Search PubMed⌕ Search

Biomedical subjects

Ralf Gold

Publications and source records attributed to Ralf Gold.

At least 55 records · Page 3Linked to original sources
PubMed2004

Modulation of experimental autoimmune encephalomyelitis by administration of cells expressing antigenic peptide covalently linked to MHC class II.

The MHC class II molecule RT1Bl covalently linked with gpMBP-71-90 was expressed in P80 cells (mouse mastocytoma P815 expressing rat-CD80) and i.v. injection ameleriorated active and adoptive transfer (AT) experimental autoimmune encephalomyelitis (EAE) in Lewis rats. Spinal cord of animals with AT-EAE showed significant increase of apoptotic T-cells at maximum of disease after injection of P80-RT1Bl-MBP-71-90 but not of P80RT1Bl or P80 cells. The data demonstrate a possible therapeutic effect on EAE by provision of T-cell receptor (TCR) and costimulatory signals by genetically engineered antigen presenting cells (APC) and suggest induction of T-cell apoptosis as important mechanism of action.

Adoptive Transfer↗
PubMed2004

Experimental pneumococcal meningitis: impaired clearance of bacteria from the blood due to increased apoptosis in the spleen in Bcl-2-deficient mice.

Necrotic and apoptotic neuronal cell death can be found in pneumococcal meningitis. We investigated the role of Bcl-2 as an antiapoptotic gene product in pneumococcal meningitis using Bcl-2 knockout (Bcl-2(-/-)) mice. By using a model of pneumococcal meningitis induced by intracerebral infection, Bcl-2-deficient mice and control littermates were assessed by clinical score and a tight rope test at 0, 12, 24, 32, and 36 h after infection. Then mice were sacrificed, the bacterial titers in blood, spleen, and cerebellar homogenates were determined, and the brain and spleen were evaluated histologically. The Bcl-2-deficient mice developed more severe clinical illness, and there were significant differences in the clinical score at 24, 32, and 36 h and in the tight rope test at 12 and 32 h. The bacterial titers in the blood were greater in Bcl-2-deficient mice than in the controls (7.46 +/- 1.93 log CFU/ml versus 5.16 +/- 0.96 log CFU/ml [mean +/- standard deviation]; P < 0.01). Neuronal damage was most prominent in the hippocampal formation, but there were no significant differences between groups. In situ tailing revealed only a few apoptotic neurons in the brain. In the spleen, however, there were significantly more apoptotic leukocytes in Bcl-2-deficient mice than in controls (5,148 +/- 3,406 leukocytes/mm2 versus 1,070 +/- 395 leukocytes/mm2; P < 0.005). Bcl-2 appears to counteract sepsis-induced apoptosis of splenic lymphocytes, thereby enhancing clearance of bacteria from the blood.

Animals↗
PubMed2003

Drug targeting by long-circulating liposomal glucocorticosteroids increases therapeutic efficacy in a model of multiple sclerosis.

High-dose glucocorticosteroid hormones are a mainstay in the treatment of relapses in multiple sclerosis. We searched for a way to deliver ultra high doses of glucocorticosteroids to the CNS of rats with experimental autoimmune encephalomyelitis (EAE) using a novel formulation of polyethylene glycol (PEG)-coated long-circulating liposomes encapsulating prednisolone (predni solone liposomes, PL). 3H-labelled PL showed selective targeting to the inflamed CNS, where up to 4.5-fold higher radioactivity was achieved than in healthy control animals. HPLC revealed much higher and more persistent levels of prednisolone in spinal cord after PL compared with an equal dose of free prednisolone. Gold-labelled liposomes could be detected in the target tissue, mostly taken up by macrophages (Mphi), microglial cells and astrocytes. Blood-brain barrier disruption was greatly reduced by 10 mg/kg PL, which was superior to a 5-fold higher dose of free methylprednisolone (MP). PL was also superior to MP in diminishing T-cell infiltration by induction of T-cell apoptosis in spinal cord. Mphi infiltration was clearly decreased only by PL. The percentage of tumour necrosis factor-alpha (TNF-alpha)-positive T cells or Mphi was greatly reduced by PL and by MP. No adverse effects on glial cells were detected. A single injection of PL clearly ameliorated the course of adoptive transfer EAE and EAE induced by immunization. In conclusion, PL is a highly effective drug in treatment of EAE, and is superior to a 5-fold higher dose of free MP, possibly by means of drug targeting. These findings may have implications for future therapy of autoimmune disorders such as multiple sclerosis.

