scholarly journals Molecular and Structural Parallels between Gluten Pathogenic Peptides and Bacterial-Derived Proteins by Bioinformatics Analysis

2021 ◽  
Vol 22 (17) ◽  
pp. 9278
Author(s):  
Diego S. Vazquez ◽  
Hanna M. Schilbert ◽  
Veronica I. Dodero
Keyword(s):  
Innate Immunity ◽  
T Cell ◽  
Molecular Mimicry ◽  
Sequence Similarity ◽  
Bacterial Pathogens ◽  
Extracellular Proteins ◽  
T Cell Epitopes ◽  
Solvent Exposure ◽  
High Sequence Similarity ◽  
Gliadin Peptides

Gluten-related disorders (GRDs) are a group of diseases that involve the activation of the immune system triggered by the ingestion of gluten, with a worldwide prevalence of 5%. Among them, Celiac disease (CeD) is a T-cell-mediated autoimmune disease causing a plethora of symptoms from diarrhea and malabsorption to lymphoma. Even though GRDs have been intensively studied, the environmental triggers promoting the diverse reactions to gluten proteins in susceptible individuals remain elusive. It has been proposed that pathogens could act as disease-causing environmental triggers of CeD by molecular mimicry mechanisms. Additionally, it could also be possible that unrecognized molecular, structural, and physical parallels between gluten and pathogens have a relevant role. Herein, we report sequence, structural and physical similarities of the two most relevant gluten peptides, the 33-mer and p31-43 gliadin peptides, with bacterial pathogens using bioinformatics going beyond the molecular mimicry hypothesis. First, a stringent BLASTp search using the two gliadin peptides identified high sequence similarity regions within pathogen-derived proteins, e.g., extracellular proteins from Streptococcus pneumoniae and Granulicatella sp. Second, molecular dynamics calculations of an updated α-2-gliadin model revealed close spatial localization and solvent-exposure of the 33-mer and p31-43 peptide, which was compared with the pathogen-related proteins by homology models and localization predictors. We found putative functions of the identified pathogen-derived sequence by identifying T-cell epitopes and SH3/WW-binding domains. Finally, shape and size parallels between the pathogens and the superstructures of gliadin peptides gave rise to novel hypotheses about activation of innate immunity and dysbiosis. Based on our structural findings and the similarities with the bacterial pathogens, evidence emerges that these pathologically relevant gluten-derived peptides could behave as non-replicating pathogens opening new research questions in the interface of innate immunity, microbiome, and food research.

scholarly journals Mining the capacity of human-associated microorganisms to trigger rheumatoid arthritis—A systematic immunoinformatics analysis of T cell epitopes

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253918
Author(s):  
Jelena Repac ◽  
Marija Mandić ◽  
Tanja Lunić ◽  
Bojan Božić ◽  
Biljana Božić Nedeljković
Keyword(s):  
Rheumatoid Arthritis ◽  
T Cell ◽  
De Novo ◽  
Molecular Mimicry ◽  
Sequence Similarity ◽  
Cell Epitope ◽  
Homology Search ◽  
T Cell Epitope ◽  
T Cell Epitopes ◽  
Painful Condition

Autoimmune diseases, often triggered by infection, affect ~5% of the worldwide population. Rheumatoid Arthritis (RA)–a painful condition characterized by the chronic inflammation of joints—comprises up to 20% of known autoimmune pathologies, with the tendency of increasing prevalence. Molecular mimicry is recognized as the leading mechanism underlying infection-mediated autoimmunity, which assumes sequence similarity between microbial and self-peptides driving the activation of autoreactive lymphocytes. T lymphocytes are leading immune cells in the RA-development. Therefore, deeper understanding of the capacity of microorganisms (both pathogens and commensals) to trigger autoreactive T cells is needed, calling for more systematic approaches. In the present study, we address this problem through a comprehensive immunoinformatics analysis of experimentally determined RA-related T cell epitopes against the proteomes of Bacteria, Fungi, and Viruses, to identify the scope of organisms providing homologous antigenic peptide determinants. By this, initial homology screening was complemented with de novo T cell epitope prediction and another round of homology search, to enable: i) the confirmation of homologous microbial peptides as T cell epitopes based on the predicted binding affinity to RA-related HLA polymorphisms; ii) sequence similarity inference for top de novo T cell epitope predictions to the RA-related autoantigens to reveal the robustness of RA-triggering capacity for identified (micro/myco)organisms. Our study reveals a much larger repertoire of candidate RA-triggering organisms, than previously recognized, providing insights into the underestimated role of Fungi in autoimmunity and the possibility of a more direct involvement of bacterial commensals in RA-pathology. Finally, our study pinpoints Endoplasmic reticulum chaperone BiP as the most potent (most likely mimicked) RA-related autoantigen, opening an avenue for identifying the most potent autoantigens in a variety of different autoimmune pathologies, with possible implications in the design of next-generation therapeutics aiming to induce self-tolerance by affecting highly reactive autoantigens.

