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

Proteomic analysis of the effect of high-fat-diet and voluntary physical activity on mouse liver

Nonalcoholic fatty liver disease (NALFD), characterized by an abnormal accumulation of triglycerides in hepatocytes, is closely linked to insulin resistance, metabolic syndrome, and changes in lipogenesis in the liver. The accumulation of hepatic lipids can lead to a range of pathologies from mild steatosis to severe cirrhosis. Endurance exercise is known to ameliorate the adverse health effects of NAFLD. Therefore, we aimed to investigate the effect of voluntary wheel running (VWR) on the metabolic changes in the livers of high-fat diet (HFD)-induced NAFLD mice and used LC-MS/MS (Liquid chromatography–mass spectrometry) to determine whether the tested intervention affected the protein expression profiles of the mouse livers. Male C57BL/6 mice were randomly divided into three groups: control (CON), high-fat diet sedentary group (HFD), high-fat diet VWR group (HFX). HFX group performed voluntary wheel running into individually cages, given a high-fat diet for 12 weeks. Food consumption, body weight, and running distance were measured every week. Using 2D (2-dimensional)-gel electrophoresis, we detected and quantitatively analyzed the protein expression with >2.0-fold change in the livers of HFD-fed mice, HFD-fed exercise (HFX) mice, and chow-fed mice. Body weight was significantly increased in HFD compared to CON (P < 0.05). The 2D-gel electrophoresis analysis indicated that there was a difference between CON and HFD groups, showing 31 increased and 27 decreased spots in the total 302 paired spots in the HFD group compared to CON. The analysis showed 43 increased and 17 decreased spots in the total 258 spots in the HFX group compared to CON. Moreover, 12 weeks of VWR showed an increase of 35 and a decrease of 8 spots in a total of 264 paired spots between HFD and HFX. LC-MS/MS of HFD group revealed that proteins involved in ketogenesis, lipid metabolism, and the metabolism of drugs and xenobiotics were upregulated, whereas detoxifying proteins, mitochondrial precursors, transport proteins, proteasomes, and proteins involved in amino acid metabolism were downregulated. On the other hand, VWR counteracted the protein expression profile of HFD-fed mice by upregulating molecular chaperones, gluconeogenesis-, detoxification-, proteasome-, and energy metabolism-related proteins. This study provided a molecular understanding of the HFD- and exercise-induced protein marker expression and presented the beneficial effects of exercise during pathophysiological conditions.

Autoimmune retinopathy: clinical, electrophysiological, and immunological features in nine patients with long-term follow-up

PURPOSE

We aim to report on the clinical, imaging, immunological, and electrophysiological features of patients with autoimmune retinopathy (AIR) with long-term follow-up.

METHODS

Single-center, retrospective study of a consecutive group of AIR patients treated in a tertiary academic medical center.

RESULTS

Included were nine patients with a mean ± SD age at presentation of 65 ± 13 years and a median follow-up of 63 months (range 18-120). Five patients were known to have cancer. Median interval between onset of ocular symptoms and diagnosis of AIR was 36 months. Mean baseline and final LogMAR visual acuity were 0.72 ± 0.9 and 1.1 ± 1.2, respectively (p = 0.17). The most common funduscopic findings included optic atrophy and bone-spicule-like pigmentation. Thinning of the nerve fiber layer was the most frequent optical coherence tomographic abnormality. Electroretinographic (ERG) recordings demonstrated variably reduced cone- and rod-derived amplitudes in the majority of eyes at presentation. The most commonly detected anti-retinal antibody was anti-α-enolase. Treatment included immunomodulatory therapy and plasmapheresis. ERG tests showed stability in 64% of eyes throughout the treatment period.

CONCLUSION

This study highlights the importance of maintaining a high index of suspicion of AIR, particularly in late middle-aged and elderly patients with "unexplained" visual loss, in light of the non-specific posterior segment signs and the inconsistency of the routinely used ancillary tests.

The Diagnostic Accuracy of Combined Enolase/Cr, CA125, and CA19-9 in the Detection of Endometriosis

Background

The present study was designed to verify the accuracy of the noninvasive biomarkers enolase/Cr, CA125, and CA19-9 as a clinical diagnostic tool for the detection of endometriosis.

Methods

A cross-sectional study was performed at Rasool-e-Akram Hospital affiliated to Iran University of Medical Sciences, Tehran, Iran, from April 2015 to April 2018. Eighty-six women were scheduled to undergo laparoscopy due to chronic pelvic pain, infertility, pelvic mass, and abnormal uterine bleeding. Serum and urine samples of all patients were collected preoperatively. Serum levels of CA125 and CA19-9, and urine levels of enolase-1 were measured. Serum levels of CA125 and CA19-9 were determined by the electrochemiluminescence method (ECL). Urinary enolase-1 was measured by the ELISA method.

Result

Serum levels of CA125 and CA19-9 were significantly higher in the endometriosis group than in controls (p < 0.001, p = 0.004, respectively). Levels of enolase I and enolase/Cr were higher in patients with endometriosis, but the differences were not statistically significant. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of combined enolase/Cr, CA125, and CA19-9 were 65%, 66.6%, 71%, and 60.1%, respectively. The positive likelihood ratio (PLR) and negative likelihood ratio (NLR) of combined enolase/Cr, CA125, and CA19-9 was 1.94 and 0.52, respectively. The area under the ROC curve for enolase/Cr + CA125 + CA19 - 9 was 0.675 (95% confidence interval 0.573-0.710).

Conclusion

The present study revealed that concurrent measurement of enolase-1, CA125, and CA19-9 might be a valuable noninvasive test for the identification of endometriosis.

Moonlighting Proteins at the Candidal Cell Surface

The cell wall in Candida albicans is not only a tight protective envelope but also a point of contact with the human host that provides a dynamic response to the constantly changing environment in infection niches. Particularly important roles are attributed to proteins exposed at the fungal cell surface. These include proteins that are stably and covalently bound to the cell wall or cell membrane and those that are more loosely attached. Interestingly in this regard, numerous loosely attached proteins belong to the class of “moonlighting proteins” that are originally intracellular and that perform essentially different functions in addition to their primary housekeeping roles. These proteins also demonstrate unpredicted interactions with non-canonical partners at an a priori unexpected extracellular location, achieved via non-classical secretion routes. Acting both individually and collectively, the moonlighting proteins contribute to candidal virulence and pathogenicity through their involvement in mechanisms critical for successful host colonization and infection, such as the adhesion to host cells, interactions with plasma homeostatic proteolytic cascades, responses to stress conditions and molecular mimicry. The documented knowledge of the roles of these proteins in C. albicans pathogenicity has utility for assisting the design of new therapeutic, diagnostic and preventive strategies against candidiasis.

Anti-enolase１antibodies from a patient with systemic lupus erythematosus accompanied by pulmonary arterial hypertension promote migration of pulmonary artery smooth muscle cells

OBJECTIVE

Pulmonary arterial hypertension (PAH) is an intractable complication in connective tissue diseases, but the pathological mechanisms responsible for progression remain obscure. This study aims to test whether patient IgG possesses biological activity promoting the migration of pulmonary artery smooth muscle cells (PASMCs).

