Hydrogen Sulfide Ameliorates Heart Aging by Downregulating Matrix Metalloproteinase-9.

PURPOSE: Aging contributes significantly to cardiovascular diseases and cardiac dysfunction, leading to the upregulation of matrix metalloproteinase-9 (MMP-9) in the heart and a significant decrease in hydrogen sulfide (H2S) content, coupled with impaired cardiac diastolic function. This study explores whether supplementing exogenous hydrogen sulfide during aging ameliorates the decline in H2S concentration in the heart, suppresses MMP-9 expression, and improves the age-associated impairment in cardiac morphology and function. METHODS: We collected plasma from healthy individuals of different ages to determine the relationship between aging and H2S and MMP-9 levels through Elisa detection and liquid chromatography-tandem mass spectrometry (LC/MC) detection of plasma H2S content. Three-month-old mice were selected as the young group, while 18-month-old mice were selected as the old group, and sodium hydrosulfide (NaHS) was injected intraperitoneally from 15 months old until 18 months old as the old + NaHS group. Plasma MMP-9 content was detected using Elisa, plasma H2S content, cardiac H2S content, and cystathionine gamma-lyase (CSE) activity were detected using LC/MC, and cardiac function was detected using echocardiography. Heart structure was assessed using hematoxylin and eosin staining, Masone staining was used to detect the degree of cardiac fibrosis, while western blot was used to detect the expression of MMP-9, CSE, and aging marker proteins. Knockdown of MMP-9 and CSE in H9c2 cells using small interfering RNA was carried out to determine the upstream-downstream relationship between MMP-9 and CSE. RESULTS: H2S content in the plasma of healthy individuals decreases with escalating age, whereas MMP-9 level rises with age progression. Aging leads to a decrease in H2S levels in the heart and plasma of mice, severe impairment of cardiac diastolic function, interstitial relaxation, and fibrosis of the heart. Supplementing with exogenous H2S can improve these phenomena. CONCLUSION: H2S maintains the structure and function of the heart by inhibiting the expression of MMP-9 during the aging process.

Assessing the effects of tempol on renal fibrosis, inflammation, and oxidative stress in a high-salt diet combined with 5/6 nephrectomy rat model: utilizing oxidized albumin as a biomarker.

BACKGROUND: Oxidative stress has been implicated in the pathogenesis of chronic kidney disease (CKD), prompting the exploration of antioxidants as a potential therapeutic avenue for mitigating disease progression. This study aims to investigate the beneficial impact of Tempol on the progression of CKD in a rat model utilizing oxidized albumin as a biomarker. METHODS: After four weeks of treatment, metabolic parameters, including body weight, left ventricle residual weight, kidney weight, urine volume, and water and food intake, were measured. Systolic blood pressure, urinary protein, oxidized albumin level, serum creatinine (Scr), blood urea nitrogen (BUN), 8-OHdG, TGF-ß1, and micro-albumin were also assessed. Renal fibrosis was evaluated through histological and biochemical assays. P65-NF-κB was quantified using an immunofluorescence test, while Smad3, P65-NF-κB, and Collagen I were measured using western blot. TNF-α, IL-6, MCP-1, TGF-ß1, Smad3, and P65-NF-κB were analyzed by RT-qPCR. RESULTS: Rats in the high-salt diet group exhibited impaired renal function, characterized by elevated levels of blood urea nitrogen, serum creatinine, 8-OHdG, urine albumin, and tubulointerstitial damage, along with reduced body weight. However, these effects were significantly ameliorated by Tempol administration. In the high-salt diet group, blood pressure, urinary protein, and oxidized albumin levels were notably higher compared to the normal diet group, but Tempol administration in the treatment group reversed these effects. Rats in the high-salt diet group also displayed increased levels of proinflammatory factors (TNF-α, IL-6, MCP1) and profibrotic factors (NF-κB activation, Collagen I), elevated expression of NADPH oxidation-related subunits (P65), and activation of the TGF-ß1/Smad3 signaling pathway. Tempol treatment inhibited NF-κB-mediated inflammation and TGF-ß1/Smad3-induced renal fibrosis signaling pathway activation. CONCLUSION: These findings suggest that Tempol may hold therapeutic potential for preventing and treating rats undergoing 5/6 nephrectomy. Further research is warranted to elucidate the mechanisms underlying Tempol's protective effects and its potential clinical applications. Besides, there is a discernible positive relationship between oxidized albumin and other biomarkers, such as 8-OHG, urinary protein levels, mALB, Scr, BUN, and TGF-ß1 in a High-salt diet combined with 5/6 nephrectomy rat model. These findings suggest the potential utility of oxidized albumin as a sensitive indicator for oxidative stress assessment.

