Childhood-onset systemic lupus erythematosus

Childhood-onset systemic lupus erythematosus (i.e., cSLE), also termed juvenile-onset systemic lupus erythematosus, juvenile systemic lupus erythematosus, and pediatric systemic lupus erythematosus, is a form of the chronic inflammatory and autoimmune disease, systemic lupus erythematosus (i.e., SLE), that develops in individuals up to 18 years old.^[1] Early-onset systemic lupus erythematosus is often used to designate a subset of cSLE patients who are up to 5 years old. Children with early-onset SLE tend to have a more severe form of cSLE than children who develop cSLE after 5 years of age.^[2]

cSLE does not include neonatal lupus erythematosus (nSLE). nSLE is a SLE-like disease that is present in infants at birth. It is caused by certain antinuclear antibodies, e.g., the immunoglobulin G types of the anti-SSA/Ro autoantibodies (e.g., anti-Ro/SS-A and anti-La/SS-B) and anti-nRNP (also termed anti-U1RNP). These antibodies form in the mother and pass from her circulation through the placenta to the fetus where they cause an often severe form of SLE that is evident in the fetus and newborn child. Most of the disorders in the infants disappear within months as these antibodies are naturally cleared from the infant. However, one disorder occurring in nSLE, congenital heart block, usually does not reverse and is potentially lethal. Fetuses and neonates with this heart block are implanted with an artificial cardiac pacemaker. However, recent studies have shown that hydroxychloroquine given to the mother in her 6th and 10th gestational weeks or intravenous immunoglobulin therapy given to the mother in her 14 and 18 gestational weeks reduces the incidence of developing this heart block (Intravenous immunoglobulins given to the mother suppress her production of antibodies including those that cause nSLE.).^[3][4]

cSLE, similar to adult-onset SLE (i.e. aSLE), is caused by an individual's production of antibodies that bind to antigens located in the individual's own cells' nuclei and cytoplasm. These antibody-antigen complexes trigger uncontrolled inflammation and injury in various tissues and organs (see below section on "Inflammation").^[5][6] Worldwide, the prevalence of cSLE is 1.9–25.7 per 100,000 children and its incidence is 0.3–0.9 per 100,000 per year.^[7] While there are similarities between the childhood and adult forms of SLE (i.e., aSLE), cSLE has several characteristics that make it a clinical entity distinct from aSLE. For example, cSLE has a more aggressive disease onset and course, more frequent disease exacerbations, more severe organ damages, and a higher mortality rate than aSLE.^[1][6][7]