A journey to your self: The vague definition of immune self and its practical implications.

The identification of immunogenic peptides has become essential in an increasing number of fields in immunology, ranging from tumor immunotherapy to vaccine development. The nature of the adaptive immune response is shaped by the similarity between foreign and self-protein sequences, a concept extensively applied in numerous studies. Can we precisely define the degree of similarity to self? Furthermore, do we accurately define immune self? In the current work, we aim to unravel the conceptual and mechanistic vagueness hindering the assessment of self-similarity. Accordingly, we demonstrate the remarkably low consistency among commonly employed measures and highlight potential avenues for future research.

1H, 13C, and 15N resonance assignments of the La Motif of the human La-related protein 1.

Human La-related protein 1 (HsLARP1) is involved in post-transcriptional regulation of certain 5' terminal oligopyrimidine (5'TOP) mRNAs as well as other mRNAs and binds to both the 5'TOP motif and the 3'-poly(A) tail of certain mRNAs. HsLARP1 is heavily involved in cell proliferation, cell cycle defects, and cancer, where HsLARP1 is significantly upregulated in malignant cells and tissues. Like all LARPs, HsLARP1 contains a folded RNA binding domain, the La motif (LaM). Our current understanding of post-transcriptional regulation that emanates from the intricate molecular framework of HsLARP1 is currently limited to small snapshots, obfuscating our understanding of the full picture on HsLARP1 functionality in post-transcriptional events. Here, we present the nearly complete resonance assignment of the LaM of HsLARP1, providing a significant platform for future NMR spectroscopic studies.

Coexisting presentation of two rare genetic variants of autosomal dominant polycystic kidney disease and Alport syndrome.

Alport syndrome and autosomal dominant polycystic kidney disease are monogenic causes of chronic kidney disease and end-stage kidney failure. We present a case of a man in his 60s with progressive chronic kidney disease, bilateral sensorineural hearing loss and multiple renal cysts. Genetic analysis revealed a heterozygous variant in COL4A3 (linked to Alport syndrome) and in the GANAB gene (associated with a milder form of autosomal dominant polycystic kidney disease). Although each variant confers a mild risk of developing end-stage kidney disease, the patient presented a pronounced and accelerated progression of chronic kidney disease, which goes beyond what would be predicted by adding up their individual effects. This suggests a potential synergic effect of both variants, which warrants further investigation.

Precise Targeting of Autoantigen-Specific B Cells in Lupus Nephritis with Chimeric Autoantibody Receptor T Cells.

Despite conventional therapy, lupus nephritis (LN) remains a significant contributor to short- and long-term morbidity and mortality. B cell abnormalities and the production of autoantibodies against nuclear complexes like anti-dsDNA are recognised as key players in the pathogenesis of LN. To address the challenges of chronic immunosuppression associated with current therapies, we have engineered T cells to express chimeric autoantibody receptors (DNA-CAART) for the precise targeting of B cells expressing anti-dsDNA autoantibodies. T cells from LN patients were transduced using six different CAAR vectors based on their antigen specificity, including alpha-actinin, histone-1, heparan sulphate, or C1q. The cytotoxicity, cytokine production, and cell-cell contact of DNA-CAART were thoroughly investigated in co-culture experiments with B cells isolated from patients, both with and without anti-dsDNA positivity. The therapeutic effects were further evaluated using an in vitro immune kidney LN organoid. Among the six proposed DNA-CAART, DNA4 and DNA6 demonstrated superior selectively cytotoxic activity against anti-dsDNA+ B cells. Notably, DNA4-CAART exhibited improvements in organoid morphology, apoptosis, and the inflammatory process in the presence of IFNα-stimulated anti-dsDNA+ B cells. Based on these findings, DNA4-CAART emerge as promising candidates for modulating autoimmunity and represent a novel approach for the treatment of LN.

Altered EBV specific immune control in multiple sclerosis.

