Effect of uric acid in animal models of ischemic stroke: A systematic review and meta-analysis

The role of amino acid metabolism alterations in acute ischemic stroke: From mechanism to application

Acute ischemic stroke (AIS) is the most prevalent type of stroke, and due to its high incidence, disability rate, and mortality rate, it imposes a significant burden on the health care system. Amino acids constitute one of the most crucial metabolic products within the human body, and alterations in their metabolic pathways have been identified in the microenvironment of AIS, thereby influencing the pathogenesis, severity, and prognosis of AIS. The amino acid metabolism characteristics in AIS are complex. On one hand, the dynamic progression of AIS continuously reshapes the amino acid metabolism pattern. Conversely, changes in the amino acid metabolism pattern also exert a double-edged effect on AIS. This interaction is bidirectional, dynamic, heterogeneous, and dose-specific. Therefore, the distinctive metabolic reprogramming features surrounding amino acids during the AIS process are systematically summarized in this paper, aiming to provide potential investigative strategies for the early diagnosis, treatment approaches, and prognostic enhancement of AIS.

Serum uric acid as a predictor of mortality in patients with stroke: results from National Health and Nutrition Examination Survey 2007-2016

Objective

This research endeavors to explore the relationship between serum uric acid (SUA) concentration and all-cause mortality in stroke patients.

Methods

We undertook a cross-sectional analysis utilizing data derived from the National Health and Nutrition Examination Survey (NHANES) spanning 2007 to 2016. The concentrations of SUA served as the independent variable, while the dependent variable was defined as all-cause mortality in stroke patients. The quartile method was utilized to classify uric acid levels into four distinct categories. Subsequently, three models were developed, and Cox proportional hazards regression was used to assess the effect of varying uric acid concentrations on the risk of all-cause mortality among stroke patients.

Results

The study included a total of 10,805 participants, of whom 395 were stroke patients. Among all populations, the group with elevated levels of uric acid (Q4) exhibited a significant association with the overall mortality risk among stroke patients in all three models (model 1 p < 0.001, model 2 p < 0.001, model 3 p < 0.001). In the male population, there was no significant correlation observed between uric acid levels and the overall mortality risk among stroke patients in model 3 (Q2 p = 0.8, Q3 p = 0.2, Q4 p = 0.2). However, within the female population, individuals with high uric acid levels (Q4) demonstrated a noteworthy association with the overall mortality risk among stroke patients across all three models (model 1 p < 0.001, model 2 p < 0.001, model 3 p < 0.001).

Conclusion

This cross-sectional investigation reveals a significant correlation between SUA levels and all-cause mortality in stroke patients, with a noticeable trend observed among females. Consequently, SUA may serve as a promising biomarker for assessing the prognosis of individuals affected by stroke.

Efficacy of bumetanide in animal models of ischemic stroke: a systematic review and meta-analysis

This meta-analysis aimed to describe the efficacy of bumetanide in improving infarct volume, brain edema, and behavioral outcomes in animal models of cerebral ischemia. Embase, PubMed and Web of Science databases were searched from their inception to February 2024 (INPLASY:202430023). Data on the animal species, stroke model, drug dose, time of treatment, method of administration, study quality, and outcomes were extracted and pooled in a meta-analysis. The combined standardized mean difference (SMD) or mean difference (MD) estimates and 95% confidence intervals (CIs) were calculated using random- or fixed-effects models. Thirteen eligible studies involving >200 animals fulfilled the inclusion criteria and were included in this meta-analysis. Meta-analyses demonstrated that bumetanide treatment significantly reduced cerebral infarct volume (SMD: -0.42; 95% CI: -0.75, -0.09; p < 0.01; n = 186 animals) and consistently relieved brain edema (SMD: -1.39; 95% CI: -2.06, -0.72; p < 0.01; n = 64 animals). Subgroup analyses demonstrated that bumetanide treatment reduced infarct volume in transient but not permanent cerebral ischemia models. When administered after the stroke, it was more effective than treatment initiation before the stroke. Eight studies assessed the effect of bumetanide on behavioral function and the results showed that bumetanide treatment significantly improved neurobehavioral deficits (SMD: -2.35; 95% CI: -2.72, -1.97; p < 0.01; n = 250 animals). We conclude that bumetanide appears to be effective in reducing infarct volume and brain edema and improving behavioral recovery in animal models of cerebral ischemia. This mechanism needs to be confirmed through further investigation.

