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C M Weyand

Publications and source records attributed to C M Weyand.

At least 37 records · Page 2Linked to original sources
PubMed2000

Pathogenic principles in giant cell arteritis.

In giant cell arteritis, an immune insult in the vascular wall initiates a reaction in the artery that leads to structural changes, intimal hyperplasia, and luminal occlusion. The mechanisms triggering the immune stimulation are unknown; however, the process is strictly dependent on T cells that are found in the vicinity of the vasa vasorum in the adventitia and that produce interferon-gamma. The major effector cells in the artery are macrophages and giant cells that are ultimately under T-cell control but assume different functions depending on their location in the arterial wall. The response of the artery to the injury is maladaptive and includes mobilization and proliferation of smooth muscle cells in conjunction with matrix production and neoangionesis, resulting in the formation of a lumen-obstructive neointima. Heterogeneity in the immune insult and the resulting arterial response patterns correlate with variations in clinical disease.

Aldehyde Reductase↗
PubMed2000

Cell-cell interactions in synovitis. Interactions between T cells and B cells in rheumatoid arthritis.

In rheumatoid arthritis, T cells and B cells participate in the immune responses evolving in the synovial lesions. Interaction between T cells and B cells is probably antigen specific because complex microstructures typical of secondary lymphoid organs are generated. Differences between patients in forming follicles with germinal centers, T-cell-B-cell aggregates without germinal center reactions, or loosely organized T-cell-B-cell infiltrates might reflect the presence of different antigens or a heterogeneity in host response patterns to immune injury. Tertiary lymphoid microstructures in the rheumatoid lesions can enhance the sensitivity of antigen recognition, optimize the collaboration of immunoregulatory and effector cells, and support the interaction between the tissue site and the aberrant immune response. The molecular basis of lymphoid organogenesis studied in gene-targeted mice will provide clues to why the synovium is a preferred site for tertiary lymphoid tissue. B cells have a critical role in lymphoid organogenesis. Their contribution to synovial inflammation extends beyond antibody secretion and includes the activation and regulation of effector T cells.

Animals↗
PubMed2000

T cell homeostasis in patients with rheumatoid arthritis.

The immune system is equipped with an extremely large spectrum of structurally diverse receptors to recognize all potential antigens. This fundamental principle of receptor diversity is no longer upheld in patients with rheumatoid arthritis (RA), who have a marked contraction of the T cell receptor repertoire. In this study, the ability of RA patients to produce T cells and to maintain T cell homeostasis was examined. CD4 T cells containing T cell receptor rearrangement excision circles (TREC) were substantially reduced in RA patients; TREC levels in young adult patients matched those of controls 20 years older. Increased self-replication of T cells in RA was indicated by age-inappropriate erosion of telomeres in circulating T cells with almost complete attrition of telomeric reserves in patients 20-30 yr of age. The degree of telomere loss was not related to disease duration or the use of disease-modifying medication and was most pronounced in CD4(+)CD45RO(null) (naive) T cells. The loss of TREC-positive T cells could be a consequence of a primary defect in peripheral T cell homeostasis. Alternatively, RA patients may have impaired thymic function with the increased turnover of peripheral T cells being a secondary compensatory event.

Adolescent↗
PubMed2000

Killer cell activating receptors function as costimulatory molecules on CD4+CD28null T cells clonally expanded in rheumatoid arthritis.