Since the 1980s it is known that immune responses to the Epstein-Barr virus (EBV) are elevated in multiple sclerosis (MS) patients. Recent seroepidemiologial data have shown that this alteration after primary EBV infection identifies individuals with a more than 30-fold increased risk to develop MS. The mechanisms by which EBV infection might erode tolerance for the central nervous system (CNS) in these individuals, years prior to clinical MS onset, remain unclear. In this review I will discuss altered frequencies of EBV life cycle stages and their tissue distribution, EBV with CNS autoantigen cross-reactive immune responses and loss of immune control for autoreactive B and T cells as possible mechanisms. This discussion is intended to stimulate future studies into these mechanisms with the aim to identify candidates for interventions that might correct EBV specific immune control and/or resulting cross-reactivities with CNS autoantigens in MS patients and thereby ameliorate disease activity.

Antigen-specific immunotherapy via delivery of tolerogenic dendritic cells for multiple sclerosis.

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system resulting from loss of immune tolerance. Many disease-modifying therapies for MS have broad immunosuppressive effects on peripheral immune cells, but this can increase risks of infection and attenuate vaccine-elicited immunity. A more targeted approach is to re-establish immune tolerance in an autoantigen-specific manner. This review discusses methods to achieve this, focusing on tolerogenic dendritic cells. Clinical trials in other autoimmune diseases also provide learnings with regards to clinical translation of this approach, including identification of autoantigen(s), selection of appropriate patients and administration route and frequency.

Determination of HLA class II risk alleles and prediction of self/non-self-epitopes contributing Hashimoto's thyroiditis in a group of Iranian patients.

One of the probable hypotheses for the onset of autoimmunity is molecular mimicry. This study aimed to determine the HLA-II risk alleles for developing Hashimoto's thyroiditis (HT) in order to analyze the molecular homology between candidate pathogen-derived epitopes and potentially self-antigens (thyroid peroxidase, TPO) based on the presence of HLA risk alleles. HLA-DRB1/-DQB1 genotyping was performed in 100 HT patients and 330 ethnically matched healthy controls to determine the predisposing/protective alleles for HT disease. Then, in silico analysis was conducted to examine the sequence homology between epitopes derived from autoantigens and four potentially relevant pathogens and their binding capacities to HLA risk alleles based on peptide docking analysis. We identified HLA-DRB1*03:01, *04:02, *04:05, and *11:04 as predisposing alleles and DRB1*13:01 as a potentially predictive allele for HT disease. Also, DRB1*11:04 ~ DQB1*03:01 (Pc = 0.002; OR, 3.97) and DRB1*03:01 ~ DQB1*02:01 (Pc = 0.004; OR, 2.24) haplotypes conferred a predisposing role for HT. Based on logistic regression analysis, carrying risk alleles increased the risk of HT development 4.5 times in our population (P = 7.09E-10). Also, ROC curve analysis revealed a high predictive power of those risk alleles for discrimination of the susceptible from healthy individuals (AUC, 0.70; P = 6.6E-10). Analysis of peptide sequence homology between epitopes of TPO and epitopes derived from four candidate microorganisms revealed a homology between envelop glycoprotein D of herpes virus and sequence 151-199 of TPO with remarkable binding capacity to HLA-DRB1*03:01 allele. Our findings indicate the increased risk of developing HT in those individuals carrying HLA risk alleles which can also be related to herpes virus infection.

Is the exquisite specificity of lymphocytes generated by thymic selection or due to evolution?

We have previously argued that the antigen receptors of T and B lymphocytes evolved to be sufficiently specific to avoid massive deletion of clonotypes by negative selection. Their optimal 'specificity' level, i.e., probability of binding any particular epitope, was shown to be inversely related to the number of self-antigens that the cells have to be tolerant to. Experiments have demonstrated that T lymphocytes also become more specific during negative selection in the thymus, because cells expressing the most crossreactive receptors have the highest likelihood of binding a self-antigen, and hence to be tolerized (i.e., deleted, anergized, or diverted into a regulatory T cell phenotype). Thus, there are two -not mutually exclusive- explanations for the exquisite specificity of T cells, one involving evolution and the other thymic selection. To better understand the impact of both, we extend a previously developed mathematical model by allowing for T cells with very different binding probabilities in the pre-selection repertoire. We confirm that negative selection tends to tolerize the most crossreactive clonotypes. As a result, the average level of specificity in the functional post-selection repertoire depends on the number of self-antigens, even if there is no evolutionary optimization of binding probabilities. However, the evolutionary optimal range of binding probabilities in the pre-selection repertoire also depends on the number of self-antigens. Species with more self antigens need more specific pre-selection repertoires to avoid excessive loss of T cells during thymic selection, and hence mount protective immune responses. We conclude that both evolution and negative selection are responsible for the high level of specificity of lymphocytes.

