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Biomedical subjects

R W Hoffman

Publications and source records attributed to R W Hoffman.

At least 19 recordsLinked to original sources
PubMed2001

T cells in the pathogenesis of systemic lupus erythematosus.

The role of T cells in the pathogenesis of systemic lupus erythematosus (SLE) is reviewed with a focus on autoantigen-specific T cells in SLE. The initial clue to a role for T cells in SLE was histopathologic studies demonstrating extensive infiltration of T cells at the sites of inflammation. Later studies, showing association between HLA polymorphisms and specific autoantibodies, directly implicated a role for T cells in autoantibody production. More recently, we and others have identified and characterized autoantigen-specific T cells in SLE. We review these studies on the role of autoantigen-specific T cells in SLE and present new findings on the molecular characterization of T cell immunity to Sm-B, Sm-D and U1-70kD small nuclear ribonucleoprotein (snRNP) autoantigens.

Autoantigens↗
PubMed2001

T cell epitope mapping of the Smith antigen reveals that highly conserved Smith antigen motifs are the dominant target of T cell immunity in systemic lupus erythematosus.

B cell and T cell immunity to the Smith Ag (Sm) is a characteristic feature of systemic lupus erythematosus (SLE). We have shown that T cell immunity against Sm can be detected in SLE patients, and that T and B cell immunity against Sm are linked in vivo. TCR usage by Sm-reactive T cells is highly restricted and characteristic of an Ag-driven immune response. Sm is a well-characterized complex Ag consisting of proteins B1, B2, D1, D2, D3, E, F, and G. A unique feature of all Sm proteins is the presence of homologous motifs, Sm motif 1 and Sm motif 2. We used limiting dilution cloning and synthetic peptide Ags to characterize the human T cell immune response against Sm in seven SLE patients. We sought to determine the precise antigenic peptides recognized, the common features of antigenic structure recognized, and the evolution of the T cell response against Sm. We found there was a highly restricted set of Sm self-peptides recognized by T cells, with three epitopes on Sm-B and two epitopes on Sm-D. We found that T cell immunity against Sm-B and Sm-D was encoded within the highly conserved Sm motif 1 and Sm motif 2, and that immunity against these epitopes appeared stable. The present study supports the concept that T cell immunity to Sm is an Ag-driven immune response directed against a highly restricted set of self-peptides, encoded within Sm motif 1 and Sm motif 2, that is shared among all Sm proteins.

Alanine↗
PubMed2001

The appearance of U1 RNP antibody specificities in sequential autoimmune human antisera follows a characteristic order that implicates the U1-70 kd and B'/B proteins as predominant U1 RNP immunogens.

OBJECTIVE: To observe the order of development of anti-U1 RNP peptide antibodies in humans. METHODS: Immunoblots against Jurkat cell lysates were performed on 5,882 serum samples from 3,668 patients referred on clinical grounds for RNP antibody testing to a reference laboratory between 1989 and 1999. In patients from whom multiple samples were drawn, we determined the order in which IgG antibodies to the U1 RNP peptides A, B'/B, C, D, and 70 kd appeared. RESULTS: One hundred sixty-three patients with serial samples were identified in whom antibodies to at least one U1 RNP peptide initially were not present but later appeared. The first RNP antibodies to appear were most often directed against the 70 kd and B'/B peptides (P < 0.01). Antibodies to the A and C peptides usually developed after other RNP peptide antibodies, and antibodies to D often emerged only after immunity to multiple other U1 RNP proteins had appeared. B'/B, but not 70 kd, was a frequent early target of spreading after initial immunity to other RNP peptides. CONCLUSION: Orderly patterns of emergence of U1 RNP peptide antibodies appear to exist in humans. Two peptides, 70 kd and B'/B, show characteristics of early immunogens in the development of human RNP immunity.

Antibodies↗
PubMed2000

Autoantibody recognition of distinctly modified forms of the U1-70-kd antigen is associated with different clinical disease manifestations.

