Autoimmune Diseases and Disorders of the Immune System

Study Notes

Autoimmune Diseases and Disorders of the Immune System

The human body's immune system is designed to recognize and eliminate foreign invaders such as pathogens while protecting against self damage. However, sometimes this delicate balance can go awry, leading to conditions where our immune cells mistakenly target healthy tissues – these conditions are known as autoimmune diseases.

To better understand autoimmune disorders, let's delve into their underlying mechanisms and some specific examples:

Mechanisms of Autoimmunity

Autoimmune diseases typically arise from either a dysfunction of the adaptive immune system (B and T cells) or innate immunity (macrophages, dendritic cells, etc.). Factors contributing to the development of autoimmune diseases may involve genetic predisposition, environmental triggers, hormonal influences, infections, and epigenetic changes. But how do they lead to misguided attacks?

Immune Tolerance: The normal functioning immune system maintains tolerance towards self-antigens by deleting autoreactive lymphocytes during maturation processes or through inhibitory signals on mature B and T cells. A breakdown in immune tolerance allows autoreactive cells to escape elimination, resulting in autoimmunity.
Molecular Mimicry: Injury or infection with certain microbes may cause the production of antigens that share similarity to host proteins, causing the immune system to attack these related healthy molecules accidentally. This phenomenon is called molecular mimicry.
Bystander Activation: During tissue injury or inflammation, cytokines released by damaged cells indirectly activate immune cells, accidentally triggering multiple reactions, including attacks on unaffected areas.

Specific Examples of Autoimmune Diseases

Rheumatoid Arthritis (RA) affects joints, particularly those in hands and feet, causing pain, swelling, stiffness and reduced mobility. RA involves a complex interplay between genetics, environment, and gender factors.
Multiple Sclerosis (MS) occurs when the protective covering of nerve fibers, myelin, breaks down due to leukocytic invasion, disrupting communication between nerves and muscles and leading to symptoms like muscle weakness, vision problems, cognitive difficulties, and mood disturbances.
Type I Diabetes results from destruction of insulin producing beta cells within pancreatic islets, leading to elevated blood glucose levels and necessitating lifelong insulin therapy.
Lupus is characterized by widespread inflammation caused by abnormal antibody formation against various cellular components, potentially affecting skin, kidneys, lungs, heart, brain, and joints. Lupus may also present in different forms based on which organs are most affected.

While current treatments help manage symptoms and prevent complications, developing new therapies that specifically target the root causes of autoimmunity remains a major challenge for researchers. Understanding individual disease pathologies, along with the discovery of novel biomarkers, will hopefully improve diagnosis and prognostication – ultimately leading to more effective treatment options in the future.

Description

This quiz explores the mechanisms behind autoimmune diseases and highlights specific examples such as Rheumatoid Arthritis, Multiple Sclerosis, Type I Diabetes, and Lupus. Learn about immune tolerance, molecular mimicry, and bystander activation, and understand how genetic, environmental, and hormonal factors contribute to the development of autoimmune disorders.