USE OF THE PROTEIN S100B AS A BIOMARKER TO DETECT RISK OF BRAIN DAMAGE IN A BIRTH CONSIDERED NORMAL PERIOD

Description

[0001] The invention relates to the field of obstetrics, more particularly to childbirth.

[0002] The invention finds a particularly advantageous application in the identification of risks of brain damage, during deliveries considered normal, in asymptomatic newborns, in the absence of fetal distress.

[0003] By " brain injury "This refers to cerebral hemorrhages, edema and ischemia.

[0004] By " childbirth "Here we refer to all the phenomena that lead to the expulsion of the fetus and its annexes (placenta, amniotic fluid and membranes). During childbirth, the part of the fetus that occupies the area of ​​the pelvic inlet to engage and then evolve according to its own mechanism is called the presentation."

[0005] By " normal delivery"Eutocic delivery" refers here to a normal birth, which results, through the sole influence of natural processes, in the expulsion of the child vaginally from the mother's genital tract, the pregnancy having reached the theoretical term of 28 weeks of amenorrhea. The course of a normal delivery includes periods known as labor.

[0006] In a normal delivery, fetal distress is considered to have no impact on the child.

[0007] By " fetal distress "This refers to a pathological condition of the fetus due to hypoxia or insufficient nutrition.

[0008] By " asymptomatic newborn "This refers to a newborn showing no signs of acidosis or hypoxia, and in particular having a normal Apgar score and a normal umbilical cord blood pH.

[0009] By its very definition, a normal delivery is declared only after the birth, based on retrospective data on the progress of labor and the condition of the newborn.

[0010] A normal delivery is contrasted with a dystocic delivery, which results in difficulties or the impossibility of vaginal delivery. Dystocia can result from a difficult presentation, such as shoulder or breech presentation. Dystocia can also result from abnormalities in uterine contractions and cervical dilation, or be of skeletal origin (symmetrical or asymmetrical narrowed pelvises), or even of fetal origin (hydrocephalus, large fetus). Cephalic presentations are the most frequent, accounting for approximately 95% of cases, and include vertex presentation (in which the occiput is the first part of the head to descend), face presentation (in which the entire face, including the chin, is the first part of the head to descend), and brow presentation, which is intermediate between vertex and face presentations.Breech presentations are rare, occurring in approximately 4% of births. The same is true for transverse and oblique presentations (shoulder presentations).

[0011] In a normal delivery, under the effect of uterine contractions, the fetal body will pass through the stages of the pelvic-genital passage (upper strait, pelvic cavity, lower strait, perineum).

[0012] A normal delivery is contrasted with a delivery involving instrumental extraction, using forceps (for example, Tarnier, Pajot, or Demelin-Suzor forceps), spatulas (for example, Thierry spatula), vacuum extraction, or an Odon device. While rare, fetal injuries resulting from the use of these extractors are known, particularly skull fractures and cerebro-meningeal lesions, occurring during difficult or forceful forceps maneuvers, or when the vacuum extraction is not perpendicular to the axis of the cup.

[0013] In a normal delivery, the first stage of labor leads to dilation of the cervix. This initial stage is marked by the onset of uterine contractions. The second stage extends from this dilation to expulsion. After the birth of the child, the third stage occurs, culminating in the expulsion of the placenta (placental delivery), followed by the fourth stage, which lasts until the mother's vital signs stabilize.

[0014] The second stage of labor begins with engagement, that is, the passage of the presenting part through the pelvic inlet. Engagement is followed by the descent and rotation of the fetal head within the pelvic cavity, and then by expulsion. It is generally accepted that the accommodation of the fetal head to the pelvic inlet involves four mechanisms: cephalic flexion, oblique orientation of the fetal head, lateral tilt or asynclitism, and plastic deformations of the fetal head (occipito-anterior, occipito-posterior, frontal, and facial). These four mechanisms occur almost simultaneously, and not all are observed: asynclitism and plastic deformations of the head are optional in normal deliveries.Cranial bone deformities due to overlapping of bones or changes in their curvatures can occur when labor has been prolonged, and are often encountered in dystocic deliveries.

