A novel eCIRP/TREM-1 pathway inhibitor attenuates acute kidney injury

Peptide therapy: new promising therapeutics for acute kidney injury

Acute kidney injury (AKI) is a common fatal condition among hospitalized patients. AKI may be induced by a variety of complicating factors such as sepsis, ischemia-reperfusion injury, nephrotoxic substances, and rhabdomyolysis. At present, symptomatic treatment is mainly used, and there are no US Food and Drug Administration (FDA)-approved drugs for the prevention or treatment of AKI. Peptides have become a promising area of research in AKI treatment because of their high efficiency and low toxicity. In this paper, we systematically review the experimental advancements of peptide therapy for AKI, analyze the mechanism of peptide action in different pathological models, discuss the challenges facing peptide therapy, and provide a scientific basis for further clinical research.

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.

Shortened PGLYRP1 Peptides Regulate Antitumor Activity of Cytotoxic Lymphocytes via TREM-1 Receptor: From Biology to Bioinformatics

The pro-inflammatory immune response plays an important role in protecting the body from pathogens and tumors. In this study, we were able to identify three peptides of the innate immunity protein PGLYRP1 (Tag7) that could regulate the activity of the TREM-1 receptor. TREM-1 receptor activation on monocytes triggers the appearance of antitumor lymphocytes. All three peptides studied (17.0, N9, and N15) bind with the TREM-1 receptor with the Kds 1.32 ± 0.2 nM, 9.66 ± 0.5 nM, and 7.43 ± 0.4 nM, respectively. An N9 peptide inhibiting the activity of the receptor was identified in addition to two peptides (N9 and N15) that jointly trigger the activation of the receptor. The conducted molecular docking study revealed amino acid residues (Ile57, Ile58, Glu106, Ser108, Leu110, Tyr116, Pro118, Pro119, Arg130, and Val 132), necessary for various functions of peptides, providing important knowledge for understanding the mechanism of activation of this receptor that can also serve as a basis for the development of therapeutic drugs to regulate its activity in the treatment of autoimmune diseases and tumors.

Host Response Protein Biomarkers Indicative of Persistent Acute Kidney Injury in Critically Ill COVID-19 Patients

IMPORTANCE

Sepsis-related host-response anomalies contribute to acute kidney injury (AKI) duration. Data on the host-response specific to COVID-19-associated AKI (COVID-AKI) in critically ill patients is limited.

OBJECTIVES

We postulated that persistent COVID-AKI (> 48 hr) differs in host response from transient (< 48 hr) or no COVID-AKI.

DESIGN, SETTING, AND PARTICIPANTS

This prospective biomarker study observed patients with severe acute respiratory syndrome coronavirus 2 infection, without chronic kidney disease, in three ICUs from March 2020 to July 2020. AKI was assessed by hourly urine output and daily plasma creatinine.

MAIN OUTCOMES AND MEASURES

Luminex and enzyme-linked immunosorbent assay were used to analyze 48 plasma protein biomarkers across six pathophysiological domains, which were tested with mixed-effects models.

RESULTS

Of 177 included patients, 106 (59.9%) had AKI within the first 48 hours of admission, of whom 76 (71.7%) had persistent AKI and 30 (28.3%) transient AKI. Those with persistent AKI often had obesity, hypertension, and a higher Sequential Organ Failure Assessment score due to the renal component. Longitudinal analyses revealed that seven proteins were elevated in persistent AKI compared with no AKI. These were related to inflammation (triggering receptor expressed on myeloid cells 1, p < 0.001; tumor necrosis factor receptor 1, p < 0.001; procalcitonin, p = 0.001), complement activation (mannan-binding lectin serine protease-2, p = 0.001), kidney dysfunction (cystatin C, p < 0.001; neutrophil gelatinase-associated lipocalin, p < 0.001), and lung dysfunction (Clara cell secretory protein 16, p < 0.001). AKI (duration) was not associated with differences in the cytokine signaling, endothelial cell activation, or coagulation domains.

