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A perspective on In vitro developmental neurotoxicity test assay results: An expert panel review. Regul Toxicol Pharmacol 2023; 143:105444. [PMID: 37442267 DOI: 10.1016/j.yrtph.2023.105444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 06/21/2023] [Accepted: 06/29/2023] [Indexed: 07/15/2023]
Abstract
For decades, there has been increasing concern about the potential developmental neurotoxicity (DNT) associated with chemicals. Regulatory agencies have historically utilized standardized in vivo testing to evaluate DNT. Owing to considerations including higher-throughput screening for DNT, reduction in animal use, and potential cost efficiencies, the development of alternative new approach methods (NAMs) occurred; specifically, the advent of the DNT in vitro test battery (DNT IVB). SciPinion convened an expert panel to address specific questions related to the interpretation of in vitro DNT test data. The consensus of the expert panel was that the DNT IVB might be used during initial screening, but it is not presently a complete or surrogate approach to determine whether a chemical is a DNT in humans. By itself, the DNT IVB does not have the ability to capture nuances and complexity of the developing nervous system and associated outcomes including behavioral ontogeny, motor activity, sensory function, and learning/memory. Presently, such developmental landmarks cannot be adequately assessed in the DNT IVB or by other NAMs. The expert panel (all who serve as co-authors of this review) recommended that additional data generation and validation is required before the DNT IVB can be considered for application within global regulatory frameworks for decision-making.
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Interleukin (IL)-17A, F and AF in inflammation: a study in collagen-induced arthritis and rheumatoid arthritis. Clin Exp Immunol 2014; 177:652-61. [PMID: 24813051 PMCID: PMC4137849 DOI: 10.1111/cei.12376] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/07/2014] [Indexed: 12/17/2022] Open
Abstract
Interleukin (IL)-17 plays a critical role in inflammation. Most studies to date have elucidated the inflammatory role of IL-17A, often referred to as IL-17. IL-17F is a member of the IL-17 family bearing 50% homology to IL-17A and can also be present as heterodimer IL-17AF. This study elucidates the distribution and contribution of IL-17A, F and AF in inflammatory arthritis. Neutralizing antibody to IL-17A alone or IL-17F alone or in combination was utilized in the mouse collagen-induced arthritis (CIA) model to elucidate the contribution of each subtype in mediating inflammation. IL-17A, F and AF were all increased during inflammatory arthritis. Neutralization of IL-17A reduced the severity of arthritis, neutralization of IL-17A+IL-17F had the same effect as neutralizing IL-17A, while neutralization of IL-17F had no effect. Moreover, significantly higher levels of IL-17A and IL-17F were detected in peripheral blood mononuclear cells (PBMC) from patients with rheumatoid arthritis (RA) in comparison to patients with osteoarthritis (OA). IL-17A and AF were detected in synovial fluid mononuclear cells (SFMC) in RA and OA, with IL-17A being significantly higher in RA patients. Enriched CD3+ T cells from RA PBMCs produced singnificantly high levels of IL-17A and IL-17AF in comparison to OA peripheral blood CD3+ T cells. IL-17A, F and AF were undetectable in T cells from SFMCs from RA and OA. While IL-17A, F, and AF were all induced during CIA, IL-17A played a dominant role. Furthermore, production of IL-17A, and not IL-17F or IL-17AF, was elevated in PBMCs, SFMCs and enriched peripheral blood CD3+ T in RA.
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Lead-induced Alterations in Gene Expression and Activity of Retinal cGMP PDE Results in Calcium Overload and Rod-selective Apoptosis. Toxicol In Vitro 2012; 12:597-8. [PMID: 20654449 DOI: 10.1016/s0887-2333(98)00044-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Divergence of the systemic immune response following oral infection with distinct strains of Porphyromonas gingivalis. Mol Oral Microbiol 2012; 27:483-95. [PMID: 23134613 DOI: 10.1111/omi.12001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2012] [Indexed: 12/17/2022]
Abstract
Periodontitis is a polymicrobial oral infection characterized by the destruction of tooth-supporting structures that can be linked to systemic diseases such as cardiovascular disease, diabetes or rheumatoid arthritis. Porphyromonas gingivalis, a bacterium implicated in the etiology of periodontitis, has shown variation in inducing T-cell responses among different strains. Therefore, in this study we investigated the strain-specific immune response using a murine experimental model of periodontitis. Periodontitis was induced by P. gingivalis strains A7A1-28, W83 and W50, and later confirmed by the presence of P. gingivalis in the oral microflora and by alveolar bone resorption. Splenocytes were evaluated for gene expression, cellular proteins and cytokine expression. Dendritic cells were stimulated in vitro for T helper cell-cytokine profiling. Results showed that P. gingivalis had the ability to alter the systemic immune response after bacterial exposure. Strains W50 and W83 were shown to induce alveolar bone loss, whereas the A7A1-28 strain did not significantly promote bone resorption in mice. Splenocytes derived from mice infected with strains W50 and W83 induced expression of high levels of interleukin-4 (IL-4) but A7A1-28 stimulated increased IL-10. Stimulation of dendritic cells in vitro showed a similar pattern of cytokine expression of IL-12p40, IL-6 and transforming growth factor-β among strains. A distinct systemic response in vivo was observed among different strains of P. gingivalis, with IL-10 associated with the least amount of alveolar bone loss. Evaluation of pathogen-driven systemic immune responses associated with periodontal disease pathogenesis may assist in defining how periodontitis may impact other diseases.
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Abstract
While T cells have been implicated in the pathogenesis of inflammatory arthritis for more than three decades, the focus on the T helper type 17 (Th17) subset of CD4 T cells and their secreted cytokines, such as interleukin (IL)-17, is much more recent. Proinflammatory actions of IL-17 were first identified in the 1990s, but the delineation of a distinct Th17 subset in late 2005 has sparked great interest in the role of these cells in a broad range of immune-mediated diseases. This review summarizes current understanding of the role of Th17 cells and their products in both animal models of inflammatory arthritis and human immune-driven arthritides.
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Pharmacological strategies to block rod photoreceptor apoptosis caused by calcium overload: a mechanistic target-site approach to neuroprotection. Eur J Ophthalmol 2003; 13 Suppl 3:S44-56. [PMID: 12749677 DOI: 10.1177/112067210301303s08] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE Photoreceptor apoptosis and resultant visual deficits occur in humans and animals with inherited, and disease-, injury- and chemical-induced retinal degeneration. Our aims were three-fold: 1) to determine the kinetics of rod apoptosis and Ca2+ overload in Pde6b9rd1) mice and developmentally lead-exposed rats, 2) to establish a pathophysiologically-relevant model of Ca2+ overload/rod-selective apoptosis in isolated rat retina and 3) to examine different mechanistic based neuroprotective strategies that would abrogate or mollify rod Ca2+ overload/apoptosis. METHODS Retinal morphometry and elemental calcium content ([Ca]) determined the kinetics of rod apoptosis and Ca2+ overload. A multiparametric analysis of apoptosis including rod [Ca], a live/dead assay, rod oxygen consumption, cytochrome c immunoblots and caspase assays was combined with pharmacological studies of an isolated rat retinal model of rod-selective Ca2+ overload/apoptosis. RESULTS Ca2+ overload preceded rod apoptosis in mice and rats, although the extent and kinetics in each differed significantly. The isolated rat model of rod Ca2+ overload/apoptosis showed that blockade of Ca2+ entry through rod cGMP-activated channels with L-cis diltiazem was partially neuroprotective, whereas blockade of Ca2+ entry into rods through L-type Ca2+ channels with D-cis diltiazem or verapamil provided no protection. Inhibition of the mitochondrial Na+/Ca2+ exchanger with D-cis diltiazem provided no protection. CsA and NIM811, mitochondrial permeability transition pore (mPTP) inhibitors, blocked all Ca(2+)-induced apoptosis, whereas the caspase-3 inhibitor DEVD-fmk only blocked the downstream cytochrome c-induced apoptosis. CONCLUSIONS The successful pharmacological neuroprotective strategies for rod Ca2+ overload/apoptosis targeted the rod cGMP-activated channels or mPTP, but not the rod L-type Ca2+ channels.
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The functional interactions between CD98, beta1-integrins, and CD147 in the induction of U937 homotypic aggregation. Blood 2001; 98:374-82. [PMID: 11435306 DOI: 10.1182/blood.v98.2.374] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD98 is expressed on both hematopoietic and nonhematopoietic cells and has been implicated in a variety of different aspects of cell physiology and immunobiology. In this study, the functional interactions between CD98 and other adhesion molecules on the surface of the promonocyte line U937 are examined by means of a quantitative assay of cell aggregation. Several of the CD98 antibodies induced homotypic aggregation of these cells without affecting cellular viability or growth. Aggregation induced by CD98 antibodies could be distinguished from that induced by beta1-integrin (CD29) ligation by lack of sensitivity to EDTA and by increased sensitivity to deoxyglucose. Aggregation induced via CD98 and CD29 could also be distinguished by the pattern of protein tyrosine phosphorylation induced. Some CD29 antibodies partially inhibited CD98-induced aggregation, and these antibodies were neither agonistic for aggregation nor inhibitors of beta1-integrin binding to substrates. Conversely, some CD98 antibodies were potent inhibitors of CD29-induced aggregation. Antibodies to beta2 integrins also partially inhibited CD98-induced aggregation. Unexpectedly, 2 antibodies to CD147, an immunoglobulin superfamily member whose function has remained unclear, were also potent inhibitors of both the aggregation and the protein tyrosine phosphorylation induced via CD98 ligation. The results of this study support a central role for CD98 within a multimolecular unit that regulates cell aggregation.
