Allergen-sensitization increases mast-cell expression of the exocytotic proteins SNAP-23 and syntaxin 4, which are involved in histamine secretion.
BACKGROUND
Activation of mast cells (MCs) via aggregation of immunoglobulin E (IgE) bound to its high affinity receptor (FcepsilonRI) results in release of inflammatory mediators from secretory granules. Histamine is one of the critical biological mediators released in the allergic response. Synaptosomal-associated protein of 23 kDa (SNAP-23) and syntaxin 4 are plasma membrane proteins that have been associated with exocytosis in MCs. Studies with monoclonal IgEs indicate that binding of IgE to FcepsilonRI induces molecular and biological changes in


OBJECTIVE
The aim of this study was to investigate changes in the expression of SNAP-23 and syntaxin 4 by MCs following rat sensitization with ovalbumin (OVA). In addition, we assessed whether these proteins were involved in histamine secretion.


METHODS
SNAP-23 and syntaxin 4 expression was analyzed by Western blot using MCs from control and sensitized animals. Successful sensitization was confirmed based on the passive cutaneous anaphylaxis reaction. To test the role of these exocytotic proteins in histamine secretion, permeabilized MCs were incubated with SNAP-23 and syntaxin 4 antibodies.


RESULTS
Expression of SNAP-23 and syntaxin 4 was significantly higher in MCs from OVA-sensitized rats than in cells from control animals. In addition, incubation of permabilized cells with antibodies to SNAP-23 and syntaxin 4 led to a marked reduction of histamine secretion in stimulated cells.


CONCLUSIONS
Sensitization with OVA increases the expression of SNAP-23 and syntaxin 4 in MCs. Furthermore, our data suggest that these exocytotic proteins participate in histamine secretion.
Salinas
E
E
Department of Microbiology, Basic Science Center, Autonomous University of Aguascalientes, México. emsalin@correo.uaa.mx
Quintanar-Stephano
A
A
Córdova
L E
LE
Ouintanar
J L
JL
D000818:Animals; D002199:Capillary Permeability / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D003888:Desensitization, Immunologic; D005089:Exocytosis / Q000235:genetics / Q000276:immunology*; D005786:Gene Expression Regulation; D006636:Histamine Release / Q000235:genetics / Q000276:immunology*; D007114:Immunization; D008297:Male; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D010047:Ovalbumin / Q000008:administration & dosage; D010323:Passive Cutaneous Anaphylaxis / Q000235:genetics / Q000276:immunology; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D050766:Qb-SNARE Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D050767:Qc-SNARE Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; C100493:SNAP23 protein, human; D010047:Ovalbumin