Is there value in plasma cytokine measurements in patients with severe trauma and sepsis?

Immune profile of patients‑a new approach in management of sepsis and septic shock?

The present study was a prospective observational single center study, enrolling 102 patients with sepsis, admitted in the Intensive Care Unit of the County Emergency Clinical Hospital in Târgu Mureș (Mureș, Romania). The main goal of the present study was to compare the changes of the following parameters on day 1 compared with day 5, in sepsis compared with septic shock, as well as in survivors compared with non-survivors: Cell blood count parameters, neutrophil-lymphocyte ratio, platelet-lymphocyte ratio and systemic inflammation index, C reactive protein (CRP), ferritin, procalcitonin (PCT), CD 3+ T cells, CD4+ T cells, CD8+ T cells, CD16+CD56+/CD3-NK cells and CD19+ B cells. The relationship between the subcategories of lymphocytes with the inflammatory markers was evaluated. The serum concentration of CRP and PCT was significantly lower on day 5 compared with day 1 and serum ferritin was significantly higher in patients with septic shock. The percentage of cytotoxic T lymphocytes was significantly decreased and the percentage of NK lymphocytes was significantly increased in patients who developed septic shock. The results indicated a negative significant correlation between the proportion of T lymphocytes and PCT concentration and a positive significant correlation between the proportion of B lymphocytes and PCT concentration.

The value of NSE to predict ICU mortality in patients with septic shock: A prospective observational study

To investigate the predictive value of neuron-specific enolase (NSE) on intensive care unit (ICU) mortality in patients with septic shock. Seventy-five patients with septic shock hospitalized in the emergency intensive care unit (EICU) of Hebei General Hospital from March 2020 to September 2021 were included, and the patients' baseline characteristics and laboratory findings were collected. NSE levels on the first and fourth days after admission were retrieved. NSE% [(NSEday1 - NSEday4)/NSEday1 × 100%] and δNSE (NSEday1 - NSEday4) were calculated. The outcome indicator was ICU mortality. The patients were divided into the survivors group (n = 57) and the nonsurvivors group (n = 18). Multivariate analysis was performed to assess the relationship between NSE and ICU mortality. The predictive value of NSE was evaluated using receiver operating characteristic (ROC) curve. There were no significant differences in age, gender, systolic blood pressure (SBP), heart rate (HR), acute physiology and chronic health evaluation II score (APACHE II score), source of infection, and comorbidities between the 2 groups (all P > .05). Interleukin-6 (IL-6), NSE (day1), and NSE (day4) were significantly higher in patients in the nonsurvivors group (all P < .05), and there were no statistical differences in other laboratory tests between the 2 groups (all P > .05). APACHE II score, IL-6, lactate (Lac), total bilirubin (TBil), NSE (day1), and NSE (day4) showed a weak positive correlation with ICU mortality in patients with septic shock (all P < .05). Multivariate logistic regression analysis demonstrated that APACHE II score (odds ratio [OR] = 1.166, 95% confidence interval [95% confidence interval [CI]] 1.005-1.352, P = .042), IL-6 (OR = 1.001, 95% CI 1.000-1.001, P = .003) and NSE (day4) (OR = 1.099, 95% CI 1.027-1.176, P = .006) were independently associated with the ICU mortality of sepsis shock patients. The area under the curve (AUCs) of APACHE II score, IL-6, NSE (day1), and NSE (day4) for predicting prognosis were 0.650, 0.694, 0.758 and 0.770, respectively (all P < .05). NSE(day4) displayed good sensitivity and specificity (Sn = 61.11%, Sp = 91.23%) for predicting ICU mortality with a cutoff value of 25.94 ug/L. High-level NSE (day4) is an independent predictor of ICU mortality in sepsis shock patients, which may become a good alternate option for evaluating sepsis severity. More extensive studies are needed in the future to demonstrate the prognosis value of NSE.

Biomarkers of sepsis in pigs, horses and cattle: from acute phase proteins to procalcitonin

Sepsis is a complex clinical syndrome triggered by an inflammatory host response to an infection. It is usually complicated to detect and diagnose, and has severe consequences in human and veterinary health, especially when treatment is not started early. Therefore, efforts to detect sepsis accurately are needed. In addition, its proper diagnosis could reduce the misuse of antibiotics, which is essential fighting against antimicrobial resistance. This case is a particular issue in farm animals, as antibiotics have been traditionally given massively, but now they are becoming increasingly restricted. When sepsis is suspected in animals, the most frequently used biomarkers are acute phase proteins such as C-reactive protein, serum amyloid A and haptoglobin, but their concentrations can increase in other inflammatory conditions. In human patients, the most promising biomarkers to detect sepsis are currently procalcitonin and presepsin, and there is a wide range of other biomarkers under study. However, there is little information on the application of these biomarkers in veterinary species. This review aims to describe the general concepts of sepsis and the current knowledge about the biomarkers of sepsis in pigs, horses, and cattle and to discuss possible advances in the field.

Characterization of Early Peripheral Immune Responses in Patients with Sepsis and Septic Shock

(1) Background: Sepsis is a life-threatening condition caused by an abnormal host response to infection that produces altered physiological responses causing tissue damage and can result in organ dysfunction and, in some cases, death. Although sepsis is characterized by a malfunction of the immune system leading to an altered immune response and immunosuppression, the high complexity of the pathophysiology of sepsis requires further investigation to characterize the immune response in sepsis and septic shock. (2) Methods: This study analyzes the immune-related responses occurring during the early stages of sepsis by comparing the amounts of cytokines, immune modulators and other endothelial mediators of a control group and three types of severe patients: critically ill non-septic patients, septic and septic shock patients. (3) Results: We showed that in the early stages of sepsis the innate immune system attempts to counteract infection, probably via neutrophils. Conversely, the adaptive immune system is not yet fully activated, either in septic or in septic shock patients. In addition, immunosuppressive responses and pro-coagulation signals are active in patients with septic shock. (4) Conclusions: The highest levels of IL-6 and pyroptosis-related cytokines (IL-18 and IL-1α) were found in septic shock patients, which correlated with D-dimer. Moreover, endothelial function may be affected as shown by the overexpression of adhesion molecules such as s-ICAM1 and E-Selectin during septic shock.

