Piet Stinissen | Universiteit Hasselt (original) (raw)

Papers by Piet Stinissen

Research paper thumbnail of Treg-Resistant Cytotoxic CD4+ T Cells Dictate T Helper Cells in Their Vicinity: TH17 Skewing and Modulation of Proliferation

International Journal of Molecular Sciences

Cytotoxic CD4+ T cells (CD4 CTL) are terminally differentiated T helper cells that contribute to ... more Cytotoxic CD4+ T cells (CD4 CTL) are terminally differentiated T helper cells that contribute to autoimmune diseases, such as multiple sclerosis. We developed a novel triple co-culture transwell assay to study mutual interactions between CD4 CTL, conventional TH cells, and regulatory T cells (Tregs) simultaneously. We show that, while CD4 CTL are resistant to suppression by Tregs in vitro, the conditioned medium of CD4 CTL accentuates the suppressive phenotype of Tregs by upregulating IL-10, Granzyme B, CTLA-4, and PD-1. We demonstrate that CD4 CTL conditioned medium skews memory TH cells to a TH17 phenotype, suggesting that the CD4 CTL induce bystander polarization. In our triple co-culture assay, the CD4 CTL secretome promotes the proliferation of TH cells, even in the presence of Tregs. However, when cell−cell contact is established between CD4 CTL and TH cells, the proliferation of TH cells is no longer increased and Treg-mediated suppression is restored. Taken together, our res...

Research paper thumbnail of Altered PPARγ Expression Promotes Myelin-Induced Foam Cell Formation in Macrophages in Multiple Sclerosis

International Journal of Molecular Sciences

Macrophages play a crucial role during the pathogenesis of multiple sclerosis (MS), a neuroinflam... more Macrophages play a crucial role during the pathogenesis of multiple sclerosis (MS), a neuroinflammatory autoimmune disorder of the central nervous system. Important regulators of the metabolic and inflammatory phenotype of macrophages are liver X receptors (LXRs) and peroxisome proliferator-activated receptors (PPARs). Previously, it has been reported that PPARγ expression is decreased in peripheral blood mononuclear cells of MS patients. The goal of the present study was to determine to what extent PPARγ, as well as the closely related nuclear receptors PPARα and β and LXRα and β, are differentially expressed in monocytes from MS patients and how this change in expression affects the function of monocyte-derived macrophages. We demonstrate that monocytes of relapsing-remitting MS patients display a marked decrease in PPARγ expression, while the expression of PPARα and LXRα/β is not altered. Interestingly, exposure of monocyte-derived macrophages from healthy donors to MS-associated...

Research paper thumbnail of Crosstalk with Inflammatory Macrophages Shapes the Regulatory Properties of Multipotent Adult Progenitor Cells

Stem Cells International

Macrophages and microglia are key effector cells in immune-mediated neuroinflammatory disorders. ... more Macrophages and microglia are key effector cells in immune-mediated neuroinflammatory disorders. Driving myeloid cells towards an anti-inflammatory, tissue repair-promoting phenotype is considered a promising strategy to halt neuroinflammation and promote central nervous system (CNS) repair. In this study, we defined the impact of multipotent adult progenitor cells (MAPC), a stem cell population sharing common mesodermal origin with mesenchymal stem cells (MSCs), on the phenotype of macrophages and the reciprocal interactions between these two cell types. We show that MAPC suppress the secretion of tumor necrosis factor alpha (TNF-α) by inflammatory macrophages partially through a cyclooxygenase 2- (COX-2-) dependent mechanism. In turn, we demonstrate that inflammatory macrophages trigger the immunomodulatory properties of MAPC, including an increased expression of immunomodulatory mediators (e.g., inducible nitric oxide synthase (iNOS) and COX-2), chemokines, and chemokine receptor...

Research paper thumbnail of Age-Associated B Cells with Proinflammatory Characteristics Are Expanded in a Proportion of Multiple Sclerosis Patients

The Journal of Immunology

Research paper thumbnail of Cytomegalovirus infection exacerbates autoimmune mediated neuroinflammation