OBJECTIVE: To examine whether autoantibody recognition of modified forms of the U1-70-kd RNP antigen correlates with manifestations of rheumatic disease. METHODS: Blinded to clinical disease manifestations, sera from 27 rheumatic disease patients with U1-70-kd antibodies were used to immunoblot control, apoptotic, and oxidatively modified HeLa cell lysates. Using densitometry, recognition of antigen fragments was quantitated. The presence or absence of 1) lupus skin disease and 2) Raynaud's phenomenon (RP) was determined for each patient by chart review. The ability of patient sera to recognize the different fragments was compared for patients with and without skin disease and with and without RP. RESULTS: Patients with lupus skin disease had higher recognition of apoptotic U1-70 kd than did patients without skin disease (mean +/- SD fragment recognition index [FRI] 1.35 +/- 0.57 versus 0.95 +/- 0.25; P < 0.024, by Student's t-test). Patients with RP had higher recognition of oxidatively modified U1-70 kd than did patients without RP (mean +/- SD FRI 0.95 +/- 0.80 versus 0.24 +/- 0.22; P < 0.048). CONCLUSION: Recognition of apoptotically and oxidatively modified forms of the U1-70-kd autoantigen are associated with distinct clinical rheumatic disease manifestations. This finding provides in vivo evidence for the hypothesis that immune recognition of modified forms of self antigens may be relevant to the pathogenesis of systemic rheumatic diseases. Understanding the antigenic modifications to which patients react may help predict the expression of rheumatic syndromes.

Antigens↗
PubMed2000

Mixed connective tissue disease.

A defining feature of mixed connective tissue disease (MCTD) is the presence of antibodies against the U1-ribonucleoprotein (RNP) complex, but other autoantibodies in MCTD have recently been described. Research has also further elucidated the immune responses directed against U1-RNP in humans and in murine models of disease. Hypotheses implicating modified self-antigens and/or infectious agents in the pathogenesis of MCTD have been advanced. Links between the immunologic and clinical phenomena in MCTD are emerging. Longitudinal study of patients with MCTD highlights the impact of pulmonary hypertension on disease outcome.

Animals↗
PubMed2000

Immunization with a bacterial ATP-binding cassette transporter fragment suppresses autoimmunity and prolongs survival in MRL/lpr lupus-prone mice.

The present study was undertaken to better define the role of the U1 70 kDa antigen in a spontaneous murine model of systemic lupus erythematosus (SLE) by testing whether immunization with the U1 70 kDa polypeptide could alter the production of antibodies against U1 70 kDa or against other small nuclear ribonucleoproteins (snRNP), modify disease expression or alter survival. We found that, while immunization with a U1 70 kDa derived fusion protein (70 KFP) tended to delay the development of anti-snRNP antibodies in the sera of MRL/lpr mice, it had no effect on autoimmune-mediated renal disease or survival. Unexpectedly, it was found that MRL/lpr mice immunized with a 367 amino acid fragment of a bacterial ATP-binding cassette transporter, MFP, had prolonged survival compared to saline injection or U1 70 kDa immunization and that this was associated with a delay in the onset of SLE-like proliferative glomerulonephritis. This is the first study, to our knowledge, in which a bacterial ATP-binding cassette transporter was shown to be beneficial in treating a murine model of SLE. We report that MFP significantly prolonged longevity in the MRL/lpr murine model of SLE compared to saline injection or 70 KFP immunization and that improved survival was associated with a delay in the onset of SLE-like glomerulonephritis.

Albuminuria↗
PubMed1999

Induction of primary human CD8+ T lymphocyte responses in vitro using dendritic cells.