[0015] The development of antenatal and neonatal imaging, the development of antenatal diagnostics and methods of monitoring during labour, the generalization of epidural analgesia techniques, the reduction in the number of maternity wards and the resulting concentration of material resources and know-how (see perinatal decree in France), the increasing proportion of births by cesarean section, the development of medically assisted reproduction (MAR) techniques have changed the expectations of parents.

[0016] Parents see childbirth as an act closely monitored by a medical team, with risks that must be identified and quantified.

[0017] However, the course of childbirth is not currently perfectly predictable, and the trial of labor is common.

[0018] At the same time, improvements in women's social status and education levels are associated with a decrease in the number of children per family and an increase in the average age of mothers having their first child. For example, according to INSEE, the average age of mothers having their first child in France was 26 in 1975 and 30.6 in 2015.

[0019] Childbirth is thus increasingly becoming a unique experience for parents.

[0020] The application of the precautionary principle and the obligation for the practitioner to respect the wishes of the person, after informing them of the consequences of their choice and their seriousness (article L 1111-4 of the French public health code) could lead to an increase in the number of planned cesarean sections, due to the fear of possible legal action in the event of a complicated vaginal birth, or of fetal distress before an emergency cesarean section is carried out.

[0021] It is indeed tempting to resort to the most medicalized techniques, which, a priori, offer the strictest control conditions, particularly cesarean sections. In 1962, the cesarean rate in France was 6%, and 21% in 2010, with half of all cesareans performed before any labor had begun. With more than 200,000 cases per year, cesarean sections are now the most frequent surgical procedure in France. According to data from the WHO and the OECD, cesarean rates are 31% in the United States, 36% in Brazil, 49% in Mexico, and 52% in China, within the framework of the one-child policy. Cesarean sections may result from medical indications (for example in the case of a scarred uterus, multiple pregnancy, the implementation of a prophylactic cesarean being decided according to the value of the biparietal diameter and the Magnin index), but cesarean sections result in a significant number of cases from a request by the mother.

[0022] Within this technical, medical, societal and legal context, significant efforts have been made for decades to detect fetal distress and assess the health status of the newborn, particularly the risks of delay and motor or cerebral infirmity, resulting from acute fetal distress.

[0023] Before delivery, the risk of hypoxia can be identified by considering risk factors related to the mother's health (including anemia, diabetes, prolonged pregnancy, iatrogenic hypotension, respiratory failure), the state of the placenta (including placenta previa), the appearance of the umbilical cord, and certain characteristics of the fetus (prematurity, Rh incompatibility, congenital heart disease, large baby, twin pregnancy). Prepartum hypoxia can also be of infectious origin (bacterial or amniotitis) or traumatic origin (particularly in cases of prolonged labor, dynamic dystocia, or dystocic presentation).

[0024] During labor, the condition of the fetus is typically monitored using various methods: monitoring of the appearance of the amniotic fluid, by amnioscopy, recording of the fetal heart rate (FHR) during the entire active phase of labor (cardiotocograph, Doppler effect sensor, through the abdominal wall, ECG by an electrode on the scalp), measurement of capillary blood pH by micro-sampling from the fetal scalp, measurement of lactates at the scalp, transcutaneous oximetry via the vaginal route, by placing a sensor on the scalp of an unborn child or on its cheek.

[0025] Amnioscopy is no longer routinely performed on women admitted to the delivery room, as its usefulness has not been demonstrated. The detection of meconium-stained amniotic fluid is a warning sign, but not specific.

[0026] Recording the fetal heart rate (FHR) allows for retrospective analysis and potential forensic medical examinations. However, interpreting FHR abnormalities presents numerous drawbacks.

