Effects of a novel hydrogen sulfide prodrug in a porcine model of acute limb ischemia

ObjectivePrevious studies have shown that hydrogen sulfide (H₂S) exerts potent proangiogenic properties under in vitro conditions and in rodent models. We sought to determine whether a novel H₂S prodrug promotes peripheral revascularization in a swine model of acute limb ischemia (ALI).MethodsALI was induced in 17 female miniswine via intravascular occlusion of the external iliac. At day 7 after ALI induction, miniswine (n = 17) were randomized to received placebo or the H₂S prodrug, SG-1002 (800 mg per os twice a day), for 35 days. At day 35 SG-1002 increased circulating levels of H₂S (5.0 ± 1.2 μmol/L vs 1.8 ± 0.50 μmol/L; P < .05), sulfane sulfur (10.6 ± 2.3 μmol/L vs 2.6 ± 0.8 μmol/L; P < .05), and nitrite (0.5 ± 0.05 μmol/L vs 0.3 ± 0.03 μmol/L; P < .005) compared with placebo. SG-1002 therapy increased angiographic scoring in ischemic limb vessel number (27.6 ± 1.6 vs 22.2 ± 1.8; P < .05) compared with placebo. Treatment with SG-1002 preserved existing capillaries in ischemic limbs (128.3 ± 18.7 capillaries/mm² vs 79.0 ± 9.8 capillaries/mm²; P < .05) compared with placebo. Interestingly, treatment with SG-1002 also improved coronary vasorelaxation responses to bradykinin and substance P in miniswine with ALI.ConclusionsOur results suggest that daily administration of the H₂S prodrug, SG-1002, leads to an increase in circulating H₂S and nitric oxide signaling and preserves vessel number and density in ischemic limbs. Furthermore, SG-1002 therapy improved endothelial-dependent coronary artery vasorelaxation in the setting of ALI. Our data demonstrate that SG-1002 preserves the vascular architecture in ischemic limbs and exerts vascular protective effects in the coronary vasculature in a model of peripheral vascular disease.     

Inhibiting hydrogen sulfide production in umbilical stem cells reduces their protective effects during experimental necrotizing enterocolitis

IntroductionUmbilical mesenchymal stem cells (USC) have been shown to reduce illness in animal models of necrotizing enterocolitis (NEC), possibly through the paracrine release of hydrogen sulfide (H₂S). We hypothesized that animals treated with USCs with inhibited H₂S synthesis would exhibit more severe disease.MethodsNEC was induced in five-day-old mouse pups by formula feeding and hypoxic and hypothermic stress. Experimental groups received intraperitoneal injection of either saline vehicle or 80,000cells/gram of one of the following cell types: USC, USCs with negative-control siRNA, or USCs with targeted siRNA inhibition of the H₂S-producing enzymes. Pups were monitored by clinical assessment and after euthanasia, intestine and lung histologic injury were scored. Tissue was homogenized, and concentrations of IL-6, IL-10, and VEGF were determined by ELISA. For statistical analysis, p < 0.05 was considered significant.ResultsAnimals treated with negative-control siRNA USCs were significantly improved compared to vehicle. Clinical sickness scores as well as intestinal and lung histologic injury scores in the targeted siRNA groups were significantly worse when compared to the negative-control siRNA group. IL-6, IL-10, and VEGF had varying patterns of expression in the different groups.ConclusionInhibition of H₂S production in USCs reduces the beneficial effects of these cells during therapy in experimental NEC.Level of evidenceAnimal studies are typically described as “foundational evidence” without a true level assigned.Type of studyAnimal Study.     

Evidence-based pathogenesis and treatment of ulcerative colitis: A causal role for colonic epithelial hydrogen peroxide

In this comprehensive evidence-based analysis of ulcerative colitis (UC), a causal role is identified for colonic epithelial hydrogen peroxide (H₂O₂) in both the pathogenesis and relapse of this debilitating inflammatory bowel disease. Studies have shown that H₂O₂ production is significantly increased in the non-inflamed colonic epithelium of individuals with UC. H₂O₂ is a powerful neutrophilic chemotactic agent that can diffuse through colonic epithelial cell membranes creating an interstitial chemotactic molecular “trail” that attracts adjacent intravascular neutrophils into the colonic epithelium leading to mucosal inflammation and UC. A novel therapy aimed at removing the inappropriate H₂O₂ mediated chemotactic signal has been highly effective in achieving complete histologic resolution of colitis in patients experiencing refractory disease with at least one (biopsy-proven) histologic remission lasting 14 years to date. The evidence implies that therapeutic intervention to prevent the re-establishment of a pathologic H₂O₂ mediated chemotactic signaling gradient will indefinitely preclude neutrophilic migration into the colonic epithelium constituting a functional cure for this disease. Cumulative data indicate that individuals with UC have normal immune systems and current treatment guidelines calling for the suppression of the immune response based on the belief that UC is caused by an underlying immune dysfunction are not supported by the evidence and may cause serious adverse effects. It is the aim of this paper to present experimental and clinical evidence that identifies H₂O₂ produced by the colonic epithelium as the causal agent in the pathogenesis of UC. A detailed explanation of a novel therapeutic intervention to normalize colonic H₂O₂, its rationale, components, and formulation is also provided.     