Absence of Stress Hyperglycemia Indicates the Most Severe Form of Blunt Liver Trauma

Background: Stress hyperglycemia is common in trauma patients. Increasing injury severity and hemorrhage trigger hepatic gluconeogenesis, glycogenolysis, peripheral and hepatic insulin resistance. Consequently, we expect glucose levels to rise with injury severity in liver, kidney and spleen injuries. In contrast, we hypothesized that in the most severe form of blunt liver injury, stress hyperglycemia may be absent despite critical injury and hemorrhage. Methods: All patients with documented liver, kidney or spleen injuries, treated at a university hospital between 2000 and 2020 were charted. Demographic, laboratory, radiological, surgical and other data were analyzed. Results: A total of 772 patients were included. In liver (n = 456), spleen (n = 375) and kidney (n = 152) trauma, an increase in injury severity past moderate to severe (according to the American Association for the Surgery of Trauma, AAST III-IV) was associated with a concomitant rise in blood glucose levels independent of the affected organ. While stress-induced hyperglycemia was even more pronounced in the most severe forms (AAST V) of spleen (median 10.7 mmol/L, p < 0.0001) and kidney injuries (median 10.6 mmol/L, p = 0.004), it was absent in AAST V liver injuries, where median blood glucose level even fell (5.6 mmol/L, p < 0.0001). Conclusions: Absence of stress hyperglycemia on hospital admission could be a sign of most severe liver injury (AAST V). Blood glucose should be considered an additional diagnostic criterion for grading liver injury.

Acute overventilation does not cause lung damage in moderately hemorrhaged swine

Airway management is important in trauma and critically ill patients. Prolonged mechanical ventilation results in overventilation-induced lung barotrauma, but few studies have examined the consequence of acute (1 h or less) overventilation. We hypothesized that acute hyperventilation, as might inadvertently be performed in prehospital settings, would elevate systemic inflammation and cause lung damage. Female Yorkshire pigs (40-50 kg, n = 10/group) were anesthetized, instrumented for hemodynamic measurements and blood sampling, and underwent a 25% controlled hemorrhage followed by 1 h of 1) spontaneous breathing, 2) "normal" bag ventilation (4.8 L·min volume, ∼400 mL tidal volume, 12 breaths/minute), 3) bag hyperventilation (9 L·min volume, ∼750 mL tidal volume, 12 breaths/minute), 4) maximum hyperventilation (15 L·min volume, ∼750 mL tidal volume, 20 breaths/minute), or 5) mechanical ventilation. Pigs then regained consciousness and recovered for 24 h, followed by euthanasia and collection of blood and tissue samples. No level of manual ventilation had any significant impact on hemodynamic variables. Blood markers of tissue damage and plasma cytokines were not statistically different between groups with the exception of a transient increase in IL-1β; all values returned to baseline by 24 h. On pathological review, severity and distribution of lung edema or other gross pathologies were not significantly different between groups. These data indicate hyperventilation causes no adverse effects, to include inflammation and tissue damage, and that acute overventilation, as could be seen in the prehospital phase of trauma care, does not produce evidence of adverse effects on the lungs following moderate hemorrhage.NEW & NOTEWORTHY Appropriate airway management is essential in trauma and critically ill patients. Prolonged mechanical ventilation can result in overventilation-induced lung barotrauma, but few studies have examined the consequence of acute overventilation. We investigated the outcome of hemorrhage followed by 1 h of overventilation in swine. We found that acute overventilation, as could be seen in the prehospital phase of trauma care, does not produce evidence of adverse effects on otherwise healthy lungs following moderate hemorrhage.

Analysis of Inflammatory Mediator Profiles in Sepsis Patients Reveals That Extracellular Histones Are Strongly Elevated in Nonsurvivors

The timely recognition of sepsis and the prediction of its clinical course are challenging due to the complex molecular mechanisms leading to organ failure and to the heterogeneity of sepsis patients. Treatment strategies relying on a “one-fits-all” approach have failed to reduce mortality, suggesting that therapeutic targets differ between patient subgroups and highlighting the need for accurate analysis of the molecular cascades to assess the highly variable host response. Here, we characterized a panel of 44 inflammatory mediators, including cytokines, chemokines, damage-associated molecular patterns, and coagulation-related factors, as well as markers of endothelial activation in 30 patients suffering from renal failure in the course of sepsis. All patients received continuous veno-venous hemodialysis with either high cut-off filters or with standard filters, and mediators were quantified for all patients at the initiation of dialysis and after 24 h and 48 h. Mediator concentrations in individual patients ranged widely, demonstrating the heterogeneity of sepsis patients. None of the mediators correlated with SAPS III or TISS scores. The overall in-hospital mortality of the study population was 56.7% (57.1% vs. 56.3% for high cut-off vs. standard filter). The two filter groups differed regarding most of the mediator levels at baseline, prohibiting conclusions regarding the effect of standard filters versus high cut-off filters on mediator depletion. The elevation and correlation of damage-associated molecular patterns and markers of endothelial activation gave evidence of severe tissue damage. In particular, extracellular histones were strongly increased and were almost 30-fold higher in nonsurvivors as compared to survivors, indicating their diagnostic and prognostic potential.

Bacterial virulence plays a crucial role in MRSA sepsis

Bacterial sepsis is a major global cause of death. However, the pathophysiology of sepsis has remained poorly understood. In industrialized nations, Staphylococcus aureus represents the pathogen most commonly associated with mortality due to sepsis. Because of the alarming spread of antibiotic resistance, anti-virulence strategies are often proposed to treat staphylococcal sepsis. However, we do not yet completely understand if and how bacterial virulence contributes to sepsis, which is vital for a thorough assessment of such strategies. We here examined the role of virulence and quorum-sensing regulation in mouse and rabbit models of sepsis caused by methicillin-resistant S. aureus (MRSA). We determined that leukopenia was a predictor of disease outcome during an early critical stage of sepsis. Furthermore, in device-associated infection as the most frequent type of staphylococcal blood infection, quorum-sensing deficiency resulted in significantly higher mortality. Our findings give important guidance regarding anti-virulence drug development strategies for the treatment of staphylococcal sepsis. Moreover, they considerably add to our understanding of how bacterial sepsis develops by revealing a critical early stage of infection during which the battle between bacteria and leukocytes determines sepsis outcome. While sepsis has traditionally been attributed mainly to host factors, our study highlights a key role of the invading pathogen and its virulence mechanisms.

