Glycans as Master Switches of B Cell Activity in Autoimmunity

Introduction

Autoimmune diseases including rheumatoid arthritis (RA) are often life-threatening disorders with increasing disability, having a negative impact on patients' quality of life. Mechanisms leading to the breach of tolerance in the development of autoimmunity are still largely unknown.

Importance of Protein Glycosylation

Protein glycosylation is an essential regulatory mechanism in the immune system. We recently demonstrated that N-glycosylation of the variable region (Fab) of autoantibodies is a hallmark of RA development and progression.

Early Detection of Glycosylation Signatures

We also demonstrated that autoantibodies acquire these Fab glycosylation signatures many years before disease onset.

Hypothesis

We herein hypothesize that Fab glycosylation at the level of the B cell receptor is a key molecular switch promoting the selection, activation, and proliferation of autoreactive B cells, leading to the concomitant breach of immunotolerance.

Objectives of GlycanSwitch

Within GlycanSwitch, we will:

1. Map the Fab glycome of various types of RA autoantibodies and autoreactive B cells.
2. Study the factors and underlying cellular mechanisms that regulate Fab glycosylation of B cell receptors and autoantibodies.
3. Investigate the immunological effects of Fab glycosylation and the impact on B cell signaling and activation in the context of molecular and cellular interacting partners in the immune microenvironment.

Experimental Approach

Finally, we will test in relevant mouse models how Fab glycosylation of autoantibodies and autoreactive B cells contributes to the breach of tolerance.

Expected Outcomes

We expect that the obtained insights into the role of glycans as a key checkpoint for the selection of autoreactive B cells and the rise of autoimmunity will provide leads for targeted therapeutic interventions, as well as rationales for the early detection of RA and autoimmune diseases in general.

Future Directions

We foresee that the knowledge generated will allow us to embark on a targeted prevention clinical study in patients at risk for RA to turn off the GlycanSwitch, leading to chronic RA.