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Staphylococcal enterotoxin of the types A and B (SEA and SEB) : effects of the pulmonary inflammatory response in mice and human eosinophils

Author(s):
Dalize Maria Squebola Cola
Total Authors: 1
Document type: Doctoral Thesis
Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
Defense date:
Examining board members:
Maria Heloisa de Souza Lima Blotta; Alessandra Linardi; Richardt Gama Landgraf; Sandra Helena Poliselli Farsky
Advisor: Edson Antunes
Abstract

Gram-positive Staphylococcus aureus releases classical enterotoxin 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. Recent study in our group showed that SEA pre-exposure in OVA challenge mice increase the eosinophils influx for lung tissues and broncoalveolar lavage (BAL) and also increase the eosinophils number in bone marrow. These eosinophils increases in BAL were accompanied for increase of the TNF? and eotaxin. Therefore, the objective of the study, was deepen the know about the responsible mechanisms of the SEA and SEB exacerbation in allergy pulmonary inflammation mice. Were investigated also, the effects of SEA and SEB in eosinophils functions (chemotaxis and adhesion). Mice were exposed to SEA at 4 h, 12 h, 24 h, 48 h and SEB 4 h, 12 h and 24 h prior to OVA challenge or prior PBS instillation. The SEA pre-exposed 12 h, 24 h and 48 h increase the eosinophils number in the lung tissues and in 48 h of the BAL. This increased was preceded of the high eotaxin levels. In the bone marrow we observed a increased of eosinophils number in 24 h and 48 h of SEA pre-exposed, accompanied of the IL-5 and eotaxin increase and the CCR3 and VLA-4 dowregulation and decrease of the eosinophils adhesion function. In blood, we observed an increase of eosinophils number in 4 h, 12 h and 24 h of the SEA pre-exposed returned in the basal levels in 48 h. In relation of SEB, we observed of the pre-exposed of SEB in OVA challenge mice increased of eosinophils number in lung tissues in all the study time (4 h, 12, and 24 h). In the BAL, we observed of the SEB pre-exposed increased the eosinophils number only in 4 h in OVA challenge mice. Also in pulmonary ambit, we observed a high eotaxin (4 h, 12 h) and IL-8 (4 h) levels and a decreased of the IL-4 and IL-6 in all the study time. In bone marrow, the SEB pre-exposed of the 4 h and 12 h, increase the eosinophils number in OVA challenge mice, not accompanied of the high IL-5 and eotaxin levels. In the first part, airways exposure to SEA produces a marked eosinophil recruitment to the lung tissue of allergic mice that is clearly detected at prolonged times of this enterotoxin exposure (24 and 48 h before OVA challenge). Eosinophils accumulate in BM at these same time-periods of SEA exposure through IL-5- and CCR3-dependent mechanisms, along with down-regulation of CCR3 / VL4 and impaired cell adhesion to VCAM-1. On the other hand, eosinophils time-dependently disappear from circulating blood after SEA exposure. Already the airways exposure to SEB produces a marked eosinophil recruitment to the lung tissue of allergic mice that is clearly detected at early times of this enterotoxin exposure and increase of eosinophils number in BM at these same time-periods of SEB exposure through IL-5 and eotaxin-independent mechanisms. It is likely that alterations of BM function are an early step for the progression of asthmatic disease and exacerbation by Staphylococcal enterotoxin. Understanding the mechanisms that regulates bone marrow eosinophil mobilization and its trafficking to the peripheral circulation and airways in allergic animals may be important for the development of effective asthma therapies in conditions of Staphylococcal superantigen exposure. To study the direct effects of the SEs in eosinophils performed the functional assays (chemotaxis and adhesion), p38 MAPK phosphorylation and calcium mobilization. The number of migrated eosinophils was significantly decrease in eosinophils incubated with SEA in the times (30 min, 2 h and 4 h) and SEA concentration (0,5, 1 and 3 ng/ml) to chemotaxis agent, eotaxin, and RANTES, compared with control eosinophils. In relation of the SEB (30 ng /ml), not differences in chemotaxis was found. Only in the SEB concentration of the 1 ng/ml observed decrease of chemotaxis in eotaxin response. In the adhesion, we observed a decreased in eosinophils incubated with SEA and SEB in response of ICAM-1 and VCAM-1. The p38 MAPK phosphorylation and calcium mobilization was decrease in eosinophils incubated with SEA and SEB in eotaxin response. Therefore, we conclude that SEA and SEB was capable of the dowregular of the human eosinophils response. (AU)

FAPESP's process: 08/10869-6 - Modulation of mice pulmonary allergic responses by the sthaphylococcal enterotoxin types a and b (sea and SEB)and human eosinophil
Grantee:Dalize Maria Squebola Cola
Support type: Scholarships in Brazil - Doctorate