Molecular dissection of an immunodominant epitope in Kv1.2-exclusive autoimmunity.

Introduction: Subgroups of autoantibodies directed against voltage-gated potassium channel (Kv) complex components have been associated with immunotherapy-responsive clinical syndromes. The high prevalence and the role of autoantibodies directly binding Kv remain, however, controversial. Our objective was to determine Kv autoantibody binding requirements and to clarify their contribution to the observed immune response. Methods: Binding epitopes were studied in sera (n = 36) and cerebrospinal fluid (CSF) (n = 12) from a patient cohort positive for Kv1.2 but negative for 32 common neurological autoantigens and controls (sera n = 18 and CSF n = 5) by phospho and deep mutational scans. Autoantibody specificity and contribution to the observed immune response were resolved on recombinant cells, cerebellum slices, and nerve fibers. Results: 83% of the patients (30/36) within the studied cohort shared one out of the two major binding epitopes with Kv1.2-3 reactivity. Eleven percent (4/36) of the serum samples showed no binding. Fingerprinting resolved close to identical sequence requirements for both shared epitopes. Kv autoantibody response is directed against juxtaparanodal regions in peripheral nerves and the axon initial segment in central nervous system neurons and exclusively mediated by the shared epitopes. Discussion: Systematic mapping revealed two shared autoimmune responses, with one dominant Kv1.2-3 autoantibody epitope being unexpectedly prevalent. The conservation of the molecular binding requirements among these patients indicates a uniform autoantibody repertoire with monospecific reactivity. The enhanced sensitivity of the epitope-based (10/12) compared with that of the cell-based detection (7/12) highlights its use for detection. The determined immunodominant epitope is also the primary immune response visible in tissue, suggesting a diagnostic significance and a specific value for routine screening.

Anti-LAMP-2 Antibody Seropositivity in Children with Primary Systemic Vasculitis Affecting Medium- and Large-Sized Vessels.

Chronic primary systemic vasculitis (PSV) comprises a group of heterogeneous diseases that are broadly classified by affected blood vessel size, clinical traits and the presence (or absence) of anti-neutrophil cytoplasmic antibodies (ANCA) against proteinase 3 (PR3) and myeloperoxidase (MPO). In small vessel vasculitis (SVV), ANCA are not present in all patients, and they are rarely detected in patients with vasculitis involving medium (MVV) and large (LVV) blood vessels. Some studies have demonstrated that lysosome-associated membrane protein-2 (LAMP-2/CD107b) is a target of ANCA in SVV, but its presence and prognostic value in childhood MVV and LVV is not known. This study utilized retrospective sera and clinical data obtained from 90 children and adolescents with chronic PSV affecting small (SVV, n = 53), medium (MVV, n = 16), and large (LVV, n = 21) blood vessels. LAMP-2-ANCA were measured in time-of-diagnosis sera using a custom electrochemiluminescence assay. The threshold for seropositivity was established in a comparator cohort of patients with systemic autoinflammatory disease. The proportion of LAMP-2-ANCA-seropositive individuals and sera concentrations of LAMP-2-ANCA were assessed for associations with overall and organ-specific disease activity at diagnosis and one-year follow up. This study demonstrated a greater time-of-diagnosis prevalence and sera concentration of LAMP-2-ANCA in MVV (52.9% seropositive) and LVV (76.2%) compared to SVV (45.3%). Further, LAMP-2-ANCA-seropositive individuals had significantly lower overall, but not organ-specific, disease activity at diagnosis. This did not, however, result in a greater reduction in disease activity or the likelihood of achieving inactive disease one-year after diagnosis. The results of this study demonstrate particularly high prevalence and concentration of LAMP-2-ANCA in chronic PSV that affects large blood vessels and is seronegative for traditional ANCA. Our findings invite reconsideration of roles for autoantigens other than MPO and PR3 in pediatric vasculitis, particularly in medium- and large-sized blood vessels.

