ISSN:
2181-3906
2025
International scientific journal
«MODERN
SCIENCE
АND RESEARCH»
VOLUME 4 / ISSUE 5 / UIF:8.2 / MODERNSCIENCE.UZ
1104
PATHOPHYSIOLOGY OF AUTOIMMUNE DISEASES MECHANISMS OF IMMUNE
TOLERANCE DISRUPTION
Sultanov Samadjon
Assistant of the Department of “Pathology and Forensic Medicine”,
Central Asian Medical University.
Xotamov Muhammadzakaryo Bahodirjon oʻgʻli
Central Asian Medical University, Dentistry Department, 2nd year, Group 523 student.
https://doi.org/10.5281/zenodo.15477844
Abstract. This article explores the complex pathophysiology of autoimmune diseases with
a primary focus on the mechanisms underlying the breakdown of immune tolerance. Immune
tolerance is essential for preventing the immune system from attacking the div’s own tissues.
The review covers both central and peripheral tolerance processes, highlighting how
genetic predispositions, environmental factors, and immune regulatory failures contribute to the
development of autoimmunity. Key cellular players, such as regulatory T cells and antigen-
presenting cells, are discussed in relation to their roles in maintaining immune homeostasis.
Additionally, the article examines current understanding of molecular mimicry, epitope
spreading, and other pathogenic mechanisms leading to self-reactivity. The challenges in
diagnosis and treatment of autoimmune diseases are also addressed, emphasizing the need for
targeted therapeutic approaches aimed at restoring immune tolerance rather than merely
suppressing immune responses.
Keywords: Autoimmunity, Tolerance, Apoptosis, Antigen, Epitope, Autoantidiv,
Lymphocyte, Cytokine, Inflammation.
ПАТОФИЗИОЛОГИЯ АУТОИММУННЫХ ЗАБОЛЕВАНИЙ МЕХАНИЗМЫ
НАРУШЕНИЯ ИММУННОЙ ТОЛЕРАНТНОСТИ
Аннотация. В статье рассматривается сложная патофизиология аутоиммунных
заболеваний с упором на механизмы, лежащие в основе нарушения иммунной
толерантности. Иммунная толерантность необходима для предотвращения атаки
иммунной системы на собственные ткани организма. Обзор охватывает как
центральные, так и периферические процессы толерантности, подчеркивая, как
генетическая предрасположенность, факторы окружающей среды и нарушения
иммунной регуляции способствуют развитию аутоиммунитета. Ключевые клеточные
игроки, такие как регуляторные Т-клетки и антигенпрезентирующие клетки,
обсуждаются в связи с их ролью в поддержании иммунного гомеостаза. Кроме того, в
статье рассматриваются современные представления о молекулярной мимикрии,
распространении эпитопов и других патогенных механизмах, приводящих к
аутореактивности. Также рассматриваются проблемы диагностики и лечения
аутоиммунных заболеваний, при этом подчеркивается необходимость целенаправленных
терапевтических подходов, направленных на восстановление иммунной толерантности,
а не просто на подавление иммунных реакций.
Ключевые слова: Аутоиммунитет, Толерантность, Апоптоз, Антиген, Эпитоп,
Аутоантитело, Лимфоцит, Цитокин, Воспаление.
ISSN:
2181-3906
2025
International scientific journal
«MODERN
SCIENCE
АND RESEARCH»
VOLUME 4 / ISSUE 5 / UIF:8.2 / MODERNSCIENCE.UZ
1105
Introduction
Autoimmune diseases are a broad class of disorders in which the immune system,
designed to defend the div against pathogens, mistakenly targets its own healthy tissues and
organs. This erroneous immune response leads to chronic inflammation, tissue destruction, and
progressive dysfunction in affected organs. Common autoimmune diseases include systemic
lupus erythematosus, rheumatoid arthritis, type 1 diabetes mellitus, and multiple sclerosis, each
of which displays unique clinical manifestations but shares a fundamental breakdown in immune
self-tolerance. Under normal physiological conditions, the immune system employs intricate
control mechanisms to prevent self-reactivity. These mechanisms are collectively referred to as
immune tolerance and are vital in distinguishing between foreign antigens and the div’s own
components. Immune tolerance is established in two primary ways: central tolerance, which
occurs during lymphocyte maturation in the thymus and bone marrow; and peripheral tolerance,
which functions in peripheral tissues to regulate mature lymphocytes that may have escaped
central deletion.