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Dendritic cells genetically engineered to express IL-4 inhibit murine collagen-induced arthritis. J Clin Invest 2001; 107:1275-84. [PMID: 11375417 PMCID: PMC209294 DOI: 10.1172/jci11490] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Dendritic cells (DCs) are specialized antigen-presenting cells that migrate from the periphery to lymphoid tissues, where they activate and regulate T cells. Genetic modification of DCs to express immunoregulatory molecules would provide a new immunotherapeutic strategy for autoimmune and other diseases. We have engineered bone marrow-derived DCs that express IL-4 and tested the ability of these cells to control murine collagen-induced arthritis (CIA), a model for rheumatoid arthritis in which Th1 cells play a critical role. IL-4-transduced DCs inhibited Th1 responses to collagen type II in vitro. A single injection of IL-4-transduced DCs reduced the incidence and severity of CIA and suppressed established Th1 responses and associated humoral responses, despite only transient persistence of injected DCs in the spleen. In contrast, control DCs and IL-4-transduced T cells or fibroblastic cells failed to alter the course of the disease. The functional effects correlated well with the differential efficiency of DC migration from various sites of injection to lymphoid organs, especially the spleen. The ability of splenic T cells to produce IL-4 in response to anti-CD3 was enhanced after the administration of IL-4-transduced DCS: These results support the feasibility of using genetically modified DCs for the treatment of autoimmune disease.
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Rheumatoid arthritis: guidelines for emerging therapies. THE AMERICAN JOURNAL OF MANAGED CARE 2001; 7:617-26. [PMID: 11439735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
The individual and societal impacts of rheumatoid arthritis are of substantial consequence. Management of the disease has pharmacologically focused on the use of anti-inflammatories and disease-modifying antirheumatic drugs, which are only partially successful in retarding joint destruction and functional disability. The recent emergence of cytokine antagonists (anti-tumor necrosis factor therapy) challenges clinicians and managed care organizations with the need to develop new treatment guidelines. Recent developments in the understanding of rheumatoid arthritis, including its epidemiological characteristics, economic costs, clinical progression, and current and emerging therapies, are reviewed. Pharmacologic utilization models are proposed. Pending the development of broad-based consensus treatment recommendations, interim treatment guidelines are suggested.
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The T lymphocyte structure CD60 contains a sialylated carbohydrate epitope that is expressed on both gangliosides and glycoproteins. Immunol Invest 2001; 30:67-85. [PMID: 11465673 DOI: 10.1081/imm-100104017] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The CD60 antigen is expressed on a majority of T cells in autoimmune lesions, and anti-CD60 can activate T lymphocytes. CD60 has been defined as the GD3 ganglioside, and subsequently as the 9-O-acetylated form of GD3. However, other evidence suggests that anti-CD60 recognizes a glycoprotein or family of glycoproteins expressed by T lymphocytes. The current studies were undertaken to better define the identity of the CD60 antigen on both T cells and non-T cells. Treatment of intact cells with neuraminidases of various specificities confirmed that detection of the CD60 epitope depends on expression of an alpha2, 8-disialic acid carbohydrate linkage, as is found in GD3 and related gangliosides. However, the sialicacid polymer colominic acid inhibited anti-GD2 and anti-GD3, but not anti-CD60 from binding to cell surfaces. Expression of CD60 did not correlate with expression of GD3 on a variety of cell lines and T cell populations. Expression of CD60 and 9-O-acetyl-GD3 was roughly parallel on some non-T cell lines such as melanoma cells, but on T cells expression of CD60 was consistently greater. Antibodies to GD2, GD3 and 9-O-acetyl-GD3 were ineffective at inhibiting binding of anti-CD60 to CD60+ cells. Activation responses of T cells to anti-CD60 were inducible in either the presence or absence of a response to anti-GD3. A novel inhibitor of glucosyl ceramide synthesis, D-threo-1-phenyl-2-palmitoylamino-3-pyrrolidino-1-propanol (D-t-P4) reduced expression of GD3 much more than CD60 on activated T lymphocytes. Following biotinylation of HUT78 T cells, anti-CD60 immunoprecipitated a 70 kDa antigen. Taken together, the present data and previous findings suggest that anti-CD60 can recognize both a modified form of the GD3 ganglioside and a carbohydrate-dependent complex epitope present on one or more glycoproteins. This glycoprotein epitope may be the more abundant and functionally significant CD60 antigen on T lymphocytes, while 9-O-acetyl-GD3 is likely to be the principal structure recognized by anti-CD60 on melanoma cells. These findings emphasize the complexity of understanding the functional roles of carbohydrate epitopes in cell activation.
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MESH Headings
- Antigens, CD/chemistry
- Antigens, CD/immunology
- Antigens, CD/metabolism
- Antigens, Differentiation, T-Lymphocyte/chemistry
- Antigens, Differentiation, T-Lymphocyte/immunology
- Antigens, Differentiation, T-Lymphocyte/metabolism
- Carbohydrate Sequence
- E-Selectin/metabolism
- Epitopes, B-Lymphocyte/chemistry
- Epitopes, B-Lymphocyte/immunology
- Epitopes, B-Lymphocyte/metabolism
- Gangliosides/chemistry
- Gangliosides/immunology
- Gangliosides/metabolism
- Glucosylceramides/antagonists & inhibitors
- Glycoproteins/chemistry
- Glycoproteins/immunology
- Humans
- Jurkat Cells
- Molecular Sequence Data
- N-Acetylneuraminic Acid/chemistry
- N-Acetylneuraminic Acid/immunology
- N-Acetylneuraminic Acid/metabolism
- Propanolamines/pharmacology
- Pyrrolidines/pharmacology
- T-Lymphocytes/immunology
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Effector function of resting T cells: activation of synovial fibroblasts. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:2270-5. [PMID: 11160281 DOI: 10.4049/jimmunol.166.4.2270] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Synovial tissue in rheumatoid arthritis is characterized by infiltration with large numbers of T lymphocytes and APCs as well as hyperplasia of synovial fibroblasts. Current understanding of the pathogenesis of RA includes the concept that synovial fibroblasts, which are essential to cartilage and bone destruction, are regulated by cytokines derived primarily from monocyte-macrophage cells. Recently it has been found that synovial fibroblasts can also function as accessory cells for T cell activation by superantigens and other stimuli. We have now found that highly purified resting T cells, even in the absence of T cell mitogens, induce activation of synovial fibroblasts when cocultured for 6-24 h. Such activation was evident by induction or augmentation of mRNA for stromelysin, IL-6, and IL-8, gene products important in joint inflammation and joint destruction. Furthermore, increased production of IL-6 and IL-8 was quantitated by intracellular cytokine staining and flow cytometry. This technique, previously used for analysis of T cell function, was readily adaptable for assays of synovial fibroblasts. Resting T cells also induced synovial fibroblasts to produce PGE(2), indicating activation of expression of the cyclooxygenase 2 gene. Synergy was observed between the effects of IL-17, a cytokine derived from stimulated T cells that activates fibroblasts, and resting T lymphocytes. Various subsets of T cells, CD4(+), CD8(+), CD45RO(+), and CD45RA(+) all had comparable ability to induce synovial fibroblast activation. These results establish an Ag-independent effector function for resting T cells that is likely to be important in inflammatory compartments in which large numbers of T lymphocytes and fibroblasts can come into direct contact with each other.
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Metals and disorders of cell accumulation: modulation of apoptosis and cell proliferation. Toxicol Sci 2000; 56:255-61. [PMID: 10910982 DOI: 10.1093/toxsci/56.2.255] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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Abstract
In this study we have re-examined the molecular mechanisms involved in activation of T cells by dendritic cells (DC). Human peripheral blood DC (PBDC) were derived by 2 h adhesion followed by 7 day culture in a combination of granulocyte macrophage colony stimulating factor and IL-4, and depletion of residual T and B cells. These PBDC were used to induce autologous T cell proliferation in a CD3-dependent response, and antibodies against CD11a/18 and CD86 were used as control inhibitors of accessory function. Antibodies against five of the cell surface molecules that we have recently identified on the surface of DC, CD13, CD87, CD98, CD147 and CD148, and an antibody which recognizes a molecule that has not as yet been identified, all inhibited the CD3-induced T cell proliferation. These findings were observed not only when antibodies were present throughout the culture, but also when they were prepulsed on to the surface of the DC, suggesting the inhibition was mediated via the antigen-presenting cells rather than the T cell. The same set of antibodies also inhibited an allospecific mixed lymphocyte reaction, confirming that the inhibitory effect was not dependent on the use of a CD3 antibody as the stimulating agent. All the antibodies of known specificity inhibited both CD4 and CD8 T cells equally. Unlike CD87, CD98 and CD147 antibodies, which inhibited activation of both CD45RA (naive) T cells and CD45RO (memory) T cells, CD13 and CD148 appeared to be involved in activation of naive cells only. The molecules identified in this study have not previously been demonstrated to play a role as accessory molecules on DC, the cells that are pivotal for immune induction. Therefore they may provide new potential targets for modulation of the immune response at the APC level.
