Research Assistant Professor University of Michigan Ann Arbor, Michigan, United States
Disclosure(s):
Olesya Plazyo, MS, PhD: No financial relationships to disclose
Introduction/Rationale: Female bias in autoimmunity is attributed in part to incomplete X chromosome inactivation of immune genes such as TLR7. However, many female-biased genes dysregulated in autoimmune diseases are autosomal, including VGLL3, a transcriptional co-factor implicated in lupus, systemic sclerosis, and Sjogren’s syndrome. Notably, TLR7 is elevated 4.5-fold in mice overexpressing (OE) Vgll3 that develop lupus-like disease. We sought to define the mechanistic relationship between VGLL3 and TLR7 in female-biased autoimmunity.
Methods: Vgll3 OE mice were crossed with Tlr7 knock-out (KO) mice, and Vgll3 KO mice were treated with the TLR7 agonist imiquimod. Disease phenotypes were assessed by histology, ELISA for autoantibodies, and RNA-seq. VGLL3 binding at the TLR7 locus was assessed by CUT&RUN. Gene expression datasets from human cells with VGLL3 perturbation were examined for correlated lnRNAs, identifying NEAT1. TLR7-sensing HEKs were stimulated with NEAT1 or extracellular vesicles (EVs) from VGLL3 OE cells. Proximal biotinylation identified upstream regulators of VGLL3.
Results: Deletion of Tlr7 in Vgll3 OE mice did not prevent skin inflammation or splenomegaly; however, autoantibody production was reduced and inflammatory signature in skin and kidneys was attenuated, with stronger effect in females. Conversely, skin inflammation after imiquimod was diminished in Vgll3 KO mice (vs WT), accompanied by reduction of IFN-stimulated genes. CUT&RUN showed no VGLL3 binding near the TLR7 promoter, indicating indirect regulation. Instead, NEAT1 robustly activated TLR7, as did EVs from VGLL3 OE keratinocytes. KDM5C, an X-linked histone demethylase known to regulate XIST, was identified as an epigenetic regulator of VGLL3.
Conclusion: VGLL3 amplifies TLR7-driven inflammatory responses through indirect mechanisms involving NEAT1 and EV signaling, forming a feedforward loop that promotes IFN-mediated, sex-biased autoimmunity. Identification of KDM5C as a regulator of VGLL3 links this pathway to X-chromosome biology.