METHODS

Cell migration was estimated by lamellipodia formation and by utilizing a Boyden chamber method. The specificity of autoantibodies was established by western blotting, ELISA, and immunocytochemistry. The target antigen was investigated by mass spectrometry.

RESULTS

IgG obtained from a patient with systemic lupus erythematosus (SLE) accompanied by PAH was found to promote lamellipodia formation and migration of PASMCs. The IgG bound to a ∼50 kDa protein expressed on the cell membrane, and in the cytoplasm and nucleus. This molecule was identified as enolase 1. Removal of enolase 1-binding antibodies from the IgG fraction, or treatment of the cells with an enolase inhibitor, significantly suppressed the migration of PASMCs.

CONCLUSION

Patients with SLE may possess autoantibodies to enolase 1 which stimulate the migration of PASMCs and are likely to play a role in the progression of PAH.

T Helper 1 Cellular Immunity Toward Recoverin Is Enhanced in Patients With Active Autoimmune Retinopathy

Autoimmune retinopathy (AIR) causes rapidly progressive vision loss that is treatable but often is confused with other forms of retinal degeneration including retinitis pigmentosa (RP). Measurement of anti-retinal antibodies (ARA) by Western blot is a commonly used laboratory assay that supports the diagnosis yet does not reflect current disease activity. To search for better diagnostic indicators, this study was designed to compare immune biomarkers and responses toward the retinal protein, recoverin, between newly diagnosed AIR patients, slow progressing RP patients and healthy controls. All individuals had measurable anti-recoverin IgG and IgM antibodies by ELISA regardless of disease status or Western blot results. Many AIR patients had elevated anti-recoverin IgG1 levels and a strong cellular response toward recoverin dominated by IFNγ. RP patients and controls responded to recoverin with a lower IFNγ response that was balanced by IL-10 production. Both AIR and RP patients displayed lower levels of total peripheral blood mononuclear cells that were due to reductions of CD4⁺ T_H cells. A comparison of messenger RNA (mRNA) for immune-related genes in whole blood of AIR patients versus RP patients or controls indicated lower expression of ATG5 and PTPN22 and higher expression of several genes involved in T_H cell signaling/transcription and adhesion. These data indicate that an immune response toward recoverin is normal in humans, but that in AIR patients the balance shifts dramatically toward higher IFNγ production and cellular activation.

Autoimmune retinopathy and optic neuropathy associated with enolase-positive renal oncocytoma

Purpose

To report a case of autoimmune retinopathy and optic neuropathy associated with an enolase-positive renal oncocytoma.

Observations

A 41-year-old man presented with subacute, painless, bilateral vision loss. On initial examination, visual acuity measured 20/125 OD and 20/1250 OS, and telangiectatic vessels were noted on the optic nerves and in the maculae. Goldmann perimetry showed bilateral, cecocentral scotomas, and electroretinography demonstrated reduced photopic and scotopic signals, concerning for autoimmune retinopathy. Serum testing showed multiple positive anti-optic nerve and anti-retinal antibodies, including to alpha-enolase. Extensive systemic workup was negative except for a large, exophytic, right renal mass. Biopsy was consistent with a benign oncocytoma, and immunohistochemical staining showed diffusely positive alpha-enolase staining. The patient was treated with a five-day course of intravenous methylprednisolone and plasmapheresis with minimal improvement. Surgical excision of the oncocytoma was performed. At 9-months post-operatively, visual acuity had improved to 20/40 OU, with corresponding improvement on visual field and electroretinography testing.

Conclusions and importance

To our knowledge, this is the first report of autoimmune retinopathy and optic neuropathy associated with a renal oncocytoma. The case highlights the importance of a thorough systemic workup in cases of suspected autoimmune retinopathy and reminds clinicians that even tumors considered benign can have distal effects on other organs.

Experimental and bioinformatic approach to identifying antigenic epitopes in human α- and β-enolases

Human α- and β-enolases are highly homologous enzymes, difficult to differentiate immunologically. In this work, we describe production, purification and properties of anti-α- and anti-β-enolase polyclonal antibodies. To raise antibodies, rabbits were injected with enolase isoenzymes that were purified from human kidney (α-enolase) and skeletal muscle (β-enolase). Selective anti-α- and anti-β-enolase antibodies were obtained by affinity chromatography on either α- or β-enolase-Sepharose columns. On Western blots, antibodies directed against human β-enolase, did not react with human α-isoenzyme, but recognized pig and rat β-enolase. To determine what makes these antibodies selective bioinformatic tools were used to predict conformational epitopes for both enolase isoenzymes. Three predicted epitopes were mapped to the same regions in both α- and β-enolase. Peptides corresponding to predicted epitopes were synthesized and tested against purified antibodies. One of the pin-attached peptides representing α-enolase epitope (the C-terminal portion of the epitope 3 - S²⁶²PDDPSRYISPDQ²⁷³) reacted with anti-α-enolase, while the other also derived from the α-enolase sequence (epitope 2 - N¹⁹³VIKEKYGKDATN²⁰⁵) was recognized by anti-β-enolase antibodies. Interestingly, neither anti-α- nor anti-β-antibody reacted with a peptide corresponding to the epitope 2 in β-enolase (G¹⁹⁴VIKAKYGKDATN²⁰⁶). Further analysis showed that substitution of E¹⁹⁷ with A in α-enolase epitope 2 peptide lead to 70% loss of immunological activity, while replacement of A¹⁹⁸ with E in peptide representing β-enolase epitope 2, caused 67% increase in immunological activity. Our results suggest that E¹⁹⁷ is essential for preserving immunologically active conformation in epitope 2 peptidic homolog, while it is not crucial for this epitope's antigenic activity in native β-enolase.

Mycoplasma synoviae enolase is a plasminogen/fibronectin binding protein

Background

Mycoplasma synoviae is an avian pathogen that can lead to respiratory tract infections and arthritis in chickens and turkeys, resulting in serious economic losses to the poultry industry. Enolase reportedly plays important roles in several bacterial pathogens, but its role in M. synoviae has not been established. Therefore, in this study, the enolase encoding gene (eno) of M. synoviae was amplified from strain WVU1853 and expressed in E. coli BL21 cells. Then the enzymatic activity, immunogenicity and binding activity with chicken plasminogen (Plg) and human fibronectin (Fn) was evaluated.