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Lead and calcium produce rod photoreceptor cell apoptosis by opening the mitochondrial permeability transition pore. J Biol Chem 2000; 275:12175-84. [PMID: 10766853 DOI: 10.1074/jbc.275.16.12175] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calcium overload is suggested to play a fundamental role in the process of rod apoptosis in chemical-induced and inherited retinal degenerations. However, this hypothesis has not been tested directly. We developed an in vitro model utilizing isolated rat retinas to determine the mechanisms underlying Ca(2+)- and/or Pb(2+)-induced retinal degeneration. Confocal microscopy, histological, and biochemical studies established that the elevated [Ca(2+)] and/or [Pb(2+)] were localized to photoreceptors and produced rod-selective apoptosis. Ca(2+) and/or Pb(2+) induced mitochondrial depolarization, swelling, and cytochrome c release. Subsequently caspase-9 and caspase-3 were sequentially activated. Caspase-7 and caspase-8 were not activated. The effects of Ca(2+) and Pb(2+) were additive and blocked completely by the mitochondrial permeability transition pore (PTP) inhibitor cyclosporin A, whereas the calcineurin inhibitor FK506 had no effect. The caspase inhibitors carbobenzoxy-Leu-Glu-His-Asp-CH(2)F and carbobenzoxy-Asp-Glu-Val-Asp-CH(2)F, but not carbobenzoxy-Ile-Glu-Thr-Asp-CH(2)F, differentially blocked post-mitochondrial events. The levels of reduced and oxidized glutathione and pyridine nucleotides in rods were unchanged. Our results demonstrate that rod mitochondria are the target site for Ca(2+) and Pb(2+). Moreover, they suggest that Ca(2+) and Pb(2+) bind to the internal metal (Me(2+)) binding site of the PTP and subsequently open the PTP, which initiates the cytochrome c-caspase cascade of apoptosis in rods.
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Calcium overload triggers rod photoreceptor apoptotic cell death in chemical-induced and inherited retinal degenerations. Ann N Y Acad Sci 2000; 893:282-5. [PMID: 10672249 DOI: 10.1111/j.1749-6632.1999.tb07837.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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The retina of c-fos-/- mice: electrophysiologic, morphologic and biochemical aspects. Invest Ophthalmol Vis Sci 2000; 41:909-16. [PMID: 10711713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
PURPOSE Mice without a functional c-Fos protein (c-fos-/- mice) do not exhibit light-induced apoptotic cell death of rods in contrast to their wild-type littermates (c-fos+/+ mice). To analyze the consequences of the absence of c-fos in the retina, we investigated whether the retinas of c-fos-/- mice have a reduced capacity to absorb and transduce light compared with c-fos+/+ mice. METHODS Retinal function was evaluated in dark-adapted mice by full-field electroretinograms (ERGs) over more than 6 log units of intensity. Retinal morphology was studied by light- and electron microscopy. Arrestin and the heat shock protein 70 (Hsp70) were detected by Western blot analysis. The rhodopsin content and the kinetics of rhodopsin regeneration were determined in retinal extracts. RESULTS Although the configuration of the ERGs was comparable in both groups of mice, c-fos-/- mice showed a marked variability in all quantitative ERG-measures with lower mean amplitudes, longer latencies, and a 0.9-log-unit lower b-wave sensitivity on average. Morphometry showed that c-fos-/- mice have 23% fewer rods on average, whereas the number of cones was comparable among c-fos+/+ and c-fos-/- mice. Arrestin levels appeared slightly reduced in c-fos-/- mice when compared with c-fos+/+ mice, whereas Hsp70 levels were comparable in both genotypes. The kinetics of rhodopsin regeneration were similar, but c-fos-/- mice had a 25% lower rhodopsin content on average. CONCLUSIONS Compared with c-fos+/+ mice, retinal function in c-fos-/- mice is attenuated to a variable but marked degree, which may be, at least in part, related to the reduced number of rods and the reduced rhodopsin content. However, c-fos does not appear to be essential for the ability to absorb photons, nor for phototransduction or the function of second-order neurons. The resistance to light-induced apoptosis of photoreceptor cells in c-fos-/- mice may result from the acute deficit of c-fos in the apoptotic cascade rather than from developmental deficits affecting rod photoreceptor function.
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Retinoic acid produces rod photoreceptor selective apoptosis in developing mammalian retina. Invest Ophthalmol Vis Sci 2000; 41:937-47. [PMID: 10711716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
PURPOSE All-trans retinoic acid (ATRA) or 9-cis retinoic acid (9CRA), added to dissociated developing neural retinal cells, induces progenitor cells to adopt the rod cell's fate. Retinoic acid (RA) also produces apoptotic cell death in developing tissues. The effects of retinoids on mouse retinal development were examined. METHODS Retinas were explanted on postnatal day (PN)1 and cultured with or without the retinal pigment epithelium (RPE) attached. Retinas were cultured for 3 weeks in the absence or presence of 100 or 500 nM ATRA or 9CRA. Morphologic development and apoptotic cell death were examined using cell-specific immunocytochemical markers, the TdT-dUTP terminal nick-end labeling (TUNEL) method, and a caspase assay. RESULTS Retinal explants, with and without RPE, had similar age-dependent increases in opsin expression. In contrast, explants with RPE had less apoptosis during the first week than retinas without RPE. In explants with RPE, ATRA or 9CRA produced rod-selective apoptotic cell death in which 20% to 25% were lost by PN7 with no further loss by PN21. 9CRA-treated explants without RPE had a decreased number of apoptotic cells and a higher number of (rhod)opsin-positive cells at PN3. CONCLUSIONS Factors in RPE appear to regulate rod apoptosis in developing retina. Retinoids produce rod-selective apoptotic cell death during normal rod differentiation. In contrast, retinoids accelerate the expression of opsin in retinas without RPE. These differential effects of RA on rod photoreceptors-apoptosis and differentiation-are similar to those observed in other developing tissues and play an important role in both normal and pathologic development.
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Cytokine blockade as a new strategy to treat rheumatoid arthritis: inhibition of tumor necrosis factor. ARCHIVES OF INTERNAL MEDICINE 2000; 160:437-44. [PMID: 10695684 DOI: 10.1001/archinte.160.4.437] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Rheumatoid arthritis (RA) is a common, frequently severe, chronic inflammatory disease. Although the cause of RA remains unknown, recent advances in understanding its pathogenesis have been substantial. Despite the use of a variety of medications, particularly methotrexate, treatment of RA is not fully effective in most patients. Until recently, insights into inflammatory mechanisms in RA had not been successfully translated into novel classes of therapeutic agents. This gap now will likely be bridged in the form of a new strategy for treating RA-cytokine blockade. Although a variety of cytokines are important in the pathogenesis of RA, tumor necrosis factor (TNF) seems to play a pivotal role. Neutralizing TNF in patients with RA, by means of soluble TNF receptors or anti-TNF monoclonal antibodies, has proven to be a powerful means of controlling disease activity. Studies are in progress to obtain additional information regarding long-term safety of TNF blockade and its effects on disease progression.
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Abstract
OBJECTIVE CD6, a cell surface glycoprotein expressed primarily on T cells, may function as a costimulatory molecule and may play a role in autoreactive immune responses. Recently, a CD6 ligand termed CD166 (previously known as activated leukocyte cell adhesion molecule [ALCAM]) has been identified and shown to be expressed on activated T cells, B cells, thymic epithelium, keratinocytes, and in rheumatoid arthritis synovial tissue. However, the results of functional studies have suggested the existence of a second CD6 ligand. The present study was undertaken to seek evidence for a second CD6 ligand on cultured synovial fibroblasts. METHODS Flow cytometric and biochemical techniques were applied, using anti-CD166 monoclonal antibody (mAb) and a recombinant CD6 fusion protein, to determine whether cultured synovial fibroblasts and other cell types expressed a non-ALCAM CD6 ligand. RESULTS CD14- fibroblastic synoviocytes showed greater binding of a recombinant CD6 fusion protein than of anti-ALCAM mAb. With interferon-gamma treatment of synovial fibroblasts, binding of both reagents increased, but this was more marked for binding of CD6 fusion protein. Exposure of synovial fibroblasts to other cytokines or to the superantigen staphylococcal enterotoxin A also regulated binding of CD6 fusion protein and anti-ALCAM mAb in a discordant manner. Immunoprecipitation of proteins from membrane extracts of synovial fibroblasts with a CD6-Ig fusion protein revealed a novel 130-kd band distinct from CD166; an identical molecule was also precipitated from membranes of HBL-100 tumor cells. CONCLUSION Taken together with previous data regarding CD6 and CD166 function, the present findings strongly suggest the existence of a second CD6 ligand distinct from CD166, which can be expressed by synovial fibroblasts as well as other cells.