Scientific Reports

Cytomegalovirus (CMV) is a latent virus which causes chronic activation of the immune system. Her... more Cytomegalovirus (CMV) is a latent virus which causes chronic activation of the immune system. Here, we demonstrate that cytotoxic and pro-inflammatory CD4 + CD28 null T cells are only present in CMV seropositive donors and that CMV-specific Immunoglobulin (Ig) G titers correlate with the percentage of these cells. In vitro stimulation of peripheral blood mononuclear cells with CMVpp65 peptide resulted in the expansion of pre-existing CD4 + CD28 null T cells. In vivo, we observed de novo formation, as well as expansion of CD4 + CD28 null T cells in two different chronic inflammation models, namely the murine CMV (MCMV) model and the experimental autoimmune encephalomyelitis (EAE) model for multiple sclerosis (MS). In EAE, the percentage of peripheral CD4 + CD28 null T cells correlated with disease severity. Pre-exposure to MCMV further aggravated EAE symptoms, which was paralleled by peripheral expansion of CD4 + CD28 null T cells, increased splenocyte MOG reactivity and higher levels of spinal cord demyelination. Cytotoxic CD4 + T cells were identified in demyelinated spinal cord regions, suggesting that peripherally expanded CD4 + CD28 null T cells migrate towards the central nervous system to inflict damage. Taken together, we demonstrate that CMV drives the expansion of CD4 + CD28 null T cells, thereby boosting the activation of disease-specific CD4 + T cells and aggravating autoimmune mediated inflammation and demyelination.

Research paper thumbnail of Cytotoxic CD4+ T Cells Drive Multiple Sclerosis Progression

Frontiers in Immunology

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) chara... more Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterized by inflammation, demyelination, and axonal loss (1). The leading hypothesis states that peripheral autoreactive T cells are activated after encountering self-antigens, after which they migrate across the blood-brain barrier into the CNS (2). Here, these T cells are reactivated , leading

Research paper thumbnail of Relapsing-remitting multiple sclerosis patients display an altered lipoprotein profile with dysfunctional HDL

Scientific reports, Jan 23, 2017

Lipoproteins modulate innate and adaptive immune responses. In the chronic inflammatory disease m... more Lipoproteins modulate innate and adaptive immune responses. In the chronic inflammatory disease multiple sclerosis (MS), reports on lipoprotein level alterations are inconsistent and it is unclear whether lipoprotein function is affected. Using nuclear magnetic resonance (NMR) spectroscopy, we analysed the lipoprotein profile of relapsing-remitting (RR) MS patients, progressive MS patients and healthy controls (HC). We observed smaller LDL in RRMS patients compared to healthy controls and to progressive MS patients. Furthermore, low-BMI (BMI ≤ 23 kg/m(2)) RRMS patients show increased levels of small HDL (sHDL), accompanied by larger, triglyceride (TG)-rich VLDL, and a higher lipoprotein insulin resistance (LP-IR) index. These alterations coincide with a reduced serum capacity to accept cholesterol via ATP-binding cassette (ABC) transporter G1, an impaired ability of HDL3 to suppress inflammatory activity of human monocytes, and modifications of HDL3's main protein component ApoA...

Research paper thumbnail of Label-Free Imaging of Umbilical Cord Tissue Morphology and Explant-Derived Cells

Stem Cells International, 2016

In situ detection of MSCs remains difficult and warrants additional methods to aid with their cha... more In situ detection of MSCs remains difficult and warrants additional methods to aid with their characterization in vivo. Two-photon confocal laser scanning microscopy (TPM) and second harmonic generation (SHG) could fill this gap. Both techniques enable the detection of cells and extracellular structures, based on intrinsic properties of the specific tissue and intracellular molecules under optical irradiation. TPM imaging and SHG imaging have been used for label-free monitoring of stem cells differentiation, assessment of their behavior in biocompatible scaffolds, and even cell tracking in vivo. In this study, we show that TPM and SHG can accurately depict the umbilical cord architecture and visualize individual cells both in situ and during culture initiation, without the use of exogenously applied labels. In combination with nuclear DNA staining, we observed a variance in fluorescent intensity in the vessel walls. In addition, antibody staining showed differences in Oct4, αSMA, vi...

Research paper thumbnail of The isotype repertoire of antibodies against novel UH-RA peptides in rheumatoid arthritis

