Mechano-regulation of Peptide-MHC Class I Conformations Determines TCR Antigen Recognition.

TCRs recognize cognate pMHCs to initiate T cell signaling and adaptive immunity. Mechanical force strengthens TCR-pMHC interactions to elicit agonist-specific catch bonds to trigger TCR signaling, but the underlying dynamic structural mechanism is unclear. We combined steered molecular dynamics (SMD) simulation, single-molecule biophysical approaches, and functional assays to collectively demonstrate that mechanical force induces conformational changes in pMHCs to enhance pre-existing contacts and activates new interactions at the TCR-pMHC binding interface to resist bond dissociation under force, resulting in TCR-pMHC catch bonds and T cell activation. Intriguingly, cancer-associated somatic mutations in HLA-A2 that may restrict these conformational changes suppressed TCR-pMHC catch bonds. Structural analysis also indicated that HLA polymorphism might alter the equilibrium of these conformational changes. Our findings not only reveal critical roles of force-induced conformational changes in pMHCs for activating TCR-pMHC catch bonds but also have implications for T cell-based immunotherapy.

γδ T cell antigen receptor polyspecificity enables T cell responses to a broad range of immune challenges.

γδ T cells are essential for immune defense and modulating physiological processes. While they have the potential to recognize large numbers of antigens through somatic gene rearrangement, the antigens which trigger most γδ T cell response remain unidentified, and the role of antigen recognition in γδ T cell function is contentious. Here, we show that some γδ T cell receptors (TCRs) exhibit polyspecificity, recognizing multiple ligands of diverse molecular nature. These ligands include haptens, metabolites, neurotransmitters, posttranslational modifications, as well as peptides and proteins of microbial and host origin. Polyspecific γδ T cells are enriched among activated cells in naive mice and the responding population in infection. They express diverse TCR sequences, have different functional potentials, and include the innate-like γδ T cells, such as the major IL-17 responders in various pathological/physiological conditions. We demonstrate that encountering their antigenic microbiome metabolite maintains their homeostasis and functional response, indicating that their ability to recognize multiple ligands is essential for their function. Human γδ T cells with similar polyspecificity also respond to various immune challenges. This study demonstrates that polyspecificity is a prevalent feature of γδ T cell antigen recognition, which enables rapid and robust T cell responses to a wide range of challenges, highlighting a unique function of γδ T cells.

Single-cell transcriptome analyses reveal disturbed decidual homoeostasis in obstetric antiphospholipid syndrome.

OBJECTIVES: Obstetric antiphospholipid syndrome (OAPS) is an autoimmune disease characterised by the presence of antiphospholipid antibodies in circulation and pathological pregnancy. However, the pathogenesis of OAPS remains unknown. We aimed to reveal cellular compositions and molecular features of decidual cells involved in the development of OAPS using single-cell RNA sequencing (scRNA-seq). METHODS: We performed unbiased scRNA-seq analysis on the first-trimester decidua from five OAPS patients and five healthy controls (HCs), followed by validations with flow cytometry, immunohistochemical staining and immunofluorescence in a larger cohort. Serum chemokines and cytokines were measured by using ELISA. RESULTS: A higher ratio of macrophages but a lower ratio of decidual natural killer (dNK) cells was found in decidua from OAPS compared with HCs. Vascular endothelial cells shrinked in OAPS decidua while having upregulated chemokine expression and conspicuous responses to IFN-γ and TNF-α. Macrophages in OAPS had stronger phagocytosis function, complement activation signals and relied more on glycolysis. dNK cells were more activated in OAPS and had enhanced cytotoxicity and IFN-γ production. Downregulation of granules in OAPS dNK cells could be associated with suppressed glycolysis. Moreover, stromal cells had a prosenescent state with weakened immune surveillance for senescent cells in OAPS. In addition, the cellular interactions between decidual immune cells and those of immune cells with non-immune cells under disease state were altered, especially through chemokines, IFN-γ and TNF-α. CONCLUSION: This study provided a comprehensive decidual cell landscape and identified aberrant decidual microenvironment in OAPS, providing some potential therapeutic targets for this disease.

The function of γδ T cells in humoral immune responses.

