Immunization of naïve mice with mouse laminin-1 affected pregnancy outcome in a mouse model

Basement membranes and autoimmune diseases

Basement membrane components are targets of autoimmune attack in diverse diseases that destroy kidneys, lungs, skin, mucous membranes, joints, and other organs in man. Epitopes on collagen and laminin, in particular, are targeted by autoantibodies and T cells in anti-glomerular basement membrane glomerulonephritis, Goodpasture's disease, rheumatoid arthritis, post-lung transplant bronchiolitis obliterans syndrome, and multiple autoimmune dermatoses. This review examines major diseases linked to basement membrane autoreactivity, with a focus on investigations in patients and animal models that advance our understanding of disease pathogenesis. Autoimmunity to glomerular basement membrane type IV is discussed in depth as a prototypic organ-specific autoimmune disease yielding novel insights into the complexity of anti-basement membrane immunity and the roles of genetic and environmental susceptibility.

Autoimmunity against laminins

Laminins are ubiquitous constituents of the basement membranes with major architectural and functional role as supported by the fact that absence or mutations of laminins lead to either lethal or severely impairing phenotypes. Besides genetic defects, laminins are involved in a wide range of human diseases including cancer, infections, and inflammatory diseases, as well as autoimmune disorders. A growing body of evidence implicates several laminin chains as autoantigens in blistering skin diseases, collagenoses, vasculitis, or post-infectious autoimmunity. The current paper reviews the existing knowledge on autoimmunity against laminins referring to both experimental and clinical data, and on therapeutic implications of anti-laminin antibodies. Further investigation of relevant laminin epitopes in pathogenic autoimmunity would facilitate the development of appropriate diagnostic tools for thorough characterization of patients' antibody specificities and should decisively contribute to designing more specific therapeutic interventions.

Autoantibodies associated with reproductive failure

Autoimmune factors are involved in some of the cases of reproductive failure. These factors entail several autoantibodies, especially in patients having systemic lupus erythematosus (SLE) or the antiphospholipid syndrome (APS). These autoantibodies include mainly antibodies directed to phospholipid such as cardiolipin, phosphatidylserine, phosphatidylethanolamine or phospholipids binding glycoproteins such as b2glycoprotein-I, annexin V, prothrombin and protein-Z. There are also some other autoantibodies directed to laminin-I, thromboplastin, mitochondrial antibodies of the M5 type, corpus luteum, prolactin, poly (ADP-ribose), thyroglobulin and more, which were also found in SLE or APS patients with reproductive failure. Moreover, the presence of additional autoantibodies directed to actin, enolase, cubilin and others, needs further investigation to support a firm association to reproductive failure in women. Future studies are likely to help to determine and expand the number of autoantibodies screened in these patients, as well as by the use of proteomics technology, to determine peptides resembling the epitope specificities associated with the specific clinical manifestations.

Anti-laminin-1 antibodies in serum and follicular fluid of women with Hashimoto's thyroiditis undergoing in vitro fertilization

The aim of this study is to evaluate the presence of anti-laminin-1 antibodies (aLN-1) in sera and follicular fluid (FF) of infertile women affected by Hashimoto's thyroiditis (HT) undergoing in vitro fertilization (IVF) and its impact on oocyte maturation and IVF outcome. aLN-1 were measured by a home-made enzyme linked immunosorbent assay (ELISA) in: (1) sera and FF from 44 infertile women affected by HT (HTIW) with tubal factor or male factor as primary cause of infertility; (2) in sera and FF from 28 infertile women without HT, with tubal factor or male factor as cause of infertility (infertile controls-ICTR); and (3) in sera from 50 fertile women (FW). aLN-1 serum levels were significantly higher in HTIW when compared with both fertile women and ICTR (P <0.001and P <0.01, respectively). Assuming as cutoff the 99th percentile of values obtained in sera of FW, 43.2% of HTIW and 3.6% of ICTR were aLN-1 positive (P = 0.0001). Also aLN-1 detected in FF from HTIW were significantly higher in comparison with those found in FF of ICTR (P = 0.006). In HTIW, metaphase II oocyte count showed inverse correlation with both serum and FF aLN-1 levels (r = 0.34, P = 0.02 and r = 0.33, P = 0.03, respectively). Implantation and pregnancy rates were significantly lower in HTIW (7.9% and 9.1%, respectively) when compared with ICTR (23% and 31.1%, respectively) (P = 0.015 and P = 0.03, respectively). Our results demonstrated for the first time the presence of aLN-1 in a relevant percentage of HTIW and suggest that these auto-antibodies may impair IVF outcome.

