Human Autoantigen Research Articles

Autoimmune Diseases and Molecular Mimicry in Tuberculosis.

We analyzed the level of antibodies in 19 patients with pulmonary tuberculosis. In all cases ELISA assays was used. Also, in parallel, we identified 29 similar pentapeptides between key Mtb antigens and human autoantigens. Bioinformatic methods were used in this study. All amino acid sequences of MT antigens and human autoantigens were obtained from the UniProt database, and similar epitopes between Mtb antigens and human autoantigens were identified using the original "Alignmentaj" program. The immunoreactivity of the shared pentapeptides in Mtb antigens was evaluated with use of the IEDB database. The high level of antibodies to modified citrulinated vimentin (anti-MCV) was most frequently detected (57%) in comparison with other antibodies. Elevated levels of antibodies to C3 complement fragments (47%) and rheumatoid factors (21%) in the absence of any rheumatic or autoimmune diseases are noteworthy. Several of the shared pentapeptides belong to the immunoreactive epitopes of Mtb antigens. The bioinformatic data correlated with our earlier studies of the levels of corresponding autoantibodies in the sera of TB patients. Our findings on cross-reactivity and sequence similarity between the Mtb proteins and human autoantigens provide support for the role of antigen mimicry in TB-related autoimmunity.

Epstein-Barr virus as a potentiator of autoimmune diseases.

The Epstein-Barr virus (EBV) is epidemiologically associated with development of autoimmune diseases, including systemic lupus erythematosus, Sjögren syndrome, rheumatoid arthritis and multiple sclerosis. Although there is well-established evidence for this association, the underlying mechanistic basis remains incompletely defined. In this Review, we discuss the role of EBV infection as a potentiator of autoimmune rheumatic diseases. We review the EBV life cycle, viral transcription programmes, serological profiles and lytic reactivation. We discuss the epidemiological and mechanistic associations of EBV with systemic lupus erythematosus, Sjögren syndrome, rheumatoid arthritis and multiple sclerosis. We describe the potential mechanisms by which EBV might promote autoimmunity, including EBV nuclear antigen 1-mediated molecular mimicry of human autoantigens; EBV-mediated B cell reprogramming, including EBV nuclear antigen 2-mediated dysregulation of autoimmune susceptibility genes; EBV and host genetic factors, including the potential for autoimmunity-promoting strains of EBV; EBV immune evasion and insufficient host responses to control infection; lytic reactivation; and other mechanisms. Finally, we discuss the therapeutic implications and potential therapeutic approaches to targeting EBV for the treatment of autoimmune disease.

12622 Molecular Physiology And Compensatory Response In Maladapted Pancreatic Islets Of Humanized Mice Model For Type 1 Diabetes

Abstract Disclosure: A. Hussain: None. A. Aldasouqi: None. S. Rafiqi: None. S.S. Khan: None. R. Paparodis: None. J.C. Jaume: None. S. Imam: None. Genetic predisposition linked with specific HLA (DR and DQ) alleles, environmental factors, and other uncharacterized physiological aberrations triggers an autoimmune attack and depletion of β cells in pancreatic islets, leading to decreased insulin secretion and diabetes. Our laboratory has generated humanized mice carrying the antigen-presenting HLA-DQ8 diabetes-linked haplotype and expressing the human autoantigen GAD65 in pancreatic beta cells. These humanized mice spontaneously develop type 1 diabetes (T1D) and represent the full spectrum of pathophysiological conditions experienced in T1D. Using humanized mice as a model of study, we studied the molecular physiology and compensatory response in maladapted pancreas under normal physiological conditions and hyperglycemic stress of T1D. We studied the differential expression of some important genes by quantitative PCR in maladapted islets to identify the physiological processes affected during the initial oxidative stress exerted by autoimmune conditions. Our results confirmed that levels of cyclin B, cMyc, Cyc D, Cyc E, PDGFRA, and NOTCH are reduced during autoimmune insult, reflecting the poor regenerative capacity of islet cells. However, Cyc A has an elevated expression, reflecting that islet cells, particularly the β cells of Type 1 diabetic mice, may have regenerative potential that may be explored. The genes for Desmin and Survivin showed decreased expression, whereas genes for Smad and Synuclein displayed increased expression. The genes for insulin and somatostatin showed elevated expression, whereas the gene for glucagon displayed reduced expression. The results suggest that during autoimmune insults, the β cells moderately whip up the synthesis of insulin-specific RNA to maintain the requirements. Among the endoplasmic reticulum-specific molecular chaperones, Calnexin showed an elevated expression, whereas calreticulin displayed a reduced expression. Among the genes involved with the architecture of the islet, Lamin and Integrin both display increased expression, reflecting the dynamic change in islet architecture during the autoimmune depletion of β cells. We also investigated the expression of ER-specific stress genes both at RNA and protein levels. Our preliminary results have confirmed that ER-specific stress genes showed an elevated expression during oxidative stress mediated by autoimmune T1D conditions. Presentation: 6/3/2024

