Low plasma progranulin levels in children with autism

BACKGROUND: Autoimmunity to brain may play a pathogenic role in autism. In autoimmune disorders, the formation of antigen-antibody complexes triggers an inflammatory response by inducing the infiltration of neutrophils. Local administration of recombinant progranulin, which is an anti-inflammatory neurotrophic factor, potently inhibit neutrophilic inflammation in vivo, demonstrating that progranulin represents a crucial inflammation-suppressing mediator. We are the first to measure plasma progranulin levels in autism. METHODS: Plasma levels of progranulin were measured, by ELISA, in 40 autistic patients, aged between 3 and 12 years, and 40 healthy-matched children. RESULTS: Autistic children had significantly lower plasma progranulin levels, P = 0.001. Reduced plasma progranulin levels were found in 65% (26/40) of autistic children. On the other hand, there was a non significant difference between plasma progranulin levels of children with mild to moderate autism and patients with severe autism, P = 0.11. CONCLUSIONS: Plasma progranulin levels were reduced in a subgroup of patients with autism. Progranulin insufficiency in some patients with autism may result in many years of reduced neutrotrophic support together with cumulative damage in association with dysregulated inflammation that may have a role in autism. However, these data should be treated with caution until further investigations are performed, with a larger subject population, to determine whether the decrease of plasma progranulin levels is a mere consequence of autism or has a pathogenic role in the disease. The role of progranulin therapy should also be studied in autism.