Expansion of CD4+CD28null T cells is a characteristic finding in patients with rheumatoid arthritis. Despite lacking CD28 molecules, these unusual CD4 T cells undergo clonal proliferation and form large and long-lived clonal populations. They produce high levels of IFN-gamma, exhibit autoreactivity, and have cytolytic function. The mechanisms facilitating the expansion and longevity of CD4+CD28null T cell clones in vivo are unknown. Here, we report that CD4+CD28null, but not CD4+CD28+, T cells express MHC class I-recognizing receptors normally found on NK cells. CD4+CD28null T cells preferentially expressed killer cell activating receptors (KAR), often in the absence of killer cell inhibitory receptors. Cross-linking of KAR molecules enhanced the proliferative response to TCR-mediated stimulation, but not the cytolytic function of CD4+CD28null T cells, suggesting different signaling pathways in CD4 T cells and NK cells. Triggering of KAR signaling led to the phosphorylation of several cellular targets, although the pattern of phosphorylation differed from that induced by the TCR. Aberrant expression of KAR molecules in the absence of inhibitory receptors and in the appropriate HLA setting may lead to the clonal outgrowth of autoreactive CD4+CD28null T cells commonly seen in rheumatoid arthritis.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Monoclonal T-cell proliferation and plaque instability in acute coronary syndromes.

BACKGROUND: Unstable angina (UA) is associated with systemic inflammation and with expansion of interferon-gamma-producing T lymphocytes. The cause of T-cell activation and the precise role of activated T cells in plaque instability are not understood. METHODS AND RESULTS: Peripheral blood T cells from 34 patients with stable angina and 34 patients with UA were compared for the distribution of functional T-cell subsets by flow cytometric analysis. Clonality within the T-cell compartment was identified by T-cell receptor spectrotyping and subsequent sequencing. Tissue-infiltrating T cells were examined in extracts from coronary arteries containing stable or unstable plaque. The subset of CD4(+)CD28(null) T cells was expanded in patients with UA and infrequent in patients with stable angina (median frequencies: 10.8% versus 1.5%, P<0.001). CD4(+)CD28(null) T cells included a large monoclonal population, with 59 clonotypes isolated from 20 UA patients. T-cell clonotypes from different UA patients used antigen receptors with similar sequences. T-cell receptor sequences derived from monoclonal T-cell populations were detected in the culprit but not in the nonculprit lesion of a patient with fatal myocardial infarction. CONCLUSIONS: UA is associated with the emergence of monoclonal T-cell populations, analogous to monoclonal gammopathy of unknown significance. Shared T-cell receptor sequences in clonotypes of different patients implicate chronic stimulation by a common antigen, for example, persistent infection. The unstable plaque but not the stable plaque is invaded by clonally expanded T cells, suggesting a direct involvement of these lymphocytes in plaque disruption.

Acute Disease↗
PubMed2000

Association of MHC and rheumatoid arthritis. HLA polymorphisms in phenotypic variants of rheumatoid arthritis.

Genes in the human leukocyte antigen (HLA) region remain the most powerful disease risk genes in rheumatoid arthritis (RA). Several allelic variants of HLA-DRB1 genes have been associated with RA, supporting a role for T-cell receptor-HLA-antigen interactions in the pathologic process. Disease-associated HLA-DRB1 alleles are similar but not identical and certain allelic variants are preferentially enriched in patient populations with defined clinical characteristics. Also, a gene dosing effect of HLA-DRB1 alleles has been suggested by the accumulation of patients with two RA-associated alleles, especially in patient subsets with a severe disease course. Therefore, polymorphisms in HLA genes are being explored as tools to dissect the clinical heterogeneity of the rheumatoid syndrome. Besides HLA polymorphisms, other risk genes will be helpful in defining genotypic profiles correlating with disease phenotypes. One such phenotype is the type of synovial lesion generated by the patient. HLA genes in conjunction with other genetic determinants may predispose patients to a certain pathway of synovial inflammation. Also, patients may or may not develop extraarticular manifestations, which are critical in determining morbidity and mortality. HLA genes, complemented by other RA risk genes, are likely involved in shaping the T-cell repertoire, including the emergence of an unusual T-cell population characterized by the potential of vascular injury, such as seen in extraarticular RA.

Arthritis, Rheumatoid↗
PubMed2000

Central role of thrombospondin-1 in the activation and clonal expansion of inflammatory T cells.

