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Reinhard Hohlfeld

Publications and source records attributed to Reinhard Hohlfeld.

At least 37 records · Page 2Linked to original sources
PubMed2004

Autoimmune concepts of multiple sclerosis as a basis for selective immunotherapy: from pipe dreams to (therapeutic) pipelines.

Autoimmune T and B cell responses to CNS antigen(s) are thought to drive the pathogenesis of multiple sclerosis (MS), and thus are logical targets for therapy. Indeed, several immunomodulatory agents, including IFN-beta 1b, IFN-beta 1a, glatiramer acetate, and mitoxantrone, have had beneficial clinical effects in different forms of MS. However, because the available treatments are only partially effective, MS therapy needs to be further improved. Selective (antigen-specific) immunotherapies are especially appealing because in theory they combine maximal efficacy with minimal side effects. Indeed, several innovative immunotherapies have been successfully applied in experimental autoimmune encephalomyelitis. For example, autoreactive T cells can be selectively targeted by means of antigen, T cell receptor, or activation markers. However, experimental autoimmune encephalomyelitis is far from being a perfect approximation of MS because MS is more heterogeneous and the target antigen(s) is (are) not known. Further advances in MS therapy will depend on our growing understanding of the pathogenesis of this still incurable disease.

Animals↗
PubMed2004

Modelling paraneoplastic CNS disease: T-cells specific for the onconeuronal antigen PNMA1 mediate autoimmune encephalomyelitis in the rat.

Antibodies directed against onconeuronal antigens provide a specific diagnostic marker for paraneoplastic neurological syndromes (PNS) and suggest that these autoantigens are targeted during disease pathogenesis. However, so far attempts to generate autoimmune models of PNS have been unsuccessful. Here we show that the adoptive transfer of T-cells specific for the autologous onconeuronal antigen Pnma1 cause encephalomyelitis in the Dark Agouti (DA) rat. The sequence of rat Ma1 (rPnma1) was determined by RT-PCR using primers for human PNMA1, followed by 5' and 3' genome walking. Rat Pnma1 is 93.8% identical to human PNMA1 at the amino acid level. Rat Pnma1 was cloned into the expression vector pQE60, and recombinant protein purified by metal chelate chromatography. Female DA rats were immunized with recombinant rPnma1 and rPnma1-specific CD4+ T-helper 1 (Th1) T-cell lines generated from the draining lymph nodes 10 days post-immunization. Freshly activated T-cell blasts were transferred into naive female DA rats, which were killed up to 9 days later. Proliferation assays demonstrated that the CD4+ Th1 T-cells were highly specific for rPnma1. After T-cell transfer the recipients developed a perivascular inflammatory response involving CNS regions affected in human disease. Anti-Pnma1 antibodies were induced by protein immunization, but this was associated with minimal CNS pathology. The induction of an inflammatory response in the CNS following the adoptive transfer of rat Pnma1-specific T-cells demonstrates for the first time that a paraneoplastic autoantigen can initiate a pathogenic effector T-cell response. This animal model strongly supports the hypothesis that the pathogenesis of paraneoplastic CNS neurological syndromes in man involves an autoimmune T-cell component.

Adoptive Transfer↗
PubMed2004

Distinct responses of monocytes to Toll-like receptor ligands and inflammatory cytokines.

In this study we compared the activation of monocytes by different bacterial products via Toll-like receptors (TLR), and by different proinflammatory mediators. In response to TLR-2, -4 and -5 engagement, approximately 50% of monocytes produced TNF-alpha, compared to only 5% after induction with IFN-gamma or GM-CSF. Furthermore, a small proportion of monocytes produced IL-10 after stimulation via TLR, but not after stimulation with cytokines. Both TLR-ligands and inflammatory cytokines induced the expression of CD25, CD69, CD80 and, surprisingly, also of CD83, commonly regarded as an activation marker for mature dendritic cells (DC). Conversely, TLR-ligands downregulated CD38, CD86 and ICOS-L. Importantly, signaling lymphocytic activation molecule (SLAM; CD150) was identified as a monocyte activation marker that could be induced ex novo via TLR-2, -4 and -5, but not by single stimulation with monocyte activators like IL-1, TNF-alpha, IFN-beta, IFN-gamma, GM-CSF or CD40-L. SLAM expression was transient and required mitogen activated protein kinase (MAPK) p38, but not ERK or JNK, and was surprisingly independent of NF-kappaB. SLAM+ monocytes, which are absent in blood, were detected in spleen and tonsils, where they could be localized to T-cell areas and germinal centers. Together, by comparing the response of monocytes to TLR-ligands and inflammatory cytokines, we have identified a monocyte activation marker, SLAM, which differs in its inducibility from other monocyte activation markers. SLAM+ monocytes and macrophages were identified for the first time in vivo. Their presence might be a sign of innate immune activation.

