Objective To study the expression levels and clinical significance of histone H3 trimethylation at lysine 4(H3K4me3),histone H3 trimethylation at lysine 27(H3K27me3)and modifying enzyme in placental tissue of patients with premature rupture of membranes(PROM)with chorioamnionitis.Methods Clinical data of 95 pregnant women treated in the Xi'an Gaoxin Hospital due to PROM from June 2021 to December 2023 were retrospectively collected,and they were divided into infected group and a non-infected group according to whether they were complicated with histological chorioamnionitis(HCA).Another 30 normal pregnant women were selected as the control group.Placental tissues of all subjects were collected and H3K4me3 and H3K27me3 levels were detected,and the expression levels of H3K4me3,H3K27me3 specific methyltransferase[mixed lineage leukemia protein-1(MLL1),Zeste enhancer homolog 2(EZH2)]and demethyltransferase[lysine-specific demethylase 5B(KDM5B),Jumonji domain-containing protein 3(JMJD3)]were detected by quantitative real-time PCR(qRT-PCR).The expression differences of H3K4me3,H3K27me3 and specific modifiers among the three groups and the correlation with the histological stage of HCA were analyzed.The Receiver operating characteristic curve(ROC)was plotted,the Area under curve(AUC)value was calculated,and H3K4me3 was evaluated.Predictive value of H3K27me3 for concurrent HCA infection.Result Compared with the control group,the levels of H3K4me3(0.08%±0.02%,0.12%±0.03%vs 0.25%±0.06%),MLL1 mRNA(1.32±0.16,1.44±0.23 vs 2.02±0.31),and JMJD3 mRNA(0.78±0.13,0.91±0.15 vs 1.53±0.23)in the infected and non-infected groups were significantly decreased(t=10.939～19.062),while the levels of H3K27me39(0.23%±0.05%,0.15%±0.03%vs 0.10%±0.02%),EZH2 mRNA(1.96±0.26,1.85±0.25 vs 1.15±0.29)and KDM5B(1.46±0.15,1.35±0.18 vs 0.94±0.12)were significantly increased(t=6.077～14.974),and the levels in the infected group were lower/higher than those in the non-infected group(t=2.017～10.688),with statistically significant differences(all P<0.05).There was a significant negatively correlation between H3K4me3 and H3K27me3 levels in placenta tissue of PROM(r=-0.604,P<0.05).The levels of H3K4me3,MLL1 and JMJD3 were negatively correlated with the histological stages of HCA(r=-0.646,-0.489,-0.503,all P<0.05).The levels of H3K27me3,EZH2 and KDM5B were positively correlated with the histological stages of HCA(r=0.632,0.515,0.520,all P<0.05).The cutoffvalues of H3K4me3 and H3K27me3 were 0.10%and 0.19%,respectively.The AUC(95%CI)value of the combined prediction of PROM combined with HCA infection was 0.896(0.882～0.947),and the sensitivity and specificity were 92.14%and 86.23%respectively,which was significantly higher than the diagnosis of a single index.Conclusion The levels of H3K4me3,H3K27me3 and modifying enzymes in the placenta tissue of PROM are closely related to HCA infection and histological stage,which has high clinical prediction value for HCA infection and is expected to be a new biomarker for clinical diagnosis.

Objective To study the expression levels and clinical significance of histone H3 trimethylation at lysine 4(H3K4me3),histone H3 trimethylation at lysine 27(H3K27me3)and modifying enzyme in placental tissue of patients with premature rupture of membranes(PROM)with chorioamnionitis.Methods Clinical data of 95 pregnant women treated in the Xi'an Gaoxin Hospital due to PROM from June 2021 to December 2023 were retrospectively collected,and they were divided into infected group and a non-infected group according to whether they were complicated with histological chorioamnionitis(HCA).Another 30 normal pregnant women were selected as the control group.Placental tissues of all subjects were collected and H3K4me3 and H3K27me3 levels were detected,and the expression levels of H3K4me3,H3K27me3 specific methyltransferase[mixed lineage leukemia protein-1(MLL1),Zeste enhancer homolog 2(EZH2)]and demethyltransferase[lysine-specific demethylase 5B(KDM5B),Jumonji domain-containing protein 3(JMJD3)]were detected by quantitative real-time PCR(qRT-PCR).The expression differences of H3K4me3,H3K27me3 and specific modifiers among the three groups and the correlation with the histological stage of HCA were analyzed.The Receiver operating characteristic curve(ROC)was plotted,the Area under curve(AUC)value was calculated,and H3K4me3 was evaluated.Predictive value of H3K27me3 for concurrent HCA infection.Result Compared with the control group,the levels of H3K4me3(0.08%±0.02%,0.12%±0.03%vs 0.25%±0.06%),MLL1 mRNA(1.32±0.16,1.44±0.23 vs 2.02±0.31),and JMJD3 mRNA(0.78±0.13,0.91±0.15 vs 1.53±0.23)in the infected and non-infected groups were significantly decreased(t=10.939～19.062),while the levels of H3K27me39(0.23%±0.05%,0.15%±0.03%vs 0.10%±0.02%),EZH2 mRNA(1.96±0.26,1.85±0.25 vs 1.15±0.29)and KDM5B(1.46±0.15,1.35±0.18 vs 0.94±0.12)were significantly increased(t=6.077～14.974),and the levels in the infected group were lower/higher than those in the non-infected group(t=2.017～10.688),with statistically significant differences(all P<0.05).There was a significant negatively correlation between H3K4me3 and H3K27me3 levels in placenta tissue of PROM(r=-0.604,P<0.05).The levels of H3K4me3,MLL1 and JMJD3 were negatively correlated with the histological stages of HCA(r=-0.646,-0.489,-0.503,all P<0.05).The levels of H3K27me3,EZH2 and KDM5B were positively correlated with the histological stages of HCA(r=0.632,0.515,0.520,all P<0.05).The cutoffvalues of H3K4me3 and H3K27me3 were 0.10%and 0.19%,respectively.The AUC(95%CI)value of the combined prediction of PROM combined with HCA infection was 0.896(0.882～0.947),and the sensitivity and specificity were 92.14%and 86.23%respectively,which was significantly higher than the diagnosis of a single index.Conclusion The levels of H3K4me3,H3K27me3 and modifying enzymes in the placenta tissue of PROM are closely related to HCA infection and histological stage,which has high clinical prediction value for HCA infection and is expected to be a new biomarker for clinical diagnosis.