Thrombocytopenia is associated with a dysregulated host response in critically ill sepsis patients

Relationship between thrombocytopenia and prognosis in children with septic shock: a retrospective cohort study

Septic shock is a life-threatening disease worldwide often associated with thrombocytopenia. Platelets play a crucial role in bridging the gap between immunity, coagulation, and endothelial cell activation, potentially influencing the course of the disease. However, there are few studies specifically evaluating the impact of thrombocytopenia on the prognosis of pediatric patients. Therefore, the study investigates effects of early thrombocytopenia in the prognosis of children with septic shock. Pediatric patients with septic shock from 2015 to 2022 were included monocentrically. Thrombocytopenia was defined as a platelet count of <100 × 109/L during the first 24 hours of septic shock onset. The primary outcome was the 28-day mortality. Propensity score matching was used to pair patients with different platelet counts on admission but comparable disease severity. A total of 419 pediatric patients were included in the analysis. Patients with thrombocytopenia had higher 28-day mortality (55.5% vs. 38.7%, p = .005) compared to patients with no thrombocytopenia. Thrombocytopenia was associated with reduced 28-PICU free days (median value, 0 vs. 13 days, p = .003) and 28-ventilator-free (median value, 0 vs. 19 days, p = .001) days. Among thrombocytopenia patients, those with platelet count ≤50 × 109/L had a higher 28-day mortality rate (63.6% vs. 45%, p = .02). Multiple logistic regression showed that elevated lactate (adjusted odds ratio (OR) = 1.11; 95% confidence interval (CI): 1.04-1.17; P <0.001) and white blood cell (WBC) count (OR = 0.97; 95% CI: 0.95-0.99; p = .003) were independent risk factors for the development of thrombocytopenia. Thrombocytopenia group had increased bleeding events, blood product transfusions, and development of organ failure. In Kaplan-Meier survival estimates, survival probabilities at 28 days were greater in patients without thrombocytopenia (p value from the log-rank test, p = .004). There were no significant differences in the type of pathogenic microorganisms and the site of infection between patients with and without thrombocytopenia. In conclusion, thrombocytopenia within 24 hours of shock onset is associated with an increased risk of 28-day mortality in pediatric patients with septic shock.

Prophylactic versus restrictive platelet transfusion strategy in patients with haematological malignancies in the ICU setting, a propensity-score analysis

PURPOSE

Prophylactic platelet transfusions (PT) aim to reduce bleeding. We assessed whether restrictive PT compared to prophylactic strategy could apply in ICU.

MATERIAL AND METHODS

We conducted a retrospective monocentric study including patients >18 yo with haematological malignancy admitted to the ICU with thrombocytopenia <20 G/L between 2018 and 2021. Patients were classified in 2 groups according transfusion strategy applied during the first 3 days: prophylactic or restrictive transfusion.

RESULTS

180 patients were included, 87 and 93 in the restrictive and prophylactic groups respectively. After propensity-score analysis, 2 groups of 54 matched patients were analyzed. Restrictive strategy led to a significant reduction in PT with incidence rate for 100-ICU-patients-days of 34.9 and 49.9, incidence rate ratio = 0.699 [0.5-0.9], p = 0.006, representing a 31% decrease. Decreased PT persisted until day 28 with platelet concentrates transfusions-free days at day 28 of 21 [13-25] and 16.5 [10.2-21] in the 2 groups (p = 0.04). Restrictive strategy did not result in higher grade ≥ 2 bleeding. Transfusion efficiency was low with similar number of days with platelet <10 or < 20 G/L regardless of strategy. Platelet transfusion strategy was not associated with 28-day mortality. Platelet nadir <5G/L was associated with day-28 mortality with HR = 1.882 [1.011-3.055], p = 0.046.

CONCLUSION

A restrictive PT strategy appears feasible in the ICU.

Platelet Activation is Upregulated in Cirrhotic Patients with Portal Vein Thrombosis

OBJECTIVE

 Platelet plays a key role in thrombosis formation, especially that the alteration of platelet function may influence the thrombosis development. This study aimed to investigate platelet function alterations in the formation of portal vein thrombosis (PVT) in cirrhosis.

METHODS

 Cirrhotic patients admitted to The First Affiliated Hospital of Soochow University between October 2021 and April 2023 were recruited and divided into PVT and non-PVT groups according to radiological results. Clinical parameters and prognosis were also collected and assessed to identify potential risk factors. Flow cytometry was used to detect the expression of CD62p, CD63, monocyte-platelet aggregates (MPAs), neutrophil-platelet aggregates (NPAs), and von Willebrand factor antigen (vWF-Ag) to evaluate platelet activation and adhesion function.

RESULTS

 A total of 145 subjects were enrolled in our study including 60 cirrhotic PVT patients, 60 cirrhotic non-PVT patients, and 25 healthy volunteers. Multivariate analysis suggested that esophageal gastric varices, splenectomy, and D-dimer were independent risk factors for PVT pathogenesis in cirrhosis. The vWF-Ag expression level was reduced in the PVT group compared with the non-PVT group (p = 0.046) but was not an independent risk factor for PVT formation pathogenesis. The expression of CD41+CD62p+ and CD41+CD63+ platelets in the PVT group was significantly elevated compared with that in the non-PVT group (p < 0.05). There were no significant differences in MPAs and NPAs between the two cirrhotic groups. Subgroup analysis showed that the mean fluorescence intensity (MFI) of CD62p and CD63 was associated with portal hypertension-related complications (p = 0.008, p < 0.001), and CD63 MFI was significantly associated with thrombosis burden (p = 0.019). CD41+CD62p+ and CD41+CD63+ platelets as well as MPAs and NPAs were highly expressed in the splenectomy group compared with those in the nonsplenectomy group in cirrhotic patients (p < 0.05). Positive correlations were found between CD62p MFI and CD63 MFI, MPAs and NPAs (r = 0.642, p < 0.001; r = 0.378, p = 0.003; r = 0.430, p < 0.001). In addition, platelet counts were also correlated with MPAs (r = 0.556, p < 0.001) and NPAs (r = 0.467, p < 0.001). Cirrhotic patients with PVT had higher mortality and were more likely to experience portal hypertension-related complications in the prognostic analysis (p < 0.05).

CONCLUSION

 Highly activated platelet function exists in patients with cirrhosis, and platelet activation was elevated during PVT formation, suggesting that activated platelets may participate in the formation of PVT in patients with cirrhosis.

The Value of Serum Procalcitonin, Thromboelastography Combined with Platelet Count in Predicting the Short-Term Progression of Septic Shock in the Intensive Care Unit

Objective

By evaluating the level of serum procalcitonin (PCT), thromboelastography (TEG) and platelet count (PLT) of patients with septic shock in intensive care unit (ICU), the predictive value of the combination of the three indicators on the short-term progression was discussed, which provided a new basis for early clinical diagnosis and disease evaluation.

Methods

The clinical data of 130 patients with septic shock admitted to the IUC of our hospital from December 2021 to December 2023 were analyzed retrospectively. These subjects were divided into good prognosis group (n=78) and poor prognosis group (n=52) according to the 28 d deaths. The influencing factors were explored using the Multivariate logistic regression analysis. The value of single or combined PCT, PLT and TEG in predicting poor short-term prognosis was assessed using the receiver operating characteristic (ROC) curve.

Results

The patients in poor prognosis group had higher Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, serum PCT level, coagulation reaction time (R value) and coagulation formation time (K value), but lower PLT levels, final strength of coagulation (MA value) and coagulation formation rate (α angle) than those in good prognosis group (P<0.001). PCT, R value and K value were risk factors (P<0.001), while PLT, MA value and α angle were protective factors (P<0.001). The area under the curve (AUC) of PCT, PLT and TEG predicting poor short-term progression was 0.813, 0.658 and 0.752, respectively. The AUC of combined three indicators was 0.905, which had the highest predictive value.

Conclusion

Serum levels of PCT, PLT and TEG had certain value in predicting poor short-term progression of septic shock patients, and their combined diagnostic value was higher. Therefore, regular monitoring of these three indicators could provide certain guiding significance for the prevention and treatment of poor short-term prognosis in patients with septic shock.

Practical approach to thrombocytopenia in patients with sepsis: a narrative review

Thrombocytopenia frequently occurs in patients with sepsis. Disseminated intravascular coagulation (DIC) may be a possible cause of thrombocytopenia owing to its high prevalence and association with poor outcomes; however, it is important to keep the presence of other diseases in mind in sepsis practice. Thrombotic microangiopathy (TMA), which is characterized by thrombotic thrombocytopenic purpura, Shiga toxin-producing Escherichia coli hemolytic uremic syndrome (HUS), and complement-mediated HUS, is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and organ damage. TMA has become widely recognized in recent years because of the development of specific treatments. Previous studies have reported a remarkably lower prevalence of TMA than DIC; however, its epidemiology is not well defined, and there may be cases in which TMA is not correctly diagnosed, resulting in poor outcomes. Therefore, it is important to differentiate DIC from TMA. Nevertheless, differentiating between DIC and TMA remains a challenge as indicated by previous reports that most patients with TMA can be diagnosed as DIC using the universal coagulation scoring system. Several algorithms to differentiate sepsis-related DIC from TMA have been suggested, contributing to improving the care of septic patients with thrombocytopenia; however, it may be difficult to apply these algorithms to patients with coexisting DIC and TMA, which has recently been reported. This review describes the disease characteristics, including epidemiology, pathophysiology, and treatment, of DIC, TMA, and other diseases with thrombocytopenia and proposes a novel practical approach flow, which is characterized by the initiation of the diagnosis of TMA in parallel with the diagnosis of DIC. This practical flow also refers to the longitudinal diagnosis and treatment flow with TMA in mind and real clinical timeframes. In conclusion, we aim to widely disseminate the results of this review that emphasize the importance of incorporating consideration of TMA in the management of septic DIC. We anticipate that this practical new approach for the diagnostic and treatment flow will lead to the appropriate diagnosis and treatment of complex cases, improve patient outcomes, and generate new epidemiological evidence regarding TMA.

