Raymond Kao

Endogenous HMGB1 contributes to ischemia-reperfusion-induced myocardial apoptosis by potentiating the effect of TNF-α/JNK.

High-mobility group box 1 (HMGB1) is a nuclear protein that has been implicated in the myocardial inflammation and injury induced by ischemia-reperfusion (I/R). The purpose of the present study was to assess the role of HMGB1 in myocardial apoptosis induced by I/R. In vivo, myocardial I/R induced an increase in myocardial HMGB1 expression and apoptosis. Inhibition of HMGB1 (A-box) ameliorated the I/R-induced myocardial apoptosis. In vitro, isolated cardiac myocytes were challenged with anoxia-reoxygenation (A/R; in vitro correlate to I/R). A/R-challenged myocytes also generated HMGB1 and underwent apoptosis. Inhibition of HMGB1 attenuated the A/R-induced myocyte apoptosis. Exogenous HMGB1 had no effect on myocyte apoptosis. However, inhibition of HMGB1 attenuated myocyte TNF-α production after the A/R was challenged; surprisingly, HMGB1 itself did not induce myocyte TNF-α production. Exogenous TNF-α induced a moderate proapoptotic effect on the myocytes, an effect substantially potentiated by coadministration of HMGB1. It is generally accepted that apoptosis induced by TNF-α is regulated by the balance of activation of c-Jun NH(2)-terminal kinase (JNK) and NF-κB. Indeed, in the present study, TNF-α increased the phosphorylation status of JNK and p65, a subunit of NF-κB; HMGB1 greatly potentiated TNF-α-induced JNK phosphorylation. Furthermore, inhibition of JNK (SP-600125) prevented the myocyte apoptosis induced by a TNF-α/HMGB1 cocktail. Finally, A/R increased HMGB1 production in both wild-type and toll-like receptor 4-deficient myocytes; however, deficiency in toll-like receptor 4 diminished A/R-induced myocyte apoptosis, TNF-α, and JNK activation. Our results indicate that myocyte-derived HMGB1 and TNF-α work in concert to promote I/R-induced myocardial apoptosis through JNK activation.

Reduction in IL-33 expression exaggerates ischaemia/reperfusion-induced myocardial injury in mice with diabetes mellitus

AIMS The underlying mechanism(s) of vulnerability of the diabetic myocardium to ischaemia/reperfusion (I/R)-induced injury is not fully understood. Interleukin-33 (IL-33) has been reported showing the beneficial effect to the myocardium on I/R injury. The aims of this study were to test whether diabetes mellitus (DM) affects myocardial levels of IL-33 and to examine whether reduction in IL-33 is responsible for exaggerated I/R injury in the diabetic myocardium. METHODS AND RESULTS DM hearts were challenged with I/R in vivo, whereas while isolated cardiomyocytes in vitro were conditioned with high glucose (HG) followed by an anoxia/reoxygenation (A/R) challenge. Myocardial levels of IL-33 were decreased in mice with DM which was associated with increased protein kinase C βII (PKCβII) activation. Exogenous IL-33 prevented the DM-induced PKCβII activation and attenuated I/R injuries (myocardial infarction size and apoptosis). HG-conditioned myocytes incurred exaggerated apoptosis when compared with naïve myocytes after A/R which was attenuated by IL-33. HG activated PKCβII in cardiomyocytes, which was further enhanced by A/R. IL-33 prevented the PKCβII activation in myocytes with HG or HG and A/R. Inhibition of PKCβII prevented the beneficial effect of IL-33. Finally, IL-33 up-regulated diacylglycerol kinase zeta (DGK-zeta) in cardiomyocytes and reversed the down-regulation of myocardial DGK-zeta in mice with DM. CONCLUSION Our results indicate that decreased levels of IL-33 are responsible for the increased sensitivity of the myocardium to I/R in DM. Reduction in IL-33 results in a chronic activation of PKCβII. I/R further enhances PKCβII activation in the diabetic myocardium which results in exaggeration of myocardial injury.

Diagnosis of Febrile Illnesses other than Ebola Virus Disease at an Ebola Treatment Unit in Sierra Leone

Abstract Patients with febrile illnesses presenting to an Ebola treatment unit in Sierra Leone had a wide range of diagnoses other than Ebola virus disease. Rapid diagnostic tests were useful in confirming these diagnoses, reducing the length of patient stay with valuable consequences. These alternative diagnoses should assist in future planning.

Cardiac fibroblasts contribute to myocardial dysfunction in mice with sepsis: the role of NLRP3 inflammasome activation.

