Sevoflurane-mediated modulation of oxidative myocardial injury.

Introduction: Volatile anesthetics offer protection when administered throughout an ischemic injury. We examined how volatile anesthetics modulate the cardiac myocytic injury associated with hydrogen peroxide. Methods: Forty-eight Long-Evans rats were divided into four groups depending on the treatment: none (CONT), Glibenclamide (GLB); Sevoflurane (SEV); or GLB+SEV. Each group was further divided into two, one of which was exposed to hydrogen peroxide (H2O2). Oral GLB was administered 48 hours before myocardial isolation. All rats were anesthetized by intraperitoneal injection of Ketamine, and the hearts were harvested after heparinization. Cardiomyocytes were isolated using a combination of mechanical mincing and enzymatic digestion. After isolation, the aliquots of cells were exposed to H2O2 and FeSO4 for 30 minutes. The cell suspensions were then bubbled for 10 minutes with 100% oxygen and 1.5% SEV if appropriate. Apoptosis was detected by fluorescein-bound annexin-V (ANX-V), necrosis by propidium iodide, and ELISA assessed caspase-3 activity in all groups. Results: There was an increase in apoptosis, necrosis, and caspase-3 activity in the cells following exposure to hydrogen peroxide. SEV reduced the rate of cell necrosis and apoptosis. Pretreatment with GLB did not alter the effects of SEV. Similarly, caspase-3 activity did not change with GLB, although SEV administration reduced this enzymatic activity in response to hydrogen peroxide. Conclusion: In this oxidant injury model, we demonstrated that incubating isolated cardiomyocytes with SEV profoundly diminished H2O2-induced apoptotic and necrotic cells compared to their CONTs. These results support the hypothesis that KATP channels are not the sole mediators associated with anesthetic preconditioning.

Antiviral Approaches against Influenza Virus.

Preventing and controlling influenza virus infection remains a global public health challenge, as it causes seasonal epidemics to unexpected pandemics. These infections are responsible for high morbidity, mortality, and substantial economic impact. Vaccines are the prophylaxis mainstay in the fight against influenza. However, vaccination fails to confer complete protection due to inadequate vaccination coverages, vaccine shortages, and mismatches with circulating strains. Antivirals represent an important prophylactic and therapeutic measure to reduce influenza-associated morbidity and mortality, particularly in high-risk populations. Here, we review current FDA-approved influenza antivirals with their mechanisms of action, and different viral- and host-directed influenza antiviral approaches, including immunomodulatory interventions in clinical development. Furthermore, we also illustrate the potential utility of machine learning in developing next-generation antivirals against influenza.

Human Innate Lymphoid Cells in Influenza Infection and Vaccination.

Influenza is a highly contagious respiratory virus that causes mild to severe respiratory illness, as well as death, and remains a serious threat to human health. Annual vaccination is the most cost-effective way to control influenza; however, the vaccine does not provide protection against emerging strains with epidemic and pandemic potential. Several antivirals have been developed to treat influenza but there is a rapid emergence of antiviral resistant strains. Therefore, there is an urgent need to understand the virus and its interactions with the host immune system so that novel strategies can be developed for prophylactic and therapeutic interventions. Innate lymphoid cells (ILCs), a family of immune cells present in the peripheral circulation and in mucosal tissues, play an important role in regulation of tissue homeostasis, inflammation, and immunity. This review examines the current understanding and therapeutic potential of ILCs during influenza virus infection in humans.

A Dual-Functioning 5'-PPP-NS1shRNA that Activates a RIG-I Antiviral Pathway and Suppresses Influenza NS1.