Potential mechanisms of tumor progression associated with postoperative infectious complications

There is increasing evidence that postoperative infectious complications (PICs) are associated with poor prognosis after potentially curative surgery. However, the role that PICs play in tumor development remains unclear. In this article, we reviewed the literature for novel insights on the mechanisms of cancer progression associated with PICs. The Medline and EMBASE databases were searched for publications regarding the role of suppression of antitumor immunity by PIC in tumor progression and selected 916 manuscripts were selected for this review. In addition, a summary of the authors' own experimental data from this field was set in the context of current knowledge regarding cancer progression under septic conditions. Initially, sepsis/microbial infection dramatically activates the systemic immune system with increases in pro-inflammatory mediators, which results in the development of systemic inflammatory response syndrome; however, when sepsis persists in septic patients, a shift toward an anti-inflammatory immunosuppressive state, characterized by macrophage deactivation, reduced antigen presentation, T cell anergy, and a shift in the T helper cell pattern to a predominantly TH2-type response, occurs. Thus, various cytokine reactions and the immune status dynamically change during microbial infection, including PIC. We proposed three possible mechanisms for the tumor progression associated with PIC: first, a mechanism in which microbes and/or microbial PAMPs may be directly involved in cancer growth; second, a mechanism in which factors released from immunocompetent cells during infections may affect tumor progression; and third, a mechanism in which factors suppress host tumor immunity during infections, which may result in tumor progression. A more detailed understanding by surgeons of the immunological features in cancer patients with PIC can subsequently open new avenues for improving unfavorable long-term oncological outcomes associated with PICs.

A Whole Blood Enzyme-Linked Immunospot Assay for Functional Immune Endotyping of Septic Patients

Sepsis initiates simultaneous pro- and anti-inflammatory processes, the pattern and intensity of which vary over time. The inability to evaluate the immune status of patients with sepsis in a rapid and quantifiable manner has undoubtedly been a major reason for the failure of many therapeutic trials. Although there has been considerable effort to immunophenotype septic patients, these methods have often not accurately assessed the functional state of host immunity, lack dynamic range, and are more reflective of molecular processes rather than host immunity. In contrast, ELISpot assay measures the number and intensity of cytokine-secreting cells and has excellent dynamic range with rapid turnaround. We investigated the ability of a (to our knowledge) novel whole blood ELISpot assay and compared it with a more traditional ELISpot assay using PBMCs in sepsis. IFN-γ and TNF-α ELISpot assays on whole blood and PBMCs were undertaken in control, critically ill nonseptic, and septic patients. Whole blood ELISpot was easy to perform, and results were generally comparable to PBMC-based ELISpot. However, the whole blood ELISpot assay revealed that nonmonocyte, myeloid populations are a significant source of ex vivo TNF-α production. Septic patients who died had early, profound, and sustained suppression of innate and adaptive immunity. A cohort of septic patients had increased cytokine production compared with controls consistent with either an appropriate or excessive immune response. IL-7 restored ex vivo IFN-γ production in septic patients. The whole blood ELISpot assay offers a significant advance in the ability to immunophenotype patients with sepsis and to guide potential new immunotherapies.

Animal-Free Human Whole Blood Sepsis Model to Study Changes in Innate Immunity

Studying innate immunity in humans is crucial for understanding its role in the pathophysiology of systemic inflammation, particularly in the complex setting of sepsis. Therefore, we standardized a step-by-step process from the venipuncture to the transfer in a human model system, while closely monitoring the inflammatory response for up to three hours. We designed an animal-free, human whole blood sepsis model using a commercially available, simple to use, tubing system. First, we analyzed routine clinical parameters, including cell count and blood gas analysis. Second, we demonstrated that extracellular activation markers (e.g., CD11b and CD62l) as well as intracellular metabolic (intracellular pH) and functional (generation of radical oxygen species) features remained stable after incubation in the whole blood model. Third, we mimicked systemic inflammation during early sepsis by exposure of whole blood to pathogen-associated molecular patterns. Stimulation with lipopolysaccharide revealed the capability of the model system to evoke a sepsis-like inflammatory phenotype of innate immunity. In summary, the presented model serves as a convenient, economic, and reliable platform to study innate immunity in human whole blood, which may yield clinically important insights.

Immunopathophysiology of trauma-related acute kidney injury

Physical trauma can affect any individual and is globally accountable for more than one in every ten deaths. Although direct severe kidney trauma is relatively infrequent, extrarenal tissue trauma frequently results in the development of acute kidney injury (AKI). Various causes, including haemorrhagic shock, rhabdomyolysis, use of nephrotoxic drugs and infectious complications, can trigger and exacerbate trauma-related AKI (TRAKI), particularly in the presence of pre-existing or trauma-specific risk factors. Injured, hypoxic and ischaemic tissues expose the organism to damage-associated and pathogen-associated molecular patterns, and oxidative stress, all of which initiate a complex immunopathophysiological response that results in macrocirculatory and microcirculatory disturbances in the kidney, and functional impairment. The simultaneous activation of components of innate immunity, including leukocytes, coagulation factors and complement proteins, drives kidney inflammation, glomerular and tubular damage, and breakdown of the blood-urine barrier. This immune response is also an integral part of the intense post-trauma crosstalk between the kidneys, the nervous system and other organs, which aggravates multi-organ dysfunction. Necessary lifesaving procedures used in trauma management might have ambivalent effects as they stabilize injured tissue and organs while simultaneously exacerbating kidney injury. Consequently, only a small number of pathophysiological and immunomodulatory therapeutic targets for TRAKI prevention have been proposed and evaluated.