Hydrogen sulfide ameliorates endothelial dysfunction in aging arteries by regulating ferroptosis.

Aging causes vascular endothelial dysfunction. We aimed to investigate the causes of vascular endothelial dysfunction during aging using plasma and renal arteries from patients who underwent nephrectomy and animal models. The results showed that the endogenous H2S-producing enzyme cystathione-γ-lyase (CSE) protein expression was downregulated in renal artery tissue, plasma H2S levels were reduced. Moreover, elevated lipid peroxidation and iron accumulation levels led to ferroptosis and endothelial diastolic function in the renal arteries was impaired in the elderly group. H2S enhanced the endogenous CSE expression in the elderly group, promoted endogenous H2S production, decreased lipid peroxide expression, and inhibited ferroptosis, which in turn improved vascular endothelial function in the elderly group. In animal models, we also observed the same results. In addition, we applied NaHS, Ferrostatin-1 (ferroptosis inhibitor) and erastin (ferroptosis inducer) to incubate renal arteries of SD rats. The results showed that NaHS enhanced ferroptosis related proteins expression, inhibited ferroptosis and improved vascular endothelial function. We demonstrated that endothelial dysfunction associated with aging is closely related to reduced endogenous H2S levels and ferroptosis in vascular endothelial cells. Notably, H2S reduced lipid peroxidation levels in vascular endothelial cells, inhibited ferroptosis in vascular endothelial cells, and improved endothelial dysfunction.

Hydrogen sulfide ameliorates senescence in vascular endothelial cells through ameliorating inflammation and activating PPARδ/SGLT2/STAT3 signaling pathway.

Mounting evidence demonstrates that hydrogen sulfide (H 2S) promotes anti-inflammatory molecules and inhibits pro-inflammatory cytokines in endothelial cells (ECs). This study aims to investigate the favorable action of H 2S on endothelial function in senescence by inhibiting the production of inflammatory molecules. Senescent ECs exhibit a reduction in H 2S, endothelial nitric oxide synthase (eNOS) and peroxisome proliferator-activated receptor δ (PPARδ), coupled with increased inflammatory molecules, sodium glucose transporter type 2 (SGLT2) and phosphorylation of STAT3, which could be reversed by the administration of a slow but sustained release agent of H 2S, GYY4137. Decreased production of eNOS and upregulated p-STAT3 and SGLT2 levels in senescent ECs are reversed by replenishment of the SGLT2 inhibitor EMPA and the PPARδ agonist GW501516. The PPARδ antagonist GSK0660 attenuates eNOS expression and increases the production of p-STAT3 and SGLT2. However, supplementation with GYY4137 has no beneficial effect on GSK0660-treated ECs. GYY4137, GW501516 and EMPA preserve endothelial-dependent relaxation (EDR) in D-gal-treated aortae, while GSK0660 destroys aortic relaxation even with GYY4137 supplementation. In summary, senescent ECs manifest aggravated the expressions of the inflammatory molecules SGLT2 and p-STAT3 and decreased the productions of PPARδ, eNOS and CSE. H 2S ameliorates endothelial dysfunction through the anti-inflammatory effect of the PPARδ/SGLT2/p-STAT3 signaling pathway in senescent ECs and may be a potential therapeutic target for anti-ageing treatment.

Deletion of Ppard in CD11c+ cells attenuates atherosclerosis in ApoE knockout mice.

