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

Representing core gene expression activity relationships using the latent structure implicit in Bayesian networks

MOTIVATION

Many types of networks, such as co-expression or ChIP-seq-based gene-regulatory networks, provide useful information for biomedical studies. However, they are often too full of connections and difficult to interpret, forming "indecipherable hairballs."

RESULTS

To address this issue, we propose that a Bayesian network can summarize the core relationships between gene expression activities. This network, which we call the LatentDAG, is substantially simpler than conventional co-expression network and ChIP-seq networks (by two orders of magnitude). It provides clearer clusters, without extraneous cross-cluster connections, and clear separators between modules. Moreover, one can find a number of clear examples showing how it bridges the connection between steps in the transcriptional regulatory network and other networks (e.g. RNA-binding protein). In conjunction with a graph neural network, the LatentDAG works better than other biological networks in a variety of tasks, including prediction of gene conservation and clustering genes.

AVAILABILITY AND IMPLEMENTATION

Code is available at https://github.com/gersteinlab/LatentDAG.

Structural and Functional Changes in Non-Paraneoplastic Autoimmune Retinopathy

BACKGROUND

To describe longitudinal changes in patients with non-paraneoplastic autoimmune retinopathy (npAIR) by utilizing different diagnostic modalities/tests.

METHODS

The index study is a retrospective longitudinal review of sixteen eyes of eight patients from a tertiary care eye hospital diagnosed with npAIR. Multiple diagnostic modalities such as wide-angle fundus photography (WAFP), WA fundus autofluorescence (WAFAF), spectral-domain optical coherence tomography (SD-OCT), Goldmann visual field (GVF) perimetry, microperimetry (MP), electrophysiologic testing, and adaptive optics scanning laser ophthalmoscopy (AOSLO) were reviewed and analyzed.

RESULTS

At the baseline visits, anomalies were detected by multimodal diagnostic tests on all patients. Subjects were followed up for a median duration of 11.5 [3.0-18.7] months. Structural changes at the baseline were detected in 14 of 16 (87.5%) eyes on WAFP and WAFAF and 13 of 16 (81.2%) eyes on SD-OCT. Eight of the ten (80%) eyes that underwent AOSLO imaging depicted structural changes. Functional changes were detected in 14 of 16 (87.5%) eyes on GVF, 15 of 16 (93.7%) eyes on MP, and 11 of 16 (68.7%) eyes on full-field electroretinogram (ff-ERG). Multifocal electroretinogram (mf-ERG) and visual evoked potential (VEP) tests were performed in 14 eyes, of which 12 (85.7%) and 14 (100%) of the eyes demonstrated functional abnormalities, respectively, at baseline. Compared to all the other structural diagnostic tools, AOSLO had a better ability to demonstrate deterioration in retinal microstructures occurring at follow-ups. Functional deterioration at follow-up was detected on GVF in 8 of 10 (80%) eyes, mf-ERG in 4 of 8 (50%) eyes, and MP in 7 of 16 (43.7%) eyes. The ff-ERG and VEP were stable in the majority of cases at follow-up.

CONCLUSIONS

The utilization of multimodal imaging/tests in the diagnosing and monitoring of npAIR patients can aid in identifying anomalous changes over time. Analysis of both the anatomical and functional aspects by these devices can be supportive of detecting the changes early in such patients. AOSLO shows promise as it enables the capture of high-resolution images demonstrating quantifiable changes to retinal microstructure.

Metabolomic and proteomic analyses of primary Sjogren's syndrome

The pathogenesis of primary Sjogren's syndrome (pSS) has not been fully elucidated. We explored differentially expressed proteins and metabolic pathways in pSS using proteomics and metabolomics. 456 named proteins in total were identified, among which 50 were significantly changed in the pSS. Altered proteins were significantly associated with signaling pathways such as antigen processing and presentation, human immunodeficiency virus 1 infection, and FC gamma R-mediated phagocytosis. Meanwhile, 12 proteins, such as SH3BGRL3, TPM4, and CA1, can be used as potential clinical molecular markers. Moreover, 128 metabolites were significantly expressed in the pSS group. A total of 96 pathways were significantly enriched including central carbon metabolism in cancer, taurine and hypotaurine metabolism, and ABC transporters. Notably, both proteomics and metabolomics enriched glycolysis/gluconeogenesis metabolism, pentose phosphate pathway, and glutathione metabolism pathways. In this study, the progression mechanism of pSS was analyzed and novel biomarkers were identified by proteomics and metabolomics.

