Autoreactive epitopes within the human alpha-enolase and their recognition by sera from patients with endometriosis

Determination of the Predictive Roles and Potentially Pathogenic Antigen Epitopes of α-Enolase Related to the Development of Miscarriage in Females with Autoimmune Thyroiditis

Autoimmune thyroiditis (AIT) is a common endocrine disease which causes a significantly increased risk of miscarriage. Our recent study has shown that the increased ENO1 autoantibody (ENO1Ab) expression in an experimental AIT mouse model was induced by thyroglobulin (Tg) immunization only. In this study, we explored the potential roles of ENO1Ab in miscarriage occurrence among AIT women, and the specific epitopes of ENO1 targeted by ENO1Ab. A total of 432 euthyroid pregnant participants were selected from the project of Subclinical Hypothyroid during Early Pregnancy, including 48 women with AIT and miscarriage, 96 with miscarriage but no AIT, 96 with AIT but no miscarriage, and 192 without either AIT or miscarriage. The enzyme-linked immunosorbent assay was used to determine the serum levels of total IgG against ENO1 and 18 predicted antigen epitopes of ENO1. The results showed that women with AIT and miscarriage had the highest serum levels of ENO1Ab compared to the other groups. Logistic regression analysis showed that the serum ENO1Ab was an independent risk factor for miscarriage, especially among AIT females. The serum level of total IgG against the predicted epitope peptide 6 (i.e., P6 and aa168-183) of ENO1 was significantly increased in women with AIT and miscarriage when compared with those of both the AIT non-miscarriage group and non-AIT miscarriage group. This pilot study suggests that serum ENO1Ab may have a fair predictive value for AIT-related miscarriage, and the autoantibody specific to P6 epitope may especially be more specifically related to this disorder.

Non-invasive diagnosis of endometriosis: Immunologic and genetic markers

Endometriosis, a benign gynecologic and chronic inflammatory disease, is defined by the presence of endometrial tissue outside the uterus characterized mainly by pelvic pain and infertility. Because endometriosis affects approximately 10% of females, it represents a significant socioeconomic burden worldwide having tremendous impact on daily quality of life. Accurate and prompt diagnosis is crucial for the management of this debilitating disorder. Unfortunately, diagnosis is typically delayed to lack of specific symptoms and readily accessible biomarkers. Although histopathologic examination remains the current gold standard, this approach is highly invasive and not applicable for early screening. Recent work has focused on the identification of reliable biomarkers including immunologic, ie, immune cells, antibodies and cytokines, as well as genetic and biochemical markers, ie, microRNAs, lncRNAs, circulating and mitochondrial nucleic acids, along with some hormones, glycoproteins and signaling molecules. Confirmatory research studies are, however, needed to more fully establish these markers in the diagnosis, progression and staging of these endometrial lesions.

A Predictive Role of Autoantibodies Against the Epitope aa168–183 of ENO1 in the Occurrence of Miscarriage Related to Thyroid Autoimmunity

Objective

The aim of the research is to study the association between the serum levels of autoantibodies against one important epitope (¹⁶⁸FMILPVGAANFREAMR¹⁸³, designated as P6) of α-enolase (ENO1-P6Abs) and miscarriage among euthyroid females with thyroid autoimmunity (TAI).

Methods

Anti-ENO1-P6 total IgG was investigated in 432 euthyroid women, and its four subclasses were analyzed in 184 euthyroid women. The serum FT4, TSH, TgAb, and TPOAb levels were determined using an electrochemiluminescence immunoassay. The serum ENO1-P6Ab and anti-protein disulfide isomerase A3 autoantibody (PDIA3Ab) levels were determined using an enzyme-linked immunosorbent assay.

Results

The serum levels of anti-ENO1-P6 total IgG, IgG2, IgG3, and IgG4 were significantly higher in euthyroid TAI females than in non-TAI controls. Additionally, anti-ENO1-P6 total IgG and its 4 subtypes were all markedly higher in euthyroid TAI females with pregnancy loss than those without miscarriage. Moreover, logistic regression analysis showed that highly expressed anti-ENO1-P6 total IgG, IgG1, IgG2, and IgG3 subtypes in the serum were all independent risk factors for euthyroid TAI-related miscarriage, and its IgG1 was also for non-TAI-related abortion. According to the trend test, the prevalence of miscarriage was increased in a titer-dependent manner with the raised levels of serum anti-ENO1-P6 total IgG and IgG1, IgG2, and IgG3 subtypes among euthyroid TAI females. The receiver operating characteristic curve analysis of anti-ENO1-P6 total IgG and IgG1, IgG2, and IgG3 subclass expressions in the serum for miscarriage prediction in euthyroid TAI females exhibited that the total areas under the curves were 0.773 ± 0.041, 0.761 ± 0.053, 0.827 ± 0.043, and 0.760 ± 0.050, respectively (all P <0.0001). Their corresponding optimal cut-off OD450 values were 0.68 (total IgG), 0.26 (IgG1), 0.97 (IgG2), and 0.48 (IgG3), with sensitivities of 70.8, 87.5, 83.3, and 85.4%, and specificities of 70.8, 59.1, 77.3, and 56.8%, respectively. There was an additive interaction between serum anti-ENO1-P6 and anti-PDIA3 total IgGs on the development of miscarriage (RERI = 23.6, AP = 0.79, SI = 5.37).

