Antibodies Against Unusual Forms of Sialylated Glycans.

Previous studies have shown that in the blood of healthy donors (1) there are no natural antibodies against sialylated glycoproteins, which contain Neu5Acα (N-acetylneuraminic acid) as the most widespread form of human sialic acid, and (2) there is a moderate level of antibodies capable of binding unnatural oligosaccharides, where Neu5Ac is beta-linked to a typical mammalian glycan core. In the present study, we investigated antibodies against ßNeu5Ac in more detail and verified the presence of Kdn (2-keto-3-deoxy- D-glycero-D-galacto-nonulosonic acid) as a possible cause behind their appearance in humans, taking into account the expected cross-reactivity to Kdn glycans, which are found in bacterial glycoconjugates in both the α- and ß-forms. We observed the binding of peripheral blood immunoglobulins to sialyllactosamines (where "sialyl" is Kdn or neuraminic acid) in only a very limited number of donors, while the binding to monosaccharide Kdn occurred in all samples, regardless of the configuration of the glycosidic bond of the Kdn moiety. In some individuals, the binding level of some of the immunoglobulins was high. This means that bacterial Kdn glycoconjugates are very unlikely to induce antibodies to ßNeu5Ac glycans in humans. To determine the reason for the presence of these antibodies, we focused on noninfectious pathologies, as well as on a normal state in which a significant change in the immune system occurs: namely, pregnancy. As a result, we found that 2/3 of pregnant women have IgM in the blood against Neu5Acß2-3Galß1-4GlcNAcß. Moreover, IgG class antibodies against Neu5Acß2-3Galß1-4GlcNAcß and Neu5Acß2-6Galß1-4GlcNAcß were also detected in eluates from the placenta. Presumably, these antibodies block fetal antigens.

Comparative Characteristics of Sialoglycans Expression Disorders in the Placental Barrier Structures in Preeclampsia and Fetal Growth Restriction.

We compared the expression profiles of α2,3- and α2,6-sialoglycans in the glycocalyx of the placental barrier structures in early and late forms of preeclampsia and fetal growth restriction using the method of lectin histochemistry. It was found that the expression of α2,3-sialoglycans in the syncytiotrophoblast and fetal endothelium of the terminal villi of the placenta was reduced in preeclampsia in comparison with normal placenta and, on the contrary, was increased in fetal growth restriction. Significant differences were found in both clinical phenotypes of preeclampsia and fetal growth restriction. Changes in the expression pattern of α2,6-sialoglycans in the endothelium of terminal villi were more pronounced than in syncytiotrophoblast. In early and late-onset preeclampsia, a significant increase in the expression of α2,6-sialoglycans was revealed only in the fetal endothelium; in early fetal growth restriction, the expression of α2,6-sialoglycans was reduced in the endothelium, but increased in syncytiotrophoblast in late fetal growth restriction. The features of the expression of sialoglycans in structures of the placental barrier in preeclampsia and fetal growth restriction were revealed, which may indicate the pathogenetic involvement of sialoglycans in the inflammatory activation cascade in fetal growth restriction, and in preeclampsia, apparently, they are associated with impaired fetal tolerance.

Comparative Characteristics of the Expression of Fucosylated Glycans and Morphometric Parameters of Terminal Placental Villi Depending on the Severity of Preeclampsia.

We performed a comparative analysis of the expression of fucosylated glycans and morphometric characteristics of the terminal villi of the placenta, depending on the severity of preeclampsia (PE). Similar patterns of the expression of fucosylated glycans in the syncytiotrophoblast glycocalyx were revealed in the placental tissue of patients with normal pregnancy and with mild and severe PE: predominance of glycans with α1,6-fucose in the core, clustered fucose residues, and LeX glycan over α1,2-fucose-containing glycans. The expression pattern of fucosylated glycans and the composition of the endothelial glycocalyx are normally close to the expression pattern and composition of the syncytiotrophoblast glycocalyx; in case of mild and severe PE, the expression pattern of fucosylated glycans was changed uniformly, and α1,2-fucose-containing glycans significantly prevailed in the endothelial glycocalyx. According to the results of Fisher's LSD test, in patients with severe PE, the total vascular area in the villus prevailed over the indices established during physiological course of pregnancy (p=0.04) and mild PE (p=0.04). Correlation analysis revealed direct and reciprocal relationships between the morphometric characteristics of the terminal villi of the placenta and the expression of fucosylated glycans in the syncytiotrophoblast and endothelium in PE. Our results indicate a changed expression of fucosylated glycans in the glycocalyx of placental barrier structures and the morphometric parameters of villi in PE of different severity, which can affect the function of the placental barrier.

Expression of fucosylated glycans in endothelial glycocalyces of placental villi at early and late fetal growth restriction.

The aim of the study was to investigate the content and distribution of fucosylated sugar residues and Lewis Y (LeY) in the endothelial glycocalyx (eGC) in placental tissue at early and late onset fetal growth restriction (FGR). Our findings demonstrated that the changes of the fucosylated glycans of type 2 (H2)/LeY in the vascular endothelium of the villi may reflect alteration of villi maturation, or adaptation to hypoxia through the change of cell proliferation potential and induction angiogenesis. Early onset FGR differs from late onset FGR by a markedly increased LeY expression, being associated with more severe pathological state.

Isolation of IgG Associated with Human Placenta.

