Sepsis: time has come to focus on the later stages

Profiling the dysregulated immune response in sepsis: overcoming challenges to achieve the goal of precision medicine

Sepsis is characterised by a dysregulated host immune response to infection. Despite recognition of its significance, immune status monitoring is not implemented in clinical practice due in part to the current absence of direct therapeutic implications. Technological advances in immunological profiling could enhance our understanding of immune dysregulation and facilitate integration into clinical practice. In this Review, we provide an overview of the current state of immune profiling in sepsis, including its use, current challenges, and opportunities for progress. We highlight the important role of immunological biomarkers in facilitating predictive enrichment in current and future treatment scenarios. We propose that multiple immune and non-immune-related parameters, including clinical and microbiological data, be integrated into diagnostic and predictive combitypes, with the aid of machine learning and artificial intelligence techniques. These combitypes could form the basis of workable algorithms to guide clinical decisions that make precision medicine in sepsis a reality and improve patient outcomes.

EARLY PERSISTENT LYMPHOPENIA AND RISK OF DEATH IN CRITICALLY ILL PATIENTS WITH AND WITHOUT SEPSIS

ABSTRACT

Purpose: To examine the relationship of early persistent lymphopenia with hospital survival in critically ill patients with and without sepsis to assess whether it can be considered a treatable trait. Methods: Retrospective database analysis of patients with nonelective admission to intensive care units (ICUs) during January 2015 to December 2018. Patients were classified as having sepsis if the Acute Physiology and Chronic Health Evaluation III admission diagnostic code included sepsis or coded for an infection combined with a Sequential Organ Failure Assessment score of ≥2. We defined early persistent lymphopenia at two thresholds (absolute lymphocyte count [ALC] <1.0 and <0.75 × 10 9 /L) based on two qualifying values recorded during the first 4 days in ICU. The main outcome measure was time to in-hospital death. Results: Of 8,507 eligible patients, 7,605 (89.4%) had two ALCs recorded during their first 4 days in ICU; of these, 1,482 (19.5%) had sepsis. Persistent lymphopenia (ALC <1.0) was present in 728 of 1,482 (49.1%) and 2,302 of 6,123 (37.6%) patients with and without sepsis, respectively. For ALC <0.75, the results were 487 of 1,482 (32.9%) and 1,125 of 6,123 (18.4%), respectively. Of 3,030 patients with persistent lymphopenia (ALC <1.0), 562 (18.5%) died compared with 439 of 4,575 (9.6%) without persistent lymphopenia. Persistent lymphopenia was an independent risk factor for in-hospital death in all patients. The hazard ratios for death at ALC <1.0 were 1.89 (95% confidence interval, 1.32-2.71; P = 0.0005) and 1.17 (95% confidence interval, 1.02-1.35; P = 0.0246) in patients with and without sepsis respectively. Conclusions: Early persistent lymphopenia is common in critically ill patients and associated with increased risk of death in patients with and without sepsis. Although the association is stronger in patients with sepsis, lymphopenia is a candidate to be considered a treatable trait; drugs that reverse lymphopenia should be trialed in critically ill patients.

Norepinephrine May Exacerbate Septic Acute Kidney Injury: A Narrative Review

Sepsis, the most serious complication of infection, occurs when a cascade of potentially life-threatening inflammatory responses is triggered. Potentially life-threatening septic shock is a complication of sepsis that occurs when hemodynamic instability occurs. Septic shock may cause organ failure, most commonly involving the kidneys. The pathophysiology and hemodynamic mechanisms of acute kidney injury in the case of sepsis or septic shock remain to be elucidated, but previous studies have suggested multiple possible mechanisms or the interplay of multiple mechanisms. Norepinephrine is used as the first-line vasopressor in the management of septic shock. Studies have reported different hemodynamic effects of norepinephrine on renal circulation, with some suggesting that it could possibly exacerbate acute kidney injury caused by septic shock. This narrative review briefly covers the updates on sepsis and septic shock regarding definitions, statistics, diagnosis, and management, with an explanation of the putative pathophysiological mechanisms and hemodynamic changes, as well as updated evidence. Sepsis-associated acute kidney injury remains a major burden on the healthcare system. This review aims to improve the real-world clinical understanding of the possible adverse outcomes of norepinephrine use in sepsis-associated acute kidney injury.

Prognostic Value of Platelet to Lymphocyte Ratio in Sepsis: A Systematic Review and Meta-analysis

The goal of this study was to conduct a systematic review of the literature on the relationship between peripheral blood platelet to lymphocyte ratio (PLR) and mortality in sepsis and to integrate the findings in a meta-analysis. An electronic search of three main databases was performed: PubMed, Embase, and Scopus on 19 December 2021. Finally, 16 studies comprising 2403 septic patients, including 1249 survivors and 1154 nonsurvivors, were included in this meta-analysis. We found that PLR levels were significantly higher in nonsurvivors than in survivors (random effect model: SMD = 0.72, 95% CI; 0.35–1.10, p < 0.001). However, significant heterogeneity was observed across the studies (I² = 94.1%, p < 0.01). So, we used random effect model in our meta-analysis. In the subgroup analysis, according to mortality time, patients deceased during one month after sepsis had elevated levels of PLR compared to survivors (SMD = 1.03, 95% CI = 0.15-1.92, p = 0.22). However, in-hospital mortality was not associated with PLR level (SMD = 0.41, 95% CI = −0.18-0.99, p = 0.175). Our findings support PLR to be a promising biomarker that can be readily integrated into clinical settings to aid in the prediction and prevention of sepsis mortality.

Serial Change of Endotoxin Tolerance in a Polymicrobial Sepsis Model

Immune suppression is known to occur during sepsis. Endotoxin tolerance is considered a mechanism of immune suppression in sepsis. However, the timing and serial changes in endotoxin tolerance have not been fully investigated. In this study, we investigated serial changes in endotoxin tolerance in a polymicrobial sepsis model. Herein, we used a rat model of fecal slurry polymicrobial sepsis. After induction of sepsis, endotoxin tolerance of peripheral blood mononuclear cells (PBMCs) and splenocytes was measured at various time points (6 h, 12 h, 24 h, 48 h, 72 h, 5 days, and 7 days), through the measurement of TNF-α production after stimulation with lipopolysaccharide (LPS) in an ex vivo model. At each time point, we checked for plasma tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 levels. Moreover, we analyzed reactive oxygen species (ROS) as measured by 2′,7′-dichlorodihydrofluorescein, plasma lactate, serum alanine aminotransferase (ALT), and creatinine levels. Nuclear factor (NF)-κB, IL-1 receptor-associated kinase (IRAK)-M, and cleaved caspase 3 levels were measured in the spleen. Endotoxin tolerance, measured by TNF-α production stimulated through LPS in PBMCs and splenocytes, was induced early in the sepsis model, starting from 6 h after sepsis. It reached a nadir at 24 to 48 h after sepsis, and then started to recover. Endotoxin tolerance was more prominent in the severe sepsis model. Plasma cytokines peaked at time points ranging from 6 to 12 h after sepsis. ROS levels peaked at 12 h and then decreased. Lactate, ALT, and serum creatinine levels increased up to 24 to 48 h, and then decreased. Phosphorylated p65 and IRAK-M levels of spleen increased up to 12 to 24 h and then decreased. Apoptosis was prominent 48 h after sepsis, and then recovered. In the rat model of polymicrobial sepsis, endotoxin tolerance occurred earlier and started to recover from 24 to 48 h after sepsis.

Critical Illness Myopathy: Diagnostic Approach and Resulting Therapeutic Implications

Purpose of review

Critical illness myopathy (CIM) is a common neuro-muscular complication of intensive care treatment associated with increased morbidity and mortality. The current guidelines for diagnosis include clinical and electrophysiological criteria as well as a muscle biopsy, and allow diagnosis only at an advanced stage of the disease. To date, there is no treatment for CIM available, apart from symptomatic and rehabilitative interventions. In this review, we discuss different diagnostic approaches and describe new treatment possibilities for CIM.