Platelet transcription factors license the pro-inflammatory cytokine response of human monocytes

In humans, blood Classical CD14+ monocytes contribute to host defense by secreting large amounts of pro-inflammatory cytokines. Their aberrant activity causes hyper-inflammation and life-threatening cytokine storms, while dysfunctional monocytes are associated with 'immunoparalysis', a state of immune hypo responsiveness and reduced pro-inflammatory gene expression, predisposing individuals to opportunistic infections. Understanding how monocyte functions are regulated is critical to prevent these harmful outcomes. We reveal platelets' vital role in the pro-inflammatory cytokine responses of human monocytes. Naturally low platelet counts in patients with immune thrombocytopenia or removal of platelets from healthy monocytes result in monocyte immunoparalysis, marked by impaired cytokine response to immune challenge and weakened host defense transcriptional programs. Remarkably, supplementing monocytes with fresh platelets reverses these conditions. We discovered that platelets serve as reservoirs of key cytokine transcription regulators, such as NF-κB and MAPK p38, and pinpointed the enrichment of platelet NF-κB2 in human monocytes by proteomics. Platelets proportionally restore impaired cytokine production in human monocytes lacking MAPK p38α, NF-κB p65, and NF-κB2. We uncovered a vesicle-mediated platelet-monocyte-propagation of inflammatory transcription regulators, positioning platelets as central checkpoints in monocyte inflammation.

Serial platelet count as a dynamic prediction marker of hospital mortality among septic patients

Background

Platelets play a critical role in hemostasis and inflammatory diseases. Low platelet count and activity have been reported to be associated with unfavorable prognosis. This study aims to explore the relationship between dynamics in platelet count and in-hospital morality among septic patients and to provide real-time updates on mortality risk to achieve dynamic prediction.

Methods

We conducted a multi-cohort, retrospective, observational study that encompasses data on septic patients in the eICU Collaborative Research Database (eICU-CRD) and the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. The joint latent class model (JLCM) was utilized to identify heterogenous platelet count trajectories over time among septic patients. We assessed the association between different trajectory patterns and 28-day in-hospital mortality using a piecewise Cox hazard model within each trajectory. We evaluated the performance of our dynamic prediction model through area under the receiver operating characteristic curve, concordance index (C-index), accuracy, sensitivity, and specificity calculated at predefined time points.

Results

Four subgroups of platelet count trajectories were identified that correspond to distinct in-hospital mortality risk. Including platelet count did not significantly enhance prediction accuracy at early stages (day 1 C-indexDynamic  vs C-indexWeibull: 0.713 vs 0.714). However, our model showed superior performance to the static survival model over time (day 14 C-indexDynamic  vs C-indexWeibull: 0.644 vs 0.617).

Conclusions

For septic patients in an intensive care unit, the rapid decline in platelet counts is a critical prognostic factor, and serial platelet measures are associated with prognosis.

Risk factors for bloodstream infection among patients admitted to an intensive care unit of a tertiary hospital of Shanghai, China

Blood flow infections (BSIs) is common occurrences in intensive care units (ICUs) and are associated with poor prognosis. The study aims to identify risk factors and assess mortality among BSI patients admitted to the ICU at Shanghai Ruijin hospital north from January 2022 to June 2023. Additionally, it seeks to present the latest microbiological isolates and their antimicrobial susceptibility. Independent risk factors for BSI and mortality were determined using the multivariable logistic regression model. The study found that the latest incidence rate of BSI was 10.11%, the mortality rate was 35.21% and the mean age of patients with BSI was 74 years old. Klebsiella pneumoniae was the predominant bacterial isolate. Logistic multiple regression revealed that tracheotomy, tigecycline, gastrointestinal bleeding, shock, length of hospital stay, age and laboratory indicators (such as procalcitonine and hemoglobin) were independent risk factors for BSI. Given the elevated risk associated with use of tracheotomy and tigecycline, it underscores the importance of the importance of cautious application of tracheostomy and empirical antibiotic management strategies. Meanwhile, the independent risk factors of mortality included cardiovascular disease, length of hospital stay, mean platelet volume (MPV), uric acid levels and ventilator. BSI patients exhibited a significant decrease in platelet count, and MPV emerged as an independent factor of mortality among them. Therefore, continuous monitoring of platelet-related parameters may aid in promptly identifying high-risk patients and assessing prognosis. Moreover, monitoring changes in uric acid levels may serve as an additional tool for prognostic evaluation in BSI patients.

Platelets: Orchestrators of immunity in host defense and beyond

Platelets prevent blood loss during vascular injury and contribute to thrombus formation in cardiovascular disease. Beyond these classical roles, platelets are critical for the host immune response. They guard the vasculature against pathogens via specialized receptors, intracellular signaling cascades, and effector functions. Platelets also skew inflammatory responses by instructing innate immune cells, support adaptive immunosurveillance, and influence antibody production and T cell polarization. Concomitantly, platelets contribute to tissue reconstitution and maintain vascular function after inflammatory challenges. However, dysregulated activation of these multitalented cells exacerbates immunopathology with ensuing microvascular clotting, excessive inflammation, and elevated risk of macrovascular thrombosis. This dichotomy underscores the critical importance of precisely defining and potentially modulating platelet function in immunity.

Thrombopoietin levels in sepsis and septic shock - a systematic review and meta-analysis

OBJECTIVES

Sepsis is a life-threatening condition implicating an inadequate activation of the immune system. Platelets act as modulators and contributors to immune processes. Indeed, altered platelet turnover, thrombotic events, and changes in thrombopoietin levels in systemic inflammation have been reported, but thrombopoietin-levels in sepsis and septic-shock have not yet been systematically evaluated. We therefore performed a meta-analysis of thrombopoietin (TPO)-levels in patients with sepsis.

METHODS

Two independent reviewers screened records and full-text articles for inclusion. Scientific databases were searched for studies examining thrombopoietin levels in adult sepsis and septic-shock patients until August 1st 2022.

RESULTS

Of 95 items screened, six studies met the inclusion criteria, including 598 subjects. Both sepsis and severe sepsis were associated with increased levels of thrombopoietin (sepsis vs. control: standardized mean difference 3.06, 95 % CI 1.35-4.77; Z=3.50, p=0.0005) (sepsis vs. severe sepsis: standardized mean difference -1.67, 95 % CI -2.46 to -0.88; Z=4.14, p<0.0001). TPO-levels did not show significant differences between severe sepsis and septic shock patients but differed between sepsis and inflammation-associated non-septic controls. Overall, high heterogeneity and low sample size could be noted.

CONCLUSIONS

Concluding, increased levels of thrombopoietin appear to be present both in sepsis and severe sepsis with high heterogeneity but thrombopoietin does not allow to differentiate between severe sepsis and septic-shock. TPO may potentially serve to differentiate sepsis from non-septic trauma and/or tissue damage related (systemic) inflammation. Usage of different assays and high heterogeneity demand standardization of methods and further large multicenter trials.

Thrombocytopenia Independently Leads to Changes in Monocyte Immune Function

BACKGROUND

While platelets have well-studied hemostatic functions, platelets are immune cells that circulate at the interface between the vascular wall and white blood cells. The physiological implications of these constant transient interactions are poorly understood. Activated platelets induce and amplify immune responses, but platelets may also maintain immune homeostasis in healthy conditions, including maintaining vascular integrity and T helper cell differentiation, meaning that platelets are central to both immune responses and immune quiescence. Clinical data have shown an association between low platelet counts (thrombocytopenia) and immune dysfunction in patients with sepsis and extracorporeal membrane oxygenation, further implicating platelets as more holistic immune regulators, but studies of platelet immune functions in nondisease contexts have had limited study.

METHODS

We used in vivo models of thrombocytopenia and in vitro models of platelet and monocyte interactions, as well as RNA-seq and ATAC-seq (assay for transposase-accessible chromatin with sequencing), to mechanistically determine how resting platelet and monocyte interactions immune program monocytes.

RESULTS

Circulating platelets and monocytes interact in a CD47-dependent manner to regulate monocyte metabolism, histone methylation, and gene expression. Resting platelet-monocyte interactions limit TLR (toll-like receptor) signaling responses in healthy conditions in an innate immune training-like manner. In both human patients with sepsis and mouse sepsis models, thrombocytopenia exacerbated monocyte immune dysfunction, including increased cytokine production.