Identification of Major Histocompatibility Complex Class II Epitopes From Lyme Autoantigen Apolipoprotein B-100 and Borrelia burgdorferi Mcp4 in Murine Lyme Arthritis.

During infection with the Lyme arthritis (LA) pathogen Borrelia burgdorferi, T-cell responses to both host and pathogen are dysregulated, resulting in chronic infection and frequent development of autoimmunity. To assess CD4+ T-cell epitopes presented during development of LA, we used an unbiased, immunopeptidomics approach to characterize the major histocompatibility complex (MHC) class II immunopeptidome in B burgdorferi-infected C57BL/6 (B6) mice, which develop mild, self-limiting LA, and infected B6 Il10-/- mice, which develop severe, persistent LA at 0, 4, and 16 weeks postinfection (22-23 mice per group). Peptides derived from proteins involved in adaptive T- and B-cell responses and cholesterol metabolism, including human Lyme autoantigen apolipoprotein B-100 (apoB-100), were enriched in infected Il10-/- mice; whereas peptides derived from proteins involved in neutrophil extracellular net formation were enriched in infected B6 mice. Presentation of apoB-100 peptides showed evidence of epitope expansion during infection. Of several identified B burgdorferi peptides, only 1, a methyl-accepting chemotaxis protein peptide Mcp4442-462, was immunogenic. ApoB-100, a human Lyme autoantigen, undergoes marked epitope expansion during LA development. The paucity of immunogenic B burgdorferi epitopes supports previous findings suggesting CD4+ T-cell responses are suppressed in murine LA.

Identification of a mimotope of a complex gp41 Human Immunodeficiency VIrus epitope related to a non-structural protein of Hepacivirus previously implicated in Kawasaki disease.

We have previously isolated a highly mutated VH1-02 antibody termed group C 76-Q13-6F5 (6F5) that targets a conformational epitope on gp41. 6F5 has the capacity to mediate Ab dependent cell cytotoxicity (ADCC). When the VH1-02 group C 76 antibodies variable chain sequence was reverted to germline (76Canc), this still retained ADCC activity. Due to this ability for the 76Canc germline antibody to functionally target this epitope, we sought to identify a protein target for vaccine development. Initially, we interrogated peptide targeting by screening a microarray containing 29,127 linear peptides. Western blot and ELISAs were used to confirm binding and explore human serum targeting. Autoimmune targeting was further interrogated on a yeast-displayed human protein microarray. 76Canc specifically recognized a number of acidic peptides. Meme analysis identified a peptide sequence similar to a non-structural protein of Hepacivirus previously implicated in Kawasaki disease (KD). Binding was confirmed to top peptides, including the Hepacivirus-related and KD-related peptide. On serum competitions studies using samples from children with KD compared to controls, targeting of this epitope showed no specific correlation to having KD. Human protein autoantigen screening was also reassuring. This study identifies a peptide that can mimic the gp41 epitope targeted by 76C group antibodies (i.e. a mimotope). We show little risk of autoimmune targeting including any inflammation similar to KD, implying non-specific targeting of this peptide during KD. Development of such peptides as the basis for vaccination should proceed cautiously.

