Biomedical subjects

P E Lipsky

Publications and source records attributed to P E Lipsky.

At least 19 recordsLinked to original sources

PubMed2006

The Met66 allele of the functional Val66Met polymorphism in the brain-derived neurotrophic factor gene confers protection against neurocognitive dysfunction in systemic lupus erythematosus.

BACKGROUND: A common functional polymorphism of the brain-derived neurotrophic factor gene (BDNF Val66Met) was previously associated with diminished episodic memory performance in healthy people. As cognitive function is commonly impaired in patients with systemic lupus erythematosus (SLE), the association of the BDNF Val66Met with neurocognitive function was studied. OBJECTIVE: To study the association of the BDNF Val66Met with neurocognitive function in a cohort of patients with SLE. METHODS: Cognitive function was assessed in 59 patients with SLE with no previous or current central nervous system involvement. Cognitive tests were grouped into five domains (memory, attention/executive function, visuospatial skills, motor function and psychomotor speed) and used to obtain domain Z scores, reflecting the difference between averaged scores of performance on individual tests and published norms in each domain. Genotyping was carried out using a 5'-nuclease assay with 99.9% accuracy. Unpaired t test was used to assess the relationship between genotypes and cognitive function, whereas the effect of possible confounders was assessed in a multivariate analysis. RESULTS: Patients carrying the Met66 allele scored significantly higher on psychomotor, attention/executive and motor function tests, resulting in significantly higher domain Z scores for the psychomotor (p = 0.005) and motor (p = 0.002) domains. CONCLUSIONS: The BDNF Met66 allele was associated with better cognitive functioning in the psychomotor and motor domains, even after controlling for differences in ethnicity, sex, depression status and prednisone treatment. These data suggest that the BDNF Met66 allele confers protection against the decline of motor and psychomotor cognitive functions in patients with longstanding SLE.

Adult↗

PubMed2006

Dissemination of a Sjögren's syndrome-associated extranodal marginal-zone B cell lymphoma: circulating lymphoma cells and invariant mutation pattern of nodal Ig heavy- and light-chain variable-region gene rearrangements.

OBJECTIVE: Both the genesis and outgrowth of extranodal marginal-zone B cell lymphomas (MZLs) of the mucosa-associated lymphoid tissue (MALT) type are generally thought to represent antigen-driven processes. We undertook this study to analyze lymphoma progression and dissemination outside of the MALT-type lesions. METHODS: Histopathologic and Ig heavy- and light-chain variable-region gene (V(H/L)) analyses were performed in sequential tissue samples from a patient with primary Sjögren's syndrome (SS) with glandular (parotid) manifestations and subsequent nodal dissemination of a low-grade MZL. RESULTS: This MZL expressed a CD20+,CD27+,sIgM/kappa+,IgD-,CD5-,CD10-,Bcl-6-,CD23-,p53-,p21-,MDM2- phenotype and mutated V(H)1-69/D2-21/J(H)4alpha-V(kappa)A27/J(kappa)2 Ig rearrangements. Notably, circulating lymphoma cells from the parotid glands occurred transiently in the patient's blood, as detected by single-cell polymerase chain reaction. In addition, 2 minor B cell clones (clones 2 and 3, with V(H)3-07/D3-22/J(H)3b-V(lambda)3L/J(lambda)2/3 and V(H)3-64/D3-03/J(H)2-V(kappa)A19/J(kappa)2 rearrangements, respectively) were also detected in the parotid glands and blood, and 1 of these (clone 2) was also detected in the lymph nodes. Ig V(H/L) analyses revealed ongoing (antigen-driven) mutations of the glandular lymphoma rearrangements, but an invariant mutation pattern of their nodal counterparts. CONCLUSION: These data indicate coexpansion and transient (re)circulation of the lymphoma clone and 2 additional glandular B cell clones in a primary SS-associated extranodal MZL. Combined histologic and molecular features of the nodal lymphoma subclone reflect a process of "follicular colonization" that eventually froze the mutation machinery after accumulation of additional (antigen-driven) Ig V(H/L) mutations.

