Impoverished language in early childhood affects the development of complex sentence structure.

The hypothesis that impoverished language experience affects complex sentence structure development around the end of early childhood was tested using a fully randomized, sentence-to-picture matching study in American Sign Language (ASL). The participants were ASL signers who had impoverished or typical access to language in early childhood. Deaf signers whose access to language was highly impoverished in early childhood (N = 11) primarily comprehended structures consisting of a single verb and argument (Subject or Object), agreeing verbs, and the spatial relation or path of semantic classifiers. They showed difficulty comprehending more complex sentence structures involving dual lexical arguments or multiple verbs. As predicted, participants with typical language access in early childhood, deaf native signers (N = 17) or hearing second-language learners (N = 10), comprehended the range of 12 ASL sentence structures, independent of the subjective iconicity or frequency of the stimulus lexical items, or length of ASL experience and performance on non-verbal cognitive tasks. The results show that language experience in early childhood is necessary for the development of complex syntax. RESEARCH HIGHLIGHTS: Previous research with deaf signers suggests an inflection point around the end of early childhood for sentence structure development. Deaf signers who experienced impoverished language until the age of 9 or older comprehend several basic sentence structures but few complex structures. Language experience in early childhood is necessary for the development of complex sentence structure.

Combined prognostic significance of white blood cell count and D-dimer on in-hospital outcomes of acute ischemic stroke.

BACKGROUND AND AIMS: The prognostic significance of combination of white blood cell (WBC) and D-dimer on acute ischemic stroke (AIS) remains to be explored. We aimed to investigate the combined effect of WBC and D-dimer levels on in-hospital outcomes of AIS patients. METHODS AND RESULTS: 801 AIS patients were included. Patients were divided into four groups according to the cut-point identified by receiver operating characteristic (ROC) curve of D-dimer (1.105 µg/L) and WBC (7.05 × 109/L): LWLD (low WBC count and low D-dimer), LWHD (low WBC count and high D-dimer), HWLD (high WBC count and low D-dimer), and HWHD (high WBC count and high D-dimer). HWHD group had the highest cumulative incidence of in-hospital mortality (hazard ratio, 5.79; 95%CI, 1.71-19.58, P = 0.006). Patients in HWHD group were 4.14 fold more likely to have in-hospital pneumonia (odds ratio, 4.14; 95%CI, 2.09-8.21; P < 0.001), compared with those in LWLD group. The area under curve (AUC) of the combination of WBC and D-dimer levels for in-hospital mortality and pneumonia was larger than that of WBC and D-dimer alone (0.920 vs. 0.900 vs. 0.915; 0.831 vs. 0.829 vs. 0.807). CONCLUSIONS: The combination of WBC count and D-dimer levels at admission was independently associated with in-hospital outcomes of AIS patients. The addition of WBC to D-dimer levels had a tendency to improve the predictive power for in-hospital mortality and pneumonia.

Interaction among Hydrogen Sulfide and Other Gasotransmitters in Mammalian Physiology and Pathophysiology.

Hydrogen sulfide (H2S), nitric oxide (NO), carbon monoxide (CO), and sulfur dioxide (SO2) were previously considered as toxic gases, but now they are found to be members of mammalian gasotransmitters family. Both H2S and SO2 are endogenously produced in sulfur-containing amino acid metabolic pathway in vivo. The enzymes catalyzing the formation of H2S are mainly CBS, CSE, and 3-MST, and the key enzymes for SO2 production are AAT1 and AAT2. Endogenous NO is produced from L-arginine under catalysis of three isoforms of NOS (eNOS, iNOS, and nNOS). HO-mediated heme catabolism is the main source of endogenous CO. These four gasotransmitters play important physiological and pathophysiological roles in mammalian cardiovascular, nervous, gastrointestinal, respiratory, and immune systems. The similarity among these four gasotransmitters can be seen from the same and/or shared signals. With many studies on the biological effects of gasotransmitters on multiple systems, the interaction among H2S and other gasotransmitters has been gradually explored. H2S not only interacts with NO to form nitroxyl (HNO), but also regulates the HO/CO and AAT/SO2 pathways. Here, we review the biosynthesis and metabolism of the gasotransmitters in mammals, as well as the known complicated interactions among H2S and other gasotransmitters (NO, CO, and SO2) and their effects on various aspects of cardiovascular physiology and pathophysiology, such as vascular tension, angiogenesis, heart contractility, and cardiac protection.