Medicina de precisión en sepsis: utilidad de los biomarcadores en pacientes biomarcadores en pacientes críticamente enfermos

Durante años la evolución del cuidado intensivo ha intentado ofrecer una atención basada en protocolos y paquetes de manejo agrupados por patologías y cuadro sindromáticos. Aunque se logró disminuir la mortalidad en diferentes patologías (sepsis y síndromes coronario agudo y de distrés respiratorio agudo), no se han resuelto por completo los problemas clínicos, en especial el diagnóstico y el manejo. Una nueva opción ha surgido en el horizonte denominada “medicina de precisión”, entendida como estrategia de prevención y tratamiento que tiene en cuenta la variabilidad individual. La sepsis es un síndrome con múltiples aristas en cuanto al fenotipo y genotipo, cuyo diagnóstico temprano es relevante para los desenlaces clínicos. Hasta el momento el enfoque principal ha sido la identificación de un germen etiológico para diferenciarla del síndrome de respuesta inflamatoria sistémica (SIRS). En los últimos años el paradigma en enfermedades infecciosas ha cambiado debido a estudios que demuestran como la respuesta inmunitaria del paciente séptico tiene un papel clave en el desarrollo de la enfermedad, con implicaciones en el diagnóstico, pronóstico y tratamiento, que podrían ayudar a cambiar el abordaje en los próximos años gracias a una estrategia basada en medicina de precisión. Hoy los aislamientos microbiológicos y los cultivos siguen siendo el estándar de referencia con varias desventajas como el tiempo para obtener resultados, sobre todo en infecciones por gérmenes resistentes u hongos, que pueden retrasar el inicio de la terapia antimicrobiana. Como alternativa se ha planteado el uso de biomarcadores en sepsis que siendo productos de la respuesta inflamatoria del individuo ante la infección, son útiles para el diagnóstico y pronóstico primordialmente en los críticamente enfermos. Decidimos realizar esta revisión narrativa acerca de la utilidad de los biomarcadores en pacientes con sepsis críticamente enfermos, para enfocarlos en un modelo de medicina personalizada.

Soluble tumour necrosis factor receptor I is a promising early indicator of complicated clinical outcome in patients following severe trauma

Post-traumatic mortality rates are still very high and show an increasing tendency. Early identification of patients at high risk of severe complications has a significant impact on treatment outcomes. The aim of the study was to better understand the early pathological inflammatory response to injury and infection, and to determine the usefulness of the assessment of TNF-α and sTNFR1 concentrations in the peripheral blood as early indicators of severe post-traumatic complications. The study was carried out in a group of 51 patients after trauma, treated in the ED, including 32 patients who met the inclusion criteria for immunological analysis. Patients were divided into two groups using the ISS scale (A ISS ≥ 20, B ISS < 20). The highest TNF-α and sTNFR1 concentrations in both groups were recorded at admission and were significantly higher in group A compared to group B (A vs. B TNF-α 2.46 pg/ml vs. 1.78 pg/ml; sTNFR1 1667.5 pg/ml vs. 875.2 p < 0.005). The concentration of sTNFR1 in patients with severe complications was significantly higher compared to patients without complications and preceded clinical symptoms of complications (C⁺ vs. C^– 1561.5 pg/ml vs. 930.6 pg/ml, p < 0,005). The high diagnostic sensitivity calculated from the ROC curves was found for the concentrations of both cytokines: TNF-α (AUC = 0.91, p = 0.004) and sTNFR1 (AUC = 0.86, p = 0.011). Elevated levels of sTNFR1, determined in the peripheral blood shortly after injury, are significantly associated with the occurrence of later complications, which in some patients lead to death. In contrast, high levels of TNF-α shortly after injury are associated with mortality.

Sodium Butyrate Ameliorates Intestinal Injury and Improves Survival in a Rat Model of Cecal Ligation and Puncture-Induced Sepsis

Sepsis is a life-threatening condition with a high rate of mortality. Unfortunately, very few therapies can improve outcomes in patients with sepsis. Butyrate, which is the most potent histone deacetylase (HDAC) inhibitor among short-chain fatty acids, exerts anti-inflammatory effects in a variety of inflammatory diseases. Butyrate might thus be valuable in the treatment of sepsis, in which inhibition of overwhelming cytokine release is vitally important. Sepsis was induced in 7- to 8-week-old Sprague-Dawley rats by cecal ligation and puncture (CLP) with a 21-g double-puncture technique. Rats received an intravenous injection of normal saline (vehicle) or sodium butyrate (200 mg/kg) after CLP and were sacrificed 12 h later. Hematoxylin and eosin staining was performed to observe the intestinal mucosal morphology. RT-PCR and ELISA were used to determine the intestinal inflammatory response in vivo. Intestinal permeability was evaluated by measuring fluorescein isothiocyanate dextran (FD-4) absorption in vivo, and tight junction protein expression was examined by western blot. NF-κB p65 activities were assessed by western blot and immunohistochemistry. Sodium butyrate treatment improved the survival rate of CLP rats and alleviated sepsis-induced intestinal mucosal injury. Proinflammatory cytokine expression was lower in butyrate-treated rats than in the vehicle group. FD-4 leakage from the intestinal tract was reduced, and the expression levels of the tight junction proteins claudin-1 and ZO-1 were also restored in rats that received sodium butyrate treatment. These effects were associated with less NF-κB p65 nuclear translocation, whereas the expression of Iκ-Bα was not affected or even increased. Sodium butyrate mitigates the inflammatory response and maintains intestinal barrier function in polymicrobial sepsis partly through inhibition of NF-κB activation and may serve as a novel therapy for sepsis.

Infection-induced innate antimicrobial response disorders: from signaling pathways and their modulation to selected biomarkers

Severe infections are a major public health problem responsible for about 40-65% of hospitalizations in intensive care units (ICU). The high mortality (30-50%) of persons diagnosed with severe infection is caused by largely unknown mechanisms of sepsis-induced immune system response. Severe infections with dynamic progress are accompanied with SIRS (systemic inflammatory reaction syndrome) and CARS (compensatory anti-inflammatory response syndrome), and require a biological treatment appropriate to the phase of immune response. The mechanisms responsible for severe infection related to immune system response particularly attract extensive interest of non-specific defense mechanisms, including signaling pathways of Toll-like receptors (mainly TLR4 and TLR2) that recognize distinct pathogen-associated molecular patterns (PAMP) and play a critical role in innate immune response. There are attempts of treatment, followed by blocking ligand binding with TLR or modulation of intracellular signaling pathways, to inhibit signal transduction. Moreover, researches regarding new and more efficient diagnostics biomarkers were mostly focused on indicators related to innate response to infection as well as connections of pro-inflammatory response with anti-inflammatory response.According to these studies, in case of ICU septic patients with high-risk of mortality, the solution for the problem will require mainly early immune and genetic diagnostics (e.g. cytokines, microRNA, cluster of differentiation-64 [CD64], triggering receptor expressed on myeloid cells-1 [TREM-1], and high mobility group box 1 protein [HMGB1]).

