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A Radbruch

Publications and source records attributed to A Radbruch.

At least 19 recordsLinked to original sources
PubMed2006

The systemic and SmD183-119-autoantigen-specific cytokine memory of Th cells in SLE patients.

OBJECTIVES: The aim of the study was to analyse the cytokine memory of T-cells derived from systemic lupus erythematosus (SLE) patients and healthy donors enriched for autoantigen-specific T-cells by in vitro stimulation with SmD1(83-119), a common autoantigen in SLE. METHODS: Autoreactive CD3+ T-cells derived from 37 SLE patients and 14 healthy donors were enriched by repetitive ex vivo stimulation of peripheral blood mononuclear cells (PBMCs) with SmD1(83-119). For control, PBMCs were stimulated only with interleukin-2 (IL-2). After two rounds of antigenic stimulation, cultures were stimulated with PMA/ionomycin to probe the cytokine memory by intracellular cytokine staining. Frequencies of cytokine-expressing T-cells were analysed and, in SLE patients, compared with disease activities and autoantibody levels. RESULTS: Comparing the cytokine memory in the cultures, SLE patients displayed higher frequencies of tumour necrosis factor-alpha (TNF-alpha)+ T-cells than healthy donors and the frequencies correlated with disease activity. Frequencies of SmD1(83-119)-specific TNF-alpha+ T-cells and of memory T-cells expressing interferon-gamma (IFN-gamma) correlated with serum anti-dsDNA antibody levels. The frequencies of IL-10 expressing SmD1(83-119)-specific T-cells were lower among PBMCs of SLE patients. Relatively higher frequencies of IL-10+ T-cells in SLE patients correlated with low disease activities, and low anti-dsDNA and anti-SmD1(83-119) antibody concentrations in culture supernatants. CONCLUSIONS: The memory of autoreactive SmD1(83-119)-specific and unspecific stimulated peripheral Th cells for re-expression of cytokines is shifted towards more cells expressing TNF-alpha and less IL-10+ cells, when compared SLE patients with normal donors. This shift towards proinflammatory memory effector Th cells correlates with disease severity and humoral autoimmunity.

Antibodies, Antinuclear↗
PubMed2006

Membrane glucocorticoid receptors are down regulated by glucocorticoids in patients with systemic lupus erythematosus and use a caveolin-1-independent expression pathway.

BACKGROUND: Membrane-bound glucocorticoid receptors (mGCR) are up regulated on monocytes after in vitro stimulation and in patients with rheumatoid arthritis. Caveolin-1 is critical for the transport of plasma membrane oestrogen receptors to the cell surface. OBJECTIVES: To investigate the expression of mGCR in patients with systemic lupus erythematosus (SLE)-a disease with different aetiopathogenesis and treatment regimens-and to examine whether caveolin-1 is critical for the transport of mGCR to the cell surface. METHODS: Frequencies of mGCR+ peripheral blood mononuclear cells were measured using high-sensitivity immunofluorescent staining and tested for correlation with SLE disease activity and glucocorticoid treatment. Semiquantitative polymerase chain reaction, immunofluorescence, recombinant expression and confocal laser-scanning microscopy were used to search for an association of mGCR with caveolin-1. RESULTS: The frequencies of mGCR+ monocytes (CD14+) were considerably higher in patients with SLE (n = 33) than in healthy controls (n = 58), whereas B cells (CD19+) were not different in this regard. T cells (CD3+) were always mGCR-. The frequency of mGCR+ monocytes in patients with SLE did not correlate with disease activity, but did inversely correlate with glucocorticoid dosages; this inverse correlation was confirmed by corresponding in vitro experiments with stimulated monocytes. The induced up regulation of mGCR was not accompanied by an up regulation of caveolin-1, and mGCR are not colocalised with caveolin-1 in plasma membrane caveolae. CONCLUSION: mGCR are (a) up regulated in patients with SLE and by inflammatory stimuli and (b) down regulated by glucocorticoids, suggesting a negative feedback loop to control glucocorticoid action. Drugs binding selectively to mGCR may in future prove to be of therapeutic value.

Adult↗
PubMed2006

Immunological memory stabilizing autoreactivity.

