MDSCs in pregnancy and pregnancy-related complications: an update†

Decreased number of myeloid-derived suppressor cells in the placental trophoblast of gestational diabetes mellitus. Possible role of leptin

Gestational diabetes mellitus (GDM) is the most common complication of pregnancy and significantly increases both maternal and fetal morbidity and mortality. Inflammation is a hallmark of GDM, and placental inflammation may play a key role in the pathophysiology of the disease. Myeloid-derived suppressor cells (MDSCs), which are innate immunosuppressive, are thought to contribute to feto-maternal tolerance. In normal pregnancies, elevated levels of MDSCs have been observed in both peripheral and umbilical cord blood. Our hypothesis postulates that trophoblasts from placentas belonging to women with GDM may have lower levels of MDSCs compared to trophoblasts from placentas originating from healthy pregnancies. Furthermore, since leptin is overexpressed in the placenta of GDM patients, we hypothesized that leptin might contribute to the reduction of MDSCs. To test this, we investigated the in vitro effects of leptin on MDSC levels in isolated peripheral blood leukocytes after 24 h of incubation. Our findings indicate that trophoblasts from placentas from women with GDM contain a lower percentage of MDSCs compared to trophoblasts from healthy pregnancies. In addition, in vitro studies demonstrated that leptin reduces the number of MDSCs in peripheral blood leukocytes. In conclusion, MDSCs are decreased in placentas from pregnancies with GDM, and leptin appears to reduce the number of MDSCs in leukocytes isolated in vitro. Increased leptin expression in trophoblasts from placentas of women with GDM may contribute to the lower levels of MDSCs, potentially playing a role in placental inflammation. However, further investigations are required to fully elucidate this mechanism.

Decoding immune tolerance in infertility: Exploring immune pathways and non-coding RNAs as pioneering biomarkers and therapeutic targets

Infertility, impacting a significant number of couples, is characterized by the failure to conceive after one year of consistent, unprotected sexual intercourse. It is multifactorial, with etiological contributors including ovulatory dysfunction, male reproductive anomalies, and tubal patency issues. Approximately 15% of infertility cases are classified as "unexplained," highlighting the complexity of this condition. Lifestyle determinants such as obesity and smoking further complicate reproductive outcomes, while infertility can also indicate underlying chronic health conditions. A specialized category, immune infertility, arises from a breakdown of immunological tolerance, an essential aspect for conception and the maintenance of pregnancy. The role of various immunological components, including immune cells, cytokines, chemokines, factors like HLA-G, etc., is pivotal in this context. Moreover, non-coding RNAs (ncRNAs) have emerged as critical regulators of immune tolerance within the reproductive axis. This review synthesizes the complex immunological pathways vital for successful implantation and the early stages of pregnancy alongside the regulatory roles of ncRNAs in these processes. Offering an integrated view of molecular and immunological interactions associated with infertility seeks to enhance our understanding of potential strategies to facilitate successful conception and sustain early pregnancy.

Association between cellular immune and preeclampsia and preterm birth: A Mendelian randomization study

Emerging evidences have highlighted immune-inflammatory imbalances as a critical driver of the pathogenesis for preeclampsia (PE) and preterm birth (PB), but the impact of specific immune factors on the diseases is largely unknown. Our aim was to determine whether these immune cells are causally associated with the onset of PE or PB. Drawing on publicly available genetic data, we applied Mendelian randomization analysis to probe the causal link of 731 immune traits (7 panels: TBNK panel, Regulatory T cells panel, Maturation stages of T-cell panel, Dendritic cell panel, B-cell panel, Monocyte panel and Myeloid cell pane) with the risk of PE and PB. The inverse variance weighting method (IVW) acted as the primary analysis to estimate the validity of causality, and sensitivity analyses were conducted to assessment of heterogeneity and pleiotropy. After adjusting for P-values for FDR method, CD27 on CD24+ CD27+ B cell, CD80 on plasmacytoid Dendritic Cell, CD33+ HLA DR+ CD14dim Absolute Count, CD33+ HLA DR+ CD14- Absolute Count, CD33+ HLA DR+ Absolute Count were remarkably causally involved in increased risk of PE, while HLA DR on Dendritic Cell exerted a protective causation against PE (PFDR < 0.05). Moreover, we determined that CD45 on CD33dim HLA DR- in myeloid cells decreased PB risk, whereas CD11b on Granulocytic Myeloid-Derived Suppressor Cells had the opposite effect on PB (FFDR < 0.2). This study provided genetic evidence for causal relationships between immune cell traits and PE and PB, offering potential candidate immunophenotypes for future studies on the etiology of pregnancy complications.

