Altered Inhibitory κB Alpha Expression in LPS-Stimulated Alveolar Macrophages Following Resuscitated Hemorrhagic Shock

Factors associated with posttraumatic meningitis among traumatic head injury patients: a nationwide study in Japan

Purpose

Posttraumatic meningitis is one of the severe complications that can result in increased mortality and longer hospital stay among trauma patients. Factors such as cerebrospinal fluid (CSF) fistula and basilar skull fracture are associated with posttraumatic meningitis. However, it remains unclear whether procedures such as burr hole surgery in the emergency department and decompressive craniectomy are associated with posttraumatic meningitis. The aim of this study was to assess factors associated with posttraumatic meningitis with a nationwide hospital-based trauma registry in Japan.

Methods

This was a retrospective observational study with a 12-year study period from January 2004 to December 2015. We included trauma patients registered in the Japanese Trauma Data Bank, whose head Abbreviated Injury Scale score was ≥ 3 in this study. The main endpoint was the occurrence of meningitis during hospitalization. Multivariable logistic regression analysis was used to assess independent parameters associated with posttraumatic meningitis such as CSF fistula, burr hole surgery in the emergency department, and decompressive craniectomy.

Results

Among 60,390 head injury patients with head AIS score 3 or more, 284 (0.5%) patients had posttraumatic meningitis. Factors associated with posttraumatic meningitis were burr hole surgery in the emergency department (adjusted odds ratio [AOR] 2.158 [95% confidence interval (CI) 1.401–3.325]), decompressive craniectomy (AOR 2.123 [95% CI 1.506–2.993]), external ventricular drainage (AOR 1.843 [95% CI, 1.157–2.935]), CSF leakage (AOR 3.328 [95% CI 2.205–5.022]), and basilar skull fracture (AOR 1.651 [95% CI 1.178–2.314]).

Conclusions

In this population of trauma patients, burr hole surgery in the emergency department and decompressive craniectomy was associated with posttraumatic meningitis.

Dynasore enhances the formation of mitochondrial antiviral signalling aggregates and endocytosis-independent NF-κB activation

BACKGROUND AND PURPOSE

Dynasore has been used extensively as an inhibitor of clathrin-mediated endocytosis. While studying the role of endocytosis in LPS-induced signalling events, we discovered that dynasore itself induced activation of NF-κB, independently of its effects on endocytosis and without involving the Toll-like receptor 4 signalling pathways. The purpose of this study was to characterize this novel effect and to explore the underlying mechanism of action.

EXPERIMENTAL APPROACH

We utilized gel electrophoresis, microscopy, gene knockdown and luciferase-based promoter activity to evaluate the effect of dynasore on cell signalling pathways and to delineate the mechanisms involved in its effects,

KEY RESULTS

Dynasore activated the NF-κB and IFN-β pathways by activating mitochondrial antiviral signalling protein (MAVS). We showed that MAVS is activated by NOX/Rac and forms high molecular weight aggregates, similar to that observed in response to viral infection. We also demonstrated that dynasore-induced activation of JNK occurs downstream of MAVS and is required for activation of NF-κB and IFN-β.

CONCLUSION AND IMPLICATIONS

These findings demonstrate a novel effect of dynasore on cell signalling. We describe a novel Rac1-, ROS- and MAVS-mediated signalling cascade through which dynasore dramatically activates NF-κB, mimicking the viral induction of this key inflammatory signalling pathway. Our results call attention to the need for a broader interpretation of results when dynasore is used in its traditional fashion as an inhibitor of clathrin-mediated endocytosis. These results suggest the intriguing possibility that dynasore or one of its analogues might be of value as an antiviral therapeutic strategy or vaccine adjuvant.

Inhibition of endogenous heat shock protein 70 attenuates inducible nitric oxide synthase induction via disruption of heat shock protein 70/Na(+) /H(+) exchanger 1-Ca(2+) -calcium-calmodulin-dependent protein kinase II/transforming growth factor β-activated kinase 1-nuclear factor-κB signals in BV-2 microglia

Inducible nitric oxide synthase (iNOS) critically contributes to inflammation and host defense. The inhibition of heat shock protein 70 (Hsp70) prevents iNOS induction in lipopolysaccharide (LPS)-stimulated macrophages. However, the role and mechanism of endogenous Hsp70 in iNOS induction in microglia remains unclear. This study addresses this issue in BV-2 microglia, showing that Hsp70 inhibition or knockdown prevents LPS-induced iNOS protein expression and nitric oxide production. Real-time PCR experiments showed that LPS-induced iNOS mRNA transcription was blocked by Hsp70 inhibition. Further studies revealed that the inhibition of Hsp70 attenuated LPS-stimulated nuclear translocation and phosphorylation of nuclear factor (NF)-κB as well as the degradation of inhibitor of κB (IκB)-α and phosphorylation of IκB kinase β (IKKβ). This prevention effect of Hsp70 inhibition on IKKβ-NF-κB activation was found to be dependent on the Ca(2+) /calcium-calmodulin-dependent protein kinase II (CaMKII)/transforming growth factor β-activated kinase 1 (TAK1) signals based on the following observations: 1) chelation of intracellular Ca(2+) or inhibition of CaMKII reduced LPS-induced increases in TAK1 phosphorylation and 2) Hsp70 inhibition reduced LPS-induced increases in CaMKII/TAK1 phosphorylation, intracellular pH value, [Ca(2+) ]i , and CaMKII/TAK1 association. Mechanistic studies showed that Hsp70 inhibition disrupted the association between Hsp70 and Na(+) /H(+) exchanger 1 (NHE1), which is an important exchanger responsible for Ca(2+) influx in LPS-stimulated cells. These studies demonstrate that the inhibition of endogenous Hsp70 attenuates the induction of iNOS, which likely occurs through the disruption of NHE1/Hsp70-Ca(2+) -CaMKII/TAK1-NF-κB signals in BV-2 microglia, providing further insight into the functions of Hsp70 in the CNS.

