Unraveling the Pathogenesis of Pruritus in Intrahepatic Cholestasis of Pregnancy

As the most common liver-related disease in pregnancy, ICP affects an average of 4% of pregnant women worldwide. In a cohort study of 12200 eligible Chinese pregnant women, the reported incidence of ICP was 6.06%. ICP is harmful to the health of both pregnant women and fetuses. For the fetus, ICP directly affects the healthy growth and smooth delivery of the fetus. Disease-related adverse events have been reported, including preterm birth, meconium contamination of amniotic fluid, fetal hypoxia, prolonged length of stay in neonatal unit, and even stillbirth. ICP has a serious impact on the physical and mental health of pregnant women, typically severe pruritus. This itching occurs mainly in the second and third trimesters of pregnancy (usually the third trimester) and tends to become progressively worse as the pregnancy progresses. It is most commonly present on the palms and soles of the feet, and some patients have generalized itching. Moreover, the itching was aggravated at night, leading to severe insomnia. Under the background of advocating multiple births in our country, the effective prevention and treatment of such diseases is particularly important.

At present, there are no effective drugs for the treatment of ICP, especially pruritus symptoms, because the molecular mechanism of ICP and its pruritus is still unclear. In this study, we have identified several endogenous potential pruritogens that can activate human MRGPRX4, the potential itch receptor of ICP pruritus, to mediate ICP pruritus based on a large number of previous cell and animal experiments. Based on clarifying the mechanism of pruritus, this project hopes to provide new biomarkers and new perspectives for the diagnosis and even prediction of the disease combined with the analysis of clinical samples. As such, health monitoring and early intervention may thus be enabled during pregnancy to benefit the treatment outcome of both the patient and child clinically. methods are as follows:

① To characterize the dynamic changes of progesterone sulfates in patients with ICP during the first, second, and third trimesters of pregnancy In cooperation with teams in the Department of Obstetrics and Gynecology of hospitals, blood samples will be collected from pregnant women at three different time points during pregnancy (including healthy pregnant women and pregnant women with ICP). A questionnaire will be completed by the pregnant women in the third trimester or by telephone follow-up after delivery. The degree of pruritus in pregnant women with ICP will be counted. The changes of progesterone sulfate levels and the degree of pruritus are characterized by the progression of pregnancy cycle. For the analysis of metabolite composition in plasma, we developed HPLC-MS based separation and quantification methods, focusing on the progesterone metabolites/derivatives of interest, including the following nine progesterone sulfates: Isopregnanolone sulfate (3β5α) (PM5S), Epipregnanolone sulfate (3β5β) (PM7S), Pregnanolone sulfate (3α5β) (PM6S), Allopregnanolone sulfate (3α5α) (PM4S), Pregnanediol sulfate (3α5β) (PM3S), Isopregnanediol sulfate (3β5α), 5β-pregnan-3α, 20α-diol-3, 20-disulfate (PM3DiS), 5α-pregnan-3α, 20α-diol-3, 20-disulfate (PM2DiS), Pregnenolone sulfate and 17-Hydroxypregnenolone sulfate. A 100 μl plasma sample is mixed with 425 μl methanol and vortexed for 10 min. After centrifugation at 14 000 g for 10 min, the supernatant is transferred to a new tube and stored at -80 ° C before HPLC-MS analysis.

② Develop diagnostic and early prediction models for ICP or pruritus symptoms. After obtaining a sufficient amount of biological samples and the metabolite analysis results, we plan to conduct effective statistical analysis and data mining based on the sample data. Using the data of related metabolites in the blood of ICP patients and healthy pregnant women in the third trimester, Receiver Operating Characteristic (ROC) curves analysis and logistic regression model will be used to find a single characteristic metabolite molecule or a combination of several metabolite molecules, which could effectively distinguish ICP patients from normal pregnant women, and serve as a new indicator with high accuracy to assist the clinical diagnosis of ICP. Furthermore, based on the analysis of blood samples in the first and second trimesters, we expect that characteristic metabolites can be mined, and the dynamic changes in their levels can even predict the probability of ICP before the onset of ICP symptoms, so as to guide the implementation of preventive measures in advance and possibly reduce the probability of adverse events.