Folic acid attenuates hyperhomocysteinemia-induced glomerular damage in rats

Association between serum homocysteine and postoperative acute kidney injury in patients undergoing cardiac surgery

Background: To explore the relationship between homocysteine (Hcy) and cardiac surgery-associated acute kidney injury (AKI). Methods: A total of 944 patients who underwent cardiac surgery were enrolled. The association between Hcy levels and the risk of cardiac surgery-associated AKI was evaluated. Results: A total of 135 patients were diagnosed with AKI and the prevalence of AKI was 14.30%. The AKI group had significantly higher levels of Hcy compared with the non-AKI group (16.90 vs 13.56 umol/l; p < 0.001). The incidence rates of AKI increased from 7.2% to 26.72% across increasing Hcy quartiles (p < 0.001). Compared with the first Hcy quartile group, the odds ratio of cardiac surgery-associated AKI was 4.43 (95% CI: 2.27-8.66) in the highest Hcy group. Conclusion: Elevated Hcy level is an independent risk factor for cardiac surgery-associated AKI.

Folic acid enhances the cardiovascular protective effect of amlodipine in renal hypertensive rats with elevated homocysteine

OBJECTIVES

To investigate the actions of amlodipine-folic acid (amlodipine-FA) preparation on hypertension and cardiovascular in renal hypertensive rats with hyperhomocysteinemia (HHcy), so as to provide experimental basis for clinical research of amlodipine folic acid tablets.

METHODS

Rats model of renal hypertension with HHcy were established. The rats were randomly divided into groups of model, amlodipine, folic acid (FA) and amlodipine-FA of various dosages. Normal rats were used as normal control group. Blood pressure, Hcy as well as plasma NO, ET-1 and hemodynamics were assayed. Histological alterations of heart and abdominal aorta were also examined.

RESULTS

Compared with the normal group, blood pressure, plasma Hcy, and NO of the rats in model group were significantly increased, while the plasma ET-1 was decreased. Compared with the normal group, the animals in the model group had reduced cardiac function, thickened wall of the aorta and narrowed lumen. In FA group and amlodipine group, the rat plasma NO was increased while ET-1 was decreased, the protective effect of amlodipine-FA group on endothelial cells was further enhanced. In amlodipine group, the rat hemodynamics (LVSP, LVEDP and ±dp/dt_max, et al.) and vascular damage were significantly reduced, while in amlodipine-FA group, the heart function were further improved, and myocardial and vascular hypertrophy were significantly reduced.

CONCLUSIONS

As compared to amlodipine alone, amlodipine -FA can lower both blood pressure and plasma Hcy, significantly enhancing vascular endothelial function to protect the heart and blood vessel in renal hypertensive rats with HHcy.

The Diagnostic and Prognostic Roles Played by Homocysteine and Other Aminothiols in Patients with Chronic Kidney Disease

We examined standard clinical and laboratory biochemical parameters, as well as the levels of aminothiols in the blood and urine (homocysteine (Hcy), cysteine (Cys), S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH)) via capillary electrophoresis in patients with CKD at stages II-V. Patient outcomes were assessed after five years. To complete forecasting, correlation and ROC analysis were performed. It was found that the levels of Cys and Hcy in blood plasma were earlier markers of CKD starting from stage II, while the levels of SAM and SAM/SAH in urine made it possible to differentiate between CKD at stages II and III. Blood plasma Hcy and urinary SAM and SAM/SAH correlated with mortality, but plasma Hcy concentrations were more significant. Thus, plasma Hcy, urine SAM, and SAM/SAH can be considered to be potential diagnostic and prognostic markers in patients with CKD.

Folic Acid Ameliorates Renal Injury in Experimental Obstructive Nephropathy: Role of Glycine N-Methyltransferase

Folic acid exerts both anti-inflammatory and antifibrotic effects. Glycine N-methyltransferase (GNMT), the major folic acid-binding protein in the liver, is a crucial enzyme that regulates the cellular methylation process by maintaining S-adenosylmethionine levels. However, as yet neither the therapeutic effects of folic acid in renal fibrosis nor whether GNMT is involved in these folic acid-associated mechanisms has been investigated. First, the expression of GNMT was examined in human kidneys with or without obstructive nephropathy. Later, wild-type and GNMT knockout (GNMT^-/-) mice were subjected to unilateral ureteral obstruction (UUO) and then treated with either folic acid or vehicle for 14 days. Renal tubular injury, inflammation, fibrosis, and autophagy were evaluated by histological analysis and Western blotting. We observed increased expression of GNMT in humans with obstructive nephropathy. Furthermore, UUO significantly increased the expression of GNMT in mice; in addition, it caused renal injury as well as the development of both hydronephrosis and tubular injury. These were all alleviated by folic acid treatment. In contrast, GNMT^-/- mice exhibited exacerbated UUO-induced renal injury, but the protective effect of folic acid was not observed in GNMT^-/- mice. We propose a novel role for folic acid in the treatment of renal fibrosis, which indicates that GNMT may be a therapeutic target.

