Serum gamma-glutamyl transferase is associated with silent brain infarcts in a healthy population

Study of Serum Gamma-Glutamyl Transferase Levels in Patients With Acute Ischemic Stroke

Background Gamma-glutamyl transferase (GGT) mediates intracellular uptake of glutathione which is a known antioxidant. GGT levels are found to be elevated in conditions of oxidative stress. Ischemic stroke results in anoxic injury, which liberates free radicals, causing glutathione to rise, which may be accompanied by a rise in serum GGT levels. This study aimed to compare serum GGT levels in acute ischemic stroke patients with normal controls and to ascertain the relation of serum GGT levels with National Institute of Health Stroke Scale (NIHSS) scores. Materials and methods This cross-sectional study was carried out in a tertiary care hospital in South India from August 2023 to February 2024. The study included 57 patients who presented with acute ischemic stroke within 24 hours of onset and 57 age- and sex-matched controls. The serum GGT levels of the cases were compared with age- and sex-matched controls using an independent t-test. Mean serum GGT levels were compared among groups with varying NIHSS scores and different locations of infarction using the ANOVA test. Serum GGT levels were also compared based on age, gender, and various comorbidities. Results The mean serum GGT levels were significantly increased (p < 0.0001) in acute ischemic stroke patients, 43.96 ± 28.02 (mean ± SD), when compared to controls, 26.14 ± 5.93 (mean ± SD). The difference in serum GGT levels with NIHSS scores of 5-15 (moderate strokes) with 34.17 ± 18.39 (mean ± SD), 16-20 (moderate-severe strokes) with 46.64 ± 21.95 (mean ± SD), and >21 (severe stroke) with 84.62 ± 39.35 (mean ± SD) was significant (p < 0.00001). Serum GGT levels were not significant while comparing age, gender, location of infarction, type 2 diabetes mellitus, and hypertension. Conclusion Serum GGT levels were significantly elevated in acute ischemic stroke patients within 24 hours of presentation. Serum GGT levels were significantly elevated with increasing severity of stroke as calculated by NIHSS scores at the time of presentation. Serum GGT levels are a potential marker of ischemic stroke and its severity.

The discovery of GGT1 as a novel gene for ischemic stroke conferring protection against disease risk in non-smokers and non-abusers of alcohol

OBJECTIVES

Increased plasma gamma-glutamyl transferase (GGT1) has been identified as a robust and independent risk factor for ischemic stroke (IS), but the molecular mechanisms of the enzyme-disease association are unclear. The present study investigated whether polymorphisms in the GGT1 gene contribute to IS susceptibility.

MATERIALS AND METHODS

DNA samples obtained from 1288 unrelated individuals (600 IS patients and 688 controls) were genotyped for common single nucleotide polymorphisms of GGT1 using the MassArray-4 platform.

RESULTS

The rs5751909 polymorphism was significantly associated with decreased risk of ischemic stroke regardless sex and age (Pperm ≤ 0.01, dominant genetic model). The haplotype rs4820599A-rs5760489A-rs5751909A showed strong protection against ischemic stroke (OR 0.53, 95 %CI 0.36 - 0.77, Pperm ≤ 0.0001). The protective effect of SNP rs5751909 in the stroke phenotype was successfully replicated in the UK Biobank, SiGN, and ISGC cohorts (P ≤ 0.01). GGT1 polymorphisms showed joint (epistatic) effects on the risk of ischemic stroke, with some known IS-associated GWAS loci (e.g., rs4322086 and rs12646447) investigated in our population. In addition, SNP rs5751909 was found to be strongly associated with a decreased risk of ischemic stroke in non-smokers (OR 0.54 95 %CI 0.39-0.75, Pperm = 0.0002) and non-alcohol abusers (OR 0.43 95 %CI 0.30-0.61, Pperm = 2.0 × 10-6), whereas no protective effects of this SNP against disease risk were observed in smokers and alcohol abusers (Pperm < 0.05).

