Browsing by Author "Trajkovic, V. (7004516866)"

The influence of a nucleoside analog 5-aza-2′-deoxycytidine (5-AzadC) on inducible nitric oxide synthase (iNOS)-dependent nitric oxide (NO) production in various rat cell types was investigated. In C6 astrocytoma cell line and primary astrocytes, 5-AzadC enhanced proinflammatory cytokine (IFN-γ, TNF-α, IL-1)-triggered NO synthesis in a time- and dose-dependent manner. In contrast, 5-AzadC did not potentiate NO production in IFN-γ-stimulated macrophages, fibroblasts, or endothelial cells. Blockade of transcription or translation in C6 cells abolished the observed effect, suggesting the iNOS gene expression, rather than its catalytic activity, as a target for the drug action. Accordingly, 5-AzadC upregulated IFN-γ-induced expression of iNOS mRNA in C6 astrocytes. The effect of 5-AzadC on astrocyte NO release was blocked by the inhibitor of p44/42 mitogen activated protein kinase-dependent signaling. Finally, the observed stimulatory effect of 5-AzadC on iNOS expression was apparently independent of DNA demethylation, as DNA digestion with methylation-sensitive restriction enzyme HpaII showed that 5-AzadC failed to demethylate cellular DNA in conditions used for iNOS induction. © 2003 Elsevier B.V. All rights reserved.

The influence of a nucleoside analog 5-aza-2′-deoxycytidine (5-AzadC) on inducible nitric oxide synthase (iNOS)-dependent nitric oxide (NO) production in various rat cell types was investigated. In C6 astrocytoma cell line and primary astrocytes, 5-AzadC enhanced proinflammatory cytokine (IFN-γ, TNF-α, IL-1)-triggered NO synthesis in a time- and dose-dependent manner. In contrast, 5-AzadC did not potentiate NO production in IFN-γ-stimulated macrophages, fibroblasts, or endothelial cells. Blockade of transcription or translation in C6 cells abolished the observed effect, suggesting the iNOS gene expression, rather than its catalytic activity, as a target for the drug action. Accordingly, 5-AzadC upregulated IFN-γ-induced expression of iNOS mRNA in C6 astrocytes. The effect of 5-AzadC on astrocyte NO release was blocked by the inhibitor of p44/42 mitogen activated protein kinase-dependent signaling. Finally, the observed stimulatory effect of 5-AzadC on iNOS expression was apparently independent of DNA demethylation, as DNA digestion with methylation-sensitive restriction enzyme HpaII showed that 5-AzadC failed to demethylate cellular DNA in conditions used for iNOS induction. © 2003 Elsevier B.V. All rights reserved.

The effect of intracellular cAMP rise on nitric oxide (NO) production was compared in murine primary fibroblasts isolated from the spleens of CBA mice, and L929 fibrosarcoma cell line. Treatment of confluent L929 cells with cAMP analogues -dibutyryl-cAMP (db-cAMP) or 8-Cl-cAMP caused dose-dependent augmentation of inducible NO synthase (iNOS)-mediated NO production, which has been abrogated by inhibition of protein synthesis with cycloheximide or addition of selective iNOS inhibitor aminoguanidine. In contrast, under the same cultivating conditions, cAMP analogues were not able to upregulate NO synthesis in primary fibroblasts. Treatment with cAMP analogues or non- selective phosphodiesterase (PDE) inhibitor pentoxifylline affected IFNγ- induced NO synthesis in both cell types, but in the opposite manner-enhancing in L929 cells and suppressive in primary fibroblasts. The induction of iNOS, but not its catalytic activity, was impaired in cAMP-treated primary fibroblasts. Finally, PDE type IV inhibitor rolipram enhanced IFN-γ- triggered NO synthesis in L929 cells, but was unable to mimic cAMP analogue or PTX-mediated suppression of NO synthesis in spleen fibroblasts. These results suggest that, in contrast to L929 fibrosarcoma cell line, intracellular cAMP rise might have a role in downregulation of NO production in murine primary fibroblasts. (C) 2000 Elsevier Science B.V.