Systemic Blood Proteome Patterns Reflect Disease Phenotypes in Neovascular Age-Related Macular Degeneration

There is early evidence of extraocular systemic signals effecting function and morphology in neovascular age-related macular degeneration (nAMD). The prospective, cross-sectional BIOMAC study is an explorative investigation of peripheral blood proteome profiles and matched clinical features to uncover systemic determinacy in nAMD under anti-vascular endothelial growth factor intravitreal therapy (anti-VEGF IVT). It includes 46 nAMD patients stratified by the level of disease control under ongoing anti-VEGF treatment. Proteomic profiles in peripheral blood samples of every patient were detected with LC-MS/MS mass spectrometry. The patients underwent extensive clinical examination with a focus on macular function and morphology. In silico analysis includes unbiased dimensionality reduction and clustering, a subsequent annotation of clinical features, and non-linear models for recognition of underlying patterns. The model assessment was performed using leave-one-out cross validation. The findings provide an exploratory demonstration of the link between systemic proteomic signals and macular disease pattern using and validating non-linear classification models. Three main results were obtained: (1) Proteome-based clustering identifies two distinct patient subclusters with the smaller one (n = 10) exhibiting a strong signature for oxidative stress response. Matching the relevant meta-features on the individual patient's level identifies pulmonary dysfunction as an underlying health condition in these patients. (2) We identify biomarkers for nAMD disease features with Aldolase C as a putative factor associated with superior disease control under ongoing anti-VEGF treatment. (3) Apart from this, isolated protein markers are only weakly correlated with nAMD disease expression. In contrast, applying a non-linear classification model identifies complex molecular patterns hidden in a high number of proteomic dimensions determining macular disease expression. In conclusion, so far unconsidered systemic signals in the peripheral blood proteome contribute to the clinically observed phenotype of nAMD, which should be examined in future translational research on AMD.

[Relationship between anti-ENO1 antibody and systemic lupus erythematosus patients with retinopathy]

OBJECTIVE

To build bridges between anti-α enolase antibody (anti-enolase 1 antibody, anti-ENO1 antibody) and common clinical and laboratory characteristics of systemic lupus erythematosus (SLE) and to analyze the role of anti-ENO1 antibody in the evaluation of SLE disease activity.

METHODS

The SLE patients with retinopathy and without retinopathy were enrolled in the study, as well as healthy individuals whose gender and age matched with those of the SLE patients. Serum anti-ENO1 antibodies were measured using enzyme-linked immunosorbent assay (ELISA), presenting as intra-group positive rate and arbitrary units (AU) value. Clinical and laboratory data were obtained from medical records.

RESULTS

The SLE retinopathy patients represented various fundus abnormalities. Ranked by percentage, the top three retinopathies were retinal hemorrhage (14/32, 43.75%), cotton-wool spots (8/32, 25.00%) and retinal vein occlusion (3/32, 9.38%). Among the 32 SLE retinopathy patients, 13 (40.63%) suffered from two or more fundus abnormalities. The positive rate and AU value of the SLE patients were higher than of the SLE patients without retinopathy (68.75% vs. 46.00%, P=0.043; 16.11%±10.35% vs. 12.06%±6.47%, P=0.045). Besides, the positive rate and AU value of the two SLE groups were both significantly higher than those of the healthy control group (P < 0.001). Compared with the SLE-without-retinopathy group, the systemic lupus erythematosus disease activity index (SLEDAI)-2000 of the SLE retinopathy patients were significantly higher than those of the SLE patients without retinopathy (17.41±4.25 vs. 9.48±5.35, P < 0.001). Dividing all the SLE patients into an anti-ENO1-positive group and an anti-ENO1-negative group, we found that anti-ENO1-positive was more likely to be correlated to developing fever and positive result of urine occult blood (P=0.011, P=0.042). Comparing with the patients with negative anti-ENO1 antibodies, the patients with positive anti-ENO1 antibodies had significantly higher erythrocyte sedimentation rate (ESR) [the median (range) was 29.50 (1.52-110.00) mg/L vs. 12.00 (4.00-101.00) mg/L, P=0.001], higher immunoglobulin G (IgG) [the median (range) was 14.30 (4.02-37.80) g/L vs. 10.46 (2.50-25.73) g/L, P=0.000 3], and higher blood platelet count (PLT) [(205.87×10⁹±67.98×10⁹) /L vs. (164.57×10⁹±69.57×10⁹) /L, P=0.008], as well as higher immunoglobulin A (IgA) [the median (range) was 2.85 (0.07-27.00) g/L vs. 2.05 (0.42-4.36) g/L, P=0.014].

