Increase of peripheral blood TCD8+ cells in women with recurrent miscarriage

Exploring the Immunological Aspects and Treatments of Recurrent Pregnancy Loss and Recurrent Implantation Failure

Recurrent pregnancy loss (RPL) is defined as the occurrence of two or more consecutive pregnancy losses before 24 weeks of gestation. It affects 3-5% of women who are attempting to conceive. RPL can stem from a variety of causes and is frequently associated with psychological distress and a diminished quality of life. By contrast, recurrent implantation failure (RIF) refers to the inability to achieve a successful pregnancy after three or more high-quality embryo transfers or at least two instances of egg donation. RIF shares several causative factors with RPL. The immunological underpinnings of these conditions involve alterations in uterine NK cells, reductions in M2 macrophages and myeloid-derived suppressor cells, an increased Th1/Th2 ratio, a decreased Treg/Th17 ratio, the presence of shared ≥3 HLA alleles between partners, and autoimmune disorders. Various therapeutic approaches have been employed to address these immunological concerns, achieving varying degrees of success, although some therapies remain contentious within the medical community. This review intends to explore the immunological factors implicated in RPL and RIF and to analyze the immunological treatments employed for these conditions, which may include steroids, intravenous immunoglobulins, calcineurin inhibitors, anti-TNF antibodies, intralipid infusions, granulocyte colony-stimulating factor, and lymphocyte immunotherapy.

Assessment of the risk of unexplained recurrent spontaneous abortion based on the proportion and correlation of NK cells and T cells in peripheral blood

BACKGROUND

Unexplained recurrent spontaneous abortion (URSA) is difficult to diagnose and treat clinically due to its unknown causeOBJECTIVE: Changes in natural killer (NK) cells, T lymphocytes, and Th1(IFNγ)/Th2(IL-4) cytokines were investigated in the peripheral blood of patients with URSA to examine the pathogenesis, clinical diagnosis, and inform potential treatment strategies for this condition.

METHODS

For this study, we selected patients with URSA as the case group and included normal women in the control group. Flow cytometry was performed to detect lymphocytes and cytokines in the peripheral blood of all subjects.

RESULTS

The proportion of NK cells, Th1 cells, and the Th1/Th2 ratio were significantly higher in the URSA group compared to the control group; whereas the proportion of CD3+T cells was lower. Pairwise correlation analysis revealed a positive correlation between the percentage of NK cells and CD3+T cells, as well as CD3+CD4+T cells. Canonical correlation analysis indicated a significant correlation between NK cells and T cells, including their subgroups.

CONCLUSION

Patients with URSA have immune balance disorders, characterised by an increased proportion of peripheral blood NK cells, Th1, and Th1/Th2 ratio along with a decreased proportion of CD3+T cells. The proportion of NK cells and CD3+T may serve as predictive factors for URSA, while NK cells are closely related to the regulation of CD3+T cells and their subsets. By regulating the level of IFN-γ, NK cells can influence the proportion of CD3+T cells and induce a Th1 (IFNγ)/Th2 (IL-4) imbalance.

Understanding human immunity in idiopathic recurrent pregnancy loss

Miscarriage, defined as the loss of a pregnancy before a viable gestation, affects 1 in 6 couples. Recurrent pregnancy loss (RPL), defined as two or more miscarriages, affects up to 1.9% of couples. The physical, psychological, and financial impact of miscarriage can be substantial. However, despite its multifactorial etiology, for up to 50% of couples a reason behind this condition cannot be identified, termed 'idiopathic RPL'. Much recent research has strived to understand this, with immune dysregulation being a source of particular interest. In this short review we summarize the current evidence on the complex role of the immune system both pre- and early post-conception in RPL. A key question is whether systemic peripheral blood markers, in particular natural killer cell and T cells, may be utilized to accurately predict and/ or diagnose those pregnancies at high risk of loss. Given the invasive nature of endometrial testing, identification of reliable peripheral immune biomarkers is particularly appealing. Clinical trials using potent immunomodulatory agents, including intravenous immunoglobulin, donor leukocyte immunization, and tumor necrosis factor (TNF)-α inhibitors, have been undertaken with the primary objective of preventing miscarriage in women with RPL. Standardisation of both diagnostic and prognostic immune cell testing assays is required to permit accurate identification of those women who may benefit from immunomodulation. Prompt clarification is required to meet the increasing expectation from couples and clinicians, as without these advancements women are at risk of exposure to potent immune-therapies and subsequent studies are at risk of failure, generating further controversy regarding the role of immune dysregulation in women with RPL. Through this review we highlight clear gaps in our current knowledge on immune activity in RPL.