The effect of intracellular cAMP rise on nitric oxide (NO) production was compared in murine primary fibroblasts isolated from the spleens of CBA mice, and L929 fibrosarcoma cell line. Treatment of confluent L929 cells with cAMP analogues -dibutyryl-cAMP (db-cAMP) or 8-Cl-cAMP caused dose-dependent augmentation of inducible NO synthase (iNOS)-mediated NO production, which has been abrogated by inhibition of protein synthesis with cycloheximide or addition of selective iNOS inhibitor aminoguanidine. In contrast, under the same cultivating conditions, cAMP analogues were not able to upregulate NO synthesis in primary fibroblasts. Treatment with cAMP analogues or non- selective phosphodiesterase (PDE) inhibitor pentoxifylline affected IFNγ- induced NO synthesis in both cell types, but in the opposite manner-enhancing in L929 cells and suppressive in primary fibroblasts. The induction of iNOS, but not its catalytic activity, was impaired in cAMP-treated primary fibroblasts. Finally, PDE type IV inhibitor rolipram enhanced IFN-γ- triggered NO synthesis in L929 cells, but was unable to mimic cAMP analogue or PTX-mediated suppression of NO synthesis in spleen fibroblasts. These results suggest that, in contrast to L929 fibrosarcoma cell line, intracellular cAMP rise might have a role in downregulation of NO production in murine primary fibroblasts. (C) 2000 Elsevier Science B.V.

The new immunosuppressive agent mycophenolate mofetil (MMF) has been shown recently to exert a protective effects in certain animal models of autoimmunity, including diabetes in diabetes-prone bio-breeding (BB) rats. In the present study, the immunomodulatory potential of MMF was investigated in autoimmune diabetes induced by multiple low doses of streptozotocin (MLD-STZ) in genetically susceptible DA rats [20 mg STZ/kg body weight (b.w.) for 5 days] and CBA/H mice (40 mg STZ/kg b.w. for 5 days). In both species, short time treatment of animals with MMF (25 mg/kg) during the early development of the disease, as well as continuous MMF treatment, prevented the appearance of hyperglycaemia and inflammatory infiltrates in the pancreatic tissue. Moreover, clinical manifestations of diabetes were suppressed by application of the drug after the onset of clinical symptoms. Treatment with guanosine (1 mg/kg) in parallel with MMF completely reversed MMF activity in vivo, indicating that inhibition of inosine monophosphate dehydrogenase (IMPDH) was responsible for the observed suppressive effects. MMF-mediated protection from diabetes correlated with reduced ex vivo spontaneous spleen mononuclear cell (MNC) proliferation and defective adhesive cell interactions. MMF-treated animals also had lower local production of IFN-γ, as well as IL-12 and nitric oxide (NO) production by peripheral tissues (spleen and peritoneal cells), compared to that in control diabetic groups, while IL-10 level was elevated. Together, these data demonstrate that MMF interferes with autoimmune process in streptozotocin-induced diabetes at multiple levels, including lymphocyte proliferation and adhesion, as well as pro/anti-inflammatory cytokine balance.

Mycophenolic acid (MPA) and A77 1726, the active components of the immunosuppressants mycophenolate mophetil and leflunomide, respectively, in a dose-dependent manner inhibited interferon (IFN)-γ/LPS-induced interleukin (IL)-6 release in confluent cultures of mouse L929 fibrosarcoma cells. In addition, both drugs markedly reduced the production of the free radical gas nitric oxide (NO), without affecting the viability of L929 cells. The inhibitors of NO synthase, aminoguanidine and L-NMMA, but not L-NMMA inactive counterpart D-NMMA, mimicked the effects of A77 1726 and MPA on IL-6 generation in L929 fibroblasts. Furthermore, NO-releasing substance SNP completely reverted IL-6 accumulation in L929 cultures treated with A77 1726, while only partial recovery of IL-6 production was observed in the presence of MPA. MPA, but not A77 1726, significantly suppressed NO-independent IL-6 release triggered by cAMP-elevating agent rolipram. Thus, while A77 1726 effect on IL-6 production was mediated through concomitant reduction of NO synthesis, MPA action was mainly independent of the interference with NO generation. Finally, both agents inhibited IFN-γ/LPS-triggered IL-6 production in mouse primary fibroblasts, but not in mouse peritoneal macrophages, indicating cell-specificity of this novel anti-inflammatory action of A77 1726 and MPA. © 2002 Published by Elsevier Science Ltd.