CONCLUSIONS

We propose mechanisms underlying the observed associations between GGT1 polymorphisms and ischemic stroke risk. This pilot study is the first to demonstrate that GGT1 is a novel susceptibility gene for ischemic stroke and provides additional evidence of the genetic contribution to impaired redox homeostasis underlying disease pathogenesis.

Blood-brain barrier biomarkers

The blood-brain barrier (BBB) is a dynamic interface that regulates the exchange of molecules and cells between the brain parenchyma and the peripheral blood. The BBB is mainly composed of endothelial cells, astrocytes and pericytes. The integrity of this structure is essential for maintaining brain and spinal cord homeostasis and protection from injury or disease. However, in various neurological disorders, such as traumatic brain injury, Alzheimer's disease, and multiple sclerosis, the BBB can become compromised thus allowing passage of molecules and cells in and out of the central nervous system parenchyma. These agents, however, can serve as biomarkers of BBB permeability and neuronal damage, and provide valuable information for diagnosis, prognosis and treatment. Herein, we provide an overview of the BBB and changes due to aging, and summarize current knowledge on biomarkers of BBB disruption and neurodegeneration, including permeability, cellular, molecular and imaging biomarkers. We also discuss the challenges and opportunities for developing a biomarker toolkit that can reliably assess the BBB in physiologic and pathophysiologic states.

Determinants of Incident Atherosclerotic Cardiovascular Disease Events and All-Cause Mortality in Patients With Age-Related Macular Degeneration: Prospective Cohort Study of UK Biobank

PURPOSE

Major risk factors of atherosclerotic cardiovascular disease (ASCVD) and mortality have been well-established in the general population. Our study is aimed at assessing longitudinal relationships between ASCVD risk factors and incident ASCVD events or all-cause mortality in patients with age-related macular degeneration (AMD).

METHODS

Multivariable-adjusted Cox proportional hazards models were used to study the association between cardiovascular risk factors with adjudicated incident ASCVD events and all-cause mortality outcomes followed until 2021. A restricted cubic spline approach was utilized to assess nonlinear associations between potential cardiovascular risk factors and ASCVD or mortality.

RESULTS

We identified 3508 eligible patients [mean (SD) age = 61.45 (6.43) years; 37.76% males] with AMD at baseline. During a median follow-up year of 12, there were 110 cases of ASCVD events and 186 cases of all-cause mortality. After multivariable adjustment, each 10 U/L increase of serum gamma-glutamyl transferase level was linearly associated with incident ASCVD [hazard ratio (HR) = 1.03, 95% CI = 1.00-1.07, Pnonlinear = 0.85)] in AMD. A history of chronic kidney disease (HR = 1.94, 95% CI = 1.09-3.46) and lower vitamin D [HR = 0.98, 95% CI = 0.97-0.99, per nanomoles per liter (nmol/L)] were significantly associated with all-cause mortality in patients with AMD, with the association between vitamin D and all-cause mortality presenting a U shape (Pnonlinear = 0.02). In contrast, risk factors significantly associated with ASCVD and all-cause mortality in healthy controls differed from patients with AMD.

CONCLUSIONS

Our findings demonstrate risk factors associated with ASCVD events and all-cause mortality among individuals with AMD differed from healthy controls and suggest the long-term management of risk factors in patients with AMD.

Subclinical liver traits are associated with structural and hemodynamic brain imaging markers

BACKGROUND & AIMS

Impaired liver function affects brain health and therefore understanding potential mechanisms for subclinical liver disease is essential. We assessed the liver-brain associations using liver measures with brain imaging markers, and cognitive measures in the general population.

METHODS

Within the population-based Rotterdam Study, liver serum and imaging measures (ultrasound and transient elastography), metabolic dysfunction-associated fatty liver disease (MAFLD), non-alcoholic fatty liver disease (NAFLD) and fibrosis phenotypes, and brain structure were determined in 3493 non-demented and stroke-free participants in 2009-2014. This resulted in subgroups of n = 3493 for MAFLD (mean age 69 ± 9 years, 56% ♀), n = 2938 for NAFLD (mean age 70 ± 9 years, 56% ♀) and n = 2252 for fibrosis (mean age 65 ± 7 years, 54% ♀). Imaging markers of small vessel disease and neurodegeneration, cerebral blood flow (CBF) and brain perfusion (BP) were acquired from brain MRI (1.5-tesla). General cognitive function was assessed by Mini-Mental State Examination and the g-factor. Multiple linear and logistic regression models were used for liver-brain associations and adjusted for age, sex, intracranial volume, cardiovascular risk factors and alcohol use.