Neuroprotective effects of anti-TRAIL-ICG nanoagent and its multimodal imaging evaluation in cerebral ischemia-reperfusion injury

Cerebral ischemia-reperfusion injury (CIRI) is a major challenge to neuronal survival in acute ischemic stroke (AIS). However, effective neuroprotective agents remain to be developed for the treatment of CIRI. In this work, we have developed an Anti-TRAIL protein-modified and indocyanine green (ICG)-responsive nanoagent (Anti-TRAIL-ICG) to target ischemic areas and then reduce CIRI and rescue the ischemic penumbra. In vitro and in vivo experiments have demonstrated that the carrier-free nanoagent can enhance drug transport across the blood-brain barrier (BBB) in stroke mice, exhibiting high targeting ability and good biocompatibility. Anti-TRAIL-ICG nanoagent played a better neuroprotective role by reducing apoptosis and ferroptosis, and significantly improved ischemia-reperfusion injury. Moreover, the multimodal imaging platform enables the dynamic in vivo examination of multiple morphofunctional information, so that the dynamic molecular events of nanoagent can be detected continuously and in real time for early treatment in transient middle cerebral artery occlusion (tMCAO) models. Furthermore, it has been found that Anti-TRAIL-ICG has great potential in the functional reconstruction of neurovascular networks through optical coherence tomography angiography (OCTA). Taken together, our work effectively alleviates CIRI after stoke by blocking multiple cell death pathways, which offers an innovative strategy for harnessing the apoptosis and ferroptosis against CIRI.

The prognostic value of combined uric acid and neutrophil-to-lymphocyte ratio in acute ischemic stroke patients treated with intravenous thrombolysis

BACKGROUND

Serum uric acid (UA) and the neutrophil-to-lymphocyte ratio (NLR) have been reported to be associated with outcomes in acute ischemic stroke (AIS). However, whether UA is related to the prognosis of AIS patients undergoing intravenous thrombolysis (IVT) remains inconclusive. We sought to explore the combined effect of UA and NLR on the prognosis of AIS treated with IVT.

METHODS

A total of 555 AIS patients receiving IVT treatment were enrolled. Patients were categorized into four groups according to the levels of UA and NLR: LNNU (low NLR and normal UA), LNHU (low NLR and high UA), HNNU (high NLR and normal UA), and HNHU (high NLR and high UA). Multivariable logistic regression analysis was used to evaluate the value of serum UA level and NLR in predicting prognosis. The primary outcomes were major disability (modified Rankin scale (mRS) score 3-5) and death within 3 months.

RESULTS

After multivariate adjustment, a high NLR (≥ 3.94) increased the risk of 3-month death or major disability (OR, 2.23; 95% CI, 1.42 to 3.55, p < 0.001). However, there was no statistically significant association between a high UA level (≥ 313.00 µmol/L) and clinical outcome. HNHU was associated with a 5.09-fold increase in the risk of death (OR, 5.09; 95% CI, 1.31-19.83; P value = 0.019) and a 1.98-fold increase in the risk of major disability (OR, 1.98; 95% CI 1.07-3.68; P value = 0.030) in comparison to LNNU.

CONCLUSIONS

High serum UA levels combined with high NLR were independently associated with 3-month death and major disability in AIS patients after IVT.

A Pilot Systematic Review and Meta-analysis of Neuroprotective Studies in Female Rodent Models of Ischemic Stroke

