Circulating Markers of Necroptosis in Acute Pancreatitis.

OBJECTIVES: Necroptosis, a programmed inflammatory cell death, is involved in the pathogenesis of acute pancreatitis (AP). We compared levels of interleukin (IL)-33 (released upon necroptosis), sST2 (soluble IL-33 receptor), MLKL, RIPK1 and RIPK3 (necroptosis executioner proteins), and proinflammatory cytokines IL-6, TNF and IL-1ß at various severity categories and stages of AP. METHODS: Plasma from 20 patients with early mild AP (MAP) (symptom onset < 72 h), 7 with severe AP (SAP) without and 4 with persistent organ failure (OF) at sampling, 8 patients with late SAP and 20 healthy controls (HC) were studied by ELISAs. RESULTS: Early sST2 and IL-6 levels predicted the development of SAP and were higher in both MAP and early and late SAP than in HC. RIPK3 levels were higher than in HC in the patients who had or would later have SAP. MLKL levels were associated with the presence of OFs, particularly in the late phase, but were also higher in MAP than in HC. CONCLUSIONS: sST2, RIPK3 and IL-6 levels may have prognostic value in AP. Elevated MLKL levels are associated with OF in AP. Better understanding of necroptosis in AP pathophysiology is needed to evaluate whether inhibiting and targeting necroptosis is a potential therapeutic option in AP.

A two-center prospective cohort study of serum RIP-3 as a potential biomarker in relation to severity and prognosis after severe traumatic brain injury.

Receptor-interacting protein kinase-3 (RIP-3) is a key component for inducing necroptosis following acute brain injury. Purpose of this study is to unveil whether serum RIP-3 levels are related to severity and clinical outcomes after human severe traumatic brain injury (sTBI). In this two-center prospective cohort study, serum RIP-3 levels were detected in 127 healthy controls coupled with 127 sTBI patients. The prognostic indicators encompassed posttraumatic 180-day mortality, overall survival and poor prognosis (defined as extended Glasgow outcome scale scores of 1-4). The prognosis associations were verified via multivariate analysis. There was a significant incremental serum RIP-3 levels in patients with sTBI, relative to the controls. RIP-3 levels of patients were independently correlated with Rotterdam Computed Tomography (CT) scores and Glasgow coma scale (GCS) scores, as well as were independently predictive of mortality, overall survival and poor prognosis. Mortality and poor prognosis were effectively predicted by serum RIP-3 levels under the receiver operating characteristic curve. Linear relationships between RIP-3 levels and their risks were verified. Mortality and poor prognosis models of serum RIP-3 levels combined with GCS and Rotterdam CT scores displayed efficient predictive abilities. The two models were graphically represented, which were of clinical stability and value by employing the calibration and decision curves. Increased serum RIP-3 levels after sTBI are closely linked to heightened trauma severity and poor prognosis, signifying that serum RIP-3 may be an encouraging biomarker for evaluating severity and predicting clinical outcome of sTBI.

Receptor-interacting protein kinase-3 (RIPK3): a new biomarker for necrotising enterocolitis in preterm infants.

OBJECTIVE: This study aimed to evaluate the role of receptor-interacting protein kinase-3 (RIPK3) in the diagnosis, estimation of disease severity, and prognosis of premature infants with necrotising enterocolitis (NEC). METHODS: RIPK3, lactic acid (LA), and C-reactive protein (CRP) levels were measured in the peripheral blood of 108 premature infants between 2019 and 2023, including 24 with stage II NEC, 18 with stage III NEC and 66 controls. Diagnostic values of the indicators for NEC were evaluated via receiver operating characteristic (ROC) curve analysis. RESULTS: Plasma RIPK3 and LA levels upon NEC suspicion in neonates with stage III NEC were 32.37 ± 16.20 ng/mL. The ROC curve for the combination of RIPK3, LA, CRP for NEC diagnosis were 0.925. The time to full enteral feeding (FEFt) after recovery from NEC was different between two expression groups of plasma RIPK3 (RIPK3 < 20.06 ng/mL and RIPK3 ≥ 20.06 ng/mL). CONCLUSION: Plasma RIPK3 can be used as a promising marker for the diagnosis and estimation of disease severity of premature infants with NEC and for the guidance on proper feeding strategies after recovery from NEC.