Ppardδ, one of the lipid-activated nuclear receptor expressed in many cell types to activate gene transcription, also regulates cellular functions other than lipid metabolism. The mechanism regulating the function of antigen-presenting cells during the development of atherosclerosis is not fully understood. Here we aimed to study the involvement of PPARδ in CD11c+ cells in atherosclerosis. We used the Cre-loxP approach to make conditional deletion of Ppard in CD11c+ cells in mice on Apoe-/- background, which were fed with high cholesterol diet to develop atherosclerosis. Ppard deficiency in CD11c+ cells attenuated atherosclerotic plaque formation and infiltration of myeloid-derived dendritic cells (DCs) and T lymphocytes. Reduced lesion was accompanied by reduced activation of dendritic cells, and also a reduction of activation and differentiation of T cells to Th1 cells. In addition, DC migration to lymph node was also attenuated with Ppard deletion. In bone marrow-derived DCs, Ppard deficiency reduced palmitic acid-induced upregulation of co-stimulatory molecules and pro-inflammatory cytokine IL12 and TNFα. Our results indicated PPARδ activation by fatty acid resulted in the activation of myeloid DCs and subsequent polarization of T lymphocytes, which contributed to atherosclerosis in Apoe-/- mice. These findings also reveal the potential regulatory role of PPARδ in antigen presentation to orchestrate the immune responses during atherosclerosis.

Trends in the clinical features of amyotrophic lateral sclerosis: A 14-year Chinese cohort study.

BACKGROUND AND PURPOSE: The aim was to determine the transitional patterns in the clinical characteristics, treatments and comorbidities in amyotrophic lateral sclerosis (ALS) patients over the past 14 years using data from a large clinical cohort in mainland China. METHODS: Sporadic ALS patients who visited the Peking University Third Hospital from January 2005 to December 2018 were included in this study. The 14 years were divided into three periods, and changes in the baseline characteristics of the participants were analyzed at 5-year intervals. RESULTS: In total, 3410 patients with sporadic ALS were recruited: 2181 were men and 1229 were women. The proportion of patients with bulbar-onset ALS increased from 13.0% in 2005-2009 to 19.5% in 2015-2018 (p < 0.001). The mean (standard deviation) age at onset increased from 49.5 (11.4) years in 2005-2009 to 53.0 (11.0) years in 2015-2018 (p < 0.001). ALS patients with diabetes or hypertension showed a delay in ALS onset, and the delay was even more apparent when the patients had both comorbidities. The proportion of riluzole users in 2015-2018 was approximately 2.5-fold of that in 2005-2009 (p < 0.001). CONCLUSIONS: In the context of a lack of clinical data on ALS in mainland China, this study evaluated a large cohort of patients diagnosed over a 14-year period. The age at onset and percentage of patients who used riluzole both increased over the study period. Additionally, it was found that patients with comorbidities such as diabetes and hypertension had a delayed age of ALS onset.

ADP-ribosylation factors improve biomass yield and salinity tolerance in transgenic switchgrass (Panicum virgatum L.).

KEY MESSAGE: PvArf regulate proline biosynthesis by physically interacting with PvP5CS1 to improve salt tolerance in switchgrass. The genetic factors that contribute to stress resiliency are yet to be determined. Here, we identified three ADP-ribosylation factors, PvArf1, PvArf-B1C, and PvArf-related, which contribute to salinity tolerance in transgenic switchgrass (Panicum virgatum L.). Switchgrass overexpressing each of these genes produced approximately twofold more biomass than wild type (WT) under normal growth conditions. Transgenic plants accumulated modestly higher levels of proline under normal conditions, but this level was significantly increased under salt stress providing better protection to transgenic plants compared to WT. We found that PvArf genes induce proline biosynthesis genes under salt stress to positively regulate proline accumulation, and further demonstrated that PvArf physically interact with PvP5CS1. Moreover, the transcript levels of two key ROS-scavenging enzyme genes were significantly increased in the transgenic plants compared to WT, leading to reduced H2O2 accumulation under salt stress conditions. PvArf genes also protect cells against stress-induced changes in Na+ and K+ ion concentrations. Our findings uncover that ADP-ribosylation factors are key determinants of biomass yield in switchgrass, and play pivotal roles in salinity tolerance by regulating genes involved in proline biosynthesis.

