Expression and activation of the oxytocin receptor in airway smooth muscle cells: Regulation by TNFα and IL-13

Abstract

BackgroundDuring pregnancy asthma may remain stable, improve or worsen. The factors underlying the deleterious effect of pregnancy on asthma remain unknown. Oxytocin is a neurohypophyseal protein that regulates a number of central and peripheral responses such as uterine contractions and milk ejection. Additional evidence suggests that oxytocin regulates inflammatory processes in other tissues given the ubiquitous expression of the oxytocin receptor. The purpose of this study was to define the role of oxytocin in modulating human airway smooth muscle (HASMCs) function in the presence and absence of IL-13 and TNFα, cytokines known to be important in asthma.MethodExpression of oxytocin receptor in cultured HASMCs was performed by real time PCR and flow cytomery assays. Responses to oxytocin was assessed by fluorimetry to detect calcium signals while isolated tracheal rings and precision cut lung slices (PCLS) were used to measure contractile responses. Finally, ELISA was used to compare oxytocin levels in the bronchoalveloar lavage (BAL) samples from healthy subjects and those with asthma.ResultsPCR analysis demonstrates that OXTR is expressed in HASMCs under basal conditions and that both interleukin (IL)-13 and tumor necrosis factor (TNFα) stimulate a time-dependent increase in OXTR expression at 6 and 18 hr. Additionally, oxytocin increases cytosolic calcium levels in fura-2-loaded HASMCs that were enhanced in cells treated for 24 hr with IL-13. Interestingly, TNFα had little effect on oxytocin-induced calcium response despite increasing receptor expression. Using isolated murine tracheal rings and PCLS, oxytocin also promoted force generation and airway narrowing. Further, oxytocin levels are detectable in bronchoalveolar lavage (BAL) fluid derived from healthy subjects as well as from those with asthma.ConclusionTaken together, we show that cytokines modulate the expression of functional oxytocin receptors in HASMCs suggesting a potential role for inflammation-induced changes in oxytocin receptor signaling in the regulation of airway hyper-responsiveness in asthma.

Phenotype of asthmatics with increased airway S-nitrosoglutathione reductase activity

“…Primary human airway smooth muscle (HASM) cells from the Panettieri lab were cultured as previously described (25). Normal human bronchial epithelial cells (NHBE, Lonza) were grown as monolayers, and primary human bronchial epithelial cells were grown at air-liquid interface as previously described (26).…”

Sex steroid signaling: Implications for lung diseases

“…Progesterone is known to inhibit oxytocin receptor binding in uterine smooth muscle to maintain quiescence during pregnancy (Grazzini et al, 1998). Oxytocin increases cytosolic Ca 2+ in human ASM cells and promotes airway narrowing in murine tracheal rings (Amrani et al, 2010). Accordingly, progesterone may indirectly influence ASM by interference with oxytocin binding: an effect to be demonstrated.…”

Glucocorticoid and TNF signaling converge at A20 (TNFAIP3) to repress airway smooth muscle cytokine expression

“…Primary HASM cells were derived from two donors with normal ASM (HASM1, a 20-yr-old man; HASM2, a 54-yr-old woman) and two patients with FA (FA-HASM1, a 15-yr-old girl; FA-HASM2, a 48-yr-old woman) as described previously (3). No recent corticosteroid use was noted for any of the donors.…”