Study of Early Elevated Gas6 Plasma Level as a Predictor of Mortality in a Prospective Cohort of Patients with Sepsis

Vitamin K: a potential missing link in critical illness-a scoping review

BACKGROUND

Vitamin K is essential for numerous physiological processes, including coagulation, bone metabolism, tissue calcification, and antioxidant activity. Deficiency, prevalent in critically ill ICU patients, impacts coagulation and increases the risk of bleeding and other complications. This review aims to elucidate the metabolism of vitamin K in the context of critical illness and identify a potential therapeutic approach.

METHODS

In December 2023, a scoping review was conducted using the PRISMA Extension for Scoping Reviews. Literature was searched in PubMed, Embase, and Cochrane databases without restrictions. Inclusion criteria were studies on adult ICU patients discussing vitamin K deficiency and/or supplementation.

RESULTS

A total of 1712 articles were screened, and 13 met the inclusion criteria. Vitamin K deficiency in ICU patients is linked to malnutrition, impaired absorption, antibiotic use, increased turnover, and genetic factors. Observational studies show higher PIVKA-II levels in ICU patients, indicating reduced vitamin K status. Risk factors include inadequate intake, disrupted absorption, and increased physiological demands. Supplementation studies suggest vitamin K can improve status but not normalize it completely. Vitamin K deficiency may correlate with prolonged ICU stays, mechanical ventilation, and increased mortality. Factors such as genetic polymorphisms and disrupted microbiomes also contribute to deficiency, underscoring the need for individualized nutritional strategies and further research on optimal supplementation dosages and administration routes.

CONCLUSIONS

Addressing vitamin K deficiency in ICU patients is crucial for mitigating risks associated with critical illness, yet optimal management strategies require further investigation.

IMPACT RESEARCH

To the best of our knowledge, this review is the first to address the prevalence and progression of vitamin K deficiency in critically ill patients. It guides clinicians in diagnosing and managing vitamin K deficiency in intensive care and suggests practical strategies for supplementing vitamin K in critically ill patients. This review provides a comprehensive overview of the existing literature, and serves as a valuable resource for clinicians, researchers, and policymakers in critical care medicine.

New Avenues to Explore in SARS-CoV-2 Infection: Both TRIM25 and TRIM56 Positively Correlate with VEGF, GAS6, and sAXL in COVID-19 Patients

The ongoing COVID-19 pandemic poses a significant threat to human health. Many hypotheses regarding pathogenesis have been proposed and are being tried to be clarified by experimental and clinical studies. This study aimed to reveal the roles of the innate immune system modulator GAS6/sAXL pathway, endothelial dysfunction markers vascular endothelial growth factor (VEGF) and hypoxia-inducible factor (HIF)-1α, and antiviral effective TRIM25 and TRIM56 proteins in pathogenesis of COVID-19. The study included 55 patients with COVID-19 and 25 healthy individuals. The serum levels of GAS6, sAXL, VEGF, HIF-1α, TRIM25, and TRIM56 were measured using commercial ELISA kits and differences between COVID-19 patients and healthy controls, and the relationship to severity and prognosis were evaluated. GAS6, sAXL, TRIM56, and VEGF were found to be higher, while TRIM25 was lower in patients. There were strong positive correlations between GAS6, sAXL, TRIM25, TRIM56, and VEGF. None of the research parameters other than HIF-1α was associated with severity or prognosis. However, HIF-1α was positively correlated with APACHE II. We speculate that the antiviral effective TRIM25 and TRIM56 proteins, as well as the GAS6/sAXL pathway, act together as a defense mechanism in COVID-19. We hope that our study will contribute to further studies to elucidate the molecular mechanism associated with TRIM56, TRIM25, GAS6, sAXL, and VEGF in COVID-19 patients.

