Maintaining moderate levels of hypochlorous acid promotes neural stem cell proliferation and differentiation in the recovery phase of stroke.

JOURNAL/nrgr/04.03/01300535-202503000-00029/figure1/v/2024-06-17T092413Z/r/image-tiff It has been shown clinically that continuous removal of ischemia/reperfusion-induced reactive oxygen species is not conducive to the recovery of late stroke. Indeed, previous studies have shown that excessive increases in hypochlorous acid after stroke can cause severe damage to brain tissue. Our previous studies have found that a small amount of hypochlorous acid still exists in the later stage of stroke, but its specific role and mechanism are currently unclear. To simulate stroke in vivo, a middle cerebral artery occlusion rat model was established, with an oxygen-glucose deprivation/reoxygenation model established in vitro to mimic stroke. We found that in the early stage (within 24 hours) of ischemic stroke, neutrophils produced a large amount of hypochlorous acid, while in the recovery phase (10 days after stroke), microglia were activated and produced a small amount of hypochlorous acid. Further, in acute stroke in rats, hypochlorous acid production was prevented using a hypochlorous acid scavenger, taurine, or myeloperoxidase inhibitor, 4-aminobenzoic acid hydrazide. Our results showed that high levels of hypochlorous acid (200 µM) induced neuronal apoptosis after oxygen/glucose deprivation/reoxygenation. However, in the recovery phase of the middle cerebral artery occlusion model, a moderate level of hypochlorous acid promoted the proliferation and differentiation of neural stem cells into neurons and astrocytes. This suggests that hypochlorous acid plays different roles at different phases of cerebral ischemia/reperfusion injury. Lower levels of hypochlorous acid (5 and 100 µM) promoted nuclear translocation of ß-catenin. By transfection of single-site mutation plasmids, we found that hypochlorous acid induced chlorination of the ß-catenin tyrosine 30 residue, which promoted nuclear translocation. Altogether, our study indicates that maintaining low levels of hypochlorous acid plays a key role in the recovery of neurological function.

Peroxynitrite-Triggered Carbon Monoxide Donor Improves Ischemic Stroke Outcome by Inhibiting Neuronal Apoptosis and Ferroptosis.

Cerebral ischemia-reperfusion injury produces excessive reactive oxygen and nitrogen species, including superoxide, nitric oxide, and peroxynitrite (ONOO-). We recently developed a new ONOO--triggered metal-free carbon monoxide donor (PCOD585), exhibiting a notable neuroprotective outcome on the rat middle cerebral artery occlusion model and rendering an exciting intervention opportunity toward ischemia-induced brain injuries. However, its therapeutic mechanism still needs to be addressed. In the pharmacological study, we found PCOD585 inhibited neuronal Bcl2/Bax/caspase-3 apoptosis pathway in the peri-infarcted area of stroke by scavenging ONOO-. ONOO- scavenging further led to decreased Acyl-CoA synthetase long-chain family member 4 and increased glutathione peroxidase 4, to minimize lipoperoxidation. Additionally, the carbon monoxide release upon the ONOO- reaction with PCOD585 further inhibited the neuronal Iron-dependent ferroptosis associated with ischemia-reperfusion. Such a synergistic neuroprotective mechanism of PCOD585 yields as potent a neuroprotective effect as Edaravone. Additionally, PCOD585 penetrates the blood-brain barrier and reduces the degradation of zonula occludens-1 by inhibiting matrix metalloproteinase-9, thereby protecting the integrity of the blood-brain barrier. Our study provides a new perspective for developing multi-functional compounds to treat ischemic stroke.

Remote Ischemic Postconditioning-Mediated Neuroprotection against Stroke by Promoting Ketone Body-Induced Ferroptosis Inhibition.

