Loss of Surface CD200 on Stored Allogeneic Leukocytes may Impair Anti-abortive EffectIn Vivo

The Impact of New Immunological Therapeutic Strategies on Recurrent Miscarriage and Recurrent Implantation Failure

Maternal-fetal immune dysregulation is one of the risk factors that increases the probability of embryo rejection and reproductive failure. The stimulation of immunological tolerance and suppression of immunological rejection are prerequisites for protecting embryos and preventing immunological attacks. Hence, it appears that immunomodulatory and immunosuppressive therapies can manage reproductive failures by controlling immune cells. The current medical literature has shown that immunotherapy approaches and cell therapy have promising results in improving pregnancy outcomes and live birth rates. These outcomes are obtained by regulating maternal immune responses, and exerting positive effects on human reproductive processes.

Lymphocyte immunotherapy in recurrent miscarriage and recurrent implantation failure

PROBLEM

Lymphocyte immunotherapy (LIT) emerged in the early 1980s as a new therapeutic proposal for couples with a history of recurrent miscarriages (RM). However, in the early 2000s, the effectiveness of LIT was questioned. Recently, meta-analyses have observed the effectiveness and safety of LIT in treating couples with RM. Some studies evaluated the use of LIT in recurrent implantation failure (RIF) in in vitro fertilization cycles.

METHODS

This systematic and narrative review evaluated the data available in the literature regarding the efficacy and safety of the use of LIT. Searches in PubMed/Medline, Embase, and Cochrane Library databases were conducted, using the following keywords: "recurrent miscarriage," "lymphocyte immunotherapy," and "recurrent implantation failure".

RESULTS

This review describes the historical aspects of LIT and discusses its protocols, mechanisms of action, side effects, complications, and current evidence of the effectiveness in cases of reproductive failure. It also discusses the use of LIT during the COVID-19 pandemic and new immunological therapies.

CONCLUSION

In the vast majority of studies, the use of LIT for RM couples has shown an improvement in pregnancy outcomes. The most of the current studies that support the evidence are quasi-experimental, with few randomized, double-blind studies (Level of evidence III). However, the current evidence are not convincing for the use of LIT in RIF patients.

Is there a Role of Intravenous Immunoglobulin in Immunologic Recurrent Pregnancy Loss?

Recurrent pregnancy loss (RPL) commonly refers to three or more miscarriages that occur before 20 weeks of pregnancy. The immunological cause of RPL could be either an auto- or alloimmune-related event or both. Because of the discovery of immunological abnormalities in RPL patients in clinical practice, several immunomodulatory therapies were introduced to maintain the immune balance at the maternal-fetal interface. Intravenous immunoglobulin (IVIg) is one of the immunomodulators. In recent years, several studies have analyzed the therapeutic effect of IVIg on RPL patients with antiphospholipid syndrome (APS) or unexplained RPL. However, their results are controversial. IVIg can be used in RPL patients with APS who have previously failed in other treatments. It is recommended that IVIg infusion could be considered used before conception in RPL patients who have cellular immune abnormalities such as increased natural killer (NK) cell counts, NK cell cytotoxicity, or increased T helper (Th)1/Th2 ratio, depending on the cut-off values of each hospital. The aim of this review was to summarize the mechanisms, efficacy, pharmacokinetics, and side effects associated with passive immunization using IVIg in immunologic RPL, according to the literature published in recent years. We hope that more obstetricians will be able to understand the timing and indication of IVIg properly in immunologic RPL patients and effectively enhance pregnancy outcomes for mothers and neonates.

Intrauterine perfusion immunotherapies in recurrent implantation failures: Systematic review

Studies have investigated the gestational outcomes of new immunological therapies in the treatment of patients with recurrent implantation failure (RIF) in assisted reproductive technology (ART). The objective of this article is to assess the current state of evidence available in the literature on intrauterine perfusion immunotherapies in women undergoing ART treatments. By considering the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA), the authors performed systematic review by searching the databases of PubMed/MEDLINE and Scopus using the following key words: "recurrent implantation failure," "intrauterine infusion," "Platelet-Rich Plasma (PRP)," "Peripheral Blood Mononuclear Cells (PBMC)," "Granulocyte Colony-Stimulating Factor (G-CSF)," and "Human Chorionic Gonadotropin (hCG)." The authors analyzed the indications and the impact of new immunological therapies with intrauterine infusions on the pregnancy outcomes of patients undergoing ART. PRP, PBMC, G-CSF, and hCG were the four most used immunological therapies with intrauterine infusion. These new therapies appear to improve the results of ART treatments in cases of RIF. However, the small number of studies does not allow definitive conclusions about the effectiveness of these therapies.

