized clinical trials are needed to verify our findings and clarify the potential mechanisms.

Decreased serum netrin-1 is associated with ischemic stroke: A case-control study

BACKGROUND AND AIMS

Netrin-1 was a laminin-related protein involved in neurovascular protection, and we previously discovered that decreased serum netrin-1 was associated with poor prognosis of ischemic stroke. However, the relationship between serum netrin-1 level and the risk of ischemic stroke remains unclear. The aim of this study was to investigate the association between netrin-1 level and risk of ischemic stroke.

METHODS AND RESULTS

A case-control study including 591 ischemic stroke patients and 591 age- and sex-matched healthy individuals was conducted, and serum netrin-1 concentrations were quantitatively determined via enzyme-linked immunosorbent assay for all participants. The serum netrin-1 levels were significantly lower in the ischemic stroke patients than those in matched controls (median, 496.4 vs 652.1 pg/mL; P < 0.001). After adjustment for potential confounders, the odds ratio of ischemic stroke associated with the highest quartile of netrin-1 was 0.07 (95% CI: 0.01-0.65; P_trend = 0.018) compared with the lowest quartile of netrin-1. Each 1-standard deviation increase of log-transformed netrin-1 was associated with a lower odds of ischemic stroke (odds ratio: 0.45, 95% CI: 0.22-0.94; P = 0.032), and a dose-response relationship between serum netrin-1 and ischemic stroke was observed (P_linearity = 0.003). Incorporating netrin-1 to conventional risk factors improved the discriminatory power for ischemic stroke (net reclassification index = 98.0%, P < 0.001; integrated discrimination improvement = 0.28%, P = 0.027).

CONCLUSIONS

Serum netrin-1 was decreased in patients with ischemic stroke compared with healthy controls, suggesting that there was a potential role of netrin-1 in the pathogenesis of ischemic stroke.

Analysis of Antiapoptosis Effect of Netrin-1 on Ischemic Stroke and Its Molecular Mechanism under Deleted in Colon Cancer/Extracellular Signal-Regulated Kinase Signaling Pathway

To analyze the regulatory effect of Netrin-1 in ischemic stroke and its influence on Deleted in Colon Cancer (DCC)/Extracellular Signal-regulated Kinase (ERK) signaling pathway, 20 male rats were selected to construct the rat model of middle cerebral artery occlusion (MCAO), 10 normal rats were selected as healthy controls (Normal Saline (NS)), and they were divided into the MCAO+Netrin-1 group, MCAO group, and NS group according to different treatment schemes. The positive expression of Netrin-1 was detected by immunostaining, magnetic resonance imaging (MRI) was adopted to detect the percentage of rat cerebral infarct volume in the cerebral hemispheres, and Modified Neurological Severity Score (mNSS) was adopted to evaluate postoperative neurological function in rats. Besides, a tunnel staining experiment was applied to detect the apoptosis rate of rat neurons, the sticker removal test was applied to evaluate the postoperative sensory function of rats, and fluorescence staining was adopted to detect the expression of DCC and ERK in rats. The results showed that the percentage of cerebral infarction volume in the cerebral hemispheres of the MCAO+Netrin-1 group was higher than that of the MCAO and NS groups (P < 0.05); in the MCAO+Netrin-1 group, the MCAO mNSS scoring and the time spent in the sticker removal test were lower than the MCAO group (P < 0.05); the apoptosis rate of rats in the MCAO+Netrin-1 group was lower than that in the MCAO group (P < 0.05); the average fluorescence intensity of DCC and p-ERK in the MCAO+Netrin-1 group was higher than that in the MCAO group (P < 0.05); the average fluorescence intensity of p-ERK in the MCAO+Netrin-1 group was higher than that in the MCAO group (P < 0.05). In short, Netrin-1 can effectively reduce the brain tissue damage in rats with ischemic stroke, improve the nerve function and sensory function of rats, and inhibit neuronal cell apoptosis. Netrin-1 can promote DCC expression and ERK phosphorylation, and the EPK signaling pathway may be involved in the antiapoptotic effect of Netrin-1.

Decreased Serum Netrin-1 as a Predictor for Post-Stroke Depression in Chinese Patients with Acute Ischemic Stroke

BACKGROUND AND AIMS

Experimental studies demonstrated that netrin-1 (NT-1) is an important factor influencing the recovery after ischemic stroke. However, whether NT-1 levels were associated with the post-stroke depression (PSD) remains unclear. We aimed to evaluate the relationship between NT-1 levels and PSD at 3 months in patients with ischemic stroke.