Extracellular Vesicles: An Important Biomarker in Recurrent Pregnancy Loss?

Recurrent pregnancy loss (RPL) has an estimated incidence of 1–3% of all couples. The etiology is considered to be multifactorial. Extracellular vesicles (EVs) take part in numerous different physiological processes and their contents show the originating cell and pathophysiological states in different diseases. In pregnancy disorders, changes can be seen in the composition, bioactivity and concentration of placental and non-placental EVs. RPL patients have an increased risk of pregnancy complications. The aim of this prospective study was to examine whether measuring different specific EV markers in plasma before and during pregnancy could be used as predictors of pregnancy loss (PL) in women with RPL. Thirty-one RPL patients were included in this study; 25 had a live birth (LB group) and six had a new PL (PL group). Five blood samples were obtained, one before achieved pregnancy and the others in gestational week 6, 8, 10 and 16. Moreover, some of the patients received intravenous immunoglobulin (IVIG) infusions as part of treatment, and it was also examined whether this treatment influenced the EV levels. Seventeen EV markers specific for the immune system, coagulation, placenta and hypoxia were analyzed in the samples with EV Array, a method able to capture small EVs by using an antibody panel targeting membrane proteins. Comparing the LB and PL groups, one EV marker, CD9, showed a significant increase from before pregnancy to gestational week 6 in the PL group. The changes in the other 16 markers were nonsignificant. One case of late-onset PL showed steeply increasing levels, with sudden decrease after gestational week 10 in nine of 17 markers. Moreover, there was an overall increase of all 17 markers after IVIG treatment in the LB group, which was significant in 15 of the markers. Whether increases in EVs positive for CD9 characterize RPL patients who subsequently miscarry should be investigated in future larger studies.

Immunoglobulin G4 deficiency can be a new entity for primary recurrent miscarriage: Successful pregnancy in two cases after treatment with intravenous immunoglobulin

Recurrent miscarriage is one of the complications of pregnancy in which the potential role of immunologic factors has already been mentioned. Here, two young women with recurrent miscarriage were consulted in the infertility center. The diagnosis of immunoglobulin G4 (IgG4) deficiency was made through the reduction of IgG4 Ig levels and normal total IgG titer. Considering this abnormality, intravenous Ig 200 mg/kg was started monthly, and they both had successful pregnancies. Little is known about IgG4 deficiency in women with recurrent miscarriage. IgG4 deficiency should be taken into account in these patients. It is expected that these results will shed further light on the feasibility of intravenous Ig for women with recurrent miscarriage.

T cell Subsets in Peripheral Blood of Women with Recurrent Implantation Failure

The objective of this study was to determine whether there are any differences in the T cell composition and the expression of specific factors (i.e., IRF4, TBX21, GATA3, and GITR) of T cells between women with Repeated Implantation Failure (RIF) and fertile women. We observed a decrease in circulating Tregs and exhausted CD8 + T cells in RIF patients when compared to the controls whereas exhausted Treg and Th17 cells were more frequent. Using real-time PCR, we determined that the expression of IRF-4 and TBX21 was significantly elevated in the cases. In contrast, mRNAs encoding GATA3 and GITR were reduced. Furthermore, the expression of some miRNAs involved in T cell differentiation and their target gene candidates were examined in T cells from women with RIF and fertile control women. The patients showed significant up-regulation of miR-25, miR-93, and miR-326. miR-155 and miR-146a demonstrated significant down-regulation in RIF patients. The results revealed that the expression pattern of target genes was in line with data for miRNAs expression from purified Treg and Th17 cells. The findings of real-time PCR analysis provided insights into the genetic pathways underlying this aberration in the proportions of T cell subsets. Our data suggest that a combination of higher pro-inflammatory Th17 and exhausted Treg cells, and lower Treg and exhausted CD8 + T cells may co-exist in the peripheral blood of women with RIF. Moreover, the expression level of transcription factors and miRNAs controlling T cell differentiation may differ in women with RIF influencing pregnancy outcomes in these women.

