Therapeutic bispecific T-cell engager (BiTEs) antibodies targeting cells presenting gliadin peptides
In autoimmune diseases, the body mounts harmful immune responses towards its own tissues. This process is driven by T cells and B cells that have antigen-specific receptors (TCRs and BCRs, respectively) that recognize self-molecules. Thus, therapeutic strategies that enable specific killing of such cells are of great interest to intervene with the autoimmune response.
Background: Celiac disease (CeD) is an inflammatory, autoimmune condition of the small intestine driven by a CD4 T-cell response towards deamidated gluten peptides from wheat, barley and rye . Activation of gluten-reactive CD4 T cells depends on recognition of gluten peptides presented on disease-associated HLA-DQ molecules on antigen-presenting cells (APCs). As such, this step is crucial for the initiation of the autoimmune response. Importantly, presentation is greatly facilitated if the gluten peptides are modified by an enzyme called transglutaminase 2 (TG2).
To characterize cells involved in presentation of gluten peptides, we have developed antibodies specific for the gluten peptide-MHC complex (pMHC) consisting of HLA-DQ2.5 with either of two different immunodominant gluten epitopes ( and Frick et al., manuscript in preparation). Using these antibodies, we have shown that plasma cells are the main gluten peptide-presenting cells in the intestinal mucosa of CeD patients . Interestingly, B cells and plasma cells specific for gluten and the self-protein TG2 are present in all CeD patients, but no pathogenic role of these cells had so far been identified.
The only current treatment option for CeD patients is a gluten-free diet. Furthermore, many CeD patients report difficulties to follow a strict gluten-free diet or may proceed to more severe disease stages. Thus, there is a motivation to explore new therapeutic strategies. In the long term, lesson learnt from CeD may also possibly be applied to other autoimmune disease.
Figure 1: The BiTE molecule can bind pMHC on the APC and CD3 on the cytotoxic T cell, thereby bridging the cells allowing specific killing.
In this master project, we will explore the therapeutic potential of antigen-specific removal of cells that are presenting gluten peptides using the specific anti-pMHC antibodies. “Bispecific T-cell engagers” (BiTEs) are proteins that combine two specificities in one molecule (Figure 1);
- targeting of a cell surface molecule on the cell to be killed with one arm, and
- targeting of a cell surface molecule on cytotoxic T cells with the ability to kill with the other arm.
Such BiTE formats are currently in clinical trials for cancer therapy . By using the scFv (variable region genes) of the pMHC-specific antibodies genetically linked to a scFv specific for the CD3 molecule expressed on T cells, it is possibly to force the cells presenting gluten peptides together with cytotoxic cells T cells with ability to kill the other cell. Here we will explore if this strategy can be used to specifically target and kill cells presenting gluten peptides. For these experiments, we have several sources of T cells and APCs available, including patient-derived cells. Finally, this concept will be tested in a mouse model.
Aim: To explore the therapeutic potential of antigen-specific removal of pathogenic cells. Sub goals:
- Construction of expression vectors encoding BiTE proteins
- Expression, purification and characterization of the BiTE proteins
- Functional assays to explore specific killing of cells presenting gliadin peptides
Methods: The student will gain experience in molecular techniques such as plasmid design and cloning to construct the various BiTE formats. The next part will involve methods such as protein expression, affinity purification, gel filtration, ELISA, SDS-PAGE and Western blot to express and validate the BiTE proteins. The last part will include cellular experiments such as flow cytometry, T-cell assays and assessment of the BiTE in mice.
The research environment: The group of Professor Ludvig Sollid is part of the K.G Jebsen Coeliac Disease Research Centre at the Institute of Immunology (Medical faculty, Rikshospitalet), a translational research center that studies all aspects of celiac disease. The research environment in the group and at the institute is ambitious, dynamic and highly collaborative. The Sollid group is a multinational research group (20+) consisting of master students, PhDs, post docs and researchers. Professor Inger Sandlie will co-supervise.
The master candidate: We seek a highly motivated and dedicated candidate. We expect you to read relevant research literature and take active part in our weekly group meetings. These meetings consist of scientific project meetings as well as journal clubs. By this, you will get a broader understanding of immunology and acquire presentation skills. The tasks within the master project are well defined and the project is as such of low risk, still the potential implications are great. We expect you to acquire good laboratory skills, become independent, and also learn to discuss with your fellow group members.
1. Sollid, L.M. and B. Jabri, Triggers and drivers of autoimmunity: lessons from coeliac disease. Nat Rev Immunol, 2013. 13(4): p. 294-302.
2. Høydahl, L.S., et al., Plasma Cells are the Most Abundant Gluten Peptide MHC-expressing Cells in Inflamed Intestinal Tissues From Patients With Celiac Disease. Gastroenterology, 2018.
3. Huehls, A.M., T.A. Coupet, and C.L. Sentman, Bispecific T-cell engagers for cancer immunotherapy. Immunol Cell Biol, 2015. 93(3): p. 290-6.