Placental gene-expression profiles of intrahepatic cholestasis of pregnancy reveal involvement of multiple molecular pathways in blood vessel formation and inflammation

Single-cell RNA sequencing reveals heterogeneity and differential expression of the maternal-fetal interface during ICP and normal pregnancy

OBJECTIVE

Intrahepatic cholestasis of pregnancy (ICP) can cause adverse perinatal outcomes. Previous studies have demonstrated that the placenta of an ICP pregnancy differs in morphology and gene expression from the placenta of a normal pregnancy. To date, however, the genetic mechanism by which ICP affects the placenta is poorly understood. Therefore, the aim of this study was to investigate the differences in main cell types, gene signatures, cell ratio, and functional changes in the placenta between ICP and normal pregnancy.

METHODS

Single-cell RNA sequencing (scRNA-seq) technology was used to detect the gene expression of all cells at the placental maternal-fetal interface. Two individuals were analyzed - one with ICP and one without ICP. The classification of cell types was determined by a graph-based clustering algorithm. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using the R software phyper () function and DAVID website. The differentially expressed genes (DEGs) encoding transcription factors (TFs) were identified using getorf and DIAMOND software.

RESULTS

We identified 14 cell types and 22 distinct cell subtypes that showed unique functional properties. Additionally, we found differences in the proportions of fibroblasts 1, helper T (Th) cells, extravillous trophoblasts, and villous cytotrophoblasts, and we observed heterogeneity of gene expression between ICP and control placentas. Furthermore, we identified 263 DEGs that belonged to TF families, including zf-C2H2, HMGI/HMGY, and Homeobox. In addition, 28 imprinted genes were preferentially expressed in specific cell types, such as PEG3 and PEG10 in trophoblasts as well as DLK1 and DIO3 in fibroblasts.

CONCLUSIONS

Our results revealed the differences in cell-type ratios, gene expression, and functional changes between ICP and normal placentas, and heterogeneity was found among cell subgroups. Hence, the imbalance of various cell types affects placental activity to varying degrees, indicating the complexity of the cell networks that form the placental tissue system, and this alteration of placental function is associated with adverse events in the perinatal period.

Comprehensive Analysis of scRNA-Seq and Bulk RNA-Seq Reveals Transcriptional Signatures of Macrophages in Intrahepatic Cholestasis of Pregnancy

Purpose

Intrahepatic cholestasis of pregnancy (ICP) is a disorder that characterized by maternal pruritus, abnormal liver function, and an elevation in total bile acid concentrations during pregnancy. Immune factors have been recognized as playing a vital role in the mechanism of ICP. However, the underlying mechanisms regulating dysfunctional immune cells and immune genes remain to be fully elucidated.

Patients and Methods

Single-cell RNA sequencing and bulk RNA sequencing data of the placenta were downloaded from the SRA database. The AUCell package, Monocle package and SCENIC package were utilized to explored immune cell activity, cell trajectory and transcription factor, respectively. GO, KEGG, and GSEA were employed to explore potential biological mechanisms. Cell-cell communications were further investigated using the CellChat package. RT-PCR, and Western blot were used to verify the gene expression in placenta.

Results

In placenta cells, macrophages were found to be significantly increased in ICP. Additionally, macrophages exhibited the highest immune gene score and were divided into four subclusters (MF1-4). Our analysis revealed significant elevations in MF2, associated with LPS response and antigen presentation, and MF4, associated with TNF and cytokine production. MF3 displayed an anti-inflammatory phenotype. MF1, closely related to ribosomes and proteins, exhibited a sharp decrease. Although ICP maintained an anti-inflammatory state, macrophage trajectories showed a gradual progression toward inflammation. Subsequently, we confirmed that cytokine- and chemokine-related signaling pathways were emphasized in macrophages. Within the CXCL signaling pathway, the increased expression of CXCL1 in macrophages can interact with CXCR2 in neutrophils, potentially inducing macrophage infiltration, stimulating neutrophil chemotaxis, and leading to an inflammatory response and cellular damage.

Conclusion

In conclusion, we firstly revealed the transcriptional signatures of macrophages in ICP and discovered a tendency toward an inflammatory state. This study also provides new evidence that the CXCL1-CXCR2 axis may play an important role in the pathogenesis of ICP.

Unveiling the placental secrets: Exploring histopathological changes and TROP2 expression in intrahepatic cholestasis of pregnancy

INTRODUCTION

Gestational cholestasis, also known as intrahepatic cholestasis of pregnancy (ICP) or obstetric cholestasis, is a liver disease that can manifest in late pregnancy. Trophoblast cell surface antigen (TROP2) is a type I transmembrane glycoprotein identified in placental trophoblast cells that plays a critical role in trophoblast invasion of the decidua upon implantation into the placenta. Our study aims to investigate the role of TROP2 in pregnancy cholestasis.

MATERIALS AND METHODS

Study groups: Group 1 (control group) (n = 10): consists of healthy normal pregnant women without any disease, Group 2 (cholestasis group) (n = 10): consists of pregnant women diagnosed with cholestasis. After routine histological follow-up, hematoxylin and eosin staining and TROP2 immunostaining were performed and scored.

RESULTS

In the cholestasis group, in contrast to the control group, thrombus structures were observed in the intervillous space. In the cholestasis group compared to the control group, villus mesenchymal connective tissue cells, capillary endothelium and trophoblasts around the villus showed significantly stronger anti-TROP2 staining (p < 0.05).

DISCUSSION

Cholestasis, a condition that may manifest during pregnancy, may be associated not only with observable pathological changes in placental tissues at the light microscopic level, but also with an increase in TROP2 expression. Given the critical role of TROP2 in trophoblast invasion during placental implantation, we hypothesize that TROP2 may serve as a key marker of the cholestatic processes occurring during pregnancy.