Ex vivo pathogenicity of anti-laminin γ1 autoantibodies

Autoimmunity against laminins has been described in several autoimmune diseases (including mucous membrane pemphigoid, anti-laminin γ1 pemphigoid, and connective tissue diseases), in pregnancy loss, and in infections such as Chagas disease. Except for anti-laminin-332 mucous membrane pemphigoid, adequate evidence has been lacking for the tissue injury potential of laminin-specific antibodies and the pathogenic epitopes. We evaluated the pathogenic potential of antibodies targeting laminin γ1, a major constituent of basement membranes and the main antigen in anti-laminin γ1 pemphigoid. Rabbit antibodies were generated against fragments of the N-terminus and C-terminus of murine laminin γ1, and their ability to disrupt ligand interactions and/or to activate complement and granulocytes was assessed using previously established ex vivo assays. Our findings document a pathogenic potential of antibodies targeting the laminin γ1 N-terminus. These antibodies interfere with the binding of nidogen to laminin and can activate granulocytes and the complement cascade. We detected antibodies with different degrees of reactivity with laminin γ1 N-terminus in patients with anti-laminin γ1 pemphigoid, cutaneous lupus erythematosus, and scleroderma. Our results provide mechanistic insights into the tissue damage associated with laminin autoimmunity and could facilitate development of appropriate diagnostic tools and therapeutic strategies.

Anti-laminin-1 antibodies in sera and follicular fluid of women with endometriosis undergoing in vitro fertilization

There is increasing evidence that autoimmune phenomena, including auto-antibody production, may affect fertility in women with endometriosis. The aims of this study are to evaluate anti-laminin-1 antibody (aLN-1) presence in sera and in follicular fluids (FF) of women with endometriosis undergoing IVF and its impact on oocyte maturation and IVF outcome. aLN-1 were measured by a home-made enzyme linked immunosorbent assay in sera and FF obtained from 35 infertile women with endometriosis and in sera from 50 fertile controls and 27 infertile women without endometriosis (IWWE). aLN-1 serum levels were significantly higher in women with endometriosis in comparison with both fertile controls and IWWE (P<0.001 and P<0.05, respectively) and a positive correlation was found between serum- and FF-aLN-1 (r=0.47, P=0.004). According to the cut-off (mean+3 SD of fertile controls), 31% of women with endometriosis were aLN-1 positive. Metaphase II oocyte counts showed inverse correlation with FF-aLN-1 levels (r=-0.549, P=0.0006). Ongoing pregnancy (i.e pregnancy progressing beyond the 12th week of gestation) occurred in 4/11 aLN-1 positive patients and in 7/24 aLN-1 negative with no significant difference (P=0.7). In conclusion, our results highlight that aLN-1 are increased in women with endometriosis and their presence in FF may affect oocyte maturation leading to a reduced fertility. However, aLN-1 seem to have no effect on IVF outcome.

Antinuclear autoantibodies in women with recurrent pregnancy loss

PROBLEM

To investigate the possibility that antinuclear antibodies (ANA) are involved in recurrent pregnancy loss (RPL).

METHODS

Case-control study carried out on 294 women (194 cases and 100 controls) in two University hospitals. The presence, the serum titers and the indirect immunofluorescence (IIF) patterns of ANA were determined in women with RPL and in control women.

RESULTS

Antinuclear antibodies at titers ≥ 1:80 were detected in 97 (50%) women with RPL and in 16 (16%) control women. Elevated ANA titers (≥1:180) were detected only in RPL women, whereas all control women had ANA titers no greater than 1:80. No differences could be detected in the IIF patterns between RPL and control women. No differences in ANA positivity could be detected according to the type (primary or secondary) or number (>2 versus ≥3) of losses.

CONCLUSIONS

ANA could be of some value in identifying women with RPL with potential, although still not fully defined, immune abnormalities.

A possible mechanism of autoimmune-mediated infertility in women with endometriosis

PROBLEM

Endometriosis has been proposed to be an autoimmune disease because of the presence of a variety of autoantibodies specific for endometrial or ovarian antigens. The object of the present study is to characterize binding specificity of anti-laminin-111 autoantibodies in infertile patients with endometriosis and to investigate whether these autoantibodies affect the in vitro embryo development.