Arthritis Research & Therapy, 2016

Background: Recently, autoantibodies against novel UH-RA peptides (UH-RA.1 and UH-RA.21) were ide... more Background: Recently, autoantibodies against novel UH-RA peptides (UH-RA.1 and UH-RA.21) were identified as candidate biomarkers for patients with rheumatoid arthritis (RA) who are seronegative for the current diagnostic markers rheumatoid factor and anticitrullinated protein antibodies. Previously, screening for anti-UH-RA autoantibodies was based on measuring the immunoglobulin (Ig) G response. We aimed to investigate whether measurement of other isotypes could improve the performance of diagnostic testing. In addition, assigning the isotype profile might provide valuable information on effector functions of the antibodies. Methods: The isotype profile of antibodies against UH-RA.1 and UH-RA.21 was studied. The IgG, IgM, and IgA classes, together with the 4 different IgG subclasses, were determined in 285 patients with RA, 88 rheumatic control subjects, and 90 healthy control subjects. Results: Anti-UH-RA.1 antibodies were primarily of the IgM isotype and twice as prevalent as IgG (IgG3-dominated) and IgA. RA sensitivity when testing for anti-UH-RA.1 IgM was shown to be higher than when testing for the IgG isotype: 18 % versus 9 % sensitivity when RA specificity was set to 90 %. Within antibodies against UH-RA.21, IgG and IgA were more common than IgM. Different anti-UH-RA.21 IgG subclasses were found, with the highest prevalence found for IgG2. Combined testing for IgG and IgA slightly increased RA sensitivity of UH-RA.21-specific antibody testing to 27 % compared with solely testing for IgG (23 %). Notably, a higher number of anti-UH-RA.21 antibody isotypes was related to increased levels of erythrocyte sedimentation rate. Finally, for both antibody responses, the full antibody isotype use was demonstrated in early and seronegative disease. Conclusions: The isotype distribution of anti-UH-RA.1 and anti-UH-RA.21 antibodies was successfully outlined, and, for antibodies against UH-RA.1, we found that isotype-specific testing might have implications for diagnostic testing. The exact mechanisms by which the different antibody isotypes act still have to be unraveled.

Research paper thumbnail of Analysis of antibody reactivity in paired cerebrospinal fluid and serum of a relapsing remitting multiple sclerosis patient

Autoimmunity, Nov 3, 2009

Increasing evidence indicates an involvement of B cells in multiple sclerosis (MS). However, litt... more Increasing evidence indicates an involvement of B cells in multiple sclerosis (MS). However, little is known about antigenic targets recognized by antibodies present in blood and cerebrospinal fluid (CSF) of MS patients. This study was therefore aimed at identifying the antigen reactivity of antibodies present in CSF and compares the identified antibody profile with that of the serum of the same patient using cDNA phage display. Selection rounds on paired CSF and serum of this patient identified 13 antigenic targets of which 5 were enriched by serum antibodies and 2 were identified by CSF antibodies. Interestingly, the six remaining antigenic targets were shown to be recognized by both CSF and serum antibodies. These findings point towards both common as well as distinct antibody profiles in CSF and serum of MS patients.

Research paper thumbnail of In Vivo Clonotypic Regulation in Human Myelin Basic Protein-Reactive T Cells by T Cell Vaccination

The Journal of Immunology, 1995

Research paper thumbnail of Discovery of Novel Antigenic Targets and Autoantibody Markers in Rheumatoid Arthritis

Research paper thumbnail of Involvement of T-cell receptor-� alterations in the development of otosclerosis linked to OTSC2

Genes Immun, 2010

Otosclerosis is a common form of hearing loss, characterized by disordered bone remodeling in the... more Otosclerosis is a common form of hearing loss, characterized by disordered bone remodeling in the otic capsule. Within the otosclerotic foci, several immunocompetent cells and immune-modulating factors can be found. Different etiological theories involving the immune system have been suggested. However, a genetic component is clearly present. In large otosclerosis families, seven autosomal-dominant loci have been found, but none of the disease-causing genes has been identified. This study focused on the exploration of the second otosclerosis locus on chromosome 7q34-36 (OTSC2), holding the T-cell receptor beta locus (TRB locus). A significantly lower T-cell receptor-β (TCR-β) mRNA expression and percentage of blood circulating TCR-αβ+ T cells was detected in OTSC2 patients compared with controls and patients with the complex form of the disease. Further analysis illustrated more significant disturbances in specific T-cell subsets, including an increased CD28null cell population, suggesting a disturbed T-cell development and ageing in OTSC2 patients. These disturbances could be associated with otosclerotic bone remodeling, given the known effects of immunocompetent cells on bone physiology. These data implicate the TRB locus as the causative gene in the OTSC2 region and represent an important finding in the elucidation of the disease pathology.

Research paper thumbnail of Autoantibodies to two novel peptides in seronegative and early rheumatoid arthritis

