Antiphospholipid syndrome and miscarriage

Antiphospholipid syndrome is the most common cause of thrombophilic complications and associated habitual pregnancy loss. There are primary antiphospholipid syndrome and secondary - if there is also an autoimmune disease (most often it is systemic lupus erythematosus). There is no big difference in all parameters between the primary antiphospholipid syndrome and the secondary one, only the symptoms of an autoimmune disease are added to the secondary one. There is also a "catastrophic antiphospholipid syndrome".

The cause of the antiphospholipid syndrome remains unclear, it is believed that the role of viral infections. The pathogenesis of the antiphospholipid syndrome is due to the fact that autoantibodies with heterogeneous specificity are directed against negatively charged phospholipids or phospholipid-binding proteins.

Based on numerous studies by a working group of experts in this field, the following criteria for antiphospholipid syndrome were adopted at the last symposium in September 2000 in France, in order to compare studies conducted in different countries.

Criteria for the classification and definition of APS

Clinical criteria

Vascular thromboses - one or more clinical episodes of arterial, venous in any tissue or organ. Thrombosis should be confirmed by dopplerometric or histological examination, with the exception of thrombosis of superficial small veins. For histological confirmation, thromboses should not be accompanied by inflammatory processes in the vascular wall.

In pregnancy:

• One or more unclear deaths of a morphologically normal fetus are older than 10 weeks of gestation, with a normal morphology given by an ultrasound scan or a direct examination of the fetus.
• One or more premature births by morphologically normal newborns until 34 weeks of gestation due to preeclampsia or eclampsia, or severe placental insufficiency.
• Three or more unclear causes of spontaneous miscarriages before 10 weeks of pregnancy in the mother after excluding the anatomical, hormonal and genetic causes of the interruption.

Laboratory criteria:

• Anticardiolipin antibodies of IgG and / or IgM isotypes in the blood, at an average or high titer 2 or more times in a 6-week study, examined by a standard enzyme-linked immunosorbent assay for beta2-glycoprotein-1-dependent anti-cardiolipin antibodies.
• Lupus anticoagulant present in the plasma 2 or more times in a row, when tested at intervals of 6 weeks, examined according to the guidance of the International Society of Thrombosis and Hemostasis by the following route:
  • Elongation of phospholipid-dependent coagulation in coagulation tests: activated partial thromboplastin time (APTT); clotting time with goat; research with snake venom; lengthening prothrombin time, Texturin-time.
  • The inability to correct the coagulation time in a screening test in a mixture with normal platelet-poor plasma.
  • Shortening or correcting the elongated coagulation time by adding excess phospholipids to the screening test.
  • Exclusion of other coagulopathies, i.e. An inhibitor of factor VIII, heparin, and others.

Among laboratory criteria, such tests as low level of anticardiolipin antibodies, IgA-anticardiolipin antibodies, anti-beta2-glycoprotein-1, antibodies to prothrombin, annexin or neutral phospholipids are excluded, Wasserman's false-positive reaction.

The working group believes that these methods require further study. As for anti-beta2-glycoprotein-1, which, according to most researchers, plays a key role in the development of thrombophilia, this test requires in-laboratory standardization and technical improvement. Perhaps in the future this test will be the main criterion in the diagnosis of antiphospholipid syndrome.

At present, studies have appeared on the role of anti-beta2-glycoprotein-1 IgA and IgG in the development of antiphospholipid syndrome. In groups of women with a clinical picture of antiphospholipid syndrome in the absence of cardiolipin antibodies and BA, a high level of these antibodies was detected.

According to the published data, the incidence of antiphospholipid syndrome among patients with a habitual loss of pregnancy is 27-42%.

The population frequency of this condition has not been studied in our country, and in the United States it is 5%.

There are two classes of antiphospholipid antibodies formed under the influence of endogenous stimuli:

1. Antiphospholipid antibodies elongating in vitro phospholipid -dependent coagulation reactions, affecting Ca ^2+-dependent binding of prothrombin and factors Xa, Va in the process of assembling the prothrombin-activator complex (prothrombinase) - lupus anticoagulant (VA);
2. Antiphospholipid antibodies, which are determined by immunological tests based on cardiolipin - anticardiolipin antibodies (AKA).

