Evaluation of the Prognostic Value of Monocytes and Lymphocyte Phenotyping, Along With Intracellular MCP-1 Expression, to Predict Preterm Delivery for Women Hospitalized for Threat of Preterm Labor Between 24 and 34 Weeks of Amenorrhea: PhenoMAP Study

The threat of preterm labour (PTL) is the first cause of hospitalization in the course of pregnancy. Its diagnostic is based on clinical examination with a positive predictive value of about 40 %. The role of the Monocyte chemotactic protein-1 (MCP-1) in delivery has been suggested by its secretion in the amniotic fluid during labour and by the increase in the expression of its RNA messengers in the peripheral maternal blood. We have also shown that the proportion of MCP-1-expressing monocytes is higher in women with vaginal delivery compared with those with caesarean delivery prior the onset of labour.

OBJECTIVES : Primary To seek link between the respective proportions of circulating maternal monocyte and lymphocyte subpopulations and the true onset of PTL characterised by delivery occurring within 7 days post admission. Secondary: to (1) compare the predictive values of these new markers with those currently used, e.g. quantification of fœtal fibronectin and assessment of cervical length and effacement, (2) Compare the respective proportions of monocytes and lymphocyte subpopulations in maternal blood and fœtal membranes, (3) determine if a correlation exists between the activation markers expressed by maternal monocyte and lymphocyte subpopulations and the neonatal outcomes of preterm infants.

MATERIAL AND METHODS: 200 patients with a singleton pregnancy between 24 and 34 weeks of amenorrhea and complicated PTL, will be prospectively included in the maternity wards of Galway (Ireland) and of Dijon with the support of the perinatal network of Burgundy. A 2X5ml blood sample will be collected upon admission, at D1, D2, D4 and D6 for women who did not deliver within the first 7 days; finally, another blood sample will be drawn upon discharge. After delivery, foetal membranes will be collected to characterize and compare the various monocyte and lymphocyte subpopulations in the maternal blood. The characterization and the study of the level of activation of blood and foetal membrane cells will be performed using flow cytometry technique with suitable markers. The main judgment criteria will be the percentage of monocytes positively expressing MCP-1 for all three monocyte subpopulations ("inflammatory", "residents or patrollers" and "intermediates", according to CD14, CD16, CCR2 and MCP-1 markers. Lymphocyte subpopulations will be assessed using the following markers: CD45, CD3, CD4, CD8 (T lymphocytes), HLA-DR (activated T lymphocytes), CD19 (B lymphocytes), CD16/CD56 (NK Cells), intracellular IFN-gamma (Th1 lymphocytes), intracellular IL-4 (Th-2 lymphocytes), intracellular IL-17 and CCR6 (Th17 lymphocytes), CD4, CD25, Foxp3 and CD127 (Tregs). Univariate statistical analysis of quantitative data will be performed using the Mann and Witney test or ANOVA, after verification of the conditions of application. The comparisons of percentages will be done using Chi-square Pearson tests and the Fisher's exact test, as appropriate. The multivariate analysis will be performed using a stepwise descending analysis.

TRANSLATIONAL DIMENSION: The characterization of the various monocyte and lymphocyte subpopulations in the maternal blood and in the foetal membranes might constitute an " immunological signature " of the labour and therefore validate the relevance of a predictive marker for clinicians.

EXPECTED RESULTS AND PERSPECTIVES: The study of the various monocyte and lymphocyte subpopulations in the maternal blood will allow to better characterise the immunological mechanisms occurring at the start of premature labour and to identity predictive markers of the preterm delivery, to validate prospectively in order to optimize the management of PTL