The restoration of hippocampal nerve de-myelination by methylcobalamin relates with the enzymatic regulation of homocysteine level in a rat model of moderate grade hepatic encephalopathy

This article describes how methylcobalamin (MeCbl) restores nerve myelination in a moderate- grade hepatic encephalopathy (MoHE) model of ammonia neurotoxicity. The comparative profiles of myelin basic protein (MBP), homocysteine (Hcy) and methionine synthase (MS: a MeCbl- dependent enzyme) activity versus nerve myelination status were studied in the hippocampus of the control, the MoHE (developed by administering 100 mg/kg bw thioacetamide i.p. for 10 days) and the MoHE rats treated with MeCbl (500 µg/kg BW i.p.) for 7 days. Compared to those of control rats, the hippocampal CA1 and CA3 regions of the MoHE rats showed significantly lower myelinated areas and MBP immunostaining. This coincided with the deranged myelin layering in TEM images, decreased MBP protein and its transcript levels in hippocampus of MoHE rats. However, all these parameters recovered to normal levels after MeCbl treatment. MeCbl is a cofactor of MS that catalyzes the conversion of Hcy to methionine as a feeder step of methylation reactions. We observed significantly increased serum and hippocampal Hcy levels in MoHE rats, however, these levels were restored to control values with a concordant activation of MS due to MeCbl treatment. A significant recovery in neurobehavioral impairments in the MoHE rats due to MeCbl treatment was also observed. These findings suggest that MoHE pathogenesis is associated with deranged nerve myelination in the hippocampus and that MeCbl treatment is able to restore it mainly by activating MS, a MeCbl-dependent Hcy-metabolizing enzyme.

Clinical significance of carotid intima-media thickness and plasma homocysteine in acute ST-segment elevation myocardial infarction

Background

Patients with acute ST-segment elevation myocardial infarction (STEMI) often have fewer identifiable traditional risk factors compared to other types of acute coronary syndrome. Therefore, it is necessary to explore more sensitive predictive models different from traditional cardiovascular scoring systems to identify high-risk populations. The retrospective case-control study aimed to investigate the predictive value of carotid intima-media thickness (CIMT) and homocysteine (Hcy) on the occurrence of STEMI.

Methods

A total of 198 patients with first STEMI were continuously selected into the observation group, who received emergency coronary angiography in Hefei Hospital Affiliated to Anhui Medical University from January 2020 to January 2022, and a total of 129 patients with chest pain and chest tightness who received coronary angiography to exclude significant coronary artery disease were selected as the control group in the above hospitals during the same period. Hcy was biochemical index determined by fasting blood sampling within 48 h after admission, while CIMT and carotid plaque was measured using ultrasound. Univariate and multivariate logistic regression analysis was used to screen out independent risk factors including Hcy, CIMT and carotid plaque of STEMI. On the basis of traditional risk factors, Hcy, CIMT and carotid plaque were introduced in order to form different combined diagnosis models. The receiver operating characteristic (ROC) curve of single indicator and multi-indicator combined diagnosis were plotted to evaluate the clinical usefulness of the study factors or diagnostic models. Based on those, a Nomogram was constructed to predict STEMI.

Results

Hcy (OR =1.161, 95% CI: 1.084-1.244, P<0.001), CIMT (OR =206.968, 95% CI: 22.375-1,914.468, P<0.001), carotid plaque (OR =2.499, 95% CI: 1.214-5.142, P=0.013) were independent risk factors for STEMI (P<0.01). ROC results suggested that the area under the curve (AUC) of Hcy was 0.729, the optimal cut-off value was 13.525 µmol/L. The AUC of CIMT is 0.763, and the optimal cut-off value is 0.875mm. Combined with the independent predictors including smoking, diabetes, high density lipoprotein cholesterol, low density lipoprotein cholesterol, Hcy, CIMT, carotid plaque, the AUC of the diagnosis model was 0.892 (95% CI: 0.856-0.928, P<0.001). Based on the above results, a Nomogram for predicting STEMI was constructed with a C-index of 0.892. The results of the H-L fitting test show that χ2=1.5049, df=2, P=0.4712; the calibration curve of the Nomogram is close to the ideal curve, and the internal validation C-index was 0.880. The clinical decision curve analysis (DCA) shows that the "nomogram line" of the model is far from the "All line" and the "None line".