Macrophage-derived sulfur dioxide is a novel inflammation regulator.

Macrophage-mediated inflammation is a key pathophysiological component of cardiovascular diseases, but the underlying mechanisms by which the macrophage regulates inflammation have been unclear. In our study, we, for the first time, showed an endogenous sulfur dioxide (SO2) production in RAW267.4 macrophages by using HPLC and SO2-specific fluorescent probe assays. Moreover, the endogenous SO2 generating enzyme aspartate aminotransferase (AAT) was found to be expressed by the macrophages. Furthermore, we showed that AAT2 knockdown triggered spontaneous macrophage-mediated inflammation, as represented by the increased TNF-α and IL-6 levels and the enhanced macrophage chemotaxis; these effects could be reversed by the treatment with a SO2 donor. Mechanistically, AAT2 knockdown activated the NF-κB signaling pathway in macrophages, while SO2 successfully rescued NF-κB activation. In contrast, forced AAT2 expression reversed AngII-induced NF-κB activation and subsequent macrophage inflammation. Moreover, treatment with a SO2 donor also alleviated macrophage infiltration in AngII-treated mouse hearts. Collectively, our data suggest that macrophage-derived SO2 is an important regulator of macrophage activation and it acts as an endogenous "on-off switch" in the control of macrophage activation. This knowledge might enable a new therapeutic strategy for cardiovascular diseases.

Negative auto-regulation of sulfur dioxide generation in vascular endothelial cells: AAT1 S-sulfenylation.

Recently, endogenous sulfur dioxide (SO2) has been found to exert an important function in the cardiovascular system. However, the regulatory mechanism for SO2 generation has not been entirely clarified. Hence, we aimed to explore the possible auto-regulation of endogenous SO2 generation and its mechanisms in vascular endothelial cells. We showed that SO2 did not affect the protein expression of aspartate aminotransferase 1 (AAT1), a major SO2 synthesis enzyme, but significantly inhibited AAT activity in primary human umbilical vein endothelial cells (HUVECs) and porcine purified AAT1 protein. An AAT1 enzymatic kinetic study showed that SO2 reduced the Vmax (1.89 ± 0.10 vs 2.55 ± 0.12, µmol/mg/min, P < 0.05) and increased the Km (35.97 ± 9.54 vs 19.33 ± 1.76 µmol/L, P < 0.05) values. Furthermore, SO2 induced S-sulfenylation of AAT1 in primary HUVECs and purified AAT1 protein. LC-MS/MS analysis indicated that SO2 sulfenylated AAT1 at Cys192. Mechanistically, thiol reductant DTT treatment or C192S mutation prevented SO2-induced AAT1 sulfenylation and the subsequent inhibition of AAT activity in purified AAT1 protein and primary HUVECs. Our findings reveal, for the first time, a mechanism of auto-regulation of SO2 generation through sulfenylation of AAT1 at Cys192 to suppress AAT activity in vascular endothelial cells. These findings will greatly deepen the understanding of regulatory mechanisms in the cardiovascular homeostasis.

Sulfur Dioxide: An Endogenous Protector Against Myocardial Injury.