Thrombospondin-1 (TSP) is a transiently expressed matricellular protein known to promote chemotaxis of leukocytes to inflammatory sites. However, TSP and its receptor CD36 are abundantly expressed in chronically inflamed tissues such as the rheumatoid synovium. Here, we show that TSP provides the costimulatory signal that is necessary for the activation of autoreactive T cells. Data presented reveal that TSP-mediated costimulation is achieved through its independent interaction with CD36 on APCs and with CD47 on T cells. We propose that a CD47-TSP-CD36 trimolecular complex is a novel costimulatory pathway that significantly decreases the threshold of T cell activation. Consistent with the paradigm that lesions in rheumatoid synovitis are sites of antigenic recognition, the characteristic focal expression of TSP on APCs such as macrophages and fibroblast-like synoviocytes suggest a central role of TSP in the expansion of tissue-infiltrating T cells.

Antigens, CD↗
PubMed2000

Treatment of giant cell arteritis: interleukin-6 as a biologic marker of disease activity.

OBJECTIVE: To determine the value of the erythrocyte sedimentation rate (ESR) and plasma interleukin-6 (IL-6) as biologic markers for monitoring disease activity in giant cell arteritis (GCA). METHODS: Twenty-five patients with biopsy-proven GCA were enrolled into a prospective treatment study. Therapy was initiated with prednisone, 60 mg/day, followed by a predetermined tapering schedule. Patients were monitored monthly for clinical signs of active vasculitis and laboratory parameters indicative of inflammation, including elevated ESR (>30 mm/hour) and elevated plasma IL-6 concentrations (>6.1 pg/ml). RESULTS: Upon initiation of corticosteroid treatment, clinical signs of GCA disappeared in all patients; however, 60% of the patients developed symptoms of recurrent disease, on 1 or more occasions, while the prednisone dosage was being reduced. These 31 disease flares diagnosed over 550 days were associated with symptoms of systemic inflammation but did not result in vascular complications. The ESR was elevated in 76% of the patients prior to initiation of treatment (median 65 mm/hour) and normalized by day 28 of therapy (median 6 mm/hour). The median ESR remained in the normal range during the followup period. Plasma IL-6 levels, which were abnormal in 92% of untreated patients (median 16 pg/ml), were partially responsive to the initial high doses of corticosteroids by day 28 (median 6 pg/ml), but levels did not completely normalize with continued therapy. Elevation of the ESR was seen during only 58% of all disease flares, but 89% of disease recurrences were associated with increased plasma IL-6 levels (P = 0.03). CONCLUSION: Plasma IL-6 is more sensitive than ESR for indicating disease activity in untreated and treated GCA patients. Standard corticosteroid regimens only partially suppress vascular inflammation. Smoldering disease activity may expose GCA patients to the risk of progressive vascular disease (e.g., formation of aortic aneurysms) and chronic systemic complications such as IL-6-mediated osteopenia.

Adrenal Cortex Hormones↗
PubMed2000

New insights into the pathogenesis of rheumatoid arthritis.

T lymphocytes play a critical role in the inflammatory process of rheumatoid arthritis (RA). Studies in a new animal model of RA, created by implanting human inflamed synovium into SCID mice, have confirmed that the production of matrix-degrading enzymes and pro-inflammatory cytokines is ultimately under T-cell control. T-cell dysfunction in RA patients also alters T-cell dynamics, resulting in profound abnormalities in T-cell pool composition. The cause and consequences of altered T-cell dynamics in RA are not yet understood, but factors determining T-cell homeostasis include the generation of new T cells, loss of T cells during immune responses and self-renewal of T cells within the system. Understanding the mechanisms that govern the formation of the T-cell pool in RA emphasizes the dynamic and quantitative aspects of lymphocyte behaviour in RA and has profound therapeutic implications when devising strategies to counteract T-cell dysfunction.