Evaluation of maternal serum vascular endothelial growth factor C and D levels in intrahepatic cholestasis of pregnancy

OBJECTIVE

This study aimed to investigate maternal serum vascular endothelial growth factor (VEGF) C and D levels in patients with intrahepatic cholestasis of pregnancy (ICP).

METHODS

A total of 83 patients, including 41 patients with ICP and 42 healthy pregnant women, were included in the study. We first compared the maternal serum VEGF-C and VEGF-D levels between the ICP and control groups and then examined the correlation between the serum VEGF-C level and the bile acid level in patients with severe ICP.

RESULTS

We observed statistically significantly higher serum VEGF-C levels and lower VEGF-D levels in the ICP group compared with the healthy controls (P < 0.001 and P = 0.015, respectively). According to receiver operating characteristic analysis, the optimal cutoff value for ICP was 147 ng/mL in the determination of the VEGF-C level (specificity and sensitivity: 76%). In patients with severe ICP, the serum VEGF-C statistically significantly correlated with the bile acid level (P = 0.019).

CONCLUSION

This study showed that the maternal serum VEGF-C level was higher and the VEGF-D level was lower in patients with ICP compared with healthy pregnant women. We also found that the VEGF-C level was correlated with the serum bile acid level in patients with severe ICP. Serum VEGF-C level can be used in the diagnosis and follow-up of intrahepatic pregnancy cholestasis.

Intrahepatic cholestasis of pregnancy: insights into pathogenesis and advances in omics studies

Intrahepatic cholestasis of pregnancy (ICP) is the most common pregnancy-specific liver disease. It is characterized by pruritus, abnormal liver function and elevated total bile acid (TBA) levels, increasing the risk of maternal and fetal adverse outcomes. Its etiology remains poorly elucidated. Over the years, various omics techniques, including metabolomics, microbiome, genomics, etc., have emerged with the advancement of bioinformatics, providing a new direction for exploring the pathogenesis, diagnosis and treatment of ICP. In this review, we first summarize the role of bile acids and related components in the pathogenesis of ICP and then further illustrate the results of omics studies.

An omics review and perspective of researches on intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is one of the common pregnancy complications that may threaten the health of both pregnant women and their fetuses. Hence, it is of vital importance to identify key moleculars and the associated functional pathways of ICP, which will help us to better understand the pathological mechanisms as well as to develop precise clinical biomarkers. The emerging and developing of multiple omics approaches enable comprehensive studies of the genome, transcriptome, proteome and metabolome of clinical samples. The present review collected and summarized the omics based studies of ICP, aiming to provide an overview of the current progress, limitations and future directions. Briefly, these studies covered a broad range of research contents by the comparing of different experimental groups including ICP patients, ICP subtypes, ICP fetuses, ICP models and other complications. Correspondingly, the studied samples contain various types of clinical samples, in vitro cultured tissues, cell lines and the samples from animal models. According to the main research objectives, we further categorized these studies into two groups: pathogenesis and diagnosis analyses. The pathogenesis studies identified tens of functional pathways that may represent the key regulatory events for the occurrence, progression, treatment and fetal effects of ICP. On the other hand, the diagnosis studies tested more than 40 potential models for the early-prediction, diagnosis, grading, prognosis or differential diagnosis of ICP. Apart from these achievements, we also evaluated the limitations of current studies, and emphasized that many aspects of clinical characteristics, sample processing, and analytical method can greatly affect the reliability and repeatability of omics results. Finally, we also pointed out several new directions for the omics based analyses of ICP and other perinatal associated conditions in the future.

Maternal and neonatal outcomes of intrahepatic cholestasis of pregnancy after in vitro fertilization

BACKGROUND

Intrahepatic cholestasis of pregnancy (ICP) is an idiopathic disease of pregnancy. Little is known about how it specifically affects pregnancies resulting from in vitro fertilization (IVF). Our aim is to evaluate the impact of IVF on the perinatal outcomes of ICP.

METHODS

A retrospective study of 242 patients with intrahepatic cholestasis of pregnancy, comprising 36 conceived through IVF and 206 spontaneous conceptions (SC), enrolled between 2019 and 2021 was carried out. Data were analyzed from the medical archives of the Huazhong University of Science and Technology, Tongji Hospital.

RESULTS

Numerical values of transaminases (ALT, alanine aminotransferase; AST, aspartate aminotransferase) and serum total bile acid (TBA) are significantly lower in the IVF group than that in the spontaneous conceived group (p < 0.05). The incidence of gestational diabetes mellitus (GDM) was higher in the IVF group than in SC group (30.6% vs. 16%, p = 0.037). The cesarean section (CS) rates are higher in the IVF group (97.2% vs. 85.4%, p = 0.023). On the other hand, the prevalence of premature rupture of membranes (PROM) was higher in the SC group (10.7%) while none was reported in the IVF-ICP group. Other maternal comorbidities and neonatal outcomes were similar between the two groups.

CONCLUSION

ICP patients who underwent IVF are more likely to suffer from GDM. Therefore, monitoring and management of blood glucose should be strengthened during pregnancy. Fortunately, IVF does not seem to worsen the progression or outlook of ICP, so sticking to standard management practices is recommended.

The role of noncoding RNA and its diagnostic potential in intrahepatic cholestasis of pregnancy: a research update

Intrahepatic cholestasis of pregnancy (ICP) is a common liver disorder that generally occurs during the second or third trimester of pregnancy. It rarely causes any harm to the mother; however, it can result in short- and long-term complications in the offspring. Therefore, it is crucial to diagnose and treat this condition to avoid poor pregnancy outcomes. The identification of novel markers with potential diagnostic, prognostic, and therapeutic utility in ICP has gained attention. Noncoding RNAs (ncRNAs), including microRNA, long noncoding RNA, and circular RNA, are a type of transcripts that are not translated into proteins. They possess vital biological functions, including transcriptional and translational regulation and DNA, RNA, and protein interactions. The pathogenesis of ICP is related to the aberrant expression of several circulating or placenta-related ncRNAs. In this review, we summarized all recent findings on ncRNAs and ICP and outlined the concepts that form the basis for the early diagnosis and targeted treatment of ICP.

