Expression and activation of the oxytocin receptor in airway smooth muscle cells: Regulation by TNFalpha and IL-13.
BACKGROUND
During 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 TNFalpha, cytokines known to be important in asthma.


METHODS
Expression 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.


RESULTS
PCR analysis demonstrates that OXTR is expressed in HASMCs under basal conditions and that both interleukin (IL)-13 and tumor necrosis factor (TNFalpha) 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, TNFalpha 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.


CONCLUSIONS
Taken 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.
Amrani
Yassine
Y
Pulmonary, Allergy and Critical Care Division, Department of Medicine, University of Pennsylvania, TRL Suite 1200, 125 South 31st Street, Philadelphia, PA 19104, USA. ya26@le.ac.uk
Syed
Farhat
F
Huang
Chris
C
Li
Katherine
K
Liu
Veronica
V
Jain
Deepika
D
Keslacy
Stefan
S
Sims
Michael W
MW
Baidouri
Hasna
H
Cooper
Philip R
PR
Zhao
Hengjiang
H
Siddiqui
Salman
S
Brightling
Christopher E
CE
Griswold
Don
D
Li
Lily
L
Panettieri
Reynold A
RA
D000328:Adult; D000818:Animals; D001249:Asthma / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D016084:Bronchoconstriction; D001993:Bronchodilator Agents / Q000494:pharmacology; D020013:Calcium Signaling; D016022:Case-Control Studies; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D005470:Fluorometry; D005541:Forced Expiratory Volume; D006801:Humans; D018793:Interleukin-13 / Q000378:metabolism*; D008168:Lung / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008875:Middle Aged; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D010121:Oxytocin / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D018045:Receptors, Oxytocin / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014132:Trachea / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D015854:Up-Regulation; D014797:Vital Capacity; D055815:Young Adult
D001993:Bronchodilator Agents; D018793:Interleukin-13; D012333:RNA, Messenger; D018045:Receptors, Oxytocin; D014409:Tumor Necrosis Factor-alpha; D010121:Oxytocin