Mycophenolic acid (MPA) and A77 1726, the active components of the immunosuppressants mycophenolate mophetil and leflunomide, respectively, in a dose-dependent manner inhibited interferon (IFN)-γ/LPS-induced interleukin (IL)-6 release in confluent cultures of mouse L929 fibrosarcoma cells. In addition, both drugs markedly reduced the production of the free radical gas nitric oxide (NO), without affecting the viability of L929 cells. The inhibitors of NO synthase, aminoguanidine and L-NMMA, but not L-NMMA inactive counterpart D-NMMA, mimicked the effects of A77 1726 and MPA on IL-6 generation in L929 fibroblasts. Furthermore, NO-releasing substance SNP completely reverted IL-6 accumulation in L929 cultures treated with A77 1726, while only partial recovery of IL-6 production was observed in the presence of MPA. MPA, but not A77 1726, significantly suppressed NO-independent IL-6 release triggered by cAMP-elevating agent rolipram. Thus, while A77 1726 effect on IL-6 production was mediated through concomitant reduction of NO synthesis, MPA action was mainly independent of the interference with NO generation. Finally, both agents inhibited IFN-γ/LPS-triggered IL-6 production in mouse primary fibroblasts, but not in mouse peritoneal macrophages, indicating cell-specificity of this novel anti-inflammatory action of A77 1726 and MPA. © 2002 Published by Elsevier Science Ltd.

Objective: To compare the concentrations of cytokines belonging to Th17 axis (interleukin (IL)-17 and IL-23) and Th1 axis (IL-12 and interferon (IFN)-γ) in obese and lean women, and to investigate their relationships with the proinflammatory adipokine leptin, proinflammatory cytokine macrophage migration inhibitory factor (MIF) and anthropometric and metabolic parameters of obesity. Design: Cross-sectional study. Subjects: Twenty-six obese women (age 20-52 years, body mass index (BMI): 30-48 kg/m2) and 20 healthy lean women (age 23-46 years, BMI: 18-25 kg/m2). Measurements: Plasma levels of cytokines and leptin, BMI, waist circumference (WC) and insulin resistance index HOMA (homeostatic model assessment). Results: Blood concentrations of IL-17, IL-23, MIF and leptin, but not IL-12 or IFN-γ, were higher in obese compared with lean women (P=0.002, 0.046, 0.006 and 0.002, respectively). There was a positive correlation between IL-17 and IL-23 (r s=0.530), which was at the border of statistical significance (P=0.065). Neither IL-17 nor IL-23 correlated with leptin or MIF, and there was no association between IL-17 and IL-23 levels with BMI, WC or HOMA index. Conclusion: Interleukin-23/IL-17 axis is stimulated in obese women independently of the increase in abdominal fat, insulin resistance, leptin and MIF levels. © 2009 Macmillan Publishers Limited All rights reserved.

Objective: To compare the concentrations of cytokines belonging to Th17 axis (interleukin (IL)-17 and IL-23) and Th1 axis (IL-12 and interferon (IFN)-γ) in obese and lean women, and to investigate their relationships with the proinflammatory adipokine leptin, proinflammatory cytokine macrophage migration inhibitory factor (MIF) and anthropometric and metabolic parameters of obesity. Design: Cross-sectional study. Subjects: Twenty-six obese women (age 20-52 years, body mass index (BMI): 30-48 kg/m2) and 20 healthy lean women (age 23-46 years, BMI: 18-25 kg/m2). Measurements: Plasma levels of cytokines and leptin, BMI, waist circumference (WC) and insulin resistance index HOMA (homeostatic model assessment). Results: Blood concentrations of IL-17, IL-23, MIF and leptin, but not IL-12 or IFN-γ, were higher in obese compared with lean women (P=0.002, 0.046, 0.006 and 0.002, respectively). There was a positive correlation between IL-17 and IL-23 (r s=0.530), which was at the border of statistical significance (P=0.065). Neither IL-17 nor IL-23 correlated with leptin or MIF, and there was no association between IL-17 and IL-23 levels with BMI, WC or HOMA index. Conclusion: Interleukin-23/IL-17 axis is stimulated in obese women independently of the increase in abdominal fat, insulin resistance, leptin and MIF levels. © 2009 Macmillan Publishers Limited All rights reserved.

[No abstract available]

To explore the role of the 10-kDa Mycobacterium tuberculosis-specific secreted antigen (MTSA-10 or CFP-10) in modulation of macrophage function, J774 macrophages were transfected stably with DNA encoding MTSA-10. Compared to normal or mock-transfected controls, MTSA-10-expressing macrophages had markedly lower levels of co-stimulatory molecule B7·1 on their surface, while the expression of B7·2 and ICAM-1 was not affected. MTSA-transfected cells also produced significantly less microbicidal free radical nitric oxide (NO) upon stimulation with interferon (IFN)-γ, lipopolysaccharide or M. tuberculosis cell lysate. Western blot analysis revealed the absence of tyrosine-phosphorylated protein slightly larger than 112 kDa in MTSA-transfected macrophages. Moreover, the treatment of control J774 cells with protein tyrosine kinase inhibitor genistein completely mimicked the effects of transfection with MTSA-10, selectively down-regulating NO and B7·1, but not B7·2 or ICAM-1 expression. The observed MTSA-10-mediated block of B7·1 expression and NO release might contribute to the suppression of antimycobacterial response in tuberculosis.