Female↗

PubMed2006

T cell activation as starter and motor of rheumatic inflammation.

Rheumatic inflammation is driven by sustained specific immunity against self-antigens, resulting in local inflammation and cellular infiltration and, subsequently, in tissue damage. Although the specific autoantigen(s) eliciting the detrimental immune reactions in rheumatic diseases have rarely been defined, it has become clear that the mechanisms resulting in the destruction of tissue and the loss of organ function during the course of the diseases are essentially the same as in protective immunity against invasive microorganisms. Of fundamental importance in initiating, controlling, and driving these specific immune responses are CD4 T cells. Currently available data provide compelling evidence for a major role of CD4 T cells in the initiation and perpetuation of chronic rheumatic inflammation. Consequently, T cell-directed therapies have been employed with substantial clinical success in the treatment of rheumatic diseases. Here, we review current knowledge based on which CD4 T cells can be implicated as the motor of rheumatic inflammation.

Animals↗

PubMed2006

Signalling pathways in B cells: implications for autoimmunity.

Following investigations of the pathogenic role of autoantibodies in rheumatic diseases, preclinical and clinical studies suggest a more central role of B cells in the maintenance of the disease process beyond just being precursors of (auto)antibody-producing plasma cells. Detailed analyses have implicated a number of surface molecules and subsequent downstream signalling pathways in the regulation of the events induced by BCR engagement. In this review, we discuss the potential role of molecules involved in altered B cell longevity, especially molecules involved in apoptosis (bcl-2, bcl-x, mutations in the Fas/Fas-L pathway), as well as molecules that might alter activation thresholds of B cells (CD19, CD21, CD22, lyn, SHP, SHIP-1) in the development of autoimmunity. Although focused on intrinsic B cell abnormalities, the complexity of interactions of B cells with other immune cells also makes it possible that increased B cell activation can be induced by distortions in the interaction with other cells. Further delineation of these alterations of B cell function in autoimmune conditions will allow development of more precise B cell-directed therapies beyond drastic B cell depletion, with the potential to improve the risk-benefit ratio of the treatments of autoimmune diseases.

Animals↗

PubMed2005

Analysis of RAG expression by peripheral blood CD5+ and CD5- B cells of patients with childhood systemic lupus erythematosus.

BACKGROUND: The assembly of immunoglobulin genes during B cell development in the bone marrow is dependent on the expression of recombination activating genes (RAG) 1 and 2. Recently, RAG expression in peripheral blood IgD+ B cells outside the bone marrow has been demonstrated and is associated with the development of autoimmune diseases. OBJECTIVE: To investigate RAG expression in the CD5+ or CD5- IgD+ B cell compartment in childhood systemic lupus erythematosus (SLE). METHODS: Using a combination of flow cytometric cell sorting and reverse transcriptase polymerase chain reaction analysis of cDNA libraries generated from individual cells, the expression of RAG, VpreB, and CD154 mRNA by individual peripheral blood B cells of three paediatric SLE patients was examined in detail. RESULTS: While only one patient had a significantly increased frequency of RAG+ B cells in the CD5- B cell population, all patients showed higher frequencies of RAG+ B cells in the CD5+IgD+ B cell population. The frequency of RAG+ IgD+CD5+/- B cells was reduced during intravenous cyclophosphamide treatment. In healthy age matched children, RAG expressing IgD+ B cells were hardly detectable. Coexpression of RAG and VpreB or CD154 mRNA could only be found in SLE B cells. CONCLUSIONS: RAG expression in peripheral blood B cells of SLE patients is particularly increased in the IgD+CD5+ B cell population. CD5+ and CD5- B cells in SLE have the potential to undergo receptor revision leading to the generation of high affinity pathogenic autoantibodies.

Adolescent↗

PubMed2005

Evidence of radiographic benefit of treatment with infliximab plus methotrexate in rheumatoid arthritis patients who had no clinical improvement: a detailed subanalysis of data from the anti-tumor necrosis factor trial in rheumatoid arthritis with concomitant therapy study.