The combination of Lonicerae Japonicae Flos and Forsythiae Fructus herb-pair alleviated inflammation in liver fibrosis

Objective: To explore the active components and epigenetic regulation mechanism underlying the anti-inflammatory effects of Lonicerae Japonicae Flos and Forsythiae Fructus herb-pair (LFP) in carbon tetrachloride (CCl₄)-induced rat liver fibrosis.

Methods: The main active ingredients and disease-related gene targets of LFP were determined using TCMSP and UniProt, and liver fibrosis disease targets were screened in the GeneCards database. A network was constructed with Cytoscape 3.8.0 and the STRING database, and potential protein functions were analyzed using bioinformatics analysis. Based on these analyses, we determined the main active ingredients of LFP and evaluated their effects in a CCl₄-induced rat liver fibrosis model. Serum biochemical indices were measured using commercial kits, hepatocyte tissue damage and collagen deposition were evaluated by histopathological studies, and myofibroblast activation and inflammation were detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blotting. High-performance liquid chromatography-mass spectrometry was performed to determine the levels of homocysteine, reduced glutathione, and oxidized glutathione, which are involved in inflammation and oxidative stress.

Results: The main active components of LFP were quercetin, kaempferol, and luteolin, and its main targets were α-smooth muscle actin, cyclooxygenase-2, formyl-peptide receptor-2, prostaglandin-endoperoxide synthase 1, nuclear receptor coactivator-2, interleukinβ, tumor necrosis factor α, CXC motif chemokine ligand 14, and transforming growth factor β1. A combination of quercetin, kaempferol, and luteolin alleviated the symptoms of liver fibrosis.

Conclusion: The results of this study support the role of LFP in the treatment of liver fibrosis, and reveal that LFP reduces collagen formation, inflammation, and oxidative stress. This study suggests a potential mechanism of action of LFP in the treatment of liver fibrosis.

Consumption of Cashew (Anacardium occidentale L.) Nuts Counteracts Oxidative Stress and Tissue Inflammation in Mild Hyperhomocysteinemia in Rats

Hyperhomocysteinemia (HHcy) is a methionine metabolism problem that causes a variety of inflammatory illnesses. Oxidative stress is among the processes thought to be involved in the pathophysiology of the damage produced by HHcy. HHcy is likely to involve the dysfunction of several organs, such as the kidney, liver, or gut, which are currently poorly understood. Nuts are regarded as an important part of a balanced diet since they include protein, good fatty acids, and critical nutrients. The aim of this work was to evaluate the anti-inflammatory and antioxidant effects of cashew nuts in HHcy induced by oral methionine administration for 30 days, and to examine the possible pathways involved. In HHcy rats, cashew nuts (100 mg/kg orally, daily) were able to counteract clinical biochemical changes, oxidative and nitrosative stress, reduced antioxidant enzyme levels, lipid peroxidation, proinflammatory cytokine release, histological tissue injuries, and apoptosis in the kidney, colon, and liver, possibly by the modulation of the antioxidant nuclear factor erythroid 2-related factor 2 NRF-2 and inflammatory nuclear factor NF-kB pathways. Thus, the results suggest that the consumption of cashew nuts may be beneficial for the treatment of inflammatory conditions associated with HHcy.

Serum homocysteine is associated with tubular interstitial lesions at the early stage of IgA nephropathy

BACKGROUND

The association between homocysteine (Hcy) and IgA nephropathy (IgAN) is not well understood. We aimed to investigate the relationship between Hcy and clinicopathologic features in IgAN patients.

METHODS

A total of 337 IgAN patients and 150 sex- and age- matched healthy controls were enrolled in this single-center retrospective study. According to Hcy ≤ 10 μmol/L or > 10 μmol/L, patients were divided into low and high Hcy groups. Multivariate logistic regression was performed to explore the risk factors for elevated Hcy.

RESULTS

Serum Hcy was higher in IgAN patients than in healthy controls [11.6 (9.1,15.3) vs. 8.8 (7.5,10.6) μmol/L, P < 0.001], unanimously in the subgroup of 156 patients with a normal estimated glomerular filtration rate (eGFR) (≥ 90 ml/min/1.73 m²) [9.9 (7.6,12.4) vs. 8.8 (7.5,10.6) μmol/L, P < 0.001]. Compared to the low Hcy group, serum creatinine (Scr), blood urine nitrogen (BUN), uric acid (UA), endocapillary hypercellularity (E) and tubular atrophy/interstitial fibrosis lesion (T) were higher in the high Hcy group. Hcy levels were positively correlated with Scr, BUN, UA, 24-h urine protein, and E and T lesions, but negatively correlated with eGFR and superoxide dismutase (SOD). In the subgroup with normal eGFR, patients with higher Hcy were persistent with higher Scr, BUN and T lesions. A multivariate logistic regression model showed that the risk of elevated Hcy in patients with pathological T increased by 2.87-fold. T lesions could better predict high Hcy, with an odds ratio (OR) of 14.20 in the subgroup with normal eGFR.

CONCLUSIONS

Pathologic T was an independent risk factor associated with elevated Hcy, especially at the early stage of IgAN.