RESULTS

Higher gamma-glutamyltransferase (GGT) levels were significantly associated with smaller total brain volume (TBV, standardized mean difference (SMD), -0.02, 95% confidence interval (CI) (-0.03 to -0.01); p = 8.4·10^-4 ), grey matter volumes, and lower CBF and BP. Liver serum measures were not related to small vessel disease markers, nor to white matter microstructural integrity or general cognition. Participants with ultrasound-based liver steatosis had a higher fractional anisotropy (FA, SMD 0.11, 95% CI (0.04 to 0.17), p = 1.5·10^-3 ) and lower CBF and BP. MAFLD and NAFLD phenotypes were associated with alterations in white matter microstructural integrity (NAFLD ~ FA, SMD 0.14, 95% CI (0.07 to 0.22), p = 1.6·10^-4 ; NAFLD ~ mean diffusivity, SMD -0.12, 95% CI (-0.18 to -0.05), p = 4.7·10^-4 ) and also with lower CBF and BP (MAFLD ~ CBF, SMD -0.13, 95% CI (-0.20 to -0.06), p = 3.1·10^-4 ; MAFLD ~ BP, SMD -0.12, 95% CI (-0.20 to -0.05), p = 1.6·10^-3 ). Furthermore, fibrosis phenotypes were related to TBV, grey and white matter volumes.

CONCLUSIONS

Presence of liver steatosis, fibrosis and elevated serum GGT are associated with structural and hemodynamic brain markers in a population-based cross-sectional setting. Understanding the hepatic role in brain changes can target modifiable factors and prevent brain dysfunction.

Elevated gamma‐glutamyl transferase levels are associated with stroke recurrence after acute ischemic stroke or transient ischemic attack

Aims

Methods

Results

Conclusion

Cardiometabolic risk factors associated with brain age and accelerate brain ageing

The structure and integrity of the ageing brain is interchangeably linked to physical health, and cardiometabolic risk factors (CMRs) are associated with dementia and other brain disorders. In this mixed cross-sectional and longitudinal study (interval mean = 19.7 months), including 790 healthy individuals (mean age = 46.7 years, 53% women), we investigated CMRs and health indicators including anthropometric measures, lifestyle factors, and blood biomarkers in relation to brain structure using MRI-based morphometry and diffusion tensor imaging (DTI). We performed tissue specific brain age prediction using machine learning and performed Bayesian multilevel modeling to assess changes in each CMR over time, their respective association with brain age gap (BAG), and their interaction effects with time and age on the tissue-specific BAGs. The results showed credible associations between DTI-based BAG and blood levels of phosphate and mean cell volume (MCV), and between T1-based BAG and systolic blood pressure, smoking, pulse, and C-reactive protein (CRP), indicating older-appearing brains in people with higher cardiometabolic risk (smoking, higher blood pressure and pulse, low-grade inflammation). Longitudinal evidence supported interactions between both BAGs and waist-to-hip ratio (WHR), and between DTI-based BAG and systolic blood pressure and smoking, indicating accelerated ageing in people with higher cardiometabolic risk (smoking, higher blood pressure, and WHR). The results demonstrate that cardiometabolic risk factors are associated with brain ageing. While randomized controlled trials are needed to establish causality, our results indicate that public health initiatives and treatment strategies targeting modifiable cardiometabolic risk factors may also improve risk trajectories and delay brain ageing.

Increased concentration of serum gamma-glutamyl transferase in ischemic stroke patients

BACKGROUND:

Stroke is responsible for the largest proportion of neurological disorders causing a significant morbidity. Gamma-glutamyl transferase (GGT) enzyme has an active involvement in atherosclerosis through its role in oxidative and inflammatory mechanisms. Recent evidence suggests that serum GGT is related to the risk and prognosis of cerebrovascular diseases.

