Study On The Roles Of Relaxin And IL-6in Premature Rupture Of The Membranes

Objective:(1) To investigate the role of relaxin (RLN) in premature rupture of membranes during thethird trimester of pregnancy.(2) Preliminary study to investigate if the mechanisum of RLN lead to PROM is related tochorioamnionitis.(2) To investigate the relationship between serum IL-6and chorioamnionitis.Materials and methods：25serum samples from pregnant women with preterm PROM(PPROM),32samples from PROM of term (TPROM),and31samples from normal pregnancieswere abtained before delivery. The placenta and fetal membranes tissue samples were obtainedafter delivery.(1) The levels of serum RLN2and IL-6was measured by ELISA；(2) The expressions ofrelaxin receptor which is leucine-rich repeat-containing G protein-coupled receptor(LGR7) andIL-6in fetal membrane and placenta was detected by immunohistochemisty streptavidin-pero-sidase(SP) method.Results：(1) The level of RLN2was372.26±143.13pg/ml in PPROM group, was292.73±96.01pg/mlin TPROM group,and241.71±91.57pg/ml in normal group.When compared the level of RLN2inPPROM group with the other two groups respectively, P=0.035and P=0.017.The differenceswere significant.(2) There was no significant difference of serum RLN2level between TPROM group andnormal group(P=0.745).(3) A positive correlation exists between serum IL-6level and the degree of chorioamnionitis(r=0.69,P＜0.001).Risk for chorioamnionitis was almost five fold(OR=5.35, P<0.001,95%CI：0.84~2.52)higher in IL-6level which is more than P50.(4) The level of serum IL-6and the degree of chorioamnionitis have a positive correlationwith the latency to delivery interval from the time of rupture of membranes respectively (P＜0.05).(5)The correlation coefficient of serum RLN2level and the degree of chorioamnionitis was small and not statistically significant(r=0.20,P=0.65).(6) LGR7were positively expressed in placenta and fetal membranes of all threegroups.LGR7were mainly located in the decidua and the membranes of syncytiotrophoblastcell,there were strong signals on the amniotic epithelium and endothelial of capillary vessel.(7) The distribution of relaxin receptor LGR7immunoreactive strong positive rate in threegroups are different(P<0.05).PPROM group is higer than normal group(2=10.501,P=0.001),but when PPROM group and normal group compared with TPROM respectly,therewere no significant differents(P＞0.0167).(8) A positive correlation exists between the expression levels of LGR7in placenta and fetalmembranes and serum RLN2level (rs=0.453,P＜0.001).(9) A positive correlation exists between the expression of IL-6in fetal membrane and thedegree of chorioamnionitis(r=0.645,P＜0.001)Conclusions：(1) Higher RLN during the third trimester of pregnancy may be associated with theoccurrence of PPROM.(2) Higher RLN during the third trimester of pregnancy may be one risk factor of prematurerupture of membranes.(3) RLN level during the third trimester is not related to the degree of chorioamnionitis.(4) Serum IL-6level may be a good detector of chorioamnionitis.