PI3K/AKT pathway mediates the antidepressant- and anxiolytic-like roles of hydrogen sulfide in streptozotocin-induced diabetic rats via promoting hippocampal neurogenesis

We have previously demonstrated that hydrogen sulfide (H₂S), the third endogenous gasotransmitter, ameliorates the depression- and anxiety-like behaviors in diabetic rats, but the underlying mechanism remains unclear. The present was aimed to investigate whether the hippocampal phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway mediates H₂S-ameliorated depression- and anxiety-like behaviors in diabetic rats by improving the hippocampal neurogenesis. The depression-like behaviors were examined by Tail suspension test (TST), the anxiety-like behaviors were examined by Elevated plus maze test (EPM), and the locomotor activity was detected by Open Field Test (OFT). The expressions of doublecortin (DCX), neuron-specific nuclear protein (NeuN), glial fibrillary acidic protein (GFAP), p-AKT, and AKT in the hippocampus were determined by Western blot analysis. Results showed that NaHS, a donor of exogenous H₂S, not only activated the hippocampal PI3K/AKT pathway, as evidenced by the increase of phosphorylated AKT, but also favorably reversed streptozotocin (STZ)-disturbed hippocampal neurogenesis, as evidenced by the increases in the expressions of DCX and NeuN as well as the decrease in the expression of GFAP in the hippocampus of STZ-induced diabetic rats. Furthermore, inhibited PI3K/AKT pathway by LY294002 significantly abolished H₂S-exerted the improvement of hippocampal neurogenesis and the antidepressant- and anxiolytic-like effects in the STZ-induced diabetic rats. Taken together, these results uncover that the activation of hippocampal PI3K/AKT pathway plays an important role to restore hippocampal neurogenesis and subsequently to mediate the antidepressant- and anxiolytic-like roles of H₂S in STZ-induced diabetic rats and enhance our understanding of the robustness of H₂S as a therapeutic strategy for treatment of depression in diabetes mellitus.     

Fe3O4纳米酶对白念珠菌的体外抑制实验研究

【摘要】 目的 研究Fe3O4纳米酶对白念珠菌的抗菌作用。方法 改进水热合成法，制备Fe3O4纳米酶。以0.5 g/L Fe3O4纳米酶和0.1% H2O2与菌液共培养，分为纳米酶组、H2O2组、联合组（纳米酶 + H2O2共处理），以未做处理菌液为对照组。4组菌液以沙氏液体培养基培养，每隔2 h检测600 nm处吸光度（A值），观察白念珠菌生长情况。取4组菌液共处理2 h，扫描电镜观察各组白念珠菌形态；涂板后，于36 ℃培养48 h，观察菌落形成情况并计数，计算抑菌率。多组间均数比较采用单因素方差分析，组间两两比较采用LSD-t检验。结果 对照组白念珠菌具有相对稳定的生存曲线，而纳米酶组、H2O2组、联合组白念珠菌的生长均受到抑制。4组菌落计数分别为124 830 ± 45 170、86 330 ± 13 960、91 670 ± 31 370、30 330 ± 3010，差异有统计学意义（F = 9.41，P < 0.05），联合组低于对照组（t = 4.63，P < 0.05）。H2O2组、纳米酶组、联合组抑菌率分别为30.84% ± 5.00%、26.57% ± 11.24%、75.70% ± 2.42%，差异有统计学意义（F = 9.413，P < 0.01），联合组高于H2O2组、纳米酶组（t = 8.08、4.27，P < 0.01），差异均有统计学意义。扫描电镜观察，经过处理后菌体形态发生皱缩、破裂甚至崩解等改变。结论 Fe3O4纳米酶联合H2O2对白念珠菌抑菌效果明显。     

Postranslational Modification of Ion Channels in Colonic Inflammation

Voltage-gated ion channels are key regulators of cell excitability. There is significant evidence that these channels are subject to modulation by redox status of the cells. Here we review the post-translational modifications of ion channels that occur in colonic inflammation. The redox mechanisms involve tyrosine nitration, covalent modification of cysteine residues and sulfhydration by hydrogen sulfide in experimental colitis. In the setting of colonic inflammation, modifications of cysteine and tyrosine are likely to occur at several sites within the same channel complex. In this review we describe alterations in channel function due to specific modifications of tyrosine and cysteine residues by reactive nitrogen, oxygen and hydrogen-sulfide resulting in altered motility.     

