Lulong Bo

PD-L1 blockade improves survival in experimental sepsis by inhibiting lymphocyte apoptosis and reversing monocyte dysfunction

IntroductionLymphocyte apoptosis and monocyte dysfunction play a pivotal role in sepsis-induced immunosuppression. Programmed death-1 (PD1) and its ligand programmed death ligand-1 (PD-L1) exert inhibitory function by regulating the balance among T cell activation, tolerance, and immunopathology. PD-1 deficiency or blockade has been shown to improve survival in murine sepsis. However, PD-L1 and PD-1 differ in their expression patterns and the role of PD-L1 in sepsis-induced immunosuppression is still unknown.MethodsSepsis was induced in adult C57BL/6 male mice via cecal ligation and puncture (CLP). The expression of PD-1 and PD-L1 expression on peripheral T cells, B cells and monocytes were measured 24 hours after CLP or sham surgery. Additionally, the effects of anti-PD-L1 antibody on lymphocyte number, apoptosis of spleen and thymus, activities of caspase-8 and caspase-9, cytokine production, bacterial clearance, and survival were determined.ResultsExpression of PD-1 on T cells, B cells and monocytes and PD-L1 on B cells and monocytes were up-regulated in septic animals compared to sham-operated controls. PD-L1 blockade significantly improved survival of CLP mice. Anti-PD-L1 antibody administration prevented sepsis-induced depletion of lymphocytes, increased tumor necrosis factor (TNF)-α and interleukin (IL)-6 production, decreased IL-10 production, and enhanced bacterial clearance.ConclusionsPD-L1 blockade exerts a protective effect on sepsis at least partly by inhibiting lymphocyte apoptosis and reversing monocyte dysfunction. Anti-PD-L1 antibody administration may be a promising therapeutic strategy for sepsis-induced immunosuppression.

Upregulation of programmed death-1 on T cells and programmed death ligand-1 on monocytes in septic shock patients

IntroductionStudies on the role of programmed death-1(PD-1) and its main ligand (PD-L1) during experimental models of sepsis have shown that the PD-1/PD-L1 pathway plays a pathologic role in altering microbial clearance, the innate inflammatory response and accelerated apoptosis in sepsis. However, the expression of PD-1 and PD-L1 and their role during the development of immune suppression in septic patients have not been elucidated. The present study was designed to determine whether the expression of PD-1 and PD-L1 is upregulated in septic shock patients and to explore the role of this pathway in sepsis-induced immunosuppression.MethodsNineteen septic shock patients and 22 sex-matched and age-matched healthy controls were prospectively enrolled. Apoptosis in lymphocyte subpopulations and PD-1/PD-L1 expression on peripheral T cells, B cells and monocytes were measured using flow cytometry. Apoptosis of T cells induced by TNFα or T-cell receptor ligation in vitro and effects of anti-PD-L1 antibody administration were measured by flow cytometry. CD14+ monocytes of septic shock patients were purified and incubated with either lipopolysaccharide, anti-PD-L1 antibody, isotype antibody, or a combination of lipopolysaccharide and anti-PD-L1 antibody or isotype antibody. Supernatants were harvested to examine production of cytokines by ELISA.ResultsCompared with healthy controls, septic shock induced a marked increase in apoptosis as detected by the annexin-V binding and active caspase-3 on CD4+ T cells, CD8+ T cells and CD19+ B cells. Expression of PD-1 on T cells and of PD-L1 on monocytes was dramatically upregulated in septic shock patients. PD-1/PD-L1 pathway blockade in vitro with anti-PD-L1 antibody decreased apoptosis of T cells induced by TNFα or T-cell receptor ligation. Meanwhile, this blockade potentiated the lipopolysaccharide-induced TNFα and IL-6 production and decreased IL-10 production by monocytes in vitro.ConclusionsThe expression of PD-1 on T cells and PD-L1 on monocytes was upregulated in septic shock patients. The PD-1/PD-L1 pathway might play an essential role in sepsis-induced immunosuppression.

