Monitoring temporary immunodepression by flow cytometric measurement of monocytic HLA-DR expression: a multicenter standardized study

A New Easy-to-Perform Flow Cytometry Assay for Determining Bacterial- and Viral-Infection-Induced Polymorphonuclear Neutrophil and Monocyte Membrane Marker Modulation in Febrile Patients

We developed a flow cytometry (FC) assay enabling the rapid and accurate identification of bacterial and viral infections using whole blood samples. The streamlined flow cytometry assay is designed to be user-friendly, making it accessible even for operators with limited experience in FC techniques. The key components of the assay focus on the expression levels of specific surface markers-CD64 on polymorphonuclear neutrophils (PMN) as a marker for bacterial infection, and CD169 on monocytes (MO) for viral infection. The strong performance indicated by an area under the receiver operating characteristic (ROC) curve of 0.94 for both PMN CD64 positive predictive value (PPV) 97.96% and negative predictive value (NPV) 76.67%, and MO CD169 PPV 82.6% and NPV 86.9%, highlight the assay's robustness in differentiating between bacterial and viral infections accurately. The FC assay includes the assessment of immune system status through HLA-DR and IL-1R2 modulation in MO, providing a useful insight into the patients' immune response. The significant increase in the frequency of MO exhibiting reduced HLA-DR expression and elevated IL-1R2 levels in infected patients (compared to healthy controls) underscores the potential of these markers as indicators of infection severity. Although the overall correlation between HLA-DR and IL-1R2 expression levels was not significant across all patients, there was a trend in patients with more severe disease suggesting that these markers may have the potential to assist in stratifying patient risk. The present FC assay has the potential to become routine in the clinical microbiology laboratory community and to be helpful in guiding clinical decision making.

Monocytes as Targets for Immunomodulation by Regional Citrate Anticoagulation

Immune alterations in end-stage renal patients receiving hemodialysis are complex and predispose patients to infections. Anticoagulation may also play an immunomodulatory role in addition to the accumulation of uremic toxins and the effects of the dialysis procedure. Accordingly, it has been recently shown that the infection rate increases in patients under regional citrate anticoagulation (RCA) compared with systemic heparin anticoagulation (SHA). We hypothesized that RCA affects the immune status of hemodialysis patients by targeting monocytes. In a cohort of 38 end-stage renal patients undergoing hemodialysis, we demonstrated that whole blood monocytes of patients receiving RCA-but not SHA-failed to upregulate surface activation markers, like human leukocyte antigen class II (HLA-DR), after stressful insults, indicating a state of deactivation during and immediately after dialysis. Additionally, RNA sequencing (RNA-seq) data and gene set enrichment analysis of pre-dialysis monocytes evidenced a great and complex difference between the groups given that, in the RCA group, monocytes displayed a dramatic transcriptional change with increased expression of genes related to the cell cycle regulation, cellular metabolism, and cytokine signaling, compatible with the reprogramming of the immune response. Transcriptomic changes in pre-dialysis monocytes signalize the lasting nature of the RCA-related effects, suggesting that monocytes are affected even beyond the dialysis session. Furthermore, these findings demonstrate that RCA-but not SHA-impairs the response of monocytes to activation stimuli and alters the immune status of these patients with potential clinical implications.

Whole blood no-lyse no-wash micromethod for the quantitative measurement of monocyte HLA-DR

BACKGROUND

Monocyte (m)HLA-DR expression appears to be a potent marker of immunosuppression in critically ill patients. The persistence of low mHLA-DR expression is associated with an increased risk of nosocomial infections and mortality. To adapt this measurement to pediatric requirements and provide extensive 24/7 access, we have developed a whole blood no-lyse no-wash micromethod (MM) and compared it with the standardized method (SM).

METHODS

mHLA-DR was quantified by flow cytometry using Quantibrite™ Anti-HLA-DR PE/Monocyte PerCP-Cy™5.5 with either the SM performed in a diagnostic hematology laboratory using manufacturer protocol, or a whole blood no-lyse no-wash MM using an Attune flow cytometer located in the pediatric ICU. Median fluorescence intensity was measured in both techniques and converted to antibodies per cell (AB/C) calibrated with BD Quantibrite™ PE beads. Blood and Quantibrite™ reagent volume used with the MM was reduced by 5-fold compared to SM. In addition to Quantibrite™ Anti-Human HLA-DR PE/Monocyte PerCP-Cy™5.5, MM required anti-CD45 and anti-CD19 labeling.

RESULTS

We determined the expression of mHLA-DR in 34 patients, 20 adults, and 14 children admitted to ICU. Correlation between MM and SM was excellent (Pearson's correlation: y = 0.8192x + 678.7, r = 0.9270, p < 0.0001). The estimated bias was 2467 ± 1.96 × 3307 AB/C; CI 95% [-4016; +8949].

CONCLUSIONS

The no-lyse no-wash whole blood microvolume method for measuring mHLA-DR expression allows for simplified sample preparation without compromising accuracy of the data. This method may simplify immune monitoring of critically ill patient by the deployment of a point of care method.

Evaluation of HLA-DR expression in monocytes and CD64 in neutrophils as A predictor of SEPSIS/sirs in the infectious-inflammatory process

Sepsis is a highly fatal disease that affects millions of people worldwide every year. Currently, the diagnosis of sepsis is made by identifying at least two symptoms of systemic inflammatory response syndrome (SIRS), along with confirming the presence of microorganisms using a blood culture examination. Some biomarkers are already used to aid in the diagnosis, such as increased levels of C-reactive protein (CRP), leukocytes, immature granulocytes (IG), and bands. In addition, studies have shown a relationship between the expression of certain antigen receptors in the body's defense cells and its infectious state. CD64 is a receptor expressed in monocytes, and, in cases of infection, its expression is strongly observed in neutrophils. On the other hand, the class II MHC (major histocompatibility complex) marker, HLA-DR (human leukocyte antigen-DR), decreases its expression in monocytes in response to infection. This cohort study was conducted with 77 adult patients from a university hospital, divided into two groups: Non-Sepsis/SIRS and Sepsis/SIRS. The selected samples were analyzed by flow cytometry, identifying the expression of CD64 and HLA-DR according to their MFI, and calculating the sepsis index (SI) for each patient. All three parameters exhibited significant differences in expression between the two groups. When compared to the laboratory tests already in use, the utilization of HLA-DR, CD64, and the new index has shown greater sensitivity and specificity in identifying sepsis. This study contributes to knowledge about the relationship between the expression of antigens on defense cells and sepsis. The use of these biomarkers can help to improve the diagnosis and treatment of sepsis, which may contribute to the reduction of mortality related to the disease.

Inflammatory biomarkers to predict the prognosis of acute bacterial and viral infections

Mortality in acute infections is mostly associated with sepsis, defined as 'life-threatening organ dysfunction caused by a dysregulated host response to infection'. It remains challenging to identify the patients with increased mortality risk due to the high heterogeneity in the dysregulated host immune response and disease progression. Biomarkers reflecting different pathways involved in the inflammatory response might improve prediction of mortality risk (prognostic enrichment) among patients with acute infections by reducing heterogeneity of the host response, as well as suggest novel strategies for patient stratification and treatment (predictive enrichment) through precision medicine approaches. The predictive value of inflammatory biomarkers has been extensively investigated in bacterial infections and the recent COVID-19 pandemic caused an increased interest in inflammatory biomarkers in this viral infection. However, limited research investigated whether the prognostic potential of these biomarkers differs between bacterial and viral infections. In this narrative review, we provide an overview of the value of various inflammatory biomarkers for the prediction of mortality in bacterial and viral infections.

Elevated monocyte HLA-DR in pediatric secondary hemophagocytic lymphohistiocytosis: a retrospective study

Introduction

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition, and its diagnosis may be challenging. In particular, some cases show close similarities to sepsis (fever, organ failure, and high ferritin), but their treatment, while urgent, differ: prompt broad-spectrum antibiotherapy for sepsis and immunosuppressive treatment for HLH. We questioned whether monocyte human leucocyte antigen (mHLA)-DR could be a diagnostic marker for secondary HLH (sHLH).

Methods

We retrospectively reviewed data from patients with a sHLH diagnosis and mHLA-DR quantification. mHLA-DR data from healthy children and children with septic shock, whose HLA-DR expression is reduced, from a previously published study were also included for comparison.

Results

Six patients with sHLH had mHLA-DR quantification. The median level of monocyte mHLA-DR expression in patients with sHLH [79,409 antibodies bound per cell (AB/C), interquartile range (IQR) (75,734-86,453)] was significantly higher than that in healthy children and those with septic shock (29,668 AB/C, IQR (24,335-39,199), and 7,493 AB/C, IQR (3,758-14,659), respectively). Each patient with sHLH had a mHLA-DR higher than our laboratory normal values. Four patients had a second mHLA-DR sampling 2 to 4 days after the initial analysis and treatment initiation with high-dose corticosteroids; for all patients, mHLA-DR decreased to within or close to the normal range. One patient with systemic juvenile idiopathic arthritis had repeated mHLA-DR measurements over a 200-day period during which she underwent four HLH episodes. mHLA-DR increased during relapses and normalized after treatment incrementation.

Conclusion

In this small series, mHLA-DR was systematically elevated in patients with sHLH. Elevated mHLA-DR could contribute to sHLH diagnosis and help earlier distinction with septic shock.