Plasma Levels of Homocysteine is Associated with Liver Fibrosis in Health Check-Up Population

Object

Studies have shown a link between homocysteine (Hcy) and heart diseases, kidney diseases, cerebrovascular diseases, liver diseases, and other pathological conditions. However, the relationship between Hcy and liver fibrosis (LF) is unclear. Here, we studied the link between plasma Hcy concentration and LF.

Methods

We determined and recorded the plasma Hcy concentration, general biochemical parameters, and liver stiffness measurement (LSM) in 1582 subjects, followed by statistical data analyses.

Results

During different stages of LF, we found a considerable difference (p <0.001 unless specified) in body mass index (BMI), sex, age, Hcy, the levels of alanine transaminase (ALT), gamma-glutamyl transpeptidase (GGT; P = 0.012), triglycerides (TG; P = 0.006), low-density lipoprotein cholesterol (LDL-C), fasting blood glucose (FBS), and platelet count (PLT). There was a strong association between the plasma Hcy concentration and the serum biomarkers of LF (P <0.001) and the values of LSM (P <0.001).

Conclusion

The plasma Hcy concentration was substantially different among different stages of LF. The higher the plasma Hcy concentration, the more evident was the degree of LF.

Plasma Homocysteine Is a Predictive Factor for Accelerated Renal Function Decline and Chronic Kidney Disease in a Community-Dwelling Population

BACKGROUND

Whether elevated plasma total homocysteine (tHcy) is a risk factor for the progression of kidney disease in general population has not been well established. The purpose of this study was to investigate the prognostic properties of plasma tHcy for renal function decrement and early chronic kidney disease (CKD) in community-dwelling populations with normal renal function at baseline.

METHODS

A total of 1,426 participants were enrolled and followed for a median of 4.8 years (interquartile range, 4.5-5.2), and estimated glomerular filtration rate (eGFR) was evaluated. One main outcome was the rapid eGFR decline defined as a decline in eGFR of >3 mL/min per 1.73 m2 per year; the other was the new incidence of CKD.

RESULTS

At the end of follow-up, the incidence of rapid eGFR decline and new-onset CKD was 20.7 and 5.6%, respectively. In multivariate linear regression analysis, age, central pulse pressure, fasting blood glucose, and concentration of tHcy were independent determinants of the change in eGFR. There was a graded association between tHcy quartiles and eGFR decline. Compared with participants with the lowest quartile of tHcy levels, those with the highest quartile had significantly increased risk for rapid eGFR decline (adjusted odds ratio [aOR] = 1.81; 95% confidence interval [CI]: 1.25-2.94) and new onset of CKD (adjusted hazard ratio = 4.29; 95% CI: 1.42-12.99) after adjusting for various confounders. Similarly, significant associations were also found when baseline tHcy was classified as hyperhomocysteinemia (>15 μmol/L) versus normal tHcy level (≤15 μmol/L). However, there was only association between the change in tHcy levels and new occurrence of CKD but not with rapid eGFR decline (aOR = 0.99, p = 0.613).

CONCLUSIONS

In this prospective cohort of individuals from community-based population, elevated plasma tHcy emerged as an independent predictor of renal function decline and incident CKD, which might support selection of at-risk individuals.

Folic acid alleviates jaundice of phenylhydrazine (PHA)-induced neonatal rats by reducing Lys-homocysteinylation of albumin

Neonatal jaundice is a common symptom that occurs in neonates during the first month of their life and is generally divided into physiological and pathological subtypes. In serious cases, pathological neonatal jaundice frequently shows complications including seizures, cerebral palsy, and kernicterus. However, due to the unclear pathogenesis of pathological neonatal jaundice, effective drugs for this disease remain unsatisfied. In the present study, we first estimated the protective effects of folic acid (FA) on phenylhydrazine (PHA) or homocysteine (Hcy)-injected neonatal rats (2-3 days aged). Intriguingly, we found that FA significantly decreased the elevated total bilirubin (TBIL) and direct bilirubin (DBIL) concentration, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) activity in PHA- or Hcy-injected rats, indicating that FA improves liver functions. Meanwhile, our results also showed that the plasma Hcy level and N-homocysteinylation (N-Hcy) modification of albumin were significantly elevated in the jaundice rats, which were obviously reversed after FA administration. Furthermore, we identified a novel N-Hcy modification site K⁵⁴⁵ of human serum albumin (HSA) using LC-MS/MS, and the mutagenesis assay in HEK293 further validated these observations. Besides, we demonstrated that the N-Hcy modification of albumin functionally inhibits the bilirubin-binding ability of albumin without altering its protein level both in vitro and in vivo. Altogether, we highlight a mechanism that FA reduces the plasma Hcy level and thereby enhance the bilirubin-binding ability of albumin, which may provide a novel therapeutic strategy for the treatment of pathological neonatal jaundice.

