title: Activation of the TNF alpha-p55 receptor induces myocyte proliferation and modulates agonist-evoked calcium transients in cultured human tracheal smooth muscle cells.
abstract: Evidence suggests that cytokines may modulate smooth muscle cell function in a variety of inflammatory diseases. In the present study, we characterized the specific receptor subtypes that mediate tumor necrosis factor alpha (TNF alpha) effects on myocyte proliferation and on agonist-induced calcium transients in cultured human tracheal smooth muscle cells (TSMC). Pretreatment of human TSMC with TNF alpha potentiated cytosolic calcium [(Ca2+)i] transients evoked by carbachol. In a similar manner, selective TNF alpha-p55 receptor agonists such as htr-9, an activating monoclonal antibody, or a recombinant TNF-p55 (rTNF-p55), which specifically activates the TNF alpha-p55 receptor but not the TNF alpha-p75 receptor, also augmented [Ca2+]i transients evoked by carbachol. In parallel experiments, TNF alpha, rTNF alpha-p55, and htr-9 induced human TSMC proliferation as measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Interestingly, activation of the TNF alpha-p75 receptor with a selective agonist, recombinant TNF alpha-p75 (rTNF alpha-p75), or inhibition of the TNF alpha-p75 receptor with utr-1, an inhibitory anti-TNF alpha-p75 receptor antibody, had no effect on TNF alpha-augmented calcium transients or on myocyte growth. To further confirm the receptor specificity of these findings, immunocytochemical studies were performed using receptor-specific antibodies. These studies demonstrated marked cell-surface expression of the TNF alpha-p55 receptor compared with expression of the TNF alpha-p75 receptor on human TSMC. Taken together, our results suggest that TNF alpha modulates agonist-induced calcium transients and induces human TSMC proliferation by specific activation of the TNF alpha-p55 receptor. Further studies addressing the cellular and molecular mechanisms regulating cytokine modulation of airway smooth muscle function may provide new insight into mechanisms that induce airway hyperresponsiveness in asthma.
authors.affiliation: INSERM U425, Faculté de Pharmacie, Illkirch, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Amrani
authors.forename: R A
authors.initials: RA
authors.lastname: Panettieri
authors.forename: N
authors.initials: N
authors.lastname: Frossard
authors.forename: C
authors.initials: C
authors.lastname: Bronner
mesh_terms: D000918:Antibody Specificity; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured / Q000378:metabolism / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D009130:Muscle, Smooth / Q000737:chemistry* / Q000166:cytology* / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D011994:Recombinant Proteins / Q000494:pharmacology; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D014132:Trachea / Q000166:cytology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D015703:Antigens, CD; D002120:Calcium Channel Agonists; D004791:Enzyme Inhibitors; D007476:Ionophores; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D011994:Recombinant Proteins; D013729:Terpenes; D014409:Tumor Necrosis Factor-alpha; D015759:Ionomycin; D019284:Thapsigargin; D002217:Carbachol; D002118:Calcium