Rheumatology, 2016

Objectives. Despite recent progress in biomarker discovery for RA diagnostics, still over one-thi... more Objectives. Despite recent progress in biomarker discovery for RA diagnostics, still over one-third of RA patients-and even more in early disease-present without RF or ACPA. The aim of this study was to confirm the presence of previously identified autoantibodies to novel Hasselt University (UH) peptides in early and seronegative RA. Methods. Screening for antibodies against novel UH peptides UH-RA.1, UH-RA.9, UH-RA.14 and UH-RA.21, was performed in two large independent cohorts. Peptide ELISAs were developed to screen for the presence of antibodies to UH-RA peptides. First, 292 RA patients (including 39 early patients), 90 rheumatic and 97 healthy controls from UH were studied. Antibody reactivity to two peptides (UH-RA.1 and UH-RA.21) was also evaluated in 600 RA patients, 309 patients with undifferentiated arthritis and 157 rheumatic controls from the Leiden Early Arthritis Clinic cohort. Results. In both cohorts, 38% of RA patients were seronegative for RF and ACPA. Testing for autoantibodies to UH-RA.1 and UH-RA.21 reduced the serological gap from 38% to 29% in the UH cohort (P = 0.03) and from 38% to 32% in the Leiden Early Arthritis Clinic cohort (P = 0.01). Furthermore, 1933% of early RA patients carried antibodies to these peptides. Specificities in rheumatic controls ranged from 82 to 96%. Whereas antibodies against UH-RA.1 were related to remission, anti-UH-RA.21 antibodies were associated with inflammation, joint erosion and higher tender and swollen joint counts. Conclusion. This study validates the presence of antibody reactivity to novel UH-RA peptides in seronegative and early RA. This might reinforce current diagnostics and improve early diagnosis and intervention in RA.

Research paper thumbnail of Current trends in multiple sclerosis research: an update on pathogenic concepts

Acta Neurologica Belgica, 2007

Financial support: 'Nationaal fonds voor wetenschappelijk onderzoek Vlaanderen (FWO)'

Research paper thumbnail of Citrullination-Specific Phage Display

Research paper thumbnail of Osteoprotegerin and receptor activator of nuclear factor-kappaB ligand mRNA expression in patients with rheumatoid arthritis and healthy controls

The Journal of Rheumatology, Aug 1, 2004

To further understand the role of osteoprotegerin (OPG) and receptor activator of nuclear factor-... more To further understand the role of osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANK-L) in rheumatoid arthritis (RA), we studied the levels of RANK-L and OPG mRNA in peripheral blood mononuclear cells (PBMC) and synovial tissue of patients with RA and controls. Methods. RANK-L and OPG mRNA levels were measured in PBMC and CD4+/CD8+ T cell subsets of patients with chronic RA, osteoarthritis (OA), and healthy controls, using quantitative real-time polymerase chain reaction. OPG and RANK-L mRNA levels were measured in paired blood and synovial tissue samples of patients with early, untreated RA at 2 timepoints with an interval of 16 weeks. Results. RANK-L mRNA levels were significantly higher in PBMC of patients with early and chronic RA compared to healthy controls. Contrary to healthy controls, RANK-L mRNA levels in patients with chronic RA were mainly of CD4+ T cell origin. OPG mRNA was observed in the blood of all (17/17) early RA patients, but could not be detected in chronic RA patients (0/14) or in patients with OA (0/8). Three out of 17 healthy controls showed measurable levels of OPG mRNA. The OPG/RANK-L ratio tended to be higher in the synovium than in the PBMC of early RA patients. RANK-L mRNA in synovial tissue was mainly of non-T cell origin. Conclusion. Since RANK-L and OPG mRNA levels are elevated in PBMC of RA patients, and CD4+ T cells are the major contributors to RANK-L mRNA expression, mononuclear cells in patients with RA may be involved in the pathways that regulate bone metabolism.

Research paper thumbnail of Biomarkers for Rheumatoid Arthritis

Research paper thumbnail of F.113. Local LIF Production in the CNS Limits Autoimmune Demyelination

Clin Immunol, 2009

Furthermore, infusion of Tregs, particularly those expressing CD62L, can prevent or ameliorate GV... more Furthermore, infusion of Tregs, particularly those expressing CD62L, can prevent or ameliorate GVHD in mice. Therefore, we sought to determine if GVHD in humans is also associated with a dearth of Tregs. We identified 63 HSCT recipients with or without GVHD at the point of diagnosis, prior to any alteration of their immunosuppressive regimen, and obtained both peripheral blood for flow cytometric analysis and GI biopsy material for immunohistochemical analysis. However, we found the percent of T cells that were FOXP3+ to be no lower in the blood or GI mucosa with GI GVHD, and actually found more FOXP3+ cells to be present in the blood when GVHD was histologically evident in both the upper and lower GI tract. Furthermore, the fraction of FOXP3+ T cells that were CD62L+ in the blood was actually higher in patients with histological evidence of GI GVHD than in those without, contrary to murine data. Among patients with GVHD, Treg frequency did not correlate with GVHD severity. In conclusion, we found no evidence that GI GVHD is caused by a lack of Tregs, and suggest that proposed clinical trials of Treg infusions for GVHD may prove less beneficial for humans than they have for mice.