Conclusion

The highly expressed ENO1-P6Abs may be important risk factors for euthyroid TAI-related miscarriage. The serum levels of ENO1-P6Abs may become good predictive markers for pregnancy loss in euthyroid TAI females, especially its IgG2 subclass expression.

Urinary Biomarkers for Detection of Clinical Endometriosis or Adenomyosis

Endometriosis or adenomyosis can be clinically diagnosed by ultrasound, symptoms, physical examination, and serum CA125. The urinary markers need to be investigated. The aim of our study was to investigate the urinary markers of clinical endometriosis/adenomyosis, and the correlation of serum CA125 was also studied. From the literature, alpha-1 antitrypsin (A1AT), enolase-1, vitamin D binding protein (VDBP), and CA125 in urine and serum were used in our study and measured by enzyme-linked immunosorbent assays (ELISA). Further clinical correlation and detection performance were evaluated. We enrolled 19 normal controls and 33 patients clinically diagnosed with endometriosis/adenomyosis. There were significant differences between studied patients and normal controls, as follows: serum CA125 (130.91 vs. 19.75 U/mL, p = 0.004); urinary CA125-creatinine ratio (5.591 vs. 0.254 ng/mg, p = 0.028); and urinary VDBP-creatinine ratio (28.028 vs. 7.301 ng/mg, p = 0.018). For diagnostic performances, serum CA125 provided the best results, with an area under curve (AUC) of 0.888 (p = 0.001) and accuracy of 86.5%. Other excellent results were also found using urinary VDBP (AUC 0.841, p = 0.001) and A1AT (AUC 0.722, p = 0.011) creatinine ratio. Using three combined biomarkers, serum CA125, urinary VDBP, and A1AT creatinine ratio, provided good detection power (AUC 0.913, p = 0.001, sensitivity 90.9%, specificity 76.5%). Double urine markers used in combination with VDBP and A1AT creatinine ratio also provided good diagnostic performance (AUC 0.809, p = 0.001, sensitivity 81.8%, specificity 76.5%, accuracy 80%). Further development of non-invasive point-of-care tests using these biomarkers could be a fruitful future endeavor.

Amoxicillin Haptenation of α-Enolase is Modulated by Active Site Occupancy and Acetylation

Allergic reactions to antibiotics are a major concern in the clinic. ß-lactam antibiotics are the class most frequently reported to cause hypersensitivity reactions. One of the mechanisms involved in this outcome is the modification of proteins by covalent binding of the drug (haptenation). Hence, interest in identifying the corresponding serum and cellular protein targets arises. Importantly, haptenation susceptibility and extent can be modulated by the context, including factors affecting protein conformation or the occurrence of other posttranslational modifications. We previously identified the glycolytic enzyme α-enolase as a target for haptenation by amoxicillin, both in cells and in the extracellular milieu. Here, we performed an in vitro study to analyze amoxicillin haptenation of α-enolase using gel-based and activity assays. Moreover, the possible interplay or interference between amoxicillin haptenation and acetylation of α-enolase was studied in 1D- and 2D-gels that showed decreased haptenation and displacement of the haptenation signal to lower pI spots after chemical acetylation of the protein, respectively. In addition, the peptide containing lysine 239 was identified by mass spectrometry as the amoxicillin target sequence on α-enolase, thus suggesting a selective haptenation under our conditions. The putative amoxicillin binding site and the surrounding interactions were investigated using the α-enolase crystal structure and molecular docking. Altogether, the results obtained provide the basis for the design of novel diagnostic tools or approaches in the study of amoxicillin-induced allergic reactions.

Anti-alpha enolase multi-antibody specificity in human diseases. Clinical significance and molecular mechanisms

