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Previous issue date: 2011 / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil. / A provocação por via respiratória com ovalbumina (OVA) em camundongos
sensibilizados promove, na medula óssea (MO), eosinopoiese, resposta exacerbada
à Interleucina(IL)-5, e mudanças no padrão de resposta em cultura à eotaxina, à IL-
13 e aos antiinflamatórios não esteroidais (NSAIDs). Em cultura de MO, a
Prostaglandina (PG) E2 induz apoptose de eosinófilos, por via dependente de NO
sintase indutível (iNOS) e ligante de CD95 (CD95L), enquanto a dexametasona
(DEXA) promove eosinopoiese, gerando eosinófilos agregados e morfológicamente
imaturos e protege contra da apoptose induzida por PGE2, provavelmente por
mecanismos que regulem a expressão ou ativação de integrinas. No presente
trabalho avaliamos se: a) in vitro, os efeitos dos NSAIDs, da IL-13 e da eotaxina
dependem da produção de cisteinil-leucotrienos (CisLT) e da sinalização via receptor
1 de CisLT (CysLT1R); b) in vitro, a DEXA regula expressão de VLA-4, que
promoveria a agregação e imaturidade dos eosinófilos, e se PGE2 contrapõe a ação
da DEXA; c) in vivo, G-CSF e dietilcarbamazina (DEC) promoveriam eosinopenia
medular e sistemica e se inibiriam a inflamação pulmonar alérgica. Resultados: a)
NSAIDs, eotaxina e IL-13 potencializam a eosinopoiese via produção de CisLT e
sinalização via CysLT1R. Os NSAIDs ainda protegem os eosinófilos da apoptose
induzida por PGE2 exógena. b) A interação farmacológica entre PGE2 e DEXA
modificam a ação de ambas, de forma estreitamente relacionada sobre a expressão
de VLA-4 e, em condições específicas, esses agentes sinergizam gerando
quantidades aumentadas de eosinófilos maduros. c) A DEC, inibidor da síntese de
LTs, que na filariose experimental possivelmente atua via iNOS, inibe a eosinopoiese
e os efeitos da provocação sobre o pulmão e a MO, através da via iNOS-CD95L. O
Fator Estimulante de Colônias de Granulócitos (G-CSF), estimulante da
neutropoiese, igualmente inibiu a inflamação pulmonar alérgica através da inibição
da eosinopoiese. Este trabalho é parte do projeto intitulado "Eosinofilia na
Asma Experimental", licenciado pela Comissão de Ética no Uso de Animais
(CEUA) da Fiocruz, sob nos L010/04 e L002/09. / Our laboratory has previously shown that airway allergen challenge in
ovalbumin-sensitized mice rapidly induces an increase in bone-marrow (BM)
eosinophil production (eosinopoiesis), along with an increased response to
Interleukin(IL)-5 in BM culture, changes in the ex vivo responses to cytokines and
immunomodulators, including nonsteroidal anti-inflammatory drugs (NSAIDs) and
cysteinyl-leukotrienes (CysLT), and colonization of the lungs by eosinophil
progenitors. Early in the course of IL-5-induced eosinophil differentiation in BM
culture, Prostaglandin E2 (PGE2) induces apoptosis, through a pathway dependent
on the inducible isoform of NO synthase (iNOS) and the ligand for CD95 (CD95L).
NSAIDs enhance eosinopoiesis and protect eosinophils in this critical period from
exogenous PGE2, through a novel mechanism of action at the celular level. In this
study, we show that indomethacin and aspirin act through endogenously synthesized
CysLT, by establishing the essential roles of 5-lipoxygenase, LTC4 synthase and
CysLT1R receptors, as well as the cytoprotective effect of CysLT against exogenous
PGE2. The similarity between the effects of NSAIDs and those of eotaxin and IL-13
prompted us to reevaluate the contribution of endogenous CysLT to the effects of
these cytokines. We confirmed that eotaxin and IL-13 act through this mechanism,
and expand therefore the list of agents that, through CysLT, enhance eosinopoiesis,
protecting immature eosinophils from apoptosis induced through the iNOS-CD95L
pathway. Dexamethasone promotes BM eosinopoiesis, generating aggregated,
cytologically immature eosinophils, which are nevertheless protected from PGE2-
induced apoptosis. We examined therefore the possibility that dexamethasone
upregulates integrin expression/activation, thereby maintaining an immature celular
phenotype in cultured eosinophils, while PGE2 would have opposite effects on both
integrin function and cytological maturation. We show that the proapoptotic effects of
PGE2 are profoundly modified by its pharmacological interaction with
dexamethasone, paralleling the effects of both drugs on integrins, and leading to a
synergic generation of increased numbers of mature eosinophils, in very specific experimental conditions. Diethylcarbamazine (DEC) is an antihelminthic drug that
blocks leukotriene synthesis, and possibly acts in experimental filarial infection
through iNOS. We have examined, for the first time, the effects of DEC in a model of
allergic pulmonary inflammation, showing that DEC is very effective in preventing the
impact of airway allergen challenge on BM and lungs, through the in vivo operation of
the iNOS-CD95L pathway. Granulocyte Colony-stimulating Factor (G-CSF), which
stimulates neutropoiesis, mobilizes CD34+ hemopoietic progenitors from BM, and
exerts complex immunoregulatory effects, was shown in our study to have a strong
impact in a murine model of allergic pulmonary inflammation. Like DEC, G-CSF
suppressed BM eosinopoiesis, although through a different mechanism, since DEC
suppressed neutrophilia in the lungs with no effect on BM neutrophilia/neutropoiesis,
while G-CSF promoted neutropoiesis and induced blood neutrophilia, even though it
suppressed eosinopoiesis.
This work was part of the Research Project “Eosinophilia in
Experimental Asthma”, licensed by the Committee on the Ethical Use of
Laboratory Animals (CEUA) at FIOCRUZ, under numbers L010/04 and L002/09.
| Identifer | oai:union.ndltd.org:IBICT/oai:www.arca.fiocruz.br:icict/6402 |
| Date | January 2011 |
| Creators | Pinto, Tulio Queto de Souza |
| Contributors | Elsas, Pedro Paulo, Martins, Patricia Machado Rodrigues e Silva, Alves Filho, José Carlos Farias, Diaz, Bruno Lourenço, Morrot, Alexandre, Monteiro, Carmen Penido, Elsas, Maria Ignez Capella Gaspar |
| Publisher | Instituto Oswaldo Cruz. |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da FIOCRUZ, instname:Fundação Oswaldo Cruz, instacron:FIOCRUZ |
| Rights | info:eu-repo/semantics/openAccess |
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