Recent findings

Of the diagnostic approaches evaluated, a new electrophysiological technique for measuring muscle excitability has the greatest potential to allow earlier diagnosis of CIM than the current guidelines do and thereby may facilitate the conduction of future pathophysiological and therapeutic studies. Although clinical trials are still lacking, in animal models, BGP-15, vamorolone, and ruxolitinib have been shown to have anti-inflammatory effects, to reduce muscle wasting and to improve muscle function and survival.

Summary

In recent years, promising methods for early and confirmatory diagnosis of CIM have been developed, but still need validation. Experimental studies on novel pharmacological interventions show promising results in terms of preventive CIM treatments, but future clinical studies will be needed to study the effectiveness and safety of these drugs.

The Need of Enterococcal Coverage in Severe Intra-Abdominal Infection: Evidence from Animal Study

Intra-abdominal infection (IAI) is a common and important cause of infectious mortality in intensive care units. Adequate source control and appropriate antimicrobial regimens are key in the management of IAI. In community-acquired IAI, guidelines recommend the use of different antimicrobial regimens according to severity. However, the evidence for this is weak. We investigated the effect of enterococcal coverage in antimicrobial regimens in a severe polymicrobial IAI model. We investigated the effects of imipenem/cilastatin (IMP) and ceftriaxone with metronidazole (CTX + M) in a rat model of severe IAI. We observed the survival rate and bacterial clearance rate. We identified the bacteria in blood culture. We measured lactate, alanine aminotransferase (ALT), creatinine, interleukin (IL)-6, IL-10, and reactive oxygen species (ROS) in the blood. Endotoxin tolerance of peripheral blood mononuclear cells (PBMCs) was also estimated to determine the level of immune suppression. In the severe IAI model, IMP improved survival and bacterial clearance compared to CTX + M. Enterococcus spp. were more frequently isolated in the CTX + M group. IMP also decreased plasma lactate, cytokine, and ROS levels. ALT and creatinine levels were lower in IMP group. In the mild-to-moderate IAI model, however, there was no survival difference between the groups. Immune suppression of PBMCs was observed in IAI model, and it was more prominent in the severe IAI model. Compared to CTX + M, IMP improved the outcome of rats in severe IAI model.

Persistent lymphopenia after diagnosis of COVID-19 predicts acute respiratory distress syndrome: A retrospective cohort study

Background

Lymphopenia is a marker of immunosuppression after severe coronavirus disease-2019 (COVID-19) which is characterized by acute respiratory distress syndrome (ARDS). This study aimed to evaluate the relationships between persistent lymphopenia and ARDS.

Methods

A retrospective cohort study of 125 patients with COVID-19 admitted to government-designated treatment center between 14 January 2020, and 20 March 2020 was conducted. We recorded all complete blood cell counts during the day 0th, 3rd, and 7th following the diagnosis of COVID-19. Patients were grouped based on the depression of the lymphocyte cell count, their return, or their failure to normal. The primary outcome was the occurrence of ARDS, and secondary outcomes included developing vital organ dysfunction and hospital lengths of stay.

Results

17.6% (22/125) patients developed ARDS. The lymphocyte counts with ARDS and non-ARDS were 0.94 × 109/L, 1.20 × 109/L at admission, respectively ( p = 0.02). On the 3rd and 7th day, the median of lymphocyte count in ARDS was significantly lower than that of non-ARDS. Multivariable logistic regression, which was adjusting for potentially confounding factors (including age, comorbidities, and APACHE II score), showed that persistent lymphopenia within the 7th day was independently associated with ARDS (OR, 3.94 [95% CI, 1.26–12.33, p = 0.018). Further, patients with persistent lymphopenia had longer hospital lengths of stay ( p < 0.001).

Conclusion

The results showed persistent lymphopenia predicted ARDS after COVID-19. Further studies are needed to investigate whether immunostimulation of lymphocytes within 1 week can reduce ARDS occurrence in patients with COVID-19.

COVID-19-associated acute respiratory distress syndrome (CARDS): Current knowledge on pathophysiology and ICU treatment - A narrative review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces coronavirus-19 disease (COVID-19) and is a major health concern. Following two SARS-CoV-2 pandemic “waves,” intensive care unit (ICU) specialists are treating a large number of COVID19-associated acute respiratory distress syndrome (ARDS) patients. From a pathophysiological perspective, prominent mechanisms of COVID19-associated ARDS (CARDS) include severe pulmonary infiltration/edema and inflammation leading to impaired alveolar homeostasis, alteration of pulmonary physiology resulting in pulmonary fibrosis, endothelial inflammation (endotheliitis), vascular thrombosis, and immune cell activation.

Although the syndrome ARDS serves as an umbrella term, distinct, i.e., CARDS-specific pathomechanisms and comorbidities can be noted (e.g., virus-induced endotheliitis associated with thromboembolism) and some aspects of CARDS can be considered ARDS “atypical.” Importantly, specific evidence-based medical interventions for CARDS (with the potential exception of corticosteroid use) are currently unavailable, limiting treatment efforts to mostly supportive ICU care.

In this article, we will discuss the underlying pulmonary pathophysiology and the clinical management of CARDS. In addition, we will outline current and potential future treatment approaches.

Reduced Monocytic Human Leukocyte Antigen-DR Expression Indicates Immunosuppression in Critically Ill COVID-19 Patients

BACKGROUND:

The cellular immune system is of pivotal importance with regard to the response to severe infections. Monocytes/macrophages are considered key immune cells in infections and downregulation of the surface expression of monocytic human leukocyte antigen-DR (mHLA-DR) within the major histocompatibility complex class II reflects a state of immunosuppression, also referred to as injury-associated immunosuppression. As the role of immunosuppression in coronavirus disease 2019 (COVID-19) is currently unclear, we seek to explore the level of mHLA-DR expression in COVID-19 patients.

METHODS:

In a preliminary prospective monocentric observational study, 16 COVID-19–positive patients (75% male, median age: 68 [interquartile range 59–75]) requiring hospitalization were included. The median Acute Physiology and Chronic Health Evaluation-II (APACHE-II) score in 9 intensive care unit (ICU) patients with acute respiratory failure was 30 (interquartile range 25–32). Standardized quantitative assessment of HLA-DR on monocytes (cluster of differentiation 14+ cells) was performed using calibrated flow cytometry at baseline (ICU/hospital admission) and at days 3 and 5 after ICU admission. Baseline data were compared to hospitalized noncritically ill COVID-19 patients.

RESULTS:

While normal mHLA-DR expression was observed in all hospitalized noncritically ill patients (n = 7), 89% (8 of 9) critically ill patients with COVID-19–induced acute respiratory failure showed signs of downregulation of mHLA-DR at ICU admission. mHLA-DR expression at admission was significantly lower in critically ill patients (median, [quartiles]: 9280 antibodies/cell [6114, 16,567]) as compared to the noncritically ill patients (30,900 antibodies/cell [26,777, 52,251]), with a median difference of 21,508 antibodies/cell (95% confidence interval [CI], 14,118–42,971), P = .002. Reduced mHLA-DR expression was observed to persist until day 5 after ICU admission.

CONCLUSIONS:

When compared to noncritically ill hospitalized COVID-19 patients, ICU patients with severe COVID-19 disease showed reduced mHLA-DR expression on circulating CD14+ monocytes at ICU admission, indicating a dysfunctional immune response. This immunosuppressive (monocytic) phenotype remained unchanged over the ensuing days after ICU admission. Strategies aiming for immunomodulation in this population of critically ill patients should be guided by an immune-monitoring program in an effort to determine who might benefit best from a given immunological intervention.

