Interleukin-1beta attenuates endothelin B receptor-mediated airway contractions in a murine in vitro model of asthma: roles of endothelin converting enzyme and mitogen-activated protein kinase pathways.
BACKGROUND
Asthma is a chronic airway disease, known to involve several inflammatory mediators. Little is known about how these mediators interact in order to produce or attenuate even basic features of the disease, like airway hyper-reactivity and remodelling. Endothelin-1 (ET-1) and IL-1beta are two mediators suggested to play important roles in the induction of airway inflammation.


OBJECTIVE
To investigate the interactions between ET-1 and IL-1beta, using a novel in vitro model of asthma, focusing on airway smooth muscle contractility.


METHODS
Isolated murine tracheal segments were cultured from 1 to 8 days in the absence and presence of IL-1beta. The subsequent contractile responses to sarafotoxin 6c (S6c) (selective agonist for ETB receptor) and sarafotoxin 6b (S6b) (ETA and ETB receptor agonist) were recorded by a myographs system. In all experiments, ETB receptors were desensitized before the contractile response to S6b was recorded. Thus, the response to S6b is only mediated by ETA receptors in the present study. The mRNA expressions for ET-1 and endothelin (ET) receptors were quantified by real-time PCR.


RESULTS
Organ culture in the presence of IL-1beta attenuated the maximal contraction induced by S6c, but not S6b. This reduction was concentration-dependent and was significant after 2, 4 and 8 days of culture. To investigate the mechanisms behind this, inhibitors for endothelin converting enzyme (ECE) phosphoramidon, c-JUN N-terminal kinase (JNK) SP600125, extracellular-signal-regulated kinase 1/2(ERK 1/2) PD98059 and p38 pathway SB203580 were used. Individually, SP600125 and PD98059, but not SB203580, could partly reverse the reduction induced by IL-1beta. An additional effect was obtained when SP600125 and PD98059 were combined. The mRNA expressions for ET-1 and ETB receptor were up- and down-regulated, respectively, by IL-1beta.


CONCLUSIONS
Presence of IL-1beta in the airways attenuate the contractile response mediated via ETB receptors, an effect dependent on ECE, JNK and ERK 1/2 pathways.
Zhang
Y
Y
Department of Otorhinolaryngology, Laboratory of Clinical and Experimental Allergy Research, Malmö University Hospital, Lund University, Malmö, Sweden. Yaping.Zhang@oron.mas.lu.se
Adner
M
M
Cardell
L-O
LO
D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000276:immunology*; D001249:Asthma / Q000276:immunology*; D004195:Disease Models, Animal; D019332:Endothelin-1 / Q000276:immunology; D000072396:Endothelin-Converting Enzymes; D048049:Extracellular Signal-Regulated MAP Kinases / Q000276:immunology; D007375:Interleukin-1 / Q000032:analysis / Q000276:immunology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000276:immunology; D008297:Male; D008666:Metalloendopeptidases; D051379:Mice; D008807:Mice, Inbred BALB C; D020928:Mitogen-Activated Protein Kinases / Q000276:immunology*; D009119:Muscle Contraction / Q000276:immunology / Q000502:physiology; D009130:Muscle, Smooth / Q000276:immunology / Q000503:physiopathology; D009924:Organ Culture Techniques / Q000379:methods; D012333:RNA, Messenger / Q000032:analysis; D044022:Receptor, Endothelin A / Q000276:immunology; D044023:Receptor, Endothelin B / Q000276:immunology*; D013997:Time Factors; D014132:Trachea / Q000276:immunology / Q000503:physiopathology; D014662:Vasoconstrictor Agents / Q000276:immunology; D014757:Viper Venoms / Q000276:immunology; D048051:p38 Mitogen-Activated Protein Kinases / Q000276:immunology
D019332:Endothelin-1; D007375:Interleukin-1; D012333:RNA, Messenger; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D014662:Vasoconstrictor Agents; D014757:Viper Venoms; C057354:sarafotoxins s6; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; D000072396:Endothelin-Converting Enzymes