PURPOSE: The purpose of this review is to discuss the role of γδ T cells played in humoral immune responses. BACKGROUND: The γδ T cell receptor (γδ TCR) recognizes antigens, including haptens and proteins, in an MHC-independent manner. The recognition of these antigens by γδ TCRs crosses antigen recognition by the B cell receptors (BCRs), suggesting that γδ T cells may be involved in the process of antigen recognition and activation of B cells. However, the role of γδ T cells in humoral immune responses is still less clear. METHODS: The kinds of literature about the γδ T cell-B cell interaction were searched on PubMed with search terms, such as γδ T cells, antibody, B cell responses, antigen recognition, and infection. RESULTS: Accumulating evidence indicates that γδ T cells, independent of αß T cells, participate in multiple steps of humoral immunity, including B cell maturation, activation and differentiation, antibody production and class switching. Mechanically, γδ T cells affect B cell function by directly interacting with B cells, secreting cytokines, or modulating αß T cells. CONCLUSION: In this review, we summarize current knowledge on how γδ T cells take part in the humoral immune response, which may assist future vaccine design.

A single peptide-major histocompatibility complex ligand triggers digital cytokine secretion in CD4(+) T cells.

We have developed a single-molecule imaging technique that uses quantum-dot-labeled peptide-major histocompatibility complex (pMHC) ligands to study CD4(+) T cell functional sensitivity. We found that naive T cells, T cell blasts, and memory T cells could all be triggered by a single pMHC to secrete tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2) cytokines with a rate of ∼1,000, ∼10,000, and ∼10,000 molecules/min, respectively, and that additional pMHCs did not augment secretion, indicating a digital response pattern. We also found that a single pMHC localized to the immunological synapse induced the slow formation of a long-lasting T cell receptor (TCR) cluster, consistent with a serial engagement mechanism. These data show that scaling up CD4(+) T cell cytokine responses involves increasingly efficient T cell recruitment rather than greater cytokine production per cell.

The role of adenosine A1 receptor on immune cells.

BACKGROUND: Adenosine, acting as a regulator by mediating the activation of G protein-coupled adenosine receptor families (A1, A2A, A2B, and A3), plays an important role under physiological and pathological conditions. As the receptor with the highest affinity for adenosine, the role of adenosine A1 receptor (A1R)-mediated adenosine signaling pathway in the central nervous system has been well addressed. However, functions of A1R on immune cells are less summarized. Considering that some immune cells express multiple types of adenosine receptors with distinct effects and varied density, exogenous adenosine of different concentrations may induce divergent immune cell functions. MATERIALS AND METHODS: The literatures about the expression of A1R and its regulation on immune cells and how it regulates the function of immune cells were searched on PubMed and Google Scholar. CONCLUSION: In this review, we discussed the effects of A1R on immune cells, including monocytes, macrophages, neutrophils, dendritic cells, and microglia, and focused on the role of A1R in regulating immune cells in diseases, which may facilitate our understanding of the mechanisms by which adenosine affects immune cells through A1R.

Metal-Chelatable Porphyrinic Frameworks for Single-Cell Multiplexing with Mass Cytometry.

Single-cell multiplexing is key to exploration of the heterogeneous cell populations in biological systems. Although the state-of-the-art mass cytometry (CyTOF) possesses high resolution and multiple dimensions, the lack of suitable marker materials prohibits fully exploiting the available CyTOF detection channels. Here we report a new design strategy for CyTOF markers using functionalized mesoporous porphyrinic frameworks (MPFs) as scaffolds for chelating metals that have been unachievable by conventional approaches. We developed surface modification for stably dispersing the MPF nanoparticles (<40 nm) during the metalation and antibody conjugation processes. Our markers exhibit higher sensitivity and comparable specificity compared with a polymer-based commercial benchmark. Compatibility with commercial markers during co-staining was also confirmed. Furthermore, our markers show promising performance for immunophenotyping and potential implementation in CyTOF systems.

γδ T cells recognize a microbial encoded B cell antigen to initiate a rapid antigen-specific interleukin-17 response.

γδ T cells contribute uniquely to immune competence. Nevertheless, how they function remains an enigma. It is unclear what most γδ T cells recognize, what is required for them to mount an immune response, and how the γδ T cell response is integrated into host immune defense. Here, we report that a noted B cell antigen, the algae protein phycoerythrin (PE), is a murine and human γδ T cell antigen. Employing this specificity, we demonstrated that antigen recognition activated naive γδ T cells to make interleukin-17 and respond to cytokine signals that perpetuate the response. High frequencies of antigen-specific γδ T cells in naive animals and their ability to mount effector response without extensive clonal expansion allow γδ T cells to initiate a swift, substantial response. These results underscore the adaptability of lymphocyte antigen receptors and suggest an antigen-driven rapid response in protective immunity prior to the maturation of classical adaptive immunity.