Gestational and perinatal outcomes in recurrent miscarriages couples treated with lymphocyte immunotherapy

Objective

This study aims to elucidate which types of recurrent miscarriage (RM) patients experienced a livebirth after paternal lymphocyte immunotherapy (LIT) and to evaluate the perinatal outcome.

Study design

Retrospective analysis of a multicenter, observational study which enrolled 1096 couples with a history of two or more spontaneous miscarriages without any intercalated delivery. We conducted an intention-to-treat analysis of couples with RM treated with or without LIT regarding to gestational and perinatal outcomes. We compared groups by using the Student’s t-test or Kruskal–Wallis test, Fisher’s exact-test and χ² test when appropriate.

Results

The success of gestation was significantly higher in the LIT group (60.1% vs. 33.1%; p <  0.001). A sub-analysis of four different immune disorder groups revealed a significantly higher success in the LIT group in all immune categories, except in patients who had autoantibodies positive. We observed no significant differences in perinatal outcomes such as gestational age at birth, preterm and extreme preterm birth, and birth weight in successful pregnancy in both groups. The success rate was significantly higher when LIT was administrated before and during pregnancy and only during pregnancy compared to only before pregnancy (p <  0.01).

Conclusions

Careful laboratory test phenotyping of RM patients may identify subgroups most likely to benefit and exclude those with little likelihood of benefit, and LIT during a pregnancy may significantly improve success rates.

CD200:CD200R-Mediated Regulation of Immunity

The type 1 membrane glycoprotein CD200, widely expressed on multiple cells/tissues, uses a structurally similar receptor (CD200R1), whose expression is more restricted to cells of the myeloid and lymphoid lineages, to transmit signals affecting responses in multiple physiological systems. Thus CD200 expression is reported to exert effects on cancer growth, autoimmune and allergic disorders, infection, transplantation, bone development and homeostasis, and reproductive biology. It was initially thought, based on the idea that CD200R1 was mostly expressed on cells of myeloid origin, that CD200:CD200R1 interactions were primarily dedicated to controlling myeloid cell function. However additional members of the CD200R family have now also been identified, although their function(s) remain unclear, and CD200R1 itself is now known to be expressed by subsets of T cells and other cells. Together these observations add layers of complexity to our understanding of CD200-related regulation. In common with a number of physiological systems, the mechanism(s) of CD200-induced signaling seem to fit within a similar framework of opposing actions of kinases and phosphatases. This paper highlights the advances in our knowledge of immunoregulation achieved following CD200:CD200R interaction and the potential clinical applicability of that information.

Immunotherapy of patients with recurrent spontaneous miscarriage and idiopathic infertility: does the immunization-dependent Th2 cytokine overbalance really matter?

Recurrent spontaneous miscarriage (RSM) and idiopathic infertility (IIF) are partially caused by immunologic disturbances. Paternal lymphocyte immunization (PLI) is proposed for restoration of the proper Th1/Th2 balance in these patients, but still there are controversies on PLI mechanism, its efficacy and identification of patients who may benefit from this therapy. The study group consisted of n = 34 RSM and n = 42 IIF women with unexplained miscarriage or IIF. PLI was offered as a treatment in both groups. Peripheral blood lymphocyte (PBL) populations (CD3(+), CD3(-)/CD19(+), CD3(+)/CD4(+), CD3(+)/CD8(+), CD3(-)/CD16(+)CD56(+)) were studied before immunization, while PBL cytokine secretion (IFN-γ, TNF-α, IL-10, IL-5, IL-4, IL-2), before and after immunization, pre-conceptionally in both groups. The reference PBL ratio and cytokine levels were adopted from previously studied normal fertile women. PBL populations, concentration and ratio of Th1/Th2 cytokines did not differ between RSM and IIF patients. Compared to the results observed in normal fertile women the levels of IFN-γ, TNF-α and IL-2 were higher, while IL-10 lower in both RSM and IIF patients (p < 0.01). After immunization a decrease of IFN-γ (RSM and IIF groups) and IL-4 and IL-10 (RSM group) were observed, as well as an increase in TNF-α/IL-4 ratio (RSM group) (p < 0.05). No differences in Th1/Th2 concentration and ratio between patients with successful and unsuccessful pregnancy were observed. No significant correlations between success and particular cytokine concentration were observed. Concentrations of Th1/Th2 cytokines and PBL populations did not differ between RSM and IIF women. Th1 shift in both RSM and IIF patients was observed in comparison to fertile women. Treatment with PLI-induced pre-conceptionally cytokine changes which neither indicated Th2 shift nor correlated with subsequent pregnancy success.