The ability of two different human professional APCs, specifically macrophages (Mphi) and dendritic cells (DC), to stimulate primary responses in human CD8+ T lymphocytes was examined using both allogeneic and Ag-pulsed autologous APCs. CTL responses in CD8+ T lymphocytes isolated from HIV-uninfected donors were evaluated against six different HIV epitopes that are restricted by four different HLA alleles using autologous human PBMC-derived Mphi and DCs for primary stimulation. In a side-by-side experiment, immature DCs, but not Mphi, were able to prime a CTL response against the B14-restricted p24gag 298-306 epitope; mature DCs were also able to prime a response against this epitope. In addition, DCs were capable of priming CD8+ CTL responses against the B8-restricted p24gag 259-267 epitope. In contrast, Mphi were unable to prime strong CTL responses against other epitopes. Since the Ag-specific cytotoxic responses required subsequent rounds of restimulation before they could be detected, the ability of the allogeneic Mphi and DCs to directly prime CD8+ T lymphocyte responses without subsequent restimulation was examined. Similar to the aforementioned peptide-specific results, DCs were more efficient than Mphi in priming both allogeneic proliferative and cytotoxic responses in human CD8+ T lymphocytes. Collectively, these results promote an enhanced status for DCs in the primary stimulation of human CD8+ T lymphocytes.

CD8-Positive T-Lymphocytes↗
PubMed1999

T cell receptor beta-chain third complementarity-determining region gene usage is highly restricted among Sm-B autoantigen-specific human T cell clones derived from patients with connective tissue disease.

OBJECTIVE: To determine the structure of T cell receptors (TCR) used by Sm-B-reactive human T cell clones, to map T cell epitopes on the Sm-B autoantigen, and to determine the HLA restriction element used in the recognition of Sm-B by T cells. METHODS: Sm-B-reactive T cell clones were generated from patients with connective tissue disease by using either a recombinant fusion protein or synthetic peptides. The TCR structure was defined with the use of polymerase chain reaction and DNA sequencing. Synthetic peptides were used to map T cell epitopes on Sm-B. HLA restriction element usage was defined by using monoclonal antibody blocking. RESULTS: Usage of the TCR third complementarity-determining region (CDR3) was highly restricted among Sm-B autoantigen-specific human T cell clones. Only amino acids 48-96 of the Sm-B2 autoantigen were recognized by T cells, and this occurred in the context of HLA-DR. CONCLUSION: TCR CDR3 gene usage is highly conserved by Sm-B autoantigen-specific T cell clones, and this appears to be related to the recognition of a limited number of T cell epitopes on the Sm-B autoantigen presented in the context of HLA-DR.

Amino Acid Sequence↗
PubMed1999

Long-term outcome in mixed connective tissue disease: longitudinal clinical and serologic findings.

OBJECTIVE: To determine the long-term clinical and immunologic outcomes in a well-characterized cohort of 47 patients with mixed connective tissue disease (MCTD), including reactivity with U small nuclear RNP (snRNP) polypeptides. METHODS: Patients were followed up over a period of 3-29 years with immunogenetic and systematic clinical and serologic analysis. Sera were analyzed for reactivity with snRNP polypeptides U1-70 kd, A, C, B/B', and D, for anti-U1 RNA, and for anticardiolipin antibodies (aCL). RESULTS: The typical core clinical features of MCTD tended to develop over time; features of inflammation as well as Raynaud's phenomenon and esophageal hypomotility diminished, while pulmonary hypertension, pulmonary dysfunction, and central nervous system disease persisted, following treatment. A favorable outcome was observed in 62% of patients; 38% had continued active disease or had died, with death associated with pulmonary hypertension and aCL. All patients had autoantibodies to the U1-70 kd polypeptide of snRNP, and most were positive for anti-U1 RNA. An orderly progression of intramolecular spreading of autoantibody reactivity against snRNP polypeptides was observed, as was the novel finding of "epitope contraction" followed by disappearance of anti-snRNP autoantibodies during prolonged remission. CONCLUSION: These patients demonstrated the typical immunogenetic, clinical, and serologic findings of MCTD, and the condition rarely evolved into systemic lupus erythematosus or systemic sclerosis. The majority of patients had favorable outcomes, with pulmonary hypertension being the most frequent disease-associated cause of death. Intramolecular spreading of autoantibody reactivity against snRNP polypeptides was observed, followed by "epitope contraction" and ultimate disappearance of anti-snRNP autoantibodies during prolonged disease remission.

Autoantibodies↗
PubMed1999

Comparison of 18S and ITS-1 rDNA sequences of selected geographic isolates of Myxobolus cerebralis.

