Mechanism of arterial injury exacerbated by hyperhomocysteinemia in spontaneously hypertensive rats

The role of the mitochondrial trans-sulfuration in cerebro-cardio renal dysfunction during trisomy down syndrome

One in 700 children is born with the down syndrome (DS). In DS, there is an extra copy of X chromosome 21 (trisomy). Interestingly, the chromosome 21 also contains an extra copy of the cystathionine beta synthase (CBS) gene. The CBS activity is known to contribute in mitochondrial sulfur metabolism via trans-sulfuration pathway. We hypothesize that due to an extra copy of the CBS gene there is hyper trans-sulfuration in DS. We believe that understanding the mechanism of hyper trans-sulfuration during DS will be important in improving the quality of DS patients and towards developing new treatment strategies. We know that folic acid "1-carbon" metabolism (FOCM) cycle transfers the "1-carbon" methyl group to DNA (H3K4) via conversion of s-adenosyl methionine (SAM) to s-adenosyl homocysteine (SAH) by DNMTs (the gene writers). The demethylation reaction is carried out by ten-eleven translocation methylcytosine dioxygenases (TETs; the gene erasers) through epigenetics thus turning the genes off/on and opening the chromatin by altering the acetylation/HDAC ratio. The S-adenosyl homocysteine hydrolase (SAHH) hydrolyzes SAH to homocysteine (Hcy) and adenosine. The Hcy is converted to cystathionine, cysteine and hydrogen sulfide (H2S) via CBS/cystathioneγ lyase (CSE)/3-mercaptopyruvate sulfurtransferase (3MST) pathways. Adenosine by deaminase is converted to inosine and then to uric acid. All these molecules remain high in DS patients. H2S is a potent inhibitor of mitochondrial complexes I-IV, and regulated by UCP1. Therefore, decreased UCP1 levels and ATP production can ensue in DS subjects. Interestingly, children born with DS show elevated levels of CBS/CSE/3MST/Superoxide dismutase (SOD)/cystathionine/cysteine/H2S. We opine that increased levels of epigenetic gene writers (DNMTs) and decreased in gene erasers (TETs) activity cause folic acid exhaustion, leading to an increase in trans-sulphuration by CBS/CSE/3MST/SOD pathways. Thus, it is important to determine whether SIRT3 (inhibitor of HDAC3) can decrease the trans-sulfuration activity in DS patients. Since there is an increase in H3K4 and HDAC3 via epigenetics in DS, we propose that sirtuin-3 (Sirt3) may decrease H3K4 and HDAC3 and hence may be able to decrease the trans-sulfuration in DS. It would be worth to determine whether the lactobacillus, a folic acid producing probiotic, mitigates hyper-trans-sulphuration pathway in DS subjects. Further, as we know that in DS patients the folic acid is exhausted due to increase in CBS, Hcy and re-methylation. In this context, we suggest that folic acid producing probiotics such as lactobacillus might be able to improve re-methylation process and hence may help decrease the trans-sulfuration pathway in the DS patients.

Comparison of the antihypertensive effects of folic acid and resveratrol in spontaneously hypertensive rats combined with hyperhomocysteinemia

Objectives

Studies have found that both folic acid and resveratrol have potential benefits in reducing complications of hypertension. The aim of this study was to compare the effects of resveratrol and folic acid on blood pressure in spontaneously hypertensive rats combined with hyperhomocystinemia, and to explore their potential mechanisms.

Methods

Twenty-four male specific pathogen free (SPF) SPF grade spontaneously hypertensive rats were randomly divided into four groups: the SHR group, the hypertension combined with hyperhomocystinemia group (SHR + HHcy), the folic acid intervention group (SHR + HHcy + FA), and the resveratrol intervention group (SHR + HHcy + Res). The rat model of hypertension combined with hyperhomocystinemia was constructed, and then folic acid or resveratrol were given by gavage. Rat tail artery blood pressure, serum homocysteine concentration, superoxide dismutase activity, malondialdehyde levels, and mRNA transcription and protein expression of endothelial nitric oxide synthase and angiotensin II were detected.