scholarly journals Molecular Mimicry Map (3M) of SARS-CoV-2: Prediction of potentially immunopathogenic SARS-CoV-2 epitopes via a novel immunoinformatic approach

2020 ◽  
Author(s):  
Hyunsu An ◽  
Jihwan Park
Keyword(s):  
T Cell ◽  
Autoimmune Diseases ◽  
Web Application ◽  
Molecular Mimicry ◽  
Sequence Similarity ◽  
Protein Structures ◽  
Cross Reactivity ◽  
T Cell Epitopes ◽  
B Cell Epitopes ◽  
Human Proteins

ABSTRACTCurrently, more than 33 million peoples have been infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and more than a million people died from coronavirus disease 2019 (COVID-19), a disease caused by the virus. There have been multiple reports of autoimmune and inflammatory diseases following SARS-CoV-2 infections. There are several suggested mechanisms involved in the development of autoimmune diseases, including cross-reactivity (molecular mimicry). A typical workflow for discovering cross-reactive epitopes (mimotopes) starts with a sequence similarity search between protein sequences of human and a pathogen. However, sequence similarity information alone is not enough to predict cross-reactivity between proteins since proteins can share highly similar conformational epitopes whose amino acid residues are situated far apart in the linear protein sequences. Therefore, we used a hidden Markov model-based tool to identify distant viral homologs of human proteins. Also, we utilized experimentally determined and modeled protein structures of SARS-CoV-2 and human proteins to find homologous protein structures between them. Next, we predicted binding affinity (IC50) of potentially cross-reactive T-cell epitopes to 34 MHC allelic variants that have been associated with autoimmune diseases using multiple prediction algorithms. Overall, from 8,138 SARS-CoV-2 genomes, we identified 3,238 potentially cross-reactive B-cell epitopes covering six human proteins and 1,224 potentially cross-reactive T-cell epitopes covering 285 human proteins. To visualize the predicted cross-reactive T-cell and B-cell epitopes, we developed a web-based application “Molecular Mimicry Map (3M) of SARS-CoV-2” (available at https://ahs2202.github.io/3M/). The web application enables researchers to explore potential cross-reactive SARS-CoV-2 epitopes alongside custom peptide vaccines, allowing researchers to identify potentially suboptimal peptide vaccine candidates or less ideal part of a whole virus vaccine to design a safer vaccine for people with genetic and environmental predispositions to autoimmune diseases. Together, the computational resources and the interactive web application provide a foundation for the investigation of molecular mimicry in the pathogenesis of autoimmune disease following COVID-19.

scholarly journals Protection against Vaccinia Virus Challenge by CD8 Memory T Cells Resolved by Molecular Mimicry

2006 ◽  
Vol 81 (2) ◽  
pp. 934-944 ◽  
Author(s):  
Markus Cornberg ◽  
Brian S. Sheridan ◽  
Frances M. Saccoccio ◽  
Michael A. Brehm ◽  
Liisa K. Selin
Keyword(s):  
T Cells ◽  
T Cell ◽  
Vaccinia Virus ◽  
Cd8 T Cells ◽  
Protective Immunity ◽  
Molecular Mimicry ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
T Cell Epitopes ◽  
Cell Responses