Cytokines in Inflammatory Disease

This review aims to briefly discuss a short list of a broad variety of inflammatory cytokines. Numerous studies have implicated that inflammatory cytokines exert important effects with regard to various inflammatory diseases, yet the reports on their specific roles are not always consistent. They can be used as biomarkers to indicate or monitor disease or its progress, and also may serve as clinically applicable parameters for therapies. Yet, their precise role is not always clearly defined. Thus, in this review, we focus on the existing literature dealing with the biology of cytokines interleukin (IL)-6, IL-1, IL-33, tumor necrosis factor-alpha (TNF-α), IL-10, and IL-8. We will briefly focus on the correlations and role of these inflammatory mediators in the genesis of inflammatory impacts (e.g., shock, trauma, immune dysregulation, osteoporosis, and/or critical illness).

A conceptual time window-based model for the early stratification of trauma patients

Progress in the testing of therapies targeting the immune response following trauma, a leading cause of morbidity and mortality worldwide, has been slow. We propose that the design of interventional trials in trauma would benefit from a scheme or platform that could support the identification and implementation of prognostic strategies for patient stratification. Here, we propose a stratification scheme based on defined time periods or windows following the traumatic event. This 'time-window' model allows for the incorporation of prognostic variables ranging from circulating biomarkers and clinical data to patient-specific information such as gene variants to predict adverse short- or long-term outcomes. A number of circulating biomarkers, including cell injury markers and damage-associated molecular patterns (DAMPs), and inflammatory mediators have been shown to correlate with adverse outcomes after trauma. Likewise, several single nucleotide polymorphisms (SNPs) associate with complications or death in trauma patients. This review summarizes the status of our understanding of the prognostic value of these classes of variables in predicting outcomes in trauma patients. Strategies for the incorporation of these prognostic variables into schemes designed to stratify trauma patients, such as our time-window model, are also discussed.

Endocrine-Metabolic Response in Patients Undergoing Multiple Body Contouring Surgeries After Massive Weight Loss

BACKGROUND

The endocrine-metabolic response to trauma is directly related to its magnitude, but little is known about the adverse effects of combined surgical procedures on morbidity.

OBJECTIVES

The authors sought to evaluate risk factors by measuring the endocrine-metabolic response in patients who underwent multiple body-contouring surgeries after massive weight loss.

METHODS

This prospective, randomized, interventional study included 46 massive weight loss patients who experienced a weight loss >30% of their body mass index (BMI) and were referred for body contouring surgery. Patients were randomly allocated to the control group (n = 10) or intervention group (n = 36), which in turn was divided into 3 subgroups (n = 12, each) according to BMI, surgical time, and scar length values. Blood samples were collected from all patients at different time points to assess biological stress markers.

RESULTS

Levels of IL-6 in patients in the higher ranges of BMI and operating time and with more extensive scar length were significantly higher in the immediate postoperative period compared with baseline. Concentrations of noradrenaline were significantly higher 24 hours after surgery compared with baseline only in patients in the higher range of operating time. A higher level of IL-6 at 72 hours after surgery compared with baseline was associated with more extensive scar length. Levels of other biological stress markers did not significantly differ.

CONCLUSIONS

The combination of surgical procedures did not significantly affect the concentrations of most biological stress markers. The variable of operating time most influenced increase in plasma concentrations of stress markers.

LEVEL OF EVIDENCE: 1

Plasma interleukin-6 concentration for the diagnosis of sepsis in critically ill adults

BACKGROUND

The definition of sepsis has evolved over time, along with the clinical and scientific knowledge behind it. For years, sepsis was defined as a systemic inflammatory response syndrome (SIRS) in the presence of a documented or suspected infection. At present, sepsis is defined as a life-threatening organ dysfunction resulting from a dysregulated host response to infection. Even though sepsis is one of the leading causes of mortality in critically ill patients, and the World Health Organization (WHO) recognizes it as a healthcare priority, it still lacks an accurate diagnostic test. Determining the accuracy of interleukin-6 (IL-6) concentrations in plasma, which is proposed as a new biomarker for the diagnosis of sepsis, might be helpful to provide adequate and timely management of critically ill patients, and thus reduce the morbidity and mortality associated with this condition.

OBJECTIVES

To determine the diagnostic accuracy of plasma interleukin-6 (IL-6) concentration for the diagnosis of bacterial sepsis in critically ill adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, and Web of Science on 25 January 2019. We screened references in the included studies to identify additional studies. We did not apply any language restriction to the electronic searches.

SELECTION CRITERIA

We included diagnostic accuracy studies enrolling critically ill adults aged 18 years or older under suspicion of sepsis during their hospitalization, where IL-6 concentrations were evaluated by serological measurement.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the references to identify relevant studies and extracted data. We assessed the methodological quality of studies using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. We estimated a summary receiver operating characteristic (SROC) curve by fitting a hierarchical summary ROC (HSROC) non-linear mixed model. We explored sources of heterogeneity using the HSROC model parameters. We conducted all analyses in the SAS statistical software package and R software.

