Annexin A2 as a target endothelial cell membrane autoantigen in Behçet's disease

Innate immune responses in Behçet disease and relapsing polychondritis

Behçet disease (BD) and relapsing polychondritis (RP) are chronic multisystem disorders characterized by recurrent flare-ups of tissue inflammation. Major clinical manifestations of BD are oral aphthae, genital aphthous ulcers, skin lesions, arthritis, and uveitis. Patients with BD may develop rare but serious neural, intestinal, and vascular complications, with high relapse rates. Meanwhile, RP is characterized by the inflammation of the cartilaginous tissues of the ears, nose, peripheral joints, and tracheobronchial tree. Additionally, it affects the proteoglycan-rich structures in the eyes, inner ear, heart, blood vessels, and kidneys. The mouth and genital ulcers with inflamed cartilage (MAGIC) syndrome is a common characteristic of BD and RP. The immunopathology of these two diseases may be closely related. It is established that the genetic predisposition to BD is related to the human leukocyte antigen (HLA)-B51 gene. Skin histopathology demonstrates the overactivation of innate immunity, such as neutrophilic dermatitis/panniculitis, in patients with BD. Monocytes and neutrophils frequently infiltrate cartilaginous tissues of patients with RP. Somatic mutations in UBA1, which encodes a ubiquitylation-related enzyme, cause vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic syndrome (VEXAS) with severe systemic inflammation and activation of myeloid cells. VEXAS prompts auricular and/or nasal chondritis, with neutrophilic infiltration around the cartilage in 52-60% of patients. Thus, innate immune cells may play an important role in the initiation of inflammatory processes underlying both diseases. This review summarizes the recent advances in our understanding of the innate cell-mediated immunopathology of BD and RP, with a focus on the common and distinct features of these mechanisms.

Mucocutaneous manifestations of Behçet's disease: Pathogenesis and management from perspectives of vasculitis

Behçet's disease (BD) is a systemic inflammatory disorder characterized by vasculitis affecting blood vessels of any caliber or type. It can present with a wide spectrum of vasculitic lesions, including erythema nodosum-like lesions and retinal vasculitis, and may also lead to larger vessel diseases, such as aortic aneurysm and deep vein thrombosis. The full etiology of BD remains unclear, but it is considered a polygenetic disease with multiple genetic risk factors that promote immune dysregulation and thrombophilia. Inflammation can be triggered by environmental factors, such as bacteria or viruses, and the dysregulation of innate and adaptive immune cell subsets. Neutrophils and lymphocytes are the primary players involved in BD pathogenesis, with specific innate (i.e., neutrophil-derived reactive oxygen species and neutrophil extracellular traps) and adaptive (i.e., anti-endothelial cell antibodies) processes inducing endothelial cell activation and chemotaxis of inflammatory cells, leading to coagulation and vasculitis. These inflammation-induced vasculitic or vasculopathic features are observed in most mucocutaneous BD lesions, although vasculitis per se is often pathologically evident only during a brief period of the disease process. Due to the multifactorial nature of BD-associated inflammation, broad-spectrum anti-inflammatory medications, including glucocorticoids and immunosuppressive drugs, have been the mainstay for managing BD. In addition, inhibitors of interleukin (IL)-1, tumor necrosis factor (TNF)-α, and IL-17, which target innate and adaptive immune functions dysregulated in BD, have emerged as promising new therapeutics. In this review, we discuss the muco-cutaneous manifestations of BD by focusing on the underlying vasculitic components in their pathologies, as well as the current array of treatment options.

Annexin A2: The Diversity of Pathological Effects in Tumorigenesis and Immune Response

Annexin A2 (ANXA2) is widely used as a marker in a variety of tumors. By regulating multiple signal pathways, ANXA2 promotes the epithelial-mesenchymal transition, which can cause tumorigenesis and accelerate thymus degeneration. The elevated ANXA2 heterotetramer facilitates the production of plasmin, which participates in pathophysiologic processes such as tumor cell invasion and metastasis, bleeding diseases, angiogenesis, inducing the expression of inflammatory factors. In addition, the ANXA2 on the cell membrane mediates immune response via its interaction with surface proteins of pathogens, C1q, toll-like receptor 2, anti-dsDNA antibodies and immunoglobulins. Nuclear ANXA2 plays a role as part of a primer recognition protein complex that enhances DNA synthesis and cells proliferation by acting on the G1-S phase of the cell. ANXA2 reduction leads to the inhibition of invasion and metastasis in multiple tumor cells, bleeding complications in acute promyelocytic leukemia, retinal angiogenesis, autoimmunity response and tumor drug resistance. In this review, we provide an update on the pathological effects of ANXA2 in both tumorigenesis and the immune response. We highlight ANXA2 as a critical protein in numerous malignancies and the immune host response.

