Autism is associated with an increase in inflammation during second trimester.

We are beginning to understand more about how autism begins and the mounting evidence suggests that it is a combination of genetic factors and environmental exposures during pregnancy. There has also been mounting evidence that a family history of immune disorders is associated with autism (autism spectrum disorder ASD). Specifically, mothers with auto-immune disorders have an increased risk of having a child with ASD. Under normal conditions, the mother’s immune system is finely tuned to keep the fetus free of infections and in a non-inflammatory state. Recently, a group of researchers characterized the inflammatory environment of pregnant mothers during their second trimester and saw that elevated levels of inflammatory markers was associated with an increased risk of giving birth to a child with ASD.

The researchers used blood that was collected mid-pregnancy from 415 mothers whose children were diagnosed with ASD and 415 mothers whose children developed normally. The 415 ASD cases were then split based upon whether they showed intellectual disabilities or not and whether their autism was early or late onset. Late onset autism was classified in this study as developmental delay. In the blood of these mothers the researchers measured the levels of immune signals. Our immune system makes a variety of proteins called cytokines and chemokines that allow our cells to communicate and mount a proper attack on the foreign invader. Scientists can measure the levels of the signals as markers of inflammation in the body. In normal conditions there are very little of these proteins present in your blood. When the team compared the levels of these proteins in the blood between the different groups they found that the mothers whose children had developed autism with intellectual disabilities were more likely to have elevated levels of specific inflammatory markers (specifically GM-CSF, IL-1 alpha, IL-6, and IFN-gamma). Normally these markers would be decreased during pregnancy as the mother’s body tries to lower the level of inflammation to protect the fetus. The researchers also found that there were differences in the maternal blood levels of 9 cytokines/chemokines in children with ASD with intellectual disabilities compared to children with developmental delay. There were also 12 different cytokines/chemokines different in children with ASD and intellectual disability compared to children with ASD without intellectual disability.

This research highlights the impact the environment can have on a developing fetus. It also shows that there could be different origins for the different types of autism and that it may be naïve to think there is one universal cause for all ASD. We do not know yet if treating inflammation in these mothers would help in preventing the development of autism but future research should focus on understanding how the elevated levels of inflammation during pregnancy may affect the development of an infant’s brain. There is evidence that there are alterations in the connections of the brain of autistic children and it would be interesting to know if this is a cause of an altered inflammatory environment during pregnancy. Autism is a complex disease and while it is unlikely there is any one cause of the disease research like this is adding to our understanding of the disease.

Image Credit: Flickr hepingting

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