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M L Crane

Publications and source records attributed to M L Crane.

4 recordsLinked to original sources
PubMed2000

Ligand-activation of the adenosine A2a receptors inhibits IL-12 production by human monocytes.

Adenosine (ADO) exerts potent anti-inflammatory and immunosuppressive effects. In this paper we address the possibility that these effects are partly mediated by inhibition of the secretion of IL-12, a proinflammatory cytokine and a major inducer of Th1 responses. We demonstrate that 5'-N-ethylcarboxamidoadenosine (NECA), a nonspecific ADO analogue, and 2-p-(2-carbonyl-ethyl)phenylethylamino-5'-N-ethylcarboxamidoadenos ine (CGS-21680), a specific A2a receptor agonist, dose-dependently inhibited, in whole blood ex vivo and monocyte cultures, the production of human IL-12 induced by LPS and Stapholococcus aureus Cowan strain 1. However, the A1 receptor agonist 2-Chloro-N6-cyclopentyladenosine and the A3 receptor agonists N6-Benzyl-NECA and 1-deoxy-1-[6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-N-methyl-be ta-d -ribofuranuronamide expressed only weak inhibitory effects. On the other hand, NECA and CGS-21680 dose-dependently potentiated the production of IL-10. The differential effect of these drugs on monocyte IL-12 and IL-10 production implies that these effects are mediated by A2a receptor signaling rather than by intracellular toxicity of ADO analogue's metabolites. Moreover, CGS-21680 inhibited IL-12 production independently of endogenous IL-10 induction, because anti-IL-10 Abs failed to prevent its effect. The selective A2a antagonist 8-(3-Chlorostyryl) caffeine prevented the inhibitory effect of CGS-21680 on IL-12 production. The phosphodiesterase inhibitor Ro 20-1724 dose-dependently potentiated the inhibitory effect of CGS-21680 and, furthermore, Rp-cAMPS, a protein kinase A inhibitor, reversed the inhibitory effect of CGS-21680, implicating a cAMP/protein kinase A pathway in its action. Thus, ligand activation of A2a receptors simultaneously inhibits IL-12 and stimulates IL-10 production by human monocytes. Through this mechanism, ADO released in excess during inflammatory and ischemic conditions, or tissue injury, may contribute to selective suppression of Th1 responses and cellular immunity.

Adenosine↗
PubMed2000

Adrenocorticotropin, glucocorticoid, and androgen secretion in patients with new onset synovitis/rheumatoid arthritis: relations with indices of inflammation.

To determine whether alterations in adrenocortical function occur early in the development of inflammatory joint disease, we examined patients with new onset synovitis (<1 yr) prior to treatment with corticosteroids or other disease-modifying antirheumatic drugs. Thirty-two patients with new onset synovitis, including 15 fitting criteria for rheumatoid arthritis (RA), taking no medications, were referred for study by local rheumatologists; 32 age- and sex-matched healthy individuals were recruited as controls. Patients and controls had blood drawn under identical conditions between 0900 and 1100 h. Plasma ACTH, cortisol, dehydroepiandrosterone (DHEA), DHEA sulfate, free and total testosterone, erythrocyte sedimentation rate, C-reactive protein, and rheumatoid factor were measured. Compared with controls, patients had higher inflammatory indices (erythrocyte sedimentation rate, C-reactive protein) and lower basal morning levels of free testosterone (lower in males age > or =45 yr), but similar levels of ACTH, cortisol, DHEA, DHEA sulfate, and total testosterone. In addition, the positive correlations between ACTH-cortisol, ACTH-DHEA, and cortisol-DHEA, observed in the normal controls, were weakened or abolished in the patients (both total and RA subset). No positive relations between inflammatory indices and ACTH or cortisol were noted, yet an inverse correlation between these indices and DHEA and testosterone was observed. Moreover, a steeper age-associated decline in DHEA was observed in our cross-sectional sample of patients with new onset synovitis. We conclude that patients with synovitis (including those fitting criteria for RA) have adrenocortical hormone alterations within a year of disease onset. Paradoxically, these patients have no positive relation between indices of inflammation and ACTH or cortisol, but rather serum androgen levels are inversely correlated with these indices. In addition, the relations between ACTH, the classic stimulus of cortisol and adrenal androgens, and these hormones are weakened or abolished, whereas the negative relation between age and zona reticularis function is steeper than that of controls.

Adrenocorticotropic Hormone↗
PubMed1995

Phenotypic and functional changes in peripheral blood monocytes during progression of human immunodeficiency virus infection. Effects of soluble immune complexes, cytokines, subcellular particulates from apoptotic cells, and HIV-1-encoded proteins on monocytes phagocytic function, oxidative burst, transendothelial migration, and cell surface phenotype.

We postulated that changes in the cell surface display of molecules that facilitate cell-cell and cell-matrix adhesions may reflect the changing immunosurveillance capacity of blood monocytes during progression of human immunodeficiency virus (HIV) infections. In Centers for Disease Control (CDC) stage A patients, whose monocytes' ability to phagocytose bacteria and generate reactive oxygen intermediates is often increased, the frequency of monocytes expressing CD49d, HLA-DP, HLA-DQ, and an activation epitope of CD11a/CD18 was increased and monocyte transendothelial migration was unimpaired. In CDC stage B/C patients, whose monocytes' ability to phagocytose bacteria and migrate across confluent endothelial monolayers was diminished, surface expression of CD49e and CD62L and the percentage of monocytes expressing CD18, CD11a, CD29, CD49e, CD54, CD58, CD31, and HLA-I were significantly decreased. Incubating normal donor monocytes with immune complexes in vitro reproduced the phenotypic and functional abnormalities seen in stage B/C patients. By contrast, in vitro stimulation with subcellular particulates released by apoptotic lymphocytes reproduced changes seen in stage A patients' monocytes. Although circulating monocytes appear to be activated at all stages, these data suggest that the high levels of circulating immune complexes, found predominantly in the later stages of HIV infection, may be particularly instrumental in reducing the monocyte's capacity to maintain surveillance against infection.

Antigen-Antibody Complex↗