Animals↗
PubMed2003

The pathogenesis of CIDP: rationale for treatment with immunomodulatory agents.

Current knowledge about the pathogenic mechanisms involved in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) supports an autoimmune etiology. Some of the cell and humorally mediated immune responses that contribute to the development of CIDP resemble those implicated in multiple sclerosis (MS). The effector role of circulating antibodies has recently been revisited. In addition, similar to the situation in MS, histopathologic studies support the heterogeneity of disease mechanisms in CIDP, with variants showing axon damage. In addition to intravenous immunoglobulin (IVIg), prednisone, and plasma exchange, immunomodulatory drugs also were used to treat CIDP, although no definitive trial data are available. One class of immunomodulators, interferon beta formulations, has proven efficacy in the treatment of MS, and because of clinical similarities between the two diseases it is attractive to investigate whether some agents that are effective in the treatment of MS would also be effective in CIDP. Preliminary studies have evaluated the effects of interferon beta formulations in the treatment of CIDP, one of which has shown promising results and warrants further investigation.

Adjuvants, Immunologic↗
PubMed2003

Phagocytosis of apoptotic inflammatory cells by microglia and its therapeutic implications: termination of CNS autoimmune inflammation and modulation by interferon-beta.

Apoptosis of autoaggressive T-cells in the CNS is an effective, noninflammatory mechanism for the resolution of T-cell infiltrates, contributing to clinical recovery in T-cell-mediated neuroinflammatory diseases. The clearance of apoptotic leukocytes by tissue-specific phagocytes is critical in the resolution of the inflammatory infiltrate and leads to a profound downregulation of phagocyte immune functions. Adult human microglia from surgically removed normal brain tissue was used in a standardized, light-microscopic in vitro phagocytosis assay of apoptotic autologous peripheral blood-derived mononuclear cells (MNCs). Microglia from five different patients had a high capacity for the uptake of apoptotic MNCs in contrast to nonapoptotic target cells with the phagocytosis rate for nonapoptotic MNCs amounting to only 61.6% of the apoptotic MNCs. A newly described phosphatidylserine receptor, critical in the phagocytosis of apoptotic cells by macrophages, is also expressed at similar levels on human microglia. The effects of the therapeutically used immunomodulatory agent interferon-beta (IFNbeta) were investigated using Lewis rat microglia and apoptotic, encephalitogenic, myelin basic protein-specific autologous T-cells. Also, rat microglia had a high capacity to phagocytose apoptotic T-cells specifically. IFNbeta increased the phagocytosis of apoptotic T-cells to 36.8% above the untreated controls. The enhanced phagocytic activity was selective for apoptotic T-cells and was not mediated by increased IL-10 secretion. Apoptotic inflammatory cells may be efficiently and rapidly removed by microglial cells in the autoimmune-inflamed human CNS. The in vitro increase of phagocytosis by IFNbeta merits further investigations whether this mechanism could also be therapeutically exploited.

Animals↗
PubMed2003

Side effects of intravenous immunoglobulins in neurological autoimmune disorders--a prospective study.

The increased use of intravenous immunoglobulins (IVIg) in the treatment of neurological autoimmune diseases has led to more awareness of adverse reactions. We studied prospectively the side effects of IVIg during 84 treatment courses with a total of 341 infusions under routine clinical conditions. Mild reactions were common. Headache was noted most often, occurring during 30% of treatment courses. There were three severe adverse events (3.6% of all treatment courses) that led to discontinuation of the treatment, namely thrombosis of the jugular vein, allergic reaction and retrosternal pressure. Significant changes in laboratory findings were seen for leucocytes, erythrocytes, haematocrit, haemoglobin, ALAT and ASAT. None of these changes were clinically relevant. The elevation of liver enzymes was dependent on the IVIg preparation used, while there was no association with the underlying disease, age, or gender of the patient. In conclusion, this prospective study confirms the high frequency of mild, self-limited side effects of IVIg. Elevation of liver enzymes may possibly be associated with certain IVIg preparations. Bearing these complications in mind, this prospective study supports the notion that IVIg can generally be regarded as safe, leading to severe adverse events during only 3 (0.9%) of 341 infusions (or 3 of 84 treatment courses, 3.6 %). However, careful monitoring for severe side effects remains mandatory, and we propose that laboratory findings like full blood count, renal and liver function should be monitored routinely.

Adolescent↗
PubMed2003

Lessons from 10 years of interferon beta-1b (Betaferon/Betaseron) treatment.