Blood Immune Cells as Biomarkers in Long-Term Surviving Patients with Advanced Non-Small-Cell Lung Cancer Undergoing a Combined Immune/Chemotherapy

An important challenge remains in identifying the baseline characteristics of cancer patients who will mostly benefit from immune checkpoint inhibitor (ICI) therapies. Furthermore, biomarkers could help in the choice of an optimal therapy duration after a primary therapy response. In this pilot study, the time courses of four different immune cell parameters were followed in 12 patients with advanced non-small-cell lung cancer (NSCLC) undergoing ICI therapy combined with chemotherapy and surviving at least 12 months. Blood was collected at the time point of the first and third antibody administration, as well as after 12 months of patients' survival. Using multi-color flow cytometry, two suppressive markers (neutrophil/lymphocyte ratio (NLR) and the frequency of circulating HLA-DRlow monocytes), as well as two markers of an ongoing immune response (6-Sulfo LacNAc (slan)+ non-classical monocytes and dendritic cell (DC) subtypes), were determined. In most of those who survived > 12 months, a low NLR and a low number of HLA-DRlow monocytes combined with clearly detectable numbers of slan+ non-classical monocytes and of DC subtypes were seen. Two of the patients had an increase in the suppressive markers paired with a decrease in slan+ non-classical monocytes and in DC subtypes, which, in at least one patient, was the correlate of an ongoing clinical progression. Our results implicate that the NLR, specific subtypes of monocytes, and the number of blood DCs might be useful predictive biomarkers for cancer patients during long-term treatment with ICI/chemotherapy.

Role of dexmedetomidine in modifying immune paralysis in patients with septic shock: randomized controlled trial

BACKGROUND

Immune paralysis can be defined as a hypoinflammatory state associated with the incapacity of the immune system to release proinflammatory mediators despite the clearance of pathogens by antimicrobials. Persistent immune paralysis leads to failure to eradicate primary infections with a substantial increase in the risk of multiorgan dysfunction and mortality. The state of immune paralysis is caused mainly by the diminished ability of monocytes to release proinflammatory cytokines in response to endotoxin. This phenomenon is known as endotoxin tolerance. This study aimed to assess the role of dexmedetomidine in modifying immune paralysis in septic shock patients.

METHODS

Twenty-four patients with septic shock were randomized into two groups of 12 patients. A continuous intravenous infusion of dexmedetomidine started at 0.15 µg kg-1 hr-1 and adjusted by 0.15 µg kg-1 h-1 to a maximum of 0.75 µg kg-1 h-1 (10 ml h-1), while midazolam was started at 1 mg h-1 (2 mL hr-1) and adjusted by 1 mg h-1 to a maximum of 5 mg h-1 (10 mL h-1). All infusions were adjusted by increments of 2 mL/hr-1 to maintain blinding. Serum levels of CD42a+/CD14+, HLADR+/CD14+, CRP, IL-6, IL-10 and TNF-α were measured at baseline (T1), 12 h (T2), and 24 h (T3).

RESULTS

Treatment with dexmedetomidine yielded no significant difference in CD42a+/CD14+, HLADR+/CD14, CD24b-MFI, HLADR-MFI, IL6 and TREM1 at all time points when compared with midazolam treatment. There was no significant difference in TLR levels between the two groups. Cardiac output in the dexmedetomidine group showed a significant decrease at 6, 12 and 24 h (P = 0.033, 0.021, and 0.005, respectively) compared with that in the midazolam group.

CONCLUSION

Our results indicated that dexmedetomidine did not affect CD42a+/CD14+ and HLA-DR+/CD14+ expression in septic patients. Furthermore, cytokine production and inflammatory biomarkers did not change with dexmedetomidine infusion. Trial registration Clinical trial.gov registry (NCT03989609) on June 14, 2019, https://register.

CLINICALTRIALS

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Staphylococcus aureus induces tolerance in human monocytes accompanied with expression changes of cell surface markers

Exposure of human monocytes to lipopolysaccharide (LPS) or other pathogen-associated molecular pattern (PAMPs) induces a temporary insensitivity to subsequent LPS challenges, a cellular state called endotoxin tolerance (ET), associated with the pathogenesis of sepsis. In this study, we aimed to characterize the cellular state of human monocytes from healthy donors stimulated with Staphylococcus aureus in comparison to TLR2-specific ligands. We analyzed S. aureus induced gene expression changes after 2 and 24 hours by amplicon sequencing (RNA-AmpliSeq) and compared the pro-inflammatory response after 2 hours with the response in re-stimulation experiments. In parallel, glycoprotein expression changes in human monocytes after 24 hours of S. aureus stimulation were analyzed by proteomics and compared to stimulation experiments with TLR2 ligands Malp-2 and Pam3Cys and TLR4 ligand LPS. Finally, we analyzed peripheral blood monocytes of patients with S. aureus bloodstream infection for their ex vivo inflammatory responses towards S. aureus stimulation and their glycoprotein expression profiles. Our results demonstrate that monocytes from healthy donors stimulated with S. aureus and TLR ligands of Gram-positive bacteria entered the tolerant cell state after activation similar to LPS treatment. In particular reduced gene expression of pro-inflammatory cytokines (TNF, IL1β) and chemokines (CCL20, CCL3, CCL4, CXCL2, CXCL3 and CXCL8) could be demonstrated. Glycoprotein expression changes in monocytes tolerized by the different TLR agonists were highly similar while S. aureus-stimulated monocytes shared some of the PAMP-induced changes but also exhibited a distinct expression profile. 11 glycoproteins (CD44, CD274, DSC2, ICAM1, LAMP3, LILRB1, PTGS2, SLC1A3, CR1, FGL2, and HP) were similarly up- or downregulated in all four comparisons in the tolerant cell state. Monocytes from patients with S. aureus bacteremia revealed preserved pro-inflammatory responsiveness to S. aureus stimulation ex vivo, expressed increased CD44 mRNA but no other glycoprotein of the tolerance signature was differentially expressed.

Immune Profiling Panel Gene Set Identifies Critically Ill Patients With Low Monocyte Human Leukocyte Antigen-DR Expression: Preliminary Results From the REAnimation Low Immune Status Marker (REALISM) Study

OBJECTIVES

There is a crucial unmet need for biomarker-guided diagnostic and prognostic enrichment in clinical trials evaluating immune modulating therapies in critically ill patients. Low monocyte expression of human leukocyte antigen-DR (mHLA-DR), considered as a reference surrogate to identify immunosuppressed patients, has been proposed for patient stratification in immunostimulation approaches. However, its widespread use in clinic has been somewhat hampered by technical constraints inherent to flow cytometry technology. The objective of the present study was to evaluate the ability of a prototype multiplex polymerase chain reaction tool (immune profiling panel [IPP]) to identify immunosuppressed ICU patients characterized by a low mHLA-DR expression.

DESIGN

Retrospective observational cohort study.

SETTING

Adult ICU in a University Hospital, Lyon, France.

PATIENTS

Critically ill patients with various etiologies enrolled in the REAnimation Low Immune Status Marker study (NCT02638779).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

mHLA-DR and IPP data were obtained from 1,731 blood samples collected from critically ill patients with various etiologies and healthy volunteers. A partial least square regression model combining the expression levels of IPP markers was trained and used for the identification of samples from patients presenting with evidence of immunosuppression, defined here as mHLADR less than 8,000 antibodies bound per cell (AB/C). The IPP gene set had an area under the receiver operating characteristic curve (AUC) of 0.86 (95% CI 0.83-0.89) for the identification of immunosuppressed patients. In addition, when applied to the 123 patients still in the ICU at days 5-7 after admission, IPP similarly enriched the number of patients with ICU-acquired infections in the immunosuppressed group (26%), in comparison with low mHLA-DR (22%).

CONCLUSIONS

This study reports on the potential of the IPP gene set to identify ICU patients presenting with mHLA-DR less than 8,000 AB/C. Upon further optimization and validation, this molecular tool may help in the stratification of patients that could benefit from immunostimulation in the context of personalized medicine.

THE ROLE OF OBESITY AND PLASMA ADIPOCYTOKINES IN IMMUNE DYSREGULATION IN SEPSIS PATIENTS

Introduction: The dysregulated immune response in sepsis is highly variable, ranging from hyperinflammation to immunoparalysis. Obesity is associated with the release of inflammatory mediators from adipose tissue, known as adipocytokines, causing a chronic inflammatory state. Perhaps counterintuitively, obesity is also associated with lower mortality in sepsis patients. We investigated the association between obesity, circulating adipocytokine concentrations, immune dysregulation, and outcome in sepsis patients. Methods In this secondary analysis of a prospective study, plasma concentrations of the adipocytokines leptin, adiponectin, and resistin were assessed in 167 patients at diagnosis of sepsis due to pneumonia, bacteremia, or acute cholangitis. Adipocytokines were compared between patients with normal weight (body mass index [BMI], 18.5-24.9 kg/m 2 ; n = 67), overweight (BMI, 25.0-29.9 kg/m 2 ; n = 56), and obesity (BMI ≥30 kg/m 2 ; n = 42), as well as between immunological endotypes: hyperinflammation (n = 40), immunoparalysis (n = 62), and unclassified (n = 55). Results: Higher circulating concentrations of leptin were observed in patients with obesity compared with patients with normal weight ( P = 0.008) and overweight ( P = 0.02), whereas adiponectin and resistin plasma concentrations were not different ( P = 0.08 and P = 0.85, respectively). Resistin concentrations were associated with immunological endotypes, with the highest levels found in hyperinflammatory patients ( P < 0.001). Furthermore, resistin concentrations were predictive for 28-day mortality (adjusted odds ratio, 1.03 per 10 ng/mL; P = 0.04). These associations were not found for leptin and adiponectin. Conclusion: Obesity and BMI-related adipocytokines are not related to the development of a hyperactive or suppressed immune response as defined by ferritin and mHLA-DR expression in sepsis patients. Although resistin is related to the immune response and an increased risk of adverse clinical outcomes, these associations are similar in patients with normal weight, overweight, and obesity. This implies that the relationship between resistin and clinical outcome is likely driven by the inflammatory response and not by obesity itself. Taken together, although there exists a strong association between inflammation and sepsis mortality, our results do not point toward a role for obesity and BMI-related adipocytokines in immune dysregulation in sepsis patients.