To explore the role of the 10-kDa Mycobacterium tuberculosis-specific secreted antigen (MTSA-10 or CFP-10) in modulation of macrophage function, J774 macrophages were transfected stably with DNA encoding MTSA-10. Compared to normal or mock-transfected controls, MTSA-10-expressing macrophages had markedly lower levels of co-stimulatory molecule B7·1 on their surface, while the expression of B7·2 and ICAM-1 was not affected. MTSA-transfected cells also produced significantly less microbicidal free radical nitric oxide (NO) upon stimulation with interferon (IFN)-γ, lipopolysaccharide or M. tuberculosis cell lysate. Western blot analysis revealed the absence of tyrosine-phosphorylated protein slightly larger than 112 kDa in MTSA-transfected macrophages. Moreover, the treatment of control J774 cells with protein tyrosine kinase inhibitor genistein completely mimicked the effects of transfection with MTSA-10, selectively down-regulating NO and B7·1, but not B7·2 or ICAM-1 expression. The observed MTSA-10-mediated block of B7·1 expression and NO release might contribute to the suppression of antimycobacterial response in tuberculosis.

Although the inhibitory effect of iron on macrophage production of tumoricidal free radical nitric oxide (NO) has been reported, its possible influence on macrophage anti-tumour activity has not been established. In the present study, FeSO 4 markedly reduced IFN-γ+ LPS-induced NO synthesis in mouse and rat macrophages. The effect of iron coincided with the loss of macrophage cytotoxic activity against NO-sensitive C6 rat astrocytoma and L929 mouse fibrosarcoma cell lines, as measured by MTT assay for cellular respiration and the crystal violet test for cell viability. Tumour cell survival did not improve further in the presence of FeSO 4 if macrophage NO release and cytotoxicity were already blocked by aminoguanidine. In accordance with the results obtained with exogenous iron, cell membrane permeable iron chelator o-phenanthroline enhanced both macrophage NO release and anti-tumour activity. Iron also down-regulated NO production and increased the viability of L929 fibrosarcoma cells stimulated with IFN-γ+ LPS in the absence of macrophages. However, neither NO release nor cell viability was affected by iron addition to cultures of the C6 astrocytoma cell line. Iron was unable to prevent L929 and C6 cell death induced by the NO releasing chemicals SNP and SIN-1, indicating that iron-mediated inhibition of NO synthesis, rather than interference with its cytotoxic action, was responsible for the protection of tumour cells. Collectively, these results indicate that iron might protect tumour cells by reducing both macrophage and tumour cell-derived NO release.

Although the inhibitory effect of iron on macrophage production of tumoricidal free radical nitric oxide (NO) has been reported, its possible influence on macrophage anti-tumour activity has not been established. In the present study, FeSO 4 markedly reduced IFN-γ+ LPS-induced NO synthesis in mouse and rat macrophages. The effect of iron coincided with the loss of macrophage cytotoxic activity against NO-sensitive C6 rat astrocytoma and L929 mouse fibrosarcoma cell lines, as measured by MTT assay for cellular respiration and the crystal violet test for cell viability. Tumour cell survival did not improve further in the presence of FeSO 4 if macrophage NO release and cytotoxicity were already blocked by aminoguanidine. In accordance with the results obtained with exogenous iron, cell membrane permeable iron chelator o-phenanthroline enhanced both macrophage NO release and anti-tumour activity. Iron also down-regulated NO production and increased the viability of L929 fibrosarcoma cells stimulated with IFN-γ+ LPS in the absence of macrophages. However, neither NO release nor cell viability was affected by iron addition to cultures of the C6 astrocytoma cell line. Iron was unable to prevent L929 and C6 cell death induced by the NO releasing chemicals SNP and SIN-1, indicating that iron-mediated inhibition of NO synthesis, rather than interference with its cytotoxic action, was responsible for the protection of tumour cells. Collectively, these results indicate that iron might protect tumour cells by reducing both macrophage and tumour cell-derived NO release.