Retinoic acid-inducible gene-I (RIG-I) is a cytosolic pathogen sensor that is crucial against a number of viral infections. Many viruses have evolved to inhibit pathogen sensors to suppress host innate immune responses. In the case of influenza, nonstructural protein 1 (NS1) suppresses RIG-I function, leading to viral replication, morbidity, and mortality. We show that silencing NS1 with in-vitro-transcribed 5'-triphosphate containing NS1 short hairpin RNA (shRNA) (5'-PPP-NS1shRNA), designed using the conserved region of a number of influenza viruses, not only prevented NS1 expression but also induced RIG-I activation and type I interferon (IFN) expression, resulting in an antiviral state leading to inhibition of influenza virus replication in vitro. In addition, administration of 5'-PPP-NS1shRNA in prophylactic and therapeutic settings resulted in significant inhibition of viral replication following viral challenge in vivo in mice with corresponding increases of RIG-I, IFN-ß, and IFN-λ, as well as a decrease in NS1 expression.

Volatile Anesthetics and Immunity.

Historically, volatile anesthetics have demonstrated interesting interactions with both the innate and adaptive immune systems. This review organizes these interactions into four phases: recognition, recruitment, response, and resolution. These phases represent a range of proinflammatory, inflammatory, and innate and adaptive immune regulatory responses. The interaction between volatile anesthetics and the immune system is discussed in the context of pathogenesis of infectious disease.

Open Tracheostomy Gastric Acid Aspiration Murine Model of Acute Lung Injury Results in Maximal Acute Nonlethal Lung Injury.

Acid pneumonitis is a major cause of sterile acute lung injury (ALI) in humans. Acid pneumonitis spans the clinical spectrum from asymptomatic to acute respiratory distress syndrome (ARDS), characterized by neutrophilic alveolitis, and injury to both alveolar epithelium and vascular endothelium. Clinically, ARDS is defined by acute onset of hypoxemia, bilateral patchy pulmonary infiltrates and non-cardiogenic pulmonary edema. Human studies have provided us with valuable information about the physiological and inflammatory changes in the lung caused by ARDS, which has led to various hypotheses about the underling mechanisms. Unfortunately, difficulties determining the etiology of ARDS, as well as a wide range of pathophysiology have resulted in a lack of critical information that could be useful in developing therapeutic strategies. Translational animal models are valuable when their pathogenesis and pathophysiology accurately reproduce a concept proven in both in vitro and clinical settings. Although large animal models (e.g., sheep) share characteristics of the anatomy of human trachea-bronchial tree, murine models provide a host of other advantages including: low cost; short reproductive cycle lending itself to greater data acquisition; a well understood immunologic system; and a well characterized genome leading to the availability of a variety of gene deletion and transgenic strains. A robust model of low pH induced ARDS requires a murine ALI that targets mainly the alveolar epithelium, secondarily the vascular endothelium, as well as the small airways leading to the alveoli. Furthermore, a reproducible injury with wide differences between different injurious and non-injurious insults is important. The murine gastric acid aspiration model presented here using hydrochloric acid employs an open tracheostomy and recreates a pathogenic scenario that reproduces the low pH pneumonitis injury in humans. Additionally, this model can be used to examine interaction of a low pH insult with other pulmonary injurious entities (e.g., food particles, pathogenic bacteria).

Directed vaccination against pneumococcal disease.

Immunization strategies against commensal bacterial pathogens have long focused on eradicating asymptomatic carriage as well as disease, resulting in changes in the colonizing microflora with unknown future consequences. Additionally, current vaccines are not easily adaptable to sequence diversity and immune evasion. Here, we present a "smart" vaccine that leverages our current understanding of disease transition from bacterial carriage to infection with the pneumococcus serving as a model organism. Using conserved surface proteins highly expressed during virulent transition, the vaccine mounts an immune response specifically against disease-causing bacterial populations without affecting carriage. Aided by a delivery technology capable of multivalent surface display, which can be adapted easily to a changing clinical picture, results include complete protection against the development of pneumonia and sepsis during animal challenge experiments with multiple, highly variable, and clinically relevant pneumococcal isolates. The approach thus offers a unique and dynamic treatment option readily adaptable to other commensal pathogens.

The Effect of Lipopolysaccharide on Ischemic-Reperfusion Injury of Heart: A Double Hit Model of Myocardial Ischemia and Endotoxemia.