Expression and Significance of Galectin-1 and Galectin-3 in the Serum and Placental Tissues of Patients with Intrahepatic Cholestasis of Pregnancy

Background

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific liver disease, usually occurring in the third trimester of pregnancy. Its typical clinical manifestations are itching and elevated serum total bile acid levels, which are more harmful to the fetus, and can lead to a variety of adverse pregnancy outcomes. This paper discusses the expressions of galectin -1 and 3 in the serum and placenta of ICP patients and their relationship with the effect of the incidence of ICP.

Methods

Galectin-1 and 3 in serum and placenta were detected in 22 pregnant women with ICP and 20 healthy pregnant women admitted to the obstetrics Department of Northern Jiangsu People's Hospital from May 2021 to February 2022.

Results

Serum levels of galectin-1 and galectin-3 in ICP pregnant women were significantly higher than those in controls, with significant differences (P<0.05). Placental galectin-1 and 3 were higher in normal pregnant women, and there were statistical differences between groups (P<0.05).

Conclusion

In ICP, the maternal serum and placental galectin-1 and 3 levels were significantly increased, both of which may play an important role in the development of ICP, which may be the initiation factor of ICP pathophysiology, a marker of ICP prediction, and a target of ICP prevention strategies.

SWATH proteomics analysis of placental tissue with intrahepatic cholestasis of pregnancy

INTRODUCTION

Intrahepatic cholestasis of pregnancy (ICP) usually occurs in the second and third trimesters. The disease's etiology and diagnostic criteria are currently unknown. Based on a sequence window to obtain all theoretical fragment ions (SWATH) proteomic approach, this study sought to identify potential proteins in placental tissue that may be involved in the pathogenesis of ICP and adverse fetal pregnancy outcomes.

METHODS

The postpartum placental tissue of pregnant women with ICP were chosen as the case group (ICP group) (subdivided into mild ICP group (MICP group) and severe ICP group (SICP group)), and healthy pregnant women were chosen as the control group (CTR). The hematoxylin-eosin (HE) staining was used to observe the histologic changes of placenta. The SWATH analysis combined with liquid chromatography-tandem mass spectrometry (LC-MS) was used to screen the differentially expressed proteins (DEPs) in ICP and CTR groups, and bioinformatics analysis was used to find out the biological process of these differential proteins.

RESULTS

Proteomic studies showed there were 126 DEPs from pregnant women with ICP and healthy pregnant women. Most of the identified proteins were functionally related to humoral immune response, cell response to lipopolysaccharide, antioxidant activity and heme metabolism. A subsequent examination of placentas from patients with mild and severe ICP revealed 48 proteins that were differentially expressed. Through death domain receptors and fibrinogen complexes, these DEPs primarily regulate extrinsic apoptotic signaling pathways, blood coagulation, and fibrin clot formation. The differential expressions of HBD, HPX, PDE3A, and PRG4 were down-regulated by Western blot analysis, which was consistent with proteomics.

DISCUSSION

This preliminary study helps us to understand the changes in the placental proteome of ICP patients, and provides new insights into the pathophysiology of ICP.

Factors associated with intrahepatic cholestasis of pregnancy and its influence on maternal and infant outcomes

The aim of this study was to investigate the clinical features and risk factors of intrahepatic cholestasis of pregnancy (ICP) and its effect on pregnancy outcomes. The data from 300 pregnant women with ICP and 300 pregnant women without ICP admitted from July 2015 to December 2016 at Changsha Maternal and Child Health Hospital were collected. The factors associated with ICP were examined. The family history of ICP, twin pregnancies, number of births, hypertensive disorder of pregnancy (HDP), gestational diabetes, hyperlipidemia, hepatitis virus infection, and in vitro fertilization and embryo transfer, differed significantly between the 2 groups (all P < .05). The multivariable analysis showed that body mass index at delivery, number of births, HDP, gestational diabetes, hyperlipidemia, and hepatitis virus infection were associated with ICP (all P < .05). The incidence of abnormal amniotic fluid and premature births in the ICP group were significantly higher than in the control group (all P < .05). ICP is associated with BMI at delivery, number of births, HDP, gestational diabetes, hyperlipidemia, and hepatitis virus infection. ICP greatly influences pregnancy outcomes.

Identification of two novel pathogenic variants of the NR1H4 gene in intrahepatic cholestasis of pregnancy patients

Background

Intrahepatic cholestasis of pregnancy (ICP) can cause adverse pregnancy outcomes, such as spontaneous preterm delivery and stillbirth. It is a complex disease influenced by multiple factors, including genetics and the environment. Previous studies have reported that functioning nuclear receptor subfamily 1 group H member 4 (NR1H4) plays an essential role in bile acid (BA) homeostasis. However, some novel variants and their pathogenesis have not been fully elucidated. Therefore, this research aimed to investigate the genetic characteristics of the NR1H4 gene in ICP.

Methods

In this study, we sequenced the entire coding region of NR1H4 in 197 pregnant women with ICP disease. SIFT and PolyPhen2 were used to predict protein changes. Protein structure modelling and comparisons between NR1H4 reference and modified protein structures were performed by SWISS-MODEL and Chimera 1.14rc, respectively. T-tests were used to analyse the potential significant differences between NR1H4 mutations and wild types for 29 clinical features. Fisher’s test was conducted to test the significance of differences in mutation frequencies between ICP and the three databases.

Results

We identified four mutations: two novel missense mutations, p.S145F and p.M185L; rs180957965 (A230S); and rs147030757 (N275N). The two novel missense mutations were absent in 1029 controls and three databases, including the 1000 Genomes Project (1000G_ALL), Exome Aggregation Consortium (ExAC) and ChinaMAP. Two web-available tools, SIFT and PolyPhen2, predicted that these mutations are harmful to the function of the protein. Moreover, compared to the wild-type protein structure, the NR1H4 p.S145F and p.M185L protein structure showed a slight change in the chemical bond in two zinc finger structures. Combined clinical data indicate that the mutation group had higher levels of total bile acid (TBA) than the wild-type group. Therefore, we hypothesized that these two mutations altered the protein structure of NR1H4, which impaired the function of NR1H4 itself and its target gene and caused an increase in TBA.