CONCLUSIONS

Thrombocytopenia immune programs monocytes in a manner that may lead to immune dysfunction in the context of sepsis. This is the first demonstration that sterile, endogenous cell interactions between resting platelets and monocytes regulate monocyte metabolism and pathogen responses, demonstrating platelets to be immune rheostats in both health and disease.

Effect of Different Induction Immunosuppression on the Incidence of Infectious Complications after Kidney Transplantation-Single Center Study

Background/Objectives: Potent immunosuppression lowers the incidence of acute graft rejection but increases the risk of infections. In order to decrease either infectious complications or acute rejection, it is necessary to identify risk groups of patients profiting from personalized induction immunosuppressive treatment. The aim of our analysis was to find whether there were higher incidences of infectious complications after kidney transplantation (KT) in groups with different induction immunosuppressive treatment and also to find independent risk factors for recurrent infections. Materials: We retrospectively evaluated all patients with induction treatment with basiliximab after kidney transplantation from 2014 to 2019 at our center relative to age- and sex-matched controls of patients with thymoglobulin induction immunosuppression. Results: Our study consisted of two groups: basiliximab (39) and thymoglobulin (39). In the thymoglobulin group we observed an increased incidence of recurrent infection in every observed interval; however, acute rejection was seen more often in the basiliximab group. A history of respiratory diseases and thrombocytopenia were identified as independent risk factors for recurrent bacterial infections from the first to sixth month after KT. Decreased eGFR from the first month, infections caused by multi-drug-resistant bacteria, and severe infections (reflected by the need for hospitalization) were identified as independent risk factors for recurrent bacterial infections from the first to the twelfth month after KT. Conclusions: We found that in the group of patients with thymoglobulin induction immunosuppressive treatment, infectious complications occurred significantly more often during the entire monitored period with decreased incidence of acute humoral and cellular rejection occurred more often.

Sepsis-Induced Coagulopathy: A Comprehensive Narrative Review of Pathophysiology, Clinical Presentation, Diagnosis, and Management Strategies

Physiological hemostasis is a balance between pro- and anticoagulant pathways, and in sepsis, this equilibrium is disturbed, resulting in systemic thrombin generation, impaired anticoagulant activity, and suppression of fibrinolysis, a condition termed sepsis-induced coagulopathy (SIC). SIC is a common complication, being present in 24% of patients with sepsis and 66% of patients with septic shock, and is often associated with poor clinical outcomes and high mortality. 1 , 2 Recent preclinical and clinical studies have generated new insights into the molecular pathogenesis of SIC. In this article, we analyze the complex pathophysiology of SIC with a focus on the role of procoagulant innate immune signaling in hemostatic activation--tissue factor production, thrombin generation, endotheliopathy, and impaired antithrombotic functions. We also review clinical presentations of SIC, the diagnostic scoring system and laboratory tests, the current standard of care, and clinical trials evaluating the efficacies of anticoagulant therapies.

Unlocking the potential of senescence-related gene signature as a diagnostic and prognostic biomarker in sepsis: insights from meta-analyses, single-cell RNA sequencing, and in vitro experiments

Cellular senescence is closely associated with the pathogenesis of sepsis. However, the diagnostic and prognostic value of senescence-related genes remain unclear. In this study, 866 senescence-related genes were collected from CellAge. The training cohort, GSE65682, which included 42 control and 760 sepsis samples, was obtained from the Gene Expression Omnibus (GEO). Feature selection was performed using gene expression difference detection, LASSO analysis, random forest, and Cox regression. TGFBI and MAD1L1 were ultimately selected for inclusion in the multivariate Cox regression model. Clustering based on the expressions of TGFBI and MAD1L1 was significantly associated with sepsis characteristics and prognoses (all P < 0.05). The risk signature served as a reliable prognostic predictor across the GSE65682, GSE95233, and GSE4607 cohorts (pooled hazard ratio = 4.27; 95% confidence interval [CI] = 1.63-11.17). Furthermore, it also served as a robust classifier to distinguish sepsis samples from control cases across 14 cohorts (pooled odds ratio = 5.88; 95% CI = 3.54-9.77). Single-cell RNA sequencing analyses from five healthy controls and four sepsis subjects indicated that the risk signature could reflect the senescence statuses of monocytes and B cells; this finding was then experimentally validated in THP-1 and IM-9 cells in vitro (both P < 0.05). In all, a senescence-related gene signature was developed as a prognostic and diagnostic biomarker for sepsis, providing cut-in points to uncover underlying mechanisms and a promising clinical tool to support precision medicine.

Platelet Count During Course of Cardiogenic Shock

The study investigates the prognostic value of the platelet count in patients with cardiogenic shock (CS). Limited data regarding the prognostic value of platelets in patients suffering from CS is available. Consecutive patients with CS from 2019 to 2021 were included at one institution. Firstly, the prognostic value of the baseline platelet count was tested for 30-day all-cause mortality. Thereafter, the prognostic impact of platelet decline during course of intensive care unit (ICU) hospitalization was assessed. A total of 249 CS patients were included with a median platelet count of 224 × 10 6 /ml. No association of the baseline platelet count with the risk of 30-day all-cause mortality was found (log-rank p = 0.563; hazard ratio [HR] = 0.879; 95% confidence interval [CI] 0.557-1.387; p = 0.579). In contrast, a decrease of platelet count by ≥ 25% from day 1 to day 3 was associated with an increased risk of 30-day all-cause mortality (55% vs. 39%; log-rank p = 0.045; HR = 1.585; 95% CI 0.996-2.521; p = 0.052), which was still evident after multivariable adjustment (HR = 1.951; 95% CI 1.116-3.412; p = 0.019). Platelet decrease during the course of ICU hospitalization but not the baseline platelet count was associated with an increased risk of 30-day all-cause mortality in CS patients.

The Function of ASK1 in Sepsis and Stress-Induced Disorders

Apoptosis signal-regulating kinase 1 (ASK1) is a serine-threonine kinase that is ubiquitously expressed in nucleated cells and is responsible for the activation of multiple mitogen-activated protein kinases (MAPK) to regulate cell stress. Activation of ASK1 via cellular stress leads to activation of downstream signaling components, activation of transcription factors, and proinflammatory cytokine production. ASK1 is also expressed in anucleate platelets and is a key player in platelet activation as it is important for signaling. Interestingly, the mechanism of ASK1 activation is cell type-dependent. In this review we will explore how ASK1 regulates a variety of cellular processes from innate immune function to thrombosis and hemostasis. We will discuss how ASK1 influences FcγRIIA-mediated platelet reactivity and how that reactivity drives platelet clearance. Furthermore, we will explore the role of ASK1 in thromboxane (TxA2) generation, which highlights differences in the way ASK1 functions in mouse and human platelets.

Diagnostic and prognostic role of platelets in patients with sepsis and septic shock

Studies investigating the prognostic role of platelets commonly include critically ill patients, whereas data regarding the prognostic impact of platelet count in patients admitted with sepsis and septic shock is limited. Therefore, the study investigates the prognostic role of platelet count in patients with sepsis and septic shock. Consecutive patients with sepsis and septic shock from 2019 to 2021 were included monocentrically. Blood samples were retrieved from the day of disease onset (day 1), days 2, 3, 5, 7 and 10. Firstly, the diagnostic value of platelet count was tested for septic shock compared to sepsis. Secondly, the prognostic value of platelet count was tested for 30-day all-cause mortality. Statistical analyses included univariable t-test, Spearman's correlation, C-statistics, Kaplan-Meier analyses, as well as multivariable mixed analysis of variance (ANOVA), Cox proportional regression analyses and propensity score matching. A total of 358 patients with sepsis and septic shock were included with a median platelet count of 176 × 10⁶/ml. The presence of thrombocytopenia (i.e. <150 × 10⁶/ml) was associated with increased risk of 30-day mortality (HR = 1.409; 95% CI 1.057-1.878; p = .019), which was still demonstrated after propensity score matching. During the course of sepsis, a nadir was observed on sepsis day 5 with a decrease in the mean platelet count by 21.5%. Especially serum lactate, mean arterial pressure and the presence of malignancies were found to predict platelet decline during the course of sepsis/septic shock. The presence of platelet decline >25% was associated with an increased risk of 30-day all-cause mortality (HR = 1.484; 95% CI 1.045-2.109; p = .028). Following platelet decline, recovery was observed from day 5 to day 10 (mean increase 7.5%). However, platelet recovery was not found to be associated with 30-day all-cause mortality (HR = 1.072; 95% CI 0.567-2.026; p = .832). In conclusion, both thrombocytopenia and platelet decline during the course of sepsis were associated with an increased risk of 30-day all-mortality in patients admitted with sepsis or septic shock.