Autoantibodies to phospholipids can occur under the influence of exogenous and endogenous stimuli. Exogenous stimuli are associated mainly with infectious antigens, they lead to the formation of transient antibodies that do not cause thrombembolic disorders. An example of such exogenous antiphospholipid antibodies is the antibodies detected by the Wasserman reaction.

Antibodies produced by endogenous stimuli are associated with impaired endothelial hemostasis. These antiphospholipid antibodies cause thromboembolic disorders, often associated with strokes, infarctions in young people, with other thromboses and thromboembolism, the development of the syndrome of Snedon. The explanation for this phenomenon was obtained in recent years when it was established that the presence of a plasma component (cofactor) that was identified as beta-glycoprotein-1 beta-1-beta-1 was required to bind antibodies present in the sera of patients with autoimmune but not infectious diseases, with cardiolipin GP-1). In a more detailed study of this phenomenon, scientists have shown that antibodies to cardiolipin isolated from sera from patients with autoimmune diseases reacted with cardiolipin only in the presence of UGP-1, while the binding of antibodies to cardiolipin (ACA) synthesized in patients with various infectious diseases malaria, infectious mononucleosis, tuberculosis, hepatitis A and syphilis), did not require cofactor in the system. Moreover, the addition of beta2-GP-1 in some cases inhibited the interaction of sera from patients with infectious diseases with cardiolipin. Clinical analysis of the results showed that the development of thrombotic complications was associated with the synthesis of cofactor-dependent antibodies to cardiolipin. However, according to other data, even in patients with antiphospholipid syndrome, despite the presence of beta2-GP-1, the ability of antibodies to phospholipids (AFA) to interact with cardiolipin is due to a number of other factors. Thus, the binding of low-like antiphospholipid antibodies to cardiolipin is more dependent on the presence of cofactor in the system than is required in the case of the presence of highly-viscous antibodies in the sera. On the contrary, A.E. Gharavi (1992) emphasizes that the cofactor dependence is characteristic of highly antibodies. Earlier, in the study of sera from patients with antiphospholipid syndrome, it was shown that in serum, in addition to antiphospholipid antibodies, a large number of various phospholipid-binding proteins reacting with anionic phospholipids (apolipoproteins, lipocortins, placental anticoagulant protein, coagulation inhibitors, C-reactive protein, etc.).

The data presented above suggested the presence of at least two populations of cardiolipin-binding antibodies. Some of them ("infectious" antibodies) have the ability to directly recognize negatively charged epitopes of phospholipids, while others ("autoimmune" antibodies) react with a complex epitope consisting of phospholipid and beta2-GP-1, and possibly other phospholipid-binding proteins.

The development of thrombotic complications is associated with the synthesis of "autoimmune" (cofactor-dependent) antibodies.

In obstetrical practice, great importance is the lupus anticoagulant. It is believed that the detection of lupus anticoagulant in blood is a qualitative manifestation of the effect of certain levels of autoantibodies to phospholipids (cardiolipin, phosphatidylethanol, phosphatidylcholine, phosphatidylserine, phosphatidylazitol, phosphotidic acid) on the state of hemostasis.

An extremely interesting approach in interpreting the immunological aspects of miscarriage is presented in the works of A. Beer and J. Kwak (1999, 2000). The authors distinguish 5 categories of immune disorders that are the cause of habitual miscarriage, IVF failures and some forms of infertility.

1. I category - compatibility of spouses on the HLA system and the connection of the now known antigens of the HLA system with reproductive harm. Compatibility for HLA, according to the authors, leads to ineffective "camouflage" of the placenta and makes it accessible to the mother's immune attack.
2. II category - antiphospholipid syndrome, associated with the circulation of antiphospholipid antibodies. The incidence of antiphospholipid syndrome among patients with habitual miscarriage is 27-42%. The pathogenetic basis of the unsuccessful completion of pregnancy with APS is the thrombotic complications arising at the level of the utero-placental basin. In addition, phosphotidylserine and phosphotidylethanolamine play an important role in the implantation process, as a "molecular adhesive". In the presence of antibodies to these phospholipids, the differentiation of the cytotrophoblast into syncytiotrophoblast may be impaired, which leads to the death of pregnancy in the early stages.
3. The III category of immunological disorders include antinuclear, antihistone antibodies that account for 22% of miscarriages of immune genesis. If these antibodies are present, there may be no manifestations of autoimmune diseases, but inflammatory changes are found in the placenta.
4. IV category - the presence of antisperm antibodies. This category of immunological disorders occurs in 10% of patients with habitual miscarriage and infertility. Antisperm antibodies are detected when women have antiphospholipid antibodies to serine or ethanolamine.
5. V category - the most severe, to it carry 45% of women with failures IVF with infringement of implantation. In this category, several sections are distinguished.