The etiopathologies of autoimmune diseases are complex. A broad variety of cell types and gene products are involved. However, clinical and experimental evidence suggests that the importance of an individual factor changes during the course of the disease. Factors and cell types that induce acute autoreactivity and initiate an autoimmune disease could be distinct from those that drive a chronic course of that disease. Autoreactive immunological memory, in particular B cell and plasma cell memory, contributes to chronicity through several mechanisms. Formation of autoreactive memory B cells leads to an increase in the numbers of autoreactive cells. In comparison to naive B cells, these memory B cells show a decreased threshold for activation. Additionally, a fraction of memory B cells express the chemokine receptor CXCR3, which supports their accumulation within chronically inflamed tissues. This may allow their escape from mechanisms for induction of peripheral tolerance. Within the inflamed tissue, inflammatory cytokines and autoantigens provide activation signals that promote plasma cell differentiation and survival. The autoantibodies produced locally by these plasma cells contribute to the severity of inflammation. Together, an autoreactive loop of autoantibody-induced inflammation is formed. Another integral part of immunological memory are long-lived plasma cells. These cells provide persistent humoral antibody memory. Though not all autoantibodies are produced by long-lived plasma cells, these cells have a special impact on immune pathology. Long-lived plasma cells are relatively resistant to existing therapies of immunosuppression and continuously secrete antibodies, without need for restimulation. Long-lived plasma cells provide titers of autoantibodies even during clinically quiescent phases and after immunosuppression. These persisting autoantibody titers, though often low and not causing acute clinical symptoms, are likely to maintain a low level of chronic inflammation and progressive tissue destruction, which reduces the threshold for another break of immunological tolerance.

Animals↗
PubMed2004

[Systemic inflammatory rheumatic diseases competence network].

The foundation of the competence network for rheumatology, which is funded by the "Bundesministerium für Bildung und Forschung" (BMBF) since 1999, succeeded to create a unique research structure in Germany: medical doctors and scientists from six university rheumatology centres (Berlin, Düsseldorf, Erlangen, Freiburg, Hannover und Lübeck/Bad Bramstedt) work closely together with scientists doing basic research at the Deutsches Rheuma-Forschungszentrum (DRFZ), with rheumatological hospitals, reha-clinics, and rheumatologists. Jointly they are searching for causes of systemic inflammatory rheumatic diseases and try to improve therapies-nationwide and with an interdisciplinary approach. The primary objective of this collaboration is to transfer new scientific insights more rapidly in order to improve methods for diagnosis and patients treatment.

Biomedical Research↗
PubMed2004

Cell therapy for autoimmune diseases: does it have a future?

Almost all current therapeutic concepts in autoimmune diseases are based on the systemic suppression of immune functions and are not curative. The recent introduction of biologicals such as tumour necrosis factor blocking antibodies or receptors has added greater specificity to efficient management of disease by targeted suppression of rheumatic inflammation. It is evident, however, that only the elimination of the cells secreting inflammatory mediators, rather than the blockade of secreted molecules, will offer real specific therapeutic advantages in the future. Merely the elimination of such cells and also cells controlling the secreting effector cells could be curative and induce true long term remissions. We review here the state of the art and future therapeutic concepts that are based on the specific modulation of pathogenic cells that induce and sustain autoimmune inflammation. This sounds visionary, however, a variety of basic tools are at hand now. Thus, direct and specific cell therapy of rheumatic diseases will become a true alternative to conventional therapies.

Adoptive Transfer↗
PubMed2003

Predominant cellular immune response to the cartilage autoantigenic G1 aggrecan in ankylosing spondylitis and rheumatoid arthritis.

OBJECTIVES: Based on their HLA association, both ankylosing spondylitis (AS) and rheumatoid arthritis (RA) seem to be T-cell-driven diseases in which the autoantigens remain to be defined. One possible autoantigen is the G1 domain of aggrecan, the major cartilage proteoglycan. In BALB/c mice immunized with this protein, spondylitis and erosive polyarthritis have been reported. Immune reactivity to the G1 has been described in patients with RA and AS in an earlier study. Using novel and more sensitive techniques and relevant controls we sought to define the role of G1 as an autoantigen more precisely and to extend the specific analyses to the peptide level. METHODS: Peripheral blood (PB) mononuclear cells (MNC) from 47 AS patients, 22 RA patients and 20 healthy normal controls were exposed in vitro for 6 h to the cartilage-derived autoantigens G1, human cartilage (HC) gp-39 and collagen II. Synovial fluid (SF) MNC from seven AS and four RA patients were similarly analysed. Furthermore, PB MNC of 15 AS and 10 RA patients were examined with overlapping 18-mer peptides covering the whole G1 protein to identify the immunodominant epitopes. T cells were stained by monoclonal antibodies directed against the surface markers CD4, CD69 and against the intracellular cytokines interferon-gamma (IFN gamma), tumour necrosis factor-alpha (TNF alpha), interleukin 4 (IL-4) and IL-10. The percentage of reactive T cells was quantified by flow cytometry. RESULTS: After antigen-specific stimulation with the G1 protein, the CD4+ T cells of 30 AS patients (61.7%) and of 12 RA patients (54.5%) secreted significant amounts of IFN gamma and TNF alpha, while, in contrast, only 10% of the normal controls showed a response (P < 0.05). The synovial CD4+ T cells of five AS (71.5%) and of all four RA patients showed antigen-specific responses to the G1. In contrast, stimulation with HC gp-39 and collagen II showed no significant IFN gamma and TNF alpha secretion of MNC in all groups. Several G1-derived T-cell epitopes were identified as immunodominant in PB MNC of AS and RA patients and were partly overlapping. CONCLUSIONS: These data show that a cellular immune response to G1 is present in most AS and RA patients. G1-immunodominant epitopes were identified. The relevance of this finding for the pathogenesis of AS and RA remains to be established.