Alpha-enolase (Eno) is an ubiquitary glycolytic enzyme playing multiple functions that go well beyond its principal metabolic role of energy supplier during glycolysis. Eno is localized in the cytoplasm, but also expressed on the cell membrane, where it binds plasminogen allowing its activation. Its shorter form, in the nucleus, acts as transcription factor. In inflammatory conditions, Eno undergoes post-translational modifications, such as citrullination, oxidation and phosphorylation. Eno is also an autoantigen in different disorders. In fact, autoantibodies to Eno have been detected in rheumatoid arthritis, lupus nephritis, primary glomerulonephritis, cancer, infections and other disorders, and in many cases they represent specific markers to be utilized in clinical practice. Anti-Eno antibodies in the different clinical conditions are not equal: they differ in isotype and often recognize different epitopes on the enzyme. IgG1 and IgG3 are prevalent in Rheumatoid Arthritis, IgG2 in Lupus nephritis and IgG4 in primary autoimmune glomerulopathy. This review analyzes the characteristics of anti-Eno autoantibodies in autoimmune disorders and cancer, describing their fine specificity and isotype restriction. The post-translational modifications that are target of autoantibodies are also discussed, as they represent the basis for elucidating the molecular mechanisms responsible for epitope generation. Despite an impressive amount of experimental work on anti-Eno antibodies, it is still necessary to validate the use of anti-Eno antibodies as biomarkers of selected diseases and extend the knowledge on the mechanisms of anti-Eno autoantibody production. Strategies that downmodulate the immune response to Eno may represent in the future novel approaches in the treatment of autoimmune disorders.

Anti α-enolase antibody is a novel autoimmune biomarker for unexplained recurrent miscarriages

Background

We recently demonstrated the increased abundance of anti-trophoblast antibodies (ATAB) in sera of patients with unexplained recurrent miscarriages (uRM). Further, the ATAB-positive sera bound to JEG-3 human choriocarcinoma cells in vitro, resulting in decreased productions of β-human chorionic gonadotropin (β-hCG) and progesterone in these cells. However, the specific antigenic epitopes of ATAB have remained unknown. Therefore, it was the aim of this study to determine specific targets of ATAB in uRM patients.

Methods

Potential targets of ATAB were analyzed by 2-dimensional difference gel electrophoresis (2D-DIGE) and mass spectrometry, and thereby identifying α-Enolase (ENO1). ATAB targeting of ENO1 was further confirmed in a competitive binding assay. Levels of anti-ENO1 antibodies as well as β-hCG and progesterone were quantified with enzyme-linked immunosorbent assay (ELISA). Additionally, expression of ENO1 was analyzed in first trimester placentas by immunohistochemistry and immunofluorescence analysis.

Findings

We here identified ENO1 as a prominent target of ATAB. Serum levels of anti-ENO1 antibodies were increased in ATAB-positive compared to ATAB-negative patients. Further, increased expression of ENO1 and its co-expression with β-arrestin was found in the extra villous trophoblasts of uRM patients in first trimester placentas. In vitro, anti-ENO1 antibodies decreased the secretion of β-hCG and progesterone in JEG-3 and primary human villous trophoblast cells.

Interpretation

Serum anti-ENO1 antibodies might be an autoimmune biomarker for uRM. Targeting the formation of anti-ENO1 antibodies or inhibition of ENO1 expression could potentially represent therapeutic strategies for these patients.

Fund

All authors declare no conflict of interest. Yao Ye was supported by the China Scholarship Council. Hellen Ishikawa-Ankerhold and Christian Schulz were supported by the SFB914, projects Z01 and A10. None of the rest authors has any conflict of interest to declare.

Are Anti-Retinal Autoantibodies a Cause or a Consequence of Retinal Degeneration in Autoimmune Retinopathies?

Autoantibodies (AAbs) against various retinal proteins have been associated with vision loss in paraneoplastic and non-paraneoplastic autoimmune retinopathies (AR). There are two major paraneoplastic syndromes associated anti-retinal AAbs, cancer-associated retinopathy (CAR), and melanoma-associated retinopathy. Some people without a cancer diagnosis may present symptoms of CAR and have anti-retinal AAbs. The etiology and pathogenesis of those entities are not fully understood. In this review, we provide evidence for the role of AAbs in retinal death and degeneration. Studies of epitope mapping for anti-recoverin, anti-enolase, and anti-carbonic anhydrase II revealed that although patients' AAbs may recognize the same retinal protein as normal individuals they bind to different molecular domains, which allows distinguishing between normal and diseased AAbs. Given the great diversity of anti-retinal AAbs, it is likely some antibodies have greater pathogenic potential than others. Pathogenic, but not normal antibodies penetrate the target cell, reach their specific antigen, induce apoptosis, and impact retinal pathophysiology. Photoreceptors, dying by apoptosis, induced by other than immunologic mechanisms produce substantial amounts of metabolic debris, which consequently leads to autoimmunization and enhanced permeability of the blood-retinal barrier. AAbs that were made as a part of anti-cancer response are likely to be the cause of retinal degeneration, whereas others, generated against released antigens from damaged retina, contribute to the progression of retinopathy. Altogether, AAbs may trigger retinal degeneration and may also exacerbate the degenerative process in response to the release of sequestered antigens and influence disease progression.

