RESUMO
Bradykinin is known to be present at sites of acute inflammation and to exert its potent inflammatory effects mainly via the bradykinin B2-receptor. Recently, bradykinin dependent processes have been described in cultured human decidual cells, so that bradykinin may expand the list of paracrine factors involved in labour induction. In this paper we present the results of in vitro studies giving evidence that these cells carry the bradykinin B2-receptor. By immunocytochemical methods the receptor protein was localized on decidual cells. Analysis of cellular extracts of cultured decidual cells by RT-PCR showed the presence of the specific mRNA coding for the bradykinin B2-receptor. Binding studies revealed a single, saturable and specific binding site for bradykinin of high affinity (Kd = 0.85 nM, Bmax = 436 fmol/mg protein). Competitive binding studies showed displacement of [3H]-bradykinin by HOE 140, but not by the ligands for the bradykinin B1-receptor, des-Arg10-kallidin and [Leu8]-des-Arg9-bradykinin. The results are consistent with the presence of the bradykinin B2-receptors.
Assuntos
Antagonistas Adrenérgicos beta/metabolismo , Antagonistas dos Receptores da Bradicinina , Bradicinina/análogos & derivados , Bradicinina/metabolismo , Decídua/metabolismo , Receptores da Bradicinina/metabolismo , Sequência de Bases , Ligação Competitiva , Células Cultivadas , Decídua/citologia , Eletroforese em Gel de Poliacrilamida , Feminino , Humanos , Imuno-Histoquímica , Inflamação/metabolismo , Marcação por Isótopo , Trabalho de Parto Induzido , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Gravidez , RNA Mensageiro/análise , RNA Mensageiro/metabolismo , Ensaio Radioligante , Receptor B2 da Bradicinina , Receptores da Bradicinina/genética , Receptores da Bradicinina/imunologia , TrítioRESUMO
Cytokines are known to participate in the process of parturition within a paracrine network in fetal membranes. Bradykinin can also contribute to this process, increasing the release of eicosanoids from decidua cells. In this study, we present evidence for a cross-link between bradykinin and the cytokines. Short and long term cultures of human decidua cells were incubated for 4 h and 24 h with and without bradykinin. IL-6 and IL-8 were determined in the supernatants by ELISA. Results show a large interindividual variability in the basal secretion of IL-6 and IL-8 and a clear increase in the secretion of both ILs in response to bradykinin. By this amplifying effect on cytokine secretion, bradykinin can initiate local and systemic effects of amniochorionitis.
Assuntos
Bradicinina/farmacologia , Decídua/metabolismo , Interleucina-6/metabolismo , Interleucina-8/metabolismo , Células Cultivadas , Feminino , Humanos , GravidezRESUMO
In vitro studies on cultured human decidual cells present evidence for the expression of the bradykinin B2 receptor. This protein was localized by immunocytochemical methods at the cellular plasma membrane and the mRNA was found in cellular extracts by RT-PCR. As a biological effect the release of 14C-AA was observed. Cells that had been incubated for 24 h with 14C-AA showed a bradykinin (BK)-induced release of radioactivity into the culture medium. This response was prevented by the specific bradykinin B2 receptor antagonist HOE 140. Pretreatment with LPS resulted in an increase of the spontaneous release of radioactivity. Adding BK, a further release of about 40-50% was to be shown. We conclude that BK can play a role in the case of bacterial infection of the fetal membranes AND may stimulate labour by an augmented production of prostaglandins.
