Tese
Estudo do papel do receptor ativado por protease 2 no recrutamento de leucócitos e na produção de mediadores inflamatórios em modelo experimental de asma induzido por ovalbumina em camundongos
Fecha
2017-10-27Autor
Natália Alves de Matos
Institución
Resumen
Proteinase-activated receptors (PAR) are part of a family of G-protein-coupled
receptors that are activated via proteolytic cleavage of a specific sequence of amino
acids in N-terminal portion, and their activation has been implicated in the regulation of
inflammation. PAR-2 has been implicated in mediating allergic airway inflammation
once is expressed by many cells in the airways as well as in epithelial and alveolar
macrophages. The aim of this study was to study the role of PAR-2 activation in the
production of inflammatory mediators and on the recruitment of leukocytes in
experimental ovalbumin (OVA)-induced asthma models. All experimental protocols
were approved by local UFMG Ethics’s Committee for Animal Use - certificate number
348/2014. Allergic lung inflammation was induced in sensitized BALB/c mice (female,
8-10 weeks) through the intranasal instillation of ovalbumin (OVA, 10μg) in two distinct
experimental models differing in relation to the number of intranasal challenges (3 or 6
challenges). Bronchoalveolar lavage (BAL) was performed and lungs were obtained in
different intervals of time, from 30 min to 72 h after challenging. To evaluate the
participation of PAR-2 in experimental asthma, sensitized mice were pretreated with
selective PAR-2 antagonist (ENMD1068, 0.1-1.0 mg / kg, intraperitoneal) 1 hour before
intranasal instillation of OVA. The blockade of the action of PAR-2 activating
endogenous proteases in PAR-2 antagonist-treated mice, played an important role on
the control of allergic respiratory inflammation in both asthma’s models. Overall,
pretreatment with PAR-2 antagonist ENMD1068 inhibited the recruitment of
neutrophils, eosinophils, mononuclear cells to LBA when compared to OVA-treated
mice. After OVA instillation (3 intranasal challenge model), PAR-2 blockade reduced
PAR-2 protein expression in leukocytes, CXCL1, IL-6 and CCL5 production in BAL and
IL-1β releasing into the lung, vascular permeability in lung and M2 lung macrophages
population. In addition, PAR-2 blockade increased IL-10 levels in BAL when compared
to OVA group. Six intranasal challenge model also promotes leukocyte infiltrating into
BAL in a PAR2-dependent manner. PAR-2 blockade impairs eosinophil peroxidase
(EPO) and myeloperoxidase (MPO) activity at the parenchyma lung, proteins
extravasation into BAL, reduces the loss of dynamic pulmonary compliance and the
lung resistance in response to methacholine, as well as mucus production and collagen
deposition when compared to OVA-challenged. In the present study we demonstrated
a role for PAR-2 activation in the modulation of essential phenomena leading to allergic
asthma in BALB/c mice both models. In addition, the blockade of the action of PAR-2
activating endogenous proteases in PAR-2 antagonist-treated mice played an
important role on the control of allergic respiratory inflammation, suggesting that PAR-2
blockade may be useful as a new pharmacological approach regarding the treatment of
airways allergic diseases.