Highly reactive gaseous free radical nitric oxide (NO), generated by astrocytes and infiltrating macrophages is implicated in inflammatory destruction of brain tissue, including that occurring in multiple sclerosis. Therefore, the influence of immunosuppressive drug leflunomide on inducible nitric oxide synthase (iNOS)-dependent NO production in rat astrocytes and macrophages was investigated. Under the same cultivating conditions, leflunomide's active metabolite A77 1726 caused a dose-dependent decrease of NO production in IFN-γ+LPS-stimulated primary astrocytes, but not in macrophages. While A77 1726 did not alter iNOS enzymatic activity, it markedly suppressed IFN-γ+LPS-triggered expression of iNOS mRNA in astrocytes. In the presence of transcription inhibitor actinomycin D, A77 1726 failed to inhibit astrocyte NO production, suggesting transcriptional regulation of iNOS by leflunomide. This assumption was further supported by the ability of A77 1726 to inhibit IFN-γ+LPS-induced expression of mRNA for an important iNOS transcription factor IRF-1. PD98059, a specific inhibitor of mitogen-activated protein kinase kinase (MAPKK/MEK), but not genistein, an unselective protein tyrosine kinase inhibitor, completely mimicked cell type-specific inhibition of NO synthesis by A77 1726. Therefore, previously described inhibition of MEK/MAP pathway by leflunomide could present a possible mechanism for A77 1726-mediated suppression of iNOS activation in astrocytes. Accordingly to results obtained with primary astrocytes, both A77 1726 and PD98059 significantly reduced IFN-γ+LPS-induced NO synthesis in the cultures of rat astrocytoma cell line C6. The ability to suppress iNOS induction in astrocytes supports potential use of leflunomide in the treatment of multiple sclerosis and other NO-dependent inflammatory brain disorders. © 2001 Elsevier Science B.V.

Highly reactive gaseous free radical nitric oxide (NO), generated by astrocytes and infiltrating macrophages is implicated in inflammatory destruction of brain tissue, including that occurring in multiple sclerosis. Therefore, the influence of immunosuppressive drug leflunomide on inducible nitric oxide synthase (iNOS)-dependent NO production in rat astrocytes and macrophages was investigated. Under the same cultivating conditions, leflunomide's active metabolite A77 1726 caused a dose-dependent decrease of NO production in IFN-γ+LPS-stimulated primary astrocytes, but not in macrophages. While A77 1726 did not alter iNOS enzymatic activity, it markedly suppressed IFN-γ+LPS-triggered expression of iNOS mRNA in astrocytes. In the presence of transcription inhibitor actinomycin D, A77 1726 failed to inhibit astrocyte NO production, suggesting transcriptional regulation of iNOS by leflunomide. This assumption was further supported by the ability of A77 1726 to inhibit IFN-γ+LPS-induced expression of mRNA for an important iNOS transcription factor IRF-1. PD98059, a specific inhibitor of mitogen-activated protein kinase kinase (MAPKK/MEK), but not genistein, an unselective protein tyrosine kinase inhibitor, completely mimicked cell type-specific inhibition of NO synthesis by A77 1726. Therefore, previously described inhibition of MEK/MAP pathway by leflunomide could present a possible mechanism for A77 1726-mediated suppression of iNOS activation in astrocytes. Accordingly to results obtained with primary astrocytes, both A77 1726 and PD98059 significantly reduced IFN-γ+LPS-induced NO synthesis in the cultures of rat astrocytoma cell line C6. The ability to suppress iNOS induction in astrocytes supports potential use of leflunomide in the treatment of multiple sclerosis and other NO-dependent inflammatory brain disorders. © 2001 Elsevier Science B.V.