The breakdown of immune tolerance can be attributed to several overlapping factors,
including genetic predisposition (such as HLA gene variants), environmental triggers (like
infections, toxins, or dietary components), and defects in immune regulatory pathways. Failure
in the deletion or inactivation of autoreactive T and B lymphocytes permits these cells to survive,
proliferate, and initiate an immune attack against self-antigens. This results in the production of
autoantibodies, activation of complement pathways, and recruitment of inflammatory cells, all of
which contribute to tissue damage and disease progression. Furthermore, autoimmune diseases
are often multifactorial in origin, with hormonal influences (such as estrogen), epigenetic
modifications, and microbiota imbalances also playing critical roles in the disruption of immune
tolerance. Gender disparities observed in autoimmunity with females being disproportionately
affected further highlight the complexity of immune regulation.
Literature review and method
Autoimmune diseases develop when the immune system mistakenly targets and attacks
the div’s own cells and tissues. This abnormal immune response leads to chronic inflammation
and tissue destruction. Under normal conditions, the immune system is able to distinguish
between self and foreign molecules, a process regulated by immune tolerance. Immune tolerance
prevents harmful immune reactions against the div's own tissues. When immune tolerance
mechanisms fail, autoreactive immune cells become activated, leading to the onset and
progression of autoimmune diseases. Understanding the pathophysiology of these diseases
requires a thorough investigation of how immune tolerance is established and maintained, and
what causes its breakdown.
Immune tolerance refers to the immune system’s ability to avoid attacking the div's own
cells and molecules. It is essential for preventing autoimmune diseases and maintaining self-
tolerance. There are two primary types of immune tolerance: central and peripheral. Central
tolerance occurs during the development of immune cells in primary lymphoid organs, where
self-reactive cells are eliminated or inactivated. Peripheral tolerance acts on mature immune cells
that have escaped central tolerance, preventing their activation in peripheral tissues. Both types
are necessary to maintain immune homeostasis and prevent autoimmunity.
ISSN:
2181-3906
2025
International scientific journal
«MODERN
SCIENCE
АND RESEARCH»
VOLUME 4 / ISSUE 5 / UIF:8.2 / MODERNSCIENCE.UZ
1106
Central tolerance mainly occurs in the thymus for T cells and in the bone marrow for B
cells. During this process, developing lymphocytes are exposed to self-antigens. Those that
strongly recognize self-antigens undergo apoptosis, a process known as negative selection. This
eliminates potentially harmful autoreactive cells early in their development. Some self-reactive
cells can also differentiate into regulatory T cells, which help suppress immune responses. The
failure of central tolerance allows autoreactive lymphocytes to enter the circulation, increasing
the risk of autoimmune diseases. Peripheral tolerance controls immune cells that escape central
tolerance and enter peripheral tissues. It involves several mechanisms such as anergy (functional
inactivation), suppression by regulatory T cells, and deletion through apoptosis. Peripheral
tolerance also depends on the absence of co-stimulatory signals and the presence of inhibitory
signals that prevent activation of autoreactive cells. These processes ensure that immune
responses are limited to harmful pathogens and do not target self-antigens, maintaining immune
balance and preventing autoimmunity.
The breakdown of immune tolerance can be triggered by genetic factors, environmental
influences, and immune regulatory failures. Genetic predispositions, such as specific HLA
alleles, increase susceptibility to autoimmune diseases. Environmental factors include infections,
toxins, and dietary components that may modify self-antigens or activate immune cells
inappropriately. Defects in regulatory T cells, co-stimulatory molecules, or cytokine signaling
pathways can impair immune regulation. Together, these factors lead to the survival and
activation of autoreactive lymphocytes, initiating autoimmune responses. Once immune
tolerance is lost, autoreactive T and B cells attack self-tissues, causing chronic inflammation and
tissue injury. Autoantibodies produced by B cells can bind to self-antigens and activate the
complement system, enhancing inflammation. Infiltration of inflammatory cells leads to
destruction of target organs, such as joints in rheumatoid arthritis or pancreatic islets in type 1
diabetes. The chronic nature of these immune attacks results in progressive organ dysfunction
and clinical symptoms characteristic of autoimmune diseases.
Treatment of autoimmune diseases focuses on suppressing the aberrant immune response
and restoring tolerance. Conventional therapies include corticosteroids and immunosuppressive
drugs that reduce inflammation but have broad effects. Emerging approaches target specific
immune pathways, such as biologics that inhibit cytokines or deplete autoreactive cells.
Immunotherapy aimed at enhancing regulatory T cells or inducing antigen-specific
tolerance shows promise for more precise and long-lasting treatment. Advances in understanding
immune tolerance mechanisms pave the way for novel therapies that can prevent or reverse
autoimmune disease progression.
