Clinical Trial Details
— Status: Recruiting
Administrative data
NCT number |
NCT06430398 |
Other study ID # |
0011882 |
Secondary ID |
|
Status |
Recruiting |
Phase |
|
First received |
|
Last updated |
|
Start date |
March 1, 2023 |
Est. completion date |
July 1, 2026 |
Study information
Verified date |
May 2024 |
Source |
Istituto Clinico Humanitas |
Contact |
n/a |
Is FDA regulated |
No |
Health authority |
|
Study type |
Observational
|
Clinical Trial Summary
Preeclampsia (PE) is a leading cause of maternal-fetal morbidity and mortality, affecting
3-8% of pregnancies and causing over 76,000 maternal deaths annually. PE is characterized by
high blood pressure and proteinuria or organ damage/intrauterine growth restriction (IUGR).
There are two phenotypes: placental PE, caused by abnormal trophoblast invasion, often
leading to early pregnancy complications and IUGR, and metabolic PE, associated with maternal
metabolic issues like visceral obesity and metabolic syndrome, leading to low-grade
inflammation and insulin resistance.
Recent research highlights the role of maternal gut microbiota in these conditions,
suggesting that gut dysbiosis-altered microbial balance-can influence systemic immune
responses and contribute to PE. This study aims to characterize the maternal gut microbiota
in the two PE phenotypes to better understand their distinct etiologies and improve
prediction and prevention strategies.
Description:
Preeclampsia (PE) is one of the leading causes of maternal-fetal morbidity and mortality. It
is defined as systolic blood pressure (SBP) ≥ 140 and diastolic blood pressure (DBP) ≥ 90 in
two consecutive measurements taken 6 hours apart, associated with proteinuria >300 mg/24 h or
2++ detected by a urine dipstick, or the presence of organ damage or intrauterine growth
restriction (IUGR). Preeclampsia complicates 3-8% of pregnancies and is responsible for over
76,000 maternal deaths each year.
Scientific evidence suggests the existence of two distinct phenotypes of the condition:
placental preeclampsia and metabolic preeclampsia. The first phenotype is caused by abnormal
invasion of the maternal endometrium by the trophoblast, leading to preeclampsia often
associated with early presentation in pregnancy, intrauterine growth restriction, and the
need for delivery at early gestational ages. Fetal growth restriction due to likely placental
insufficiency is defined by the Delphi criteria: estimated fetal weight (EFW) < 3rd
percentile, or at least two of the following criteria: EFW < 10th percentile, a decrease in
EFW by at least 40 percentiles even if above the 10th percentile, cerebro-placental ratio
(CPR) ≤ 1 (5th percentile) or umbilical artery pulsatility index (PI) ≥ 95th percentile,
uterine arteries with PI ≥ 95th percentile.
Beyond the hypothesis of abnormal placentation at the beginning of pregnancy, it is now
recognized that maternal metabolic risk factors may cause placental malfunction later in
pregnancy. The second phenotype is rooted in a metabolic basis, representing about 4% of
hypertensive disorders of pregnancy (HDP), and depends on a maternal predisposition in
patients with visceral obesity and metabolic syndrome. Visceral obesity is associated with a
state of chronic low-grade inflammation, which contributes to insulin resistance, altered
glucose homeostasis, and cardiovascular complications.
Metabolic preeclampsia occurs in patients with a pre-existing state of low-grade inflammation
related to trunk obesity and metabolic syndrome, compounded by the inflammation and insulin
resistance typical of pregnancy. Scientific evidence has shown that in the placentas of these
patients, there is a higher density of tertiary villi compared to physiological pregnancies,
with reduced intervillous spaces, resulting in hypoperfusion and oxidative stress.
Differentiation between these clinical phenotypes can be identified during pregnancy by
studying fetal growth as an index of placental function, as well as maternal cardiovascular
adaptation to pregnancy in terms of hemodynamic parameters and body water, and finally by
studying placental histology after delivery. Hypertensive disorders of pregnancy associated
with intrauterine growth restriction (HDP-IUGR) and hypertensive disorders of pregnancy with
appropriate-for-gestational-age fetuses (HDP-AGA) are distinguished.
Currently, starting from the first trimester of pregnancy, maternal cardiovascular and
hemodynamic function can be assessed with a non-invasive and harmless method for both mother
and fetus using the USCOM (Ultra Sonic Cardiac Output Monitor) system. This provides
real-time data on numerous central and peripheral hemodynamic parameters such as cardiac
output and stroke volume beat-to-beat. It allows measurement of cardiac output from both the
right and left heart, systolic stroke volume (SV), systemic vascular resistance, and
inotropic index. Its use in pregnancy has already been validated and will significantly
enhance the quality of care provided to women with high-risk or pathological pregnancies.
However, there is still discordance among scientific societies regarding the classification
of preeclampsia and its potential different clinical phenotypes, making a personalized
clinical approach to this condition challenging. While diagnostic criteria have been codified
by major national and international scientific societies, it is increasingly important to
identify high-risk groups early on, not only to plan a close diagnostic follow-up but also to
define appropriate therapeutic strategies based on the etiology.
Recently, a screening method at 11-13 weeks of gestation has been developed, capable of
predicting 75% of pregnancies that will develop preterm preeclampsia (<37 weeks of
gestation). This is based on a risk calculation algorithm that combines measurements of
weight and height, mean arterial pressure measured with automated devices, blood sampling for
PLGF levels, and Doppler ultrasound measurement of the mean pulsatility index (PI) of the
uterine arteries. However, this screening can only predict a subset of patients who will
develop preeclampsia <37 weeks and who may benefit from aspirin administration if taken at
doses >100mg and before 16 weeks.
To date, it is still not possible to effectively predict and prevent preeclampsia manifesting
>37 weeks, and the etiology of this serious obstetric condition remains a topic of debate and
scientific research. Among emerging etiological hypotheses, numerous scientific publications
support that an alteration in maternal immunity and immune tolerance underlies hypertensive
disorders in pregnancy. Studies on animal models have shown that the activation and expansion
of aberrant B cells can trigger inflammatory events leading to preeclampsia. IFN-γ produced
by NK cells plays an essential role in spiral arterial remodeling in murine pregnancy.
Studies on NK cell-deficient mice have shown defective placental vascular remodeling,
characterized by narrow vascular lumens, thick vascular walls, and retention of vascular
smooth muscle actin.
Recent discoveries suggest that changes in the maternal gut microbiota, a commensal microbial
community capable of modulating the host's immune responses, underlie these immunological
alterations. It has been widely described how changes in the diversity and composition of the
host gut microbiota-a phenomenon called "dysbiosis," commonly induced by dietary changes or
antibiotic treatment-affect systemic immune responses and can disrupt the balance between
pro-inflammatory and anti-inflammatory activation. Gut dysbiosis can be associated with
excessive weight gain during pregnancy and promote metabolic disorders such as gestational
diabetes and preeclampsia, with risks of metabolic alterations in the newborn.
Based on these premises, this study aims to define the characteristics of the maternal gut
microbiota in the two different clinical phenotypes of preeclampsia: placental preeclampsia,
where the hypertensive disorder is associated with growth restriction, and metabolic
preeclampsia, where the hypertensive disorder is associated with a fetus of appropriate
weight for gestational age.