Unlocking the Untapped Potential of Endothelial Kinase and Phosphatase Involvement in Sepsis for Drug Treatment Design

Sepsis is a devastating clinical condition that can lead to multiple organ failure and death. Despite advancements in our understanding of molecular mechanisms underlying sepsis and sepsis-associated multiple organ failure, no effective therapeutic treatment to directly counteract it has yet been established. The endothelium is considered to play an important role in sepsis. This review highlights a number of signal transduction pathways involved in endothelial inflammatory activation and dysregulated endothelial barrier function in response to sepsis conditions. Within these pathways – NF-κB, Rac1/RhoA GTPases, AP-1, APC/S1P, Angpt/Tie2, and VEGF/VEGFR2 – we focus on the role of kinases and phosphatases as potential druggable targets for therapeutic intervention. Animal studies and clinical trials that have been conducted for this purpose are discussed, highlighting reasons why they might not have resulted in the expected outcomes, and which lessons can be learned from this. Lastly, opportunities and challenges that sepsis and sepsis-associated multiple organ failure research are currently facing are presented, including recommendations on improved experimental design to increase the translational power of preclinical research to the clinic.

The suppressive effects of Mer inhibition on inflammatory responses in the pathogenesis of LPS-induced ALI/ARDS

The pathogenesis of sepsis-induced acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) has not yet been fully elucidated. Growth arrest-specific 6 (Gas6) has marked effects on hemostasis and reduces inflammation through its interaction with receptor tyrosine kinases of the TAM family: Tyro3, Axl, and Mer. Here, we found that plasma concentrations of Gas6 and soluble Mer were greater in patients with severe sepsis or septic ALI/ARDS compared with those in normal healthy donors. To determine whether the Gas6-Mer axis was critical in the pathogenesis of ALI/ARDS, we investigated the effects of intravenous administration of the selective Mer inhibitor UNC2250 on lipopolysaccharide (LPS)-induced ALI in mouse models subjected to inhalation of LPS. UNC2250 markedly inhibited the infiltration into the lungs of neutrophils and monocytes with increased amounts of Gas6 and Mer proteins, severe lung damage, and increased amounts of reactive oxygen species (ROS) in LPS-induced ALI in mice. In human pulmonary aortic endothelial cells, LPS induced decreases in the amounts of endothelial nitric oxide synthase, thrombomodulin, and vascular endothelial-cadherin, which was blocked by treatment with UNC2250. UNC2250 also inhibited the LPS-dependent increases in cell proliferation and enhanced apoptosis in HL-60 cells, a human neutrophil-like cell line, and RAW264.7 cells, a mouse monocyte/macrophage cell line. These data provide insights into the potential multiple beneficial effects of the Mer inhibitor UNC2250 as a therapeutic reagent to treat inflammatory responses in ALI/ARDS.

Are Baseline Levels of Gas6 and Soluble Mer Predictors of Mortality and Organ Damage in Patients with Sepsis? The Need-Speed Trial Database

Soluble tyrosine kinase receptor Mer (sMer) and its ligand Growth arrest-specific protein 6 (Gas6) are predictors of mortality in patients with sepsis. Our aim is to clarify whether their measurement at emergency department (ED) presentation is useful in risk stratification. We re-analyzed data from the Need-Speed trial, evaluating mortality and the presence of organ damage according to baseline levels of sMer and Gas6. 890 patients were eligible; no association with 7- and 30-day mortality was observed for both biomarkers (p > 0.05). sMer and Gas6 levels were significantly higher in acute kidney injury (AKI) patients compared to non-AKI ones (9.8 [4.1–17.8] vs. 7.9 [3.8–12.9] ng/mL and 34.8 [26.4–47.5] vs. 29.8 [22.1–41.6] ng/mL, respectively, for sMer and Gas6), and Gas6 also emerged as an independent AKI predictor (odds ratio (OR) 1.01 [1.00–1.02]). Both sMer and Gas6 independently predicted thrombocytopenia in sepsis patients not treated with anticoagulants (OR 1.01 [1.00–1.02] and 1.04 [1.02–1.06], respectively). Moreover, sMer was an independent predictor of both prothrombin time-international normalized ratio (PT-INR) > 1.4 (OR 1.03 [1.00–1.05]) and sepsis-induced coagulopathy (SIC) (OR 1.05 [1.02–1.07]). An early measurement of the sMer and Gas6 plasma concentration could not predict mortality. However, the biomarkers were associated with AKI, thrombocytopenia, PT-INR derangement and SIC, suggesting a role in predicting sepsis-related organ damage.