The monocyte cell surface is a unique site of autoantigen generation in rheumatoid arthritis.

Although anti-citrullinated protein autoantibodies (ACPAs) are a hallmark serological feature of rheumatoid arthritis (RA), the mechanisms and cellular sources behind the generation of the RA citrullinome remain incompletely defined. Peptidylarginine deiminase IV (PAD4), one of the key enzymatic drivers of citrullination in the RA joint, is expressed by granulocytes and monocytes; however, the subcellular localization and contribution of monocyte-derived PAD4 to the generation of citrullinated autoantigens remain underexplored. In this study, we demonstrate that PAD4 displays a widespread cellular distribution in monocytes, including expression on the cell surface. Surface PAD4 was enzymatically active and capable of citrullinating extracellular fibrinogen and endogenous surface proteins in a calcium dose-dependent manner. Fibrinogen citrullinated by monocyte-surface PAD4 could be specifically recognized over native fibrinogen by a panel of eight human monoclonal ACPAs. Several unique PAD4 substrates were identified on the monocyte surface via mass spectrometry, with citrullination of the CD11b and CD18 components of the Mac-1 integrin complex being the most abundant. Citrullinated Mac-1 was found to be a target of ACPAs in 25% of RA patients, and Mac-1 ACPAs were significantly associated with HLA-DRB1 shared epitope alleles, higher C-reactive protein and IL-6 levels, and more erosive joint damage. Our findings implicate the monocyte cell surface as a unique and consequential site of extracellular and cell surface autoantigen generation in RA.

Antigen-specific Fab profiling achieves molecular-resolution analysis of human autoantibody repertoires in rheumatoid arthritis.

The presence of autoantibodies is a defining feature of many autoimmune diseases. The number of unique autoantibody clones is conceivably limited by immune tolerance mechanisms, but unknown due to limitations of the currently applied technologies. Here, we introduce an autoantigen-specific liquid chromatography-mass spectrometry-based IgG1 Fab profiling approach using the anti-citrullinated protein antibody (ACPA) repertoire in rheumatoid arthritis (RA) as an example. We show that each patient harbors a unique and diverse ACPA IgG1 repertoire dominated by only a few antibody clones. In contrast to the total plasma IgG1 antibody repertoire, the ACPA IgG1 sub-repertoire is characterised by an expansion of antibodies that harbor one, two or even more Fab glycans, and different glycovariants of the same clone can be detected. Together, our data indicate that the autoantibody response in a prominent human autoimmune disease is complex, unique to each patient and dominated by a relatively low number of clones.

Activated B-Cells enhance epitope spreading to support successful cancer immunotherapy.

Immune checkpoint therapies (ICT) have transformed the treatment of cancer over the past decade. However, many patients do not respond or suffer relapses. Successful immunotherapy requires epitope spreading, but the slow or inefficient induction of functional antitumoral immunity delays the benefit to patients or causes resistances. Therefore, understanding the key mechanisms that support epitope spreading is essential to improve immunotherapy. In this review, we highlight the major role played by B-cells in breaking immune tolerance by epitope spreading. Activated B-cells are key Antigen-Presenting Cells (APC) that diversify the T-cell response against self-antigens, such as ribonucleoproteins, in autoimmunity but also during successful cancer immunotherapy. This has important implications for the design of future cancer vaccines.

Induction of islet autoimmunity to defective ribosomal product of the insulin gene as neoantigen after anti-cancer immunotherapy leading to autoimmune diabetes.