Hyper-N-glycosylated SEL1L3 as auto-antigenic B-cell receptor target of primary vitreoretinal lymphomas

Primary vitreoretinal lymphoma (PVRL) is a rare subtype of DLBCL and can progress into primary central nervous system lymphoma (PCNSL). To investigate the role of chronic antigenic stimulation in PVRL, we cloned and expressed B-cell receptors (BCR) from PVRL patients and tested for binding against human auto-antigens. SEL1L3, a protein with multiple glycosylation sites, was identified as the BCR target in 3/20 PVRL cases. SEL1L3 induces proliferation and BCR pathway activation in aggressive lymphoma cell lines. Moreover, SEL1L3 conjugated to a toxin killed exclusively lymphoma cells with respective BCR-reactivity. Western Blot analysis indicates the occurrence of hyper-N-glycosylation of SEL1L3 at aa 527 in PVRL patients with SEL1L3-reactive BCRs. The BCR of a PVRL patient with serum antibodies against SEL1L3 was cloned from a vitreous body biopsy at diagnosis and of a systemic manifestation at relapse. VH4-04*07 was used in both lymphoma manifestations with highly conserved CDR3 regions. Both BCRs showed binding to SEL1L3, suggesting continued dependence of lymphoma cells on antigen stimulation. These results indicate an important role of antigenic stimulation by post-translationally modified auto-antigens in the genesis of PVRL. They also provide the basis for a new treatment approach targeting unique lymphoma BCRs with ultimate specificity.

Decoding the relationship between cow's milk proteins and development of type 1 diabetes mellitus.

To analyze in silico the evidence of molecular mimicry between human beta-cell autoantigens and cow's milk proteins as a potential type 1 diabetes mellitus (T1DM) trigger. The in silico analysis was performed using bioinformatics tools to compare the amino acid sequences of cow's milk proteins (bovine serum albumin [BSA] and beta-lactoglobulin [BLG]) and human beta-cell autoantigens (glutamic acid decarboxylase-65 [GAD-65], insulin, and zinc transporter 8 [ZnT8]). The structural and functional characteristics of the proteins were analyzed to identify potential molecular mimicry mechanisms. The results of the in silico analysis showed significant sequence similarity between BSA/BLG and GAD-65/human insulin/ZnT8, ranging from 19.64% to 27.27%. The cow's milk proteins evaluated shared structural features with the beta-cell antigens selected for comparison, indicating a potential for molecular mimicry between these proteins. The findings of this study provide further evidence for a potential role of cow's milk proteins in triggering T1DM. The in silico analysis suggests that molecular mimicry mechanisms between cow's milk proteins and human beta-cell antigens may contribute to the autoimmune response leading to T1DM.

Single-cell RNAseq identifies clonally expanded antigen-specific T-cells following intradermal injection of gold nanoparticles loaded with diabetes autoantigen in humans.

Gold nanoparticles (GNPs) have been used in the development of novel therapies as a way of delivery of both stimulatory and tolerogenic peptide cargoes. Here we report that intradermal injection of GNPs loaded with the proinsulin peptide C19-A3, in patients with type 1 diabetes, results in recruitment and retention of immune cells in the skin. These include large numbers of clonally expanded T-cells sharing the same paired T-cell receptors (TCRs) with activated phenotypes, half of which, when the TCRs were re-expressed in a cell-based system, were confirmed to be specific for either GNP or proinsulin. All the identified gold-specific clones were CD8+, whilst proinsulin-specific clones were both CD8+ and CD4+. Proinsulin-specific CD8+ clones had a distinctive cytotoxic phenotype with overexpression of granulysin (GNLY) and KIR receptors. Clonally expanded antigen-specific T cells remained in situ for months to years, with a spectrum of tissue resident memory and effector memory phenotypes. As the T-cell response is divided between targeting the gold core and the antigenic cargo, this offers a route to improving resident memory T-cells formation in response to vaccines. In addition, our scRNAseq data indicate that focusing on clonally expanded skin infiltrating T-cells recruited to intradermally injected antigen is a highly efficient method to enrich and identify antigen-specific cells. This approach has the potential to be used to monitor the intradermal delivery of antigens and nanoparticles for immune modulation in humans.

Two Decades of Arrayed Imaging Reflectometry for Sensitive, High-Throughput Biosensing.