Fc receptors gone wrong: A comprehensive review of their roles in autoimmune and inflammatory diseases

Systemic autoimmune and inflammatory diseases have a complex and only partially known pathophysiology with various abnormalities involving all the components of the immune system. Among these components, antibodies, and especially autoantibodies are key elements contributing to autoimmunity. The interaction of antibody fragment crystallisable (Fc) and several distinct receptors, namely Fc receptors (FcRs), have gained much attention during the recent years, with possible major therapeutic perspectives for the future. The aim of this review is to comprehensively describe the known roles for FcRs (activating and inhibitory FcγRs, neonatal FcR [FcRn], FcαRI, FcεRs, Ro52/tripartite motif containing 21 [Ro52/TRIM21], FcδR, and the novel Fc receptor-like [FcRL] family) in systemic autoimmune and inflammatory disorders, namely rheumatoid arthritis, Sjögren's syndrome, systemic lupus erythematosus, systemic sclerosis, idiopathic inflammatory myopathies, mixed connective tissue disease, Crohn's disease, ulcerative colitis, immunoglobulin (Ig) A vasculitis, Behçet's disease, Kawasaki disease, IgG4-related disease, immune thrombocytopenia, autoimmune hemolytic anemia, antiphospholipid syndrome and heparin-induced thrombocytopenia.

The important roles and molecular mechanisms of annexin A2 autoantibody in children with nephrotic syndrome

BACKGROUND

In recent years, B-cell dysfunction has been found to play an important role in the pathogenesis of primary nephrotic syndrome (PNS). B cells play a pathogenic role by secreting antibodies against their target antigens after transforming into plasma cells. Therefore, this study aimed to screen the autoantibodies that cause PNS and explore their pathogenic mechanisms.

METHODS

Western blotting and mass spectrometry were employed to screen and identify autoantibodies against podocytes in children with PNS. Both in vivo and in vitro experiments were used to study the pathogenic mechanism of PNS. The results were confirmed in a large multicenter clinical study in children.

RESULTS

Annexin A2 autoantibody was highly expressed in children with PNS with a pathological type of minimal change disease (MCD) or focal segmental glomerulosclerosis without genetic factors. The mouse model showed that anti-Annexin A2 antibody could induce proteinuria in vivo. Mechanistically, the effect of Annexin A2 antibody on the Rho signaling pathway was realized through promoting the phosphorylation of Annexin A2 at Tyr24 on podocytes by reducing its binding to PTP1B, which led to the cytoskeletal rearrangement and damage of podocytes, eventually causing proteinuria and PNS.

CONCLUSIONS

Annexin A2 autoantibody may be responsible for some cases of PNS with MCD/FSGS in children.

Plasma membrane integrity: implications for health and disease

Plasma membrane integrity is essential for cellular homeostasis. In vivo, cells experience plasma membrane damage from a multitude of stressors in the extra- and intra-cellular environment. To avoid lethal consequences, cells are equipped with repair pathways to restore membrane integrity. Here, we assess plasma membrane damage and repair from a whole-body perspective. We highlight the role of tissue-specific stressors in health and disease and examine membrane repair pathways across diverse cell types. Furthermore, we outline the impact of genetic and environmental factors on plasma membrane integrity and how these contribute to disease pathogenesis in different tissues.