OBJECTIVE: To assess the relationship between inflammation and joint destruction in rheumatoid arthritis (RA) patients who have not responded clinically to treatment. METHODS: Changes from baseline to week 54 in clinical variables and measures of radiographic progression were compared between patients who received infliximab (3 mg/kg or 10 mg/kg every 4 or 8 weeks) plus methotrexate (MTX) and those who received MTX plus placebo in the Anti-Tumor Necrosis Factor Trial in RA with Concomitant Therapy trial. RESULTS: At week 54, patients who did not show 20% improvement by American College of Rheumatology criteria (ACR20 nonresponders) while receiving infliximab plus MTX exhibited mild but statistically significant improvement in clinical variables, including the 28-joint Disease Activity Score (DAS28) (P < 0.001), tender joint count (P = 0.014), swollen joint count (P < 0.001), and C-reactive protein (CRP) level (P < 0.001). Whereas the clinical and CRP changes among ACR20 nonresponders to infliximab plus MTX were small and much lower than among ACR20 responders to this treatment, radiographic progression among ACR20 nonresponders to infliximab plus MTX was significantly inhibited (P < 0.001) compared with ACR20 nonresponders to MTX plus placebo. Radiographic progression was much greater in patients receiving MTX plus placebo than in patients receiving infliximab plus MTX, irrespective of ACR response status (mean change in modified Sharp/van der Heijde score 6.0 in ACR20 responders and 7.2 in ACR20 nonresponders in the MTX plus placebo-treated group, versus 0.1 in ACR20 responders and 1.2 in ACR20 nonresponders in the infliximab plus MTX-treated group). Furthermore, among patients who were ACR20 nonresponders through week 54, patients who were DAS nonresponders at weeks 30 and 54, and patients without any improvement in individual clinical variables, those receiving infliximab plus MTX still demonstrated inhibition of structural damage that was statistically significant compared with inhibition in patients who received MTX plus placebo (P < 0.05 to P < 0.001). CONCLUSION: Even in patients without clinical improvement, treatment with infliximab plus MTX provided significant benefit with regard to the destructive process, suggesting that in such patients these 2 measures of disease are dissociated.

Antibodies, Monoclonal↗

PubMed2005

Molecular basis of immunoglobulin variable region gene usage in systemic autoimmunity.

This review focuses on the immunoglobulin variable region (IgV) chain gene usage in patients with systemic autoimmune diseases, with particular emphasis on systemic lupus erythematosus (SLE), a condition known to be associated with the production of a number of characteristic autoantibodies as an abnormality. The IgV repertoire is shaped by a variety of molecular and selective influences that are difficult to distinguish. Studies of IgV gene rearrangement by PCR of individual B cells permitted insight in the differential impact of these processes, including somatic hypermutation and indications of receptor editing/revision. Although the majority of current data indicate that there is no major molecular abnormality in V(D)J recombination in SLE patients, abnormalities in subsequent events, such as the degree of receptor editing and somatic hypermutation, and positive and negative selection fundamentally alter the composition of the peripheral B-cell repertoire. Identification of the mechanisms that influence the IgV gene and B-cell repertoire may allow new therapeutic approaches in autoimmunity.

Autoantibodies↗

PubMed2005

Chronic non-bacterial osteomyelitis in children.

