Cytochrome P450 26A1 modulates natural killer cells in mouse early pregnancy

Identification and Verification of Potential Markers Related to Myocardial Fibrosis by Bioinformatics Analysis

Mounting evidence indicates that myocardial fibrosis (MF) is frequently intertwined with immune and metabolic disorders. This comprehensive review aims to delve deeply into the crucial role of immune-related signature genes in the pathogenesis and progression of MF. This exploration holds significant importance as understanding the underlying mechanisms of MF is essential for developing effective diagnostic and therapeutic strategies. The dataset GSE9735 about myocardial fibrosis and non-fibrosis was downloaded from GEO database. Differentially expressed genes (DEGs) were identified by 'limma' package in R software. Then, the biological function of DEG was determined by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. XCell was used to estimate the composition pattern of matrix and immune cells. Protein-protein interaction (PPI) network was constructed based on STRING analysis software, and Hub genes were screened and functional modules were analyzed. The correlation between hub genes and immune cell subtypes was analyzed. Hub genes with |correlation coefficient|> 0.45 and p-value < 0.05 were used as characteristic biomarkers. Finally, the logistic regression model is used to verify the three markers in the training set and verification set (GSE97358 and GSE225336). A total of 635 DEGs were identified. Functional enrichment analysis shows that inflammation and immune response, extracellular matrix and structural remodeling play an important role in the pathological mechanism of MF. Immune cell infiltration analysis showed that immune cells (Plasma cells, Eosinophils, Chondrocytes and Th2 cells) significantly changed in MF pathological conditions. In PPI network analysis, IL1β, TTN, PTPRC, IGF1, ALDH1A1, CYP26A1, ALDH1A3, MYH11, CSF1R and CD80 were identified as hub genes, among which IL1β, CYP26A1 and GNG2 were regarded as immune-related characteristic markers. The AUC scores of the three biomarkers are all above 0.65, which proves that they have a good discrimination effect in MF. In this study, three immune-related genes were identified as diagnostic biomarkers of MF, which provided a new perspective for exploring the molecular mechanism of MF. This study takes a comprehensive approach to understanding the intricate relationship between myocardial fibrosis and immune metabolism. By identifying key immune-related biomarkers, this study not only reveals the molecular basis of myocardial fibrosis but also paves the way for the development of novel diagnostic tools and therapeutic strategies. These findings are critical for improving patient prognosis and may have broader implications for studying and treating other cardiovascular diseases associated with immune dysregulation.

Palmitic Acid Upregulates CD96 Expression to Mediate Maternal-Foetal Interface Immune Tolerance by Inhibiting Cytotoxic Activity and Promoting Adhesion Function in Human Decidual Natural Killer Cells

Decidual natural killer cells (dNK cells) are an essential component of the immune cells present at the maternal-foetal interface during early pregnancy, and they play a vital role in various physiological processes. Abnormalities in the ratio or function of dNK cells have been linked to recurrent miscarriages. CD96 has been previously shown to regulate NK cell function in the tumour microenvironment; however, its role and mechanism at the maternal-foetal interface remains unclear. The present study aimed to investigate the immunomodulatory role of CD96 in dNK cells and its function at the maternal-foetal interface. Immunofluorescence staining and flow cytometry were used to detect the expression of cellular markers such as CD96. Furthermore, the secretory function, adhesion-function-related molecules, and cell proliferation markers of CD96+ and CD96- dNK cells were detected using flow cytometry. In addition, we performed cell culture experiments via the magnetic bead sorting of NK cells to detect changes in the expression of the aforementioned functional molecules in dNK cells after the CD96 blockade. Furthermore, we examined the functional characteristics of dNK cells after palmitic acid treatment at a concentration of 10 μM. We also examined the changes in dNK cell function when subjected to the combined effect of palmitic acid and CD96 antagonists. The results indicated that CD96, TIGIT, CD155, and CD112 were highly expressed at the maternal-foetal interface, with dNK cells predominantly expressing CD96, whereas TIGIT was mainly expressed on T cells, and CD155 and CD112 were mainly present in metaphase stromal and trophoblast cells. CD96+ dNK cells displayed low cytotoxic activity and a high adhesion phenotype, which mediated the immunosuppressive effect on dNK cells at the maternal-foetal interface. Palmitic acid upregulated CD96 expression on the surface of dNK cells in the coculture system, inhibiting dNK cell activity and increasing their adhesion molecule expression. CD96 antagonist treatment blocked the inhibitory effect of trophoblasts on dNK cells, resulting in enhanced cytokine secretion and reduced adhesion. The results of this study provide valuable insight into the immunomodulatory role of CD96 in dNK cells and its mechanism at the maternal-foetal interface, particularly in metaphase NK cells. This study sheds light on the mechanisms of immune regulation at the maternal-foetal interface and their implications for the study of recurrent miscarriages of unknown origin.

