Interleukin-6, S-Nitrosothiols, and Neurodegeneration in Different Central Nervous System Demyelinating Disorders: Is There a Relationship?

BACKGROUND AND PURPOSE: A few groups have suggested that activated cytokines and nitrosative stress are closely involved in the pathogenesis of different demyelinating disorders induced by the neuroinflammatory destruction of neurons. The purpose of this study was to elucidate the associations of cytokines and S-nitrosothiols (RSNO) with the severity of neurodegeneration during relapse in demyelinating disorders of the central nervous system. METHODS: We measured levels of interleukin-6 (IL-6), erythropoietin, RSNO, and phosphorylated neurofilament heavy chain (pNfh) in cerebrospinal fluid (CSF) samples obtained from patients with different demyelinating disorders: multiple sclerosis (MS, n=52), acute disseminated encephalomyelitis (ADEM, n=9), and neuromyelitis optica spectrum disorders (NMOSD) with aquaporin-4 immunoglobulin G (AQP4-IgG, n=12). We compared these levels with those measured in a control group (n=24). RESULTS: We found that IL-6 in CSF was elevated in NMOSD with AQP4-IgG and ADEM patients as well as in MS patients after the destruction of soluble IL-6. Erythropoietin levels were lower in MS, while RSNO levels were higher in NMOSD with AQP4-IgG and MS patients than in the control group. CSF pNfh levels were elevated in MS and ADEM patients. CONCLUSIONS: These results confirm that IL-6 is activated in different demyelinating disorders, with this elevation being more prominent in the CSF of NMOSD with AQP4-IgG and ADEM patients. Moreover, S-nitrosylation is activated in demyelinating disorders with spinal-cord injury and neurodegeneration in these patients. However, we found no correlation between these biochemical markers, and so we could not confirm whether IL-6-mediated nitric oxide production is involved in spinal-cord lesions.

S-Nitroso-N-acetyl-L-cysteine ethyl ester (SNACET) and N-acetyl-L-cysteine ethyl ester (NACET)–Cysteine-based drug candidates with unique pharmacological profiles for oral use as NO, H2S and GSH suppliers and as antioxidants: Results and overview / 药物分析学报

S-Nitrosothiols or thionitrites with the general formula RSNO are formally composed of the nitrosylcation(NO+)and a thiolate(RS-),the base of the corresponding acids RSH.The smallest S-nitrosothiol isHSNO and derives from hydrogen sulfide(HSH,H2S).The most common physiological S-nitrosothiols arederived from the amino acid L-cysteine(CysSH).Thus,the simplest S-nitrosothiol is S-nitroso-L-cysteine(CysSNO).CysSNO is a spontaneous potent donor of nitric oxide(NO)which activates soluble guanylylcyclase to form cyclic guanosine monophosphate(cGMP).This activation is associated with multiplebiological actions that include relaxation of smooth muscle cells and inhibition of platelet aggregation.Like NO,CysSNO is a short-lived species and occurs physiologically at concentrations around 1 nM inhuman blood.CysSNO can be formed from CysSH and higher oxides of NO including nitrous acid(HONO)and its anhydride(N2O3).The most characteristic feature of RSNO is the S-transnitrosation reaction bywhich the NO+group is reversibly transferred to another thiolate.By this way numerous RSNO can beformed such as the low-molecular-mass S-nitroso-N-acetyl-L-cysteine(SNAC)and S-nitroso-glutathione(GSNO),and the high-molecular-mass S-nitrosol-L-cysteine hemoglobin(HbCysSNO)present in erythrocytesand S-nitrosol-L-cysteine albumin(AlbCysSNO)present in plasma at concentrations of theorder of 200 nM.All above mentioned RSNO exert NO-related biological activity,but they must be administeredintravenously.This important drawback can be overcome by lipophilic charge-free RSNO.Thus,we prepared the ethyl ester of SNAC,the S-nitroso-N-acetyl-L-cysteine ethyl ester(SNACET),fromsynthetic N-acetyl-L-cysteine ethyl ester(NACET).Both NACET and SNACET have improved pharmacologicalfeatures over N-acetyl-L-cysteine(NAC)and S-nitroso-N-acetyl-L-cysteine(SNAC),respectively,including higher oral bioavailability.SNACET exerts NO-related activities which can be utilized in theurogenital tract and in the cardiovascular system.NACET,with high oral bioavailability,is a strong antioxidantand abundant precursor of GSH,unlike its free acid N-acetyl-L-cysteine(NAC).Here,we reviewthe chemical and pharmacological properties of SNACET and NACET as well as their analytical chemistry.We also report new results from the ingestion of S-[15N]nitroso-N-acetyl-L-cysteine ethyl ester(S15NACET)demonstrating the favorable pharmacological profile of SNACET.