[0027] One of the difficulties in interpreting the FHR is defining criteria for normal fetal heart rhythm, proposed by learned societies, with different FHR classifications depending on the country ( International Federation of Gynecology and Obstetrics (FIGO), National Institute of Child Health and Human Development (NICHD), Royal College of Obstetricians and Gynecologists (RCOG), Society of Obstetricians and Gynecologists of Canada (SOGC), French National Agency for Accreditation and Evaluation in Health (ANAES), American College of Obstetricians and Gynecologists (ACOG), French National College of Gynecologists and Obstetricians (CNGOF) ) . In France, it is conventionally accepted that the baseline heart rate should be between 110 and 160 beats per minute (bpm), with a variability of 6 to 25 bpm, and without any slowing. The CNGOF (National College of Gynecologists and Obstetricians of France) defines normal heart rates, low risk of acidosis, risk of acidosis, high risk of acidosis, and high risk of acidosis in its clinical practice guidelines.

[0028] Another difficulty in interpreting fetal heart rate (FHR) is inter- and intra-observer variability. FHR has low specificity with a high false-positive rate of approximately 30% and is not a reliable diagnostic test. The high proportion of false positives leads to unnecessary cesarean sections and instrumental deliveries.

[0029] Fetal pH analysis by scalp micropuncture, described as early as 1962, is considered a gold standard for diagnosing asphyxia during labor in cases of fetal heart rate abnormalities. Scalp pH is a commonly used second-line method. However, fetal pH analysis has several drawbacks. This examination is invasive, and measurement failure rates are significant (particularly due to insufficient blood volume or contamination by amniotic fluid). Furthermore, fetal pH can decrease rapidly, as the measurement result is only a snapshot in time.

[0030] Scalp lactate measurement is similar to pH measurement, but requires a smaller blood sample. The disadvantage of lactate measurement is that it only allows for intermittent monitoring.

[0031] Oximetry is tricky to implement, especially to maintain constant contact of the sensor with the fetal temple or cheek, in the presence of amniotic fluid, or even vernix or meconium.

[0032] When delivery is complete, acidosis with a lactate concentration of 10 mmol / L or more and / or an Apgar score of less than 7 at 5 minutes are considered symptomatic of prenatal asphyxia.

[0033] Hypoxia leads to acidosis, a slowing of the fetal heart rate, as well as the expulsion of meconium into the amniotic fluid, and cerebral vasomotor disorders responsible for cerebro-meningeal ischemia and hemorrhages.

[0034] Prepartum hypoxia can lead to cerebral hypoxia-ischemia, which can lead to neonatal encephalopathy, with risks of sequelae, some children becoming cerebral palsy.

[0035] In the event of hypoxia, neonatal encephalopathy can occur in the first week, secondary to edema with cerebral hypertension, associating in a variable manner signs of central nervous system depression, signs of involvement of cortical, subcortical and spinal motor pathways, and signs of brainstem involvement.

[0036] Newborn brain imaging does not allow us to consistently confirm the anoxic-ischemic nature of the images observed.

[0037] Ultrasound can detect hemorrhagic pathologies in cases of neonatal encephalopathy, but it cannot determine the timing of the hypoxic event. Transfontanellar ultrasound is the first-line imaging modality in newborns with neonatal encephalopathy, to investigate a cause such as hemorrhage or a post-traumatic subdural hematoma. Apart from these rare cases, the contribution of this imaging technique is considered limited.

[0038] A brain scan is indicated in an emergency if trauma or intracranial hemorrhage is suspected on ultrasound.

[0039] Magnetic resonance imaging (MRI) is the gold standard for the prognostic assessment of asphyxia encephalopathies. However, interpreting this examination requires experience in neonatal neuroradiology.

[0040] When hypoxia or an abnormality has been detected in the newborn, various biological markers have been proposed for the risks of developing brain deficits.

[0041] In a review published in 2017, Satriano et al. presented various biomarkers under consideration (activin A, glial fibrillary acid protein GFAP, neurospecific enolase NSE, S100B protein, adrenomedullin AM), at the clinical research stage, as predictors of brain deficits in newborns with hypoxia (The potentials and limitations of neuro-biomarkers as predictors of outcome in neonates with birth asphyxia, Early Human Development 105, 2017, pp. 63-67 ).