CONCLUSION

The positive rate and AU value of anti-ENO1 antibody suggested higher SLE disease activity and they were elevated in SLE and SLE retinopathy.

Correlation of photoreceptor damage with anti-retina antibodies level in aqueous humor in macular edema patients

This study aimed to investigate the correlation between the severity of photoreceptor damage and the level of anti-retina antibodies (ARAs) in aqueous humor, including recoverin, CA II and enolase-α IgG antibody of macular edema patients. Aqueous humor samples were collected from macular edema patients and from cataract patients. Patients were divided into three groups according to the severity of discontinuity of ellipsoid zone (EZ) shown on optical coherence tomography (OCT) imaging: cataract patients with intact EZ, macular edema patients with mild EZ damage, and macular edema patients with severe EZ damage. The level of ARAs was determined with enzyme-linked immunosorbent assay (ELISA). The correlation between the level of ARAs and the degree of photoreceptor damage was analyzed. The level of ARAs of the intact EZ group was significantly lower than that in the severely damaged group (P < 0.05). The level of recoverin IgG of the intact EZ group was significantly lower than mildly damaged group (P = 0.030). In a subgroup analysis, the level of recoverin IgG of DME patients was correlated with their central retinal thickness (CRT) (r = 0.462, P = 0.035). The level of ARAs in aqueous humor of patients with DME and RVO-ME was correlated with the degree of photoreceptor damage.

Biomarkers of autoimmunity and beta cell metabolism in type 1 diabetes

Posttranslational protein modifications (PTMs) are an inherent response to physiological changes causing altered protein structure and potentially modulating important biological functions of the modified protein. Besides cellular metabolic pathways that may be dictated by PTMs, the subtle change of proteins also may provoke immune attack in numerous autoimmune diseases. Type 1 diabetes (T1D) is a chronic autoimmune disease destroying insulin-producing beta cells within the pancreatic islets, a result of tissue inflammation to specific autoantigens. This review summarizes how PTMs arise and the potential pathological consequence of PTMs, with particular focus on specific autoimmunity to pancreatic beta cells and cellular metabolic dysfunction in T1D. Moreover, we review PTM-associated biomarkers in the prediction, diagnosis and in monitoring disease activity in T1D. Finally, we will discuss potential preventive and therapeutic approaches of targeting PTMs in repairing or restoring normal metabolic pathways in pancreatic islets.

Evidence for the Rapid and Divergent Evolution of Mycoplasmas: Structural and Phylogenetic Analysis of Enolases

Mycoplasmas are a group of prokaryotes without cell walls that have evolved through several rounds of degenerative evolution. With a low cell DNA G + C content and definitively long genetic lineages, mycoplasmas are thought to be in a state of rapid evolution. However, little associated evidence has been provided. Enolase is a key enzyme in glycolysis that is widely found in all species from the three domains, and it is evolutionarily conserved. In our previous studies, enolase acted as a virulence factor and participated in cell-surface adhesion in Mycoplasma hyopneumoniae. Furthermore, unique loop regions were first found in the crystal structure of Mhp Eno. Here, enolase structures from Mycoplasma pneumoniae and Mycoplasma bovis were determined. An extra helix 7 is specific and conservatively found in almost all mycoplasma enolases, as confirmed by crystal structures and sequence alignment. Particular motifs for helix 7, which is composed of F-K/G-K-L/F-K-X-A-I, have been proposed and could be regarded as molecular markers. To our surprise, the genetic distances between any two mycoplasma enolases were obviously longer than those between the two corresponding species themselves, indicating divergent evolution of mycoplasma enolases, whereas no horizontal gene transfer was detected in mycoplasma enolase genens. Furthermore, different evolutionary patterns were adopted by different loop regions of mycoplasma enolase. Enolases from different Mycoplasma species also showed different affinities for PLG and fibronectin. Our results indicate the rapid and divergent evolution of mycoplasma enolase and mycoplasmas. This study will also aid understanding the independent evolution of Mycoplasma species after separation from their common ancestor.