In 1993, interferon beta-1b (IFN beta-1b, Betaferon/Betaseron) was the first interferon approved in the USA for relapsing-remitting multiple sclerosis (RRMS). Since then, dose-dependent effects of IFN beta in MS have been extensively discussed. Such effects had already been observed in the pivotal trial and were followed by dose comparison trials with IFN beta-1a. Later, the therapeutic efficacy of IFN beta-1b could also be demonstrated in secondary progressive (SP) MS patients. We learnt from further studies that benefit from IFN beta in SPMS seems to be most pronounced in those patients still having active disease with superimposed relapses or clear progression. The most common IFN beta-related adverse events, especially in the early treatment phase, have been flu-like symptoms and injection-site reactions. The consequent management of those as well as of other, less frequent, side-effects turned out to be of tremendous importance to ensure patients' compliance. Based on the experience of 10 years, IFN beta-1b belongs to the firstline therapeutics in RR and SPMS.

Adult↗
PubMed2003

Effects of polyclonal immunoglobulins and other immunomodulatory agents on microglial phagocytosis of apoptotic inflammatory T-cells.

T-cell apoptosis in the CNS is an effective mechanism for the noninflammatory resolution of autoimmune T-cell infiltrates. Ingestion of apoptotic leukocytes by microglia results in an efficient clearance of the inflammatory infiltrate, followed by a profound downregulation of proinflammatory phagocyte immune functions. The effects of different immunomodulatory agents on Lewis rat microglial phagocytosis of apoptotic autologous thymocytes or myelin-basic protein (MBP)-specific, encephalitogenic T-cells were investigated using a standardized, light microscopical in vitro phagocytosis assay. Pretreatment of microglia with polyclonal 7S immunoglobulins (IVIg) decreased the phagocytosis of apoptotic thymocytes by 38.2% (p<0.0001). Also, immunoglobulin F(ab')(2) fragments decreased microglial phagocytosis, suggesting an Fc receptor-independent mechanism. Similar results were obtained using MBP-specific T-cells. Pretreatment of microglia with IFN-gamma increased the phagocytosis of apoptotic cells by 65.4%, which was to a large extent counteracted by IVIg. Glatiramer acetate (GLAT) did not exert an effect on microglial phagocytosis, while methylprednisolone (MP) induced microglial apoptosis in vitro. These results indicate that IVIg has a high potential to inhibit microglial phagocytosis of apoptotic inflammatory T-cells even under proinflammatory conditions and extend our view of the complex immunomodulatory effects of IVIg.

Animals↗
PubMed2003

Treatment and prevention of experimental autoimmune neuritis with superagonistic CD28-specific monoclonal antibodies.

Two distinct CD28-specific mAb were used in treatment of active or adoptive transfer (AT)-experimental autoimmune neuritis (EAN): "superagonistic" JJ316 activates T cells without T cell receptor (TCR) occupancy, and conventional JJ319 activates T cells only in the presence of TCR-stimulation. Treatment with JJ316 during induction phase of active and adoptive-transfer experimental autoimmune encephalomyelitis (AT-EAN) dramatically reduced disease severity and improved nerve function as revealed by electrophysiology. JJ316 given 1 week before immunization had a preventive effect. By immunohistology, JJ316 markedly reduced TC infiltration of the sciatic nerve in active and AT-EAN. JJ319 was less effective. Ex vivo, JJ316 therapy reduced P2-specific proliferation and interferon-gamma (IFN-gamma) production of lymph node cells. We demonstrate preventive and therapeutic effects of a "superagonistic" mAb-mediated, TCR-independent CD28 stimulation in EAN, possibly with implications for therapy of autoimmune-inflammatory disorders.

Adoptive Transfer↗
PubMed2003

Immunotherapy in autoimmune neuromuscular disorders.

Important progress has been made in our understanding of the cellular and molecular processes underlying autoimmune neuromuscular diseases that has led us to identify targets for rational therapeutic intervention. Although antigen-specific immunotherapy is not yet available, old and new immunomodulatory treatments, alone or in combination, provide effective immunotherapy for most autoimmune disorders. In parallel, the achievements of molecular medicine provide more specific yet largely experimental therapeutic tools that need to be tested in the human diseases. Here we review the principles and targets of immunotherapy for autoimmune neuromuscular disorders, address applications and practical guidelines, and give an outlook on future developments.

Animals↗
PubMed2003

Therapy of neurological disorders in systemic vasculitis.

