Investigating into microbiota in the uterine cavity of the unexplained recurrent pregnancy loss patients in early pregnancy.

INTRODUCTION: The majority of unexplained recurrent pregnancy loss (URPL) cases have been attributed to immune abnormalities. Inappropriate changes in microbiota could lead to immune disorders. However, the specific role of uterine cavity microbiota in URPL remains unclear, and only a limited number of related studies are available for reference. METHODS: We utilized double-lumen embryo transfer tubes to collect uterine cavity fluid samples from pregnant women in their first trimester. Subsequently, we conducted 16S rRNA sequencing to analyze the composition and abundance of the microbiota in these samples. RESULTS: For this study, we enlisted 10 cases of URPL and 28 cases of induced miscarriages during early pregnancy. Microbial communities were detected in all samples of the URPL group (100 %, n = 10), whereas none were found in the control group (0 %, n = 28). Among the identified microbes, Lactobacillus and Curvibacter were the two most dominant species. The abundance of Curvibacter is correlated with the number of NK cells in peripheral blood (r = -0.759, P = 0.018). DISCUSSION: This study revealed that during early pregnancy, Lactobacillus and Curvibacter were the predominant colonizers in the uterine cavity of URPL patients and were associated with URPL. Consequently, alterations in the dominant microbiota may lead to adverse pregnancy outcomes.

Pyroelectric Photoconductive Diode for Highly Sensitive and Fast DUV Detection.

Detecting high-energy photons from the deep ultraviolet (DUV) to X-rays is vital in security, medicine, industry, and science. Wide bandgap (WBG) semiconductors exhibit great potential for detecting high-energy photons. However, the implementation of highly sensitive and high-speed detectors based on WBG semiconductors has been a huge challenge due to the inevitable deep level traps and the lack of appropriate device structure engineering. Here, a sensitive and fast pyroelectric photoconductive diode (PPD), which couples the interface pyroelectric effect with the photoconductive effect based on tailored polycrystal Ga-rich GaOx (PGR-GaOx) Schottky photodiode, is first proposed. The PPD device exhibits ultrahigh detection performance for DUV and X-ray light. The responsivity for DUV light and sensitivity for X-ray are up to 104 A W-1 and 105 µC Gyair -1 cm-2, respectively. Especially, the interface pyroelectric effect induced by polar symmetry in the depletion region of the PGR-GaOx can significantly improve the response speed of the device by 105 times. Furthermore, the potential of the device is demonstrated for imaging enhancement systems with low power consumption and high sensitivity. This work fully excavates the potential of the pyroelectric effect for detectors and provides a novel design strategy to achieve sensitive and high-speed detectors.

Motility and tumor infiltration are key aspects of invariant natural killer T cell anti-tumor function.

Dysfunction of invariant natural killer T (iNKT) cells contributes to immune resistance of tumors. Most mechanistic studies focus on their static functional status before or after activation, not considering motility as an important characteristic for antigen scanning and thus anti-tumor capability. Here we show via intravital imaging, that impaired motility of iNKT cells and their exclusion from tumors both contribute to the diminished anti-tumor iNKT cell response. Mechanistically, CD1d, expressed on macrophages, interferes with tumor infiltration of iNKT cells and iNKT-DC interactions but does not influence their intratumoral motility. VCAM1, expressed by cancer cells, restricts iNKT cell motility and inhibits their antigen scanning and activation by DCs via reducing CDC42 expression. Blocking VCAM1-CD49d signaling improves motility and activation of intratumoral iNKT cells, and consequently augments their anti-tumor function. Interference with macrophage-iNKT cell interactions further enhances the anti-tumor capability of iNKT cells. Thus, our findings provide a direction to enhance the efficacy of iNKT cell-based immunotherapy via motility regulation.

Cytotoxic lymphocyte-monocyte complex reflects the dynamics of COVID-19 systemic immune response.