Introduction: The autoimmune response in type 1 diabetes (T1D), in which the beta cells expressing aberrant or modified proteins are killed, resembles an effective antitumor response. Defective ribosomal protein products in tumors are targets of the anti-tumor immune response that is unleashed by immune checkpoint inhibitor (ICI) treatment in cancer patients. We recently described a defective ribosomal product of the insulin gene (INS-DRiP) that is expressed in stressed beta cells and targeted by diabetogenic T cells. T1D patient-derived INS-DRiP specific T cells can kill beta cells and are present in the insulitic lesion. T cells reactive to INS-DRiP epitopes are part of the normal T cell repertoire and are believed to be kept in check by immune regulation without causing autoimmunity. Method: T cell autoreactivity was tested using a combinatorial HLA multimer technology measuring a range of epitopes of islet autoantigens and neoantigen INS-DRiP. INS-DRiP expression in human pancreas and insulinoma sections was tested by immunohistochemistry. Results: Here we report the induction of islet autoimmunity to INS-DRiP and diabetes after ICI treatment and successful tumor remission. Following ICI treatment, T cells of the cancer patient were primed against INS-DRiP among other diabetogenic antigens, while there was no sign of autoimmunity to this neoantigen before ICI treatment. Next, we demonstrated the expression of INS-DRiP as neoantigen in both pancreatic islets and insulinoma by staining with a monoclonal antibody to INS-DRiP. Discussion: These results bridge cancer and T1D as two sides of the same coin and point to neoantigen expression in normal islets and insulinoma that may serve as target of both islet autoimmunity and tumor-related autoimmunity.

[Molecular mimicry between Plasmodium sp and Guillain-Barre syndrome antigens]. / Mimetismo molecular entre el Plasmodium sp y los antígenos del síndrome de Guillain-Barre.

OBJECTIVE: Analyze the molecular mimicry between Plasmodium spp. and autoantigens associated with GBS, identifying possible antigenic epitopes. METHODS: PSI-Blast, Praline, Emboss, Protein Data Bank, Swiss Model Server, AlphaFold 2, Ellipro and PyMol 2.3 were used to search for homologies, perform alignments, obtain protein structures, and predict epitopes. RESULTS: 17 autoantigens and seven immunological targets of the peripheral nervous system were included, identifying 72 possible epitopes associated with GBS. From the proteome of Plasmodium spp. (298 proteins), only two showed similarities close to 30% with TRIM21 and BACE1, generating seven possible epitopes. CONCLUSION: No significant homologies were observed between the proteome of GBS and Plasmodium spp. The exploration of other mechanisms such as immune-mediated capillary damage, Epitope Spreading or Bystander Activation is suggested to explain the mentioned association. These findings underscore the need to clarify the etiology of autoimmune diseases and the role of pathogens. The need for experimental studies to validate these results is emphasized.

OBJETIVO: Analizar el mimetismo molecular entre Plasmodium spp. y autoantígenos asociados al SGB, identificando posibles epítopos antigénicos. MÉTODOS: Se emplearon PSI-Blast, Praline, Emboss, Protein Data Bank, Swiss Model Server, AlphaFold 2, Ellipro y PyMol 2.3 para buscar homologías, realizar alineamientos, obtener estructuras proteicas y predecir epítopos. RESULTADOS: Se incluyeron 17 autoantígenos y siete objetivos inmunológicos del sistema nervioso periférico, identificándose 72 posibles epítopos asociados al SGB. Del proteoma de Plasmodium spp. (298 proteínas), solo dos mostraron similitud cercana al 30% con TRIM21 y BACE1, generando siete posibles epítopos. CONCLUSIÓN: No se observaron homologías significativas entre el proteoma de SGB y Plasmodium spp. Se sugiere la exploración de otros mecanismos como el daño capilar inmunomediado, Epitope Spreading o Bystander Activation para explicar la asociación mencionada. Estos hallazgos subrayan la necesidad de aclarar la etiología de las enfermedades autoinmunes y el papel de los patógenos. Se enfatiza la necesidad de estudios experimentales para validar estos resultados.

[Molecular mimic between cardiovascular diseases and microorganism antigens]. / Mimetismo molecular entre enfermedades cardiovasculares y antígenos de microorganismos.

