S Scharpé

University of Antwerp, Antwerpen, Flanders, Belgium

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Publications (196)773.39 Total impact

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    ABSTRACT: The association between the pro-inflammatory state of schizophrenia and increased tryptophan degradation into kynurenine has been reported. However, the relationship between metabolites from subdivisions of the kynurenine pathway, kynurenic acid and 3-hydroxykynurenine, remains unknown. The present study tested the relationship between these kynurenine metabolites in the plasma of medication-naïve (n=35) or medication-free (n=18) patients with schizophrenia at admission and following 6-week antipsychotic treatment compared to healthy controls (n=48). The plasma concentrations of kynurenic acid (nmol/l) were lower (difference=-8.44 (-13.22 to -3.65); p=0.001) and of 3-hydroxykynurenine (nmol/l) were higher (difference=11.24 (8.11-14.37); p<0.001) in the patients compared with the healthy controls. The kynurenic acid/kynurenine (difference=-2.75 (-5.115 to -0.336); p=0.026) and kynurenic acid/3-hydroxykynurenine (difference=-1.08 (-1.431 to -0.729); p<0.001) ratios were also lower in the patients. After the 6-week treatment, the patients' plasma kynurenic acid levels (difference=3.85 (-0.23 to 7.94); p=0.064) showed a trend towards an increase, whereas plasma 3-hydroxykynurenine levels (difference=22.41 (19.76-25.07); p<0.001) decreased. As a consequence, the kynurenic acid/3-hydroxykynurenine ratio (difference=-4.41 (-5.51 to -3.3); p<0.001) increased. Higher initial plasma kynurenic acid levels on admission or increased kynurenic acid/kynurenine ratio after treatment were associated with reduction of clinical symptoms scores upon discharge although higher kynurenic acid/kynurenine on admission may induce higher positive symptoms score. In contrast, higher 3-hydroxykynurenine is associated with lower positive symptoms score. These results indicate that there is an imbalance in the kynurenine pathway in schizophrenia. The 6-week antipsychotic treatment may partially reverse the imbalance in kynurenine metabolism and that in turn induces clinical response.
    Brain Behavior and Immunity 05/2011; 25(8):1576-81. · 5.61 Impact Factor
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 01/2010; 26(41).
  • Journal of Heart and Lung Transplantation. 01/2009; 28(2):S218-S218.
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    ABSTRACT: Abnormal activity in peripheral blood of the cytosolic enzyme prolyl endopeptidase (PEP, EC 3.4.21.26, post prolyl cleaving enzyme, prolyl oligopeptidase) has been found in patients with a variety of psychiatric disorders, most consistently in mood disorders. Mood disturbance is a well-known side effect of immunotherapy with interferon-alpha (IFN-alpha). Earlier, we documented a decrease in serum PEP activity in the first 4 weeks of treatment with IFN-alpha. In 24 patients (16 men, 8 women, median age 60.5 years, range 47-72 years) with metastatic renal cell carcinoma (RCC), psychiatric assessment and blood sampling were performed before and at 4 and 8 weeks and at 6 months after initiation of treatment with IFN-alpha. No episodes of depression were observed, and the sum score and the scores on the subscales for depression and hostility of the Symptom Check List-90 (SCL-90) did not change during follow-up, whereas the anxiety scores were somewhat lower at 4 and 8 weeks compared with baseline. No change in plasma PEP activity and no relationships between change in psychiatric parameters and change in plasma PEP activity were found. As more subtle relationships between PEP activity and psychiatric status could have easily been obscured, a role for PEP in the pathophysiology of IFN-alpha-induced mood disturbance can neither be confirmed nor excluded.
    Journal of Interferon & Cytokine Research 06/2008; 28(5):283-6. · 3.30 Impact Factor
  • Journal of Heart and Lung Transplantation. 01/2008; 27(2):S216-S217.
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    ABSTRACT: CD26/Dipeptidyl peptidase (DPP) IV is an integral membrane protein of lymphocytes that modulates the activities of chemokines, interleukins, and neuropeptides. We investigated the effect of enzymatic DPP IV inhibition on ischemia/reperfusion injury after extended ischemia prior to transplantation. We used a syngeneic rat (Lewis) orthotopic left lung transplantation model. In the control group (group I), donor lungs were flushed and preserved in Perfadex for 18 hours at 4 degrees C, then transplanted and reperfused for 2 hours. Group II donor lungs were perfused with and stored in Perfadex +25mol/L AB192 (bis(4-acetamidophenyl) 1-(S)-prolylpyrrolidine-2(R,S)-phosphonate), a small molecular weight DPP IV inhibitor. After 2-hour reperfusion, we measured blood gas, peak airway pressure, and thiobarbituric acid reactive substances. Grafts from group II versus group I showed a significantly increased oxygenation capacity (II: 298.4 +/- 87.6 mm Hg vs 120.9 +/- 48.0, P < .01), lower peak airway pressure (11.8 +/- 0.9 mm Hg vs 16.0 +/- 1.4, P < .01), and less lipid peroxidation (9.3 +/- 2.0 micromol/L vs 13.8 +/- 1.8, P < .01). Inhibition of intragraft DPP IV enzymatic activity significantly reduced ischemia/reperfusion-associated pulmonary injury, allowing for successful transplantation after 18 hours of ischemia.
    Transplantation Proceedings 12/2006; 38(10):3369-71. · 0.95 Impact Factor
  • Journal of Peptide Science 01/2006; 12:168-168. · 2.07 Impact Factor
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    Journal of Cystic Fibrosis - J CYST FIBROS; 01/2006
  • FEBS Journal 01/2005; 272:171-171. · 4.25 Impact Factor