Autoimmunity against a glycolytic enzyme as a possible cause for persistent symptoms in Lyme disease

Some patients with a history of Borrelia burgdorferi infection develop a chronic symptomatology characterized by cognitive deficits, fatigue, and pain, despite antibiotic treatment. The pathogenic mechanism that underlines this condition, referred to as post-treatment Lyme disease syndrome (PTLDS), is currently unknown. A debate exists about whether PTLDS is due to persistent infection or to post-infectious damages in the immune system and the nervous system. We present the case of a patient with evidence of exposure to Borrelia burgdorferi sl and a long history of debilitating fatigue, cognitive abnormalities and autonomic nervous system issues. The patient had a positive Western blot for anti-basal ganglia antibodies, and the autoantigen has been identified as γ enolase, the neuron-specific isoenzyme of the glycolytic enzyme enolase. Assuming Borrelia own surface exposed enolase as the source of this autoantibody, through a mechanism of molecular mimicry, and given the absence of sera reactivity to α enolase, a bioinformatical analysis was carried out to identify a possible cross-reactive conformational B cell epitope, shared by Borrelia enolase and γ enolase, but not by α enolase. Taken that evidence, we hypothesize that this autoantibody interferes with glycolysis in neuronal cells, as the physiological basis for chronic symptoms in at least some cases of PTLDS. Studies investigating on the anti-γ enolase and anti-Borrelia enolase antibodies in PTLDS are needed to confirm our hypotheses.

A comprehensive narrative review of diagnostic biomarkers in human primary membranous nephropathy

Membranous nephropathy (MN) is relatively major cause of nephrotic syndrome in adults which is recognized as an organ-specific autoimmune disease. The etiology of most cases is idiopathic, whereas the secondary MN is caused by systemic autoimmune diseases, infections, medications and malignancies. The idiopathic disease is developed by the formation of sub-epithelial immune complex deposits most likely due to binding the circulating auto-antibodies to intrinsic antigen on podocytes. The major auto antibody is the anti-phospholipase A2 receptor (anti-PLA2R), however, it is not enough sensitive. Several attempts for diagnostic biomarker identification by modern analytical technologies have been devoted recently. This article reviews the biomarker candidates for primary type of MN that are detected by different approaches on human subjects.

Impact of Autoantibodies against Glycolytic Enzymes on Pathogenicity of Autoimmune Retinopathy and Other Autoimmune Disorders

Autoantibodies (AAbs) against glycolytic enzymes: aldolase, α-enolase, glyceraldehyde-3-phosphate dehydrogenase, and pyruvate kinase are prevalent in sera of patients with blinding retinal diseases, such as paraneoplastic [cancer-associated retinopathy (CAR)] and non-paraneoplastic autoimmune retinopathies, as well as in many other autoimmune diseases. CAR is a degenerative disease of the retina characterized by sudden vision loss in patients with cancer and serum anti-retinal AAbs. In this review, we discuss the widespread serum presence of anti-glycolytic enzyme AAbs and their significance in autoimmune diseases. There are multiple mechanisms responsible for antibody generation, including the innate anti-microbial response, anti-tumor response, or autoimmune response against released self-antigens from damaged, inflamed tissue. AAbs against enolase, GADPH, and aldolase exist in a single patient in elevated titers, suggesting their participation in pathogenicity. The lack of restriction of AAbs to one disease may be related to an increased expression of glycolytic enzymes in various metabolically active tissues that triggers an autoimmune response and generation of AAbs with the same specificity in several chronic and autoimmune conditions. In CAR, the importance of serum anti-glycolytic enzyme AAbs had been previously dismissed, but the retina may be without pathological consequence until a failure of the blood–retinal barrier function, which would then allow pathogenic AAbs access to their retinal targets, ultimately leading to damaging effects.

Circulating antibodies to α-enolase and phospholipase A2 receptor and composition of glomerular deposits in Japanese patients with primary or secondary membranous nephropathy

Background

Phospholipase A₂ receptor (PLA₂R) is recognized as a target antigen in primary membranous nephropathy (MN); Anti-α-enolase antibody in primary and secondary MN has been proposed, however, little is known about the potential contribution of α-enolase to the pathogenesis of MN.

Methods

We evaluated circulating antibodies to α-enolase by a dot blotting system and PLA₂R by indirect immunofluorescence, and glomerular deposition of these proteins in 25 patients with primary MN, 20 patients with secondary MN, 44 patients with collagen disease or severe infection, 60 patients with nephritis (each ten patients of IgA nephropathy, focal segmental gloemrulosclerosis, minimal change nephrotic syndrome, membranoproliferative glomeurlonephritis, diabetic glomerulosclerosis, and tubulointerstitial nephritis) as disease control, and 20 healthy subjects.