Cytokine Removal in Critically Ill Patients Requiring Surgical Therapy for Infective Endocarditis (RECReATE): An Investigator-initiated Prospective Randomized Controlled Clinical Trial Comparing Two Established Clinical Protocols

INTRODUCTION

Infective endocarditis (IE) and other severe infections induce significant changes in the immune response in a considerable number of affected patients. Numerous IE patients develop a persistent functional immunological phenotype that can best be characterized by a profound anti-inflammation and/ or functional "anergy." This is pronounced in patients with unresolved infectious foci and was previously referred to as "injury-associated immunosuppression" (IAI). IAI can be assessed by measurement of the monocytic human leukocyte antigen-DR (mHLA-DR) expression, a global functional marker of immune competence. Persistence of IAI is associated with prolonged intensive care unit length of stay, increased secondary infection rates, and death. Immunomodulation to reverse IAI was shown beneficial in early immunostimulatory (randomized controlled) clinical trials.

METHODS

Prospective 1:1 randomized controlled clinical study to compare the course of mHLA-DR in patients scheduled for cardiac surgery for IE. Patients will receive either best standard of care plus cytokine adsorption during surgery while on cardiopulmonary bypass (protocol A) versus best standard of care alone, that is, surgery without cytokine adsorption (protocol B). A total of 54 patients will be recruited and randomized. The primary endpoint is a change in quantitative expression of mHLA-DR (antibodies per cell on CD14+ monocytes/ macrophages, assessed using a quantitative standardized assay) from baseline (preoperation [pre-OP], visit 1) to day 1 post-OP (visit 4).

DISCUSSION

This randomized controlled clinical trial (RECReATE) will compare 2 clinical treatment protocols and will investigate whether cytokine adsorption restores monocytic immune competence (reflected by increased mHLA-DR expression) in patients with IE undergoing cardiac surgery.

TRIAL REGISTRATION

This protocol was registered in ClinicalTrials.gov, under number NCT03892174, first listed on March 27, 2019.

Time and sex dependency of hemodynamic, renal, and survivability effects of endotoxemia in rats

Widely different exposure times to endotoxic insults have been employed in reported studies. The current experimental study systematically evaluated the time-course and sex influences of endotoxic insult on survivability and cardiovascular and renal functions. Rats received i.p. lipopolysaccharide (LPS, 5 mg/kg) once or twice (over 2 successive days). Systolic blood pressure (SBP), biomarkers of renal function and inflammation, and vasodilator responsiveness of isolated perfused kidneys to acetylcholine (ACh) or N-ethylcarboxamidoadenosine (NECA) were evaluated 6 hr after first LPS injection or 1, 2, or 6 days later. A single 6-hr LPS challenge caused (i) sex-unrelated elevations in serum urea and creatinine and reductions in NECA, but not ACh, vasodilations, (ii) more increases in renal NF-κB/iNOS expressions in male than in female rats, and (iii) hypotension and tachycardia only in male rats. These parameters, except for hemodynamic changes, were restored to near-control levels 1 day after single LPS dosing. The 2-days dosing with LPS had no effects on renal function biomarkers, but caused hypotension, tachycardia, and increases in renal NF-κB/iNOS expression and NECA and ACh vasodilations in both rat sexes. None of these parameters were different from control values when measured 6 days after the endotoxic insult. Alternatively, the rat mortality was observed during first 2 days of the study and was notably higher in male than in female rats. Our data suggest that the frequency and time elapsed after LPS exposure as well as rat sex are important determinants of the magnitude and direction of detrimental effects of endotoxemia.

Exogenous Heat Shock Cognate Protein 70 Suppresses LPS-Induced Inflammation by Down-Regulating NF-κB through MAPK and MMP-2/-9 Pathways in Macrophages

Heat shock cognate protein 70 (HSC70), a molecular chaperone, is constitutively expressed by mammalian cells to regulate various cellular functions. It is associated with many diseases and is a potential therapeutic target. Although HSC70 also possesses an anti-inflammatory action, the mechanism of this action remains unclear. This current study aimed to assess the anti-inflammatory effects of HSC70 in murine macrophages RAW 264.7 exposed to lipopolysaccharides (LPS) and to explain its pathways. Mouse macrophages (RAW 264.7) in 0.1 µg/mL LPS incubation were pretreated with recombinant HSC70 (rHSC70) and different assays (Griess assay, enzyme-linked immune assay/ELISA, electrophoretic mobility shift assay/EMSA, gelatin zymography, and Western blotting) were performed to determine whether rHSC70 blocks pro-inflammatory mediators. The findings showed that rHSC70 attenuated the nitric oxide (NO) generation, tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) expressions in LPS-stimulated RAW264.7 cells. In addition, rHSC70 preconditioning suppressed the activities and expressions of matrix metalloproteinase-2 (MMP-2) and MMP-9. Finally, rHSC70 diminished the nuclear translocation of nuclear factor-κB (NF-κB) and reduced the phosphorylation of extracellular-signal regulated kinases 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinases (MAPK), and phosphatidylinositol-3-kinase (PI3K/Akt). We demonstrate that rHSC70 preconditioning exerts its anti-inflammatory effects through NO production constriction; TNF-α, and IL-6 suppression following down-regulation of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), and MMP-2/MMP-9. Accordingly, it ameliorated the signal transduction of MAPKs, Akt/IκBα, and NF-κB pathways. Therefore, extracellular HSC70 plays a critical role in the innate immunity modulation and mechanisms of endogenous protective stimulation.

Fc Gamma Receptor IIB Deficient Mice: A Lupus Model with Increased Endotoxin Tolerance-Related Sepsis Susceptibility

Hyper-elevated immune response of FcGRIIb-/- mice, a lupus model with an inhibitory-signaling defect, can become exhausted (less subsequent immune-response than the first response) with sequential lipopolysaccharide (LPS) stimulation. Endotoxin tolerance-related modifications of inflammatory response were investigated in FcGRIIb-/- mice in both an in vivo sepsis model and in vitro using cultured macrophages. Serum cytokine concentrations, after the second LPS injection (at 5-fold higher levels than the first dose), did not exceed the first dose levels in either FcGRIIb-/- or wild-type mice. These data indicated an endotoxin-tolerance response in both genetic backgrounds. However, the difference of cytokine levels between the first and second LPS injection was more prominent in FcGRIIb-/- mice. More importantly, CLP-induced sepsis after LPS-preconditioning (two separated doses of LPS administration) was more severe in FcGRIIb-/- mice (as measured by mortality rate, bacteria count in blood, serum cytokines, creatinine, and alanine transaminase). An attenuated response was demonstrated after two sequential LPS stimulations of bone-marrow-derived macrophages. Cytokine production was reduced and lower bacterial killing activity occurred with macrophages from FcGRIIb-/- mice relative to wild-type macrophages. Thus, there is a more prominent effect of endotoxin-tolerance in FcGRIIb-/- macrophages relative to wild-type. In conclusion, repeated-LPS administrations induced quantitatively greater endotoxin-tolerance responses in FcGRIIb-/- mice both in vivo and in vitro. Endotoxin-tolerance in vivo was associated with more severe sepsis, at least in part, due to macrophage-dysfunction.

Opioids and immunosupression in oncological postoperative patients

INTRODUCTION

Recent animal studies demonstrated immunosuppressive effects of opioid withdrawal resulting in a higher risk of infection. The aim of this study was to determine the impact of remifentanil discontinuation on Post-Anesthesia Care Unit (PACU)-acquired infection after a schedule of sedoanalgesia of at least 6 days.

