ABT-263 enhanced bacterial phagocytosis of macrophages in aged mouse through Beclin-1-dependent autophagy.

BACKGROUND: Sepsis is a critical challenge for the older adults as the immune function is less responsive by aging. Although cell numbers seem preserved in the older adults, macrophages present age-related function decline, which including reduced chemokines, phagocytosis, and autophagy. ABT-263, an inhibitor of the anti-apoptotic protein Bcl-2, is reported had a senolytic effect which can selectively clear the senescent cells in vivo and rejuvenate the aged tissues. METHODS: We treated the aged (12-16 months) and young (4-6 months) C57BL/6 mouse with ABT-263, then gave the animals cecal slurry injection to induce sepsis to observe the effect of senolytic compound ABT-263 on the survival rate of sepsis. Additionally, we isolated peritoneal macrophages from the aged mouse to investigate the cell function and molecular mechanism. 3-methyladenine (3-MA), a phosphatidylinositol 3-kinases (PI3K) inhibitor, and rapamycin, an autophagy-enhancer, were used to block or mimic the autophagy, respectively. RT-PCR and Western Blot were used to detect autophagy related gene and protein changes in sepsis. EGFP-expressing E. coli was used as a marker to evaluate the phagocytic ability of macrophages. RESULTS: The results showed ABT-263 treatment improved the survival rate of sepsis in the aged mouse which related to autophagy, while blocking the autophagy can eliminate this effect. It is revealed that ABT-263 enhanced the phagocytic ability of the peritoneal macrophages by increasing the Trem-2 receptor. Additionally, ABT-263 blocked the binding of Bcl-2 to Beclin-1, thus induced Beclin-1-dependent autophagy. CONCLUSION: ABT-263 enhanced the macrophage function in aged mouse by increasing the Trem-2 receptors and inducing a beclin-1-dependent autophagy, consequently, protected the aged mouse from sepsis.

Defensins and sepsis.

Sepsis is a leading cause of mortality and morbidity in the critical illness. Multiple immune inflammatory processes take part in the pathogenesis of sepsis. Defensins are endogenous antimicrobial peptides with three disulphide bonds created by six cysteine residues. Besides the intrinsic microbicidal properties, defensins are active players which modulate both innate and adaptive immunity against various infections. Defensins can recruit neutrophils, enhance phagocytosis, chemoattract T cells and dendritic cells, promote complement activation, and induce IL-1ß production and pyrotosis. Previous publications have documented that defensins play important roles in a series of immune inflammatory diseases including sepsis. This review aims to briefly summarize in vitro, in vivo, and genetic studies on defensins' effects as well as corresponding mechanisms within sepsis and highlights their promising findings which may be potential targets in future therapies of sepsis.

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.

[Early high-volume hemofiltration treatment in severe sepsis].

OBJECTIVE: To evaluate the effect of early application of high-volume hemofiltration treatment (HVHF) on the levels of lactic acid, pro-inflammatory cytokines and C-reactive protein (CRP) in plasma, as well as APACHE II score in patients suffering from severe sepsis. METHODS: Thirty patients meeting the diagnosis of severe sepsis were enrolled in the trial within 24 hours of insults. The level of lactic acid, interleukin-6 (IL-6) and CRP in plasma were measured before HVHF and at 24, 48 or 72 h following HVHF treatment. RESULT: The plasma levels of lactic acid and IL-6 decreased significantly at 24 h, 48 h, 72 h after HVHF (P <0.05), while, IL-10 did not differ significantly following HVHF (P>0.05), when compared with that before HVHF. CONCLUSION: The early application of HVHF could clear the plasma lactic acid and pro-inflammatory cytokines, and improve the tissue oxygenation in severe sepsis.

[Epidemiological study of severe sepsis in a newborn intensive care unit].

OBJECTIVES: To determine the incidence and outcome of severe sepsis in Newborn Intensive Care Unit (NICU) and to characterize their demographics and infection pattern. METHODS: Characteristics of 243 newborns admitted to NICU from June 1st, 2006 to May 31st, 2007 were retrospectively analyzed. RESULTS: Analysis of data derived from 243 newborns admitted to NICU over an 1-year period with 48 (19.8%) cases diagnosed as severe sepsis, and 70.8% of them were males. The median age of severe sepsis patients was 2 (1-6 ) days. In 56.3% of the patients bacteria were isolated, and E. coli was the predominant microbe. PRISM score and mortality rate were higher in those with severe sepsis, while their Apgar score was lower than other cases. The overall hospital mortality of severe sepsis was 45.8%. Risk factors for hospital mortality included higher PRISM score, severe organ dysfunction, circulatory system dysfunction, and hematological or central nervous system dysfunction. CONCLUSIONS: This study shows that severe sepsis is a common, frequently fatal morbid condition in critical ill newborns in NICU, showing similar disease pattern with other investigations. Further multiple-center investigations are helpful to prevent, control and salvage critically ill children suffering from severe sepsis.

[Comparison of three different organ failure assessment score systems in predicting outcome of severe sepsis].

OBJECTIVE: To compare multiple organ dysfunction score (MODS), the sequential organ failure assessment (SOFA) and the logistic organ dysfunction score (LODS) in predicting hospital mortality in severe sepsis. METHODS: Four hundred and three patients admitted to the ICU from December 2004 to November 2007 with a diagnosis of severe sepsis were enrolled in this study. Their MODS, SOFA, LODS and Acute Physiology and Chronic Health Evaluation (APACHE) II at admission and the highest score during hospitalization were respectively recorded and collected in regard to mortality. The discrimination of three multiple organ dysfunction score systems were assessed by the areas under the receiver operating characteristic curves (AUC). RESULTS: The AUC of admission scores was 0.811 for LODS, 0.787 for SOFA, 0.725 for MODS, and 0.770 for APACHE II in predicting hospital mortality. All maximum scores had better power of discrimination than the admission scores (P < 0.01). The power of discrimination of LODS and SOFA were better than the MODS, either the admission or the highest, respectively (P < 0.01). However, no significant difference was observed between the LODS and the SOFA regarding mortality prediction (P > 0.05). The AUC value for the APACHE II score was much lower compared to LODS (P < 0.01). However, there was no difference in AUC value among APACHE II, SOFA and MODS (P > 0.05). CONCLUSION: LODS, SOFA and MODS show a good discrimination power, while maximum LODS is of the highest discrimination power to predict the outcome of patient with severe sepsis.