Immunology of Uterine and Vaginal Mucosae: (Trends in Immunology 39, 302-314, 2018)

Validation of vaginal microbiome proxies for in vitro experiments that biomimic Lactobacillus-dominant vaginal cultures

The vaginal microbiome includes diverse microbiota dominated by Lactobacillus [L.] spp. that protect against infections, modulate inflammation, and regulate vaginal homeostasis. Because it is challenging to incorporate vaginal microbiota into in vitro models, including organ-on-a-chip systems, we assessed microbial metabolites as reliable proxies in addition to traditional vaginal epithelial cultures (VECs). Human immortalized VECs cultured on transwells with an air-liquid interface generated stratified cell layers colonized by transplanted healthy microbiomes (L. jensenii- or L. crispatus-dominant) or a community representing bacterial vaginosis (BV). After 48-h, a qPCR array confirmed the expected donor community profiles. Pooled apical and basal supernatants were subjected to metabolomic analysis (untargeted mass spectrometry) followed by ingenuity pathways analysis (IPA). To determine the bacterial metabolites' ability to recreate the vaginal microenvironment in vitro, pooled bacteria-free metabolites were added to traditional VEC cultures. Cell morphology, viability, and cytokine production were assessed. IPA analysis of metabolites from colonized samples contained fatty acids, nucleic acids, and sugar acids that were associated with signaling networks that contribute to secondary metabolism, anti-fungal, and anti-inflammatory functions indicative of a healthy vaginal microbiome compared to sterile VEC transwell metabolites. Pooled metabolites did not affect cell morphology or induce cell death (∼5.5%) of VEC cultures (n = 3) after 72-h. However, metabolites created an anti-inflammatory milieu by increasing IL-10 production (p = .06, T-test) and significantly suppressing pro-inflammatory IL-6 (p = .0001), IL-8 (p = .009), and TNFα (p = .0007) compared to naïve VEC cultures. BV VEC conditioned-medium did not affect cell morphology nor viability; however, it induced a pro-inflammatory environment by elevating levels of IL-6 (p = .023), IL-8 (p = .031), and TNFα (p = .021) when compared to L.-dominate microbiome-conditioned medium. VEC transwells provide a suitable ex vivo system to support the production of bacterial metabolites consistent with the vaginal milieu allowing subsequent in vitro studies with enhanced accuracy and utility.

Immune activation of vaginal human Langerhans cells increases susceptibility to HIV-1 infection

Vaginal inflammation increases the risk for sexual HIV-1 transmission but underlying mechanisms remain unclear. In this study we assessed the impact of immune activation on HIV-1 susceptibility of primary human vaginal Langerhans cells (LCs). Vaginal LCs isolated from human vaginal tissue expressed a broad range of TLRs and became activated after exposure to both viral and bacterial TLR ligands. HIV-1 replication was restricted in immature vaginal LCs as only low levels of infection could be detected. Notably, activation of immature vaginal LCs by bacterial TLR ligands increased HIV-1 infection, whereas viral TLR ligands were unable to induce HIV-1 replication in vaginal LCs. Furthermore, mature vaginal LCs transmitted HIV-1 to CD4 T cells. This study emphasizes the role for vaginal LCs in protection against mucosal HIV-1 infection, which is abrogated upon activation. Moreover, our data suggest that bacterial STIs can increase the risk of HIV-1 acquisition in women.

Lactobacillus, glycans and drivers of health in the vaginal microbiome

A microbiome consists of microbes and their genomes, encompassing bacteria, viruses, fungi, protozoa, archaea, and eukaryotes. These elements interact dynamically in the specific environment in which they reside and evolve. In the past decade, studies of various microbiomes have been prevalent in the scientific literature, accounting for the shift from culture-dependent to culture-independent identification of microbes using new high-throughput sequencing technologies that decipher their composition and sometimes provide insights into their functions. Despite tremendous advances in understanding the gut microbiome, relatively little attention has been devoted to the vaginal environment, notably regarding the ubiquity and diversity of glycans which denote the significant role they play in the maintenance of homeostasis. Hopefully, emerging technologies will aid in the determination of what is a healthy vaginal microbiome, and provide insights into the roles of Lactobacillus, glycans and microbiome-related drivers of health and disease.