Conclusions

To our knowledge, this is the first study to identify the novel p.S145F and p.M185L mutations in 197 ICP patients. Our present study provides new insights into the genetic architecture of ICP involving the two novel NR1H4 mutations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01240-w.

Unfolding newer concepts in placental pathology of obstetric cholestasis-a cause for prematurity

Intrahepatic cholestasis of pregnancy (ICP) has an increased predisposition to occur in the third trimester of pregnancy and has a varied population incidence rates due to genetic influences. Owing to the adverse and unpredictable fetal outcomes, it poses a serious therapeutic challenge to the clinician. A rise in the incidence of iatrogenic prematurity has been observed, raising concerns over the perinatal outcomes. Excess bile acids and altered placental transport mechanisms have been strongly implicated in the pathogenesis of ICP and its complications. The exact etiology is not known; yet major underlying risk factors that are thought to contribute to the disease process include genetic, environmental, hormonal, and immunological. Newer molecular processes acting at the placental level, apart from specific histopathological changes, have assumed significance in recent times. In this review, we attempt to highlight the recent understanding of the mechanisms that operate in the placenta in patients with obstetric cholestasis that lead to poor fetal outcomes, through various studies published in the literature. Despite these additions to the existing knowledge on the etiopathogenesis of obstetric cholestasis and its possible placental origin, further studies are needed to validate the newer concepts.

Prenatal ethanol exposure increases maternal bile acids through placental transport pathway

High maternal serum bile acid level is common and sometimes harmful to the gravida. This study aimed to confirm the bile acid phenotypic change caused by prenatal ethanol exposure (PEE) and elucidate its placental mechanism. Pregnant Wistar rats were administered intragastrically with ethanol 4 g/kg⋅d from gestational day 9-20. Total bile acids (TBA) were detected in maternal, fetal serum and placental tissues, increasing significantly in the serum but no significant change in the placental tissues. Meta-analysis was performed and verified the efficacy of the PEE-induced model based on published data from several relevant studies. Mining of microarray data from human and rat placental sources identified the involvement of bile acid metabolism and its significant genes, which were verified by RT-qPCR and western blotting on tissues and treated BeWo cells with the administration of FXR/PXR siRNAs or FXR/PXR agonists. Our examination, consistent with microarray data and wet experiments, showed that organic anion transporter polypeptide-related protein 2B1 (Oatp2b1), multidrug resistance-associated proteins 3 (Mrp3) and breast cancer resistance protein (Bcrp) expression were increased, while nuclear receptor farnesoid X receptor (Fxr) was decreased but pregnane X receptor (Pxr) was increased. Furthermore, the interventional experiments confirmed that FXR regulated Bcrp while PXR regulated Oatp2b1 and Mrp3. In summary, PEE could induce high bile acid level in maternal serum and its mechanism is associated with the high expression of BCRP/MRP3/OATP2B1 in the placenta through up-regulating PXR and down-regulating FXR, thereby leading to an excessive bile acid transport to maternal blood via the placenta. Our study provides a novel perspective in terms of placenta, explaining the increased maternal blood bile acids under the toxicity of PEE.

Molecular Pathogenesis of Intrahepatic Cholestasis of Pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific liver disease. The maternal symptoms are characterized by skin pruritus and elevated bile acids, causing several adverse outcomes for fetuses, including an increased risk of preterm birth, meconium-stained amniotic fluid, neonatal depression, respiratory distress syndrome, and stillbirth. Genetic, hormonal, immunological, and environmental factors contribute to the pathogenesis of ICP, and the estrogen-bile acid axis is thought to play a dominant role. The advances in the past 10 years uncover more details of this axis. Moreover, dysregulation of extracellular matrix and oxygen supply, organelle dysfunction, and epigenetic changes are also found to cause ICP, illuminating more potential drug targets for interfering with. Here, we summarize the molecular pathogenesis of ICP with an emphasis on the advancement in the past 10 years, aiming to give an updated full view of this field.

Current approaches and developments in transcript profiling of the human placenta

BACKGROUND

The placenta is the active interface between mother and foetus, bearing the molecular marks of rapid development and exposures in utero. The placenta is routinely discarded at delivery, providing a valuable resource to explore maternal-offspring health and disease in pregnancy. Genome-wide profiling of the human placental transcriptome provides an unbiased approach to study normal maternal–placental–foetal physiology and pathologies.

OBJECTIVE AND RATIONALE

To date, many studies have examined the human placental transcriptome, but often within a narrow focus. This review aims to provide a comprehensive overview of human placental transcriptome studies, encompassing those from the cellular to tissue levels and contextualize current findings from a broader perspective. We have consolidated studies into overarching themes, summarized key research findings and addressed important considerations in study design, as a means to promote wider data sharing and support larger meta-analysis of already available data and greater collaboration between researchers in order to fully capitalize on the potential of transcript profiling in future studies.

SEARCH METHODS

The PubMed database, National Center for Biotechnology Information and European Bioinformatics Institute dataset repositories were searched, to identify all relevant human studies using ‘placenta’, ‘decidua’, ‘trophoblast’, ‘transcriptome’, ‘microarray’ and ‘RNA sequencing’ as search terms until May 2019. Additional studies were found from bibliographies of identified studies.

