Pre-exposure to Staphylococcal enterotoxin A exacerbates the pulmonary allergic eosinophil recruitment in rats.
Gram-positive Staphylococcus aureus releases classical enterotoxins which aggravates allergic airway diseases. However, little is known about the mechanisms underlying the cell influx exacerbation in asthmatic individuals under exposure to Staphylococcal enterotoxins. We therefore aimed to investigate the effects of airways exposure to Staphylococcal enterotoxin A (SEA) to pulmonary leukocyte recruitment in rats sensitized and challenged with ovalbumin (OVA). Rats were exposed to SEA at 4h prior to OVA challenge or at 4h post-OVA challenge. Bronchoalveolar lavage (BAL) fluid, bone marrow and lung tissue were obtained at 24h after OVA challenge. Pre-exposure to SEA markedly enhanced the eosinophil counts in both BAL fluid and pulmonary tissue in OVA-challenged rats, whereas neutrophil and mononuclear cell counts remained unchanged. In bone marrow, pre-exposure to SEA alone significantly increased the number of eosinophils, and that was further increased in OVA-challenged rats. Exposure to SEA post-OVA challenge did not affect the number of eosinophils, neutrophils and mononuclear cells in BAL fluid. Pre-exposure to the endotoxin lipopolyssacharide (LPS) in OVA-challenged animals rather enhanced the neutrophil number in BAL fluid. In rats pre-exposed to SEA and OVA-challenged, a marked elevation in the levels of TNF-alpha and eotaxin (but not of IL-10) in BAL fluid was observed. The eotaxin levels increased by about of 3-fold in alveolar macrophages treated with SEA in vitro. In conclusion, airways pre-exposure to SEA causes a selective increase in eosinophil number in BAL fluid and bone marrow of OVA-challenged rats by mechanisms involving enhancement of TNF-alpha and eotaxin synthesis.
Mariano
Nadia S
NS
Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas (Sao Paulo), Brazil.
de Mello
Glaucia C
GC
Ferreira
Tatiane
T
Schenka
André
A
Camargo
Enilton A
EA
de Nucci
Gilberto
G
DeSouza
Ivani A
IA
Antunes
Edson
E
D000818:Animals; D001853:Bone Marrow / Q000187:drug effects / Q000276:immunology; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D002465:Cell Movement / Q000187:drug effects* / Q000276:immunology; D002478:Cells, Cultured; D018450:Disease Progression; D004768:Enterotoxins / Q000494:pharmacology*; D004804:Eosinophils / Q000187:drug effects* / Q000473:pathology; D007114:Immunization; D008168:Lung / Q000187:drug effects / Q000276:immunology; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000473:pathology; D008297:Male; D009504:Neutrophils / Q000187:drug effects / Q000473:pathology; D010047:Ovalbumin / Q000276:immunology; D051381:Rats; D017208:Rats, Wistar; D012130:Respiratory Hypersensitivity / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics
D004768:Enterotoxins; D014409:Tumor Necrosis Factor-alpha; C026066:enterotoxin A, Staphylococcal; D010047:Ovalbumin