INTRODUCTION: Myocardial ischemia may coincide and interact with sepsis and inflammation. Our objective was to examine the effects of bacterial endotoxin on myocardial functions and cell injury during acute ischemia. METHODS: Rabbits were pretreated with incremental doses of E. Coli lipopolysaccharide (LPS) or normal saline. Myocardial ischemia was induced by 50-minute occlusion of left anterior descending artery. S-TNFaR was additionally used to block the effects LPS. RESULTS: Ventricular contractility as it was measured by dp/dt during systole decreased from 2445± 1298 to 1422 ± 944 mm Hg/s, P = .019. Isovolumetric relaxation time as an index of diastolic function was prolonged from 50±18 ms to 102± 64 ms following ischemia. Pretreatment with low concentrations of LPS (<1 µg) had no effect on dp/dt, while at higher concentrations it suppressed both contractility and prolonged IVRT. Cell injury as measured by cardiac troponin I level increased to 15.1± 3.2 ng/dL following ischemia and continued to rise with higher doses of LPS. While blocking TNFa did not improve the myocardial contractility after ischemia, it eliminated additional deleterious effects of LPS. CONCLUSION: Lower doses of LPS had no deleterious effect on myocardial function, whereas higher doses of this endotoxin cause cardiac dysfunction and increased extent of injury.

Halothane modulates the type i interferon response to influenza and minimizes the risk of secondary bacterial pneumonia through maintenance of neutrophil recruitment in an animal model.

BACKGROUND: To minimize the risk of pneumonia, many anesthesiologists delay anesthesia-requiring procedures when patients exhibit signs of viral upper respiratory tract infection. Postinfluenza secondary bacterial pneumonias (SBPs) are a major cause of morbidity and mortality. An increased host susceptibility to SBP postinfluenza has been attributed to physical damage to the pulmonary epithelium, but flu-induced effects on the immune system are being shown to also play an important role. The authors demonstrate that halothane mitigates the risk of SBP postflu through modulation of the effects of type I interferon (IFN). METHODS: Mice (n = 6 to 15) were exposed to halothane or ketamine and treated with influenza and Streptococcus pneumoniae. Bronchoalveolar lavage and lung homogenate were procured for the measurement of inflammatory cells, cytokines, chemokines, albumin, myeloperoxidase, and bacterial load. RESULTS: Halothane exposure resulted in decreased bacterial burden (7.9 ± 3.9 × 10 vs. 3.4 ± 1.6 × 10 colony-forming units, P < 0.01), clinical score (0.6 ± 0.2 vs. 2.3 ± 0.2, P < 0.0001), and lung injury (as measured by bronchoalveolar lavage albumin, 1.5 ± 0.7 vs. 6.8 ± 1.6 mg/ml, P < 0.01) in CD-1 mice infected with flu for 7 days and challenged with S. pneumoniae on day 6 postflu. IFN receptor A1 knockout mice similarly infected with flu and S. pneumoniae, but not exposed to halothane, demonstrated a reduction of lung bacterial burden equivalent to that achieved in halothane-exposed wild-type mice. CONCLUSION: These findings indicate that the use of halogenated volatile anesthetics modulates the type I IFN response to influenza and enhance postinfection antibacterial immunity.

Chronic constriction injury-induced nociception is relieved by nanomedicine-mediated decrease of rat hippocampal tumor necrosis factor.

Neuropathic pain is a chronic pain syndrome that arises from nerve injury. Current treatments only offer limited relief, clearly indicating the need for more effective therapeutic strategies. Previously, we demonstrated that proinflammatory tumor necrosis factor-alpha (TNF) is a key mediator of neuropathic pain pathogenesis; TNF is elevated at sites of neuronal injury, in the spinal cord, and supraspinally during the initial development of pain. The inhibition of TNF action along pain pathways outside higher brain centers results in transient decreases in pain perception. The objective of this study was to determine whether specific blockade of TNF in the hippocampus, a site of pain integration, could prove efficacious in reducing sciatic nerve chronic constriction injury (CCI)-induced pain behavior. Small inhibitory RNA directed against TNF mRNA was complexed to gold nanorods (GNR-TNF siRNA; TNF nanoplexes) and injected into the contralateral hippocampus of rats 4 days after unilateral CCI. Withdrawal latencies to a noxious thermal stimulus (hyperalgesia) and withdrawal to innocuous forces (allodynia) were recorded up to 10 days and compared with baseline values and sham-operated rats. Thermal hyperalgesia was dramatically decreased in CCI rats receiving hippocampal TNF nanoplexes; and mechanical allodynia was transiently relieved. TNF levels (bioactive protein, TNF immunoreactivity) in hippocampal tissue were decreased. The observation that TNF nanoplex injection into the hippocampus alleviated neuropathic pain-like behavior advances our previous findings that hippocampal TNF levels modulate pain perception. These data provide evidence that targeting TNF in the brain using nanoparticle-protected siRNA may be an effective strategy for treatment of neuropathic pain.

