---
title: "Molecular mimicry and autoimmune disease: review unavailable — summary of source limitations"
id: "frontiers-in-immunology-15-molecular-mimicry-revisited-novel-perspectives-on-autoimmune-disease-initiation"
canonical_url: "https://medichelpline.com/clinical-feed/frontiers-in-immunology-15-molecular-mimicry-revisited-novel-perspectives-on-autoimmune-disease-initiation"
content_type: "clinical_feed_article"
specialty: "Infectious Disease"
source_name: "Frontiers in Immunology"
source_url: "https://www.frontiersin.org/articles/10.3389/fimmu.2026.1922884"
published_at: "2026-09-22T00:00:00.000Z"
evidence_level: "Journal Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Molecular mimicry and autoimmune disease: review unavailable — summary of source limitations
## Provenance & Clinical Metadata
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- **Specialty:** [Infectious Disease](https://medichelpline.com/clinical-feed/infectious-disease.md)
- **Primary Source:** Frontiers in Immunology
- **Source URL:** [Original Journal Publication](https://www.frontiersin.org/articles/10.3389/fimmu.2026.1922884)
- **Published At:** 2026-09-22T00:00:00.000Z
- **Evidence Rating:** Journal Feed
## Executive GIST (TL;DR)
- The provided source page did not include the article text for the review titled "Molecular mimicry revisited: novel perspectives on autoimmune disease initiation and progression." - Key concepts usually expected—definitions of **molecular mimicry**, proposed mechanisms linking infection to autoimmunity, specific disease examples, and experimental or clinical evidence—were not present in the supplied content. - The source material contained only website navigation, journal sections, and links; no abstract, methods, results, or conclusions were reported. - Because the article body and factual details (mechanistic pathways, cited studies, data, and recommendations) were absent, no clinical claims, numerical results, or study conclusions could be extracted or summarized from the source. - The lack of article content prevents outlining evidence strength, diagnostic or therapeutic implications, or citing authors/Institutions; those details were not reported in the source. - Readers should consult the original Frontiers in Immunology article page directly to access the full text for accurate clinical and scientific content about **molecular mimicry** and autoimmunity.
## Clinical Analysis & Structured Key Points
Frontiers | Molecular mimicry revisited: novel perspectives on autoimmune disease initiation and progression REVIEW article Front. Immunol. , 22 September 2026 Sec. Autoimmune Disorders Volume 17 - 2026 | https://doi.org/10.3389/fimmu.2026.1922884 Published in Frontiers in Immunology Autoimmune Disorders 7 impact factor 11.3 citescore Part of a Research Topic Evolution of Theories in Autoimmune Disease: From Early Concepts to Modern Integrations Submission open 46k views 19 articles Editor & Reviewers Edited by G H Gunnar Houen Reviewed by J B Jagadeesh BAYRY S D Selen Duygu Arık Outline Figures and Tables Figure 1 View in article Table 1 Co-evolution of pathogen and host. View in article Table 2 Most prominent examples for molecular mimicry as drivers of autoimmunity. View in article Table 3 Timeline of molecular mimicry as a concept. View in article Table 4 Molecular mimicry today. View in article REVIEW article Front. Immunol. , 22 September 2026 Sec. Autoimmune Disorders Volume 17 - 2026 | https://doi.org/10.3389/fimmu.2026.1922884 Molecular mimicry revisited: novel perspectives on autoimmune disease initiation and progression U C Urs Christen * E H Edith Hintermann Institute for Pharmacology and Toxicology, Goethe University Frankfurt, Frankfurt am Main, Germany Article metrics View details Abstract Molecular mimicry has long been implicated as one possible mechanism linking pathogen infection to autoimmunity, yet firm proof of its contribution to disease initiation and/or progression remains incompletely defined. In this review, we revisit the concept of molecular mimicry in light of recent advances in immunology, structural biology, and systems medicine. Beyond classical sequence homology, emerging evidence highlights the importance of structural and conformational epitope similarity, post-translational modifications, and context-dependent antigen presentation in shaping cross-reactive immune responses. We discuss how these factors influence the activation of autoreactive T and B cells, the breakdown