Significant progress has been made in our understanding of the underlying cellular and molecular mechanisms associated with vasculitis. Simultaneous involvement of the nervous system and systemic organs points to shared antigenic targets or immune mechanisms operative at both sites. Although specific immunotherapy is not available, the old and new immunomodulatory therapies have been instrumental in providing effective therapy in most of these chronic autoimmune disorders. The treatment of giant cell arteritis, neurosarcoidosis, Wegener's granulomatosis, systemic lupus erythematosus, polyarteritis, Sjögren's syndrome, and Behcet disease will be reviewed.

Adjuvants, Immunologic↗
PubMed2003

Non-invasive functional and biochemical assessment of mitoxantrone cardiotoxicity in patients with multiple sclerosis.

As mitoxantrone is a recently approved immunosuppressant for managing multiple sclerosis, the number of patients treated with this effective but potentially cardiotoxic anthracenedione derivative will increase substantially. To detect subclinical mitoxantrone-induced cardiotoxicity, sensitive non-invasive diagnostic tools are required. Assuming that changes in myocardial high-energy phosphate metabolism and alterations in left ventricular (LV) diastolic performance might be early markers of mitoxantrone-induced cardiotoxicity we examined fifteen MS patients treated with mitoxantrone up to 100 mg/m2 compared with 15 matched control MS patients. 31P-magnetic resonance (MR) spectroscopy was employed to measure myocardial high-energy phosphate metabolism, MR imaging for morphometric evaluation of changes in LV geometry. Indices of diastolic performance were assessed by Doppler echocardiography. In this exploratory study, phosphocreatine/ATP ratios were comparable between mitoxantrone-treated and control patients (1.48 +/- 0.23 and 1.43 +/- 0.41). LV mass, LV end-diastolic and systolic volumes, wall motion score, EF and cardiac output did not differ between both groups. All parameters of diastolic performance (E/A-ratio, isovolumic relaxation time, and E-wave deceleration time) were not different and within normal limits.In conclusion, using advanced diagnostic methodology, including functional, morphometric, and biochemical measurements no cardiotoxic effect of mitoxantrone up to a cumulative dose range of 100 mg/m2 could be detected.

Adolescent↗
PubMed2003

Intravenous liposomal prednisolone downregulates in situ TNF-alpha production by T-cells in experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) relapses are treated with high-dose IV glucocorticosteroids. Here we investigated mechanisms of long-circulating polyethylene glycol-coated liposomes encapsulating prednisolone (PL) in adoptive transfer experimental autoimmune encephalomyelitis. Rats received IV 10 mg/kg PL 6, 18, or 42 hr before sacrifice at disease maximum. In formalin-fixed, paraffin-embedded spinal cord we employed a nonfluorescent immunohistochemical (IHC) double labeling. We stained for tumor necrosis factor-alpha (TNF-alpha) in combination with a T-cell antigen. Compared with PBS-containing liposomes, PL at 18 hr, and more at 42 hr, significantly reduced the rate of TNF-alpha double-labeled T-cells. This correlated with an ameliorated disease score at day 5 after PL 42 hr. Our results help to further understand mechanisms of action of drug targeting by liposomal steroids, with possible implications for treatment of autoimmune disorders such as MS.

Animals↗
PubMed2002

Paraneoplastic myasthenia gravis correlates with generation of mature naive CD4(+) T cells in thymomas.

Myasthenia gravis (MG) is the leading paraneoplastic manifestation of thymomas and is probably related to the capacity of thymomas to mature and export potentially autoreactive T cells. Why some thymomas are MG associated (MG+) and others are not (MG-) has been unclear. We addressed this question by comparing the percentages of intratumorous naive mature CD45RA+ thymocytes in 9 MG(+) and in 13 MG(-) thymomas by fluorescence-activated cell sorting analysis. Our results show that intratumorous naive CD4 T cells were present in all MG(+) thymomas and in one MG(-) thymoma with the development of MG only 2 months after surgery. By contrast, the percentage of naive CD4(+) T cells was significantly reduced in all 13 MG(-) thymomas (P <.0001). Alterations in intratumorous thymopoiesis were reflected by corresponding alterations of naive T-cell subset composition in the blood, in that only MG(-) patients had significantly decreased levels (P =.02) of naive CD4(+) T cells compared with age- and sex-matched control persons. We conclude that paraneoplastic MG is highly associated with the efficiency of thymomas to produce and export naive CD4(+) T cells. The acquisition of the CD45RA(+) phenotype on CD4(+) T cells during terminal intratumorous thymopoiesis is associated with the presence of MG in most thymoma patients.