Pharmacological and toxicological characteristics of baicalin in preventing spontaneous abortion and recurrent pregnancy loss: A multi-level critical review

Relevance

Spontaneous abortion (SAB) and recurrent pregnancy loss (RPL) occur alone or concurrently with increasing incidences recently. Scutellaria baicalensis Georgi (SBG) has been used to prevent pregnancy loss for thousands of years, which is recognized as a "pregnancy-stabilizing herb" in ancient China. Baicalin (BA) and its metabolite baicalein (BE) are the main bioactive flavonoids in the root of SBG.

Methods

In this study, we focused particularly on the metabolism, toxicology, and pharmacological effects of BA at the maternal-fetal interface based on the biological process prediction by network pharmacology. Focused on the systematic review of BA's regulatory mechanisms of immune homeostasis, cell proliferation and invasion, programmed cell death, inflammatory microenvironment, angiogenesis, oxidative stress and vascular remodeling at the maternal-fetal interface, it was found that BA exerts its biological effects to treat SAB and RPL through multiple perspectives and targets. We also critically elucidated the limitations of using BA from a clinical perspective.

Results

We explored the bioavailability, targeting and efficacy of BA from a new perspective (optimization of the BA delivery system, organoid studies based on BA, potential effects of BA on uterine flora and bioactive components). Finally, we propose a multimodal stereo sequencing study of biologically active components based on pathological dynamics incorporating single-cell RNA sequencing, spatially resolved transcriptomics, and single-cell multimodal omics to delve deeper into the fetal-preserving mechanism of BA and to promote the application of BA in clinical practice.

Innate and adaptive immune dysregulation in women with recurrent implantation failure

Recurrent implantation failure (RIF) is a condition where a woman fails to obtain pregnancy after multiple embryo transfer cycles, even with superior-quality blastocysts. There are various factors that can contribute to RIF, including immunologic disturbances. The immune system is extremely important during pregnancy. Immune cells such as T cells, B cells, natural killer (NK) cells, and macrophages (MQ) are present in the female reproductive tract and are accountable for regulating the immune response to invading pathogens and maintaining tissue homeostasis. Dysregulation of these immune cells can lead to inflammation, which can impair fertility. One of the most common immunological disturbances observed in RIF is an altered Th1/Th2 ratio, along with changes in NK cell and macrophage numbers. In addition, the presence of some antibodies, such as anti-ovarian antibodies, can also contribute to RIF. Interleukins have been implicated in the development of an inflammatory response that can interfere with successful embryo implantation. As a result, a comprehensive understanding of immunological compartments in RIF women could assist us in determining the immunological origins of this disease. We will discuss immunological factors that might contribute to RIF etiology, including cellular and molecular components.