Conclusions

Hcy, CIMT, and carotid artery plaque could be independent risk factors of STEMI. The inclusion of these factors in addition to traditional risk factors can more fully and accurately predict the risk of STEMI. The Nomogram based on the results of this study is feasible and can bring clinical net benefit.

Plasma cystine/methionine ratio is associated with left ventricular diastolic function in patients with heart disease

Elevated circulating homocysteine (Hcy) is a well-known risk factor for cardiovascular diseases (CVDs), including coronary artery disease (CAD) and heart failure (HF). It remains unclear how Hcy and its derivatives relate to left ventricular (LV) diastolic function. The aim of the present study was to investigate the relationship between plasma Hcy-related metabolites and diastolic dysfunction (DD) in patients with heart disease (HD). A total of 62 HD patients with preserved LV ejection fraction (LVEF ≥ 50%) were enrolled. Plasma Hcy and its derivatives were measured by liquid chromatography‒mass spectrometry (LC-MS/MS). Spearman's correlation test and multiple linear regression models were used to analyze the associations between metabolite levels and LV diastolic function. The cystine/methionine (CySS/Met) ratio was positively correlated with LV diastolic function, which was defined from the ratio of mitral inflow E and mitral e' annular velocities (E/e') (Spearman's r = 0.43, p < 0.001). When the subjects were categorized into two groups by E/e', the high-E/e' group had a significantly higher CySS/Met ratio than the low-E/e' group (p = 0.002). Multiple linear regression models revealed that the CySS/Met ratio was independently associated with E/e' after adjustment for age, sex, body mass index (BMI), diabetes mellitus, hypertension, chronic kidney disease (CKD),　hemoglobin, and lipid peroxide (LPO) {standardized β (95% CI); 0.14 (0.04-0.23); p = 0.005}. Hcy, CySS, and Met did not show a significant association with E/e' in the same models. A high plasma CySS/Met ratio reflected DD in patients with HD.

The Protective Effects of Acetazolamide Against Homocysteine-Induced Blood-Brain-Barrier Disruption by Regulating the Activation of the Wnt/β-Catenin Signaling Pathway

Acetazolamide (AZA) is a carbonic anhydrase inhibitor (CAI) with neuroprotective effects. Hyperhomocysteinemia is associated with blood-brain-barrier (BBB) disruption in brain disorders. A previous study indicated that AZA might have a new role in brain disorders. However, its function in hyperhomocysteinemia-related BBB disruption has not been reported. Here, we aim to clarify the role of AZA in homocysteine (Hcy)-mediated BBB dysfunction using both in vivo and in vitro assays. We found that AZA improved memory and cognitive function, and reduced brain edema in Hcy-stimulated hyperhomocysteinemia model rats. This protective effect of AZA on hyperhomocysteinemia rats was accompanied by improved BBB permeability and increased expression levels of the tight junction proteins, occludin, and claudin-5. The in vitro assay results show that AZA prevented Hcy-induced cell injury and attenuated the increased permeability in Hcy-treated bEnd.3 brain endothelial cells. The Hcy-induced decrease in occludin and claudin-5, and increase in MMP-2 and MMP-9 expression levels were attenuated by AZA in bEnd.3 cells. Moreover, the Hcy-induced downregulation of the Wnt/β-catenin signaling pathway in bEnd.3 cells was abolished by AZA. Inhibition of Wnt/β-catenin by ICG-001 reversed the protective effects of AZA in Hcy-treated bEnd.3 cells. We also prove that this process is mediated by WTAP. These findings suggest that acetazolamide mitigated the Hcy-induced compromised brain vascular endothelial integrity by regulating the activation of the Wnt/β-catenin signaling pathway.