Adult↗
PubMed2002

Effects of intravenous immunoglobulins on T cell and oligodendrocyte apoptosis in high-dose antigen therapy in experimental autoimmune encephalomyelitis.

Intravenous immunoglobulins (IVIg) are purified preparations of immunoglobulins from plasma of healthy human donors containing polyclonal IgG and various immunomodulatory contaminants. IVIg may exert its therapeutic effect at several levels of the immune network. Antigen-specific therapy of adoptive transfer-(AT)-EAE in Lewis rats leads to elevated serum levels of tumor necrosis factor-alpha (TNF-alpha). TNF-alpha release at sites of inflammation increased apoptosis of autoaggressive T cells in spinal cord in situ and oligodendrocyte apoptosis. In addition, autoinflammatory T cells in liver were destroyed and caused liver damage by TNF-alpha release. To explore a possible neutralizing effect of IVIg on TNF-alpha secreted by antigen-specific T cells, we analyzed T cell and oligodendrocyte apoptosis as well as liver damage in rats that had been injected with myelin basic protein (MBP) and co-treated intravenously with human IVIg. As in our earlier studies, we found that TNF-alpha serum levels were raised by antigen therapy and decreased with concomitant IVIg administration. Using IVIg treatment, antigen-induced T cell apoptosis in inflamed spinal cord and liver of MBP/IVIg-treated animals was significantly reduced compared to control rats treated with MBP/albumin. T cell apoptosis decreased to levels observed in EAE rats receiving albumin only. In addition, serum levels of liver enzymes were raised after MBP/albumin administration and decreased by co-treatment with IVIg, indicating protection of hepatocytes by the neutralization of TNF-alpha. In contrast, oligodendrocyte apoptosis in animals receiving MBP/IVIg was significantly higher than in EAE controls. This indicates that IVIg may have different tissue-specific effects. Besides neutralization of TNF-alpha-mediated cell death, IVIg may also interfere with the network of local immune cells, thus modulating survival of glial cells.

Alanine Transaminase↗
PubMed2002

Analysis of maturation states of rat bone marrow-derived dendritic cells using an improved culture technique.

In this study, we examined in more detail the development of rat bone marrow-derived dendritic cells (BMDC). A two-stage culture system was used to propagate BMDC from rat bone marrow precursors. BMDC developed within clusters of proliferating cells after repetitive addition of rat granulocyte/macrophage colony-stimulating factor and rat interleukin (IL)-4 at a concentration of 5 ng/ml to the cultures. Fluorescence-activated cell sorter analysis performed at an early stage of development (day 6) revealed an immature phenotype with intermediate levels of major histocompatibility complex (MHC) class II expression and low levels of the costimulator molecules CD80 and CD86. Upon further culture, a strong upregulation of MHC class II, costimulatory and adhesion molecules could be observed, whereas macrophage marker antigens were downregulated. Late-stage BMDC (day 10) showed a high expression of MHC class I and II, ICAM-1, Ox62 and CD11c, and revealed a split pattern of B7-1 and B7-2. The cell yield was about 40% of the initially plated bone marrow cells with 80% MHC class II-high and less than 20% MHC class II-low positive cells. Full maturation of rat BMDC (day 12) with an almost uniform expression of B7 was achieved by subsequent subculture and further stimulation with rat tumour necrosis factor alpha (TNF-alpha), lipopolysaccharide (LPS) or soluble CD40 ligand (CD40L). Analysis of the cell supernatant revealed a strong IL-12 production after LPS or CD40L, and to a lesser extent after TNF-alpha stimulation. Additionally, LPS-treated, but not CD40L-treated BMDC secreted TNF-alpha into the supernatant. Early-stage BMDC sufficiently triggered a T cell receptor (TCR) downregulation, but did not stimulate naive T cells in an allogeneic mixed leukocyte reaction (MLR) and revealed a low stimulatory capacity in an antigen-specific T cell assay. In contrast, late-stage BMDC and especially fully mature BMDC strongly induced TCR internalisation, elicited high T cell responses in the allogeneic MLR similar to those obtained by mature rat spleen dendritic cells and efficiently activated antigen-specific T cells. In conclusion, this protocol allows easy access to large numbers of rat BMDC at defined maturation stages and selective studies for the manipulation of immune responses in rat models.

Animals↗