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Microbes & Immunity Infectious agents and autoimmune diseases

and, as their name denotes, they are directly related to Table 1. Correlations between common autoimmune
infections by gram-positive or spherical bacteria. diseases and specific pathogens
Moreover, inflammatory bowel diseases, comprising Autoimmune Pathogens
Crohn’s disease and ulcerative colitis, have been related to disease
gastrointestinal pathogens, such as Campylobacter species, Crohn’s disease Campylobacter species, Salmonella species,
Salmonella species, enterohepatic Helicobacter species, enterohepatic Helicobacter species,
Mycobacterium avium paratuberculosis, Clostridioides Mycobacterium avium paratuberculosis,
Clostridioides difficile, and Listeria
difficile, and Listeria monocytogenes. Notably, several monocytogenes
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gastrointestinal microbes and intestinal helminths have Graves’s disease Hepatitis C virus, Coxsackie virus, Yersinia
been inversely associated with the risk of inflammatory enterocolitica, Borrelia burgdorferi, Helicobacter
bowel diseases. 23 pylori, and retroviruses
Similarly, autoimmune thyroid diseases, namely, Guillain-Barré Campylobacter jejuni, cytomegalovirus,
Graves’s and Hashimoto’s diseases, have been correlated syndrome Epstein-Barr virus, influenza A virus,
Mycoplasma pneumoniae, and Haemophilus
with many types of infectious agents, such as hepatitis C influenzae
virus, Coxsackie virus, Yersinia enterocolitica, Borrelia Hashimoto’s disease Hepatitis C virus, Coxsackie virus, Yersinia
burgdorferi, Helicobacter pylori, and retroviruses. 24 enterocolitica, Borrelia burgdorferi, Helicobacter
Other autoimmune diseases could also be induced or pylori, and retroviruses
exacerbated by many different microbial infections, as Multiple sclerosis Herpes, viruses of the human endogenous
summarized by Von Herrath et al. Multiple sclerosis, for retrovirus family, protozoa, and bacteria
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instance, has been related to viruses of the herpes and the PANDAS Gram-positive or spherical bacteria.
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human endogenous retrovirus families, as well as protozoa Rheumatoid arthritis Epstein-Barr virus
and bacteria. At the same time, Guillain-Barré syndrome Sjogren’s syndrome Epstein-Barr virus and hepatitis C virus
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has been associated mainly with Campylobacter jejuni, Sydenham chorea Hemolytic streptococcus
cytomegalovirus, Epstein-Barr virus, influenza A virus, Systemic lupus Epstein-Barr virus
Mycoplasma pneumoniae, and Haemophilus influenzae. In erythematosus
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addition, primary Sjögren’s syndrome has been related to Type 1 diabetes Coxsackie enterovirus
infections by viruses, such as Epstein–Barr and hepatitis C. 30
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Ulcerative colitis Campylobacter species, Salmonella species,
The correlations between common autoimmune enterohepatic Helicobacter species,
diseases and specific pathogens are summarized in Table 1. Mycobacterium avium paratuberculosis,
The content should be considered as indicative, as a Clostridioides difficile, and Listeria
comprehensive review of all research relating autoimmune monocytogenes
diseases to microbial infections is beyond the scope of this Abbreviation: PANDAS: Pediatric autoimmune neuropsychiatric
paper. disorders associated with streptococcal infections.
The role of Vitamin D in alleviating symptoms of key role in the proposed conceptual model of autoimmune
inflammatory bowel diseases through “restoration” of diseases, as it takes time for cellular alterations to accumulate
intestinal microbiota and, eventually, of the gut barrier to a detectable or recognizable extent.
function, is also indicative of the complex relationship
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between microbes and autoimmune diseases. 3. Contribution of the proposed model to
Moreover, another important correlation between the understanding of autoimmunity
pathogens and autoimmunity is found in the mechanism
of bystander activation. 10,32,33 This phenomenon refers to While the correlation of autoimmunity with infectious
the activation of T cells without antigen recognition, which agents is well established, the mechanisms involved are not
is indirectly caused by the inflammatory environment completely understood, and many relevant issues remain
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generated during immune responses to pathogens. obscure. The conceptual model proposed in this paper
Bystander activation plays an important role in triggering or allows for new explanations of some important features of
aggravating autoimmune diseases, such as multiple sclerosis, autoimmune diseases, which are outlined in the following
rheumatoid arthritis, type 1 diabetes, and autoimmune paragraphs.
encephalomyelitis. Progressive forms of autoimmune diseases can be
Autoimmunity has also been related to virus explained in the following way: The patient’s immune
persistence. 33,34 The persistence of infectious agents plays a system targets specific cells (e.g., myelin in multiple

Volume 2 Issue 4 (2025) 19 doi: 10.36922/MI025100017