Section 1 is related to an increase in the content of natural killer CD 56 in the blood over 12%. According to the authors, with an increase in CD 56+ above 18% - always the death of the embryo. This type of cells is determined both in the blood and in the endometrium. In addition to the cytotoxic function, they synthesize proinflammatory cytokines, including TNFa. As a result of the excess of pro-inflammatory cytokines, implantation processes are disrupted, trophoblast cells are damaged, followed by development of trophoblast insufficiency, placenta and embryo / fetal death (similar findings were obtained by other authors).

The second section of category V is associated with the activation of CD19 + 5 + cells. The level above 10% is considered pathological. The main importance of these cells is associated with the production of antibodies to hormones that are crucial for the normal development of pregnancy: estradiol, progesterone, chorionic gonadotropin. In addition, there may be antibodies to thyroid hormones, growth hormones. With pathological activation of CD 19 + 5 +, luteal phase failure, inadequate response to ovulation stimulation, "ovarian resistant" syndrome, premature "aging" of the ovaries, premature menopause develop. In addition to directly affecting the listed hormones with excessive activity of these cells, there is a lack of preparatory reactions for implantation in the endometrium and in myometrium, and later in decidual tissue. This is manifested in inflammatory and necrotic processes in decidua, in violation of the formation of fibrinoids, in excessive deposition of fibrin.

Section 3 is associated with a high content of CD 19 + 5 + cells that produce antibodies to neurotransmitters. Including serotonin, endorphins and enkephalins. These antibodies contribute to ovarian resistance to stimulation, affect the development of myometrium, contribute to a decrease in blood circulation in the uterus during implantation. If these antibodies are present, patients may have depression, fibromyalgia, sleep disturbance, panic disorder.

Such a differentiated approach allows us to individually approach the solution of the problem of the role of different immune aspects in the genesis of the habitual loss of pregnancy. Unfortunately, such a clear division in clinical practice does not work. Most often, patients with antiphospholipid syndrome can have antibodies to HCG and antithyroid antibodies, etc.

In recent years, the problem of alloimmune relations regarding compatibility with antigens of the HLA system has been very widely discussed. Many researchers question the existence of this problem, taking into account that HLA antigens are not expressed on the trophoblast. Studies on this issue were raised back in the 70's. A number of researchers believed that leukocyte sensitization like erythrocyte is accompanied by a spontaneous abortion of pregnancy. With Rhesus and ABO-conflict pregnancy, the most frequent complication of pregnancy is the threat of its interruption. But even without sensitization, the threat of interruption is the most frequent complication. Even with severe damage to the fetus and its death from hemolytic disease, termination of pregnancy often does not happen spontaneously. The work carried out by us for a number of years has shown that habitual miscarriage, as a rule, does not have a direct etiological connection with Rh-and AVO-sensibilization. Frequent interruptions, especially after 7-8 weeks (the time of appearance of Rh factor in the fetus), can lead to the appearance of sensitization, which complicates the course of pregnancy. In the conduct of such a pregnancy there are complex problems. Is it worth to examine and treat the habitual miscarriage of pregnancy, if the patient has Rh-sensitization, since, keeping the pregnancy in the early stages, you can get a fetus with a swollen form of hemolytic disease in later terms.

Particular attention is paid in the literature to the question of the role of histocompatibility antigens in miscarriage. The likelihood of allosensitisation of the maternal organism to fetal leukocyte antigens is sufficiently high, given their early formation and ability to penetrate the placenta. The question of the etiological role of leukocyte sensitization is considered extremely contradictory. Many researchers etiologically associate leukosensitivity with miscarriage and recommend immunosuppressive therapy.