Sulfur dioxide (SO2) was previously known as a harmful gas in air pollution. Recently, it was reported that SO2 can be endogenously generated in cardiovascular tissues. Many studies have revealed that endogenous SO2 has important physiological and pathophysiological significance and pharmacological potential. As a novel gasotransmitter, SO2 has important regulatory effects on the heart. It has a dose-dependent negative inotropic effect on cardiac function, in which L-type calcium channels are involved. SO2 can also attenuate myocardial injury caused by various harmful stimuli and play an important role in myocardial ischemia-reperfusion injury and myocardial hypertrophy. These effects are thought to be linked to its ability to reduce inflammation and as an antioxidant. In addition, SO2 regulates cardiomyocyte apoptosis and autophagy. Therefore, endogenous SO2 plays an important role in maintaining cardiovascular system homeostasis. In the present review, the literature concerning the metabolism of endogenous SO2, its cardiac toxicological effects and physiological regulatory effects, mechanisms for SO2-mediated myocardial protection and its pharmacological applications are summarized and discussed.

Different attributes of creaky voice distinctly affect Mandarin tonal perception.

Previous work has shown mixed findings concerning the role of voice quality cues in Mandarin tones, with some studies showing that creak improves identification. This study tests the linguistic importance of acoustic properties of creak for Mandarin tone perception. Mandarin speakers identified tones with four resynthesized creak manipulations: low spectral tilt, irregular F0, period doubling, and extra-low F0. Two experiments with three conditions were conducted. In Experiment 1, the manipulations were confined to a portion of the stimuli's duration; in Experiment 2 the creak manipulations were modified and lengthened throughout the stimuli, and in a second condition, noise was incorporated to weaken F0 cues. Listeners remained most sensitive to extra-low F0, which affected identification of the four tones differently: it improved the identification accuracy of Tone 3 and hindered that of Tones 1 and 4. Irregular F0 consistently hindered T1 identification. The effects of irregular F0, period doubling, and low spectral tilt emerged in Experiment 2, where F0 cues were less robust and creak cues were stronger. Thus, low F0 is the most prominent cue used in Mandarin tone identification, but other voice quality cues become more salient to listeners when the F0 cues are less retrievable.

Angiotensin II downregulates vascular endothelial cell hydrogen sulfide production by enhancing cystathionine γ-lyase degradation through ROS-activated ubiquitination pathway.

The interactions between vasoactive peptides and gasotransmitters have attracted considerable attention from scientists. However, the impact of angiotensin II (AngII) on the endogenous hydrogen sulfide/cystathionine γ-lyase (H2S/CSE) pathway in vascular endothelial cells remains unclear. In this study, we found, for the first time, that AngII downregulated the endogenous H2S/CSE pathway in a time-dependent manner. Mechanistically, AngII accelerated the degradation of the CSE protein and shortened its half-life in endothelial cells. AngII significantly induced Lys48 (K48)-linked CSE ubiquitination and subsequent CSE degradation but did not affect Lys63 (K63)-linked CSE ubiquitination in vascular endothelial cells. Treatment with the proteasome inhibitor MG132 and mutation of Lys48 to Arg in ubiquitin successfully blunted the inhibitory effects of AngII on the endogenous H2S/CSE pathway in vascular endothelial cells. Furthermore, we found that superoxide anion levels were significantly increased in AngII-treated endothelial cells compared with controls and that the ROS scavenger N-acetyl-l-cysteine (NAC) significantly abolished CSE ubiquitination. Taken together, our data suggested that AngII inhibited endogenous H2S generation through ubiquitination-mediated CSE degradation via the ROS pathway in vascular endothelial cells.

Endogenous hydrogen sulfide sulfhydrates IKKß at cysteine 179 to control pulmonary artery endothelial cell inflammation.

