Epidemiological and Clinical Findings of Short-Term Recurrence of Severe Acute Respiratory Syndrome Coronavirus 2 Ribonucleic Acid Polymerase Chain Reaction Positivity in 1282 Discharged Coronavirus Disease 2019 Cases: A Multicenter, Retrospective, Observational Study.

BACKGROUND: Short-term recurrence of positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ribonucleic acid (RNA) polymerase chain reaction (PCR) in discharged coronavirus disease 2019 (COVID-19) patients attracts the public's concern. This study aimed to determine the clinical and epidemiological results of such patients. METHODS: This retrospective study was conducted on 32 designated hospitals for COVID-19 patients discharged from January 14 to March 10, 2020. After 28-day followed-up, patients who tested positive again for SARS-CoV-2 RNA and confirmed by reverse-transcriptase polymerase chain reaction were re-admitted to hospital for further treatments. All of the close contacts of patients who tested positive again were asked to self-segregate for 14 days. Data of epidemiology, symptoms, laboratory tests, and treatments were analyzed in those patients, and their close contacts were investigated. RESULTS: Of 1282 discharged patients, 189 (14.74%) tested positive again for SARS-CoV-2 RNA during 28-day follow-up. The median time from discharge to the next positive test was 8 days (interquartile range [IQR], 5-13). Patients in the group that tested positive again were younger (34 vs 45 years, P < .001) with a higher proportion of moderate symptoms (95.77% vs 84.35%, P < .001) in the first hospitalization than in the negative group. During the second hospitalization, all patients who tested positive again showed normal peripheral white blood cells and lymphocytes and no new symptoms of COVID-19; 78.31% further improved on chest computed tomography scan compared with the first discharge, yet 25.93% accepted antiviral therapy. The median time of re-positive to negative test was 8 days (IQR, 4-15). None of the close contacts developed COVID-19. CONCLUSIONS: Our data suggest that the short-term recurrence of positive SARS-CoV-2 RNA in discharged patients is not a relapse of COVID-19, and the risk of onward transmission is very low. This provides important information for managing COVID-19 patients.

Hypertonic saline mediates the NLRP3/IL-1ß signaling axis in microglia to alleviate ischemic blood-brain barrier permeability by downregulating astrocyte-derived VEGF in rats.

INTRODUCTION: The aim of this study was to explore whether the antibrain edema of hypertonic saline (HS) is associated with alleviating ischemic blood-brain barrier (BBB) permeability by downregulating astrocyte-derived vascular endothelial growth factor (VEGF), which is mediated by microglia-derived NOD-like receptor protein 3 (NLRP3) inflammasome. METHODS: The infarct volume and BBB permeability were detected. The protein expression level of VEGF in astrocytes in a transient focal brain ischemia model of rats was evaluated after 10% HS treatment. Changes in the NLRP3 inflammasome, IL-1ß protein expression, and the interleukin-1 receptor (IL1R1)/pNF-кBp65/VEGF signaling pathway were determined in astrocytes. RESULTS: HS alleviated the BBB permeability, reduced the infarct volume, and downregulated the expression of VEGF in astrocytes. HS downregulates IL-1ß expression by inhibiting the activation of the NLRP3 inflammasome in microglia and then downregulates VEGF expression by inhibiting the phosphorylation of NF-кBp65 mediated by IL-1ß in astrocytes. CONCLUSIONS: HS alleviated the BBB permeability, reduced the infarct volume, and downregulated the expression of VEGF in astrocytes. HS downregulated IL-1ß expression via inhibiting the activation of the NLRP3 inflammasome in microglia and then downregulated VEGF expression through inhibiting the phosphorylation of NF-кBp65 mediated by IL-1ß in astrocytes.

Ulinastatin Ameliorates Pulmonary Capillary Endothelial Permeability Induced by Sepsis Through Protection of Tight Junctions via Inhibition of TNF-α and Related Pathways.

