Lipid Antigen Presentation as a Driver of T2D Inflammation

PROJECT SUMMARY Substantial research effort has uncovered a critical role for chronic inflammation in the development of insulin resistance, a hallmark of Type 2 Diabetes (T2D). Even with this discovery, no successful anti-inflammatory therapeutics have been developed, and research has stagnated with a focus on characterizing adipose tissue inflammation in mouse models of T2D. Importantly, the initiator of chronic inflammation in T2D remains unknown. Type 2 Diabetes presents with autoantibodies against a wide array of self-proteins, but protein screens for antibody reactivity have not discovered initiators of T2D inflammation. Remarkably, not all autoantigens in T2D are protein. We have identified lipid autoantigens in T2D that have been completely overlooked, likely due to the proteins which present lipid antigen, Group 1 CD1 molecules, not being expressed in mice. This lack of expression has left a gaping hole in our understanding of lipid antigens in immunological homeostasis and disease, especially T2D. To remedy this issue, we will use transgenic mice which express human CD1 molecules and in vitro models of human immune responses to understand lipid-mediated immune function in T2D. The long-term goal of this proposal is to establish a new scientific direction with the broad long-term purpose of understanding the role of lipids in pro-inflammatory responses, T2D, and autoimmune diseases. This proposal tests the overarching hypothesis that lipid antigen presentation is a key mechanism by which chronic inflammation in T2D is initiated. This innovative and novel investigation of lipid antigen presentation in T2D combines use of human blood samples, transgenic and humanized mice, single cell RNA sequencing, multiparameter cytokine analysis and flow cytometry, coupled with computational methods that allow for a systems biology approach to antigen discovery and hypotheses testing. In research Area 1, we will assess lipid antigen dependent activation of T cell responses. We will use humanized mice and human blood samples to interrogate the impact of these lipid antigens on T cell function in vitro (CD1 tetramer loading) and in vivo (high fat diet). In research Area 2, we will target lipid antigen presentation to prevent and treat T2D. The capacity of neutralizing antibodies targeted against group 1 CD1 molecules and lipid autoantigens to inhibit pro-inflammatory cytokines secreted from human immune cells and to prevent and treat disease in transgenic mice will be assessed. In research Area 3. Lipid autoantigen discovery in T2D will be performed with a novel 3D printed lipid microarray for antibody profiling. This proposal has the potential to redefine T2D as an autoimmune disease driven by lipid antigen presentation and completely change the strategies for management of disease and therapeutic development. Outcomes of this proposal will allow for the identification of specific inflammatory pathways that can be targeted for disease treatment.