Results

In primary MN, 18 of 25 sera (72 %) showed anti-α-enolase antibody (IgG1 and IgG4, 11 pts; IgG4 alone, six pts; IgG1 alone, one pt). In secondary MN, 15 of 20 sera (75 %) contained anti-α-enolase antibody (IgG1 and IgG3, 13 pts; IgG3 alone, two pts). No circulating anti-α-enolase antibody was found in 44 collagen diseases or septic patients, 60 nephritis without MN, and 20 healthy subjects. Twelve of 25 sera (48 %) from patients with primary MN were positive for anti-PLA₂R antibody, whereas all patients with secondary MN were negative. Eight of the 12 PLA₂R-positive patients (67 %) with primary MN also had anti α-enolase antibody. Although PLA₂R antigen was present in a subepithelial pattern in 10 of 19 (52 %) patients with primary MN, α-enolase was never detected in glomerular deposits in 19 and ten patients with primary and secondary MN, respectively.

Conclusions

Circulating anti-α-enolase antibodies are highly present in both primary and secondary MN (about 70 %, respectively), while anti-PLA₂R antibodies are specific for primary MN (48 %) with a prevalence apparently lower in the Japanese population than in Chinese and Caucasian populations. The absence of α-enolase from subepithelial immune deposits suggests that anti-α-enolase antibodies do not contribute directly to immune-deposit formation, although they may have other pathogenic effects.

Electronic supplementary material

The online version of this article (doi:10.1007/s10157-016-1235-2) contains supplementary material, which is available to authorized users.

Influence of pathogenic bacteria species present in the postpartum bovine uterus on proteome profiles

In the first 2-3 weeks after parturition >90% of dairy cows will have some form of uterine infection. Uterine contamination with pathogens, such as Trueperella (formerly Arcanobacterium) pyogenes increases the risk of developing more severe endometritis, which can reduce conception rates. In this study, we compared the uterine proteome of cows infected with Trueperella pyogenes with that of uninfected cows, using 2D gel electrophoresis, and identified annexins A1 and A2 (ANXA1 and ANXA2), apolipoprotein A-1, calprotectin (S100A9), cathelicidin, enolase 1 (ENO1), peptidoglycan recognition protein 1 (PGLYRP1), phosphoglycerate mutase 1 (PGAM1), serine dehydratase (SDS) and serine protease inhibitors (SERPIN) B1, B3 and B4 proteins as differing in abundance in endometritis. Subsequently, levels of ten of these proteins were monitored in uterine samples collected from a herd of lactating, dairy cows at 15 and 42 days post-partum (DPP). The levels were compared with the cytology scores of the samples and the bacterial species isolated from the uterus. Cathelicidin, PGLYRP1, SERPINB1 and S100A9 levels at 15DPP showed strong positive correlations (r=0.78, 0.80, 0.79, and 0.68 respectively; P<0.001) with % of polymorphonuclear neutrophils (PMN). When compared with other bacterial pathogens identified, Streptococcus agalactiae and Truperella pyogenes induced increased expression of the indicator proteins, suggesting that these organisms may adversely affect the subsequent ability of the cow to conceive. Interestingly, there was no difference in the proportion of cows pregnant at 6 and 17 weeks after start of mating between the cows with high or low %PMN.

Evaluation of elevated urinary enolase I levels in patients with endometriosis

OBJECTIVE

The aim of this study is to validate and investigate the clinical value of urinary enolase I in patients with endometriosis.

METHODS

Urine samples of 39 patients with histologically confirmed endometriosis and 20 patients without endometriosis were collected. Western blot analysis and enzyme-linked immunosorbent assay were used to detect the increase of enolase I in patients' urine.

RESULTS

Urinary enolase I expression corrected for creatinine ratio (non neuronal enolase (NNE)-Cr) was significantly greater in patients with endometriosis (p = 0.026). When the diagnostic performance of NNE-Cr was evaluated with serum CA-125 combination, the area under the curve was 0.821 (95% confidence interval 0.713-0.928) with sensitivity and specificity of 76.9% and 85.0%, respectively.

CONCLUSION

Elevated urinary enolase I, in conjunction with serum CA-125, may be used as a potential biomarker for endometriosis.

Identification of novel therapeutic targets in microdissected clear cell ovarian cancers

Clear cell ovarian cancer is an epithelial ovarian cancer histotype that is less responsive to chemotherapy and carries poorer prognosis than serous and endometrioid histotypes. Despite this, patients with these tumors are treated in a similar fashion as all other ovarian cancers. Previous genomic analysis has suggested that clear cell cancers represent a unique tumor subtype. Here we generated the first whole genomic expression profiling using epithelial component of clear cell ovarian cancers and normal ovarian surface specimens isolated by laser capture microdissection. All the arrays were analyzed using BRB ArrayTools and PathwayStudio software to identify the signaling pathways. Identified pathways validated using serous, clear cell cancer cell lines and RNAi technology. In vivo validations carried out using an orthotopic mouse model and liposomal encapsulated siRNA. Patient-derived clear cell and serous ovarian tumors were grafted under the renal capsule of NOD-SCID mice to evaluate the therapeutic potential of the identified pathway. We identified major activated pathways in clear cells involving in hypoxic cell growth, angiogenesis, and glucose metabolism not seen in other histotypes. Knockdown of key genes in these pathways sensitized clear cell ovarian cancer cell lines to hypoxia/glucose deprivation. In vivo experiments using patient derived tumors demonstrate that clear cell tumors are exquisitely sensitive to antiangiogenesis therapy (i.e. sunitinib) compared with serous tumors. We generated a histotype specific, gene signature associated with clear cell ovarian cancer which identifies important activated pathways critical for their clinicopathologic characteristics. These results provide a rational basis for a radically different treatment for ovarian clear cell patients.