Background: Increased permeability of pulmonary capillary is a common consequence of sepsis that leads to acute lung injury. In this connection, ulinastatin, a urinary trypsin inhibitor (UTI), is used clinically to mitigate pulmonary edema caused by sepsis. However, the underlying mechanism of UTI in alleviating sepsis-associated pulmonary edema remains to be fully elucidated. As tight junctions (TJs) between the pulmonary microvascular endothelial cells (PMVECs) play a pivotal role in the permeability of pulmonary capillary, this study investigated the effect of UTI on expression of junctional proteins in PMVECs during sepsis. Methods: Male adult Sprague Dawley rats were subjected to cecal ligation and puncture (CLP) and divided into sham, CLP, and UTI+CLP groups. UTI was administered every 8 h for 3 days before CLP. At 48 h after surgery, Evans blue (EB) was administered to evaluate the pulmonary vascular leakage. Histological staining was used for evaluation of lung injury score. Using immunofluorescence staining and Western blot, the expression of junctional proteins (occludin, claudin-5, and ZO-1) in pulmonary endothelia was assessed. In vitro, PMVECs were divided into control, lipopolysaccharide (LPS), and UTI+LPS groups for examination of expression of junctional proteins and TNF-α as well as inhibitor of NF-κB (IκB), p38 mitogen-activated protein kinases (p38 MAPKs), c-Jun N-terminal kinases (JNKs), and extracellular signal-regulated kinases (ERKs) signaling pathways. Additionally, the expression of various junctional proteins was determined in PMVECs of control, LPS, and TNF-α receptor antagonist-LPS groups. PMVECs were also treated with TNF-α and TNF-α receptor antagonist and the expression of various junctional proteins was assessed. Results: Compared with the CLP group, UTI markedly decreased EB leakage and lung injury score. The expression of occludin, claudin-5, and ZO-1 was decreased in both CLP rats and LPS-treated PMVECs, but it was reversed by UTI and TNF-α receptor antagonist. TNF-α expression was vigorously elevated in the lung of CLP rats and in LPS-challenged PMVECs, which were suppressed by UTI. In addition, TNF-α also reduced occludin, claudin-5, and ZO-1 expression in PMVECs, but these effects of TNF-α were antagonized by pretreatment with TNF-α receptor antagonist. Furthermore, UTI inhibited LPS-induced activation of NF-κB and mitogen-activated protein kinases (MAPKs) pathways in PMVECs. Conclusion: UTI effectively protects TJs and helps to attenuate the permeability of pulmonary capillary endothelial cells during sepsis through inhibiting NF-κB and MAPKs signal pathways and TNF-α expression.

Effect of bone marrow mesenchymal stem cells on the polarization of macrophages.

Inflammation is a defensive response in the living tissue of the vascular system that acts against damage factors and involves various types of immune cells, including macrophages, neutrophils, endothelial cells and other associated immune molecules. If the release of inflammatory mediators is excessive, systemic inflammatory response syndrome may develop. Sepsis is the most common complication of severe burns and is a systemic inflammatory response syndrome that is caused by infectious factors and is capable of leading to multiple organ dysfunction and potentially death. Research concerning the mechanism and treatment of sepsis is crucial. Macrophages are an important type of immune cell that remove invasive pathogens and are involved in innate and adaptive immune responses. It has been previously reported that bone marrow mesenchymal stem cells (BMSCs) affect macrophages by regulating immunity. The present study aimed to investigate the effect of BMSCs on macrophage polarization in vivo and in vitro, in addition to the potential therapeutic effect of these cells on experimental sepsis. BMSCs and peritoneal macrophages were isolated from Sprague­Dawley rats and co­cultured overnight as a mixed culture or Transwell system, and subsequently stimulated with 100 ng/ml lipopolysaccharide (LPS). After 12 h, the medium was replaced with normal complete medium for various durations and supernatants were collected to extract proteins and cells for ELISA, western blot and flow cytometry analysis to investigate different aspects of macrophages. Sepsis was induced in Sprague­Dawley rats by injection of LPS (5 mg/kg), followed by tail vein injection of BMSCs or PBS 1 h later. After 6, 12, 24 and 48 h, lung tissues were harvested for pathological observation and peritoneal macrophages were collected for flow cytometry analysis to assess the expression of markers, including cluster of differentiation (CD)68 (used for gating), CD11c and CD206. The results demonstrated that, in the culture medium, LPS stimulation increased the expression of CD11c in macrophages, and the levels of tumor necrosis factor­α and inducible nitric oxide synthase were also increased. By contrast, in macrophages treated with BMSCs directly, the expression of CD11c was reduced compared with the LPS­stimulated macrophage alone group. However, the secretion of interleukin­10, transforming growth factor­ß and arginase­1 was increased in the direct co­culture group, compared with the LPS­stimulated macrophage alone group. BMSCs reduced the inflammation in lung tissues and inhibited macrophage expression of CD11c in the rat model of sepsis. The results of the present study demonstrated that BMSCs co­cultured with macrophages directly inhibited macrophage differentiation into the M1 phenotype and reduced inflammation in macrophages stimulated by LPS. In vivo, BMSCs decreased the expression of CD11c in peritoneal macrophages and reduced the pathological inflammatory response in the lungs. The findings of the present study demonstrated that BMSCs may reduce the extent of the systemic inflammatory response, which may contribute to the development for a novel type of treatment for sepsis in the future.