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Abstract
PURPOSE Test the hypothesis that the development of mammalian rod outer segments (ROS) varies with retinal eccentricity. METHODS During the period of photoreceptor cell development, ROS lengths, opsin mRNA and (rhod)opsin were measured in central and peripheral retina of cows and pigmented rats. Published ROS length and/or rhodopsin data from albino rats, cows and monkeys were re-analyzed. Logistic growth curves were fitted to the newly obtained and published data. Within a species, growth in central and peripheral regions was compared. RESULTS The logistic growth curves fit all the data well and provide an excellent view of the developmental increases in ROS length, opsin mRNA and (rhod)opsin in each retinal region. Within a species, the growth curves for ROS length, opsin mRNA and (rhod)opsin concentration are superimposable. The age at which ROS length reaches 50% of its adult value is invariant with eccentricity. An exception to this pattern is the simian parafoveal ROS, which appears to have a delayed course of development. CONCLUSIONS The hypothesis is disproved. Unlike rod photoreceptor cell genesis, ROS development is invariant with retinal eccentricity. Primate parafoveal ROS appear to have a different pattern of development.
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Systemic toxicity following administration of sirolimus (formerly rapamycin) for psoriasis: association of capillary leak syndrome with apoptosis of lesional lymphocytes. ARCHIVES OF DERMATOLOGY 1999; 135:553-7. [PMID: 10328196 DOI: 10.1001/archderm.135.5.553] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Sirolimus (formerly rapamycin) is an immunosuppressive agent that interferes with T-cell activation. After 2 individuals with psoriasis developed a capillary leak syndrome following treatment with oral sirolimus lesional skin cells and activated peripheral blood cells were analyzed for induction of apoptosis. OBSERVATIONS A keratome skin specimen from 1 patient with sirolimus-induced capillary leak syndrome had a 2.3-fold increase in percentage of apoptotic cells (to 48%) compared with an unaffected sirolimus-treated patient with psoriasis (21%). Activated peripheral blood T cells from patients with psoriasis tended to exhibit greater spontaneous or dexamethasone-induced apoptosis than did normal T cells, particularly in the presence of sirolimus. CONCLUSIONS Severe adverse effects of sirolimus include fever, anemia, and capillary leak syndrome. These symptoms may be the result of drug-induced apoptosis of lesional leukocytes, especially activated T lymphocytes, and possibly release of inflammatory mediators. Because patients with severe psoriasis may develop capillary leak from various systemic therapies, clinical monitoring is advisable for patients with inflammatory diseases who are treated with immune modulators.
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Apoptosis of human T-cells: induction by glucocorticoids or surface receptor ligation in vitro and ex vivo. J BIOL REG HOMEOS AG 1999; 13:80-9. [PMID: 10503730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Activated T-cells are susceptible to induction of apoptosis or programmed cell death in response to ligation of several cell surface structures, including CD2, CD3, and CD95/Fas. These mechanisms may be important in the regulation of immune responses and in prevention of autoimmunity. We used flow cytometric quantitation of DNA strand breaks to detect T-cells committed to programmed cell death. Activated human peripheral blood T-lymphocytes, and freshly isolated human thymocytes underwent apoptosis when exposed to dexamethasone or to monoclonal antibodies directed at CD2 or CD3. Interleukin-2 reduced spontaneous or dexamethasone-induced apoptosis, but augmented apoptosis due to ligation of CD2. A neutralizing anti-Fas antibody reduced the amount of DNA strand breakage, not only in T-cells exposed to antibodies to CD2 or CD3, but also in dexamethasone-treated cultures. In vivo activated T-cells, from inflammatory synovial fluids, were sensitive to immediate induction of DNA strand breaks without prior in vitro activation by lectin and IL-2. Taken together, the results indicated that: 1. Human lymphocytes, like murine thymocytes, are sensitive to glucocorticoid-induced apoptosis, as well as to programmed cell death triggered through surface receptors; 2. The effects of IL-2 on T-cell apoptosis depend on the apoptotic stimulus; 3. Fas/Fas ligand interactions may be relevant for both membrane receptor and glucocorticoid-induced cell death; and 4. Induction of T-cell apoptosis may be important in therapeutic effects of glucocorticoids in human disease.
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Spatial and temporal expression of AP-1 responsive rod photoreceptor genes and bZIP transcription factors during development of the rat retina. Mol Vis 1998; 4:32. [PMID: 9873070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
PURPOSE The promoter region of the rod-specific beta subunit of cGMP PDE (beta-PDE) and opsin genes contains highly conserved cis-acting elements, which include an AP-1 and/or Nrl response element (NRE: An extended AP-1 like sequence). Transactivation of AP-1 or NRE appears necessary to drive expression of these rod-specific genes during adulthood, however, their role during development is relatively unknown. Therefore, we determined the spatial and temporal relationships between rod morphological and functional development, rod-specific gene expression, and expression of the bZIP transcription factors c-fos, junD and Nrl. METHODS Retinas from 0-45 day old (PN0-45) dark- and light-adapted Long-Evans rats were used. Morphological development was monitored by light and electron microscopy. Whole retinal trypsin-activated cGMP-PDE activity and rhodopsin content were measured biochemically. The expression of opsin, beta-PDE, c-fos, junD and Nrl mRNAs were determined by Northern blot analysis. The cellular localization of Nrl was examined with in situ hybridization. RESULTS The mRNAs for opsin, beta-PDE and c-fos were observed at PN0-2, while cGMP-PDE activity and rhodopsin were detected first at PN5: coincident with rod outer segment development. The developmental pattern of cGMP-PDE activity and rhodopsin accumulation paralleled the expression of beta-PDE and opsin mRNA and all reached their maximal levels by PN45. Nrl expression, for all three transcripts found in the rat retina, was low on PN2 and reached its maximal level at PN14. The c-fos and Nrl expression preceded beta-PDE and opsin mRNA expression by 1-2 days. Nrl expression was detected first in the distal post-mitotic retina at PN5 and then in all nuclear layers during retinal development. Maximal expression shifted from the ganglion cells to the outer nuclear layer as the neural retina matured. In contrast, junD expression was highest at PN0 and declined to a stable level by PN10. CONCLUSIONS Colocalization of Nrl and c-Fos suggests that expression of rod-specific genes, which utilize AP-1 or NRE sites in their promoter, could be regulated through the formation of Nrl-Fos dimers. We hypothesize that Nrl and c-Fos play a fundamental role in the initiation and regulation of the rod-specific gene expression in developing and adult rod photoreceptors.
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Lead-induced alterations in retinal cGMP phosphodiesterase trigger calcium overload, mitochondrial dysfunction and rod photoreceptor apoptosis. Toxicol Lett 1998; 102-103:359-61. [PMID: 10022279 DOI: 10.1016/s0378-4274(98)00232-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Lead exposure results in the selective apoptotic loss of rods and bipolar cells. During and following developmental lead exposure rod/retinal cGMP phosphodiesterase expression and activity are delayed in onset and decreased, [Ca2+] is elevated, and mitochondrial ATP synthesis is decreased. In vitro studies, using retinas incubated in Ca2+ and/or Pb2+, demonstrate that rods selectively die by apoptosis, retinal mitochondrial ATP synthesis is decreased, mitochondrial cytochrome c is released and caspase activity is increased. These results suggest that lead-induced rod and bipolar cell apoptosis is triggered by Ca2+ and Pb2+ overload due to altered cGMP phosphodiesterase activity and that mitochondrial alterations play a central role in this process.
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Lead-induced alterations in retinal cGMP phosphodiesterase trigger calcium overload, mitochondrial dysfunction and rod photoreceptor apoptosis. Toxicol Lett 1998. [PMID: 10022279 DOI: 10.1016/s0378-4274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Lead exposure results in the selective apoptotic loss of rods and bipolar cells. During and following developmental lead exposure rod/retinal cGMP phosphodiesterase expression and activity are delayed in onset and decreased, [Ca2+] is elevated, and mitochondrial ATP synthesis is decreased. In vitro studies, using retinas incubated in Ca2+ and/or Pb2+, demonstrate that rods selectively die by apoptosis, retinal mitochondrial ATP synthesis is decreased, mitochondrial cytochrome c is released and caspase activity is increased. These results suggest that lead-induced rod and bipolar cell apoptosis is triggered by Ca2+ and Pb2+ overload due to altered cGMP phosphodiesterase activity and that mitochondrial alterations play a central role in this process.