ABSTRACT Live vaccinia virus (VV) vaccination has been highly successful in eradicating smallpox. However, the mechanisms of immunity involved in mediating this protective effect are still poorly understood, and the roles of CD8 T-cell responses in primary and secondary VV infections are not clearly identified. By applying the concept of molecular mimicry to identify potential CD8 T-cell epitopes that stimulate cross-reactive T cells specific to lymphocytic choriomeningitis virus (LCMV) and VV, we identified after screening only 115 peptides two VV-specific immunogenic epitopes that mediated protective immunity against VV. An immunodominant epitope, VV-e7r130, did not generate cross-reactive T-cell responses to LCMV, and a subdominant epitope, VV-a11r198, did generate cross-reactive responses to LCMV. Infection with VV induced strong epitope-specific responses which were stable into long-term memory and peaked at the time virus was cleared, consistent with CD8 T cells assisting in the control of VV. Two different approaches, direct adoptive transfer of VV-e7r-specific CD8 T cells and prior immunization with a VV-e7r-expressing ubiquitinated minigene, demonstrated that memory CD8 T cells alone could play a significant role in protective immunity against VV. These studies suggest that exploiting cross-reactive responses between viruses may be a useful tool to complement existing technology in predicting immunogenic epitopes to large viruses, such as VV, leading to a better understanding of the role CD8 T cells play during these viral infections.

scholarly journals Candidate targets for immune responses to 2019-Novel Coronavirus (nCoV): sequence homology- and bioinformatic-based predictions

2020 ◽  
Author(s):  
Alba Grifoni ◽  
John Sidney ◽  
Yun Zhang ◽  
Richard H Scheuermann ◽  
Bjoern Peters ◽  
...  
Keyword(s):  
Immune Responses ◽  
Sequence Similarity ◽  
Rapid Expansion ◽  
Immune Recognition ◽  
T Cell Epitopes ◽  
High Sequence Similarity ◽  
Essential Information ◽  
Viral Spread ◽  
Recent Emergence ◽  
Novel Coronavirus

ABSTRACTEffective countermeasures against the recent emergence and rapid expansion of the 2019-Novel Coronavirus (2019-nCoV) require the development of data and tools to understand and monitor viral spread and immune responses. However, little information about the targets of immune responses to 2019-nCoV is available. We used the Immune Epitope Database and Analysis Resource (IEDB) resource to catalog available data related to other coronaviruses, including SARS-CoV, which has high sequence similarity to 2019-nCoV, and is the best-characterized coronavirus in terms of epitope responses. We identified multiple specific regions in 2019-nCoV that have high homology to SARS virus. Parallel bionformatic predictions identified a priori potential B and T cell epitopes for 2019-nCoV. The independent identification of the same regions using two approaches reflects the high probability that these regions are targets for immune recognition of 2019-nCoV.ONE SENTENCE SUMMARYWe identified potential targets for immune responses to 2019-nCoV and provide essential information for understanding human immune responses to this virus and evaluation of diagnostic and vaccine candidates.

scholarly journals Haemophilus parasuis (Glaesserella parasuis) as a Potential Driver of Molecular Mimicry and Inflammation in Rheumatoid Arthritis

2021 ◽  
Vol 8 ◽  
Author(s):  
Gabriele Di Sante ◽  
Elisa Gremese ◽  
Barbara Tolusso ◽  
Paola Cattani ◽  
Clara Di Mario ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
T Cells ◽  
T Cell ◽  
Mononuclear Cells ◽  
Molecular Mimicry ◽  
Sequence Similarity ◽  
Infectious Agent ◽  
Haemophilus Parasuis ◽  
Peripheral Blood Mononuclear ◽  
The Cross

Background:Haemophilus parasuis (Hps; now Glaesserella parasuis) is an infectious agent that causes severe arthritis in swines and shares sequence similarity with residues 261–273 of collagen type 2 (Coll261−273), a possible autoantigen in rheumatoid arthritis (RA).Objectives/methods: We tested the presence of Hps sequencing 16S ribosomal RNA in crevicular fluid, synovial fluids, and tissues in patients with arthritis (RA and other peripheral arthritides) and in healthy controls. Moreover, we examined the cross-recognition of Hps by Coll261−273-specific T cells in HLA-DRB1*04pos RA patients, by T-cell receptor (TCR) beta chain spectratyping and T-cell phenotyping.Results:Hps DNA was present in 57.4% of the tooth crevicular fluids of RA patients and in 31.6% of controls. Anti-Hps IgM and IgG titers were detectable and correlated with disease duration and the age of the patients. Peripheral blood mononuclear cells (PBMCs) were stimulated with Hps virulence-associated trimeric autotransporter peptide (VtaA10755−766), homologous to human Coll261−273 or co-cultured with live Hps. In both conditions, the expanded TCR repertoire overlapped with Coll261−273 and led to the production of IL-17.Discussion: We show that the DNA of an infectious agent (Hps), not previously described as pathogen in humans, is present in most patients with RA and that an Hps peptide is able to activate T cells specific for Coll261−273, likely inducing or maintaining a molecular mimicry mechanism.Conclusion: The cross-reactivity between VtaA10755−766 of a non-human infectious agent and human Coll261−273 suggests an involvement in the pathogenesis of RA. This mechanism appears emphasized in predisposed individuals, such as patients with shared epitope.

