We were inspired by a subtype of autism, which is classified as an autoimmune disorder. The concentration of autoantibodies in the cerebrospinal fluid of children with the disease has been tested to be significantly higher.

This leads us to think that there may be a problem with the blood-brain barrier in these children, which allows large molecules such as antibodies to enter the brain and attack neurons.

Therefore, we are trying to find a way to block the high expression of antibodies in patients, so as to achieve the effect of treating this disease. After group discussion, we decided to synthesize a small molecule metabolite of intestinal flora through synthetic biology method, bind specifically to antibodies, thereby reducing antibody concentration and relieving symptoms.

After reviewing the literature, we finally identified three kinds of antibodies, including anti-GM1[ Mostafa GA, Al-Ayadhi LY. Increased serum levels of anti-ganglioside M1 auto-antibodies in autistic children: relation to the disease severity. J Neuroinflammation. 2011 Apr 25;8:39.],anti-GAD[ Aslan C, Konuşkan B, Şener B, Ünal F. Comparison of serum anti-neuronal antibody levels in patients having autism spectrum disorder with and without regression. Turk J Pediatr. 2021;63(5):780-789. doi: 10.24953/turkjped.2021.05.006. PMID: 34738360.], and anti-MBP[ Mostafa GA, Al-Ayadhi LY. A lack of association between hyperserotonemia and the increased frequency of serum anti-myelin basic protein auto-antibodies in autistic children. J Neuroinflammation. 2011 Jun 22;8:71. doi: 10.1186/1742-2094-8-71. PMID: 21696608; PMCID: PMC3142225.].For each of these antibodies, there is strong evidence that they are associated with subtypes of ASD.

However, considering the need to understand the antibody structure in bioinformatics in order to find the corresponding small molecule metabolites, we finally decided to use anti-GM1,anti-GAD and anti-MBP as the antibodies for study, and finally verified the efficiency through molecular docking experiments.

As for project design, we proposed to utilize small molecule metabolites screened from the Gut Microbial Metabolite Library to bind to the autoantibodies in brain of children with ASD by competitive inhibition, thus blocking autoantibody to neurons and alleviating neural damage to a certain extent in an immune-related subtype of ASD.

Firstly, we performed molecular docking analysis to screen the small molecule metabolites that can bind to the auto-antibodies and induce inactivation of antibody.

Secondly, we found bacteria capable of producing this metabolite in the gut microbiota repertoire. We induced this bacterium to produce this metabolite in large quantities by over-expressing some key enzymes in the production pathway to bind the autoantibody.

Finally, we control the production of the engineered bacteria by suicide switch design to achieve the purpose of regulation.

In this project, from the perspective of small molecule blocking antibodies,we innovatively utilize small molecule metabolites from the Gut Microbial Metabolite Library and designed a certain amount of the selected intestinal metabolites through synthetic biology, which provides a new therapeutic target for the treatment of ASD.