Arrayed imaging reflectometry (AIR), first introduced in 2004, is a thin-film interference sensor technique that optimizes optical properties (angle of incidence, polarization, substrate refractive index, and thickness) to create a condition of total destructive interference at the surface of a silicon substrate. The advantages of AIR are its sensitivity, dynamic range, multiplex capability, and high-throughput compatibility. AIR has been used for the detection of antibodies against coronaviruses, influenza viruses, Staphylococcus aureus, and human autoantigens. It has also shown utility in detection of cytokines, with sensitivity comparable to bead-based and ELISA assays. Not limited to antibodies or antigens, mixed aptamer and protein arrays as well as glycan arrays have been employed in AIR for differentiating influenza strains. Mixed arrays using direct and competitive inhibition assays have enabled simultaneous measurement of cytokines and small molecules. Finally, AIR has also been used to measure affinity constants, kinetic and at equilibrium. In this review, we give an overview of AIR biosensing technologies and present the latest AIR advances.

ZNF330/NOA36 interacts with HSPA1 and HSPA8 and modulates cell cycle and proliferation in response to heat shock in HEK293 cells

BackgroundThe human genome contains nearly 20.000 protein-coding genes, but there are still more than 6,000 proteins poorly characterized. Among them, ZNF330/NOA36 stand out because it is a highly evolutionarily conserved nucleolar zinc-finger protein found in the genome of ancient animal phyla like sponges or cnidarians, up to humans. Firstly described as a human autoantigen, NOA36 is expressed in all tissues and human cell lines, and it has been related to apoptosis in human cells as well as in muscle morphogenesis and hematopoiesis in Drosophila. Nevertheless, further research is required to better understand the roles of this highly conserved protein.ResultsHere, we have investigated possible interactors of human ZNF330/NOA36 through affinity-purification mass spectrometry (AP-MS). Among them, NOA36 interaction with HSPA1 and HSPA8 heat shock proteins was disclosed and further validated by co-immunoprecipitation. Also, “Enhancer of Rudimentary Homolog” (ERH), a protein involved in cell cycle regulation, was detected in the AP-MS approach. Furthermore, we developed a NOA36 knockout cell line using CRISPR/Cas9n in HEK293, and we found that the cell cycle profile was modified, and proliferation decreased after heat shock in the knocked-out cells. These differences were not due to a different expression of the HSPs genes detected in the AP-MS after inducing stress.ConclusionsOur results indicate that NOA36 is necessary for proliferation recovery in response to thermal stress to achieve a regular cell cycle profile, likely by interaction with HSPA1 and HSPA8. Further studies would be required to disclose the relevance of NOA36-EHR interaction in this context.

Expanded presentation of Lyme autoantigens and identification of a novel immunogenic CD4+ T cell epitope from Borrelia burgdorferiMCP4 in murine Lyme arthritis

Abstract Lyme arthritis (LA), caused by Borrelia burgdorferi (Bb), is often accompanied by autoimmune T and B cell responses, but the mechanisms of infection-induced autoimmunity are unclear. We used an immunopeptidomics approach to identify potential Lyme autoantigens and immunogenic Bb antigens, which were validated by histology and testing of T cell reactivity. C57BL/6 (B6) mice, which develop mild inflammatory LA, and B6 Il10−/− (IL10 KO) mice, which develop severe, persistent LA, were infected with Bb for 4 or 16 weeks, and MHCII-bound peptides from inguinal and popliteal lymph nodes were identified by LC-MS/MS. Joint inflammation, fibrosis, and vascular remodeling were analyzed by H&E, Masson’s trichrome, and anti-CD31 immunohistochemistry, respectively. Six Bb peptides were identified by LC-MS/MS, of which one epitope from methyl-accepting chemotaxis protein 4 (MCP4) was an immunogenic CD4+ T cell antigen. Over 10,000 self peptides, particularly from proteins involved in cholesterol metabolism, tissue damage, and vascular inflammation were identified in infected mice. Presentation of peptides from previously identified human Lyme autoantigens apolipoprotein B-100, fibronectin, and type V collagen were expanded in infected mice, suggestive of epitope spreading. Consistent with immunopeptidomics data, joints showed increased inflammatory infiltrate, fibrosis and neovascularization in infected mice, compared with joints from uninfected mice. In conclusion, this immunopeptidomics approach revealed key insights into potential mechanisms of infection-induced autoimmunity in LA and indentified a novel immunogenic CD4+ T cell antigen from Bb MCP4. Supported by grants from NIAID (R21AI148982)

Post-COVID Endocrine Disorders: Putative Role of Molecular Mimicry and Some Pathomorphological Correlates.

