Premium
Human bronchial epithelial cells express an active and inducible biosynthetic pathway for leukotrienes B 4 and C 4
Author(s) -
Jame A. J.,
Lackie P. M.,
Cazaly A. M.,
Sayers I.,
Penrose J. F.,
Holgate S. T.,
Sampson A. P.
Publication year - 2007
Publication title -
clinical and experimental allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 154
eISSN - 1365-2222
pISSN - 0954-7894
DOI - 10.1111/j.1365-2222.2007.02733.x
Subject(s) - arachidonate 5 lipoxygenase , cell culture , leukotriene , microbiology and biotechnology , blot , respiratory epithelium , chemistry , biology , enzyme , epithelium , arachidonic acid , immunology , biochemistry , asthma , gene , genetics
Summary Background Human bronchial epithelial cells synthesize cyclooxygenase and 15‐lipoxygenase products, but the 5‐lipoxygenase (5‐LO) pathway that generates the leukotriene (LT) family of bronchoconstrictor and pro‐inflammatory mediators is thought to be restricted to leucocytes. Objective We hypothesized that human bronchial epithelial cells (HBECs) express a complete and active 5‐LO pathway for the synthesis of LTB 4 and LTC 4 , either constitutively or after stimulation. Methods Flow cytometry, RT‐PCR, Western blotting, enzyme immunoassays and reverse‐phase high‐performance liquid chromatography were used to investigate constitutive and stimulated expression of 5‐LO pathway enzymes and the synthesis of LTs B 4 and C 4 in primary HBECs and in the 16‐HBE 14o − cell line. Results Constitutive mRNA and protein expression for 5‐LO, 5‐LO‐activating protein (FLAP), LTA 4 hydrolase and LTC 4 synthase were demonstrated in primary HBECs and in the 16‐HBE 14o − cell line. In 16‐HBE 14o − cells, treatment with calcium ionophore A23187, bradykinin or LPS up‐regulated the expression of these enzymes. The up‐regulation of 5‐LO was blocked by the anti‐inflammatory glucocorticoid dexamethasone. Human bronchial epithelial cells were shown to generate bioactive LTs, with primary HBECs generating 11‐fold more LTC 4 and five‐fold more LTB 4 than 16‐HBE 14o − cells. LT production was enhanced by ionophore treatment and blocked by the FLAP inhibitor MK‐886. Conclusions Expression of an active and inducible 5‐LO pathway in HBEC suggests that damaged or inflamed bronchial epithelium may synthesize LTs that contribute directly to bronchoconstriction and leucocytosis in airway inflammation.