Results

We demonstrated that the recombinant M. synoviae enolase protein (rMsEno) can catalyze the conversion of 2-phosphoglycerate (2-PGA) to phosphoenolpyruvate (PEP), the Km and Vmax values of rMsEno were 1.1 × 10⁻³ M and 0.739 μmol/L/min, respectively. Western blot and immuno-electron microscopy analyses confirmed that enolase was distributed on the surface and within the cytoplasm of M. synoviae cells. The binding assays demonstrated that rMsEno was able to bind to chicken Plg and human Fn proteins. A complement-dependent mycoplasmacidal assay demonstrated that rabbit anti–rMsEno serum had distinct mycoplasmacidal efficacy in the presence of complement, which also confirmed that enolase was distributed on the surface of M. synoviae. An inhibition assay showed that the adherence of M. synoviae to DF-1 cells pre-treated with Plg could be effectively inhibited by treatment with rabbit anti-rMsEno serum.

Conclusion

These results reveal that M. synoviae enolase has good catalytic activity for conversion of 2-PGA to PEP, and binding activity with chicken Plg and human Fn. Rabbit anti–rMsEno serum displayed an obvious complement-dependent mycoplasmacidal effect and adherent inhibition effect. These results suggested that the M. synoviae enolase plays an important role in M. synoviae metabolism, and could potentially impact M. synoviae infection and immunity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-014-0223-6) contains supplementary material, which is available to authorized users.

Modulation of α-enolase post-translational modifications by dengue virus: increased secretion of the basic isoforms in infected hepatic cells

Hepatic cells are major sites of dengue virus (DENV) replication and liver injury constitutes a characteristic of severe forms of dengue. The role of hepatic cells in dengue pathogenesis is not well established, but since hepatocytes are the major source of plasma proteins, changes in protein secretion by these cells during infection might contribute to disease progression. Previously, we showed that DENV infection alters the secretion pattern of hepatic HepG2 cells, with α-enolase appearing as one of the major proteins secreted in higher levels by infected cells. ELISA analysis demonstrated that DENV infection modulates α-enolase secretion in HepG2 cells in a dose-dependent manner, but has no effect on its gene expression and on the intracellular content of the protein as assessed by PCR and western blot analyses, respectively. Two-dimensional western blots showed that both intracellular and secreted forms of α-enolase appear as five spots, revealing α-enolase isoforms with similar molecular weights but distinct isoeletric points. Remarkably, quantification of each spot content revealed that DENV infection shifts the isoform distribution pattern of secreted α-enolase towards the basic isoforms, whereas the intracellular protein remains unaltered, suggesting that post-translational modifications might be involved in α-enolase secretion by infected cells. These findings provide new insights into the mechanisms underlying α-enolase secretion by hepatic cells and its relationship with the role of liver in dengue pathogenesis. In addition, preliminary results obtained with plasma samples from DENV-infected patients suggest an association between plasma levels of α-enolase and disease severity. Since α-enolase binds plasminogen and modulates its activation, it is plausible to speculate the association of the increase in α-enolase secretion by infected hepatic cells with the haemostatic dysfunction observed in dengue patients including the promotion of fibrinolysis and vascular permeability alterations.

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.

Autoantibodies against phospholipase A2 receptor in Korean patients with membranous nephropathy

The data were presented in abstract form at the 45^th meeting of the American Society of Nephrology, October 30-November 04 2012, San Diego, CA, USA. Circulating autoantibodies against M-type phospholipase A₂ receptor (PLA₂R) are important pathogenic antibodies of idiopathic membranous nephropathy (MN) in adults. However, previous studies on the clinical impact of anti-PLA₂R antibodies demonstrated several limitations, including insufficient numbers of study subjects and different time points and methods for anti-PLA₂R antibody measurement. To verify the clinical significance of anti-PLA₂R antibodies in Korean patients with MN, we measured autoantibodies in serum samples obtained at the time of biopsy from a total of 100 patients with idiopathic MN who had not yet received immunosuppressive treatment. We detected anti-PLA₂R antibody in 69 patients, and we observed that autoantibody reactivity reflected the severity of disease activity. Proteinuria and hypoalbuminemia were more severe in patients with anti-PLA₂R than in those without the autoantibodies (2.95 g/g vs. 6.85 g/g, P = 0.003; 3.1 g/dL vs. 2.5 g/dL, P = 0.004, respectively). Additionally, the clinical severities worsened proportionally as the levels of anti-PLA₂R antibodies increased (P = 0.015 and P for trend <0.001 for proteinuria and hypoalbuminemia, respectively). However, neither the levels nor the presence or absence of anti-PLA₂R antibody showed a significant correlation with clinical outcomes, such as remission rate and time to remission. In conclusion, we observed that anti-PLA₂R antibodies are highly prevalent in Korean patients with idiopathic MN and that they reflect the clinical disease activity before the administration of immunosuppressive treatment. However, the levels of anti-PLA₂R antibody at the time of kidney biopsy may not predict the clinical outcomes in current clinical practice.

Identification of Candida albicans heat shock proteins and Candida glabrata and Candida krusei enolases involved in the response to oxidative stress

In the past two decades, Candida species have become the second leading cause of invasive mycosis in immunocompromised patients. In order to colonize their hosts, these microorganisms express adhesins and cell wall proteins that allow them to adhere and neutralize the reactive oxygen species produced by phagocytic cells during the respiratory burst. However, the precise mechanism by which Candida cell wall proteins change their expression in response to oxidative stress has not been described. In an attempt to understand this change in response to oxidative stress, in this study, three Candida species, namely, C. albicans, C. glabrata and C. krusei, were exposed to increasing concentrations of H2O2 and induced cell wall proteins were identified by two-dimensional gel electrophoresis and peptide mass fingerprinting. Sequence analysis of differential proteins led to the identification of two heat-shock proteins in C. albicans, two enolases in C. glabrata and one enolase in C. krusei. Enolases may be involved in the protection of pathogenic cells against oxidative stress as suggested by the decrease in their expression when they were exposed to high concentrations of H2O2. To our knowledge, this is the first demonstration that expression of these proteins changes in response to oxidative stress in different Candida species. This knowledge can eventually facilitate both an early diagnosis and a more efficient treatment of this mycosis.

Optical coherence tomography findings in autoimmune retinopathy

PURPOSE

To report optical coherence tomography (OCT) features of patients with autoimmune retinopathy.

DESIGN

Consecutive case series.

METHOD

Eight patients who presented with unexplained loss of central vision, visual field defects, and/or photopsia were diagnosed with autoimmune retinopathy based on clinical features, electroretinogram (ERG) findings, and serum antiretinal antibody analysis. All patients underwent OCT testing of the macula and nerve fiber layer (NFL).

RESULTS

Outer retinal abnormalities and/or decreased macular thickness on OCT were seen in all patients. Macular OCT showed reduced central macular and foveal thicknesses in 6 patients (mean thickness 143±30 μm and 131±29 μm respectively). In all but 1 patient, loss of the photoreceptor layer or disruption of the photoreceptor outer and inner segment junction was noted. Three patients showed only mild to moderate focal NFL loss.

CONCLUSIONS

Retinal atrophy and reduced macular thickness on OCT are predominant features in patients with autoimmune retinopathy. OCT provides objective measures of retinal damage and may offer clues toward understanding the mechanism of visual dysfunction and the diagnosis of autoimmune retinopathy.