Inhibition of receptor-interacting protein kinase 1 improves experimental non-alcoholic fatty liver disease.

BACKGROUND & AIMS: In non-alcoholic fatty liver disease (NAFLD), hepatocytes can undergo necroptosis: a regulated form of necrotic cell death mediated by the receptor-interacting protein kinase (RIPK) 1. Herein, we assessed the potential for RIPK1 and its downstream effector mixed lineage kinase domain-like protein (MLKL) to act as therapeutic targets and markers of activity in NAFLD. METHODS: C57/BL6J-mice were fed a normal chow diet or a high-fat diet (HFD). The effect of RIPA-56, a highly specific inhibitor of RIPK1, was evaluated in HFD-fed mice and in primary human steatotic hepatocytes. RIPK1 and MLKL concentrations were measured in the serum of patients with NAFLD. RESULTS: When used as either a prophylactic or curative treatment for HFD-fed mice, RIPA-56 caused a downregulation of MLKL and a reduction of liver injury, inflammation and fibrosis, characteristic of non-alcoholic steatohepatitis (NASH), as well as of steatosis. This latter effect was reproduced by treating primary human steatotic hepatocytes with RIPA-56 or necrosulfonamide, a specific inhibitor of human MLKL, and by knockout (KO) of Mlkl in fat-loaded AML-12 mouse hepatocytes. Mlkl-KO led to activation of mitochondrial respiration and an increase in ß-oxidation in steatotic hepatocytes. Along with decreased MLKL activation, Ripk3-KO mice exhibited increased activities of the liver mitochondrial respiratory chain complexes in experimental NASH. In patients with NAFLD, serum concentrations of RIPK1 and MLKL increased in correlation with activity. CONCLUSION: The inhibition of RIPK1 improves NASH features in HFD-fed mice and reverses steatosis via an MLKL-dependent mechanism that, at least partly, involves an increase in mitochondrial respiration. RIPK1 and MLKL are potential serum markers of activity and promising therapeutic targets in NAFLD. LAY SUMMARY: There are currently no pharmacological treatment options for non-alcoholic fatty liver disease (NAFLD), which is now the most frequent liver disease. Necroptosis is a regulated process of cell death that can occur in hepatocytes during NAFLD. Herein, we show that RIPK1, a gatekeeper of the necroptosis pathway that is activated in NAFLD, can be inhibited by RIPA-56 to reduce not only liver injury, inflammation and fibrosis, but also steatosis in experimental models. These results highlight the potential of RIPK1 as a therapeutic target in NAFLD.

Plasma receptor interacting protein kinase-3 levels are associated with acute respiratory distress syndrome in sepsis and trauma: a cohort study.

BACKGROUND: Necroptosis, a form of programmed cell death mediated by receptor interacting serine/threonine-protein kinase-3 (RIPK3), is implicated in murine models of acute respiratory distress syndrome (ARDS). We hypothesized that plasma RIPK3 concentrations in sepsis and trauma would be associated with ARDS development and that plasma RIPK3 would reflect changes in lung tissue RIPK3 in a murine model of systemic inflammation. METHODS: We utilized prospective cohort studies of critically ill sepsis (n = 120) and trauma (n = 180) patients and measured plasma RIPK3 at presentation and 48 h. Patients were followed for 6 days for ARDS by the Berlin definition. We used multivariable logistic regression to determine the association of plasma RIPK3 with ARDS in each cohort, adjusting for confounders. In mice, we determined whether plasma and lung tissue RIPK3 levels rise concomitantly 4 h after injection with lipopolysaccharide and ZVAD-FMK, an apoptosis inhibitor. RESULTS: The change in plasma RIPK3 from presentation to 48 h (ΔRIPK3) was associated with ARDS in sepsis (OR 1.30, 95% CI 1.03-1.63, per ½ standard deviation) and trauma (OR 1.79, 95% CI 1.33-2.40). This association was not evident for presentation RIPK3 levels. Secondary analyses showed similar findings for the association of ΔRIPK3 with acute kidney injury and 30-day mortality. Mice injected with lipopolysaccharide and ZVAD-FMK had significantly higher plasma (p < 0.001) and lung (p = 0.005) RIPK3 than control mice. CONCLUSIONS: The change in plasma RIPK3 from presentation to 48 h in both sepsis and trauma patients is independently associated with ARDS, and plasma RIPK3 may reflect RIPK3 activity in lung tissue.