Hydrogen sulfide therapy: a narrative overview of current research and possible therapeutic implications in future

Diabetic nephropathy is one of the most important comorbidities in the diabetic population. In China, more and more young patients are showing an increasing prevalence of diabetes. As a gas molecule, hydrogen sulfide (H2 S) has some unique chemical and physiological functions. In recent years, it has been studied in various fields. These effects are manifested in the induction of renal vasodilation and anti-renal vascular fibrosis. The ball clearing function is improved. Therefore, increasing prospective studies have focused on how H2 S protects diabetic nephropathy and how to obtain H2 S by modern means to treat diabetic nephropathy.

Folic acid ameliorates homocysteine-induced angiogenesis and portosystemic collaterals in cirrhotic rats

INTRODUCTION AND OBJECTIVES

Liver cirrhosis is characterized by increased intrahepatic resistance, splanchnic vasodilation/angiogenesis, and formation of portosystemic collateral vessels. Collaterals can cause lethal complications such as gastroesophageal variceal hemorrhage. Homocysteine is linked to vascular dysfunction and angiogenesis and higher levels have been reported in cirrhotic patients. It is also known that folic acid supplementation reverses the effects of homocysteine. However, the treatment effect in cirrhosis has yet to be investigated.

MATERIAL AND METHODS

Liver cirrhosis was induced in Sprague-Dawley rats with common bile duct ligation (CBDL). The CBDL rats randomly received (1) vehicle; (2) dl-homocysteine thiolactone (1g/kg/day); (3) dl-homocysteine thiolactone plus folic acid (100mg/kg/day); or (4) folic acid. On the 29th day, hemodynamic parameters, liver and renal biochemistry, protein expressions of proangiogenic factors, mesenteric vascular density and portosystemic shunting were evaluated.

RESULTS

In the cirrhotic rats, homocysteine increased mesenteric vascular density and the severity of shunting. It also up-regulated the protein expressions of mesenteric vascular endothelial growth factor (VEGF) and phosphorylated-endothelial nitric oxide synthase (p-eNOS). These effects were reversed by folic acid treatment (P<0.05).

CONCLUSION

Folic acid ameliorated the adverse effects of homocysteine in the cirrhotic rats, which may be related to down-regulation of the VEGF-NO signaling pathway.

NLPR3 Inflammasomes and Their Significance for Atherosclerosis

Atherosclerosis is a serious disorder, with numerous potential complications such as cardiovascular disease, ischemic stroke, and myocardial infarction. The origin of atherosclerosis is related to chronic inflammation, lipid metabolism alterations, and oxidative stress. Inflammasomes are the cytoplasmic multiprotein complex triggering the activation of inflammatory response. NLRP3 inflammasomes have a specific activation pathway that involves numerous stimuli, including a wide range of PAMPs and DAMPs. Recent studies of atherosclerotic pathology are focused on the mitochondria that appear to be a promising target for therapeutic approach development. Mitochondria are the main source of reactive oxygen species (ROS) associated with oxidative stress. It was previously shown that NLRP3 inflammasome activation results in mitochondrial damage, but the exact mechanisms of this need to be specified. In this review, we focused on the features of NLRP3 inflammasomes and their significance for atherosclerosis, especially concerning mitochondria.

Hydrogen Sulfide Protects Hyperhomocysteinemia-Induced Renal Damage by Modulation of Caveolin and eNOS Interaction

The accumulation of homocysteine (Hcy) during chronic kidney failure (CKD) can exert toxic effects on the glomeruli and tubulo-interstitial region. Among the potential mechanisms, the formation of highly reactive metabolite, Hcy thiolactone, is known to modify proteins by N-homocysteinylation, leading to protein degradation, stress and impaired function. Previous studies documented impaired nitric oxide production and altered caveolin expression in hyperhomocysteinemia (HHcy), leading to endothelial dysfunction. The aim of this study was to determine whether Hhcy homocysteinylates endothelial nitric oxide synthase (eNOS) and alters caveolin-1 expression to decrease nitric oxide bioavailability, causing hypertension and renal dysfunction. We also examined whether hydrogen sulfide (H₂S) could dehomocysteinylate eNOS to protect the kidney. WT and Cystathionine β-Synthase deficient (CBS+/-) mice representing HHcy were treated without or with sodium hydrogen sulfide (NaHS), a H₂S donor (30 µM), in drinking water for 8 weeks. Hhcy mice (CBS+/-) showed low levels of plasma H₂S, elevated systolic blood pressure (SBP) and renal dysfunction. H₂S treatment reduced SBP and improved renal function. Hhcy was associated with homocysteinylation of eNOS, reduced enzyme activity and upregulation of caveolin-1 expression. Further, Hhcy increased extracellular matrix (ECM) protein deposition and disruption of gap junction proteins, connexins. H₂S treatment reversed the changes above and transfection of triple genes producing H₂S (CBS, CSE and 3MST) showed reduction of vascular smooth muscle cell proliferation. We conclude that during Hhcy, homocysteinylation of eNOS and disruption of caveolin-mediated regulation leads to ECM remodeling and hypertension, and H₂S treatment attenuates renovascular damage.