of immune tolerance, and the establishment of chronic autoimmune disease. We further reevaluate the body of evidence for molecular mimicry as inducer and/or accelerator of specific autoimmune diseases ranging from mere association to proven causative relationship. Thereby, we further examine novel experimental approaches that have refined the identification of mimicry candidates and improved our understanding of their pathogenic relevance. By integrating classical paradigms with contemporary findings, this review provides a detailed outline for understanding molecular mimicry as a dynamic and multi-layered contributor to autoimmune disease. Introduction The first reference of the term “molecular mimicry” appears in a publication from Raymon T. Damian that suggested a sharing of antigenic structures (proteins, lipids, or carbohydrates) by parasite and host as a defense mechanism for pathogens to avoid being recognized by the host’s immune system ( 1 ). This concept has been formulated already two years earlier by Rowley and Jenkin who observed an antigenic cross-reactivity between parasite and host and postulated that serum factors, so-called opsonins, might be involved in the pathogenicity ( 2 ). As we know now such opsonins comprise a large group of proteins, including complement and antibodies, that tag bacteria or host cells to be recognized by phagocytes ( 3 ). Thus, from an evolutionary point of view it is beneficial for a pathogen to share structural similarities with the host to avoid being tagged by opsonins, such as specific antibodies, and to be eliminated eventually. For the host a more aggressive immune response is beneficial, since pathogen elimination is accelerated. Further, an uncompromising immune response is also better in recognizing modified self, such as cancer cells or neo-antigens arising through protein modification by xenobiotics. Thereby a more divers MHC repertoire might guarantee protection from a broader range of pathogens but also increases the probability of cross-reactivity with self-components. Thus, autoimmunity might be the price we pay for a better pathogen defense. The evolution of the immune system is a long-term process with pathogens trying to circumvent the defense mechanisms of the host and the host developing new mechanisms to overcome the new strategies of the pathogens ( Table 1 ). Molecular mimicry is just one of many evolutionary adaptations that facilitated pathogen survival. In order to counter this strategy, the host needed to further improve pathogen recognition and elimination, which might have come along with a possible self-reactivity. It seems that for a very long time such a trade-off survival against infection has outweighed later-life autoimmune costs. However, due to the changes in our lifestyle and the environment these costs may get bigger and bigger. Table 1 Phase Host defense Pathogen response Host countermeasures Preimmune age • Membranes • Chemical barriers • Membrane penetration • Horizontal gene transfer • Selective membrane transport • Early restriction modification Prokaryotic immunity • Restriction enzymes • CRISPR-Cas • Sequence mutations • Anti-CRISPR proteins • CRISPR diversification • Cas protein variants Early eukaryotes (Unicellular) • Phagocytosis • Autophagy • Intracellular survival (lysosomal resistance) • Hijacking of vesicular trafficking • Enhancement of lysosomal enzymes • Intracellular pattern recognition Innate immunity (Multicellular) • Pattern recognitions receptors (PPR, i.e. TLRs) • Pathogen-associated molecular pattern (PAMP) recognition • Pro-inflammatory factors • PAMP alteration • PAMP masking • Anti-inflammatory factors • PPR diversification and redundancy • Recognition of damage- associated molecular patterns (DAMPs) Innate immunity (Invertebrates) • Cellular defenses • Antimicrobial peptides (AMP) • RNA interference (RNAi) • Accelerated replication to exhaust defenses • RNAi suppression • AMP diversification • RNAi amplification loops Adaptive immunity and MHC immune surveillance • B and T cells • VDJ recombination (Antibody diversification) • Antigen presentation (MHC) • High rate of mutation • Antigenic variation • Phases of latency • MHC downregulation • Clonal expansion • B and T cell memory • Cytotoxicity • NK cells detect “missing self” Advanced vertebrate immunity • Antibody class switching • Mucosal immunity • Somatic hypermutation • Complex cytokine networks • Molecular mimicry • Exploitation of immune tolerance • Regulatory T cells • Immune balance Modern human technology • Antibiotics • Virostatics • Vaccination • Antibiotic-Resistance • Virostatic-Resistance • Antigenic escape variants • New antimicrobial drugs • Strain-matching vaccinations • Multivalent vaccines • Enhancement of T cell immunity Co-evolution of pathogen and host. Pathogens have influenced defense mechanisms of the host since the beginning of life. Such a co-evolution of pathogen and host led to the development of the immune system as we know it today. Molecular mimicry turned out to be a selective advantage for pathogens that share similarities of critical epitopes with the host in order to avoid being recognized as foreign. Note that this table is an approximation of the co-evolutionary events based on several reviews on that topic that does not claim to be complete ( 139 – 142 ). In contrast to the evolution of our immune system, the changes in our environment, as occurring in the last two centuries, are much quicker and leave only very limited time for adaptation. For example, within the lifespan of only a few generations the overall hygiene has changed dramatically for a large portion of humanity from an environment that has constantly exposed our organism to pathogens to clean, almost sterile, conditions in many regions today. In this context the hygiene hypothesis originally stating that allergies occur more frequently in families with only one or two children than in families with many siblings due to their lower exposure to common childhood infections ( 4 ) has been expanded to autoimmune diseases in the early 2000s ( 5 ). In the meantime, additional factors, such as the microbiome, dysbiosis, and multiple infections, have been integrated into the hygiene hypothesis ( 6 ). Thus, in a nutshell: An underemployed immune system may become dysregulated and targets self. Dysbiosis due to a modern lifestyle consisting of low-fiber, highly processed “Western” diet as well as high sugar and fat intake combined with an excessive use of antibiotics and reduced microbiota exposure early in life may contribute to immune system dysregulation ( 7 , 8 ). Furthermore, chemical pollutants, nanoparticles, and the excessive use of laundry detergents may cause epithelial barrier breaches resulting in microbial translocation and chronic immune activation ( 9 ). As demonstrated for Enterococcus gallinarum , gut commensial bacteria may themselves cause a barrier breach and translocate to other organs, such as the liver, where they may exacerbate autoimmunity ( 10 ). Indeed, E. gallinarum has been found in the liver of patients with autoimmune liver diseases and drives autoimmunity in mouse models ( 11 ). Thus, molecular mimicry between pathogen and host is just one out of many factors that contribute to the recent dramatic increase in the incidence of autoimmune diseases and allergies. Due to such multifactorial etiology firm proof of a contribution or even a critical role of any of these factors seems difficult. Pathogens may have beneficial (hygiene hypothesis) or detrimental effects on autoimmunity. Here the nature of the pathogens is an important factor. On the one hand, beneficial effects have been largely attributed to parasitic pathogens, including Helminths ( 12 ) that elicit a pronounced type 2 immune response and immunoregulatory circuits that largely tolerate the pathogen and thereby reduce tissue damage caused by an overly active immune response ( 13 ). On the other hand, intracellular pathogens, such as viruses, that induce a strong type 1 polarity, are with a few exceptions (for example cytomegalovirus seropositivity that is negatively associated with multiple sclerosis ( 14 )) predominantly associated with an initiation or exacerbation of autoimmunity ( 15 ). Here, we will review the evidence for molecular mimicry to initiate and/or accelerate certain autoimmune diseases. In addition, we would like to display how our current understanding of the molecular mimicry concept has changed from the initial postulation in the early 1960s and the first identification of sequence similarities in the 1980s. Pathogens as drivers of autoimmunity Pathogens have been widely associated with virtually all autoimmune diseases in the past. However, firm proof for pathogens as actual drivers of autoimmunity is rather difficult due to the following reasons: First, not all infected individuals develop the corresponding autoimmune disease or autoimmunity remains asymptomatic. Second, pathogens