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

IntroductionTo investigate the effects of G-CSF or GM-CSF therapy in non-neutropenic patients with sepsis.MethodsA systematic literature search of Medline, Embase and Cochrane Central Register of Controlled Trials was conducted using specific search terms. A manual review of references was also performed. Eligible studies were randomized control trials (RCTs) that compared granulocyte-colony stimulating factor (G-CSF) or granulocyte-macrophage colony stimulating factor (GM-CSF) therapy with placebo for the treatment of sepsis in adults. Main outcome measures were all-cause mortality at 14 days and 28 days after initiation of G-CSF or GM-CSF therapy, in-hospital mortality, reversal rate from infection, and adverse events.ResultsTwelve RCTs with 2,380 patients were identified. In regard to 14-day mortality, a total of 9 death events occurred among 71 patients (12.7%) in the treatment group compared with 13 events among 67 patients (19.4%) in the placebo groups. Meta-analysis showed there was no significant difference in 28-day mortality when G-CSF or GM-CSF were compared with placebo (relative risks (RR) = 0.93, 95% confidence interval (CI): 0.79 to 1.11, P = 0.44; P for heterogeneity = 0.31, I2 = 15%). Compared with placebo, G-CSF or GM-CSF therapy did not significantly reduce in-hospital mortality (RR = 0.97, 95% CI: 0.69 to 1.36, P = 0.86; P for heterogeneity = 0.80, I2 = 0%). However, G-CSF or GM-CSF therapy significantly increased the reversal rate from infection (RR = 1.34, 95% CI: 1.11 to 1.62, P = 0.002; P for heterogeneity = 0.47, I2 = 0%). No significant difference was observed in adverse events between groups (RR = 0.93, 95% CI: 0.70 to 1.23, P = 0.62; P for heterogeneity = 0.03, I2 = 58%). Sensitivity analysis by excluding one trial did not significantly change the results of adverse events (RR = 1.05, 95% CI: 0.84 to 1.32, P = 0.44; P for heterogeneity = 0.17, I2 = 36%).ConclusionsThere is no current evidence supporting the routine use of G-CSF or GM-CSF in patients with sepsis. Large prospective multicenter clinical trials investigating monocytic HLA-DR (mHLA-DR)-guided G-CSF or GM-CSF therapy in patients with sepsis-associated immunosuppression are warranted.

The Timing of Tracheotomy in Critically Ill Patients Undergoing Mechanical Ventilation: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND The objective of this study was to systematically review and quantitatively synthesize all randomized controlled trials (RCTs), comparing important outcomes in ventilated critically ill patients who received an early or late tracheotomy. METHODS A systematic literature search of PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Embase, the Cochrane Central Register of Controlled Trials, the National Research Register, the National Health Service Trusts Clinical Trials Register, and the Medical Research Council UK database was conducted using specific search terms. Eligible studies were RCTs that compared early tracheotomy (ET) with either late tracheotomy or prolonged endotracheal intubation in critically ill adult patients. RESULTS Seven trials with 1,044 patients were analyzed. ET did not significantly reduce short-term mortality (relative risk [RR], 0.86; 95% CI, 0.65-1.13), long-term mortality (RR, 0.84; 95% CI, 0.68-1.04), or incidence of ventilator-associated pneumonia (RR, 0.94; 95% CI, 0.77-1.15) in critically ill patients. The timing of the tracheotomy was not associated with a markedly reduced duration of mechanical ventilation (MV) (weighted mean difference [WMD], -3.90 days; 95% CI, -9.71-1.91) or sedation (WMD, -7.09 days; 95% CI, -14.64-0.45), shorter stay in ICU (WMD, -6.93 days; 95% CI, -16.50-2.63) or hospital (WMD, 1.45 days; 95% CI, -5.31-8.22), or more complications (RR, 0.94; 95% CI, 0.66-1.34). CONCLUSIONS The present meta-analysis suggested that the timing of the tracheotomy did not significantly alter important clinical outcomes in critically ill patients. The duration of MV and sedation, as well as the long-term outcomes of ET in mechanically ventilated patients, should be evaluated in rigorously designed and adequately powered RCTs in the future.

Dose-dependent effect of anti-CTLA-4 on survival in sepsis.

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is one of the critical inhibitory regulators of early stages of T-cell activation and proliferation, which opposes the actions of CD28-mediated costimulation. Anti-CTLA-4 therapy has been effective clinically in enhancing immunity and improving survival in patients with metastatic cancer. Sepsis is a lethal condition that shares many of the same mechanisms of immune suppression with cancer. Given the similarities in immune defects in cancer and sepsis, we examined the ability of anti-CTLA-4 antibody to block apoptosis, reverse the immunosuppression of sepsis, and improve survival in the cecal ligation and puncture model. Mice underwent sham or cecal ligation and puncture, and spleens harvested at various time points after surgery. Expression of CTLA-4 on CD4, CD8, and regulatory T cells was quantitated. Anti-CTLA-4 was administrated 6 and 24 h after surgery. Spleens were harvested at 48 h after surgery, and apoptosis and cytokine production determined. Seven-day survival studies were also conducted. Expression of CTLA-4 on CD4, CD8, and regulatory T cells increased during sepsis. Anti-CTLA-4 therapy decreased sepsis-induced apoptosis but had little effect on proinflammatory or anti-inflammatory cytokines. There was a dose-dependent effect of anti-CTLA-4 on survival. At high dose, anti-CTLA-4 worsened survival, but at lower doses, survival was significantly improved. Survival in sepsis depends on the proper balance between the proinflammatory and anti-inflammatory/immunologic systems. Anti-CTLA-4-based immunotherapy offers promise in the treatment of sepsis, but care must be used in the timing and dose of administration of the drug to prevent adverse effects.

