Human chorionic gonadotropin regulates cytokine production by lymphocytes from patients with multiple sclerosis.

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) that primarily affects young adults, predominantly females. This was partially attributed to sex differences in immunity, which are influenced by changes in sex hormones occurring during women's life, among other factors. Furthermore, MS patients experience significant improvement in their symptoms during pregnancy when levels of female sex-hormones significantly increase. This phenomenon was attributed to immune adaptations occurring during gestation which are regulated by paternal antigens and sex hormones. The human chorionic gonadotropin (hCG) was shown to have strong immunosuppressive abilities. We aimed to analyze here the capacity of the hCG to regulate pro- and anti-inflammatory cytokine production by PBMC from MS patients. PBMC isolated from 17 MS patients receiving IFNß1a treatment were cultured with or without recombinant or urinary hCG. Cytokine production in the supernatants was assessed using a CBA array and cytokine production by lymphocytes and expression of co-stimulatory molecules in B-lymphocytes were evaluated by flow cytometry. hCG reduced the production of TNF by PBMC from MS patients while lowering the percentages of TNF producing T cells and diminishing the production of TNF by B cells. hCG significantly boosted the production of IL-10 by regulatory T cells and CD19high B cells from MS patients. Furthermore, hCG treatment lowered the percentages of CD80+CD86+ expressing B cells within PBMC from MS patients. Overall, our results described a novel and not yet explored mechanisms of action of hCG in the context of MS.

Lupus and recurrent pregnancy loss: the role of female sex hormones and B cells.

Systemic lupus erythematosus is a debilitating autoimmune disease characterized by uncontrolled activation of adaptive immunity, particularly B cells, which predominantly affects women in a 9 to 1 ratio compared to men. This stark sex disparity strongly suggests a role for female sex hormones in the disease's onset and progression. Indeed, it is widely recognized that estradiol not only enhances the survival of autoreactive B cells but also stimulates the production of autoantibodies associated with systemic lupus erythematosus, such as anti-nuclear antibodies and anti-dsDNA antibodies. Clinical manifestations of systemic lupus erythematosus typically emerge after puberty and persist throughout reproductive life. Furthermore, symptoms often exacerbate during the premenstrual period and pregnancy, as increased levels of estradiol can contribute to disease flares. Despite being fertile, women with lupus face a heightened risk of pregnancy-related complications, including pregnancy loss and stillbirth, which significantly surpass the rates observed in the healthy population. Therefore, this review aims to summarize and discuss the existing literature on the influence of female sex hormones on B-cell activation in patients with systemic lupus erythematosus, with a particular emphasis on their impact on pregnancy loss.

Splenic B1 B Cells Acquire a Proliferative and Anti-Inflamatory Profile During Pregnancy in Mice.

B cells are a heterogeneous cell population with differential ontogeny, anatomical location, and functions. B1 B cells are a distinct subpopulation characterized by their unique capacity of self-renewal, the production of large quantities of IL-10, and the ability to secrete protective, anti-inflammatory natural antibodies (NAbs), presumably upon down-regulation of CD1d expression. Although natural antibodies are thought to be protective, due to their polyreactivity, their participation in certain autoimmune diseases has been suggested. In the context of pregnancy, the role of B1 B cells has been discussed controversially. While in human pregnancies B1 B cells and natural/polyreactive antibodies they produce are involved in the development of preeclampsia, in mice they promote healthy gestation and fetal protection. In this work, we aimed to functionally characterize the splenic B1 B cell population during pregnancy in mice. Functional enrichment analysis using only up-regulated transcripts from a transcriptomic profile performed on total splenic B cells from pregnant compared to non-pregnant mice showed augmented cell cycle and DNA replication pathways. Proliferation studies by flow cytometry showed augmented Ki-67 proliferation marker expression and percentages of B1 B cells. Furthermore, B1 B cells produced higher levels of IL-10 and lower levels of TNF-α leading to an increased IL-10/TNF-α ratio and showing an immunoregulatory phenotype. Finally, we observed lower expression of CD1d on B1 B cells, suggesting a higher capacity to produce NAbs in the context of pregnancy. In summary, our results showed not only an expanded and proliferative splenic B1 B cell population during pregnancy but also the acquisition of immunomodulatory capacities suggesting its critical role in the intricate process of pregnancy tolerance.

An overview of the role of probiotics in pregnancy-associated pathologies with a special focus on preterm birth.

Probiotics can modulate the host immune system and keep a healthy microbiota thus enhancing the integrity of the mucosal epithelium. They were proven to be useful as therapeutic strategies for a variety of inflammatory diseases. Preterm birth is a multicausal complication where the early inflammatory cascade activation affects both the mother and the fetus and may have an irreversibly impact on infant development. Prevention of preterm birth is a challenge that calls for different strategies targeting its diverse etiologies. For the past decade, novel and numerous studies investigated the role of probiotics for the prevention of preterm birth given their above-mentioned abilities. This allows a wider approach to the multifactorial causes of preterm birth. In this sense, probiotic administration was shown to be inversely related to the rate of preterm birth. In this review, we discuss the latest reports involving probiotics and preterm birth, and the chances of probiotics becoming a therapeutic strategy for the prevention of pregnancy-associated pathologies like preterm birth shortly.

B cells acquire a unique and differential transcriptomic profile during pregnancy.

