RESUMO
PROBLEM: Human labour is an inflammatory process with a heavy infiltration of immune cells into the myometrium and cervix induced by local chemokine production. Myometrial cells also express chemokine receptors, but there is little information about their behaviour or function during pregnancy and labour. METHOD OF STUDY: We studied the behaviour of the receptors (CCR2, CXCR1 and CXCR2) for the CCL2 and CXCL8 in human myometrium, because both have been shown to be important in labour. RESULTS: We found that there was a significant decline in the mRNA expression of all three receptors in the upper segment and a similar trend in the lower segment with the onset of term labour (TL). Chemokine receptor mRNA expression was increased by stretch, reduced by oxytocin and PGF(2α) acting via phospholipase C (PLC). CXCR2 declined with exposure to CXCL8, consistent with the negative relationship observed in labouring myometrial tissue. The mRNA changes were confirmed by western analysis and flow cytometry. CONCLUSION: These data show that myometrial chemokine receptor expression is reduced with the onset of term labour probably in response to the increased activity of chemokines, oxytocin and PGF(2α) .
Assuntos
Citocinas/fisiologia , Trabalho de Parto/efeitos dos fármacos , Miométrio/imunologia , Ocitocina/fisiologia , Prostaglandinas/fisiologia , Receptores CCR2/biossíntese , Receptores de Interleucina-8A/biossíntese , Receptores de Interleucina-8B/biossíntese , Células Cultivadas , Citocinas/farmacologia , Dinoprosta/farmacologia , Dinoprosta/fisiologia , Dinoprostona/farmacologia , Dinoprostona/fisiologia , Regulação para Baixo , Feminino , Humanos , Trabalho de Parto/imunologia , Mecanotransdução Celular , Miométrio/efeitos dos fármacos , Trabalho de Parto Prematuro/imunologia , Ocitocina/farmacologia , Gravidez , Prostaglandinas/farmacologia , Receptores CCR2/genética , Receptores de Interleucina-8A/genética , Receptores de Interleucina-8B/genéticaRESUMO
Both human preterm labor (PTL) and term labor are consistently associated with a chemokine-induced inflammatory infiltration of the myometrium. However, what regulates myometrial chemokine expression and whether the increase in expression precedes the onset of labor, and so may have a role in its causation, or occurs after, and is simply a consequence of labor, is uncertain. Therefore, we assessed 1) chemokine expression in nonlaboring and laboring myometrial samples obtained at and before term and 2) the factors that regulate myometrial chemokine expression. We found that term labor was characterized by an increase in CXCL8 and CCL2 in both upper and lower segments, whereas PTL was associated with a distinct pattern of chemokine expression, with increases in CCL5, CXCL5, and CCL20 in the lower segment myometrium only. Further, we found that chemokine expression in myometrial cell cultures was increased by stretch and inflammatory cytokines and reduced by prostglandins and oxytocin and that the primary mediator of stretch and cytokine effects was nuclear factor κB (NF-κB) and to a lesser extent MAPK. These data show that PTL appears to be associated with a distinct pattern of chemokine expression, that stretch and cytokines both drive myometrial chemokine expression primarily via activation of NF-κB. These data suggest that the modulation of NF-κB activity may be of potential benefit in the management of PTL.
Assuntos
Quimiocinas/metabolismo , Citocinas/metabolismo , Mediadores da Inflamação/metabolismo , Miométrio/metabolismo , NF-kappa B/metabolismo , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Quimiocina CCL20/genética , Quimiocina CCL20/metabolismo , Quimiocina CCL5/genética , Quimiocina CCL5/metabolismo , Quimiocina CXCL5/genética , Quimiocina CXCL5/metabolismo , Quimiocinas/genética , Citocinas/genética , Feminino , Humanos , Interleucina-8/genética , Interleucina-8/metabolismo , Trabalho de Parto/genética , Trabalho de Parto/metabolismo , Trabalho de Parto Prematuro/genética , Trabalho de Parto Prematuro/metabolismo , Gravidez , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transdução de Sinais , Estresse MecânicoRESUMO
Preterm labour (PTL) is the most important cause of neonatal morbidity and mortality. While some causes have been identified, the mechanisms involved remain elusive. This study investigates whether term labour (TL) is an appropriate model for PTL by examining pro-labour gene expression, using quantitative rtPCR, and protein synthesis, using Western analysis, in preterm and term myometrial samples obtained from the upper and lower uterine segments before and after the onset of labour. In the lower segment, the levels of prostaglandin H synthase type-2 (PGHS-2), interleukin-1beta (IL-1beta), IL-6 and IL-8 mRNA expression were significantly higher in TL compared with PTL samples. Compared with non-labour controls, the expression of IL-1beta and IL-8 mRNA was increased in both PTL and TL samples and the expression of PGHS-2 and IL-6 mRNA was increased in TL samples only. In the upper segment, there were no differences between PTL and TL samples and the mRNA expression of PGHS-2 and IL-1beta was increased in TL compared with term no labour samples. No effect of PTL or TL was seen on either oxytocin receptor or connexin-43 mRNA expression or protein levels. The multiple regression analysis and studies in primary cultures of uterine myocytes suggest that the inflammatory cytokines, IL-1beta and tumour necrosis factor-alpha, are the most important regulators of PGHS-2 and IL-8. Our data show that preterm and term labouring myometrium are significantly different and that the most marked labour-induced changes in gene expression are in the lower segment. These changes may occur in response to the release of inflammatory cytokines by the labour-associated inflammatory infiltration.