Neuronal death resulting from ischemic stroke is the primary cause of adult mortality and disability, and effective neuroprotective agents for poststroke intervention are still lacking. Remote ischemic postconditioning (RIPostC) has demonstrated significant protective effects against ischemia in various organs; however, the specific mechanisms are not fully understood. This study investigated the potential neuroprotective mechanisms of RIPostC in the context of ischemic stroke. Using a rat model of middle cerebral artery occlusion, we found that RIPostC mitigated neurological damage, improved movement in the open-field test, and protected against neuronal apoptosis. In terms of energy metabolism, RIPostC enhanced ATP levels, suppressed lactate content, and increased the production of ketone bodies (KBs). In the ferroptosis assay, RIPostC protected against lipoperoxidation, reversed the reduction of glutathione peroxidase 4 (GPX4), and mitigated the excessive expression of long-chain acyl-CoA synthetase family member 4 (ACSL4). In oxygen-glucose deprivation/reoxygenation-treated HT22 cells, KBs maintained GPX4 levels, suppressed ACSL4 expression, and preserved the mitochondrial cristae number. However, the effect of KBs on the expression of GPX4, ACSL4, and the number of mitochondrial cristae was blocked by erastin. Moreover, both RIPostC and KBs reduced total iron and ferrous ion content by repressing iron transporters both in vitro and in vivo. In conclusion, KBs-induced mitigation of ferroptosis could represent a new therapeutic mechanism for RIPostC in treating stroke.

Healthy Serum-Derived Exosomes Improve Neurological Outcomes and Protect Blood-Brain Barrier by Inhibiting Endothelial Cell Apoptosis and Reversing Autophagy-Mediated Tight Junction Protein Reduction in Rat Stroke Model.

Blood-brain barrier (BBB) dysfunction causing edema and hemorrhagic transformation is one of the pathophysiological characteristics of stroke. Protection of BBB integrity has shown great potential in improving stroke outcome. Here, we assessed the efficacy of exosomes extracted from healthy rat serum in protection against ischemic stroke in vivo and in vitro. Exosomes were isolated by gradient centrifugation and ultracentrifugation and exosomes were characterized by transmission electron microscopy (TEM) and nanoparticle tracking video microscope. Exosomes were applied to middle cerebral artery occlusion (MCAO) rats or brain microvascular endothelial cell line (bEnd.3) subjected to oxygen-glucose deprivation (OGD) injury. Serum-derived exosomes were injected intravenously into adult male rats 2 h after transient MCAO. Infarct volume and gross cognitive function were assessed 24 h after reperfusion. Poststroke rats treated with serum-derived exosomes exhibited significantly reduced infarct volumes and enhanced neurological function. Apoptosis was assessed via terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) staining and the expression of B-cell lymphoma-2 (Bcl-2), Bax, and cleaved caspase-3 24 h after injury. Our data showed that serum exosomes treatment strikingly decreased TUNEL+ cells in the striatum, enhanced the ratio of Bcl-2 to Bax, and inhibited cleaved caspase-3 production in MCAO rats and OGD/reoxygenation insulted bEnd.3 cells. Under the consistent treatment, the expression of microtubule-associated protein 1 light chain 3B-II (LC3B-II), LC3B-I, and Sequestosome-1 (SQSTM1)/p62 was detected by Western blotting. Autolysosomes were observed via TEM. We found that serum exosomes reversed the ratio of LC3B-II to LC3B-I, prevented SQSTM1/p62 degradation, autolysosome formation, and autophagic flux. Together, these results indicated that exosomes isolated from healthy serum provided neuroprotection against experimental stroke partially via inhibition of endothelial cell apoptosis and autophagy-mediated BBB breakdown. Intravenous serum-derived exosome treatment may, therefore, provide a novel clinical therapeutic strategy for ischemic stroke.

A study of auditory localization mechanism based on thought experiments.

