A novel opsonic eCIRP inhibitor for lethal sepsis

Identification of a multiple DAMP scavenger mimicking the DAMP-binding site of TLR4 to ameliorate lethal sepsis

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Current treatments are limited to source control and supportive care, underscoring the urgent need for novel therapeutic interventions. Endogenous molecules released from stressed or damaged cells, known as damage-associated molecular patterns (DAMPs), exacerbate inflammation, organ injury, and mortality in sepsis. In this study, we discovered a novel therapeutic compound, opsonic peptide 18 (OP18), designed to scavenge multiple DAMPs, including extracellular cold-inducible RNA-binding protein (eCIRP), high mobility group box 1 (HMGB1) and histone H3, by facilitating their clearance via macrophages. OP18 was developed by identifying a 15-amino acid (aa) binding site within the extracellular domain of Toll-like receptor 4 (TLR4) shared by eCIRP, HMGB1, and histone H3, then extending it with an αvβ3-integrin binding RGD (Arg-Gly-Asp) motif, resulting in an 18-aa peptide. Our data show that OP18 binds strongly to the above DAMPs and interacts with αvβ3-integrin on macrophages, promoting phagocytosis of DAMPs and facilitating their lysosomal degradation. In vitro, OP18 reduced the production of the inflammatory cytokine TNF-α in DAMP-activated macrophages and restored mitochondrial function, as evidenced by improved oxygen consumption rate (OCR) and ATP production. In a lethal sepsis model induced by cecal ligation and puncture (CLP), DAMP levels were significantly elevated, while OP18 treatment markedly reduced the serum DAMP levels. Additionally, OP18-treated septic mice demonstrated reduced blood organ injury markers, decreased proinflammatory cytokine levels, attenuated ALI, and improved survival. These findings establish OP18 as a promising therapeutic molecule that reduces DAMP-induced inflammation, offering a potential strategy to improve outcomes in lethal sepsis.

Anti-DAMP therapies for acute inflammation

Shock, affecting a third of intensive care patients, remains a highly fatal condition despite advances in critical care, irrespective of its etiology. Cellular injury, central to shock pathophysiology, triggers the release of damage-associated molecular patterns (DAMPs), such as extracellular cold-inducible RNA-binding protein (eCIRP), high-mobility group box 1 (HMGB1), histones 3 and 4, and adenosine triphosphate (ATP). These molecules are confined within cells under normal conditions and perform essential physiological functions. However, upon their extracellular release during cellular injury, they act as alarmins, engaging pattern recognition receptors (PRRs) on immune cells. This interaction triggers a robust inflammatory response, propagating systemic inflammation and exacerbating tissue damage. Excessive DAMP-mediated inflammation is increasingly recognized as a major contributor to morbidity and mortality in a wide range of critical illnesses, including trauma, hemorrhagic shock, sepsis, and organ ischemia/reperfusion (I/R) injury. These pathologies are characterized by uncontrolled inflammatory cascades driven by the deleterious effects of DAMPs, underscoring the urgent need for targeted therapeutic interventions. This review explores the pivotal role of DAMPs in the pathogenesis of acute inflammation and shock, highlighting cutting-edge therapeutic strategies aimed at mitigating their effects. Emerging approaches include monoclonal antibodies, decoy receptors, small molecule inhibitors, and scavengers designed to neutralize or inhibit DAMP activity. The discussion also delves into the potential clinical applications of these interventions, offering insights into how targeting DAMPs could transform the management of shock and improve patient outcomes.

Extracellular Cold-Inducible RNA-Binding Protein: Progress from Discovery to Present

Extracellular cold-inducible RNA-binding protein (eCIRP) is a critical damage-associated molecular pattern (DAMP) that drives inflammation and tissue injury in hemorrhagic and septic shock, and has emerged as a promising therapeutic target. Since then, extensive research using preclinical models of diseases and patient materials has explored eCIRP's role in driving inflammatory responses and its potential as a biomarker. The main objective of this comprehensive review is to provide a detailed overview of eCIRP, covering its discovery, role in disease pathophysiology, mechanisms of release and action, potential as a biomarker, and therapeutic strategies targeting eCIRP in preclinical models of inflammatory and ischemic diseases. We examine the molecular, cellular, and immunological mechanisms through which eCIRP contributes to disease progression, and explore both well-established and emerging areas of research. Furthermore, we discuss potential therapeutic strategies targeting eCIRP across a broad spectrum of inflammatory conditions, including shock, ischemia-reperfusion injury, neurodegenerative diseases, and radiation injury.

Milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3 (MOP3) attenuates inflammation and improves survival in hepatic ischemia/reperfusion injury

INTRODUCTION

Hepatic ischemia/reperfusion injury is a severe clinical condition leading to high mortality as the result of excessive inflammation, partially triggered by released damage-associated molecular patterns. Extracellular cold-inducible RNA-binding protein is a new damage-associated molecular pattern. Current clinical management of hepatic ischemia/reperfusion injury is limited to supportive therapy, necessitating the development of novel and effective treatment strategies. Milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3 is a newly invented oligopeptide originating from milk fat globule-epidermal growth factor-VIII. This peptide acts as an opsonic compound that specifically binds to extracellular cold-inducible RNA-binding protein to facilitate its clearance by phagocytes, thereby attenuating inflammation. In this study, we hypothesized that milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3 attenuated hepatic ischemia/reperfusion injury by inhibiting extracellular cold-inducible RNA-binding protein-induced inflammation in Kupffer cells.

METHODS

We treated Kupffer cells isolated from male C57BL/6 mice with extracellular cold-inducible RNA-binding protein and various doses of milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3 for 4 hours, then measured cytokines in the culture supernatants. In addition, mice underwent 70% hepatic ischemia for 60 minutes immediately followed by the intravenous administration of either vehicle or milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3. Blood and ischemic liver tissues were collected 24 hours later, and inflammatory markers including cytokines, liver enzymes, chemokines, myeloperoxidase activity, and Z-DNA-binding protein 1 were measured. Hepatic tissue damage and cell death were evaluated histologically. Survival rates were monitored for 10 days posthepatic ischemia/reperfusion.

RESULTS

The release of interleukin-6 and tumor necrosis factor-α from extracellular cold-inducible RNA-binding protein-challenged Kupffer cells was significantly reduced by milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3 in a dose-dependent manner. In hepatic ischemia/reperfusion mice, milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3 treatment significantly decreased serum levels of extracellular cold-inducible RNA-binding protein, interleukin-6, tumor necrosis factor-α, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. Milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3 treatment also significantly reduced mRNA levels of interleukin-6, tumor necrosis factor-α, interleukin-1β, Z-DNA-binding protein 1, and chemokine macrophage inflammatory protein-2, as well as myeloperoxidase activity in hepatic tissues. Histologic evaluation demonstrated that treatment with milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3 significantly attenuated tissue damage and cell death in the liver of hepatic ischemia/reperfusion mice. Milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3 treatment significantly improved the survival rate of hepatic ischemia/reperfusion mice.

CONCLUSION

Milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3 significantly attenuated inflammation and liver tissue damage and improved survival after hepatic ischemia/reperfusion. Thus, milk fat globule-epidermal growth factor-VIII-derived oligopeptide 3 holds promise as a potential future therapeutic strategy for hepatic ischemia/reperfusion injury.

Extracellular cold-inducible RNA-binding protein in CNS injury: molecular insights and therapeutic approaches