C-Type Lectin-like Receptor 2 Expression Is Decreased upon Platelet Activation and Is Lower in Most Tumor Entities Compared to Healthy Controls

The C-type lectin-like receptor 2 (CLEC-2) is expressed on platelets and mediates binding to podoplanin (PDPN) on various cell types. The binding to circulating tumor cells (CTCs) leads to platelet activation and promotes metastatic spread. An increased level of soluble CLEC-2 (sCLEC-2), presumably released from activated platelets, was shown in patients with thromboinflammatory and malignant disease. However, the functional role of sCLEC-2 and the mechanism of sCLEC-2 release are not known. In this study, we focused on the effect of platelet activation on CLEC-2 expression and the sCLEC-2 plasma level in patients with cancer. First, citrated blood from healthy volunteer donors (n = 20) was used to measure the effect of platelet stimulation by classical agonists and PDPN on aggregation, CLEC-2 expression on platelets with flow cytometry, sCLEC-2 release to the plasma with ELISA and total CLEC-2 expression with Western blot analysis. Second, sCLEC-2 was determined in plasma samples from healthy donors (285) and patients with colorectal carcinoma (CRC; 194), melanoma (160), breast cancer (BC; 99) or glioblastoma (49). PDPN caused a significant increase in the aggregation response induced by classical agonists. ADP or PDPN stimulation of platelets caused a significant decrease in CLEC-2 on platelets and sCLEC-2 in the plasma, whereas total CLEC-2 in platelet lysates remained the same. Thus, the increased plasma level of sCLEC-2 is not a suitable biomarker of platelet activation. In patients with CRC (median 0.9 ng/mL), melanoma (0.9 ng/mL) or BC (0.7 ng/mL), we found significantly lower sCLEC-2 levels (p < 0.0001), whereas patients with glioblastoma displayed higher levels (2.6 ng/mL; p = 0.0233) compared to healthy controls (2.1 ng/mL). The low sCLEC-2 plasma level observed in most of the tumor entities of our study presumably results from the internalization of sCLEC-2 by activated platelets or binding of sCLEC-2 to CTCs.

A simplified machine learning model utilizing platelet-related genes for predicting poor prognosis in sepsis

Background

Thrombocytopenia is a known prognostic factor in sepsis, yet the relationship between platelet-related genes and sepsis outcomes remains elusive. We developed a machine learning (ML) model based on platelet-related genes to predict poor prognosis in sepsis. The model underwent rigorous evaluation on six diverse platforms, ensuring reliable and versatile findings.

Methods

A retrospective analysis of platelet data from 365 sepsis patients confirmed the predictive role of platelet count in prognosis. We employed COX analysis, Least Absolute Shrinkage and Selection Operator (LASSO) and Support Vector Machine (SVM) techniques to identify platelet-related genes from the GSE65682 dataset. Subsequently, these genes were trained and validated on six distinct platforms comprising 719 patients, and compared against the Acute Physiology and Chronic Health Evaluation II (APACHE II) and Sequential Organ-Failure Assessment (SOFA) score.

Results

A PLT count <100×109/L independently increased the risk of death in sepsis patients (OR = 2.523; 95% CI: 1.084-5.872). The ML model, based on five platelet-related genes, demonstrated impressive area under the curve (AUC) values ranging from 0.5 to 0.795 across various validation platforms. On the GPL6947 platform, our ML model outperformed the APACHE II score with an AUC of 0.795 compared to 0.761. Additionally, by incorporating age, the model's performance was further improved to an AUC of 0.812. On the GPL4133 platform, the initial AUC of the machine learning model based on five platelet-related genes was 0.5. However, after including age, the AUC increased to 0.583. In comparison, the AUC of the APACHE II score was 0.604, and the AUC of the SOFA score was 0.542.

Conclusion

Our findings highlight the broad applicability of this ML model, based on platelet-related genes, in facilitating early treatment decisions for sepsis patients with poor outcomes. Our study paves the way for advancements in personalized medicine and improved patient care.

Dysregulated neutrophil extracellular traps formation in sepsis

The migration and antimicrobial functions of neutrophils seem to be impaired during sepsis and contribute to the dysregulation of immune responses and disease pathogenesis. However, the role of neutrophil extracellular traps (NETs) remains to be clarified. The study aimed to analyse sequential phenotypic and functional changes of neutrophils during the time following the diagnosis of sepsis. We prospectively enrolled 49 septic and 18 non-septic patients from the intensive care unit (ICU) and emergency room (ER) and 20 healthy volunteers (HV). Baseline blood samples from septic and non-septic patients were collected within 12 h of admission to the hospital. Additional septic samples were drawn at 24, 48 and 72 h after baseline. Neutrophil phenotype and degranulation capacity were assessed by flow cytometry and NET formation was quantified by fluorescence. Neutrophils from septic patients exhibited increased CD66b, CD11b and CD177 expression but displayed reduced NET formation at baseline compared with non-septic patients and HV controls. Neutrophils expressing CD177 interacted less with platelets, were related to reduced NETosis and tended to indicate a worse sepsis outcome. In vitro experiments revealed that neutrophil function is compromised by the origin of sepsis, including the pathogen type and the affected organ. Assessing a decision tree model, our study showed that CD11b expression and NETosis values are useful variables to discriminate septic from non-septic patients. We conclude that sepsis induces changes in neutrophil phenotype and function that may compromise the effective capacity of the host to eliminate pathogens.

Association between admission systemic immune-inflammation index and mortality in critically ill patients with sepsis: a retrospective cohort study based on MIMIC-IV database

Systemic immune-inflammation index (SII) has been identified as a prognostic biomarker for various diseases. Our study aimed to investigate the association between SII and mortality risk in critically ill patients with sepsis, thus exploring possible tools for rapid screening. This retrospective cohort study was conducted using clinical data extracted from the Medical Information Mart for Intensive Care Database. The study included only patients diagnosed with sepsis admitted to the intensive care unit for the first time. We used the restricted cubic splines to explore the relationship between SII and 28-day mortality. Kaplan-Meier curve and Cox regression models were performed to evaluate the association between SII and mortality. Subgroup analysis was performed to explore the stability of the primary results. A total of 16,007 patients with sepsis were eligible in the final analysis. We found a J-shaped relationship between SII and mortality risk. The SII level associated with the lowest mortality risk was 774.46*109/L. Compared with the reference group (second SII quartile), the 28-day mortality was increased in the highest quartile and third quartile groups of SII levels; fully adjusted HRs were 1.16 (1.02 to 1.32) and 1.40 (1.23 to 1.58), respectively. However, although the lower SII (Q1 group) also showed a trend toward a higher hazard of 28-day mortality, there was no statistical difference, with a fully adjusted HR of 1.05 (0.92 to 1.21). In the population of critically ill patients with sepsis, low and high SII levels were associated with an increased risk of short-term mortality. The 28-day mortality risk was lowest at SII levels of 774.46*109/L.

Hemostasis without clot formation: how platelets guard the vasculature in inflammation, infection, and malignancy

Platelets are key vascular effectors in hemostasis, with activation signals leading to fast recruitment, aggregation, and clot formation. The canonical process of hemostasis is well-characterized and shares many similarities with pathological thrombus formation. However, platelets are also crucially involved in the maintenance of vascular integrity under both steady-state and inflammatory conditions by ensuring blood vessel homeostasis and preventing microbleeds. In these settings, platelets use distinct receptors, signaling pathways, and ensuing effector functions to carry out their deeds. Instead of simply forming clots, they mainly act as individual sentinels that swiftly adapt their behavior to the local microenvironment. In this review, we summarize previously recognized and more recent studies that have elucidated how anucleate, small platelets manage to maintain vascular integrity when faced with challenges of infection, sterile inflammation, and even malignancy. We dissect how platelets are recruited to the vascular wall, how they identify sites of injury, and how they prevent hemorrhage as single cells. Furthermore, we discuss mechanisms and consequences of platelets' interaction with leukocytes and endothelial cells, the relevance of adhesion as well as signaling receptors, in particular immunoreceptor tyrosine-based activation motif receptors, and cross talk with the coagulation system. Finally, we outline how recent insights into inflammatory hemostasis and vascular integrity may aid in the development of novel therapeutic strategies to prevent hemorrhagic events and vascular dysfunction in patients who are critically ill.

Common laboratory tests and their correlation with the clinical presentation and prognosis of Lemierre syndrome

INTRODUCTION

Lemierre syndrome is a thromboembolic complication following an acute bacterial infection of the head/neck area, often due to anaerobes. Data on the prognostic role of laboratory parameters is lacking.

METHODS

We analyzed individual-patient level data from a multinational cohort of patients with Lemierre-syndrome. Patients had an infection in the head/neck area, and contiguous vein thrombosis or septic embolism, irrespective of the causal pathogen. We studied the patterns of white blood cell count, platelet count, and C-reactive protein concentration investigating their association with baseline characteristics and in-hospital clinical outcomes (septic embolism, major bleeding, all-cause death).

RESULTS

A total of 447 (63%) patients had complete data for analysis. White blood cells were elevated across all subgroups (median 17 × 103/μL; Q1-Q3:12-21). Median platelet count was 61 × 103/μL (Q1-Q3:30-108) with decreasing levels with increasing age. Males, patients with renal failure or cardiopulmonary impairment, and those with typical Lemierre syndrome (tonsillitis, septic thromboembolism, positivity for Fusobacterium spp.) had the lowest platelet count. Median C-reactive protein was 122 (Q1-Q3:27-248) mg/L with higher values in patients who also had more severe thrombocytopenia. The overall risk of complications was similar across subgroups of patients stratified according to white blood cell and C-reactive protein levels. Patients in the lowest third of platelet count (<42 × 103/μL) had the highest rate of complications (26%), as opposed to those in the highest third (11%), notably septic embolic events.