SARS-CoV-2 infection causes a variety of clinical manifestations, many of which originate from altered immune responses, either locally or systemically. Immune cell crosstalk occurs mainly in lymphoid organs. However, systemic cell interaction specific to COVID-19 has not been well characterized. Here, by employing single cell RNA sequencing and imaging flow cytometry analysis, we unraveled, in peripheral blood, a heterogeneous group of cell complexes formed by the adherence of CD14+ monocytes to different cytotoxic lymphocytes, including SARS-CoV-2-specific CD8+ T cells, γδT and NKT cells. These lymphocytes attached to CD14+ monocytes that showing enhanced inflammasome activation and pyroptosis-induced cell death in progression stage, whereas in convalescent phase, CD14+ monocytes with elevated antigen presentation potential were targeted by cytotoxic lymphocytes, thereby restricting the excessive immune activation. Collectively, our study reports previously unrecognized cell-cell interplay in SARS-CoV-2 specific immune response, providing new insight into the intricacy of dynamic immune cell interaction representing anti-viral defense.

Probing the Molecular Structure and Dynamics of Membrane-Bound Proteins during Misfolding Processes by Sum-Frequency Generation Vibrational Spectroscopy.

Protein misfolding and amyloid formation are implicated in the protein dysfunction, but the underlying mechanism remains to be clarified due to the lack of effective tools for detecting the transient intermediates. Sum frequency generation vibrational spectroscopy (SFG-VS) has emerged as a powerful tool for identifying the structure and dynamics of proteins at the interfaces. In this review, we summarize recent SFG-VS studies on the structure and dynamics of membrane-bound proteins during misfolding processes. This paper first introduces the methods for determining the secondary structure of interfacial proteins: combining chiral and achiral spectra of amide A and amide I bands and combining amide I, amide II, and amide III spectral features. To demonstrate the ability of SFG-VS in investigating the interfacial protein misfolding and amyloid formation, studies on the interactions between different peptides/proteins (islet amyloid polypeptide, amyloid ß, prion protein, fused in sarcoma protein, hen egg-white lysozyme, fusing fusion peptide, class I hydrophobin SC3 and class II hydrophobin HFBI) and surfaces such as lipid membranes are discussed. These molecular-level studies revealed that SFG-VS can provide a unique understanding of the mechanism of interfacial protein misfolding and amyloid formation in real time, in situ and without any exogenous labeling.

Antigen Priming Induces Functional Reprogramming in iNKT Cells via Metabolic and Epigenetic Regulation: An Insight into iNKT Cell-Based Antitumor Immunotherapy.

Dysfunction of intratumoral invariant natural killer T (iNKT) cells hinders their antitumor efficacy, but the underlying mechanisms and the relationship with endogenous antigen priming remain to be explored. Here, we report that antigen priming leads to metabolic reprogramming and epigenetic remodeling, which causes functional reprogramming in iNKT cells, characterized by limited cytokine responses upon restimulation but constitutive high cytotoxicity. Mechanistically, impaired oxidative phosphorylation (OXPHOS) in antigen-primed iNKT cells inhibited T-cell receptor signaling, as well as elevation of glycolysis, upon restimulation via reducing mTORC1 activation, and thus led to impaired cytokine production. However, the metabolic reprogramming in antigen-primed iNKT cells was uncoupled with their enhanced cytotoxicity; instead, epigenetic remodeling explained their high expression of granzymes. Notably, intratumoral iNKT cells shared similar metabolic reprogramming and functional reprogramming with antigen-primed iNKT cells due to endogenous antigen priming in tumors, and thus recovery of OXPHOS in intratumoral iNKT cells by ZLN005 successfully enhanced their antitumor responses. Our study deciphers the influences of antigen priming-induced metabolic reprogramming and epigenetic remodeling on functionality of intratumoral iNKT cells, and proposes a way to enhance efficacy of iNKT cell-based antitumor immunotherapy by targeting cellular metabolism.

LncRNA PVT1 promotes strong stemness and endothelial progenitor cell characteristics in renal carcinoma stem cells.