Combined treatment of prednisone and hydroxychloroquine may improve outcomes of frozen embryo transfer in antinuclear antibody-positive patients undergoing IVF/ICSI treatment.

BACKGROUND: The influence of anti-nuclear antibody (ANA) on induced ovulation was controversial, and the effect of prednisone plus hydroxychloroquine (HCQ) treatment on frozen embryo transfer outcomes of in-vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) for ANA-positive women was unclear. METHODS: Fifty ANA-positive women and one-hundred ANA-negative women matched for age and anti-Mullerian hormone (AMH) were included from a Reproductive Medical Central of a University Hospital. Sixty-one oocytes pick-up (OPU) cycles in ANA+ group and one-hundred OPU cycles in ANA- group were compared; 30 frozen embryo transfer cycles without treatment and 66 with prednisone plus HCQ treatment among ANA-positive women were compared. RESULTS: There was no statistical difference in number of retrieved oocytes (13.66 ± 7.71 vs 13.72 ± 7.23, p = .445), available embryos (5.23 ± 3.37 vs 5.47 ± 3.26, p = .347), high-quality embryos (3.64 ± 3.25 vs 3.70 ± 3.52, p = .832), and proportion of high-quality embryos (26.5% vs. 26.7%, p = .940). Biochemical pregnancy rate (33.3% vs. 68.2%, p < .05), clinical pregnancy rate (20.0% vs. 50.1%, p < .05), and implantation rate (5.6% vs. 31.8%, p < .05) were lower, and pregnancy loss rate (83.3% vs. 23.1%, p < .05) was higher in patients with treatment than no treatment. CONCLUSION: The influence of ANA on number of retrieved oocytes, available embryos, high-quality embryos, and proration of high-quality embryos was not found. The treatment of prednisone plus HCQ may improve implantation rate, biochemical pregnancy rate, and clinical pregnancy rate, and reduce pregnancy loss rate in frozen embryo transfer outcomes for ANA-positive women.

Astragalus protects PC12 cells from 6-hydroxydopamine-induced neuronal damage: A serum pharmacological study.

Accumulating evidence has already indicated that traditional Chinese medicine (TCM) possesses tremendous potential for treating neurodegenerative diseases. Astragalus, also named Huangqi, is a famous traditional medical herb that can be applied to treat cerebral ischemia and prevent neuronal degeneration. Nevertheless, the underlying mechanisms remain largely unexplored. In the present study, Astragalus-containing serum (ASMES) was prepared and added into the culture medium of PC12 cells to explore its neuroprotective effect on 6-hydroxydopamine (6-OHDA)-caused neuronal toxicity. Our data showed that ASMES significantly ameliorated the cellular viability of cultured PC12 cells against the neurotoxicity induced by 6-OHDA (P < 0.05). Moreover, ASMES significantly decreased the cell apoptosis triggered by 6-OHDA (P < 0.01). Furthermore, 2',7'-dichlorofluorescin diacetate assay was performed to detect the changes in oxidative stress, and we showed that 6-OHDA elevated the production of reactive oxygen species (ROS), whereas ASMES significantly reversed these changes (P < 0.01). Besides, mitochondrial membrane potential (MMP) assay showed that ASMES could restore 6-OHDA-damaged MMP in cultured PC12 cells (P < 0.05). In conclusion, Astragalus could protect PC12 cells from 6-OHDA-caused neuronal toxicity, and possibly, the ROS-mediated apoptotic pathway participated in this process. Collectively, our findings provided valuable insights into the potential in treatment of neurodegenerative diseases.

Reduced frequency and functional defects of CD4+CD25highCD127low/- regulatory T cells in patients with unexplained recurrent spontaneous abortion.