BACKGROUND: Pulmonary artery endothelial cell (PAEC) inflammation is a critical event in the development of pulmonary arterial hypertension (PAH). However, the pathogenesis of PAEC inflammation remains unclear. METHODS: Purified recombinant human inhibitor of κB kinase subunit ß (IKKß) protein, human PAECs and monocrotaline-induced pulmonary hypertensive rats were employed in the study. Site-directed mutagenesis, gene knockdown or overexpression were conducted to manipulate the expression or activity of a target protein. RESULTS: We showed that hydrogen sulfide (H2S) inhibited IKKß activation in the cell model of human PAEC inflammation induced by monocrotaline pyrrole-stimulation or knockdown of cystathionine γ-lyase (CSE), an H2S generating enzyme. Mechanistically, H2S was proved to inhibit IKKß activity directly via sulfhydrating IKKß at cysteinyl residue 179 (C179) in purified recombinant IKKß protein in vitro, whereas thiol reductant dithiothreitol (DTT) reversed H2S-induced IKKß inactivation. Furthermore, to demonstrate the significance of IKKß sulfhydration by H2S in the development of PAEC inflammation, we mutated C179 to serine (C179S) in IKKß. In purified IKKß protein, C179S mutation of IKKß abolished H2S-induced IKKß sulfhydration and the subsequent IKKß inactivation. In human PAECs, C179S mutation of IKKß blocked H2S-inhibited IKKß activation and PAEC inflammatory response. In pulmonary hypertensive rats, C179S mutation of IKKß abolished the inhibitory effect of H2S on IKKß activation and pulmonary vascular inflammation and remodeling. CONCLUSION: Collectively, our in vivo and in vitro findings demonstrated, for the first time, that endogenous H2S directly inactivated IKKß via sulfhydrating IKKß at Cys179 to inhibit nuclear factor-κB (NF-κB) pathway activation and thereby control PAEC inflammation in PAH.

Non-prescription cold and flu medication-induced transient myopia with uveal effusion: case report.

BACKGROUND: To report a case of non-prescription cold and flu medication-induced transient myopia with uveal effusion. CASE PRESENTATION: Bilateral high intraocular pressure, shallow anterior chambers, uveal effusion, and a myopic shift were encountered in a 39-year-old Chinese male 1 night after taking a non-prescription flu medicine three times than the recommended dose. Ultrasound biomicroscopy (UBM) showed bilateral ciliochoroidal effusions, disappearance of the ciliary sulcus, closure of the angle of the anterior chamber, and anterior displacement of the lens-iris diaphragm. Treatment with aqueous suppressants was given. Within a week, the uncorrected vision restored, and the myopia had disappeared. UBM revealed major resolution of the ciliochoroidal effusions in both eyes, deepening of the anterior chamber, return of the lens-iris diaphragm to a more posterior position. CONCLUSIONS: Overdose of non-prescription cold and flu medication may cause bilateral uveal effusions inducing acute angle-closure glaucoma and acute myopia.

Retina-derived endogenous sulfur dioxide might be a novel anti-apoptotic factor.

Endogenous sulfur dioxide (SO2) was found to be generated from the enzymatic reaction catalysed by aspartate transference 1 (AAT1) in the mammals and play importantly biological effects. In the present study, we explored the existence of endogenous SO2 pathway in mouse retinal tissues and 661w photoreceptor cell and investigated its possible pathophysiological role in the hydrogen peroxide (H2O2)-induced mouse photoreceptor cell apoptosis. The data showed that endogenous SO2 pathway including AAT1 expression and SO2 content was found to be presented in mouse photoreceptor cells. AAT1 protein and SO2 were mainly distributed in the cytoplasm, while a small amount of AAT1 protein and SO2 was found in the nucleus of 661W photoreceptor cells. H2O2 significantly decreased the SO2 content and AAT1 expression, but increased the cleaved caspase-3 protein level and the apoptotic index, and the number of TUNEL-positive cells in the 661W photoreceptor cells. Moreover, an AAT inhibitor HDX treatment inhibited SO2 synthesis and mimicked H2O2-induced apoptosis in 661W cells. In conclusion, the endogenous SO2/AAT1 pathway is firstly found to be present in mouse photoreceptor cells, and might play an important role in the prevention from mouse photoreceptor cell apoptosis.

Shift of Macrophage Phenotype Due to Cartilage Oligomeric Matrix Protein Deficiency Drives Atherosclerotic Calcification.

