Effect of TIM-3 Blockade on the Immunophenotype and Cytokine Profile of Murine Uterine NK Cells

Association of adverse fetal outcomes with placental inflammation after oral gestational exposure to hexafluoropropylene oxide dimer acid (GenX) in Sprague-Dawley rats

Hexafluoropropylene oxide dimer acid (HFPO-DA), known as "GenX" for its trade name, is gradually taking the place of Perfluorooctanoic acid (PFOA). However, there is a poor understanding of the developmental effects of GenX. This study aims to explore whether GenX produces adverse effects on offspring development in Sprague-Dawley (SD) rats and the underlying mechanisms. Pregnant rats were orally administered with GenX (0, 1, 10 and 100 mg/kg/day) from gestational 0.5-19.5 days. Experimental data showed that the exposure to GenX resulted in increased rats' gestational weight gain, whereas both body weight and body length of their fetuses born naturally were significantly reduced. This could contribute to the developmental delays of fetal body weight, body length and tail length from postnatal 1-21 days. Histopathological evaluation of placenta indicated that GenX exposure led to neutrophil infiltration in decidual zone and congestion in labyrinth zone. Moreover, placental proteomics showed changes at the expression levels of the inflammation-related proteins in the Rap1 signaling pathway. In conclusion, gestational exposure to GenX induced fetal intrauterine and extrauterine development retardation in SD rats. Placental inflammation may play a key role in this process through the Rap1 signaling pathway.

Efficacy of mesenchymal stromal cells in the treatment of unexplained recurrent spontaneous abortion in mice: An analytical and systematic review of meta-analyses

OBJECTIVES

Unexplained recurrent spontaneous abortion (URSA) remains an intractable reproductive dilemma due to the lack of understanding of the pathogenesis. This study aimed to evaluate the preclinical evidence for the mesenchymal stromal cell (MSC) treatment for URSA.

METHODS

A meticulous literature search was independently performed by two authors across the Cochrane Library, EMBASE, and PubMed databases from inception to April 9, 2023. Each study incorporated was assessed using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk of bias tool. The amalgamated standardized mean difference (SMD) accompanied by 95% confidence interval (CI) were deduced through a fixed-effects or random-effects model analysis.

RESULTS

A total of ten studies incorporating 140 mice were subjected to data analysis. The MSC treatment yielded a significant reduction in the abortion rate within the URSA model (OR = 0.23, 95%CI [0.17, 0.3], P<0.00001). Moreover, it elicited a positive modulatory impact on the expression profiles of several inflammatory cytokines in the decidual tissue of URSA murine models, inclusive of IL4 (SMD 1.63, 95% CI [0.39, 2.86], P = 0.01), IL10 (SMD 1.60, 95% CI [0.58, 2.61], P = 0.002), IFN-γ (SMD -1.66, 95%CI [-2.79, -0.52], P = 0.004), and TNF-α (SMD -1.98, 95% CI [-2.93, -1.04], P< 0.0001). Subgroup analyses underscored that the administration mode of intraperitoneal and uterine horn injections, and sources of bone MSCs and adipose-derived MSCs contributed positively to the expression of IL4, IL10, and decreased the expression of IFN-γ in decidual tissue of URSA (P<0.05). Conversely, the tail vein injections subgroup was observed with no statistical significance (P>0.05).

CONCLUSIONS

The findings underscore the considerable potential of MSCs in URSA therapy. Nonetheless, the demand for enhanced transparency in research design and direct comparisons between various MSC sources and administration routes in URSA is paramount to engendering robust evidence that could pave the way for successful clinical translation.

A newly intervention strategy in preeclampsia: Targeting PD-1/Tim-3 signaling pathways to modulate the polarization of decidual macrophages

Programmed cell death-1 (PD-1) and T-cell immunoglobulin mucin-3 (Tim-3) are important immune checkpoint receptors that prevent an overreacted maternal immune response to fetal antigens during pregnancy. Disruption of complex immune regulation mechanisms is associated with adverse pregnancy outcomes, including preeclampsia (PE). Our recent study showed that the Tim-3 pathway was involved in the regulation of decidual macrophage polarization. Decidual macrophages polarized to the M1 phenotype may impair uterine vessel remodeling during placentation, accounting for the occurrence of PE. Co-blockade of the PD-1/Tim-3 pathway was shown to successfully control tumor growth in preclinical cancer models. However, the effects of activating both PD-1 and Tim-3 pathways as a combined intervention strategy in PE are never reported. Herein, we observed the skew of decidual macrophage polarization toward the M1 phenotype in patients with PE and lipopolysaccharide (LPS)-induced PE-like rat model. Moreover, we found that the activation of PD-1/Tim-3 pathway by using PD-L1 and Gal-9 fusion proteins could alleviate the manifestation of the LPS-induced PE-like rats and protect their offspring. Compared with the single intervention, the combination of PD-L1and Gal-9 fusion proteins exhibited obvious advantages in the relief of PE-like symptoms, trophoblast invasion, and fetal vascular development, indicating a synergistic effect of the activated PD-1/Tim-3 pathway. The in vitro study also revealed that the combined intervention using PD-L1 and Gal-9 fusion proteins inhibited the LPS-induced M1 macrophage polarization via the synergic activation of the ERK/GSK3β/β-catenin signaling pathway. Together, our findings provide the first evidence that simultaneous activation of PD-1/Tim-3 signaling pathways may have an optimal protective effect and serve as a new potential target for PE intervention.