Complement activation in severely ill patients with sepsis: no relationship with inflammation and disease severity

BACKGROUND

Sepsis is characterized by a dysregulated immune response to infection. The complement system plays an important role in the host defence to pathogens. However, exaggerated complement activation might contribute to a hyperinflammatory state. The interplay between complement activation and inflammation in relationship with adverse outcomes in sepsis patients is unclear.

METHODS

Secondary analysis of complement factors in a prospective study in 209 hospitalized sepsis patients, of whom the majority presented with shock. Concentrations of complement factors C3, C3a, C3c, C5, C5a, and soluble terminal complement complex were assessed in ethylenediaminetetraacetic acid plasma samples collected within 24 h after sepsis diagnosis using enzyme-linked immunosorbent assays.

RESULTS

The concentration of complement factors in plasma of severely ill sepsis patients indicated profound activation of the complement system (all P < 0.01 compared to healthy controls). Spearman rank correlation tests indicated consistent relationships between the different complement factors measured, but no significant correlations were observed between the complement factors and other inflammatory biomarkers such as leukocyte numbers, C-reactive protein and ferritin concentrations, or HLA-DR expression on monocytes. The concentration of complement factors was not associated with Sequential Organ Failure Assessment score, the incidence of septic shock, and mortality rates (all P > 0.05) in this cohort of patients with high disease severity.

CONCLUSIONS

Once an infection progresses to severe sepsis or septic shock, the complement pathway is already profoundly activated and is no longer related to a dysregulated inflammatory response, nor to clinical outcome. This implies that in this patient category with severe disease, the complement system is activated to such an extent that it no longer has predictive value for clinical outcome.

Monocytic HLA-DR Expression in Immune Responses of Acute Pancreatitis and COVID-19

Acute pancreatitis is a common gastrointestinal disease with increasing incidence worldwide. COVID-19 is a potentially life-threatening contagious disease spread throughout the world, caused by severe acute respiratory syndrome coronavirus 2. More severe forms of both diseases exhibit commonalities with dysregulated immune responses resulting in amplified inflammation and susceptibility to infection. Human leucocyte antigen (HLA)-DR, expressed on antigen-presenting cells, acts as an indicator of immune function. Research advances have highlighted the predictive values of monocytic HLA-DR (mHLA-DR) expression for disease severity and infectious complications in both acute pancreatitis and COVID-19 patients. While the regulatory mechanism of altered mHLA-DR expression remains unclear, HLA-DR-/low monocytic myeloid-derived suppressor cells are potent drivers of immunosuppression and poor outcomes in these diseases. Future studies with mHLA-DR-guided enrollment or targeted immunotherapy are warranted in more severe cases of patients with acute pancreatitis and COVID-19.

Utility of monocyte HLA-DR and rationale for therapeutic GM-CSF in sepsis immunoparalysis

Sepsis, a heterogeneous clinical syndrome, features a systemic inflammatory response to tissue injury or infection, followed by a state of reduced immune responsiveness. Measurable alterations occur in both the innate and adaptive immune systems. Immunoparalysis, an immunosuppressed state, associates with worsened outcomes, including multiple organ dysfunction syndrome, secondary infections, and increased mortality. Multiple immune markers to identify sepsis immunoparalysis have been proposed, and some might offer clinical utility. Sepsis immunoparalysis is characterized by reduced lymphocyte numbers and downregulation of class II human leukocyte antigens (HLA) on innate immune monocytes. Class II HLA proteins present peptide antigens for recognition by and activation of antigen-specific T lymphocytes. One monocyte class II protein, mHLA-DR, can be measured by flow cytometry. Downregulated mHLA-DR indicates reduced monocyte responsiveness, as measured by ex-vivo cytokine production in response to endotoxin stimulation. Our literature survey reveals low mHLA-DR expression on peripheral blood monocytes correlates with increased risks for infection and death. For mHLA-DR, 15,000 antibodies/cell appears clinically acceptable as the lower limit of immunocompetence. Values less than 15,000 antibodies/cell are correlated with sepsis severity; and values at or less than 8000 antibodies/cell are identified as severe immunoparalysis. Several experimental immunotherapies have been evaluated for reversal of sepsis immunoparalysis. In particular, sargramostim, a recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF), has demonstrated clinical benefit by reducing hospitalization duration and lowering secondary infection risk. Lowered infection risk correlates with increased mHLA-DR expression on peripheral blood monocytes in these patients. Although mHLA-DR has shown promising utility for identifying sepsis immunoparalysis, absence of a standardized, analytically validated method has thus far prevented widespread adoption. A clinically useful approach for patient inclusion and identification of clinically correlated output parameters could address the persistent high unmet medical need for effective targeted therapies in sepsis.

Monitoring Blood Immune Cells in Patients with Advanced Small Cell Lung Cancer Undergoing a Combined Immune Checkpoint Inhibitor/Chemotherapy

In this exploratory prospective observational study on 40 small cell lung cancer (SCLC) patients treated with a combination of chemotherapy and immune checkpoint inhibitors, blood immune cells were characterized by multi-color flow cytometry at the baseline and at the third therapy cycle. The numbers of neutrophils and of T-, B-, and NK cells, as well as the frequency of HLA-DR^low monocytes, 6-SulfoLacNAc (slan)+ non-classical monocytes and circulating dendritic cell (DC) subtypes were determined. The prognostic value of the parameters was evaluated by the patient's survival analysis with overall survival (OS) as the primary endpoint. In addition, blood cell parameters from SCLC patients were compared to those from non-SCLC (NSCLC). The global median OS of patients was 10.4 ± 1.1 months. Disease progression (15% of patients) correlated with a higher baseline neutrophil/lymphocyte ratio (NLR), more HLA-DR^low monocytes, and lower NK cell and DC numbers. The risk factors for poor OS were the presence of brain/liver metastases, a baseline NLR ≥ 6.1, HLA-DR^low monocytes ≥ 21% of monocytes, slan+ non-classical monocytes < 0.12%, and/or CD1c+ myeloid DC < 0.05% of leukocytes. Lymphocytic subpopulations did not correlate with OS. When comparing biomarkers in SCLC versus NSCLC, SCLC had a higher frequency of brain/liver metastases, a higher NLR, the lowest DC frequencies, and lower NK cell numbers. Brain/liver metastases had a substantial impact on the survival of SCLC patients. At the baseline, 45% of SCLC patients, but only 24% of NSCLC patients, had between three and five risk factors. A high basal NLR, a high frequency of HLA-DR^low monocytes, and low levels of slan+ non-classical monocytes were associated with poor survival in all lung cancer histotypes. Thus, the blood immune cell signature might contribute to a better prediction of SCLC patient outcomes and may uncover the pathophysiological peculiarities of this tumor entity.

[Update: Immunosuppression in organ transplantation]

Immunosuppression is an essential prerequisite for successful transplantation. In order to reduce the sometimes-considerable side effects, combination therapies with different agents are used. This article aims to provide an up-to-date overview of immunosuppression after liver and kidney transplantation.

Blood Immune Cell Biomarkers in Lung Cancer Patients Undergoing Treatment with a Combination of Chemotherapy and Immune Checkpoint Blockade

Although immune checkpoint inhibitor (ICI) therapies have improved the treatment of patients with advanced non-small cell lung cancer (NSCLC), several patients do not achieve durable clinical responses. Biomarkers for the prediction of therapy responses are urgently needed. To identify blood cell parameters correlating with patients’ survival, immune cells from 90 patients with NSCLC undergoing a combination of ICI and chemotherapy were prospectively monitored. At the time point of the first and third antibody administration, complete leukocyte blood count, the percentage of HLA-DRlow monocytes, the percentage of 6-Sulfo LacNAc (slan)+CD16+ non-classical monocytes, and the number of circulating dendritic cell (DC) subtypes, as well as T-, B-, and NK cells were determined by multi-color flow cytometry in peripheral blood. The prognostic value of the immune cell parameters investigated was evaluated by patients’ survival analysis, with progression-free survival (PFS) as the main criterion. A total of 67 patients (74.4%) showed a partial remission or a stable disease, and 35% of patients even survived 12 months and longer. Patients with a neutrophil-to-lymphocyte ratio (NLR) ≥6.1, a frequency of HLA-DRlow monocytes ≥22%, of slan+ non-classical monocytes <0.25% of leukocytes, and/or a sum of myeloid DC (MDC) and plasmacytoid DC (PDC) ≤0.14% of leukocytes had a poorer prognosis. The hazard ratio for PFS was 2.097 (1.208−3.640) for the NLR, 1.964 (1.046−3.688) for HLA-DRlow monocytes, 3.202 (1.712−5.99) for slan+ non-classical monocytes, and 2.596 (1.478−4.56) for the MDC/PDC sum. Patients without any of the four risk factors showed the best PFS. Furthermore, low NK cell counts correlated with shorter PFS (cutoff 200 cells/µL). Female patients had lower baseline NK cell counts and a shorter PFS. Our study confirms the usefulness of blood immune cells as biomarkers for clinical response and survival in NSCLC patients undergoing a combined ICI/chemotherapy.