RATIONALE: Intimal calcification is highly correlated with atherosclerotic plaque burden, but the underlying mechanism is poorly understood. We recently reported that cartilage oligomeric matrix protein (COMP), a component of vascular extracellular matrix, is an endogenous inhibitor of vascular smooth muscle cell calcification. OBJECTIVE: To investigate whether COMP affects atherosclerotic calcification. METHODS AND RESULTS: ApoE(-/-)COMP(-/-) mice fed with chow diet for 12 months manifested more extensive atherosclerotic calcification in the innominate arteries than did ApoE(-/-) mice. To investigate which origins of COMP contributed to atherosclerotic calcification, bone marrow transplantation was performed between ApoE(-/-) and ApoE(-/-)COMP(-/-) mice. Enhanced calcification was observed in mice transplanted with ApoE(-/-)COMP(-/-) bone marrow compared with mice transplanted with ApoE(-/-) bone marrow, indicating that bone marrow-derived COMP may play a critical role in atherosclerotic calcification. Furthermore, microarray profiling of wild-type and COMP(-/-) macrophages revealed that COMP-deficient macrophages exerted atherogenic and osteogenic characters. Integrin ß3 protein was attenuated in COMP(-/-) macrophages, and overexpression of integrin ß3 inhibited the shift of macrophage phenotypes by COMP deficiency. Furthermore, adeno-associated virus 2-integrin ß3 infection attenuated atherosclerotic calcification in ApoE(-/-)COMP(-/-) mice. Mechanistically, COMP bound directly to ß-tail domain of integrin ß3 via its C-terminus, and blocking of the COMP-integrin ß3 association by ß-tail domain mimicked the COMP deficiency-induced shift in macrophage phenotypes. Similar to COMP deficiency in mice, transduction of adeno-associated virus 2-ß-tail domain enhanced atherosclerotic calcification in ApoE(-/-) mice. CONCLUSIONS: These results reveal that COMP deficiency acted via integrin ß3 to drive macrophages toward the atherogenic and osteogenic phenotype and thereby aggravate atherosclerotic calcification.

Sulphur dioxide suppresses inflammatory response by sulphenylating NF-κB p65 at Cys38 in a rat model of acute lung injury.

The present study was designed to investigate whether endogenous sulphur dioxide (SO2) controlled pulmonary inflammation in a rat model of oleic acid (OA)-induced acute lung injury (ALI). In this model, adenovirus expressing aspartate aminotransferase (AAT) 1 was delivered to the lungs, and the levels of SO2 and proinflammatory cytokines in rat lung tissues were measured. In the human alveolar epithelial cell line A549, the nuclear translocation and DNA binding activities of wild-type (wt) and C38S (cysteine-to-serine mutation at p65 Cys38) NF-κB p65 were detected. GFP-tagged C38S p65 was purified from HEK 293 cells and the sulphenylation of NF-κB p65 was studied. OA caused a reduction in SO2/AAT pathway activity but increased pulmonary inflammation and ALI. However, either the presence of SO2 donor, a combination of Na2SO3 and NaHSO3, or AAT1 overexpression in vivo successfully blocked OA-induced pulmonary NF-κB p65 phosphorylation and consequent inflammation and ALI. Either treatment with an SO2 donor or overexpression of AAT1 down-regulated OA-induced p65 activity, but AAT1 knockdown in alveolar epithelial cells mimicked OA-induced p65 phosphorylation and inflammation in vitro Mechanistically, OA promoted NF-κB nuclear translocation, DNA binding activity, recruitment to the intercellular cell adhesion molecule (ICAM)-1 promoter, and consequent inflammation in epithelial cells; these activities were reduced in the presence of an SO2 donor. Furthermore, SO2 induced sulphenylation of p65, which was blocked by the C38S mutation on p65 in epithelial cells. Hence, down-regulation of SO2/AAT is involved in pulmonary inflammation during ALI. Furthermore, SO2 suppressed inflammation by sulphenylating NF-κB p65 at Cys38.

[Cardiovascular Regulation by Sulfur-containing Gaseous Signaling Molecules and the Underlying Mechanisms:Updated Research Evidence].