METHOD

All patients over 18 years of age with a unit admission of more than 4 days were consecutively selected. The study population was the one affected by surgical pathology of any origin where sedation was based on any hypnotic and the opioid remifentanil was used as analgesic for at least 96 hours in continuous perfusion. Patients who died during admission to the unit and those with combined analgesia (peripheral or neuroaxial blocks) were excluded. Bivariate analysis was performed to determine risk factors for infection acquired in the unit. A comparative study between periods of 6 days before and after the cessation of remifentanil was performed. Paired samples test and McNemar test was used for quantitative and categorical variables, respectively.

RESULTS

There were 1,789 patients admitted to the PACU during the study and the population eligible was constituted for 102 patients. The incidence rate of PACU-acquired infection was 38 per 1,000 PACU days. Ventilator-associated pneumonia was the most frequently diagnosed PACU-acquired infection. Pseudomona aeruginosa was the most frequently isolated microorganism. Hospital mortality was 36.27%. No statistically significant differences were seen in the incidence of HAI in cancer patients in relation to discontinuation of remifentanil (p=0.068).

CONCLUSION

The baseline state of immunosuppression of cancer patients does not imply a higher incidence of HAI in relation to the interruption of remifentanil. It would be of interest to carry out a multicenter PACU study that included immunological patterns.

Assessment of immune organ dysfunction in critical illness: utility of innate immune response markers

In critically ill patients, organ dysfunctions are routinely assessed, monitored, and treated. Mounting data show that substantial critical illness-induced changes in the immune system can be observed in most ICU patients and that not only "hyper-inflammation" but also persistence of an anti-inflammatory phenotype (as in sepsis-associated immunosuppression) is associated with increased morbidity and mortality. Despite common perception, changes in functional immunity cannot be adequately assessed by routine inflammatory biomarkers such as C-reactive protein, procalcitonin, or numerical analysis of leukocyte (sub)-counts. Cytokines appear also not suited due to their short half-life and pleiotropy, their unexclusive origin from immune cells, and their potential to undergo antagonization by circulating inactivating molecules. Thus, beyond leukocyte quantification and use of routine biomarkers, direct assessment of immune cell function seems required to characterize the immune systems' status. This may include determination of, e.g., ex vivo cellular cytokine release, phagocytosis activity, and/or antigen-presenting capacity. In this regard, standardized flow-cytometric assessment of the major histocompatibility-II complex human leukocyte antigen (-D related) (HLA-DR) has gained particular interest. Monocytic HLA-DR (mHLA-DR) controls the interplay between innate and adaptive immunity and may serve as a "global" biomarker of injury-associated immunosuppression, and its decreased expression is associated with adverse clinical outcomes (e.g., secondary infection risk, mortality). Importantly, recent data demonstrate that injury-associated immunosuppression can be reversed-opening up new therapeutic avenues in affected patients. Here we discuss the potential scientific and clinical value of assessment of functional immunity with a focus on monocytes/macrophages and review the current state of knowledge and potential perspectives for affected critically ill patients.

Sepsis after renal transplantation: Clinical, immunological, and microbiological risk factors

BACKGROUND

As immunosuppressive therapy and allograft survival have improved, the increased incidence of sepsis has become a major hurdle of disease-free survival after renal transplantation.

METHODS

We identified 112 of 957 kidney transplant recipients (KTRs) with sepsis. In all, 31 KTRs developed severe sepsis or septic shock, and 30 KTRs died from sepsis. KTRs without sepsis were used for comparison. CMV-specific and alloreactive T cells were measured using an interferon-γ Elispot assay. The extent of immunosuppression was quantified by lymphocyte subpopulations.

RESULTS

Five-year patient survival was 70.3% with sepsis compared to 88.2% without (P<.001). Five-year estimated glomerular filtration rate was lower in KTRs developing sepsis (P<.001). Upon multivariate analysis, diabetes, lymphocyte-depleting induction, donor age, CMV replication, and acute rejection increased the risk of sepsis (P<.05). Age, diabetes, underweight/obesity, and pneumonia as site of infection were predictive factors of mortality (P<.05). Early-onset sepsis was associated with decreased CD3+ and CD4+ T cells pre-transplantation (P<.05). Impaired CMV-specific cellular immunity pre-transplantation was associated with CMV replication and early-onset sepsis (P<.05). High frequencies of alloreactive T cells were associated with acute rejection, lymphocyte-depleting rejection treatment, and early-onset sepsis (P<.05).

CONCLUSION

KTRs developing sepsis show inferior patient survival and allograft function. Identified risk factors and differences in lymphocyte counts, CMV-specific immunity, and alloreactivity may prove useful to identify KTRs at increased risk.

Shenfu injection for improving cellular immunity and clinical outcome in patients with sepsis or septic shock

PURPOSE

To assess the efficacy of Shenfu injection (SFI) for enhancing cellular immunity and improving the clinical outcomes of patients with septic shock.

METHODS

Patients with sepsis were randomly assigned to receive either SFI at a dose of 100mL every 24hours for 7 consecutive days or a placebo in addition to conventional therapy. The immunologic parameters were collected on days 1, 3, and 7 after the above treatments, and the clinical outcomes were updated for 28days.

RESULTS

Of these160 patients, 3 were excluded from the analysis due to protocol violation and withdrawal of consent; thus, 157 completed the study (78 in the SFI group and 79 in the placebo group). We found that SFI increased both CD4⁺ and CD8⁺ T cells in peripheral blood and up-regulated HLA-DR expression in monocytes (P<.05). Furthermore, SFI was also found to restore ex vivo monocytic tumor necrosis factor α and interleukin 6 proinflammatory cytokine release in response to the endotoxin (P<.05). Importantly, the SFI group showed better clinical outcomes than did the placebo group in terms of the duration of vasopressor use (P=.008), Acute Physiology and Chronic Health Evaluation II score (P=.034), Marshall score (P=.01), and length of intensive care unit stay (10.5±3.2 vs 12.2±2.8days; P=.012). However, the 28-day mortality rate was not significantly different between the SFI (20.5%; 16/78) and placebo groups (27.8%; -22/79; P=.28).

CONCLUSION

These findings suggest that SFI can enhance the cellular immunity of patients with septic shock and could be a promising adjunctive treatment for patients with septic shock.

A Review of GM-CSF Therapy in Sepsis

Determine what clinical role, if any, GM-CSF may have in the clinical treatment of sepsis in the adult patient. Advancements in the management of sepsis have led to significant decreases in early mortality; however, sepsis remains a significant source of long-term mortality and disability which places strain on healthcare resources with a substantial growing economic impact. Historically, early multiple organ failure (MOF) and death in patients with severe sepsis was thought to result from an exaggerated proinflammatory response called the systemic inflammatory response syndrome (SIRS). Numerous prospective randomized controlled trials (PRCTs) tested therapies aimed at decreasing the organ injury associated with an exaggerated inflammatory response. With few exceptions, the results from these PRCTs have been disappointing, and currently no specific therapeutic agent is approved to counteract the early SIRS response in patients with severe sepsis. It has long been recognized that there is a delayed immunosuppressive state that contributes to long-term morbidity. However, recent findings now support a concurrent proinflammatory and anti-inflammatory response present throughout sepsis. Multiple immunomodulating agents have been studied to combat the immunosuppressive phase of sepsis with the goal of decreasing secondary infection, reducing organ dysfunction, decreasing ICU stays, and improving survival. Granulocyte-macrophage colony stimulating factor (GM-CSF), a myelopoietic growth factor currently used in patients with neutropenia secondary to chemotherapy-induced myelosuppression, has been studied as a potential immune-activating agent. The applicability of GM-CSF as a standard therapy for generalized sepsis is still largely understudied; however, small-scale studies available have demonstrated some improved recovery from infection, decreased hospital length of stay, decreased days requiring mechanical ventilation, and decreased medical costs.