Hypercapnia induces IL-1ß overproduction via activation of NLRP3 inflammasome: implication in cognitive impairment in hypoxemic adult rats.

BACKGROUND: Cognitive impairment is one of common complications of acute respiratory distress syndrome (ARDS). Increasing evidence suggests that interleukin-1 beta (IL-1ß) plays a role in inducing neuronal apoptosis in cognitive dysfunction. The lung protective ventilatory strategies, which serve to reduce pulmonary morbidity for ARDS patients, almost always lead to hypercapnia. Some studies have reported that hypercapnia contributes to the risk of cognitive impairment and IL-1ß secretion outside the central nervous system (CNS). However, the underlying mechanism of hypercapnia aggravating cognitive impairment under hypoxia has remained uncertain. This study was aimed to explore whether hypercapnia would partake in increasing IL-1ß secretion via activating the NLRP3 (NLR family, pyrin domain-containing 3) inflammasome in the hypoxic CNS and in aggravating cognitive impairment. METHODS: The Sprague-Dawley (SD) rats that underwent hypercapnia/hypoxemia were used for assessment of NLRP3, caspase-1, IL-1ß, Bcl-2, Bax, and caspase-3 expression by Western blotting or double immunofluorescence, and the model was also used for Morris water maze test. In addition, Z-YVAD-FMK, a caspase-1 inhibitor, was used to treat BV-2 microglia to determine whether activation of NLRP3 inflammasome was required for the enhancing effect of hypercapnia on expressing IL-1ß by Western blotting or double immunofluorescence. The interaction effects were analyzed by factorial ANOVA. Simple effects analyses were performed when an interaction was observed. RESULTS: There were interaction effects on cognitive impairment, apoptosis of hippocampal neurons, activation of NLRP3 inflammasome, and upregulation of IL-1ß between hypercapnia treatment and hypoxia treatment. Hypercapnia + hypoxia treatment caused more serious damage to the learning and memory of rats than those subjected to hypoxia treatment alone. Expression levels of Bcl-2 were reduced, while that of Bax and caspase-3 were increased by hypercapnia in hypoxic hippocampus. Hypercapnia markedly increased the expression of NLRP3, caspase-1, and IL-1ß in hypoxia-activated microglia both in vivo and in vitro. Pharmacological inhibition of NLRP3 inflammasome activation and release of IL-1ß might ameliorate apoptosis of neurons. CONCLUSIONS: The present results suggest that hypercapnia-induced IL-1ß overproduction via activating the NLRP3 inflammasome by hypoxia-activated microglia may augment neuroinflammation, increase neuronal cell death, and contribute to the pathogenesis of cognitive impairments.

Hypertonic saline attenuates expression of Notch signaling and proinflammatory mediators in activated microglia in experimentally induced cerebral ischemia and hypoxic BV-2 microglia.

