Objective:We studied the production of the oxytocin receptor and interleukins in human uterine smooth muscle cells cultured in vitro in the presence of cytokines that were shown to be elevated in gestational diseases such as intrauterine infections and chorioamnionitis.
Methods:Human uterine smooth muscle cells were cultured in the absence or presence of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor α (TNFα), or lipopolysaccharide (LPS). Additionally, cells were cultivated under hypoxic conditions (3.5% oxygen). After 6, 12, 24, and 48 hours of incubation, oxytocin receptor mRNA was measured from total RNA using quantitative, competitive reverse transcriptase-polymerase chain reaction. Secreted cytokines (IL-1β, IL-6, or IL-8) were quantitated from supernatants after 6, 12, 24, and 48 hours of stimulation by commercially available enzyme-linked immunosorbent assay.
Results:In nonstimulated cultures basal secretion of IL-1β, IL-6, and IL-8 was detectable. Supplementation of IL-1β induced a statistically significant decrease in oxytocin receptor mRNA abundance, whereas IL-6, TNFα, LPS, or hypoxia did not significantly affect oxytocin receptor gene expression. The cytokines IL-1 and TNFα induced IL-6 and IL-8 release, whereas secretion of the two interleukins was not altered in the presence of LPS or hypoxia. Expression of IL-1β was not significantly induced under inflammatory or hypoxic culture conditions.
Conclusion:The constitutive and cytokine-inducible expression of interleukins from uterine smooth muscle cells suggests that the myometrium may contribute to the overall production of inflammatory mediators in the uterus that are thought to govern term or infection-induced preterm labor. Down-regulation of the oxytocin receptor under IL-1β in myometrial cells may indicate that initiation and maintenance of labor could be partially limited under severe inflammatory conditions such as chorioamnionitis.
1. Romero R, Manogue KR, Mitchell MD, et al. Infection and labor. IV. Cachectin-tumor necrosis factor in the amniotic fluid of women with intraamniotic infection and preterm labor. Am J Obstet Gynecol1989;161:336-341.
2.
2. Romero R, Mazor M, Morrotti R, et al. Infection and labor. VII. Microbial invasion of the amniotic cavity in spontaneous rupture of membranes at term. Am J Obstet Gynecol1992;166:129-133.
3.
3. Romero R, Kadar N, Hobbins JC, Duff GW. Infection and labor: The detection of endotoxin in amniotic fluid. Am J Obstet Gynecol1987;157:815-819.
4.
4. Dudley DJ, Collmer D, Mitchell MD, Trautman MS. Inflammatory cytokine mRNA in human gestational tissues: Implications for term and preterm labor. J Soc Gynecol Investig1996;3:328-335.
5.
5. Sennstrom MB, Ekman G, Westergren-Thorsson G, et al. Human cervical ripening, an inflammatory process mediated by cytokines. Mol Hum Reprod2000;6:375-381.
6.
6. Mitchell MD, Flint AP, Turnbull AC. Stimulation of uterine activity by administration of prostaglandin F-2alpha during parturition in sheep. J Reprod Fertil1976;48:189-190.
7.
7. Saji F, Samejima Y, Kamiura S, Sawai K, Shimoya K, Kimura T. Cytokine production in chorioamnionitis. J Reprod Immunol2000;47:185-196.
8.
8. Mitchell MD, Romero RJ, Avila C, Foster JT, Edwin SS. Prostaglandin production by amnion and decidual cells in response to bacterial products. Prostaglandins Leukot Essent Fatty Acids1991;42:167-169.
9.
9. Pollard JK, Thai D, Mitchell MD. Mechanism of cytokine stimulation of prostaglandin biosynthesis in human decidua. J Soc Gynecol Investig1994;1:31-36.
10.
10. Molnar M, Romero R, Hertelendy F. Interleukin-1 and tumor necrosis factor stimulate arachidonic acid release and phospholipid metabolism in human myometrial cells. Am J Obstet Gynecol1993;169:825-829.
11.
11. Hansen WR, Keelan JA, Skinner SJ, Mitchell MD. Key enzymes of prostaglandin biosynthesis and metabolism. Coordinate regulation of expression by cytokines in gestational tissues: A review. Prostaglandins Other Lipid Mediat1999;57:243-257.
12.
12. Gimpl G, Fahrenholz F. The oxytocin receptor system: Structure, function, and regulation. Physiol Rev2001;81:629-683.
13.