The focus of this study is auditory localization. Based on wave mechanics and structural mechanics, we analyze the sound field encircling external ear and the function of the soft tissues in middle ear respectively. And then, with the help of two rules, some details of the generation of spatial hearing are revealed. For auditory direction perception, three semicircular canals work as the reference coordinate system, and the cues are the direction of the concentrated force acting on tympanic membrane and the synchronous stress state. For the distance perception, because the distance information of the sound source is converted into some comparisons, the accuracy is closely related to the amount of useable sound sources. Therefore, the bad accuracy of the distance perception is inevitable in most cases. When it is necessary, many cues based on experience will be utilized to enhance the accuracy of the distance perception, which brings the diversity to auditory localization. Additionally, our results also can be used to explain some well known acoustic phenomena, such as auditory localization with one ear and the cocktail party effect.

The protective effect of the EP2 receptor on TGF-ß1 induced podocyte injury via the PI3K / Akt signaling pathway.

Transforming growth factor ß1 (TGF-ß1) plays a central role in chronic kidney diseases. TGF-ß1 induction causes podocyte injury, which results in proteinuria and renal failure. However, the effect of the prostaglandin E2 /E-prostanoid receptor (EP2) on TGF-ß1-induced podocyte injury remains unknown. Previous studies have shown that phosphoinositide 3-OH kinase (PI3K)/Akt is widespread in cells, and is vital for the regulation of cell proliferation, differentiation, apoptosis and metabolism. In this study, we cultured immortalized mouse podocytes in vitro in different groups: control group; TGF-ß1 (5ng/ml) group; EP2 agonist Butaprost treatment (10-7, 10-6, or 10-5mol/L) +TGF-ß1 group; EP2 antagonist AH6809 treatment (10-7, 10-6, or 10-5mol / L) + TGF-ß1 group. We found that compared with the control group, proliferation of podocytes in the TGF-ß1 group significantly decreased and apoptosis increased. Expression of cAMP decreased, whereas PGE2 increased. Meanwhile, expressions of nephrin, podocin and CD2AP mRNA and protein were dramatically downregulated, activated caspase-3 was increased, and activated PI3K/Akt activity were depressed. Butaprost intervention promoted podocyte proliferation with reduced apoptosis. Conversely, AH6809 intervention led to opposite results (P<0.05). Our findings suggested that EP2 agonist protects podocytes by increasing expression of cAMP, which creates feedback of inhibiting PGE2 expression. This causes the interaction of nephrin, podocin and CD2AP resulting the inhibition of apoptosis induced by activation of the PI3K / Akt signaling pathway.

SB-216763, a GSK-3ß inhibitor, protects against aldosterone-induced cardiac, and renal injury by activating autophagy.

Cardiovascular and renal inflammation induced by Aldosterone (Aldo) plays a pivotal role in the pathogenesis of hypertension and renal fibrosis. GSK-3ß contributes to inflammatory cardiovascular and renal diseases, but its role in Aldo-induced hypertension, and renal damage is not clear. In the present study, rats were treated with Aldo combined with SB-216763 (a GSK-3ß inhibitor) for 4 weeks. Hemodynamic, cardiac, and renal parameters were assayed at the indicated time. Here we found that rats treated with Aldo presented cardiac and renal hypertrophy and dysfunction. Cardiac and renal expression levels of molecular markers attesting inflammation and fibrosis were increased by Aldo infusion, whereas the treatment of SB-216763 reversed these alterations. SB-216763 suppressed cardiac and renal inflammatory cytokines levels (TNF-a, IL-1ß, and MCP-1). Meanwhile, SB-216763 increased the protein levels of LC3-II in the cardiorenal tissues as well as p62 degradation, indicating that SB-216763 induced autophagy activation in cardiac, and renal tissues. Importantly, inhibition of autophagy by 3-MA attenuated the role of SB-216763 in inhibiting perivascular fibrosis, and tubulointerstitial injury. These data suggest that SB-216763 protected against Aldo-induced cardiac and renal injury by activating autophagy, and might be a therapeutic option for salt-sensitive hypertension and renal fibrosis.