might act as “hit-and-run” events leaving no traces of their prior presence by the time of disease diagnosis. Third, every individual encounters numerous infections within their lifetime, some of which might leave traces of their existence or are even persistently present, but have no impact on autoimmunity. Fourth, epidemiologic observations and experimental evidence suggest that some pathogens have the potential to prevent or abrogate autoimmune processes. This circumstance is also supported by the hygiene hypothesis. Last, it is likely that for many autoimmune diseases not a single but multiple infectious events might be involved in their etiology. Considering that the burden of proof for pathogens to drive autoimmunity is stringent and often relies on information that is difficult to gather, it seems clear that demonstrating a critical role of molecular mimicry as a mechanism by which such pathogens indeed brake self-tolerance is even more problematic. At the end, molecular mimicry is just one of many possible mechanisms by which pathogens might be involved in the development of autoimmune diseases. For example, pathogen infections can cause the release of previously sequestered antigens or uncovering of cryptic epitopes to which no central tolerance has been established. Bystander activation through pro-inflammatory cascades may activate anergic, self-reactive T cells polyclonally. Similarly, bacterial superantigens may cross-link MHC and T cell receptor (TCR) without the requirement of a presented peptide. Further, pathogens might cause bystander suppression of regulatory T cells resulting in a shift of the immune balance towards a more aggressive response ( 16 ). Mechanism of molecular mimicry As such molecular mimicry appears to be a widespread phenomenon. Forty years ago, Sirinivasappa et al. screened more than 600 monoclonal antibodies raised against 11 different viruses and found that 3.5% of the antibodies reacted to specific cell types in organs from normal, uninfected mice ( 17 ). However, this study only demonstrated that the cross-reactivity of these anti-virus antibodies was sufficient to elicit an immunofluorescent signal on mouse tissue sections that has been considered “positive” or “weakly positive” ( 17 ). For molecular mimicry to indeed induce and/or accelerate autoimmunity several requirements must be fulfilled: First, the host has to be exposed to environmental factors, such as pathogens or xenobiotics. Second, such environmental factors need to share a structural similarity to one or more host components. Third, antibodies and/or T cells should exhibit cross-reactivity within a critical range of affinity. In this context, it is important to acknowledge that due to the high level of B cell receptor (BCR) and TCR degeneracy cross-reactivity may also occur for peptide sequences with only moderate similarity ( 18 ). In pathogen infections, sequential or conformational similarities between host and pathogen proteins are most frequently observed. In contrast, similar to hapten-carrier complexes known from hypersensitivity reactions, xenobiotics would need to modify self-proteins to form protein-adducts that share similarities to endogenous self-protein modifications. However, the mere formation of neo-antigens by chemicals does not necessarily result in molecular mimicry of (other) self-components. The formation of neo-antigens is well-documented for chemicals, such as the antihypertensive hydralazine, the antiarrhythmic agent procainamide, or the anesthetic agent halothane. Reactive metabolites of hydralazine and procainamide form neo-antigens that may cause drug-induced lupus erythematosus ( 19 ). Similarly, halothane, when metabolized by cytochrome P450 2E1 generates trifluoroacetylated-proteins (TFA-proteins) that are recognized as neo-antigens by the immune system and may cause an autoimmune-mediated halothane hepatitis in a minority of individuals ( 20 ). Initially, the immune response is directed against the protein modification itself; however, owing to epitope spreading, subsequent reactivity to unmodified epitopes results in chronic autoreactivity against the native proteins ( 21 ). Interestingly, TFA-proteins have endogenous human counterparts that can serve as molecular mimicry targets, namely enzymes of the 2-oxoacide dehydrogenase family, including the E2-subunit of the pyruvate dehydrogenase complex (PDC-E2) ( 22 , 23 ). In this case, patients’ cross-reactive antibodies