Vitamin K Effects on Gas6 and Soluble Axl Receptors in Intensive Care Patients: An Observational Screening Study

Growth arrest-specific gene 6 protein (Gas6) is avitamin K-dependent tissue bound protein. Gas6 has been shown to promote growth and therapy resistance among different types of cancer as well as thromboembolism. The aim of this prospective screening study: ClinicalTrials.gov; Identifier: NTC3782025, was to evaluate the effects of intravenously administered vitamin K1 on Gas6 and its soluble (s)Axl receptor plasma levels in intensive care patients. Vitamin K1 was intravenously injected in non-warfarin treated patients with prolonged Owren prothrombin time international normalized ratio (PT-INR) > 1.2 and blood samples were retrieved before and 20-28 h after injection. Citrate plasma samples from 52 intensive care patients were analysed for different vitamin K dependent proteins. There was a significant, but small increase in median Gas6. Only one patient had a large increase in sAxl, but overall, no significant changes in sAxl Gas6 did not correlate to PT-INR, thrombin generation assay, coagulation factors II, VII, IX and X, but to protein S and decarboxylated matrix Gla protein (dp-ucMGP). In conclusion, there was a small increase in Gas6 over 20-28 h. The pathophysiology and clinical importance of this remains to be investigated. To verify a true vitamin K effect, improvement of Gas6 carboxylation defects needs to be studied.

Evolution of NETosis markers and DAMPs have prognostic value in critically ill COVID-19 patients

Coronavirus disease 19 (COVID-19) presents with disease severities of varying degree. In its most severe form, infection may lead to respiratory failure and multi-organ dysfunction. Here we study the levels and evolution of the damage associated molecular patterns (DAMPS) cell free DNA (cfDNA), extracellular histone H3 (H3) and neutrophil elastase (NE), and the immune modulators GAS6 and AXL in relation to clinical parameters, ICU scoring systems and mortality in patients (n = 100) with severe COVID-19. cfDNA, H3, NE, GAS6 and AXL were increased in COVID-19 patients compared to controls. These measures associated with occurrence of clinical events and intensive care unit acquired weakness (ICUAW). cfDNA and GAS6 decreased in time in patients surviving to 30 days post ICU admission. A decrease of 27.2 ng/mL cfDNA during ICU stay associated with patient survival, whereas levels of GAS6 decreasing more than 4.0 ng/mL associated with survival. The presence of H3 in plasma was a common feature of COVID-19 patients, detected in 38% of the patients at ICU admission. NETosis markers cfDNA, H3 and NE correlated well with parameters of tissue damage and neutrophil counts. Furthermore, cfDNA correlated with lowest p/f ratio and a lowering in cfDNA was observed in patients with ventilator-free days.

Growth Arrest-Specific Factor 6 (GAS6) Is Increased in COVID-19 Patients and Predicts Clinical Outcome

Background: Growth arrest-specific factor 6 (GAS6) and the Tyro3, AXL, and MERTK (TAM) receptors counterbalance pro-inflammatory responses. AXL is a candidate receptor for SARS-CoV-2, particularly in the respiratory system, and the GAS6/AXL axis is targeted in current clinical trials against COVID-19. However, GAS6 and TAMs have not been evaluated in COVID-19 patients at emergency admission. Methods: Plasma GAS6, AXL, and MERTK were analyzed in 132 patients consecutively admitted to the emergency ward during the first peak of COVID-19. Results: GAS6 levels were higher in the SARS-CoV-2-positive patients, increasing progressively with the severity of the disease. Patients with initial GAS6 at the highest quartile had the worst outcome, with a 3-month survival of 65%, compared to a 90% survival for the rest. Soluble AXL exhibited higher plasma concentration in deceased patients, without significant differences in MERTK among SARS-CoV-2-positive groups. GAS6 mRNA was mainly expressed in alveolar cells and AXL in airway macrophages. Remarkably, THP-1 human macrophage differentiation neatly induces AXL, and its inhibition (bemcentinib) reduced cytokine production in human macrophages after LPS challenge. Conclusions: Plasma GAS6 and AXL levels reflect COVID-19 severity and could be early markers of disease prognosis, supporting a relevant role of the GAS6/AXL system in the immune response in COVID-19.