Animals↗
PubMed2000

The role of T cells in rheumatoid arthritis.

In rheumatoid arthritis (RA), T cells infiltrate into the synovial membrane where they initiate and maintain activation of macrophages and synovial fibroblasts, transforming them into tissue-destructive effector cells. The diversity of the disease process and the formation of complex lymphoid microstructures indicate that multiple T cell activation pathways are involved. This model is supported by the association of distinct disease patterns with different variants and combinations of HLA class II molecules. T cell pathology in RA, however, is not limited to the joint. Affected patients have major abnormalities in the T cell pool, with a marked contraction in T cell receptor diversity and an outgrowth of large clonal populations. Clonally expanded CD4+ T cells lose expression of the CD28 molecule and gain expression of perforin and granzyme. Consequently, the functional profile of expanded CD4(+)CD28null T cells is fundamentally changed and is shifted towards tissue-injurious capabilities. CD4(+)CD28null T cells are particularly important in patients with extra-articular manifestations of RA, where they may have a direct role in vascular injury. Understanding the mechanisms underlying the loss of T cell diversity and the emergence of pro-inflammatory CD4(+)CD28null T cell clonotypes may have implications for other autoimmune syndromes.

Arthritis, Rheumatoid↗
PubMed2000

[Clinical and genetic heterogeneity of rheumatoid arthritis].

The diagnostic category of rheumatoid arthritis, a syndrome of chronic inflammatory disease of the synovial membrane and of extraarticular tissues, covers a broad spectrum of clinical phenotypes. Here we propose that distinct combinations of disease risk genes produce heterogeneity of rheumatoid disease. Recognition of this genetic and clinical heterogeneity has immediate implications as it provides the opportunity to develop selective therapies for the different variants of disease.

Arthritis, Rheumatoid↗
PubMed1999

Perturbation of the T-cell repertoire in patients with unstable angina.

BACKGROUND: Monocytes are constitutively activated in unstable angina (UA), resulting in the production of IL-6 and the upregulation of acute phase proteins. Underlying mechanisms are not understood. To explore whether the production of the potent monocyte activator IFN-gamma is altered in UA, we compared cytokine production by T lymphocytes in patients with UA (Braunwald's class IIIB) and with stable angina (SA). METHODS AND RESULTS: Peripheral blood lymphocytes were collected at the time of hospitalization and after 2 and 12 weeks. Cytokine-producing CD4(+) and CD8(+) T cells were quantified by 3-color flow cytometry after stimulation with phorbol myristate acetate and ionomycin. UA was associated with an increased number of CD4(+) and CD8(+) T cells producing IFN-gamma, whereas patients with SA had higher frequencies of IL-2(+) and IL-4(+) CD4(+) T cells. Expansion of the IFN-gamma( +) T-cell population in UA persisted for at least 3 months. Increased production of IFN-gamma in UA could be attributed to the expansion of an unusual subset of T cells, CD4(+)CD28(null) T cells. CONCLUSIONS: Patients with UA are characterized by a perturbation of the functional T-cell repertoire with a bias toward IFN-gamma production, suggesting that monocyte activation and acute phase responses are consequences of T-cell activation. IFN-gamma is produced by CD4(+)CD28(null) T cells, which are expanded in UA and distinctly low in SA and controls. The emergence of CD4(+)CD28(null) T cells may result from persistent antigenic stimulation.

Adult↗
PubMed1999

Modulation of CD28 expression: distinct regulatory pathways during activation and replicative senescence.