Research paper thumbnail of Increased frequency of γδ T cells in cerebrospinal fluid and peripheral blood of patients with multiple sclerosis: Reactivity, cytotoxicity, and T cell receptor V gene rearrangements

Research paper thumbnail of Treg-Resistant Cytotoxic CD4+ T Cells Dictate T Helper Cells in Their Vicinity: TH17 Skewing and Modulation of Proliferation

International Journal of Molecular Sciences

Cytotoxic CD4+ T cells (CD4 CTL) are terminally differentiated T helper cells that contribute to ... more Cytotoxic CD4+ T cells (CD4 CTL) are terminally differentiated T helper cells that contribute to autoimmune diseases, such as multiple sclerosis. We developed a novel triple co-culture transwell assay to study mutual interactions between CD4 CTL, conventional TH cells, and regulatory T cells (Tregs) simultaneously. We show that, while CD4 CTL are resistant to suppression by Tregs in vitro, the conditioned medium of CD4 CTL accentuates the suppressive phenotype of Tregs by upregulating IL-10, Granzyme B, CTLA-4, and PD-1. We demonstrate that CD4 CTL conditioned medium skews memory TH cells to a TH17 phenotype, suggesting that the CD4 CTL induce bystander polarization. In our triple co-culture assay, the CD4 CTL secretome promotes the proliferation of TH cells, even in the presence of Tregs. However, when cell−cell contact is established between CD4 CTL and TH cells, the proliferation of TH cells is no longer increased and Treg-mediated suppression is restored. Taken together, our res...

Research paper thumbnail of Altered PPARγ Expression Promotes Myelin-Induced Foam Cell Formation in Macrophages in Multiple Sclerosis

International Journal of Molecular Sciences

Macrophages play a crucial role during the pathogenesis of multiple sclerosis (MS), a neuroinflam... more Macrophages play a crucial role during the pathogenesis of multiple sclerosis (MS), a neuroinflammatory autoimmune disorder of the central nervous system. Important regulators of the metabolic and inflammatory phenotype of macrophages are liver X receptors (LXRs) and peroxisome proliferator-activated receptors (PPARs). Previously, it has been reported that PPARγ expression is decreased in peripheral blood mononuclear cells of MS patients. The goal of the present study was to determine to what extent PPARγ, as well as the closely related nuclear receptors PPARα and β and LXRα and β, are differentially expressed in monocytes from MS patients and how this change in expression affects the function of monocyte-derived macrophages. We demonstrate that monocytes of relapsing-remitting MS patients display a marked decrease in PPARγ expression, while the expression of PPARα and LXRα/β is not altered. Interestingly, exposure of monocyte-derived macrophages from healthy donors to MS-associated...

Research paper thumbnail of Crosstalk with Inflammatory Macrophages Shapes the Regulatory Properties of Multipotent Adult Progenitor Cells

Stem Cells International

Macrophages and microglia are key effector cells in immune-mediated neuroinflammatory disorders. ... more Macrophages and microglia are key effector cells in immune-mediated neuroinflammatory disorders. Driving myeloid cells towards an anti-inflammatory, tissue repair-promoting phenotype is considered a promising strategy to halt neuroinflammation and promote central nervous system (CNS) repair. In this study, we defined the impact of multipotent adult progenitor cells (MAPC), a stem cell population sharing common mesodermal origin with mesenchymal stem cells (MSCs), on the phenotype of macrophages and the reciprocal interactions between these two cell types. We show that MAPC suppress the secretion of tumor necrosis factor alpha (TNF-α) by inflammatory macrophages partially through a cyclooxygenase 2- (COX-2-) dependent mechanism. In turn, we demonstrate that inflammatory macrophages trigger the immunomodulatory properties of MAPC, including an increased expression of immunomodulatory mediators (e.g., inducible nitric oxide synthase (iNOS) and COX-2), chemokines, and chemokine receptor...

Research paper thumbnail of Age-Associated B Cells with Proinflammatory Characteristics Are Expanded in a Proportion of Multiple Sclerosis Patients

The Journal of Immunology

Research paper thumbnail of Cytomegalovirus infection exacerbates autoimmune mediated neuroinflammation