OUTCOMES

The 179 identified studies were classifiable into four broad themes: healthy placental development, pregnancy complications, exposures during pregnancy and in vitro placental cultures. The median sample size was 13 (interquartile range 8–29). Transcriptome studies prior to 2015 were predominantly performed using microarrays, while RNA sequencing became the preferred choice in more recent studies. Development of fluidics technology, combined with RNA sequencing, has enabled transcript profiles to be generated of single cells throughout pregnancy, in contrast to previous studies relying on isolated cells. There are several key study aspects, such as sample selection criteria, sample processing and data analysis methods that may represent pitfalls and limitations, which need to be carefully considered as they influence interpretation of findings and conclusions. Furthermore, several areas of growing importance, such as maternal mental health and maternal obesity are understudied and the profiling of placentas from these conditions should be prioritized.

WIDER IMPLICATIONS

Integrative analysis of placental transcriptomics with other ‘omics’ (methylome, proteome and metabolome) and linkage with future outcomes from longitudinal studies is crucial in enhancing knowledge of healthy placental development and function, and in enabling the underlying causal mechanisms of pregnancy complications to be identified. Such understanding could help in predicting risk of future adversity and in designing interventions that can improve the health outcomes of both mothers and their offspring. Wider collaboration and sharing of placental transcriptome data, overcoming the challenges in obtaining sufficient numbers of quality samples with well-defined clinical characteristics, and dedication of resources to understudied areas of pregnancy will undoubtedly help drive the field forward.

Whole-exome sequencing identifies novel mutations in ABC transporter genes associated with intrahepatic cholestasis of pregnancy disease: a case-control study

Background

Intrahepatic cholestasis of pregnancy (ICP) can cause premature delivery and stillbirth. Previous studies have reported that mutations in ABC transporter genes strongly influence the transport of bile salts. However, to date, their effects are still largely elusive.

Methods

A whole-exome sequencing (WES) approach was used to detect novel variants. Rare novel exonic variants (minor allele frequencies: MAF < 1%) were analyzed. Three web-available tools, namely, SIFT, Mutation Taster and FATHMM, were used to predict protein damage. Protein structure modeling and comparisons between reference and modified protein structures were performed by SWISS-MODEL and Chimera 1.14rc, respectively.

Results

We detected a total of 2953 mutations in 44 ABC family transporter genes. When the MAF of loci was controlled in all databases at less than 0.01, 320 mutations were reserved for further analysis. Among these mutations, 42 were novel. We classified these loci into four groups (the damaging, probably damaging, possibly damaging, and neutral groups) according to the prediction results, of which 7 novel possible pathogenic mutations were identified that were located in known functional genes, including ABCB4 (Trp708Ter, Gly527Glu and Lys386Glu), ABCB11 (Gln1194Ter, Gln605Pro and Leu589Met) and ABCC2 (Ser1342Tyr), in the damaging group. New mutations in the first two genes were reported in our recent article. In addition, compared to the wild-type protein structure, the ABCC2 Ser1342Tyr-modified protein structure showed a slight change in the chemical bond lengths of ATP ligand-binding amino acid side chains. In placental tissue, the expression level of the ABCC2 gene in patients with ICP was significantly higher (P < 0.05) than that in healthy pregnant women. In particular, the patients with two mutations in ABC family genes had higher average values of total bile acids (TBA), aspartate transaminase (AST), direct bilirubin (DBIL), total cholesterol (CHOL), triglycerides (TG) and high-density lipoprotein (HDL) than the patients who had one mutation, no mutation in ABC genes and local controls.

Conclusions

Our present study provide new insight into the genetic architecture of ICP and will benefit the final identification of the underlying mutations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03595-x.

An insight into the mechanism and molecular basis of dysfunctional immune response involved in cholestasis

Cholestasis is one of the most common clinical symptom of liver diseases. If patients do not receive effective treatment, cholestasis can evolve into liver fibrosis, cirrhosis and ultimately liver failure requiring liver transplantation. Currently, only ursodeoxycholic acid, obeticholic acid and bezafibrate are FDA-approved drugs, thereby requiring a breakthrough in new mechanisms and therapeutic development. Inflammation is one of the common complications of cholestasis. Hepatic accumulation of toxic hydrophobic bile acids is a highly immunogenic process involving both resident and immigrating immune cells. And the resulting inflammation may further aggravate hepatocyte injury. Though, great investigations have been made in the immune responses during cholestasis, the relationship between immune responses and cholestasis remains unclear. Moreover, scarce reviews summarize the immune responses during cholestasis and the efficacy of therapies on immune response. The main purpose of this paper is to review the existing literature on dysfunctional immune response during cholestasis and the effect of treatment on immune response which may provide an insight for researchers and drug development.

Prevalence and risk factors of intrahepatic cholestasis of pregnancy in a Chinese population

Studies on the risk factors for intrahepatic cholestasis of pregnancy (ICP) in a population-based cohort are lacking. We assess the prevalence and risk factors of ICP in a Chinese population. In this study, a cohort study was conducted that included 12,200 eligible pregnant women. The overall incidence of ICP in this cohort was 6.06%. With increasing maternal age, the incidence of ICP decreased in women younger than 30 years of age but increased in those older than 30. With increasing pre-pregnancy BMI, the incidence of ICP decreased if the pre-pregnancy BMI was less than 23 kg/m² but increased if it was 23 kg/m² or higher. Further analysis showed that the risk of ICP increased when maternal age was < 25 years (Adjusted RR  2.01; 95% CI 1.64–2.47) or ≥ 35 years (Adjusted RR  1.34; 95% CI 1.02–1.76). Furthermore, an increased risk of ICP was associated with pre-pregnancy underweight (adjusted RR  1.27; 95% CI 1.04–1.56), inadequate gestational weight gain (GWG) (adjusted RR  1.58; 95% CI 1.28–1.96), lower maternal education (adjusted RR  2.96; 95% CI 2.35–3.74), multiparity (adjusted RR  1.54; 95% CI 1.23–1.93), and twin/multiple pregnancies (adjusted RR  2.12; 95% CI 1.25–3.58). Maternal age (< 25 or ≥ 35 years), underweight, inadequate GWG, lower maternal education, multiparity, and twin/multiple pregnancies were identified as risk factors of ICP.