Cytochrome P450 26A1 regulates the clusters and killing activity of NK cells during the peri-implantation period

Cytochrome P450 26A1 (CYP26A1) plays a vital role in early pregnancy in mice. Our previous studies have found that CYP26A1 affects embryo implantation by modulating natural killer (NK) cells, and that there is a novel population of CYP26A1⁺ NK cells in the uteri of pregnant mice. The aim of this study was to investigate the effects of CYP26A1 on the subsets and killing activity of NK cells. Through single-cell RNA sequencing (scRNA-seq), we identified four NK cell subsets in the uterus, namely, conventional NK (cNK), tissue-resident NK (trNK) 1 and 2, and proliferating trNK (trNKp). The two most variable subpopulations after uterine knockdown of CYP26A1 were trNKp and trNK2 cells. CYP26A1 knockdown significantly downregulated the expression of the NK cell function-related genes Cd44, Cd160, Vegfc, and Slamf6 in trNK2 cells, and Klra17 and Ogn in trNKp cells. Both RNA-seq and cytotoxicity assays confirmed that CYP26A1⁺ NK cells had low cytotoxicity. These results indicate that CYP26A1 may affect the immune microenvironment at the maternal-foetal interface by regulating the activity of NK cells.

Cytochrome P450 26A1 Modulates the Polarization of Uterine Macrophages During the Peri-Implantation Period

Uterine M1/M2 macrophages activation states undergo dynamic changes throughout pregnancy, and inappropriate macrophages polarization can cause adverse pregnancy outcomes, especially during the peri-implantation period. Our previous studies have confirmed that Cytochrome P450 26A1 (CYP26A1) can affect embryo implantation by regulating uterine NK cells and DCs. The aim of this study was to investigate whether CYP26A1 regulates the polarization of uterine macrophages in early pregnancy. Here, we observed that Cyp26a1 was significantly upregulated in M1 as compared with M2 of uterine macrophages, Raw264.7 and iBMDM. Knockdown of CYP26A1 in mice uterine significantly decreased the number of embryo implantation sites and the proportion of CD45⁺F4/80⁺CD206⁻ M1-like uterine macrophages. Primary uterine macrophages treated with anti-CYP26A1 antibody expressed significantly lower levels of M1 markers Nos2, Il1b, Il6 and Tnf-a. In CYP26A1 knockout Raw264.7 cells, the protein levels of M1 markers TNF-α, IL-6 and CD86 were significantly decreased as compared with the wild type cells. Moreover, CYP26A1 deficiency decreased the ability to produce nitric oxide and increased the phagocytosis capacity of Raw264.7 cells under M1 stimulation state. The re-introduction of CYP26A1 partially reversed the polarization levels of M1 in CYP26A1 knockout Raw264.7 cells. CYP26A1 may regulate the polarization of uterine macrophages to M1 through Stap1 and Slc7a2. In summary, these results indicate that CYP26A1 plays a significant role in macrophage polarization, and knockdown of CYP26A1 can cause insufficient M1 polarization during the peri-implantation period, which has adverse effects on blastocyst implantation.