Fetal rejection: infertility and immunity

Defective reaction toward fetal alloantigens could result in both recurrent spontaneous abortions (RSAs) and recurrent early pregnancy failures (REPFs), the latter existing in couples with unexplained infertility and multiple failures of implantation after in vitro fertilization embryo transfer. Immunological mechanisms leading to RSA and REPF seem to be different, although both syndromes probably have a genetic background that has not been identified so far. Despite the fact that antiphospholipid syndrome is a well-established cause of repeated pregnancy loss, the role of different autoantibodies existing in RSA and REPF patients needs to be elucidated. Immunotherapy is believed to correct the detrimental immune reactions; however, its real effectiveness and safety for the treatment of distinct forms of pregnancy loss need to be reconsidered.

LPS-induced murine abortions require C5 but not C3, and are prevented by upregulating expression of the CD200 tolerance signaling molecule

PROBLEM

Lipopolysaccharide (LPS) acts via tlr4 to promote Th1 cytokine secretion and abortions. LPS is an essential co-factor in spontaneous abortion in the CBA x DBA/2 model and in stress-triggered abortions. In the CBA x DBA/2 model, C3a, C5a, and fgl2 prothrombinase participate in triggering inflammation that terminates embryo viability. As fgl2 prothrombinase (via thrombin) can generate C5a, it was predicted that LPS-driven abortions (which require fgl2) would be independent of C3. CD200Fc can prevent abortions in the CBA x DBA/2 model, but an action through Fc could not be excluded.

METHOD OF STUDY

C3(-/-) and C5(-/-) knock-out mice on a B6 background were syngeneically mated and Salmonella enteritidis LPS was administered i.p. on day 6.5 or pregnancy along with 2 mg progesterone in sesame oil s.c. The total number of implants and the number of resorbing embryos were counted on day 13.5 of pregnancy. CD200-rtTA double transgenic homozygous males (B6 background) mated with B6(+/+) females were similarly treated. To up-regulate CD200 expression in embryonic trophoblasts, doxycycline was added to the drinking water from the time of mating.

RESULTS

The LPS boosted the abortion rate from 15.5% (control) to 42.0% in C3(-/-) mice (chi(2) = 9.28, P < 0.005). In C5(-/-) mice, there was no increase in abortion rate with LPS compared to progesterone-treated controls (22.8%versus 26.3%, P = NS). LPS-treated transgenic mice given LPS + progesterone had a 42.5% abortion rate, but when the mice were given doxycycline to induce expression of CD200 by the embryo, the abortion rate was only 8.3% (chi(2) = 14.40, P < 0.005, Fisher's exact test P = 0.00007).

CONCLUSION

C5, but not C3, appears necessary for LPS-driven abortions. Up-regulation of CD200 can prevent LPS-driven abortions, possibly by altering dendritic cells to promote Treg cell development or by a direct suppressive action on macrophages and mast cells that also express CD200 receptors.

Decreased expression of CD200 and CD200 receptor in Alzheimer's disease: a potential mechanism leading to chronic inflammation

Inflammatory activation of microglia in response to neurodegenerative changes in diseases such as Alzheimer's disease (AD) and Parkinson's disease has been extensively described. These observations have suggested that inflammation could be contributing to disease progression. In this paper, the potential role of CD200 and CD200 receptor (CD200R), whose known functions are to activate anti-inflammatory pathways and induce immune tolerance through binding of CD200 to CD200 receptor (CD200R), was studied in AD. Quantitative studies showed a significant decrease in CD200 protein and mRNA in AD hippocampus and inferior temporal gyrus, but not cerebellum. Immunohistochemistry of brain tissue sections of hippocampus, superior frontal gyrus, inferior temporal gyrus and cerebellum from AD and non-demented cases demonstrated a predominant, though heterogeneous, neuronal localization for CD200. Decreased neuronal expression was apparent in brain regions affected by AD pathology. There was also a significant decrease in CD200R mRNA expression in AD hippocampus and inferior temporal gyrus, but not cerebellum. Low expression of CD200R by microglia was confirmed at the mRNA and protein level using cultured human microglia compared to blood-derived macrophages. Treatment of microglia and macrophages with interleukin-4 and interleukin-13 significantly increased expression of CD200R. Expression of these cytokines was not generally detectable in brain. These data indicate that the anti-inflammatory CD200/CD200R system may be deficient in AD brains. Mechanisms aimed at increasing levels of CD200 and CD200R could have therapeutic potential for controlling inflammation in human neurodegenerative diseases.