Receptor-Interacting Protein Kinase 3 (RIPK3) mRNA Levels Are Elevated in Blood Mononuclear Cells of Patients with Poor Prognosis of Acute-on-Chronic Hepatitis B Liver Failure.

Necroptosis refers to a programmed form of necrosis, which involves the receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL). In this study, to investigate the role of necroptosis in the pathogenesis of acute-on-chronic hepatitis B liver failure (ACHBLF), we retrospectively analyzed 122 patients with ACHBLF, 131 patients with chronic hepatitis B (CHB), and 35 healthy controls (HCs). Using quantitative real-time polymerase chain reaction (RT-qPCR), we measured RIPK3 mRNA levels in peripheral blood mononuclear cells (PBMCs). ELISA was performed to measure the serum levels of MLKL, TNF-α and caspase-8. We found that RIPK3 mRNA levels were significantly higher in patients with ACHBLF than those with CHB or HCs. RIPK3 mRNA levels in patients with ACHBLF were positively correlated with serum levels of TNF-α or MLKL and negatively correlated with caspase-8 levels. Univariate and multivariate analysis revealed that RIPK3 mRNA level was predictive of 3-month mortality of ACHBLF. The area under receiver operating characteristic curve (AUC) of RIPK3 mRNA levels was 0.810 (95% CI: 0.729-0.876), which was higher than that of MELD scores (0.766, 95% CI: 0.681-0.838). The optimal cut-off point of 8.81 was determined for RIPK3 mRNA levels, which showed a sensitivity of 80.7% and a negative predictive value of 80.4%. These results indicate that elevated RIPK3 mRNA levels in PBMCs are associated with poor prognosis of ACHBLF. We thus propose that necroptosis may play an important role in pathogenesis of ACHBLF.

Low Necroptosis Process Predicts Poor Treatment Outcome of Human Papillomavirus Positive Cervical Cancers by Decreasing Tumor-Associated Macrophages M1 Polarization.

BACKGROUND/AIM: The aim of this study was to assess the functions of the necroptosis process on the prognosis of high-risk human papillomavirus (HR-HPV)-related cervical cancer. METHODS: PCR and western blotting were used to demonstrate the expression of the necroptosis marker, mixed lineage kinase domain-like protein (MLKL), in whole blood and peripheral blood mononuclears (PBMCs) of 89 cervical cancer patients and 15 healthy volunteers. Necroptosis levels and M1 polarization were determined in tumor co-cultured macrophages. RESULTS: We found that MLKL expressions were significantly increased in cervical cancer patients in both whole blood and PBMC samples compared to the expressions in the healthy controls. Low MLKL expression was significantly associated with decreased survival rate in overall survival and disease-free survival. Co-culture cervical cancer cells decrease the necroptosis process of macrophage, together with the proinflammatory factors (M1 markers) downregulation, and this negative regulation was exacerbated in HPV-positive cases. Necroptosis enhancer RIPK3 overexpression showed reversed regulation of these M1 markers, suggesting that co-culture cervical cancer cells decrease the macrophage M1 polarization partly through necroptosis downregulation. CONCLUSION: Our study revealed that necroptosis process could be a relevant marker for the determination of the prognosis in cervical cancer patients, which might be because of its role in regulating macrophage polarization.