Myxobolus cerebralis, the myxosporean parasite-causing salmonid whirling disease, was first reported among rainbow trout (Oncorhynchus mykiss) in Germany in 1903. The parasite was reported for the first time in North America in 1958 among hatchery-reared trout in the eastern USA, presumably arriving with frozen trout shipments from Europe. A comparison of 18S and ITS-1 ribosomal DNA sequences was conducted to identify potential strain differences between selected geographic isolates of this parasite from Europe and North America. Only fourteen of 1700 base pairs were different in the 18S rRNA gene from isolates obtained from California and West Virginia in the USA, and the Federal German Republic. No evidence for strain differences was obtained from ITS-1 sequences that were found to be identical among all parasite isolates. This finding is consistent with the hypothesis that the parasite was recently introduced to the USA from Europe.

Animals↗
PubMed1999

Analysis of T cell receptors specific for U1-70kD small nuclear ribonucleoprotein autoantigen: the alpha chain complementarity determining region three is highly conserved among connective tissue disease patients.

The U1-70kD autoantigen is a major target of B cell responses in patients with connective tissue diseases (CTD). T cell responses are important in the pathogenesis of CTD, however little is known about autoantigen-specific T cells in these diseases. We have recently proven that U1-70kD-reactive human T cells exist. To further characterize these autoreactive T cells, U1-70kD-reactive T cell clones have been generated from patients with CTD using either a recombinant fusion protein or synthetic peptides spanning the U1-70kD polypeptide. T cell receptors (TCR) isolated from the U1-70kD-reactive T cell clones were sequenced and the third complementarity-determining region (CDR3) compared to determine if a common motif was present. mAb blocking of antigen-induced proliferation was done to determine the HLA restriction element used in recognition of the U1-70kD autoantigen by T cells. The results presented here indicate that TCRAV CDR3 usage is highly restricted among U1-70kD autoantigen-specific human T cells clones derived from CTD patients with distinctive structural features. Furthermore, the recognition of the U1-70kD autoantigen occurs in the context of HLA-DR.

Amino Acid Sequence↗
PubMed1998

Abnormal early TCR/CD3-mediated signaling events of a snRNP-autoreactive lupus T cell clone.

Multiple immunoregulatory abnormalities characterize systemic lupus erythematosus. Abnormalities of the antigen receptor-mediated early signal transduction biochemical events underscore the diverse cellular aberrations. Fresh peripheral T and B cells and T cell lines from patients with systemic lupus erythematosus display increased Ca2+ responses that are preceded by enhanced antigen receptor-initiated cytosolic protein tyrosine phosphorylation. To further dissect the aberrant signaling events of lupus T cells we studied the early anti-CD3 mAb-induced signaling events in autoantigen-specific T cells from lupus patients. We report herein that a lupus snRNP-specific T cell clone, but not other T cells, displays increased Ca2+ fluxes and enhanced production of tyrosine-phosphorylated proteins following TCR/CD3 stimulation.

Antibodies, Monoclonal↗
PubMed1998

Analysis of autoantibodies against RNA polymerases using immunoaffinity-purifed RNA polymerase I, II, and III antigen in an enzyme-linked immunosorbent assay.

Autoantibodies against RNA polymerases (RNAP) have been reported to occur in patients with a wide variety of connective tissue diseases (CTD), including systemic sclerosis (SSc), systemic lupus erythematosus (SLE), and mixed connective tissue disease (MCTD). The frequency of anti-RNAP antibodies has been reported to vary widely between different CTD diseases in studies examining different patient populations. Furthermore, these studies have been limited by the fact that methods have not previously been available for detecting antibodies against RNAP which are both rapid and quantitative. We have developed an enzyme-linked immunosorbent assay (ELISA) for rapidly quantitating antibodies against RNAP I, II, and III. We have utilized both the ELISA and the immunoprecipitation of 35S-labeled HeLa cells to analyze sera from a large cohort of well-characterized Caucasian CTD patients for the presence of anti-RNAP antibodies. We found excellent concordance for the presence of anti-RNAP antibodies using immunoprecipitation and ELISA. Anti-RNAP antibodies occurred predominantly among female patients with the diffuse form of SSc and were detected in 8/36 (22%) of Caucasian patients with diffuse SSc and 1/53 (2%) with limited SSc. Anti-RNAP antibodies occurred in 1/42 (2%) of patients with SLE. Anti-RNAP antibodies did not occur in MCTD (0/49). Antibodies against RNAP were rare among antinucleolar-reactive sera, occurring in only 3/200 (1.5%). The RNAP ELISA provides a validated method which can be rapidly utilized in a clinical diagnostic laboratory setting to identify SSc patients who are at risk for developing diffuse SSc with multiorgan involvement and hypertensive renal crisis.