Pregnancy alters B cell development and function. B cell activation is initiated by antigens binding to the BCR leading to B cell survival, proliferation, antigen presentation and antibody production. We performed a genome-wide transcriptome profiling of splenic B cells from pregnant (P) and non-pregnant (NP) mice and identified 1136 genes exhibiting differential expression in B cells from P mice (625 up- and 511 down-regulated) compared to NP animals. In silico analysis showed that B cell activation through BCR seems to be lowered during pregnancy. RT-qPCR analysis confirmed these data. Additionally, B cells from pregnant women stimulated in vitro through BCR produced lower levels of inflammatory cytokines compared to non-pregnant women. Our results suggest that B cells acquire a state of hypo-responsiveness during gestation, probably as part of the maternal immune strategy for fetal tolerance but also open new avenues to understand why pregnant women are at highest risk for infections.

Probiotic Lactobacillus kefiri prevents endotoxin-induced preterm birth and stillbirth in mice.

Preterm birth (PTB), defined as birth occurring before 37 weeks of pregnancy, affects 5-18% of pregnancies and is the leading cause of neonatal morbidity and mortality worldwide. Although PTB is considered a syndrome, infection-induced inflammation accounts for up to 50% of all cases. Despite the effort to reduce the incidence of PTB, it continues to rise worldwide and current approaches for preventing or treating PTB are largely unsatisfactory. Probiotics are live microorganisms which, when administered in adequate amounts, confer a health benefit on the host. It is well known that probiotics can modulate the host immune system exerting a potent anti-inflammatory activity. The main aim of this work was to evaluate the capacity of the probiotic Lactobacillus kefiri (Lk48) to prevent preterm birth in mice. C57BL/6 female mice were treated with Lk48 or vehicle a week before and during pregnancy and were challenged with LPS (10 µg), a dose known to induce PTB on gestational day 16. Percentages of PTB as well as stillbirth were evaluated. We observed that oral administration of Lk48 significantly reduced the occurrence of LPS-induced PTB and stillbirth as well as improved post-natal development. This protective effect was associated with a reduction in leucocyte infiltration and reduced inflammation-induced damage in reproductive tissue. Besides, Lk48 treatment also modulated the diversity of vaginal microbiota. Our results demonstrated that prophylactic consumption of probiotic L. kefiri prevented LPS-induced PTB and still birth in mice and opens new avenues for exploring novel and promising strategies for preventing PTB in humans.

Expression of IL-33 Receptor Is Significantly Up-Regulated in B Cells During Pregnancy and in the Acute Phase of Preterm Birth in Mice.

Interleukin-33 (IL-33) is a mucosal alarmin belonging to the IL-1 cytokine family and is now recognized to have a key role in innate and adaptive immunity, contributing to tissue homeostasis and response to environmental stresses. In addition, IL-33 has also been shown to work as a positive regulator that initiates and maintains a Th2 immune response. In the context of pregnancy, it has been recently demonstrated that upon certain stress conditions, such as an infection induced inflammation, IL-33 is released from the uterine mucosa and triggers decidual B cells to produce anti-inflammatory molecules, which in turn restore immune homeostasis and prevents the development of preterm birth. In this study we therefore performed a detailed characterization of IL-33 receptor (Il1rl1 or ST2) expression in B cells during normal pregnancy, as well as in a mouse model of preterm birth. We observed that splenic B cells significantly up-regulate the expression of Il1rl1 during pregnancy and identified the B1 B cell population as the main ST2-expressing B cell subset. A further kinetic analysis showed that percentages of ST2-expressing B1 B cells are significantly augmented on days 12 and 14 of pregnancy, both in the spleen and peritoneal cavity of pregnant mice, and then drop toward the end of pregnancy to the levels observed in non-pregnant animals. Furthermore, using a mouse model of LPS-induced preterm birth, we demonstrated that not only are the percentages of ST2-expressing B1 B cells significantly enlarged in the spleen during the acute phase of preterm birth, but decidual B cells also significantly up-regulate ST2 expression as compared to term-pregnant mice. Overall, our results suggest a functional role of ST2 expression in B cells during pregnancy and reinforce the importance of the IL-33/ST2 axis in B cells as a critical mechanism to control inflammation-induced preterm birth.

Characterization of murine amniotic fluid B cells in normal pregnancy and in preterm birth.

The amniotic fluid provides mechanical protection and immune defense against pathogens to the fetus. Indeed, components of the innate and adaptive immunity, including B cells, have been described in the amniotic fluid. However, limited information concerning phenotype and functionality of amniotic fluid B cells is available. Hence, we aimed to perform a full phenotypical and functional characterization of amniotic fluid B cells in normal pregnancy and in a mouse model of preterm birth. Phenotypic analysis depicted the presence of two populations of amniotic fluid B cells: an immature population, resembling B1 progenitor cells and a more mature population. Further isolation and in vitro co-culture with a bone marrow stroma cell line demonstrated the capacity of the immature B cells to mature. This was further supported by spontaneous production of IgM, a feature of the B1 B cell sub-population. An additional in vitro stimulation with lipopolysaccharide induced the activation of amniotic fluid B cells as well as the production of pro and anti-inflammatory cytokines. Furthermore, amniotic fluid B cells were expanded in the acute phase of LPS-induced preterm birth. Overall our data add new insight not only on the phenotype and developmental stage of the amniotic fluid B1 B cells but especially on their functionality. This provides important information for a better understanding of their role within the amniotic fluid as immunological protective barrier, especially with regard to intraamniotic infection and preterm birth.