Liver disease in pregnancy: Medical aspects and their implications for mother and child

Liver disease during pregnancy is more common than expected and may require specialized intervention. It is important to determine if changes in liver physiology may develop into liver disease, to assure early diagnosis. For adequate surveillance of mother-fetus health outcome, liver disease during pregnancy might require intervention from a hepatologist. Liver diseases have a prevalence of at least 3% of all pregnancies in developed countries, and they are classified into two main categories: related to pregnancy; and those non- related that are present de novo or are preexisting chronic liver diseases. In this review we describe and discuss the main characteristics of those liver diseases associated with pregnancy and only some frequent pre-existing and co-incidental in pregnancy are considered. In addition to the literature review, we compiled the data of liver disease occurring during pregnancies attended at the National Institute of Perinatology in Mexico City in a three-year period. In our tertiary referral women hospital, liver disease was present in 11.24 % of all pregnancies. Associated liver disease was found in 10.8% of all pregnancies, mainly those related to pre-eclampsia (9.9% of pregnancies). Only 0.56% was due to liver disease that was co-incidental or preexisting; the acute or chronic hepatitis C virus was the most frequent in this group (0.12%). When managing pregnancy in referral hospitals in Latin America, it is important to discard liver alterations early for adequate follow up of the disease and to prevent adverse consequences for the mother and child.

MicroRNAs derived from urinary exosomes act as novel biomarkers in the diagnosis of intrahepatic cholestasis of pregnancy

We aimed to investigate the value of cholestasis-related miRNAs in the diagnosis of intra-hepatic cholestasis of pregnancy (ICP) as well as the molecular mechanisms underlying the role of these miRNAs in the pathogenesis of ICP. In this study, electron microscopy was utilized to observe the exosomes present in the urine samples collected from both ICP patients and healthy pregnant women. Real-time PCR and area under curve (AUC) analysis were performed to predict the values of several miRNAs in the diagnosis of ICP. Bioinformatics analysis and luciferase assays were conducted to identify the target genes of miR-21, miR-29a and miR-590-3p, whose regulatory relationships were then established using real-time PCR, immunohistochemistry (IHC) assay and Western Blot. In the exosomes isolated from urine samples, several miRNAs, including miR-21, miR-29a and miR-590-3p, were differentially expressed between ICP patients and healthy pregnant women. In addition, the gene of intercellular adhesion molecule 1 (ICAM1) was identified as a shared target of miR-21, miR-29a and miR-590-3p, all of which inhibited ICAM1 expression. Therefore, up-regulated expression of miR-21, miR-29a and miR-590-3p in urinary exosomes reduced the expression of ICAM1, which in turn increased the incidence of ICP.

Resveratrol regulates the silent information regulator 1-nuclear factor-κB signaling pathway in intrahepatic cholestasis of pregnancy

AIM

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific liver disease characterized by raised serum bile acids and adverse fetal outcomes. In this study, we aimed to explore the molecular and biochemical mechanism of resveratrol in regulating the silent information regulator 1-nuclear factor-κB (SIRT1-NF-κB) signaling pathway and bile acid biosynthesis in ICP.

METHODS

We analyzed serum and placenta samples from 30 normal and ICP pregnancy women. Then we treated HTR-8/SVneo cells with taurocholic acid (TCA) to mimic ICP conditions before treating these cells with resveratrol, as an activator of SIRT1, and EX-57, as an inhibitor of SIRT1. We established an ICP rat model to analyze the therapeutic effect of resveratrol.

RESULTS

The expression of SIRT1 protein was higher in normal placenta tissues than in ICP, and the expression of NF-κB was lower in the normal group than in the ICP group. We found that SIRT1 was downregulated, whereas NF-κB and tuor necrosis factor-α (TNF-α) were upregulated, in syncytiotrophoblast HTR-8 cells treated with TCA. This phenomenon could be reversed by resveratrol, and these effects could be blocked by Ex-527.

CONCLUSION

These data indicate that resveratrol might protect syncytiotrophoblast against TCA-induced inflammatory injury by upregulation of SIRT1 and downregulation of NF-κB and TNF-α. Resveratrol could be a potential therapeutic target for ICP.

PPARγ provides anti-inflammatory and protective effects in intrahepatic cholestasis of pregnancy through NF-κB pathway

AIMS

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific hepatic disorder with potentially deleterious consequences of fetuses. Although the intimate relationship between ICP and peroxisome proliferator-activated receptor γ (PPARγ) has been previously reported in physiological and pathological conditions, the detailed mechanisms in the process of intrahepatic cholestasis of pregnancy has been unclear. The aims of this study are to assess the role of PPARγ regulating the reactive oxygen species (ROS) and inflammation in the process of the ICP.

METHODS

Clinical data of the pregnant women were collected. And the serum of cytokines, hepatic function, the expression of PPARγ and NF-κB were measured. The rat and fetal rat ICP model were constructed and detection of the expression of PPARγ and NF-κB, evaluation the level of ROS and inflammation.

RESULTS

The clinical data showed that the new-born information in severe ICP group were significantly different as compared to that in control group (P < 0.05), and part of information in mild ICP group were also difference to that in control group (P < 0.05). The expression of PPARγ and NF-κB were significantly higher in clinical pregnant women, rat, fetal rat ICP model groups and taurocholate acid (TCA) treated HTR-8/SVneo cell (P < 0.01). PPARγ inhibited the production of ROS and decreased the level of inflammation. PPARγ down-regulated the NF-κB pathway.

CONCLUSIONS

PPARγ provides the anti-inflammatory and protective effects in intrahepatic cholestasis of pregnancy through NF-κB pathway, which might be a probably one of the mechanisms of ICP.