The costimulatory molecule CD28 has a restricted tissue distribution and is expressed on T cells and some plasmacytoma cells. Although CD28 is constitutively expressed, its expression is transiently down-regulated following T cell activation and declines progressively with in vitro senescence. In vivo, CD8+ T cells and, less frequently, CD4+ T cells may completely lose CD28 surface expression during chronic infections and with aging. This correlates with changes of nuclear protein-binding activities to two motifs, site alpha and beta, within the CD28 minimal promoter. Both alpha- and beta-bound complexes are found only in lymphoid tissues, in CD28+ T cells, and in some transformed B cells. These complexes are coordinately expressed except during replicative senescence, which is characterized by the down-modulation of site beta- but not site alpha-binding activities. In contrast, T cell activation induces a parallel decline in both site alpha- and beta-binding activities. CD4+ and CD8+ T cells differ in their beta-binding profiles, which may explain the more pronounced down-regulation of CD28 in senescent CD8+ T cells. In vivo expanded CD4+CD28null and CD8+CD28null T cells uniformly lack alpha- and beta-bound complexes, resembling the pattern seen in chronically activated cells and not of senescent cells.

Antibodies, Monoclonal↗
PubMed1999

Tissue-destructive macrophages in giant cell arteritis.

Giant cell arteritis (GCA) is an inflammatory vasculopathy in which T cells and macrophages infiltrate the wall of medium and large arteries. Clinical consequences such as blindness and stroke are related to arterial occlusion. Formation of aortic aneurysms may result from necrosis of smooth muscle cells and fragmentation of elastic membranes. The molecular mechanisms of arterial wall injury in GCA are not understood. To identify mechanisms of arterial damage, gene expression in inflamed and unaffected temporal artery specimens was compared by differential display polymerase chain reaction. Genes differentially expressed in arterial lesions included 3 products encoded by the mitochondrial genome. Immunohistochemistry with antibodies specific for a 65-kDa mitochondrial antigen revealed that increased expression of mitochondrial products was characteristic of multinucleated giant cells and of CD68+ macrophages that cluster in the media and at the media-intima junction. 4-Hydroxy-2-nonenal adducts, products of lipid peroxidation, were detected on smooth muscle cells and on tissue infiltrating cells, in close proximity to multinucleated giant cells and CD68+ macrophages. Also, giant cells and macrophages with overexpression of mitochondrial products were able to synthesize metalloproteinase-2. Our data suggest that in the vascular lesions characteristic for GCA, a subset of macrophages has the potential to support several pathways of arterial injury, including the release of reactive oxygen species and the production of metalloproteinase-2. This macrophage subset is topographically defined and is also identified by overexpression of mitochondrial genes. Because these macrophages have a high potential to promote several mechanisms of arterial wall damage, they should be therapeutically targeted to prevent blood vessel destruction.

Antigens, CD↗
PubMed1999

IL-16 as an anti-inflammatory cytokine in rheumatoid synovitis.

T lymphocytes are a major component of the inflammatory infiltrate in rheumatoid synovitis, but their exact role in the disease process is not understood. Functional activities of synovial T cells were examined by adoptive transfer experiments in human synovium-SCID mouse chimeras. Adoptive transfer of tissue-derived autologous CD8+ T cells induced a marked reduction in the activity of lesional T cells and macrophages. Injection of CD8+, but not CD4+, T cells decreased the production of tissue IFN-gamma, IL-1beta, and TNF-alpha by >90%. The down-regulatory effect of adoptively transferred CD8+ T cells was not associated with depletion of synovial CD3+ T cells or synovial CD68+ macrophages, and it could be blocked by Abs against IL-16, a CD8+ T cell-derived cytokine. In the synovial tissue, CD8+ T cells were the major source of IL-16, a natural ligand of the CD4 molecule that can anergize CD4-expressing cells. The anti-inflammatory activity of IL-16 in rheumatoid synovitis was confirmed by treating synovium-SCID mouse chimeras with IL-16. Therapy for 14 days with recombinant human IL-16 significantly inhibited the production of IFN-gamma, IL-1beta, and TNF-alpha in the synovium. We propose that tissue-infiltrating CD8+ T cells in rheumatoid synovitis have anti-inflammatory activity that is at least partially mediated by the release of IL-16. Spontaneous production of IL-16 in synovial lesions impairs the functional activity of CD4+ T cells but is insufficient to completely abrogate their stimulation. Supplemental therapy with IL-16 may be a novel and effective treatment for rheumatoid arthritis.

