QiXing Chen

Differential expression of alpha- and beta-defensins in human peripheral blood.

Background  Human defensin peptides with broad‐spectrum antimicrobial activity have been implicated in the human defence response towards microbial invasion. Two families of defensins designated α‐ and β‐defensins, respectively, have been identified. Little is known about the expression of both defensin families in human peripheral blood. The purpose of this study was to examine the expression of α‐ and β‐defensin genes in human peripheral blood.

Triggering Receptor Expressed on Myeloid Cells-2 Protects against Polymicrobial Sepsis by Enhancing Bacterial Clearance

RATIONALE Triggering receptor expressed on myeloid cells-2 (TREM-2) is a cell surface receptor primarily expressed on macrophages and monocyte-derived cells. TREM-2 not only functions as a regulator of inflammatory response, but also serves as a phagocytic receptor for bacteria. However, the role of TREM-2 in sepsis remains unknown. OBJECTIVES To investigate whether TREM-2 plays a role in sepsis. METHODS The manner of expression of TREM-2 was evaluated in patients with sepsis and in polymicrobial septic mouse model induced by the cecum ligation and puncture approach. Recombinant mouse TREM-2 was used to block the effect of TREM-2. Bone marrow-derived myeloid cells (BMMCs) that overexpress TREM-2 were administrated into septic mice at various times after cecum ligation and puncture. MEASUREMENTS AND MAIN RESULTS The expression levels of TREM-2 were up-regulated in patients with sepsis and septic mice. The kinetics of TREM-2 expression in polymicrobial sepsis was comparable with that of bacteria burden in peritoneal lavage fluid. Blocking the effect of TREM-2 resulted in markedly increased mortality and bacterial burden in polymicrobial sepsis. Administration of TREM-2-overexpressing BMMCs significantly reduced the mortality, even when it was administered 4 hours after the initiation of sepsis. However, injection of TREM-2-overexpressing BMMCs into LPS-challenged endotoxemia mice did not improve the survival rate. The protective effect of TREM-2 in polymicrobial sepsis was not associated with its antiinflammatory properties, but it enhanced bacterial clearance in vivo. Furthermore, administration of TREM-2-overexpressing BMMCs improved the organ injury. CONCLUSIONS TREM-2 plays an important role in the host defense response to sepsis by enhancing bacterial clearance.

Plasma sRAGE enables prediction of acute lung injury after cardiac surgery in children

IntroductionAcute lung injury (ALI) after cardiac surgery is associated with a high postoperative morbidity and mortality, but few predictors are known for the occurrence of the complication. This study evaluated whether elevated plasma levels of soluble receptor for advanced glycation end products (sRAGE) and S100A12 reflected impaired lung function in infants and young children after cardiac surgery necessitating cardiopulmonary bypass (CPB).MethodsConsecutive children younger than 3 years after cardiac surgery were prospectively enrolled and assigned to ALI and non-ALI groups, according to the American-European Consensus Criteria. Plasma concentrations of sRAGE and S100A12 were measured at baseline, before, and immediately after CPB, as well as 1 hour, 12 hours, and 24 hours after operation.ResultsFifty-eight patients were enrolled and 16 (27.6%) developed postoperative ALI. Plasma sRAGE and S100A12 levels increased immediately after CPB and remained significantly higher in the ALI group even 24 hour after operation (P < 0.01). In addition, a one-way MANOVA revealed that the overall sRAGE and S100A12 levels were higher in the ALI group than in the non-ALI group immediately after CPB (P < 0.001). The multivariate logistic regression analysis showed that the plasma sRAGE level immediately after CPB was an independent predictor for postoperative ALI (OR, 1.088; 95% CI, 1.011 to 1.171; P = 0.025). Increased sRAGE and S100A12 levels immediately after CPB were significantly correlated with a lower PaO2/FiO2 ratio (P < 0.01) and higher radiographic lung-injury score (P < 0.01), as well as longer mechanical ventilation time (sRAGEN: r = 0.405; P = 0.002; S100A12N: r = 0.322; P = 0.014), longer surgical intensive care unit stay (sRAGEN: r = 0.421; P = 0.001; S100A12N: r = 0.365; P = 0.005) and hospital stay (sRAGEN: r = 0.329; P = 0.012; S100A12N: r = 0.471; P = 0.001).ConclusionsElevated sRAGE and S100A12 levels correlate with impaired lung function, and sRAGE is a useful early biomarker of ALI in infants and young children undergoing cardiac surgery.