CONCLUSIONS

Common laboratory tests correlate with the clinical presentation of Lemierre syndrome. However, extreme values did not appear to be prognostically relevant for in-hospital complications and potentially able to improve clinical management.

Four Assessment Tools for Predicting Mortality and Adverse Events in Surgical Patients With Sepsis and Septic Shock: A Comparative Study

BACKGROUND

The mortality rate for sepsis and septic shock in surgical patients is approximately 36%, which is higher than that of other medical patients. Predisposition, infection/injury, response, and organ dysfunction (PIRO) is currently the most widely used tool for assessing patients with surgical sepsis. However, it is not a standardized assessment tool for surgical patients in general.

PURPOSE

The purposes of this study were to (a) create a modified PIRO (mPIRO) that adds a count of platelets and does not include a body temperature reading; (b) test the sensitivity and specificity of the mPIRO for predicting mortality and adverse events among patients with surgical sepsis; and (c) compare the predictive accuracy of the mPIRO, sequential organ failure assessment (SOFA), quick SOFA, and PIRO tools.

METHODS

A retrospective observational cohort study was conducted. Two thousand fifty-five patient medical records were reviewed, with 103 identified as meeting the inclusion criteria.

RESULTS

Compared with the other tools, mPIRO ≥ 4 achieved better sensitivity (90.5%) in predicting mortality and high sensitivity (72%) and specificity (80%) in predicting adverse events. mPIRO was the most accurate predictor of mortality (area under the receiver operating characteristic curve [AUC] = 0.83) among the tools considered. SOFA and mPIRO were the first and second most accurate predictor of adverse events, respectively, with respective AUC values of 0.86 and 0.82.

CONCLUSIONS/IMPLICATIONS FOR PRACTICE

mPIRO, which employs an easy-to-use scoring system, is a valid assessment tool with good sensitivity and AUC for predicting both mortality and adverse events in patients with surgical sepsis. We recommend using mPIRO ≥ 3 as an indicator of potential adverse events.

Current knowledge of thrombocytopenia in sepsis and COVID-19

Thrombocytopenia, characterized by a decrease in platelet count, is commonly observed in sepsis and COVID-19. In sepsis, thrombocytopenia can result from various mechanisms, including impaired platelet production in the bone marrow, accelerated platelet destruction due to increased inflammation, sequestration of platelets in the spleen, immune-mediated platelet destruction, or dysregulated host responses. Similarly, thrombocytopenia has been reported in COVID-19 patients, but the immune-related mechanisms underlying this association remain unclear. Notably, interventions targeting thrombocytopenia have shown potential for improving outcomes in both sepsis and COVID-19 patients. Understanding these mechanisms is crucial for developing effective treatments.

Platelet count predicts mortality in patients with sepsis: A retrospective observational study

Platelet count is a key component of sepsis severity score. However, the predictive value of the platelet count at admission for mortality in sepsis remains unclear. We designed a retrospective observational study of patients with sepsis admitted to our hospital from January 2017 to September 2021 to explore the predictive value of platelet count at admission for mortality. A total of 290 patients with sepsis were included in this study. Multivariate logistic regression analysis was used to evaluate the risk factors for mortality and construct a predictive model with statistically significant factors. Compared with survivors, nonsurvivors tended to be much older and had significantly higher acute physiology and chronic health evaluation II and sequential organ failure assessment scores (P < .001). The platelet count was significantly lower in the nonsurvivor group than in the survivor group (P < .001). Multivariate logistic regression analysis indicated that age (P = .003), platelet count (P < .001) and lactate level (P = .018) were independent risk factors for mortality in patients with sepsis. Finally, the area under the receiver operating characteristic curve of platelet count predicting mortality in sepsis was 0.763 (95% confidence interval, 0.709-0.817, P < .001), with a sensitivity of 55.6% and a specificity of 91.8%. In our study, platelet count at admission as a single biomarker showed good predictability for mortality in patients with sepsis.

Thrombocytopenia is associated with a dysregulated host response in severe COVID-19

BACKGROUND

Thrombocytopenia is associated with increased mortality in COVID-19 patients.

OBJECTIVE

To determine the association between thrombocytopenia and alterations in host response pathways implicated in disease pathogenesis in patients with severe COVID-19.

PATIENTS/METHODS

We studied COVID-19 patients admitted to a general hospital ward included in a national (CovidPredict) cohort derived from 13 hospitals in the Netherlands. In a subgroup, 43 host response biomarkers providing insight in aberrations in distinct pathophysiological domains (coagulation and endothelial cell function; inflammation and damage; cytokines and chemokines) were determined in plasma obtained at a single time point within 48 h after admission. Patients were stratified in those with normal platelet counts (150-400 × 109/L) and those with thrombocytopenia (<150 × 109/L).

RESULTS

6.864 patients were enrolled in the national cohort, of whom 1.348 had thrombocytopenia and 5.516 had normal platelets counts; the biomarker cohort consisted of 429 patients, of whom 85 with thrombocytopenia and 344 with normal platelet counts. Plasma D-dimer levels were not different in thrombocytopenia, although patients with moderate-severe thrombocytopenia (<100 × 109/L) showed higher D-dimer levels, indicating enhanced coagulation activation. Patients with thrombocytopenia had lower plasma levels of many proinflammatory cytokines and chemokines, and antiviral mediators, suggesting involvement of platelets in inflammation and antiviral immunity. Thrombocytopenia was associated with alterations in endothelial cell biomarkers indicative of enhanced activation and a relatively preserved glycocalyx integrity.

CONCLUSION

Thrombocytopenia in hospitalized patients with severe COVID-19 is associated with broad host response changes across several pathophysiological domains. These results suggest a role of platelets in the immune response during severe COVID-19.

PAI-1 genetic polymorphisms influence septic patients' outcomes by regulating neutrophil activity

BACKGROUND

Plasminogen activator inhibitor-1 (PAI-1) plays an important role in the pathophysiology of sepsis, but the exact mechanism remains debatable. In this study, we investigated the associations among the serum levels of PAI-1, the incidence of 4G/5G promoter PAI-1 gene polymorphisms, immunological indicators, and clinical outcomes in septic patients.

METHODS

A total of 181 patients aged 18-80 years with sepsis between November 2016 and August 2018 in the intensive care unit in the Xinhua Hospital were recruited in this retrospective study, with 28-day mortality as the primary outcome. The initial serum level of PAI-1 and the presence of rs1799768 single nucleotide polymorphisms (SNPs) were examined. Univariate logistic regression and multivariate analyses were performed to determine the factors associated with different genotypes of PAI-1, serum level of PAI-1, and 28-day mortality.

RESULTS

The logistic analysis suggested that a high serum level of PAI-1 was associated with the rs1799768 SNP of PAI-1 (4G/4G and 4G/5G) (Odds ratio [OR]: 2.49; 95% confidence interval [CI]: 1.09, 5.68). Furthermore, a high serum level of PAI-1 strongly influenced 28-day mortality (OR 3.36; 95% CI 1.51, 7.49). The expression and activation of neutrophils (OR 0.96; 95% CI 0.93, 0.99), as well as the changes in the expression patterns of cytokines and chemokine-associated neutrophils (OR: 1.00; 95% CI: 1.00, 1.00), were both regulated by the genotype of PAI-1.

CONCLUSIONS

Genetic polymorphisms of PAI-1 can influence the serum levels of PAI-1, which might contribute to mortality by affecting neutrophil activity. Thus, patients with severe sepsis might clinically benefit from enhanced neutrophil clearance and the resolution of inflammation via the regulation of PAI-1 expression and activity.

Platelet ITGA2B inhibits caspase-8 and Rip3/Mlkl-dependent platelet death though PTPN6 during sepsis

Platelets play an important role in the pathogenesis of sepsis and platelet transfusion is a therapeutic option for sepsis patients, although the exact mechanisms have not been elucidated so far. ITGA2B encodes the αIIb protein in platelets, and its upregulation in sepsis is associated with increased mortality rate. Here, we generated a Itga2b (Q887X) knockin mouse, which significantly reduced ITGA2B expression of platelet and megakaryocyte. The decrease of ITGA2B level aggravated the death of septic mice. We analyzed the transcriptomic profiles of the platelets using RNA sequencing. Our findings suggest that ITGA2B upregulates PTPN6 in megakaryocytes via the transcription factors Nfkb1 and Rel. Furthermore, PTPN6 inhibits platelet apoptosis and necroptosis during sepsis by targeting the Ripk1/Ripk3/Mlkl and caspase-8 pathways. This prevents Kupffer cells from rapidly clearing activated platelets, and eventually maintains vascular integrity during sepsis. Our findings indicate a new function of ITGA2B in the regulation of platelet death during sepsis.

Thrombocytopenia as an important determinant of poor prognosis in patients with pyogenic liver abscess: a retrospective case series

BACKGROUND

Thrombocytopenia and poor prognosis in severe conditions are associated. However, the clinical significance of thrombocytopenia in pyogenic liver abscess (PLA) has not been evaluated.

OBJECTIVE

To evaluate the association between thrombocytopenia and the prognosis of patients with PLA.

METHODS

A consecutive case series of 458 adult patients with PLA hospitalized at Tongji Hospital (Wuhan, China) between October 2011 and June 2021 was included in this cross-sectional analysis. Patient data were compared between the thrombocytopenia and non-thrombocytopenia groups. Multivariate logistic regression, receiver operating characteristic (ROC) curve and propensity score -matched analyses (PSM) were performed.