The sulfur-containing gases hydrogen sulfide (H2S)and sulfur dioxide (SO2 )were previously considered to be waste gases. Recent studies showed that they could be endogenously generated from metabolism of the sulfur-containing amino acids in mammals. Endogenous H2S and SO2 generation pathways also existed in the cardiovascular system.H2S and SO2 had important physiological effects in the cardio-vascular system including vasorelaxation and myocardial negative inotropic effect. The pathophysiological effects of H2S and SO2 in the cardiovascular system have been recognized, such as alleviating hypertension and pulmonary hypertension, inhibiting the development of atherosclerosis, and protecting against myocardial ischemia-reperfusion (I /R)injury and isoproterenol-induced myocardial injury. Adenosine triphosphate-sensitive potassium (KATP )channel, L-type calcium (L-Ca2 +) channel, cGMP, NF-κB signaling pathway and MAPK signaling pathway and so on participated in the biological effects of H2S and SO2 .The above findings suggested that H2S and SO2 were important endogenous gaseous signaling molecules in the cardiovascular system, which provided a new way to elucidate the pathogenesis and therapeutic targets of cardiovascular diseases.

ADAMTS-7 inhibits re-endothelialization of injured arteries and promotes vascular remodeling through cleavage of thrombospondin-1.

BACKGROUND: ADAMTS-7, a member of the disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) family, was recently identified to be significantly associated genomewide with coronary artery disease. However, the mechanisms that link ADAMTS-7 and coronary artery disease risk remain elusive. We have previously demonstrated that ADAMTS-7 promotes vascular smooth muscle cell migration and postinjury neointima formation via degradation of a matrix protein cartilage oligomeric matrix protein. Because delayed endothelium repair renders neointima and atherosclerosis plaque formation after vessel injury, we examined whether ADAMTS-7 also inhibits re-endothelialization. METHODS AND RESULTS: Wire injury of the carotid artery and Evans blue staining were performed in Adamts7(-/-) and wild-type mice. Adamts-7 deficiency greatly promoted re-endothelialization at 3, 5, and 7 days after injury. Consequently, Adamts-7 deficiency substantially ameliorated neointima formation in mice at days 14 and 28 after injury in comparison with the wild type. In vitro studies further indicated that ADAMTS-7 inhibited both endothelial cell proliferation and migration. Surprisingly, cartilage oligomeric matrix protein deficiency did not affect endothelial cell proliferation/migration and re-endothelialization in mice. In a further examination of other potential vascular substrates of ADAMTS-7, a label-free liquid chromatography-tandem mass spectrometry secretome analysis revealed thrombospondin-1 as a potential ADAMTS-7 target. The subsequent studies showed that ADAMTS-7 was directly associated with thrombospondin-1 by its C terminus and degraded thrombospondin-1 in vivo and in vitro. The inhibitory effect of ADAMTS-7 on postinjury endothelium recovery was circumvented in Tsp1(-/-) mice. CONCLUSIONS: Our study revealed a novel mechanism by which ADAMTS-7 affects neointima formation. Thus, ADAMTS-7 is a promising treatment target for postinjury vascular intima hyperplasia.

Cartilage oligomeric matrix protein prevents vascular aging and vascular smooth muscle cells senescence.