Diversity in autoimmunity against retinal, neuronal, and axonal antigens in acquired neuro-retinopathy

PURPOSE

Autoimmune retinopathies and optic neuropathies are complex disorders of the retina and the optic nerve, in which patients develop autoantibodies (AAbs) against retinal and optic nerve proteins. Autoimmunity might significantly influence the outcome of retinal and optic nerve degenerative process but the pathogenic process is not fully elucidated. To better understand the role of AAbs in pathogenicity of these suspected autoimmune visual disorders, we focused on unique AAbs specificities associated with the syndrome to identify their antigenic targets in the optic nerve and retina.

METHODS

Serum samples were obtained from patients, whose visual disorders were potentially autoimmune in nature, including patients with cancer with possible paraneoplastic syndrome. Autoantibodies were tested against human optic nerve and retinal antigens for specificity by Western blotting and immunofluorescence.

RESULTS

Out of 209 tested for anti-optic nerve autoantibodies, 55% showed specific neuronal autoantibodies. The repertoire of anti-optic nerve autoantibodies often differed from anti-retinal antibodies. The major antigenic targets for these antibodies could be divided into four groups. Autoantibodies specific to classical glycolytic enzymes involved in energy production (α and γ enolases, glyceraldehyde 3-phosphate dehydrogenase) also reacted with retinal antigens. Autoantibodies targeted neuronal-specific myelin proteins (MBP, MOG), aquaporin 4, and collapsing response mediator protein 5 reacted with optic nerve antigens. They showed immunostaining of axons and myelin in the optic nerve as determined by double immunofluorescence.

CONCLUSION

We identified novel neuronal autoantigens not previously known to be associated with acquired autoimmune retinopathy and optic neuropathy. Knowledge of the full autoantibody repertoire perpetuating this syndrome is an important first requirement in increasing our understanding of the autoimmune process to facilitate better diagnosis, prognosis, and treatment.

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.

Anti-alpha-enolase antibody as a serologic marker and its correlation with disease severity in intestinal Behçet's disease

BACKGROUND

Intestinal Behçet's disease (BD) is a chronic inflammatory bowel disease, as are Crohn's disease (CD) and ulcerative colitis (UC). But unlike CD and UC, serologic markers for intestinal BD are not well known. Recently, anti-α-enolase antibody (AAEA) has been detected in sera from BD patients.

AIMS

The aim of this study was to evaluate the prevalence of AAEA in intestinal BD and its clinical correlations.

METHODS

The study sample included 80 patients with intestinal BD and 23 healthy controls. IgM AAEA was detected by ELISA. The positivity of IgM AAEA was defined as an optical density greater than three standard deviations above the mean of the control sera. Other parameters, such as demographic information, subtype of BD, colonoscopic findings, disease severity and treatment modality, were analyzed retrospectively.

RESULTS

The prevalence of IgM AAEA was 67.5% in intestinal BD and 0% in the control group. The positivity rate of IgM AAEA was higher in complete or incomplete BD than in suspected BD (77.5% vs. 51.6%, P = 0.016). The mean HBI score was higher in antibody positive patients than in antibody negative patients (5.60 vs. 4.61, P = 0.003). The cumulative probability of steroid use for aggravation of intestinal and extra-intestinal symptoms was higher in antibody positive patients than in antibody negative patients (P = 0.012). The number of patients with systemic involvement was higher in the AAEA positive group than in the negative group.

CONCLUSIONS

Monitoring IgM AAEA may be helpful for diagnosis of intestinal BD and could be used to predict clinical course and disease severity.

Generation and characterization of anti-alpha-enolase single-chain antibodies in chicken

It was previously reported that up-regulation of α-enolase protein was detected in 65% of patients with non-small cell lung cancers (NSCLC). Moreover, a high titer of anti-α-enolase antibodies was developed in a smaller proportion (7.4%) of these patients than in non-tumor-associated patients and healthy subjects. In the present study, we characterized polyclonal and single-chain variable fragment (scFv) anti-α-enolase antibodies from immunized chickens. The E. coli-derived recombinant α-enolase protein was purified to its high homogenicity as verified by SDS-PAGE. After the 4th immunization, a high titer of specific polyclonal anti-α-enolase antibodies was elicited in immunized chickens and specifically recognized the purified human α-enolase antigen as determined by Western blot and ELISA. The expressed heavy and light chain variable genes (VH and VL) were isolated from spleen B cells and amplified to construct phage antibody libraries containing scFv molecules. After four rounds of panning selection, the scFv antibodies of randomly chosen clones were expressed and their binding specificity to α-enolase protein was verified using competitive ELISA, flow cytometry and immunofluorescence staining. Nucleotide sequence analysis from 10 α-enolase binding clones showed that 3 (30%) clones used identical heavy and light genes for scFv antibody expression, as represented by EnL5. Notably, amino acid changes in complementarity-determining regions (CDRs) were more frequently observed than those in framework regions (FRs) in all clones, indicating a strong affinity selection through mutations. All together, it is believed that these polyclonal and scFv IgY antibodies may be helpful in the development of molecular diagnostic and therapeutic agents for lung cancers in the future.

Autoantigens in ovarian autoimmunity associated with unexplained infertility and premature ovarian failure

OBJECTIVE

To identify ovarian autoantigens associated with ovarian autoantibodies.

DESIGN

Hypothesis-generating prospective study.

SETTING

Urban infertility referral centers and academic research institution.

PATIENT(S)

Seventy-four patients with infertility, 19 patients with premature ovarian failure (POF), and 16 healthy control women.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Identification of autoantigens.

RESULT(S)

To identify major antigens for ovarian autoimmunity, sera from 74 women with unexplained infertility were screened for ovarian autoantibodies (AOAs) by immunoassay and one-dimensional Western blot. The majority of sera had immunoreactions at 50-56 kDa. Six representative positive infertility sera were used to identify antigens between 40 and 60 kD by two-dimensional Western blot and mass spectrometry. Antigens included aldehyde (retinal) dehydrogenases (ALDH1A1, ALDH1A2, and ALDH7A1), protein disulfide isomerase A3, vimentin, α-enolase, phosphoglycerate dehydrogenase, and selenium-binding protein 1 (SBP1). Sixty percent (24 out of 40) of infertility and POF sera were positive for recombinant ALDH1A1, SBP1, or enolase; 80.7% (21 out of 26) of AOA-positive sera had antibodies to one or more of the three antigens, and only 7% (1 out of 14) of AOA-negative sera had antibodies to recombinant proteins.

CONCLUSION(S)

ALDH1A1 and SBP1 are unique to ovarian autoimmunity associated with infertility and POF, and may provide the basis for specific tests to identify patients with ovarian autoimmunity.

Anti-alpha-enolase autoantibodies are down-regulated in advanced cancer patients

OBJECTIVE

Elevation of serum autoantibodies to alpha-enolase (ENO1) is often seen in inflammation diseases. However, it is unclear whether the levels of serum ENO1 autoantibodies could be affected during tumor progression. Hence, we attempted to determine the relative serum ENO1 autoantibody levels in healthy individuals and various stages of patients with lung and breast cancers.

