PubMed Health⌕ Search

Biomedical subjects

Reinhard Hohlfeld

Publications and source records attributed to Reinhard Hohlfeld.

43 records · Page 3Linked to original sources
PubMed2002

An autoreactive gamma delta TCR derived from a polymyositis lesion.

To investigate the role of gammadelta T cells in human autoimmune disease we expressed and characterized a gammadelta TCR from an autoimmune tissue lesion. The TCR was first identified in a rare form of polymyositis characterized by a monoclonal infiltrate of gammadelta T cells which invaded and destroyed skeletal muscle fibers. The Vgamma1.3-Jgamma1-Cgamma1/Vdelta2-Jdelta3 TCR cDNA of the original muscle invasive gammadelta T cell clone was reconstructed from unrelated cDNA and transfected into the mouse hybridoma BW58alpha(-)beta(-). Appropriate anti-human gammadelta TCR Abs stimulated the TCR transfectants to produce IL-2, thus demonstrating that the human gammadelta TCR functionally interacted with murine signaling components. The transfected Vgamma1.3/Vdelta2 TCR recognized a cytosolic protein expressed in cultured human myoblasts and TE671 rhabdomyosarcoma cells. The Ag was recognized in the absence of presenting cells. Using a panel of control gammadelta TCR transfectants with defined exchanges in different positions of both TCR chains, we showed that the gammadelta TCR recognized its Ag in a TCR complementarity-determining region 3-dependent way. To our knowledge, this is the first example of a molecularly defined gammadelta TCR directly derived from an autoimmune tissue lesion. The strategy used in this study may be applicable to other autoimmune diseases.

Amino Acid Sequence↗
PubMed2002

Immunological assay for assessing the efficacy of glatiramer acetate (Copaxone) in multiple sclerosis. A pilot study.

Recently we described an enzyme-linked immunoadsorbent spot (ELISPOT) assay allowing us to define an immunological response profile observed in multiple sclerosis patients treated with Copaxone (glatiramer acetate; GA) but not untreated subjects [4]. The profile encompasses three criteria, a) reduced proliferative response to GA (as observed with a standard primary proliferation assay); b) strong in vitro activation of interferon-gamma-producing T cells at high concentrations of GA (as detected by interferon-gamma ELISPOT); and c) activation of interleukin-4-producing T cells over a wider range of concentrations of GA (as detected by interleukin-4 ELISPOT). It is at present unknown whether the immunological response to GA correlates with the clinical response. To address this question we performed the pilot study reported here. We asked the major German multiple sclerosis centres to send us blood samples from all GA-treated patients who were going to discontinue treatment because of treatment failure. The clinical nonresponders either had an unchanged or increased exacerbation rate, or developed a secondary progressive course during GA treatment. Over more than one year, we prospectively collected 9 samples from clinical non-responders. We compared the immune response to GA of peripheral blood mononuclear cells from the 9 clinical nonresponders with 15 clinical responders, using a standard proliferation assay combined with ELISPOT assays for detection of interferon-gamma and interleukin-4 secreting cells. Thirteen (86 %) of the 15 clinical responders met at least 2 of the immunological response criteria mentioned above. In contrast, only 2 (22 %) of the 9 clinical nonresponders met two of the immunological criteria (p = 0.0006). We conclude that the ELISPOT assay may provide a promising additional tool for monitoring the treatment response in multiple sclerosis patients treated with GA.

Adult↗
PubMed2002

BDNF and gp145trkB in multiple sclerosis brain lesions: neuroprotective interactions between immune and neuronal cells?

Recent immunohistological and imaging studies emphasize the crucial role of axonal injury in determining the extent of permanent neurological deficits in patients with multiple sclerosis. We have recently shown that human immune cells are capable of producing the neurotrophin brain-derived neurotrophic factor (BDNF), which can prevent axonal and neuronal damage after various pathological insults. BDNF imported into the CNS by immune cells would thus be an attractive candidate for mediating neuroprotective effects in multiple sclerosis. The aim of the present study was to perform a detailed immunohistochemical analysis of the expression of BDNF and its receptor truncated trkB tyrosine kinase receptor (gp145trkB) in a series of multiple sclerosis brain lesions. Our data show that various types of neurones throughout the brain are BDNF immunopositive in multiple sclerosis patients as well as in controls. Furthermore, in multiple sclerosis lesions, BDNF is primarily present in immune cells (T cells, macrophages/microglia) and reactive astrocytes. The number of BDNF immunopositive cells correlates with lesional demyelinating activity. The BDNF receptor gp145trkB is found in neurones in the immediate vicinity of multiple sclerosis plaques as well as in reactive astrocytes within the lesion, but not in immune cells. Our results demonstrate that both BDNF and gp145trkB are expressed in multiple sclerosis lesions. This suggests that BDNF and gp145trkB are involved in immune-mediated neuroprotective interactions in multiple sclerosis, and supports the concept that immune cells produce both damaging and protective factors in multiple sclerosis lesions.

Adult↗
PubMed2002

Glatiramer acetate-specific T-helper 1- and 2-type cell lines produce BDNF: implications for multiple sclerosis therapy. Brain-derived neurotrophic factor.