Prognostic performance of pancreatic stone protein in critically ill patients with sepsis

Aim: To assess the prognostic value for 28-day mortality of PSP in critically ill patients with sepsis. Material & methods: 122 consecutive patients with sepsis were enrolled in this study. Blood samples were collected on admission and day 2. Results: On admission, the combination of PSP and lactate achieved an area under the receiver operating characteristic (AUC-ROC) of 0.796, similar to sequential organ failure assessment score alone (AUC-ROC: 0.826). On day 2, PSP was the biomarker with the highest performance (AUC-ROC: 0.844), although lower (p = 0.041) than sequential organ failure assessment score (AUC-ROC: 0.923). Conclusion: The combination of PSP and lactate and PSP alone, on day 2, have a good performance for prognosis of 28-day mortality and could help to identify patients who may benefit most from tailored intensive care unit management.

Gas6/TAM Axis in Sepsis: Time to Consider Its Potential Role as a Therapeutic Target

Tyrosine kinase receptors are transmembrane proteins involved in cell signaling and interaction. Among them, the TAM family (composed by Tyro 3, Axl, and Mer) represents a peculiar subgroup with an important role in many physiological and pathological conditions. Despite different mechanisms of activation (e.g., protein S and Galactin-3), TAM action is tightly related to their common ligand, a protein named growth arrest-specific 6 (Gas6). Since the expression of both TAM and Gas6 is widely distributed among tissues, any alteration of one of these components can lead to different pathological conditions. Moreover, as they are indispensable for homeostasis maintenance, in recent years a growing interest has emerged regarding their role in the regulation of the inflammatory process. Due to this involvement, many authors have demonstrated the pivotal role of the Gas6/TAM axis in both sepsis and the sepsis-related inflammatory responses. In this narrative review, we highlight the current knowledge as well as the last discoveries on TAM and Gas6 implication in different clinical conditions, notably in sepsis and septic shock. Lastly, we underline not only the feasible use of Gas6 as a diagnostic and prognostic biomarker in certain systemic acute conditions but also its potential therapeutic role in these life-threatening diseases.

A high Gas6 level in plasma predicts venous thromboembolism recurrence, major bleeding and mortality in the elderly: a prospective multicenter cohort study

Essentials Predictive ability of pro-hemostatic Gas6 for recurrent venous thromboembolism (VTE) is unknown. We measured Gas6 levels in 864 patients with VTE over 3 years. High Gas6 (> 157%) at diagnosis is associated with VTE recurrence, major bleeding and mortality. Gas6 plasma levels measured 12 months after the index VTE are discriminatory for VTE recurrence. SUMMARY: Background Growth arrest-specific gene 6 (Gas6) is a prohemostatic protein with an unknown predictive ability for recurrent venous thromboembolism (VTE). In the elderly, VTE results in higher mortality but does not have a higher rate of recurrence than in younger patients. Consequently, anticoagulation management in the elderly is challenging. Objective To prospectively investigate the performance of Gas6 in predicting VTE recurrence, major bleeding and mortality in the elderly. Methods Consecutive patients aged ≥ 65 years with acute VTE were followed for a period of 3 years. Primary outcomes were symptomatic VTE recurrence, major bleeding, and mortality. Plasma Gas6 was measured with ELISA. Results Gas6 levels were measured in 864 patients at the time of the index VTE (T1) and, in 70% of them, also 12 months later (T2). The Gas6 level at T1 was discriminatory for VTE recurrence (C-statistic, 0.56; 95% confidence interval [CI] 0.51-0.62), major bleeding (0.60, 95% CI 0.55-0.65) and mortality (0.69, 95% CI 0.65-0.73) up to 36 months. VTE recurrence up to 24 months after T2 was discriminated by the Gas6 level at T2 (0.62, 95% CI 0.54-0.71). High Gas6 levels (> 157%) and continuous Gas6 levels at T1 were associated with VTE recurrence up to 6 months and 12 months, respectively. Conclusions In elderly patients, a high Gas6 level is associated with higher risks of VTE recurrence, major bleeding, and death. These findings support further studies to assess the performance of Gas6 in adjusting the length of anticoagulation.