Trimethylamine-N-oxide aggravated the sympathetic excitation in D-galactose induced aging rats by down-regulating P2Y12 receptor in microglia.

This study aimed to determine whether trimethylamine N-oxide (TMAO) was involved in sympathetic activation in aging and the underlying mechanisms. Our hypothesis is TMAO reduces P2Y12 receptor (P2Y12R) and induces microglia-mediated inflammation in the paraventricular nucleus (PVN), then leading to sympathetic activation in aging. This study involved 18 young adults and 16 old adults. Aging rats were established by injecting D-galactose (D-gal, 200 mg/kg/d) subcutaneously for 12 weeks. TMAO (120 mg/kg/d) or 1% 3, 3-dimethyl-l-butanol (DMB) was administrated via drinking water for 12 weeks to investigate their effects on neuroinflammation and sympathetic activation in aging rats. Plasma TMAO, NE and IL-1ß levels were higher in old adults than in young adults. In addition, standard deviation of all normal to normal intervals (SDNN) and standard deviation of the average of normal to normal intervals (SDANN) were lower in old adults and negatively correlated with TMAO, indicating sympathetic activation in old adults, which is associated with an increase in TMAO levels. Treatment of rats with D-gal showed increased senescence-associated protein levels and microglia-mediated inflammation, as well as decreased P2Y12R protein levels in PVN. Plasma TMAO, NE and IL-1ß levels were increased, accompanied by enhanced renal sympathetic nerve activity (RSNA). While TMAO treatment exacerbated the above phenomenon, DMB mitigated it. These findings suggest that TMAO contributes to sympathetic hyperactivity in aging by downregulating P2Y12R in microglia and increasing inflammation in the PVN. These results may provide promising new target for the prevention and treatment of aging and aging-related diseases.

Decreased levels of hydrogen sulfide in the hypothalamic paraventricular nucleus contribute to sympathetic hyperactivity induced by cerebral infarction.

Paroxysmal sympathetic hyperactivity (PSH) is a common clinical feature secondary to ischemic stroke (IS), but its mechanism is poorly understood. We aimed to investigate the role of H2S in the pathogenesis of PSH. IS patients were divided into malignant (MCI) and non-malignant cerebral infarction (NMCI) group. IS in rats was induced by the right middle cerebral artery occlusion (MCAO). H2S donor (NaHS) or inhibitor (aminooxy-acetic acid, AOAA) were microinjected into the hypothalamic paraventricular nucleus (PVN). Compared with the NMCI group, patients in the MCI group showed PSH, including tachycardia, hypertension, and more plasma norepinephrine (NE) that was positively correlated with levels of creatine kinase, glutamate transaminase, and creatinine respectively. The 1-year survival rate of patients with high plasma NE levels was lower. The hypothalamus of rats with MCAO showed increased activity, especially in the PVN region. The levels of H2S in PVN of the rats with MCAO were reduced, while the blood pressure and renal sympathetic discharge were increased, which could be ameliorated by NaHS and exacerbated by AOAA. NaHS completely reduced the disulfide bond of NMDAR1 in PC12 cells. The inhibition of NMDAR by MK-801 microinjected in PVN of rats with MCAO also could lower blood pressure and renal sympathetic discharge. In conclusion, PSH may be associated with disease progression and survival in patients with IS. Decreased levels of H2S in PVN were involved in regulating sympathetic efferent activity after cerebral infarction. Our results might provide a new strategy and target for the prevention and treatment of PSH.

A chromosome-level genome assembly for Onobrychis viciifolia reveals gene copy number gain underlying enhanced proanthocyanidin biosynthesis.