We optimized the method of isolation of antibodies from placental tissue of a conventionally healthy patient. Four protocols of antibody isolation were evaluated and a protocol with tissue grinding (without homogenization) and successive elution of the antibodies with acidic and alkaline buffers was recommended for use. The repertoire of the isolated antibodies was characterized using a glycan array. Partial coincidence of the specificity of the isolated antibodies with antibodies in the peripheral blood was demonstrated, which indicates their possible association with carbohydrate antigens in the placenta. Identification of potential molecular targets of resident antibodies in the placenta is necessary for understanding the mechanisms of formation of immunological tolerance to the fetus.

Hyaluronic Acid in Vascular and Immune Homeostasis during Normal Pregnancy and Preeclampsia.

Preeclampsia (PE) is a multisystem pathologic state that clinically manifests itself after the 20th week of pregnancy. It is characterized by high maternal and perinatal morbidity and mortality. According to modern concepts, the impairment of trophoblast invasion into maternal spiral arteries, leading to the development of ischemia in placenta, is considered to be the major pathogenetic factor of PE development. Ischemic lesions initiate the development of a systemic inflammatory response (SIR) and endothelial dysfunction, which is the main cause of the multiple organ failure in PE. Some data has appear indicating the importance of a glycans-forming endothelial glycocalyx and extracellular matrix (ECM) for placenta morphogenesis, as well as their role in the regulation of vascular permeability and vascular tone in hypertension disorders and, in particular, PE. Since intact glycocalyx and ECM are considered to be the major factors that maintain the physiological vascular tone and adequate intercellular interactions, their value in PE pathogenesis is underestimated. This review is focused on hyaluronic acid (HA) as the key glycan providing the organization and stabilization of the ECM and glycocalyx, its distribution in tissues in the case of presence or absence of placental pathology, as well as on the regulatory function of hyaluronic acids of various molecular weights in different physiological and pathophysiological processes. The summarized data will provide a better understanding of the PE pathogenesis, with the main focus on glycopathology.

Differences of glycocalyx composition in the structural elements of placenta in preeclampsia.

INTRODUCTION: Glycans expressed in the fetal-maternal interface were shown to exert immunomodulating effects and to mediate interactions between the cells. The aim of this study was to investigate alterations in the structure of carbohydrate chains of glycocalyx in placental tissue in pregnancies complicated with preeclampsia (PE). METHODS: A histochemical analysis of placental tissues was performed with a panel of biotinylated lectins. We analyzed placental tissues in women who had severe or moderate PE and compared them to placentas from women with normal pregnancies. RESULTS: There was decreased content of terminal residues of α(2,6)-linked sialic acid (as stained by SNA lectin) in the carbohydrate chains of glycocalyx of the endothelium of placental terminal villi in patients with moderate preeclampsia. The composition of the glycocalyx of syncytiotrophoblast in patients of this group did not differ from the control group. Amount of the glycans with terminal ß-Gal- (ECL) and α-mannosyl residues (ConA) in the syncytiotrophoblast and capillary endothelium of the placenta was significantly higher in the group with severe PE compared to the control group. The increased content of sialoglycans with α(2,6)-linked sialic acids residues were discovered in the syncytium, and the decreased content of α(2,3)-linked sialic acids residues - in the endothelium of terminal villi in preeclampsia. DISCUSSION: The most prominent alteration of the glycocalyx composition was found in the placentas of women with severe preeclampsia. It is likely that the modified glycome of syncytiotrophoblast and capillary endothelium may play an important role in pathogenesis of preeclampsia.

Detection of Antibodies In Vitro Binding to Endothelial Cells in the Sera from Women with Normal Pregnancy and Preeclampsia.

Activity of serum antibodies in vitro binding to endothelial cells in women with normal pregnancy and preeclampsia was studied. Flow cytometry detected peculiarities of antibody binding to endothelial cells in health and disease. Detection of antiendothelial antibodies in trimesters II and III can be diagnostically important in preeclampsia.

Time course of the cytokine profiles during the early period of normal pregnancy and in patients with a history of habitual miscarriage.

The time course of the peripheral blood cytokine profiles was studied in patients with a history of habitual miscarriages and in normal gestation. Low levels of anti-inflammatory cytokines during the early periods of gestation were characteristic of patients with a history of habitual miscarriages; however, an anti-inflammatory shift of the cytokine spectrum developed by the end of the first trimester.

Optimal detection of serum antipaternal antileukocytic antibodies after injection of allogenic lymphocytes in women with habitual abortions.

The level of antipaternal antileukocytic antibodies detected by flow cytometry is a parameter reflecting the efficiency of alloimmunization of women with reproductive disorders during preparation to pregnancy. The results of evaluation of antipaternal antileukocytic antibodies by two modifications of the method are presented. The optimal method for detection of antipaternal antileukocytic antibodies after immunocytotherapy is selected.

The significance of angiogenic growth factor in the pathogenesis of gestosis in pregnant women with varicose disease.

Recently, a close relationship between angiogenesis processes, growth factor activity in vascular abnormalities, and gestosis was revealed. In the present study, the dynamics of serum vascular endothelial growth factor during pregnancy was studied in patients with varicose disease with and without gestosis and in healthy women. The level of vascular endothelial growth factor increased during normal pregnancy, but decreased in gestosis. In pregnant patients with varicose disease, a less pronounced increase in this parameter was observed in comparison with that in healthy women.