Renal cancer stem cells (RCSCs) derived from clear cell renal cell carcinoma (ccRCC) tissues with higher microvessel density (MVD) have strong stemness and endothelial progenitor cells-like (EPCs-like) characteristics. A high level of lncRNA PVT1 expression is essential for simultaneously retaining strong RCSC stemness and EPCs-like characteristics. PVT1 binds with TAZ protein and prevents its phosphorylation, which promotes RCSC stemness. Moreover, RCSCs support endothelial differentiation and angiogenesis, which are mediated via the PVT1/miR-15b/KDR axis. This report provides insight into the determinants of RCSC impact on stemness and highlights the critical role of RCSC in angiogenesis. The presented findings suggest that targeting RCSC through PVT1 expression may be a new treatment strategy for ccRCC.

HIVEP3 inhibits fate decision of CD8+ invariant NKT cells after positive selection.

CD8+ invariant natural killer T (iNKT) cells are functionally different from other iNKT cells and are enriched in human but not in mouse. To date, their developmental pathway and molecular basis for fate decision remain unclear. Here, we report enrichment of CD8+ iNKT cells in neonatal mice due to their more rapid maturation kinetics than CD8- iNKT cells. Along developmental trajectories, CD8+ and CD8- iNKT cells separate at stage 0, following stage 0 double-positive iNKT cells, and differ in HIVEP3 expression. HIVEP3 is lowly expressed in stage 0 CD8+ iNKT cells and negatively controls their development, whereas it is highly expressed in stage 0 CD8- iNKT cells and positively controls their development. Despite no effect on IFN-γ, HIVEP3 inhibits granzyme B but promotes interleukin-4 production in CD8+ iNKT cells. Together, we reveal that, as a negative regulator for CD8+ iNKT fate decision, low expression of HIVEP3 in stage 0 CD8+ iNKT cells favors their development and T helper 1-biased cytokine responses as well as high cytotoxicity.

PKM2 allosteric converter: A self-assembly peptide for suppressing renal cell carcinoma and sensitizing chemotherapy.

Stronger intrinsic Warburg effect and resistance to chemotherapy are the responses to high mortality of renal cell carcinoma (RCC). Pyruvate kinase M2 (PKM2) plays an important role in this process. Promoting PKM2 conversion from dimer to tetramer is a critical strategy to inhibit Warburg effect and reverse chemotherapy resistance. Herein, a PKM2 allosteric converter (PAC) is constructed based on the "in vivo self-assembly" strategy, which is able to continuously stimulate PKM2 tetramerization. The PAC contains three motifs, a serine site that is protected by enzyme cleavable ß-N-acetylglucosamine, a self-assembly peptide and a AIE motif. Once PAC nanoparticles reach tumor site via the EPR effect, the protective and hydrophilic ß-N-acetylglucosamine will be removed by over-expressed O-GlcNAcase (OGA), causing self-assembled peptides to transform into nanofibers with large serine (PKM2 tetramer activator) exposure and long-term retention, which promotes PKM2 tetramerization continuously. Our results show that PAC-induced PKM2 tetramerization inhibits aberrant metabolism mediated by Warburg effect in cytoplasm. In this way, tumor proliferation and metastasis behavior could be effectively inhibited. Meanwhile, PAC induced PKM2 tetramerization impedes the nuclear translocation of PKM2 dimer, which restores the sensitivity of cancer cells to first-line anticancer drugs. Collectively, the innovative PAC effectively promotes PKM2 conversion from dimer to tetramer, and it might provide a novel approach for suppressing RCC and enhancing chemotherapy sensitivity.

Isolation and genomic analysis of a novel bacteriophage IME278 infecting Enterobacter hormaechei and its biocontrol potential on pork.