硫化氢吸入对心搏骤停复苏大鼠脑蛋白激酶C同工酶的影响

目的探讨吸入硫化氢对心搏骤停复苏大鼠脑蛋白激酶C(PKC)同工酶的影响。方法取清洁级健康SD雄性大鼠60只,采用数字表法,将其随机分为假手术组(10只)、对照组(25只)和硫化氢组(25只)。对照组和硫化氢组采用窒息性心搏骤停后心肺复苏模型,硫化氢组于自主循环恢复后立即吸入含有0.08‰硫化氢的30%氧气1 h。各组大鼠于假手术或自主循环恢复后24 h时,应用神经功能缺损评分(NDS)评价神经功能;于24 h监测PKC同工酶α、βⅠ、βⅡ、δ及ε的活性水平;于7 d计算存活率、计数海马CA1区存活神经细胞。结果 (1)假手术组大鼠全部存活,对照组和硫化氢组存活率分别为45.0%(9/20)和80.0%(16/20),与对照组相比,硫化氢组大鼠存活率明显增加,组间差异有统计学意义(χ2=8.087,P=0.018)。(2)自主循环恢复(ROSC)24 h,与假手术组相比,对照组和硫化氢组NDS评分均明显降低,组间中位数两两比较,差异均有统计学意义[46(43,52)、60(55,68)分比80(80,80),均P0.05];与对照组比较,硫化氢组NDS评分升高,组间差异有统计学意义(P0.05)。(3)ROSC后24 h,与假手术组比较,对照组PKC-α、PKC-βⅠ、PKC-βⅡ和PKC-δ活性水平明显升高,PKC-ε活性水平受到抑制,组间比较差异均有统计学意义[(1.63±0.14)比(1.00±0.02)、(2.00±0.08)比(1.00±0.04)、(1.51±0.10)比(1.00±0.01)、(2.02±0.12)比(1.00±0.02);均P0.05];硫化氢组PKC-α、PKC-βⅠ、PKC-βⅡ、PKC-δ和PKC-ε活性水平的差异无统计学意义(均P0.05);与对照组比较,硫化氢组PKC-α、PKC-βⅠ、PKC-βⅡ和PKC-δ活性水平[分别为(0.94±0.06)、(1.26±0.04)、(0.83±0.02)、(1.04±0.06)]明显下降,PKC-ε水平明显升高[(1.13±0.07)比(0.73±0.04)],组间差异均有统计学意义(均P0.05)。(4)ROSC后7 d,假手术组、对照组和硫化氢组海马CA1区存活神经细胞计数分别为(53±3)、(23±2)和(34±1)个,与假手术组相比,对照组和硫化氢组存活神经细胞计数均明显降低(均P0.01);与对照组比较,硫化氢组存活神经细胞计数明显升高(P0.01)。结论心搏骤停/心肺复苏后,早期吸入硫化氢可抑制PKC-α、PKC-βⅠ、PKC-βⅡ及PKC-δ激活,促进PKC-ε激活,改善大鼠神经功能和促进神经细胞存活。     

Identification of a functional dddD-Rh for dimethyl sulfide production in the Antarctic Rhodococcus sp. NJ-530

Dimethylsulfoniopropionate (DMSP) is widespread in the oceans, and its biological metabolite, dimethyl sulfide (DMS), plays an important role in the atmosphere. The Antarctic region has become a hotspot in DMS studies due to the high spatial and temporal variability in DMS(P) concentration, but the level of bacterial DMS production remains unclear. In this study, a bacterium isolated from Antarctic floating ice, Rhodococcus sp. NJ-530, was found to metabolize DMSP into DMS, and the rate of DMS production was measured as 3.96 pmol·mg protein⁻¹·h⁻¹. Rhodococcus sp. NJ-530 had a DddD-Rh enzyme containing two CaiB domains, which belonged to the CoA-transferase III superfamily. However, the DddD-Rh had a molecular weight of 73.21 kDa, which was very different from previously characterized DddD enzymes in sequence and evolution. In vitro assays showed that DddD-Rh was functional in the presence of acetyl-CoA. This was the first functional DddD from Gram-positive Actinobacteria. Moreover, a quantitative real-time polymerase chain reaction revealed that high temperature facilitated the expression of dddD-Rh, and changes of salinity had little effect on it. This study adds new evidence to the bacterial DMS production in the Southern Ocean and provides a basis for investigating the metabolic mechanism of DMSP in extreme environments.     

蛋氨酸限制提高内源性H2S活性延缓衰老的机制研究进展

蛋氨酸限制(Methionine restriction,MetR)作为饮食限制的方法之一,能够改善多种无脊椎动物、啮齿类动物及包括人类灵长类动物的衰老及其相关疾病。但MetR对衰老的具体调节作用机制尚未完全明确,目前除了与饮食限制的共有机制以外,越来越多的研究表明内源性硫化氢(Endogenous hydrogen sulfide,H2S)可能是其发挥效应的主要机制。硫化氢作为水溶性和脂溶性的小分子气体,在延缓衰老进程和改善衰老相关疾病中具有重要意义。本文阐述了MetR通过提高内源性H2S的活性延缓衰老的机制及相关研究。