[0042] In a review published in 2015, Bersani et al present various biomarkers under consideration (S100B protein, adrenomedullin AM, erythropoietin, activin A, neurospecific enolase NSE, glial fibrillary acid protein GFAP, creatine kinase isoenzyme CKBB), at the clinical research stage, as predictors of neonatal brain damage (Use of early biomarkers in neonatal brain damage and sepsis: state of the art and future perspectives, BioMed Research International, 2015, article 253520 ).

[0043] An earlier meta-analysis, published in 2009, of biomarkers of neonatal encephalopathy is proposed by Murabayashi et al (Kinetics of serum S100B in newborns with intracranial lesions. Pediatr Int Off J Jpn Pediatr Soc 2008; 50(1):17-22 ) Another meta-analysis was published in 2009 by Ramaswamy et al (Systematic review of biomarkers of brain injury in term neonatal encephalopathy, Pediatric Neurology, 40, 2009, pp. 215-226). ).

[0044] The measurement methods used for continuous monitoring of childbirth and the markers used do not allow for the satisfactory detection of the risks of brain injury.

[0045] The invention aims to provide a solution for assessing health risks for children, particularly during normal deliveries and asymptomatic newborns.

[0046] The invention is based on the discovery that many vaginal deliveries, considered "normal", can result in brain damage, without pH change, with a normal Agpar score, the newborns being asymptomatic, and that this damage could be detected by a deviation in the level of S100B protein from a safety value, preferably in umbilical cord blood.

[0047] The term S100B (or S100β) refers to a holoprotein synthesized primarily by glial cells of the central nervous system and by Schwann cells. This 21 kDa protein was discovered in 1965 and is composed of two subunits (two beta subunits or one β subunit and one α subunit). Its plasma half-life is approximately two hours, and it is eliminated via the kidneys. S100B is physiologically present in the brain and is released into the cerebrospinal fluid and blood in cases of brain injury. Currently, there is no international reference value for serum S100B concentration.

[0048] The invention proposes, according to a first aspect, the use of the S100β protein to identify the risk of brain damage in asymptomatic newborns during deliveries considered normal. In other words, the invention proposes the S100B protein for use in identifying the risk of brain damage in asymptomatic newborns during deliveries considered normal.

[0049] According to the embodiment, the S100β protein is used according to the following provisions, the measurement of the S100β protein being carried out in the umbilical arterial blood; a comparison of the content of S100β protein in the umbilical arterial blood is carried out, in relation to a threshold value, the threshold value being 3.25 times the median value.

[0050] The invention thus relates to a new use of a known molecule, this new use facilitating the identification of brain lesions in asymptomatic newborns, particularly following deliveries considered to be normal.

[0051] The plaintiff discovered that many vaginal deliveries considered "normal" (normal pH and Apgar score, asymptomatic newborn) can result in brain damage. This damage could be detected by a deviation in the S100B protein level from a safe value, preferably measured in blood, for example from a vein or artery of the umbilical cord, or in saliva or urine.

[0052] The origins of these phenomena are unknown to the applicant, who proposes several mechanisms.

[0053] In the absence of fetal distress or abnormality for the newborn, no attention had previously been paid to the level of S100B protein.

[0054] For example, the mode of delivery (vaginal or cesarean) was considered to have no influence on S100B protein levels: excluding cases of perinatal asphyxia and dystocia, Gazzolo et al. observed no difference in salivary S100B protein levels in newborns (S100B protein levels in saliva: correlation with gestational age in normal term and preterm newborns. Clin Biochem 2005;38(3):229-33). ).

[0055] Similarly, considering only spontaneous vaginal deliveries with cephalic presentation and cesarean sections, Amer-Wåhlin et alThey found no difference in the level of S100B protein in umbilical blood between newborns, and discerned no influence of the duration of labor; the high level of S100B protein in newborns is, according to these authors, not linked to pre- or perinatal trauma or hypoxia, this high level being observed in healthy newborns. ( Brain-specific NSE and S-100 proteins in umbilical blood after normal delivery. Clin Chim Acta Int J Clin Chem 2001;304(1-2):57-63 ).

