Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells characterized by their immunosuppressive functions. MDSCs expand during chronic and acute inflammatory conditions, the best ...described being cancer. Recent studies uncovered an important role of MDSCs in the pathogenesis of infectious diseases along with sepsis. Here we discuss the mechanisms underlying the expansion and immunosuppressive functions of MDSCs, and the results of preclinical and clinical studies linking MDSCs to sepsis pathogenesis. Strikingly, all clinical studies to date suggest that high proportions of blood MDSCs are associated with clinical worsening, the incidence of nosocomial infections and/or mortality. Hence, MDSCs are attractive biomarkers and therapeutic targets for sepsis, especially because these cells are barely detectable in healthy subjects. Blocking MDSC-mediated immunosuppression and trafficking or depleting MDSCs might all improve sepsis outcome. While some key aspects of MDSCs biology need in depth investigations, exploring these avenues may participate to pave the way toward the implementation of personalized medicine and precision immunotherapy for patients suffering from sepsis.
To review the impact of the timeliness of antibiotic therapy on the outcome of patients with sepsis or septic shock.
We searched MEDLINE, EMBASE, the Cochrane Library, Web of Science, Open-SIGLE ...databases, ClinicalTrials.gov and the metaRegister of Controlled Trials on July 27, 2020 for relevant studies on the timing of antibiotic therapy in adult patients with sepsis or septic shock. The primary outcome measure was all-cause crude or adjusted mortality at reported time points.
We included 35 sepsis studies involving 154,330 patients. Nineteen studies (54%) provided information on the appropriateness of antibiotic therapy in 20,062 patients of whom 16,652 patients (83%) received appropriate antibiotics. Twenty-four studies (68.6%) reported an association between time-to-antibiotics and mortality. Time thresholds associated with patient's outcome varied considerably between studies consisting of a wide range of time cutoffs (1 h, 125 min, 3 h or 6 h) in 14 studies, hourly delays (derived from the analyses of time intervals ranging from to 1 to 24 h) in 8 studies or time-to-antibiotic in 2 studies. Analyses of subsets of studies that focused on patients with septic shock (11 studies, 12,756 patients) or with sepsis (6 studies, 24,281 patients) yielded similar results.
While two-thirds of sepsis studies reported an association between early administration of antibiotic therapy and patient outcome, the time-to-antibitiocs metrics varied significantly across studies and no robust time thresholds emerged.
Sepsis is a clinical syndrome defined as a dysregulated host response to infection resulting in life-threatening organ dysfunction. Sepsis is a major public health concern associated with one in five ...deaths worldwide. Sepsis is characterized by unbalanced inflammation and profound and sustained immunosuppression, increasing patient susceptibility to secondary infections and mortality. microRNAs (miRNAs) play a central role in the control of many biological processes, and deregulation of their expression has been linked to the development of oncological, cardiovascular, neurodegenerative and metabolic diseases. In this review, we discuss the role of miRNAs in sepsis pathophysiology. Overall, miRNAs are seen as promising biomarkers, and it has been proposed to develop miRNA-based therapies for sepsis. Yet, the picture is not so straightforward because of the versatile and dynamic features of miRNAs. Clearly, more research is needed to clarify the expression and role of miRNAs in sepsis, and to promote the use of miRNAs for sepsis management.
Trained immunity refers to the ability of the innate immune system exposed to a first challenge to provide an enhanced response to a secondary homologous or heterologous challenge. We reported that ...training induced with β-glucan one week before infection confers protection against a broad-spectrum of lethal bacterial infections. Whether this protection persists over time is unknown. To tackle this question, we analyzed the immune status and the response to
(
) of mice trained 9 weeks before analysis. The induction of trained immunity increased bone marrow myelopoiesis and blood counts of Ly6C
inflammatory monocytes and polymorphonuclear neutrophils (PMNs).
, whole blood, PMNs and monocytes from trained mice produced increased levels of cytokines in response to microbial products and limited the growth of
.
, following challenge with
, peripheral blood leukocytes were massively depleted in control mice but largely preserved in trained mice. PMNs were reduced also in the spleen from control mice, and increased in the spleen of trained mice. In transwell experiments, PMNs from trained mice showed increased spontaneous migration and CXCL2/MIP2α-induced chemotaxis, suggesting that training promotes the migration of PMNs in peripheral organs targeted by
. Trained PMNs and monocytes had higher glycolytic activity and mitochondrial respiration than control cells when exposed to
. Bacterial burden and dissemination in blood, spleen and liver as well as systemic cytokines and inflammation (multiplex bead assay and bioluminescence imaging) were reduced in trained mice. In full agreement with these results, mice trained 9 weeks before infection were powerfully protected from lethal listeriosis. Altogether, these data suggest that training increases the generation and the antimicrobial activity of PMNs and monocytes, which may confer prolonged protection from lethal bacterial infection.
Abstract
Background
Clarithromycin may act as immune-regulating treatment in sepsis and acute respiratory dysfunction syndrome. However, clinical evidence remains inconclusive. We aimed to evaluate ...whether clarithromycin improves 28-day mortality among patients with sepsis, respiratory and multiple organ dysfunction syndrome.
