Norepinephrine suppresses wound macrophage phagocytic efficiency through alpha- and beta-adrenoreceptor dependent pathways.

BACKGROUND: The systemic response to injury is characterized by massive release of norepinephrine (NE) into the circulation as a result of global sympathetic activation. We have recently demonstrated that NE modulates the recruitment of macrophages to the cutaneous wound. We hypothesized that NE suppresses wound macrophage phagocytic function through canonical adrenergic signaling pathways. METHODS: Murine wound macrophages were harvested at 5 days after injury and treated with physiologic and pharmacologic dose norepinephrine. Phagocytosis of green fluorescent protein-labeled Escherichia coli was assayed by flow cytometry. The signaling pathways mediating NE modulation of wound macrophage phagocytosis were interrogated by pharmacologic manipulation of alpha- and beta-adrenoreceptors (ARs), intracellular cyclic adenosine monophosphate (cAMP), and protein kinase A (PKA). Tissue specificity was determined by comparison of wound macrophages to splenic macrophages. RESULTS: Both physiologic and pharmacologic dose NE suppressed wound macrophage phagocytic efficiency. This effect was mediated by alpha- and beta-ARs in a dose-dependent fashion. Direct stimulation of cAMP-suppressed phagocytic efficiency and blockade of PKA signaling prevented NE-mediated suppression of phagocytic efficiency. Splenic macrophage phagocytic efficiency was less than that of wound macrophages and was not altered by NE. CONCLUSIONS: NE has a profound immunosuppressive effect on wound macrophage function that is tissue specific and appears to be mediated through adrenergic receptors and their canonical downstream signaling pathway. Attenuation of post-injury immunosuppression represents another potential mechanism by which beta-AR blockade may reduce morbidity and mortality after severe injury.

Clonidine reduces hypersensitivity and alters the balance of pro- and anti-inflammatory leukocytes after local injection at the site of inflammatory neuritis.

Perineural alpha2-adrenoceptor activation relieves hypersensitivity induced by peripheral nerve injury or sciatic inflammatory neuritis. This effect is associated with a reduction in pro-inflammatory cytokines, as well as a reduction in local leukocyte number and their capacity to produce pro-inflammatory cytokines. Curiously, clonidine's antinociceptive effect appears with a 2-3-day delay after injection. Previous observations have shown that alpha-adrenoceptor activation induces apoptosis in leukocytes, which would reduce leukocyte number. Additionally, macrophage scavenging of apoptotic cells results in a shift to an anti-inflammatory phenotype, with expression of transforming growth factor (TGF)-beta1. We therefore examined the effects of perineural clonidine 24 h and 3 days after its injection on apoptosis, TGF-beta1 expression and lymphocyte and macrophage phenotype in acute sciatic inflammatory neuritis. Perineural clonidine reduced ipsilateral neuritis-induced hypersensitivity in a delayed manner (3 days after treatment), along with a reduction at this time in lymphocyte number and an increase in caspase-3 and TGF-beta1 expressing cells and macrophages co-expressing TGF-beta1 in the sciatic nerve. One day after injection clonidine treatment was associated with a reduction in lymphocytes and pro-inflammatory Th-1 cells as well as increased numbers of caspase-3 and TGF-beta1 expressing cells and macrophages co-expressing TGF-beta1 in sciatic nerve. Clonidine's effects were prevented by co-administration of an alpha2-adrenoceptor antagonist. These data suggest that alpha2-adrenoceptor activation in sciatic inflammatory neuritis increases local apoptosis and anti-inflammatory products early after treatment. This early effect likely underlies the delayed anti-inflammatory and anti-hypersensitivity effects of perineural clonidine in this setting.

Interleukin-1 beta rapidly inhibits aortic endothelium-dependent relaxation by a DNA transcription-dependent mechanism.

OBJECTIVES: This study examined the effects of interleukin-1 beta on isometric tension development and relaxation in isolated rat aortic rings in response to the alpha-1 adrenergic agonist phenylephrine, the endothelium-dependent vasodilator acetylcholine, and the endothelium-independent vasodilator sodium nitroprusside. DESIGN: Randomized, controlled, paired design. SETTING: Animal laboratory within a university department of physiology. SUBJECTS Paired aortic thoracic aortic rings from specific pathogen-free Sprague-Dawley rats. INTERVENTIONS: Series I examined the potential for interleukin-1 beta to cause early arterial endothelial dysfunction. Paired aortic rings were incubated for 2 hrs with interleukin-1 beta or vehicle. Series II examined the potential for inhibition of DNA transcription to attenuate interleukin-1 beta-mediated endothelial dysfunction. Paired rings received either dactinomycin or vehicle before interleukin-1 beta incubation. Series III quantified the degree to which inhibition of DNA transcription inhibited early interleukin-1 beta-mediated endothelial dysfunction. Paired rings received either dactinomycin pretreatment followed by interleukin-1 beta incubation, or pretreatment and incubation with inert vehicles. Series IV assessed the effects of interleukin-1 beta on responsiveness to an exogenous nitric oxide donor, sodium nitroprusside, in the presence of the nitric oxide synthesis inhibitor N omega-nitro-L-arginine methyl ester. MEASUREMENTS AND MAIN RESULTS: Incubation with interleukin-1 beta for 2 hrs had no effect on contractile response but attenuated endothelium-dependent relaxation significantly relative to control. Dactinomycin pretreatment inhibited early interleukin-1 beta-mediated endothelial dysfunction. The combination of interleukin-1 beta and dactinomycin produced effects on endothelium-dependent relaxation that were not different from that seen in rings not exposed to interleukin-1 beta. Interleukin-1 beta attenuated responsiveness to sodium nitroprusside relative to control. CONCLUSIONS: Interleukin-1 beta causes an early impairment of endothelium-dependent vasorelaxation with an onset that precedes its effects on systemic contractility. This impairment occurs via a mechanism that is wholly or predominantly dependent on DNA transcription. The altered vasorelaxation induced by interleukin-1 beta is at least partly mediated by a reduction in nitric oxide responsiveness.

