Mechanism of myeloid differentiation factor 2 on mediating sepsis-associated encephalopathy / 中华危重病急救医学

OBJECTIVE@#To investigate the role and underlying mechanism of human myeloid differentiation protein 2 (MD2) in the process of neuronal death induced by lipopolysaccharide (LPS) by establishing an in vitro model of sepsis-associated encephalopathy (SAE) by LPS.@*METHODS@#Healthy C57BL/6J mice at 14-18 days of gestation were selected, and brain cortical tissue was taken from fetal mice. Neurons were stimulated with 0 (control), 1, 5 and 10 g/L of LPS for 24 hours. The release of lactate dehydrogenase (LDH) was detected and the death of neurons was observed. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of inflammatory factors interleukins (IL-6, IL-1β), in order to determine the optimal dose of LPS for establishing an in vitro neuroinflammation model of SAE. The cells were divided into blank control group and LPS group. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL) was used to discover apoptosis. Western blotting was used to detect the expression of the relevant protein markers activated caspase-3, necroptosis-associated protein neuronal receptor-interacting serine/threonine-protein kinase 3 (RIPK3) and phosphorylated RIPK3 (p-RIPK3). Immunofluorescence chemical staining was used to detect the expressions of p-RIPK3 and microtubule-associated protein 2 (MAP2) to evaluate the type of cell death and the degree of neuronal death. Western blotting was used to detect MD2 expression. Immunofluorescence chemical staining was performed to observe the expression and distribution of p-RIPK3 and MD2 in neurons to assess whether MD2 was involved in the inflammatory response promoting neuronal death. In addition, the cells were divided into blank control group, LPS group, and MD2 interfering peptide group (LPS+TC group), and the levels of IL-6, IL-1β and LDH were detected to evaluate whether interfering with MD2 can alleviate LPS induced neuroinflammation.@*RESULTS@#10 g/L LPS induced notable neuronal death, and the release of LDH in neurons stimulated with this concentration for 24 hours was significantly higher than that in the blank control group (relative release: 1.45±0.04 vs. 1.00±0.00, P < 0.01), indicating apoptosis and necroptosis occurred in neurons, and the levels of inflammatory factors IL-6 and IL-1β were remarkable increased [IL-6 (relative level): 1.94±0.04 vs. 1.00±0.00, IL-1β (relative level): 1.53±0.09 vs. 1.00±0.00, both P < 0.01]. Compared with the blank control group, the apoptosis of cells, cleaved-caspase-3 expression, the p-RIPK3/RIPK3 ratio, and p-RIPK3 expression around neurons in the LPS group were significantly increased [cleaved-caspase-3/GAPDH: 1.55±0.10 vs. 1.00±0.00, P < 0.01; p-RIPK3/RIPK3 ratio (relative value): 1.54±0.06 vs. 1.00±0.00, P < 0.05], which suggested that typical apoptosis and necroptosis apoptosis occurred in neurons in the septic environment. Furthermore, MD2 expression was significantly increased in the LPS group compared with the blank control group (MD2/GAPDH: 1.91±0.07 vs. 1.00±0.00, P < 0.01), and MD2 expression around neurons was increased, indicating that LPS-induced MD2 upregulation may play a key role in neuroinflammation and induction of neuronal death in sepsis. In addition, compared with the LPS group, the MD2-interfering peptide could reduce the expression levels of inflammatory factors IL-6 and IL-1β [IL-6 (relative level): 1.16±0.08 vs. 1.94±0.04, IL-1β (relative level): 1.15±0.05 vs. 1.75±0.09, both P < 0.01] and decrease LDH release (relative release: 1.09±0.01 vs. 1.44±0.04, P < 0.05).@*CONCLUSIONS@#LPS induced neuronal inflammatory responses via MD2, which ultimately leads to apoptosis and necroptosis. Interfering with MD2 reduces inflammation and inhibits neuronal death.

Recent progress of antimicrobial peptides in sepsis treatment / 中华危重病急救医学

Sepsis is a life-threatening organ dysfunction due to the dysregulation of host responses during infection. Severe systemic inflammatory response syndrome (SIRS) is the primary pathophysiological feature. Despite the classical antibiotic therapies play an important role in sepsis, the emergence of multi-resistant bacteria makes a greater challenge in clinical. Antimicrobial peptides (AMP) which consist of small cationic peptides, can be found in most organisms. As a result of their board-spectrum antibacterial activities and immunoregulatory functions, AMPs may have an excellent effect on the treatment of sepsis. In this review, we will discuss the basic role of AMPs in sepsis treatment and their application prospect and the challenges which need to be resolved in order to provide ideas for clinical application of AMPs.

How to improve the teaching ability of young teachers of critical care medicine? / 中华危重病急救医学

Intensive care unit (ICU) in teaching hospital plays important roles in teaching work. The young teachers of critical care medicine are gradually becoming the backbone of teaching work. Improving the teaching ability of young teachers is essential to increase learning motivation of the students and to promote the overall teaching quality of critical care medicine. Therefore, pay attention to help the young teachers of critical care medicine to improve their teaching skill is good for enhancing the faculty developing of critical care medicine, as well as essential for the prosperity and sustainable development of critical care medicine. Based on the problems existing during the teaching process of young teachers of critical care medicine and aimed to train excellent teachers, this article discussed the teaching methods and experience of young teachers of critical care medicine which focuses on teaching program design, class affinity improvement and humanistic education in order to improve the teaching level of young teachers of critical care medicine.

Neuroprotective Autophagic Flux Induced by Hyperbaric Oxygen Preconditioning is Mediated by Cystatin C / 神经科学通报·英文版

We have previously reported that Cystatin C (CysC) is a pivotal mediator in the neuroprotection induced by hyperbaric oxygen (HBO) preconditioning; however, the underlying mechanism and how CysC changes after stroke are not clear. In the present study, we demonstrated that CysC expression was elevated as early as 3 h after reperfusion, and this was further enhanced by HBO preconditioning. Concurrently, LC3-II and Beclin-1, two positive-markers for autophagy induction, exhibited increases similar to CysC, while knockdown of CysC blocked these elevations. As a marker of autophagy inhibition, p62 was downregulated by HBO preconditioning and this was blocked by CysC knockdown. Besides, the beneficial effects of preserving lysosomal membrane integrity and enhancing autolysosome formation induced by HBO preconditioning were abolished in CysC rats. Furthermore, we demonstrated that exogenous CysC reduced the neurological deficits and infarct volume after brain ischemic injury, while 3-methyladenine partially reversed this neuroprotection. In the present study, we showed that CysC is biochemically and morphologically essential for promoting autophagic flux, and highlighted the translational potential of HBO preconditioning and CysC for stroke treatment.