Mesenchymal stem cells alter the frequency and cytokine profile of natural killer cells in abortion-prone mice

Natural killer cells, which play a pivotal role in the establishment and maintenance of normal pregnancy, are the most abundant leukocytes at the fetomaternal interface that their subsets frequencies and cytokine profile are influential factors in the preservation of the decidual tolerogenic microenvironment. Any imbalance in NK cells' frequency and functions could be associated with pregnancy failure. Mesenchymal stem cells (MSCs) are shown to have immunomodulatory effects on NK cells and their cytokine profile. The purpose of this study is to evaluate the impact of MSCs therapy on the cytokine profiles and subpopulations of NK cells in a murine model of recurrent pregnancy loss. Adipose-derived MSCs were injected intraperitoneally to the abortion-prone mice on Day 4.5 of gestation. The abortion rate was determined after MSCs administration and the frequency and cytokine profiles of the different subsets of NK cells were determined using the flow cytometry. Our results showed that, in abortion-prone mice, the frequency of CD49b⁺ NK cells was significantly higher than normal pregnant mice that decreased after therapy. We also demonstrated that MSCs downregulated the production of IFN-γ and upregulated IL-4 and IL-10 production by uNK cells. These findings indicate that MSCs can decrease the infiltration of CD49b⁺ NK cells to the fetomaternal interface and modulate the cytokine profile of NK cells from inflammatory to tolerogenic profile and thereby improve the tolerogenic microenvironment at the fetomaternal interface in benefit of pregnancy maintenance.

Gestational Perfluorooctanoic Acid Exposure Inhibits Placental Development by Dysregulation of Labyrinth Vessels and uNK Cells and Apoptosis in Mice

Perfluorooctanoic acid (PFOA) is a widely used perfluorinated compound and known to cause developmental toxicity which includes the increase of resorbed embryo, decrease of fetal survival, and fetal growth retardation. Nevertheless, whether it is associated with alteration of placental development remains unknown. Pregnant mice were gavaged with 0, 2.5, 5, 10 mg PFOA /kg/day from pregnancy day (PD) 1 to PD 13. Results showed that PFOA exposure markedly decreased the placental weight and caused interstitial edema of placenta. Laminin staining indicated that blood sinusoids area was shrunken in placenta of PFOA-exposed mice. Furthermore, PFOA treatment significantly reduced numbers of uNK cells. Western blot analysis revealed that levels of Bax and cleaved-caspase 3 proteins were markedly up-regulated in PFOA-treated groups. In addition, TEM examination showed that PFOA treatment caused rupture of nuclear membrane and nuclear pyknosis and fragmentation. Thus, our results suggested that gestational PFOA exposure significantly inhibited development of early placenta through shrinkage of labyrinth vessels and downregulation of uNK cells and apoptosis induction, which may result in adverse gestational outcomes.

Immune Checkpoint Molecules in Reproductive Immunology

Immune checkpoint molecules, like CTLA-4, TIM-3, PD-1, are negative regulators of immune responses to avoid immune injury. Checkpoint regulators are thought to actively participate in the immune defense of infections, prevention of autoimmunity, transplantation, and tumor immune evasion. Maternal-fetal immunotolerance represents a real immunological challenge for the immune system of the mother: beside acceptance of the semiallogeneic fetus, the maternal immune system has to be prepared for immune defense mostly against infections. In this particular situation, the role of immune checkpoint molecules could be of special interest. In this review, we describe current knowledge on the role of immune checkpoint molecules in reproductive immunology.