[0056] S100B protein testing has been proposed for newborns with brain abnormalities, at-risk newborns, and in high-risk pregnancies. Most of the articles reporting clinical research results on this topic come from Italian researchers working with Dr. Diego Gazzolo. S100B protein testing has also been proposed for newborns who have undergone surgery.

[0057] Massaro et al. presented in 2014 an evaluation of S100B protein and neuron-specific enolase (NSE) in newborns with encephalopathy treated with hypothermia. All 80 newborns included in the study presented with marked signs of encephalopathy, according to the Sarnat classification, as well as acidosis and low Apgar scores (Biomarkers S100B and neuron-specific enolase predict outcome in hypothermia-treated encephalopathic newborns. Pediatr Crit Care Med J Soc Crit Care Med World Fed Pediatr Intensive Crit Care Soc 2014;15(7):615-22). .

[0058] You can also refer to the following documents: pour le pronostic des nouveau-nés atteints d'encéphalopathies, avec traitement notamment par hypothermie : Massaro AN et al. Biomarkers of brain injury in neonatal encephalopathy treated with hypothermia. J Pediatr 2012;161(3):434-40 ; Çelik Y et al. The effects of selective head cooling versus whole-body cooling on some neural and inflammatory biomarkers: a randomized controlled pilot study. Ital J Pediatr 2015;41:79 ; Sun J et al Effects of hypothermia on NSE and S-100 protein levels in CSF in neonates following hypoxic / ischaemic brain damage. Acta Paediatr Oslo Nor 1992 2012;101(8):e316-20 ; Roka A et al Serum S100B and neuron-specific enolase levels in normothermic and hypothermic infants after perinatal asphyxia, Acta Paediatr Oslo Nor 1992 2012;101(3):319-23 ; Sofijanova A et al. Predicting outcome after severe brain injury in risk neonates using the serum S100B biomarker: results using single (24 h) time-point. Prilozi 2012; 33(1):147-56 ;Qian J et al Umbilical artery blood S100beta protein: a tool for the early identification of neonatal hypoxic-ischemic encephalopathy. Eur J Pediatr 2009;168(1):71-7 ; Martins RO et al. S100B protein related neonatal hypoxia. Arq Neuropsiquiatr 2006;64(1):24-9 ; Gazzolo et al, S100B protein in urine of preterm newborns with ominous outcome, Pediatric research 58, 2005, pp. 1170-117 ; pour le prognostic des prématurés: Serpero et al The clinical and diagnostic utility of S100B in preterm newborns, Clinica Chimica cta 444, 2015, pp. 193-198 ; Sannia et al S100B urine concentrations in late preterm infants are gestational age and gender dependent. Clin Chim Acta Int J Clin Chem 2013; 417:31-4 ; Gazzolo et al S100B protein in urine of preterm newborns with ominous outcome. Pediatr Res 2005;58(6):1170-4 ;For the assessment of the risk of intrauterine death: Florio et al. Amniotic fluid S100B protein in mid-gestation and intrauterine fetal death, Lancet 2004, pp. 364-370 ; For deliveries with acidosis, detected by measuring umbilical cord blood pH, and abnormal heart rhythm, see for example Stuart A et al. Fetal electrocardiographic monitoring during labor in relation to cord blood levels of the brain-injury marker protein S-100. J Perinat Med 2008;36(2):136-41 ; Kaandorp et al. Antenatal allopurinol for reduction of birth asphyxia induced brain damage (ALLO-Trial); a randomized double blind placebo controlled multicenter study. BMC Pregnancy Childbirth 2010;10:8 ; For the prognosis of newborns with intracranial lesions detected by CT or MRI, see, for example, Murabayashi M et al. Kinetics of serum S100B in newborns with intracranial lesions. Pediatr Int Off J Jpn Pediatr Soc 2008;50(1):17-22 ;For the prognosis of newborns suffering from asphyxia and the risks of rapid death, see Gazzolo D et al. Diagnostic accuracy of S100B urinary testing at birth in full-term asphyxiated newborns to predict neonatal death. PIoS One 2009;4(2):e4298 .