BACKGROUND: Unexplained recurrent spontaneous abortion (URSA) is defined as two or more consecutive pregnancy losses, generally of unknown cause; it is related to a failure of fetal-maternal immunological tolerance. Regulatory T cells (Tregs) exert immunosuppressive effects, which are essential to maintain fetal-maternal immunological tolerance and regulate immune balance. In this study, we used the specific cell-surface phenotype of CD4+CD25highCD127low/- Tregs to investigate the number and suppressive function of Tregs isolated from the peripheral blood of patients with URSA with the aim of expanding our understanding of their role in URSA. METHODS: We isolated a relatively pure population of peripheral CD4+CD25highCD127low/- Tregs and CD4+CD25- responder T cells (Tresps) from the patients with URSA and normal fertile nonpregnant control women via fluorescence-activated cell sorting. We compared the frequency, suppressive capacity, and forkhead box transcription factor P3 (FOXP3) expression of Tregs in the peripheral blood between patients with URSA and normal controls. RESULTS: The frequency of CD4+CD25highCD127low/- Tregs in the peripheral blood was lower in URSA patients than in the controls (P < 0.05). The mean fluorescence intensity of FOXP3 and FOXP3 mRNA expression in Tregs was also significantly lower in the URSA patients (P < 0.01). Tregs suppressed the activity of autologous Tresps stimulated with anti-CD3/CD28 beads in a concentration-dependent manner, with the strongest suppression occurring in cocultures with a 1:1 Treg:Tresp ratio in both groups; however, patient-derived Tregs exhibited a poorer capacity to suppress the proliferation of autologous Tresps than the Tregs from normal controls (P < 0.01). Moreover, Tregs isolated from URSA patients inhibited the proliferation of Tresps from normal controls less potently than the Tregs from normal controls (P < 0.01), and Tresps from URSA patients were less effectively suppressed by autologous Tregs than by those from normal controls (P < 0.01). Tresp activity were intact in both groups. CONCLUSIONS: We observed a lower frequency of peripheral CD4+CD25highCD127low/- Tregs with lower FOXP3 expression in the peripheral blood of URSA patients. In addition, highly purified Tregs from patients with URSA exhibited impaired suppressive effects. The defect in immune regulation in URSA patients appears to be primarily related to impaired Tregs, and not to increased resistance of Tresps to suppression. Our findings reveal a potential novel therapeutic target for URSA.

Association between Ambient Air Pollution and Pregnancy Outcomes in Patients Undergoing In Vitro Fertilization in Chengdu, China: A retrospective study.

Ambient air pollution has been a major concern in China due to its effect on population health. Exposure to ambient air pollution has negative impact on animal reproduction and fertility, however, its effect on human reproduction has been inconclusive. We conducted a retrospective study on in vitro fertilization (IVF) patients from Chengdu, Sichuan Province in western China, a city with persistent ambient air pollution. We analyzed the medical records of 1139 patients who underwent first conventional IVF cycles during 2014-2019. The relationship between six atmospheric pollutants (PM2.5, PM10, O3, NO2, SO2, CO) and IVF pregnancy outcomes were assessed by 1) stratification of maternal age into three groups (<35, 35-39, ≥40 years), and by 2) averaging pollutant concentration during different exposure windows. The results indicate that the association between ambient air pollution and IVF pregnancy outcomes (biochemical pregnancy and clinical pregnancy) is more significant for women in <35 years age group. Concentrations of PM2.5, PM10, NO2, SO2 and CO are negatively associated with the odds of biochemical pregnancy and clinical pregnancy, and concentration of CO in particular is associated with the largest reduction in odds. Conversely, O3 concentration is positively associated with biochemical pregnancy and clinical pregnancy. Moreover, pollutant concentration during long-term exposure window is associated with larger magnitude of change in the odds of biochemical pregnancy and clinical pregnancy. Findings from this study suggest that exposure to ambient air pollution during any period within the IVF treatment timeline would influence IVF pregnancy outcomes, and such influence is more pronounced in younger women (<35 years).

Detection, phenotyping, and quantification of antigen-specific T cells using a peptide-MHC dodecamer.

Here we report a peptide-MHC (pMHC) dodecamer as a "next generation" technology that is a significantly more sensitive and versatile alternative to pMHC tetramers for the detection, isolation, and phenotypic analysis of antigen-specific T cells. In particular, dodecamers are able to detect two- to fivefold more antigen-specific T cells in both human and murine CD4(+)and CD8(+)αß T-cell compartments compared with the equivalent tetramers. The low-affinity, tetramer-negative, dodecamer-positive T cells showed comparable effector cytokine responses as those of high-affinity, tetramer-positive T cells. Dodecamers are able to detect early stage CD4(+)CD8(+)double-positive thymocytes on which T-cell receptors are 10- to 30-fold less dense than mature T cells. Dodecamers also show utility in the analysis of γδ T cells and in cytometry by time-of-flight applications. This construct has a simple structure with a central scaffold protein linked to four streptavidin molecules, each having three pMHC ligands or other molecules. The dodecamer is straightforward and inexpensive to produce and is compatible with current tetramer technology and commercially available streptavidin conjugates.