Sainfoin (Onobrychis viciifolia), which belongs to subfamily Papilionoideae of Leguminosae, is a vital perennial forage known as "holy hay" due to its high contents of crude proteins and proanthocyanidins (PAs, also called condensed tannins) that have various pharmacological properties in animal feed, such as alleviating rumen tympanic disease in ruminants. In this study, we select an autotetraploid common sainfoin (2n = 4x = 28) and report its high-quality chromosome-level genome assembly with 28 pseudochromosomes and four haplotypes (~1950.14 Mb, contig N50 = 10.91 Mb). The copy numbers of genes involved in PA biosynthesis in sainfoin are significantly greater than those in four selected Fabales species, namely, autotetraploid Medicago sativa and three other diploid species, Lotus japonicus, Medicago truncatula, and Glycine max. Furthermore, gene expansion is confirmed to be the key contributor to the increased expression of these genes and subsequent PA enhancement in sainfoin. Transcriptomic analyses reveal that the expression of genes involved in the PA biosynthesis pathway is significantly increased in the lines with high PA content compared to the lines with medium and low PA content. The sainfoin genome assembly will improve our understanding of leguminous genome evolution and biosynthesis of secondary metabolites in sainfoin.

Exercise protects vascular function by countering senescent cells in older adults.

Blood vessels are key conduits for the transport of blood and circulating factors. Abnormalities in blood vessels promote cardiovascular disease (CVD), which has become the most common disease as human lifespans extend. Aging itself is not pathogenic; however, the decline of physiological and biological function owing to aging has been linked to CVD. Although aging is a complex phenomenon that has not been comprehensively investigated, there is accumulating evidence that cellular senescence aggravates various pathological changes associated with aging. Emerging evidence shows that approaches that suppress or eliminate cellular senescence preserve vascular function in aging-related CVD. However, most pharmacological therapies for treating age-related CVD are inefficient. Therefore, effective approaches to treat CVD are urgently required. The benefits of exercise for the cardiovascular system have been well documented in basic research and clinical studies; however, the mechanisms and optimal frequency of exercise for promoting cardiovascular health remain unknown. Accordingly, in this review, we have discussed the changes in senescent endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) that occur in the progress of CVD and the roles of physical activity in CVD prevention and treatment.

A two-sample Mendelian randomization analysis of modifiable risk factors and intracranial aneurysms.

We aimed to investigate the causality between potentially modifiable risk factors and the risk of intracranial aneurysm. Genetic instruments for 51 modifiable factors and intracranial aneurysm data were obtained from recently published genome-wide association studies. We applied two-sample Mendelian randomization methods to investigate their causal relationships. Genetically predicted cigarettes per day, smoking initiation, systolic blood pressure, hypertension and body fat percentage were significantly associated with an increased risk of intracranial aneurysm [odds ratios (OR) 2.67, 95% confidence interval (CI) 1.75-4.07, p = 5.36 × 10-6, OR 1.53, 95% CI 1.32-1.77, p = 9.58 × 10-9, OR 1.05, 95% CI 1.02-1.08, p = 1.18 × 10-3, OR 1.65, 95% CI 1.19-2.28, p = 2.56 × 10-3 and OR 1.29, 95% CI 1.11-1.52, p = 1.33 × 10-3, respectively]. Type 2 diabetes mellitus was significantly associated with a decreased risk of intracranial aneurysm (OR 0.89, 95% CI 0.83-0.95, p = 8.54 × 10-4). Body fat percentage was significantly associated with subarachnoid haemorrhage (p = 5.70 × 10-5). This study provided genetic evidence of causal effects of smoking, blood pressure, type 2 diabetes mellitus and obesity on the risk of intracranial aneurysm.

Hydrogen sulfide ameliorated preeclampsia via suppression of toll-like receptor 4-activated inflammation in the rostral ventrolateral medulla of rats.

