The distribution of beta-adrenoceptors in human cervix

The association of beta-2 adrenoceptor genotype with short-cervix mediated preterm birth: a case-control study

OBJECTIVE

To determine whether β2 -adrenoceptor (β2 AR) genotype is associated with shortening of the cervix or with preterm birth (PTB) risk among women with a short cervix in the second trimester.

DESIGN

A case-control ancillary study to a multicentre randomised controlled trial.

SETTING

Fourteen participating centres of the Maternal-Fetal Medicine Units Network of the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

POPULATION

Four hundred thirty-nine women, including 315 with short cervix and 124 with normal cervical length.

METHODS

Nulliparous women with cervical length <30 mm upon a 16-22-week transvaginal sonogram and controls frequency-matched for race/ethnicity with cervical lengths ≥40 mm were studied. β2 AR genotype was determined at positions encoding for amino acid residues 16 and 27.

MAIN OUTCOME MEASURES

Genotype distributions were compared between case and control groups. Within the short cervix group, pregnancy outcomes were compared by genotype, with a primary outcome of PTB <37 weeks.

RESULTS

Genotype data were available at position 16 for 433 women and at position 27 for 437. Using a recessive model testing for association between short cervix and genotype, and adjusted for ethnicity, there was no statistical difference between cases and controls for Arg16 homozygosity (OR 0.7, 95% CI 0.4-1.3) or Gln27 homozygosity (OR 0.9, 95% CI 0.3-2.7). Among cases, Arg16 homozygosity was not associated with protection from PTB or spontaneous PTB. Gln27 homozygosity was not associated with PTB risk, although sample size was limited.

CONCLUSIONS

β2 AR genotype does not seem to be associated with short cervical length or with PTB following the second-trimester identification of a short cervix. Influences on PTB associated with β2 AR genotype do not appear to involve a short cervix pathway.

Beta-2 adrenoceptor genotype and progress in term and late preterm active labor

OBJECTIVE

We sought to evaluate whether beta-2 adrenoceptor (β2AR) genotype at a functional polymorphic site encoding for amino acid residue 16 influences rate of cervical dilatation in term and late preterm active labor.

STUDY DESIGN

Subjects who underwent vaginal delivery at ≥34 weeks' gestational age from May 2006 through August 2007 were identified. Each subject had provided venous blood from which DNA was extracted for β2AR genotyping. Digital cervical examinations with paired examination times were collected from intrapartum records. Rate of cervical dilatation in active labor was determined using linear regression. Rates were compared between genotype groups.

RESULTS

Among 401 subjects with satisfactory genotype and intrapartum data, overall rate of active labor was 0.76±0.01 cm/h. When labor was compared by genotype, homozygous Arg/Arg16 subjects progressed at a slower rate (0.64±0.03 cm/h) than all other pooled genotypes (0.8±0.02 cm/h, P<.001).

CONCLUSION

Homozygous β2AR genotype encoding for Arg/Arg16 was associated with slower progress in active labor.

Epidermal growth factor facilitates epinephrine inhibition of P2X7-receptor-mediated pore formation and apoptosis: a novel signaling network

Epidermal growth factor (EGF), epinephrine, and the P2X7 receptor system regulate growth of human uterine cervical epithelial cells, but little is known about how these systems intercommunicate in exerting their actions. The objective of this study was to understand the mechanisms of EGF and epinephrine regulation of growth of cervical cells. Treatment of cultured CaSki cells with 0.2 nM EGF increased cell number via a PD98059-sensitive pathway. Treatment with 2 nM epinephrine increased cell number, and the effect was facilitated by cotreatment with EGF. Whereas the effect of EGF alone involved up-regulation of [3H]-thymidine incorporation and an increase in cell proliferation, the effect of epinephrine was mediated by inhibition of apoptosis. Epinephrine inhibited apoptosis induced by the P2X7 receptor ligand 2',3'-0-(4-benzoylbenzoyl)-ATP, by attenuation of P2X7 receptor plasma membrane pore formation. Cotreatment with EGF facilitated epinephrine effect via a phosphoinositide 3-kinase-dependent mechanism. CaSki cells express the beta2-adrenoceptor, and the epinephrine antiapoptotic effect could be mimicked by beta2-adrenoceptor agonists and by activators of adenylyl cyclase. Likewise, the effect could be blocked by beta2-adrenoceptor blockers and by the inhibitor of protein kinase-A H-89. Western immunoblot analysis revealed that epinephrine decreased the levels of the glycosylated 85-kDa form of the P2X7 receptor and increased receptor degradation, and that EGF potentiated these effects of epinephrine. EGF did not affect cellular levels of the beta2-adrenoceptor. In contrast, EGF, acting via the EGF receptor, augmented beta2-adrenoceptor recycling, and it inhibited beta2-adrenoceptor internalization via a phosphoinositide 3-kinase-dependent mechanism. We conclude that, in cervical epithelial cells, EGF has a dual role: as mitogen, acting via the MAPK/MAPK kinase pathway, and as an antiapoptotic factor by facilitating epinephrine effect and resulting in greater expression of beta2-adrenoceptors in the plasma membrane. These findings underscore a novel signaling network of communication between the receptor tyrosine kinases, the G protein-coupled receptors, and the purinergic P2X7 receptor.