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    ABSTRACT: Studies show that administration of interferon (IFN)-α causes a significant increase in depressive symptoms. The enzyme indoleamine 2,3-dioxygenase (IDO), which converts tryptophan (TRP) into kynurenine (KYN) and which is stimulated by proinflammatory cytokines, may be implicated in the development of IFN-α-induced depressive symptoms, first by decreasing the TRP availability to the brain and second by the induction of the KYN pathway resulting in the production of neurotoxic metabolites. Sixteen patients with chronic hepatitis C, free of psychiatric disorders and eligible for IFN-α treatment, were recruited. Depressive symptoms were measured using the Montgomery Asberg Depression Rating Scale (MADRS). Measurements of TRP, amino acids competing with TRP for entrance through the blood–brain barrier, KYN and kynurenic acid (KA), a neuroprotective metabolite, were performed using high-performance liquid chromatography. All assessments were carried out at baseline and 1, 2, 4, 8, 12 and 24 weeks after treatment was initiated. The MADRS score significantly increased during IFN-α treatment as did the KYN/TRP ratio, reflecting IDO activity, and the KYN/KA ratio, reflecting the neurotoxic challenge. The TRP/CAA (competing amino acids) ratio, reflecting TRP availability to the brain, did not significantly change during treatment. Total MADRS score was significantly associated over time with the KYN/KA ratio, but not with the TRP/CAA ratio. Although no support was found that IDO decreases TRP availability to the brain, this study does support a role for IDO activity in the pathophysiology of IFN-α-induced depressive symptoms, through its induction of neurotoxic KYN metabolites.
    Molecular Psychiatry 01/2005; 10(6):538-544. · 15.15 Impact Factor
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    ABSTRACT: Immunotherapy with interferon-alpha (IFN-alpha) induces neuropsychiatric side effects, most notably depression. In hepatitis patients treated with IFN-alpha, severity of depression correlates with a decrease in serum activity of dipeptidyl peptidase IV (DPP-IV, EC 3.4.14.5), a membrane-bound protease involved in the cleavage of cytokines and neuroactive peptides. Abnormal serum activity of the cytosolic peptidase prolyl endopeptidase (PEP, EC 3.4.21.26, postprolyl cleaving enzyme, prolyl oligopeptidase) has been documented in patients with a variety of psychiatric disorders, most consistently in mood disorders. The serum activity of PEP and DPP-IV was measured before and after 4 weeks of high-dose induction treatment with IFN-alpha in 18 patients with high-risk melanoma. In this exploratory study, we show a clear decrease in the serum activity of PEP after 4 weeks of treatment with IFN-alpha. This decrease was not related to changes in hematologic parameters. In contrast, serum activity of DPP-IV did not change. Further studies focusing on a possible role of PEP in the pathophysiology of IFN-alpha-induced depression are warranted.
    Journal of Interferon & Cytokine Research 08/2004; 24(7):411-5. · 3.30 Impact Factor
  • American Journal of Transplantation. 01/2004; 4:195-195.
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    ABSTRACT: Research on the biological pathophysiology of autism has found some evidence that immune alterations may play a role in the pathophysiology of that illness. As a consequence we expected to find that autism is accompanied by abnormalities in the pattern obtained in serum protein electrophoresis and in the serum immunoglobulin (Ig) and IgG subclass profile. We examined whether subjects with autism showed changes in total serum protein (TSP) and the serum concentrations of albumin, alpha1 globulin, alpha2 globulin, beta globulin and gamma globulins, IgA, IgM and IgG and the IgG subclasses IgG 1, IgG2, IgG3 and IgG4, compared with normal controls. We found significantly increased concentrations of TSP in autistic subjects, which were attributable to increased serum concentrations of albumin and gamma globulin. Serum IgG, IgG2 and IgG4 were also significantly raised. In autism there were significant and positive correlations between social problems and TSP and serum gamma globulin and between withdrawal symptoms and TSP and serum albumin and IgG. The results suggest that autism is characterized by increased TSP, a unique pattern obtained in serum protein electrophoresis, i.e. increased serum albumin and IgG, and by a specific IgG subclass profile, i.e. increased serum IgG2 and IgG4. The increased serum concentrations of IgGs in autism may point towards an underlying autoimmune disorder and/or an enhanced susceptibility to infections resulting in chronic viral infections, whereas the IgG subclass skewing may reflect different cytokine-dependent influences on autoimmune B cells and their products.
    Psychological Medicine 12/2002; 32(8):1457-63. · 5.59 Impact Factor
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    ABSTRACT: Background: It has been established that thyrotropin-releasing hormone (TRH) affects several aspects of immunoreactivity, e.g. production of proinflammatory cytokines. It has been shown that TRH enhances the therapeutic efficiency of classical tricyclic antidepressants. Proinflammatory cytokines may play a role in the etiology of depression, whereas the therapeutic efficacy of antidepressants may be related to their negative immunoregulatory effects.Objective: In order to verify the hypothesis that TRH-induced increase of therapeutic efficiency of classical tricyclic antidepressants results from synergistic inhibitory effects of these agents on the secretion of proinflammatory cytokines, we determine the effect of imipramine or fluoxetine with and without TRH on the production of interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) and interleukin-10 (IL-10) by stimulated human whole blood cells.Methods: Diluted whole blood of 17 volunteers was incubated with imipramine or fluoxetine (both in doses of 10−5 M) with or without TRH (in a dose of 10−5 M). The supernatants were collected 24 h later for the assay of TNF-α and after 72 h for the assays of IFN-γ and IL-10. The three cytokines were assayed by ELISA methods.Results: A significant decrease in production of IFN-γ was observed in cells stimulated with mitogens and co-incubated with imipramine or fluoxetine and TRH. Under the same conditions, TRH alone did not change the production of these cytokines, whereas imipramine alone significantly decreases IFN-γ production, and fluoxetine alone significantly decreases IFN-γ and TNF-α production.Conclusion: Although a significant decrease in IFN-γ production was observed after joint application of TRH and antidepressants, our data did not support the above-mentioned hypothesis. Indeed, we did not observe synergistic inhibitory effects of these agents on the secretion of proinflammatory cytokines.