Increased Genomic Copy Number of DEFA1/DEFA3 Is Associated with Susceptibility to Severe Sepsis in Chinese Han Population

Background:Human neutrophil peptides 1–3 are endogenous cationic antimicrobial peptides implicated in host defense against microbes. The genes encoding human neutrophil peptides 1–3 (DEFA1/DEFA3) exhibit copy number variations. This study was designed to determine whether DEFA1/DEFA3 copy number variations conferred susceptibility to infection-induced complications such as severe sepsis. Methods:This case–control study was performed in 179 patients with severe sepsis and 233 healthy blood donors and was replicated in an independent cohort of 112 cases and 118 controls. Plasma levels of human neutrophil peptides 1–3, tumor necrosis factor-&agr;, interleukin-6, and interleukin-10 were detected. Results:The genotype of DEFA1/DEFA3 with more than eight copies was more frequent in patients with severe sepsis than in controls (55.9% vs. 31.3%; P = 1.13 × 10−6, odds ratio 2.77, 95% confidence interval 1.85–4.16). After adjustment for age and gender, logistic regression analysis confirmed the association of the genotype of more than eight copies with an increased risk of severe sepsis (P = 2.25 × 10−5, odds ratio 2.66, 95% confidence interval 1.69–4.19). This established association was replicated in a second age- and gender-matched case–control cohort (P = 0.02, odds ratio 1.90, 95% confidence interval 1.11–3.27). Furthermore, compared with those with fewer copies, the patients carrying more than eight copies of DEFA1/DEFA3 presented significantly lower plasma levels of human neutrophil peptides 1–3, tumor necrosis factor-&agr;, interleukin-6, and interleukin-10 (P = 0.039, 0.017, 0.030, and 0.029, respectively). Conclusions:DEFA1/DEFA3 is an important genetic component participating in host immune response to severe sepsis. A higher copy number of DEFA1/DEFA3 (>8 copies) is significantly associated with the risk of severe sepsis.

Circulating nucleosomes as a predictor of sepsis and organ dysfunction in critically ill patients

OBJECTIVES Sepsis is a leading cause of death in critically ill patients, and apoptosis plays a major role in the pathophysiology of sepsis. Elevated levels of circulating nucleosomes released by apoptotic cells have been detected in patients with severe sepsis and septic shock. The aim of this study was to evaluate the diagnostic/prognostic value of circulating nucleosomes in sepsis. METHODS Seventy-four newly admitted patients with an estimated length of stay in the intensive care unit of more than 48 h, were prospectively enrolled as cohort 1. The second independent cohort (cohort 2) consisted of 91 post-surgery patients. Patients receiving chemotherapy, those with AIDS, those on steroid treatment, and those undergoing transplants were excluded. Levels of circulating nucleosomes within 24h of admission in both cohorts, and for cohort 1 also on days 3, 5, and 7 and a last time-point of ICU discharge or at imminent death, were measured and analyzed for their capacity to predict sepsis. The severity of the inflammatory response and organ dysfunction were assessed by cytokine levels and sepsis scores. RESULTS Nucleosome levels on admission in septic patients were significantly higher than those in non-septic controls in both of the cohorts. The area under the receiver operating characteristic curve for admission nucleosome levels to differentiate septic patients from non-septic patients was 0.70 (95% confidence interval (CI) 0.51-0.88) in cohort 1, 0.66 (95% CI 0.55-0.79) in cohort 2, and 0.67 (95% CI 0.55-0.79) in all of the subjects. After multiple logistic regression analysis, circulating nucleosomes remained as an independent predictor of sepsis. Furthermore, the levels of circulating nucleosomes on admission were significantly correlated with the inflammatory response and organ dysfunction in sepsis. Meanwhile, a trend was observed for admission levels of circulating nucleosomes in non-survivors to be higher than those in survivors. CONCLUSIONS The level of circulating nucleosomes in the serum has a predictive value for sepsis and organ dysfunction and may serve as a candidate biomarker for the diagnosis/prognosis of sepsis. Further studies are warranted to confirm the present findings.

