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Immune Aging and Autoimmune Diseases in Children

“…Although limited by the small patient numbers and heterogeneity of medical therapy, treatment of patients was not shown to influence the measured parameters [15,78]. However, as a clinical consequence, alterations of the naive T cell homeostasis or age-inappropriate thymus function may cause a dysfunction in reconstitution of the naive T cell compartment in JIA patients, which may be relevant in the context of new therapies or for the response to vaccinations or to infections with new pathogens [15][16][17]. This may be also of particular importance in the application of stem cell transplantation in severe cases of JIA.…”

“…Reduction of thymic output, as described after physiological thymic involution, and/or chronic peripheral activation and stimulation occurring in autoimmune conditions may contribute to reduced TREC levels and increased replication markers of naive T cells [15]. A decrease of peripheral blood CD4+CD45RA+ T cells in JIA patients may influence TREC amounts per naive T cells and can be due to several reasons: A diminution of thymic output, a switch to other phenotypes (for example CD45R0+ T cells), and an accumulation of this T cell subset at other sites [16].…”

“…Thus, more studies on early onset autoimmunity in children are needed in order to understand the mechanisms of T cell production and peripheral T cell maintenance under autoimmune conditions. Recent studies suggest that a disturbed T cell homeostasis with alterations mimicking the immunological findings of elderly people or adult patients with autoimmune diseases may be of relevance in the early stages of juvenile idiopathic arthritis (JIA) [15][16][17] and diabetes mellitus type I (T1DM) [18]. However, as autoimmunity is a multifactorial process, premature immunosenescence is certainly not the only mechanism that can induce autoimmunity in children.…”