Mycophenolate mofetil (MMF) is an immunosuppressive drug that acts as a selective inhibitor of inosine monophosphate dehydrogenase (IMPDH). MMF has recently been shown to inhibit the enzymatic activity of inducible NO synthase (iNOS) and subsequent production of the cytotoxic free radical nitric oxide (NO) in endothelial cells. We here investigated the effect of bioactive MMF compound mycophenolic acid (MPA) on iNOS-mediated NO synthesis in fibroblasts, which are important source of NO in rheumatoid arthritis and during rejection of solid organ transplants. MPA exerted dose-dependent inhibition of NO synthesis, measured as nitrite accumulation, in IFN-γ+ LPS-stimulated L929 mouse fibroblast cell line and rat primary fibroblasts. The effect of MPA was not mediated through interference with IMPDH-dependent synthesis of iNOS co-factor BH4 and subsequent suppression of iNOS enzymatic activity, as direct BH4 precursor sepiapterin failed to block the action of the drug. MPA suppressed the IFN-γ+ LPS-induced expression of fibroblast iNOS protein, as well as mRNA for iNOS and its transcription factor IRF-1, as assessed by cell-based ELISA and semiquantitative RT-PCR, respectively. MPA suppression of fibroblast NO release, iNOS, and IRF-1 activation, was efficiently prevented by exogenous guanosine, indicating that the drug acted through reduction of IMPDH-dependent synthesis of guanosine nucleotides. These results suggest that MPA inhibits NO production in fibroblasts by blocking guanosine nucleotide-dependent expression of iNOS gene, through mechanisms that might involve the interference with the induction of iNOS transcription factor IRF-1.

Mycophenolate mofetil (MMF) is an immunosuppressive drug that acts as a selective inhibitor of inosine monophosphate dehydrogenase (IMPDH). MMF has recently been shown to inhibit the enzymatic activity of inducible NO synthase (iNOS) and subsequent production of the cytotoxic free radical nitric oxide (NO) in endothelial cells. We here investigated the effect of bioactive MMF compound mycophenolic acid (MPA) on iNOS-mediated NO synthesis in fibroblasts, which are important source of NO in rheumatoid arthritis and during rejection of solid organ transplants. MPA exerted dose-dependent inhibition of NO synthesis, measured as nitrite accumulation, in IFN-γ+ LPS-stimulated L929 mouse fibroblast cell line and rat primary fibroblasts. The effect of MPA was not mediated through interference with IMPDH-dependent synthesis of iNOS co-factor BH4 and subsequent suppression of iNOS enzymatic activity, as direct BH4 precursor sepiapterin failed to block the action of the drug. MPA suppressed the IFN-γ+ LPS-induced expression of fibroblast iNOS protein, as well as mRNA for iNOS and its transcription factor IRF-1, as assessed by cell-based ELISA and semiquantitative RT-PCR, respectively. MPA suppression of fibroblast NO release, iNOS, and IRF-1 activation, was efficiently prevented by exogenous guanosine, indicating that the drug acted through reduction of IMPDH-dependent synthesis of guanosine nucleotides. These results suggest that MPA inhibits NO production in fibroblasts by blocking guanosine nucleotide-dependent expression of iNOS gene, through mechanisms that might involve the interference with the induction of iNOS transcription factor IRF-1.

Interleukin-6 (IL-6) and nitric oxide (NO) are implicated in the pathology of multiple sclerosis (MS). We have investigated the levels of these mediators in the cerebrospinal fluid (CSF) from 50 patients with MS and 23 control subjects. Mean CSF IL-6 level was higher in the total MS group in comparison with controls, but not significantly, whilst the difference between patients with stable MS and controls reached the level of statistical significance. Mean CSF nitrite/nitrate level was significantly higher in the total MS group compared with the control group, as well as in active MS patients versus controls. There was significant difference neither in the mean CSF IL-6 nor in nitrite/nitrate levels between active and stable MS patients. Interestingly, we observed a significant negative correlation between IL-6 and nitrite/nitrate levels in the CSF in the total MS group. Such a trend existed in both subgroups with active and stable MS, but without reaching the level of statistical significance. Our data further support the involvement of IL-6 and NO in ongoing pathological processes in MS, suggesting their potential interplay within the central nervous system in this disease.

Interleukin-6 (IL-6) and nitric oxide (NO) are implicated in the pathology of multiple sclerosis (MS). We have investigated the levels of these mediators in the cerebrospinal fluid (CSF) from 50 patients with MS and 23 control subjects. Mean CSF IL-6 level was higher in the total MS group in comparison with controls, but not significantly, whilst the difference between patients with stable MS and controls reached the level of statistical significance. Mean CSF nitrite/nitrate level was significantly higher in the total MS group compared with the control group, as well as in active MS patients versus controls. There was significant difference neither in the mean CSF IL-6 nor in nitrite/nitrate levels between active and stable MS patients. Interestingly, we observed a significant negative correlation between IL-6 and nitrite/nitrate levels in the CSF in the total MS group. Such a trend existed in both subgroups with active and stable MS, but without reaching the level of statistical significance. Our data further support the involvement of IL-6 and NO in ongoing pathological processes in MS, suggesting their potential interplay within the central nervous system in this disease.