Scientific Reports

Cytomegalovirus (CMV) is a latent virus which causes chronic activation of the immune system. Her... more Cytomegalovirus (CMV) is a latent virus which causes chronic activation of the immune system. Here, we demonstrate that cytotoxic and pro-inflammatory CD4 + CD28 null T cells are only present in CMV seropositive donors and that CMV-specific Immunoglobulin (Ig) G titers correlate with the percentage of these cells. In vitro stimulation of peripheral blood mononuclear cells with CMVpp65 peptide resulted in the expansion of pre-existing CD4 + CD28 null T cells. In vivo, we observed de novo formation, as well as expansion of CD4 + CD28 null T cells in two different chronic inflammation models, namely the murine CMV (MCMV) model and the experimental autoimmune encephalomyelitis (EAE) model for multiple sclerosis (MS). In EAE, the percentage of peripheral CD4 + CD28 null T cells correlated with disease severity. Pre-exposure to MCMV further aggravated EAE symptoms, which was paralleled by peripheral expansion of CD4 + CD28 null T cells, increased splenocyte MOG reactivity and higher levels of spinal cord demyelination. Cytotoxic CD4 + T cells were identified in demyelinated spinal cord regions, suggesting that peripherally expanded CD4 + CD28 null T cells migrate towards the central nervous system to inflict damage. Taken together, we demonstrate that CMV drives the expansion of CD4 + CD28 null T cells, thereby boosting the activation of disease-specific CD4 + T cells and aggravating autoimmune mediated inflammation and demyelination.

Research paper thumbnail of Cytotoxic CD4+ T Cells Drive Multiple Sclerosis Progression

Frontiers in Immunology

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) chara... more Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterized by inflammation, demyelination, and axonal loss (1). The leading hypothesis states that peripheral autoreactive T cells are activated after encountering self-antigens, after which they migrate across the blood-brain barrier into the CNS (2). Here, these T cells are reactivated , leading

Research paper thumbnail of Relapsing-remitting multiple sclerosis patients display an altered lipoprotein profile with dysfunctional HDL

Scientific reports, Jan 23, 2017

Lipoproteins modulate innate and adaptive immune responses. In the chronic inflammatory disease m... more Lipoproteins modulate innate and adaptive immune responses. In the chronic inflammatory disease multiple sclerosis (MS), reports on lipoprotein level alterations are inconsistent and it is unclear whether lipoprotein function is affected. Using nuclear magnetic resonance (NMR) spectroscopy, we analysed the lipoprotein profile of relapsing-remitting (RR) MS patients, progressive MS patients and healthy controls (HC). We observed smaller LDL in RRMS patients compared to healthy controls and to progressive MS patients. Furthermore, low-BMI (BMI ≤ 23 kg/m(2)) RRMS patients show increased levels of small HDL (sHDL), accompanied by larger, triglyceride (TG)-rich VLDL, and a higher lipoprotein insulin resistance (LP-IR) index. These alterations coincide with a reduced serum capacity to accept cholesterol via ATP-binding cassette (ABC) transporter G1, an impaired ability of HDL3 to suppress inflammatory activity of human monocytes, and modifications of HDL3's main protein component ApoA...

Research paper thumbnail of Label-Free Imaging of Umbilical Cord Tissue Morphology and Explant-Derived Cells

Stem Cells International, 2016

In situ detection of MSCs remains difficult and warrants additional methods to aid with their cha... more In situ detection of MSCs remains difficult and warrants additional methods to aid with their characterization in vivo. Two-photon confocal laser scanning microscopy (TPM) and second harmonic generation (SHG) could fill this gap. Both techniques enable the detection of cells and extracellular structures, based on intrinsic properties of the specific tissue and intracellular molecules under optical irradiation. TPM imaging and SHG imaging have been used for label-free monitoring of stem cells differentiation, assessment of their behavior in biocompatible scaffolds, and even cell tracking in vivo. In this study, we show that TPM and SHG can accurately depict the umbilical cord architecture and visualize individual cells both in situ and during culture initiation, without the use of exogenously applied labels. In combination with nuclear DNA staining, we observed a variance in fluorescent intensity in the vessel walls. In addition, antibody staining showed differences in Oct4, αSMA, vi...

Research paper thumbnail of The isotype repertoire of antibodies against novel UH-RA peptides in rheumatoid arthritis