MAIN RESULTS

We included 23 studies (n = 4192) assessing the accuracy of IL-6 for the diagnosis of sepsis in critically ill adults. Twenty studies that were available as conference proceedings only are awaiting classification. The included participants were heterogeneous in terms of their distribution of age, gender, main diagnosis, setting, country, positivity threshold, sepsis criteria, year of publication, and origin of infection, among other factors. Prevalence of sepsis greatly varied across studies, ranging from 12% to 78%. We considered all studies to be at high risk of bias due to issues related to the index test domain in QUADAS-2. The SROC curve showed a great dispersion in individual studies accuracy estimates (21 studies, 3650 adult patients), therefore the considerable heterogeneity in the collected data prevented us from calculating formal accuracy estimates. Using a fixed prevalence of sepsis of 50% and a fixed specificity of 74%, we found a sensitivity of 66% (95% confidence interval 60 to 72). If we test a cohort 1000 adult patients under suspicion of sepsis with IL-6, we will find that 330 patients would receive appropriate and timely antibiotic therapy, while 130 patients would be wrongly considered to have sepsis. In addition, 370 out of 1000 patients would avoid unnecessary antibiotic therapy, and 170 patients would have been undiagnosed of sepsis. This numerical approach should be interpreted with caution due to the limitations described above.

AUTHORS' CONCLUSIONS

Our evidence assessment of plasma interleukin-6 concentrations for the diagnosis of sepsis in critically ill adults reveals several limitations. High heterogeneity of collected evidence regarding the main diagnosis, setting, country, positivity threshold, sepsis criteria, year of publication, and the origin of infection, among other factors, along with the potential number of misclassifications, remain significant constraints for its implementation. The 20 conference proceedings assessed as studies awaiting classification may alter the conclusions of the review once they are fully published and evaluated. Further studies about the accuracy of interleukin-6 for the diagnosis of sepsis in adults that apply rigorous methodology for conducting diagnostic test accuracy studies are needed. The conclusions of the review will likely change once the 20 studies pending publication are fully published and included.

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.

High Mobility Group Box-1 and Pro-inflammatory Cytokines Are Increased in Dogs After Trauma but Do Not Predict Survival

Trauma is common in dogs and causes significant morbidity and mortality, but it remains challenging to predict the prognosis of dogs with traumatic injuries. This study aimed to quantify plasma high-mobility group box-1 (HMGB-1) and cytokine concentrations in dogs with moderate-to-severe trauma, and to evaluate the association between these biomarkers and the injury severity and survival to discharge. Using a prospective, observational case-control study design, 49 dogs with an animal trauma triage (ATT) score ≥3 were consecutively enrolled from 07/2015 to 10/2017 and followed to hospital discharge. Dogs <3 kg and those with pre-existing coagulopathies were excluded. Thirty three healthy control dogs were also enrolled. Illness and injury severity scores including the acute patient physiologic and laboratory evaluation (APPLE) were calculated using at-presentation data. Plasma HMGB-1 concentrations were measured by ELISA; concentrations of 13 cytokines were measured using multiplex bead-based assays and separately concentrations of 4 cytokines were measured using a multiplex canine-specific ELISA. All biomarkers were measured in duplicate. Mann-Whitney U tests were used to compare biomarker concentrations between groups and between survivors and non-survivors. Associations between biomarkers were evaluated using Spearman's correlation coefficients. Independent predictors of survival were identified using multivariable logistic regression. Alpha was set at 0.05. Plasma concentrations of HMGB-1, interleukin-6, C-X-C motif chemokine-8, keratinocyte chemoattractant-like, and C-C chemokine ligand-2 were significantly greater in injured dogs vs. controls (all P ≤ 0.011). In univariate analyses, HMGB-1 was significantly greater in non-survivors 46.67 ng/mL (8.94-84.73) compared to survivors 6.03 ng/mL (3.30-15.75), (P = 0.003). Neither HMGB-1 or the cytokines were associated with survival independent of illness severity as measured by the APPLE score, however.

ADAR1 prevents small intestinal injury from inflammation in a murine model of sepsis

Adenosine deaminase acting on RNA 1 (ADAR1), a double-stranded RNA-editing enzyme that converts adenosine (A) to inosine (I), has been identified as a modulator of immune responses. However, the role of ADAR1 in small intestinal homeostasis during sepsis remains unclear. In this study, we examined the role of ADAR1 on intestinal inflammation in a murine model of sepsis. We found that ADAR1 was highly expressed in "septic" macrophages and small intestinal tissue of septic mice. Deletion of ADAR1 in "septic" macrophages led to rapid apoptosis. In addition, suppression of ADAR1 in "septic" macrophages significantly enhanced inflammation, while over-expression of ADAR1 significantly suppressed the level of inflammatory cytokines. Furthermore, suppression of ADAR1 in septic mice significantly enhanced inflammation and intestinal damage, while enhanced ADAR1 expression resulted in reduced damage and inflammation. Finally, over-expression of ADAR1 improved survival of septic mice. In conclusion, we have identified a novel ADAR1 protective effect for maintaining intestinal homeostasis. Our findings may provide a new targeted therapy for sepsis treatment.

Clearance of Selected Plasma Cytokines with Continuous Veno-Venous Hemodialysis Using Ultraflux EMiC2 versus Ultraflux AV1000S

BACKGROUND

High cutoff hemofilters might support the restoration of immune homeostasis in systemic inflammation by depleting inflammatory mediators from the circulation.

METHODS

Interleukin (IL)-6, IL-8, IL-10, and tumor necrosis factor-alpha depletion was assessed in 30 sepsis patients with acute renal failure using continuous veno-venous hemodialysis with high cutoff versus standard filters (CVVHD-HCO vs. CVVHD-STD) over 48 h.

RESULTS

The transfer of IL-6 and IL-8 was significantly higher for CVVHD-HCO, as shown by increased IL-6 and IL-8 effluent concentrations. The mean plasma cytokine concentrations decreased over time for all cytokines without detectable differences for the treatment modalities. No transfer of albumin was observed for either of the filters. C-reactive protein remained stable over time and did not differ between CVVHD-HCO and CVVHD-STD, while procalcitonin decreased significantly over 48 h for both treatment modalities.

CONCLUSION

CVVHD-HCO achieved enhanced removal of IL-6 and IL-8 as compared to CVVHD-STD, without differentially reducing plasma cytokine levels.

Effects of hydroxyethyl starch 130/0.42 vs. Ringer's acetate on cytokine levels in severe sepsis

BACKGROUND

The Scandinavian Starch for Severe Sepsis/Septic Shock (6S) trial showed increased 90-day mortality with hydroxyethyl starch (HES) 130/0.42 vs. Ringer's acetate. To explore the underlying pathophysiology, we compared early changes in plasma cytokine concentrations between patients resuscitated with HES vs. Ringer's acetate.