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.

Serum anti-endometrial antibodies in infertile women - potential risk factor for implantation failure

PROBLEM

Female infertility patients with diverse etiologies show increased production of autoantibodies.

METHOD OF STUDY

Immunoblot analysis of sera from patients with endometriosis and tubal factor infertility (TFI) and mass spectrometry identification of candidate antigens.

RESULTS

The immunoblot results demonstrated the presence of IgA and IgG anti-endometrial antibodies (AEA) to various antigens at molecular weights ranging from 10 to 200 kDa. Differences were detected in certain AEA reactions between the patients' groups and particular AEA were associated with in vitro fertilization (IVF) implantation failure. IgA AEA to a 47-kDa protein were more prevalent in TFI patients and were associated with unsuccessful IVF treatment. This antigen was subsequently identified as alpha-enolase.

CONCLUSION

Determination of the presence and spectra of AEA in patients with endometriosis and TFI undergoing IVF may be a useful marker to predict their pregnancy outcome.

Identification of anti-α-enolase autoantibody as a novel serum marker for endometriosis

Diagnosis of endometriosis needs invasive maneuvers. New serum marker that possesses both high sensitivity and high specificity has long been desired. To establish novel serum marker for endometriosis, serum autoantibodies (autoAbs) were investigated using proteomic approach. AutoAbs in sera of endometriotic patients and healthy controls were analyzed using a mesothelial cell line, 2-DE and Western blotting. Proteins in reacted spots were identified using MALDI TOF-MS with MASCOT analysis. ELISAs were established using recombinant proteins and autoAb-titers were estimated in sera of endometriotic patients, disease and healthy controls. Several autoAbs were identified. Anti-α-enolase (Eno1)-autoAb levels in endometriotic patients were significantly elevated compared with both healthy and disease controls. Sensitivity and specificity of serum anti-Eno1-autoAb was nearly comparable to serum CA125. When anti-Eno1-autoAb and CA125 assays were combined, diagnostic sensitivity and accuracy improved. Serum anti-Eno1-autoAb can be a new serum endometriotic marker and it is useful as a supplement assay for CA125. This study validates further clinical evaluation of this novel marker.

An integrated humoral and cellular response is elicited in pancreatic cancer by alpha-enolase, a novel pancreatic ductal adenocarcinoma-associated antigen

Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease with a very poor 5-year survival rate. alpha-Enolase is a glycolytic enzyme that also acts as a surface plasminogen receptor. We find that it is overexpressed in PDAC and present on the cell surface of PDAC cell lines. The clinical correlation of its expression with tumor status has been reported for lung and hepatocellular carcinoma. We have previously demonstrated that sera from PDAC patients contain IgG autoantibodies to alpha-enolase. The present work was intended to assess the ability of alpha-enolase to induce antigen-specific T cell responses. We show that alpha-enolase-pulsed dendritic cells (DC) specifically stimulate healthy autologous T cells to proliferate, secrete IFN-gamma and lyse PDAC cells but not normal cells. In vivo, alpha-enolase-specific T cells inhibited the growth of PDAC cells in immunodeficient mice. In 8 out of 12 PDAC patients with circulating IgG to alpha-enolase, the existence of alpha-enolase-specific T cells was also demonstrated. Taken as a whole, these results indicate that alpha-enolase elicits a PDAC-specific, integrated humoral and cellular response. It is thus a promising and clinically relevant molecular target candidate for immunotherapeutic approaches as new adjuvants to conventional treatments in pancreatic cancer.

Multidimensional degradomics identifies systemic autoantigens and intracellular matrix proteins as novel gelatinase B/MMP-9 substrates