Microbial-driven preterm labour involves crosstalk between the innate and adaptive immune response

There has been a surge in studies implicating a role of vaginal microbiota in spontaneous preterm birth (sPTB), but most are associative without mechanistic insight. Here we show a comprehensive approach to understand the causative factors of preterm birth, based on the integration of longitudinal vaginal microbiota and cervicovaginal fluid (CVF) immunophenotype data collected from 133 women at high-risk of sPTB. We show that vaginal depletion of Lactobacillus species and high bacterial diversity leads to increased mannose binding lectin (MBL), IgM, IgG, C3b, C5, IL-8, IL-6 and IL-1β and to increased risk of sPTB. Cervical shortening, which often precedes preterm birth, is associated with Lactobacillus iners and elevated levels of IgM, C3b, C5, C5a and IL-6. These data demonstrate a role for the complement system in microbial-driven sPTB and provide a scientific rationale for the development of live biotherapeutics and complement therapeutics to prevent sPTB.

Gaining mechanistic insight into the microbiological and immunological factors that are associated with spontaneous preterm birth is important for the development of prevention strategies. Here authors show that the complement system in conjunction with specific vaginal microbial and associated immunological changes are contributing to this condition.

Building a stem cell-based primate uterus

The uterus is the organ for embryo implantation and fetal development. Most current models of the uterus are centred around capturing its function during later stages of pregnancy to increase the survival in pre-term births. However, in vitro models focusing on the uterine tissue itself would allow modelling of pathologies including endometriosis and uterine cancers, and open new avenues to investigate embryo implantation and human development. Motivated by these key questions, we discuss how stem cell-based uteri may be engineered from constituent cell parts, either as advanced self-organising cultures, or by controlled assembly through microfluidic and print-based technologies.

Superovulation with gonadotropin-releasing hormone agonist or chorionic gonadotropin for ovulation trigger differentially affects leukocyte populations in the peri-implantation mouse uterus

OBJECTIVE

To investigate the effect of superovulation with human chorionic gonadotropin (hCG) or gonadotropin-releasing hormone agonist (GnRHa) trigger on leukocyte density and expression of leukocyte-specific genes in the peri-implantation period in the mouse uterus.

DESIGN

Laboratory research.

SETTING

University laboratory facility.

INTERVENTIONS

Female mice were mated to fertile male mice in one of three protocols: (1) natural mating or mating following injection with pregnant mare serum gonadotropin followed by trigger with (2) GnRHa or (3) hCG. Female mice were killed prior to implantation, 3 days after ovulation (E3.5), and the ovaries and uterine tissue were collected. Total RNA was isolated and assayed using quantitative reverse transcription polymerase chain reaction, and the uterine tissue was stained for histologic analysis of immune cell markers.

MAIN OUTCOME MEASURES

Endometrial leukocyte (CD45) and vessel density (CD31) by immunohistochemical staining; expression of leukocyte markers CD11b, CD335, and CD22, by quantitative reverse transcription polymerase chain reaction in the whole uterine tissue.

RESULTS

Superovulation decreased (compared with controls) the endometrial leukocyte density, based on the number of cells staining for CD45, and endometrial vessel density, based on the number of cells staining for CD31. Leukocyte density was additionally decreased in the GnRHa trigger group compared with that in the hCG trigger group. Superovulation with hCG and GnRHa triggers decreased the uterine expression of the B-cell marker CD22 compared with controls. The expression of the natural killer cell marker CD11b was decreased by the hCG trigger but not by the GnRHa. Abundance of mRNA encoding the CD335 natural killer cell marker was not affected by superovulation or trigger agent.