BACKGROUND: Ischemic stroke is a major disease that threatens human health in ageing population. Increasing evidence has shown that neuroinflammatory mediators play crucial roles in the pathophysiology of cerebral ischemia injury. Notch signaling is recognized as the cell fate signaling but recent evidence indicates that it may be involved in the inflammatory response in activated microglia in cerebral ischemia. Previous report in our group demonstrated hypertonic saline (HS) could reduce the release of interleukin-1 beta and tumor necrosis factor-alpha in activated microglia, but the underlying molecular and cellular mechanisms have remained uncertain. This study was aimed to explore whether HS would partake in regulating production of proinflammatory mediators through Notch signaling. RESULTS: HS markedly attenuated the expression of Notch-1, NICD, RBP-JK and Hes-1 in activated microglia both in vivo and in vitro. Remarkably, HS also reduced the expression of iNOS in vivo, while the in vitro levels of inflammatory mediators Phos-NF-κB, iNOS and ROS were reduced by HS as well. CONCLUSION: Our results suggest that HS may suppress of inflammatory mediators following ischemia/hypoxic through the Notch signaling which operates synergistically with NF-κB pathway in activated microglia. Our study has provided the morphological and biochemical evidence that HS can attenuate inflammation reaction and can be neuroprotective in cerebral ischemia, thus supporting the use of hypertonic saline by clinicians in patients with an ischemia stroke.

Hypertonic saline protects brain endothelial cells against hypoxia correlated to the levels of epidermal growth factor receptor and interleukin-1ß.

OBJECTIVE: The aim of this study was to verify the protective effect of hypertonic saline (HS) on brain endothelial cells under hypoxic conditions and the relevant underlying mechanism. METHODS: bEnd.3 cells were treated with oxygen-glucose deprivation (OGD)-induced injury. To measure HS performance, cell viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt assay, and cell apoptosis was assessed by flow cytometry and Terminal deoxynucleotidyl transferase UTP nick-end labeling staining. RNA-seq was performed to assess the expression profiles and screen the candidate genes that participated in OGD-induced injury and the HS protective effect. Quantitative real-time polymerase chain reaction (qPCR) and western blot analysis were used to confirm the expression of candidate genes, and enzyme-linked immunosorbent assay was used to measure the level of interleukin (IL)-1ß. Overexpression analyses were performed to confirm the functions of the differentially expressed genes. RESULTS: HS with a concentration of 40 mmol/L NaCl had an obvious protective effect on bEnd.3 cells after OGD-induced injury, resulting in increased cell viability and a smaller percentage of apoptotic cells. According to the RNA-seq results, epidermal growth factor receptor (EGFR) was chosen as the differentially expressed gene target in this study. The qPCR and western blot analyses further confirmed that the levels of EGFR/phosphorylated epidermal growth factor receptor and IL-1ß were enhanced after OGD-induced injury, but attenuated after treatment with 40 mmol/L of NaCl HS. Overexpressed EGFR reversed the protective effect of HS that caused low viability and high rates of apoptosis in cells. CONCLUSION: HS can protect endothelial cells against OGD-induced injury, but is affected by the expression of EGFR/p-EGFR and IL-1ß.

Rapamycin inhibits lipopolysaccharide-induced neuroinflammation in vitro and in vivo.

Alzheimer's disease (AD) is the most common type of progressive neurodegenerative disorder, and is responsible for the most common form of dementia in the elderly. Inflammation occurs in the brains of patients with AD, and is critical for disease progression. In the present study, the effects of rapamycin (RAPA) on neuroinflammation lipopolysaccharide (LPS)-induced were investigated. SH­SY5Y human neuroblastoma cells were treated with 20 µg/ml LPS and 0.1, 1 or 10 nmol/l RAPA, and were analyzed at various time points (6, 12 and 24 h). The mRNA expression levels of interleukin (IL) 1ß, IL6 and hypoxia­inducible factor 1α (HIF1α) were determined using reverse transcription­quantitative polymerase chain reaction. The protein expression levels of phosphorylated (p­)S6, p­nuclear factor κB (NFκB), p­inhibitor of NFκB kinase subunit ß (IKKß) and p­tau protein were measured by western blot analysis. p­IKKß, p­NFκB, p­S6 and p­tau were significantly decreased at 6, 12 and 24 h when cells were treated with ≥0.1 nmol/ml RAPA. In addition, female Sprague Dawley rats were intracranially injected with a single dose of 100 µg/kg LPS in the absence or presence of 1 mg/kg RAPA pretreatment. Brain tissues were subjected to immunohistochemical analysis 6­24 h later, which revealed that the expression levels of HIF1α and p­S6 in rat cerebral cortex were increased following LPS injection; however, this increase was abrogated by RAPA treatment. RAPA may therefore be considered a potential therapeutic agent for the early or emergency treatment of neuroinflammation.

Huperzine A protects sepsis associated encephalopathy by promoting the deficient cholinergic nervous function.