CONCLUSIONS AND RELEVANCE

In contrast with sepsis-associated AKI, primarily inflammation-related biomarker levels correlated with COVID-AKI persistence. This study offers insights into COVID-AKI and may guide approaches to mitigate its persistence.

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.

Assessing donor kidney function: the role of CIRBP in predicting delayed graft function post-transplant

Introduction

Delayed graft function (DGF) shortens the survival time of transplanted kidneys and increases the risk of rejection. Current methods are inadequate in predicting DGF. More precise tools are required to assess kidney suitability for transplantation. Cold-inducible RNA-binding protein (CIRBP) expression has been linked to acute kidney injury, suggesting its potential as a new biomarker for transplanted kidney function.

Methods

We included deceased donors and recipients who had undergone successful kidney transplantation between 2016 and 2019. Recipients and their paired donors are assigned to either the DGF or immediate graft function (IGF) group, based on the recipient's recovery of graft renal function. Donor plasma CIRBP levels were measured using an enzyme-linked immunosorbent assay kit to assess their relationships with DGF.

Results

Donor plasma CIRBP concentrations in the DGF group were approximately twice as high as those in the IGF group (6.82 vs. 3.44; P<0.001). DGF occurred in all cases where CIRBP concentrations exceeded 7.92 ng/mL. Furthermore, univariate and multivariate analyses (odds ratio [OR]=1.660; P<0.001) confirmed that donor plasma CIRBP level was an independent risk factor for DGF. Additionally, higher CIRBP levels were associated with increased plasma creatinine at 6 months (R²=0.08; P<0.001), and survival analysis showed shorter kidney survival in recipients with DGF (P=0.002).

Conclusions

This study demonstrated that donor plasma CIRBP levels can effectively predict the occurrence of DGF. CIRBP is a potential novel biomarker for evaluating transplanted kidney function.

Clinical trial registration

https://clinicaltrials.gov, identifier NCT06641622.

Extracellular Cold-Inducible RNA-Binding Protein and Hemorrhagic Shock: Mechanisms and Therapeutics

Hemorrhagic shock is a type of hypovolemic shock and a significant cause of trauma-related death worldwide. The innate immune system has been implicated as a key mediator in developing severe complications after shock. Inflammation from the innate immune system begins at the time of initial insult; however, its activation is exaggerated, resulting in early and late-stage complications. Hypoxia and hypoperfusion lead to the release of molecules that act as danger signals known as damage-associated molecular patterns (DAMPs). DAMPs continue to circulate after shock, resulting in excess inflammation and tissue damage. We recently discovered that cold-inducible RNA-binding protein released into the extracellular space acts as a DAMP. During hemorrhagic shock, hypoperfusion leads to cell necrosis and the release of CIRP into circulation, triggering both systemic inflammation and local tissue damage. In this review, we discuss extracellular cold-inducible RNA-binding protein (eCIRP)'s role in sterile inflammation, as well as its various mechanisms of action. We also share our more newly developed anti-eCIRP agents with the eventual goal of producing drug therapies to mitigate organ damage, reduce mortality, and improve patient outcomes related to hemorrhagic shock. Finally, we suggest that future preclinical studies are required to develop the listed therapeutics for hemorrhagic shock and related conditions. In addition, we emphasize on the challenges to the translational phase and caution that the therapy should allow the immune system to continue to function well against secondary infections during hospitalization.

TREM-1 and TREM-2 as therapeutic targets: clinical challenges and perspectives

TREM-1 and TREM-2 as Therapeutic Targets: Clinical Challenges and Perspectives.