Antigens, CD↗
PubMed2004

Multiple sclerosis: glatiramer acetate inhibits monocyte reactivity in vitro and in vivo.

It is widely assumed that glatiramer acetate (GA), an approved agent for the immunomodulatory treatment of multiple sclerosis, acts primarily as an antigen for T lymphocytes. Recent studies, however, indicated that in vitro, GA directly inhibits dendritic cells, a rare but potent type of professional antigen-presenting cell (APC). To investigate whether these in vitro observations are relevant to the actions of GA in vivo, we studied the effects of GA on monocytes, the major type of circulating APC. In a first series of experiments, we investigated the effects of GA on monocyte reactivity in vitro. Monocytes were stimulated with ligands for Toll-like receptor (TLR)-2 (peptidoglycan and lipoteichoic acid), TLR-4 [lipopolysaccharide (LPS)] and TLR-5 (flagellin), as well as two proinflammatory cytokines (interferon-gamma and granulocyte-monocyte colony-stimulating factor). Monocyte activation was measured by induction of the surface markers signalling lymphocytic activation molecule (SLAM), CD25 and CD69 (detected by cytofluorometry), and by production of monocyte-derived tumour necrosis factor (TNF)-alpha (detected by enzyme-linked immunospot assay). GA had a broad inhibitory effect on all measures of monocyte reactivity, regardless of which stimulator was used. It is unlikely that this reflects a simple toxic effect, because monocyte viability and CD14 expression were unaffected. In a second series of experiments, we investigated the properties of monocytes cultured ex vivo from eight GA-treated multiple sclerosis patients, eight untreated multiple sclerosis patients and eight healthy subjects. We found that LPS-induced SLAM expression and TNF-alpha production were significantly reduced in monocytes from GA-treated patients compared with controls. These results demonstrate for the first time that GA inhibits monocyte reactivity in vitro and in vivo, significantly extending the current concept of the mechanism of action of GA.

Adult↗
PubMed2004

Multiple sclerosis: brain-infiltrating CD8+ T cells persist as clonal expansions in the cerebrospinal fluid and blood.

We surveyed the T cell receptor repertoire in three separate compartments (brain, cerebrospinal fluid, and blood) of two multiple sclerosis patients who initially had diagnostic brain biopsies to clarify their unusual clinical presentation but were subsequently confirmed to have typical multiple sclerosis. One of the brain biopsy specimens had been previously investigated by microdissection and single-cell PCR to determine the clonal composition of brain-infiltrating T cells at the single-cell level. Using complementarity-determining region 3 spectratyping, we identified several identical, expanded CD8+ (but not CD4+) T cell clones in all three compartments. Some of the expanded CD8+ T cells also occurred in sorted CD38+ blood cells, suggesting that they were activated. Strikingly, some of the brain-infiltrating CD8+ T cell clones persisted for >5 years in the cerebrospinal fluid and/or blood and may thus contribute to the progression of the disease.

Amino Acid Sequence↗
PubMed2004

[Cannabinoids in multiple sclerosis. Opportunity or hazard?].