METHODS

In a subgroup of 226 patients from the 6S trial, we calculated delta plasma concentrations of tumour necrosis factor alpha (TNF-α), interleukin (IL)-6 and IL-10 from randomization to day 2. We used multiple linear and logistic regression analyses to assess differences between the groups and associations between delta cytokine concentrations and 90-day mortality, respectively.

RESULTS

Baseline characteristics and day 2 mortality were comparable between the groups. We observed similar delta cytokine concentrations in the HES vs. Ringer's group (mean difference in delta TNF-α: -1.5 pg/ml (95% CI, -4.9 to 1.9), P = 0.39; IL-6: 36.0 pg/ml (-24.1 to 96.1), P = 0.24; IL-10: -3.9 pg/ml (-21.1 to 28.9), P = 0.76). In all included patients, we observed a linear relationship between increases in TNF-α and 90-day mortality (P = 0.005).

CONCLUSION

Resuscitation with HES 130/0.42 vs. Ringer's acetate did not appear to affect plasma concentrations of TNF-α, IL-6 or IL-10 differently during the first days after randomization into the 6S trial. In the overall cohort, increases in TNF-α were associated with increased 90-day mortality. Although interpretation should be done with caution, it seems unlikely that the increased mortality observed with the use HES in the 6S trial is signalled by early changes in three biomarkers of systemic inflammation.

Chemokines in tumor proximal fluids

Chemokines are chemotactic cytokines produced by leukocytes and other types of cells including tumor cells. Their action is determined by the expression of cognate receptors and subsequent signaling in target cells, followed by the modulation of cytoskeletal proteins and the induction of other responses. In tumors, chemokines produced by neoplastic/stroma cells control the leukocyte infiltrate influencing tumor growth and progression. Tumor cells also express functional chemokine receptors responding to chemokine signals, promoting cell survival, proliferation and metastasis formation. Chemokines may be detected in serum of cancer patients, but due to the paracrine nature of these molecules, more significant concentrations are found in the tumor adjacent, non-vascular fluids, collectively called tumor proximal fluids. This review summarizes the expression of CC and CXC chemokines in these fluids, namely in interstitial fluid, pleural, ascitic, and cyst fluids, but also in urine, saliva, cerebrospinal fluid, cervical secretions and bronchoalveolar lavage fluid. Most comparative clinical studies reveal increased chemokine levels in high-grade tumor proximal fluids rather than in low-grade tumors and benign conditions, indicating shorter survival periods. The data confirm peritumoral fluid chemokines as sensitive diagnostic and prognostic markers, as well as offer support for chemokines and their receptors as potential targets for antitumor therapy.

Cigarette Smoke Attenuates the Nasal Host Response to Streptococcus pneumoniae and Predisposes to Invasive Pneumococcal Disease in Mice

Streptococcus pneumoniae is a leading cause of invasive bacterial infections, with nasal colonization an important first step in disease. While cigarette smoking is a strong risk factor for invasive pneumococcal disease, the underlying mechanisms remain unknown. This is partly due to a lack of clinically relevant animal models investigating nasal pneumococcal colonization in the context of cigarette smoke exposure. We present a model of nasal pneumococcal colonization in cigarette smoke-exposed mice and document, for the first time, that cigarette smoke predisposes to invasive pneumococcal infection and mortality in an animal model. Cigarette smoke increased the risk of bacteremia and meningitis without prior lung infection. Mechanistically, deficiency in interleukin 1α (IL-1α) or platelet-activating factor receptor (PAFR), an important host receptor thought to bind and facilitate pneumococcal invasiveness, did not rescue cigarette smoke-exposed mice from invasive pneumococcal disease. Importantly, we observed cigarette smoke to attenuate nasal inflammatory mediator expression, particularly that of neutrophil-recruiting chemokines, normally elicited by pneumococcal colonization. Smoking cessation during nasal pneumococcal colonization rescued nasal neutrophil recruitment and prevented invasive disease in mice. We propose that cigarette smoke predisposes to invasive pneumococcal disease by suppressing inflammatory processes of the upper respiratory tract. Given that smoking prevalence remains high worldwide, these findings are relevant to the continued efforts to reduce the invasive pneumococcal disease burden.

[Microarrays as biomarkers in trauma]

BACKGROUND

The traditional hypothesis-driven scientific approach cannot so far sufficiently elucidate complex pathophysiologies, such as posttraumatic systemic inflammation and subsequent multiple organ failure. This complex system includes different biological and functional levels, the genome, the transcriptome, the proteome, the biome (cells), the organs and finally the whole organism.

METHODS

Microarray techniques enable a simultaneous search for these different biological levels and their functional relationships on a large scale and to discover new functional pathways and networks and potentially new biomarkers for different pathologies. Microarray technologies lead to a new paradigm in science, the hypothesis-generating approach.

AIM

This article reviews important microarray findings in trauma and systemic inflammation research and discusses potentials and limitations of these biotechnological screening methods.

Biomarkers for Sepsis: What Is and What Might Be?

Every year numerous individuals develop the morbid condition of sepsis. Therefore, novel biomarkers that might better inform clinicians treating such patients are sorely needed. Difficulty in identifying such markers is in part due to the complex heterogeneity of sepsis, resulting from the broad and vague definition of this state/condition based on numerous possible clinical signs and symptoms as well as an incomplete understanding of the underlying pathobiology of this complex condition. This review considers some of the attempts that have been made so far, looking at both the pro- and anti-inflammatory response to sepsis, as well as genomic analysis, as sources of potential biomarkers. Irrespective, for functional biomarker(s) of sepsis to successfully translate from the laboratory to a clinical setting, the biomarker must be target specific and sensitive as well as easy to implement/interpret, and be cost effective, such that they can be utilized routinely in patient diagnosis and treatment.