This study aims to determine whether toll-like receptor 4 (TLR4)-mediated inflammation in rostral ventrolateral medulla (RVLM) causes sympathetic overactivity leading to preeclampsia (PE) and if TLR4 inhibition with hydrogen sulfide (H2S) would reduce PE severity. Thirty patients with PE and 30 pregnant controls were involved. PE in rats was induced through deoxycorticosterone acetate and normal saline. NaHS (donor of H2S), lipopolysaccharide (LPS) (TLR4 agonist), and TAK-242 (TLR4 inhibitor) were injected in lateral cerebral ventricle to investigate their effect on microglia-mediated inflammation in RVLM, sympathetic activation, and PE symptoms. In patients with PE, plasma levels of NE, TNF-α, and interleukin-1ß were high compared with those of controls, whereas levels of H2S were low. Rats with PE showed an increased amount of renal sympathetic nerve activity and plasma levels of NE, with decreased H2S levels in RVLM. Microglia-mediated inflammation was observed in the RVLM of PE rats. Central infusion of LPS in pregnant rats induced microglia-mediated inflammation, sympathetic nervous tension, and PE-like symptoms, whereas TAK-242 reduced PE symptoms. NaHS treatment lessened microglia-mediated inflammation in the RVLM, sympathetic tension, and symptoms of PE both in PE rats and LPS-treating pregnant rats.These results suggest that inflammation in the RVLM caused by microglial activation might contribute to the progression of PE via an overactive sympathetic system. H2S could reduce PE via inhibiting inflammation in the RVLM. These results might provide a new target for the treatment of PE.

CT-Visible Convexity Subarachnoid Hemorrhage Predicts Early Recurrence of Lobar Hemorrhage.

Background and Purpose: Convexity subarachnoid hemorrhage (cSAH) may predict an increased recurrence risk in cerebral amyloid angiopathy (CAA)-related intracerebral hemorrhage (ICH) survivors. We aimed to investigate whether cSAH detected on CT was related to early recurrence in patients with ICH related to CAA. Methods: We analyzed data from consecutive lobar ICH patients diagnosed as probable or possible CAA according to the Boston criteria using the method of cohort study. Demographic and clinical data, ICH recurrence at discharge and within 90 days were collected. The association between cSAH detected on CT and early recurrent ICH was analyzed using multivariable logistic regression. Results: A total of 197 cases (74 [66-80] years) were included. cSAH was observed on the baseline CT of 91 patients (46.2%). A total of 5.1% (10/197) and 9.5% (17/179) of patients experienced ICH recurrence within 2 weeks and 90 days, respectively. The presence of cSAH was related to recurrence within 2 weeks (OR = 5.705, 95%CI 1.070-30.412, P = 0.041) after adjusting for hypertension, previous symptomatic ICH and anticoagulant use. The presence of cSAH was related to recurrence within 90 days (OR 5.473, 95%CI 1.425-21.028, P = 0.013) after adjusting for hypertension, previous symptomatic ICH and intraventricular hemorrhage. The similar results were obtained in other models using different methods to select adjusting variables. Conclusion: In patients with lobar ICH related to CAA, 5.1% and 9.5% of them experienced ICH recurrence within 2 weeks and 90 days, respectively. CT-visible cSAH was detected in 46.2% of patients and indicates an increased risk for early recurrent ICH.

Rare and Common Variants in COL4A1 in Chinese Patients With Intracerebral Hemorrhage.

Here, we screened the COL4A1 variants in Chinese intracerebral hemorrhage (ICH) patients to summarize the relationship between the variants and clinical characteristics. Targeted sequencing of a 65-gene panel including COL4A1 was performed to detect all the coding regions and ±10-bp splicing sites. In total, 568 patients were included. Regarding rare nonsynonymous variants with a minor allele frequency (MAF) <0.5%, 6 missense variants and five suspicious splice site variants, absent in 573 healthy controls, were found in 11 patients. The subgroup carrying rare variants did not show specific phenotype compared with non-variant carriers. For the single nucleotide polymorphism (SNP) loci with an MAF> 5%, we did not find a significant association between the allele or genotype distribution of the SNP loci and the risk of ICH. Rs3742207 was nominally associated with death at 1-year follow-up (p = 0.02027, OR 1.857, 95% CI 1.101-3.133) after adjusted by age, hypertension history, hematoma volume and recurrent ICH history. Nevertheless, after the Bonferroni correction, the association was no longer significant. In conclusion, rare nonsynonymous variants in COL4A1 were identified in 1.94% (11/568) of Chinese ICH patients, while rs3742207 maybe indicate a worse prognosis of ICH.

Integrated morphological, physiological and omics analyses reveal the arylalkylamine N-acetyltransferase (AANAT) gene contributing to growth, flowering and defence in switchgrass (Panicum virgatum L.).