Based on patient reports, animal data, and in vitro experiments, evidence has emerged indicating a positive effect of cannabinoids as symptomatic treatment of spasticity and pain in multiple sclerosis. The recently published CAMS study was the first multicenter, randomized, placebo-controlled phase III trial to examine the efficacy of cannabinoids on symptoms related to MS. There was no treatment effect of cannabinoids on the primary outcome measure, a difference in the reduction of spasticity as assessed by the so-called Ashworth score. In contrast, significant effects on patient-reported spasticity and pain were documented. A major problem of the study was a high degree of patient unmasking in the active treatment group. In this review, the results of the CAMS study are discussed in the context of previous trials, the putative mechanism of action of cannabinoids and their adverse event profile.

Animals↗
PubMed2004

Antigen recognition properties of a Vgamma1.3Vdelta2-T-cell receptor from a rare variant of polymyositis.

Previously we partially characterized an autoreactive human Vgamma1.3Vdelta2-T-cell receptor (TCR) that had originally been identified in muscle of a patient with an unusual form of polymyositis. This TCR recognizes a muscle-associated auto-antigen in a CDR3-dependent, MHC non-restricted way. Here we show that this TCR also recognizes an antigen from Escherichia coli. Like the muscle-associated mammalian antigen, the bacterial antigen is recognized in a CDR3-dependent, but MHC-non-restricted way. Both antigens have strikingly similar molecular characteristics suggesting that their epitopes are at least very similar. The dissociation kinetics of the bacterial antigen-TCR complexes was investigated by surface plasmon resonance using soluble single-chain TCR molecules produced in COS-7 cells. The measured dissociation rate constant (k(off)=5.7 x 10(-3) s(-1)) shows that the complexes dissociate more slowly than most previously described antigen/alphabeta-TCR complexes, but much faster than antibody/antigen pairs. These results (a) provide further insight into the molecular properties of this unusual TCR, and (b) should help in future attempts to identify the elusive target antigen(s).

Animals↗
PubMed2004

Immunologic factors in primary progressive multiple sclerosis.

Primary progressive multiple sclerosis (PPMS) is clinically characterized by progression without remission or relapse, in contrast to relapsing forms of MS. Pathologic and imaging findings also indicate that PPMS differs from relapsing forms. Recent studies examining potential immunologic differences among MS forms suggest that cytokine and adhesion molecule expression profiles, but not chemokine receptor profiles, in PPMS patients resemble those in healthy controls more than those in patients with relapsing MS. However, the significance of these findings remains to be fully elucidated, and there is little additional evidence as yet of marked differences among MS forms based on immunologic characteristics. Of interest are the recent demonstrations that activated immune cells produce brain-derived neurotrophic factor (BDNF), a neuroprotective factor, in MS lesions, that BDNF receptors are located in MS tissue, and that glatiramer acetate (GA)-specific T cells produce BDNF irrespective of T helper cell Th1 or Th2 phenotype. These findings both support the concept of a protective inflammation in MS and suggest an additional mechanism of action for the clinical effects of GA therapy in MS. Whether and to what extent this mechanism is present in different MS forms remain to be clarified.

Anti-Inflammatory Agents↗
PubMed2003

Polymyositis and dermatomyositis.

The inflammatory myopathies, commonly described as idiopathic, are the largest group of acquired and potentially treatable myopathies. On the basis of unique clinical, histopathological, immunological, and demographic features, they can be differentiated into three major and distinct subsets: dermatomyositis, polymyositis, and inclusion-body myositis. Use of new diagnostic criteria is essential to discriminate between them and to exclude other disorders. Dermatomyositis is a microangiopathy affecting skin and muscle; activation and deposition of complement causes lysis of endomysial capillaries and muscle ischaemia. In polymyositis and inclusion-body myositis, clonally expanded CD8-positive cytotoxic T cells invade muscle fibres that express MHC class I antigens, which leads to fibre necrosis via the perforin pathway. In inclusion-body myositis, vacuolar formation with amyloid deposits coexists with the immunological features. The causative autoantigen has not yet been identified. Upregulated vascular-cell adhesion molecule, intercellular adhesion molecule, chemokines, and their receptors promote T-cell transgression, and various cytokines increase the immunopathological process. Early initiation of therapy is essential, since both polymyositis and dermatomyositis respond to immunotherapeutic agents. New immunomodulatory agents currently being tested in controlled trials may prove promising for difficult cases.