Homocysteine promotes cardiac fibrosis by regulating the Akt/FoxO3 pathway

Background

Evaluated plasma homocysteine (Hcy) is an independent risk factor for cardiac fibrosis which is a common feature of cardiovascular disease, although the mechanisms are still unclear. This study aims to explore the mechanism of Hcy-induced cardiac fibrosis.

Methods

The mRNA and protein levels of Forkhead box O3 (FoxO3) and differentiation markers were detected in primary cardiac fibroblasts (CFs) after 300 µM Hcy treatment. Scratch and transwell migration assay were used to determine the effect of Hcy on proliferation and migration in CFs. The protein levels involved in the fibrotic processes in mice fed with high methionine diet (HMD) for 4 or 8 weeks were investigated by western blot. CFs were infected with FoxO3 recombinant adenovirus to explore the potential role of FoxO3 in Hcy-induced cardiac dysfunction.

Results

Hcy treatment significantly promoted the differentiation, proliferation and migration of CFs, while FoxO3 activity were decreased in CFs. In HMD hearts, the protein levels of TIMP1, Fibronectin and α-SMA were increased after 4 or 8 weeks, but the FoxO3 activity was decreased. Moreover, the HMD hearts had a higher level of Bcl2 but lower of Bax and LC3II protein. In addition, FoxO3 overexpression attenuates Hcy-induced dysfunction in CFs.

Conclusions

Hcy promotes myofibroblast activation and resistance to autophagy and apoptosis in CFs, and eventually results in cardiac fibrosis by regulating the Akt/FoxO3 pathway. Thus, FoxO3 is a promising therapeutic target to prevent cardiac remodeling.

A Cross-sectional Study on the Relationship Between Homocysteine and Lipid Profiles Among Chinese Population from Hunan

Previous studies have explored the relationship between homocystein (Hcy) and lipid profiles. However, the results from these studies have been inconsistent. The current study investigated the correlation between Hcy and lipid profiles in Chinese community-based population. The participants were composed of 4012 Chinese people aged 30-92 years old, who were recruited from rural and urban communities in the Hunan Province. Non-parametric test and logistic regression were used to examine the distribution of Hcy and lipid profiles (triglyceride [TG], total cholesterol [TC], low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C]) and the relationship between them. The median age of subjects was 54.50 years old, and 40.98% were male. Median Hcy was 13.20 μmol/L, and 35.39% had hyperhomocysteinemia (HHcy). Median TG was 1.51 mmol/L, TC was 4.77 mmol/L, LDL-C was 2.62 mmol/L, and HDL-C was 1.27 mmol/L. In multivariable logistic regression analysis, HHcy was associated with high levels of TG (OR_male = 2.240, p < 0.001; OR_female = 2.539, p < 0.001), TC (OR_male = 2.237, p < 0.001; OR_female = 2.202, p < 0.001), and LDL-C (OR_male = 1.413, p = 0.010; OR_female = 1.617, p < 0.001) in the different sexes population and low level of HDL-C in females (OR = 1.326, p = 0.023) after adjusting for confounders. HHcy was independently associated with an increasing risk of low HDL-C among females. The regression analysis showed that HHcy was also associated with hypertriglyceridemia, hypercholesterolemia, and high level of LDL-C in males and females from Chinese community-based population, which provides a basis for the treatment and prevention of abnormal lipid metabolism.

High-concentration homocysteine inhibits mitochondrial respiration function and production of reactive oxygen species in neuron cells

OBJECTIVE

Homocysteine plays critical roles in cellular redox homeostasis, and hyperhomocysteinemia has been associated with multiple diseases, including neurological disorders involving reactive oxygen species-inducing and pro-inflammatory effects of homocysteine that are related to mitochondria. This study investigated the role of homocysteine in regulating mitochondria of neuron cell lines.