Most ischemic stroke (IS) patients go untreated due to limited treatment windows, restrictive eligibility criteria, and poor availability of current clinical therapies. Neuroprotective treatments targeting protracted neurodegeneration are needed yet keep failing in clinical trials. Over half of IS patients are female, and the scarcity of neuroprotective studies using female animals hinders translational success. This pilot review and meta-analysis assessed the relationship between the risk of bias and efficacy of studies testing post-ischemic neuroprotective therapies using female rodent models of IS. We carried out a systematic search of the PubMed database for studies published between 1999 and May 2022, used the CAMARADES checklist to evaluate study quality, and extracted data pertaining to lesion volume and behavioral assessment. We found that 34 studies met our inclusion criteria, with pooled effect sizes depicting a significant treatment effect. However, researchers used mostly healthy young females, administered therapies within short time windows, ignored hormonal influences, and did not assess long-term outcomes. Interestingly, studies failing to report factors impacting internal validity, such as blinding and random allocation, had inflated effect sizes or did not reach statistical significance. There was also a relationship between low study quality and larger effect sizes for functional outcome, stressing the need to follow the existing translational design, reporting, and data analysis guidelines. In this review, we cover previous recommendations and offer our own in hopes that rigorous and meticulous research using female animal models of IS will increase our chances of successful bench-to-bedside translation.

CNS Drug Delivery in Stroke: Improving Therapeutic Translation From the Bench to the Bedside

Drug development for ischemic stroke is challenging as evidenced by the paucity of therapeutics that have advanced beyond a phase III trial. There are many reasons for this lack of clinical translation including factors related to the experimental design of preclinical studies. Often overlooked in therapeutic development for ischemic stroke is the requirement of effective drug delivery to the brain, which is critical for neuroprotective efficacy of several small and large molecule drugs. Advancing central nervous system drug delivery technologies implies a need for detailed comprehension of the blood-brain barrier (BBB) and neurovascular unit. Such knowledge will permit the innate biology of the BBB/neurovascular unit to be leveraged for improved bench-to-bedside translation of novel stroke therapeutics. In this review, we will highlight key aspects of BBB/neurovascular unit pathophysiology and describe state-of-the-art approaches for optimization of central nervous system drug delivery (ie, passive diffusion, mechanical opening of the BBB, liposomes/nanoparticles, transcytosis, intranasal drug administration). Additionally, we will discuss how endogenous BBB transporters represent the next frontier of drug delivery strategies for stroke. Overall, this review will provide cutting edge perspective on how central nervous system drug delivery must be considered for the advancement of new stroke drugs toward human trials.

Efficacy of ferulic acid in the treatment of acute ischemic stroke injury in rats: a systematic review and meta-analysis

Background: Intravenous thrombolysis is commonly used in the treatment of acute ischemic stroke damage. The existing thrombolytic drugs still suffer significant shortcomings, including a limited fibrin specificity and bleeding complications. Ferulic acid can directly bind the key thrombus enzymes and target to blood clots, suggesting its thrombolytic potency that may be beneficial with thrombolytic potency for the treatment of acute ischemic stroke damage. Objective: The purpose of this systematic review and meta-analysis was to evaluate the efficacy of ferulic acid in the treatment of acute ischemic stroke injury in rats and its potential mechanism of action. Materials and methods: We conducted a literature search in six databases, including CNKI, up to July 2023. Results: Sixteen trials were included in the meta-analysis, which demonstrated that ferulic acid significantly reduced infarct size, neurological deficit score, apoptosis index, cleaved caspase-3, and cytochrome C levels (all p < 0.05). In addition, ferulic acid significantly increased the levels of phosphorylated Akt, mitochondrial Bcl-xL/Bax, phosphorylated astrocyte PEA15, hippocampal calcium binding protein, and mitochondrial Bcl-2/Bax ratio (all p < 0.05). Conclusion: This study demonstrates that ferulic acid protects against acute ischemic stroke injury in rats by inhibiting ischemia-induced excitotoxicity, inflammatory response, and apoptosis.

Oxidative stress, the blood-brain barrier and neurodegenerative diseases: The critical beneficial role of dietary antioxidants

In recent years, growing awareness of the role of oxidative stress in brain health has prompted antioxidants, especially dietary antioxidants, to receive growing attention as possible treatments strategies for patients with neurodegenerative diseases (NDs). The most widely studied dietary antioxidants include active substances such as vitamins, carotenoids, flavonoids and polyphenols. Dietary antioxidants are found in usually consumed foods such as fresh fruits, vegetables, nuts and oils and are gaining popularity due to recently growing awareness of their potential for preventive and protective agents against NDs, as well as their abundant natural sources, generally non-toxic nature, and ease of long-term consumption. This review article examines the role of oxidative stress in the development of NDs, explores the 'two-sidedness' of the blood-brain barrier (BBB) as a protective barrier to the nervous system and an impeding barrier to the use of antioxidants as drug medicinal products and/or dietary antioxidants supplements for prevention and therapy and reviews the BBB permeability of common dietary antioxidant suplements and their potential efficacy in the prevention and treatment of NDs. Finally, current challenges and future directions for the prevention and treatment of NDs using dietary antioxidants are discussed, and useful information on the prevention and treatment of NDs is provided.