The clinical effects of glatiramer acetate (GA), an approved therapy for multiple sclerosis, are thought to be largely mediated by a T-helper 1 (TH1) to T-helper 2 (TH2) shift of GA-reactive T-lymphocytes. Current theories propose that activated GA-reactive TH2 cells penetrate the CNS, release anti-inflammatory cytokines such as interleukin (IL)-4, IL-5 and IL-10, and thus inhibit neighbouring inflammatory cells by a mechanism termed 'bystander suppression'. We demonstrate that both GA-specific TH2 and TH1 cells produce the neurotrophin brain-derived neurotrophic factor (BDNF). As the signal-transducing receptor for BDNF, the full-length 145 tyrosine kinase receptor (trk) B, is expressed in multiple sclerosis lesions, it is likely that the BDNF secreted by GA-reactive TH2 and TH1 has neurotrophic effects in the multiple sclerosis target tissue. This may be an additional mechanism of action of GA, and may be relevant for therapies with altered peptide ligands in general. To demonstrate that GA-reactive T cells produce BDNF, we selected four GA-specific, long-term T-cell lines (TCLs), which were characterized according to their cytokine profile by intracellular double-fluorescence flow cytometry. Three TCLs (isolated from a normal subject) had the phenotypes TH1, TH1/TH0, and TH0; the fourth, derived from a GA-treated patient, had the phenotype TH2. To demonstrate BDNF production, we used a combination of RT-PCR (reverse transcription-polymerase chain reaction) and two specially designed techniques for BDNF protein detection: one was based on ELISA (enzyme-linked immunosorbent assay) of supernatants from co-cultures of GA-specific TCLs plus GA-pulsed antigen-presenting cells, and the other on the direct intracellular staining of BDNF in individual T cells and flow cytometric analysis. The different assays and different TCLs yielded similar, consistent results. All four GA-specific T-cell lines, representing the major different TH phenotypes, could be stimulated to produce BDNF.

Brain↗
PubMed2002

Therapeutic approaches in multiple sclerosis: lessons from failed and interrupted treatment trials.

The therapy for multiple sclerosis (MS) has changed dramatically over the past decade. Recent immunobiological findings and current pathophysiological concepts together with advances in biotechnology, improvements in clinical trial design and development of magnetic resonance imaging have led to a variety of evaluable therapeutic approaches in MS. However, in contrast to the successfully introduced and established immunomodulatory therapies (e.g. interferon-beta and glatiramer acetate), there have been a remarkable number of therapeutic failures as well. Despite convincing immunological concepts, impressive data from animal models and promising results from phase I/II studies, the drugs and strategies investigated showed no benefit or even turned out to have unexpectedly severe adverse effects. Although to date there is no uniformly accepted model for MS, there is agreement on the significance of inflammatory events mediated by autoreactive T cells in the CNS. These can be modified therapeutically at the individual steps of a hypothetical pathogenetic cascade. Crucial corners like: the prevalence and peripheral activation of CNS-autoreactive T cells in the periphery;adhesion and penetration of T cells into the CNS;local activation and proliferation and;de- and remyelination processes can be targeted through their putative mediators. Like a 'specificity pyramid', therapeutic approaches therefore cover from general immunosuppression up to specific targeting of T-cell receptor peptide major histocompatibility (MHC) complex. We discuss in detail clinical MS trials that failed or were discontinued for other reasons. These trials include cytokine modulators [tumour necrosis factor (TNF)-alpha antagonists, interleukin-10, interleukin-4, transforming growth factor-beta2], immunosuppressive agents (roquinimex, gusperimus, sulfasalazine, cladribine), inducers of remyelination [intravenous immunoglobulins (IVIg)], antigen-derived therapies [oral tolerance, altered peptide ligands (APL), MHC-Peptide blockade], T cell and T-cell receptor directed therapies (T cell vaccination, T-cell receptor peptide vaccination), monoclonal antibodies against leucocyte differentiation molecules (anti-CD3, anti-CD4), and inactivation of circulating T cells (extracorporeal photopheresis). The main conclusions that can be drawn from these 'negative' experiences are as follows. Theoretically promising agents may paradoxically increase disease activity (lenercept, infliximab), be associated with unforeseen adverse effects (e.g. roquinimex) or short-term favourable trends may reverse with prolonged follow-up (e.g. sulfasalzine). One should not be too enthusiastic about successful trials in animal models (TNFalpha blockers; oral tolerance; remyelinating effect of IVIg) nor be irritated by non-scientific media hype (deoxyspergualine; bone marrow transplantation). More selectivity can imply less efficacy (APL, superselective interventions like T-cell receptor vaccination) and antigen-related therapies can stimulate rather than inhibit encephalitogenic cells. Failed strategies are of high importance for a critical revision of assumed immunopathological mechanisms, their neuroimaging correlates, and for future trial design. Since failed trials add to our growing understanding of multiple sclerosis, 'misses' are nearly as important to the scientific process as the 'hits'.

Antibodies, Monoclonal↗