Polyclonal anti-idiotypic antibodies to idazoxan and their interaction with human brain imidazoline binding sites.

Polyclonal antibodies were raised in rabbits against purified polyclonal anti-idazoxan antibodies. The anti-idiotypic antibodies thus obtained, proved able to inhibit [3H]idazoxan specific binding to anti-idazoxan antibodies. Applied to human nucleus reticularis lateralis membrane preparations, these antibodies (20 micrograms) inhibited about 50 and 70% of the imidazoline specific binding of [3H]idazoxan and [3H]clonidine, respectively. Furthermore, they specifically immunoprecipitated 50% of [3H]idazoxan binding activity of imidazoline binding sites solubilized from the same tissue. [3H]Rauwolscine binding to alpha 2-adrenoceptors in rat cortex was not significantly affected by these antibodies. The antibodies labeled a 43 kDa protein in Western blots of partially purified imidazoline binding sites from human brain. In conclusion, these anti-idiotypic antibodies recognize imidazoline binding sites from human brain and allow the detection of a 43 kDa binding protein associated with or representing the imidazoline receptor expressed in human brain.

Neuroendocrine regulation of immunity: the effects of noradrenaline in Xenopus laevis, the South African clawed toad.

A functional association between the peripheral nervous and the immune system in Xenopus laevis, the South African clawed toad, is demonstrated. This association involves the neurotransmitter noradrenaline (NA), produced and released by the sympathetic nerves of the spleen. Chemical sympathectomy prior to immunization reduces splenic NA, and decreases thymus-dependent (TD), but increases thymus-independent (TI), antibody responses. Immune challenge with representatives of the three antigen classes affects splenic NA levels differentially. Thus, the modulatory effect of NA on immunity will depend on the immunogen used. Carrier-priming of helper function in TD responses stimulates a transitory NA release in the spleen, while subsequent immunization activates a more prolonged release. The two types of challenge differ in the antigenic dose given. The effects of NA also depend on the time when it is applied. If used early in the in vivo TD response, antibody production is increased, but if given later, suppressor function is stimulated, thus decreasing antibody production. NA increases both amplifying and suppressing T cell functions in TD responses through stimulation of the alpha 2 adrenoceptor. Alpha 2 adrenoceptor stimulation decreases, and beta adrenoceptor stimulation increases, anti-TNP reactivity. Since an alpha 2 receptor agonist does not affect lectin-stimulated T cell mitogenesis, while a beta receptor agonist depresses it, NA appears to up-regulate T cell functions by affecting their maturation, rather than their clonal expansion.

The Bela Schick lecture for 1985. The atopic diseases.

Review of the atopic diseases suggests a redefinition of the term "atopy" is indicated to reflect new information that has become available during the 60 years since the term was introduced. Atopy may be viewed as a manifestation of a still undefined defect. It is characterized by certain clinical findings and frequently by derangement of the immune and autonomic nervous systems. The atopic diseases are a group of seemingly unrelated conditions--eczema, asthma, rhinitis, hypertrophic sinusitis, and perhaps vernal conjunctivitis and migraine--which cluster in individuals and families. In the respiratory tract and eye, eosinophils in the tissues and secretions are characteristic and are not dependent on the presence of immediate hypersensitivity. Symptoms suggestive of basophil and mast cell mediator release are common to all the atopic diseases, and there is some evidence that nonimmunologic mediator release is enhanced in atopic patients. In the most clearly defined atopic diseases, eczema and asthma, approximately 80% of patients have an increased IgE response to normal environmental allergens. Accompanying and perhaps underlying these enhanced IgE responses are deficiencies of T cell numbers and function particularly in the suppressor T lymphocytes. Evidence exists that decreased beta-2-adrenergic and increased cholinergic and alpha-adrenergic responsiveness accompany and perhaps underlies the atopic diseases irrespective of the presence or absence of allergy.