Dermatomyositis↗
PubMed2003

Clonal tracking of autoaggressive T cells in polymyositis by combining laser microdissection, single-cell PCR, and CDR3-spectratype analysis.

Clonal expansions of CD8+ T cells have been identified in muscle and blood of polymyositis patients by PCR techniques, including T cell receptor (TCR) complementarity-determining region (CDR)3 length analysis (spectratyping). To examine a possible pathogenic role of these clonally expanded T cells, we combined CDR3 spectratyping with laser microdissection and single-cell PCR of individual myocytotoxic T cells that contact, invade, and destroy a skeletal muscle fiber. First, we screened cDNA from muscle biopsy specimens by CDR3 spectratyping for expanded TCR beta chain variable region (BV) sequences. To pinpoint the corresponding T cells in tissue, we stained cryostat sections with appropriate anti-TCR BV mAbs, isolated single BV+ T cells that directly contacted or invaded a muscle fiber by laser-assisted microdissection, and amplified their TCR BV chain sequences from rearranged genomic DNA. In this way, we could relate the oligoclonal peaks identified by CDR3-spectratype screening to morphologically characterized microdissected T cells. In one patient, a large fraction of the microdissected T cells carried a common TCR-BV amino acid CDR3 motif and conservative nucleotide exchanges in the CDR3 region, suggesting an antigen-driven response. In several cases, we tracked these T cell clones for several years in CD8+ (but not CD4+) blood lymphocytes and in two patients also in consecutive muscle biopsy specimens. During immunosuppressive therapy, oligoclonal CDR3-spectratype patterns tended to revert to more polyclonal Gaussian distribution-like patterns. Our findings demonstrate that CDR3 spectratyping and single-cell analysis can be combined to identify and track autoaggressive T cell clones in blood and target tissue. This approach should be applicable to other inflammatory and autoimmune disorders.

Adult↗
PubMed2003

Neurotrophic cross-talk between the nervous and immune systems: implications for neurological diseases.

Inflammatory reactions in the central nervous system usually are considered detrimental, but recent evidence suggests that they also can be beneficial and even have neuroprotective effects. Intriguingly, immune cells can produce various neurotrophic factors of various molecular families. The concept of "neuroprotective immunity" will have profound consequences for the pathogenesis and treatment of neuroinflammatory diseases such as multiple sclerosis. It also will prove important for neurodegenerative disorders, in which inflammatory reactions often occur. This review focuses on recent findings that immune cells produce brain-derived neurotrophic factor in multiple sclerosis lesions, whereas neurons and astrocytes express the appropriate tyrosine kinase receptor TrkB. Together with functional evidence for the neuroprotective effects of immune cells, these observations support the concept of "neuroprotective immunity." We next examine current and future therapeutic strategies for multiple sclerosis and experimental autoimmune encephalomyelitis in light of neuroprotective immunity and finally address the broader implications of this new concept for other neuroinflammatory and neurodegenerative diseases.

Animals↗
PubMed2003

T-cell-mediated autoimmunity: novel techniques to characterize autoreactive T-cell receptors.

Histological samples of autopsy or biopsy tissue provide the best available evidence that autoreactive T cells are involved in the immunopathogenesis of many autoimmune diseases. However, morphology alone does not provide information on the antigen-specific T-cell receptor (TCR) of these cells, let alone on their antigen specificity. In this review article we discuss a number of emerging possibilities for identifying TCR sequences directly from biopsy tissue. We also review the methods for expressing presumably autoreactive TCR molecules and speculate on how the expressed TCR might be used to identify target antigens. Such information should eventually provide new insights into disease pathogenesis which lead to better therapies.

Autoimmunity↗
PubMed2003

Basic principles of immunotherapy for neurologic diseases.