Myocardial contractile dysfunction in sepsis is associated with the increased morbidity and mortality. Although the underlying mechanisms of the cardiac depression have not been fully elucidated, an exaggerated inflammatory response is believed to be responsible. Nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome is an intracellular platform that is involved in the maturation and release of interleukin (IL)-1β. The aim of the present study is to evaluate whether sepsis activates NLRP3 inflammasome/caspase-1/IL-1β pathway in cardiac fibroblasts (CFs) and whether this cytokine can subsequently impact the function of cardiomyocytes (cardiac fibroblast-myocyte cross-talk). We show that treatment of CFs with lipopolysaccharide (LPS) induces upregulation of NLRP3, activation of caspase-1, as well as the maturation (activation) and release of IL-1β. In addition, the genetic (small interfering ribonucleic acid [siRNA]) and pharmacological (glyburide) inhibition of the NLRP3 inflammasome in CFs can block this signaling pathway. Furthermore, the inhibition of the NLRP3 inflammasome in cardiac fibroblasts ameliorated the ability of LPS-chalenged CFs to impact cardiomyocyte function as assessed by intracellular cyclic adenosine monophosphate (cAMP) responses in cardiomyocytes. Salient features of this the NLP3 inflammasome/ caspase-1 pathway were confirmed in in vivo models of endotoxemia/sepsis. We found that inhibition of the NLRP3 inflammasome attenuated myocardial dysfunction in mice with LPS and increased the survival rate in mice with feces-induced peritonitis. Our results indicate that the activation of the NLRP3 inflammasome in cardiac fibroblasts is pivotal in the induction of myocardial dysfunction in sepsis.

Induction of acute lung inflammation in mice with hemorrhagic shock and resuscitation: role of HMGB1

BackgroundHemorrhagic shock and resuscitation (HS/R) can induce multiple organ failure which is associated with high mortality. The lung is an organ commonly affected by the HS/R. Acute lung injury is a major cause of dysfunction in other organ systems. The objective of this study is to test the hypothesis that HS/R causes increased gut permeability which results in induction of high mobility group box1 protein (HMGB1) and further leads to the development of acute lung inflammation.Materials and methodsA mouse model of HS/R was employed in this study. Gut permeability and bacterial translocation were assessed with circulating FD4 and lipopolysaccharide (LPS). Circulating HMGB1 was determined with ELISA. Acute lung inflammation (ALI) was determined with lung myeloperoxidase (MPO) activity and pulmonary protein leakage.ResultsHS/R induced intestinal barrier dysfunction as evidenced by increased circulating FD4 and LPS at 30 min and 2 hrs after resuscitation, respectively. In addition, circulating HMGB1 levels were increased in mice with HS/R as compared with sham animals (p < 0.05). HS/R resulted in ALI (increased lung MPO activity and pulmonary protein leakage in mice with HS/R compared with sham mice, p < 0.05). Inhibition of HMGB1 (A-box and TLR4-/-) attenuated the ALI in mice with HS/R. However, inhibition of HMGB1 did not show protective effect on gut injury in early phase of HS/R in mice.ConclusionsOur results suggest that induction of HMGB1 is important in hemorrhagic shock and resuscitation-induced acute lung inflammation.

Carbon monoxide releasing molecule-3 improves myocardial function in mice with sepsis by inhibiting NLRP3 inflammasome activation in cardiac fibroblasts

The NLRP3 inflammasome is an intracellular multiple-protein complex that controls the maturation and release of interleukin (IL)-1β and IL-18. Endogenous carbon monoxide (CO) is anti-inflammatory. The aim of this study was to assess the effects/mechanisms of CO-releasing molecule-3 (CORM-3)-dependent modulation of the NLRP3 inflammasome in cardiac fibroblasts (CF) and its effect on myocardial function in sepsis. CF were treated with CORM-3 or inactive CORM-3 (iCORM-3) before NLRP3 inflammasome priming with lipopolysaccharides (LPS) or following activation with adenosine triphosphate (ATP). In parallel, cardiomyocytes (CM) were challenged with supernatants of LPS/ATP-stimulated CF or a cytokine mixture (Cyto-mix) containing IL-1β, IL-18, and HMGB1. In vivo, mice were treated with CORM-3 before or after LPS to induce sepsis (endotoxemia). Pretreatment of CF with CORM-3 prevented an LPS-induced increase in NLRP3 and pro-IL-1β expression. Treatment of CF with CORM-3 before ATP prevented ATP-induced activation of the NLRP3 inflammasome. Challenging CF with LPS/ATP promoted NLRP3 interactions with adaptor ASC (apoptosis-associated speck-like protein containing a caspase-recruitment domain), which was prevented by CORM-3. Challenging CM with supernatants of CF with LPS/ATP or Cyto-mix (IL-1β, IL-18, and HMGB1) resulted in CM apoptosis, which was attenuated with either a CORM-3 or IL-1 receptor antagonist. Finally, myocardial NLRP3 inflammasome activation and myocardial dysfunction in septic mice were abolished by CORM-3. In NLRP3-deficient mice with sepsis, CORM-3 did not show additional benefits in improving myocardial function. Our results indicate that CORM-3 suppresses NLRP3 inflammasome activation by blocking NLRP3 interactions with the adaptor protein ASC and attenuates myocardial dysfunction in mice with sepsis.

