Complex sentence: The immune system is thought to play an important role in autism, autistic children have been found by researchers to have inflammation of both the peripheral and central immune systems as indicated by increased levels of pro-inflammatory cytokines and significant activation of microglia.
Split into simpler sentences: The immune system is thought to play an important role in autism. Autistic children have been found by researchers to have inflammation of both the peripheral and central immune systems as indicated by increased levels of pro-inflammatory cytokines and significant activation of microglia.