METHOD OF STUDY

An ELISA analysis using overlapping synthesized peptides that covered the entire G domain of laminin-α1 chain was performed in infertile patients with endometriosis (n = 45). Mouse blastocysts were cultured in media containing the purified IgG from one antibody-positive serum on laminin-111-coated dishes.

RESULTS

Anti-laminin-111 autoantibodies were directed to several particular biologically functional peptide sequences in laminin-α 1 chain G domain. The tested IgG significantly inhibited the extent of in vitro trophoblast outgrowth.

CONCLUSION

Anti-laminin-111 autoantibodies may have major pathogenic roles on early reproductive failure including endometriosis-associated infertility.

Valproic acid increases expression of methylenetetrahydrofolate reductase (MTHFR) and induces lower teratogenicity in MTHFR deficiency

Valproate (VPA) treatment in pregnancy leads to congenital anomalies, possibly by disrupting folate or homocysteine metabolism. Since methylenetetrahydrofolate reductase (MTHFR) is a key enzyme of folate interconversion and homocysteine metabolism, we addressed the possibility that VPA might have different teratogenicity in Mthfr(+/+) and Mthfr(+/-) mice and that VPA might interfere with folate metabolism through MTHFR modulation. Mthfr(+/+) and Mthfr(+/-) pregnant mice were injected with VPA on gestational day 8.5; resorption rates and occurrence of neural tube defects (NTDs) were examined on gestational day 14.5. We also examined the effects of VPA on MTHFR expression in HepG2 cells and on MTHFR activity and homocysteine levels in mice. Mthfr(+/+) mice had increased resorption rates (36%) after VPA treatment, compared to saline treatment (10%), whereas resorption rates were similar in Mthfr(+/-) mice with the two treatments (25-27%). NTDs were only observed in one group (VPA-treated Mthfr(+/+)). In HepG2 cells, VPA increased MTHFR promoter activity and MTHFR mRNA and protein (2.5- and 3.7-fold, respectively). Consistent with cellular MTHFR upregulation by VPA, brain MTHFR enzyme activity was increased and plasma homocysteine was decreased in VPA-treated pregnant mice compared to saline-treated animals. These results underscore the importance of folate interconversion in VPA-induced teratogenicity, since VPA increases MTHFR expression and has lower teratogenic potential in MTHFR deficiency.

Placental thrombosis in experimental anticardiolipin antibodies-mediated intrauterine fetal death

PROBLEM

Anticardiolipin (aCL) antibodies are associated with stillbirths, recurrent miscarriages and recurrent in vitro fertilization implantation failure in women. Previous animal studies have demonstrated that these antibodies can cause early fetal demise and implantation failure in mice, but most previous studies have not allowed the immunized mice to proceed to the full term of gestation.

METHOD OF STUDY

Mice were immunized with either cardiolipin alone or cardiolipin in combination with beta2-glycoprotein I (beta2GPI) and have studied the effects of these antibodies on pregnancies which were allowed to progress to term.

RESULTS

Immunization with cardiolipin alone induced significant levels of anticardiolipin antibodies in mice, but immunization with a combination of cardiolipin and beta2GPI produced even higher levels of antibodies. Mice with elevated levels of anticardiolipin antibodies had poor pregnancy outcomes. This study confirms previous results that anticardiolipin antibodies cause early pregnancy losses and also demonstrates that these antibodies cause stillbirth-like late fetal demise. This study further demonstrated that very high levels of anticardiolipin antibodies cause intrauterine death by facilitating the thrombotic episode in placenta.

CONCLUSIONS

The present study concludes that the possible mechanism involves in stillbirth of aCL is possibly because of the thrombotic events of placenta.

Predicting and preventing autoimmunity, myth or reality?