Identification of novel autoantigens as potential biomarkers in juvenile idiopathic arthritis associated uveitis

BACKGROUND

Many children with juvenile idiopathic arthritis (JIA) have autoantibodies, targeting nuclear components (anti-nuclear antibodies, ANA). ANA in JIA is associated with uveitis, an eye inflammation which may cause permanent vision impairment if not detected and treated. However, ANA-testing is neither specific nor sensitive enough to be a clinically reliable predictor of uveitis risk, and the precise autoantigens targeted by ANA in JIA are largely unknown. If identified, specific autoantibodies highly associated with uveitis could be used as biomarkers to facilitate identification of JIA patients at risk.

METHODS

Antibodies from six ANA-positive, oligoarticular JIA patients, with and without uveitis, were explored by two large-scale methods: (1) screening against 42,100 peptides on an autoimmunity profiling planar array, and (2) immunoprecipitations from cell lysates with antigen identification by mass spectrometry. Three hundred thirty-five peptide antigens, selected from proteins identified in the large-scale methods and the scientific literature were investigated using a bead-based array in a cohort of 56 patients with oligoarticular- or RF-negative polyarticular JIA, eight of which were having current or previous uveitis.

RESULTS

In the planar array, reactivity was detected against 332 peptide antigens. The immunoprecipitations identified reactivity towards 131 proteins. Only two proteins were identified by both methods. In the bead-based array of selected peptide antigens, patients with uveitis had a generally higher autoreactivity, seen as higher median fluorescence intensity (MFI) across all antigens, compared to patients without uveitis. Reactivity towards 17 specific antigens was significantly higher in patients with uveitis compared to patients without uveitis. Hierarchical clustering revealed that patients with uveitis clustered together.

CONCLUSION

This study investigated autoantigens in JIA and uveitis, by combining two exploratory methods and confirmation in a targeted array. JIA patients with current or a history of uveitis had significantly higher reactivity towards 17 autoantigens and a generally higher autoreactivity compared to JIA patients without uveitis. Hierarchical clustering suggests that a combination of certain autoantibodies, rather than reactivity towards one specific antigen, is associated with uveitis. Our analysis of autoantibodies associated with uveitis in JIA could be a starting point for identification of prognostic biomarkers useful in JIA clinical care.

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

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

Multifunctional Fructose 1,6-Bisphosphate Aldolase as a Therapeutic Target

Fructose 1,6-bisphosphate aldolase is a ubiquitous cytosolic enzyme that catalyzes the fourth step of glycolysis. Aldolases are classified into three groups: Class-I, Class-IA, and Class-II; all classes share similar structural features but low amino acid identity. Apart from their conserved role in carbohydrate metabolism, aldolases have been reported to perform numerous non-enzymatic functions. Here we review the myriad "moonlighting" functions of this classical enzyme, many of which are centered on its ability to bind to an array of partner proteins that impact cellular scaffolding, signaling, transcription, and motility. In addition to the cytosolic location, aldolase has been found the extracellular surface of several pathogenic bacteria, fungi, protozoans, and metazoans. In the extracellular space, the enzyme has been reported to perform virulence-enhancing moonlighting functions e.g., plasminogen binding, host cell adhesion, and immunomodulation. Aldolase's importance has made it both a drug target and vaccine candidate. In this review, we note the several inhibitors that have been synthesized with high specificity for the aldolases of pathogens and cancer cells and have been shown to inhibit classical enzyme activity and moonlighting functions. We also review the many trials in which recombinant aldolases have been used as vaccine targets against a wide variety of pathogenic organisms including bacteria, fungi, and metazoan parasites. Most of such trials generated significant protection from challenge infection, correlated with antigen-specific cellular and humoral immune responses. We argue that refinement of aldolase antigen preparations and expansion of immunization trials should be encouraged to promote the advancement of promising, protective aldolase vaccines.