The action radius of matrix metalloproteinases or MMPs is not restricted to massive extracellular matrix (ECM) degradation, it extends to the proteolysis of numerous secreted and membrane-bound proteins. Although many instances exist in which cells disintegrate, often in conjunction with induction of MMPs, the intracellular MMP substrate repertoire or degradome remains relatively unexplored. We started an unbiased exploration of the proteolytic modification of intracellular proteins by MMPs, using gelatinase B/MMP-9 as a model enzyme. To this end, multidimensional degradomics technology was developed by the integration of broadly available biotechniques. In this way, 100-200 MMP-9 candidate substrates were isolated, of which 69 were identified. Integration of these results with the known biological functions of the substrates revealed many novel MMP-9 substrates from the intracellular matrix (ICM), such as actin, tubulin, gelsolin, moesin, ezrin, Arp2/3 complex subunits, filamin B and stathmin. About 2/3 of the identified candidates were autoantigens described in multiple autoimmune conditions and in cancer (e.g. annexin I, nucleolin, citrate synthase, HMGB1, alpha-enolase, histidyl-tRNA synthetase, HSP27, HSC70, HSP90, snRNP D3). These findings led to the insight that MMPs and other proteases may have novel (immuno)regulatory properties by the clearance of toxic and immunogenic burdens of abundant ICM proteins released after extensive necrosis. In line with the extracellular processing of organ-specific autoantigens, proteolysis might also assist in the generation of immunodominant 'neo-epitopes' from systemic autoantigens. The study of proteolysis of ICM molecules, autoantigens, alarmins and other crucial intracellular molecules may result in the discovery of novel roles for proteolytic modification.

Membranous nephropathy and pulmonary alveolar proteinosis

A 47-year-old woman with a severe cough and high-grade fever demonstrated proteinuria of 3.2 g/day. Chest radiograph and CT scan revealed scattered small nodules and ground-glass opacities with interlobular septal thickening in both lungs. The serum levels of surfactant A, surfactant D, and KL-6 were increased to 190 ng/ml (normal: 0-43.8), 360 ng/ml (normal: 0-110), and 4850 U/ml (normal: 0-500), respectively. Video-assisted thoracoscopic lung biopsy revealed eosinophilic amorphous material within alveoli and thickened alveolar septa, which is compatible with pulmonary alveolar proteinosis. Kidney biopsy exhibited membranous nephropathy (Stage I-II) accompanied by granular IgG deposition along the glomerular basement membrane. Although the patient refused treatment with granulocyte macrophage colony stimulating factor (GM-CSF) for pulmonary alveolar proteinosis, her proteinuria and the pulmonary lesion gradually diminished and disappeared after one year.

Alpha-enolase: a novel autoantigen in patients with premature ovarian failure

OBJECTIVE

Although controversial, the presence of circulating antiovarian antibodies (AOA) may be considered a marker of autoimmune premature ovarian failure (POF). The purpose of the present work was to evaluate the presence of AOA in POF patients, and to identify a possible autoantigen in order to develop a reliable diagnostic tool that might help to determine the real prevalence of autoimmune POF.

DESIGN

Non-randomised study. Blood sampling for determination of circulating AOA.

PATIENTS

One hundred and ten patients with POF and 60 normally menstruating women with no record of autoimmune diseases (controls).

MEASUREMENTS

Presence of circulating AOA was assessed by Western-blot, using cytosolic fraction from human ovarian homogenate as antigen.

RESULTS

Twenty-one of 110 women with POF presented circulating antibodies directed toward an antigen of approximately 50 kD. Sixty control subjects proved negative. After purification and analysis by mass spectrometry, the antigen was identified as alpha-enolase.

CONCLUSION

Determination of the presence of circulating antialpha-enolase antibodies might be instrumental in identifying those patients who may present a putative defect in immunoregulation and therefore a possible autoimmune aetiolgy for POF.

Alpha-enolase: a target of antibodies in infectious and autoimmune diseases

Alpha-enolase, also called non-neuronal enolase, belongs to a family of cytoplasmic and glycolytic enzymes. In addition to its glycolytic function, alpha-enolase exerts many other functions in eukaryotes and prokaryotes. Antibodies (Abs) against alpha-enolase have been detected in a large variety of infectious and autoimmune diseases. These Abs might arise as a consequence of a microbial infection or uncontrolled growth or proliferation of cells in specific organs in pathophysiological conditions. In infections, anti-alpha-enolase Abs could play a role in limiting microbial tissue invasion. In autoimmune and inflammatory diseases, anti-alpha-enolase Abs could induce endothelial injury through the generation of immune complexes and activation of the complement classical pathway, inhibit the binding of plasminogen to alpha-enolase with perturbations of the intravascular and pericellular fibrinolytic system, and induce cell death through an apoptotic process. However, further studies are needed to improve our knowledge on the pathogenic role of these Abs.