Neuroinflammatory deregulation in the brain plays a crucial role in the pathogenesis of sepsis associated encephalopathy (SAE). Given the mounting evidence of anti-inflammatory and neuroprotective effects of the cholinergic nervous system, it is surprising that there is little information about its changes in the brain during sepsis. To elucidate the role of the cholinergic nervous system in SAE, hippocampal choline acetyltransferase, muscarinic acetylcholine receptor-1, acetylcholinesterase and acetylcholine were evaluated in LPS-induced sepsis rats. Expression of pro-inflammatory cytokines, neuronal apoptosis, and animal cognitive performance were also assessed. Furthermore, therapeutic effects of the acetylcholinesterase inhibitor Huperzine A (HupA) on the hippocampal cholinergic nervous function and neuroinflammation were evaluated. A deficiency of the cholinergic nervous function was revealed in SAE, accompanied with over-expressed pro-inflammatory cytokines, increase in neuronal apoptosis and brain cognitive impairment. HupA remarkably promoted the deficient cholinergic nervous function and attenuated the abnormal neuroinflammation in SAE, paralleled with the recovery of brain function. We suggest that the deficiency of the cholinergic nervous function and the abnormal neuroinflammation are synergistically implicated in the pathogenesis of SAE. Thus, HupA is a potential therapeutic candidate for SAE, as it improves the deficient cholinergic nervous function and exerts anti-inflammatory action.

Hypertonic saline alleviates cerebral edema by inhibiting microglia-derived TNF-α and IL-1ß-induced Na-K-Cl Cotransporter up-regulation.

BACKGROUND: Hypertonic saline (HS) has been successfully used clinically for treatment of various forms of cerebral edema. Up-regulated expression of Na-K-Cl Cotransporter 1 (NKCC1) and inflammatory mediators such as tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1ß) has been demonstrated to be closely associated with the pathogenesis of cerebral edema resulting from a variety of brain injuries. This study aimed to explore if alleviation of cerebral edema by 10% HS might be effected through down-regulation of inflammatory mediator expression in the microglia, and thus result in decreased NKCC1 expression in astrocytes in the cerebral cortex bordering the ischemic core. METHODS: The Sprague-Dawley (SD) rats that underwent right-sided middle cerebral artery occlusion (MCAO) were used for assessment of NKCC1, TNF-α and IL-1ß expression using Western blotting, double immunofluorescence and real time RT-PCR, and the model also was used for evaluation of brain water content (BWC) and infarct size. SB203580 and SP600125, specific inhibitors of the p38 and JNK signaling pathways, were used to treat primary microglia cultures to determine whether the two signaling pathways were required for the inhibition of HS on microglia expressing and secreting TNF-α and IL-1ß using Western blotting, double immunofluorescence and enzyme-linked immunosorbent assay (ELISA). The effect of TNF-α and IL-1ß on NKCC1 expression in primary astrocyte cultures was determined. In addition, the direct inhibitory effect of HS on NKCC1 expression in primary astrocytes was also investigated by Western blotting, double immunofluorescence and real time RT-PCR. RESULTS: BWC and infarct size decreased significantly after 10% HS treatment. TNF-α and IL-1ß immunoexpression in microglia was noticeably decreased. Concomitantly, NKCC1 expression in astrocytes was down-regulated. TNF-α and IL-1ß released from the primary microglia subjected to hypoxic exposure and treatment with 100 mM HS were decreased. NKCC1 expression in primary astrocytes was concurrently and progressively down-regulated with decreasing concentration of exogenous TNF-α and IL-1ß. Additionally, 100 mM HS directly inhibited NKCC1 up-regulation in astrocytes under hypoxic condition. CONCLUSIONS: The results suggest that 10% HS alleviates cerebral edema through inhibition of the NKCC1 Cotransporter, which is mediated by attenuation of TNF-α and IL-1ß stimulation on NKCC1.

[Clinical value of extravascular lung water and preload parameters in weaning of mechanical ventilation in patients with septic shock].