Impact of haemorrhagic shock intensity on the dynamic of alarmins release in porcine poly-trauma animal model

PURPOSE

Traumatic insults result in an altered inflammatory response, in which alarmins release has a central role. The impact of haemorrhagic shock intensity on the long-term kinetics of alarmins is not yet fully elucidated. We investigated these aspects in a combined trauma (chest, abdominal, and extremities injury) porcine model with different severities and durations of haemorrhagic shock.

METHODS

After induction of combined trauma (tibia fracture, lung contusion, and liver laceration), haemorrhagic shock was induced at different intensities: moderate haemorrhage (MH; n = 15): mean arterial pressure (MAP) <30 ± 5 mmHg [maximum loss of total blood volume (TBVmax): 45 %] for 90 min, and severe haemorrhage (SH; n = 10): MAP <25 ± 5 mmHg (TBVmax 50 %) for 120 min. Resuscitation was performed using a standardized crystalloid infusion protocol. Animals were mechanically ventilated and underwent ICU-monitoring for 48 h (MH) and 48.5 h (SH). Blood samples were collected over the clinical time course, and systemic levels of serum alarmins [High-Mobility Group Protein B-1 (HMGB-1) and Heat Shock Protein 70 (HSP70)] were measured using an ELISA kit.

RESULTS

Heart rate, systemic blood pressure, lactate, and base excess were significantly altered as a function of haemorrhagic shock in both trauma groups (MH and SH). Systemic HMGB-1 levels were significantly elevated in both trauma groups when compared to the sham group. Haemorrhagic shock severity and duration were positively correlated with HMGB-1 levels and compared to baseline values, concentrations remained significantly increased in SH when compared to MH. On the other hand, we observed a significant decrease in the systemic HSP70 levels of trauma groups (MH, and SH) when compared to the sham group, which was significantly decreased compared to baseline values in SH over the entire time course.

CONCLUSION

Our data show that haemorrhagic shock duration and severity affect the systemic levels of HMGB-1 and HSP70. This early alarmins release after trauma can be used to guide the treatment strategies (e.g. surgical procedures) of polytrauma patients.

Circulating levels of platelet α-granule cytokines in trauma patients

OBJECTIVE AND DESIGN

To elucidate whether platelets differentiate cytokine release following trauma, we prospectively measured three major platelet-derived cytokines in 213 trauma patients on hospital arrival.

METHODS

We measured plasma levels of the anti-inflammatory β-thromboglobulins (βTGs), transforming growth factor-β1 (TGFβ1) and the pro-inflammatory platelet factor 4 (PF4) cytokines. We also measured soluble glycoprotein VI (sGPVI), procoagulant platelet microparticles (PMPs) and white blood cell (WBC) counts, and evaluated in vitro platelet function in primary and secondary haemostasis by aggregometry and thromboelastometry, respectively. We evaluated associations of each cytokine by multivariate regression including injury severity score (ISS), WBC counts, sGPVI and platelet counts as explanatory variables.

RESULTS

Severely injured patients (ISS > 15) had higher levels of βTGs and TGFβ1 (both p < 0.01) but lower levels of PF4 (p = 0.02). GPVI and PMPs levels correlated with TGFβ1 and PF4 whereas we found no significant association between cytokine levels and measures of haemostasis. By multivariate regression, a high WBC count was associated with high levels of TGFβ1 (p = 0.01) and βTGs (p < 0.01) but with low levels of PF4 (p = 0.03).

CONCLUSION

Severely injured patients had higher levels of βTGs and TGFβ1 but lower levels of the PF4; a high WBC count predicted this anti-inflammatory profile of platelet cytokines.

Clinical relevance of IL-6 gene polymorphism in severely injured patients

In polytrauma, injuries that may be surgically treated under regular circumstances due to a systemic inflammatory response become life-threatening. The inflammatory response involves a complex pattern of humoral and cellular responses and the expression of related factors is thought to be governed by genetic variations. This aim of this paper is to examine the influence of interleukin (IL) 6 single nucleotide polymorphism (SNP) -174C/G and -596G/A on the treatment outcome in severely injured patients. Forty-seven severely injured patients were included in this study. Patients were assigned an Injury Severity Score. Blood samples were drawn within 24 h after admission (designated day 1) and on subsequent days (24, 48, 72 hours and 7 days) of hospitalization. The IL-6 levels were determined through ELISA technique. Polymorphisms were analyzed by a method of Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR). Among subjects with different outcomes, no statistically relevant difference was found with regards to the gene IL-6 SNP-174G/C polymorphism. More than a half of subjects who died had the SNP-174G/C polymorphism, while this polymorphism was represented in a slightly lower number in survivors. The incidence of subjects without polymorphism and those with heterozygous and homozygous gene IL-6 SNP-596G/A polymorphism did not present statistically significant variations between survivors and those who died. The levels of IL-6 over the observation period did not present any statistically relevant difference among subjects without the IL-6 SNP-174 or IL- 6 SNP -596 gene polymorphism and those who had either a heterozygous or a homozygous polymorphism.

Relationship between acid-base status and inflammation in the critically ill

Introduction

There is a complex interplay between changes in acid–base components and inflammation. This manuscript aims to explore associations between plasma cytokines and chemokines and acid–base status on admission to intensive care.

Methods

We conducted a prospective cohort study in a 13-bed ICU in a tertiary-care center in Brazil. 87 unselected patients admitted to the ICU during a 2-year period were included. We measured multiple inflammatory mediators in plasma using multiplex assays and evaluated the association between mediator concentrations and acid–base variables using a variety of statistical modeling approaches, including generalized linear models, multiadaptive regression splines and principal component analysis.

Results

We found a positive association between strong ion gap (SIG) and plasma concentrations of interleukin (IL)6, 8, 10 and tumor necrosis factor (TNF); whereas albumin was negatively associated with IL6, IL7, IL8, IL10, TNF and interferon (IFN)α. Apparent strong ion difference (SID_a) was negatively associated with IL10 and IL17. A principal component analysis including SAPS 3 indicated that the association between acid–base components and inflammatory status was largely independent of illness severity, with both increased SIG and decreased SID_a (both drivers of acidosis) associated with increased inflammation.

Conclusion

Acid–base variables (especially increased SIG, decreased albumin and decreased SID_a) on admission to ICU are associated with immunological activation. These findings should encourage new research into the effects of acid–base status on inflammation.