Expression and significance of dendritic cells and Th17/Treg in serum and placental tissues of patients with intrahepatic cholestasis of pregnancy

PURPOSE

Dendritic cells (DCs) are involved in immune system, which can also regulate the differentiation of T helper 17 (Th17) and regulatory T cells (Treg). DCs and Th17/Treg participate in preeclampsia and recurrent spontaneous abortion (RSA), but there is still lack of research in intrahepatic cholestasis of pregnancy (ICP). The aim was to evaluate the expression and significance of CD83+DCs, CD1a+DCs, interleukin-17 (IL-17) and IL-35 in serum and placental tissues of patients with ICP.

METHODS

Thirty cases of mild ICP, 25 cases of severe ICP were selected, and 30 cases of normal pregnant women were selected as control group. Enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC) were used to detect the expression of CD83+DCs, CD1a+DCs, IL-17 and IL-35 in serum and placenta tissues, respectively.

RESULTS

There were more CD83+DCs, IL-17 expressed in placenta from women with ICP than in normal pregnancies, while the number of decidual CD1a+DCs, IL-35 was significantly lower in ICP than in normal pregnant women. The comparison within three groups had statistical difference (p < .05). Serum CD83+DCs and CD1a+DCs levels had no significance. IL-17 was higher in ICP, while IL-35 was lower.

CONCLUSIONS

DCs are involved in damaging the maternal-fetal immune tolerance by changing the phenotype and mature state, which may affect the differentiation of Th17/Treg to cause ICP.

Bile acids and gestation

There are numerous profound maternal physiological changes that occur from conception onwards and adapt throughout gestation in order to support a healthy pregnancy. By the time of late gestation, when circulating pregnancy hormones are at their highest concentrations, maternal adaptations include relative hyperlipidemia, hypercholanemia and insulin resistance. Bile acids have now been established as key regulators of metabolism, and their role in gestational changes in metabolism is becoming apparent. Bile acid homeostasis is tightly regulated by the nuclear receptor FXR, which has been shown to have reduced activity during pregnancy. This review focuses on the gestational alterations in bile acid homeostasis that occur in normal pregnancy, which in some women can become pathological, leading to the development of intrahepatic cholestasis of pregnancy. As well as their important role in maternal metabolic health, we will review bile acid metabolism in the feto-placental unit.

Downregulation of peroxiredoxin-3 by hydrophobic bile acid induces mitochondrial dysfunction and cellular senescence in human trophoblasts

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific disorder characterised by raised bile acids in foetal-maternal circulation, which threatens perinatal health. During the progression of ICP, the effect of oxidative stress is underscored. Peroxiredoxin-3 (PRDX3) is a mitochondrial antioxidant enzyme that is crucial to balance intracellular oxidative stress. However, the role of PRDX3 in placental trophoblast cells under ICP is not fully understood. We demonstrated that the level of PRDX3 was downregulated in ICP placentas as well as bile acids–treated trophoblast cells and villous explant in vitro. Toxic levels of bile acids and PRDX3 knockdown induced oxidative stress and mitochondrial dysfunction in trophoblast cells. Moreover, silencing of PRDX3 in trophoblast cell line HTR8/SVneo induced growth arrest and cellular senescence via activation of p38-mitogen-activated protein kinase (MAPK) and induction of p21^WAF1/CIP and p16^INK4A. Additionally, enhanced cellular senescence, determined by senescence-associated beta-galactosidase staining, was obviously attenuated by p38-MAPK inhibitor SB203580. Our data determined that exposure to bile acid decreased PRDX3 level in human trophoblasts. PRDX3 protected trophoblast cells against mitochondrial dysfunction and cellular senescence induced by oxidative stress. Our results suggest that decreased PRDX3 by excessive bile acids in trophoblasts plays a critical role in the pathogenesis and progression of ICP.

Bile acids evoke placental inflammation by activating Gpbar1/NF-κB pathway in intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a cholestatic disorder with potentially deleterious consequences for fetuses. Although a clear correlation between the elevated levels of maternal serum bile acids and deficient fetal outcome has been established in clinical practice, the underlying mechanisms remain elusive. Herein, we report that bile acids induce NF-κB pathway activation via G protein-coupled bile acid receptor 1 (Gpbar1), with consequent upregulation of inflammatory genes in trophoblasts, leading to aberrant leukocyte infiltration and inflammation in placenta. Ursodeoxycholic acid (UDCA), a drug used clinically to treat ICP, competes with other bile acids for binding with Gpbar1 and thus inhibits bile acid-induced inflammatory response in trophoblasts and improves fetal survival in pregnant rats with obstructive cholestasis. Notably, inhibition of NF-κB by andrographolide is more effective than UDCA in benefiting placentas and fetuses. Thus, anti-inflammation therapy targeting Gpbar1/NF-κB pathway could be effective in suppressing bile acid-induced inflammation and alleviating ICP-associated fetal disorders.

Immunology of hepatic diseases during pregnancy

The mother's immune system has to adapt to pregnancy accepting the semi-allograft fetus and preventing harmful effects to the developing child. Aberrations in feto-maternal immune adaptation may result in disease of the mother, such as liver injury. Five pregnancy-associated liver disorders have been described so far, however, little is known concerning immune alterations promoting the respective disease. These liver disorders are pre-eclampsia, hemolysis, elevated liver enzymes, low platelet count (HELLP), acute fatty liver, hyperemesis gravidarum, and intrahepatic cholestasis of pregnancy. On the other hand, pre-existing autoimmune liver injury of the mother can be affected by pregnancy. This review intends to summarize current knowledge linking feto-maternal immunology and liver inflammation with a special emphasis on novel potential biomarkers.

The pathophysiology of intrahepatic cholestasis of pregnancy

A number of liver disorders are specific to pregnancy. Amongst these, intrahepatic cholestasis of pregnancy (ICP), also known as obstetric cholestasis (OC), is the commonest, affecting approximately 1 in 140 UK pregnancies. Patients commonly present in the third trimester with severe pruritus and deranged serum liver tests; bile acids are elevated, in severe cases >40 μmol/L. Although the disease is considered relatively benign for the mother, increased rates of adverse fetal outcomes, including stillbirth, are associated with ICP. As our knowledge of the mechanisms underlying bile acid homeostasis has advanced in the last 15 years our understanding of ICP has grown, in particular with respect to genetic influences on susceptibility to the disease, the role of reproductive hormones and their metabolites and the possible identity of the pruritic agents. In this review, we will describe recent advances in the understanding of this condition with a particular emphasis on how aspects of genetic and reproductive hormone involvement in pathophysiology have been elucidated. We also review recent developments regarding our knowledge of placental and fetal pathophysiology and the long-term health consequences for the mother and child.