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Abstract
Autoantibodies against recoverin are found in the sera of patients with cancer-associated retinopathy (CAR) syndrome. In these studies we examined the effect of anti-recoverin antibodies from the sera of patients with CAR and rat monoclonal antibody on the retinas of Lewis rats. Anti-recoverin autoanti-bodies penetrated into the photoreceptor and bipolar cell layers following intravitreal injection. Their presence in the retina could be detected by immunofluorescence 24 h after injection. At the same time, individual cells undergoing apoptosis were identified throughout photoreceptor and bipolar cell layers using terminal transferase-mediated dUTP nick-end labeling (TUNEL) and electron microscopy. Normal antibodies used in control experiments did not produce TUNEL labeling. At 24 h, DNA fragmentation was confirmed by DNA ladder electrophoresis. At the electron microscopic level, there was clear evidence of cells undergoing apoptotic cell death in the retinas treated with anti-recoverin antibodies. At 24 and 96 h, nuclear chromatin condensation and increased vacuolization of photoreceptor outer segments were observed. An examination of retinas from animals receiving anti-retinal antibodies revealed a loss of 1-2 rows of nuclei in the outer and inner nuclear layers whereas all controls (sham, normal IgG, phosphate buffered saline) showed an unchanged number of nuclei rows. In addition, there was an increase in spacing between the rows of nuclei of the outer nuclear layer in retinas treated with anti- recoverin antibodies, indicating additional cell loss. These studies provide clear evidence that anti-recoverin antibodies are capable of penetrating photoreceptor and bipolar cells, the normal site of recoverin expression in the retina, and that anti-recoverin antibodies produce apoptotic cell death. A similar mechanism may occur in patients with CAR, which may lead to visual loss and blindness.
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A role for CD98 in cellular activation. J BIOL REG HOMEOS AG 1998; 12:25-32. [PMID: 9677532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Functional alterations and apoptotic cell death in the retina following developmental or adult lead exposure. Neurotoxicology 1997; 18:645-64. [PMID: 9339814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Long-term visual system deficits occur in man and animals following developmental and occupational lead exposure. Recent experimental data suggests that the adult brain is not altered following lead exposure. Therefore, the aim of these studies was to use the retina as a CNS model to examine and compare the morphological, biochemical and electroretinographic (ERG) changes occurring in rats exposed to low or moderate levels of lead during development (0-21 days of age) with those occurring in adult rats with equivalent blood and retinal levels of lead for three or six weeks. Five main results were obtained. First, developmental and adult lead exposure for six weeks produced age- and dose-dependent retinal degeneration such that rods and bipolar cells were selectively lost. At the ultrastructural level, all dying cells exhibited the classical morphological features of apoptotic cell death. Second, in the lead-exposed groups, the decrease in the number of rods was correlated with the loss of rhodopsin content per eye confirming that rods were directly affected by lead. Third, single-flash rod ERGs and cone ERGs obtained from developmentally and adult lead-exposed rats demonstrated that there were age- and dose-dependent decreases in the rod a-wave and b-wave sensitivity and maximum amplitudes without any effect on cones. In adult rats exposed to lead for three weeks, qualitatively similar ERG changes occurred in the absence of cell loss or decrease in rhodopsin content. Fourth, developmental and adult lead exposure for three and six weeks produced age- and dose-dependent decreases in retinal cGMP phosphodiesterase (PDE) activity resulting in increased cGMP levels. Fifth, picomolar to micromolar concentration of free lead directly inhibited rat retinal and purified bovine rod cGMP PDE. In summary, there are three main conclusions. First, the retinas of developing and adult rats exposed to lead exhibit qualitatively similar rod-mediated ERG alterations as well as rod and bipolar apoptotic cell death. Thus, developing and mature retinas are both sensitive to the adverse effects of lead: albeit to significantly different extents. Second, a similar biochemical mechanism such as the inhibition of rod and bipolar cell cGMP PDE, varying only in degree and duration, underlies both the lead-induced ERG rod-mediated deficits and the rod and bipolar apoptotic cell death. Third, the composite results from our experiments and those of others suggest that the developing retina might be more sensitive to preweaning lead exposure than the hippocampus and thus may serve as a good model for studying the cellular and molecular mechanisms underlying developmental and adult lead neurotoxicity.
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Abstract
CD98 is a 125 kDa heterodimer, which is strongly expressed on the surface of activated and proliferating cells. Its expression is strikingly regulated during T cell differentiation and activation, but the role of CD98 during T lymphocyte responses is not yet understood. We report here that proliferation of resting peripheral blood mononuclear cells (PBMC) induced by lectin, superantigen (SAg) or conventional antigens was blocked by anti-CD98 heavy chain (CD98hc) mAb. In contrast, anti-CD98hc did not block responses of T cell clones or lines. Anti-CD98hc inhibited IL-2 receptor expression and progression of T cells from G1 to S phase, but did not reduce expression of the IL-2 gene. Anti-CD98hc mAb did not regulate the initial activation events involving the TCR and co-receptor structures, but instead inhibited T lymphocyte responses even when added 18 h or more after the activation stimulus. Further experiments demonstrated that anti-CD98 was not directly affecting T cells in this system, but was instead acting on accessory cells. This was supported using a novel xenogeneic system that takes advantage of the lack of xenoreactivity of purified human T cells against mouse splenocytes. Despite absence of a direct xenoresponse to murine spleen cells, human T cells were activated by SAg presented by murine splenic antigen-presenting cells (APC). Murine anti-human CD98hc did not block T cell proliferation in this system. Furthermore, responses using monocyte-depleted PBMC as APC were not blocked by anti-CD98hc. Taken together, the present data suggests that triggering of human monocyte CD98 can suppress T cell proliferation by a process that halts progression through the cell cycle of recently activated T lymphocytes. This may represent a novel pathway for monocyte regulation of T cell activation.
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MESH Headings
- Antibodies, Blocking/drug effects
- Antibodies, Blocking/pharmacology
- Antibodies, Monoclonal/metabolism
- Antibodies, Monoclonal/pharmacology
- Antigen-Presenting Cells/immunology
- Antigen-Presenting Cells/metabolism
- Antigens, CD/immunology
- Antigens, CD/physiology
- Binding Sites, Antibody
- Binding, Competitive/drug effects
- Binding, Competitive/immunology
- Carrier Proteins/immunology
- Carrier Proteins/physiology
- Cell Cycle/immunology
- Enterotoxins/pharmacology
- Epitopes, T-Lymphocyte/immunology
- Fusion Regulatory Protein-1
- Humans
- Interleukin-2/biosynthesis
- Interleukin-2/genetics
- Interphase/genetics
- Interphase/immunology
- Lymphocyte Activation/drug effects
- Monocytes/immunology
- N-Formylmethionine Leucyl-Phenylalanine/pharmacology
- RNA, Messenger/biosynthesis
- Receptors, Interleukin-2/antagonists & inhibitors
- Receptors, Interleukin-2/biosynthesis
- Receptors, Interleukin-2/immunology
- Signal Transduction/immunology
- Staphylococcus aureus/immunology
- Superantigens/pharmacology
- T-Lymphocyte Subsets/immunology
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The pattern of expression of CD147/neurothelin during human T-cell ontogeny as defined by the monoclonal antibody 8D6. TISSUE ANTIGENS 1997; 50:147-52. [PMID: 9271824 DOI: 10.1111/j.1399-0039.1997.tb02853.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A novel monoclonal antibody termed 8D6 was generated against the human leukemic T-cell line Molt 13 and was found to recognize the neurothelin structure, recently termed CD147. UM8D6 precipitated a single band from HSB2 cells of molecular weight 35 kDa nonreduced and 40 kDa reduced. CD147 is broadly expressed on human hematopoietic cells and is expressed more intensely on thymocytes than on mature peripheral blood T cells. A clear distinction was found by three-color flow cytometry between antigen density on single positive mature thymocytes subsets compared with the corresponding subset from peripheral blood. The 8D6 antibody did not have direct effects on T-cell activation or apoptosis, and the function of CD147 in development and activation of T cells is not yet clear. Nevertheless, its highly regulated expression during T-cell differentiation and the structural characteristics of this antigen suggest that it has an interesting and important role in T-cell biology.
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CD6 dependent interactions of T cells and keratinocytes: functional evidence for a second CD6 ligand on gamma-interferon activated keratinocytes. Immunol Lett 1997; 58:9-14. [PMID: 9436462 DOI: 10.1016/s0165-2478(97)02707-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The CD6 glycoprotein is expressed by T lymphocytes and is hypothesized to interact with one or more ligands expressed on antigen presenting cells (APCs). We show that CD6 mediates binding of the transformed CD4+ T cell line Hut 78 to gamma-interferon activated keratinocytes (KCs). A recombinant CD6-Ig fusion protein has been reported to bind to a CD6 ligand ALCAM, but this is the first demonstration that cell-cell adhesion of human T lymphocytes can be CD6 dependent. The known CD6 ligand ALCAM (CD166) is expressed on cultured KCs but does not appear to mediate KC-Hut 78 binding, suggesting the existence of additional CD6 ligands expressed on KCs. In functional studies using autologous KCs as APCs for tetanus toxoid specific T cell clones, KCs +/- gamma-interferon are unable to stimulate autologous T cells with recall antigen. Therefore interaction of T cell CD6 with CD6 ligands on KCs does not provide sufficient co-stimulation of primed T cells to support responses to nominal antigen.