A prospective cohort study regarding usability of serum RIPK3 as a biomarker in relation to early hematoma growth and neurological outcomes after acute intracerebral hemorrhage.

OBJECTIVE: The receptor-interacting protein kinase 3 (RIPK3) is a pivotal component for triggering necroptosis. We intended to investigate predictive effects of serum RIPK3 levels on early hematoma growth (EHG) and poor neurological outcome after acute intracerebral hemorrhage (ICH). METHODS: In this prospective cohort study, 183 ICH patients and 100 controls were enrolled for measuring serum RIPK3 levels. National Institutes of Health Stroke Scale (NIHSS) and hematoma volume were recorded as the severity indicators. EHG and poststroke 6-month unfavorable outcome (modified Rankin Scale scores of 3-6) were registered as the two prognostic parameters. Multivariate analyses were implemented to discern relevance of serum RIPK3 to ICH severity and prognosis. RESULTS: Serum RIPK3 levels of patients, which were dramatically higher than those of controls, were independently related to NIHSS scores, hematoma volume, EHG, 6-month mRS scores and unfavorable outcome. Risks of EHG and unfavorable outcome were linearly pertinent to and efficiently discriminated by RIPK3 levels under restricted cubic spline and receiver operating characteristic curve respectively. RIPK3 levels nonsignificantly interacted with age, gender, hypertension, etc. Predictive ability of RIPK3 levels resembled those of NIHSS scores and hematoma volume. The prediction models, in which serum RIPK3, NIHSS scores and hematoma volume were integrated, were visually displayed via nomograms. The models' predictive capabilities substantially surpassed that of serum RIPK3, NIHSS scores and hematoma volumes alone. The models kept stable under calibration curve. CONCLUSION: A profound increase of serum RIPK3 levels after ICH is tightly relevant to severity, EHG and poor neurological outcomes, assuming that serum RIPK3 may emerge as a valuable prognostic predictor of ICH.

Analysis of the serum levels of RIP3 and Drp1 in patients with heart failure.

AIMS: As necroptosis involving receptor-interacting protein kinase 3 (RIP3) and dynamin-related protein 1 (Drp1)-mediated signalling is a crucial mechanism of cell loss in heart failure (HF), we aimed to determine the potential diagnostic use of these molecules. METHODS AND RESULTS: The serum samples of the healthy subjects (n = 8) and patients with HF with reduced ejection fraction (n = 31), being subdivided according to the aetiology and New York Heart Association (NYHA) class, were used to measure RIP3 and Drp1 levels by enzyme-linked immunosorbent assay. Although the serum levels of Drp1 in the patients with HF were comparable with those seen in healthy individuals, we found a trend of increase in the levels of RIP3 (P = 0.0697) in the diseased group. These changes were unlikely dependent on the HF aetiology or NYHA class. The circulating RIP3 correlated with neither the main parameters assessing cardiac function (left ventricular ejection fraction, left ventricular end-diastolic diameter, and N-terminal pro-brain natriuretic peptide) nor the marker of inflammation (C-reactive protein). CONCLUSIONS: In this pilot study, findings on serum RIP3 supported the importance of necroptosis in HF pathomechanisms. The potential diagnostic use of circulating RIP3, unlike Drp1, as an additional biomarker of HF has also been indicated; however, further large studies are needed to prove this concept.

Serum HMGB-1 released by ferroptosis and necroptosis as a novel potential biomarker for systemic lupus erythematosus.