Persistent lymphopenia after diagnosis of sepsis predicts mortality

OBJECTIVE

The objective of this study was to determine whether persistent lymphopenia on the fourth day following the diagnosis of sepsis predicts mortality.

METHODS

This was a single-center, retrospective cohort study of 335 adult patients with bacteremia and sepsis admitted to a large university-affiliated tertiary care hospital between January 1, 2010, and July 31, 2012. All complete blood cell count profiles during the first 4 days following the diagnosis of sepsis were recorded. The primary outcome was 28-day mortality. Secondary outcomes included development of secondary infections, 1-year mortality, and hospital and intensive care unit lengths of stay.

RESULTS

Seventy-six patients (22.7%) died within 28 days. Lymphopenia was present in 28-day survivors (median, 0.7 × 10 cells/μL; interquartile range [IQR], 0.4-1.1 × 10 cells/μL) and nonsurvivors (median, 0.6 × 10 cells/μL; IQR, 0.4-1.1 × 10 cells/μL) at the onset of sepsis and was not significantly different between the groups (P = 0.35). By day 4, the median absolute lymphocyte count was significantly higher in survivors compared with nonsurvivors (1.1 × 10 cells/μL [IQR, 0.7-1.5 × 10 cells/μL] vs. 0.7 × 10 cells/μL [IQR, 0.5-1.0 × 10 cells/μL]; P < 0.0001). Using logistic regression to account for potentially confounding factors (including age, Acute Physiology and Chronic Health Evaluation II score, comorbidities, surgical procedure during the study period, and time until appropriate antibiotic administration), day 4 absolute lymphocyte count was found to be independently associated with 28-day survival (adjusted odds ratio, 0.68 [95% confidence interval, 0.51-0.91]) and 1-year survival (adjusted odds ratio, 0.74 [95% confidence interval, 0.59-0.93]). Severe persistent lymphopenia (defined as an absolute lymphocyte count of 0.6 × 10 cells/μL or less on the fourth day after sepsis diagnosis) was associated with increased development of secondary infections (P = 0.04).

CONCLUSIONS

Persistent lymphopenia on the fourth day following the diagnosis of sepsis predicts early and late mortality and may serve as a biomarker for sepsis-induced immunosuppression.

Park7 interacts with p47(phox) to direct NADPH oxidase-dependent ROS production and protect against sepsis

Inappropriate inflammation responses contribute to mortality during sepsis. Through Toll-like receptors (TLRs), reactive oxygen species (ROS) produced by NADPH oxidase could modulate the inflammation responses. Parkinson disease (autosomal recessive, early onset) 7 (Park7) has a cytoprotective role by eliminating ROS. However, whether Park7 could modulate inflammation responses and mortality in sepsis is unclear. Here, we show that, compared with wild-type mice, Park7(-/-) mice had significantly increased mortality and bacterial burdens in sepsis model along with markedly decreased systemic and local inflammation, and drastically impaired macrophage phagocytosis and bacterial killing abilities. Surprisingly, LPS and phorbol-12-myristate-13-acetate stimulation failed to induce ROS and proinflammatory cytokine production in Park7(-/-) macrophages and Park7-deficient RAW264.7 cells. Through its C-terminus, Park7 binds to p47(phox), a subunit of the NADPH oxidase, to promote NADPH oxidase-dependent production of ROS. Restoration of Park7 expression rescues ROS production and improves survival in LPS-induced sepsis. Together, our study shows that Park7 has a protective role against sepsis by controlling macrophage activation, NADPH oxidase activation and inflammation responses.

An Endotoxin Tolerance Signature Predicts Sepsis and Organ Dysfunction at Initial Clinical Presentation

Background

Sepsis involves aberrant immune responses to infection, but the exact nature of this immune dysfunction remains poorly defined. Bacterial endotoxins like lipopolysaccharide (LPS) are potent inducers of inflammation, which has been associated with the pathophysiology of sepsis, but repeated exposure can also induce a suppressive effect known as endotoxin tolerance or cellular reprogramming. It has been proposed that endotoxin tolerance might be associated with the immunosuppressive state that was primarily observed during late-stage sepsis. However, this relationship remains poorly characterised. Here we clarify the underlying mechanisms and timing of immune dysfunction in sepsis.

Methods

We defined a gene expression signature characteristic of endotoxin tolerance. Gene-set test approaches were used to correlate this signature with early sepsis, both newly and retrospectively analysing microarrays from 593 patients in 11 cohorts. Then we recruited a unique cohort of possible sepsis patients at first clinical presentation in an independent blinded controlled observational study to determine whether this signature was associated with the development of confirmed sepsis and organ dysfunction.

Findings

All sepsis patients presented an expression profile strongly associated with the endotoxin tolerance signature (p < 0.01; AUC 96.1%). Importantly, this signature further differentiated between suspected sepsis patients who did, or did not, go on to develop confirmed sepsis, and predicted the development of organ dysfunction.

Interpretation

Our data support an updated model of sepsis pathogenesis in which endotoxin tolerance-mediated immune dysfunction (cellular reprogramming) is present throughout the clinical course of disease and related to disease severity. Thus endotoxin tolerance might offer new insights guiding the development of new therapies and diagnostics for early sepsis.

•

Addresses sepsis that affects up to 18 million persons annually with up to 5 million deaths worldwide.

•

Describes an endotoxin tolerance gene expression signature associated with consecutive treatments with endotoxin and reflecting cellular reprogramming.

•

Using a meta-analysis of the literature demonstrates the statistically significant association (p < 0.01; AUC 96.1%) of this endotoxin tolerance signature with early (day 1–3 after ICU admission) sepsis in 593 patients in 11 adult or child cohorts.

•

Demonstrates, at first clinical presentation, the ability of this signature to predict the eventual diagnosis of sepsis and organ failure in an independent blinded controlled observational study of a unique cohort of possible sepsis patients.

•

This study provides new insights that have the potential to guide the development of new therapies and diagnostics for early sepsis.

Preliminary results in quantitation of HLA-DRA by real-time PCR: a promising approach to identify immunosuppression in sepsis

INTRODUCTION

Reduced monocyte human leukocyte antigen (mHLA)-DR surface expression in the late phase of sepsis is postulated as a general biomarker of sepsis-induced immunosuppression and an independent predictor of nosocomial infections.

METHODS

Fifty-nine patients with sepsis and blood culture growing pathogenic bacteria were studied. Blood samples were collected at day 1 or 2 after admission, for measurement of mHLA-DR by flow cytometry and mRNA expression of HLA-DRA and class II transactivator (CIITA) by qRT-PCR. Blood samples from blood donors were used as controls (n = 30).

RESULTS

A significant reduced expression of mHLA-DR, HLA-DRA, and CIITA was seen in septic patients compared with controls. HLA-DRA mRNA level in whole blood was highly correlated with surface expression of mHLA-DR.

CONCLUSIONS

Patients with sepsis display a diminished expression of HLA-DR at the monocyte surface as well as in the gene expression at the mRNA level. The mRNA expression level of HLA-DRA monitored by qRT-PCR correlates highly with surface expression of HLA-DR and appears to be a possible future biomarker for evaluation of immunosuppression in sepsis.