Autoantibody profiles and clinical association in Thai patients with autoimmune retinopathy

Autoimmune retinopathy (AIR) is a rare immune-mediated inflammation of the retina. The autoantibodies against retinal proteins and glycolytic enzymes were reported to be involved in the pathogenesis. This retrospective cohort study assessed the antiretinal autoantibody profiles and their association with clinical outcomes of AIR patients in Thailand. We included 44 patients, 75% were females, with the overall median age of onset of 48 (17-74, IQR 40-55.5) years. Common clinical presentations were nyctalopia (65.9%), blurred vision (52.3%), constricted visual field (43.2%), and nonrecordable electroretinography (65.9%). Underlying malignancy and autoimmune diseases were found in 2 and 12 female patients, respectively. We found 41 autoantibodies, with anti-α-enolase (65.9%) showing the highest prevalence, followed by anti-CAII (43.2%), anti-aldolase (40.9%), and anti-GAPDH (36.4%). Anti-aldolase was associated with male gender (P = 0.012, OR 7.11, 95% CI 1.54-32.91). Anti-CAII showed significant association with age of onset (P = 0.025, 95% CI - 17.28 to - 1.24), while anti-α-enolase (P = 0.002, OR 4.37, 95% CI 1.83-10.37) and anti-GAPDH (P = 0.001, OR 1.87, 95% CI 1.32-2.64) were significantly associated with nonrecordable electroretinography. Association between the antibody profiles and clinical outcomes may be used to direct and adjust the treatment plans and provide insights in the pathogenesis of AIR.

Alpha-enolase involvement in intestinal and extraintestinal manifestations of celiac disease

Celiac disease is a life-long intestinal autoimmune disease, characterized by the gluten intolerance and chronic enteric inflammation. Traditionally presented by intestinal manifestations, however, a shift toward extra intestinal presentation is taking place. One of the affected organs is the nervous systems presented by neuropsychiatric manifestations, hence the mechanism and pathways are not clear. The presence of neuronal and alpha-enolases and their corresponding antibodies were noticed in the mucosa and serum of celiac disease patients, as well as in other various autoimmune diseases with psycho-neurological manifestations. The aims of the present review are to screen the literature on different isoforms of enolase, mainly alpha enolase, and their specific antibodies and to suggest their potential pathophysiological mechanisms relaying the enolases to intestinal or extraintestinal celiac disease manifestations. The shared aspects between the enolases and celiac disease and the cross-talks between alpha-enolase and tissue transglutaminase suggest new potential pathophysiological mechanisms that might drive celiac disease evolvement.

Moonlighting Proteins: The Case of the Hexokinases

Moonlighting proteins are defined as proteins with two or more functions that are unrelated and independent to each other, so that inactivation of one of them should not affect the second one and vice versa. Intriguingly, all the glycolytic enzymes are described as moonlighting proteins in some organisms. Hexokinase (HXK) is a critical enzyme in the glycolytic pathway and displays a wide range of functions in different organisms such as fungi, parasites, mammals, and plants. This review discusses HXKs moonlighting functions in depth since they have a profound impact on the responses to nutritional, environmental, and disease challenges. HXKs’ activities can be as diverse as performing metabolic activities, as a gene repressor complexing with other proteins, as protein kinase, as immune receptor and regulating processes like autophagy, programmed cell death or immune system responses. However, most of those functions are particular for some organisms while the most common moonlighting HXK function in several kingdoms is being a glucose sensor. In this review, we also analyze how different regulation mechanisms cause HXK to change its subcellular localization, oligomeric or conformational state, the response to substrate and product concentration, and its interactions with membrane, proteins, or RNA, all of which might impact the HXK moonlighting functions.

Alpha-Enolase: Emerging Tumor-Associated Antigen, Cancer Biomarker, and Oncotherapeutic Target

Alpha-enolase, also known as enolase-1 (ENO1), is a glycolytic enzyme that “moonlights” as a plasminogen receptor in the cell surface, particularly in tumors, contributing to cancer cell proliferation, migration, invasion, and metastasis. ENO1 also promotes other oncogenic events, including protein-protein interactions that regulate glycolysis, activation of signaling pathways, and resistance to chemotherapy. ENO1 overexpression has been established in a broad range of human cancers and is often associated with poor prognosis. This increased expression is usually accompanied by the generation of anti-ENO1 autoantibodies in some cancer patients, making this protein a tumor associated antigen. These autoantibodies are common in patients with cancer associated retinopathy, where they exert pathogenic effects, and may be triggered by immunodominant peptides within the ENO1 sequence or by posttranslational modifications. ENO1 overexpression in multiple cancer types, localization in the tumor cell surface, and demonstrated targetability make this protein a promising cancer biomarker and therapeutic target. This mini-review summarizes our current knowledge of ENO1 functions in cancer and its growing potential as a cancer biomarker and guide for the development of novel anti-tumor treatments.

Effect of aflibercept on proliferative vitreoretinopathy: Proteomic analysis in an experimental animal model

PURPOSE

The aim of this study was to monitor inflammatory, proliferative and progressive effects of proliferative vitreoretinopathy (PVR) and aflibercept treatment in dispase induced PVR rat model by proteomic analysis.