BACKGROUND: Chronic recurrent multifocal osteomyelitis (CRMO) in children is a chronic non-suppurative inflammation involving multiple sites. Some children affected by chronic non-bacterial osteomyelitis (CNO) do not have multiple lesions or a recurrent course. OBJECTIVE: To characterise the long term outcome of children with the full spectrum of CNO. METHODS: 30 children diagnosed with CNO were followed up for a mean of 5.6 years and their disease assessed using a clinical score, multiple imaging, and a diagnostic biopsy, including extensive microbial analysis. RESULTS: 9 patients had unifocal non-relapsing disease, 3 unifocal lesions with relapses, 9 multifocal lesions without relapses, and 9 multifocal lesions with relapses (CRMO). Granulocytes were present significantly more often in CRMO than in unifocal and non-recurrent lesions. Pustulosis was more common in multifocal cases regardless of recurrence. Mean duration of treatment in 15 children with a single occurrence was 9.2 months. Naproxen treatment was generally effective. Naproxen treatment in 12 patients with relapses lasted 25 months. However, 7 of these were not effectively treated with naproxen alone. Five were treated with oral glucocorticoids for 27 days in addition to naproxen, which induced remission in four, lasting for at least 1.5 years. Longitudinal growth of affected bones was not altered, except for the development of hyperostosis. CONCLUSION: CNO is a spectrum of inflammatory conditions, with CRMO being the most severe. Most children with CNO have a favourable outcome of the disease. Oral glucocorticoids may be necessary in severe recurrent cases.

Adolescent↗

PubMed2004

Association between baseline radiographic damage and improvement in physical function after treatment of patients with rheumatoid arthritis.

OBJECTIVES: To identify factors associated with poor physical function in rheumatoid arthritis and to assess whether baseline joint damage has an impact on improvement in physical function during infliximab treatment. METHODS: 428 patients with active rheumatoid arthritis despite methotrexate treatment received methotrexate alone or with infliximab (3 mg/kg or 10 mg/kg every four or eight weeks) for 54 weeks (the ATTRACT trial). Data on clinical outcomes and physical function (assessed by the health assessment questionnaire (HAQ)) were collected. Structural damage was assessed using the van der Heijde modification of the Sharp score. Odds ratios (OR) for factors associated with severe functional disability (HAQ > or =2.0) at baseline were estimated using multiple logistic regression analyses, and baseline factors related to the change in physical function after treatment at week 54 were determined. RESULTS: Baseline radiographic scores were correlated with baseline HAQ scores. After adjustment for demographic characteristics in the logistic regression model, baseline disease activity scores, radiological joint damage, fatigue, and morning stiffness were found to be associated with severe functional disability (HAQ >2.0), with OR values of 2.00 (1.53 to 2.63), 1.82 (1.15 to 2.87), 1.19 (1.05 to 1.34), and 1.07 (1.01 to 1.13), respectively. In multiple linear regression analysis, physical disability, joint damage, and fatigue at baseline were correlated with less improvement in physical function after treatment. Infliximab treatment was associated with greater improvement in physical function. CONCLUSIONS: Greater joint damage at baseline was associated with poorer physical function at baseline and less improvement in physical function after treatment, underlining the importance of early intervention to slow the progression of joint destruction.

Antibodies, Monoclonal↗

PubMed2004

Sustained improvement over two years in physical function, structural damage, and signs and symptoms among patients with rheumatoid arthritis treated with infliximab and methotrexate.

OBJECTIVE: To evaluate the efficacy and safety of repeated administration of infliximab plus methotrexate (MTX) over a 2-year period in patients with rheumatoid arthritis (RA) who previously experienced an incomplete response to MTX. METHODS: Four hundred twenty-eight patients were randomly assigned to receive MTX plus placebo or infliximab at a dose of 3 or 10 mg/kg plus MTX for 54 weeks, with an additional year of followup. The protocol was later amended to allow for continued treatment during the second year. Of 259 patients who entered the second year of treatment, 216 continued to receive infliximab plus MTX for 102 weeks. Ninety-four of these 259 patients experienced a gap in therapy of >8 weeks before continuing therapy. Infusions were administered at weeks 0, 2, and 6, followed by treatment every 4 weeks or every 8 weeks (alternating with placebo infusions in the interim 4-week visits) at a dose of 3 or 10 mg/kg for a total of 102 weeks (including the gap in therapy). For safety and efficacy assessments, data on the patients who were randomized to receive treatment, irrespective of whether treatment was administered for 102 weeks, were evaluated using all actual observations available. The efficacy measures included the Health Assessment Questionnaire (HAQ) (physical function), Short Form 36 health survey (SF-36) (health-related quality of life), total radiographic scores (structural damage), and the American College of Rheumatology 20% improvement criteria (ACR20) (signs and symptoms). RESULTS: The infliximab plus MTX regimens resulted in significantly greater improvement in HAQ scores (P < or = 0.006) and SF-36 physical component summary scores (P < or = 0.011) compared with the MTX-only group. There also was stability in the SF-36 mental component summary score among patients who received the infliximab plus MTX regimens. Median changes from baseline to week 102 in the total radiographic score were 4.25 for patients who received the MTX-only regimen and 0.50 for patients who received the infliximab plus MTX regimen. The proportion of patients achieving an ACR20 response at week 102 varied from 40% to 48% for the infliximab plus MTX groups compared with 16% for the MTX-only group. CONCLUSION: Throughout 102 weeks of therapy, infliximab plus MTX provided significant, clinically relevant improvement in physical function and quality of life, accompanied by inhibition of progressive joint damage and sustained improvement in the signs and symptoms of RA among patients who previously had an incomplete response to MTX alone.