Assessment of ocular surface toxicity after topical instillation of nitric oxide donors / Avaliação da toxicidade na superfície ocular após instilação tópica de doadores de óxido nítrico

PURPOSE: To evaluate the ocular surface toxicity of two nitric oxide donors in ex vivo and in vivo animal models: S-nitrosoglutathione (GSNO) and S-nitroso-N-acetylcysteine (SNAC) in a hydroxypropyl methylcellulose (HPMC) matrix at final concentrations 1.0 and 10.0 mM. METHODS: Ex vivo GSNO and SNAC toxicities were clinically and histologically analyzed using freshly excised pig eyeballs. In vivo experiments were performed with 20 albino rabbits which were randomized into 4 groups (5 animals each): Groups 1 and 2 received instillations of 150 µL of aqueous HPMC solution containing GSNO 1.0 and 10.0 mM, respectively, in one of the eyes; Groups 3 and 4 received instillations of 150 µL of aqueous HPMC solution-containing SNAC 1.0 and 10.0 mM, respectively, in one of the eyes. The contralateral eyes in each group received aqueous HPMC as a control. All animals underwent clinical evaluation on a slit lamp and the eyes were scored according to a modified Draize eye test and were histologically analyzed. RESULTS: Pig eyeballs showed no signs of perforation, erosion, corneal opacity or other gross damage. These findings were confirmed by histological analysis. There was no difference between control and treated rabbit eyes according to the Draize eye test score in all groups (p>0.05). All formulations showed a mean score under 1 and were classified as "non-irritating". There was no evidence of tissue toxicity in the histological analysis in all animals. CONCLUSION: Aqueous HPMC solutions containing GSNO and SNAC at concentrations up to 10.0 mM do not induce ocular irritation.

OBJETIVO: Avaliar a toxidade na superfície ocular de dois compostos doadores de óxido nítrico em modelos ex vivo e in vivo: S-nitrosoglutationa (GSNO) e S-nitroso-N-acetilcisteína (SNAC), em uma matriz de hidroxipropil metilcelulose (HPMC) nas concentrações finais de 1,0 and 10,0 mM. MÉTODOS: As toxicidades de GSNO e SNAC foram avaliadas clinicamente e histologicamente em modelo ex vivo usando globos oculares porcinos recém excisados. Experimentos in vivo foram realizados com 20 coelhos albinos que foram randomizados em 4 grupos (5 animais em cada): Os grupos 1 e 2 receberam instilações de 150 µL de solução aquosa de HPMC contendo GSNO 1,0 e 10,0 mM, respectivamente, em um dos olhos; Os grupos 3 e 4 receberam instilações de 150 µL de solução aquosa de HPMC contendo SNAC 1,0 and 10,0 mM, respectivamente, em um dos olhos. Os olhos contralaterias em cada grupo receberam solução aquosa de HPMC como controle. Todos os animais foram clinicamente avaliados em lâmpada de fenda e os olhos foram pontuados de acordo com o teste de Draize modificado e analisados histologicamente. RESULTADOS: Os globos oculares porcinos não apresentaram sinais de perfuração, erosão, opacidade da córnea ou outros danos graves. Esses resultados foram confirmados pela análise histológica. Não houve diferença entre os olhos dos coelhos tratados e controles de acordo com a pontuação do teste de Draize em todos os grupos (p>0,05). Todas as formulações apresentaram um escore médio menor do que 1 e foram classificadas como "não-irritantes". Não houve evidência de toxicidade tecidual nas análises histológicas em todos os animais. CONCLUSÃO: Soluções aquosas de HPMC contendo GSNO e SNAC em concentrações até 10,0 mM não induzem irritação ocular.

Overproduction of nitrate and S-nitrosothiols in diabetic patients / 老年心脏病学杂志（英文版）

Objective The present study was designed to investigate changes in serum or plasma concentrations of nitric oxide and its derivatives in diabetic patients.Methods Serum nitrate concentration of 84 diabetic patients was measured by using an enzyme kinetic method,and the plasma S-nitrosothiols concentration of 10 cases was measured by using HPLC technique.Results Serum nitrate concentration and plasma S-nitrosothiols concentration in the diabetics were significantly higher than in control group (P＜0.01 andP＜0.05,respectively).The serum nitrate concentration in diabetics also had a significant positive correlation with the serum glucose concentration (R=0.7256,P＜0.05),but this correlation was not found in control group.Conclusion These data showed that NO and its derivatives are overproduced in the diabetic patients.(J Geriatr Cardiol 2008;5:25-27)