Galectin-9 Alleviates LPS-Induced Preeclampsia-Like Impairment in Rats via Switching Decidual Macrophage Polarization to M2 Subtype

Dysfunction of decidual macrophages (DMs) is considered a critical event in the pathogenesis of pre-eclampsia (PE). T cell immunoglobulin mucin 3 (Tim-3) is an important negative regulatory molecule that induces immune tolerance by interacting with its ligand Galectin-9 (Gal-9) and thus modulating function of various immune cells, including macrophages. However, the regulatory effects of Tim-3/Gal-9 signaling on DMs polarization and its role in PE remain unclear. In this study, we established a PE-like rat model by administering 1.0 μg/kg lipopolysaccharide (LPS) to normal pregnant Sprague-Dawley rats via the tail vein at embryonic day 5 (E5). Apart from the pre-eclamptic manifestations, increased M1 subtype and decreased M2 subtype were observed at the maternal-fetal interface, as well as increased pro-inflammatory cytokines (TNF-α and IL-1β) and reduced anti-inflammatory cytokines (TGF-β and IL-10). Moreover, the expression of Tim-3 in DMs and that of Gal-9 at the maternal-fetal interface were reduced. After administration of recombinant Galectin-9 (rGal-9) protein, we found that liver and renal injuries and maternofetal placental functional deficiency, including inadequate trophoblast cells invasion, impaired spiral artery remodeling and fetal capillary development, were reversed. In addition, the polarization of DMs was inclined to M2 subtype, which was similar to the polarization of DMs in the control rats but contrary to the PE-like rats. Interestingly, at E9, the expression of Tim-3 in DMs and that of Gal-9 at the maternal-fetal interface were significantly increased in the rGal-9 protein intervention group. Taken together, our findings show that administration of rGal-9 protein can alleviate the PE-like rat manifestations induced by LPS. This finding may be related to the activation of the Tim-3/Gal-9 signaling pathway, which promotes DMs polarization dominantly shifting to M2 subtype. Moreover, upregulation of Tim-3 in DMs and Gal-9 at the maternal-fetal interface at E9 suggests that Tim-3/Gal-9 pathway may play some important roles in early pregnancy and even embryo development.

Biomarkers in Fetomaternal Tolerance

Multiple mechanisms of tolerance operate in the immune cross-talk at the fetomaternal interface, contributing to successful pregnancy outcome. The cross-talk includes interaction between various cell subsets and between cytokines and molecules of the endocrine system. A depiction of how all these components interact with each other and contribute to tolerance of the fetus is not clearly understood. Dysregulation in one or more of these mechanisms leads to fetal loss. Few effective biomarkers are available that can safely predict fetal loss. This review discusses some potential biomarkers that can predict failure of tolerance at the fetomaternal interface.

miR-330-5p/Tim-3 axis regulates macrophage M2 polarization and insulin resistance in diabetes mice

Obesity is associated with a state of low-grade inflammatory response in adipose tissue, and contributes to the development of type 2 diabetes. Immune cells such as macrophages can infiltrate adipose tissue and are responsible for the majority of inflammatory cytokine production. Therefore, adipose tissue promotes macrophage infiltration, resulting in local inflammation and insulin resistance. Tim-3 negatively regulates IFN-γ secretion and influences the ability to induce T cell tolerance in diabetes. MicroRNA contributes to the development of immunological tolerance and involves in macrophage polarization. However, the potential of Tim-3 to regulate macrophage polarization and the related microRNA has not been reported. In this experiment, 8-week-old C57BL/6 mice were fed a high-fat diet for 8 weeks. The adipose tissue macrophages were isolated, miR-330-5p and Tim-3 levels, and M1/M2 polarization were analyzed. In addition, insulin tolerance tests was detected. The results demonstrated that miR-330-5p levels increased but Tim-3 levels decreased, leading to M1 polarization and insulin tolerance in diabetes mice. In addition, inhibition of miR-330-5p enhanced Tim-3 levels, leading to M2 polarization and insulin tolerance attenuation in diabetes mice. Furthermore, we detected the inverse relationship between miR-330-5p and Tim-3. We found that Tim-3 mRNA contained conserved miR-330-5p binding sites in its 3'UTR, and miR-330-5p could directly regulate Tim-3 expression through these 3'UTR sites. Our study demonstrated that miR-330-5p served as a regulator of the M2 polarization and miR-330-5p/Tim-3 axis potentially down-regulated insulin resistance in diabetes, probably through enhancing the M2 polarization of macrophage.

Upregulation of Tim-3 expression at feto-maternal interface may explain embryo survival in the CBAxDBA/2 model of abortion

PROBLEM

To understand the mechanisms of action of Tim-3 at the maternal-fetal interface and explore how Tim-3 might be involved in the pathogenesis of abortion by constructing an in vitro trophoblast-lymphocyte system.

METHODS OF STUDY

Female CBA/J × male DBA/2 matings were used as the abortion-prone model and CBA/J × male BALB/c matings as control. The expression of Tim-3 at the maternal-fetal interface and in the peripheral blood lymphocytes was measured by immunohistochemistry and Western blotting. The proliferation index of lymphocytes and levels of Th1/Th2-derived cytokines in peripheral blood and in the co-culture system were determined using CCK-8 assay and ELISA, respectively.

