TRIM25 triggers pyroptosis through mitochondrial DNA release in intestinal ischemia-reperfusion injury.

Ischemia-reperfusion injury refers to the damage that occurs in an organ or tissue following the restoration of blood supply after a period of ischemia. Intestinal ischemia-reperfusion injury (I/R) represents a worldwide public health issue characterized by excessive inflammation and currently lacks effective clinical therapies. Activation of the NLRP3 inflammasome is not only a hallmark feature of intestinal I/R but also serves as a significant exacerbating factor in intestinal deterioration. TRIM25 is involved in regulating endoplasmic reticulum stress, the unfolded protein response, and inflammatory responses. However, its specific role in intestinal I/R remains unclear and may be associated with the activation of the NLRP3 inflammasome. In the intestinal tissues of mice subjected to intestinal I/R, TRIM25 expression was significantly upregulated and showed a positive correlation with NLRP3 inflammasome activation. Knockdown of TRIM25 suppressed hypoxia-reoxygenation (H/R)-induced activation of the NLRP3 inflammasome and the cGAS-STING pathway. It also reduced mitochondrial reactive oxygen species production, alterations in mitochondrial membrane potential, and cytosolic release of mitochondrial DNA. Moreover, NLRP3 inflammasome activation during intestinal I/R was attenuated by both cGAS knockdown and treatment with a specific cGAS inhibitor. Mechanistically, TRIM25 interacts with and potentially ubiquitinates the mitochondrial outer membrane phosphatase PGAM5, which leads to increased mitochondrial membrane permeability and thereby promotes the leakage of mtDNA into the cytosol. The leaked mtDNA is subsequently recognized by cGAS, initiating the activation of its downstream coupled STING pathway-a key component of the innate immune system responsible for detecting the presence of cytosolic DNA. Consequently, our results demonstrate that TRIM25-mediated mtDNA release, induced through its direct interaction with PGAM5, which in turn leads to the activation of the cGAS-STING pathway. This activation represents a critical determinant of NLRP3 inflammasome activation and intestinal injury. Accordingly, therapeutic targeting of this signaling pathway may hold potential for the treatment of intestinal I/R.