Effect of CYP3A4*1G on the fentanyl consumption for intravenous patient-controlled analgesia after total abdominal hysterectomy in Chinese Han population.

What is known and Objective:  Clinical investigations into postoperative intravenous patient‐controlled analgesia (PCA) have indicated interindividual differences in fentanyl consumption. Cytochrome P450 3A4 (CYP3A4) is the main metabolism enzyme of fentanyl, and single nucleotide polymorphisms within the CYP3A4 gene may contribute to the variability of fentanyl analgesic efficacy. The aim of this study was to investigate whether the most common genetic variation in Chinese, CYP3A4*1G, has an impact on the fentanyl consumption for intravenous PCA in Chinese Han women undergone abdominal total hysterectomy.

Alarmin HNP-1 promotes pyroptosis and IL-1β release through different roles of NLRP3 inflammasome via P2X7 in LPS-primed macrophages

Defensins are the first endogenous mediators to be characterized as alarmins and play multifunctional roles in immune response. Previous studies reported that human neutrophil peptide (HNP)-1, a member of the α-defensin subfamily, could regulate the IL-1β post-translational process; however, the underlying mechanism remained unknown. Using an LPS-primed THP-1 macrophage model, we found that inhibition of P2X purinoceptor 7 (P2X7) suppressed HNP-1-initiated mature IL-1β release. Confocal microscopy and glutathione S-transferase (GST) pull-down assay demonstrated that HNP-1 bound to P2X7 directly. HNP-1 treatment increased the activated level of caspase-1, and inhibition of caspase-1 abolished IL-1β release. Incubation of LPS-primed macrophages with potassium chloride also prevented HNP-1-induced export of mature IL-1β. Likewise, an ethidium bromide uptake test showed that the P2X7-K+ efflux-caspase-1 signaling pathway triggered by HNP-1 contributed to pyroptotic pore formation. Furthermore, knock down of inflammasome adaptor Nod-like receptor family pyrin domain containing 3 (NLRP3) decreased activated caspase-1 level and reduced pore formation in macrophages, whereas IL-1β release was not significantly impaired. These findings not only illustrated the mechanism for alarmin HNP-1 in enhancing inflammatory response, but also provided therapeutic targets for certain inflammatory diseases in which defensins play important roles.

Altered melatonin secretion and circadian gene expression with increased proinflammatory cytokine expression in early-stage sepsis patients.

Inflammatory and immune responses, as well as melatonin secretion, are affected by circadian regulation. Abnormal circadian rhythm of melatonin release has been reported to be associated with the later stages of sepsis; however, its role in the early stages of sepsis is unclear. We studied 11 septic and 11 non-septic patients in our intensive care unit (ICU). Peripheral blood was drawn at 4-h intervals on the first day, beginning at 2:00 p.m., over a total period of 24 h. Plasma levels of melatonin, tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) were measured by radioimmunoassay or enzyme-linked immunosorbent assay (ELISA). Messenger RNA levels of circadian genes Cry-1 and Per-2 were analyzed using quantitative real-time PCR. Results show the circadian rhythm of melatonin secretion was altered in the early stages of sepsis. The melatonin secretion acrophase occurred earlier in septic patients at 6:00 p.m., compared with at 2:00 a.m. in non-septic ICU patients. Compared with the non-septic group, both Cry-1 and Per-2 expression were significantly decreased while TNF-α and IL-6 expression were significantly increased in septic patients [TNF-α, 64.1 (43.6-89.1) vs. 11.4 (10.4-12.5) ng/ml; IL-6, 41.2 (35.7-50.8) vs. 19.1 (16-136.7) ng/ml; median (range), both P=0.04]. The peak concentrations of TNF-α and IL-6 were shown to be in concordance with the rhythm of melatonin secretion. The circadian rhythm of melatonin secretion and circadian gene expression were altered in the early stages of sepsis, which likely led to the changes in pro-inflammatory cytokine release. These findings shed light on the potential link between circadian rhythm and the progression of early-stage sepsis.