INTRODUCTION: Cardiovascular diseases are the result of genetic and environmental interaction that conditions the integrity of the heart and blood vessels. Risk factors include infections. The inflammatory response against the infectious agent is a trigger of autoimmune cardiovascular diseases due to the similarity between the pathogen proteins and human antigens, since the immune response can present cross-reactivity caused by molecular mimicry. METHODS: We performed a search for pathogens involved in autoimmune heart diseases and autoantigens 9 associated with these diseases in the Pubmed and Google Scholar search engines. Identity between proteins was performed through global alignments using PSI-BLAST. The 3D structures of the proteins were obtained by Uniprot or NCBI and, if not found, the structure was modeled by homology using the Swiss Model server. Epitope prediction was performed through Ellipro and the Immunological Epitope Database (IEDB). In addition, the PYMOL program was used to visualize proteins in 3D and position the epitopes in the structure. RESULTS: A total of ten cardiovascular proteins showed identity (30-88,24%) in their amino acid sequences with antigens from 10 pathogens. Actin proteins and heat shock protein (HSP) families had higher levels of identity with Trypanosoma Cruzi, Cryptococcus neoformans, and Chlamydia trachomatis, 71,47%, 88,24%, and 80,61%, respectively. Other pathogens, such as Streptococcus pyogenes, Bacillus sp, Magnetospirillum gryphiswaldense, Helicobacter pylori and Chlamydia pneumoniae, presented a moderate identity with a maximum value of 65,79%. CONCLUSION: Human actin and HSPs share a high degree of conservation with epitopes from various microorganisms, such as bacteria, fungi and protozoa, suggesting molecular mimicry and cross-reactivity as a mechanism for the development of atherosclerosis, heart disease rheumatic disease, myocarditis and Chagas heart disease. In vitro and in vivo work is needed to demonstrate the results obtained in the In Silico analysis.

INTRODUCCIÓN: Las enfermedades cardiovasculares son el resultado de la interacción genética y ambiental que condiciona la integridad del corazón y los vasos sanguíneos. Los factores de riesgo incluyen infecciones. La respuesta inflamatoria contra el agente infeccioso es un desencadenante de las enfermedades cardiovasculares autoinmunes, debido a la similitud entre las proteínas del patógeno y los antígenos humanos, pues la respuesta inmunitaria puede presentar reactividad cruzada causada por mimetismo molecular. MÉTODOS: Realizamos una búsqueda de patógenos involucrados en enfermedades cardíacas autoinmunes y de autoantígenos asociados a estas enfermedades en los buscadores Pubmed y Google Scholar. La identidad entre proteínas se realizó a través de alineamientos globales utilizando PSI-BLAST. Las estructuras 3D de las proteínas fue obtenida por Uniprot o NCBI y, si no se encontraban, las estructuras se modelaban por homología, utilizando el servidor Swiss Model. La predicción de los epítopes se realizó a través de Ellipro, y la Base de Datos de Epítopos Inmunológicos (IEDB). Además, se utilizó el programa PYMOL para la visualización de proteínas en 3D, y el posicionamiento de los epítopes en la estructura. RESULTADOS: Diez proteínas cardiovasculares mostraron una identidad (30-88,24%) en sus secuencias de aminoácidos con antígenos de diez patógenos. Las proteínas de actina y las familias de proteínas de choque térmico (HSP, por sus siglas en inglés), presentaron niveles de identidad más altos con Trypanosoma Cruzi, Cryptococcus neoformans y Chlamydia trachomatis, 71,47%, 88,24% y 80,61%, respectivamente. Otros patógenos, como Streptococcus pyogenes, Bacillus sp, Magnetospirillum gryphiswaldense, Helicobacter pylori y Chlamydia pneumoniae, presentaron identidad moderada con un valor máximo del 65,79%. CONCLUSIÓN: La actina humana y las HSP comparten un alto grado de conservación con epítopos de varios microorganismos, como bacterias, hongos y protozoos; lo que sugiere la imitación molecular y la reactividad cruzada como mecanismos para el desarrollo de la aterosclerosis, la enfermedad cardíaca reumática, la miocarditis y la enfermedad cardíaca de Chagas. Se necesitan trabajos in vitro e in vivo, que demuestren los resultados obtenidos en el análisis In Silico.

[Molecular mimicry between human thyroid peroxidase, thyroglobulin, cosinophil peroxidase, IL-24 and microorganisms antigens]. / Mimetismo molecular entre peroxidasa tiroidea humana, tiroglobulina, peroxidasa de eosinófilos, IL-24 y antígenos de microorganismos.