Result

Compared with the SHR group, the SHR + HHcy group significantly increased hyperhomocystinemia and malondialdehyde levels, and inhibited superoxide dismutase activity and endothelial nitric oxide synthase expression. Compared with the SHR + HHcy group, the SHR + HHcy + FA group significantly reduced hyperhomocystinemia and malondialdehyde levels, and significantly increased superoxide dismutase activity and endothelial nitric oxide synthase expression; the SHR + HHcy + Res group also inhibited malondialdehyde levels and promoted endothelial nitric oxide synthase expression, but did not reduce hyperhomocystinemia. When comparing between the SHR + HHcy + FA group and the SHR + HHcy + Res group, folic acid significantly decreased hyperhomocystinemia and increased superoxide dismutase activity, while resveratrol significantly decreased blood pressure and angiotensin II expression.

Conclusions

Both resveratrol and folic acid reduced the levels of oxidative stress and promoted the expression of endothelial nitric oxide synthase in SHRs combined with hyperhomocystinemia. Moreover, resveratrol exhibited superior antihypertensive efficacy compared to folic acid, potentially attributed to its ability to inhibit angiotensin II expression.

Expression and clinical significance of RBBP4 gene in lower-grade glioma: An integrative analysis

This study investigated the expression pattern of retinoblastoma binding protein 4 (RBBP4) gene in glioma and explored its associations with clinicopathologic characteristics and prognosis of patients. Data retrieved from the GEPIA, CGGA, HPA and TIMER databases were processed to analyze RBBP4 expression in glioma and investigate its relationship with clinicopathologic characteristics, tumor immune infiltration and prognosis in glioma patients. Immunohistochemistry was applied to determine the expression of RBBP4 protein in glioma tissue. Additionally, the Coexpedia database was visited to identify co-expressed genes for RBBP4 gene, while the Cytoscape software was run to visualize the enriched GO entries and KEGG pathways of these co-expressed genes. The expression levels of RBBP4 in lower-grade glioma (LGG) and glioblastoma (GBM) tissues were markedly elevated when compared to normal tissues (both p < 0.05). The up-regulation of RBBP4 expression was associated with an increase in WHO grade (II-IV), wild-type IDH, and 1p/19q non-codeletion (all p < 0.05). Multi-variate Cox regression analysis showed that both increased abundance of infiltrating macrophages and up-regulated RBBP4 expression independently predicted poor survival outcomes in LGG patients (both p < 0.05). Furthermore, RBBP4 expression exhibited significant positive correlations with the abundance of infiltrating B cell, CD8+ T cell, CD4+ T cell, macrophage, neutrophil, and dendritic cell in LGG (all p < 0.05). Functional enrichment analyses indicated that the co-expressed genes associated with RBBP4 were highly involved in pathways such as the p53 signaling pathway, cell cycle, DNA replication, glutathione metabolism, as well as biological processes including cell cycle process, DNA replication, and DNA repair. High levels of RBBP4 are predictive for the poor survival outcome of LGG patients. RBBP4 gene, therefore, is expected to be a potential biomarker for prognosis of LGG and a target for immunotherapy.

H-type hypertension is a risk factor for chronic total coronary artery occlusion: a cross-sectional study from southwest China

BACKGROUND

Chronic total coronary occlusion (CTO) is serious and the "last bastion" of percutaneous coronary intervention. Hypertension and hyperhomocysteinemia (HHCY) are synergistic and significantly increase cardiovascular event risk. The relationship between H-type hypertension and CTO remains unclear; thus, this cross-sectional study investigated this potential association.

METHODS

Between January 2018 and June 2022, 1446 individuals from southwest China were recruited to participate in this study. CTO was defined as complete coronary artery occlusion persisting for over three months. H-type hypertension was defined as hypertension with plasma homocysteine levels ≥ 15 µmol/L. Multivariate logistic regression models were applied to assess the association between H-type hypertension and CTO. Receiver operating characteristic (ROC) curves were generated to determine the accuracy of H-type hypertension in predicting CTO.

RESULTS

Of the 1446 individuals, 397 had CTO, and 545 had H-type hypertension. After multivariate adjustment, the odds ratio (OR) for CTO in individuals with H-type hypertension was 2.3-fold higher (95% CI 1.01-5.26) than that in healthy controls. The risk of CTO is higher in individuals with H-type hypertension than in those with isolated HHCY and hypertension. The area under the ROC curve for CTO was 0.685 (95% CI, 0.653-0.717) for H-type hypertension.

CONCLUSIONS

In southwest China, H-type hypertension is significantly related to the occurrence of CTO.

TRIAL REGISTRATION

This retrospective study was registered with the Chinese Clinical Trials Registry ( http://www.chictr.org.cn , ChiCTR2100050519.2.2).