Inhibiting triggering receptor expressed on myeloid cells 1 signaling to ameliorate skin fibrosis

Systemic sclerosis (SSc) is characterized by immune system failure, vascular insult, autoimmunity, and tissue fibrosis. TGF-β is a crucial mediator of persistent myofibroblast activation and aberrant extracellular matrix production in SSc. The factors responsible for this are unknown. By amplifying pattern recognition receptor signaling, triggering receptor expressed on myeloid cells 1 (TREM-1) is implicated in multiple inflammatory conditions. In this study, we used potentially novel ligand-independent TREM-1 inhibitors in preclinical models of fibrosis and explanted SSc skin fibroblasts in order to investigate the pathogenic role of TREM-1 in SSc. Selective pharmacological TREM-1 blockade prevented and reversed skin fibrosis induced by bleomycin in mice and mitigated constitutive collagen synthesis and myofibroblast features in SSc fibroblasts in vitro. Our results implicate aberrantly activated TREM-1 signaling in SSc pathogenesis, identify a unique approach to TREM-1 blockade, and suggest a potential therapeutic benefit for TREM-1 inhibition.

Role of triggering receptor expressed on myeloid cells-1 in kidney diseases: A biomarker and potential therapeutic target

ABSTRACT

Triggering receptor expressed on myeloid cells-1 (TREM-1) is a member of the immunoglobulin superfamily. As an amplifier of the inflammatory response, TREM-1 is mainly involved in the production of inflammatory mediators and the regulation of cell survival. TREM-1 has been studied in infectious diseases and more recently in non-infectious disorders. More and more studies have shown that TREM-1 plays an important pathogenic role in kidney diseases. There is evidence that TREM-1 can not only be used as a biomarker for diagnosis of disease but also as a potential therapeutic target to guide the development of novel therapeutic agents for kidney disease. This review summarized molecular biology of TREM-1 and its signaling pathways as well as immune response in the progress of acute kidney injury, renal fibrosis, diabetic nephropathy, immune nephropathy, and renal cell carcinoma.

Serum CIRP increases the risk of acute kidney injury after cardiac surgery

Introduction

Acute kidney injury (AKI) is a frequent perioperative complication. The underlying mechanisms of cardiac surgery-associated AKI are still not completely elucidated. Cold-induced RNA-binding protein (CIRP) has been subsequently found to be regulated by various stress conditions. During cardiac surgery and cardiopulmonary bypass (CPB), the host is subjected to hypothermia and inadequate organ perfusion, resulting in an upregulation of CIRP secretion. The aim of this study is to evaluate the role of elevated extracellular CIRP level as a contributing factor in the development of AKI.

Methods

A total of 292 patients who underwent cardiac surgery were retrospectively enrolled and their serum samples were collected preoperative and postoperative. Demographic data, intraoperative data, in-hospital outcomes, and the occurrence of AKI were also collected for the patients. The correlation between CIRP and intraoperative procedures, as well as its association with postoperative outcomes were analyzed.

Results

In multivariable analysis, higher ΔCIRP (p = 0.036) and body mass index (p = 0.015) were independent risk factors for postoperative AKI. Meanwhile, patients with postoperative AKI exhibited lower survival rate in 2-year follow-up (p = 0.008). Compared to off-pump coronary artery bypass grafting surgery, patients who underwent on-pump coronary artery bypass grafting, valve surgery, aortic dissection and other surgery showed higher ΔCIRP, measuring 1,093, 666, 914 and 258 pg/mL, respectively (p < 0.001). The levels of ΔCIRP were significantly higher in patients who underwent CPB compared to those who did not (793.0 ± 648.7 vs. 149.5 ± 289.1 pg/mL, p < 0.001). Correlation analysis revealed a positive correlation between ΔCIRP levels and the duration of CPB (r = 0.502, p < 0.001). Patients with higher CIRP levels are at greater risk of postoperative AKI (OR: 1.67, p = 0.032), especially the stage 2-3 AKI (OR: 2.11, p = 0.037).

Conclusion

CIRP secretion increases with prolonged CPB time after cardiac surgery, and CIRP secretion is positively correlated with the duration of CPB. Cardiac surgeries with CPB exhibited significantly higher levels of CIRP compared to non-CPB surgeries. Elevation of CIRP level is an independent risk factor for the incidence of AKI, especially the severe AKI, and were associated with adverse in-hospital outcomes.