Systemic varicella-zoster virus infection in two critically ill patients in an intensive care unit

Varicella-zoster virus (VZV) usually causes localized zoster in adults. However, in immunocompromised patients, it can cause systemic infection accompanied by complications such as pneumonia, encephalitis, and hepatitis. Although most of critically ill patients in intensive care unit (ICU) are immunologically compromised, they are usually not considered to be at risk for systemic VZV infection.We report two cases of systemic VZV infection occurring in critically ill patients in an ICU. One patient was a 69-year-old man with Streptococcus pneumoniae-induced purpurafulminans, and the other was a 75-year-old woman with severe acute pancreatitis. During the clinical course in the ICU, characteristic vesicles with umbilical fossa appeared diffusely and bilaterally on their face, trunk, and extremities. VZV-specific IgG levels were confirmed to be elevated compared to that of the pre-onset, and a diagnosis of recurrent VZV infection was made in both patients. The patients were treated at the same ICU but did not coincide with each other; therefore a cross-infection was unlikely. They were treated with intravenous acyclovir, but the latter patient eventually died of respiratory failure.VZV infection can cause a number of serious complications, and can lead to death in some patients. Early detection and proper treatment are needed to prevent the infection from spreading out and save the patients. It might be necessary to consider antiviral prophylaxis against VZV infection for a part of critically ill patients in ICU, although the effectiveness of this approach is yet to be established.

In vivo effect of recombinant human granulocyte colony-stimulating factor on neutrophilic expression of CD11b in septic neonates: a randomized controlled trial

Neonates are susceptible to septicemia secondary to quantitative and qualitative neutrophilic defects. Granulocyte colony-stimulating factor (G-CSF) stimulates myeloid progenitor cell proliferation and induces selective neutrophil functions. The authors aimed to evaluate the effect of G-CSF administration in septic neonates on neutrophil production and CD11b expression. Sixty septic neonates were randomized to receive intravenous G-CSF 10 μg/kg/day for 3 days (G-CSF group, n = 30), or not to receive G-CSF (non-G-CSF group, n = 30). Thirty healthy newborns were included as controls. Laboratory investigations included complete blood count, C-reactive protein, blood culture, renal and liver function tests, and assessment of neutrophilic expression of CD11b. Total leukocytes count (TLC), absolute neutrophil count (ANC), and immature myeloid cell count in G-CSF group showed significant difference between post-and pre-G-CSF levels. TLC, ANC, immature myeloid cell count and immature/total myeloid cells ratio were higher in G-CSF group compared to non-G-CSF group on days 1 and 3. Higher neutrophilic expression of CD11b was reported in both septic groups on day 0 compared to control group. On day 5, CD11b was higher in G-CSF group than non-G-CSF group. G-CSF improved CD11b% in neutropenic and non-neutropenic septic neonates. No significant difference was found between pre- and posttreatment renal and liver function tests. Lower duration of antibiotic intake and hospitalization was observed in G-CSF group compared to non-G-CSF group. G-CSF administration as an adjuvant therapy for neonatal septicemia, whether neutropenic or not, improves neutrophilic count and function and contributed to early healing from sepsis.

[Reversing ICU-acquired immunosuppression: an innovative biomarker-guided therapeutic strategy for decreasing sepsis mortality and nosocomial infection rate]

Septic syndromes (systemic inflammatory response associated with infection) remain a major although largely under-recognized health care problem and represent the first cause of mortality in intensive care units. Regarding immune response, it is now agreed that sepsis induces an anti-inflammatory process, acting as a negative feedback. This inhibitory mechanism becomes deleterious as nearly all immune functions are rapidly compromised. The magnitude and persistence over time of this immunosuppression is correlated with nosocomial infections and mortality. Decreased HLA-DR expression on monocytes/increased percentage of regulatory T cells are biomarkers identifying patients at risk who could benefit from immunotherapy. This review attempts to integrate these new facts into an up-to-date account of sepsis pathophysiology.

Induction of endotoxin tolerance in vivo inhibits activation of IRAK4 and increases negative regulators IRAK-M, SHIP-1, and A20

TLRs mediate host defense against microbial pathogens by eliciting production of inflammatory mediators and activating expression of MHC, adhesion, and costimulatory molecules. Endotoxin tolerance limits excessive TLR-driven inflammation during sepsis and reprograms macrophage responses to LPS, decreasing expression of proinflammatory cytokines without inhibiting anti-inflammatory and antimicrobial mediators. Molecular mechanisms of reprogramming of TLR4 signaling upon in vivo induction of endotoxin tolerance are incompletely understood. We used an in vivo model of endotoxin tolerance, whereby C57BL/6 mice were i.p.-inoculated with LPS or PBS, followed by in vitro challenge of peritoneal or splenic macrophages with LPS to examine activation of IRAK4 and expression of negative regulatory molecules. Administration of LPS in vivo-induced endotoxin tolerance in peritoneal and splenic macrophages, as evidenced by decreased degradation of IκBα, suppressed phosphorylation of p38 and reduced expression of TNF-α, IL-6, and KC mRNA upon in vitro LPS challenge. Macrophages from control and endotoxin-tolerant mice exhibited comparable TLR4 mRNA levels and similar expression of IL-1RA and IL-10 genes. Endotoxin tolerization in vivo blocked TLR4-driven IRAK4 phosphorylation and activation in macrophages, while increasing expression of IRAK-M, SHIP-1, A20 mRNA, and A20 protein. Thus, induction of endotoxin tolerance in vivo inhibits expression of proinflammatory mediators via impaired activation of IRAK4, p38, and NF-κB and increases expression of negative regulators of TLR4 pathways.

LPS pretreatment ameliorates multiple organ injuries and improves survival in a murine model of polymicrobial sepsis

OBJECTIVE

The endotoxin tolerance phenotype is characterized with decreased inflammation and increased phagocytosis. We hypothesized that endotoxin tolerance would provide protective effects on experimental sepsis with multiple organ injuries induced by cecal ligation and puncture (CLP).

METHODS

Endotoxin tolerance was induced in male Sprague-Dawley rats with daily intraperitoneal injection of either 0.6 mg/kg of lipopolysaccharide (LPS) or vehicle for four consecutive days before subsequent CLP. Biochemical parameters, histological changes, inflammatory cytokine production, and lung tissue nuclear factor-κB (NF-κB) activation were assessed post-CLP. In a separate experiment, survival rate was monitored for 7 days after CLP.

RESULTS

In vehicle-treated animals, CLP caused multiple organ injuries confirmed by the biochemical variables and histological examination. This was accompanied by an early activation of NF-κB in the lung and a substantial increase in plasma levels of tumor necrosis factor-α, interleukin-6, and interleukin-10. In contrast, pretreatment with LPS not only alleviated the development of multiple organ injuries after CLP, but also decreased sepsis-induced activation of pulmonary NF-κB and reduced plasma cytokines production. In addition, LPS pretreatment improved the survival in rats subjected to CLP.

CONCLUSIONS

The beneficial effects of endotoxin tolerance indicate the potential of immunomodulatory strategies in the management of severe sepsis.

Immunostimulation using granulocyte- and granulocyte-macrophage colony stimulating factor in patients with severe sepsis and septic shock

Sepsis is associated with failure of multiple organs, including failure of the immune system. The resulting 'sepsis-associated immunosuppression' resembles a state of immunological anergy that is characterized by repeated 'infectious hits', prolonged multiple-organ failure, and death. As a consequence, adjunctive treatment approaches using measures of immunostimulation with colony-stimulating factors (CSFs) were tested in animal experiments and clinical trials. Herein, data from randomized clinical trials will be discussed in the context of a recently published meta-analysis investigating the effects of granulocyte- and granulocyte-macrophage colony-stimulating factor therapy in patients with severe sepsis and septic shock.

Granulocyte-colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF) for sepsis: a meta-analysis

Introduction

To investigate the effects of G-CSF or GM-CSF therapy in non-neutropenic patients with sepsis.

Methods

A systematic literature search of Medline, Embase and Cochrane Central Register of Controlled Trials was conducted using specific search terms. A manual review of references was also performed. Eligible studies were randomized control trials (RCTs) that compared granulocyte-colony stimulating factor (G-CSF) or granulocyte-macrophage colony stimulating factor (GM-CSF) therapy with placebo for the treatment of sepsis in adults. Main outcome measures were all-cause mortality at 14 days and 28 days after initiation of G-CSF or GM-CSF therapy, in-hospital mortality, reversal rate from infection, and adverse events.