A novel Cytochrome P450 26A1 expressing NK cell subset at the mouse maternal-foetal interface

Cyp26a1 had important roles in mouse embryo implantation and was highly expressed in some of NK cells at the human maternal-foetal interface in early pregnancy. However, the regulatory effect of Cyp26a1 on NK cells remains poorly understood. Through qPCR and flow cytometric assays, we found that Cyp26a1 was expressed by mouse uterine NK cells but not spleen NK cells during the peri-implantation period and there was a group of NK cells that highly expressed Cyp26a1, that is Cyp26a1+ NK cell subset. single cell-population transcriptome sequencing on Cyp26a1+ NK and Cyp26a1- NK cell subsets was performed. We found that there were 3957 differentially expressed genes in the Cyp26a1+ NK cell subset with a cut-off of fold change ≥2 and FDR < 0.01, 2509 genes were up-regulated and 1448 genes were down-regulated in Cyp26a1+ NK cell subset. Moreover, cytokine-cytokine receptor interaction signalling pathway and natural killer cell-mediated cytotoxicity signalling pathway were enriched according to KEGG pathway enrichment analysis. We further found that the expression of Gzma and Klrg1 was significantly increased and Fcgr4 was significantly decreased when inhibiting Cyp26a1. Our experimental results show that there is a novel NK cell subset of Cyp26a1+ NK cells in mouse uterus and Cyp26a1 can regulate the gene expression of Gzma, Klrg1 and Fcgr4 in the Cyp26a1+ NK cells.

Cytochrome P450 26A1 modulates uterine dendritic cells in mice early pregnancy

Cytochrome P450 26A1 (CYP26A1) plays important roles in the mice peri‐implantation period. Inhibiting its expression or function leads to pregnancy failure. However, little is known about the underlying mechanisms involved, especially the relationship between CYP26A1 and immune cells. In this study, using Cyp26a1‐specific antisense morpholigos (Cyp26a1‐MO) knockdown mice model and pCR3.1‐Cyp26a1 vaccine mice model, we found that the number of uterine CD45⁺CD11c⁺MHCII^lo‐hiF4/80⁻ dendritic cells (DCs) was significantly decreased in the treated mice. The percentage of mature DCs (CD86^hi) was obviously lower and the percentage of immature DCs (CD86^lo) was remarkably higher in uterine DCs in the treatment group than that of the control group. Further experiments found that ID2, a transcription factor associated with DCs development, and CD86, a DC mature marker molecule, were both significantly reduced in mice uteri in the treated group. In vitro, ID2 and CD86 also decreased in bone marrow‐derived DCs under Cyp26a1‐MO treatment. These findings provide novel information that CYP26A1 might affect the embryo implantation via modulating the differentiation and maturation of uterine DCs.

Elongation of Müllerian ducts and connection to urogenital sinus determine the borderline of uterine and vaginal development

In female mice, proximal, middle and caudal Müllerian ducts (MDs) differentiate into oviduct, uterus and vagina, respectively. The fates of female reproductive tract epithelia are determined by the mesenchyme. However, the mesenchymal fate determination system is still unclear. It is reported that presence or absence of retinoic acid (RA) signaling in MD mesenchyme induced uterine or vaginal mesenchyme, respectively. To analyze determination of the borderline, RA signal switching factors were found to play critical roles. Expression of a RA metabolizing enzyme, CYP26A1, was high in the epithelium of caudal MD and urogenital sinus, indicating that the enzyme causes the absence of RA signaling in the region. mRNA expression of some transcription factors regulating Aldh1a2, RA synthesis enzyme expressed in MDs, in other tissues was detected in MDs. When the transcription factor genes were overexpressed in a uterine mesenchymal cell line, C/ebpδ overexpression stimulated Aldh1a2 expression. Furthermore, C/EBPδ protein was strongly expressed in the proximal and middle regions of the MDs and bound to the Aldh1a2 promoter in vivo. Since C/ebpδ mRNA expression was maintained at the same level in proximal, middle and caudal MDs, we hypothesize that a high frequency of mitosis induces a low level protein expression in MD mesenchyme. In fact, the mitotic activity was significantly high in caudal mesenchyme, and a mathematical model showed that a gradient of protein was induced by cell proliferation. Therefore, morphogenesis of MDs controls the fate of mesenchyme via RA degradation in urogenital sinus and a gradient of proteins involved in RA synthesis.

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Degradation of RA by CYP26A1 is involved in fate determination of vaginal mesenchyme.

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C/EBPδ can directly bind to Aldh1a2 promoter and stimulates the expression.

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Müllerian ductal cell proliferation causes protein gradient involved in RA synthesis.