A multi-laboratory preclinical trial in rodents to assess treatment candidates for acute ischemic stroke

Human diseases may be modeled in animals to allow preclinical assessment of putative new clinical interventions. Recent, highly publicized failures of large clinical trials called into question the rigor, design, and value of preclinical assessment. We established the Stroke Preclinical Assessment Network (SPAN) to design and implement a randomized, controlled, blinded, multi-laboratory trial for the rigorous assessment of candidate stroke treatments combined with intravascular thrombectomy. Efficacy and futility boundaries in a multi-arm multi-stage statistical design aimed to exclude from further study highly effective or futile interventions after each of four sequential stages. Six independent research laboratories performed a standard focal cerebral ischemic insult in five animal models that included equal numbers of males and females: young mice, young rats, aging mice, mice with diet-induced obesity, and spontaneously hypertensive rats. The laboratories adhered to a common protocol and efficiently enrolled 2615 animals with full data completion and comprehensive animal tracking. SPAN successfully implemented treatment masking, randomization, prerandomization inclusion and exclusion criteria, and blinded assessment of outcomes. The SPAN design and infrastructure provide an effective approach that could be used in similar preclinical, multi-laboratory studies in other disease areas and should help improve reproducibility in translational science.

Serum uric acid and prognosis in acute ischemic stroke: a dose-response meta-analysis of cohort studies

Background

There have been contradictory findings regarding the relationship between serum uric acid levels and prognosis in acute ischemic stroke. Whether this association is nonlinear due to uric acid's paradoxical properties (antioxidant and prooxidant) is unclear.

Methods

We searched PubMed, Web of Science, and Embase databases until December 2022. Cohort studies reporting serum uric acid levels and functional outcome, mortality, or neurological complications in patients with acute ischemic stroke were included. Summary effect estimates were calculated using a random-effect model. Moreover, dose-response relationships were assessed by the generalized least squares trend estimation.

Results

Altogether, 13 cohort studies were identified in this study. Compared to the lowest baseline serum uric acid levels, the highest levels were associated with decreased risk of poor functional outcome (OR = 0.70, 95% CI 0.54-0.91, I2 = 29%), hemorrhagic transformation (OR = 0.15, 95% CI 0.05-0.42, I2 = 79%), and post-stroke depression (OR = 0.04, 95% CI 0.00-0.95, I2 = 89%), but not associated with mortality and symptomatic intracerebral hemorrhage. A nonlinear relationship was observed in poor functional outcome (U-shaped, P for nonlinearity = 0.042), hemorrhagic transformation (inverse, P for nonlinearity = 0.001), and post-stroke depression (inverse, P for nonlinearity = 0.002). In addition, there was a single study reporting a U-shaped association in post-stroke epilepsy (P for nonlinearity <0.001). Furthermore, another study reported a positive curvilinear association in stroke recurrence (P for nonlinearity <0.05). The insufficient number of original articles for some prognostic indicators should be considered when interpreting the results of this meta-analysis.

Conclusion

In patients with acute ischemic stroke, serum uric acid levels are nonlinearly associated with the risk of poor functional outcome (U-shaped). More evidence is needed to confirm the association between serum uric acid levels and neurological complications following acute ischemic stroke.