scholarly journals HLA-dependent variation in SARS-CoV-2 CD8+ T cell cross-reactivity with human coronaviruses

2021 ◽  
Author(s):  
Paul Buckley ◽  
Chloe Hyun-jung Lee ◽  
Mariana Pereira Pinho ◽  
Rosana Ottakandathil Babu ◽  
Jeongmin Woo ◽  
...  
Keyword(s):  
T Cell ◽  
Sequence Similarity ◽  
Cross Reactivity ◽  
Skewed Distribution ◽  
Prior Exposure ◽  
High Sequence Similarity ◽  
Protein Coding ◽  
Cell Immunity ◽  
Immunogenic Peptides ◽  
Human Coronaviruses

Pre-existing T cell immunity to SARS-CoV-2 in individuals without prior exposure to SARS-CoV-2 has been reported in several studies. While emerging evidence hints toward prior exposure to common-cold human coronaviruses (HCoV), the extent of- and conditions for- cross-protective immunity between SARS-CoV-2 and HCoVs remain open. Here, by leveraging a comprehensive pool of publicly available functionally evaluated SARS-CoV-2 peptides, we report 126 immunogenic SARS-CoV-2 peptides with high sequence similarity to 285 MHC-presented target peptides from at least one of four HCoV, thus providing a map describing the landscape of SARS-CoV-2 shared and private immunogenic peptides with functionally validated T cell responses. Using this map, we show that while SARS-CoV-2 immunogenic peptides in general exhibit higher level of dissimilarity to both self-proteome and -microbiomes, there exist several SARS-CoV-2 immunogenic peptides with high similarity to various human protein coding genes, some of which have been reported to have elevated expression in severe COVID-19 patients. We then combine our map with a SARS-CoV-2-specific TCR repertoire data from COVID-19 patients and healthy controls and show that whereas the public repertoire for the majority of convalescent patients are dominated by TCRs cognate to private SARS-CoV-2 peptides, for a subset of patients, more than 50% of their public repertoires that show reactivity to SARS-CoV-2, consist of TCRs cognate to shared SARS-CoV-2-HCoV peptides. Further analyses suggest that the skewed distribution of TCRs cognate to shared and private peptides in COVID-19 patients is likely to be HLA-dependent. Finally, by utilising the global prevalence of HLA alleles, we provide 10 peptides with known cognate TCRs that are conserved across SARS-CoV-2 and multiple human coronaviruses and are predicted to be recognised by a high proportion of the global population. Overall, our work indicates the potential for HCoV-SARS-CoV-2 reactive CD8+ T cells, which is likely dependent on differences in HLA-coding genes among individuals. These findings may have important implications for COVID-19 heterogeneity and vaccine-induced immune responses as well as robustness of immunity to SARS-CoV-2 and its variants.

scholarly journals Natural variants of α-gliadin peptides within wheat proteins with reduced toxicity in coeliac disease

2020 ◽  
Vol 123 (12) ◽  
pp. 1382-1389
Author(s):  
Nika Japelj ◽  
Tanja Suligoj ◽  
Wei Zhang ◽  
Beatriz Côrte-Real ◽  
Joachim Messing ◽  
...  
Keyword(s):  
T Cell ◽  
Coeliac Disease ◽  
Wheat Gluten ◽  
T Cell Epitopes ◽  
Structural Variations ◽  
Cd Toxicity ◽  
Natural Variants ◽  
Gliadin Peptides ◽  
Reduced Toxicity ◽  
T Cell Lines

AbstractThe only generally accepted treatment of coeliac disease (CD) is a lifelong gluten-free diet. Wheat gluten proteins include gliadins, low and high molecular weight glutenins. However, we have found significant structural variations within these protein families among different cultivars. To determine which structural motifs might be less toxic than others, we assessed five variants of α-gliadin immunodominant CD-toxic peptides synthesised as 16mers in CD T cell stimulation assays with gluten-sensitive T cell lines generated from duodenal biopsies from CD-affected individuals. The peptides harboured the overlapping T cell epitopes DQ 2.5-glia-α-2 and naturally occurring variants that differed in certain amino acids (AA). The results revealed that introduction of two selected AA substitutions in α-gliadin peptides reduced immunogenicity. A peptide with three AA substitutions involving two glutamic acids (E) and one glutamine residue (G) revealed the peptide was negative in 5:5 samples. We used CD small-intestinal organ culture to assess CD toxicity that revealed two peptides with selected substitution of both glutamic acid (E) and proline (P) residues abrogated evidence of CD toxicity.