Results

Twelve RCTs with 2,380 patients were identified. In regard to 14-day mortality, a total of 9 death events occurred among 71 patients (12.7%) in the treatment group compared with 13 events among 67 patients (19.4%) in the placebo groups. Meta-analysis showed there was no significant difference in 28-day mortality when G-CSF or GM-CSF were compared with placebo (relative risks (RR) = 0.93, 95% confidence interval (CI): 0.79 to 1.11, P = 0.44; P for heterogeneity = 0.31, I² = 15%). Compared with placebo, G-CSF or GM-CSF therapy did not significantly reduce in-hospital mortality (RR = 0.97, 95% CI: 0.69 to 1.36, P = 0.86; P for heterogeneity = 0.80, I² = 0%). However, G-CSF or GM-CSF therapy significantly increased the reversal rate from infection (RR = 1.34, 95% CI: 1.11 to 1.62, P = 0.002; P for heterogeneity = 0.47, I² = 0%). No significant difference was observed in adverse events between groups (RR = 0.93, 95% CI: 0.70 to 1.23, P = 0.62; P for heterogeneity = 0.03, I² = 58%). Sensitivity analysis by excluding one trial did not significantly change the results of adverse events (RR = 1.05, 95% CI: 0.84 to 1.32, P = 0.44; P for heterogeneity = 0.17, I² = 36%).

Conclusions

There is no current evidence supporting the routine use of G-CSF or GM-CSF in patients with sepsis. Large prospective multicenter clinical trials investigating monocytic HLA-DR (mHLA-DR)-guided G-CSF or GM-CSF therapy in patients with sepsis-associated immunosuppression are warranted.

Intensive care unit-acquired weakness (ICUAW) and muscle wasting in critically ill patients with severe sepsis and septic shock

Sepsis presents a major health care problem and remains one of the leading causes of death within the intensive care unit (ICU). Therapeutic approaches against severe sepsis and septic shock focus on early identification. Adequate source control, administration of antibiotics, preload optimization by fluid resuscitation and further hemodynamic stabilisation using vasopressors whenever appropriate are considered pivotal within the early-golden-hours of sepsis. However, organ dysfunction develops frequently in and represents a significant comorbidity of sepsis. A considerable amount of patients with sepsis will show signs of severe muscle wasting and/or ICU-acquired weakness (ICUAW), which describes a frequently observed complication in critically ill patients and refers to clinically weak ICU patients in whom there is no plausible aetiology other than critical illness. Some authors consider ICUAW as neuromuscular organ failure, caused by dysfunction of the motor unit, which consists of peripheral nerve, neuromuscular junction and skeletal muscle fibre. Electrophysiologic and/or biopsy studies facilitate further subclassification of ICUAW as critical illness myopathy, critical illness polyneuropathy or critical illness myoneuropathy, their combination. ICUAW may protract weaning from mechanical ventilation and impede rehabilitation measures, resulting in increased morbidity and mortality. This review provides an insight on the available literature on sepsis-mediated muscle wasting, ICUAW and their potential pathomechanisms.

IFN-γ abrogates endotoxin tolerance by facilitating Toll-like receptor-induced chromatin remodeling

An important mechanism by which IFN-γ primes macrophages for enhanced innate immune responses is abrogation of feedback inhibitory pathways. Accordingly, IFN-γ abrogates endotoxin tolerance, a major negative feedback loop that silences expression of inflammatory cytokine genes in macrophages previously exposed to endotoxin/Toll-like receptor (TLR) ligands. Mechanisms by which IFN-γ inhibits endotoxin tolerance have not been elucidated. Here, we show that pretreatment with IFN-γ prevented tolerization of primary human monocytes and restored TLR4-mediated induction of various proinflammatory cytokines, including IL-6 and TNFα. Surprisingly, IFN-γ did not alter proximal TLR4 signaling defects in tolerized monocytes. Instead, IFN-γ blocked tolerance-associated down-regulation of IL6 and TNF transcription, RNA polymerase II recruitment, and NF-κB and CCAAT/enhancer-binding protein β transcription factor binding to the IL6 and TNF promoters in tolerized monocytes. The mechanism by which IFN-γ restored IL6 expression was by facilitating TLR4-induced recruitment of chromatin remodeling machinery to the IL6 promoter and promoting IL6 locus accessibility in tolerized monocytes. Our results suggest that IFN-γ overcomes endotoxin tolerance by facilitating TLR-induced chromatin remodeling to allow expression of proinflammatory genes. These results identify a mechanism by which IFN-γ promotes activation of macrophages and highlight the importance of chromatin remodeling and transcriptional control in the regulation of inflammatory cytokine production in tolerant and activated macrophages.

Low monocyte human leukocyte antigen-DR is independently associated with nosocomial infections after septic shock

PURPOSE

Sepsis-induced immunosuppression is postulated to contribute to a heightened risk of nosocomial infection (NI). This prospective, single-center, observational study was conducted to assess whether low monocyte human leukocyte antigen-DR expression (mHLA-DR), proposed as a global biomarker of sepsis immunosuppression, was associated with an increased incidence of NI after septic shock.

METHODS

The study included 209 septic shock patients. mHLA-DR was measured by flow cytometry at days (D) 3-4 and 6-9 after the onset of shock. After septic shock, patients were screened daily for NI at four sites (microbiologically documented pulmonary, urinary tract, bloodstream, and catheter-related infections). A competing risk approach was used to evaluate the impact of low mHLA-DR on the incidence of NI.

RESULTS

At D3-4, we obtained measurements in 153 patients. Non-survivors (n = 51) exhibited lower mHLA-DR values expressed as means of fluorescence intensities than survivors (n = 102) (33 vs. 67; p < 0.001). The patients who developed NI (n = 37) exhibited lower mHLA-DR values than those without NI (n = 116) (39 vs. 65; p = 0.008). mHLA-DR ≤ 54 remained independently associated with NI occurrence after adjustment for clinical parameters (gender, simplified acute physiology score II, sepsis-related organ failure assessment, intubation, and central venous catheterization) with an adjusted hazards ratio (aHR) of 2.52 (95% CI 1.20-5.30); p = 0.02. Similarly, at D6-9, low mHLA-DR (≤ 57) remained independently associated with NI with an aHR of 2.18 (95% CI 1.04-4.59); p = 0.04.

CONCLUSIONS

In septic shock patients, after adjustment with usual clinical confounders (including ventilation and central venous catheterization), persistent low mHLA-DR expression remained independently associated with the development of secondary NI.

High-mobility group box-1 protein serum levels do not reflect monocytic function in patients with sepsis-induced immunosuppression

BACKGROUND

High-mobility group box-1 (HMGB-1) protein is released during "late sepsis" by activated monocytes. We investigated whether systemic HMGB-1 levels are associated with indices of monocytic activation/function in patients with sepsis-induced immunosuppression.

METHODOLOGY

36 patients (31 male, 64 +/- 14 years) with severe sepsis/septic shock and monocytic deactivation (reduced mHLA-DR expression and TNF-alpha release) were assessed in a subanalysis of a placebo-controlled immunostimulatory trial using GM-CSF. HMGB-1 levels were assessed over a 9-day treatment interval. Data were compared to standardized biomarkers of monocytic immunity (mHLA-DR expression, TNF-alpha release).

PRINCIPLE FINDINGS

HMGB-1 levels were enhanced in sepsis but did not differ between treatment and placebo groups at baseline (14.6 +/- 13.5 versus 12.5 +/- 11.5 ng/ml, P = .62). When compared to controls, HMGB-1 level increased transiently in treated patients at day 5 (27.8 +/- 21.7 versus 11.0 +/- 14.9, P = .01). Between group differences were not noted at any other point of assessment. HMGB-1 levels were not associated with markers of monocytic function or clinical disease severity.