MATERIAL AND METHODS

A total of 35 male Long Evans pigmented rats were divided into three groups, namely, PVR (dispase+saline), PVR+aflibercept (dispase+aflibercept) and control. The PVR group received 2 μl of 0.03 IU/μl dispase and 2 μl saline, the PVR+aflibercept group received 2 μl of 0.03 IU/μl and 2 μl of 40 mg/ml aflibercept at the first day of the experiment. At the end of the 6th week all retina and vitreous specimens were collected by evisceration and transferred to the proteomics laboratory for analysis. Proteomic analysis by 2D gel electrophoresis coupled with MALDI-TOF/TOF was performed.

RESULTS

In the PVR and PVR+aflibercept group 16 different proteins that were identified to be differentially regulated in comparison to the control group. In the PVR+aflibercept group, ENO1, ENO2, LDH-B, PEBP-1 and GS levels were higher than the PVR group. In addition, the association of proteins such as UCHL, PEBP1, PDHB and ENO1 with PVR has been demonstrated for the first time.

CONCLUSION

STRING analysis elucidated the functional protein-protein interaction among the differentially regulated proteins and highlighted that those proteins mainly played roles in carbon and nucleotide metabolisms. Functional analysis of the differentially regulated proteins indicated the presence of inflammation, gliosis and retinal damage in the PVR group. Aflibercept treatment had pronounced effect on prevention of inflammation and retinal damage while causing a slight increase in gliosis. However, aflibercept treatment was not effective enough to normalize the levels of differentially regulated proteins of the PVR group. Therefore, we predict that the treatment dose of aflibercept used in this study was below of its ideal concentration and should be increased in the future studies. The differential regulation of these structural proteins in this study should shed some light to the mechanism of glial wound formation in the retina and guide future treatment modalities.

Using bioinformatic protein sequence similarity to investigate if SARS CoV-2 infection could cause an ocular autoimmune inflammatory reactions?

Although severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) infection have emerged globally, findings related to ocular involvement and reported cases are quite limited. Immune reactions against viral infections are closely related to viral and host proteins sequence similarity. Molecular Mimicry has been described for many different viruses; sequence similarities of viral and human tissue proteins may trigger autoimmune reactions after viral infections due to similarities between viral and human structures. With this study, we aimed to investigate the protein sequence similarity of SARS CoV-2 with retinal proteins and retinal pigment epithelium (RPE) surface proteins. Retinal proteins involved in autoimmune retinopathy and retinal pigment epithelium surface transport proteins were analyzed in order to infer their structural similarity to surface glycoprotein (S), nucleocapsid phosphoprotein (N), membrane glycoprotein (M), envelope protein (E), ORF1ab polyprotein (orf1ab) proteins of SARS CoV-2. Protein similarity comparisons, 3D protein structure prediction, T cell epitopes-MHC binding prediction, B cell epitopes-MHC binding prediction and the evaluation of the antigenicity of peptides assessments were performed. The protein sequence analysis was made using the Pairwise Sequence Alignment and the LALIGN program. 3D protein structure estimates were made using Swiss Model with default settings and analyzed with TM-align web server. T-cell epitope identification was performed using the Immune Epitope Database and Analysis (IEDB) resource Tepitool. B cell epitopes based on sequence characteristics of the antigen was performed using amino acid scales and HMMs with the BepiPred 2.0 web server. The predicted peptides/epitopes in terms of antigenicity were examined using the default settings with the VaxiJen v2.0 server. Analyses showed that, there is a meaningful similarities between 6 retinal pigment epithelium surface transport proteins (MRP-4, MRP-5, RFC1, SNAT7, TAUT and MATE) and the SARS CoV-2 E protein. Immunoreactive epitopic sites of these proteins which are similar to protein E epitope can create an immune stimulation on T cytotoxic and T helper cells and 6 of these 9 epitopic sites are also vaxiJen. These result imply that autoimmune cross-reaction is likely between the studied RPE proteins and SARS CoV-2 E protein. The structure of SARS CoV-2, its proteins and immunologic reactions against these proteins remain largely unknown. Understanding the structure of SARS CoV-2 proteins and demonstration of similarity with human proteins are crucial to predict an autoimmune response associated with immunity against host proteins and its clinical manifestations as well as possible adverse effects of vaccination.