[Expression of HSP70 in Kunming Mouse Embryos Stimulated by Chronic Mild Anticipatory Stress].

OBJECTIVE: To measure the expression of heat shock protein 70 (HSP70) in mice embryos with the stimulation of chronic mild anticipatory stress (CUMS) to female Kunming mice. METHODS: Three hundreds female Kunming mice were stressed by 9 chronic mild unpredictable stress factors for 28 days and then divided into three groups of mild, moderate and severe stress. PMSG/hCG was measured to assess the induction of superovulation, and ovarian response and embryo development potential were observed. The expression of HSP70 in 2-cell embryos and day 4 embryos was detected by immunofluorescence and real time polymerase chain reaction (RT-PCR). RESULTS: After 28 d CUMS stimulation, the rate of mice in mild, moderate and severe stress were 50%, 32% and 18%, respectively. In the mild stress group, ovarian response and oocyte development potential were similar to those of control, while HSP70 expression of the embryos was significantly higher (P<0.05). In the severe stress group, ovarian response and oocyte development potential were significantly decreased compared with the control group (P<0.05), while HSP70 expression was similar to that of control. CONCLUSION: HSP70 overexpression observed in the embryos may be related to its proteetive effect against chronic unpredictable stress.

The natural and the inducible: interleukin (IL)-17-producing γδ T cells.

γδ T cells are the major initial interleukin (IL)-17 producers in acute infections. Recent studies have indicated that some γδ T cells have IL-17-producing capabilities without explicit induction of an immune response. They are preferentially localized in barrier tissues and are likely to originate from fetal γδ thymocytes. In addition, γδ T cells present in the secondary lymphoid organs will mature and differentiate to produce IL-17 after antigen encounter in an immune response. Based on these studies, we propose that there are two different sets of IL-17-producing γδ T cells (Tγδ17) referred to as the 'natural' and the 'inducible' Tγδ17 cells. This review focuses on recent publications leading to the delineation of these two types of cells and their implied roles in host immune defense.

HSP70 overexpression may play a protective role in the mouse embryos stimulated by CUMS.

BACKGROUND: We evaluated whether heat shock protein HSP70 plays a protective role in the embryos of Kunming mice subjected to chronic unpredictable mild stress. METHODS: Female mice were stimulated for 4 weeks with nine stressors and then divided into mild, moderate and severe stress groups. Superovulation was induced with a gonadotropin preparation (PMSG/HCG) and HSP70 expression in 2-cell embryos and day 4 embryos was detected by immunofluorescence (IF) and real-time polymerase chain reaction (RT-PCR). RESULTS: In the mild stress group, ovarian response and oocyte development potential were similar to those of the control group, while the HSP70 mRNA levels of the embryos were significantly higher (P < 0.05). In the severe stress group, ovarian response and oocyte development potential decreased compared with the control group (P < 0.05), while the HSP70 mRNA levels were similar. The results of the moderate stress group were intermediate among the three groups. Furthermore, HSP70 mRNA levels of the embryos were shown to be positively associated with parameters of oocyte and embryo development potential (P < 0.05). CONCLUSIONS: HSP70 overexpression may play a protective role in the embryos of the mild or moderate stress mice stimulated by chronic unpredictable mild stress.

Ligand recognition during thymic development and gammadelta T cell function specification.

gammadelta T cells develop in the thymus before entering the periphery. Recent work suggests that thymic development does little to constrain gammadelta T cell antigen specificities, but instead determines their effector fate. When triggered through the T cell receptor, ligand-naïve gammadelta T cells produce IL-17, ligand-experienced cells make IFN-gamma and those that are strongly self-reactive make IL-4. Importantly, gammadelta T cells are able to make cytokines immediately upon TCR engagement. These characteristics allow gammadelta T cells to initiate an acute inflammatory response to pathogens and to host antigens revealed by injury. These advances warrant a fresh look at how gammadelta T cells may function in the immune system.