Enterobacter hormaechei is an opportunistic pathogen and is found in a large variety of food including animal-derived food. In recent years, bacteria present a severe clinical challenge due to their increasing resistance to antibiotics. Bacteriophages have gained attention as a new antibacterial strategy. In this study, we isolated a novel E. hormaechei bacteriophage IME278 from hospital sewage in Beijing, China. Bacteriophage IME278 had a double-stranded linear DNA genome with 40,164 bp and 51.99% GC content. Whole-genome alignments showed IME278 shared 87% homology with other phages in the National Center for Biotechnology Information (NCBI) database. And phylogenetic analysis demonstrated that IME278 was highly similar to bacteriophages belonging to the genus Kayfunavirus, family Autographiviridae, indicating IME278 can be classified as a new member of the Autographiviridae family. Transmission electron microscopy revealed that IME278 had an icosahedral head 51.72 nm in diameter and a tail 151.28 nm in length. Bacteriophage IME278 was able to survive under high temperature (50 °C-70 °C) and its activity decreased significantly above 70 °C and almost completely inactivated at 80 °C. Bacteriophage IME278 could survive in a wide pH range (4.0-11.0) and it was stable in chloroform (up to 5%). The phage was sensitive to UV irradiation. Bacteriophage IME278 had a latent period of 40 min and reached a plateau stage at 150 min and its cleavage was approximately 8.21 × 108/3.66 × 108 = 2.24. The biocontrol potential of bacteriophage IME278 was evaluated in a model that artificially contaminated pork with E. hormaechei 529 and the result revealed that IME278 could effectively control bacterial contamination on pork. The in-depth analysis of the biological characteristics, whole genome sequencing, and bioinformatics of IME278 has laid the foundation for the biocontrol application and the treatment of bacteria using bacteriophages.

Pyroptosis-Related Subtypes Predict the Response of Clear Cell Renal Cell Carcinoma to Targeted Therapy.

BACKGROUND: Pyroptosis plays a crucial role in anti-tumor immunity and in formation of the immune microenvironment. However, whether pyroptosis is involved in the progression of clear cell renal cell carcinoma (ccRCC) is still unclear. Personalized treatment of ccRCC requires detailed molecular classification to inform a specific therapy. METHODS: Molecular subtyping of ccRCC was performed based on consensus clustering of pyroptosis-related genes. The characteristics of these molecular subtypes were explored at the genome, transcriptome and protein levels. Single-cell RNA sequencing and CIBERSORT analysis were used to analyse the immune microenvironment of ccRCC, while Lasso regression was used to develop a prediction model based on hub genes. Expression of the pyroptosis-related gene GSDMB was also investigated at the tissue and cellular levels. RESULTS: Two molecular subtypes were identified based on the clustering of pyroptosis-related genes. Cluster 1 was associated with activation of classical oncogenic pathways, especially the angiogenesis pathway. Cluster 2 was associated with activation of immune-related pathways and high levels of immunosuppressive cells, exhausted CD8+ T cells, and tumor-associated fibroblast infiltration. Clusters 1 and 2 were thus defined as the angiogenic and inflamed subtypes, respectively. The two subtypes were predictive of the response of ccRCC to anti-angiogenic therapy and immunotherapy, with Cluster 1 patients benefiting from anti-angiogenic therapy and Cluster 2 patients showing better response to anti-PD1 inhibitor therapy. Furthermore, a 9-gene expression signature (HJURP, NUF2, KIF15, MELK, TPX2, PLK1, CDCA3, CTLA4, FOXP3) was identified that could predict outcome and response to immune checkpoint blockade therapy in test cohorts. Finally, GSDMB was found to be involved in the development of renal clear cell carcinoma. CONCLUSIONS: These results on pyroptosis-related genes in ccRCC provide a theoretical basis for understanding molecular heterogeneity and for the development of individualized treatment strategies.

Isolation and characterization of the novel bacteriophage vB_SmaS_BUCT626 against Stenotrophomonas maltophilia.