RESULTS

Of the 458 patients with PLA, 94 (20.5%) developed thrombocytopenia, 19 (4.1%) developed septic shock, 14 (3.1%) were admitted to the ICU, and 15 (3.3%) died during hospitalization. Thrombocytopenia was independently associated with shock (95%CI = 3.529-57.944, P < 0.001), ICU admission (95%CI = 1.286-25.733, P = 0.022), and mortality (95%CI = 1.947-34.223, P = 0.004) in multivariate regression analysis. ROC analysis showed that thrombocytopenia may be an identified marker of shock [area under the ROC curve (AUC), 0.8119; cut-off, 92.50; P < 0.0001], ICU admission (AUC, 0.7484; cut-off, 82.50; P < 0.0015), and mortality (AUC, 0.7827; cut-off, 122.50; P < 0.002). These findings remained consistent across 86 pairs of patients analyzed for PSM analyses.

CONCLUSIONS

Thrombocytopenia is an independent risk factor for poor prognosis in PLA and patients may be more prone to adverse outcomes.

Myristica fragrans Extract Inhibits Platelet Desialylation and Activation to Ameliorate Sepsis-Associated Thrombocytopenia in a Murine CLP-Induced Sepsis Model

Sepsis, characterized by an uncontrolled host inflammatory response to infections, remains a leading cause of death in critically ill patients worldwide. Sepsis-associated thrombocytopenia (SAT), a common disease in patients with sepsis, is an indicator of disease severity. Therefore, alleviating SAT is an important aspect of sepsis treatment; however, platelet transfusion is the only available treatment strategy for SAT. The pathogenesis of SAT involves increased platelet desialylation and activation. In this study, we investigated the effects of Myristica fragrans ethanol extract (MF) on sepsis and SAT. Desialylation and activation of platelets treated with sialidase and adenosine diphosphate (platelet agonist) were assessed using flow cytometry. The extract inhibited platelet desialylation and activation via inhibiting bacterial sialidase activity in washed platelets. Moreover, MF improved survival and reduced organ damage and inflammation in a mouse model of cecal ligation and puncture (CLP)-induced sepsis. It also prevented platelet desialylation and activation via inhibiting circulating sialidase activity, while maintaining platelet count. Inhibition of platelet desialylation reduces hepatic Ashwell-Morell receptor-mediated platelet clearance, thereby reducing hepatic JAK2/STAT3 phosphorylation and thrombopoietin mRNA expression. This study lays a foundation for the development of plant-derived therapeutics for sepsis and SAT and provides insights into sialidase-inhibition-based sepsis treatment strategies.

Thrombocytopenia Independently Leads to Monocyte Immune Dysfunction

In addition to their well-studied hemostatic functions, platelets are immune cells. Platelets circulate at the interface between the vascular wall and leukocytes, and transient platelet-leukocyte complexes are found in both healthy and disease states, positioning platelets to provide physiologic cues of vascular health and injury. Roles for activated platelets in inducing and amplifying immune responses have received an increasing amount of research attention, but our past studies also showed that normal platelet counts are needed in healthy conditions to maintain immune homeostasis. We have now found that thrombocytopenia (a low platelet count) leads to monocyte dysfunction, independent of the cause of thrombocytopenia, in a manner that is dependent on direct platelet-monocyte CD47 interactions that regulate monocyte immunometabolism and gene expression. Compared to monocytes from mice with normal platelet counts, monocytes from thrombocytopenic mice had increased toll-like receptor (TLR) responses, including increased IL-6 production. Furthermore, ex vivo co-incubation of resting platelets with platelet naïve bone marrow monocytes, induced monocyte metabolic programming and durable changes in TLR agonist responses. Assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-Seq) on monocytes from thrombocytopenic mice showed persistently open chromatin at LPS response genes and resting platelet interactions with monocytes induced histone methylation in a CD47 dependent manner. Using mouse models of thrombocytopenia and sepsis, normal platelet numbers were needed to limit monocyte immune dysregulation and IL6 expression in monocytes from human patients with sepsis also inversely correlated with patient platelet counts. Our studies demonstrate that in healthy conditions, resting platelets maintain monocyte immune tolerance by regulating monocyte immunometabolic processes that lead to epigenetic changes in TLR-related genes. This is also the first demonstration of sterile cell interactions that regulate of innate immune-metabolism and monocyte pathogen responses.

Orthopaedic infections: what have we learned?

Orthopaedic infections remain challenging complications to treat, with profound economic impact in addition to patient morbidity. The overall estimates of infection after orthopaedic surgery with internal devices has been estimated at 5%, with hospital costs eight times that of those without fracture-related infections and with significantly poorer functional and pain interference PROMIS scores. Orthopaedic infection interventions have been focused on prevention and treatment options. The creation of new modalities for orthopaedic infection treatment can benefit from the understanding of the temporal relationship between bacterial colonization and host-cell integration, a concept referred to as "the race for the surface." Regarding prevention, host modulation and antibiotic powder use have been explored as viable options to lower infection rates. Orthopaedic infection treatment has additionally continued to evolve, with PO antibiotics demonstrating equivalent efficacy to IV antibiotics for the treatment of orthopaedic infections in recent studies. In conclusion, orthopaedic infections remain difficult clinical dilemmas, although evolving prevention and treatment modalities continue to emerge.

SCIATIC DENERVATION-INDUCED SKELETAL MUSCLE ATROPHY IS ASSOCIATED WITH PERSISTENT INFLAMMATION AND INCREASED MORTALITY DURING SEPSIS

ABSTRACT

Background: Patients with underlying skeletal muscle atrophy are likely to develop aggravated sepsis. However, no study has experimentally verified the association between the prognosis of sepsis and muscle atrophy, and the mechanism of aggravation of sepsis under muscle atrophy remains unclear. In this study, we investigated the effect of skeletal muscle atrophy induced by sciatic denervation (DN), an experimental muscle atrophy model, on sepsis prognosis. Methods: Skeletal muscle atrophy was induced by DN of the sciatic nerve in C57BL/6J male mice. Cecal ligation and puncture (CLP) was performed to induce sepsis. Results: The survival rates of the sham and DN groups 7 days after CLP were 63% and 35%, respectively, wherein an approximately 30% reduction was observed in the DN group ( P < 0.05, vs. sham-CLP). The DN group had a higher bacterial count in the blood 48 h after CLP ( P < 0.05, vs. sham-CLP). Notably, NOx (a metabolite of nitric oxide) concentrations in DN mice were higher than those in sham mice after CLP ( P < 0.05, vs. sham-CLP), whereas serum platelet levels were lower 48 h after CLP ( P < 0.05, vs. sham-CLP). In organ damage analysis, DN mice presented increased protein expression of the kidney injury molecule (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL), a kidney injury marker, after CLP (NGAL 48 h after CLP, P < 0.05, vs. sham-CLP; KIM-1 24 h after CLP, P < 0.01, vs. sham-CLP). Furthermore, nitro tyrosine levels in the kidneys of DN mice were higher 48 h after CLP compared with those in sham-CLP mice, indicating the accumulation of nitrative stress ( P < 0.05, vs. sham-CLP). Serum cytokine levels were increased in both groups after CLP, but decreased in the sham group 48 h after CLP and remained consistently higher in the DN group (tumor necrosis factor [TNF]-α: P < 0.05, sham-CLP vs. DN-CLP; interleukin (IL)-1β: P < 0.01, sham-CLP vs. DN-CLP; IL-6: P < 0.05, DN vs. DN-CLP; IL-10: P < 0.05, sham-CLP vs. DN-CLP). Conclusions: We verified that skeletal muscle atrophy induced by DN is associated with poor prognosis after CLP-induced sepsis. Importantly, mice with skeletal muscle atrophy presented worsening sepsis prognosis at late onset, including prolonged infection, persistent inflammation, and kidney damage accumulation, resulting in delayed recovery.

Blood count derangements after sepsis and association with post-hospital outcomes

Rationale

Predicting long-term outcomes in sepsis survivors remains a difficult task. Persistent inflammation post-sepsis is associated with increased risk for rehospitalization and death. As surrogate markers of inflammation, complete blood count parameters measured at hospital discharge may have prognostic value for sepsis survivors.

Objective

To determine the incremental value of complete blood count parameters over clinical characteristics for predicting 90-day outcomes in sepsis survivors.

Methods

Electronic health record data was used to identify sepsis hospitalizations at United States Veterans Affairs hospitals with live discharge and relevant laboratory data (2013 to 2018). We measured the association of eight complete blood count parameters with 90-day outcomes (mortality, rehospitalization, cause-specific rehospitalizations) using multivariable logistic regression models.