Animals↗
PubMed1999

Corticosteroid requirements in polymyalgia rheumatica.

BACKGROUND: Polymyalgia rheumatica (PMR) is a systemic inflammatory disease of unknown cause that affects older individuals. Clinical symptoms respond promptly to corticosteroids, but treatment is often required for several years, frequently resulting in adverse drug effects. Guidelines for the optimal use of corticosteroids that maximize relief of symptoms but minimize adverse effects of the therapy are needed. OBJECTIVE: To determine whether clinical or laboratory parameters in PMR could be identified that allow for stratifying patients into subsets with differences in corticosteroid requirements. PATIENTS AND METHODS: We studied 27 patients with PMR treated with a standardized schedule of prednisone. Patients were reevaluated at monthly intervals for pain scores and physician and patient assessments. Plasma interleukin 6 level and the erythrocyte sedimentation rate were measured at each visit. The duration of steroid therapy and the cumulative steroid dose were calculated. RESULTS: Based on the initial response to therapy and the duration of disease, the 27 patients could be subdivided into 3 distinct groups. Eight with low erythrocyte sedimentation rates responded rapidly and required corticosteroids for less than 1 year with rare disease flares on tapering of prednisone. Twelve others responded well initially but did not tolerate reduction to lower doses and had remitting disease of more than 1 year. Seven patients had only a partial response to the initial steroid regimen. After 4 weeks of therapy, the erythrocyte sedimentation rates improved, but levels of interleukin 6 remained elevated. Pretreatment pain scores were also higher in these partial responder patients (P = .05). CONCLUSIONS: Polymyalgia rheumatica is a heterogeneous disease with variations in the treatment duration and dose of corticosteroids required for suppression of symptoms. Pretreatment erythrocyte sedimentation rate and nonresponsiveness of interleukin 6 to steroid therapy are helpful in dividing patients into subsets with different treatment requirements.

Acute Disease↗
PubMed1999

Disease pattern in cranial and large-vessel giant cell arteritis.

OBJECTIVE: To identify variables that distinguish large-vessel giant cell arteritis (GCA) with subclavian/axillary/brachial artery involvement from cranial GCA. METHODS: Seventy-four case patients with subclavian/axillary GCA diagnosed by angiography and 74 control patients with temporal artery biopsy-proven GCA without large vessel involvement matched for the date of first diagnosis were identified. Pertinent initial symptoms, time delay until diagnosis, and clinical symptoms, as well as clinical and laboratory findings at the time of diagnosis, were recorded by retrospective chart review. Expression of cytokine messenger RNA in temporal artery tissue from patients with large-vessel and cranial GCA was determined by semiquantitative polymerase chain reaction analysis. Distribution of disease-associated HLA-DRB1 alleles in patients with aortic arch syndrome and cranial GCA was assessed. RESULTS: The clinical presentation distinguished patients with large-vessel GCA from those with classic cranial GCA. Upper extremity vascular insufficiency dominated the clinical presentation of patients with large-vessel GCA, whereas symptoms related to impaired cranial blood flow were infrequent. Temporal artery biopsy findings were negative in 42% of patients with large-vessel GCA. Polymyalgia rheumatica occurred with similar frequency in both patient groups. Large-vessel GCA was associated with higher concentrations of interleukin-2 gene transcripts in arterial tissue and overrepresentation of the HLA-DRB1*0404 allele, indicating differences in pathogenetic mechanisms. CONCLUSION: GCA is not a single entity but includes several variants of disease. Large-vessel GCA produces a distinct spectrum of clinical manifestations and often occurs without involvement of the cranial arteries. Large-vessel GCA requires a different approach to the diagnosis and probably also to treatment.

Aged↗