MicroRNAs miR-4535 and miR-1915-5p in amniotic fluid as predictive biomarkers for chorioamnionitis

Assessment of intra-amniotic colonization based on copy numbers of 16S ribosomal deoxyribonucleic acid: A diagnostic and prognostic study

AIM

This study aimed to assess amniotic fluid bacterial load using the copy number of 16S ribosomal deoxyribonucleic acid and to clarify its association with perinatal outcomes.

METHODS

This retrospective diagnostic and prognostic study included 63 patients with preterm labor and suspected intra-amniotic infection who underwent amniocentesis before 34 weeks of gestation. We measured the copy number of 16S ribosomal deoxyribonucleic acid in 1 mL of amniotic fluid using droplet digital polymerase chain reaction and graded infections as Grade (G) 0, 1, 2, or 3. Case-control analysis was performed to compare G3 (N = 29), G1-2 (N = 18), and G0 (N = 17) patients. The main outcome measures were histologic chorioamnionitis, funisitis, and amniocentesis-to-delivery time windows.

RESULTS

The frequency of histologic chorioamnionitis (Stage III) and funisitis was as follows: G3, 86% and 79%; G1-2, 28% and 56%; and G0, 0% and 6%, respectively. The rate of post-amniocentesis delivery within 1 and 2 days was as follows: G3, 62% and 83%; G1-2, 56% and 78%; G0, 13% and 25%, respectively. Comparisons between the G3 and G0 groups revealed significant differences in all criteria (p < 0.05). Additionally, significant differences were noted in pathological inflammatory findings between the G3 and G1-2 groups, as well as in all perinatal outcomes between the G1-2 and G0 groups (p < 0.05).

CONCLUSIONS

Our diagnostic method, based on the copy number of 16S ribosomal deoxyribonucleic acid, supports intra-amniotic colonization assessment, guiding clinical decisions regarding the timing of delivery and potentially informing antimicrobial interventions.

Clinical Significance of miR-4535 and miR-191-5p in Maternal Serum as Independent Biomarkers for Severe Chorioamnionitis

INTRODUCTION

Chorioamnionitis, a perinatal condition caused by fetal membrane inflammation, results in preterm birth, neonatal sepsis, necrotizing enterocolitis, and brain disease in infants. However, predicting maternal and fetal prognoses is challenging. We aimed to assess the relationship between fetal infection induced by severe chorioamnionitis or morbidity and the expression levels　of serum miR-4535, miR-1915-5p, and miR-191-5p levels, which are promising biomarkers for chorioamnionitis, in pregnant women with chorioamnionitis.

METHODS

We collectedserum and amniotic fluid samples from 40 pregnant women with preterm labor and analyzed miR-4535, miR-1915-5p, and miR-191-5p expressions. We calculated the area under the curve (AUC) and Youden index to examine the diagnostic accuracy of infection-induced fetal morbidity.

RESULTS

The serum miR-4535 and miR-191-5p levels were significantly higher in patients with severe chorioamnionitis than in those with chorionitis or sub-chorionitis (P = 0.001 and 0.003, respectively). The AUC of miR-4535 and miR-191-5p (0.864 and 0.836, respectively) indicated their good diagnostic accuracy for severe chorioamnionitis. Significant correlations were observed between serum and amniotic fluid miR-4535 expression (P = 0.011) and serum miR-4535 and miR-191-5p expressions. miR-4535 AUC accurately predicted elevated neonatal immunoglobulin M level (AUC = 0.922) and infection-induced fetal morbidity (AUC = 0.805).

CONCLUSION

Serum miR-4535 and miR-191-5p are associated with infection-induced severe chorioamnionitis and fetal morbidity and maternal infection, respectively.

Diagnostic predictability of miR-4535 and miR-1915-5p expression in amniotic fluid for foetal morbidity of infection

INTRODUCTION

Clinical prediction of foetal inflammatory response syndrome (FIRS) is highly necessary. We have previously reported that miR-4535 and miR-1915-5p are potential biomarkers for severe chorioamnionitis based on the results of microRNA array analysis. Therefore, we evaluated the relationship between foetal morbidity of infection and miR-4535, miR-1915-5p, interleukin (IL)-6, or 16S rDNA copy number levels in amniotic fluid from pregnant women with chorioamnionitis.

METHODS

Amniotic fluid from 57 pregnant women with preterm premature membrane rupture or threatened premature labour were collected. Infants with WBC counts <5000/μL or >20,000/μL, CRP >0.5 mg/mL, or IgM >20 mg/mL at birth received a diagnosis of suspicious foetal infection, and those requiring antibiotic administration for >5 days were considered infected newborns. miR-4535, miR-1915-5p, and IL-6 levels and 16S rDNA copy number were evaluated. Mann-Whitney U test and Dunn's test were used for comparison. The area under the curve (AUC) and Youden index were calculated to examine the diagnostic accuracy of foetal morbidity of infection.

RESULTS

miR-4535, miR-1915-5p, 16S rDNA, and IL-6 were significantly higher in patients with severe chorioamnionitis than in patients with chorionitis or sub-chorionitis (P < 0.05). miR-4535 and miR-1915-5p levels were significantly associated with WBC counts <5000/μL or >20,000/μL, CRP >0.5 mg/mL, or IgM >20 mg/mL (P < 0.05). AUC values of miR-4535 and miR-1915-5p indicated moderate or low accuracy for foetal morbidity of infection, while those of IL-6 and 16S rDNA seemed unreliable.

DISCUSSION

MiR-4535 and miR-1915-5p levels in amniotic fluid may be considered clinically predictive for foetal morbidity of infection.