Postnatal Administration of Homocysteine Induces Cerebellar Damage in Rats: Protective Effect of Folic Acid

A widely held view suggests that homocysteine (Hcy) can contribute to neurodegeneration through promotion of oxidative stress. There is evidence that homocysteine is toxic to cerebellar Purkinje neurons in vitro; however, in vivo action of Hcy on Purkinje cell has not been investigated so far. Thus, this study was designed to evaluate the Hcy effects on neonatal rat cerebellum and cerebellar oxidative stress. We also evaluated the folic acid effects on biochemical alterations elicited by hyperhomocysteinemia (hHcy) in the cerebellum. Group I received normal saline, group II received Hcy subcutaneously twice a day at 8-h intervals (0.3-0.6 μmol/g body weight), group III received Hcy + folic acid (0.011 μmol/g body weight), and group IV received folic acid on postnatal day (PD) 4 until 25. On day 25, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities in the cerebellum and motor cortex were assayed. Malondialdehyde (MDA) levels were also evaluated as a marker of lipid peroxidation. Rotarod and locomotor activity tests were performed in PD 25-27. Our results indicated that administration of Hcy increased plasma, cortical, and cerebellar total Hcy levels; reduced GPx activity; and induced lipid peroxidation in the cerebellum. Hcy impaired performance on the rotarod in rats. However, treatment with folic acid significantly attenuated motor coordination impairment, GPx activity reduction, the lipid peroxidation process, and significantly reduced plasma total Hcy levels. Histological analysis indicated that Hcy could decrease Purkinje cell count and folic acid prevented this toxic effect. We conclude that Hcy can induce neurotoxicity and folic acid has neuroprotective effects against cerebellar Hcy toxicity.

Peperomin E (PepE) protects against high fat diet-induced atherosclerosis in Apolipoprotein E deficient (ApoE-/-) mice through reducing inflammation via the suppression of NLRP3 signaling pathway

Peperomin E (PepE) is a type of secolignan, a major component of the plant Peperomia dindygulensis. It has been shown to exert anti-inflammatory effects; however, the effects of PepE on human atherosclerosis remain unexplored. In the study, we investigated the role of PepE in high fat diet (HFD) induced atherosclerosis using apolipoprotein E defcient (ApoE^-/-) mice. Elevated serum homocyteine, cholesterol, and triglyceride levels, accelerated progression of atherosclerosis and exacerbated macrophage infiltration into atherosclerotic lesions were observed in HFD-fed ApoE^-/- mice, which were attenuated by PepE treatment. ApoE^-/- mice fed with HFD exhibited significantly high levels of inflammation-associated regulators in artery tissues, accompanied with an increased expression of p-inhibitor of κBα (IκBα) and p-nuclear factor-kappa B (NF-κB), and the process was blocked by PepE administration. Further, we found NOD-like receptor pyrin 3 (NLRP3) inflammasome activation in artery tissues of HFD-fed ApoE^-/- mice. In vitro, silencing NLRP3 using small interfering RNA efficiently inhibited oxidized-low-density lipoprotein (oxLDL)-induced ASC and Caspase-1 expressions, interleukin (IL)-1β and IL-18 production in human aortic endothelial cells (HAECs). Further experiments indicated that NLRP3-ASC pathway was activated by reactive oxygen species (ROS), since ROS scavenger of N-acetyl-cysteine (NAC) prevented, which was further reduced by PepE addition. However, the anti-inflammatory effects of PepE on oxLDL-incubated HAECs were abolished by over-expression NLRP3. Together, our study revealed that PepE inhibited atherosclerosis development in HFD-fed ApoE^-/- mice by suppressing NLRP3 inflammatory signaling pathway, and suggested that PepE might be a potential therapeutic strategy in the prevention of atherosclerosis.

Cigarette smoking reduced renal function deterioration in hypertensive patients may be mediated by elevated homocysteine

Elevated homocysteine (HCY) and smoking are both important risk factors for hypertensive patients. However, whether they have crossing effect on renal function deterioration of hypertensive patients and what is the underlying mechanism are unclear. In the present study, 3033 participants diagnosed as essential hypertension with estimated glomerular filtration rate (eGFR)> 30 ml/min/1.73 m² from southern China were enrolled in this cross-sectional study. We collected the demographic and clinical data. In addition, the mediation effects were analyzed. The results showed that, comparing with non-smokers, smokers had significant higher levels of HCY (13.10 (11.20−16.87) vs. 11.00 (8.90−13.40) umol/L, P < 0.001) and lower eGFR (79.71 (66.83−91.05) vs. 82.89 (69.80−95.85) ml/min/1.73m², P < 0.001). HCY levels and smoking were independently associated with decreased eGFR. Meanwhile, eGFR levels were significantly negatively correlated with HCY (P < 0.001), and this correlation might be stronger in current smokers. Current smoker consuming over 20 cigarettes per day would accelerate early renal function deterioration (OR = 1.859, P = 0.019). The mediation effects analysis further showed that the association between smoking and renal function deterioration was mediated by HCY. And elevated HCY was accounted for 56.94% of the estimated causal effect of smoking on renal function deterioration in hypertensive patients. Our findings indicated that cigarette smoking was associated with renal function deterioration in hypertensive patients, and the association between cigarette smoking and renal function deterioration was probably mediated by elevated HCY. Therefore, HCY-lowering therapy may be beneficial for renal function deterioration in hypertensive smoking patients.