High mobility group box proterin-1 (HMGB-1) is a multifunctional protein that can be released by various programmed cell deaths (PCDs), such as necroptosis and ferroptosis. PCDs play a critical role in the pathogenesis of systemic lupus erythematosus (SLE). However, the role of HMGB-1 in the process of SLE remains unclear. This study aims to demonstrate the potential diagnosing role of serum HMGB-1 in SLE that released by necroptosis and ferroptosis. We found that the serum levels of HMGB-1, receptor-interacting protein kinase 3 (RIPK3) /mixed lineage kinase domain-like protein (MLKL) related with necroptosis, and metabolites associated with ferroptosis were significantly upregulated in SLE patients compared to HC individuals. These serum levels were positively correlated with SLE disease activity. Additionally, the serum level of HMGB-1 showed a strong positive correlated with the levels of RIPK3/MLKL and ferroptosis metabolites. Moreover, the serum level of HMGB-1 was correlated with renal involvement and high-antinuclear antibodies (ANA) titer. After SLE serum and interferon γ (IFN-γ) treatment in vitro, the level of necroptosis and ferroptosis markers were activated and HMGB1 was released both in HEK293 and HK2 cells. Clinically, HMGB-1 was considered as a significant independent risk factor in SLE serum by binary logistic assay. Notably, HMGB-1 exhibited outstanding diagnostic ability for SLE by the area under the curve (AUC) in receiver operating characteristic (ROC) curve analysis. Taken together, our study indicates that the serum level of HMGB-1 is a promising biomarker for the diagnosis and monitoring of SLE.

Association of Plasma Levels of Fas Ligand with Severity and Outcome of Sepsis.

INTRODUCTION: Levels of the apoptosis regulator Fas ligand (FasL) are associated with severity of sepsis, but its association with the mortality of sepsis and necroptosis, a regulated cell death mechanism, is not yet clear. We aimed to assess the association of FasL level with outcomes of sepsis and receptor interacting protein kinase-3 (RIPK3), an essential necroptosis mediator, for determining the relationship between FasL and necroptosis. METHODS: Plasma FasL and RIPK3 levels were measured by ELISA from prospectively enrolled critically ill adult patients. The best cut-off level of FasL for 28-day mortality prediction was determined by Youden's index. The association between plasma levels of FasL and RIPK3 was assessed by a linear regression method. RESULTS: Among 188 patients, 58 (30.9%) were diagnosed with sepsis and 84 (44.7%) with septic shock, respectively. Plasma levels of FasL increased in the group order of control, sepsis, and septic shock groups (P for trend < 0.001). For 142 patients with sepsis, organ dysfunction and septic shock were more prevalent in the group with plasma FasL levels that were higher than the best cut-off level. A significant difference in mortality between high and low FasL patients was observed up to 90 days (Log-rank P = 0.013). FasL levels did not significantly change over day 3 and day 7. FasL levels were not correlated with those of RIPK3. CONCLUSIONS: The plasma level of FasL was associated with severity of sepsis and was predictive of mortality. However, it was not correlated with RIPK3 level.

mtDNA-STING pathway promotes necroptosis-dependent enterocyte injury in intestinal ischemia reperfusion.

Intestinal ischemia reperfusion (I/R) injury is the important pathogenesis for acute intestinal barrier disruption. The STING signaling is associated with gut homeostasis and barrier integrity. However, the biological function and regulation of STING signaling in intestinal I/R injury are not yet fully understood. As the ligand of STING signaling, the mitochondrial DNA (mtDNA) has been found to be associated with necroptosis. It still remains unknown whether mtDNA-STING signaling triggers intestinal necroptosis in intestinal I/R injury. We found that circulating RIPK3 was significantly increased and had a positive correlation with markers of enterocyte injury in critically ill patients with intestinal injury. Moreover, the levels of circulating mtDNA were also associated with the levels of circulating RIPK3. To explore the relationship between mtDNA and intestinal necroptosis, mice were treated with the intraperitoneal injection of mtDNA, and necroptosis signaling was remarkably activated and the inhibition of necroptosis alleviated mtDNA-induced intestinal injury. Furthermore, STING knockout mice showed an alleviated intestinal necroptosis. In intestinal I/R injury, mtDNA was released from IECs and necroptosis was also triggered, companied with a significant decrease of RIPK3 in the intestine. STING knockout mice markedly attenuated intestinal necroptosis and intestinal I/R injury. Finally, we found that mtDNA-mediated STING signaling triggered necroptosis through synergistic IFN and TNF-α signaling in primary IECs. Our results indicated that mtDNA-STING signaling can contribute to intestinal I/R injury by promoting IEC necroptosis. STING-mediated both IFN and TNF-α signaling can trigger intestinal nercroptosis.