METHODS

Neuron cells were pre-treated with homocysteine, and then flow cytometry was used to detect reactive oxygen species production and mitochondrial membrane potential, while Seahorse XFp Mito stress assay was used to comprehensively analyze mitochondrial function.

RESULTS

The experimental results showed that high-concentration homocysteine diminished carbonyl cyanide-4 (trifluoromethoxy) phenylhydrazone-stimulated oxygen consumption rate and mitochondrial spare respiration capacity in a time- and concentration-dependent manner, and homocysteine also reduced reactive oxygen species in cultured neuron cell lines while no changes in mitochondrial membrane potential were observed.

CONCLUSION

These results indicate that homocysteine diminished mitochondrial respiration function in neuron cell lines mediated by its reactive oxygen species-reducing effects, which may underlie the association between hyperhomocysteinemia and human diseases.

Clinical Application of LC-MS/MS in the Follow-Up for Treatment of Children with Methylmalonic Aciduria

INTRODUCTION

To explore the value of high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the follow-up for treatment of children with methylmalonic aciduria (MMA).

METHODS

Methylmalonic acid (MMA), 2-methylcitric acid (MCA) and homocysteine (Hcy) were detected by LC-MS/MS in a total of 1016 samples whose estimated 0.5th and 99.5th percentiles was taken as the reference value. The samples of children with MMA and propionic aciduria (PA) who were followed up in our hospital from January 2017 to August 2018 were collected. Samples of dried blood spots, serum, and urine were taken from each patient on the same day. The concentration of the C3 indicator in the dried blood spots was tested by MS/MS. MMA, MCA, and Hcy in the dried blood spots were quantitatively determined by LC-MS/MS, the concentrations of MMA and MCA in urine filter papers were determined by gas chromatography-mass spectrometry (GC/MS), and the concentration of homocysteine in serum was determined by enzymatic cycling assay.

RESULTS

Reference values of MMA, MCA and HCY by LC-MS/MS in the newborn population were determined. The samples from a total of 50 patients were collected, 48 were from children with MMA, and 2 were from children with PA. The first-order equation regression coefficient of MMA in the blood spots and MMA in urine was significant (P < 0.05), r² = 0.736; the first-order equation regression coefficient of MCA in bthe lood spots and MCA in urine was significant (P < 0.05), r² = 0.946; the first-order equation regression coefficient of tHcy in bthe lood spots and Hcy in serum was significant (P < 0.05), r² = 0.771.

CONCLUSION

LC-MS/MS can be used for the follow-up of children with MMA after treatment, but it is necessary to establish a reference interval suitable for the local population.

Effect of homocysteine on pregnancy: A systematic review

Research purpose was to put together the available pieces of present scientific data and to close the gap in the knowledge of Hcy levels in pregnancy and its association with some pregnancy complications. Scientific data were taken from research papers published between January 1990 and December 2017, and found on the Internet (PubMed, ClinicalKey and Embase databases) by the following tags entered in English, Russian, French and German languages: pregnancy, homocysteine, pregnancy complications, pregnancy loss, preeclampsia, intrauterine growth restriction, and placental abruption. The review showed that Hcy levels range in uncomplicated pregnancy. Upon that, Hcy level tends to decrease during the second and third trimesters. Some studies have revealed a link between polymorphism and abortion. Sufficient data were obtained indicating the relationship between HHcy and PE. Placental abruption was also associated with high Hcy levels increasing the risk 5.3-fold, but still there are data not supporting the hypothesis that Hcy levels correlate with placental abruption.