scholarly journals Targeting “Immunogenic Hotspots” in Dengue and Zika Virus:  A Novel Approach to a Common Vaccine

2021 ◽  
Author(s):  
Dhrubajyoti Mahata ◽  
Debangshu Mukherjee ◽  
Vanshika Malviya ◽  
Gayatri Mukherjee
Keyword(s):  
Immune Responses ◽  
B Cell ◽  
Sequence Similarity ◽  
Docking Studies ◽  
T Cell Epitopes ◽  
Biophysical Parameters ◽  
High Sequence Similarity ◽  
B Cell Epitopes ◽  
Denv Serotypes ◽  
Novel Approach

Diseases caused by Dengue (DENV) and Zika (ZIKV) viruses cause significant mortality and illness globally. Due to the high sequence similarity of the viral proteins and the purported cross-reactive immune responses against the viruses, we envisioned a common multi-epitope vaccine (MEV) against both viruses by adopting a novel approach of identifying “immunogenic hotspots”. These stretches of the structural and non-structural proteins are enriched with MHC class I and class II supertype-restricted T cell epitopes, and B cell epitopes, in addition to being highly conserved between different DENV serotypes and ZIKV. Such an approach ensures inclusion of multiple overlapping T and B cell epitopes common to both viruses, and also warrants high population coverage. Importantly, epitopes known to cause antibody-dependent-enhancement of infection have been excluded. These immunogenic hotspots have then been stitched together with linkers in-silico along with an adjuvant, CTxB to develop the MEV candidate. Four structural models of the MEV were selected on the basis of conformational preservation of CTxB, and their biophysical parameters, which also conserved the immunogenicity of the multiple epitopes. Importantly, each of the MEV candidates were found to interact with TLR4-MD2 complex by molecular docking studies, indicative of their ability to induce TLR-mediated immune responses.

scholarly journals Pre-existing T cell-mediated cross-reactivity to SARS-CoV-2 cannot solely be explained by prior exposure to endemic human coronaviruses

2020 ◽  
Author(s):  
Cedric C.S. Tan ◽  
Christopher J. Owen ◽  
Christine Y.L. Tham ◽  
Antonio Bertoletti ◽  
Lucy van Dorp ◽  
...  
Keyword(s):  
T Cell ◽  
Sequence Homology ◽  
Core Genome ◽  
Sequence Similarity ◽  
Cell Epitope ◽  
Cross Reactivity ◽  
Prior Exposure ◽  
Phylogenetic Distance ◽  
T Cell Epitopes ◽  
Human Coronaviruses

AbstractSeveral studies have reported the presence of pre-existing humoral or cell-mediated cross-reactivity to SARS-CoV-2 peptides in healthy individuals unexposed to SARS-CoV-2. In particular, the current literature suggests that this pre-existing cross-reactivity could, in part, derive from prior exposure to ‘common cold’ endemic human coronaviruses (HCoVs). In this study, we characterised the sequence homology of SARS-CoV-2-derived T-cell epitopes reported in the literature across the entire diversity of the Coronaviridae family. Slightly over half (54.8%) of the tested epitopes did not have noticeable homology to any of the human endemic coronaviruses (HKU1, OC43, NL63 and 229E), suggesting prior exposure to these viruses cannot explain the full cross-reactive profiles observed in healthy unexposed individuals. Further, we find that the proportion of cross-reactive SARS-CoV-2 epitopes with noticeable sequence homology is extremely well predicted by the phylogenetic distance to SARS-CoV-2 (R2 = 96.6%). None of the coronaviruses sequenced to date showed a statistically significant excess of T-cell epitope homology relative to the proportion of expected random matches given the sequence similarity of their core genome to SARS-CoV-2. Taken together, our results suggest that the repertoire of cross-reactive epitopes reported in healthy adults cannot be primarily explained by prior exposure to any coronavirus known to date, or any related yet-uncharacterised coronavirus.

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