MCC950 attenuates plasma cell mastitis in an MDSC-dependent manner

Plasma cell mastitis (PCM) is a sterile inflammatory condition primarily characterized by periductal inflammation and ductal ectasia. Currently, there is a lack of non-invasive or minimally invasive treatment option other than surgical intervention. The NLRP3 inflammasome has been implicated in the pathogenesis and progression of various inflammatory diseases, however, its involvement in PCM has not yet been reported. In this study, we initially observed the pronounced upregulation of NLRP3 in both human and mouse PCM tissue and elucidated the mechanism underlying the attenuation of PCM through inhibition of NLRP3. We established the PCM murine model and collected samples on day 14, when inflammation reached its peak, for subsequent research purposes. MCC950, an NLRP3 inhibitor, was utilized to effectively ameliorate PCM by significantly reducing plasma cell infiltration in mammary tissue, as well as attenuate the expression of pro-inflammatory cytokines including IL-1β, TNF-α, IL-2, and IL-6. Mechanistically, we observed that MCC950 augmented the function of myeloid-derived suppressor cells (MDSCs), which in turn inhibited the infiltration of plasma cells. Furthermore, it was noted that depleting MDSCs greatly compromised the therapeutic efficacy of MCC950. Collectively, our findings suggest that the administration of MCC950 has the potential to impede the progression of PCM by augmenting MDSCs both numerically and functionally, ultimately treating PCM effectively. This study provides valuable insights into the utilization of pharmacological agents for PCM treatment.

Kisspeptin prevents pregnancy loss by modulating the immune microenvironment at the maternal-fetal interface in recurrent spontaneous abortion

PROBLEM

Immune factors are crucial in the development of recurrent spontaneous abortion (RSA). This study aimed to investigate whether kisspeptin regulates immune cells at the maternal-fetal interface and whether G protein-coupled receptor 54 (GPR54) is involved in this process, through which it contributes to the pathogenesis of RSA.

METHOD OF STUDY

Normal pregnancy (NP) (CBA/J × BALB/c) and RSA (CBA/J × DBA/2) mouse models were established. NP mice received tail vein injections of PBS and KP234 (blocker of kisspeptin receptor), whereas RSA mice received PBS and KP10 (active fragment of kisspeptin). The changes in immune cells in mouse spleen and uterus were assessed using flow cytometry and immunofluorescence. The expression of critical cytokines was examined by flow cytometry, ELISA, Western blotting, and qPCR. Immunofluorescence was employed to detect the coexpression of FOXP3 and GPR54.

RESULTS

The findings revealed that the proportion of Treg cells, MDSCs, and M2 macrophages in RSA mice was lower than that in NP mice, but it increased following the tail vein injection of KP10. Conversely, the proportion of these cells was reduced in NP mice after the injection of KP234. However, the trend of γδT cell proportion change is contrary to these cells. Furthermore, FOXP3 and GPR54 were coexpressed in mouse spleen and uterus Treg cells as well as in the human decidua samples.

CONCLUSION

Our results suggest that kisspeptin potentially participates in the pathogenesis of RSA by influencing immune cell subsets at the maternal-fetal interface, including Treg cells, MDSC cells, γδT cells, and M2 macrophages.

Myeloid-derived suppressor cells in the therapy of autoimmune diseases

Myeloid-derived suppressor cells (MDSCs) are well recognized as critical factors in the pathology of tumors. However, their roles in autoimmune diseases are still unclear, which hampers the development of efficient immunotherapies. The role of different MDSCs subsets in multiple sclerosis, inflammatory bowel diseases, rheumatoid arthritis, type 1 diabetes, and systemic lupus erythematosus displayed different mechanisms of immune suppression, and several studies pointed to MDSCs' capacity to induce T-helper (Th)17 cells and tissue damage. These results also suggested that MDSCs could be present in different functional states and utilize different mechanisms for controlling the activity of T and B cells. Therefore, various therapeutic strategies should be employed to restore homeostasis in autoimmune diseases. The therapies harnessing MDSCs could be designed either as cell therapy or rely on the expansion and activation of MDSCs in vivo, or their depletion. Cumulatively, MDSCs are inevitable players in autoimmunity, and rational approaches in developing therapies are required to avoid the adverse effects of MDSCs and harness their suppressive mechanisms to improve the overall efficacy of autoimmunity therapy.