CD200-dependent and nonCD200-dependent pathways of NK cell suppression by human IVIG

PROBLEM

Intravenous immunoglobulin (IVIG) has been used to suppress autoimmune and inflammatory disorders by a variety of mechanisms. Recently, the CD200 tolerance-promoting signal has been found to play a role in IVIG suppression of blood natural killer (NK) cells. Further, different types of IVIG have been reported to differ in this activity, and that has been related to efficacy (and inefficacy) of treatment of women with pregnancy failure. CD200 acts by binding to CD200 receptors (C200R). The objective of this study was to determine if CD200-dependent NK suppression by IVIG involved direct binding of IVIG-associated CD200 molecules to CD200R on NK cells.

METHOD OF STUDY

Peripheral Blood Lymphocytes isolated from human blood were used as a source of NK cells to lyse Cr(51)-labelled K562 target cells in vitro in 18 and 4 h assays, and three different types of IVIG were tested for suppressive activity in the presence or absence of specific monoclonal anti-huCD200. In some experiments, CD56(+) NK cells were purified using anti-CD56 magnetic beads. Western blotting of IVIG using a specific anti-huCD200 antibody was done. Enzyme-Linked ImmunoSorbent Assays were used to measure cytokine production in NK assays.

RESULTS

Different IVIGs showed significant differences in potency in suppressing NK cytolytic activity in vitro (mg/ml for 60% suppression, Gammagard 4.1, Gamunex 14.1, Gamimmune 20.2). For CD200-dependent suppression, Gammagard was twice as potent as Gamimmune, but equivalent to Gamunex. The presence of suppression in 4 hour assays indicated stimulation of cytokine synthesis was unlikely to explain CD200-dependent suppression. Purification of NK cells led to loss of the CD200-dependent component. Western blotting confirmed that material reactive with anti-CD200 antibody was present in Immunoglobulin G (IgG) preparations, and at a lower level in human serum that contains IgG.

CONCLUSIONS

IVIGs are not all equipotent in suppressing NK cell cytolytic activity. CD200 associated with IVIG is an important component of suppression. CD200-dependent suppression appears to be mediated by a non-NK population that then acts on NK cells by direct contact rather than indirectly through release of immunosuppressive cytokines.

Administration of high-dose intact immunoglobulin has an anti-resorption effect in a mouse model of reproductive failure

Administration of high-dose intact human immunoglobulin (IH-Ig) has been applied to treat a variety of inflammatory and autoimmune diseases, and is expected to have beneficial effects on human fecundity. In the present study, we investigated whether Ig had anti-resorption effects using polyinosinic-polycytidylic acid sodium salt [poly (I:C)]-induced enhancement of fetal resorption in the mating of CBA/J x DBA/2J resorption-prone mouse model. Furthermore, we investigated the mechanism of the effect by examining the mRNA expression of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, IL-10, IL-4 and TGF-beta(1) in spleens and placentas from the resorption-prone model treated with IH-Ig, by reverse transcription (RT)-polymerase chain reaction (PCR). Administration of high-dose IH-Ig significantly reduced the fetal resorption rate from 55% to 10%. This anti-resorption effect, however, was not detected in mice administered with Fab fragments of human Ig. We then performed adoptive transfer experiments to examine whether cellular components could transfer the effect. A remarkable anti-resorption effect was seen in poly (I:C)-injected pregnant recipients transferred with spleen cells from IH-Ig-treated donor mice. The RT-PCR study showed that IH-Ig reduced the expression of IFN-gamma and TNF-alpha mRNA in placentas of poly (I:C)-injected pregnant mice. The present findings demonstrate that intact Ig, particularly its Fc portion, possesses anti-resorption activity. The effect might be attributed to the suppressed production of pro-inflammatory cytokines at the maternofetal interface.

The Th1/Th2 paradigm: still important in pregnancy?

The enunciation of the T helper 1/T helper 2 (Th1/Th2) paradigm in pregnancy has represented a major step forward in our understanding of physiological and pathologic materno-foetal relationship. However, recent developments in studies of the implantation process and in the emergence of the uterine vascular bed and its control by natural killer cells and cytokines suggest that one must go beyond this hitherto useful scheme. In this review, we replace the emergence of the paradigm in its historical context and then emphasises what it does explain and what it no longer account for. A final reappraisal of the paradigm is suggested.

Natural killer cell functional activity suppression by intravenous immunoglobulin, intralipid and soluble human leukocyte antigen-G

PROBLEM

The purpose of this study was to compare the ability of intravenous immunoglobulin (IVIg), intralipid and soluble human leukocyte antigen (sHLA)-G to suppress natural killer (NK) cell cytotoxicity in an in vitro assay.