NOVEL PS-OME MIRNA130B-3P REDUCES INFLAMMATION AND INJURY AND IMPROVES SURVIVAL AFTER RENAL ISCHEMIA-REPERFUSION INJURY

ABSTRACT

Introduction : Acute kidney injury (AKI) is a prevalent medical disorder characterized by a sudden decline in kidney function, often because of ischemia/reperfusion (I/R) events. It is associated with significant chronic complications, and currently available therapies are limited to supportive measures. Extracellular cold-inducible RNA-binding protein (eCIRP) has been identified as a mediator that potentiates inflammation after I/R injury. However, it has been discovered that miRNA 130b-3p acts as an endogenous inhibitor of eCIRP. To address the inherent instability of miRNA in vivo , a chemically modified miRNA mimic called PS-OME miR130 was developed. We hypothesize that administration of PS-OME miR130 after renal I/R can lead to reduced inflammation and injury in a murine model of AKI. Methods : C57BL/6 male mice underwent renal I/R by clamping of bilateral renal hilum for 30 min or sham operation. Immediately after closure, mice were intravenously administered vehicle (phosphate-buffered saline) or PS-OME miR130 at a dose of 12.5 nmol/mouse. Blood and kidneys were collected after 24 h for further analysis. Separately, mice underwent renal I/R and administered vehicle or treatment and, survival was monitored for 10 days. Results : After renal I/R, mice receiving vehicle showed a significant increase in serum markers of kidney injury and inflammation including blood urea nitrogen, NGAL, KIM-1, and IL-6. After treatment with PS-OME miR130, these markers were significantly decreased. Kidney tissue mRNA expression for injury and inflammation markers including NGAL, KIM-1, KC, and MIP-2 were increased after renal I/R; however, these markers showed a significant reduction with PS-OME miR130 treatment. Histologically, treatment with PS-OME miR130 showed a significant decrease in neutrophil infiltration and injury severity score, and decreased apoptosis. In the 10-day survival study, mice in the treatment group showed a significant reduction in mortality as compared with vehicle group. Conclusion : In a murine renal I/R model, the administration of PS-OME miR130, a direct eCIRP antagonistic miRNA mimic, resulted in the reduction of kidney inflammation and injury, and improved survival. PS-OME miR130 holds promise to be developed as novel therapeutic for AKI as an adjunct to the standard of care.

Soluble triggering receptor expressed on myeloid cell-1 reflects the cross-sectional activity of microscopic polyangiitis and granulomatosis with polyangiitis

Objectives

We investigated whether soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) reflects cross-sectional activity of microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA).

Methods

Forty-seven MPA and 32 GPA patients with well-documented clinical records and stored sera were enrolled. sTREM-1 levels were evaluated using Magnetic Luminex® assay, and disease activity was assessed using Birmingham vasculitis activity score (BVAS). Patients were divided into two groups according to the upper and lower halves of BVAS. Receiver operator characteristic (ROC) curve analysis was used to identify cut-off for determining upper half of BVAS. Linear and binary logistic regression was performed to evaluate the association between sTREM-1 and disease activity and status.

Results

The median age of patients was 67.0 years, and 58.2 % were women. The median BVAS and sTREM-1 were 12.0 and 467.1 pg/mL. sTREM-1 was significantly correlated with BVAS along with five-factor score, Short-Form 36-Item Health Surveys, and C-reactive protein. In multivariable linear regression analysis, erythrocyte sedimentation rate (standardised β 0.241), and sTREM-1 (standardised β 0.288) were correlated with BVAS. ROC analysis revealed that the cut-off of sTREM-1 for the upper half of BVAS was 474.1 pg/mL. MPA and GPA patients with sTREM-1 ≥474.1 pg/mL exhibited a significantly higher risk for the upper half of BVAS than those without (relative risk 5.932). Multivariable logistic regression analysis demonstrated sTREM-1 ≥474.1 pg/mL (odds ratio 5.662) was associated with the upper half of BVAS.

Conclusion

sTREM-1 reflects the activity of MPA and GPA, suggesting its role as a potential biomarker for assessing disease severity.