In order to identify corresponding amino acid sequences (pentapeptides) between the SPs, MPs and NPs of human coronaviruses and human autoantigens targeted in autoimmune endocrinopathies, and for a comparative analysis of the various coronaviruses proteome and the proteome of human, the original computer program was used. Quantitatively, SP, MP and NP of the human coronaviruses were found to share totally 117 minimal immune pentapeptide epitopes: 79 in SP, 14 in MP and 24 in NP, - with 18 autoantigens expressed by human endocrinocytes. The shared pentapeptides belong to the proteins of human endocrine cells. Samples of the pituitary, adrenal and thyroid from patients who died from coronavirus infection (COVID-19) were studied morphologically using histochemical methods. A high incidence of SARS-CoV-2 infection of endocrine cells was showed. The high affinity of SARS-CoV-2 the cells of the adenohypophysis was revealed, but there was no expression of viral proteins by the cells of the neurohypophysis. The foci of lesions in endocrine organs contained abundant lymphocytic infiltrates which may indicate the impact of autoimmune processes. Autoimmune disorders have a multi-faceted etiology and depend on polygenic predispose and additive action of many epigenetic and environmental factors causing hyperstimulation of imperfectly functioning immune system. It means that the phenomenon of molecular mimicry cannot be blamed as their single prerequisite, but it is just a tile in mosaic of autoimmunity. The facts revealed emphasize the need of endocrinological diagnostic alertness of a physician while observing patients with post-vaccination and post-COVID-19 health disorders.

Mechanisms of autoimmune pathology in post-COVID syndrome

One of the delayed consequences of SARS-CoV-2 infection is post-acute COVID-19 – polymorphic disorders of various organ systems that affect COVID-19 convalescents and persist for more than four weeks after an acute infection. Due to the infectious nature of the COVID-19, we would like to pay special attention to complications from the immune system, especially concomitant and new-onset autoimmune pathology. This review analyzes the current state of the issue of post-acute COVID-19 complications, discusses the molecular features of the SARS-CoV-2 virus and the mechanisms underlying the impaired immune response during acute COVID-19 infection and the occurrence of autoimmune and autoinflammatory conditions during convalescence. Particular attention is paid to the molecular mimicry of antigenic determinants of the SARS-CoV-2 virus, which are structurally similar to the epitopes of human autoantigens. The current data on post-acute COVID-19 autoimmune complications from humoral immunity and the endocrine system, as well as reproductive disorders faced by male patients are presented. For the first time, we hypothesize a role of the structural homology of the human SOX13 autoantigen (HMG box factor SOX13) associated with diabetes mellitus and SARS-CoV-2 envelope (E) protein in the development of the post-acute COVID-19 autoimmune pathologies. Due to the structural similarity of the two proteins and the overlap of their immunogenic regions, we suggest that the increased risk of developing diabetes mellitus and reproductive disorders in men after suffering from COVID-19 may be associated with immunological cross-reactivity.

Prediction of molecular mimicry between proteins from Trypanosoma sp. and human antigens associated with systemic lupus erythematosus

The immune response against pathogens induces protection from future infection, however, molecular mimicry between the pathogen and the human host can promote autoreactive responses. Using in silico approaches, we identified molecular mimicry between Trypanosoma sp. and human autoantigens involved in the development of systemic lupus erythematosus (SLE). We retrieved all reported autoantigen amino acid sequences for SLE from the AAgAtlas database to perform PSI-BLAST against the Trypanosoma sp proteome to determine amino acid sequence identity with each other. The antigens given in the Protein Data Bank without a 3D structure were modeled by homology with the "Swiss Modeller Server". Epitopes shared between Trypanosoma sp. and human antigens were identified using the Ellipro server and the Immune Epitope Database (IEDB), and cross-reactive epitopes were assigned to the 3D models. 36 autoantigens involved in SLE showed molecular mimicry with Trypanosoma sp. Antigens Epitope prediction revealed that some autoantigens shared several antigenic.

Autoimmunity to Sphingosine-1-Phosphate-Receptors in Systemic Sclerosis and Pulmonary Arterial Hypertension.