Epigallocatechin gallate protects against homocysteine-induced vascular smooth muscle cell proliferation

Epigallocatechin gallate (EGCG), a bioactive ingredient of green tea, plays a protective role in the cardiovascular system. Homocysteine (Hcy) is a major risk factor for chronic kidney disease and cardiovascular disease. The present study aimed to investigate the role of EGCG in Hcy-induced proliferation of vascular smooth muscle cells (VSMCs) and its underlying mechanism. We also explored the roles of rennin-angiotensin system (RAS), extracellular signal-regulated kinases (ERK1/2), and p38 mitogen-activated protein kinase (p38 MAPK) in this process. Human aortic smooth muscle cells (HASMCs) were treated with different drugs for different periods. The proliferation rate of HASMCs was detected using the CCK-8 and BrdU labeling assays. The Western blot assay was used to determine the expression levels of angiotensin II type 1 receptor (AT-1R), ERK1/2, and p38 MAPK. Compared with the control group, the HASMCs treated with Hcy at different doses (100, 200, 500, and 1000 µM) showed significantly increased proliferation. Hcy increased the expression of AT-1R, whereas EGCG decreased the protein expression of AT-1R. Furthermore, we found that Hcy-induced expression of p-ERK1/2 and p-p38MAPK was dependent on AT-1R. Compared with Hcy (500 µM)-treated cells, EGCG (20 µM)-treated cells showed decreased proliferation as well as expression of AT-1R, p-ERK1/2, and p-p38MAPK. In addition, HASMC proliferation was suppressed by the addition of an AT-1R blocker (olmesartan), an ERK1/2 inhibitor (PD98059), and a p38MAPK inhibitor (SB202190). EGCG can inhibit AT-1R and affect ERK1/2 and p38MAPK signaling pathways, resulting in the decrease of VSMC proliferation induced by Hcy.

Effect of Homocysteine on Voltage-Gated Sodium Channel Currents in Primary Cultured Rat Caudate Nucleus Neurons and Its Modulation by 2-Arachidonylglycerol

Homocysteine (Hcy) is an important risk factor for Alzheimer's disease (AD) and other neurodegenerative diseases. Caudate nucleus (CN), the largest nucleus in the brain, is also implicated in many neurological disorders. 2-Arachidonoylglycerol (2-AG), the most abundant endogenous cannabinoid, has been shown to exhibit neuroprotective effects from many stimuli in the central nervous system (CNS). Furthermore, it has been reported that voltage-gated sodium channels (VGSCs) are the common targets of many neuronal damages and drugs. However, it is still not clear whether VGSCs are involved in the neurotoxicity of Hcy and the neuroprotective effect of 2-AG in CN neurons. In the present study, whole-cell patch clamp recording was used to invest the action of Hcy on sodium currents in primary cultured rat CN neurons and its modulation by 2-AG. The results showed that in cultured CN neurons, pathological concentration of Hcy (100 μM) significantly increased the voltage-gated sodium currents (I(Na)) and produced a hyperpolarizing shift in the activation-voltage curve of I(Na). The further data demonstrated 2-AG is capable of suppressing elevation of Hcy-induced increase in I(Na) and hyperpolarizing shift of activation curves most partly through CB1 receptor-dependent way. Our study provides a better understanding of Hcy-associated neurological disorders and suggests the therapeutic potential for 2-AG for the treatment of these diseases.

Relationship of plasma homocysteine with lipid profile parameters in ischemic heart disease

The present study was undertaken to explore the relationship of plasma homocysteine with other biochemical parameters in ischemic heart disease. Plasma levels of total homocysteine was measured by HPLC-fluorescence detection with internal standard in 60 ischemic heart disease patients and were compared with 30 age matched normal healthy controls. The significant increase of plasma homocysteine was observed in both myocardial infarction and chronic stable ischemic heart disease patients when compared with the controls. The hyperhomocysteinemia appears be to due to increased body demand of vitamins such as folic acid, vitamin B(12), B(6), B(2) either alone or in combination to regulate normal homocysteine metabolism.