The changes of circulating lymphocyte sub-populations in women with preterm labour: a case-controlled study

Immunological Changes in Pregnancy and Its Relation to COVID-19 Infection

This chapter describes the immunological adaptation to pregnancy. A special focus is drawn on the susceptibility to viral infections, especially COVID-19. Older literature refers to the pregnancy as an immunosuppressive state, while recent studies show an immunomodulation to adapt to the growing semiallograftic fetus. Despite this, pregnant women are not susceptible to all viral infections. Regarding influenza, pregnant women are not more susceptible to the infection, but more severe maternal courses. To prevent this, influenza vaccination is recommended for pregnant women. Based on the available evidence, pregnant patients are also not more susceptible to infection with regard to COVID-19 infection. Yet, more severe courses are described throughout gestation with the onset of obstetrical complications.

Regulatory B Cells Are Decreased and Impaired in Their Function in Peripheral Maternal Blood in Pre-term Birth

Preterm birth (PTB) is defined as birth before 37 completed weeks of gestation. The causes of PTB are multiple and complex, the underlying pathophysiology being largely unknown. Interferences in the fine-tuned balance of the maternal immune system have been pointed to as one possible cause of PTB. Regulatory B cells (Breg) are part of the adaptive immune response, and recent data suggest that they may contribute to a healthy pregnancy by their regulatory/suppressive function. We investigated the frequency of Breg cells in peripheral blood of women undergoing PTB and control women immediately before giving birth via cesarean section. We detected an enhanced number of B cells, but a reduced number of Breg cells in women delivering preterm. In addition, the percentage of IL-10-producing B cells was decreased in PTB following stimulation with TLR agonists CpG or LPS, alone or combined with CD40L. This was associated with increased levels of pro-inflammatory cytokines in maternal serum. Moreover, isolated maternal B cells before delivering premature babies secreted higher level of the pro-inflammatory cytokine IL-6. No alterations in the frequency of regulatory T cells were found. Our data indicate that alterations in the number and function of Breg cells in peripheral maternal blood contribute to the immunological changes observed in preterm delivery and suggest these cells as important regulators of maternal immune responses.

Are naïve T cells and class-switched memory (IgD- CD27+) B cells not essential for establishment and maintenance of pregnancy? Insights from a case of common variable immunodeficiency with pregnancy

The disruption of adaptive immune response has adverse effects on the establishment and maintenance of pregnancy. The adaptive immune system is regulated by several types of immune cells. However, there is limited information about cell hierarchy in the adaptive immune response to the establishment and maintenance of pregnancy in women. The assessment of the outcome of pregnancy in primary immunodeficiency diseases could help in understanding the cell hierarchy in the adaptive immune system during pregnancy. Common variable immunodeficiency (CVID) is a heterogeneous adaptive immune system disorder characterized by primary hypogammaglobulinemia. A few studies have previously reported the assessment of the T and B cell subpopulations in CVID patients. However, an assessment of the subpopulations of T and B cells and the outcome of pregnancy in women with CVID has not been reported till date. Most CVID patients show a general decrease in the expression of CD27 in B cells. The assessment of pregnancy and the subpopulations of T and B cells in CVID women with severe reduction in the naïve T and switched B cells could help understand whether these cells are essential for the establishment and maintenance of pregnancy in women.

Maternal Serum B-Cell Activating Factor Levels

Hypertensive disorders of pregnancy are a leading cause of maternal and perinatal morbidity and mortality. Early suppression of B-cell lymphopoiesis is necessary for a normal pregnancy. Dysregulation of factors critical to B-cell survival may result in pregnancy complications, including hypertension. In this prospective observational study at a single medical center, serum levels of BAFF (B-cell activating factor) were measured in pregnant participants at each trimester, at delivery, and postpartum and in nonpregnant controls at a single time point. Comparisons were made between nonpregnant and pregnant subjects and between time periods of pregnancy. First-trimester serum BAFF levels were further tested for association with hypertensive disorders of pregnancy. The study included 149 healthy pregnant women, 25 pregnant women with chronic hypertension, and 48 nonpregnant controls. Median first-trimester serum BAFF level (ng/mL) for healthy women (0.90) was lower than median serum BAFF levels for women with chronic hypertension (0.96; P =0.013) and controls (1.00; P =0.002). Serum BAFF levels steadily declined throughout pregnancy, with the median second-trimester level lower than the corresponding first-trimester level (0.77; P =0.003) and the median third-trimester level lower than the corresponding second-trimester level (0.72; P =0.025). The median first-trimester serum BAFF level was elevated in women who subsequently developed hypertension compared with women who remained normotensive (1.02 versus 0.85; P =0.012), with the area under the receiver operating characteristic curve being 0.709. First-trimester serum BAFF level may be an early and clinically useful predictor of hypertensive disorders of pregnancy.