METHODS:

A total of 200 patients (100 with acute ischemic stroke and 100 without stroke) were recruited from various medical wards and medical intensive care unit. Categorical variables were compared between two groups using Chi-squared test and odds ratio (OR). Independent sample t-test was used to see to compare mean GGT level of stroke patients with control.

RESULTS:

There was no statistical difference with respect to distribution of age groups (χ² = 1.25, P = 0.741) and gender (χ² = 2.678, P = 0.1018) between cases and controls. Mean age of stroke patients (mean [M] = 61.7, standard deviation [SD] = 13.8) did not differ from controls (M = 62.2, SD = 13.6), P = 0.80. The odds of suffering from diabetes were significantly higher in stroke patients than cases (OR = 2.25, P = 0.005). Independent sample t-test found a significant difference in serum GGT level between cases (M = 57.47, SD = 11.8) and control (M = 41.72, SD = 7.5), P ≤ 0.0001.

CONCLUSIONS:

Serum GGT was significantly higher in stroke patients than age-sex-matched nonstroke patients. Association remained significant in stroke patients irrespective of age, gender, and other risk factors. Stroke patients with diabetes, hypertension, dyslipidemia, obesity, and smoking had higher level serum GGT level than those without these risk factors. Prospective cohort studies can further explore the potential of GGT as a predictor of acute ischemic stroke.

The dark side of gamma-glutamyltransferase (GGT): Pathogenic effects of an 'antioxidant' enzyme

Having long been regarded as just a member in the cellular antioxidant systems, as well as a clinical biomarker of hepatobiliary diseases and alcohol abuse, gamma-glutamyltransferase (GGT) enzyme activity has been highlighted by more recent research as a critical factor in modulation of redox equilibria within the cell and in its surroundings. Moreover, due to the prooxidant reactions which can originate during its metabolic function in selected conditions, experimental and clinical studies are increasingly involving GGT in the pathogenesis of several important disease conditions, such as atherosclerosis, cardiovascular diseases, cancer, lung inflammation, neuroinflammation and bone disorders. The present article is an overview of the laboratory findings that have prompted an evolution in interpretation of the significance of GGT in human pathophysiology.

High triglyceride-glucose index is associated with subclinical cerebral small vessel disease in a healthy population: a cross-sectional study

Background

The triglyceride-glucose (TyG) index is a marker of insulin resistance (IR) and has been associated with various metabolic syndromes, cardiovascular diseases, and cerebrovascular diseases. However, limited information is available regarding its association with subclinical cerebral small vessel disease (cSVD). In this study, we evaluated the relationship between the TyG index and cSVD, including silent brain infarcts (SBIs) and white matter hyperintensity (WMH).

Methods

We assessed health check-up participants aged 40–79 years from 2006 to 2013. The TyG index was calculated using the log scale of fasting triglyceride (mg/dL) × fasting glucose (mg/dL)/2. The Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) was also calculated. This was compared with two insulin surrogates and cSVD as another IR indicator and compared the association between two insulin surrogates and cSVD. SBI was measured for both prevalence and burden. The WMH volume was quantitatively rated using a computer-assisted semi-automated technique.

Results

A total of 2615 participants were evaluated (median age: 56 years, male sex: 53%). In the multivariable logistic regression analysis, the TyG index was seen to be associated with SBI prevalence (adjusted odds ratio: 1.39; 95% confidence interval [CI] = 1.06–1.81). Further quantitative analyses showed a positive dose–response relationship between the TyG index and SBI burden (P for trend = 0.006). In multivariable linear regression analysis, the TyG index was also found to be related to the volume of WMH (β = 0.084; 95% CI = 0.013 to 0.154). Additionally, the TyG index showed a similar or slightly stronger association with the prevalence of SBI and the volume of WMH than did HOMA-IR.

Conclusions

A high TyG index was associated with a higher prevalence and burden of cSVD in a neurologically healthy population. This marker of IR could be a convenient and useful predictor of cSVD.