New Insights on Intrahepatic Cholestasis of Pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is characterized by maternal pruritus, and elevated serum transaminases and bile acids. Genetic defects in at least 6 canalicular transporters have been found. Association studies stress the variability of genotypes, different penetrance, and influence of environmental factors. Serum autotaxin is a sensitive, specific, and robust diagnostic marker. Elevated maternal bile acids correlate with fetal complications. Long-term sequelae for mothers include the gallstone risk and chronic liver disease. There is an association between ICP and hepatitis C. Current treatment is ursodeoxycholic acid, owing to benefits on pruritus, liver function, safety, and decreased rates of adverse effects.

Immunological basis in the pathogenesis of intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy poses a great risk to both maternal and fetal health. Despite extensive research, much of the pathogenesis of this disorder is unknown. The increase in bile acids observed in patients with intrahepatic cholestasis of pregnancy has been noted to cause a change in the immune system from the normally mediated TH2 response to one that is more oriented towards TH1. In this literature review, we have critically reviewed the current literature regarding the changes in the immune system and the potential effects of immunological changes in the management of the patient. The current treatment, ursodeoxycholic acid, is also discussed along with potential combination therapies and future directions for research.

The role of interleukin-17 in intrahepatic cholestasis of pregnancy

OBJECTIVE

Intrahepatic cholestasis of pregnancy (ICP) is the most common pregnancy-specific liver disease, is characterized by pruritus, abnormal liver function and elevated serum bile acid levels. The main cause of ICP has not yet been identified. We aimed to provide a new perspective to the pathogenesis of by investigating the possible association of circulating interleukin-17 (IL-17) that is a recently discovered proinflammatory cytokine levels with ICP.

MATERIALS AND METHODS

In this controlled cross-sectional study, maternal venous blood samples were obtained from 33 consecutive pregnant women with ICP (15 with mild and 18 with severe forms of the disease) and 25 healthy women with uncomplicated pregnancies (as the control group) and IL-17 levels were compared among the groups.

RESULTS

Although serum IL-17 levels were significantly higher in the severe ICP group than in the control group (p = 0.022), there were no significant differences between the mild and severe ICP groups or between the control and mild ICP groups.

CONCLUSION

Explaining the mechanisms of hepatocyte injury might contribute to the existing therapeutic strategies for treating cholestatic diseases. Changes in IL-17 levels may shed light on the pathogenesis of ICP.

Placental ADAMTS-12 Levels in the Pathogenesis of Preeclampsia and Intrahepatic Cholestasis of Pregnancy

Our aim was to determine whether placental A Disintegrin-like Metalloproteinase with ThromboSpondin motif 12 (ADAMTS-12), arylesterase (ARES) levels, total oxidant status (TOS), and total antioxidant status (TAS) differ in preeclampsia, intrahepatic cholestasis of pregnancy (ICP), and uncomplicated pregnancies or not. A prospective case-control study was carried out including 84 pregnant women (26 with ICP, 28 preeclamptic patients, and 30 healthy controls). Levels of ADAMTS-12, TAS, TOS, and ARES were studied in the supernatants of placental tissue homogenates. Placental ADAMTS-12 levels were distributed as 240.9 pg/mg in ICP, 289.7 pg/mg in preeclampsia, and 310.8 pg/mg in control groups. Levels of ADAMTS-12 (odds ratio = 6.509, 95% confidence interval:1.070-39.592, P = .042) in the placenta of the ICP were significantly lower than those in preeclampsia and control groups (P = .004), but no statistical significant difference was determined between preeclampsia and control groups. Decreased levels of placental ADAMTS-12 were found to be associated with ICP, suggesting a possible role of inflammation in the pathogenesis.

Review of a challenging clinical issue: Intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a reversible pregnancy-specific cholestatic condition characterized by pruritus, elevated liver enzymes, and increased serum bile acids. It commences usually in the late second or third trimester, and quickly resolves after delivery. The incidence is higher in South American and Scandinavian countries (9.2%-15.6% and 1.5%, respectively) than in Europe (0.1%-0.2%). The etiology is multifactorial where genetic, endocrine, and environmental factors interact. Maternal outcome is usually benign, whereas fetal complications such as preterm labor, meconium staining, fetal distress, and sudden intrauterine fetal demise not infrequently lead to considerable perinatal morbidity and mortality. Ursodeoxycholic acid is shown to be the most efficient therapeutic agent with proven safety and efficacy. Management of ICP consists of careful monitoring of maternal hepatic function tests and serum bile acid levels in addition to the assessment of fetal well-being and timely delivery after completion of fetal pulmonary maturity. This review focuses on the current concepts about ICP based on recent literature data and presents an update regarding the diagnosis and management of this challenging issue.

Effect of the maternal-fetal interface immunoregulation on the occurrence of intrahepatic cholestasis of pregnancy

Maternal immune tolerance of the fetus is indispensable for a healthy pregnancy. Currently, the study of the immune microenvironment of the maternal-fetal interface has been a heated topic in reproductive immunology research. More and more studies show that the immune imbalance in the maternal-fetal interface plays a very important role in the incidence of intrahepatic cholestasis of pregnancy (ICP). However, the precise etiology and mechanism of immune imbalance in the occurrence of ICP is still unknown. In order to clarify the potential immunologic mechanisms of ICP, this review summarizes the recent studies of the decidual immunology microenvironment and the potential immunologic mechanisms related to the development of ICP.