Studying ETS2-mediated monocyte activation in lupus

About This Grant

Project Summary/Abstract: The pathologic hallmarks of systemic lupus erythematosus (SLE or lupus) are altered immune responses to nuclear autoantigens with autoantibody production and subsequent tissue injury. In addition to adaptive immunity, innate immunity plays a role in lupus. Our published studies demonstrated IL- 1β and IL-18 production from human monocytes (MO) exposed to lupus U1-snRNP/anti-U1-snRNP antibody (Ab) or dsDNA/anti-dsDNA Ab immune complex (snRNP IC or dsDNA IC, also lupus IC refers to both) through the Toll-like receptors (TLRs) 7/8/9 and the NLRP3 inflammasome activation. The same lupus IC can induce other inflammatory cytokines such as IL-6, IL-8, and IL-23, which are increased in the peripheral blood, skin and/or kidneys of lupus patients. Erythroblast transformation specific 2 (ETS2) is a transcription factor that belongs to the ETS family. A recent study reported a role of ETS2 in regulating genes associated with inflammatory diseases in MO and macrophages (MΦ). The deletion of ETS2 in human MO resulted in decreased inflammatory cytokine production, including IL-1β, IL-6, and IL-8, up on differentiation into MΦ and subsequent stimulation with molecules including the TLR1/2 ligand Pam3CSK4. Indeed, overexpression of ETS2 in resting human MΦ increased inflammatory genes (e.g., IL1B, TNF, IL6, and IL23A) in response to the TLR4 ligand LPS. These findings support an important role of ETS2 in the development of inflammatory responses in human MO and MΦ. However, the role of ETS2 in the development of lupus IC-mediated inflammatory responses in MO and MΦ is unknown. Of note, our preliminary data show that snRNP IC induces activation (phosphorylation) and upregulation of ETS2 in human MO. Based on these observations, we hypothesize that ETS2 plays an important role in the development of lupus IC-driven inflammatory responses in MO and MΦ, contributing to the pathogenesis of lupus, and that such responses can be suppressed by small molecule(s). The hypothesis will be tested with the followings: 1) Aim 1 will elucidate the significance and mechanisms of lupus immune complex (IC)-mediated ETS2 activation in human MO and MΦ by assessing global transcriptomics, cytokine production, and cellular characteristics in human ETS2 knockout (KO) and control MO and MΦ as well as by dissecting the pathways involved in activating such cells in response to lupus IC and ETS2; and 2) Aim 2 will identify small molecule(s) that target ETS2 in human MO and MΦ stimulated with lupus immune complexes (IC) using a combination of computational and high-throughput screening approaches. Specifically, we will performing massive virtual screening of ~300,000 small molecules curated at the Yale Center for Molecular Discovery (YCMD) using our recently developed AI-based modeling of ligand-protein binding affinity and other tools including AlphaFold3 followed by ex vivo validation assays. Our study will be highly informative in understanding lupus pathogenesis and in developing new approaches for evaluating and treating lupus.