About this Research Topic
Forkhead box protein 3 (FOXP3) is an essential transcriptional regulator in the maintenance of self-tolerance and prevention of autoimmune diseases that regulates the function of CD4+ T regulatory cells (Tregs). The importance of FOXP3 protein in the homeostasis of the immune system is exemplified by FOXP3 mutations that impair or abrogate its expression and result in the early-onset and life threatening autoimmune disease, immune dysregulation, polyendocrinopathy, and enteropathy, X-linked (IPEX) syndrome. Without early diagnosis and timely treatment, IPEX syndrome can be lethal within the first years of life. Since its first definition in 2001, murine studies and human clinical and immunological investigations of affected patients have tremendously advanced awareness of the disease providing new insights into the pathogenesis, diagnosis and treatment of IPEX, as well as of similar genetic immune regulatory disorders, grouped as IPEX-like syndromes or Tregopathies.
This Research Topic will update understanding of the role of FOXP3 in the immune system and delineate how different FOXP3 mutations determine the clinical manifestations of IPEX Syndrome, thus enabling more effective diagnosis and treatment.
Although rare, detection of FOXP3 mutations has increased to include those that lead to severe disease manifestations, as well as those that cause recurrent milder autoimmunity, sometimes overlapping with inflammatory manifestations. These differing mutational FOXP3 alleles, and their impact on IPEX disease manifestations, allow us to pose the following questions: Is detection of FOXP3 mutation sufficient to make the diagnosis of IPEX or should we combine this with an independent molecular and/or functional biomarker of the disease? When should we intervene with suppressive treatments or bone marrow transplants? How aggressive and persistent should the treatment approach be in relation to the mutation, and the functional impairment?
Gathering insights of the best experts in the field and through Reviews, Mini Reviews, Perspectives and Opinion articles, we will:
• Summarize the current knowledge of FOXP3 function in mice and man, clarifying the differences between murine and human Treg cells;
• Recapitulate the genetics of IPEX syndrome and how different mutations are affecting protein expression and function;
• Provide an updated characterization of the protein structure and distribution and epigenetic regulation of expression;
• Look at all the possible clinical presentations of IPEX beyond the typically described severe presentation;
• Aim at more precise diagnosis targeted to better understand prognosis and guide treatments;
• Revise current treatments rationale and present the frontiers for novel curative options that are underway;
• Extend the “lesson learned” from IPEX to other Tregopathies.
Keywords: IPEX, FOXP3, Tregopathies, pediatric immunology, epigenetics
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