13. Fuchs AR, Fuchs F, Husslein P, Soloff MS, Fernstrom MJ. Oxytocin receptors and human parturition: A dual role for oxytocin in the initiation of labor. Science1982;215:1396-1398.
14.
14. Kimura T. Regulation of the human oxytocin receptor in the uterus: A molecular approach. Hum Reprod Update1998;4:615-624.
15.
15. Kawarabayashi T, Tsukamoto T, Shojo H, Nakamura S, Sugimori H. Changes in responsiveness of freshly isolated longitudinal muscle cells from rat uterus towards oxytocin during gestation: Contractility and calcium signaling. Mol Cell Endocrinol1997;128:77-84.
16.
16. Fuchs AR, Periyasamy S, Alexandrova M, Soloff MS. Correlation between oxytocin receptor concentration and responsiveness to oxytocin in pregnant rat myometrium: Effects of ovarian steroids. Endocrinology1983;113:742-749.
17.
17. Inoue T, Kimura T, Azuma C, et al. Structural organization of the human oxytocin receptor gene. J Biol Chem1994;269:32451-32456.
18.
18. Leung ST, Cheng Z, Sheldrick EL, et al. The effects of lipopolysaccharide and interleukins-1alpha, -2 and -6 on oxytocin receptor expression and prostaglandin production in bovine endometrium. J Endocrinol2001;168:497-508.
19.
19. Rauk PN, Friebe-Hoffmann U. Interleukin-1 beta down-regulates the oxytocin receptor in cultured uterine smooth muscle cells. Am J Reprod Immunol2000;43:85-91.
20.
20. Rauk PN, Chiao JP. Oxytocin signaling in human myometrium is impaired by prolonged exposure to interleukin1-. Biol Reprod2000;63:846-850.
21.
21. Kiss H, Schneeberger C, Tschugguel W, et al. Expression of endothelial (type III) nitric oxide synthase in cytotrophoblastic cell lines: Regulation by hypoxia and inflammatory cytokines. Placenta1998;19:603-611.
22.
22. Helmer H, Hackl T, Schneeberger C, et al. Oxytocin and vasopressin 1a receptor gene expression in the cycling or pregnant human uterus. Am J Obstet Gynecol1998;179:1572-1578.
23.
23. Dudley DJ. Immunoendocrinology of preterm labor: The link between corticotropin-releasing hormone and inflammation. Am J Obstet Gynecol1999;180:251-256.
24.
24. Olson DM, Mijovic JE, Sadowsky DW. Control of human parturition. Semin Perinatol1995;19:52-63.
25.
25. Silver RK, Gibbs RS, Castillo M. Effect of amniotic fluid bacteria on the course of labor in manulliparous women at term. Obstet Gynecol1986;68:587-592.
26.
26. Phaneuf S, Asboth G, Carrasco MP, et al. Desensitization of oxytocin receptors in human myometrium. Hum Reprod Update1998;4:625-633.
27.
27. Uduwela AS, Perera MA, Aiqing L, Fraser IS. Endometrial-myometrial interface: Relationship to adenomyosis and changes in pregnancy. Obstet Gynecol Surv2000;55:390-400.
28.
28. Rhee JW, Zhang L, Ducsay CA. Suppression of myometrial contractile responses to oxytocin after different durations of chronic hypoxia in the near-term pregnant rat. Am J Obstet Gynecol1997;177:639-644.
29.
29. Sehringer B, Schafter WR, Wetzka B, et al. Formation of proinflammatory cytokines in human term myometrium is stimulated by lipopolysaccharide but not by corticotropin-releasing hormone. J Clin Endocrinol Metab2000;85:4859-4865.
30.
30. Elliott CL, Slater DM, Dennes W, Poston L, Bennett PR. Interleukin 8 expression in human myometrium: Changes in relation to labor onset and with gestationl age. Am J Reprod Immunol2000;43:272-277.
31.
31. Todd HM, Dundoo VL, Gerber WR, Cwiak CA, Baldassare JJ, Hertelendy F. Effect of cytokines on prostaglandin E2 and prostacyclin production in primary culures of human myometrial cells. J Matern Fetal Med1996;5:161-167.
32.
32. Rauk PN, Friebe-Hoffmann U, Winebrenner LD, Chiao JP. Interleukin-6 up-regulates the oxytocin receptor in cultured uterine smooth muscle cells. Am J Reprod Immunol2001;45:148-153.
33.
33. Schmid B, Wong S, Mitchell BF. Transcriptional regulation of oxytocin receptor by interleukin-1beta and interleukin-6. Endocrinology2001;142:1380-1385.