Arthritis Research & Therapy, 2016

Background: Recently, autoantibodies against novel UH-RA peptides (UH-RA.1 and UH-RA.21) were ide... more Background: Recently, autoantibodies against novel UH-RA peptides (UH-RA.1 and UH-RA.21) were identified as candidate biomarkers for patients with rheumatoid arthritis (RA) who are seronegative for the current diagnostic markers rheumatoid factor and anticitrullinated protein antibodies. Previously, screening for anti-UH-RA autoantibodies was based on measuring the immunoglobulin (Ig) G response. We aimed to investigate whether measurement of other isotypes could improve the performance of diagnostic testing. In addition, assigning the isotype profile might provide valuable information on effector functions of the antibodies. Methods: The isotype profile of antibodies against UH-RA.1 and UH-RA.21 was studied. The IgG, IgM, and IgA classes, together with the 4 different IgG subclasses, were determined in 285 patients with RA, 88 rheumatic control subjects, and 90 healthy control subjects. Results: Anti-UH-RA.1 antibodies were primarily of the IgM isotype and twice as prevalent as IgG (IgG3-dominated) and IgA. RA sensitivity when testing for anti-UH-RA.1 IgM was shown to be higher than when testing for the IgG isotype: 18 % versus 9 % sensitivity when RA specificity was set to 90 %. Within antibodies against UH-RA.21, IgG and IgA were more common than IgM. Different anti-UH-RA.21 IgG subclasses were found, with the highest prevalence found for IgG2. Combined testing for IgG and IgA slightly increased RA sensitivity of UH-RA.21-specific antibody testing to 27 % compared with solely testing for IgG (23 %). Notably, a higher number of anti-UH-RA.21 antibody isotypes was related to increased levels of erythrocyte sedimentation rate. Finally, for both antibody responses, the full antibody isotype use was demonstrated in early and seronegative disease. Conclusions: The isotype distribution of anti-UH-RA.1 and anti-UH-RA.21 antibodies was successfully outlined, and, for antibodies against UH-RA.1, we found that isotype-specific testing might have implications for diagnostic testing. The exact mechanisms by which the different antibody isotypes act still have to be unraveled.

Research paper thumbnail of Analysis of antibody reactivity in paired cerebrospinal fluid and serum of a relapsing remitting multiple sclerosis patient

Autoimmunity, Nov 3, 2009

Increasing evidence indicates an involvement of B cells in multiple sclerosis (MS). However, litt... more Increasing evidence indicates an involvement of B cells in multiple sclerosis (MS). However, little is known about antigenic targets recognized by antibodies present in blood and cerebrospinal fluid (CSF) of MS patients. This study was therefore aimed at identifying the antigen reactivity of antibodies present in CSF and compares the identified antibody profile with that of the serum of the same patient using cDNA phage display. Selection rounds on paired CSF and serum of this patient identified 13 antigenic targets of which 5 were enriched by serum antibodies and 2 were identified by CSF antibodies. Interestingly, the six remaining antigenic targets were shown to be recognized by both CSF and serum antibodies. These findings point towards both common as well as distinct antibody profiles in CSF and serum of MS patients.

Research paper thumbnail of In Vivo Clonotypic Regulation in Human Myelin Basic Protein-Reactive T Cells by T Cell Vaccination

The Journal of Immunology, 1995

Research paper thumbnail of Discovery of Novel Antigenic Targets and Autoantibody Markers in Rheumatoid Arthritis

Research paper thumbnail of Involvement of T-cell receptor-� alterations in the development of otosclerosis linked to OTSC2

Genes Immun, 2010

Otosclerosis is a common form of hearing loss, characterized by disordered bone remodeling in the... more Otosclerosis is a common form of hearing loss, characterized by disordered bone remodeling in the otic capsule. Within the otosclerotic foci, several immunocompetent cells and immune-modulating factors can be found. Different etiological theories involving the immune system have been suggested. However, a genetic component is clearly present. In large otosclerosis families, seven autosomal-dominant loci have been found, but none of the disease-causing genes has been identified. This study focused on the exploration of the second otosclerosis locus on chromosome 7q34-36 (OTSC2), holding the T-cell receptor beta locus (TRB locus). A significantly lower T-cell receptor-β (TCR-β) mRNA expression and percentage of blood circulating TCR-αβ+ T cells was detected in OTSC2 patients compared with controls and patients with the complex form of the disease. Further analysis illustrated more significant disturbances in specific T-cell subsets, including an increased CD28null cell population, suggesting a disturbed T-cell development and ageing in OTSC2 patients. These disturbances could be associated with otosclerotic bone remodeling, given the known effects of immunocompetent cells on bone physiology. These data implicate the TRB locus as the causative gene in the OTSC2 region and represent an important finding in the elucidation of the disease pathology.

Research paper thumbnail of Autoantibodies to two novel peptides in seronegative and early rheumatoid arthritis