Plasma levels of receptor interacting protein kinase-3 correlated with coronary artery disease.

BACKGROUND: Necroptosis plays an important role in human atherosclerosis and atheroma development. Since receptor interacting protein kinase-3 (RIP3) acts as a key mediator of necroptosis, this study aimed to explore its relationship between plasma RIP3 levels and coronary artery disease (CAD) and discover a potential new biomarker for screening CAD subtypes and severity. METHODS: A total of 318 patients with CAD who had coronary angiography and 166 controls in Peking Union Medical College Hospital from September 2017 to January 2018 were enrolled in this study. Patients with CAD were divided into three subgroups: patients with stable coronary artery disease (SCAD), patients with unstable angina (UA), and patients with myocardial infarction (MI). The severity of atherosclerosis was determined by Gensini score (GSS). Logistic regression was used to determine the relationship between plasma RIP3 levels and CAD. The correlation between plasma RIP3 and GSS was calculated using multiple linear regression models. RESULTS: Overall, plasma RIP3 levels were significantly higher than serum RIP3 levels. Plasma RIP3 levels in patients with CAD were significantly higher than those in controls. Plasma RIP3 levels were strongly associated with CAD (odds ratio: 6.00, 95% confidence interval 3.04-11.81; P < 0.001). Plasma RIP3 levels increased linearly from controls to patients with SCAD, then patients with UA, and finally to patients with MI. We found a significantly positive correlation between proportion of cases of acute coronary syndrome in subjects and their plasma RIP3 level quartile. Plasma RIP3 levels were also associated with GSS (B 0.027; standard error 0.012; P < 0.05). CONCLUSIONS: Plasma RIP3 levels were independently associated with CAD. Plasma RIP3 levels could potentially supplement clinical assessment to screen CAD and determine CAD severity.

Circulating RIPK3 levels are associated with mortality and organ failure during critical illness.

BACKGROUND: Necroptosis is a form of programmed necrotic cell death that is rapidly emerging as an important pathophysiological pathway in numerous disease states. Necroptosis is dependent on receptor-interacting protein kinase 3 (RIPK3), a protein shown to play an important role in experimental models of critical illness. However, there is limited clinical evidence regarding the role of extracellular RIPK3 in human critical illness. METHODS: Plasma RIPK3 levels were measured in 953 patients prospectively enrolled in 5 ongoing intensive care unit (ICU) cohorts in both the USA and Korea. RIPK3 concentrations among groups were compared using prospectively collected phenotypic and outcomes data. RESULTS: In all 5 cohorts, extracellular RIPK3 levels in the plasma were higher in patients who died in the hospital compared with those who survived to discharge. In a combined analysis, increasing RIPK3 levels were associated with elevated odds of in-hospital mortality (odds ratio [OR] 1.7 for each log10-unit increase in RIPK3 level, P < 0.0001). When adjusted for baseline severity of illness, the OR for in-hospital mortality remained statistically significant (OR 1.33, P = 0.007). Higher RIPK3 levels were also associated with more severe organ failure. CONCLUSIONS: Our findings suggest that elevated levels of RIPK3 in the plasma of patients admitted to the ICU are associated with in-hospital mortality and organ failure. FUNDING: Supported by NIH grants P01 HL108801, R01 HL079904, R01 HL055330, R01 HL060234, K99 HL125899, and KL2TR000458-10. Supported by Samsung Medical Center grant SMX1161431.

RIPK3 mediates pathogenesis of experimental ventilator-induced lung injury.