Benefits of BCG-induced metabolic switch from oxidative phosphorylation to aerobic glycolysis in autoimmune and nervous system diseases

The most commonly used vaccine worldwide, bacillus Calmette-Guerin (BCG), appears to have the ability to restore blood sugar control in humans with early-onset but long-duration type 1 diabetes when a repeat vaccination strategy is used. This is a process that may be driven by a metabolic switch from overactive oxidative phosphorylation to accelerated aerobic glycolysis and a reset of the immune system. BCG is a live, attenuated strain of Mycobacteria bovis, a cousin of M. tuberculosis. Humans and Mycobacteria, which are found in the environment and in warm-blooded hosts, share a long coevolutionary history. In recent times, humans have had fewer exposures to these and other microorganisms that historically helped shape the immune response. By 're-introducing' an attenuated form of Mycobacteria via BCG vaccination, humans might benefit from an immunological perspective, a concept supported by a growing body of data in autoimmunity and robust data on the nonspecific immune effects of BCG related to protection from diverse infections and early mortality. New findings of immune and metabolic defects in type 1 diabetes that can be corrected with repeat BCG vaccination suggest that this therapeutic strategy may be applicable in other diseases with inadequate aerobic glycolysis, including Parkinson's disease, dementia, depression and other disorders affecting the nervous system.

Ocular Paraneoplastic Syndromes

Ocular-involving paraneoplastic syndromes present a wide variety of clinical symptoms. Understanding the background pathophysiological and immunopathological factors can help make a more refined differential diagnosis consistent with the signs and symptoms presented by patients. There are two main pathophysiology arms: (1) autoimmune pathomechanism, which is presented with cancer-associated retinopathy (CAR), melanoma-associated retinopathy (MAR), cancer-associated cone dysfunction (CACD), paraneoplastic vitelliform maculopathy (PVM), and paraneoplastic optic neuritis (PON), and (2) ectopic peptides, which is often caused by tumor-expressed growth factors (T-exGF) and presented with bilateral diffuse uveal melanocytic proliferation (BDUMP). Meticulous systematic analysis of patient symptoms is a critical diagnostic step, complemented by multimodal imaging, which includes fundus photography, optical coherent tomography, fundus autofluorescence, fundus fluorescein angiography, electrophysiological examination, and sometimes fundus indocyjanin green angiography if prescribed by the clinician. Assessment of the presence of circulating antibodies is required for diagnosis. Antiretinal autoantibodies are highly associated with visual paraneoplastic syndromes and may guide diagnosis by classifying clinical manifestations in addition to monitoring treatment.

Occurrence of major anti-retinal autoantibodies associated with paraneoplastic autoimmune retinopathy

Autoantibodies (AAbs) against retinal antigens can be found in patients with cancer and unexplained vision loss unrelated to the cancer metastasis. Cancer-associated retinopathy (CAR) is a rare paraneoplastic visual syndrome mediated by AAbs. Our goal was to determine whether CAR patients with different malignancies have a specific AAb or repertoire of AAbs that could serve as biomarkers for retinal disease. We found AAbs against 12 confirmed retinal antigens, with α-enolase being the most frequently recognized. The significant finding of the study was a high incidence of anti-aldolase AAbs in colon-CAR, anti-CAII in prostate-CAR, and anti-arrestin in skin melanoma patients thus these AAbs could serve as biomarkers in the context of clinical presentation and could support the diagnosis of CAR. However, a lack of AAb restriction to any one antigenic protein or to one retinal cellular location makes screening for a CAR biomarker challenging.

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.

Occurrence of major anti-retinal autoantibodies associated with paraneoplastic autoimmune retinopathy

Autoantibodies (AAbs) against retinal antigens can be found in patients with cancer and unexplained vision loss unrelated to the cancer metastasis. Cancer-associated retinopathy (CAR) is a rare paraneoplastic visual syndrome mediated by AAbs. Our goal was to determine whether CAR patients with different malignancies have a specific AAb or repertoire of AAbs that could serve as biomarkers for retinal disease. We found AAbs against 12 confirmed retinal antigens, with α-enolase being the most frequently recognized. The significant finding of the study was a high incidence of anti-aldolase AAbs in colon-CAR, anti-CAII in prostate-CAR, and anti-arrestin in skin melanoma patients thus these AAbs could serve as biomarkers in the context of clinical presentation and could support the diagnosis of CAR. However, a lack of AAb restriction to any one antigenic protein or to one retinal cellular location makes screening for a CAR biomarker challenging.

