Role of protein kinase A in the maintenance of inflammatory pain.
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Although the initiation of inflammatory pain (hyperalgesia) has been demonstrated to require the cAMP second messenger signaling cascade, whether this mechanism and/or other mechanisms underlie the continued maintenance of the induced hyperalgesia is unknown. We report that injection of adenylyl cyclase inhibitors before but not after injection of direct-acting hyperalgesic agents (prostaglandin E2 and purine and serotonin receptor agonists) resulted in reduction in hyperalgesia, evaluated by the Randall-Selitto paw-withdrawal test. In contrast, injection of protein kinase A (PKA) inhibitors either before or after these hyperalgesic agents resulted in reduced hyperalgesia, suggesting that hyperalgesia after its activation was maintained by persistent PKA activity but not by adenylyl cyclase activity. To evaluate further the role of PKA activity in the maintenance of hyperalgesia, we injected the catalytic subunit of PKA (PKACS) that resulted in hyperalgesia similar in magnitude to that induced by the direct-acting hyperalgesic agents but much longer in duration (>48 vs 2 hr). Injection of WIPTIDE (a PKA inhibitor) at 24 hr after PKACS reduced hyperalgesia, suggesting that PKACS hyperalgesia is not independently maintained by steps downstream from PKA. In summary, our results indicate that, once established, inflammatory mediator-induced hyperalgesia is no longer maintained by adenylyl cyclase activity but rather is dependent on ongoing PKA activity. An understanding of the mechanism maintaining hyperalgesia may provide important insight into targets for the treatment of persistent pain. (+info)
Role of nitric oxide in the regulation of microvascular perfusion in human skin in vivo.
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1. Nitric oxide (NO) concentrations were measured in dialysate from healthy human skin, in vivo, both at rest and during the inflammatory response to intradermal histamine or bradykinin. Changes in dialysate NO concentration, measured by electrochemical detection, were related to changes in dermal vascular perfusion, measured using scanning laser Doppler imaging. 2. Basal NO concentration in dermal microdialysate was 0.60 +/- 0.14 microM (mean +/- s.e.m.). Following the intradermal injection of histamine, a transient, time-dependent increase in NO concentration was measured in areas of skin incorporating the weal and in others incorporating the flare. The increase in NO concentration was associated with an increase in dialysate cGMP concentration in both the weal and flare areas. 3. Addition of N G-nitro-l-arginine-methyl ester (L-NAME, 5 mM) to the probe perfusate resulted in an inhibition of the histamine-induced increase in NO and cGMP. Moreover, the reduction in dialysate NO concentration was associated with a reduction in dermal vascular flux, both under basal conditions and within the weal and flare response. 4. These results demonstrate, by the use of microdialysis, that vasoactive mediators can be measured in healthy human skin in vivo. They provide direct evidence that endogenous concentration of NO increases during the inflammatory weal and flare response to histamine and that the increase in dermal NO concentration is associated with increases in cGMP concentration and dermal vascular perfusion, thus confirming a role for NO in vasoregulation in human skin. (+info)
Immunization with recombinant human granulocyte-macrophage colony-stimulating factor as a vaccine adjuvant elicits both a cellular and humoral response to recombinant human granulocyte-macrophage colony-stimulating factor.
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Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important cytokine for the generation and propagation of antigen-presenting cells and for priming a cellular immune response. We report here that use of recombinant human GM-CSF (rhGM-CSF), administered as an adjuvant in a peptide-based vaccine trial given monthly by intradermal injection, led to the development of a T-cell and antibody response to rhGM-CSF. An antibody response occurred in the majority of patients (72%). This antibody response was not found to be neutralizing. In addition, by 48-hour delayed type hypersensitivity (DTH) skin testing, 17% of patients were shown to have a cellular immune response to the adjuvant rhGM-CSF alone. Thymidine incorporation assays also showed a peripheral blood T-cell response to rhGM-CSF in at least 17% of the patients. The generation of rhGM-CSF-specific T-cell immune responses, elicited in this fashion, is an important observation because rhGM-CSF is being used as a vaccine adjuvant in various vaccine strategies. rhGM-CSF-specific immune responses may be incorrectly interpreted as antigen-specific immunity, particularly when local DTH responses to vaccination are the primary means of immunologic evaluation. We found no evidence of hematologic or infectious complications as a result of the development of rhGM-CSF-specific immune responses. (+info)
Absence of Peyer's patches and abnormal lymphoid architecture in chronic proliferative dermatitis (cpdm/cpdm) mice.