In patients requiring ventilator support, mechanical ventilation (MV) may induce acute lung injury (ventilator-induced lung injury [VILI]). VILI is associated with substantial morbidity and mortality in mechanically ventilated patients with and without acute respiratory distress syndrome. At the cellular level, VILI induces necrotic cell death. However, the contribution of necroptosis, a programmed form of necrotic cell death regulated by receptor-interacting protein-3 kinase (RIPK3) and mixed-lineage kinase domain-like pseudokinase (MLKL), to the development of VILI remains unexplored. Here, we show that plasma levels of RIPK3, but not MLKL, were higher in patients with MV (i.e., those prone to VILI) than in patients without MV (i.e., those less likely to have VILI) in two large intensive care unit cohorts. In mice, RIPK3 deficiency, but not MLKL deficiency, ameliorated VILI. In both humans and mice, VILI was associated with impaired fatty acid oxidation (FAO), but in mice this association was not observed under conditions of RIPK3 deficiency. These findings suggest that FAO-dependent RIPK3 mediates pathogenesis of acute lung injury.

RIPK3 promotes sepsis-induced acute kidney injury via mitochondrial dysfunction.

Sepsis causes acute kidney injury (AKI) in critically ill patients, although the pathophysiology remains unclear. The receptor-interacting protein kinase-3 (RIPK3), a cardinal regulator of necroptosis, has recently been implicated in the pathogenesis of human disease. In mice subjected to polymicrobial sepsis, we demonstrate that RIPK3 promotes sepsis-induced AKI. Utilizing genetic deletion and biochemical approaches in vitro and in vivo, we identify a potentially novel pathway by which RIPK3 aggravates kidney tubular injury independently of the classical mixed lineage kinase domain-like protein-dependent (MLKL-dependent) necroptosis pathway. In kidney tubular epithelial cells, we show that RIPK3 promotes oxidative stress and mitochondrial dysfunction involving upregulation of NADPH oxidase-4 (NOX4) and inhibition of mitochondrial complex I and -III, and that RIPK3 and NOX4 are critical for kidney tubular injury in vivo. Furthermore, we demonstrate that RIPK3 is required for increased mitochondrial translocation of NOX4 in response to proinflammatory stimuli, by a mechanism involving protein-protein interactions. Finally, we observed elevated urinary and plasma RIPK3 levels in human patients with sepsis-induced AKI, representing potential markers of this condition. In conclusion, we identify a pathway by which RIPK3 promotes kidney tubular injury via mitochondrial dysfunction, independently of MLKL, which may represent a promising therapeutic target in sepsis-induced AKI.

Expression and genetic polymorphism of necroptosis related protein RIPK1 is correlated with severe hepatic ischemia-reperfusion injury and prognosis after hepatectomy in hepatocellular carcinoma patients.

OBJECTIVES: The goal of our study was to assess the prognostic impact of the necroptosis relative protein RIPK1 genetic polymorphism in ischemia-reperfusion injury and survival after hepatectomy in hepatocellular carcinoma (HCC) patients. METHODS: In this study, expression of RIPK1 and its genetic polymorphism(rs2272990) were examined in plasma of 44 HCC patients. All these patients were undergoing partial hepatectomy. The prognostic values of RIPK1 genetic polymorphism for tumor development and survival, and ischemia-reperfusion injury after hepatectomy were further determined. RESULTS: Plasma RIPK1 expressions were significantly increased in HCC patients, compared to the healthy control group. Totally 19 patients have the GA + AA genotype in the RIPK1 rs2272990 SNP site and 25 have GG genotype. There were no statistically significant intergroup differences observed in age, gender, AFP value, HBV positive, tumor size or cirrhosis. GG genotype had positive correlation with TNM classification (p= 0.033) and lymphatic metastasis (p= 0.027) and was significantly associated with severe hepatic ischemia-reperfusion injury and decreased survival rate after hepatectomy. CONCLUSION: In conclusion, the RIPK1 polymorphism is an indicator of hepatic injury and a novel prognostic biomarker for tumor development and survival of HCC recipients after hepatectomy.