ContextPulmonary arterial hypertension (PAH) is a frequent extracutaneous manifestation of systemic sclerosis (SSc). PAH is characterized by increased vasomotor tone, progressive remodeling of pulmonary arteries and arterioles, consequentially increased pulmonary vascular resistance, right heart hypertrophy, and eventually right ventricular failure. Autoimmunity against G-protein coupled receptors (GPCRs) has been implicated in the development of SSc-associated PAH. Sphingosine-1-phosphate (S1P) receptors (S1PR) present a potential, yet so far untested antigen for PAH autoimmunity, given the documented role of S1P/S1PR signaling in PAH pathogenesis.ObjectiveWe hypothesized that S1P receptors (S1PR) may constitute autoantigens in human patients, and that the prevalence of autoantibodies (aAb) to S1PR1, S1PR2 and S1PR3 is elevated in SSc patients and associated with PAH.MethodsFor this exploratory study, serum samples from 158 SSc patients, 58 of whom with PAH, along with 333 healthy control subjects were screened for S1PR-aAb. S1PR1-3 were expressed as fusion proteins with luciferase in human embryonic kidney cells and used to establish novel in-vitro assays for detecting and quantifying S1PR-aAb. The fusion proteins were incubated with serum samples, the aAb-S1PR complexes formed were precipitated by protein-A, washed and tested for luciferase activity. Commercial anti-S1PR-antibodies were used to verify specificity of the assays.ResultsAll three assays showed dose-dependent signal intensities when tested with S1PR-subtype specific commercial antibodies. Natural aAb to each S1PR were detected in healthy controls with a prevalence of <10% each, i.e., 2.7% for S1PR1-aAb, 3.6% for S1PR2-aAb, and 8.3% for S1PR3. The respective prevalence was higher in the cohort of SSc patients without PAH, with 17.1% for S1PR1-aAb, 19.0% for S1PR2-aAb, and 21.5% for S1PR3. In the subgroup of SSc patients with PAH, prevalence of aAb to S1PR2 and S1PR3 was further elevated to 25.9% for S1PR2-aAb, and 27.6% for S1PR3. Notably, the majority of patients with positive S1PR2-aAb (60.7%) or S1PR3-aAb (71.9%) displayed interstitial lung disease.ConclusionS1PR1–3 can constitute autoantigens in humans, particularly in SSC patients with PAH. The potential pathophysiological significance for the etiology of the disease is currently unknown, but the elevated prevalence of S1PR2-aAb and S1PR3-aAb in SSC patients with PAH merits further mechanistic investigations.

Molecular mimicry among human proteinase 3 and bacterial antigens: implications for development of c-ANCA associated vasculitis.

Wegener's granulomatosis is an autoimmune disease where autoantibodies target human autoantigen PR3, a serine protease locates on the neutrophil membrane. This disease affects blood small vessels and could be deadly. The origin of these autoantibodies is unknown, but infections have been implicated with autoimmune disease. In this study, we explored potential molecular mimicry between human PR3 and homologous pathogens through in silico analysis. Thirteen serine proteases from human pathogens (Klebsiella pneumoniae, Acinetobacter baumannii, Salmonella sp., Streptococcus suis, Vibrio parahaemolyticus, Bacteroides fragilis, Enterobacter ludwigii, Vibrio alginolyticus, Staphylococcus haemolyticus, Enterobacter cloacae, Escherichia coli and Pseudomonas aeruginosa) shared structural homology and amino acid sequence identity with human PR3. Epitope prediction found an only conserved epitope IVGG, located between residues 59-74. However, multiple alignments showed conserved regions that could be involved in cross-reactivity between human and pathogens serine proteases (90-98, 101-108, 162-169, 267 and 262 residues positions). In conclusion, this is the first report providing in silico evidence about the existence of molecular mimicry between human and pathogens serine proteases, that could explain the origins of autoantibodies found in patients suffering from Wegener's granulomatosis.

Serum autoantibodyome reveals that healthy individuals share common autoantibodies

SUMMARYAutoantibodies are a hallmark of both autoimmune disease and cancer, but they also occur in healthy individuals. Here, we perform a meta-analysis of nine datasets and focus on the common autoantibodies shared by healthy individuals. We report 77 common autoantibodies based on the protein microarray data obtained from probing 182 healthy individual sera on 7,653 human proteins and an additional 90 healthy individual sera on 1,666 human proteins. There is no gender bias; however, the number of autoantibodies increase with age, plateauing around adolescence. We use a bioinformatics pipeline to determine possible molecular-mimicry peptides that can contribute to the elicitation of these common autoantibodies. There is enrichment of intrinsic properties of proteins like hydrophilicity, basicity, aromaticity, and flexibility for common autoantigens. Subcellular localization and tissue-expression analysis reveal that several common autoantigens are sequestered from the circulating autoantibodies.