Nuclear factor-κB mediated lipopolysaccharide-induced mRNA expression of hepcidin in human peripheral blood leukocytes

Hepcidin is a known key modulator of iron homeostasis and an innate immune molecule secreted by the liver. The transcriptional mechanism of hepcidin in hepatocytes during inflammation is mediated via the IL-6/STAT3 pathway. Recently, hepcidin demonstrated an anti-inflammatory function in endotoxic mice, and a TLR4-dependent inducible expression of hepcidin was detected in myeloid cells. In this study, we explored the expression and signaling mechanism regulating hepcidin mRNA expression in peripheral blood leukocytes. The mRNA levels of hepcidin in peripheral blood leukocytes from patients with severe sepsis (n = 14) was significantly higher than those in healthy controls (n = 16;0.286 ± 0.065 vs 0.068 ± 0.025; P < 0.05). Ex vivo studies found hepcidin mRNA can be highly induced by challenge of 100 ng/ml LPS or 20 ng/ml TNF-α in peripheral blood leukocytes rather than IL-6, IL-1 and IFN-γ. Anti-TNF-α antibody significantly decreased the levels of hepcidin mRNA induced by LPS. Inhibitor of nuclear factor (NF)-κB rather than that of STAT3 completely abolished the inducibility of hepcidin mRNA in PBMCs and neutrophils. These results indicate that hepcidin mRNA expression in peripheral blood leukocytes induced by LPS depends on NF-κB, and TNF-α may be a key mediator in this procedure.

Hepatic hepcidin protects against polymicrobial sepsis in mice by regulating host iron status.

Background:Hepcidin is a master regulator of iron metabolism primarily produced by the liver. Markedly increased hepcidin levels have been observed in septic individuals, while decreased hepatic hepcidin expression has been demonstrated in liver diseases that tend to develop into sepsis. However, the role of liver hepcidin in sepsis remains unknown. Methods:Mouse hepatic hepcidin expression was silenced using adenovirus-mediated hepcidin-specific short hairpin RNA injected via the tail vein. Sepsis was induced by cecal ligation and puncture, and the outcome (n = 23 for hepcidin knockdown mice, n = 15 for controls) and pathogenic changes (n = 5) related to sepsis were evaluated. The impact of alteration of iron status on the survival rate of hepatic hepcidin knockdown mice (n = 18 to 19) was also investigated. Results:Disruption of liver hepcidin expression increased serum iron level (537.8 ± 28.1 &mgr;g/dl [mean ± SD] vs. 235.9 ± 62.2 &mgr;g/dl; P < 0.05) and reduced iron content in the spleen macrophages at the steady state. Hepatic hepcidin knockdown mice not only showed increased 7-day mortality (73.9% vs. 46.7%; P < 0.05), but also had exacerbated organ damage and oxidative stress, as well as compromised host inflammatory responses and bacterial clearance at 24 h after polymicrobial sepsis. Treating the hepatic hepcidin knockdown mice with low-iron diet plus iron chelation decreased systemic iron content (serum level: 324.0 ± 67.4 &mgr;g/dl vs. 517.4 ± 13.4 &mgr;g/dl; P < 0.05) and rescued the mice from lethal sepsis (7-day survival: 36.8% vs. 83.3%; P < 0.01). Conclusions:Hepatic hepcidin plays an important role in sepsis through regulation of iron metabolism. The findings may have potential therapeutic implications for liver diseases in which hepcidin expression is decreased.