Antibodies, Monoclonal↗

PubMed2004

Triptolide, an active component of the Chinese herbal remedy Tripterygium wilfordii Hook F, inhibits production of nitric oxide by decreasing inducible nitric oxide synthase gene transcription.

OBJECTIVE: The ethyl acetate (EA) extract of Tripterygium wilfordii Hook F (TWHF) and its major active component, triptolide, have been reported to be effective in the treatment of rheumatoid arthritis and other autoimmune inflammatory diseases. Nitric oxide (NO) has been recognized as an important mediator of inflammation. This study was therefore undertaken to examine the effects of the EA extract and triptolide on the production of NO and inducible NO synthase (iNOS) gene expression and transcription in vivo and in vitro. METHODS: Peritoneal macrophages from C57BL/6J mice treated orally with the EA extract of TWHF were assayed for NO production and iNOS messenger RNA (mRNA) expression by reverse transcriptase-polymerase chain reaction. The murine fibroblast cell line NIH3T3 was also assessed for NO production and iNOS mRNA expression, as well as for iNOS promoter activation, Oct-1 nuclear binding capacity, and Oct-1 protein content by transient transfection, electrophoretic mobility shift assay, and immunoblotting, respectively. RESULTS: NO production and iNOS mRNA expression by macrophages from C57BL/6J mice immunized with trinitrophenyl-bovine serum albumin in Freund's complete adjuvant were significantly inhibited by oral administration of the EA extract (52.3% and 59.8% of control, respectively, at one-eighth of the dose that is lethal for 50% of the animals [LD(50)] and 21.0% and 38.1% of control, respectively, at one-fourth the LD(50)). Moreover, the EA extract and triptolide significantly inhibited NO production in vitro in activated peritoneal macrophages, which reflected a decreased level of iNOS mRNA. Finally, triptolide inhibited promoter activity of the iNOS gene and induction of the activity of the regulator of iNOS transcription, Oct-1. CONCLUSION: The EA extract of TWHF and triptolide inhibit transcription of the iNOS gene. This may contribute to the antiinflammatory effects of this traditional herbal remedy.

Animals↗

PubMed2004

Infliximab in active early rheumatoid arthritis.

OBJECTIVE: To examine the impact of the combination of infliximab plus methotrexate (MTX) on the progression of structural damage in patients with early rheumatoid arthritis (RA). METHODS: Subanalyses were carried out on data for patients with early RA in the Anti-TNF Therapy in RA with Concomitant Therapy (ATTRACT) study, in which 428 patients with active RA despite MTX therapy received placebo with MTX (MTX-only) or infliximab 3 mg/kg or 10 mg/kg every (q) 4 or 8 weeks with MTX (infliximab plus MTX) for 102 weeks. Early RA was defined as disease duration of 3 years or less; 82 of the 428 patients (19%) met this definition. Structural damage was assessed with the modified van der Heijde-Sharp score. The changes from baseline to week 102 in total modified van der Heijde-Sharp score were compared between the infliximab plus MTX groups and the MTX-only group. RESULTS: The erosion and joint space narrowing scores from baseline to week 102 in the cohort of patients with early RA decreased significantly in each infliximab dose regimen compared with the MTX-only regimen. Consistent benefit was seen in the joints of both hands and feet. CONCLUSIONS: Infliximab combined with MTX inhibited the progression of structural damage in patients with early RA during the 2 year period of treatment. Early intervention with infliximab in patients with active RA despite MTX therapy may provide long term benefits by preventing radiographic progression and preserving joint integrity.