Dampened Inflammatory Signalling and Myeloid-Derived Suppressor-Like Cell Accumulation Reduces Circulating Monocytic HLA-DR Density and May Associate With Malignancy Risk in Long-Term Renal Transplant Recipients

Background

Malignancy is a major cause of morbidity and mortality in transplant recipients. Identification of those at highest risk could facilitate pre-emptive intervention such as reduction of immunosuppression. Reduced circulating monocytic HLA-DR density is a marker of immune depression in the general population and associates with poorer outcome in critical illness. It has recently been used as a safety marker in adoptive cell therapy trials in renal transplantation. Despite its potential as a marker of dampened immune responses, factors that impact upon monocytic HLA-DR density and the long-term clinical sequelae of this have not been assessed in transplant recipients.

Methods

A cohort study of stable long-term renal transplant recipients was undertaken. Serial circulating monocytic HLA-DR density and other leucocyte populations were quantified by flow cytometry. Gene expression of monocytes was performed using the Nanostring nCounter platform, and 13-plex cytokine bead array used to quantify serum concentrations. The primary outcome was malignancy development during one-year follow-up. Risk of malignancy was calculated by univariate and multivariate proportionate hazards modelling with and without adjustment for competing risks.

Results

Monocytic HLA-DR density was stable in long-term renal transplant recipients (n=135) and similar to non-immunosuppressed controls (n=29), though was suppressed in recipients receiving prednisolone. Decreased mHLA-DRd was associated with accumulation of CD14+CD11b+CD33+HLA-DRlo monocytic myeloid-derived suppressor-like cells. Pathway analysis revealed downregulation of pathways relating to cytokine and chemokine signalling in monocytes with low HLA-DR density; however serum concentrations of major cytokines did not differ between these groups. There was an independent increase in malignancy risk during follow-up with decreased HLA-DR density.

Conclusions

Dampened chemokine and cytokine signalling drives a stable reduction in monocytic HLA-DR density in long-term transplant recipients and associates with subsequent malignancy risk. This may function as a novel marker of excess immunosuppression. Further study is needed to understand the mechanism behind this association.

Monitoring of circulating monocyte HLA-DR expression in a large cohort of intensive care patients: relation with secondary infections

Introduction

The reports of an early and profound acquired immunodepression syndrome (AIDs) in ICU patients had gained sufficient credence to modify the paradigm of acute inflammation. However, despite several articles published on AIDs and its assessment by monocytic HLA-DR monitoring, several missing informations remained: 1—Which patients’ are more prone to benefit from mHLA-DR measurement, 2—Is the nadir or the duration of the low mHLA-DR expression the main parameter to consider? 3—What are the compared performances of leukocytes’ count analyses (lymphocyte, monocyte).

Material and method

We conducted an observational study in a surgical ICU of a French tertiary hospital. A first mHLA-DR measurement (fixed flow cytometry protocol) was performed within the first 3 days following admission and a 2nd, between day 5 and 10. The other collected parameters were: SAPS II and SOFA scores, sex, age, comorbidities, mortality and ICU-acquired infections (IAI). The associations between mHLA-DR and outcomes were tested by adjusted Fine and Gray subdistribution competing risk models.

Results

1053 patients were included in the study, of whom 592 had a 2nd mHLA-DR measurement. In this cohort, 223 patients (37.7%) complicated by IAI. The initial decrement in mHLA-DR was not associated with the later occurrence of IAI, (p = 0.721), however, the persistence of a low mHLA-DR (< 8000 AB/C), measured between day 5 and day 7, was associated with the later occurrence of IAI (p = 0.01). Similarly, a negative slope between the first and the second value was significantly associated with subsequent IAI (p = 0.009). The best performance of selected markers was obtained with the combination of the second mHLA-DR measurement with SAPSII on admission. Persisting lymphopenia and monocytopenia were not associated with later occurrence of IAI.

Conclusion

Downregulation of mHLA-DR following admission is observed in a vast number of patients whatever the initial motif for admission. IAI mostly occurs among patients with a high severity score on admission suggesting that immune monitoring should be reserved to the most severe patients. The initial downregulation did not preclude the later development of IAI. A decreasing or a persisting low mHLA-DR expression below 8000AB/C within the first 7 days of ICU admission was independently and reliably associated with subsequent IAI among ICU patients with performances superior to leukocyte subsets count alone.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01010-y.

SIGLEC1 enables straightforward assessment of type I interferon activity in idiopathic inflammatory myopathies

Objective

To evaluate sialic acid binding Ig-like lectin 1 (SIGLEC1) expression on monocytes by flow cytometry as a type I interferon biomarker in idiopathic inflammatory myopathies (IIM).

Methods

We performed a retrospective analysis of adult and paediatric patients with the diagnosis of IIM. SIGLEC1 expression was assessed by flow cytometry and was compared with Physician Global Assessment or Childhood Myositis Assessment Scale disease activity scores. Mann Whitney U test and receiver operating characteristic curves were used for cross-sectional data analysis (n=96), two-level mixed-effects linear regression model for longitudinal analyses (n=26, 110 visits). Response to treatment was analysed in 14 patients within 12 months, using Wilcoxon test. SIGLEC1 was compared with interferon-stimulated gene 15/MxA status by immunohistochemical staining of muscle biopsies (n=17).

Results

96 patients with adult (a) and juvenile (j) dermatomyositis (DM, n=38), antisynthetase syndrome (AS, n=19), immune-mediated necrotising myopathy (IMNM, n=8), inclusion body myositis (IBM, n=9) and overlap myositis (n=22) were included. SIGLEC1 distinguished significantly between active and inactive disease with an area under the curve of 0.92 (95% CI 0.83 to 1) in DM and correlated with disease activity longitudinally (aDM: standardised beta=0.54, p<0.001; jDM: standardised beta=−0.70, p<0.001). Response to treatment in DM was associated with a decreasing SIGLEC1 (p<0.01, Wilcoxon test). SIGLEC1 was found upregulated in 8 of 19 patients with AS, 2 of 9 patients with IBM but not in IMNM.

Conclusion

SIGLEC1 is a candidate biomarker to assess type I interferon activity in IIM and proved useful for monitoring disease activity and response to treatment in juvenile and adult DM.

Association of monocyte HLA-DR expression over time with secondary infection in critically ill children: a prospective observational study

An impaired immune response could play a role in the acquisition of secondary infections in critically ill children. Human leukocyte antigen-DR expression on monocytes (mHLA-DR) has been proposed as marker to detect immunosuppression, but its potential to predict secondary infections in critically ill children is unclear. We aimed to assess the association between mHLA-DR expression at several timepoints and the change of mHLA-DR expression over time with the acquisition of secondary infections in critically ill children. In this prospective observational study, children < 18 years with fever and/or suspected infection (community-acquired or hospital-acquired) were included at a paediatric intensive care unit in the Netherlands. mHLA-DR expression was determined by flow cytometry on day 1, day 2-3 and day 4-7. The association between delta-mHLA-DR expression (difference between last and first measurement) and secondary infection was assessed by multivariable regression analysis, adjusted for age and Paediatric Logistic Organ Dysfunction-2 score. We included 104 patients at the PICU (median age 1.2 years [IQR 0.3-4.2]), of whom 28 patients (27%) developed a secondary infection. Compared to 93 healthy controls, mHLA-DR expression of critically ill children was significantly lower at all timepoints. mHLA-DR expression did not differ at any of the time points between patients with and without secondary infection. In addition, delta-mHLA-DR expression was not associated with secondary infection (aOR 1.00 [95% CI 0.96-1.04]).Conclusions: Our results confirm that infectious critically ill children have significantly lower mHLA-DR expression than controls. mHLA-DR expression was not associated with the acquisition of secondary infections. What is Known: • An impaired immune response, estimated by mHLA-DR expression, could play an essential role in the acquisition of secondary infections in critically ill children. • In critically ill children, large studies on the association of mHLA-DR expression with secondary infections are scarce. What is New: • Our study confirms that critically ill children have lower mHLA-DR expression than healthy controls. • mHLA-DR expression and change in mHLA-DR was not associated with the acquisition of secondary infection.

Immune System Dysfunction Criteria in Critically Ill Children: The PODIUM Consensus Conference

CONTEXT

Immune system dysfunction is poorly represented in pediatric organ dysfunction definitions.