Adipokines↗
PubMed2003

Perturbations of peripheral B lymphocyte homoeostasis in children with systemic lupus erythematosus.

OBJECTIVE: To investigate the distribution of peripheral B cell subpopulations of children with active and inactive systemic lupus erythematosus (SLE) compared with healthy controls. METHODS: Peripheral B cell subpopulations of 11 children with SLE (6 with active and 5 with inactive disease) and 14 age matched normal healthy children were analysed. Active disease was diagnosed in children with a flare of SLE, who received treatment by i.v. cyclophosphamide or i.v. methylprednisolone pulse to control the disease. Additionally, the peripheral B cells of the children with SLE were compared with those of 13 consecutive patients with adult onset SLE. RESULTS: No major difference was found in the frequency and total number of CD27(-)/CD19(+) naïve B cells and CD27(+)/CD19(+) memory B cells between patients with active and inactive lupus and healthy controls, but there was a significant increase in CD27(high) expressing plasma blasts in patients with active SLE. These cells coexpress CD38(+), HLA-DR(dim), surface Ig(low) and lack the expression of CD20 but are clearly positive for intracellular Ig, indicative of early plasma cells. Most CD138(+) cells coexpress CD27(high)/CD19(+). The enhanced frequency of peripheral plasma blasts in children with active SLE is consistent with previous findings in adult patients with SLE, whereas a relative predominance of CD27(+) memory B cells was only identified in the adult patients. CONCLUSIONS: Profound abnormalities in the distribution of B cell compartments are more pronounced in older patients with SLE, but an enhanced frequency and cell number of peripheral plasma blasts is characteristic of both diseases during active stages. Thus detection of CD27(high) plasma blasts significantly correlates with active lupus in both children and adults.

Adolescent↗
PubMed2002

[Cytometric analyses in systemic autoimmune diseases].

A number of autoantibodies play a significant role in collagen vascular diseases and represent diagnostic markers of some of these entities. Despite increasing knowledge of these serological findings, data are limited about potential disturbances of precursor cells that finally lead to the autoantibody producing plasma cells. Recent evidence of disturbed B cell homeostasis indicates that the peripheral B cell compartments in systemic lupus erythematodes (SLE) and Sjögren's syndrome are characteristically different to normal. Although the identification of autoreactive B cells in peripheral blood is still subject of ongoing studies, the differences in B cell subsets add to the understanding of the immunopathogenesis of these diseases and may provide new diagnostic clues and therapeutical avenues of these entities.

Autoimmune Diseases↗
PubMed2002

[Preface].

Explore the source record for details and available documents.

Biomedical Research↗
PubMed2002

Detection and characterization of plasma cells in peripheral blood: correlation of IgE+ plasma cell frequency with IgE serum titre.

In atopic patients and patients with hyper-IgE syndrome (HIE) highly elevated IgE serum levels can be detected. Due to their very low frequency little is known about IgE-producing plasma cells (PC) in peripheral blood. We used CD138 MACS microbeads to enrich plasma cells from peripheral blood of normal donors, atopic patients and one HIE patient. CD138+ cells were mainly CD45+, CD44++, CD19dim, CD38++, CD27++, CD86+, HLA-DR+/++, CD71dim, VLA-4+, VLA-5-, CD28-, CD25-, CD69-, CLA-, CD20-, CD21- and CD22-. They show weak expression of surface Ig but high levels of intracellular Ig and they secrete Ig in culture. Thus CD138+ cells from peripheral blood show characteristics of early plasma cells. IgE+ CD138+ plasma cells could be detected in 19 of 24 normal donors with an average frequency of 0.06% IgE+ cells among CD138+ cells. Higher frequencies were detected in atopic patients, atopic patients with markedly elevated serum IgE levels and the hyper-IgE patient with an average of 0.32%, 7.21% and 6.54%, respectively. Additionally, using the recently developed cellular affinity matrix technology, we were able to detect IgE secreting plasma cells and thereby could demonstrate that most of the IgE secreting cells express CD138. The frequency of IgE+ CD138+ cells among PBMC correlated highly significantly with serum IgE titres (r = 0.8532***), indicating that IgE secreting CD138+ cells in peripheral blood are directly related to the plasma cell pool contributing to the IgE titre.