The Relationship between Maternal Nutrition during Pregnancy and Offspring Kidney Structure and Function in Humans: A Systematic Review

The intrauterine environment is critical for fetal growth and organ development. Evidence from animal models indicates that the developing kidney is vulnerable to suboptimal maternal nutrition and changes in health status. However, evidence from human studies are yet to be synthesised. Therefore, the aim of the current study was to systematically review current research on the relationship between maternal nutrition during pregnancy and offspring kidney structure and function in humans. A search of five databases identified 9501 articles, of which three experimental and seven observational studies met the inclusion criteria. Nutrients reviewed to date included vitamin A (n = 3), folate and vitamin B12 (n = 2), iron (n = 1), vitamin D (n = 1), total energy (n = 2) and protein (n = 1). Seven studies were assessed as being of "positive" and three of "neutral" quality. A variety of populations were studied, with limited studies investigating maternal nutrition during pregnancy, while measurements of offspring kidney outcomes were diverse across studies. There was a lack of consistency in the timing of follow-up for offspring kidney structure and/or function assessments, thus limiting comparability between studies. Deficiencies in maternal folate, vitamin A, and total energy during pregnancy were associated with detrimental impacts on kidney structure and function, measured by kidney volume, proteinuria, eGFR_cystC and mean creatinine clearance in the offspring. Additional experimental and longitudinal prospective studies are warranted to confirm this relationship, especially in Indigenous populations where the risk of renal disease is greater.

Activation of NLRP3 inflammasomes contributes to hyperhomocysteinemia-aggravated inflammation and atherosclerosis in apoE-deficient mice

Hyperhomocysteinemia (HHcy) has been shown to promote vascular inflammation and atherosclerosis, but the underlying mechanisms remain largely unknown. The NLRP3 inflammasome has been identified as the cellular machinery responsible for activation of inflammatory processes. In this study, we hypothesized that the activation of NLRP3 inflammasomes contributes to HHcy-induced inflammation and atherosclerosis. ApoE^-/- mice were fed regular chow, high-fat (HF) diet, or HF plus high methionine diet to induce HHcy. To assess the role of NLRP3 inflammasomes in HHcy-aggravated atherosclerosis, NLRP3 shRNA viral suspension was injected via tail vein to knock down the NLRP3 gene. Increased plasma levels of IL-1β and IL-18, aggravated macrophage infiltration into atherosclerotic lesions, and accelerated development of atherosclerosis were detected in HHcy mice as compared with control mice, and were associated with the activation of NLRP3 inflammasomes. Silencing the NLRP3 gene significantly suppressed NLRP3 inflammasome activation, reduced plasma levels of proinflammatory cytokines, attenuated macrophage infiltration and improved HHcy-induced atherosclerosis. We also examined the effect of homocysteine (Hcy) on NLRP3 inflammasome activation in THP-1-differentiated macrophages in the presence or absence of NLRP3 siRNA or the caspase-1 inhibitor Z-WEHD-FMK. We found that Hcy activated NLRP3 inflammasomes and promoted subsequent production of IL-1β and IL-18 in macrophages, which were blocked by NLRP3 gene silencing or Z-WEHD-FMK. As reactive oxygen species (ROS) may have a central role in NLRP3 inflammasome activation, we next investigated whether antioxidant N-acetyl-l-cysteine (NAC) prevented Hcy-induced NLRP3 inflammasome activation in macrophages. We found Hcy-induced NLRP3 inflammasome activation was abolished by NAC. Treatment with NAC in HHcy mice also suppressed NLRP3 inflammasome activation and improved HHcy-induced atherosclerosis. These data suggest that the activation of NLRP3 inflammasomes contributes to HHcy-aggravated inflammation and atherosclerosis in apoE^-/- mice. Hcy activates NLRP3 inflammasomes in ROS-dependent pathway in macrophages. These results may have implication for the treatment of HHcy-associated cardiovascular diseases.

Maternal and Fetal Folate, Vitamin B12, and Homocysteine Concentrations and Childhood Kidney Outcomes

Background

Folate, vitamin B₁₂ and homocysteine concentrations during pregnancy are important factors for early development and may persistently influence kidney function in the offspring. We examined the associations of folate, vitamin B₁₂, and homocysteine concentrations during pregnancy with kidney outcomes in school-aged children.

Study design

Population-based prospective cohort study from fetal life onwards.

Settings & participants

This study was performed among 4,226 pregnant women and their children.

Predictors

Folate, vitamin B₁₂ and homocysteine blood concentrations measured in early pregnancy (median gestational age 13.2 weeks (25th to 75th percentiles 12.2, 14.8) and at birth (cord blood).

Outcomes & measurements

At the median age of 6.0 years (25th to 75th percentiles 5.9, 6.3) we measured combined kidney volume with ultrasound, estimated glomerular filtration rate based on creatinine (eGFR_creat) and cystatin C (eGFR_cystC) concentrations and microalbuminuria.

