Immune recognition of citrullinated epitopes

Area of Science:

• Immunology
• Biochemistry
• Molecular Biology

Background:

• Citrullination is a post-translational modification of arginine to citrulline.
• Aberrant citrullination can lead to autoimmunity by creating neo-antigens recognized by the immune system.
• This process is implicated in rheumatoid arthritis and other autoimmune conditions.

Purpose of the Study:

• To review the recognition of citrullinated antigens in human autoimmune diseases.
• To explore the role of citrullination in increasing antigenic diversity and evading tolerance.
• To discuss the mechanistic links between citrullination, inflammation, and infection.

Main Methods:

• Review of published literature on citrullination and autoimmunity.
• Analysis of studies investigating T-cell and autoantibody responses to citrullinated antigens.
• Examination of evidence implicating autophagy and membrane attack pathways in citrullination.

Main Results:

• Citrullinated proteins are targeted by autoantibodies in rheumatoid arthritis.
• Citrullinated peptides are preferentially presented by specific HLA class II molecules.
• Evidence suggests citrullinated epitopes are relevant in type 1 diabetes and multiple sclerosis.
• Inflammation or insult activates peptidyl deiminases, linking citrullination to environmental factors.
• Responses to citrullinated peptides may aid in clearing novel influenza strains.

Conclusions:

• Immune recognition of citrullinated epitopes is central to autoimmunity.
• Citrullination contributes to antigenic diversity and circumvents self-tolerance.
• Understanding citrullination offers insights into autoimmune disease initiation and cross-reactivity with pathogens.