Heparin fragments induce cervical inflammation by recruiting immune cells through Toll-like receptor 4 in nonpregnant mice.

Inflammation is a hallmark in the human cervix remodelling. A possible candidate inducing the inflammatory driven ripening of the cervix is the matrix component heparan sulphate, which has been shown to be elevated in late pregnancy in the cervix and uterus. Heparin and a glycol-split low molecular weight heparin (gsHep) with low anticoagulant potency has been shown to enhance myometrial contraction and interleukin (IL)-8 production by cervical fibroblasts. The aim of this study was to investigate the mechanism by which heparin promotes cervical inflammation. Wild-type, Toll-like receptor 4 (TLR4), Myeloid differentiation primary response gene 88 (MyD88) and Interferon regulatory factor 3 (IRF3)-deficient mice were treated by deposition of gsHep into the vaginas of nonpregnant mice. To identify which cells that responded to the heparin fragments, a rhodamine fluorescent construct of gsHep was used, which initially did bind to the epithelial cells and were at later time points located in the sub-mucosa. The heparin fragments induced a strong local inflammatory response in wild-type mice shown by a rapid infiltration of neutrophils and to a lesser extent macrophages into the epithelium and the underlying extracellular matrix of the cervix. Further, a marked migration into the cervical and vaginal lumen was seen by both neutrophils and macrophages. The induced mucosal inflammation was strongly reduced in TLR4- and IRF3-deficient mice. In conclusion, our findings suggest that a TLR4/IRF3-mediated innate immune response in the cervical mucosa is induced by gsHep. This low anticoagulant heparin version, a novel TLR4 agonist, could contribute to human cervical ripening during the initiation of labour.

Does low molecular weight heparin shorten term labor?

Dalteparin, a low molecular weight heparin (LMWH), is given to pregnant women with thrombotic disorders. Clinical observations together with the documented changes of heparan sulfate proteoglycans in normal and protracted labor fostered the idea that LMWH shortens delivery time. Labor time was retrospectively determined among nulliparous pregnant women treated with dalteparin because of previous venous thromboembolism (VTE), thrombophilia or acute VTE during current pregnancy. Their labor time was compared to matched untreated controls. The proportion of instrumental deliveries and neonatal outcome was also compared. The dalteparin-treated group showed a significantly (30%) shorter labor time compared to matched controls. Total instrumental deliveries were the same in the two groups but operative intervention due to protracted labor was significantly less common in dalteparin-treated women. There was no difference in neonatal outcome. Dalteparin most likely shortens parturition time and may decrease the number of operative interventions due to protracted labor.

Low molecular weight heparin stimulates myometrial contractility and cervical remodeling in vitro.

OBJECTIVES: The low molecular weight heparin, Dalteparin, shortens human labor time. The aim of this study was to investigate if the mechanism behind this effect involves myometrial contractility and cervical ripening and if the anticoagulative activity is necessary for its effect. DESIGN: Experimental in vitro study. SETTING: Lund University and Karolinska Institute, Sweden. METHODS: The effect of low molecular weight heparins with or without anticoagulative properties on myometrial contractility was measured in vitro on smooth muscle strips from biopsies obtained at elective cesarean sections. The effects on cervical ripening were assessed in cervical fibroblasts cultured from explants of cervical biopsies obtained at delivery. MAIN OUTCOME MEASURES: Mean force and number of contractions in uterine smooth muscle strips and interleukin-8 (IL-8) secretion in cervical fibroblasts. RESULTS: Myometrial smooth muscle strips pretreated with low molecular weight heparins showed increased contractile activity compared to untreated smooth muscle strips. Secretion of IL-8 from cultured cervical fibroblasts was significantly increased after treatment with low molecular weight heparin. Both these effects were independent of anticoagulative activity of the low molecular weight heparin. CONCLUSIONS: A possible underlying mechanism for the shortened labor time after low molecular weight heparin treatment is enhanced myometrial contractility and an increased IL-8 secretion in cervical fibroblast, mimicking the final cervical ripening in vivo. Our data support the notion that anticoagulant activity is not required to promote labor.

Differences in heparan sulfate production in cervical fibroblast cultures from women undergoing term and preterm delivery.

OBJECTIVE: An extensive remodeling of the human cervical connective tissue occurs throughout pregnancy, with a decrease in the total concentration of collagen and proteoglycans. We hypothesized that the profound changes in proteoglycan production in the cervix would be seen in corresponding cervical fibroblasts as well. METHODS: Cervical biopsies were obtained from five non-pregnant women, five women undergoing elective Cesarean section, six women directly after spontaneous term parturition and four directly after spontaneous preterm parturition. By explant technique, fibroblasts were cultured from the biopsies. Subcultures of the primary fibroblasts were treated with antibodies to heparan sulfate proteoglycans and labeled with radioactive sulfate. The labeled proteoglycans were purified by ion-exchange chromatography and separated by gel electrophoresis. RESULTS: Proteoglycan production was reduced by 50% in fibroblasts obtained from term and preterm women. In comparison to equivalent control cultures from non-pregnant women, this decline was significant. Production of the proteoglycans biglycan and perlecan was similar in term partal and preterm partal cell cultures. Biglycan production was significantly reduced (by 40%) and perlecan production was significantly induced (by 60%) compared to control cultures. Fibroblast cultures established from women with preterm delivery had significantly higher production of heparan sulfate proteoglycans than those obtained from non-pregnant donors. Heparan sulfate proteoglycans were localized to cell membranes and intracellular compartments. CONCLUSIONS: The changes in proteoglycan production in the human pregnant cervix can also be seen in corresponding cervical fibroblasts. Term partal and preterm partal cells differed from their non-pregnant counterpart, which suggests a role for proteoglycans in cervical ripening.