Stenotrophomonas maltophilia has been recognized as an emerging global opportunistic pathogen, and it is intrinsically resistant to most antibiotics, which makes the limited choice for treating S. maltophilia infections. Bacteriophage with the proper characterization is considered as a promising alternative treatment option to control S. maltophilia infections. In this study, we isolated a novel Siphoviridae bacteriophage vB_SmaS_BUCT626 with lytic activity against S. maltophilia. Phage vB_SmaS_BUCT626 can lysis 10 of 20 S. maltophilia and was relatively stable at a wide range of temperatures (4-70 °C) and pH values (3.0-13.0) and exhibited good tolerance to chloroform. The genome of phage vB_SmaS_BUCT626 was a 61,662-bp linear double-stranded DNA molecule with a GC content of 56.2%, and contained 100 open-reading frames. It carried no antibiotic resistance, toxin, virulence-related genes, or lysogen-formation gene clusters. Together, these characteristics make phage vB_SmaS_BUCT626, a viable candidate as a biocontrol agent against S. maltophilia infection.

Identification of liver-specific CD24+ invariant NK T cells with low granzyme B production and high proliferative capacity.

Invariant NK T (iNKT) cells are innate-like lymphocytes that can recognize the lipid Ag presented by MHC I like molecule CD1d. Distinct tissue distribution of iNKT cells subsets implies a contribution of these subsets to their related tissue regional immunity. iNKT cells are enriched in liver, an organ with unique immunological properties. Whether liver-specific iNKT cells exist and dedicate to the liver immunity remains elusive. Here, a liver-specific CD24+ iNKT subset is shown. Hepatic CD24+ iNKT cells show higher levels of proliferation, glucose metabolism, and mTOR activity comparing to CD24- iNKT cells. Although CD24+ iNKT cells and CD24- iNKT cells in the liver produce similar amounts of cytokines, the hepatic CD24+ iNKT cells exhibit lower granzyme B production. These liver-specific CD24+ iNKT cells are derived from thymus and differentiate into CD24+ iNKT in the liver microenvironment. Moreover, liver microenvironment induces the formation of CD24+ conventional T cells as well, and these cells exhibit higher proliferation ability but lower granzyme B production in comparison with CD24- T cells. The results propose that liver microenvironment might induce the generation of liver-specific iNKT subset that might play an important role in maintaining liver homeostasis.

Vam6 reduces iNKT cell function in tumor via modulating AMPK/mTOR pathways.

Activation of mTORC1 is essential for anti-tumor function of iNKT cells. The mechanisms underlying impaired mTORC1 activation in intratumoral iNKT cells remain unclear. Via generating Vam6+/- mice and using flow cytometry, image approach, and RNA sequencing, we studied the role of Vam6 in controlling mTORC1 activation and intratumoral iNKT cell functions. Here, we find that increased Vam6 expression in intratumoral iNKT cells leads to impaired mTORC1 activation and IFN-γ production. Mechanistically, Vam6 in iNKT cells is essential for Rab7a-Vam6-AMPK complex formation and thus for recruitment of AMPK to lysosome to activate AMPK, a negative regulator of mTORC1. Additionally, Vam6 relieves inhibitory effect of VDAC1 on Rab7a-Vam6-AMPK complex formation at mitochondria-lysosome contact site. Moreover, we report that lactic acid produced by tumor cells increases Vam6 expression in iNKT cells. Given the key roles of increased Vam6 in promoting AMPK activation in intratumoral iNKT cells, reducing Vam6 expression signifificantly enhances the mTORC1 activation in intratumoral iNKT cells as well as their anti-tumor effificacy. Together, we propose Vam6 as a target for iNKT cell-based immunotherapy.

Understanding recurrent pregnancy loss: recent advances on its etiology, clinical diagnosis, and management.

Recurrent pregnancy loss (RPL) has become an important reproductive health issue worldwide. RPL affects about 2%-3% of reproductive-aged women, and makes serious threats to women's physical and mental health. However, the etiology of approximately 50% of RPL cases remains unknown (unexplained RPL), which poses a big challenge for clinical management of these patients. RPL has been widely regarded as a complex disease where its etiology has been attributed to numerous factors. Heretofore, various risk factors for RPL have been identified, such as maternal ages, genetic factors, anatomical structural abnormalities, endocrine dysfunction, prethrombotic state, immunological factors, and infection. More importantly, development and applications of next generation sequencing technology have significantly expanded opportunities to discover chromosomal aberrations and single gene variants responsible for RPL, which provides new insight into its pathogenic mechanisms. Furthermore, based upon patients' diagnostic evaluation and etiologic diagnosis, specific therapeutic recommendations have been established. This review will highlight current understanding and recent advances on RPL, with a special focus on the immunological and genetic etiologies, clinical diagnosis and therapeutic management.

iNKT subsets differ in their developmental and functional requirements on Foxo1.