To B or not to B cells-mediate a healthy start to life

Maternal immune responses during pregnancy are critical in programming the future health of a newborn. The maternal immune system is required to accommodate fetal immune tolerance as well as to provide a protective defence against infections for the immunocompromised mother and her baby during gestation and lactation. Natural immunity and antibody production by maternal B cells play a significant role in providing such immunoprotection. However, aberrations in the B cell compartment as a consequence of maternal autoimmunity can pose serious risks to both the mother and her baby. Despite their potential implication in shaping pregnancy outcomes, the role of B cells in human pregnancy has been poorly studied. This review focuses on the role of B cells and the implications of B cell depletion therapy in pregnancy. It highlights the evidence of an association between aberrant B cell compartment and obstetric conditions. It also alludes to the potential mechanisms that amplify these B cell aberrances and thereby contribute to exacerbation of some maternal autoimmune conditions and poor neonatal outcomes. Clinical and experimental evidence suggests strongly that maternal autoantibodies contribute directly to the pathologies of obstetric and neonatal conditions that have significant implications for the lifelong health of a newborn. The evidence for clinical benefit and safety of B cell depletion therapies in pregnancy is reviewed, and an argument is mounted for further clinical evaluation of B cell-targeted therapies in high-risk pregnancy, with an emphasis on improving neonatal outcomes and prevention of neonatal conditions such as congenital heart block and fetal/neonatal alloimmune thrombocytopenia.

Over-expression of the thrombin receptor (PAR-1) in the placenta in preeclampsia: a mechanism for the intersection of coagulation and inflammation

OBJECTIVE

Preeclampsia (PE) is characterized by excessive thrombin generation, which has been implicated in the multiple organ damage associated with the disease. The biological effects of thrombin on coagulation and inflammation are mediated by protease-activated receptor-1 (PAR-1), a G protein-coupled receptor. The aim of this study was to determine whether preterm PE is associated with changes in placental expression of PAR-1.

STUDY DESIGN

This cross-sectional study included two groups matched for gestational age at delivery: (1) patients with preterm PE (<37 weeks of gestation; n = 26) and (2) a control group of patients with preterm labor without intra-amniotic infection (n = 26). Placental tissue microarrays were immunostained for PAR-1. Immunoreactivity of PAR-1 in the villous trophoblasts was graded as negative, weak-positive, or strong-positive.

RESULTS

(1) The proportion of cases with strong PAR-1 immunoreactivity was significantly higher in placentas of patients with PE than in placentas from the control group (37.5% (9/24) vs. 8.7% (2/23); p = 0.036, respectively). (2) PAR-1 immunoreactivity was found in the cellular compartments of the placental villous tree, mainly in villous trophoblasts and stromal endothelial cells. (3) PAR-1 was detected in 92.3% (24/26) of the placentas of women with PE and in 88.5% (23/26) of the placentas from the control group.

CONCLUSION

Placentas from pregnancies complicated by preterm PE had a significantly higher frequency of strong PAR-1 expression than placentas from women with spontaneous preterm labor. This observation is consistent with a role for PAR-1 as a mediator of the effect of thrombin on coagulation and inflammation in PE. We propose that the effects of thrombin in PE are due to increased thrombin generation and higher expression of PAR-1, the major receptor for this enzyme.

Decreased serum level of macrophage inflammatory chemokine-3β/CCL19 in preterm labor and delivery

OBJECTIVE

Chemokines are small soluble molecules which mediate leukocyte migration and may be involved in the pathophysiology of preterm labor. We aimed to determine if serum concentrations of selected chemokines are changed in preterm labor and delivery.

STUDY DESIGN

A novel array-based enzyme-linked immunosorbent assay was used to quantitate serum levels of nine chemokines from a single sample: MDC/CCL22, TARC/CCL17, ITAC/CXCL11, I-309/CCL1, IP-10/CXCL10, MIP-1alpha/CCL3, -1beta/CCL4, -3alpha/CCL20 and -3beta/CCL19. Women in preterm labor who delivered (n = 17), women at preterm pregnancy not in labor (n = 13) and women in labor at term (n = 8) participated.

RESULTS

In the preterm delivery group of patients, the MIP-3beta/CCL19 concentration was in mean (+/-S.D.) 70.4+/-31.7 pg/mL, which was significantly lower than that in preterm gravidas not in labor of 123+/-34 pg/mL (p < 0.001) and those in labor at term of 118+/-25.6 pg/mL (p < 0.01). The other measured chemokines did not differ significantly.

CONCLUSIONS

Of a small number of examined chemokines, we were able to show that one of them, MIP-3beta/CCL19 was significantly lower in women with preterm labor and delivery. Whether or not this chemokine has a potential as biochemical marker of preterm delivery remains to be determined.