Reduction in the IL-6 level at 24 h after admission to the intensive care unit is a survival predictor for Vietnamese patients with sepsis and septic shock: a prospective study

Background

Sepsis and septic shock are common problems in intensive care units (ICUs). The mortality of patients with sepsis or septic shock is high. We investigated if reduction in the serum concentration of the cytokines tumor necrosis factor α, interleukin (IL)-6 and IL-10, and the rate of change in the IL-6 level at 24 h after ICU admission were survival predictors for patients with sepsis and septic shock in a Vietnamese population.

Methods

This was a prospective study conducted at an ICU in Cho Ray Hospital, Vietnam, from October 2014 to October 2016. Patients diagnosed with sepsis or septic shock using validated international guidelines were enrolled. Plasma samples were collected upon (T₀) and 24 h after (T₂₄) ICU admission for measurement of cytokine concentrations. Blood tests were done to detect organ dysfunction. The duration of ICU stays, hospital stay, APACHE II and SOFA scores, and the in-hospital mortality were compared between survival and non-survival groups. Univariate logistic regression and multivariate analysis were done to determine the association between survival and IL-6 reduction at 24 h after ICU admission.

Results

A total of 123 patients were enrolled. The concentration (in pg/mL) of IL-6 at T_o was 413.3 in survivors and 530.0 in non- survivors. At T₂₄, the IL-6 level was 65.4 for survivors and 286.9 for non-survivors. The survival rate was 39.0%. At T₂₄, the concentrations of IL-6 and the reduction in IL-6 level were predictors of survival in patients with sepsis and septic shock. We found a significant association between IL-6 reduction and survival at ≥86% with Odds Ratio (OR) 5.67, 95% Confidence Interval (CI); 1.27–25.3, compared with an increase in the IL-6 rate of change.

Conclusions

Our findings suggested that a reduction in the IL-6 level of ≥86% at 24 h from ICU admission is a survival predictor for patients with sepsis and septic shock in our population.

Elevated Plasma Levels of Gas6 Are Associated with Acute Lung Injury in Patients with Severe Sepsis

Acute lung injury (ALI) is one of the complications of severe sepsis, causing sudden deaths. However, information regarding predictive factors for the onset of ALI in severe sepsis is limited. Growth arrest-specific gene 6 (Gas6) is secreted by endothelial cells and is important for the activation of endothelium during inflammation. This study aimed to investigate the predictive effect of plasma Gas6 in patients with severe sepsis. Collection of plasma samples was carried out from 129 participants with severe sepsis following with or without ALI development. We found that the elevated levels of Gas6, interleukin-6 and -8 (IL-6 and IL-8) in plasma were associated with the ALI development (P = 0.003, 0.002, and 0.004, respectively). We also observed the robust correlation between the plasma level of Gas6 and the following ALI development to adjustment for sepsis and administration of vasopressor. Between patients with ALI (n = 18) and those without ALI (n = 111), Gas6 and the Lung Injury Prediction Score (LIPS) showed promising discrimination (AUROC, 0.74 and 0.68, respectively), and in combination with these two indexes, the AUROC was increased to 0.86 (vs. 0.74, P = 0.05), while soluble receptor for advanced glycation end products (sRAGE) and Willebrand factor (vWF) in plasma showed no predictive value for of ALI. Collectively, our findings indicate that higher levels of Gas6 in plasma are obviously correlated with ALI development. An early increase in the plasma Gas6 level suggests that endothelial injury is a key link in the pathogenesis of ALI.