CONCLUSIONS

GM-CSF treatment for sepsis-induced immunosuppression induces a moderate but only transient increase in systemic HMGB-1 levels. HMGB-1 levels should not be used for monitoring of monocytic function in immunostimulatory trials as they do not adequately portray contemporary changes in monocytic immunity.

Treatment with granulocyte-macrophage colony-stimulating factor is associated with reduced indoleamine 2,3-dioxygenase activity and kynurenine pathway catabolites in patients with severe sepsis and septic shock

The immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO) controls tryptophan metabolism and is induced by pro-inflammatory stimuli. We investigated whether immunostimulatory treatment with granulocyte-macrophage colony-stimulating factor (GM-CSF) influences IDO activity and tryptophan metabolism in sepsis. Thirty-six patients with severe sepsis/septic shock and sepsis-associated immunosuppression (assessed using monocytic human leukocyte antigen-DR (mHLA-DR) expression) were assessed in a controlled trial of GM-CSF or placebo treatment for 8 days. Using tandem mass spectrometry, levels of tryptophan, kynurenine, kynurenic acid, quinolinic acid, 5-hydroxytryptophan, serotonin, and estimated IDO activity were determined in a blinded fashion over a 9-day interval. At baseline, tryptophan and metabolite levels did not differ between the study groups. Although tryptophan levels were unchanged in both groups over the treatment interval (all p>0.8), IDO activity was markedly reduced after GM-CSF treatment (35.4 +/- 21.0 vs 21.6 +/-9.9 (baseline vs day 9), p = 0.02). IDO activity differed significantly between the 2 groups after therapy (p = 0.03). Metabolites downstream of IDO (kynurenine, quinolinic acid, kynurenic acid) were all induced in sepsis and declined in the GM-CSF group, but not in controls. Serotonin pathway metabolites remained unchanged in both groups (all p>0.15). Moreover, IDO activity correlated with procalcitonin (p< 0.0001, r = 0.56) and mHLA-DR levels (p = 0.005, r = -0.28) in the overall samples group. Thus, GM-CSF therapy is associated with decreased IDO activity and reduced kynurenine pathway catabolites in sepsis. This may be due to an improved antibacterial defence.

Therapeutic strategies targeting the LPS signaling and cytokines

Lipopolysaccharide (LPS) has been recognized as a major player in the pathogenesis of sepsis and neutralization of LPS or inhibition of its signal transduction mechanism is promising new treatment strategy in preclinical experiments. However, these therapeutic approaches have been shown unsuccessful in clinical trials. LPS activates Toll-like receptor 4 (TLR4) and induces pro-inflammatory and anti-inflammatory responses, the altered innate and adaptive immune responses eventually lead to the immunosuppressive state. The future therapeutic efforts in sepsis should focus on the immunosuppressive state. In this article, we will outline the current data on therapeutic strategies targeting LPS, TLR4 and single cytokine in sepsis and discuss the experimental and clinical evaluation of the immunomodulatory action of glycine and berberine. While we have demonstrated berberine in combination with yohimbine can modulate host immune responses in endotoxemia, it seems worthwhile to conduct clinical trials on the safe and efficacy of this new immunomodulatory therapy.

Phenotype changes and impaired function of dendritic cell subsets in patients with sepsis: a prospective observational analysis

INTRODUCTION

Patients with sepsis often demonstrate severely impaired immune responses. The hallmark of this state of immunoparalysis is monocytic deactivation characterized by decreased human leukocyte antigen (HLA)-DR expression and reduced production of proinflammatory cytokines. Recently, diminished numbers of dendritic cells (DCs) were reported in patients with sepsis. However, little is known about DC phenotype and function in human sepsis. We therefore compared phenotypic and functional changes in monocyte and DC subsets in patients with sepsis and immunoparalysis.

METHODS

In a prospective observational analysis, 16 consecutive patients with severe sepsis and septic shock (age 59.2 +/- 9.7 years, 13 male, Sequential Organ Failure Assessment score 6.1 +/- 2.7) and immunoparalysis (monocytic HLA-DR expression < 5,000 antibodies/cell) and 16 healthy volunteers were included. Peripheral blood DC counts, HLA-DR expression and ex vivo cytokine production were evaluated in comparison with monocyte subsets over time.

RESULTS

At baseline, a profound reduction in the numbers of myeloid DCs (MDCs), plasmacytoid DCs (PDCs), and CD14dimCD16positive monocytes was observed in sepsis whereas CD14brightCD16negative and CD14brightCD16positive monocyte numbers were increased. HLA-DR expression was reduced on all monocyte and DC subsets. Production of proinflammatory cytokines and intracellular cytokine staining in response to lipopolysaccharide and lipoteichoic acid was impaired in monocyte subsets and MDCs, whereas IL-10 secretion was increased. IFNalpha response by stimulated PDCs was significantly decreased compared with controls. At day 28, HLA-DR expression and cytokine production of DC and monocyte subsets remained lower in septic patients compared with controls.

CONCLUSIONS

In sepsis, long-lasting functional deactivation is common to all circulating monocyte and DC subsets. In addition to decreased peripheral blood DC counts, functional impairment of antigen-presenting cells may contribute to an impaired antimicrobial defense in sepsis.

Granulocyte-macrophage colony-stimulating factor to reverse sepsis-associated immunosuppression: a double-blind, randomized, placebo-controlled multicenter trial

RATIONALE

Sustained sepsis-associated immunosuppression is associated with uncontrolled infection, multiple organ dysfunction, and death.

OBJECTIVES

In the first controlled biomarker-guided immunostimulatory trial in sepsis, we tested whether granulocyte-macrophage colony-stimulating factor (GM-CSF) reverses monocyte deactivation, a hallmark of sepsis-associated immunosuppression (primary endpoint), and improves the immunological and clinical course of patients with sepsis.

METHODS

In a prospective, randomized, double-blind, placebo-controlled, multicenter trial, 38 patients (19/group) with severe sepsis or septic shock and sepsis-associated immunosuppression (monocytic HLA-DR [mHLA-DR] <8,000 monoclonal antibodies (mAb) per cell for 2 d) were treated with GM-CSF (4 microg/kg/d) or placebo for 8 days. The patients' clinical and immunological course was followed up for 28 days.

MEASUREMENTS AND MAIN RESULTS

Both groups showed comparable baseline mHLA-DR levels (5,609 +/- 3,628 vs. 5,659 +/- 3,332 mAb per cell), which significantly increased within 24 hours in the GM-CSF group. After GM-CSF treatment, mHLA-DR was normalized in 19/19 treated patients, whereas this occurred in 3/19 control subjects only (P < 0.001). GM-CSF also restored ex-vivo Toll-like receptor 2/4-induced proinflammatory monocytic cytokine production. In patients receiving GM-CSF, a shorter time of mechanical ventilation (148 +/- 103 vs. 207 +/- 58 h, P = 0.04), an improved Acute Physiology and Chronic Health Evaluation-II score (P = 0.02), and a shorter length of both intrahospital and intensive care unit stay was observed (59 +/- 33 vs. 69 +/- 46 and 41 +/- 26 vs. 52 +/- 39 d, respectively, both not significant). Side effects related to the intervention were not noted.

CONCLUSIONS

Biomarker-guided GM-CSF therapy in sepsis is safe and effective for restoring monocytic immunocompetence. Use of GM-CSF may shorten the time of mechanical ventilation and hospital/intensive care unit stay. A multicenter trial powered for the improvement of clinical parameters and mortality as primary endpoints seems indicated. Clinical trial registered with www.clinicaltrials.gov (NCT00252915).