CONCLUSIONS

In mice, superovulation with the GnRHa trigger compared with that with the hCG trigger differentially alters key immunologic factors in the uterine peri-implantation. These altered immunologic factors have roles in angiogenesis that may assist in elucidating the effects of assisted reproductive technologies on implantation efficiency and fetal growth and development.

Localized and Systemic Immune Response in Human Reproductive Tract

Sexually transmitted infections (STIs) are one of the significant causes of morbidity and mortality among adolescents and adults across the globe and encompass all the infections transmitted via person-to-person sexual contact. In spite of the widespread approach being used, STIs remain under-reported and many infections have taken an epidemic turn. The biggest roadblock in this is the unraveled basis of immunopathology of these infections, hindering the discovery of potential targets for immunization. Thereby, it is of utmost significance to decipher the hidden basis of these STIs to control the increasing epidemic of less commonly studied STIs. A complex interplay between innate immune defenses, with resident microbiota and mucosal immune response serves as the basis of therapeutic approaches, by targeting the vital steps of this dynamic interaction. The characterization of pathogen-specific antibodies to significant immunogenic molecules may divulge the conceivable protective effects.

Impacts of Cyclosporin A on clinical pregnancy outcomes of patients with a history of unexplained transfer failure: a retrospective cohort study

BACKGROUND

A rapid development in assisted reproductive technology (ART) has led to a surge in its popularity among target couples. However, elucidation on the molecular mechanism and effective solutions for a common problem posed by ART, namely transfer failure, is still lacking. The new therapeutic potential of cyclosporin A (CsA), a typical immunosuppressant widely used in the treatment of rejection after organ transplantation, in recurrent pregnancy loss (RPL) patients may inspire some novel transfer failure therapies in the future. To further explore the clinical effects of CsA, this study investigated whether its application can improve clinical pregnancy outcomes in patients with a history of unexplained transfer failure in frozen-thawed embryo transfer (FET) cycles.

METHODS

Data from a retrospective cohort investigation (178 frozen-thawed embryo transfer cycles in 178 patients) were analysed using binary logistic regression to explore the relationship between CsA treatment and clinical pregnancy outcomes; the odds ratios (ORs) and 95 % confidence intervals (CIs) were calculated as a measure of relevancy. Implantation rate was the main outcome measure.

RESULTS

There was no difference in the fine adjusted OR (95 % CI) of the implantation rate [1.251 (0.739-2.120)], clinical pregnancy rate [1.634 (0.772-3.458)], chemical pregnancy rate [1.402 (0.285-6.909)], take-home baby rate [0.872 (0.423-1.798)], multiple births rate [0.840 (0.197-3.590)], preterm birth [1.668 (0.377-7.373)], abnormal birth weight [1.834 (0.533-6.307)] or sex ratio [0.956 (0.339-2.698)] between the CsA-treated group and control group. No birth defects were observed in the present study.

CONCLUSIONS

Although CsA does not affect infant characteristics, it has no beneficial effects on the clinical pregnancy outcomes in patients with a history of unexplained transfer failure in FET cycles.

IL-7-Adjuvanted Vaginal Vaccine Elicits Strong Mucosal Immune Responses in Non-Human Primates