Results

We observed that higher maternal folate concentrations were associated with larger childhood combined kidney volume, whereas higher maternal vitamin B₁₂ concentrations were associated with higher childhood eGFR_cystC (p-values <0.05). These associations were independent of homocysteine concentrations. Higher maternal homocysteine concentrations were associated with smaller combined kidney volume and lower childhood eGFR_cystC (p-values <0.05). The association of maternal homocysteine concentrations with childhood eGFR_cystC was largely explained by combined kidney volume. Higher cord blood homocysteine concentrations were associated with larger combined kidney volume and lower eGFR_cystC (p-values <0.05). Folate, vitamin B₁₂ or homocysteine concentrations were not associated microalbuminuria.

Limitations

Observational study, so causality cannot be established.

Conclusion

Our findings suggest that folate, vitamin B₁₂ and homocysteine concentrations during fetal life are associated with offspring kidney development. However, the effect sizes are small. Further studies are needed to replicate these findings and assess the causality and consequences for kidney health in later life.

High Prevalence of Hyperhomocysteinemia and Its Association with Target Organ Damage in Chinese Patients with Chronic Kidney Disease

Hyperhomocysteinemia (HHcy) is recognized as a risk factor for cardiovascular disease. However, the prevalence of HHcy and its role in association with target organ damage in patients with chronickidney disease (CKD) are not well understood. This cross-sectional study included 1042 CKD patients who were admitted to our hospital. Patients were divided into two groups: hyperhomocysteinemia and normohomocysteinemia. Multivariable linear regression analyses were used to evaluate the association between plasma homocysteine and renal/cardiovascular parameters. The prevalence of HHcy in patients with CKD was 52.78%, and the prevalence in CKD stage 1, stage 2, stage 3, stage 4 and stage 5 patients was 10.73%, 29.22%, 58.71%, 75.23% and 83.75%, respectively. Patients with HHcy had higher incidences of renal damage, left ventricular hypertrophy, left ventricular diastolic dysfunction and abnormal carotid intima-media thickness compared with patients with normohomocysteinemia (p < 0.05), while multivariable linear regression analyses showed plasma homocysteine was only associated with the estimated glomerular filtration rate (eGFR). eGFR, uric acid, albumin, gender, hemoglobin and calcium×phosphate were associated with levels of plasma homocysteine in these CKD patients. The prevalence of HHcy in Chinese patients with CKD was high, and serum homocysteine levels were associated with impaired renal function in these patients.

Hyperhomocysteinemia impairs regional blood flow: involvements of endothelial and neuronal nitric oxide

Increasing evidence support the idea that hyperhomocysteinemia (HHcy) is responsible for pathogenesis underlying cerebral, coronary, renal, and other vascular circulatory disorders and for hypertension. Impaired synthesis of nitric oxide (NO) in the endothelium or increased production of asymmetric dimethylarginine and activated oxygen species are involved in the impairment of vasodilator effects of NO. Impaired circulation in the brain derived from reduced synthesis and actions of NO would be an important triggering factor to dementia and Alzheimer's disease. Reduced actions of NO and brain hypoperfusion trigger increased production of amyloid-β that inhibits endothelial function, thus establishing a vicious cycle for impairing brain circulation. HHcy is involved in the genesis of anginal attack and coronary myocardial infarction. HHcy is also involved in renal circulatory diseases. The homocysteine (Hcy)-induced circulatory failure is promoted by methionine and is prevented by increased folic acid and vitamin B6/B12. Eliminating poor life styles, such as smoking and being sedentary; keeping favorable dietary habits; and early treatment maintaining constitutive NOS functions healthy, reducing oxidative stresses would be beneficial in protecting HHcy-induced circulatory failures.

Palm tocotrienol-rich fraction inhibits methionine-induced cystathionine β-synthase in rat liver

Oxidative stress plays an important role in cardiovascular diseases. The study investigated the effects of dietary palm tocotrienol-rich fraction on homocysteine metabolism in rats fed a high-methionine diet. Forty-two male Wistar rats were randomly assigned to six groups. Five groups were fed with high-methionine diet (1%) for 10 weeks. Groups 2 to 5 were also given dietary folate (8 mg/kg) and three doses of palm tocotrienol-rich fraction (30, 60 and 150 mg/kg) from week 6 to week 10. The last group was only given basal rat chow. High-methionine diet increased plasma homocysteine after 10 weeks, which was prevented by the supplementations of folate and high-dose palm tocotrienol-rich fraction. Hepatic S-adenosyl methionine (SAM) content was unaffected in all groups but S-adenosyl homocysteine (SAH) content was reduced in the folate group. Folate supplementation increased the SAM/SAH ratio, while in the palm tocotrienol-rich fraction groups, the ratio was lower compared with the folate. Augmented activity of hepatic cystathionine β-synthase and lipid peroxidation content by high-methionine diet was inhibited by palm tocotrienol-rich fraction supplementations (moderate and high doses), but not by folate. The supplemented groups had lower hepatic lipid peroxidation than the high-methionine diet. In conclusion, palm tocotrienol-rich fraction reduced high-methionine-induced hyperhomocysteinaemia possibly by reducing hepatic oxidative stress in high-methionine-fed rats. It may also exert a direct inhibitory effect on hepatic cystathionine β-synthase.