Hydrogen-Rich Saline Protects Against Renal Ischemia/Reperfusion Injury in Rats

BACKGROUND Recently it has been demonstrated that hydrogen, as a novel antioxidant, can selectively reduce hydroxyl radicals (·OH) and peroxynitrite anion (ONOO-) in vitro and exert therapeutic antioxidant activity in many diseases. This study was designed to investigate the effect of hydrogen-rich saline on renal ischemia/reperfusion (I/R) injury in rats. METHODS A rat model of renal I/R injury was induced by 45-min occlusion of the bilateral renal pedicles and 24-h reperfusion. Physiologic saline, hydrogen-rich saline, or nitrogen-rich saline (8 mL/kg) were administered intraperitoneally at 5 min before reperfusion, respectively. RESULTS After I/R injury, serum blood urea nitrogen (BUN), creatinine (Cr), tissue malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OhdG), TNF-α, IL-1β, IL-6 levels, and myeloperoxidase (MPO) activity were all increased significantly, while tissue superoxide dismutase (SOD) and catalase (CAT) activities were all decreased significantly. Hydrogen-rich saline reversed these changes and relieved morphological renal injury and I/R-induced apoptosis, while no significant changes were observed in the nitrogen-rich saline-treated group compared with physiologic saline-treated group. CONCLUSIONS Hydrogen-rich saline is able to attenuate the renal I/R injury, which is possibly by reduction of oxidative stress and inflammation.

Accuracy of plasma sTREM-1 for sepsis diagnosis in systemic inflammatory patients: a systematic review and meta-analysis

IntroductionEarly diagnosis of sepsis is vital to the clinical course and outcome of septic patients. Recently, soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) appears to be a potential marker of infection. The objective of this systematic review and meta-analysis was to evaluate the accuracy of plasma sTREM-1 for sepsis diagnosis in systemic inflammatory patients.MethodsA systematic literature search of PubMed, Embase and Cochrane Central Register of Controlled Trials was performed using specific search terms (up to 15 October 2012). Studies were included if they assessed the accuracy of plasma sTREM-1 for sepsis diagnosis in adult patients with systemic inflammatory response syndrome (SIRS) and provided sufficient information to construct a 2 X 2 contingency table.ResultsEleven studies with a total of 1,795 patients were included. The pooled sensitivity and specificity was 79% (95% confidence interval (CI), 65 to 89) and 80% (95% CI, 69 to 88), respectively. The positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio were 4.0 (95% CI, 2.4 to 6.9), 0.26 (95% CI, 0.14 to 0.48), and 16 (95% CI, 5 to 46), respectively. The area under the curve of the summary receiver operator characteristic was 0.87 (95% CI, 0.84 to 0.89). Meta-regression analysis suggested that patient sample size and assay method were the main sources of heterogeneity. Publication bias was suggested by an asymmetrical funnel plot (P = 0.02).ConclusionsThe present meta-analysis showed that plasma sTREM-1 had a moderate diagnostic performance in differentiating sepsis from SIRS. Accordingly, plasma sTREM-1 as a single marker was not sufficient for sepsis diagnosis in systemic inflammatory patients.

Brain natriuretic peptide for prediction of mortality in patients with sepsis: a systematic review and meta-analysis

IntroductionEarly identification of septic patients at high risk of dying remains a challenge. The prognostic role of brain natriuretic peptide (BNP) or N-terminal pro-B-type natriuretic peptide (NT-proBNP) in septic patients remains controversial. The purpose of this systematic review and meta-analysis was to investigate the value of elevated BNP or NT-proBNP in predicting mortality in septic patients.MethodsPubMed, Embase and the Cochrane Central Register of Controlled Trials were searched (up to February 18, 2011). Studies were included if they had prospectively collected data on all-cause mortality in adult septic patients with either plasma BNP or NT-proBNP measurement. Studies that failed to construct a 2 × 2 table of results were excluded. Two authors independently determined the validity of included studies and extracted data.Results12 studies with a total of 1,865 patients were included. Elevated natriuretic peptides were significantly associated with increased risk of mortality (odds ratio (OR) 8.65, 95% confidence interval (CI) 4.94 to 15.13, P < 0.00001). The association was consistent for BNP (OR 10.44, 95% CI 4.99 to 21.58, P < 0.00001) and NT-proBNP (OR 6.62, 95% CI 2.68 to 16.34, P < 0.0001). The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were 79% (95% CI 75 to 83), 60% (95% CI 57 to 62), 2.27 (95% CI 1.83 to 2.81) and 0.32 (95% CI 0.22 to 0.46), respectively.ConclusionsOur results suggested that an elevated BNP or NT-proBNP level may prove to be a powerful predictor of mortality in septic patients. Future larger and more adequately powered prospective studies are warranted to clarify the assay standardization, the optimal cut-off, and the prognostic value of BNPs in conjunction with other biomarkers.