The analysis of the data showed that in healthy, multi-valued women, antileukocytic sensitization is observed much more often than in pregnant women with habitual miscarriage (33.6% and 14.9%, respectively). In this case, a number of features are revealed: in women who had multiple pregnancies completed with normal births, leukosensitivity was 4 times more likely than in those who had abortions with artificial abortion (respectively, 33.6% versus 7.2%). Frequent detection of these antibodies in the blood of healthy, multicore women testified to their harmlessness for reproduction processes. On the other hand, the increase in the frequency of occurrence in blood of healthy women of lymphocytotoxic and leukoagglutinating antibodies as the number of normal pregnancies completed by birth increases, indicates the physiological rather than pathological significance of this type of isensensibilization. The production of anti-leukocyte antibodies is a natural process, since the fetus necessarily contains transplant antigens incompatible with the mother, and they seem to protect the fetus from the damaging effect of the mother's immune lymphocytes.

According to the research, when studying the indices of cellular immunity in pregnant women with miscarriages, it was not possible to find significant differences in them from women with a physiologically occurring pregnancy. The significance of the blast-transformation reaction with phytohemagglutinin, the intensity of the blast-transformation reaction in the mixed culture of lymphocytes, the content of serum immunoglobulins did not differ statistically. At the same time, with miscarriage, serum of women significantly more often stimulated cellular immunity, and serum blocking factor was detected in uncomplicated pregnancy. In the physiological course of pregnancy, 83.3% of women were diagnosed with lymphocyte sensitization to fetal antigens. In pregnant women with habitual miscarriages, the sensitization of cells was weaker and less common, the blocking effect of serum was generally absent.

The revealed differences indicate a weakening of the blocking properties of the serum of pregnant women with a threatening spontaneous abortion. Apparently, the immunoregulatory properties of blood serum play a crucial role in the development of pregnancy. With a decrease in the blocking properties of serum, the mechanisms leading to abortion are activated. Similar data were obtained by many researchers.

This theory of the role of the blocking properties of serum in maintaining pregnancy is not recognized by many researchers. Their main motivation is that there are women with normal pregnancy, who do not have blocking antibodies.

Moreover, the methods for determining blocking antibodies are not standardized and have low sensitivity, so that they can obtain similar results accurately and in different laboratories. The detection of blocking antibodies by the reaction of a mixed culture of lymphocytes also has a number of defects:

1. Variability of responses among different patients and even the same, but conducted at different times;
2. difficulties in assessing the degree of suppression, with respect to blocking activity;
3. the sensitivity of the method is unknown;
4. There is no standardization of the method and standards for the evaluation of the result;
5. There is no single method for interpreting data.

Despite this, many groups of researchers consider this problem among the immunological factors of miscarriage. It is believed that blocking antibodies can act in several ways. They can be directed against antigen-specific receptors on the maternal lymphocytes, which prevents their reaction to the antigens of the fetoplacental tissues; or they can react with antigens of fetoplacental tissues and block their recognition by maternal lymphocytes. It is also believed that blocking antibodies are anti-idiotypic antibodies directed against antigen-specific sides (idiots) of other antibodies, i. E. Receptor antigens on the surface of T-lymphocytes can be linked and therefore prevent their action against the embryo. There is evidence that they may be associated with anti-HLA-DR antigens and with anti-Fc receptor antibodies.

In addition to blocking antibodies, there is evidence of the role of lymphocyte antibodies against the lymphocytes of the husband. Most researchers believe that they, as well as blocking antibodies, are a consequence of a normally occurring pregnancy. At 20%, they are detected after the first normal pregnancy, and 64% of them have a lot and successfully delivered women. In women with habitual miscarriage, they are much less common (from 9 to 23%).

Along with this, there are works indicating that the presence of neutrophil-specific antibodies against the father's antigens in the mother may be accompanied by severe neutropenia in the fetus. Neutrophil-specific antigens NA1, NA2, NB1 and NC1 were first characterized by Lalezari et al. (1960). Other antigens of neutrophils NB2, ND1, NE1 were discovered by Lalezari et al. (1971), Verheugt F. Et al. (1978), ClaasF. Et al. (1979) respectively.

N antigens are independent of other antigens present on the surface of neutrophils, such as HLA f. The most significant antigens that cause the production of antibodies are the NA1 and NB1 antigens. The frequency of detection of neutrophil-specific antibodies varies in different studies from 0.2% to 20%. This difference is due to the fact that only recently there have been methods of detecting these antibodies and because severe neutropenia in infants is rare. Most often these children develop infection early and very quickly become sepsis. Therefore, the authors recommend that in all newborns with unclear neutropenia, especially in preterm infants, to conduct blood tests of the mother for the presence of antibodies to neutrophils. In the mother, the presence of antibodies to neutrophils does not produce neutropenia, similar to Rh antibodies, provided they are not autoimmune.