[0059] The S100B protein has been discussed in the prior art as a parameter for assessing the severity of brain lesions already observed (e.g., by medical imaging, particularly MRI), or highly probable, when the usual markers of hypoxia are abnormal. A reference value is chosen using newborns considered healthy, forming a reference group. This reference group is defined using the Apgar score and umbilical cord blood pH; see, for example: Risso et al Perinatal asphyxia kidney failure does not affect S100B urine concentrations, Clinica Chimica 413, 2013, pp. 150-153 ;Sannia et al, S100B protein maternal and foetal bloodstreams gradient in healthy and small for gestational age pregnancies, Clinica Chimica Acta, 412, 2011, pp. 1337-1340 ; Sannia A, Risso FM, Serpero LD, et al. Antenatal glucocorticoid treatment affects preterm infants' S100B urine concentration in a dose-dependent manner, Clin Chim Acta Int J Clin Chem 2010;411(19-20):1539-41 ; Risso FM, Serpero LD, Zimmermann LJI, et al. Urine S100 BB and A1B dimers are valuable predictors of adverse outcome in full-term asphyxiated infants, Acta Paediatr Oslo Nor 1992 2013; 102(10):e467-72 . Maschmann J, Erb null, Heinemann MK, Ziemer G, Speer CP. Evaluation of protein S-100 serum concentrations in healthy newborns and seven newborns with perinatal acidosis, Acta Paediatr Oslo Nor 1992 2000; 89(5):553-5 .

[0060] The invention proposes a different approach, in which the level of S100B protein is systematically measured, a level above a threshold value being considered significant of a risk of brain injury, even in the case of normal delivery and in the presence of an asymptomatic newborn.

[0061] The applicant hypothesizes that normal childbirth results in high mechanical stresses on the skull, and that these stresses have become more significant in Western societies, partly due to an increase in skull dimensions.

[0062] The plaintiff notably hypothesizes that the increase in skull size stems in particular from a greater use of cesarean sections. Such a hypothesis has been recently proposed by some authors (see Mitteroecker P et al (2016) Cliff-edge model of obstetric selection in humans, Proc Natl Acad Sciences, 113(51):14680-14685). ).

[0063] The plaintiff hypothesizes that during normal childbirth, newborns experience cerebral compression, often linked to temporary reshaping of the fetal skull bones during passage through the birth canal at the midpelvis. The plaintiff has established that such cerebral compression can be inferred from measurements taken during MRI-guided deliveries, with the images feeding into a mechanical model.

[0064] The plaintiff believes that this cerebral compression may be responsible for a cerebral contusion which could be reflected by the elevation of the S100β protein in the blood.

[0065] The systematic measurement of S100β protein concentration in the newborn's cord blood after delivery allows for the prediction of the risks of cerebral hemorrhage and ischemia in asymptomatic newborns.

[0066] S100β protein levels can be measured using techniques marketed by various manufacturers (Sangtec, Elecsys Roche, CanAg, YK150). For example, the Elecsys S100β test can be used. This immunoassay is for the quantitative in vitro determination of S100 protein (S100A1B and S100BB) in human serum. This ECLIA electroluminescence assay is used on Elecsys and Cobas analyzers. Manufactured by Roche Diagnostics GmbH and distributed by Roche Diagnostics France, the assay takes approximately 18 minutes and is inexpensive (BHN 120, €32).

[0067] The invention offers a means of assisting in the detection of low-level brain lesions in asymptomatic newborns, particularly following delivery considered normal, where none of the conventional means (pH, lactase, FHR, Apgar score) classify the newborn in a category considered at risk.

[0068] The invention thus allows for early treatment of brain lesions that only result in low-grade inflammatory states, the treatment making it possible to avoid the deleterious effects of these lesions on the child's development.

Claims

1. A use of the S100β protein in the identification of risks of brain injuries (haemorrhages, brain ischemias), during deliveries considered normal (eutocic delivery), in asymptomatic newborns, in the absence of foetal suffering, the newborn showing no signs of acidosis or hypoxia, and having a normal Apgar score, normal umbilical blood pH, the risks of brain injuries being identified by a level of S100β protein in umbilical arterial blood above a safety threshold value of 3.25 times the median value.