Invariant natural killer T (iNKT) cells play important roles in regulating immune responses. Based on cytokine profiling and key transcriptional factors, iNKT cells are classified into iNKT1, iNKT2, and iNKT17 subsets. However, whether the development and functions of these subsets are controlled by distinct mechanisms remains unclear. Here, we show that forkhead box protein O1 (Foxo1) promotes differentiation of iNKT1 and iNKT2 cells but not iNKT17 cells because of its distinct contributions to IL7R expression in these subsets. Nuclear Foxo1 is essential for Il7r expression in iNKT1 and iNKT2 cells at early stages of differentiation but is dispensable in iNKT17 cells. RORγt, instead of Foxo1, promotes IL7R expression in iNKT17 cells. Additionally, Foxo1 is required for the effector function of iNKT1 and iNKT2 cells but not iNKT17 cells. Cytoplasmic Foxo1 promotes activation of mTORC1 in iNKT1 and iNKT2 cells through inhibiting TSC1-TSC2 interaction, whereas it is dispensable for mTORC1 activation in iNKT17 cells. iNKT17 cells display distinct metabolic gene expression patterns from iNKT1 and iNKT2 cells that match their different functional requirements on Foxo1. Together, our results demonstrate that iNKT cell subsets differ in their developmental and functional requirements on Foxo1.

ASC deglutathionylation is a checkpoint for NLRP3 inflammasome activation.

Activation of NLRP3 inflammasome is precisely controlled to avoid excessive activation. Although multiple molecules regulating NLRP3 inflammasome activation have been revealed, the checkpoints governing NLRP3 inflammasome activation remain elusive. Here, we show that activation of NLRP3 inflammasome is governed by GSTO1-promoted ASC deglutathionylation in macrophages. Glutathionylation of ASC inhibits ASC oligomerization and thus represses activation of NLRP3 inflammasome in macrophages, unless GSTO1 binds ASC and deglutathionylates ASC at ER, under control of mitochondrial ROS and triacylglyceride synthesis. In macrophages expressing ASCC171A, a mutant ASC without glutathionylation site, activation of NLRP3 inflammasome is GSTO1 independent, ROS independent, and signal 2 less dependent. Moreover, AscC171A mice exhibit NLRP3-dependent hyperinflammation in vivo. Our results demonstrate that glutathionylation of ASC represses NLRP3 inflammasome activation, and GSTO1-promoted ASC deglutathionylation at ER, under metabolic control, is a checkpoint for activating NLRP3 inflammasome.

Changes in the Distribution of Intrauterine Microbiota May Attribute to Immune Imbalance in the CBA/J×DBA/2 Abortion-Prone Mice Model.

