Interstitial lung disease and the STING pathway

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Abstract

Identification of the genetic mutations underlying the ultrarare monogenic conditions STING-associated vasculopathy with onset in infancy (SAVI) and coatomer protein complex subunit alpha (COPA) syndrome revealed a role for the stimulator of interferon genes (STING) immune pathway in the pathogenesis of interstitial lung disease (ILD) in these conditions. STING-focused therapeutics could be a potential avenue for the treatment of SAVI and COPA syndrome in the future, yet the relevance of STING to more common types of ILD is not clear. Here, we provide an overview of SAVI and COPA syndrome, the nature of ILD in these conditions, and current evidence regarding STING activity in their pathogenesis. We discuss data from studies of a variety of other ILDs and model systems and explore the potential role for STING in more common forms of ILD.

Authors

Prasad Palani Velu, Gaofeng Zhu, Karen J. Mackenzie

Autoinflammatory syndromes of STING and TREX1 dysfunction

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Abstract

Breakthroughs in rare genetic disease research elucidate the relationships among cytosolic DNA sensing, genome instability, and autoimmune disease phenotypes. Cytosolic self-DNA is a potent trigger of innate immunity, activating the DNA sensor cyclic GMP-AMP synthase (cGAS) and its downstream effector stimulator of interferon genes (STING). This pathway is negatively regulated by the DNA-degrading enzyme three-prime repair exonuclease 1 (TREX1); loss-of-function TREX1 variants lead to accumulation of cytosolic DNA, resulting in STING-mediated autoinflammation. Similarly, STING gain-of-function mutations cause STING-associated vasculopathy with onset in infancy, another disease characterized by multi-organ damage, disability, and premature death. The TREX1-cGAS-STING pathway has also been implicated in regulation of genome stability. Indeed, DNA damage lies at the heart of a separate TREX1-mediated disease, known as retinal vasculopathy with cerebral leukoencephalopathy, where the aberrant nuclear activity of mislocalized TREX1 damages genomic DNA, resulting in multi-organ degeneration syndrome with features of autoimmunity. Thus, monogenic autoimmune diseases and DNA damage syndromes sometimes overlap clinically, and the study of these diseases has created pathways for developing first-in-class small molecule therapeutics.

Authors

Debby J. Park, Kate M. Jones, Jessica B. Anderson, Amanda V. Finck, Jonathan J. Miner

Expanding roles of cGAS-STING signaling in neuroinflammation

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Abstract

The cyclic GMP-AMP synthase–stimulator of interferon genes (cGAS-STING) pathway is a central mediator of cytosolic DNA–induced innate immune responses, driving the production of type I IFNs and pro-inflammatory cytokines. Beyond its canonical role in cytosolic DNA sensing, increasing attention has been directed toward the noncanonical functions of cGAS and STING, particularly within the nucleus. Recent studies implicate dysregulated cGAS-STING signaling in neurodegenerative diseases and brain aging, with a prominent contribution to glial activation–associated neuroinflammation, a hallmark of many neurological disorders. In this Review, we first summarize the molecular mechanisms underlying the canonical cGAS-STING pathway in DNA sensing and innate immune activation. We then discuss emerging noncanonical roles of cGAS in chromatin organization and RNA metabolism, drawing on insights from evolutionary conservation and protein interactome analyses. Finally, we outline the involvement of cGAS-STING signaling in diverse aspects of brain function, including glial state regulation, neuronal homeostasis, blood-brain barrier integrity, and peripheral immune surveillance, highlighting their contributions to neuroinflammation and neuropathology. We also summarize current pharmacological inhibitors targeting cGAS and STING and discuss their therapeutic potential for modulating cGAS-STING signaling to manage brain disorders.

Authors

Weixi Feng, Abulimiti Aikedan, Subhash C. Sinha, Li Gan