P1174 Engineering therapeutic Tregs to overexpress GPR15 improves functional fitness for in vivo gut homing
T M Müller, L J Liu, M Wiesinger, I Atreya, B Siegmund, R Atreya, C Berking, M F Neurath, C Voskens, S ZundlerAbstract
Background
Inflammatory bowel diseases (IBD) like Crohn’s disease and ulcerative colitis, are marked by an imbalance of pro- and anti-inflammatory T cells in the lamina propria of the intestinal tract. Only subgroups of patients respond to current therapeutic approaches designed to restrain pro-inflammatory cells or signalling. Adoptive transfer of autologous ex vivo expanded regulatory T cells (Tregs) has previously been suggested as a promising future therapeutic approach to resolve chronic intestinal inflammation by promoting anti-inflammatory pathways.
Methods
Using a previously established protocol for the ex vivo expansion of Tregs (Investigational Medicinal Product-Tregs; IMP-Tregs), we characterized the migration and homing capabilities as well as the immunosuppressive function of non-expanded and IMP-Tregs using 3D-motility, in vivo gut homing and T cell suppression assays. Furthermore, via electroporation with GPR15 mRNA, IMP-Tregs were engineered to express the gut homing marker GPR15 and tested for their functional fitness in dynamic adhesion, T cell suppression assays as well as in vivo gut homing assays.
Results
Our data show that while the expansion protocol generates highly suppressive Tregs, only a fraction of them is equipped with surface molecules for gut homing. In order to overcome this limitation, we successfully engineered IMP-Tregs to express the gut homing marker GPR15. On a functional level, this led to improved adhesion to the cell adhesion molecules MAdCAM-1 and VCAM-1, which are expressed on the intestinal endothelium, as well as to increased gut homing in a humanized in vivo mouse model without affecting the immunosuppressive character of the engineered IMP-Tregs.
Conclusion
In conclusion, our data indicate superior functional fitness of GPR15-engineered IMP-Tregs for homing to the inflamed gut nominating them a promising further development of autologous Treg transfer therapy for IBD.