Central nervous system (CNS) injuries, such as ischemic stroke (IS), intracerebral hemorrhage (ICH) and traumatic brain injury (TBI), are a significant global burden. The complex pathophysiology of CNS injury is comprised of primary and secondary injury. Inflammatory secondary injury is incited by damage-associated molecular patterns (DAMPs) which signal a variety of resident CNS cells and infiltrating immune cells. Extracellular cold-inducible RNA-binding protein (eCIRP) is a DAMP which acts through multiple immune and non-immune cells to promote inflammation. Despite the well-established role of eCIRP in systemic and sterile inflammation, its role in CNS injury is less elucidated. Recent literature suggests that eCIRP is a pleiotropic inflammatory mediator in CNS injury. eCIRP is also being evaluated as a clinical biomarker to indicate prognosis in CNS injuries. This review provides a broad overview of CNS injury, with a focus on immune-mediated secondary injury and neuroinflammation. We then review what is known about eCIRP in CNS injury, and its known mechanisms in both CNS and non-CNS cells, identifying opportunities for further study. We also explore eCIRP's potential as a prognostic marker of CNS injury severity and outcome. Next, we provide an overview of eCIRP-targeting therapeutics and suggest strategies to develop these agents to ameliorate CNS injury. Finally, we emphasize exploring novel molecular mechanisms, aside from neuroinflammation, by which eCIRP acts as a critical mediator with significant potential as a therapeutic target and prognostic biomarker in CNS injury.

A NOVEL OPSONIC EXTRACELLULAR CIRP INHIBITOR MOP3 ALLEVIATES GUT ISCHEMIA/REPERFUSION INJURY

ABSTRACT

Introduction: Gut ischemia and reperfusion (I/R) injury promotes the release of damage-associated molecular patterns (DAMPs) such as extracellular cold-inducible RNA-binding protein (eCIRP). Gut I/R often leads to acute lung injury (ALI), a major contributor to mortality. Milk fat globule-epidermal growth factor-factor VIII-derived oligopeptide-3 (MOP3) is a novel peptide that attenuates sepsis by opsonizing eCIRP and facilitating its phagocytic clearance. We hypothesized that MOP3 reduces inflammation, mitigates gut and lung injury, and improves survival in gut I/R injury. Methods: Phagocytosis of FITC-labeled eCIRP by intestinal epithelial cells was determined by confocal microscopy, and the cell supernatant was evaluated for cytokine expression by ELISA. Adult C57BL/6 mice underwent 60 min of gut ischemia via superior mesenteric artery occlusion followed by reperfusion. Mice were treated with MOP3 or vehicle via retro-orbital injection at the time of reperfusion. At 4 h post-I/R, blood, gut, and lungs were harvested for further assay. In additional mice, 36-h survival was assessed. Plasma levels of injury and inflammatory markers were measured with colorimetry and ELISA, respectively. Tissue mRNA expression was measured with qPCR. Myeloperoxidase (MPO), TUNEL, histologic injury, and ZO-1 immunohistochemistry assessments were performed. Results: MOP3 significantly increased eCIRP phagocytosis by intestinal epithelial cells ( P < 0.01) and decreased IL-6 release ( P < 0.001). Gut I/R caused elevated plasma eCIRP levels. MOP3 treatment significantly reduced plasma levels of IL-1β ( P < 0.01), IL-6 ( P < 0.05), and lactate dehydrogenase ( P < 0.05) along with a significant decrease in gut ( P < 0.05) and lung ( P < 0.001) injury scores as well as gut cell death ( P < 0.05). Moreover, MOP3 reduced pulmonary levels of chemokines and the granulocyte activation marker MPO after gut I/R. Mechanistically, ZO-1 expression in the gut was decreased following gut I/R injury, whereas MOP3 significantly reversed the decrease in ZO-1 mRNA expression ( P < 0.001). Finally, mice treated with MOP3 exhibited a significant decrease in mortality ( P < 0.05). Conclusions: Treatment with MOP3 effectively mitigates organ injury induced by gut I/R. This beneficial effect is attributed to the facilitation of eCIRP clearance, directing the potential of MOP3 as an innovative therapeutic approach for this critical and often fatal condition.

An anti-eCIRP strategy for necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease characterized by intestinal inflammation and injury, with high mortality risk. Extracellular cold-inducible RNA-binding protein (eCIRP) is a recently discovered damage-associated molecular pattern that propagates inflammation and tissue injury; however, the role of eCIRP in NEC remains unknown. We hypothesize that eCIRP exacerbates NEC pathogenesis and the novel eCIRP-scavenging peptide, milk fat globule-epidermal growth factor-factor VIII (MFG-E8)-derived oligopeptide 3 (MOP3), attenuates NEC severity, serving as a new therapeutic strategy to treat NEC.