Exosome-derived CIRP: An amplifier of inflammatory diseases

Cold-inducible RNA-binding protein (CIRP) is an intracellular stress-response protein and a type of damage-associated molecular pattern (DAMP) that responds to various stress stimulus by altering its expression and mRNA stability. Upon exposure to ultraviolet (UV) light or low temperature, CIRP get translocated from the nucleus to the cytoplasm through methylation modification and stored in stress granules (SG). During exosome biogenesis, which involves formation of endosomes from the cell membrane through endocytosis, CIRP also gets packaged within the endosomes along with DNA, and RNA and other proteins. Subsequently, intraluminal vesicles (ILVs) are formed following the inward budding of the endosomal membrane, turning the endosomes into multi-vesicle bodies (MVBs). Finally, the MVBs fuse with the cell membrane to form exosomes. As a result, CIRP can also be secreted out of cells through the lysosomal pathway as Extracellular CIRP (eCIRP). Extracellular CIRP (eCIRP) is implicated in various conditions, including sepsis, ischemia-reperfusion damage, lung injury, and neuroinflammation, through the release of exosomes. In addition, CIRP interacts with TLR4, TREM-1, and IL-6R, and therefore are involved in triggering immune and inflammatory responses. Accordingly, eCIRP has been studied as potential novel targets for disease therapy. C23 and M3, polypeptides that oppose eCIRP binding to its receptors, are beneficial in numerous inflammatory illnesses. Some natural molecules such as Luteolin and Emodin can also antagonize CIRP, which play roles similar to C23 in inflammatory responses and inhibit macrophage-mediated inflammation. This review aims to provide a better understanding on CIRP translocation and secretion from the nucleus to the extracellular space and the mechanisms and inhibitory roles of eCIRP in diverse inflammatory illnesses.

Extracellular CIRP induces acute kidney injury via endothelial TREM-1

Introduction: Acute kidney injury is associated with elevated serum levels of extracellular cold-inducible RNA-binding protein (eCIRP), a damage-associated molecular pattern released during ischemia/reperfusion injury, hemorrhagic shock, and sepsis. It is unknown if circulating eCIRP and eCIRP-induced activation of receptor triggering receptor expressed on myeloid cells-1 (TREM-1), expressed on endothelial cells, play an important role in the pathogenesis of AKI.

Methods: Male B6 wild-type (WT) and TREM-1^−/− mice were subjected to intravenous injection of recombinant murine (rm) CIRP. Serum, urine, and renal tissue were collected 6 h later for analysis. Additionally, primary human renal glomerular endothelial cells (HRGEC) were stimulated in vitro with rmCIRP after pretreatment with M3, a novel inhibitory peptide of TREM-1, or vehicle. Supernatants and cells were collected 20 h after stimulation.

Results: After injection with rmCIRP, WT mice had a significant increase in serum levels of BUN, creatinine, and NGAL compared to control. Additionally, NGAL was significantly increased in the urine of rmCIRP-injected mice, suggesting that circulating eCIRP can directly induce AKI. The levels of TREM-1 mRNA in the kidneys, as well as soluble (s) TREM-1 released into the serum and urine, were significantly increased in rmCIRP-injected mice. TREM-1^−/− mice injected with rmCIRP had attenuated AKI, indicated by significantly decreased serum BUN, creatinine, and NGAL, and renal mRNA expression of NGAL and KIM-1 compared to WT mice. TREM-1^−/− mice also had attenuated endothelial activation, with decreased mRNA and protein expression of ICAM-1 in renal tissue. HRGEC stimulated with rmCIRP in vitro had significant increases in cytokine production and sTREM-1 release, which was attenuated in cells treated with M3.

Conclusion: Activation of renal TREM-1 with circulating eCIRP is sufficient to cause AKI. Elevated levels of eCIRP may be critical for the development of AKI under conditions such as ischemia/reperfusion injury, hemorrhagic shock, and sepsis. Mice deficient in the TREM-1 receptor have attenuated AKI and reduced endothelial cell activation after injection of rmCIRP. TREM-1 inhibition with M3 attenuates HRGEC activation after eCIRP stimulation. Targeting eCIRP activation of TREM-1 may provide a novel and effective treatment for AKI.