Rheumatology, 2016

Objectives. Despite recent progress in biomarker discovery for RA diagnostics, still over one-thi... more Objectives. Despite recent progress in biomarker discovery for RA diagnostics, still over one-third of RA patients-and even more in early disease-present without RF or ACPA. The aim of this study was to confirm the presence of previously identified autoantibodies to novel Hasselt University (UH) peptides in early and seronegative RA. Methods. Screening for antibodies against novel UH peptides UH-RA.1, UH-RA.9, UH-RA.14 and UH-RA.21, was performed in two large independent cohorts. Peptide ELISAs were developed to screen for the presence of antibodies to UH-RA peptides. First, 292 RA patients (including 39 early patients), 90 rheumatic and 97 healthy controls from UH were studied. Antibody reactivity to two peptides (UH-RA.1 and UH-RA.21) was also evaluated in 600 RA patients, 309 patients with undifferentiated arthritis and 157 rheumatic controls from the Leiden Early Arthritis Clinic cohort. Results. In both cohorts, 38% of RA patients were seronegative for RF and ACPA. Testing for autoantibodies to UH-RA.1 and UH-RA.21 reduced the serological gap from 38% to 29% in the UH cohort (P = 0.03) and from 38% to 32% in the Leiden Early Arthritis Clinic cohort (P = 0.01). Furthermore, 1933% of early RA patients carried antibodies to these peptides. Specificities in rheumatic controls ranged from 82 to 96%. Whereas antibodies against UH-RA.1 were related to remission, anti-UH-RA.21 antibodies were associated with inflammation, joint erosion and higher tender and swollen joint counts. Conclusion. This study validates the presence of antibody reactivity to novel UH-RA peptides in seronegative and early RA. This might reinforce current diagnostics and improve early diagnosis and intervention in RA.

Research paper thumbnail of Current trends in multiple sclerosis research: an update on pathogenic concepts

Acta Neurologica Belgica, 2007

Financial support: 'Nationaal fonds voor wetenschappelijk onderzoek Vlaanderen (FWO)'

Research paper thumbnail of Citrullination-Specific Phage Display

Research paper thumbnail of Osteoprotegerin and receptor activator of nuclear factor-kappaB ligand mRNA expression in patients with rheumatoid arthritis and healthy controls

The Journal of Rheumatology, Aug 1, 2004

To further understand the role of osteoprotegerin (OPG) and receptor activator of nuclear factor-... more To further understand the role of osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANK-L) in rheumatoid arthritis (RA), we studied the levels of RANK-L and OPG mRNA in peripheral blood mononuclear cells (PBMC) and synovial tissue of patients with RA and controls. Methods. RANK-L and OPG mRNA levels were measured in PBMC and CD4+/CD8+ T cell subsets of patients with chronic RA, osteoarthritis (OA), and healthy controls, using quantitative real-time polymerase chain reaction. OPG and RANK-L mRNA levels were measured in paired blood and synovial tissue samples of patients with early, untreated RA at 2 timepoints with an interval of 16 weeks. Results. RANK-L mRNA levels were significantly higher in PBMC of patients with early and chronic RA compared to healthy controls. Contrary to healthy controls, RANK-L mRNA levels in patients with chronic RA were mainly of CD4+ T cell origin. OPG mRNA was observed in the blood of all (17/17) early RA patients, but could not be detected in chronic RA patients (0/14) or in patients with OA (0/8). Three out of 17 healthy controls showed measurable levels of OPG mRNA. The OPG/RANK-L ratio tended to be higher in the synovium than in the PBMC of early RA patients. RANK-L mRNA in synovial tissue was mainly of non-T cell origin. Conclusion. Since RANK-L and OPG mRNA levels are elevated in PBMC of RA patients, and CD4+ T cells are the major contributors to RANK-L mRNA expression, mononuclear cells in patients with RA may be involved in the pathways that regulate bone metabolism.

Research paper thumbnail of Biomarkers for Rheumatoid Arthritis

Research paper thumbnail of F.113. Local LIF Production in the CNS Limits Autoimmune Demyelination

Clin Immunol, 2009

Furthermore, infusion of Tregs, particularly those expressing CD62L, can prevent or ameliorate GV... more Furthermore, infusion of Tregs, particularly those expressing CD62L, can prevent or ameliorate GVHD in mice. Therefore, we sought to determine if GVHD in humans is also associated with a dearth of Tregs. We identified 63 HSCT recipients with or without GVHD at the point of diagnosis, prior to any alteration of their immunosuppressive regimen, and obtained both peripheral blood for flow cytometric analysis and GI biopsy material for immunohistochemical analysis. However, we found the percent of T cells that were FOXP3+ to be no lower in the blood or GI mucosa with GI GVHD, and actually found more FOXP3+ cells to be present in the blood when GVHD was histologically evident in both the upper and lower GI tract. Furthermore, the fraction of FOXP3+ T cells that were CD62L+ in the blood was actually higher in patients with histological evidence of GI GVHD than in those without, contrary to murine data. Among patients with GVHD, Treg frequency did not correlate with GVHD severity. In conclusion, we found no evidence that GI GVHD is caused by a lack of Tregs, and suggest that proposed clinical trials of Treg infusions for GVHD may prove less beneficial for humans than they have for mice.

Research paper thumbnail of Increased frequency of γδ T cells in cerebrospinal fluid and peripheral blood of patients with multiple sclerosis: Reactivity, cytotoxicity, and T cell receptor V gene rearrangements