METHODS

Sera were obtained from 99 normal individuals, 21 patients with non-cancer-associated diseases and 178 cancer patients, including Stage I, II and IV non-small cell lung cancer, small cell lung cancer and breast cancer. The ENO1 autoantibody levels were determined by enzyme-linked immunosorbent assay.

RESULTS

Compared with the healthy individuals, the levels of ENO1 autoantibodies were significantly decreased in Stage IV non-small cell lung cancer, small cell lung cancer and breast cancer patients. Consistently, this phenomenon was also observed in tumor-grafted mice. Using logistic regression analyses, data show that the titer status of ENO1 autoantibody level is highly associated with the late stage of lung and breast cancers when compared with those of healthy controls. In contrast, there were no statistic differences between healthy controls and early stages of non-small cell lung cancer patients, and total amounts of serum immunoglobulin A, immunoglobulin G and immunoglobulin M levels in Stage IV non-small cell lung cancer patients were not significantly distinct from those of the healthy controls. Thus, the decreased ENO1 autoantibody event in malignant stage of cancer patients is not contributed by reduction in total immunoglobulin.

CONCLUSIONS

Marked decrease in the basal level of serum ENO1 autoantibodies is a common malignant event of lung and breast cancers, suggesting that ENO1 autoantibody may serve as a prognostic marker to monitor the disease progression of these cancer patients.

Melanoma-associated retinopathy: a paraneoplastic autoimmune complication

OBJECTIVES

To study 11 patients with melanoma-associated retinopathy (MAR) to clarify the reliability of various methods of diagnostic testing, to determine the underlying antigenic retinal proteins, and to study the clinical histories and types of associated melanomas.

METHODS

Clinical data were obtained from patients with melanoma who developed marked visual problems. Testing included electroretinography, kinetic visual fields, comparative studies of Western blots, and indirect immunohistologic examination to detect antiretinal antibodies, as well as proteomic studies to identify underlying antigenic retinal proteins.

RESULTS

Patients with MAR typically have rapid onset of photopsias, scotomata, and loss of central or paracentral vision. Ophthalmoscopy seldom shows significant changes early, but electroretinograms are abnormal. Results of Western blots and immunohistologic examination can show antiretinal antibodies but not always. Most patients (9 of 11) had a strong family history of autoimmune disorders. Any type of melanoma (cutaneous, choroidal, ciliary body, or choroidal nevi) may be associated with this paraneoplastic autoimmune reactivity. MAR may precede or follow the diagnosis of melanoma. Patients with MAR have the same antigenic retinal proteins that have been associated with cancer-associated retinopathy. In addition, 2 new antigenic retinal proteins, aldolase A and aldolase C, were found.

CONCLUSIONS

There was a high prevalence of positive family histories of autoimmune disease in patients with MAR. To confirm the disorder, multiple clinical and serum diagnostic techniques (Western blot or indirect immunohistologic examination) are needed. Two newly observed antigenic retinal proteins, aldolase A and aldolase C, are associated with MAR.

Prevalence of antitumor antibodies in laying hen model of human ovarian cancer

Antitumor antibodies are associated with tumors in human cancers. There is relatively little information on the timing and progression of antibody response to tumors. The objective of the study was to determine if spontaneous ovarian cancer in the egg-laying hen is associated with antitumor antibodies. Antibodies were detected by immunoassay and immunoblotting using proteins from normal ovary and ovarian tumors. Candidate antigens were identified by mass spectrometry of immunoreactive spots cut from 2-dimensional gels and Western blot. Antitumor (serum reacting against tumor ovarian extract) and antiovarian (serum reacting against normal ovarian extract) antibodies were significantly associated with ovarian cancer (67%; P <or= 0.001) compared with normal control hens. Hens with abnormal histology but no gross tumor had antitumor antibodies (63%; P <or= 0.025) but not antiovarian antibodies. There were common as well as different immunoreactions against normal ovary and homologous and heterologous tumor proteins in 2-dimensional Western blots. The candidate antigens included those commonly associated with human cancers and other diseases such as vimentin, apolipoprotein A1, Annexin II, enolase, DJ-1, and so on. The results suggest that antitumor antibodies are associated with ovarian cancer in hens, similar to human ovarian cancer. The egg-laying hen may be a model for understanding the antitumor humoral immune response, particularly at early tumor stages that are not readily accessible in human ovarian cancer.

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.

Elevated anti-alpha-enolase antibody levels in Kawasaki disease

OBJECTIVE

By functioning as a heat-shock protein (HSP), alpha-enolase has an important role in the pathophysiology of multivariant vasculitis. Kawasaki disease (KD) is a type of vasculitis occurring primarily in children. The role of alpha-enolase in KD was assessed by measuring anti-alpha-enolase antibody (Ab) titres in patients with KD and the usefulness of anti-alpha-enolase Ab as a diagnostic tool in atypical KD patients was evaluated.

METHODS

Anti-alpha-enolase Ab titres were measured by using an enzyme-linked immunosorbent assay (ELISA) in seven normal control patients, nine febrile control patients and 14 KD patients (10 typical KD, four atypical KD). A standard deviation (SD) of 3 above the mean of the normal control group was considered to be positive reactivity. Western blotting using recombinant human alpha-enolase was performed in four KD patients and three normal controls.

RESULTS

With the positive reactivity limited to +3 SD over the mean (>0.6), 10 out of 14 patients (71%) were positive at the acute onset and 12 out of 14 patients (85.7%) were positive before discharge. In total, 12 out of 14 patients (85.7%) were positive either at acute onset or before discharge. All four atypical KD patients showed positive reactivity. Specific positive bands against recombinant human alpha-enolase were detected by western blotting in all four KD patients, but no reactivity was seen in three patients with normal controls.

CONCLUSION

This is the first study to demonstrate that autoantibodies against the alpha-enolase are present in the sera of KD patients. We suggest that anti-alpha-enolase Ab should be a good candidate for a diagnostic tool in atypical KD.

Anti-alpha-enolase antibodies in patients with inflammatory Bowel disease

BACKGROUND

Patients with inflammatory bowel disease (IBD) carry autoantibodies such as perinuclear antineutrophil cytoplasmic antibodies (pANCA). alpha-Enolase has been proposed as a target antigen in IBD. We evaluated the prevalence and diagnostic value of anti-alpha-enolase antibodies in IBD and related disorders.

METHODS

We used a classic proteomic approach with extracts from granulocytes and pANCA-positive ulcerative colitis (UC) sera to confirm alpha-enolase as a target antigen. By means of Western blot analysis, we screened a cohort of 525 subjects for the presence of anti-alpha-enolase antibodies. We performed GeneArray experiments on RNA extracted from colonic mucosal biopsies from 35 IBD and 6 control patients.