A maladaptive role for EP4 receptors in mouse mesangial cells.

Roles of the prostaglandin E2 E-prostanoid 4 receptor (EP4) on extracellular matrix (ECM) accumulation induced by TGF-ß1 in mouse glomerular mesangial cells (GMCs) remain unknown. Previously, we have identified that TGF-ß1 stimulates the expression of FN and Col I in mouse GMCs. Here we asked whether stimulation of EP4 receptors would exacerbate renal fibrosis associated with enhanced glomerular ECM accumulation. We generated EP4(Flox/Flox) and EP4(+/-) mice, cultured primary WT, EP4(Flox/Flox) and EP4(+/-) GMCs, AD-EP4 transfected WT GMCs (EP4 overexpression) and AD-Cre transfected EP4(Flox/Flox) GMCs (EP4 deleted). We found that TGF-ß1-induced cAMP and PGE2 synthesis decreased in EP4 deleted GMCs and increased in EP4 overexpressed GMCs. Elevated EP4 expression in GMCs augmented the coupling of TGF-ß1 to FN, Col I expression and COX2/PGE2 signaling, while TGF-ß1 induced FN, Col I expression and COX2/PGE2 signaling were down-regulated in EP4 deficiency GMCs. 8 weeks after 5/6 nephrectomy (Nx), WT and EP4(+/-) mice exhibited markedly increased accumulation of ECM compared with sham-operated controls. Albuminuria, blood urea nitrogen and creatinine (BUN and Cr) concentrations were significantly increased in WT mice as compared to those of EP4(+/-) mice. Urine osmotic pressure was dramatically decreased after 5/6 Nx surgery in WT mice as compared to EP4(+/-) mice. The pathological changes in kidney of EP4(+/-) mice was markedly alleviated compared with WT mice. Immunohistochemical analysis showed significant reductions of Col I and FN in the kidney of EP4(+/-) mice compared with WT mice. Collectively, this investigation established EP4 as a potent mediator of the pro-TGF-ß1 activities elicited by COX2/PGE2 in mice GMCs. Our findings suggested that prostaglandin E2, acting via EP4 receptors contributed to accumulation of ECM in GMCs and promoted renal fibrosis.

The role of renal damage on cardiac remodeling in patients with diabetic nephropathy.

BACKGROUND: Cardiovascular damage and diabetic nephropathy are major complications in patients with Type 2 diabetic nephropathy (T2DN); however, the role of renal damage on cardiac remodeling is not yet fully known. METHODS: A retrospective research was conducted in 254 T2DN patients. All were divided into three groups according to urinary albumin excretion (UAE): the normoalbuminuria group (UAE < 30 mg/g, n = 18), the microalbuminuria group (UAE 30 - 300 mg/g, n = 99) and the macroalbuminuria group (UAE > 300 mg/g, n = 137). The parameters of cardiac remodeling, left atrial diameter (LAD), left ventricular diameter at the end of diastole (LVDd), interventricular septum (IVS), posterior wall of left ventricle (PWLV) and ejection fraction (EF), were determined by Doppler echocardiography. The effects of renal damage on cardiac remodeling were analyzed. RESULTS: Among the 254 patients, LAD and LVDd enlargement was found in 180 (70.86%) and 53 (20.86%) patients, respectively; 46 cases (18.11%) suffered from both LAD and LVDd enlargement. Compared with normal LAD/LVDd groups, creatinine clearance (Ccr) and hemoglobin (Hb) were significantly lower in the left atrial (LA) and left ventricular (LV) dilated groups. LAD was positively correlated with mesangial sclerosis, tubular-interstitial lesions, interstitial fibrosis, as well as tubular basement membrane thickness (r = 0.273, 0.208, 0.176, 0.155, p < 0.05, respectively). Moreover, in comparison to patients with LA enlargement, more severe renal damage was detected in patients with LV enlargement. CONCLUSION: There is a strong correlation between echocardiographic parameters and kidney lesions in patients with T2DN in China; the more severe the renal damage, the more severe the cardiac structural alteration. Renal damage contributes to cardiac remodeling, which may provide new insights into the pathogenesis of cardiovascular complications ,in diabetes mellitus.