Adult↗
PubMed1997

Mycoplasma infection and rheumatoid arthritis: analysis of their relationship using immunoblotting and an ultrasensitive polymerase chain reaction detection method.

OBJECTIVE: To examine the relationship between infection with Mycoplasma and the development of rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA). METHODS: Immunoblotting of patient synovial fluid and sera on detergent-phase membrane protein extracts of various Mycoplasma species was carried out to learn whether patients exhibited serologic evidence of previous exposure to mycoplasmas. Moreover, an ultrasensitive polymerase chain reaction (PCR) method was developed for assessing whether Mycoplasma DNA could be detected in synovial fluid from patients and controls. RESULTS: Immunoblotting provided serologic evidence of previous Mycoplasma exposure in patients and controls. The genus-specific PCR detected known human Mycoplasma species and could reliably detect <5 copies of Mycoplasma hominis, Mycoplasma fermentans, or a molecular mimic control in synovial fluid. Repeat testing revealed no evidence of Mycoplasma DNA in patient synovial samples. CONCLUSION: This study provided serologic evidence suggesting that, while previous exposure to Mycoplasma was common, there was no detectable persistence of Mycoplasma DNA in the synovial fluid or tissue of patients with RA or JRA.

Adult↗
PubMed1997

Analysis of human T cell and B cell responses against U small nuclear ribonucleoprotein 70-kd, B, and D polypeptides among patients with systemic lupus erythematosus and mixed connective tissue disease.

OBJECTIVE: To analyze T and B cell reactivity with U small nuclear RNP (snRNP) 70-kd, B, and D polypeptides among patients with connective tissue disease (CTD) and to examine the functional characteristics of snRNP-reactive T cell clones. METHODS: We used an snRNP enzyme-linked immunosorbent assay and immunoblotting to characterize antibodies in patients' sera. We used human recombinant fusion proteins 70 kd, B, and D to stimulate and clone snRNP-reactive T cells from CTD patients. We analyzed the cell surface phenotype, antigenic specificity, and cytokine profiles of T cell clones. RESULTS: Patients showed T cell responsiveness to snRNP polypeptides that paralleled their autoantibody reactivities. A total of 256 clones were generated, and clones were identified which were specific for the 70-kd, B, or D polypeptides. Clones expressed a T helper cell phenotype, and were found to produce substantial quantities of both interleukin-4 (IL-4) and interferon-gamma, and lesser quantities of IL-2 and IL-6. CONCLUSION: These results show that CTD patients have clonable circulating snRNP-reactive T cells that parallel the specificity of snRNP-reactive antibodies in their sera. The snRNP-reactive T cells exhibit a helper cell phenotype and produce cytokines which are important in B cell help and differentiation.

Adult↗
PubMed1997

The importance of enhancing self-efficacy in rheumatoid arthritis.

OBJECTIVE: To examine relationships among changes in self-efficacy and changes in other clinically relevant outcome measures. METHOD: Subjects (n = 44) were participants in a prospective, randomized stress-management study followed over 15 months. Outcome measures included self-efficacy, depression, pain, health status, and disease activity. RESULTS: Correlational analyses revealed significant associations between changes in self-efficacy (particularly total self-efficacy) and changes in selected measures of depression, pain, health status, and disease activity. The observed associations were not due to changes in medication regimen or to nonadherence to the stress-management program. CONCLUSIONS: Evidence is provided that induced changes in self-efficacy following a stress-management program were significantly related to other clinically important outcome measures.

Activities of Daily Living↗