DESIGN
Description and Overall Design
Rheumatoid arthritis (RA) is a serious chronic, inflammatory and systemic autoimmune disease. It occurs virtually in all races of the world. RA presents great pain and financial burden for patients, but for the time being, there is no radical cure for RA. Therefore, it is necessary to develop a kind of novel targeted cell therapy for RA.
To solve the problems existing in the current treatment of RA, we design and build a brand new immunotherapy. FOXP3+ regulatory T cells, which can suppress and regulate immune reaction, are engineered by inserting a chimeric antigen receptor (CAR) using lentiviral vectors to recognize RA related inflammatory cells. At the same time, we insert another receptor to activate the functional stability pathway of regulatory T cells in the inflammatory environment, thus making it possible for them to be more immunosuppressive and more stable in lesions in hope for a better anti-RA effect. These two redirections of the two different systems on the native regulatory T cell response ensure both the efficacy and efficiency of our novel immunotherapy for RA.
![](https://static.igem.org/mediawiki/2017/5/56/T--CPU_CHINA--des-figure4.png)
SynNotch System
SynNotch is a system that is capable of specifically activating the expression of the USP7 gene in an inflammatory environment, thereby maintaining the activity of Treg cells by stabilizing the FOXP3 proteins.
![](https://static.igem.org/mediawiki/2017/5/53/T--CPU_CHINA--eng-figure3_7.png)
In our SynNotch system, we retain the functional sequence of the transmembrane domain and the cleavage site of the Notch 1 protein. At the N-terminus, we fuse the extracellular domain of IL17RA with Notch 1 to specifically recognize IL-17A secreted by Th17 cells, so that our regulatory T cells to obtain the ability to response to IL-17A. We also connect the gene of Gal4-vp64 (a fusion protein) in the downstream of Notch 1. In the presence of inflammatory cytokines IL17A, SynNotch protein is cleaved, and thus Gal4-VP64 fusion protein is detached from the cell membrane.
The released Gal4-VP64 will recognize UAS sequence in the upstream of promoter USP7 (in our another part BBa_K ) and then these two proteins combine together, which enable USP7 gene express with high efficiency. USP7 proteins will deubiquitinate the ubiquitinated FOXP3, so that enhance the stability of FOXP3 protein in the inflammation environment by protecting FOXP3 from degradation via ubiquitination. In this way, Treg cells can survive and play a role of immunosuppression.
CAR System
CAR-CD20 is a module that enables engineered modified T cells to specifically recognize the surface antigen CD20 in B lymphocytes and thus to play anti-inflammatory function. Our CAR-CD20 system is made up of the gene sequences of several proteins.
![](https://static.igem.org/mediawiki/2017/5/5a/T--CPU_CHINA--eng-figure3_9.png)