Arylalkylamine N-acetyltransferase (AANAT) catalyses the acetylation of serotonin, a rate-limiting process in melatonin biosynthesis. To obtain better insight into the underlying mechanism of AANAT's actions in switchgrass growth, flowering and defence, we performed integrated morphological, physiological and omics analyses between overexpressed oAANAT transgenic lines in wild-type and transgenic control (expressing only the empty vector) plants. We showed that oAANAT played pivotal roles in modulating plant growth through its regulation of cell elongation, and regulating flowering through photoperiod and GA pathways. In relation to photosynthesis, oAANAT promoted photosynthetic efficiency primarily through regulating leaf anatomical structures, stomatal development and chlorophyll metabolism. Moreover, oAANAT overexpression can trigger a number of defence responses or strategies, including antioxidant enzymatic properties, non-enzymatic capacity, significantly activated phenylpropanoid biosynthesis, and adaptive morphological characteristics. This study unveils the possible molecular mechanisms underlying oAANAT dependent melatonin functions in switchgrass, providing an important starting point for further analyses.

Hydrogen Sulfide Inhibits Ferroptosis in Cardiomyocytes to Protect Cardiac Function in Aging Rats.

Aging contributes significantly to cardiovascular diseases and cardiac dysfunction. To explore the reasons for the decline in cardiac function in the elderly, we collected clinical data and blood samples from 231 individuals. Our results indicated that aging was accompanied by a decline in cardiac function and remodeling of the left ventricle, and cardiac function was negatively correlated with age. Serum hydrogen sulfide (H2S) decreased, while serum malondialdehyde (MDA) and iron increased with aging in healthy individuals. A rat model of aging and iron overload was constructed for in vivo research. In the animal model, we found that the expression of endogenous H2S-producing enzymes decreased, and endogenous H2S levels decreased, while oxidative stress levels rose. The regulation of iron metabolism and the maintenance of iron homeostasis declined. The accumulation of MDA and iron led to ferroptotic cell death and subsequent myocardial injury and deterioration. A high-iron diet accelerated the aging process and death in rats. The decline of cardiac function in aging rats and iron-overload rats may be caused by cardiomyocyte ferroptosis. Exogenous H2S enhanced the expression of endogenous H2S synthase, promoted endogenous H2S production, regulated iron metabolism, and reduced oxidative stress levels. The protective effects of H2S on cardiac function in aging rats and iron-overload rats may be partly due to the inhibition of cardiomyocyte ferroptosis. We demonstrated that cardiac dysfunction associated with aging was closely related to decreased endogenous H2S levels and cardiomyocyte ferroptosis. H2S-regulated iron metabolism reduced oxidative stress levels in cardiomyocytes, inhibited cardiomyocyte ferroptosis, and protected cardiac function in aging rats.

Hydrogen Sulfide Ameliorated High Choline-Induced Cardiac Dysfunction by Inhibiting cGAS-STING-NLRP3 Inflammasome Pathway.

Although it is an essential nutrient, high choline intake directly or indirectly via its metabolite is associated with increased risk of cardiovascular disease, the mechanism of which remains to be elucidated. The present study was performed to investigate whether hydrogen sulfide (H2S) was involved in high choline-induced cardiac dysfunction and explore the potential mechanisms. We found that ejection fraction (EF) and fractional shortening (FS), the indicators of cardiac function measured by echocardiography, were significantly decreased in mice fed a diet containing 1.3% choline for 4 months as compared to the control, while applying 3,3-dimethyl-1-butanol (DMB) to suppress trimethylamine N-oxide (TMAO, a metabolite of choline) generation ameliorated the cardiac function. Subsequently, we found that feeding choline or TMAO significantly increased the protein levels of cyclic GMP-AMP (cGAMP) synthase (cGAS), stimulator of interferon genes (STING), NOD-like receptor protein 3 (NLRP3), caspase-1, and interleukin-1ß (IL-1ß) as compared to the control, which indicated the activation of cGAS-STING-NLRP3 inflammasome axis. Moreover, the protein expression of cystathionine γ-lyase (CSE), the main enzyme for H2S production in the cardiovascular system, was significantly increased after dietary supplementation with choline, but the plasma H2S levels were significantly decreased. To observe the effect of endogenous H2S, CSE knockout (KO) mice were used, and we found that the EF, FS, and plasma H2S levels in WT mice were significantly decreased after dietary supplementation with choline, while there was no difference between CSE KO + control and CSE KO + choline group. To observe the effect of exogenous H2S, mice were intraperitoneally injected with sodium hydrosulfide (NaHS, a H2S donor) for 4 months, and we found that NaHS improved the cardiac function and reduced the protein levels of cGAS, STING, NLRP3, caspase-1, and IL-1ß in mice receiving dietary choline. In conclusion, our studies revealed that high choline diet decreased plasma H2S levels and induced cardiac dysfunction via cGAS-STING-NLRP3 inflammasome axis while H2S treatment could restore the cardiac function by inhibiting cGAS-STING-NLRP3 inflammasome axis.