recognize the lipoic acid prosthetic group of PDC-E2 ( 24 ). Interestingly, patients with halothane hepatitis were found to exhibit aberrant expression of the cross-reactive self-component PDC-E2 ( 25 ). Thus, in the majority of individuals molecular mimicry seems to instigate protection, rather than damage, by establishing immune tolerance not only to PDC-E2, but also to its mimicry counterpart, the TFA-modification. A well-characterized case of pathogen-induced protein modification is the citrullination of proteins by the oral pathogen Porphyromonas gingivalis through the bacterial peptidylarginine deiminase ( 26 ). The resulting citrullinated bacterial proteins resemble citrullinated host proteins, such as citrullinated α-enolase, and may contribute to the progression of rheumatoid arthritis (RA) through the generation of anti-citrullinated protein antibodies (ACPA) ( 27 ). Other post-translational modifications, including carbamylation, acetylation, or transglutaminase-mediated deamidation may also be important in generating neo-epitopes to which cross-reactive antibodies bind or which may alter peptide-MHC binding. Under inflammatory conditions carbamylation of proteins results in the conversion of lysine residues to homocitrullin. In RA the presence of homocitrullin may cause the formation of anti-carbamylated protein (anti-CarP) antibodies that are, like ACPA, cross-reacting with citrullinated α-enolase ( 28 , 29 ). Further, acetylation of lysine-residues to form acetyl-lysine may result in the generation of anti-acetylated protein antibodies (AAPA). In RA-patients all these anti-modified protein antibodies (AMPA) show considerable cross-reactivity with citrullinated, homocitrullinated/carbamylated, and acetylated proteins ( 30 ). Another interesting post-translational modification that may result in molecular mimicry is transglutaminase 2 (TG2)-mediated deamidation of glutamine to glutamate, which may occur within gluten peptides. Deamidated gluten peptides bind particularly well to HLA-DQ2 and HLA-DQ8, the major genetic susceptibility molecules for celiac disease (CD) ( 31 ). Thus, TG2-mediated gluten modification increases its immunogenicity and may even result in the generation of anti-TG2 autoantibodies, possibly through initial recognition of TG2-gluten complexes ( 32 , 33 ). Anti-TG2 autoantibodies are the hallmark autoantibodies in CD and plasma cells secreting TG2-specific IgA autoantibodies have been found in high abundance in CD intestinal lesions ( 34 ). As for deamidated gluten peptides, the MHC haplotype has a tremendous impact on molecular mimicry. Cross-reactivity can only occur if both mimicry partners are properly presented within the available MHC molecules. Indeed, rheumatic fever following group A streptococcal infection is associated with the presence of HLA-DR4, HLA-DR7, and HLA-DQ alleles (see below for more details on the evidence of molecular mimicry in rheumatic fever) ( 35 ). MHC haplotype susceptibility is more important for cross-reactive T cells but may also influence cross-reactive B cells through its effect on T cell help. Historically, because patients’ serum samples were relatively easy to analyze, more putative cases of molecular mimicry based on sequence homology were identified and verified for cross-reactive antibodies than T cells. However, only a minority of autoimmune diseases, such as Guillain–Barré Syndrome (GBS) or acute rheumatic fever (ARF), are predominantly autoantibody-mediated. Interestingly, GBS and ARF are diseases for which the strongest evidence exists for molecular mimicry as a driver of the disease (see below). In contrast, the majority of autoimmune diseases, including type 1 diabetes, multiple sclerosis, or autoimmune uveitis, are predominantly propelled by tissue-destructive autoreactive T cells. Indeed, detailed assessment of patients’ T cell repertoires confirmed the presence of cross-reactive T cells that target predicted epitopes of both pathogen and host. Thus, autoreactive T cells seem to be central orchestrators of molecular mimicry-driven autoimmunity ( 36 ). Overall, the degree of similarity of linear epitopes seems critical. Too low a similarity would result in a low affinity recognition by cross-reactive T cells. In contrast, a very high similarity, or even identity, might prevent T cell recognition due to a high degree of tolerance originating from the negative selection in the thymus. The
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