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The chronic proliferative dermatitis (cpdm) mutation causes inflammation in multiple organs, most prominently in the skin. Examination of the immune system revealed severe abnormalities in the architecture of lymphoid tissues. Peyer's patches were absent. In contrast, the spleen, lymph nodes, and nasal-associated lymphoid tissues were present. The spleen had normal numbers of T and B cells, but the spleen, lymph nodes, and nasal-associated lymphoid tissues had poorly defined follicles and lacked germinal centers and follicular dendritic cells. The marginal zone in the spleen was absent. The total concentration of serum IgG, IgA, and IgE in cpdm/cpdm mice was significantly decreased, whereas serum IgM was normal. Fecal IgA was low to undetectable in mutant mice, and the concentration of fecal IgM was increased. The titer of DNP-specific Abs following immunization with DNP-keyhole limpet hemocyanin was significantly decreased for all IgG subclasses. In contrast, T cell function appeared normal as assessed by evaluation of the contact hypersensitivity response in cpdm/cpdm mice. The cpdm mutation causes a complex phenotype that is characterized by multiorgan inflammation and the defective development of lymphoid tissues. The cpdm/cpdm mouse may be a useful model to study the factors that control the development of lymphoid tissues, in particular the Peyer's patches, and the mechanisms that control the humoral immune response. (+info)
Golli-induced paralysis: a study in anergy and disease.
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The Golli-MBP transcription unit contains three Golli-specific exons as well as the seven exons of the classical myelin basic protein (MBP) gene and encodes alternatively spliced proteins that share amino acid sequence with MBP. Unlike MBP, which is a late Ag expressed only in the nervous system, Golli exon-containing gene products are expressed both pre- and postnatally at many sites, including lymphoid tissue, as well as in the central nervous system. To investigate whether Golli-MBP peptides unique to Golli would result in neurological disease, we immunized rats and observed a novel neurological disease characterized by mild paralysis and the presence of groups of lymphocytes in the subarachnoid space but not in the parenchyma of the brain. Disease was induced by Th1-type T cells that displayed an unusual activation phenotype. Primary stimulation in vitro induced T cell proliferation with increased surface CD45RC that did not become down-regulated as it did in other Ag-stimulated cultures. Secondary stimulation of this CD45RChigh population with Ag, however, did not induce proliferation or IL-2 production, although an IFN-gamma-producing population resulted. Proliferation could be induced by secondary stimulation with IL-2 or PMA-ionomycin, suggesting an anergic T cell population. Cells could adoptively transfer disease after secondary stimulation with IL-2, but not with Ag alone. These responses are suggestive of a chronically stimulated, anergic population that can be transiently activated to cause disease, fall back into an anergic state, and reactivated to cause disease again. Such a scenario may be important in chronic human disease. (+info)
Final height in girls with Turner's syndrome treated with once or twice daily growth hormone injections. Dutch Advisory Group on Growth Hormone.
