Increased secretion of leukemia inhibitory factor by immature airway smooth muscle cells enhances intracellular signaling and airway contractility.
Airway smooth muscle cells (ASMC) play a major role in airway inflammation, hyperresponsiveness, and obstruction in asthma. However, very little is known regarding the relation between inflammatory mediators and cytokines and immature ASMC. The aim of this study was to evaluate 1) the secretion of leukemia inhibitory factor (LIF) (an IL-6 family neurotrophic cytokine) by ASMC; 2) intracellular calcium concentration ([Ca(2+)](i)) signaling; and 3) the effect of LIF on mast cell chemotaxis and rat airway contractility. Immature and adult human ASMC were cultured. ELISA and real-time PCR were performed to assess LIF protein secretion and mRNA production, [methyl-(3)H]thymidine incorporation to quantify ASMC DNA synthesis, a Boyden chamber to evaluate the effect of LIF on mast cell chemotaxis, microspectroflurimetry using indo-1 (at baseline and after stimulation bradykinin, U-46619, histamine, and acetylcholine, in the presence or absence of LIF or TNF-alpha) for [Ca(2+)](i) signaling, and isolated rat pup tracheae to determine the effect of LIF on airway contractility to ACh. TNF-alpha-stimulated immature ASMC produce more LIF mRNA and protein than adult ASMC, although this cytokine induces a moderate increase in DNA synthesis (+20%) in adult ASMC only. Human recombinant LIF exerts no chemotactic effect on human mast cells. In immature ASMC, ACh-induced [Ca(2+)](i) response was enhanced twofold after incubation with LIF, whereas TNF-alpha increased the [Ca(2+)](i) to U-46619 threefold. In TNF-alpha-exposed adult ASMC, [Ca(2+)](i) responses to ACh were of greater magnitude (sixfold increase) than in immature ASMC. Human recombinant LIF increased contractility to ACh by 50% in immature, isolated rat tracheae. Stimulated immature human ASMC greatly secrete LIF, thus potentially contributing to neuroimmune airway inflammation and subsequent remodeling. Increased LIF secretion enhances airway reactivity and [Ca(2+)](i) signaling.
Fayon
Michael
M
Laboratoire de Physiologie Cellulaire Respiratoire, Université Victor Segalen Bordeaux 2, and Institut National de la Santé et de la Recherche Médicale, France. michael.fayon@chu-bordeaux.fr
Rebola
Muriel
M
Berger
Patrick
P
Daburon
Sophie
S
Ousova
Olga
O
Lavrand
Frédéric
F
Moukaïla
Boutchi
B
Pujol
Wilfried
W
Taupin
Jean Luc
JL
Labbé
André
A
Molimard
Mathieu
M
Marthan
Roger
R
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000328:Adult; D000368:Aged; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002465:Cell Movement; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D053605:Leukemia Inhibitory Factor; D008297:Male; D008407:Mast Cells / Q000166:cytology / Q000378:metabolism; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology*; D014132:Trachea / Q000033:anatomy & histology* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D015850:Interleukin-6; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; D014409:Tumor Necrosis Factor-alpha; D014662:Vasoconstrictor Agents; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D002118:Calcium