OBJECTIVE: To investigate the values of extravascular lung water and preload parameters of weaning from mechanical ventilation on patients with septic shock. METHODS: A prospective study was conducted. A total of 52 septic shock patients with mechanical ventilation were enrolled from January 2010 to July 2012. All patients were treated and monitored by pulse induced continuous cardiac output (PiCCO) till they reached weaning criteria, and then spontaneous breathing trial (SBT), weaning, and extubation were performed in turn. The enrolled patients were divided into two groups including successful weaning group (n=38) and weaning failure group (n=14) according to clinical manifestations during 48 hours after weaning. Extravascular lung water index (EVLWI), preload parameters such as global end diastolic volume index (GEDVI) and intra-thoracic blood volume index (ITBVI), pulmonary vascular permeability index (PVPI) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) were compared at the time before weaning, 0.5 hour after weaning, 0.5 hour after extubation, and time of weaning failure or 48 hours after weaning. The patients in weaning failure group were sub-divided into high PVPI group (PVPI≥1.5 ml/m(2)) and low PVPI group (PVPI<1.5 ml/m(2)), the NT-proBNP and pulmonary blood volume (PBV) were compared between two groups. RESULTS: Before weaning, there was no statistical difference in NT-proBNP, volume parameters and EVLWI between two groups. EVLWI, GEDVI, ITBVI, PVPI and log NT-proBNP were gradually increased after weaning and extubation in two groups. The EVLWI, PVPI and log NT-proBNP were significantly higher at end point of observation in weaning failure group compared with those in successful weaning group (EVLWI: 12.81±2.13 ml/kg vs. 8.48±1.53 ml/kg, PVPI: 2.79±1.29 ml/m(2) vs. 2.19±0.94 ml/m(2), log NT-proBNP: 3.72±0.35 vs. 3.44±0.28, P<0.05 or P<0.01). GEDVI, ITBVI at 0.5 hour after weaning and end point of observation in weaning failure group were significantly higher than those in successful weaning group (0.5 hour after extubation: GEDVI 986.29±166.44 ml/m(2) vs. 856.47±149.15 ml/m(2), ITBVI: 1171.07±167.03 ml/m(2) vs. 1045.79±146.09 ml/m(2); end point of observation: GEDVI 957.00±67.25 ml/m(2) vs. 816.86±27.58 ml/m(2), ITBVI: 1184.29±209.68 ml/m(2) vs. 993.79±168.90 ml/m(2), P<0.05 or P<0.01). Sub-analysis showed that in weaning failure group, higher log NT-proBNP and PBV were found in patients with low PVPI compared with those with high PVPI (log NT-proBNP: 4.02±0.11 vs. 3.71±0.23, PBV: 507.19±25.72 ml vs. 347.85±47.52 ml, P<0.05 and P<0.01). CONCLUSIONS: Increased EVLW is the reason of pulmonary edema caused by weaning in septic shock patients, to which both hydrostatic and pulmonary permeability may contribute, and the latter could be more important. Monitoring preload parameters could help distinguish the mechanism of pulmonary edema after weaning, which may be useful in treatment.

Role of microglia in the process of inflammation in the hypoxic developing brain.

The developing brain is susceptible to hypoxic damage because of its high oxygen and energy requirements. Hypoxia-induced inflammatory response has been recognized as one of the main culprits in the development of hypoxic brain injury. In this regard, a hallmark feature is microglial activation which results in overproduction of inflammatory cytokines, free radicals and nitric oxide. Concomitantly, activated microglia exhibit enhanced expression of ion channels such as Kv1.2, Kv1.1 and Nav which further promote the release of inflammatory cytokines, chemokines and reactive oxygen species. Through the above-mentioned inflammatory mediators, activated microglia induce neuronal loss, axonal damage and oligodendroglial death along with myelination disturbances. Our recent studies have extended that tumor necrosis factor-alpha, interleukin-1beta, monocyte chemoattractant protein-1 and macrophage colony stimulating factor produced by activated microglia are linked to the pathogenesis of periventricular white matter damage in the hypoxic brain. It is envisaged that a better understanding of the interactions between microglia and neurons, axons and oligodendrocytes is key to the development of effective preventive and therapeutic strategies for mitigation of hypoxic brain injury.

A comparative study on the efficacy of 10% hypertonic saline and equal volume of 20% mannitol in the treatment of experimentally induced cerebral edema in adult rats.