Discussion
The pathophysiology of autoimmune diseases is deeply rooted in the failure of immune
tolerance mechanisms. Both central and peripheral tolerance play indispensable roles in
preventing self-reactivity, and disturbances in either can contribute to the development of
autoimmunity. Genetic predisposition, combined with environmental factors such as infections or
toxins, can trigger immune tolerance breakdown, highlighting the multifactorial nature of these
disorders. One important aspect is the role of regulatory T cells (Tregs), which are crucial for
maintaining peripheral tolerance.
ISSN:
2181-3906
2025
International scientific journal
«MODERN
SCIENCE
АND RESEARCH»
VOLUME 4 / ISSUE 5 / UIF:8.2 / MODERNSCIENCE.UZ
1107
Dysfunction or deficiency of Tregs has been implicated in many autoimmune conditions,
emphasizing their potential as therapeutic targets. Additionally, molecular mimicry—where
foreign antigens resemble self-antigens can lead to cross-reactivity and immune activation
against self-tissues.
Despite significant advances in understanding immune tolerance mechanisms, many
questions remain. The precise triggers that shift the balance from tolerance to autoimmunity are
not fully understood, and individual variability in immune responses complicates diagnosis and
treatment. Moreover, current therapies largely focus on symptom management and immune
suppression rather than restoring tolerance, underscoring the need for more targeted and curative
approaches. Future research should prioritize identifying early biomarkers of tolerance
breakdown and developing antigen-specific immunotherapies that selectively re-establish
immune balance without broadly suppressing immunity. Integrating genetic, epigenetic, and
environmental data will also be vital to create personalized treatment strategies. Overall, a
comprehensive understanding of immune tolerance failure is essential for improving outcomes
for patients suffering from autoimmune diseases.
Conclusion
Autoimmune diseases result from a complex failure of the immune system to maintain
self-tolerance, leading to immune attacks against the div’s own tissues. Both central and
peripheral immune tolerance mechanisms are essential for preventing the activation of
autoreactive lymphocytes. Genetic predispositions, environmental triggers, and defects in
immune regulation collectively contribute to the breakdown of immune tolerance. This
breakdown initiates chronic inflammation and tissue damage, which characterize autoimmune
disorders. Despite advances in understanding the underlying mechanisms, many challenges
remain in diagnosing and effectively treating these diseases. Current therapies focus mainly on
suppressing immune responses rather than restoring normal immune tolerance. Future
therapeutic strategies should aim to specifically target the causes of immune tolerance failure and
promote long-lasting immune balance. Overall, deepening our knowledge of immune tolerance
and its disruption is crucial for developing more precise and effective treatments for autoimmune
diseases, ultimately improving patient outcomes and quality of life.
REFERENCES
1.
Abbas, A.K., Lichtman, A.H., & Pillai, S. (2018). Cellular and Molecular Immunology (9th
ed.). Elsevier.
2.
Rose, N.R., & Bona, C. (1993). Defining criteria for autoimmune diseases (Witebsky’s
postulates revisited). Immunology Today, 14(9), 426–430.
3.
Goodnow, C.C., Sprent, J., Fazekas de St Groth, B., & Vinuesa, C.G. (2005). Cellular and
genetic mechanisms of self tolerance and autoimmunity. Nature, 435(7042), 590–597.
4.
Davidson, A., & Diamond, B. (2001). Autoimmune diseases. The New England Journal of
Medicine, 345(5), 340–350.
5.
Sakaguchi, S., Yamaguchi, T., Nomura, T., & Ono, M. (2008). Regulatory T cells and
immune tolerance. Cell, 133(5), 775–787.
ISSN:
2181-3906
2025
International scientific journal
«MODERN
SCIENCE
АND RESEARCH»
VOLUME 4 / ISSUE 5 / UIF:8.2 / MODERNSCIENCE.UZ
1108
6.
Vinuesa, C.G., Sanz, I., & Cook, M.C. (2009). Dysregulation of germinal centres in
autoimmune disease. Nature Reviews Immunology, 9(12), 845–857.
7.
Tsokos, G.C. (2011). Systemic lupus erythematosus. The New England Journal of Medicine,
365(22), 2110–2121.
8.
Mathis, D., & Benoist, C. (2009). Aire. Annual Review of Immunology, 27, 287–312.
9.
Wucherpfennig, K.W. (2001). Mechanisms for the induction of autoimmunity by infectious
agents. Journal of Clinical Investigation, 108(8), 1097–1104.
