Autism is not one single disease but a suite of many, which is why researchers have long struggled to understand its underlying causes. Often referred to as the Autism Spectrum Disorders, autism has been linked to multiple genetic and environmental factors—different combinations of which can all result in autism or autistic-like behavior.
But as we first reported in last week’s Weekly Roundup, scientists at the University of California, Los Angeles (UCLA) have identified a new factor that can occur during pregnancy and that may be linked to the development of autism-like behavior. These results shed new light on a notoriously murky condition.
UCLA scientist Dr. Harley Kornblum led the study, which was published last week in the journal Stem Cell Reports.
In it, Kornblum and his team describe how inflammation in pregnant mice, known as ‘maternal inflammation’ caused a spike in the production of neural stem cells—cells that one day develop into mature brain cells, such as neurons and glia cells. This abnormal growth, the team argues, led to enlarged brains in the newborn mice and, importantly, autism-like behavior such as decreased vocalization and social behavior, as well as overall increase in anxiety and repetitive behaviors, such as grooming. As Kornblum explained in a news release:
“We have now shown that one way maternal inflammation could result in larger brains and, ultimately, autistic behavior is through the activation of the neural stem cells that reside in the brain of all developing and adult mammals.”
However, Kornblum notes that many environmental factors may cause inflammation during pregnancy—and the inflammation itself is not thought to directly cause autism.
“Autism is a complex group of disorders, with a variety of causes. Our study shows a potential way that maternal inflammation could be one of those contributing factors, even if it is not solely responsible, through interactions with known risk factors.”
These known risk factors include genetic mutations, such as those to a gene called PTEN, which have been shown to increase one’s risk for autism.
Further research by Kornblum’s team further clarified the connection between inflammation and neural stem cell overgrowth. Specifically, they noticed a series of chemical reactions, known as a molecular pathway, appeared to stimulate the growth of neural stem cells in the developing mice. The identification of pathways such as these are vital when exploring new types of therapies—because once you know the pathway’s role in disease, you can then figure out how to change it.
“The discovery of these mechanisms has identified new therapeutic targets for common autism-associated risk factors,” said Dr. Janel Le Belle, the paper’s lead author. “The molecular pathways that are involved in these processes are ones that can be manipulated and possibly even reversed pharmacologically.”
These findings also support previous clinical findings that the roots of autism likely begin in the womb and continue to develop after birth.
One key difference between this work and previous studies, however, was that most studies point to irregularities in the way that neurons are connected as a key factor that leads to autism. This study points to not just a network ‘dysregulation,’ but also perhaps an overabundance of neurons overall.
“Our hypothesis—that one potential means by which autism may develop is through an overproduction of cells in the brain, which then results in altered connectivity—is a new way of thinking about autism.”
Advances in the fields of stem cell biology and regenerative medicine have given new hope to families caring for autistic loved ones. Read more about one such family in our Stories of Hope series. You can also learn more about how CIRM-funded researchers are building our understanding of autism in our recent video: Reversing Autism in the Lab with help from Stem Cells and the Tooth Fairy.