RESULTS

We detected anti-alpha-enolase antibodies 49.0% of patients with UC, 50.0% of patients with Crohn's disease, 30.5% of patients with primary sclerosing cholangitis, 37.8% of patients with autoimmune hepatitis, 34.0% of patients with ANCA-positive vasculitis, 31.0% of non-IBD gastrointestinal controls, and 8.5% of healthy controls. Gene array experiments showed a significant upregulation of alpha-enolase mRNA in colonic mucosal biopsies from patients with IBD, but not from controls. There was no association between the presence of pANCA and anti-alpha-enolase antibodies. Preabsorption with alpha-enolase did not eliminate the pANCA pattern on indirect immunofluorescence.

CONCLUSIONS

Anti-alpha-enolase antibodies are present in a substantial proportion of patients with IBD, patients with various inflammatory/autoimmune disorders, and non-IBD gastrointestinal controls. Therefore, anti-alpha-enolase antibodies are of limited diagnostic value for the diagnosis of IBD.

Using proteomics to identify targets of antiendothelial cell antibodies

Antiendothelial cell antibodies represent a heterogeneous group of antibodies directed against a variety of antigen determinants of endothelial cells. Antibodies reacting with endothelial structures have been detected in sera from patients with autoimmune vasculitis, both primary and secondary to systemic connective tissue diseases. It may interfere with several functions and, therefore, may be a pathophysiological relevance. The analysis of the antigens recognized by antiendothelial cell antibodies showed that the antibodies are directed against a heterogeneous family of both constitutive and nonconstitutive surface endothelial proteins. Proteomics is a field of science that evaluates a large number of proteins expressed from a given cell line or organism. The technology of proteomics has been used as a method for discovering the target protein specific to a particular disease by searching for the expression or modification of the protein. Recently, progress has been made in defining the target antigens of these antibodies and proteomic technologies is one of them. This review will focus on the proteomic technologies in searching autoantigens/autoantibodies associated with disease of the endothelium.

Enolase and arrestin are novel nonmyelin autoantigens in multiple sclerosis

INTRODUCTION

Although myelin autoimmunity is known to be a major factor in the pathogenesis of multiple sclerosis (MS), the role of nonmyelin antigens is less clear. Given the complexity of this disease, it is possible that autoimmunity against nonmyelin antigens also has a pathogenic role. Autoantibodies against enolase and arrestin have previously been reported in MS patients. The T-cell response to these antigens, however, has not been established.

METHODS

Thirty-five patients with MS were recruited, along with thirty-five healthy controls. T-cell proliferative responses against non-neuronal enolase, neuron-specific enolase (NSE), retinal arrestin, beta-arrestin, and myelin basic protein were determined.

RESULTS

MS patients had a greater prevalence of positive T-cell proliferative responses to NSE, retinal arrestin, and beta-arrestin than healthy controls (p<0.0001). The proliferative response against NSE, retinal arrestin, and beta-arrestin correlated with the response against myelin basic protein (p < or = 0.004). Furthermore, the proliferative response against retinal arrestin was correlated to beta-arrestin (p<0.0001), whereas there was no such correlation between non-neuronal enolase and NSE (p = 0.23).

DISCUSSION

There is accumulating evidence to suggest that the pathogenesis of MS involves more than just myelin autoimmunity/destruction. Autoimmunity against nonmyelin antigens may be a component of this myriad of immunopathological events. NSE, retinal arrestin, and beta-arrestin are novel nonmyelin autoantigens that deserve further investigation in this respect. Autoimmunity against these antigens may be linked to neurodegeneration, defective remyelination, and predisposition to uveitis in multiple sclerosis. Further investigation of the role of these antigens in MS is warranted.

The role of anti-alpha-enolase autoantibodies in pathogenicity of autoimmune-mediated retinopathy

Autoantibodies against alpha-enolase, a glycolytic enzyme, have been frequently associated with visual loss and retinal degeneration in patients with autoimmune and cancer-associated retinopathy; however their role in the pathogenicity of retinopathy has not been fully explained. Thus, we examined the causative role of anti-enolase antibodies on retinal cells. In the in vitro studies reported here, we found that Enol-1 monoclonal antibody against alpha-enolase significantly inhibited the catalytic function of enolase, which resulted in the depletion of glycolytic ATP. Enol-1 significantly increased intracellular Ca(2+), which led to Bax translocation to the mitochondria, and the release of cytochrome c into the cytoplasm--events that correlated with the initiation of apoptosis. Normal IgG did not induce intracellular calcium or reduce cytosolic ATP. L-type voltage-gated calcium channel blockers (nifedipine, D-cis-diltiazem, and verapamil) were effective in blocking the Ab-induced intracellular Ca(2+) rise and induction of Bax. Based on these findings we propose that chronic access of autoantibodies to the retina results in the inhibition of enolase catalytic function, depletion of ATP, and elevation in intracellular Ca(2+), leading to deregulation of glycolysis in retinal neurons and their destruction.

Enolase autoantibodies and retinal function in multiple sclerosis patients

BACKGROUND

Electroretinographic (ERG) abnormalities have been reported in multiple sclerosis (MS), as well as the presence of circulating antiretinal antibodies. We and others have reported cases of impaired vision and diminished ERGs in MS patients with alpha-enolase autoantibodies. Anti-enolase antibodies have been implicated in autoimmune retinopathy. We performed this study to further explore the relationship between antiretinal antibodies and ERG changes in patients with MS.

METHODS

Patients with clinically definite MS and normal visual acuity were recruited for this study, along with healthy controls. All patients and controls had ERG testing done according to ISCEV standards. Patient and control sera were analyzed for the presence of antiretinal antibodies using Western blot and ELISA techniques, and HLA class II typing was performed using polymerase chain reaction.

RESULTS

We found a statistically significant difference between MS patients and controls in the rod-cone b-wave implicit time (p < 0.005). We found autoantibodies against alpha-enolase in 38% of MS patients and 11% of controls (p < 0.02). There was no statistically significant difference between ERG parameters of MS patients with alpha-enolase autoantibodies compared to those without alpha-enolase antibodies. Furthermore, the presence of alpha-enolase did not associate with a particular HLA haplotype.

CONCLUSIONS

Factors affecting the retina other than alpha-enolase antibodies may account for the delayed rod-cone b-wave implicit times observed in MS patients in this study. Anti-enolase antibodies are likely an epiphenomenon of autoimmune disease, and are not causing retinopathy in MS patients with normal visual acuity. However, the possibility of rare cases of patients with pathogenic alpha-enolase autoantibodies can not be excluded. The pathogenic contribution of these antibodies in MS patients with visual impairment deserves further investigation.

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.

Identification of alpha-enolase as an autoantigen in lung cancer: its overexpression is associated with clinical outcomes

PURPOSE

Although existence of humoral immunity has been previously shown in malignant pleural effusions, only a limited number of immunogenic tumor-associated antigens (TAA) have been identified and associated with lung cancer. In this study, we intended to identify more TAAs in pleural effusion-derived tumor cells.