Many autoimmune diseases are chronic conditions that progress over the course of years, and are characterized by the presence of autoantibodies that precede the overt disease by months or years. As examples, the presence of two islet cell antibodies (ICA) are associated with a 50% risk of developing diabetes mellitus in 5 years, anticyclic citrullinated (anti-CCP) antibodies are found in the sera of rheumatoid arthritis (RA) patients a median of 4.5 years before the overt disease, and in systemic lupus erythematosus (SLE), patients accrue antibodies throughout a foreseen course during the 3-4 years prior to the clinical symptoms. This ability to predict autoimmune diseases, or rather their clinical manifestations, leads to the prospect of screening healthy individuals for autoantibodies. The importance of such a notion lies not only in the ability to prevent life-threatening manifestations, such as Addisonian's crisis and thyroid storm, but also in the ability to treat and even prevent overt autoimmune diseases. Among such documented treatment modalities are administration of aspirin in antiphospholipid syndrome, ursodeoxycholic acid in primary biliary cirrhosis (PBC), vitamin D in SLE and autoimmune thyroid diseases (AITD), and more. Although additional studies are still needed to fully assess these notions, as well as the appropriate screening strategies to apply them, one cannot ignore the prospect of predicting and preventing autoimmunity.

Pregnancy loss and endometriosis: pathogenic role of anti-laminin-1 autoantibodies

Laminin-1 is a major multifunctional glycoprotein that forms an integral part of the scaffolding network of basement membranes, and is the earliest synthesized component during embryogenesis. This protein (alpha1beta1gamma1) plays an important role in basement membrane assembly and epiblast differentiation during embryonic development. Anti-laminin-1 autoantibodies are known to cause infertility and recurrent spontaneous abortion in animals. Recently, we reported that the presence of IgG anti-laminin-1 antibodies (Abs) in the blood is significantly associated with recurrent first-trimester miscarriages and subsequent negative pregnancy outcomes. Interestingly, these antibodies are also strongly associated with infertility, especially infertility caused by endometriosis. Laminin-alpha1, laminin-beta1, and laminin-gamma1 mRNAs were also detected in 90% of endometriotic lesions, and all laminin-alpha1, laminin-beta1, and laminin-gamma1 chains were localized to the basement membranes of glandular epithelium in endometriotic peritoneal lesions. ELISA showed specific reactivity of the autoantibodies to a particular region of the laminin-1 molecule, that is, the alpha1 chain G domain. IgM monoclonal anti-laminin-1 Abs, which we recently established, also recognized the G domain and cross-reacted with human alpha1 chain located in the basement membrane of the glandular epithelium of human endometrium. We also established an animal model that produced high titers of anti-laminin-1 Abs after immunization with mouse laminin-1. Anti-laminin-1 Abs from the immunized mice caused a higher fetal resorption rate with lower embryonic and placental weights. Thus, anti-laminin-1 Abs may be important in the development of autoimmune-mediated reproductive failures, and the assessment of the such antibodies may provide a novel means for noninvasive diagnosis of endometriosis.

Maternal methylenetetrahydrofolate reductase deficiency and low dietary folate lead to adverse reproductive outcomes and congenital heart defects in mice

BACKGROUND

Genetic or nutritional disturbances in folate metabolism may affect embryonic development because of the critical role of folate in nucleotide synthesis and methylation reactions. The possible role of a mild deficiency in methylenetetrahydrofolate reductase (MTHFR) and low dietary folate in pregnancy outcomes and heart morphogenesis requires further investigation.

OBJECTIVE

We investigated the effect of mild MTHFR deficiency, low dietary folate, or both on resorption rates, on length and weight, and on the incidence of heart malformations in murine embryos.

DESIGN

Female Mthfr +/+ and +/- mice were fed a control diet (CD) or a folic acid-deficient diet (FADD) before mating with male Mthfr +/- mice. On gestational day 14.5, implantation and resorption sites were recorded and viable embryos were examined for gross malformations, growth delay, and congenital heart defects.

RESULTS

Plasma homocysteine in Mthfr +/- dams and in FADD-treated dams was significantly higher than that in Mthfr +/+ dams and CD-treated dams, respectively. A significantly higher rate of resorption and greater developmental delay were observed in hyperhomocysteinemic mice than in CD-treated +/+ dams. Heart defects were identified in 4 of 11, 5 of 10, and 4 of 10 litters from CD-treated +/-, FADD-treated +/+, and FADD-treated +/- dams, respectively, but not in any of those from CD-treated +/+ dams (0/11 litters).

CONCLUSION

Our findings suggest that mild MTHFR deficiency, low dietary folate, or both in the dams increase the incidence of fetal loss, intrauterine growth retardation, and heart defects. These data support the benefit of folic acid supplementation in pregnant women, particularly in those with MTHFR deficiency.