RESULTS

The expression level of Tim-3 was higher in abortion-prone matings than that of control (P < .05). A preponderance of Th1 was observed in the co-culture system in the abortion-prone mating group. Recombinant Tim-3 Ig reversed the imbalance of Th1/Th2 immunity of abortion-prone matings by suppressing the secretion of IFN-γ and IL-2 but had no direct effect on the generation of IL-4.

CONCLUSION

Tim-3 might contribute to successful pregnancy by restraining Th1 bias, and the maternal immune system might develop a strategy including upregulation of Tim-3 at the maternal-fetal interface and in peripheral blood so as to maintain moderate inflammatory responses against miscarriage.

TIM-3 as a Target for Cancer Immunotherapy and Mechanisms of Action

Cancer immunotherapy has produced impressive clinical results in recent years. Despite the success of the checkpoint blockade strategies targeting cytotoxic T lymphocyte antigen 4 (CTLA-4) and programmed death receptor 1 (PD-1), a large portion of cancer patients have not yet benefited from this novel therapy. T cell immunoglobulin and mucin domain 3 (TIM-3) has been shown to mediate immune tolerance in mouse models of infectious diseases, alloimmunity, autoimmunity, and tumor Immunity. Thus, targeting TIM-3 emerges as a promising approach for further improvement of current immunotherapy. Despite a large amount of experimental data showing an immune suppressive function of TIM-3 in vivo, the exact mechanisms are not well understood. To enable effective targeting of TIM-3 for tumor immunotherapy, further in-depth mechanistic studies are warranted. These studies will also provide much-needed insight for the rational design of novel combination therapy with other checkpoint blockers. In this review, we summarize key evidence supporting an immune regulatory role of TIM-3 and discuss possible mechanisms of action.

Tim-3: Expression on immune cells and roles at the maternal-fetal interface

Successful pregnancy relies on the accurate regulation of the maternal-fetal immune system. Without enough tolerance in the uterine microenvironment, the mother and the hemiallogeneic fetus could not peacefully coexist. T cell immunoglobulin and mucin domain (Tim)-3 is a molecule originally regarded as to be expressed on terminally differentiated IFN-γ expressing CD4⁺ T cells (Th1). The engagement of Tim-3 with its ligand, galectin-9 (Gal-9) could induce the exhaustion or apoptosis of effector T cells, and thus might regulate the tolerance. Tim-3 pathway also participates in regulating the activities of CD4⁺ regulatory T cells, monocyte-macrophages, dendritic cells and natural killer cells. Dysregulation of Tim-3 expression can elicit excessive or inhibited inflammatory responses and ultimately result in autoimmune diseases, viral or tumor evasion and pregnancy complications. In this review, we will mainly focus on the expression of Tim-3 on local immune cells and its function in pregnancy. In addition, meaningful questions that need further investigation and the potential roles of Tim-3 in fetal tolerance will be discussed. Deeper understanding of the immune checkpoint receptor Tim-3 will shed new light on exploring the pathogenesis of some pregnancy complications, including pre-eclampsia, intrauterine growth restriction, recurrent spontaneous abortion and preterm birth. Tim-3 pathway might be a new target of immune therapy for pregnancy complications in the future.

Endogenous TWEAK is critical for regulating the function of mouse uterine natural killer cells in an immunological model of pregnancy loss

Uterine natural killer (uNK) cells are the most abundant lymphocyte population in the feto-maternal interface during early gestation, and uNK cells play a significant role in the establishment and maintenance of pregnancy-related vascularization, as well as in tolerance to the fetus. Tumour necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor, fibroblast growth factor-inducible molecule (Fn14), are involved in preventing local cytotoxicity and counterbalancing the cytotoxic function of uNK cells. Here, we studied the regulation of TWEAK/Fn14-mediated innate immunity in the uterus using a lipopolysaccharide (LPS)-induced model of abortion in pregnant mice. Specifically, we detected the expression of TWEAK and Fn14 in the uterus and in uNK cells following LPS treatment. Our results revealed that TWEAK and Fn14 are expressed by uNK cells in pregnant mice; in particular, it appears that the cytokine TWEAK is primarily derived from uNK cells. Interestingly, the down-regulation of TWEAK in uNK cells and the up-regulation of the Fn14 receptor in the uterus in LPS-treated mice may contribute to the disruption of decidual homeostasis by altering uNK cell cytotoxicity - ultimately leading to fetal rejection. In conclusion, the present study strongly suggests that the TWEAK-Fn14 axis in uNK cells is involved in maintaining the tolerance necessary for successful pregnancy.