Mucosal immune responses are crucial in protecting against pathogens entering through mucosal surfaces. However, due to poor T-cell responsiveness upon mucosal antigenic stimulation, mucosal immunity remains difficult to obtain through vaccines and requires appropriate adjuvants. We previously demonstrated that administered systemically to healthy macaques or locally expressed in the intestinal mucosa of acutely SIV-infected macaques, interleukin-7 (IL-7) triggers chemokine expression and immune cell homing into mucosae, suggesting its important role in the development of mucosal immune responses. We therefore examined whether local delivery of recombinant glycosylated simian IL-7 (rs-IL-7gly) to the vaginal mucosa of rhesus macaques could prepare the lower female genital tract (FGT) for subsequent immunization and act as an efficient mucosal adjuvant. First, we showed that local administration of rs-IL-7gly triggers vaginal overexpression of chemokines and infiltration of mDCs, macrophages, NKs, B- and T-cells in the lamina propria while MamuLa-DR⁺ APCs accumulated in the epithelium. Subsequent mucosal anti-DT immunization in macaques resulted in a faster, stronger, and more persistent mucosal antibody response compared to DT-immunization alone. Indeed, we detected robust productions of DT-specific IgAs and IgGs in their vaginal secretions and identified cells secreting DT-specific IgAs in their vaginal mucosa and IgGs in draining lymph nodes. Finally, the expression of chemokines involved in the organization of tertiary lymphoid structures (TLS) was only increased in the vaginal mucosa of IL-7-adjuvanted immunized macaques. Interestingly, TLSs developed around PNAd⁺ high endothelial venules in their lower FGT sampled 2 weeks after the last immunization. Non-traumatic vaginal administration of rs-IL-7gly prepares the mucosa to respond to subsequent local immunization and allows the development of a strong mucosal immune response in macaques, through the chemokine-dependent recruitment of immune cells, the activation of mDCs and the formation of TLSs. The localization of DT-specific IgA⁺ plasma cells in the upper vaginal mucosa argues for their contribution to the production of specific immunoglobulins in the vaginal secretions. Our results highlight the potential of IL-7 as a potent mucosal adjuvant to stimulate the FGT immune system and elicit vaginal antibody responses to local immunization, which is the most promising way to confer protection against many sexually transmitted diseases.

Protective and Pathogenic Effects of Interferon Signaling During Pregnancy

Immune regulation at the maternal-fetal interface is complex due to conflicting immunological objectives: protection of the fetus from maternal pathogens and prevention of immune-mediated rejection of the semiallogeneic fetus and placenta. Interferon (IFN) signaling plays an important role in restricting congenital infections as well as in the physiology of healthy pregnancies. In this review, we discuss the antiviral and pathogenic effects of type I IFN (IFN-α, IFN-β), type II IFN (IFN-γ), and type III IFN (IFN-λ) during pregnancy, with an emphasis on mouse and non-human primate models of congenital Zika virus infection. In the context of these animal model systems, we examine the role of IFN signaling during healthy pregnancy. Finally, we review mechanisms by which dysregulated type I IFN responses contribute to poor pregnancy outcomes in humans with autoimmune disease, including interferonopathies and systemic lupus erythematosus.

Immunity in the Cervix: Interphase between Immune and Cervical Epithelial Cells

The cervix is divided into two morphologically and immunologically distinct regions, namely, (1) the microbe-laden ectocervix, which is proximal to the vagina, and (2) the "sterile" endocervix, which is distal to the uterus. The two cervical regions are bordered by the cervical transformation zone (CTZ), an area of changing cells, and are predominantly composed of cervical epithelial cells. Epithelial cells are known to play a crucial role in the initiation, maintenance, and regulation of innate and adaptive response in collaboration with immune cells in several tissue types, including the cervix, and their dysfunction can lead to a spectrum of clinical syndromes. For instance, epithelial cells block progression and neutralize or kill microorganisms through multiple ways. These (ways) include mounting physical (intercellular junctions, secretion of mucus) and immune barriers (pathogen-recognition receptor-mediated pathways), which collectively and ultimately lead to the release of specific chemokines and or cytokines. The cytokines subsequently recruit subsets of immune cells appropriate to a particular immune context and response, such as dendritic cells (DCs), T, B, and natural killer (NK) cells. The immune response, as most biological processes in the female reproductive tract (FRT), is mainly regulated by estrogen and progesterone and their (immune cells) responses vary during different physiological phases of reproduction, such as menstrual cycle, pregnancy, and post menopause. The purpose of the present review is to compare the immunological profile of the mucosae and immune cells in the ecto- and endocervix and their interphase during the different phases of female reproduction.