Measurements and main results

We identified 155,988 eligible hospitalizations for sepsis. Anemia (93.6%, N=142,162) and lymphopenia (28.1%, N=29,365) were the most common blood count abnormalities at discharge. In multivariable models, all parameters were associated with the primary outcome of 90-day mortality or rehospitalization and improved model discrimination above clinical characteristics alone (likelihood ratio test, p<0.02 for all). A model including all eight parameters significantly improved discrimination (AUROC, 0.6929 v. 0.6756) and reduced calibration error for the primary outcome. Hemoglobin had the greatest prognostic separation with a 1.5 fold increased incidence of the primary outcome in the lowest quintile (7.2-8.9 g/dL) versus highest quintile (12.70-15.80 g/dL). Hemoglobin and neutrophil lymphocyte ratio provided the most added value in predicting the primary outcome and 90-day mortality alone, respectively. Absolute lymphocyte count added little value in predicting 90-day outcomes.

Conclusions

The incorporation of discharge complete blood count parameters into prognostic scoring systems could improve prediction of 90-day outcomes. Hemoglobin had the greatest prognostic value for the primary composite outcome of 90-day rehospitalization or mortality. Absolute lymphocyte count provided little added value in multivariable model comparisons, including for infection- or sepsis-related rehospitalization.

Prognostic significance of early platelet dynamics in Staphylococcus aureus bacteremia

BACKGROUND

Platelets are recognized as key immune effectors, but they are targets of bacterial virulence factors. In the present study, we aimed to examine the relationship between early platelet dynamics and the outcome of Staphylococcus aureus bacteremia (SAB).

METHOD

Electronic medical records of adult patients hospitalized for SAB between July 2012 and November 2020 were retrospectively reviewed for relevant demographic, laboratory, and clinical data. The outcome endpoints were mortality and microbial persistence.

RESULTS

Among the 811 patients evaluated, 29% experienced thrombocytopenia on Day 1. Platelet count nadir occurred on Days 2-3 following SAB onset, and Day 4 was a determining point of platelet count trajectory and mortality. Mortality risk was 6% or less for those with normal platelet count by Day 4 regardless of whether they experienced thrombocytopenia on Day 1, but the risk increased to 16-21% for those who experienced thrombocytopenia on Day 4 regardless of whether they had normal platelet count on Day 1 or sustained thrombocytopenia. The duration of bacteremia was prolonged by one day (median 3 d vs. 2 d) for those with sustained thrombocytopenia compared to those without.

CONCLUSION

Early platelet dynamics during SAB have prognostic significance and represent an early window for potential platelet-directed therapeutic interventions to improve outcome.

Sepsis associated acute kidney injury in pediatric intensive care unit

BACKGROUND

We aimed to compare the acute kidney injury (AKI) incidence in pediatric septic shock patients according to the three different classifications.

METHODS

We analyzed retrospectively 52 patients with severe sepsis between January 2019 and December 2019.

RESULTS

While 21 patients have been diagnosed with SA-AKI according to the pRIFLE criteria, 20 children have been diagnosed according to the AKIN criteria, and 21 children have been diagnosed according to the KDIGO criteria. Older age, lower platelet count were determined as independently risk factor for SA-AKI. Older age and higher PRISM score were associated with mortality. According to Canonical correlation coefficients, pRIFLE is the most successful classification to distinguish AKI state. The canonical correlation coefficients for pRIFLE, KDIGO, and AKIN were 0.817, 0.648, and 0.615, respectively.

CONCLUSION

Although AKI incidence was similar between the three classifications, pRIFLE was the most successful classification to distinguish AKI state.

Myeloid miR-155 plays a limited role in antibacterial defense during Klebsiella-derived pneumosepsis and is dispensable for lipopolysaccharide- or Klebsiella-induced inflammation in mice

MicroRNA-155 (miR-155) plays a crucial role in regulating host inflammatory responses during bacterial infection. Previous studies have shown that constitutive miR-155 deficiency alleviates inflammation while having varying effects in different bacterial infection models. However, whether miR-155 in myeloid cells is involved in the regulation of inflammatory and antibacterial responses is largely elusive. Mice with myeloid cell specific miR-155 deficiency were generated to study the in vitro response of bone marrow-derived macrophages (BMDMs), alveolar macrophages (AMs) and peritoneal macrophages (PMs) to lipopolysaccharide (LPS), and the in vivo response after intranasal or intraperitoneal challenge with LPS or infection with Klebsiella (K.) pneumoniae via the airways. MiR-155-deficient macrophages released less inflammatory cytokines than control macrophages upon stimulation with LPS in vitro. However, the in vivo inflammatory cytokine response to LPS or K. pneumoniae was not affected by myeloid miR-155 deficiency. Moreover, bacterial outgrowth in the lungs was not altered in myeloid miR-155-deficient mice, but Klebsiella loads in the liver of these mice were significantly higher than in control mice. These data argue against a major role for myeloid miR-155 in host inflammatory responses during LPS-induced inflammation and K. pneumoniae-induced pneumosepsis but suggest that myeloid miR-155 contributes to host defense against Klebsiella infection in the liver.

Communication from the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis on sepsis-induced coagulopathy in the management of sepsis

Disseminated intravascular coagulation (DIC) is a life-threatening complication in sepsis and other critical conditions. The International Society on Thrombosis and Haemostasis (ISTH) released the diagnostic criteria for overt DIC in 2001. Since then, ISTH overt DIC has been used as the global standard criterion for a decompensated stage of DIC. Because detecting an earlier stage of DIC would be useful for therapeutic considerations, the scientific standardization committees of the ISTH introduced the sepsis-induced coagulopathy (SIC) scoring system in 2019. The SIC scoring system is specifically designed to detect the compensated phase of DIC in sepsis, which can lead to overt DIC with disease progression. Studies examining the performance of the SIC scoring system have reported its usefulness over the past 5 years. The reported incidence of SIC was approximately 60% in patients with sepsis, which was twice as much as that of overt DIC. Almost all patients with overt DIC were diagnosed with SIC earlier. The reported mortality of SIC was ≥30% and, thus, can be used for patient selection for anticoagulant therapy. Despite the limited data, some continue to suggest the potential efficacy of anticoagulant therapy in patients with SIC. Although heparin, antithrombin, and thrombomodulin are the candidates for anticoagulation, none of them have proven to be effective with robust evidence, and future trials are warranted.

Use of full blood count parameters and haematology cell ratios in screening for sepsis in South Africa

Background

Sepsis is characterised by multi-organ failure due to an uncontrolled immune response to infection. Sepsis prevalence is increased in developing countries and requires prompt diagnosis and treatment. Reports, although controversial, suggest that full blood count parameters and cell ratios could assist in the early screening for sepsis.

Objective

The study evaluated the use of haematological cell ratios in screening for sepsis in a South African population.

Methods

The study retrospectively analysed the complete blood counts, blood cultures (BC) and biochemical test results of 125 adult patients who presented between January 2021 and July 2021 at a hospital in Cape Town. An ISO15189-accredited laboratory performed all of the tests. We compared and correlated the automated differential counts, neutrophil, monocyte and platelet-to-lymphocyte ratios with procalcitonin levels. A p-value of < 0.05 was considered significant.

Results

Sixty-two sepsis patients (procalcitonin > 2 ng/L and positive BC) were identified and compared to 63 non-sepsis controls. All cell ratios were significantly elevated in sepsis patients (p < 0.001). However, the two groups had no significant difference in absolute monocyte counts (p = 0.377). In addition, no correlation was detected between any cell ratios and procalcitonin.

Conclusion

In combination with complete blood count parameters, haematology cell ratios can be used for early sepsis detection. The full blood count is widely available, inexpensive, and routinely requested by emergency care clinicians. Although procalcitonin and BC remain the gold standard, the calculation of cell ratios could provide a simple screening tool for the early detection of sepsis.

What this study adds

This study adds evidence to the proposal that calculating haematological cell ratios assists in the early screening of sepsis in a South African setting.

Association between age and the host response in critically ill patients with sepsis

BACKGROUND

The association of ageing with increased sepsis mortality is well established. Nonetheless, current investigations on the influence of age on host response aberrations are largely limited to plasma cytokine levels while neglecting other pathophysiological sepsis domains like endothelial cell activation and function, and coagulation activation. The primary objective of this study was to gain insight into the association of ageing with aberrations in key host response pathways and blood transcriptomes in sepsis.

METHODS

We analysed the clinical outcome (n = 1952), 16 plasma biomarkers providing insight in deregulation of specific pathophysiological domains (n = 899), and blood leukocyte transcriptomes (n = 488) of sepsis patients stratified according to age decades. Blood transcriptome results were validated in an independent sepsis cohort and compared with healthy individuals.

RESULTS

Older age was associated with increased mortality independent of comorbidities and disease severity. Ageing was associated with lower endothelial cell activation and dysfunction, and similar inflammation and coagulation activation, despite higher disease severity scores. Blood leukocytes of patients ≥ 70 years, compared to patients < 50 years, showed decreased expression of genes involved in cytokine signaling, and innate and adaptive immunity, and increased expression of genes involved in hemostasis and endothelial cell activation. The diminished expression of gene pathways related to innate immunity and cytokine signaling in subjects ≥ 70 years was sepsis-induced, as healthy subjects ≥ 70 years showed enhanced expression of these pathways compared to healthy individuals < 50 years.

CONCLUSIONS

This study provides novel evidence that older age is associated with relatively mitigated sepsis-induced endothelial cell activation and dysfunction, and a blood leukocyte transcriptome signature indicating impaired innate immune and cytokine signaling. These data suggest that age should be considered in patient selection in future sepsis trials targeting the immune system and/or the endothelial cell response.