BACKGROUND: Hypertonic saline and mannitol are commonly used in the treatment of cerebral edema and elevated intracranial pressure (ICP) at present. In this connection, 10% hypertonic saline (HS) alleviates cerebral edema more effectively than the equal volume of 20% mannitol. However, the exact underlying mechanism for this remains obscure. This study aimed to explore the possible mechanism whereby 10% hypertonic saline can ameliorate cerebral edema more effectively than mannitol. RESULTS: Adult male Sprague-Dawley (SD) rats were subjected to permanent right-sided middle cerebral artery occlusion (MCAO) and treated with a continuous intravenous infusion of 10% HS, 20% mannitol or D-[1-3H(N)]-mannitol. Brain water content (BWC) as analyzed by wet-to-dry ratios in the ischemic hemisphere of SD rats decreased more significantly after 10% HS treatment compared with 20% mannitol. Concentration of serum Na+ and plasma crystal osmotic pressure of the 10% HS group at 2, 6, 12 and 18 h following permanent MCAO increased significantly when compared with 20% mannitol treated group. Moreover, there was negative correlation between the BWC of the ipsilateral ischemic hemisphere and concentration of serum Na+, plasma crystal osmotic pressure and difference value of concentration of serum Na+ and concentration of brain Na+ in ipsilateral ischemic hemisphere in the 10% HS group at the various time points after MCAO. A remarkable finding was the progressive accumulation of mannitol in the ischemic brain tissue. CONCLUSIONS: We conclude that 10% HS is more effective in alleviating cerebral edema than the equal volume of 20% mannitol. This is because 10% HS contributes to establish a higher osmotic gradient across BBB and, furthermore, the progressive accumulation of mannitol in the ischemic brain tissue counteracts its therapeutic efficacy on cerebral edema.

Microglia-derived macrophage colony stimulating factor promotes generation of proinflammatory cytokines by astrocytes in the periventricular white matter in the hypoxic neonatal brain.

Inflammation in the periventricular white matter (PWM) of hypoxic neonatal brain causes myelination disturbances. In this connection, macrophage colony-stimulating factor (M-CSF) has been reported to regulate release of proinflammatory cytokines that may be linked to PWM damage. We sought to determine if M-CSF derived from amoeboid microglial cells (AMC) would promote proinflammatory cytokine production by astrocytes in the PWM following hypoxic exposure, and, if so, whether it is associated with axon degeneration and myelination disturbances. In 1-day hypoxic rats, expression of M-CSF was upregulated in AMC. This was coupled with increased expression of CSF-1 receptor, tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in astrocytes, and TNF-receptor 1 and IL-receptor 1 on the axons. Neurofilament-200 immunopositive axons and myelin basic protein immunopositive processes appeared to undergo disruption in 14-days hypoxic rats. By electron microscopy, some axons showed degenerative changes affecting the microtubules and myelin sheath. Primary cultured microglial cells subjected to hypoxia showed enhanced release of M-CSF. Remarkably, primary cultured astrocytes treated with conditioned-medium derived from hypoxic microglia or M-CSF exhibited increased production of TNF-alpha and IL-1beta. Our results suggest that AMC-derived M-CSF promotes astrocytes to generate proinflammatory cytokines, which may be involved in axonal damage following a hypoxic insult.

Systemic inflammatory response following acute traumatic brain injury.

The early, delayed, and systemic effects of acute traumatic brain injury (TBI) are the result of inflammatory mediators which initiate systemic inflammatory response syndrome (SIRS), subsequent complement deficits and coagulopathy. Once SIRS is triggered by acute inflammation, it can detrimentally self-propagate. Systemic inflammation causes tissue damage leading to further inflammation and damage, leaving the body in a vicious cycle of hyperinflammation. Therefore, important inflammatory mediators like interleukin (IL)-1 beta, IL-6 and tumour necrosis factor (TNF) alpha, are targeted in compensatory anti-inflammatory response syndrome (CARS) in an attempt to control the development of SIRS. The hypothalamus-pituitary (HPA)-axis and sympathetic nervous system (SNS) efferent limbs in CARS provide negative feedback for the production of inflammatory mediators. However, in the case of acute TBI, the activation of CARS often leads to the complication of immunosuppression which may result in multi-organ dysfunction syndrome (MODS) and mortality. In light of this, the activation of the SIRS following acute TBI does not bode well. If left uncontrolled, multiple systems will be implicated making it difficult to remedy.