Aging-related vascular dysfunction contributes to cardiovascular morbidity and mortality. Cartilage oligomeric matrix protein (COMP), a vascular extracellular matrix protein, has been described as a negative regulatory factor for the vascular aging-related processes including atherosclerosis and vascular calcification. However, whether COMP is implicated in the process of vascular aging remains unclear. Here, we identified a novel function of COMP in preventing vascular aging and vascular smooth muscle cells (VSMCs) senescence. Firstly, vascular COMP expression was decreased in three different senescence-accelerated mouse models and was also declining with age. COMP(-/-) mice displayed elevated senescence-associated markers expression, including p53, p21 and p16, in the aortas compared with their wild type (WT) littermates. In accordance, COMP deficiency induced aging-related vascular dysfunction as evidenced by the significantly reduced phenylephrine-induced contraction and increased vascular stiffness as evaluated by pulse wave velocity. The aortic wall of COMP(-/-) mice was susceptible to senescence by displaying senescence-associated ß-galactosidase (SA ß-gal) activity induced by periadventitial application of CaCl2 to the abdominal aorta. In vitro, COMP knockdown by small interfering (si) RNA led to the elevation of p53, p21 and p16 as well as SA ß-gal activity in VSMCs after H2O2 stimulation. VSMCs isolated from COMP(-/-) mice showed elevated senescence-associated markers expression and supplement of COMP adenovirus to COMP-deficient VSMCs greatly rescued cellular senescence. Taken together, these findings revealed the essential role of COMP in retarding the development of vascular aging and VSMC senescence.

The vasodilatory effect of sulfur dioxide via SGC/cGMP/PKG pathway in association with sulfhydryl-dependent dimerization.

The present study was designed to explore the role of soluble guanylate cyclase (sGC)/cyclic guanosine monophosphate (cGMP)/PKG pathway in sulfur dioxide (SO2)-induced vasodilation. We showed that SO2 induced a concentration-dependent relaxation of phenylephrine (PE)-precontracted rat aortic rings in association with an increase in cGMP concentration, whereas l-aspartic acid ß-hydroxamate (HDX), an inhibitor of SO2 synthase, contracted rings in a dose-dependent manner. Pretreatment of aortic rings with the sGC inhibitor ODQ (30 µM) attenuated the vasodilatory effects of SO2, suggesting the involvement of cGMP pathway in SO2-induced vasodilation. Mechanistically, SO2 upregulated the protein levels of sGC and PKG dimers, while HDX inhibited it, indicating SO2 could promote cGMP synthesis through sGC activation. Furthermore, the dimerization of sGC and PKG and vasodilation induced by SO2 in precontracted rings were significantly prevented by thiol reductants dithiothreitol (DTT). In addition, SO2 reduced the activity of phosphodiesterase type 5 (PDE5), a cGMP-specific hydrolytic enzyme, implying that SO2 elevated cGMP concentration by inhibiting its hydrolysis. Hence, SO2 exerted its vasodilatory effects at least partly by promoting disulfide-dependent dimerization of sGC and PKG, resulting in an activated sGC/cGMP/PKG pathway in blood vessels. These findings revealed a new mode of action and mechanisms by which SO2 regulated the vascular tone.

Endogenous Sulfur Dioxide Inhibits Vascular Calcification in Association with the TGF-ß/Smad Signaling Pathway.

The study was designed to investigate whether endogenous sulfur dioxide (SO2) plays a role in vascular calcification (VC) in rats and its possible mechanisms. In vivo medial vascular calcification was induced in rats by vitamin D3 and nicotine for four weeks. In vitro calcification of cultured A7r5 vascular smooth muscle cells (VSMCs) was induced by calcifying media containing 5 mmol/L CaCl2. Aortic smooth muscle (SM) α-actin, runt-related transcription factor 2 (Runx2), transforming growth factor-ß (TGF-ß) and Smad expression was measured. VC rats showed dispersed calcified nodules among the elastic fibers in calcified aorta with increased aortic calcium content and alkaline phosphatase (ALP) activity. SM α-actin was markedly decreased, but the osteochondrogenic marker Runx2 concomitantly increased and TGF-ß/Smad signaling was activated, in association with the downregulated SO2/aspartate aminotransferase (AAT) pathway. However, SO2 supplementation successfully ameliorated vascular calcification, and increased SM α-actin expression, but inhibited Runx2 and TGF-ß/Smad expression. In calcified A7r5 VSMCs, the endogenous SO2/AAT pathway was significantly downregulated. SO2 treatment reduced the calcium deposits, calcium content, ALP activity and Runx2 expression and downregulated the TGF-ß/Smad pathway in A7r5 cells but increased SM α-actin expression. In brief, SO2 significantly ameliorated vascular calcification in association with downregulation of the TGF-ß/Smad pathway.