Background: Female Genital Tract (FGT) is an important micro-ecological area of human body. Microbiota in the lower reproductive tract may subsequently invade the uterine cavity during embryo implantation and produce immune responses. CBA/J×DBA/2 mating combination has been widely used as an abortion-prone mice model but whether microbiota existed in their uterine cavity remains unclear. In this context, the role of the microbial communities in immune response deserves attention. Objective: To investigate the relationship between the distribution of microbiota in the uterine cavity of CBA/J×DBA/2 abortion-prone mouse model and the immune imbalance of the maternal-fetal interface. Methods: In this study, female CBA/J mice were paired with male DBA/2 mice to develop an abortion-prone model (BA group), and with male BALB/c mice to build a standard pregnancy model (BC group). The non-pregnant female mice were served as the control group (C group). Uterine flushing fluid and sera were collected on day 13.5 of pregnancy. 16S rRNA sequencing technology was used to analyze the distribution of intrauterine microbiota. Phylogenetic Investigation of Communities were conducted to predict the microbiota functions by Reconstruction of Unobserved States (PICRUST) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The serum IL 10, INF-γ, and TNF-α levels were examined using Enzyme-linked immunosorbent assay (ELISA) method. Results: All samples were detected with microbial communities. The α diversity (p = 0.00077) had significant differences among three groups. Proteobacteria was the most dominant phylum in C group (mean = 83.21%) and BA group (mean = 43.23%). Firmicutes was dominant in BC group (mean = 46.4%), as well as the second dominant one in C group (mean = 12.63%) and BA group (mean = 40.55%). Microbiota functions were associated with metabolism and immune response through the NOD-like receptor signaling pathway. The serum IL 10 level in BA group were significantly lower than that in BC group (10.14 ± 1.90 pg/ml, n = 8; vs. 19.03 ± 1.82 pg/ml, n = 10; p = 0.004). The serum TNF-α and INF-γ level in BA group were also significantly higher than that in BC group (523.1 ± 58.14 pg/ml, n = 8 vs. 310.3 ± 28.51 pg/ml, n = 10, p = 0.0029; 69.22 ± 5.38 pg/ml, n = 8 vs. 50.85 ± 2.45 pg/ml, n = 10, p = 0.0042). Conclusion: Microbial communities were colonized in uterine cavity of CBA/J mice both at non-pregnant stage and pregnant stage when mated with both BALB/c and DBA/2 male mice. The differentially abundant microbiome may be attributed to the immune tolerance through binding to the NOD-like receptor.

SO2 derivatives induce dysfunction in human trophoblasts via inhibiting ROS/IL-6/STAT3 pathway.

BACKGROUND: Epidemiological studies have revealed that sulfur dioxides (SO2) can increase the risk of pregnancy complications such as missed abortion in the first trimester, stillbirth, preterm birth, small for gestational age, gestational diabetes mellitus and preeclampsia, but the mechanisms underlying these findings remains unknown. What is known, however, is that trophoblasts, a type of fetal cell exerting vital immunologic functions to maintain a successful pregnancy, are usually involved in the pathogenic mechanism of pregnancy complications. OBJECTIVE: To study the effect of SO2 derivatives (bisulfite and sulfite, 1:3 M/M) on the function of trophoblasts. METHODS: Swan.71 trophoblast cells were treated with various concentrations of SO2 derivatives to determine the effect of SO2 derivatives on cellular viability by CKK8. Flow cytometry was performed to analyze the effect of SO2 derivatives on apoptosis, cell cycle and intracellular ROS. Wound healing assay and transwell assay were conducted to examine the migration and invasion of Swan.71 cells. Inflammation-related cytokines in the supernatant (IL-1ß, IL-6, IL-8, IL-10 and TNF-α) were measured by IMMULITE®1000 Systems (SIEMENS). The expression level of NLRP3, Caspase1, MMP9, MMP2, STAT3, and p-STAT3 were evaluated by Western Blotting. RESULTS: Exposure to SO2 derivatives significantly decreased cellular viability, arrested cell cycle at S/G2/M phase and induced cell apoptosis of Swan.71 trophoblasts. In addition, the migration and invasion of Swan.71 cell were significantly inhibited. SO2 derivatives also significantly increased IL-1ß secretion while it is NLRP3/Caspase1 independent. IL-6 secretion was significant inhibited accompanied by decreased STAT3 phosphorylation and expression of MMP2 and MMP9. The intracellular ROS level was significantly suppressed by SO2 derivatives. CONCLUSION: SO2 derivatives exert toxic effects on trophoblasts which results in: suppressing cellular viability and intracellular ROS level, interfering with cell proliferation through arresting cell cycle, inducing cell apoptosis, disturbing inflammation-related cytokines secretion and inhibiting motility. Decreased ROS/IL-6/STAT3 levels play a role in inhibited cell viability, cell cycle arrest, apoptosis and defective motility.