title: Neuropeptide-induced inhibition of IL-16 release from eosinophils.
abstract: OBJECTIVE
  Eosinophils are prominent inflammatory cells that respond to peripheral neuropeptides in vitro and in vivo. At inflammatory sites, cytokines activate distinct cellular and biochemical pathways that act in a coordinated fashion. We investigated whether peripheral neuropeptides can act as immunomodulators by influencing cytokine release from eosinophils.
  
  
  METHODS
  Human eosinophils were enriched using magnetic cell sorting, and IL-16 levels in supernatants from maintained eosinophils were measured by ELISA. Biological activity of IL-16 was confirmed in lymphocyte chemotaxis assays.
  
  
  RESULTS
  Substance P, vasoactive intestinal polypeptide, calcitonin gene-related peptide and secretoneurin reduced the IL-16 release from eosinophils; this effect was additive to that observed with GM-CSF or IL-5. Decreased IL-16 levels in supernatants resulted in reduced lymphocyte chemotaxis, whereas supernatants derived from SP-treated eosinophils stimulated lymphocyte chemotaxis, even though IL-16 was decreased.
  
  
  CONCLUSIONS
  Results suggest that distinct neuropeptides are able to reduce the number of lymphocytes at inflammatory sites during existing eosinophilia by inhibiting eosinophil IL-16 release, thus attenuating the pro-inflammatory action of lymphocytes and monocytes.
authors.affiliation: Department of Internal Medicine, University of Innsbruck, Innsbruck, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Dunzendorfer
authors.forename: Clemens
authors.initials: C
authors.lastname: Feistritzer
authors.forename: Barbara
authors.initials: B
authors.lastname: Enrich
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Wiedermann
mesh_terms: D000276:Adjuvants, Immunologic / Q000378:metabolism* / Q000494:pharmacology; D000893:Anti-Inflammatory Agents / Q000378:metabolism* / Q000494:pharmacology; D015740:Calcitonin Gene-Related Peptide / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000276:immunology; D015536:Down-Regulation / Q000187:drug effects / Q000276:immunology; D004804:Eosinophils / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism* / Q000494:pharmacology; D019410:Interleukin-16 / Q000378:metabolism*; D015848:Interleukin-5 / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D015213:Neuroimmunomodulation / Q000187:drug effects / Q000276:immunology*; D009479:Neuropeptides / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D053381:Secretogranin II; D013373:Substance P / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology; D014660:Vasoactive Intestinal Peptide / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000276:Adjuvants, Immunologic; D000893:Anti-Inflammatory Agents; D018836:Inflammation Mediators; D019410:Interleukin-16; D015848:Interleukin-5; D009479:Neuropeptides; D053381:Secretogranin II; C081159:secretoneurin; D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D015740:Calcitonin Gene-Related Peptide