Homocysteine as a potential biomarker in bipolar disorders: a critical review and suggestions for improved studies

INTRODUCTION

Homocysteine levels have been associated with major depression, but associations with bipolar disorder remain less clear. Some data suggest homocysteine levels have potential as a biomarker of treatment response; however the literature is mixed.

AREAS COVERED

Oxidized forms of homocysteine can be potentially neurotoxic leading to glutamate toxicity, apoptotic transformation and neurodegenerative processes. High homocysteine may be a risk biomarker for bipolar disorders, but the empirical base remains too weak for firm conclusions. This review discusses the current literature for homocysteine levels as a biomarker.

EXPERT OPINION

It is premature to foreclose the utility of homocysteine levels as a biomarker for bipolar disorder due the methodological inadequacies in the existing literature. These methodological design issues include lack of control for the confounding variables of concurrent medication, phase of bipolar disorder, gender, age, nutritional status, thyroid, liver and renal function, smoking or lean body mass. Well-powered association studies with confounder control could help shed more light on the important clinical question of homocysteine's utility as a biomarker in bipolar disorder. Future experiments are needed to examine the outcome of interventions modulating homocysteine for treating bipolar disorder. Only prospective randomized control trials will provide definitive evidence of the utility of homocysteine as a biomarker or therapeutic target.

Nebivolol to attenuate the effects of hyper-homocysteinaemia in rats

OBJECTIVE

This study investigated the prophylactic effect of nebivolol against hyper-homocysteinaemia (hHcy) induced oxidative stress in brain, heart, liver and kidney tissues and histomorphometric changes in the thoracic aorta.

METHODS

Twenty-four adult male Wistar rats were divided into a control, nebivolol, hHcy and nebivolol+hHcy group. hHcy was induced by oral administration of L-methionine (1 g/kg/day) for 28 days. 10 mg/kg/day nebivolol was administered orally for 28 days. Malondialdehyde (MDA) and glutathione (GSH) levels and catalase (CAT) and superoxide dismutase (SOD) activities in the tissues were determined. The total cross-sectional area (TCSA), luminal cross-sectional area (LCSA) and intima-media thickness (IMT) were measured in the thoracic aorta.

RESULTS

Homocysteine (Hcy) levels were lower in the nebivolol+hHcy group than in the hHcy group. Nebivolol treatment significantly decreased high MDA levels in the brain, heart and liver tissues. The level of GSH was higher in the brain, heart and kidney tissues of the nebivolol+hHcy group (P<0.001). The activity of CAT increased only in the kidney tissue of the nebivolol+hHcy group (P<0.01), and the activity of SOD was significantly increased in all the tissues in this group. Increased TCSA and IMT in the nebivolol+hHcy group were significantly decreased after nebivolol administration. The LCSA was significantly higher in the hHcy group than the control group, probably due to outward vascular remodelling.

CONCLUSION

Nebivolol treatment may be useful in different clinical scenarios where hHcy affects physiopathological pathways.

Nod-like receptor protein 3 (NLRP3) inflammasome activation and podocyte injury via thioredoxin-interacting protein (TXNIP) during hyperhomocysteinemia

NADPH oxidase-derived reactive oxygen species (ROS) have been reported to activate NLRP3 inflammasomes resulting in podocyte and glomerular injury during hyperhomocysteinemia (hHcys). However, the mechanism by which the inflammasome senses ROS is still unknown in podocytes upon hHcys stimulation. The current study explored whether thioredoxin-interacting protein (TXNIP), an endogenous inhibitor of the antioxidant thioredoxin and ROS sensor, mediates hHcys-induced NLRP3 inflammasome activation and consequent glomerular injury. In cultured podocytes, size exclusion chromatography and confocal microscopy showed that inhibition of TXNIP by siRNA or verapamil prevented Hcys-induced TXNIP protein recruitment to form NLRP3 inflammasomes and abolished Hcys-induced increases in caspase-1 activity and IL-1β production. TXNIP inhibition protected podocytes from injury as shown by normal expression levels of podocyte markers, podocin and desmin. In vivo, adult C57BL/6J male mice were fed a folate-free diet for 4 weeks to induce hHcys, and TXNIP was inhibited by verapamil (1 mg/ml in drinking water) or by local microbubble-ultrasound TXNIP shRNA transfection. Evidenced by immunofluorescence and co-immunoprecipitation studies, glomerular inflammasome formation and TXNIP binding to NLRP3 were markedly increased in mice with hHcys but not in TXNIP shRNA-transfected mice or those receiving verapamil. Furthermore, TXNIP inhibition significantly reduced caspase-1 activity and IL-1β production in glomeruli of mice with hHcys. Correspondingly, TXNIP shRNA transfection and verapamil attenuated hHcys-induced proteinuria, albuminuria, glomerular damage, and podocyte injury. In conclusion, our results demonstrate that TXNIP binding to NLRP3 is a key signaling mechanism necessary for hHcys-induced NLRP3 inflammasome formation and activation and subsequent glomerular injury.