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The role of T cells in the immunopathogenesis of rheumatoid arthritis: new perspectives. ARTHRITIS AND RHEUMATISM 1997; 40:598-609. [PMID: 9125240 DOI: 10.1002/art.1780400403] [Citation(s) in RCA: 228] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Lesional psoriatic T cells contain the capacity to induce a T cell activation molecule CDw60 on normal keratinocytes. THE AMERICAN JOURNAL OF PATHOLOGY 1997; 150:675-83. [PMID: 9033280 PMCID: PMC1858261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In this report we demonstrate, that in psoriatic skin, basal and suprabasal keratinocytes express CDw60. The CDw60-specific monoclonal antibody, UM4D4, has recently been shown to recognize the 9-O-acetylated disialosyl group on ganglioside GD3. The CDw60 antigen on cultured keratinocytes also seems to be identical with the 9-O-acetylated disialosyl group, because the anti-UM4D4 binding was markedly reduced after neuraminidase treatment of keratinocytes. To examine whether factors from T cells in psoriatic lesions are responsible for the overexpression of CDw60 on keratinocytes, T cell lines obtained from lesional skin were initiated and cloned by limiting dilution. Factors released from 19 of 19 activated T cell clones up-regulated CDw60 expression on cultured normal keratinocytes. T-cell-secreted cytokines, including interleukin (IL)-2, IL-3, IL-4, IL-6, IL-13, transforming growth factor-beta, granulocyte/macrophage colony-stimulating factor, and interferon-gamma were tested for their capacity to modulate keratinocyte CDw60 expression. IL-4 and IL-13 strongly up-regulated the expression of CDw60; by contrast, interferon-gamma down-regulated keratinocyte CDw60 expression. Interestingly, IL-13 may in part be responsible for the T-cell-induced up-regulation of CDw60, because anti-IL-13 partly neutralized this effect of the T cell supernatant. In conclusion, CDw60 expression on psoriatic epidermal keratinocytes is likely induced by intralesionally activated T cells and may in part be due to IL-13. These findings would represent a novel mechanism by which T cells participate in the pathogenesis of psoriasis.
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A novel murine model for the assessment of human CD2-related reagents in vivo. THE JOURNAL OF IMMUNOLOGY 1996. [DOI: 10.4049/jimmunol.157.5.1863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
CD2 is a T cell surface glycoprotein that mediates both cell-cell adhesion and transmembrane signal transduction. To construct a model for the in vivo evaluation of human (h)CD2 function and hCD2-related reagents, hCD2 transgenic mice and murine (m)CD2 knockout mice were crossed, and the F2 generation selected for mCD2-hCD2+ animals by fluorescent flow cytometry. The mCD2-hCD2+ mice are healthy and have a normal distribution of mCD3, mCD4, and mCD8 in thymus, spleen, and lymph node. Therefore expression of the hCD2 transgene does not appear to disrupt normal T cell development. The functionality of hCD2 was demonstrated by T lymphocyte proliferation upon stimulation by combined anti-CD2 plus anti-CD2R (anti-T11(2) plus anti-T11(3)) mAbs. Anti-T11(2) plus anti-T11(3) anti-human CD2 mAbs also induced proliferation of mCD2+hCD2+ F1 lymphocytes, but not mCD2+hCD2- wild-type murine lymphocytes. Either an anti-murine or the human CD2 specific (anti-T11(1)) mAbs inhibited proliferation in alloantigen, PHA, or anti-CD3 mAb stimulated cultures and inhibited only cells bearing the appropriate cognate CD2. In vivo studies of immune function yielded results consistent with these in vitro assays. Thus, anti-T11(1) mAb suppressed contact sensitivity in vivo in the transgenic/knockout mice. mCD2-hCD2+ mice treated with anti-T11(1) or LFA-3 fusion proteins also showed significant prolongation of cardiac allograft survival. This prolongation was associated both with depletion and down-modulation of CD2 on remaining T cells. These data suggest that the transgenic/knockout mice provide a useful in vivo model for the assessment of hCD2-related reagents and CD2 function, free from any potential interactions with mCD2 and mCD2 ligands.
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A novel murine model for the assessment of human CD2-related reagents in vivo. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 1996; 157:1863-9. [PMID: 8757303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
CD2 is a T cell surface glycoprotein that mediates both cell-cell adhesion and transmembrane signal transduction. To construct a model for the in vivo evaluation of human (h)CD2 function and hCD2-related reagents, hCD2 transgenic mice and murine (m)CD2 knockout mice were crossed, and the F2 generation selected for mCD2-hCD2+ animals by fluorescent flow cytometry. The mCD2-hCD2+ mice are healthy and have a normal distribution of mCD3, mCD4, and mCD8 in thymus, spleen, and lymph node. Therefore expression of the hCD2 transgene does not appear to disrupt normal T cell development. The functionality of hCD2 was demonstrated by T lymphocyte proliferation upon stimulation by combined anti-CD2 plus anti-CD2R (anti-T11(2) plus anti-T11(3)) mAbs. Anti-T11(2) plus anti-T11(3) anti-human CD2 mAbs also induced proliferation of mCD2+hCD2+ F1 lymphocytes, but not mCD2+hCD2- wild-type murine lymphocytes. Either an anti-murine or the human CD2 specific (anti-T11(1)) mAbs inhibited proliferation in alloantigen, PHA, or anti-CD3 mAb stimulated cultures and inhibited only cells bearing the appropriate cognate CD2. In vivo studies of immune function yielded results consistent with these in vitro assays. Thus, anti-T11(1) mAb suppressed contact sensitivity in vivo in the transgenic/knockout mice. mCD2-hCD2+ mice treated with anti-T11(1) or LFA-3 fusion proteins also showed significant prolongation of cardiac allograft survival. This prolongation was associated both with depletion and down-modulation of CD2 on remaining T cells. These data suggest that the transgenic/knockout mice provide a useful in vivo model for the assessment of hCD2-related reagents and CD2 function, free from any potential interactions with mCD2 and mCD2 ligands.
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Role of the CD6 glycoprotein in antigen-specific and autoreactive responses of cloned human T lymphocytes. Immunol Suppl 1996; 88:537-43. [PMID: 8881754 PMCID: PMC1456636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
CD6 is a 130 000 MW T-cell surface glycoprotein that can deliver coactivating signals to mature T lymphocytes. Studies using monoclonal antibodies (mAb) have defined at least four epitopes on CD6, and distinct functional responses are elicited by mAb to the different epitopes. The function of CD6 is unknown. Multiple CD6 ligands are predicted, based on data that a soluble CD6 fusion protein precipitates at least three peptides. A cDNA clone for one of these ligands, termed activated leucocyte-cell adhesion molecule (ALCAM) has recently been isolated. In order to further characterize the role of CD6 in cell-cell interactions, we have examined the role of CD6 in a variety of responses by tetanus toxoid (TT) specific human T-cell clones. Anti-CD6 mAb UMCD6 (epitope 3) inhibits antigen-specific responses of such clones to TT, but not to the superantigen SEA. Responses of clones to nominal antigen are CD6-dependent using either peripheral blood mononuclear cells (PBMC) or macrophage-depleted E rosette negative cells as the antigen-presenting cell (APC) population. Furthermore, these clones made autoreactive with DNA methyltransferase inhibitors express increased CD6, and autoreactivity is inhibited by UMCD6. Taken together, the data suggests the existence of a functional CD6 ligand in peripheral blood which is expressed by APC, including cells other than macrophages. Interactions between CD6 and CD6 ligands may regulate both antigen specific and autoreactive responses of human T lymphocytes.
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Dopamine inhibits mammalian photoreceptor Na+,K+-ATPase activity via a selective effect on the alpha3 isozyme. Proc Natl Acad Sci U S A 1996; 93:8034-9. [PMID: 8755598 PMCID: PMC38870 DOI: 10.1073/pnas.93.15.8034] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The rat retina contains dopaminergic interplexiform cells that send processes to the outer plexiform layer where dopamine is released in a light-dependent manner. We report herein that physiologically relevant concentrations of dopamine inhibited ouabain-sensitive photoreceptor oxygen consumption in dark- and light-adapted rat retinas and inhibited Na+,K+-ATPase specific activity (EC 3.6.1.37) in a rat rod outer-inner segment preparation. Experiments with the selective D1 agonist fenoldopam or D2 agonist quinpirole and experiments with dopamine plus either the D1 antagonist SCH23390 or D2/D4 antagonist clozapine showed that the inhibition of oxygen consumption and enzyme activity were mediated by D2/D4-like receptors. The amphetamine-induced release of dopamine, monitored by the inhibition of oxygen consumption, was blocked by L-2-amino-4-phosphonobutyric acid and kynurenic acid. Pharmacological and biochemical experiments determined that the IC50 values of ouabain for the alpha1-low and alpha3-high ouabain affinity isozymes of photoreceptor Na+,K+-ATPase were approximately 10(-5) and approximately 10(-7) M, respectively, and that the D2/D4-like mediated inhibition of Na+,K+-ATPase was exclusively selective for the alpha3 isozyme. The dopamine-mediated inhibition of alpha3 first occurred at 5 nM, was maximal at 100 microM (-47%), had an IC50 value of 382 +/- 23 nM, and exhibited negative cooperativity (Hill coefficient, 0.27). Prior homogenization of the rod outer-inner segment completely prevented the long-lasting inhibition, suggesting that the effect was coupled to a second messenger. Although the physiological significance of our findings to photoreceptor function is unknown, we hypothesize that these results may have relevance for the temporal tuning properties of rods.