Chlorogenic acid inhibits the proliferation of human lung cancer A549 cell lines by targeting annexin A2 in vitro and in vivo

Chlorogenic acid, an important active component of coffee with anti-tumor activities, has been found for a hundred years. However, the lack of understanding about its target proteins greatly limits the exploration of its anti-tumor molecular mechanisms and clinical applications. Here, in vitro and animal experiments showed that chlorogenic acid had a significant inhibitory effect on the proliferation of A549 cells. The ability of chlorogenic acid to naturally emit fluorescence was exploited to screen its target proteins while avoiding false positives brought about by chemical modifications when using fluorescent tags. Consequently, we identified and verified annexin A2 as a covalent binding target of chlorogenic acid in A549 cells. We also discovered that chlorogenic acid inhibits the binding of annexin A2 to p50 subunit thereby inhibiting the expression of downstream anti-apoptotic genes cIAP1 and cIAP2 of the NF-κB signaling pathway in A549 cells in vitro and in vivo. Moreover, we found that chlorogenic acid hindered the binding of annexin A2 to actin possibly causing inhibition of tumor cell cycle and migration. Thus, this work demonstrates that chlorogenic acid binds annexin A2, causing a decrease in the expression of NF-κB downstream anti-apoptotic genes, and inhibiting the proliferation of A549 cells in vivo and in vitro.

Circulation autoantibodies against C-terminus of NuMA in patients with Behçet's disease

Circulating autoantibodies have a close association with autoimmune diseases, which may be seen even in healthy individuals. These are also considered as promising source of new biomarkers in various autoimmune diseases. However, their profile is not completely understood till now. Here, we evaluated autoantibodies against nuclear mitotic apparatus protein located at the carboxy terminus (C-NuMA)in blood circulation of Han Chinese patients, using different technical approaches to discover pathological reaction leading to Behçet's disease (BD). In the first step, the recombinant human carboxy-terminal region of NuMA peptide (C-NuMA) was over-expressed and purified. In the second step, the indirect immunofluorescence method was used with patients' sera, and commercial anti-NuMA antibody was used to determine the NuMA as a potential autoantigen. Results were confirmed at cell level by western blots, indicating that two of ten patients with Behçet's disease could react with the recombinant C-NuMA,and the presence of antibodies were further verified by immunoprecipitation technique. Finally, the corresponding immunoassay (ELISA) was developed and optimized with specific recombinant C-NuMA as an in vitro method to test the confirmed patients with Behçet's disease. Our findings demonstrated that C-terminus of NuMA is an immune target of Behçet's disease in Han Chinese patients.

Moesin expression is correlated with its involvement in patients with Behcet's disease

INTRODUCTION

Behcet's disease (BD) is a rare, chronic autoimmune disorder of unknown etiology. Although the profile of autoantibodies for this disease is not yet completely understood, because of better disease recognition, its prevalence is increasing throughout the world. Among ERM proteins (ezrin/radixin/moesin), moesin is a member of a family which is involved in autoimmune diseases. The aim of this study is to confirm whether moesin is a potential anti-endothelial cell autoantigen (AECA) in Hans Chinese BD patients.

MATERIAL AND METHODS

First, a full length recombinant human moesin protein was over-expressed and purified. Second, it was identified by mass spectrometry and then purified moesin was used to perform Western blotting, immunoprecipitation and ELISA with confirmed BD patients. Finally, in vitro cytotoxicity experiments were conducted with anti-moesin antibodies by the resazurin reduction assay method.

RESULTS

: Purified moesin protein was successfully expressed and then its antigenicity was confirmed by Western blotting and immunoprecipitation techniques. Anti-moesin antibodies were detected in approximately one-third (38%) of BD patients by ELISA and the reactivity of BD serum IgG antibodies against moesin was found to be significantly higher than HC (p < 0.0001). Moreover, in order to validate our results, cytotoxicity experiments also confirmed that anti-moesin antibody had a significant inhibitory effect on endothelial cell activity.

CONCLUSIONS

Expression is correlated with the involvement of moesin as an autoantigen in BD pathology, which is a new finding. It might be a new candidate biomarker in the Han Chinese population.

Reciprocal regulation of pro-inflammatory Annexin A2 and anti-inflammatory Annexin A1 in the pathogenesis of rheumatoid arthritis