OBJECTIVE

To evaluate evidence for criteria that define immune system dysfunction in critically ill children and associations with adverse outcomes and develop consensus criteria for the diagnosis of immune system dysfunction in critically ill children.

DATA SOURCES

We conducted electronic searches of PubMed and Embase from January 1992 to January 2020, using medical subject heading terms and text words to define immune system dysfunction and outcomes of interest.

STUDY SELECTION

Studies of critically ill children with an abnormality in leukocyte numbers or function that is currently measurable in the clinical laboratory in which researchers assessed patient-centered outcomes were included. Studies of adults or premature infants, animal studies, reviews and commentaries, case series (≤10 subjects), and studies not published in English with inability to determine eligibility criteria were excluded.

DATA EXTRACTION

Data were abstracted from eligible studies into a standard data extraction form along with risk of bias assessment by a task force member.

RESULTS

We identified the following criteria for immune system dysfunction: (1) peripheral absolute neutrophil count <500 cells/μL, (2) peripheral absolute lymphocyte count <1000 cells/μL, (3) reduction in CD4+ lymphocyte count or percentage of total lymphocytes below age-specific thresholds, (4) monocyte HLA-DR expression <30%, or (5) reduction in ex vivo whole blood lipopolysaccharide-induced TNFα production capacity below manufacturer-provided thresholds.

LIMITATIONS

Many measures of immune system function are currently limited to the research environment.

CONCLUSIONS

We present consensus criteria for the diagnosis of immune system dysfunction in critically ill children.

Immunomonitoring of Monocyte and Neutrophil Function in Critically Ill Patients: From Sepsis and/or Trauma to COVID-19

Immune cells and mediators play a crucial role in the critical care setting but are understudied. This review explores the concept of sepsis and/or injury-induced immunosuppression and immuno-inflammatory response in COVID-19 and reiterates the need for more accurate functional immunomonitoring of monocyte and neutrophil function in these critically ill patients. in addition, the feasibility of circulating and cell-surface immune biomarkers as predictors of infection and/or outcome in critically ill patients is explored. It is clear that, for critically ill, one size does not fit all and that immune phenotyping of critically ill patients may allow the development of a more personalized approach with tailored immunotherapy for the specific patient. In addition, at this point in time, caution is advised regarding the quality of evidence of some COVID-19 studies in the literature.

Immune Dysfunction is Associated with Readmission in Survivors of Sepsis Following Infected Pancreatic Necrosis

Objective

Immunosuppression is common in patients with infected pancreatic necrosis (IPN) and associated with morbidity and mortality. This study aimed to investigate the impact of immune status on mortality and readmission after hospital discharge in patients with IPN-related sepsis.

Methods

In this prospective observational study, eligible adult patients with IPN-related sepsis requiring ICU admission were included. Monocytic human leukocyte antigen DR (mHLA-DR), expression of regulatory T cells (Treg), and neutrophil CD88 (nCD88) were measured on the diagnosis of sepsis, ICU discharge, hospital discharge, and 15, 30, 60 days after hospital discharge. Logistic regression model was used to assess potential risk factors for readmission 60-days within the index discharge.

Results

A total of 53 patients were included, 13 died during hospitalization and one withdrew the consent soon after discharge. Among the survivors, a tendency of immune recovery was observed during the consecutive follow-ups, evidenced by the increased expression of mHLA-DR. Sixteen patients (41.03%) were readmitted within 60 days after the index discharge. In the multivariable regression model, APACHE II score when sepsis was diagnosed >9 and mHLA-DR at discharged <14,591 AB/C were found to be independent risk factors affecting readmission.

Conclusion

Immunosuppression is common in patients with IPN-related sepsis and can persist until two months after discharge. The compromised mHLA-DR level at discharge was associated with readmission within two months after discharge.

Sepsis-Induced Immunosuppression

Sepsis is expected to have a substantial impact on public health and cost as its prevalence increases. Factors contributing to increased prevalence include a progressively aging population, advances in the use of immunomodulatory agents to treat a rising number of diseases, and immune-suppressing therapies in organ transplant recipients and cancer patients. It is now recognized that sepsis is associated with profound and sustained immunosuppression, which has been implicated as a predisposing factor in the increased susceptibility of patients to secondary infections and mortality. In this review, we discuss mechanisms of sepsis-induced immunosuppression and biomarkers that identify a state of impaired immunity. We also highlight immune-enhancing strategies that have been evaluated in patients with sepsis, as well as therapeutics under current investigation. Finally, we describe future challenges and the need for a new treatment paradigm, integrating predictive enrichment with patient factors that may guide the future selection of tailored immunotherapy. Expected final online publication date for the Annual Review of Physiology, Volume 84 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Severe COVID-19 is characterized by the co-occurrence of moderate cytokine inflammation and severe monocyte dysregulation

Background

SARS-CoV-2 has been responsible for considerable mortality worldwide, owing in particular to pulmonary failures such as ARDS, but also to other visceral failures and secondary infections. Recent progress in the characterization of the immunological mechanisms that result in severe organ injury led to the emergence of two successive hypotheses simultaneously tested here: hyperinflammation with cytokine storm syndrome or dysregulation of protective immunity resulting in immunosuppression and unrestrained viral dissemination.

Methods

In a prospective observational monocentric study of 134 patients, we analysed a panel of plasma inflammatory and anti-inflammatory cytokines and measured monocyte dysregulation via their membrane expression of HLA-DR. We first compared the results of patients with moderate forms hospitalized in an infectious disease unit with those of patients with severe forms hospitalized in an intensive care unit. In the latter group of patients, we then analysed the differences between the surviving and non-surviving groups and between the groups with or without secondary infections.

Findings

Higher blood IL-6 levels, lower quantitative expression of HLA-DR on blood monocytes and higher IL-6/mHLA-DR ratios were statistically associated with the risk of severe forms of the disease and among the latter with death and the early onset of secondary infections.

Interpretation

The unique immunological profile in patients with severe COVID-19 corresponds to a moderate cytokine inflammation associated with severe monocyte dysregulation. Individuals with major CSS were rare in our cohort of hospitalized patients, especially since the use of corticosteroids, but formed a very severe subgroup of the disease.

Funding

None.

Immune Function in Critically Ill Septic Children

The inflammatory response in pediatric sepsis is highly dynamic and includes both pro- and anti-inflammatory elements that involve the innate and adaptive immune systems. While the pro-inflammatory response is responsible for the initial clinical signs and symptoms of sepsis, a concurrent compensatory anti-inflammatory response often results in an occult, but highly clinically relevant, form of acquired immunodeficiency. When severe, this is termed "immunoparalysis" and is associated with increased risks for nosocomial infection, prolonged organ dysfunction, and death. This review focuses on the pathophysiology and clinical implications of both over- and under-active immune function in septic children. Host-, disease-, and treatment-specific risk factors for immunoparalysis are reviewed along with immune phenotype-specific approaches for immunomodulation in pediatric sepsis which are currently the subject of clinical trials.

Monocyte human leukocyte antigen-DR but not β-D-glucan may help early diagnosing invasive Candida infection in critically ill patients

Background

Precision medicine risk stratification is desperately needed to both avoid systemic antifungals treatment delay and over prescription in the critically ill with risk factors. The aim of the present study was to explore the combination of host immunoparalysis biomarker (monocyte human leukocyte antigen-DR expression (mHLA-DR)) and Candida sp wall biomarker β-d-glucan in risk stratifying patients for secondary invasive Candida infection (IC).

Methods

Prospective observational study. Two intensive care units (ICU). All consecutive non-immunocompromised septic shock patients. Serial blood samples (n = 286) were collected at day 0, 2 and 7 and mHLA-DR and β-d-glucan were then retrospectively assayed after discharge. Secondary invasive Candida sp infection occurrence was then followed at clinicians’ discretion.

Results

Fifty patients were included, 42 (84%) had a Candida score equal or greater than 3 and 10 patients developed a secondary invasive Candida sp infection. ICU admission mHLA-DR expression and β-d-glucan (BDG) failed to predict secondary invasive Candida sp infection. Time-dependent cause-specific hazard ratio of IC was 6.56 [1.24–34.61] for mHLA-DR < 5000 Ab/c and 5.25 [0.47–58.9] for BDG > 350 pg/mL. Predictive negative value of mHLA-DR > 5000 Ab/c and BDG > 350 pg/mL combination at day 7 was 81% [95% CI 70–92].

Conclusions

This study suggests that mHLA-DR may help predicting IC in high-risk patients with septic shock. The added value of BDG and other fungal tests should be regarded according to the host immune function markers.

Monocyte Dysfunction Detected by the Designed Ankyrin Repeat Protein F7 Predicts Mortality in Patients Receiving Veno-Arterial Extracorporeal Membrane Oxygenation

Background: Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is used for critically ill patients requiring hemodynamic support but has been shown to induce an inflammatory response syndrome potentially leading to severe complications and poor outcome. Monocytes are comprised of different subsets and play a central role in the innate immune system. The unique small binding proteins, Designed Ankyrin Repeat Protein “F7” and single chain variable fragment “MAN-1,” specifically detect the activated conformation of the leukocyte integrin Mac-1 enabling the highly sensitive detection of monocyte activation status. The aim of this study was to characterize monocyte function and heterogeneity and their association with outcome in VA-ECMO patients.