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A double-blind, placebo-controlled study of anti-CD5 immunoconjugate in patients with rheumatoid arthritis. The Xoma RA Investigator Group. ARTHRITIS AND RHEUMATISM 1996; 39:1102-8. [PMID: 8670317 DOI: 10.1002/art.1780390705] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE To evaluate the efficacy of an anti-CD5 ricin-linked immunoconjugate (CD5-IC) in patients with rheumatoid arthritis (RA). METHODS A total of 104 evaluable patients were enrolled in a multicenter, double-blind, multiple-dose, placebo-controlled study of CD5-IC. RESULTS Treatment with CD5-IC in doses up to 8 mg/m2/day for 4 days in 1 month failed to produce marked or prolonged T cell depletion and was no more effective than placebo in ameliorating disease manifestations. An unexpectedly high placebo response was observed in 48% of the patients. Adverse events were correlated with the dose of CD5-IC, but the treatment was generally well-tolerated. CONCLUSION At the doses used in this study, CD5-IC was ineffective for treating RA.
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Responsiveness of human T lymphocytes to bacterial superantigens presented by cultured rheumatoid arthritis synoviocytes. ARTHRITIS AND RHEUMATISM 1996; 39:125-36. [PMID: 8546721 DOI: 10.1002/art.1780390117] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVE Type B fibroblastic synoviocytes are abundant in inflamed joints of patients with rheumatoid arthritis (RA), and can secrete cytokines and other mediators of inflammation. The aim of this study was to determine whether cell lines derived from RA type B synoviocytes could also serve as accessory cells for T lymphocyte activation. METHODS Cells from RA synoviocyte lines, with or without preculture in interferon-gamma (IFN gamma), were cultured with purified peripheral blood T cells, in the presence or absence of superantigens or other accessory cell-dependent T cell mitogens. T cell proliferation was measured by thymidine incorporation, and synoviocyte surface markers were analyzed by flow cytometry. RESULTS RA type B synoviocyte lines were potent accessory cells for T cell responses to bacterial superantigens or lectins, and direct cell-cell contact was required. Preculture in IFN gamma augmented synoviocyte expression of major histocompatibility complex (MHC) class II molecules and of ligands for some T cell costimulatory receptors, but synoviocyte accessory cell function was evident even in the absence of IFN gamma. Blocking studies using monoclonal antibodies supported the notion of a role CD2, CD11a/CD18 and MHC class II molecules in synoviocyte-dependent T cell activation. Monoclonal antibodies against IFN gamma, interleukin-1 beta (IL-1 beta), IL-6, IL-8, and tumor necrosis factor alpha failed to block the T cell proliferative responses, but anti-IL-2 was strongly inhibitory. CONCLUSION Cultured RA and type B synoviocytes can perform some of the functions of professional antigen-presenting cells. If such cells have similar properties in vivo, they may be important participants in activation of immune responses, in addition to their previously described synthetic and proinflammatory roles. If RA synovial tissue T cells, like normal peripheral blood T cells, can respond to superantigens presented by synoviocytes, this interaction could be important in the pathogenesis of RA.
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A method for monoclonal antibody isotype switching: anti-CD60 VH expression in a heavy chain-deficient hybridoma variant. Hybridoma (Larchmt) 1995; 14:597-601. [PMID: 8770649 DOI: 10.1089/hyb.1995.14.597] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Alteration of monoclonal antibody isotype is desirable for a variety of purposes, including obtaining an improved reagent for investigative or therapeutic use. A variety of approaches for isotype switching, particularly from IgM to various IgG subclasses, have been described. Antibodies that recognize carbohydrate determinants on glycoproteins, glycolipids, or polysaccharides are generally of the IgM isotype. This includes all available antibodies to the human CD60 antigen, a determinant with cell coactivating properties described on a subset of T lymphocytes and on other cell types. In this report a new method for monoclonal antibody isotype switching is presented. A plasmid containing the VH regions of anti-CD60 linked to C gamma 1 was transfected into a spontaneously arising variant of the CD60 hybridoma that produced kappa light chain but no heavy chain. This transfected hybridoma line maintains stable production of useful quantities of IgG1 monoclonal anti-CD60 in vitro and in vivo.
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Abstract
Retinal cGMP hydrolysis is inhibited following developmental and in vitro lead exposure. To determine whether Pb2+ directly inhibits the rod-specific cGMP phosphodiesterase (PDE) and to examine the kinetic mechanism of this inhibition, purified bovine rod cGMP PDE was assayed at varying [cGMP], [Mg2+] and [Pb2+]. Increasing [cGMP] or [Mg2+] shifted the Pb2+ curves leftward or rightward revealing increased or decreased potency of Pb2+ (nM to pM range), respectively. A 1/velocity vs. 1/mg2+ plot revealed that picomolar [Pb2+] competitively inhibited PDE relative to millimolar [Mg2+]. These novel findings reveal that Pb2+ binds at the Mg2+ site but with 4-6 log units higher affinity, thus preventing cGMP hydrolysis. These results may have implications for other enzymes using Mg2+ as a co-factor and suggest that Mg2+ may be useful for reversing the PDE inhibition by Pb2+.
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Expression of CD60 on multiple cell lineages in inflammatory synovitis. J Transl Med 1995; 73:332-8. [PMID: 7564265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND CD60 is a recently described T cell subset marker that is expressed on the surface of most T lymphocytes in synovial tissue and fluid and on a smaller proportion of peripheral T cells. Activation of T lymphocytes can be triggered through CD60. CD60 is also expressed by neuroectodermally derived cells in thymic epithelium and in skin. EXPERIMENTAL DESIGN Immunohistologic analysis of CD60 expression in synovium and thymus was performed using formalin-fixed tissue samples. Nonlymphoid cell lines grown from similar tissues were analyzed by flow cytometry. RESULTS CD60 was readily identified in formalin-fixed, paraffin-embedded tissues. Simultaneous examination of CD60 distribution and cell morphology demonstrated that, in addition to its presence on T cells, CD60 was also expressed by a variety of nonlymphoid cells in synovium, including synovial lining cells, vascular endothelium, and dendritic-appearing cells deep within synovial tissue. Synovial tissue expression of CD60 was similar in rheumatoid arthritis and in other forms of inflammatory arthritis. In addition, it was strongly expressed by giant cells in pigmented villonodular synovitis. Surface expression of CD60 was detected by flow cytometry on cultured synoviocytes and on other CD60+ nonlymphoid cells, thus excluding adsorption of CD60 shed by T cells as a sufficient explanation of the immunohistologic findings. CONCLUSIONS These results define the T cell-activating CD60 determinant as a broadly distributed Ag within synovial tissue, with a possible functional role in the activation of a variety of cellular populations. CD60 may also be a marker for previously undescribed cell subsets in the synovial compartment, possibly including a cell population of neuroectodermal origin.
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Lead- and calcium-mediated inhibition of bovine rod cGMP phosphodiesterase: interactions with magnesium. Toxicol Appl Pharmacol 1995; 134:43-52. [PMID: 7676457 DOI: 10.1006/taap.1995.1167] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Previously we showed that cGMP hydrolysis in rat whole retinal homogenates exhibited a dose-dependent inhibition following developmental lead exposure and a concentration-dependent inhibition with direct Pb2+ exposure. Additionally, developmental lead exposure resulted in a dose-dependent increase in retinal cGMP and rod Ca2+ levels. To determine whether Pb2+ or Ca2+ directly inhibited the rod-specific cGMP phosphodiesterase (PDE) and to examine the kinetic mechanism of this inhibition, purified bovine rod cGMP PDE was assayed in the presence of varying concentrations of cGMP, and Mg2+, Pb2+, and/or Ca2+. Increasing concentrations of the substrate, cGMP, resulted in a shift of the Pb2+ and Ca2+ concentration-response curves to the left, indicating a decrease in the half-maximal inhibitory concentrations of Pb2+ from nanomolar to picomolar levels. Increasing concentrations of the cofactor, Mg2+, resulted in a shift of the Pb2+ and Ca2+ concentration-response curves to the right, indicating a decrease in the inhibition of PDE activity by Pb2+ or Ca2+. A plot of 1/velocity vs 1/Mg2+ as a function of Pb2+ revealed that picomolar concentrations of Pb2+ competitively inhibited PDE relative to millimolar concentrations of Mg2+. Consistent with this finding, Mg2+ reversed the Pb(2+)-induced inhibition of PDE. Our recent kinetic analysis showed that Mg2+ and cGMP bind at interacting sites on the PDE in a random order. The present results reveal that Pb2+ may bind at the same site but with 4-6 log units higher affinity than Mg2+, thus preventing the hydrolysis of cGMP. These findings provide a novel mechanism for understanding the Pb(2+)-induced inhibition of cGMP PDE. These results may have implications for other enzymes using Mg2+ as a cofactor and suggest that Mg2+ may be useful in these situations for reversing the inhibition by Pb2+.