Methods
We conducted a multicenter, randomized, clinical trial in patients with sepsis. Participants with ratio of partial oxygen pressure to fraction of inspired oxygen less than 200 and more than 3 SOFA points from systems other than the respiratory function were enrolled between December 2017 and September 2019. Patients were randomized to receive 1 gr of clarithromycin or placebo intravenously once daily for 4 consecutive days. The primary endpoint was 28-day all-cause mortality. Secondary outcomes were 90-day mortality; sepsis response (defined as at least 25% decrease in SOFA score by day 7); sepsis recurrence; and differences in peripheral blood cell populations and leukocyte transcriptomics.
Results
Fifty-five patients were allocated to each arm. By day 28, 27 (49.1%) patients in the clarithromycin and 25 (45.5%) in the placebo group died (risk difference 3.6% 95% confidence interval (CI) − 15.7 to 22.7;
P
= 0.703, adjusted OR 1.03 95%CI 0.35–3.06;
P
= 0.959). There were no statistical differences in 90-day mortality and sepsis response. Clarithromycin was associated with lower incidence of sepsis recurrence (OR 0.21 95%CI 0.06–0.68;
P
= 0.012); significant increase in monocyte HLA-DR expression; expansion of non-classical monocytes; and upregulation of genes involved in cholesterol homeostasis. Serious and non-serious adverse events were equally distributed.
Conclusions
Clarithromycin did not reduce mortality among patients with sepsis with respiratory and multiple organ dysfunction. Clarithromycin was associated with lower sepsis recurrence, possibly through a mechanism of immune restoration.
Clinical trial registration
clinicaltrials.gov identifier
NCT03345992
registered 17 November 2017; EudraCT 2017-001056-55.
We used unsupervised immunophenotyping of blood leukocytes and measured cytokine production by innate immune cell exposed to LPS and R848. We show that COVID‐19 induces a rapid, transient ...upregulation of myeloid‐derived suppressor cells (MDSCs) accompanied by a rapid, sustained (up to 3 months) hyporesponsiveness of dendritic cells and monocytes. Blood MDSCs may represent biomarkers and targets for intervention strategies in COVID‐19 patients.
Background
Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells with immunosuppressive functions sub-classified into monocytic and polymorphonuclear MDSCs (M-MDSCs and PMN-MDSCs). ...Clinical studies reported increased levels of MDSCs that were associated with poor outcome in sepsis patients. Since sepsis patients exhibit signs of inflammation and immunosuppression, MDSCs may provide benefit by dampening deleterious inflammation in some patients. To test this hypothesis, we measured MDSCs in critically ill sepsis patients with pneumonia and multi-organ dysfunctions and a high likelihood of death.
Methods
This was a prospective multicenter observational cohort study performed in eight ICUs in Athens and Thessaloniki, Greece, enrolling critically ill patients with pneumonia and sepsis with multi-organ dysfunctions. A flow cytometry approach using blood collected at study inclusion in tubes containing lyophilized antibodies combined to unsupervised clustering was developed to quantify M-MDSCs and PMN-MDSCs.
Results
Forty-eight patients were included, of whom 34 died within 90 days. At study inclusion, M-MDSCs and PMN-MDSCs were increased in sepsis patients when compared to healthy subjects (3.07% vs 0.96% and 22% vs 2.1% of leukocytes, respectively;
p
< 10
–4
). Increased PMN-MDSCs were associated with secondary infections (
p
= 0.024) and new sepsis episodes (
p
= 0.036). M-MDSCs were more abundant in survivors than in patients who died within 28 days (
p
= 0.028). Stratification of patients according to M-MDSC levels revealed that high levels of M-MDSC were associated with reduced 90-day mortality (high vs low M-MDSCs: 47% vs 84% mortality,
p
= 0.003, hazard ratio HR = 3.2, 95% CI 1.4–7.2). Combining high M-MDSC levels with low Acute Physiology and Chronic Health Evaluation (APACHE) II score improved patient stratification (M-MDSCs
high
/APACHE II
low
vs M-MDSCs
low
/APACHE II
low
: 20% vs 80% 90-day mortality,
p
= 0.0096, HR = 7.2, 95% CI 1.6–32). In multivariate analyses high M-MDSCs remained correlated with improved survival in patients with low APACHE II score (
p
= 0.05, HR = 5.26, 95% CI 1.0–27.8).
Conclusion
This is the first study to associate high levels of M-MDSCs with improved survival in sepsis patients.
Background
Systemic inflammatory response syndrome (SIRS) is a clinical syndrome following inflammation. Clinically, it is difficult to distinguish SIRS following an infection, i.e., sepsis, from ...non-infectious SIRS. Myeloperoxidase is a hemeprotein stored in the neutrophil azurophilic granules and is one of the main pillars of neutrophil attack. Therefore, we hypothesized that myeloperoxidase can differentiate between sepsis and non-infectious SIRS in patients with systemic inflammatory response syndrome in the intensive care unit (ICU).
Methods
An observational single-center cohort study was conducted measuring myeloperoxidase in patients with SIRS in the first 48 h after admission. The outcomes were established using predefined definitions. Thirty-day mortality was retrospectively assessed.
Results
We found significantly higher levels of myeloperoxidase in patients with sepsis and septic shock compared to patients without sepsis (60 ng/ml versus 43 ng/ml,
P
= 0.002). Myeloperoxidase levels were related to 30-day mortality (
P
= 0.032), and high MPO levels on top of a high APACHE IV score further increased mortality risk.
Conclusions
We show that myeloperoxidase is a potentially novel biomarker for sepsis in the ICU. Myeloperoxidase could eventually help in diagnosing sepsis and predicting mortality. However, more research is necessary to confirm our results.
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