EXPERIMENTAL DESIGN

Using morphologically normal lung tissues as a control lysate in Western blotting analyses, 54 tumor samples were screened with autologous effusion antibodies. Biochemical purification and mass spectrometric identification of TAAs were done using established effusion tumor cell lines as antigen sources. We identified a p48 antigen as alpha-enolase (ENO1). Semiquantitative immunohistochemistry was used to evaluate expression status of ENO1 in the tissue samples of 80 patients with non-small cell lung cancer (NSCLC) and then correlated with clinical variables.

RESULTS

Using ENO1-specifc antiserum, up-regulation of ENO1 expression in effusion tumor cells from 11 of 17 patients was clearly observed compared with human normal lung primary epithelial and non-cancer-associated effusion cells. Immunohistochemical studies consistently showed high level of ENO1 expression in all the tumors we have examined thus far. Log-rank and Cox's analyses of ENO1 expression status revealed that its expression level in primary tumors was a key factor contributing to overall- and progression-free survivals of patients (P < 0.05). The same result was also obtained in the early stage of NSCLC patients, showing that tumors expressing relatively higher ENO1 level were tightly correlated with poorer survival outcomes.

CONCLUSIONS

Our data strongly support a prognostic role of ENO1 in determining tumor malignancy of patients with NSCLC.

Fungal heat-shock proteins in human disease

Heat-shock proteins (hsps) have been identified as molecular chaperones conserved between microbes and man and grouped by their molecular mass and high degree of amino acid homology. This article reviews the major hsps of Saccharomyces cerevisiae, their interactions with trehalose, the effect of fermentation and the role of the heat-shock factor. Information derived from this model, as well as from Neurospora crassa and Achlya ambisexualis, helps in understanding the importance of hsps in the pathogenic fungi, Candida albicans, Cryptococcus neoformans, Aspergillus spp., Histoplasma capsulatum, Paracoccidioides brasiliensis, Trichophyton rubrum, Phycomyces blakesleeanus, Fusarium oxysporum, Coccidioides immitis and Pneumocystis jiroveci. This has been matched with proteomic and genomic information examining hsp expression in response to noxious stimuli. Fungal hsp90 has been identified as a target for immunotherapy by a genetically recombinant antibody. The concept of combining this antibody fragment with an antifungal drug for treating life-threatening fungal infection and the potential interactions with human and microbial hsp90 and nitric oxide is discussed.

An Immunoproteomic Approach for Identification of Clinical Biomarkers for Monitoring Disease

Circulating antibodies can be used to probe protein arrays of body fluids, prepared by two-dimensional gel electrophoresis, for antigenic biomarker detection. However, detected proteins, particularly low abundance antigens, often remain unidentifiable due to proteome complexity and limiting sample amounts. Using a novel enrichment approach exploiting patient antibodies for isolation of antigenic biomarkers, we demonstrate how immunoproteomic strategies can accelerate biomarker discovery. Application of this approach as a means of identifying biomarkers was demonstrated for cystic fibrosis (CF) lung disease by isolation and identification of inflammatory-associated autoantigens, including myeloperoxidase and calgranulin B from sputum of subjects with CF. The approach was also exploited for isolation of proteins expressed by the Pseudomonas aeruginosa strain PA01. Capture of PA01 antigens using circulating antibodies from CF subjects implicated in vivo expression of Pseudomonas proteins. All CF subjects screened, but not controls, were immunoreactive against immunocaptured Pseudomonas proteins, representing stress (GroES and ferric iron-binding protein HitA), immunosuppressive (thioredoxin), and alginate synthetase pathway (nucleoside-diphosphate kinase) proteins, implicating their clinical relevance as biomarkers of infection.

Antibodies against human muscle enolase recognize a 45-kDa bacterial cell wall outer membrane enolase-like protein

Enolase, is a glycolytic enzyme ubiquitous in higher organisms, where it forms tissue specific dimers of isoforms, also found in the cytoplasm of fermentative bacteria. The aim of this work was to identify enolase-like proteins in the cell wall of some Gram-negative bacteria using antibodies against human beta-enolase, an isoenzyme specific to skeletal and heart muscles. Cell wall outer membrane protein (OMP) preparations were obtained from 9 strains of Enterobacteriaceae and one of Pseudomonas aeruginosa. Specific enzymatic enolase activity was detected in the supernatant fractions of cytosolic and inner membrane material, but not in purified OMP preparations. Rabbit polyclonal antibodies specific against human beta-enolase were prepared and purified using immobilized human beta-enolase in affinity chromatography. In SDS-polyacrylamide gel electrophoresis and immunoblotting assay of purified OMP preparations, rabbit anti-enolase antibody interacted specifically with a few OMPs, of which a 45-kDa band also interacted with human sera of patients presenting Buerger disease and atherosclerosis. The most distinct interaction of human sera was observed with a 45-kDa OMP of Klebsiella pneumoniae. This protein was further isolated from K. pneumoniae cell mass in two ways, namely preparative SDS-polyacrylamide gel electrophoresis and specific affinity chromatography using immobilized affinity-purified rabbit antibody raised against human beta-enolase. The data obtained from tandem mass spectrometry tryptic peptide analysis and sequence comparison of human and bacterial enolases using protein databases, could reveal the similarity in the epitopes between membrane enolase-like protein from Klebsiella and human beta-enolase. The results show that the protein present in all studied strains has a common epitope on human beta-enolase. These data raise the question whether such a bacterial protein might be a marker for detecting and monitoring damage to skeletal and heart muscles.

Clinical and electrophysiologic characterization of paraneoplastic and autoimmune retinopathies associated with antienolase antibodies

PURPOSE

Paraneoplastic and autoimmune retinopathies are immunologically mediated retinal degenerations that are associated with antibodies directed against any of several retinal proteins, including alpha-enolase. We report the clinical and electrophysiological features of antienolase retinopathy in contrast to the features of antirecoverin retinopathy.

DESIGN

Retrospective, observational case series.

METHODS

Patients were referred for evaluation of unexplained acquired visual symptoms, including photopsias, and loss of visual acuity or field considered of possible retinal origin. Full-field and multifocal electroretinograms (ERGs) were performed. Sera from patients were examined for antiretinal antibodies by Western blot analysis using proteins extracted from human retinas and by immunohistochemistry; antienolase was confirmed by incubating patient sera with purified alpha-enolase.

RESULTS

Of 87 patients with unexplained retinal visual symptoms associated with abnormal ERGs, 37 (43%) demonstrated autoantibodies to retinal antigens, including 12 against alpha-enolase, of whom 4 had cancer. Initial visual loss was typically central and often asymmetric. The ERGs demonstrated mostly normal rod responses but central cone abnormalities (evident on multifocal ERG) and, for many, global cone abnormalities. Seven patients developed optic disk pallor. Corticosteroid and immunosuppressive therapy, when attempted, was clinically ineffective.

CONCLUSIONS

Antienolase retinopathy is a protean autoimmune retinopathy that characteristically presents with cone dysfunction. The visual impairment and course vary from relative stability for years to slow progression with loss of central vision. With time, optic disk pallor can evolve, presumably from attrition of ganglion cells.