Hydrogen sulfide suppresses oxidized low-density lipoprotein (ox-LDL)-stimulated monocyte chemoattractant protein 1 generation from macrophages via the nuclear factor κB (NF-κB) pathway.

This study was designed to examine the role of hydrogen sulfide (H2S) in the generation of oxidized low-density lipoprotein (ox-LDL)-stimulated monocyte chemoattractant protein 1 (MCP-1) from macrophages and possible mechanisms. THP-1 cells and RAW macrophages were pretreated with sodium hydrosulfide (NaHS) and hexyl acrylate and then treated with ox-LDL. The results showed that ox-LDL treatment down-regulated the H2S/cystathionine-ß-synthase pathway, with increased MCP-1 protein and mRNA expression in both THP-1 cells and RAW macrophages. Hexyl acrylate promoted ox-LDL-induced inflammation, whereas the H2S donor NaHS inhibited it. NaHS markedly suppressed NF-κB p65 phosphorylation, nuclear translocation, DNA binding activity, and recruitment to the MCP-1 promoter in ox-LDL-treated macrophages. Furthermore, NaHS decreased the ratio of free thiol groups in p65, whereas the thiol reductant DTT reversed the inhibiting effect of H2S on the p65 DNA binding activity. Most importantly, site-specific mutation of cysteine 38 to serine in p65 abolished the effect of H2S on the sulfhydration of NF-κB and ox-LDL-induced NF-κB activation. These results suggested that endogenous H2S inhibited ox-LDL-induced macrophage inflammation by suppressing NF-κB p65 phosphorylation, nuclear translocation, DNA binding activity, and recruitment to the MCP-1 promoter. The sulfhydration of free thiol group on cysteine 38 in p65 served as a molecular mechanism by which H2S inhibited NF-κB pathway activation in ox-LDL-induced macrophage inflammation.

Hydrogen sulfide alleviates myocardial collagen remodeling in association with inhibition of TGF-ß/Smad signaling pathway in spontaneously hypertensive rats.

The study was designed to explore the role and possible mechanisms of hydrogen sulfide (H2S) in the regulation of myocardial collagen remodeling in spontaneously hypertensive rats (SHRs). We treated nine-week-old male SHRs and age- and sex-matched Wistar-Kyoto rats (WKYs) with NaHS (90 µmol/kg(-1)·day(-1)) for 9 wks. At 18 wks, plasma H2S, tail arterial pressure, morphology of the heart, myocardial ultrastructure and collagen volume fraction (CVF), myocardial expressions of collagen I and III protein and procollagen I and III mRNA, transforming growth factor-ß1 (TGF-ß1), TGF-ß type I receptor (TßR-I), type II receptor (TßR-II), p-Smad2 and 3, matrix metalloproteinase (MMP)-13 and tissue inhibitors of MMP (TIMP)-1 proteins were determined. TGF-ß1-stimulated cultured cardiac fibroblasts (CFs) were used to further study the mechanisms. The results showed that compared with WKYs, SHRs showed a reduced plasma H2S, elevated tail artery pressure and increased myocardial collagen, TGF-ß1, TßR-II, p-Smad2 and p-Smad3 expressions. However, NaHS markedly decreased tail artery pressure and inhibited myocardial collagen, TGF-ß1, TßR-II, p-Smad2 and p-Smad3 protein expressions, but H2S had no effect on the expressions of MMP-13 and TIMP-1. Hydralazine reduced blood pressure but had no effect on myocardial collagen, MMP-13 and TIMP-1 expressions and TGF-ß1/Smad signaling pathway. H2S prevented activation of the TGF-ß1/Smad signaling pathway and abnormal collagen synthesis in CFs. In conclusion, the results suggested that H2S could prevent myocardial collagen remodeling in SHR. The mechanism might be associated with inhibition of collagen synthesis via TGF-ß1/Smad signaling pathway.