STING-dependent Intestinal Regeneration upon Radiation Injury

Summary The intestinal epithelium is the fast renewing adult tissue and highly sensitive to genotoxic agents such as radiation and chemotherapy. Acute gastrointestinal (GI) injury can be lethal in radiation victims or dose-limiting in cancer patients, which can lead to chronic barrier dysfunctions that impair the quality of life in survivors. Radiation induced enteritis was first described in 1897, while there is still no FDA-approved treatment, in part due to limited understanding of how intestinal stem cell (ISC) injury is coupled to regeneration. We and others have established that the cell-intrinsic p53 pathway governs ISC intestinal regeneration using high dose total body irradiation (TBI) and abdominal irradiation (ABI) (with major bone marrow sparing) models. Our recent data indicate a novel role of “Niche” signals including innate immune signaling in intestinal regeneration. We demonstrated that a highly temporal and dynamic acute and local inflammation is “reparative”, which is activated by Stimulator of Interferon Genes (STING)-dependent Type 1 Interferon (IFN) response following delayed mitotic death to promote intestinal regeneration. Surprisingly, non-bone marrow (BM) STING plays a major role in acute crypt inflammation and regeneration. Remarkably, a single administration of IFNβ given 48 hours after TBI or ABI improved survival and intestinal regeneration in STING-deficient mice and WT mice. These data support that inducible production of IFNβ is necessary and sufficient to promote ISC and intestinal barrier recovery from radiation injury through a novel niche and immune-dependent mechanism. We will test this hypothesis with three specific aims using in vivo and ex vivo mouse and human intestinal organoids coupled with in depth mechanistic dissection. SA1. Dissect STING-dependent local IFNβ production in acute crypt regeneration. SA2. Elucidate STING-dependent immune targets for ISC regeneration. SA3. Establish IFNβ as a novel target to enhance long- term ISC and intestinal barrier recovery from radiation injury. The proposed studies will provide novel mechanistic insights in radiation-induced ISC regeneration through epithelial and immune interactions in the niche, and establish temporal STING/IFNβ signaling as a novel and normal tissue selective target to treat radiation-induced acute intestinal damage.