    Acta Neuropsychiatrica 09/2002; 14(5):226 - 230. · 0.61 Impact Factor
  • Transplantation Proceedings 09/2002; 34(5):1753-4. · 0.95 Impact Factor
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    ABSTRACT: To test the hypothesis that the direct thrombin inhibitor, melagatran is able to inhibit local pro-carboxypeptidase U (proCPU) activation that occurs during thrombolytic treatment, t-PA alone, or in combination with melagatran, was given to dogs with a coronary artery thrombosis. Blood samples from the great cardiac vein and aorta were collected at baseline, during thrombus formation, throughout the t-PA+/-melagatran infusion and during the patency period, for analysis of CPU activity using a novel assay. A higher CPU activity in venous compared to arterial blood (V-A difference) indicates CPU activation in coronary vessels. Efficacy was assessed by determination of time to lysis, duration of patency and blood flow during patency. Dogs (n = 26) were randomized to receive either 1) t-PA, 1 mg/kg as an intravenous 20-min infusion; 2) t-PA as in group 1, +melagatran bolus, 0.3 mg/kg, followed by a 3-h infusion (0.15 mg/kg per h); 3) sham-operated but no coronary thrombus, and administered t-PA as for Group 1. All groups had similar baseline characteristics. Significant increases in CPU activity were observed in Groups 1 and 2 during thrombus formation, with V-A differences of 5.5 and 4.5 U/L, respectively. No significant V-A difference was observed in the sham-operated group. CPU activity increased in Group 1 during the t-PA infusion (V-A difference 15.9 U/L), whereas the V-A difference in Group 2 decreased to 2.6 U/L following melagatran treatment. These results demonstrate that melagatran attenuates generation of CPU in the coronary circulation. The mechanism is probably indirect, via inhibition of thrombin-mediated activation of proCPU.
    Thrombosis and Haemostasis 05/2002; 87(4):557-62. · 5.76 Impact Factor
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    ABSTRACT: The mixed 5-HT receptor agonist/antagonist meta-chlorophenylpiperazine (mCPP) is known to suppress locomotor activity in mice and rats. This study aimed: (1) to determine whether mCPP induces cognitive and motor changes in normal human volunteers and how these changes relate to the neuroendocrine effects of mCPP; and (2) to compare these cognitive and motor changes to the known cognitive and motor slowing patterns in depression and schizophrenia. A computerized method (used in previous research) analyzed fine motor behavior during figure-copying tasks. In 14 normal male volunteers behavioral responses, body temperature, plasma levels of prolactin and cortisol, and cognitive and motor performance during figure-copying tasks were measured after a single oral dose of mCPP (0.5 mg/kg). mCPP-induced prolongation of the reaction times in all copying tasks, parallel to increases in cortisol and prolactin and some self-reported behavioral effects. There were no changes in the movement times or the velocities of the writing movements. In conclusion, mCPP induced cognitive, but not motor slowing, in normal male volunteers. This indicates that the human serotonin system is also implicated in psychomotor behavior. This pattern of slowing was different from that in depressed and schizophrenic patients.
    Psychiatry Research 01/2002; 105(3):151-63. · 2.68 Impact Factor
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    ABSTRACT: Background. Research on the biological pathophysiology of autism has found some evidence that immune alterations may play a role in the pathophysiology of that illness. As a consequence we expected to find that autism is accompanied by abnormalities in the pattern obtained in serum protein electrophoresis and in the serum immunoglobulin (Ig) and IgG subclass profile.
    Psychological Medicine 01/2002; 32(08). · 5.59 Impact Factor
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    ABSTRACT: Dipeptidyl-peptidase IV (DPPIV/CD26) metabolizes neuropeptides regulating insulin secretion. We studied the in vitro steady-state kinetics of DPPIV/CD26-mediated truncation of vasoactive intestinal peptide (VIP), pituitary adenylyl cyclase-activating peptide (PACAP27 and PACAP38), gastrin-releasing peptide (GRP) and neuropeptide Y (NPY). DPPIV/CD26 sequentially cleaves off two dipeptides of VIP, PACAP27, PACAP38 and GRP. GRP situates between the best DPPIV/CD26 substrates reported, comparable to NPY. Surprisingly, the C-terminal extension of PACAP38, distant from the scissile bond, improves both PACAP38 binding and turnover. Therefore, residues remote from the scissile bond can modulate DPPIV/CD26 substrate selectivity as well as residues flanking it.
    FEBS Letters 12/2001; 507(3):327-30. · 3.58 Impact Factor
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    ABSTRACT: Chemokines coordinate many aspects of leukocyte migration. As chemoattractants they play an important role in the innate and acquired immune response. There is good experimental evidence that N-terminal truncation by secreted or cell surface proteases is a way of modulating chemokine action. The localization of CD26/dipeptidyl peptidase IV on cell surfaces and in biological fluids, its primary specificity, and the type of naturally occurring truncated chemokines are consistent with such a function. We determined the steady-state catalytic parameters for a relevant selection of chemokines (CCL3b, CCL5, CCL11, CCL22, CXCL9, CXCL10, CXCL11, and CXCL12) previously reported to alter their chemotactic behavior due to CD26/dipeptidyl peptidase IV-catalyzed truncation. The results reveal a striking selectivity for stromal cell-derived factor-1alpha (CXCL12) and macrophage-derived chemokine (CCL22). The kinetic parameters support the hypothesis that CD26/dipeptidyl peptidase IV contributes to the degradation of certain chemokines in vivo. The data not only provide insight into the selectivity of the enzyme for specific chemokines, but they also contribute to the general understanding of CD26/dipeptidyl peptidase IV secondary substrate specificity.
    Journal of Biological Chemistry 09/2001; 276(32):29839-45. · 4.65 Impact Factor