Role of alveolar macrophages in the inflammatory response after trauma

Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS), can result from both direct and indirect pulmonary damage caused by trauma and shock. In the course of ALI/ARDS, mediators released from resident cells, such as alveolar macrophages, may act as chemoattractants for invading cells and stimulate local cells to build up a proinflammatory micromilieu. Depending on the trauma setting, the role of alveolar macrophages is differentially defined. This review focuses on alveolar macrophage function after blunt chest trauma, ischemia/reperfusion, hemorrhagic shock, and thermal burns.

Dai Huang Fu Zi Tang could ameliorate intestinal injury in a rat model of hemorrhagic shock by regulating intestinal blood flow and intestinal expression of p-VASP and ZO-1

Background

Dai Huang Fu Zi Tang (DHFZT), an oriental herbal formula, has long been used clinically in treatment of intestinal obstruction, acute pancreatitis, cholecystalgia and chronic diarrhea for thousands of years. Recent studies have demonstrated that DHFZT can reduce intestinal pathological injury and the concentration of enterogenous endotoxin in an animal model. But the underlying mechanism has not been fully elucidated.

Methods

SD male rats in adult were used to model HS and treated with DHFZT. The serum concentration of endotoxin were analyzed by dynamic turbidimetric method. In addition, the blood flow of small intestine were measured using laser speckle technique. Phosphorylated vasodilator-stimulated phosphoprotein (p-VASP) and zonula occludens (ZO)-1 protein, intestinal fatty acid binding protein (IFABP) were measured by Western Blotting, RT-PCR, ELISA respectively.

Results

Present study showed that DHFZT markedly elevated the blood flow of small intestine, protected the intestinal barrier function by up-regulating the expression of ZO-1 protein and down-regulating expression of p-VASP, and notely decreased serum concentration of IFABP and endotoxin in HS.

Conclusions

These results reveal that DHFZT improves intestinal blood flow, protects the intestinal barrier function, and ameliorates intestinal endotoxaemia in rats with HS.

Trauma equals danger--damage control by the immune system

Traumatic injuries induce a complex host response that disrupts immune system homeostasis and predisposes patients to opportunistic infections and inflammatory complications. The response to injuries varies considerably by type and severity, as well as by individual variables, such as age, sex, and genetics. These variables make studying the impact of trauma on the immune system challenging. Nevertheless, advances have been made in understanding how injuries influence immune system function as well as the immune cells and pathways involved in regulating the response to injuries. This review provides an overview of current knowledge about how traumatic injuries affect immune system phenotype and function. We discuss the current ideas that traumatic injuries induce a unique type of a response that may be triggered by a combination of endogenous danger signals, including alarmins, DAMPs, self-antigens, and cytokines. Additionally, we review and propose strategies for redirecting injury responses to help restore immune system homeostasis.

Acute ethanol gavage attenuates hemorrhage/resuscitation-induced hepatic oxidative stress in rats

Acute ethanol intoxication increases the production of reactive oxygen species (ROS). Hemorrhagic shock with subsequent resuscitation (H/R) also induces ROS resulting in cellular and hepatic damage in vivo. We examined the role of acute ethanol intoxication upon oxidative stress and subsequent hepatic cell death after H/R. 14 h before H/R, rats were gavaged with single dose of ethanol or saline (5 g/kg, EtOH and ctrl; H/R_EtOH or H/R_ctrl, resp.). Then, rats were hemorrhaged to a mean arterial blood pressure of 30 ± 2 mmHg for 60 min and resuscitated. Two control groups underwent surgical procedures without H/R (sham_ctrl and sham_EtOH, resp.). Liver tissues were harvested at 2, 24, and 72 h after resuscitation. EtOH-gavage induced histological picture of acute fatty liver. Hepatic oxidative (4-hydroxynonenal, 4-HNE) and nitrosative (3-nitrotyrosine, 3-NT) stress were significantly reduced in EtOH-gavaged rats compared to controls after H/R. Proapoptotic caspase-8 and Bax expressions were markedly diminished in EtOH-gavaged animals compared with controls 2 h after resuscitation. EtOH-gavage increased antiapoptotic Bcl-2 gene expression compared with controls 2 h after resuscitation. iNOS protein expression increased following H/R but was attenuated in EtOH-gavaged animals after H/R. Taken together, the data suggest that acute EtOH-gavage may attenuate H/R-induced oxidative stress thereby reducing cellular injury in rat liver.