Annexin A2 has been implicated in several immune modulated diseases including Rheumatoid arthritis (RA) pannus formation. The most relied treatment option for RA pathogenesis is glucocorticoids. Glucocorticoids regulate the synthesis, phosphorylation and cellular deposition of Annexin A1. This annexin mediates the anti-inflammatory actions of glucocorticoids. These two first characterized members of annexin superfamily proteins acts reciprocally, one as an anti-inflammatory and the other proinflammatory in nature. The possibility of these molecules as soluble biomarkers and as an upstream regulator of major cytokine devastation at RA microenvironment has not been previously explored. Current study elucidates the reciprocal regulation of these two annexins in RA pathogenesis. These Annexin A2/A1 and downstream cytokines in RA serum were analysed by ELISA. Western blot, Immunocytochemistry, immunoprecipitation and Immunohistochemistry were adapted to analyse these molecules in tissue and synovial fibroblasts and also in different experimental conditions. Significant increase in the level of Annexin A2 was noticed in naïve RA patients compared to controls (14.582 ± 1.766 ng/ml vs. 7.37 ± 1.450 ng/ml; p ≤ 0.001). In remission cases significant low levels was detected. On the contrary, significant decrease in the level of Annexin A1 was noticed in naïve RA patients compared to healthy controls (12.322 ± 2.91 vs. 16.998 ± 4.298 ng/ml; p ≤ 0.001), wherein remission cases serum Annexin A1 was significantly high. The knockdown of proinflammatory Annexin A2 by siRNA/antibody treatment could mimic the glucocorticoid treatment as which induced cellular Annexin A1 and membrane translocation resulting in the terminal action. Current data elucidating the regulatory interplay between Annexin A2 and Annexin A1 in RA pathogenesis.

PGK1 as an immune target in Kawasaki disease

Kawasaki disease (KD) is an immune-mediated vasculitis with symptoms that mimic febrile illness; the immune origin has been suggested but never proved. First, cell chip technology was used to screen immune targets cells. With the indirect immunofluorescence assay we found that the HeLa cell chip could be recognized by KD patient serum samples. The target cell proteome was extracted as antigens, and antigen recognition reaction was performed using the patients' serum as antibodies and the detected target protein was detected and identified as phosphoglycerate kinase 1 (PGK1). Then PGK1 was produced and tested with enzyme-linked immunosorbent assay (ELISA), Western blotting, immunoprecipitation and competitive inhibition immunofluorescence assay. Immunoglobulin (Ig)G against PGK1 was detected in 46% (23 of 50) sera of KD patients, 13% (five of 38) sera in febrile non-KD patients (FC) and 2·6% (one of 38) sera in healthy donors. As an immune target, PGK1 not only helps understanding of the pathogenesis, it also has potential value in facilitating the laboratory diagnosis of KD.

Expression correlates between Annexin A1 and A2 autoantibodies in patients with Behçet's disease

The autoantibodies profile of Behçet’s disease (BD) is yet incompletely understood. Annexins are a family of highly conserved proteins which are involved in some human autoimmune diseases. Autoantibodies directed toward Annexin A1 and A2 are involved in BD pathology, but correlation in their clinical role is controversial. The aim of our study is to estimate and evaluate the expression correlation between Annexin A1 and A2 autoantibodies in BD patients. We have designed and implemented different technical approaches to prove the hypothesis. First, bioinformatics tools such as amino acid sequence alignment, epitope prediction analysis, and 3D structural comparison were performed to find out the correlation between Annexin A1 and A2. Second, amplification of the corresponding gene by RT-PCR, then cloning, and purification techniques were applied to acquire the recombinant Annexin A1. Third, the target protein band was excised from gel electrophoresis, digested with trypsin, and analyzed by MALDI-TOF/TOF. Finally, in-house ELISA was developed to determine the induced anti-Annexin A1 autoantibodies in BD patients. Obtained results demonstrated that the BD serum reactivity against recombinant Annexin A1 was significantly higher as compared with healthy control (HC) (P<0.001). Moreover, bioassay results of Annexin A1 and A2 also showed the presence, absence, and independent coexistence of autoantibodies, when reacted with BD sera. In conclusion, Annexin A1 has a similar immunogenic expression and correlation with its analog Annexin A2 and their association may be a novel immune target of BD in Han Chinese population.

Immunoproteomics technologies in the discovery of autoantigens in autoimmune diseases

Proteomics technologies are often used for the identification of protein targets of the immune system. Here, we discuss the immunoproteomics technologies used for the discovery of autoantigens in autoimmune diseases where immune system dysregulation plays a central role in disease onset and progression. These autoantigens and associated autoantibodies can be used as potential biomarkers for disease diagnostics, prognostics and predicting/monitoring drug responsiveness (theranostics). Here, we compare a variety of methods such as mass spectrometry (MS)-based [serological proteome analysis (SERPA), antibody mediated identification of antigens (AMIDA), circulating immune complexome (CIC) analysis, surface enhanced laser desorption/ionization-time of flight (SELDI-TOF)], nucleic acid based serological analysis of antigens by recombinant cDNA expression cloning (SEREX), phage immunoprecipitation sequencing (PhIP-seq) and array-based immunoscreening (proteomic microarrays), luciferase immunoprecipitation systems (LIPS), nucleic acid programmable protein array (NAPPA) methods. We also review the relevance of immunoproteomic data generated in the last 10 years, with a focus on the aforementioned MS based methods.