Antibody Affinity↗
PubMed2002

Expression of a 4-(hydroxy-3-nitro-phenyl) acetyl (NP) specific equi-murine IgE antibody that mediates histamine release in vitro and a type I skin reaction in vivo.

Due to characteristic clinical signs, immunoglobulins of isotype E (IgE) are believed to be involved in several allergic diseases of the horse. To date, closer investigations have been hampered by the fact that neither purified equine IgE nor anti-equine IgE monoclonal antibodies were available for IgE isotype determination. As an approach to solve this problem, we constructed a stable cell line (EqE6) that expresses recombinant equi-murine IgE specific for 4-(hydroxy-3-nitro-phenyl) acetyl (NP). Biochemical analysis of the purified protein revealed a highly glycosilated IgE monomer of approximately 230,000 Da. The biological ability of the NP-IgE to mediate histamine release after crosslinking with antigen was demonstrated in vitro using equine blood leucocytes. In vivo, the intradermal application of NP-IgE followed by antigen crosslinking induced a type I hypersensitivity skin reaction in horses. Both results indicate that the recombinant NP-IgE contains an intact and functional Fc(epsilon) RI binding site and mediates effector functions in equine basophils and cutaneous mast cells. This equi-murine IgE can be used for the production of IgE-specific polyclonal and monoclonal antibodies. In addition, the NP specificity allows the antigen-specific activation of equine Fc(epsilon)-receptor-expressing cells, such as mast cells and basophils. This property could be used to investigate IgE-mediated mechanisms for a better understanding of equine type I allergic diseases.

Amino Acid Sequence↗
PubMed2001

Identification of HLA-B27-restricted peptides from the Chlamydia trachomatis proteome with possible relevance to HLA-B27-associated diseases.

The association of HLA-B27 with ankylosing spondylitis and reactive arthritis is the strongest one known between an MHC class I Ag and a disease. We have searched the proteome of the bacterium Chlamydia trachomatis for HLA-B27 binding peptides that are stimulatory for CD8(+) cells both in a model of HLA-B27 transgenic mice and in patients. This was done by combining two biomathematical computer programs, the first of which predicts HLA-B27 peptide binding epitopes, and the second the probability of HLA-B27 peptide generation by the proteasome system. After preselection, immunodominant peptides were identified by Ag-specific flow cytometry. Using this approach we have identified for the first time nine peptides derived from different C. trachomatis proteins that are stimulatory for CD8(+) T cells. Eight of these nine murine-derived peptides were recognized by cytotoxic T cells. The same strategy was used to identify B27-restricted chlamydial peptides in three patients with reactive arthritis. Eleven peptides were found to be stimulatory for patient-derived CD8(+) T cells, of which eight overlapped those found in mice. Additionally, we applied the tetramer technology, showing that a B27/chlamydial peptide containing one of the chlamydial peptides stained CD8(+) T cells in patients with Chlamydia-induced arthritis. This comprehensive approach offers the possibility of clarifying the pathogenesis of B27-associated diseases.

Animals↗
PubMed2001

An instructive component in T helper cell type 2 (Th2) development mediated by GATA-3.

Although interleukin (IL)-12 and IL-4 polarize naive CD4(+) T cells toward T helper cell type 1 (Th1) or Th2 phenotypes, it is not known whether cytokines instruct the developmental fate in uncommitted progenitors or select for outgrowth of cells that have stochastically committed to a particular fate. To distinguish these instructive and selective models, we used surface affinity matrix technology to isolate committed progenitors based on cytokine secretion phenotype and developed retroviral-based tagging approaches to directly monitor individual progenitor fate decisions at the clonal and population levels. We observe IL-4-dependent redirection of phenotype in cells that have already committed to a non-IL-4-producing fate, inconsistent with predictions of the selective model. Further, retroviral tagging of naive progenitors with the Th2-specific transcription factor GATA-3 provided direct evidence for instructive differentiation, and no evidence for the selective outgrowth of cells committed to either the Th1 or Th2 fate. These data would seem to exclude selection as an exclusive mechanism in Th1/Th2 differentiation, and support an instructive model of cytokine-driven transcriptional programming of cell fate decisions.

Animals↗