Methods: VA-ECMO patients were recruited from the ICUs of the University Hospital in Freiburg, Germany. Blood was sampled on day 0 and day 3 after VA-ECMO placement, after VA-ECMO explantation and from healthy controls. Monocyte subset distribution, baseline activation and stimulability were analyzed by flow cytometry using the unique small binding proteins F7 and MAN-1 and the conventional activation markers CD163, CD86, CD69, and CX3CR1. Furthermore, expression of monocyte activation markers in survivors and non-survivors on day 0 was compared. Simple logistic regression was conducted to determine the association of monocyte activation markers with mortality.

Results: Twenty two patients on VA-ECMO and 15 healthy controls were recruited. Eleven patients survived until discharge from the ICU. Compared to controls, baseline monocyte activation was significantly increased, whereas stimulability was decreased. The percentage of classical monocytes increased after explantation, while the percentage of intermediate monocytes decreased. Total, classical, and intermediate monocyte counts were significantly elevated compared to controls. On day 0, baseline binding of F7 was significantly lower in non-survivors than survivors. The area under the ROC curve associated with mortality on day 0 was 0.802 (p = 0.02).

Conclusions: Distribution of monocyte subsets changes during VA-ECMO and absolute classical and intermediate monocyte counts are significantly elevated compared to controls. Monocytes from VA-ECMO patients showed signs of dysfunction. Monocyte dysfunction, as determined by the unique tool F7, could be valuable for predicting mortality in patients receiving VA-ECMO and may be used as a novel biomarker guiding early clinical decision making in the future.

Bicentric evaluation of stabilizing sampling tubes for assessment of monocyte HLA-DR expression in clinical samples

BACKGROUND

Diminished expression of human leukocyte antigen DR on circulating monocytes (mHLA-DR), measured by standardized flow cytometry procedure, is a reliable indicator of immunosuppression in severely injured intensive care unit patients. As such, it is used as stratification criteria in clinical trials evaluating novel immunostimulating therapies. Preanalytical constraints relative to the short delay between blood sampling and flow cytometry staining have nevertheless limited its use in multicentric studies. The objective of the present work was to compare mHLA-DR expression between whole blood samples simultaneously drawn in EDTA or Cyto-Chex BCT tubes.

METHODS

In two university hospitals, mHLA-DR was assessed in fresh whole blood from septic patients (n = 12) and healthy donors (n = 6) simultaneously sampled on EDTA and Cyto-Chex BCT tubes. Staining was performed immediately after sampling and after blood storage at room temperature.

RESULTS

We confirmed that samples collected in Cyto-Chex tube had substantially enhanced stability for mHLA-DR results (48-72 h) over those collected in EDTA. On baseline values, despite good correlation between tubes (r = 0.98, p < 0.001), mHLA-DR expression was systematically lower with Cyto-Chex BCT.

CONCLUSION

The present reports confirms the potential of Cyto-Chex BCT tubes to stabilize mHLA-DR expression before staining and extends the work of Quadrini et al. [Cytometry B 2021;100:103-114]. In centers without rapid access to flow cytometry facilities, it enables to tolerate delays in mHLA-DR staining. However, a 30% gap exists between results obtained with EDTA and Cyto-Chex BCT tubes. As current thresholds for clinical decisions were obtained with EDTA samples, further studies are needed to confirm clinical thresholds with Cyto-Chex BCT tubes.

Blood Immune Cell Biomarkers in Patient With Lung Cancer Undergoing Treatment With Checkpoint Blockade

Supplemental Digital Content is available in the text.

Characterization of host immune cell parameters before and during immunotherapy is expected to identify predictive biomarkers for clinical outcome. We prospectively monitored blood immune cells from 35 patients with advanced non–small cell lung cancer undergoing checkpoint inhibitor monotherapy. The aim was to identify parameters correlating with better/worse outcome. Peripheral blood was serially collected before each infusion at the onset and at cycle 3 and 5 of immunotherapy. A complete leukocyte blood count, the lymphocytic subpopulations and the percentages of both HLA-DR^low monocytes and dendritic cells (DC) were monitored. Disease control was defined as partial/complete response and stable disease on computed tomography scan according to RECIST 1.1. The predictive value of the immune cell parameters investigated was evaluated by patients’ survival analysis. Forty percent of patients showed a clinical response, and the global median overall survival was 7.0 months (95% confidence interval: 3.5–10.5). Patients with an initial neutrophil-to-lymphocyte ratio (NLR) ≥5.2, and/or an amount of HLA-DR^low monocytes ≥11% and/or a total DC level ≤0.4% of leukocytes did rarely respond to PD-1 inhibitor therapy. Otherwise, the immunotherapy-induced decrease of the neutrophil-to-lymphocyte ratio and/or HLA-DR^low monocytes and the increase of total DC frequencies were correlated with improved therapy response and prolonged overall survival. Blood values in the third cycle of immunotherapy did already reflect the effects observed. On the basis of the 3 immune cell parameters identified we created 3 different variants of scores that enable to stratify patients into groups of risk/therapy response. Our results warrant further investigation in larger prospective clinical trials for validation.

Monocytic Human Leukocyte Antigen DR Expression in Young Infants Undergoing Cardiopulmonary Bypass

BACKGROUND

Monocytic human leukocyte antigen DR (mHLA-DR) expression levels have been reported to be a marker of immunosuppression and a predictor of sepsis and mortality. There are, however, scant data regarding mHLA-DR monitoring in young infants after cardiopulmonary bypass. Our objectives were to investigate the kinetics of mHLA-DR expression and to determine whether mHLA-DR levels are associated with healthcare-associated infection (HAI) after cardiopulmonary bypass in young infants.

METHODS

mHLA-DR levels were analyzed by flow cytometry using a standardized method in 49 infants (<3 months old) with congenital heart disease before and after cardiopulmonary bypass. Results are expressed as the number of anti-HLA-DR antibodies per cell (AB/c).

RESULTS

Postoperative mHLA-DR expression was reduced in all infants. Eleven patients (22%) developed HAI, and 4 patients (8%) died during the 30-day follow-up. mHLA-DR expression was significantly lower on postoperative day 4 in the HAI group compared with those who without HAI (3768 AB/c [range, 1938-6144] vs 13,230 AB/c [range, 6152-19,130], P = .014). Although mHLA-DR expression was associated with postoperative severity, mHLA-DR ≤4500 AB/c in the first 72 hours among patients with higher postoperative severity (extracorporeal membrane oxygenation and/or corticoids and/or delayed closure of sternum) was associated with occurrence of HAI in the univariate analysis (odds ratio, 6.3; 95% confidence interval, 1.0-38.7; P = .037).

CONCLUSIONS

Cardiopulmonary bypass induces a profound decrease in mHLA-DR expression in young infants. Among patients with higher postoperative severity, low level of mHLA-DR in the early postoperative period is associated with the development of HAI.

Decreased Human Leukocyte Antigen DR on Circulating Monocytes Expression After Severe Pediatric Trauma: An Exploratory Report

OBJECTIVES

Major trauma in adults induces immune dysfunction, with diminished expression of human leukocyte antigen-DR on circulating monocytes. No pediatric data are available. This study described the kinetics of human leukocyte antigen-DR on circulating monocytes following major pediatric trauma and relationships between human leukocyte antigen-DR on circulating monocytes and outcomes.

DESIGN

Prospective observational study.

SETTING

PICU and trauma unit at a tertiary-care university hospital in South Africa.

PATIENTS

Children between 1 month and 13 years hospitalized for severe brain trauma or trauma with an Injury Severity Score greater than or equal to 16, from November 2016 to March 2017.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We included 36 children. Median (interquartile range) age and Injury Severity Score were 7 years (4.9-10.5 yr) and 25 years (22.7-30 yr), respectively. Blood samples (n = 83) for standardized human leukocyte antigen-DR on circulating monocytes measurement were collected at days 1-2, 3-4, and 8-9 after injury (D1, D3, and D8, respectively). On D1, median (interquartile range) human leukocyte antigen-DR on circulating monocytes was markedly reduced relative to normal values (7,031 [5,204-11,201] antibodies per cell). There was a significant increase in human leukocyte antigen-DR on circulating monocytes from D1 to D8. Although all patients with secondary infections (n = 8; 22%) had human leukocyte antigen-DR on circulating monocytes less than 15,000 antibodies per cell at D3, human leukocyte antigen-DR on circulating monocytes levels were not associated with the occurrence of secondary infections (p = 0.22). At D3, human leukocyte antigen-DR on circulating monocytes was significantly higher in patients discharged home (n = 21) by Day 30 after trauma compared with those who died or were still hospitalized (n = 14) (p = 0.02).

CONCLUSIONS

Pediatric severe trauma induced an early and dramatic decrease in human leukocyte antigen-DR on circulating monocytes expression. This alteration of innate immunity was not associated with the occurrence of secondary infection, possibly due to a lack of statistical power. However, human leukocyte antigen-DR on circulating monocytes at Day 3 is a potential indicator of those at high risk of secondary infection and worse outcomes.

Circadian rhythms in septic shock patients

BACKGROUND

Despite the intensive efforts to improve the diagnosis and therapy of sepsis over the last decade, the mortality of septic shock remains high and causes substantial socioeconomical burden of disease. The function of immune cells is time-of-day-dependent and is regulated by several circadian clock genes. This study aims to investigate whether the rhythmicity of clock gene expression is altered in patients with septic shock.