Cellular targets of anti-α-enolase autoantibodies of patients with autoimmune retinopathy

Autoantibodies against alpha-enolase are often associated with visual loss in patients with autoimmune retinopathy. Anti-recoverin autoantibodies have been the most extensively studied for their pathologic association with cancer-associated retinopathy (CAR). It has been shown that anti-recoverin antibodies penetrate retinal layers corresponding to the cellular location of recoverin and cause the death of photoreceptors and bipolar cells. However, the pathogenic effects of anti-alpha-enolase antibodies have not been studied. In this study, we tested the labeling and apoptotic effects of such autoantibodies on retinal cells. Serum antibodies against alpha-enolase from patients with autoimmune retinopathy were tested ex vivo and in vivo in Sprague-Dawley rats. Autoantibodies to alpha-enolase specifically labeled the retinal ganglion cells and inner nuclear layer cells. Using ex vivo experiments and intravitreal injections, we observed that antibodies were capable of penetrating retinal tissue to target ganglion cell and inner nuclear layers and, consequently, were able to induce cell death through an apoptotic process. The apoptotic nuclei detected by a DNA fragmentation assay and caspase 3-positive cells were co-localized in the ganglion cell layer and inner nuclear layer. The results showed that antibodies against alpha-enolase target antigens in these layers and induce the apoptotic death of sensitive cells. Rat retinal explants and the intravitreal injection of antibodies provide us with a good model to identify antibody pathogenic targets in the retina. Such identification may help explain the complex of clinical symptoms for autoimmune retinopathy mediated by autoantibody and may help guide treatment strategies.

Disease association, origin, and clinical relevance of autoantibodies to the glycolytic enzyme enolase

Serum autoantibodies to the glycolytic enzyme enolase have been reported in a diverse range of inflammatory, degenerative, and psychiatric disorders. Diseases in which these antibodies have been reported in high incidence include autoimmune polyglandular syndrome type 1 (80%, 35 of 44), primary (69%, 60 of 87), and secondary (58%, 14 of 24) membranous nephropathy, cancer-associated retinopathy (68.8%, 11 of 16), autoimmune hepatitis type 1 (60%, 12 of 20), mixed cryoglobulinemia with renal involvement (63.6%, seven of 11), cystoid macular edema (60%, six of 10), and endometriosis (50%, 21 of 41). In autoimmune polyglandular syndrome type 1 patients, all had chronic mucocutaneous candidiasis with demonstrated antibody reactivity to candida enolase, which is suggestive of cross reactivity or epitope mimicry. Formation of autoantibodies to enolase may be a normal process, with reported incidence in apparently healthy subjects ranging from 0% (zero of 91) to 11.7% (seven of 60). Nonetheless, we suggest that excessive production of these autoantibodies, which are generated as a consequence of uptake of enolase by antigen-presenting cells and subsequent B cell activation, can potentially initiate tissue injury as a result of immune complex deposition.

Circulating antibodies against alpha-enolase in patients with primary membranous nephropathy (MN)

MN is characterized by the glomerular deposition of IgG4 immune complexes. This suggests that nephritogenic immune responses in MN are of the Th2 T helper cell type; however, the pathogenesis of MN is still unknown. In this study we examined sera from patients with primary MN for antibodies to renal proteins. A 47-kD protein in both human and porcine renal extracts was found by immunoblotting to react specifically with serum IgG from some patients. This protein was purified from porcine kidney and identified as alpha-enolase on the basis of its partial amino acid sequences. Sera from 87 patients with primary MN, 24 patients with secondary MN (15 rheumatoid arthritis patients, nine systemic lupus erythematosus patients), and 16 healthy subjects were examined by ELISA using purified alpha-enolase. In 60 (69%) patients with primary MN and 14 (58%) patients with secondary MN, the measured optical density values, and hence serum anti-alpha-enolase antibody levels, were greater than the mean + 2 s.d. of healthy subjects. Immunoblot analysis showed that IgG1 or IgG3 was the predominant subclass (Th1 T helper cell type subclass) of antibodies against alpha-enolase in patients with primary and secondary MN. Since circulating antibodies against alpha-enolase have recently been reported in patients with various autoimmune disorders, our results suggest that a number of patients with presumed primary MN may also have abnormalities in Th1 T helper cell-mediated immune responses.

Anti-enolase-alpha autoantibodies in cancer-associated retinopathy: epitope mapping and cytotoxicity on retinal cells

Patients with cancer-associated retinopathy syndrome (CAR), a progressive blinding disease related to retinal degeneration and systemic tumor outside the eye, develop autoantibodies against alpha-enolase. A small percentage of healthy subjects without evident tumor or visual symptoms also possess autoantibody against enolase. In these studies we examined the fine specificity of anti-enolase antibodies derived from patients with CAR and healthy individuals, using synthetic peptides covering the entire sequence of human alpha-enolase. Epitope mapping revealed that three binding regions of enolase within the residues 31-38 (FRAAVPSG), 176-183 (ANFREAMR), and 421-428 (AKFAGRNF) were common for all autoantibodies tested. However, pathogenic sera recognized an additional unique region, the sequence 56-63 (RYMGKGVS). There were also differences in in vitro cytotoxic activities on E1A.NR3 retinal cells and cell-death promoting activities between anti-enolase antibodies of healthy and CAR affected individuals. These studies showed that anti-enolase antibodies from patients with CAR were able to induce apoptotic cell death in E1A.NR3 retinal cells and provided a potential mechanism for retinal degeneration in humans.