Upstream drivers of type I interferons in lupus

Project Summary/Abstract This is a multi-PI project in which the 3 PIs each have a set of unique, but complimentary, cutting- edge technologies, patient resources, and computational tools that together enable us to fill a key knowledge gap: what are the upstream pathways that drive the chronic production of type I interferons (IFN-Is) in systemic lupus erythematosus (SLE)? Our work with focus on innate immune cells (neutrophils and monocytes) and skin biopsies from SLE patients (compared to healthy donors) obtained at the University of Washington and the University of Michigan, respectively. These samples will be subjected to ultrasensitive protein detection and protein- bound nucleic acid sequencing at Rockefeller University, as well as joint experiments in the first two labs. We anticipate that the synthesis of data from these approaches will be transformative for our understanding of SLE pathogenesis and the molecular mechanisms of lupus flares. Our aims are: AIM 1. To identify the NA(s) that triggers IFN-I production in SLE neutrophils and monocytes. Because SLE is a systemic disease involving numerous cell types, including immune cells, we focus this aim on neutrophils and monocytes. This choice is in part based on many recent papers indicating that they play an important role in SLE and in part because our preliminary data show that neutrophils are much altered in this disease, contain all the components for nucleic acid sensing and IFN-I production, and are the lineage with the highest retrotransposon expression. Monocytes likely play a (similar?) role in SLE. In this Aim, we will focus on identifying the nucleic acid species that are associated with the nucleic acid sensors that drive IFN-I using ultrasensitive detection methods. AIM 2. To identify the pathogenic DNA species that triggers IFN-I production in lupus skin. The skin is a key location of pathology in SLE patients. Ultraviolet (UV) light triggers flares of rashes and systemic disease in SLE patients, yet the reasons for this are unknown. IFN-Is are chronically upregulated in SLE epidermis, drive inflammatory responses in the skin, and are dysregulated after UV light exposure such that more IFN-I is produced in SLE vs. healthy control skin. The reasons for increased IFN-I production in SLE skin remain undefined yet are critical targets for novel therapeutic development and flare prevention. In this Aim, the macromolecular aggregates of nucleic acid sensors and the associated nucleic acids will be identified in keratinocytes before and after UVB exposure and the source of the pathogenic nucleic acid(s) determined.