OBJECTIVE: Identify molecular mimicry between TPO, eosinophil peroxidase (EPX), thyroglobulin and IL24 and microorganism antigens. METHODS: Through in silico analysis, we performed local alignments between human and microorganism antigens with PSI-BLAST. Proteins that did not present a 3D structure were modeled by homology through the Swiss Modeller server and epitope prediction was performed through Ellipro. Epitopes were located in the 3D models using PYMOL software. RESULTS: A total of 38 microorganism antigens (parasites, bacteria) had identities between 30% and 45%, being the highest with Anisakis simplex. The alignment between 2 candidate proteins from A. simplex and EPX presented significant values, with identities of 43 and 44%. In bacteria, Campylobacter jejuni presented the highest identity with thyroglobulin (35%). 220 linear and conformational epitopes of microorganism antigens were predicted. Peroxidasin-like proteins from Toxocara canis and Trichinella pseudospiralis presented 10 epitopes similar to TPO and EPX, as possible molecules triggering cross-reactivity. No virus presented identity with the human proteins studied. CONCLUSION: TPO and EPX antigens shared potential cross-reactive epitopes with bacterial and nematode proteins, suggesting that molecular mimicry could be a mechanism that explains the relationship between infections and urticaria/hypothyroidism. In vitro work is needed to demonstrate the results obtained in the in silico analysis.

OBJETIVO: Identificar mimetismo molecular entre TPO, eosinofil peroxidasa (EPX), tiroglobulina e IL24 y antígenos de microorganismos. MÉTODOS: A través de análisis in silico, realizamos los alineamientos locales entre los antígenos humanos y de microorganismos con PSI-BLAST. Las proteínas que no presentaban estructura 3D, fueron modeladas por homología a través del servidor Swiss Modeller y se realizó una predicción de epítopes a través de Ellipro. Los epítopes se localizaron en los modelos 3D utilizando el software PYMOL. RESULTADOS: Un total de 38 antígenos de microorganismos (parásitos y bacterias), tuvieron identidades entre 30 y 45%, siendo los más altos con Anisakis simplex. El alineamiento entre dos proteínas candidatas de A. simplex y EPX presentaron valores importantes, con identidades de 43 y 44%. En las bacterias, Campylobacter jejuni presentó la mayor identidad con tiroglobulina (35%). Se predijeron 220 epítopes lineales y conformacionales de antígenos de microorganismos. Las proteínas similares a la peroxidasina de Toxocara canis y Trichinella pseudospiralis presentaron diez epítopes similares a TPO y EPX, como posibles moléculas desencadenantes de una reactividad cruzada. Ningún virus presentó identidad con las proteínas humanas estudiadas. CONCLUSIÓN: Los antígenos TPO y EPX compartieron potenciales epítopes de reacción cruzada con proteínas bacterianas y nematodos, lo que sugiere que el mimetismo molecular podría ser un mecanismo que explique la relación entre infecciones y la urticaria/hipotiroidismo. Se necesitan trabajos in vitro que demuestren los resultados obtenidos en el análisis in silico.

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.

Biological functions of Circular RNA_LARP4/ Upstream frameshift 1 in development of gastric cancer.

Recently, the progression of gastric cancer (GC), as one of the most ordinary malignant tumors, has been reported to be associated with circular RNAs. This study aimed to identify the role of circular RNA_LARP4 in GC. We performed real-time quantitative polymerase chain reaction (RT-qPCR) in 46 paired GC patients and GC cell lines to detect the expression of circular RNA_LARP4. Moreover, the role of circular RNA_LARP4 in GC proliferation was identified through proliferation assay and colony formation assay, while the role of circular RNA_LARP4 in GC metastasis was measured through scratch wound assay and transwell assay. Furthermore, the potential targets of circular RNA_LARP4 were predicted through bioinformatics methods and further identified by western blot assay and RT-qPCR. Circular RNA_LARP4 expression was remarkably lower in GC tissues compared with that in adjacent samples. Besides, cell proliferation of GC was inhibited after overexpression of circular RNA_LARP4, while cell migration and invasion of GC was inhibited after overexpression of circular RNA_LARP4. Furthermore, Upstream frameshift 1 (UPF1) was predicted as the potential target of circular RNA_LARP4 and was upregulated via overexpression of circular RNA_LARP4 in GC. Circular RNA_LARP4 inhibits GC cell proliferation and metastasis via targeting UPF1 in vitro, which might provide a new tumor suppressor in GC development.