Immune Cell Infiltration into the Eye Is Controlled by IL-10 in Recoverin-Induced Autoimmune Retinopathy

Autoimmune retinopathy (AIR) is a treatable condition that manifests in acute and progressive vision loss in patients. It has recently been determined that AIR is associated with an imbalance of T_H1 versus regulatory T cell immunity toward the retinal protein, recoverin. This study describes a new murine model to understand the immunopathology of AIR and its association with T cell responses toward recoverin. Immunization of C57BL/6 mice with recoverin resulted in ocular inflammation including infiltration of CD4⁺ and CD8⁺ T lymphocytes, B cells, and CD11b⁺Ly6C⁺ inflammatory monocytes in the eyes. Production of IFN-γ and IL-17 from T cells was exacerbated in IL-10 knockout (KO) mice and kinetics of disease development was accelerated. Infiltration of T cells and inflammatory monocytes into the eyes dramatically increased in recoverin-immunized IL-10 KO mice. An immunodominant peptide of recoverin, AG-16, was capable of inducing disease in IL-10 KO mice and resulted in expansion of AG-16 tetramer-specific CD4⁺ T cells in lymphoid organs and eyes. Adoptive transfer of recoverin-stimulated cells into naive mice was sufficient to induce AIR, and immunization of B cell-deficient mice led to a milder form of the disease. This model supports the hypothesis that recoverin-specific T cell responses are major drivers of AIR pathogenesis and that IL-10 is an important factor in protection.

Beneath the Retinal Pigment Epithelium: Histopathologic Findings in Metastatic Extranodal Natural Killer/T-Cell Lymphoma, Nasal Type

Purpose

To report a case of extranodal natural killer/T-cell lymphoma (ENKTCL), nasal type metastatic to the space beneath the retinal pigment epithelium (RPE) with coincident paraneoplastic lymphoma-associated retinopathy.

Methods

Findings of clinical and histopathologic examination are presented with differential diagnoses and a literature review.

Case Report

A 53-year-old man presented with bilateral blindness and had exudative retinal detachments overlying subretinal masses in both eyes. Flow cytometry of pericardial fluid revealed malignant T lymphocytes. After two cycles of chemotherapy, the patient was hospitalized and quickly expired. Autopsy revealed lymphoma involving the eyes, heart, right lung, and two subcarinal lymph nodes focally. Histopathologic examination of the eyes revealed intraocular metastases from ENKTCL, nasal type. Expression of CD3 and CD56, along with expression of Epstein-Barr virus by in situ hybridization, confirmed the diagnosis. Lymphomatous infiltrates were confined to the space beneath the neurosensory retina and between the RPE and the Bruch membrane, sparing the uveal tissue, similar to other metastatic T-cell lymphomas. Extensive RPE and photoreceptor loss in regions with and without underlying tumor was typical of a concurrent paraneoplastic lymphoma-associated retinopathy.

Conclusion

Patients diagnosed with ENKTCL should be evaluated by an ophthalmologist, as ophthalmic involvement portends a poor prognosis.

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

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

Elevated serum levels of IL-6 and CXCL9 in autoimmune retinopathy (AIR) patients

Autoimmune retinopathy (AIR) is a rare immune-mediated retinopathy associated with circulating antiretinal antibodies (ARAs). Other prominent features of AIR include visual field deficits and photoreceptor dysfunction in the setting of progressive unexplained vision loss. The role of inflammation is poorly understood in AIR. Since cytokines play a central role in the initiation and development of inflammation, we evaluated the presence of proinflammatory cytokines and chemokines in AIR patient sera. We demonstrate that IL-6 and CXCL9 are both elevated in AIR patient sera. Moreover, the presence and concentration of these 2 molecules appear to correlate with AIR patient disease severity. This cytokine profile, IL-6 and CXCL9, has been described to participate in a variety of autoimmune and inflammatory diseases. Our study provides support for an activated inflammatory process in AIR and identifies possible mechanisms that can drive autoimmunity in this disease.

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IL-6 and CXCL9 are both elevated in AIR patient sera.

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The presence and concentration of IL-6 and CXCL9 correlate with AIR patient disease severity.

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These cytokines may play a prominent role in the initiation and development of inflammation and autoimmunity.

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The data provides evidence for activated inflammatory processes in AIR.