E women with miscarriages can detect autoantibodies against their own lymphocytes - lymphocytotoxic autoantibodies, which in women with habitual miscarriage are detected in 20.5% of cases, whereas in a physiologically occurring pregnancy they are not detected.

Reduction of the blocking properties of serum is associated with compatibility of spouses with antigens of the system HLA (Human leycocyteantigens). The HLA system, or the old name "major histocompatibility complex," is a group of genes whose proteins serve as identity markers on the surface of various cells with which T lymphocytes interact through their own receptors in an immune response. For the first time they were detected in the rejection reaction of the transplant. HLA consists of a group of genes I, II and III classes, located on the 6 th chromosome. This system has a huge polymorphism and only within one chromosome, the number of possible combinations of its genes is 3x10 ⁶.

HLA class I includes HLA-AB and -C loci - these genes represent a family of peptides that react with T-cytotoxic (CD8 +) cells.

To the second class include loci HU \ DP, -DQ and DR - they mainly interact with T-helpers (CD4 +). Region III class of genes takes the main part in inflammation processes, contains alleles of complement components C2, C4 and Bf (properdin factor), as well as TNF (tumor necrosis factor) and a number of isoenzymes. In addition, it was recently discovered that class I molecules also interact with NK cells, preventing lysis of cells.

A large group of immunoglobulins, similar to NK cell receptors, is found on 19 chromosomes - the so-called nonclassical loci of HLA-E, -F and G. They also participate in immune responses, and the fetal HLA-G locus is expressed on the trophoblast.

Allelic variants of genes have a different frequency of occurrence. The symptom of allele frequency is used as a genetic marker of a number of pathological conditions.

In recent years, the links of the HLA system with various diseases have been intensively studied. So it is established that autoimmune diseases, such as arthritis, Reuters disease in 95% are observed in patients with HLA B27 allele, i.e. Almost 20 times more often than this antigen occurs in the population.

In 86.4% of patients with antiphospholipid syndrome, HLA DQ4 is determined. If you have a husband HLA DQ 201 - in 50% of cases will be anembrion.

In the presence of HLA B14 spouses should be examined for the presence of adrenogenital syndrome gene; at HLA B18 the probability of a child with anomalies of development is high.

With habitual miscarriage, an increase in the incidence of some alleles and HLA phenotypes: A19, B8, B13, B15, B35, DR5, DR7, their occurrence is 19%, 9.5%, 19%, 17.5%, 22.2% , 69.6% and 39.1% versus 6.3%, 3.8%, 10.3%, 16.7%, 29.9% and 22.7%, respectively, in women with uncomplicated pregnancy.

In addition to the HLA phenotype, many researchers believe that the compatibility of spouses with antigens HLA plays a very large role. The main idea is that when compatibility with the HLA system does not develop antibodies that play the role of a blocking factor. If the spouses are compatible for more than 2 HLA antigens, the risk of miscarriage is almost 100%.

Compatibility of spouses in the HLA system and its importance in reproduction for a long time remains in the field of attention of immunologists and midwives. There is a whole line of research on the role of lymphocytotherapy in the treatment of habitual miscarriage using the lymphocytes of the father or donor or both. There are many supporters of this therapy.

At the same time, there are many opponents of this therapy who believe that compatibility is unlikely to play a role and lymphocyte therapy does not give the same effect as that of adherents of this therapy.

Different results are obtained from methodologically different approaches to solving this problem: different groups of patients, different amounts of injected lymphocytes, different periods of pregnancy, under which therapy is administered, etc.

There is still in the literature the original point of view about the HLA system According to Chiristiansen OB et al. (1996), the compatibility effect of parental antigens can be of non-immunological origin. In experiments on mouse embryos, the authors demonstrated the existence of a lethal recessive gene closely associated with HLA. Mouse mice homozygous for certain HLA alleles die at different stages of embryogenesis. HLA a similar complex can be and at people. If so, parental HLA compatibility may be secondary, reflecting homozygosity for the embryo for the HLA-related lethal gene.

Further research in this area will allow more precise determination of the location of HLA in the reproductive system.

[1], [2], [3], [4], [5]