Uric Acid and Cognitive Impairment in Patients with Acute Ischemic Stroke: A Meta-Analysis

Serum uric acid (UA) has been suggested to be correlated with outcomes after stroke. We performed a meta-analysis to evaluate the association between serum UA and post-stroke cognitive impairment (PSCI) in patients with acute ischemic stroke (AIS). Relevant observational studies were identified by search of electronic databases including PubMed, Embase, and Web of Science. A randomized-effect model incorporating the possible between-study heterogeneity was used to pool the results. Overall, eleven studies with 4246 patients of AIS were included, 2073 (48.8%) of them had PSCI. Pooled results showed that patients with PSCI had significantly higher level of serum UA as compared to those without PSCI (mean difference: 35.70 μmol/l, 95% confidence interval (CI): 8.36 to 63.01, p=0.01; I2=95%). Subgroup analysis showed significant higher level of serum UA in patients with PSCI evaluated during follow-up of 3 months to 3 years, but not for those evaluated during hospitalization (p for subgroup difference=0.01). In addition, results of meta-analysis also showed that compared to patients with lower serum UA, AIS patients with higher serum UA had increased risk of PSCI (odds ratio: 1.33, 95% CI: 1.02 to 1.73, p=0.04; I2=72%). Higher level of serum UA after disease onset may be a marker of increased risk of PSCI in patients with AIS. Although these findings need to be validated in large-scale prospective studies, the possible mechanisms underlying the association between UA and PSCI should be also investigated.

U-Shaped Association Between Serum Uric Acid and Hemorrhagic Transformation After Intravenous Thrombolysis

BACKGROUND

Uric acid (UA) has both antioxidative and pro-oxidative properties. The study aimed to investigate the relationship between serum UA and hemorrhagic transformation (HT) after intravenous thrombolysis in patients with acute ischemic stroke.

METHODS

The patients undergoing intravenous thrombolysis from two hospitals in China were retrospectively analyzed. HT was evaluated using computed tomography images reviewed within 24- 36h after thrombolysis. Symptomatic intracranial hemorrhage (sICH) was defined as HT accompanied by worsening neurological function. Multivariate logistic regression and spline regression models were performed to explore the relationship between serum UA levels and the risk of HT and sICH.

RESULTS

Among 503 included patients, 60 (11.9%) were diagnosed with HT and 22 (4.4%) developed sICH. Patients with HT had significant lower serum UA levels than those without HT (245 [214-325 vs. 312 [256-370] μmol/L, p < 0.001). Multivariable logistic regression analysis indicated that patients with higher serum UA levels had a lower risk of HT (OR per 10-μmol/L increase 0.96, 95%CI 0.92-0.99, p = 0.015). Furthermore, multiple-adjusted spline regression models showed a Ushaped association between serum UA levels and HT (p < 0.001 for non-linearity). Similar results were present between serum UA and sICH. Restricted cubic spline models predicted the lowest risk of HT and sICH when the serum UA levels were 386μmol/L.

CONCLUSION

The data show the U-shaped relationship between serum UA levels and the risk of HT and sICH after intravenous thrombolysis.

Sex-specific relationship between serum uric acid levels and the prevalence of large vessel occlusion in acute ischemic stroke

PURPOSE

Previous studies have found that uric acid (UA) plays a neuroprotective role in ischemic stroke patients. However, the relationship between serum UA of acute ischemic stroke (AIS) and large vessel occlusion (LVO) strokes is unclear.

METHODS

In this retrospective study, 1318 AIS patients were enrolled. All patients underwent imaging examinations to assess the intracranial and carotid vessels. Multivariate logistic regression analysis was conducted to evaluate the relationship between UA levels and the prevalence of LVO.

RESULTS

The 1318 enrolled AIS patients were comprised of 287 LVO and 1031 non-LVO patients. UA levels in males were higher than females (321.04 ± 91.28 vs. 274.43 ± 82.11, p < .001). The association between serum UA levels and LVO was modified by sex (p = .007). When serum UA levels were continuous, after adjusting for related risk factors, higher serum UA levels were still associated with a lower prevalence of LVO in males (odds ratio (OR) 0.997, 95% confidence interval (CI) 0.994-0.999), but not in female subjects (OR 0.998, 95% CI 0.995-1.001). When serum UA levels were divided into tertiles, higher UA levels had a lower risk of LVO than the moderate (p = .006) and lower tertiles of UA levels (p = .010) in males, but not in females (p = .402 and p = .206 for moderate and low tertiles, respectively).

CONCLUSIONS

AIS patients with higher serum UA levels tend to be associated with a lower risk of LVO in males, but not in females.