Photo, pH and redox multi-responsive nanogels for drug delivery and fluorescence cell imaging

A light, pH and redox triple-responsive spiropyran-based nanogel is prepared and applied for the efficient delivery of anticancer drugs and fluorescence cell imaging for the strong emission of merocyanine photoisomers.

Annexin A2, autoimmunity, anxiety and depression

OBJECTIVES

Antiphospholipid syndrome (APS) is associated with neurological manifestations and one of the novel autoantigens associated with this disease is Annexin A2 (ANXA2). In this work we have examined the effect of high levels of autoantibodies to ANXA2 on the brain in a mouse model.

METHODS

Recombinant ANXA2 emulsified in adjuvant was used to immunize mice while mice immunized with adjuvant only served as controls. At peak antibody levels the animal underwent behavioral and cognitive tests and their brains were examined for ANXA2 immunoglobulin G (IgG) and expression of ANXA2 and the closely linked protein p11.

RESULTS

Very high levels of anti-ANXA2 antibodies (Abs) were associated with reduced anxiety in the open field 13.14% ± 0.89% of the time in the center compared to 8.64% ± 0.91% observed in the control mice (p < 0.001 by t-test). A forced swim test found significantly less depression manifested by immobility in the ANXA2 group. The changes in behavior were accompanied by a significant reduction in serum corticosteroid levels of ANXA2 group compared to controls. Moreover, higher levels of total IgG and p11 expression were found in ANXA2 group brains. Lower levels of circulating anti-ANXA2 Abs were not associated with behavioral changes.

CONCLUSIONS

We have established an animal model with high levels of anti-ANXA2 Abs which induced IgG accumulation in the brain and specific anxiolytic and anti-depressive effects. This model promises to further our understanding of autoimmune disease such as APS and to provide better understanding of the role of the ANXA2-p11 complex in the brain.

HnRNP A1 is Involved in Deep Vein Thrombosis Patients with Behçet's Disease

Objective

The aim of this study was to verify the hypothesis originated from bioinformatics and literature reviews that hnNRP A1 may be a new immune target of Behçet's disease (BD).

Methods

First, bioinformatics was used to show the correlation between hnRNP A1 and A2/B1 in amino acid sequences and three dimensional structures. Second, hnRNP A1 was expressed, purified, and immunologically confirmed by systematic immunology methods including: Western blotting, immunoprecipitation and Dot-ELISA. Then, ELISA was used to screen the anti-hnRNP A1 autoantibodies in newly confirmed clinical samples and the clinical significance was compared between anti-hnRNP A1 antibody positive and negative groups. Finally, the endothelial cells antigen profile of one anti-hnRNP A1 antibody positive BD patient was detected using immunoprecipitation with liquid chromatography tandem mass spectrometry (LC–TMS).

Results

In total 720 subjects enrolled and tested in this study. Our results demonstrated hnRNP A1 as a new immune target of BD. The reactivity of BD serum IgG antibodies against hnRNP A1 was significantly higher than healthy controls (P < 0.0001), and deep vein thrombosis (DVT) showed a significant higher in the anti-hnRNP A1 antibodies positive group (P < 0.05).

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Bioinformatics was used to predict that hnRNP A1 may play a role in BD.

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HnRNP A1 was immunologically confirmed as an autoantigen of BD.

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Deep vein thrombosis has a close relationship with anti-hnRNP A1 antibody in patients' blood circulation.

Behçet's disease (BD) is a chronic systemic autoimmune disease. The pathogenesis of BD is still not clear, and the diagnosis is based on typical clinical syndromes. Autoantigen identification was considered a key to solve this problem. This study was to verify the hypothesis suggested by bioinformatics that hnRNP A1 may be a new autoantigen of BD. Among the 720 subjects enrolled and systemic tested, our results demonstrated hnRNP A1 as a new autoantigen of BD, and associated with deep vein thrombosis.