Acute Disease↗

PubMed2004

Correlation of circulating CD27high plasma cells and disease activity in systemic lupus erythematosus.

CD27 is a useful marker in assessing the number of circulating B cells and B cell subsets because it permits one step identification of the major B cell compartments, CD27- naïve and CD27+ memory B cells as well as CD27high plasma cells. Abnormalities in the distribution ofCD27+ B cell subsets are useful in assessing disease activity in patients with systemic lupus erythematosus (SLE). In particular, the frequency of CD27high plasma cells significantly correlates with lupus activity in both children and adults with SLE. Conventional immunosuppressive therapies affect the number of CD27- naïve B cells and CD27high plasma cells, but do not target CD27+ memory B cells. These results suggest that disease flares may relate to the retention of CD27+ memory B cells after conventional immunosuppressive therapy and that new therapies that target these cells specifically may offer new opportunities to induce remission in SLE.

B-Lymphocytes↗

PubMed2004

Rationale for interleukin-6 blockade in systemic lupus erythematosus.

Interleukin-6 (IL-6) is a pleiotropic cytokine with a wide range of biological activities that plays an important role in immune regulation and inflammation. Among other actions, it induces terminal differentiation of B lymphocytes into antibody-forming cells and the differentiation of T cells into effector cells. IL-6 also has multiple potent proinflammatory effects. An association between IL-6 and lupus was demonstrated in murine models of SLE and blocking IL-6 improved lupus in all models tested. Data from several studies suggest that IL-6 plays a critical role in the B cell hyperactivity and immunopathology of human SLE, and may have a direct role in mediating tissue damage. Based on these data, we propose that blocking the effect of IL-6 in humans may improve lupus by interacting with the autoinflammatory process both systemically and locally.

Animals↗

PubMed2003

Comparison of immunoglobulin heavy chain rearrangements between peripheral and glandular B cells in a patient with primary Sjögren's syndrome.

Myoepithelial sialadenitis (MESA) of the major salivary glands is a characteristic feature of primary Sjögren's syndrome (pSS). To delineate systemic and organ-specific influences on B cells in a patient with pSS and benign MESA, individual B cells were simultaneously obtained from the peripheral blood and inflamed parotid gland. Immunoglobulin variable heavy chain (VH) rearrangements in single sorted CD19+ B cells were subsequently amplified, sequenced and analysed. Despite the presence of two clonal expansions using VH1-08 and VH2-70 segments, respectively, the majority of glandular B cells were polyclonal, resembling the VH gene usage and mutational pattern of the corresponding blood population. However, striking differences were observed in the proportion of cells expressing mutated VH rearrangements (blood, 28.9% versus parotid, 80.4%; P < 0.0001). Moreover, the glandular productive VH rearrangements differed significantly from their blood counterparts by a higher mutational frequency (P < 0.0001), shorter CDR3 lengths (P = 0.001) and a less frequent usage of JH6 (P = 0.0292), indicating an accumulation of memory B cells in the inflamed parotid. Thus, both preferential influx/homing of memory B cells and local proliferation may contribute to the pattern of benign MESA in pSS. Notably, one of the glandular clonal rearrangements (using VH1-08) was also detected in the patient's peripheral repertoire.

Aged↗

PubMed2001

Stimulation of T-Cell activation by CXCL12/stromal cell derived factor-1 involves a G-protein mediated signaling pathway.