Publication Stats

6k Citations
773.39 Total Impact Points

Institutions

  • 1986–2011
    • University of Antwerp
      • • Department of Pharmaceutical sciences
      • • Faculteit Geneeskunde en Gezondheidswetenschappen
      Antwerpen, Flanders, Belgium
  • 2006
    • University of Zurich
      • Internal Medicine Unit
      Zürich, Zurich, Switzerland
  • 2001–2005
    • Maastricht University
      • Psychiatrie en Neuropsychologie
      Maastricht, Provincie Limburg, Netherlands
  • 2004
    • Erasmus MC
      • Department of Psychiatry
      Rotterdam, South Holland, Netherlands
  • 2001–2002
    • AstraZeneca
      Tukholma, Stockholm, Sweden
  • 2000
    • Polish Academy of Sciences
      • Institute of Pharmacology
      Warsaw, Masovian Voivodeship, Poland
  • 1998–1999
    • KU Leuven
      • Rega Institute for Medical Research
      Leuven, VLG, Belgium
    • Vanderbilt University
      Nashville, Michigan, United States
  • 1997–1999
    • Brigham and Women's Hospital
      • Department of Medicine
      Boston, MA, United States
  • 1991
    • Weizmann Institute of Science
      Israel
  • 1973
    • Ghent University
      Gand, Flanders, Belgium