METHOD OF STUDY

Blood samples taken from 275 women experiencing reproductive failure were analyzed for NK cytotoxicity and the suppression of NK cytotoxicity by IVIg 4 and 2 mg/mL (n = 275), intralipid 18 and 9 mg/mL (n = 275) and sHLA-G 70 and 35 ng/mL (n = 50) using immunofluorescent labeled K562 cells as targets and flow cytometry.

RESULTS

Natural killer cytotoxicity was suppressed in all samples. Among patients with normal NK cell activity, IVIg suppressed NK cytotoxicity by 44.9 +/- 8.1%, intralipid suppressed NK killing by 45.2 +/- 8.3% and sHLA-G suppressed by 49.0 +/- 9.2%. When specimens with abnormal NK activity were observed for suppression of cytotoxicity, IVIg suppressed by 38.9 +/- 5.4%, intralipid suppressed by 39.8 +/- 6.2% and sHLA-G suppressed by 39.9 +/- 5.0%.

CONCLUSION

Intravenous immunoglobulin, intralipid and sHLA-G suppressed NK cell cytotoxicity with equal efficacy in an in vitro assay.

Immunological analogy between allograft rejection, recurrent abortion and pre-eclampsia - the same basic mechanism?

There are still controversies concerning the role of immunological mechanisms engaged both in recurrent abortions (RA) and pre-eclampsia (PE). According to some opinions, recurrent miscarriage is comparable to organ-specific autoimmune disease. Analysis of immune reactions shows that graft rejection shares many similar mechanisms with RA and PE. This fact allows us to conclude that rejection of transplanted alloantigenic organs and pregnancy loss have probably the same evolutionary origin. Subsets and functions of immunocompetent cells (T CD4, suppressor gammadeltaT, cytotoxic T CD8, Treg, Tr1, uterine NK cells), over-activation of innate immunity (activation of NK cytotoxic cells, macrophages, neutrophils and complement), changes of Th1/Th2 cytokine balance (IL-2, IL-12, IL-15, IL-18, IFNgamma, TNFalpha vs. IL-4, IL-10, TGFbeta), importance of HLA-G molecule, CD200/CD200R interaction, over-expression of adhesion molecules, fgl2 prothrombinase activation and stimulation of IDO and HO expression, all suggest that RA and PE are syndromes of fetal allograft rejection, and not organ-specific autoimmune diseases. According to that supposition, an analogy might exist between acute graft rejection and recurrent abortion, and between chronic graft rejection and pre-eclampsia.

Is intravenous immunoglobulins (IVIG) efficacious in early pregnancy failure? A critical review and meta-analysis for patients who fail in vitro fertilization and embryo transfer (IVF)

PROBLEM

Intravenous Immunoglobulins (IVIG) are widely used off label in the treatment of early reproductive failure. As IVIG is expensive, and may have side-effects, evidence of efficacy is needed. Previous results have suggested that the pre-conception treatment of primary recurrent abortion patients might be effective, but the data set has been too small for adequate statistical power. More recently it has been suggested that IVIG may improve the success rate of in vitro fertilization and embryo transfer (IVF) in patients with prior IVF failures, but clinical trials have given conflicting results that need explanation. Systematic reviews generating inconclusive results have focused on methodological rigor to the exclusion of biological plausibility.

METHODS

Review of current basic science of design, measurement, and evaluation of clinical trials and basic science mechanisms providing a rationale for treatment. Meta-analysis of published randomized controlled and cohort-controlled trials (updated with two unpublished data sets) evaluating IVIG treatment in IVF failure patients. Live birth rate was used as the most relevant endpoint. The ability of different sources of IVIG to suppress natural killer (NK) cell activity was determined using a standard (51)Cr-release assay in vitro.

RESULTS AND CONCLUSIONS

Meta-analysis of three published randomized controlled trials (RCTs) of IVIG in IVF failure patients shows a significant increase in the live birth rate per woman (p = 0.012; Number Needed to Treat for 1 additional live birth, NNT = 6.0 women). Using live birth rate per embryo transferred, and adding data from two cohort-controlled trials to the meta-analysis further supports this conclusion (overall p = 0.000015, NNT = 3.7 women). Relevant variables appear to include properties and scheduling of the IVIG, and selection of patients with abnormal immune test results. Different IVIG preparations vary significantly in their ability to suppress NK activity in vitro. A rationale for use of IVIG is provided by a review of mechanisms of IVIG action and mechanisms underlying failure of chromosomally normal embryos.