Cluster analysis reveals a homogeneous subgroup of PCOS women with metabolic disturbance associated with adverse reproductive outcomes.

BACKGROUND: Polycystic ovarian syndrome (PCOS) is a heterogeneous and complex reproductive endocrinological disease that could lead to infertility. There were many attempts to classify PCOS but it remains unclear whether there is a specific subgroup of PCOS that is associated with the best or worst reproductive outcomes of assisted reproductive techniques (ART). METHODS: Infertile PCOS patients who underwent their first cycle of in vitro fertilization (IVF) in West China Second University Hospital, Sichuan University from January 2019 to December 2021 were included. Basic clinical and laboratory information of each individual were extracted. Unsupervised cluster analysis was performed. Controlled ovarian stimulation parameters and reproductive outcomes were collected and compared between the different clusters of PCOS. RESULTS: Our analysis clustered women with PCOS into "reproductive", "metabolic", and "balanced" clusters based on nine traits. Reproductive group was characterized by high levels of testosterone (T), sex hormone-binding globulin (SHBG), follicular stimulation hormone (FSH), luteinizing hormone (LH), and anti-Müllerian hormone (AMH). Metabolic group was characterized by high levels of body mass index (BMI), fasting insulin, and fasting glucose. Balanced group was characterized by low levels of the aforementioned reproductive and metabolic parameters, except for SHBG. Compared with PCOS patients in reproductive and balanced clusters, those in metabolic cluster had lower rates of good quality day 3 embryo and blastocyst formation. Moreover, PCOS patients in the reproductive cluster had greater fresh embryo transfer (ET) cancelation rate and clinical pregnancy rate after fresh ET than metabolic cluster (odds ratio [OR] = 3.37, 95% confidence interval [CI]: 1.77-6.44, and OR = 6.19, 95% CI: 1.58-24.24, respectively). And compared with PCOS of metabolic cluster, PCOS of balanced cluster also had higher chance for fresh ET cancelation (OR = 2.83, 95% CI: 1.26-6.35). CONCLUSION: Our study suggested that PCOS patients in metabolic cluster may be associated with adverse reproductive outcomes and might need individualized treatment and careful monitoring before and during ART.

Challenges and strategies in relation to effective CAR-T cell immunotherapy for solid tumors.

Chimeric Antigen Receptor T cell (CAR-T) therapy has revolutionized cancer treatment, but its application to solid tumors is limited. CAR-T cells have poor incapability of entering, surviving, proliferating, and finally exerting function in the tumor microenvironment. This review summarizes the main strategies related to enhancing the infiltration, efficacy, antigen recognition, and production of CAR-T in solid tumors. Additional applications of CAR-γδ T and macrophages are also discussed. We believe CAR-T will be a milestone in treating solid tumors once these problems are solved.

Effects of different gonadotropin preparations in GnRH antagonist protocol for patients with polycystic ovary syndrome during IVF/ICSI: a retrospective cohort study.

Purpose: To compare the effects of recombinant FSH alfa (rFSH-alfa), rFSH-beta, highly purified human menopausal gonadotropin (HP-hMG) and urinary FSH (uFSH) in women with polycystic ovarian syndrome who have undertaken the GnRH antagonist protocol during IVF/ICSI treatment. Method: A single-center retrospective cohort study including women with PCOS who received the GnRH antagonist protocol from January 2019 to July 2022 was conducted. Patients were divided into rFSH-alfa group, HP-hMG group, uFSH group, and rFSH-beta group, and the number of oocytes retrieved, clinical pregnancy rate of the fresh cycle (primary outcomes), embryo quality, and severe OHSS rate (secondary outcomes) were compared. Results: No statistical differences were found among the four groups in fresh cycle clinical pregnancy rate (p=0.426), nor in the subgroup analyses. The HP-hMG group had a smaller number of oocytes retrieved and a higher high-quality D3 embryo rate than the three FSH groups (p<0.05). No statistical differences were found among the four groups in the severe OHSS rate (p=0.083). Conclusion: For women with PCOS undergoing the GnRH antagonist protocol, the clinical pregnancy rates of fresh IVF/ICSI-ET cycle are similar for all four types of Gn. With a lower risk of OHSS and a similar number of high-quality and available embryos, HP-hMG may have an advantage in the PCOS population.