METHODS

From January 2018 to December 2019, consecutive Chinese patients with first-ever ischemic stroke were prospectively recruited. Serum NT-1 levels were measured at admission. Patients with a 17-item Hamilton Depression Scale score of ≥7 were given the Structured Clinical Interview of the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, for diagnosis of PSD.

RESULTS

A total of 238 patients (mean age, 62.5 years; 45.4% female) were enrolled. The median NT-1 concentrations were 467.8 pg/mL (interquartile range, 351.8-581.0 pg/mL). During the 3-month follow-up period, 64 patients (26.9%) experienced PSD. Serum NT-1 levels were significantly lower in PSD patients than in patients without PSD (median, 380.3 pg/mL versus 478.5 pg/mL; P = 0.001). After adjusting for demographic characteristic, National Institutes of Health stroke score, and other potential confounders by multiple logistic regression analysis, patients with NT-1 levels in the first quartile were more likely to have 3-month PSD (as compared with the fourth quartile, odds ratio 3.83, 95% confidence intervals, 1.53-9.63, P = 0.004). Similar significant findings were observed when the NT-1 levels were added as a continuous variable.

CONCLUSIONS

Our data demonstrated that decreased serum NT-1 levels, in a Chinese population, were significantly associated with PSD at 3 months.

Effect of Serum Netrin-1 Levels on Diagnosis and Prognosis in Patients Admitted to the Emergency Service for Acute Coronary Syndrome

Background

Netrin-1 is a recently discovered diagnostic biomarker that indicates atherosclerosis, angiogenesis, and ischemia-reperfusion damage. There are no human studies about Netrin-1 in acute coronary syndrome (ACS). The purpose of the present study was to investigate Netrin-1 levels in the early diagnosis and successful reperfusion of ACS.

Method

The study was conducted with 188 patients diagnosed with ACS and 50 healthy subjects at the emergency unit in a prospective design. Blood samples were collected from the patient group at initial admission and after angiography. The control group consisted of healthy adult subjects without any disease. Netrin-1 levels were studied in both groups.

Results

The Netrin-1 levels of the patient group at the time of admission were found to be higher than of the control group (p<0.001). In the patient group, netrin-1 levels measured at initial admission (1.53±0.19) and after angiography (1.49±0.19) were determined to be statistically significant (p:0.049). In the patient group, where the Thrombolysis in Myocardial Infarction (TIMI) 3 flow was established after angiography, netrin-1 levels were detected to be low (p:0.039). Netrin-1 levels obtained at the time of admission were determined to be significantly different in the Global Registry of Acute Coronary Events (GRACE) moderate and high-risk groups in comparison to the low-risk group (p:0.017).

Conclusion

Netrin-1 was shown to increase in the early diagnosis of ACS and to decrease in patients for whom reperfusion was established after angiography. Therefore, Netrin-1 can be an important biomarker as an indicator of diagnosis and successful reperfusion in ACS.

Decreased Serum Retinoic Acid May Predict Poor Outcome in Ischemic Stroke Patients

BACKGROUND AND AIMS

Decreased serum retinoic acid (RA) levels have been shown to be linked with increased mortality in cardiovascular diseases. This study aimed to investigate the relationship between serum RA and 3-month functional outcome after ischemic stroke.

METHODS

Between January 2019 and September 2019, we prospectively recruited ischemic stroke patients within 24 hrs of symptom onset. Serum RA levels were measured for all patients at admission. The primary outcome was defined as poor functional outcome (modified Rankin Scale 3-6) at 90 days. The secondary outcome was defined as early neurological deterioration (END), which is considered as an increase of ≥1 point in motor power or total National Institutes of Health Stroke Scale score of ≥2 points within 7 days.

RESULTS

A total of 217 patients were included in the analysis. The median RA levels were 2.9 ng/mL. Ninety-four (43.3%) and 65 (30.0%) patients experienced 3-month poor outcome and END, respectively. After adjusted for potential confounders, decreased levels of serum RA were associated with a higher risk of poor outcome (P for trend = 0.001) and END (P for trend = 0.002). Adding RA quartile to the existing risk factors improved risk prediction for poor outcome [net reclassification improvement (NRI) = 42.6%, P = 0.001; integrated discrimination improvement (IDI) = 5.7%, P = 0.001] and END (NRI index = 45.4%, P = 0.001; IDI = 4.3%; P = 0.005).

CONCLUSION

Low serum RA levels at baseline were associated with poor prognosis at 90 days after ischemic stroke, suggesting that RA may be a potential prognostic biomarker for ischemic stroke.