Erythropoietin improves skeletal muscle microcirculation through the activation of eNOS in a mouse sepsis model.

BACKGROUND Sepsis and septic shock remain the major causes of morbidity and mortality in intensive care units. One mechanism that leads to organ failure is microcirculatory dysfunction. Erythropoietin (EPO) is a glycoprotein produced by the kidney that primarily regulates erythropoiesis, but it also can exert hemodynamic, anti-inflammatory, and tissue protective effects. We previously reported that administration of EPO to septic mice improves mouse skeletal muscle capillary perfusion and tissue bioenergetics. The objective of this study was to explore the potential mechanism(s) involved. METHODS Sepsis was induced by intraperitoneal (i.p.) injection of a fecal suspension (12.5 g in 0.5 saline/mouse) in mice. At 18 hours after sepsis induction, a single dose of rHuEPO (400 U/kg) was given to the mice. Mouse capillary perfusion density and nicotinamide adenine dinucleotide (NADH) fluorescence in skeletal muscle were observed using intravital microscopy. Endothelial cells derived from the skeletal muscle were treated with rHuEPO (5 U/mL) and endothelial nitric oxide synthase (eNOS) activation and activity were assessed. RESULTS Septic mice had decreased capillary perfusion density and increased tissue NADH fluorescence indicating impaired tissue bioenergetics, whereas animals treated with rHuEPO demonstrated an improvement in capillary perfusion density and decreased skeletal muscle NADH fluorescence. The beneficial effect of rHuEPO did not occur in septic mice treated with l-NAME (an NOS inhibitor, 20 mg/kg) or mice genetically deficient in eNOS. Treatment of endothelial cells with rHuEPO resulted in activation of eNOS as indicated by increased eNOS phosphorylation and NO production. CONCLUSIONS Our results suggest that eNOS plays an important role in mediating the beneficial effect of rHuEPO on microcirculation in this septic mouse model.

A Health Care Worker with Ebola Virus Disease and Adverse Prognostic Factors Treated in Sierra Leone.

We describe the management of a Sierra Leonean health care worker with severe Ebola virus disease complicated by diarrhea, significant electrolyte disturbances, and falciparum malaria coinfection. With additional resources and staffing, high quality care can be provided to patients with Ebola infection and adverse prognostic factors in west Africa.

The effect of erythropoietin on microcirculation perfusion and tissue bioenergetics of the small intestine in a hemorrhagic shock and resuscitation rat model.

BACKGROUND Erythropoietin (EPO) can exert acute hemodynamic and anti-inflammatory effects in addition to erythropoiesis. We tested the hypothesis that EPO given at resuscitation with saline will improve capillary perfusion and tissue oxygenation in the gut using a hemorrhagic shock model. METHODS Sprague-Dawley rats were bled 30 mL/kg to maintain a mean arterial blood pressure of 40 mm Hg for 50 minutes and then randomized to one of four resuscitation groups (n = 6 per group): blood, blood + recombinant human EPO (rHuEPO), saline, and saline + rHuEPO. Intravenous rHuEPO (1,000 U/kg) was given at the start of resuscitation. Intravital microscopy was used to measure perfused capillary density, flow motion of red blood cell (RBC), and tissue NADH fluorescence 60 minutes after resuscitation. Venous oxygenation saturation (Svo2) was also measured in a second experiment. RESULTS In the blood +/- rHuEPO resuscitation group, the perfused capillary density, RBC flow motion scores, and NADH fluorescence returned to near normal values. The saline + rHuEPO group compared with the saline group demonstrated an increased RBC flow motion score (2.32 vs. 1.60; p < 0.01); however, the perfused capillary density was not significantly increased (23.03 Cap/mm vs. 21.61 Cap/mm; p = 0.40). The saline + rHuEPO group also demonstrated statistically significant lower NADH fluorescence than the saline group after shock following resuscitation (110% +/- 3.64% vs. 122% +/- 4.26%; p < 0.05) suggesting decreased tissue dysoxia. The Svo2 in the saline + rHuEPO group was higher when compared with the saline group (45% vs. 38% by continuous oximetry; 38% vs. 29% by co-oximetry; p < 0.05). CONCLUSION Our results suggest that the addition of rHuEPO at the time of saline resuscitation may have beneficial effects in hemorrhagic shock by improving tissue perfusion and decreasing dysoxia in the gut.

Enhanced case management can be delivered for patients with EVD in Africa: Experience from a UK military Ebola treatment centre in Sierra Leone

Highlights • EVD is associated with life-threatening electrolyte imbalance and organ dysfunction.• Clinical staging/early warning scores can be useful EVD prognostic indicators.• Enhanced protocolized care is a blueprint for future treatment in low-resource settings.