METHODS

This prospective pilot study was performed at the university hospital Charité-Universitätsmedizin Berlin, Department of Anesthesiology and Operative Intensive Care Medicine (CCM, CVK). We included 20 patients with septic shock between May 2014 and January 2018, from whom blood was drawn every 4 h over a 24-h period to isolate CD14-positive monocytes and to measure the expression of 17 clock and clock-associated genes. Of these patients, 3 whose samples expressed fewer than 8 clock genes were excluded from the final analysis. A rhythmicity score SP was calculated, which comprises values between -1 (arrhythmic) and 1 (rhythmic), and expression data were compared to data of a healthy study population additionally.

RESULTS

77% of the measured clock genes showed inconclusive rhythms, i.e., neither rhythmic nor arrhythmic. The clock genes NR1D1, NR1D2 and CRY2 were the most rhythmic, while CLOCK and ARNTL were the least rhythmic. Overall, the rhythmicity scores for septic shock patients were significantly (p < 0.0001) lower (0.23 ± 0.26) compared to the control group (12 healthy young men, 0.70 ± 0.18). In addition, the expression of clock genes CRY1, NR1D1, NR1D2, DBP, and PER2 was suppressed in septic shock patients and CRY2 was significantly upregulated compared to controls.

CONCLUSION

Molecular rhythms in immune cells of septic shock patients were substantially altered and decreased compared to healthy young men. The decrease in rhythmicity was clock gene-dependent. The loss of rhythmicity and down-regulation of clock gene expression might be caused by sepsis and might further deteriorate immune responses and organ injury, but further studies are necessary to understand underlying pathophysiological mechanisms. Trail registration Clinical trial registered with www.ClinicalTrials.gov (NCT02044575) on 24 January 2014.

Ratio of serum procalcitonin to monocytic HLA-DR as a reliable parameter in prognosis prediction of sepsis

BACKGROUND

We evaluated the prognostic potential of the ratio of serum procalcitonin to monocytic HLA-DR for 28-day mortality in sepsis.

METHODS

In this retrospective study, a total of 91 patients with sepsis were enrolled. Clinical and laboratory data detected on admission (D0) and 7 days thereafter (D7) including the Acute Physiology and Chronic Health Evaluation II (APACHE II), the Sequential Organ Failure Assessment (admission SOFA), serum lactate, D-dimer, mHLA-DR, procalcitonin, platelet and white blood cell count, neutrophil-to-lymphocyte ratio were collected. The PCT/mHLA-DR ratio, the changes in mHLA-DR and WBC on day 7 compared with those on the day of admission and PCT clearance were calculated. Receiver operating characteristic curves, Kaplan-Meier survival curves, DeLong test and Cox regression analyses were used to assess and compare their predictive values.

RESULTS

Among all studied parameters, D₇-PCT/mHLA-DR showed the best discriminatory property to differentiate survivors from non-survivors and was identified as an independent predictor of 28-day mortality.

CONCLUSION

The D₇-PCT/mHLA-DR ratio was more sensitive than either biomarker alone in predicting fatal outcome in septic patients. Combining pro-inflammatory and immunosuppression biomarkers might improve the prognostic accuracy in sepsis.

Immunophenotyping of Peripheral Blood Mononuclear Cells in Septic Shock Patients With High-Dimensional Flow Cytometry Analysis Reveals Two Subgroups With Differential Responses to Immunostimulant Drugs

Sepsis is associated with a dysregulated inflammatory response to infection. Despite the activation of inflammation, an immune suppression is often observed, predisposing patients to secondary infections. Therapies directed at restoration of immunity may be considered but should be guided by the immune status of the patients. In this paper, we described the use of a high-dimensional flow cytometry (HDCyto) panel to assess the immunophenotype of patients with sepsis. We then isolated peripheral blood mononuclear cells (PBMCs) from patients with septic shock and mimicked a secondary infection by stimulating PBMCs for 4 h in vitro with lipopolysaccharide (LPS) with or without prior exposure to either IFN-γ, or LAG-3Ig. We evaluated the response by means of flow cytometry and high-resolution clustering cum differential analysis and compared the results to PBMCs from healthy donors. We observed a heterogeneous immune response in septic patients and identified two major subgroups: one characterized by hypo-responsiveness (Hypo) and another one by hyper-responsiveness (Hyper). Hypo and Hyper groups showed significant differences in the production of cytokines/chemokine and surface human leukocyte antigen-DR (HLA-DR) expression in response to LPS stimulation, which were observed across all cell types. When pre-treated with either interferon gamma (IFN-γ) or lymphocyte-activation gene 3 (LAG)-3 recombinant fusion protein (LAG-3Ig) prior to LPS stimulation, cells from the Hypo group were shown to be more responsive to both immunostimulants than cells from the Hyper group. Our results demonstrate the importance of patient stratification based on their immune status prior to any immune therapies. Once sufficiently scaled, this approach may be useful for prescribing the right immune therapy for the right patient at the right time, the key to the success of any therapy.

Establishing CD19 B-cell reference control materials for comparable and quantitative cytometric expression analysis

In the field of cell-based therapeutics, there is a great need for high-quality, robust, and validated measurements for cell characterization. Flow cytometry has emerged as a critically important platform due to its high-throughput capability and its ability to simultaneously measure multiple parameters in the same sample. However, to assure the confidence in measurement, well characterized biological reference materials are needed for standardizing clinical assays and harmonizing flow cytometric results between laboratories. To date, the lack of adequate reference materials, and the complexity of the cytometer instrumentation have resulted in few standards. This study was designed to evaluate CD19 expression in three potential biological cell reference materials and provide a preliminary assessment of their suitability to support future development of CD19 reference standards. Three commercially available human peripheral blood mononuclear cells (PBMCs) obtained from three different manufacturers were tested. Variables that could potentially contribute to the differences in the CD19 expression, such as PBMCs manufacturing process, number of healthy donors used in manufacturing each PBMC lot, antibody reagent, operators, and experimental days were included in our evaluation. CD19 antibodies bound per cell (ABC) values were measured using two flow cytometry-based quantification schemes with two independent calibration methods, a single point calibration using a CD4 reference cell and QuantiBrite PE bead calibration. Three lots of PBMC from three different manufacturers were obtained. Each lot of PBMC was tested on three different experimental days by three operators using three different lots of unimolar anti-CD19PE conjugates. CD19 ABC values were obtained in parallel on a selected lot of the PBMC samples using mass spectrometry (CyTOF) with two independent calibration methods, EQ4 and bead-based calibration were evaluated with CyTOF-technology. Including all studied variabilities such as PBMC lot, antibody reagent lot, and operator, the averaged mean values of CD19 ABC for the three PBMC manufacturers (A,B, and C) obtained by flow cytometry were found to be: 7953 with a %CV of 9.0 for PBMC-A, 10535 with a %CV of 7.8 for PBMC-B, and 12384 with a %CV of 16 for PBMC-C. These CD19 ABC values agree closely with the findings using CyTOF. The averaged mean values of CD19 ABC for the tested PBMCs is 9295 using flow cytometry-based method and 9699 using CyTOF. The relative contributions from various sources of uncertainty in CD19 ABC values were quantified for the flow cytometry-based measurement scheme. This uncertainty analysis suggests that the number of antigens or ligand binding sites per cell in each PBMC preparation is the largest source of variability. On the other hand, the calibration method does not add significant uncertainty to the expression estimates. Our preliminary assessment showed the suitability of the tested materials to serve as PBMC-based CD19+ reference control materials for use in quantifying relevant B cell markers in B cell lymphoproliferative disorders and immunotherapy. However, users should consider the variabilities resulting from different lots of PBMC and antibody reagent when utilizing cell-based reference materials for quantification purposes and perform bridging studies to ensure harmonization between the results before switching to a new lot.

A flow cytometric assay for HLA-DR expression on monocytes validated as a biomarker for enrollment in sepsis clinical trials

PURPOSE

Decreased expression of HLA-DR on monocytes (mHLA-DR) is a reliable indicator of immunosuppression in patients with sepsis and is correlated with increased risk of secondary infection and mortality. A flow cytometry-based laboratory developed test for the measurement of mHLA-DR in whole blood was validated for clinical trial enrollment, which is considered medical decision-making, for patients with severe sepsis or septic shock.

METHODS

The BD Quantibrite™ anti-HLA-DR/anti-monocyte reagent measures antibodies bound per cell of HLA-DR on CD14+ monocytes. The mHLA-DR assay was planned to support inclusion/exclusion of patients for a clinical trial and was validated according to New York State Department of Health (NYSDOH) requirements for a new non-malignant leukocyte immunophenotyping assay.

RESULTS

Normal, healthy donor and sepsis patient samples were stable up to 72 h post-collection in Cyto-Chex BCT phlebotomy tubes. Pre-determined acceptance criteria were met for precision parameters (average %CV ≤ 20%) and global laboratory-to-laboratory comparisons (average %Δ ≤ 20%). The approaches taken to evaluate and report accuracy, analytical specificity and sensitivity, reportable range, reference interval, and the proposed multi-level quality control were accepted by NYSDOH.