METHODS

Stool samples from premature neonates were collected prospectively and eCIRP levels were measured. Wild-type (WT) and CIRP-/- mouse pups were subjected to NEC utilizing a combination of hypoxia and hypercaloric formula orogastric gavage with lipopolysaccharide supplementation. In parallel, WT pups were treated with MOP3 or vehicle. Endpoints including NEC severity, intestinal injury, barrier dysfunction, lung injury, and overall survival were determined.

RESULTS

Stool samples from NEC neonates had elevated eCIRP levels compared to healthy age-matched controls (p < 0.05). CIRP-/- pups were significantly protected from NEC severity, intestinal injury, bowel inflammation, intestinal barrier dysfunction, lung injury, and systemic inflammation. NEC survival was 100% for CIRP-/- pups compared to 65% for WT (p < 0.05). MOP3 treatment recapitulated the benefits afforded by CIRP-knockdown, preventing NEC severity, improving inflammatory profiles, and attenuating organ injury. MOP3 treatment improved NEC survival to 80% compared to 50% for vehicle treatment (p < 0.05).

CONCLUSIONS

eCIRP exacerbates NEC evidenced by protection with CIRP-deficiency and administration of MOP3, a CIRP-directed therapeutic, in a murine model. Thus, eCIRP is a novel target with human relevance, and MOP3 is a promising treatment for lethal NEC.

Chromatin as alarmins in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease primarily affecting premature neonates, marked by poorly understood pro-inflammatory signaling cascades. Recent advancements have shed light on a subset of endogenous molecular patterns, termed chromatin-associated molecular patterns (CAMPs), which belong to the broader category of damage-associated molecular patterns (DAMPs). CAMPs play a crucial role in recognizing pattern recognition receptors and orchestrating inflammatory responses. This review focuses into the realm of CAMPs, highlighting key players such as extracellular cold-inducible RNA-binding protein (eCIRP), high mobility group box 1 (HMGB1), cell-free DNA, neutrophil extracellular traps (NETs), histones, and extracellular RNA. These intrinsic molecules, often perceived as foreign, have the potential to trigger immune signaling pathways, thus contributing to NEC pathogenesis. In this review, we unravel the current understanding of the involvement of CAMPs in both preclinical and clinical NEC scenarios. We also focus on elucidating the downstream signaling pathways activated by these molecular patterns, providing insights into the mechanisms that drive inflammation in NEC. Moreover, we scrutinize the landscape of targeted therapeutic approaches, aiming to mitigate the impact of tissue damage in NEC. This in-depth exploration offers a comprehensive overview of the role of CAMPs in NEC, bridging the gap between preclinical and clinical insights.

DAMPs and radiation injury

The heightened risk of ionizing radiation exposure, stemming from radiation accidents and potential acts of terrorism, has spurred growing interests in devising effective countermeasures against radiation injury. High-dose ionizing radiation exposure triggers acute radiation syndrome (ARS), manifesting as hematopoietic, gastrointestinal, and neurovascular ARS. Hematopoietic ARS typically presents with neutropenia and thrombocytopenia, while gastrointestinal ARS results in intestinal mucosal injury, often culminating in lethal sepsis and gastrointestinal bleeding. This deleterious impact can be attributed to radiation-induced DNA damage and oxidative stress, leading to various forms of cell death, such as apoptosis, necrosis and ferroptosis. Damage-associated molecular patterns (DAMPs) are intrinsic molecules released by cells undergoing injury or in the process of dying, either through passive or active pathways. These molecules then interact with pattern recognition receptors, triggering inflammatory responses. Such a cascade of events ultimately results in further tissue and organ damage, contributing to the elevated mortality rate. Notably, infection and sepsis often develop in ARS cases, further increasing the release of DAMPs. Given that lethal sepsis stands as a major contributor to the mortality in ARS, DAMPs hold the potential to function as mediators, exacerbating radiation-induced organ injury and consequently worsening overall survival. This review describes the intricate mechanisms underlying radiation-induced release of DAMPs. Furthermore, it discusses the detrimental effects of DAMPs on the immune system and explores potential DAMP-targeting therapeutic strategies to alleviate radiation-induced injury.