Immunosuppressive drugs and immunomodulating procedures can improve the quality of life in patients with immune-related neurologic diseases and can even be lifesaving if properly used to avoid deleterious or irreversible adverse effects. For the successful use of these drugs or procedures, the treating physician must be familiar and comfortable with the drugs' mode of action, the accuracy of the diagnosis, the goals and expectations of therapy, and the risk-benefit ratio of the therapy. Improvement must be based on a beneficial change in activities of daily living and not solely on a change in the laboratory test values.

Activities of Daily Living↗
PubMed2003

The non-classical MHC molecule HLA-G protects human muscle cells from immune-mediated lysis: implications for myoblast transplantation and gene therapy.

HLA-G is a non-classical MHC class I molecule with highly limited tissue distribution which has been attributed chiefly immune-regulatory functions. We previously have reported that HLA-G is expressed in inflamed muscle in vivo and by cultured myoblasts in vitro. Here, we used the in vitro models of human myoblasts or TE671 muscle rhabdomyosarcoma cells to characterize the functional role of HLA-G for muscle immune cell interactions. Gene transfer of the two major isoforms of HLA-G (transmembranous HLA-G1 and soluble HLA-G5) into TE671 rendered these cells resistant to alloreactive lysis by direct inhibition of natural killer (NK) cells, and CD4 and CD8 T cells. Further, HLA-G reduced alloproliferation, interfered with effective priming of antigen-specific cytotoxic T cells and reduced antigen-specific alloreactive lysis. HLA-G pre-induced on cultured myoblasts inhibited lysis by alloreactive peripheral blood mononuclear cells. This protection was reversed by a neutralizing HLA-G antibody. Interestingly, a few HLA-G-positive cells within a population of HLA-G-negative muscle target cells conveyed significant inhibitory effects on alloreactive lysis. Our results reveal further insights into the immunobiology of muscle and suggest that ectopic expression of HLA-G may promote the survival of transplanted myoblasts in the future treatment of hereditary muscle diseases. Further, HLA-G could represent a novel self-derived anti-inflammatory principle applicable in strategies against inflammatory aggression.

Apoptosis↗
PubMed2003

Muscle fibres and cultured muscle cells express the B7.1/2-related inducible co-stimulatory molecule, ICOSL: implications for the pathogenesis of inflammatory myopathies.

Inducible co-stimulator ligand (ICOSL), a member of the B7 family of co-stimulatory molecules related to B7.1/2, regulates CD4 as well as CD8 T-cell responses via interaction with its receptor ICOS on activated T cells. Here we examined the expression and the functional relevance of ICOSL in human muscle cells in vivo and in vitro. We investigated 25 muscle biopsy specimens from patients with polymyositis, dermatomyositis, inclusion body myositis, Duchenne muscular dystrophy and non-myopathic controls for ICOSL expression by immunohistochemistry. Normal muscle fibres constitutively express low levels of ICOSL. However, ICOSL expression is markedly increased in muscle fibres in inflammatory myopathies. Cell surface staining was most prominent in the contact areas between muscle fibres and inflammatory cells, which in turn show expression of ICOS as a marker of T-cell activation. Muscle endothelial cells show constitutive expression of ICOSL under normal and pathological conditions. We also detected mRNA and cell surface protein expression of ICOSL on myoblasts cultured from control subjects and patients as well as in TE671 muscle rhabdomyosarcoma cells. ICOSL expression was upregulated by tumour necrosis factor-alpha (TNF-alpha), whereas interferon-gamma (IFN-gamma) had no such effect. Co-culture experiments of major histocompatibility complex (MHC) class II-positive myoblasts with CD4 T cells together with superantigen demonstrated that the expression of muscle-related ICOSL has functional consequences: the production of Th1 (IFN-gamma) and Th2 cytokines [interleukin (IL)-4 and IL-10] by CD4 T cells was markedly reduced in the presence of a neutralizing anti-ICOSL monoclonal antibody (mAb HIL-131), thus showing the importance of ICOSL co-stimulation for T-cell activation. Taken together, our results demonstrate that human muscle cells express ICOSL, a functional co-stimulatory molecule distinct from B7.1 and B7.2. ICOSL-ICOS interactions may play an important role in inflammatory myopathies, providing further evidence for the antigen-presenting capacity of muscle cells.

Adult↗