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.

Elevated percentage of CD3+T cells and pregnancy outcome in women with recurrent pregnancy loss

BACKGROUND

Even though the immune factor is not yet established as a cause of recurrent pregnancy loss (RPL), tons of other studies have shown that a significant proportion of immune abnormalities exist in RPL.

METHODS

We conducted a retrospective cohort study with 850 women who were diagnosed with RPL. The percentages of CD3⁺, CD3⁺CD4⁺ and CD3⁺CD8⁺T cells of each participant, detected by flow cytometry, were obtained before pregnancy and at 6 weeks of gestation as part of their routine medical examination.

RESULTS

Peripheral blood CD3⁺ T cells prior to pregnancy (at baseline), increased significantly in women who had a miscarriage compared with the subsequent live birth group. Moreover, the percentage of CD3⁺ and CD3⁺CD4⁺T cells during pregnancy increased significantly as compared with the baseline level. After adjusting for potential confounders, the multiple regression equation showed that the CD3⁺ T cells <67.84% was associated with the risk of miscarriage (OR 1.05, 95% CI, 1.01 to 1.11, p = .04). Additionally, a nonlinear relationship was observed between the percentage of CD3⁺T cells and the risk of miscarriage.

CONCLUSIONS

The risk of miscarriage increased as the percentage of population with CD3+ value below 67.84% has increased, nevertheless, the miscarriage risk did not increase further when the level of CD3⁺T cells was >67.84%.

Reference values for maternal total and differential leukocyte counts in different trimesters of pregnancy and the initial postpartum period in western Turkey

The aim of this study was to investigate alterations in the leukocyte and differential leukocyte counts in different trimesters of pregnancy and the initial postpartum period. The study population consisted of 40,325 pregnant women. A full blood count and automated differential leukocyte count were performed and all the haemogram results in the different trimesters of pregnancy were recorded. Percentiles were calculated using statistical software. A total of 82,786 complete blood count evaluations were performed in 40,325 subjects from the 6th to 41st week of pregnancy and in the initial postpartum period. The leukocyte counts increased from the 1st to the 3rd trimester and peaked in the initial postpartum period. Our reference values for the total and differential leukocyte counts may assist clinicians in distinguishing between leukocytosis and pathological elevation of the white blood cell count during pregnancy and the initial postpartum period. Impact statement Pregnancy requires profound adaptation by multiple systems to accommodate the demands of the developing foetus. Similar to all other systems, many haematological changes occur during pregnancy. Studies of normal variation in leukocyte counts were insufficient to distinguish normal from abnormal leukocyte counts during pregnancy and in the initial postpartum period, due to small numbers of patients and a lack of differential leukocyte counts. Without reference leukocyte levels, infections may be more difficult to assess during pregnancy and in the postpartum period. In this study, we report the 3rd, 5th, 10th, 50th, 95th and 99th percentile values for the total and differential leukocyte counts according to trimester in normal pregnancy and the initial postpartum period. Our reference values for the total and differential leukocyte counts in each trimester and the initial postpartum period may assist clinicians in distinguishing between normal leukocytosis and pathological elevation of the white blood cell count during pregnancy and the initial postpartum period. Our results may prevent misdiagnosis of physiological elevated leukocytes as bacterial infection that leads to unnecessary medication use that may compromise the foetus.