Serum levels of RIPK3 and troponin I as potential biomarkers for predicting impaired left ventricular function in patients with myocardial infarction with ST segment elevation and normal troponin I levels prior percutaneous coronary intervention.

The current study examined the serum levels of receptor-interacting protein kinase 3 (RIPK3) in 51 patients with New York Heart Association (NYHA) class III-IV heart failure, 53 patients with myocardial infarction with ST elevation (STEMI), and 19 healthy subjects serving as a control group. An enzyme-linked immunoadsorbent assay (ELISA) was used to measure the levels of RIPK3 expression in serum. The area under the receiver operating characteristic curve (AUC) was then used to evaluate the predictive performance of RIPK3 and troponin I in patients with STEMI. In patients with normal levels of troponin I prior to percutaneous coronary intervention (PCI), serum levels of RIPK3 and troponin I after PCI were sufficient to differentiate patients with a preserved left ventricular ejection fraction (LVEF) from those with impaired left ventricular function after PCI (AUC = 0.780 (95% CI: 0.565-0.995, p = 0.043) with a sensitivity of 76.9% and a specificity of 71.4% vs. AUC = 0.735 (95% CI: 0.530-0.941, p = 0.038) with a sensitivity of 88.2% and a specificity of 63.6% at the optimal cutoff values, respectively). Moreover, elevated levels of troponin I after PCI were associated with an increased risk of an LVEF < 50% prior to discharge (odds ratio, 1.014; 95 % CI, 1.001 to 1.027; p = 0.03), while elevated levels of RIPK3 were not associated with such a risk. The current findings suggest that in patients with normal levels of troponin I prior to PCI, serum levels of RIPK3 and troponin I can serve as a potential marker to identify patients with a decreased LVEF, thus possibly allowing an early shift to more intensive therapy.

Plasma Levels of Receptor Interacting Protein Kinase-3 (RIP3), an Essential Mediator of Necroptosis, are Associated with Acute Kidney Injury in Critically Ill Trauma Patients.

BACKGROUND: Receptor interacting protein kinase-3 (RIP3) is a key mediator of necroptosis, a form of regulated cell death recently implicated in murine models of renal ischemia-reperfusion injury and transfusion-associated endothelial injury. The importance of necroptosis in human AKI is unknown. We hypothesized that plasma RIP3 concentrations would be associated with acute kidney injury (AKI) after severe trauma. METHODS: We performed a case-control study nested in a prospective cohort of critically ill trauma patients. AKI was defined by AKI Network creatinine criteria within 6 days of presentation. Of 158 cohort subjects, we selected 13 who developed AKI stage 2 or 3, 27 with AKI stage 1, and 40 without AKI. We compared plasma RIP3 concentrations across these groups at presentation and 48 h. Since red blood cell (RBC) transfusion is an AKI risk factor, we also tested the association of RBCs transfused during resuscitation with RIP3 levels. RESULTS: Median plasma RIP3 concentration rose more than 10-fold from presentation (15.6 (interquartile range 15.6-41.3) pg/mL) to 48 h (164.7 (66.9-300.6) pg/mL; P <0.001). RIP3 concentrations at 48 h were associated with AKI stage (no AKI: 144.8 (58.6-234.9) pg/mL; AKI stage 1: 165.8 (43.0-310.9) pg/mL; AKI stage 2-3: 365.5 (155.1-727.5) pg/mL; P = 0.010) whereas this association was not seen at presentation (P = 0.324). RBC transfusions were also associated with 48-h plasma RIP3 (no RBCs: 99.4 (15.6-166.1) pg/mL; 1-5 units: 182.6 (98.5-274.1) pg/mL; >5 units: 341.8 (150.1-423.8) pg/mL; P <0.001). CONCLUSIONS: In critically ill trauma patients, plasma levels of the necroptosis mediator RIP3 at 48 h were associated with AKI stage and RBC transfusions.