CONCLUSIONS

In this study, the validation strategy necessary when the intended use of assay results changes from exploratory to medical decision making (patient enrollment), which successfully resulted in regulatory approval, is described.

Update: Immunsuppression bei Organtransplantationen

Die Immunsuppression ist eine wesentliche Grundvoraussetzung für eine erfolgreiche Transplantation. Zur Reduktion der teils beträchtlichen Nebenwirkungen werden Kombinationstherapien mit unterschiedlichen Wirkstoffen durchgeführt. Dieser Beitrag soll einen aktuellen Überblick zur Immunsuppression nach Leber- und Nierentransplantation geben.

Regulatory T cells for minimising immune suppression in kidney transplantation: phase I/IIa clinical trial

OBJECTIVE

To assess whether reshaping of the immune balance by infusion of autologous natural regulatory T cells (nTregs) in patients after kidney transplantation is safe, feasible, and enables the tapering of lifelong high dose immunosuppression, with its limited efficacy, adverse effects, and high direct and indirect costs, along with addressing several key challenges of nTreg treatment, such as easy and robust manufacturing, danger of over immunosuppression, interaction with standard care drugs, and functional stability in an inflammatory environment in a useful proof-of-concept disease model.

DESIGN

Investigator initiated, monocentre, nTreg dose escalation, phase I/IIa clinical trial (ONEnTreg13).

SETTING

Charité-University Hospital, Berlin, Germany, within the ONE study consortium (funded by the European Union).

PARTICIPANTS

Recipients of living donor kidney transplant (ONEnTreg13, n=11) and corresponding reference group trial (ONErgt11-CHA, n=9).

INTERVENTIONS

CD4+ CD25+ FoxP3+ nTreg products were given seven days after kidney transplantation as one intravenous dose of 0.5, 1.0, or 2.5-3.0×10⁶ cells/kg body weight, with subsequent stepwise tapering of triple immunosuppression to low dose tacrolimus monotherapy until week 48.

MAIN OUTCOME MEASURES

The primary clinical and safety endpoints were assessed by a composite endpoint at week 60 with further three year follow-up. The assessment included incidence of biopsy confirmed acute rejection, assessment of nTreg infusion related adverse effects, and signs of over immunosuppression. Secondary endpoints addressed allograft functions. Accompanying research included a comprehensive exploratory biomarker portfolio.

RESULTS

For all patients, nTreg products with sufficient yield, purity, and functionality could be generated from 40-50 mL of peripheral blood taken two weeks before kidney transplantation. None of the three nTreg dose escalation groups had dose limiting toxicity. The nTreg and reference groups had 100% three year allograft survival and similar clinical and safety profiles. Stable monotherapy immunosuppression was achieved in eight of 11 (73%) patients receiving nTregs, while the reference group remained on standard dual or triple drug immunosuppression (P=0.002). Mechanistically, the activation of conventional T cells was reduced and nTregs shifted in vivo from a polyclonal to an oligoclonal T cell receptor repertoire.

CONCLUSIONS

The application of autologous nTregs was safe and feasible even in patients who had a kidney transplant and were immunosuppressed. These results warrant further evaluation of Treg efficacy and serve as the basis for the development of next generation nTreg approaches in transplantation and any immunopathologies.

TRIAL REGISTRATION

NCT02371434 (ONEnTreg13) and EudraCT:2011-004301-24 (ONErgt11).

Toward Monocyte HLA-DR Bedside Monitoring: A Proof-of-Concept Study

OBJECTIVES

Decreased expression of human leukocyte antigen-DR on monocytes (mHLA-DR) is recognized as the most appropriate marker for the monitoring of immune alterations in septic patients and critically ill subjects. Its measurement has been established for years by flow cytometry, but remains under-used due to pre-analytical constraints. The objectives of the present work were to develop a rapid and robust one-step protocol.

METHODS

A novel, simplified protocol has been developed to measure mHLA-DR in whole blood using flow cytometry. It is a one-step procedure that includes red cell lysis, antibodies, and fixative reagents. It has been compared to the standardized routine protocol in two consecutive cohorts of septic shock patients (n = 37). Finally, the protocol was applied to a few subjects in point-of-care settings, by collecting capillary blood from fingerpricks.

RESULTS

Strong correlation was observed between the one-step method and routine protocol in 24 patients. After testing several stabilizing agents, the procedure was further optimized by adding a low-dose formaldehyde to the stain and lyse solution. This improved method was tested in a second cohort of 13 patients, and again strongly correlated to the routine protocol. Finally, the fingerprick and venous puncture samples were shown to provide similar results.

CONCLUSIONS

The present work demonstrates the feasibility of a bedside protocol for flow cytometry measurement of mHLA-DR in critically ill subjects. This helps overcome pre-analytical constraints previously identified, which have limited wider use of this biomarker in intensive care units. In addition, preliminary results from fingerprick samples are promising.

Deciphering heterogeneity of septic shock patients using immune functional assays: a proof of concept study

The complexity of sepsis pathophysiology hinders patient management and therapeutic decisions. In this proof-of-concept study we characterised the underlying host immune response alterations using a standardised immune functional assay (IFA) in order to stratify a sepsis population. In septic shock patients, ex vivo LPS and SEB stimulations modulated, respectively, 5.3% (1/19) and 57.1% (12/21) of the pathways modulated in healthy volunteers (HV), highlighting deeper alterations induced by LPS than by SEB. SEB-based clustering, identified 3 severity-based groups of septic patients significantly different regarding mHLA-DR expression and TNFα level post-LPS, as well as 28-day mortality, and nosocomial infections. Combining the results from two independent cohorts gathering 20 HV and 60 patients, 1 cluster grouped all HV with 12% of patients. The second cluster grouped 42% of patients and contained all non-survivors. The third cluster grouped 46% of patients, including 78% of those with nosocomial infections. The molecular features of these clusters indicated a distinctive contribution of previously described genes defining a “healthy-immune response” and a “sepsis-related host response”. The third cluster was characterised by potential immune recovery that underlines the possible added value of SEB-based IFA to capture the sepsis immune response and contribute to personalised management.

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.

Pattern of human monocyte subpopulations in health and disease

Monocytes are important cells of the innate system. They are a heterogeneous type of cells consisting of phenotypically and functionally distinct subpopulations, which play a specific role in the control, development and escalation of the immunological processes. Based on the expression of superficial CD14 and CD16 in flow cytometry, they can be divided into three subsets: classical, intermediate and non-classical. Variation in the levels of human monocyte subsets in the blood can be observed in patients in numerous pathological states, such as infections, cardiovascular and inflammatory diseases, cancer and autoimmune diseases. The aim of this review is to summarize current knowledge of human monocyte subsets and their significance in homeostasis and in pathological conditions.

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.

Treatment With Acetylsalicylic Acid Reverses Endotoxin Tolerance in Humans In Vivo: A Randomized Placebo-Controlled Study

OBJECTIVE

To investigate immunostimulatory effects of acetylsalicylic acid during experimental human endotoxemia and in sepsis patients.

DESIGN

Double-blind, randomized, placebo-controlled study in healthy volunteers and ex vivo stimulation experiments using monocytes of septic patients.

SETTING

Intensive care research unit of an university hospital.

SUBJECTS

Thirty healthy male volunteers and four sepsis patients.

INTERVENTIONS

Healthy volunteers were challenged IV with endotoxin twice, at a 1-week interval, with each challenge consisting of a bolus of 1 ng/kg followed by continuous administration of 1 ng/kg/hr during 3 hours. Volunteers were randomized to acetylsalicylic acid prophylaxis (80 mg acetylsalicylic acid daily for a 14-d period, starting 7 d before the first endotoxin challenge), acetylsalicylic acid treatment (80 mg acetylsalicylic acid daily for the 7-d period in-between both endotoxin challenges), or the control group (receiving placebo). Furthermore, monocytes of sepsis patients were incubated with acetylsalicylic acid preexposed platelets and were subsequently stimulated with endotoxin.

MEASUREMENTS AND MAIN RESULTS

Acetylsalicylic acid prophylaxis enhanced plasma tumor necrosis factor-α concentrations upon the first endotoxin challenge by 50% compared with the control group (p = 0.02) but did not modulate cytokine responses during the second endotoxin challenge. In contrast, acetylsalicylic acid treatment resulted in enhanced plasma levels of tumor necrosis factor-α (+53%; p = 0.02), interleukin-6 (+91%; p = 0.03), and interleukin-8 (+42%; p = 0.02) upon the second challenge, whereas plasma levels of the key antiinflammatory cytokine interleukin-10 were attenuated (-40%; p = 0.003). This proinflammatory phenotype in the acetylsalicylic acid treatment group was accompanied by a decrease in urinary prostaglandin E metabolite levels (-27% ± 7%; p = 0.01). Ex vivo exposure of platelets to acetylsalicylic acid increased production of tumor necrosis factor-α (+66%) and decreased production of interleukin-10 (-23%) by monocytes of sepsis patients.

CONCLUSIONS

Treatment, but not prophylaxis, with low-dose acetylsalicylic acid, partially reverses endotoxin tolerance in humans in vivo by shifting response toward a proinflammatory phenotype. This acetylsalicylic acid-induced proinflammatory shift was also observed in septic monocytes, signifying that patients suffering from sepsis-induced immunoparalysis might benefit from initiating acetylsalicylic acid treatment.