Serum Antibodies to Retinal Antigens in Lung Cancer and Sarcoidosis

OBJECTIVE

Autoantibodies to various neuronal proteins frequently accompany lung cancer and their appearance may precede cancer symptoms. In this study we examined which retinal antigens (RAs) are recognized by sera of patients with lung cancer and whether the occurrence of serum antibodies to particular RAs is characteristic for cancer in comparison with a noncancer lung disease.

METHODS

Sera of 72 patients with non-small-cell lung cancer (NSCLC), 29 with small-cell lung cancer (SCLC), 27 with sarcoidosis (S), and sera of 32 healthy donors were examined in immunoblotting using retinal extracts and purified RAs as antigens.

RESULTS

69.0% of SCLC, 45.8% of NSCLC, and 44.4% of S sera displayed anti-RAs reactivity. Significantly less (p < 0.05; chi(2) test) percent of healthy control sera reacted with RAs. Lung cancer sera recognized mainly 46-, 56-, and 36-kD and to a smaller extent also 96-, 72-, 43-, and 26-kD proteins. Most of them were recognized with about 2-fold lower frequencies by S and control sera. Only lung cancer sera contained very high-titer antibodies to 46- and 26-kD RAs, identified as alpha-enolase and recoverin, respectively.

CONCLUSION

Antibodies to RAs occur more frequently and in higher titers in lung cancer (especially SCLC) than in sarcoidosis or control sera. Although antibodies to retinal alpha-enolase, recoverin and other RAs are present mainly or exclusively in lung cancer sera, none of them seems to be a specific marker of a particular disease.

Anti-alpha-enolase antibodies in pituitary disease

A previous study reported a high prevalence of autoantibodies to alpha-enolase in lymphocytic hypophysitis and these antibodies efficiently distinguished lymphocytic hypophysitis from pituitary tumors. To confirm this, we examined autoantibodies to alpha-enolase in patients with lymphocytic hypophysitis (n = 17), pituitary non-functioning adenoma (n = 13), other pituitary diseases (n = 17) and other autoimmune diseases (n = 30), and compared to healthy controls (n = 46). Autoantibodies were found in 41.2%, 46.2%, 23.5%, 20.0% and 4.3%, respectively. Our findings indicate that detection of anti-alpha-enolase antibodies is not suitable for specific diagnosis of lymphocytic hypophysitis.

Human alpha-enolase from endothelial cells as a target antigen of anti-endothelial cell antibody in Behçet's disease

OBJECTIVE

To identify and recombine a protein of the human dermal microvascular endothelial cell (HDMEC) that specifically reacts with anti-endothelial cell antibody (AECA) in the serum of patients with Behçet's disease (BD), and to evaluate the usefulness of this protein in BD.

METHODS

The proteomics technique, with 2-dimensional gel electrophoresis and matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry, was used to identify and recombine HDMEC antigen. Western blotting and enzyme-linked immunosorbent assay (ELISA) of recombinant protein isolated by gene cloning were performed on serum from healthy controls, patients with BD, and patients with other rheumatic diseases (rheumatoid arthritis, systemic lupus erythematosus, and Wegener's granulomatosis).

RESULTS

Eighteen of 40 BD patients had serum IgM antibody to HDMEC antigen. The purified protein that reacted with AECA in BD patient sera was found to be alpha-enolase by 2-dimensional gel electrophoresis followed by immunoblotting and MALDI-TOF mass spectrometry. Recombinant alpha-enolase protein was isolated and refined by gene cloning. On Western blots, AECA-positive IgM from the sera of patients with active BD reacted strongly with recombinant human alpha-enolase. BD patient sera positive for anti-alpha-enolase did not react with human gamma-enolase. On dot-blotting, reactivity to human alpha-enolase was detected only in the IgM-positive group. Fifteen of the 18 AECA-positive sera that were positive for the HDMEC antigen showed reactivity to recombinant alpha-enolase IgM antibody by ELISA.

CONCLUSION

The alpha-enolase protein is the target protein of serum AECA in BD patients. This is the first report of the presence of IgM antibodies to alpha-enolase in endothelial cells from the serum of BD patients. Although further studies relating this protein to the pathogenesis of BD will be necessary, alpha-enolase and its antibody may prove useful in the development of new diagnostic and treatment modalities in BD.

Identification of rat targets of anti-soluble liver antigen autoantibodies by serologic proteome analysis

BACKGROUND

Anti-soluble liver antigen (SLA) autoantibodies are specific for autoimmune hepatitis type 1 and are the only immunologic marker found in 15-20% of hepatitis cases previously considered cryptogenic. Anti-SLA antibodies react with the 100 000g supernatant from rat liver homogenate, but the molecular targets remain controversial.

METHODS

We characterized anti-SLA targets by one- and two-dimensional immunoblotting analysis. The recognized proteins were identified by peptide mass fingerprint analysis after matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry.

RESULTS

Three proteins of 35 kDa and pI 6.0, 50 kDa and pI between 6.0 and 6.5, and 58 kDa and pI between 6.5 and 7.0 were stained more intensely by anti-SLA positive-sera than by control sera. After in-gel tryptic digestion, MALDI-TOF analysis of the generated peptides enabled the clear identification of N-hydroxyarylamine sulfotransferase, isoforms of alpha-enolase, and isoforms of catalase.

CONCLUSIONS

Possible antigens for anti-SLA antibodies include a sulfotransferase, alpha-enolase(s), and catalase(s). Two-dimensional electrophoresis combined with mass spectrometry offers a versatile tool to identify molecular targets of autoantibodies and thus to improve diagnostic tools and the understanding of the immune process.

Differential expression of the enolase gene under in vivo versus in vitro growth conditions of Aeromonas hydrophila

Aeromonas hydrophila is an emerging human pathogen that leads to gastroenteritis and other invasive diseases. By using a murine peritoneal culture (MPC) model, we identified via restriction fragment differential display PCR (RFDDPCR) five genes of A. hydrophila that were differentially expressed under in vivo versus in vitro growth conditions. The gene encoding enolase was among those five genes that were differentially up regulated. Enolase is a glycolytic enzyme and its surface expression was recently shown to be important in the pathogenesis of a gram-positive bacterium Streptococcus pyogenes. By Western blot analysis and Immunogold staining, we demonstrated secretion and surface expression of enolase in A. hydrophila. We also showed that the whole cells of A. hydrophila had strong enolase activity. Using an enzyme-linked immunosorbant assay and sandwich Western blot analysis, we demonstrated binding of enolase to human plasminogen, which is involved in the fibrinolytic system of the host. We cloned the A. hydrophila enolase gene, which exhibited 62% homology at the DNA level and 57% homology at the amino acid level when compared to S. pyogenes enolase. This is a first report describing the increased expression of enolase gene in vivo that could potentially contribute to the pathogenesis of A. hydrophila infections.