Extracellular vesicles participate in the pathogenesis of sepsis

Sepsis is one of the leading causes of mortality worldwide and is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. The early diagnosis and effective treatment of sepsis still face challenges due to its rapid progression, dynamic changes, and strong heterogeneity among different individuals. To develop novel strategies to control sepsis, a better understanding of the complex mechanisms of sepsis is vital. Extracellular vesicles (EVs) are membrane vesicles released from cells through different mechanisms. In the disease state, the number of EVs produced by activated or apoptotic cells and the cargoes they carry were altered. They regulated the function of local or distant host cells in autocrine or paracrine ways. Current studies have found that EVs are involved in the occurrence and development of sepsis through multiple pathways. In this review, we focus on changes in the cargoes of EVs in sepsis, the regulatory roles of EVs derived from host cells and bacteria, and how EVs are involved in multiple pathological processes and organ dysfunction in sepsis. Overall, EVs have great application prospects in sepsis, such as early diagnosis of sepsis, dynamic monitoring of disease, precise therapeutic targets, and prevention of sepsis as a vaccine platform.

Immunopathology of chronic critical illness in sepsis survivors: Role of abnormal myelopoiesis

Sepsis remains the single most common cause of mortality and morbidity in hospitalized patients requiring intensive care. Although earlier detection and improved treatment bundles have reduced in-hospital mortality, long-term recovery remains dismal. Sepsis survivors who experience chronic critical illness often demonstrate persistent inflammation, immune suppression, lean tissue wasting, and physical and functional cognitive declines, which often last in excess of 1 year. Older patients and those with preexisting comorbidities may never fully recover and have increased mortality compared with individuals who restore their immunologic homeostasis. Many of these responses are shared with individuals with advanced cancer, active autoimmune diseases, chronic obstructive pulmonary disease, and chronic renal disease. Here, we propose that this resulting immunologic endotype is secondary to a persistent maladaptive reprioritization of myelopoiesis and pathologic activation of myeloid cells. Driven in part by the continuing release of endogenous alarmins from chronic organ injury and muscle wasting, as well as by secondary opportunistic infections, ongoing myelopoiesis at the expense of lymphopoiesis and erythropoiesis leads to anemia, recurring infections, and lean tissue wasting. Early recognition and intervention are required to interrupt this pathologic activation of myeloid populations.

Acute Kidney Injury and Hemolytic Uremic Syndrome in Severe Pneumococcal Pneumonia—A Retrospective Analysis in Pediatric Intensive Care Unit

Objectives: This study aimed to evaluate the prevalence of acute kidney injury (AKI) and hemolytic uremic syndrome (HUS) in severe pediatric pneumonia due to Streptococcus pneumoniae and to identify factors associated with AKI and HUS in these patients.

Methods: We retrospectively analyzed pediatric patients who were admitted to our pediatric intensive care unit due to severe pneumococcal pneumonia between 2013 and 2019.

Results: Forty-two patients with a median age of 4.3 years were included. Among these patients, 14 (33.3%) developed AKI, including seven (16.7%) stage 1, two (4.8%) stage 2, and five (11.9%) stage 3 AKI. Features of HUS were present in all of the patients with stage 3 AKI, and four required renal replacement therapy (RRT), with a median duration of 10.5 days (range 3 to 16 days). All patients with HUS required mechanical ventilation and inotropic supports. Patients with lower leukocyte and platelet counts, serum sodium and bicarbonate levels, positive urine dipstick (heme or protein ≥ 2 + ), and presence of bacteremia were associated with stage 2 and 3 AKI.

Conclusions: Pediatricians should be aware of the relatively high prevalence of kidney involvement in severe pneumococcal pneumonia, with one-third having AKI and 11.9% developing HUS. Majority (80%) of HUS patients required RRT. Positive urine dipstick, serum sodium, and bicarbonate at presentation, which can be measured in point-of-care tests, may potentially be useful as quick tests to stratify the risks of moderate-to-severe AKI.

RISK OF HOSPITAL MORTALITY IN CRITICALLY ILL PATIENTS WITH TRANSIENT AND PERSISTENT THROMBOCYTOPENIA: A RETROSPECTIVE STUDY

ABSTRACT

Background: Thrombocytopenia (TP), a common occurrence among patients admitted to the intensive care unit (ICU), is significantly associated with prolonged ventilator use, prolonged ICU stay, and increased mortality. The duration of TP serves as an indicator of patient outcome, although the exact duration of TP associated with poor patient outcome remains unclear. In this study, the data of 3,291 patients on their first admission to the ICU between January 2010 and December 2020 were retrospectively analyzed. Participants were divided into the no TP, TP 1-2 days, TP 3-6 days, and TP ≥7 days groups based on the duration of TP. External validation was performed using the Medical Information Mart for Intensive Care III data set. Results: A longer duration of TP was significantly associated with high volume of transfusion and high hospital mortality ( P < 0.01), and 37.3% of the participants developed TP during their ICU stay. The results of Kaplan-Meier survival analysis and Cox regression analysis after excluding the effects of patients who died shortly after ICU admission revealed the absence of significant differences between the no TP and TP 1-2 days groups ( P > 0.05). However, when the duration of TP exceeded 2 days, patient mortality increased with an increase in the duration of TP ( P < 0.01). Similar findings were obtained with the Medical Information Mart for Intensive Care III data set. Conclusions: The duration of TP in critically ill patients is positively correlated with poor patient outcome. We classified TP as either transient TP or persistent TP based on a cutoff duration of 2 days. Monitoring the duration of TP may aid in the prediction of patients' outcome in the ICU.

Occurrence and role of lung megakaryocytes in infection and inflammation

Megakaryocytes (MKs) are large cells giving rise to platelets. It is well established that in adults, MKs develop from hematopoietic stem cells and reside in the bone marrow. MKs are also rare but normal constituents of the venous blood returning to the lungs, and MKs are found in the lung vasculature (MK_circ), suggesting that these cells are migrants from the bone marrow and get trapped in lung capillaries where the final steps of platelet production can occur. An unprecedented increase in the number of lung and circulating MKs was described in coronavirus disease 2019 (COVID-19) patients, suggesting that lung thrombopoiesis may be increased during lung infection and/or thromboinflammation. In addition to the population of platelet-producing intravascular MKs in the lung, a population of lung-resident megakaryocytes (MK_L) has been identified and presents a specific immune signature compared to its bone marrow counterparts. Recent single-cell analysis and intravital imaging have helped us gain a better understanding of these populations in mouse and human. This review aims at summarizing the recent data on increased occurrence of lung MKs and discusses their origin, specificities, and potential role in homeostasis and inflammatory and infectious lung diseases. Here, we address remaining questions, controversies, and methodologic challenges for further studies of both MK_circ and MK_L.

Recombinant human thrombopoietin treatment in patients with chronic liver disease-related thrombocytopenia undergoing invasive procedures: A retrospective study

BACKGROUND

Chronic liver disease (CLD) related thrombocytopenia increases the risk of bleeding and poor prognosis. Many liver disease patients require invasive procedures or surgeries, such as liver biopsy or endoscopic variceal ligation, and most of them have lower platelet counts, which could aggravate the risk of bleeding due to liver dysfunction and coagulation disorders. Unfortunately, there is no defined treatment modality for CLD-induced thrombocytopenia. Recombinant human thrombopoietin (rhTPO) is commonly used to treat primary immune thrombocytopenic purpura and thrombocytopenia caused by solid tumor chemotherapy; however, there are few reports on the use of rhTPO in the treatment of CLD-related thrombocytopenia.

AIM

To evaluate the efficacy of rhTPO in the treatment of patients with CLD-associated thrombocytopenia undergoing invasive procedures.

METHODS

All analyses were based on the retrospective collection of clinical data of patients with CLD who were treated in the Department of Infectious Diseases at The First Affiliated Hospital of Soochow University between June 2020 and December 2021. Fifty-nine male and 41 female patients with liver disease were enrolled in this study to assess the changes in platelet counts and parameters before and after the use of rhTPO for thrombocytopenia. Adverse events related to treatment, such as bleeding, thrombosis, and disseminated intravascular coagulation, were also investigated.

RESULTS

Among the enrolled patients, 78 (78%) showed a platelet count increase after rhTPO use, while 22 (22%) showed no significant change in platelet count. The mean platelet count after rhTPO treatment in all patients was 101.53 ± 81.81 × 10⁹/L, which was significantly improved compared to that at baseline (42.88 ± 16.72 × 10⁹/L), and this difference was statistically significant (P < 0.001). In addition, patients were further divided into three subgroups according to their baseline platelet counts (< 30 × 10⁹/L, 30-50 × 10⁹/L, > 50 × 10⁹/L). Subgroup analyses showed that the median platelet counts after treatment were significantly higher (P < 0.001, all). Ninety (90%) patients did not require platelet transfusion partially due to an increase in platelet count after treatment with rhTPO. No serious adverse events related to rhTPO treatment were observed. Overall, rhTPO demonstrated good clinical efficacy for treating CLD-associated thrombocytopenia.

CONCLUSION

rhTPO can improve platelet count, reduce the risk of bleeding, and decrease the platelet transfusion rate, which may promote the safety of invasive procedures and improve overall survival of patients with CLD.