Leukotriene D4 stimulates collagen production from myofibroblasts transformed by TGF-beta.
BACKGROUND
Airway remodeling has an important role in the pathogenesis of bronchial asthma. Many mediators that influence the pathophysiology of bronchial asthma, especially cysteinyl leukotrienes (CysLTs) and TGF-beta1, are involved in airway remodeling.


OBJECTIVE
To know whether TGF-beta1 alters fibroblast responsiveness to CysLTs, we examined the effects of leukotriene (LT) D4 on collagen production from fibroblasts and from myofibroblasts transformed by TGF-beta1. We also examined whether TGF-beta1 upregulates CysLT1 receptor (CysLT1R) expression in fibroblasts.


METHODS
Concentrations of procollagen in the human fetal lung fibroblast (HFL) 1 cell supernatant were measured by using an enzyme immunoassay kit in the presence or absence of various concentrations of LTD4, TGF-beta1, CysLT1R antagonist, or some combination of these. The mRNA expression of CysLT1R and alpha-smooth muscle actin as a marker of myofibroblasts was measured by means of real-time PCR. Furthermore, protein expression of CysLT1R on fibroblasts was measured by means of flow cytometric analysis.


RESULTS
TGF-beta1 stimulated collagen production from HFL-1 cells, but LTD4 alone did not. LTD4 in combination with TGF-beta1 increased collagen production compared with TGF-beta1 alone. Real-time PCR showed that stimulation with TGF-beta1 significantly upregulated CysLT1R and alpha-smooth muscle actin mRNA expression in HFL-1 cells.


CONCLUSIONS
LTD4 increased collagen production by upregulating CysLT1R induced by TGF-beta1. In the TGF-beta-rich milieu, activated myofibroblasts expressing CysLT1R can respond to CysLTs and produce large amounts of extracellular matrix, thereby contributing to airway remodeling. These data suggest that treatment with leukotriene receptor antagonists might prevent airway remodeling in patients with asthma.
Asakura
Takuma
T
Department of Pulmonary Medicine and Clinical Immunology, Dokkyo University School of Medicine, Japan.
Ishii
Yoshiki
Y
Chibana
Kazuyuki
K
Fukuda
Takeshi
T
D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D017998:Leukotriene D4 / Q000494:pharmacology*; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology; D010446:Peptide Fragments / Q000096:biosynthesis*; D011347:Procollagen / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000032:analysis; D018077:Receptors, Leukotriene / Q000235:genetics / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D008565:Membrane Proteins; D010446:Peptide Fragments; D011347:Procollagen; D012333:RNA, Messenger; D018077:Receptors, Leukotriene; D016212:Transforming Growth Factor beta; C042813:procollagen type I carboxy terminal peptide; D017998:Leukotriene D4; C083169:leukotriene D4 receptor