Branched-chain amino acid supplementation impairs insulin sensitivity and promotes lipogenesis during exercise in diet-induced obese mice.

OBJECTIVE: Branched-chain amino acids (BCAAs) are popular dietary supplements for exercise. However, increased BCAA levels positively correlate with obesity and diabetes. The metabolic impact of BCAA supplementation on insulin sensitivity during exercise is less understood. METHODS: Male C57BL/6 mice were fed for 12 weeks with a high-fat diet, normal chow diet, or BCAA-restricted high-fat diet. They were subjected to running exercise with or without BCAA treatment for another 12 weeks. RESULTS: Exercise reduced body weight, improved insulin sensitivity, lowered BCAAs in plasma, and inhibited the upregulation of BCAAs and metabolites caused by BCAA supplementation in the subcutaneous white adipose tissue (sWAT) of obese mice. BCAA supplementation reversed insulin sensitivity ameliorated by exercise. The phosphorylation of protein kinase B (Ser473 and Ser474) was decreased by BCAAs in the sWAT of obese mice. However, BCAA supplementation had no such effects in lean mice. BCAAs also increased the expression of fatty acid synthase and other lipogenesis genes in the sWAT of exercised obese mice. BCAA restriction had no effect on body weight and insulin sensitivity in obese mice. CONCLUSIONS: BCAA supplementation impaired the beneficial effect of exercise on glycolipid metabolism in obese but not lean mice. Caution should be taken regarding the use of BCAAs for individuals with obesity who exercise.

A Mendelian randomization analysis of the relationship between cardioembolic risk factors and ischemic stroke.

Observational studies have shown that several risk factors are associated with cardioembolic stroke. However, whether such associations reflect causality remains unknown. We aimed to determine whether established and provisional cardioembolic risk factors are causally associated with cardioembolic stroke. Genetic instruments for atrial fibrillation (AF), myocardial infarction (MI), electrocardiogram (ECG) indices and N-terminal pro-brain natriuretic peptide (NT-pro BNP) were obtained from large genetic consortiums. Summarized data of ischemic stroke and its subtypes were extracted from the MEGASTROKE consortium. Causal estimates were calculated by applying inverse-variance weighted analysis, weighted median analysis, simple median analysis and Mendelian randomization (MR)-Egger regression. Genetically predicted AF was significantly associated with higher odds of ischemic stroke (odds ratio (OR): 1.20, 95% confidence intervals (CI): 1.16-1.24, P = 6.53 × 10-30) and cardioembolic stroke (OR: 1.95, 95% CI: 1.85-2.06, P = 8.81 × 10-125). Suggestive associations were found between genetically determined resting heart rate and higher odds of ischemic stroke (OR: 1.01, 95% CI: 1.00-1.02, P = 0.005), large-artery atherosclerotic stroke (OR: 1.02, 95% CI: 1.00-1.04, P = 0.026) and cardioembolic stroke (OR: 1.02, 95% CI: 1.00-1.04, P = 0.028). There was no causal association of P-wave terminal force in the precordial lead V1 (PTFVI), P-wave duration (PWD), NT-pro BNP or PR interval with ischemic stroke or any subtype.