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Abstract
Biochemical, physiological and histological data have established that 55-65% of retinal mitochondria are located in the photoreceptor inner segments and suggested that photoreceptors have at least a two-fold greater oxygen consumption (QO2) than the remaining inner retina. QO2 in isolated whole rat retina (QWR), outer retina (QOR) and inner retina (QIR) was measured during dark and rod-saturating light adaptation. The effects of function-specific chemical agents on QWR, QOR and QIR during dark and light adaptation were determined. In addition, the oxidation-reduction (redox) potential of cytochrome a3 of whole, outer and inner retina was measured during dark and light adaptation. During dark adaptation, the mean QWR was 1.62 mumol O2 (mg dry wt)-1 hr-1 and whole retinal level of reduced cytochrome a3 was 19%. They decreased by 24% and 37% during light adaptation, respectively. To determine QOR and QIR during dark and light adaptation, the outer retina was pharmacologically-isolated from inner retina using L-2-amino-4-phosphonobutyric acid plus kynurenic acid (APB/Kyn). Experiments in the presence or absence of APB/Kyn revealed that: (i) QOR, but not QIR, of the dark-adapted retina was decreased 37% during light adaptation, (ii) the outer and inner retina consumed 65% and 35% of the QWR during dark adaptation, respectively, and 54% and 46% of the QWR during light adaptation, respectively, (iii) the level of reduced retinal cytochrome a3 in the outer, but not inner, retina was decreased 34% during light adaptation, (iv) during light adaptation, the rate of QO2 was equal in the outer and inner retina, and (v) the effects of APB/Kyn were reversible. These results establish that the mean rate of QIR and retinal cytochrome a3 are unchanged during dark or light adaptation. In addition, they suggest that QOR:QIR in the rat may be modeled using a 65%:35% model during DA and a 55%:45% model during LA. All the function-specific agents--IBMX, lead, diltiazem, ouabain, CO2+ plus Mg2+ and verapamil--significantly decreased QWR during dark and light adaptation. A more detailed analysis revealed that IBMX and lead each selectively reduced (> or = 90%) QOR during dark adaptation whereas CO2+ plus Mg2+ and verapamil each selectively reduced (> or = 93%) QIR during dark and light adaptation. These results are consistent with the known pharmacological sites and mechanisms of these agents. Additional experiments determined that the IBMX- and lead-induced inhibition of QOR during dark adaptation resulted, either wholly or partially, from the influx of extracellular Ca2+. During dark adaptation in Ca(2+)-free medium: (i) QWR and QOR increased while QIR was unchanged, (ii) QOR was not decreased in the presence of IBMX and (iii) QOR was only partially decreased in the presence of lead.(ABSTRACT TRUNCATED AT 400 WORDS)
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Abstract
Biological therapies for rheumatoid arthritis (RA) make use of molecules (including derivative and recombinant forms) produced by cells of the immune system or by cells that participate in inflammatory reactions. Development of monoclonal antibodies against cell-surface structures that are lineage or subset specific has led to trials of anti-T-cell reagents in RA, but results thus far must be regarded as a significant therapeutic disappointment. A monoclonal antibody designed to interfere with the action of a cytokine, tumor necrosis factor alpha (TNF-alpha), has been studied in both open and controlled trials. Treatment with this antibody resulted in marked changes in indices of inflammation, but duration of responses may be limited by the eventual development of antibodies to the anti-TNF-alpha antibody. Immunomodulatory strategies that use the immune system to regulate autoimmune activity have been developed based on animal studies, and evaluation of oral collagen as a treatment in RA is currently underway. If successful, this approach would represent a new direction in the treatment of human autoimmune disease. In the future, use of gene therapy directed to the joint could be a powerful approach to treatment of RA. Rational use of biological therapies in RA will depend, in part, on improved understanding of the pathogenesis of this condition.
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Effects of magnesium on cyclic GMP hydrolysis by the bovine retinal rod cyclic GMP phosphodiesterase. Biochem J 1995; 308 ( Pt 2):653-8. [PMID: 7772055 PMCID: PMC1136976 DOI: 10.1042/bj3080653] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Knowledge of the kinetics of the rod cyclic GMP phosphodiesterase is essential for understanding the kinetics and gain of the light response. Therefore, the interactions between Mg2+, cyclic GMP, and purified, trypsin-activated bovine rod cyclic GMP phosphodiesterase (EC 3.1.4.17) were examined. The effects of Mg2+ and of cyclic GMP on the rod phosphodiesterase activity were mutually concentration-dependent. Formation of a free Mg-cyclic GMP complex is unlikely due to its high dissociation constant (Kd = 19 mM). Plots of 1/velocity versus 1/[cyclic GMP] as a function of [Mg2+] and 1/velocity versus 1/[Mg2+] as a function of [cyclic GMP] intersected to the left of the 1/velocity axis. This is consistent with the formation of a ternary complex between the phosphodiesterase, Mg2+, and cyclic GMP. A competitive inhibitor of the phosphodiesterase relative to cyclic GMP, 3-isobutyl-1-methylxanthine, non-competitively inhibited the enzyme relative to Mg2+, Pb2+, a competitive inhibitor of the phosphodiesterase relative to Mg2+ [D. Srivastava, R.L. Hurwitz and D. A. Fox (1995) Toxicol. Appl. Pharmacol, in the press] non-competitively inhibited the enzyme relative to cyclic GMP. Collectively these results are suggestive of a rapid equilibrium random binding order of Mg2+ and cyclic GMP to the rod phosphodiesterase.
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Trichloroacetic acid: investigation into the mechanism of chromosomal damage in the in vitro human lymphocyte cytogenetic assay and the mouse bone marrow micronucleus test. Carcinogenesis 1995; 16:1127-33. [PMID: 7767975 DOI: 10.1093/carcin/16.5.1127] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Trichloroacetic acid (TCA) was tested for its ability to induce chromosomal damage in cultured human peripheral blood lymphocytes and in bone marrow cells of male and female C57BL/6JfBL10/Alpk mice. Two in vitro cytogenetic assays were conducted with TCA. In the first TCA, as free acid, was added to whole blood cultures at final concentrations of 500, 2000 and 3500 micrograms/ml in the presence and absence of an auxiliary metabolic activation system (rat liver S9-mix). Statistically significant increases in the percentage of aberrant cells compared with solvent control values were observed in cultures treated with TCA at 2000 and 5000 mu/ml. Investigation into the effects of TCA on the pH of the culture medium revealed significant reductions in pH at both these TCA concentrations. Neutralized TCA was then tested at concentrations of 500, 2,000 and 5000 micrograms/ml, also in the presence and absence of S9-mix. No statistically or biologically significant increases in the percentage of aberrant cells were observed in any of these cultures. In the mouse micronucleus test, neutralized TCA was administered in two equal intraperitoneal doses 24 h apart to C57BL/6JfBL10/Alpk mice (337, 675 and 1080 mg/kg in males; 405, 810 and 1300mg/kg in females). These dose levels represent 25%, 50% and 80% of the median lethal dose (MLD) in this strain of mouse. Bone marrow samples were taken 6 and 24 h after the second dose and the chromosomal damage assessed by analysis of the bone marrow for micronuclei. No statistically or biologically significant increases in the incidence of micronucleated polychromatic erythrocytes compared with the solvent control dosed animals were observed in either sex at the 6 h sampling time or in the females at the 24 h sampling time. A small but statistically significant increase in micronucleated polychromatic erythrocytes was observed in male mice 24 h after a dose of 675 mg/kg (50% MLD). Since no increases were noted at the 25 or 80% MLD, and the levels recorded are within the range of the concurrent solvent control values, the small increase observed in the males at the 50% MLD is considered not to be biologically significant. Flow cytometric studies on suspensions of isolated liver cell nuclei revealed that changes in FITC binding (indicating altered chromatin conformation) were induced by pH changes alone and were not caused by neutralized TCA.(ABSTRACT TRUNCATED AT 400 WORDS)
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Structures on the cell surface. Update from the Fifth International Workshop on Human Leukocyte Differentiation Antigens. ARTHRITIS AND RHEUMATISM 1994; 37:1245-8. [PMID: 8053962 DOI: 10.1002/art.1780370820] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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