Baicalin Improves Survival in a Murine Model of Polymicrobial Sepsis via Suppressing Inflammatory Response and Lymphocyte Apoptosis

Background An imbalance between overwhelming inflammation and lymphocyte apoptosis is the main cause of high mortality in patients with sepsis. Baicalin, the main active ingredient of the Scutellaria root, exerts anti-inflammatory, anti-apoptotic, and even antibacterial properties in inflammatory and infectious diseases. However, the therapeutic effect of baicalin on polymicrobial sepsis remains unknown. Methodology/Principal Findings Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in C57BL/6 mice. Mice were infused with baicalin intraperitoneally at 1 h, 6 h and 12 h after CLP. Survival rates were assessed over the subsequent 8 days. Bacterial burdens in blood and peritoneal cavity were calculated to assess the bacterial clearance. Neutrophil count in peritoneal lavage fluid was also calculated. Injuries to the lung and liver were detected by hematoxylin and eosin staining. Levels of cytokines, including tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-10 and IL-17, in blood and peritoneum were measured by enzyme-linked immunosorbent assay. Adaptive immune function was assessed by apoptosis of lymphocytes in the thymus and counts of different cell types in the spleen. Baicalin significantly enhanced bacterial clearance and improved survival of septic mice. The number of neutrophils in peritoneal lavage fluid was reduced by baicalin. Less neutrophil infiltration of the lung and liver in baicalin-treated mice was associated with attenuated injuries to these organs. Baicalin significantly reduced the levels of proinflammatory cytokines but increased the level of anti-inflammatory cytokine in blood and peritoneum. Apoptosis of CD3+ T cell was inhibited in the thymus. The numbers of CD4+, CD8+ T lymphocytes and dendritic cells (DCs) were higher, while the number of CD4+CD25+ regulatory T cells was lower in the baicalin group compared with the CLP group. Conclusions/Significance Baicalin improves survival of mice with polymicrobial sepsis, and this may be attributed to its antibacterial property as well as its anti-inflammatory and anti-apoptotic effects.

Subglottic secretion drainage for preventing ventilator-associated pneumonia: an updated meta-analysis of randomized controlled trials.

BACKGROUND: Subglottic secretion drainage (SSD) has been shown to be associated with a lower incidence of ventilator-associated pneumonia (VAP) in a previous meta-analysis. However, a number of randomized controlled trials (RCTs) have been published since then, and so we aimed to conduct an updated meta-analysis. METHODS: A systematic literature search of Pubmed, Embase, and Cochrane Central Register of Controlled Trials was conducted using specific search terms. Eligible studies were RCTs that compared SSD with standard endotracheal tube care in mechanically ventilated adult patients. RESULTS: Ten RCTs with 2,213 patients were identified. SSD significantly reduced incidence of VAP (relative risk [RR] = 0.56, 95% confidence interval [CI]: 0.45–0.69, p < 0.00001) and early-onset VAP (RR = 0.23, 95% CI: 0.13–0.43, p < 0.00001), shortened ventilation duration by 1.55 days (95% CI: −2.40 to −0.71 days, p = 0.0003), and prolonged time to VAP by 3.90 days (95% CI: 2.56–5.24 days). Subgroup analyses suggested a significant reduction in incidence of VAP when stratified by intermittent (RR = 0.49, 95% CI: 0.34–0.71, p = 0.0001) and continuous SSD (RR = 0.61, 95% CI: 0.46–0.79, p = 0.0003). No significant differences were observed regarding incidence of late-onset VAP, overall mortality, or length of intensive care unit or hospital stay. CONCLUSIONS: This updated meta-analysis confirmed that SSD was beneficial in preventing VAP. Furthermore, the effect of SSD on late-onset VAP, comparison between intermittent and continuous SSD, and safety of SSD in mechanically ventilated patients should be evaluated in future RCTs. LEVEL OF EVIDENCE: I, meta-analysis.