Guillain-Barré Syndrome in the COVID-19 Pandemic.

There have been several reported cases of severe acute respiratory syndrome (SARS-CoV-2) infection that were associated with an increased incidence of neurological manifestations, including Guillain–Barré syndrome (GBS). This review aims to present information on the reports of GBS associated with coronavirus disease 2019 (COVID-19) infection. Our review is retrospective work examining articles published from the 1 April 2020 to the 8 May 2021 in the English language. We used the diagnostic criteria and classification published by the National Institute of Neurological Disorders and Stroke and Brighton Collaboration. GBS is usually a postinfectious syndrome, but GBS in the COVID-19 pandemic also takes on a para-infectious profile. In the reports, the genetic factor has a role in developing GBS in some patients. In conclusion, the association between COVID-19 and GBS is not very clear. Still, one mechanism is strongly associated with COVID-19 and immune-mediated neurological complications, which is molecular mimicry between SARS-CoV-2 and human autoantigens.

Development of a New Murine Model of Type 2 Autoimmune Hepatitis Using a Human Liver Protein

Autoimmune hepatitis (AIH) is a chronic inflammatory condition of the liver characterized by parenchymal destruction, hypergammaglobulinemia, specific autoantibody production, and hepatic fibrosis and necrosis. Murine models of AIH have been described; however, little is known about the immunologic mechanisms of tissue destruction. In this study, a new murine model of type 2 AIH was developed using recombinant human cytochrome P450 (CYP) 2D6 emulsified with complete Freund's adjuvant (CFA). BALB/c mice were immunized with 2 μg/mL i.p. of CYP2D6 in CFA. The control group received CFA or phosphate-buffered saline alone. Alanine aminotransferase activity, autoantibody production, IgG concentrations, histologic damage, and specific T-cell response were evaluated. Persistent AIH, characterized by cellular infiltration, hepatic fibrosis, elevated alanine aminotransferase, and the production of anti-liver kidney microsomal antibody type 1 developed in CFA/CYP2D6-immunized mice. These mice presented high levels of IgG and its subclasses IgG1, IgG2a, and IgG2b against liver self-proteins. Interestingly, IL-2+ and interferon γ-positive Cyp2d6-specific T cells were present in greater concentrations in mice immunized with CFA/CYP2D6 compared with control. Immunization with CFA, in combination with a natural human autoantigen like CYP2D6, was demonstrated to break tolerance, resulting in a chronic form of autoimmune-related liver damage. This murine model of type 2 AIH is expected to be instrumental in understanding the immunologic mechanisms of the pathogenesis of this autoimmune liver disease.

Oligoclonal IgGs against DNA, Histones, and Myelin Basic Protein in the Cerebrospinal Fluid of Patients with Multiple Sclerosis

Multiple Sclerosis (MS) is known as a chronic demyelinating pathology of the central nervous system. The most accepted MS pathogenesis theory assigns the main role to demyelination of myelin-proteolipid shells due to inflammationrelated with autoimmune reactions. One of the features of MS patients is the enhanced synthesis of oligoclonal IgGs in the bone marrow Cerebrospinal Fluid (CSF). By antigen-specific immunoblotting after isoelectrofocusing of IgGs, oligoclonal IgGs in CSF of MS patients were revealed only against the components of Epstein-Barr virus and Chlamydia. However, there was still unknown to which human auto-antigens in MS patients oligoclonal IgGs may be produced. Here it was first shown that in the CSF of a narrow percentage of MS patients, oligoclonal IgGs are produced against their own antigens: DNA (24% patients), histones (20%), and myelin basic protein (12%). At the same time, the CSF of MS patients contains a very large amount of auto-IgGs-abzymes that hydrolyze DNA, histones, and myelin basic protein, which during isofocusing, are distributed throughout the gel from pH 3 to 10. It is concluded that these multiple IgGs-abzymes, which are dangerous to humans since stimulate development of MS, in the main are non-oligoclonal antibodies.