Recently we found that CXCL12/SDF-1 is a costimulator of peripheral CD4+ T cells. In this study, we report that CXCL12 alone induced expression of activation markers by peripheral CD4+ memory T cells and costimulated activation marker expression by anti-CD3 stimulated peripheral CD4+ naive and CD4+ memory T cells as well as by peripheral CD8+ T cells. The stimulation by CXCL12 was inhibited by Pertussis Toxin (PTX), but not by anti-CD25 mAb. CXCL12 also induced enhancement of IL-2 production and proliferation by anti-CD3 stimulated CD4+ memory T cells, but not by CD4+ naive T cells. PTX inhibited the enhancement of IL-2 production and proliferation, whereas anti-CD25 mAb inhibited proliferation, but not IL-2 production. Thus, CXCL12 upregulated T-cell activation, and a G-coupled protein mediated signaling pathway was necessary for stimulation of T cells by CXCL12.

Antigens, CD↗

PubMed2001

Perturbations in the impact of mutational activity on Vlambda genes in systemic lupus erythematosus.

To assess the impact of somatic hypermutation and selective influences on the Vlambda light chain repertoire in systemic lupus erythematosus (SLE), the frequency and pattern of mutations were analyzed in individual CD19+ B cells from a patient with previously undiagnosed SLE. The mutational frequency of nonproductive and productive rearrangements in the SLE patient was greater (3.1 x 10(-2) vs 3.4 x 10(-2), respectively) than that in normal B cells (1.2 x 10(-2) vs 2.0 x 10(-2), both P < 0.001). The frequencies of mutated rearrangements in both the nonproductive and productive repertoires were significantly higher in the patient with SLE than in normal subjects. Notably, there were no differences in the ratio of replacement to silent (R/S) mutations in the productive and nonproductive repertoires of the SLE patient, whereas the R/S ratio in the framework regions of productive rearrangements of normal subjects was reduced, consistent with active elimination of replacement mutations in this region. The pattern of mutations was abnormal in the SLE patient, with a significant increase in the frequency of G mutations in both the productive and nonproductive repertoires. As in normal subjects, however, mutations were found frequently in specific nucleotide motifs, the RGYW/WRCY sequences, accounting for 34% (nonproductive) and 46% (productive) of all mutations. These data are most consistent with the conclusion that in this SLE patient, the mutational activity was markedly greater than in normal subjects and exhibited some abnormal features. In addition, there was decreased subsequent positive or negative selection of mutations. The enhanced and abnormal mutational activity along with disturbances in selection may play a role in the emergence of autoreactivity in this patient with SLE.

B-Lymphocytes↗

PubMed2001

Antigen-independent Th2 cell differentiation by stimulation of CD28: regulation via IL-4 gene expression and mitogen-activated protein kinase activation.

To delineate the molecular mechanisms regulating Th2 cell differentiation, CD28-mediated generation of Th2 effectors was analyzed. In the absence of TCR ligation CD28 stimulation induced Th2 differentiation of memory but not of naive CD4(+) T cells, whereas costimulation via CD28 and the TCR enhanced Th2 differentiation from naive T cells but suppressed it from memory T cells. Stimulation of T cells via the CD28 pathway, therefore, provided critical signals facilitating Th2 cell differentiation. By comparing the responses to CD28 stimulation in memory and naive T cells and by using specific inhibitors, signaling pathways were defined that contributed to Th2 differentiation. CD28-induced Th2 differentiation required IL-4 stimulation and the activation of the mitogen-activated protein kinases p38 and extracellular signal-regulated kinases 1/2. CD28 engagement directly initiated IL-4 gene transcription in memory T cells and induced activation of phosphatidylinositol 3-kinase, p38, and c-Jun NH(2)-terminal kinase/stress-activated protein kinase pathways. Extracellular signal-regulated kinase phosphorylation that was necessary for Th2 differentiation, however, required stimulation by IL-2. These results indicate that optimal TCR-independent generation of Th2 effectors requires coordinate signaling via the CD28 and IL-2 pathways. TCR-independent generation of Th2 effectors might provide a mechanism to control Th1-dominated cellular inflammation.

Adult↗