The relationship between obesity and diabetic nephropathy in China.

BACKGROUND: The epidemic of diabetic nephropathy (DN) has been paralleled by rapid increases in both obesity and diabetes in China. The aim of this study was to investigate the natural history of DN and the association of obesity and renal function with diabetes. METHODS: In total, 264 patients with renal biopsy-confirmed DN were examined from 2002 to 2008 and followed up to June 2008 in our institute. Among these, 129 patients were classified into a Kidney Disease Outcomes Quality Initiative (K/DOQI) stage I subgroup. Weight status, clinico-histopathological features, the development of end-stage renal disease (ESRD) and increased proteinuria were evaluated at the baseline of biopsy and during the follow up. Lean, overweight and obese phenotypes were defined as body mass index (BMI) less than 25 kg/m2, 25-28 kg/m2, and more than 28 kg/m2 over, respectively. RESULTS: In the patients with renal biopsy-confirmed DN, BMI was 25.5 ± 3.39 kg/m2, with 122 (46.2%), 83 (31.4%) and 59 (22.3%) having lean, overweight and obese phenotypes, respectively. Mean proteinuria was 3.09 ± 2.32 g/24 h, serum creatinine was 2.02 ± 2.02 mg/dL, and creatinine clearance rate (Ccr) was 96.0 ± 54.0 mL/min/1.73 m2. Compared with obese patients, lean patients had a lower Ccr, a higher percentage of anemia, more renal lesions and higher risk for ESRD (HR = 1.812, P = 0.048). The weight in obese patients decreased significantly after 27 months, and lean patients had a longer duration of diabetes than obese patients. Regarding patients at K/DOQI stage I, patients with DN showed similar duration of diabetes regardless of weight status. Minimal weight loss was recorded in obese patients during follow-up, and they exhibited greater glomerular hyperfiltration and higher risk for increased proteinuria (HR = 2.872, P = 0.014) than lean patients. CONCLUSIONS: In China, obesity is common in DN patients undergoing biopsy. Initial high levels of proteinuria and subsequent weight loss are the major characteristics of the natural course of DN. Obesity contributed to increased proteinuria at an early stage, while the lean phenotype was associated with ESRD development, especially at the later stages.

Evaluation of metabolic risk marker in obesity-related glomerulopathy.

OBJECTIVE: Insulin resistance is a common metabolic abnormality, which increases the risk of renal events in obesity. The present study is aimed to examine the relation between metabolic factors and obesity-related glomerulopathy (ORG), and then compare the risk markers of insulin resistance for clinical prediction. METHODS: A total of 112 cases with proven renal ORG and 135 age- and gender-matched lean controls were included. The degree of proteinuria, endogenous creatinine clearance rate, body mass index, amylin, fasting glucose, insulin, lipid and lipoprotein concentrations were measured during the steady state. RESULTS: The patients with ORG were clinically characterized by increased body mass index and proteinuria, with higher levels of amylin, homeostasis model assessment of insulin resistance (HOMA-IR), insulin, glucose, and lipid proteins when compared with the lean controls. Multiple logistic regression analysis revealed that amylin and HOMA-IR were significantly associated with the prevalence of ORG. In patients with ORG, proteinuria level correlated with amylin, total cholesterol, fasting insulin, and HOMA-IR. Moreover, proteinuria correlated positively with HOMA-IR and amylin in a multiple regression analysis. In addition, the endogenous creatinine clearance rate did not correlate with any metabolic marker. CONCLUSION: This study suggested that screening for HOMA-IR might have predictive value for renal damage in obese patients. In addition to insulin resistance, amylin also showed positive effects on evaluation of such renal impairment.