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OBJECTIVES: To study final height in girls with Turner's syndrome treated with once or twice daily injections of growth hormone (GH) in combination with low dose ethinyl oestradiol. DESIGN: Until final height was reached, the effect of fractionated subcutaneous injections given twice daily was compared with once daily injections of a total GH dose of 6 IU/m2/day. Twice daily injections were given as one third in the morning and two thirds at bedtime. All girls concurrently received low dose oestradiol (0.05 microgram ethinyl oestradiol/kg/day, increased to 0.10 microgram/kg/day after 2.25 years). PATIENTS: Nineteen girls with Turner's syndrome aged > or = 11 years (mean (SD) 13.6 (1.7) years). MEASUREMENTS: To determine final height gain, we assessed the difference between the attained final height and the final height predictions at the start of treatment. These final height predictions were calculated using the Bayley-Pinneau (BP) prediction method, the modified projected adult height (mPAH), the modified index of potential height (mIPHRUS), and the Turner's specific prediction method (PTSRUS). RESULTS: The gain in final height (mean (SD)) was not significantly different between the once daily and the twice daily regimens (7.6 (2.3) v 5.1 (3.2) cm). All girls exceeded their adult height prediction (range, 1.6-12.3 cm). Thirteen of the 19 girls had a final height gain > 5.0 cm. Mean (SD) attained final height was 155.5 (5.4) cm. A "younger bone age" at baseline and a higher increase in height standard deviation score for chronological age (Dutch-Swedish-Danish references) in the first year of GH treatment predicted a higher final height gain after GH treatment. CONCLUSIONS: Division of the total daily GH dose (6 IU/m2/day) into two thirds in the evening and one third in the morning is not advantageous over the once daily GH regimen with respect to final height gain. Treatment with a GH dose of 6 IU/m2/day in combination with low dose oestrogens can result in a significant increase in adult height in girls with Turner's syndrome, even if they start GH treatment at a relatively late age. (+info)
Expression of multiple unique rejection antigens on murine leukemia BALB/c RLmale symbol1 and the role of dominant Akt antigen for tumor escape.
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Using the pRL1a Ag-loss RLmale symbol1 tumor variant cell line RM2-1, we demonstrated the presence of tumor Ags other than pRL1a that were recognized by CTLs on RLmale symbol1 cells. Semiallogeneic CB6F1 or syngeneic BALB/c CTLs generated against RM2-1 lysed RM2-1 and RLmale symbol1 cells to a similar extent, but no killing was observed with any other tumor or normal cells examined. Clonal analysis and sensitization with reversed phase-HPLC fractions revealed that there were Dd- and Ld-binding peptides recognized by RM2-1 CTLs. Lysis by bulk CTLs stimulated against RLmale symbol1 and limiting dilution analysis suggested that the pRL1a peptide was dominantly recognized to the RM2-1 peptides by CTLs on RLmale symbol1 cells. The rejection response against the parental RLmale symbol1 tumor was much less than that against RM2-1 cells in either CB6F1 or BALB/c mice, suggesting that the presence of altered Akt molecules from which the dominant pRL1a peptide was derived inhibited the rejection response against RLmale symbol1. Depletion of CD4 T cells caused the regression of RLmale symbol1 at the doses in which the tumor grew in untreated mice. The generation of pRL1a CTLs was inhibited in RLmale symbol1-bearing mice. Thus, immunoregulatory CD4 T cells were most likely activated by the altered Akt molecules and inhibited the efficient generation of CTLs against the dominant pRL1a Ag in RLmale symbol1. (+info)
Induction of genital immunity by DNA priming and intranasal booster immunization with a replication-defective adenoviral recombinant.
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Mice immunized through different routes such as i.m., intradermally, or intratracheally with a DNA vaccine to rabies virus developed high titers of serum Ab but only borderline levels of mucosal Abs determined from vaginal secretions. DNA vaccines given by either route enhanced vaginal IgA and IgG2a secretion upon a subsequent intranasal booster immunization with an E1-deleted adenoviral recombinant expressing the same Ag of rabies virus. DNA vaccine priming reduced the Ab response to the adenoviral Ags and counterbalanced the impaired B cell response to the rabies virus Ag expressed by the adenoviral recombinant in mice preimmune to adenovirus. The vaginal B cell response could further be enhanced by using the Th2-type cytokines IL-4 or IL-5 as genetic adjuvants concomitantly with the DNA vaccine before intranasal booster immunization with the recombinant vaccine. (+info)