Dietary advanced glycation end-products, its pulmonary receptor, and high mobility group box 1 in aspiration lung injury.

BACKGROUND: Gastric aspiration is a significant cause of acute lung injury and acute respiratory distress syndrome. Environmental risk factors, such as a diet high in proinflammatory advanced glycation end-products (AGEs), may render some patients more susceptible to lung injury after aspiration. We hypothesized that high dietary AGEs increase its pulmonary receptor, RAGE, producing an amplified pulmonary inflammatory response in the presence of high mobility group box 1 (HMGB1), a RAGE ligand and an endogenous signal of epithelial cell injury after aspiration. MATERIALS AND METHODS: CD-1 mice were fed either a low AGE or high AGE diet for 4 wk. After aspiration injury with acidified small gastric particles, bronchoalveolar lavage and whole-lung tissue samples were collected at 5 min, 1 h, 5 h, and 24 h after injury. RAGE, soluble RAGE (sRAGE), HMGB1, cytokine and chemokine concentrations, albumin levels, neutrophil influx, and lung myeloperoxidase activity were measured. RESULTS: We observed that high AGE-fed mice exhibited greater pulmonary RAGE levels before aspiration and increased bronchoalveolar lavage sRAGE levels after aspiration compared with low AGE-fed mice. Lavage HMGB1 levels rose immediately after aspiration, peaking at 1 h, and strongly correlated with sRAGE levels in both dietary groups. High AGE-fed mice demonstrated higher cytokine and chemokine levels with increased pulmonary myeloperoxidase activity over 24 h versus low AGE-fed mice. CONCLUSIONS: This study indicates that high dietary AGEs can increase pulmonary RAGE, augmenting the inflammatory response to aspiration in the presence of endogenous damage signals such as HMGB1.

Low pH environmental stress inhibits LPS and LTA-stimulated proinflammatory cytokine production in rat alveolar macrophages.

Gastric aspiration increases the risks for developing secondary bacterial pneumonia. Cytokine elaboration through pathogen recognition receptors (PRRs) is an important mechanism in initiating innate immune host response. Effects of low pH stress, a critical component of aspiration pathogenesis, on the PRR pathways were examined, specifically toll-like receptor-2 (TLR2) and TLR4, using isolated rat alveolar macrophages (aMØs). We assessed the ability of aMØs after brief exposure to acidified saline to elaborate proinflammatory cytokines in response to lipopolysaccharide (LPS) and lipoteichoic acid (LTA) stimulation, known ligands of TLR4 and TLR2, respectively. Low pH stress reduced LPS- and LTA-mediated cytokine release (CINC-1, MIP-2, TNF-α, MCP-1, and IFN-ß). LPS and LTA increased intracellular Ca²âº concentrations while Ca²âº chelation by BAPTA decreased LPS- and LTA-mediated cytokine responses. BAPTA blocked the effects of low pH stress on most of LPS-stimulated cytokines but not of LTA-stimulated responses. In vivo mouse model demonstrates suppressed E. coli and S. pneumoniae clearance following acid aspiration. In conclusion, low pH stress inhibits antibacterial cytokine response of aMØs due to impaired TLR2 (MyD88 pathway) and TLR4 signaling (MyD88 and TRIF pathways). The role of Ca²âº in low pH stress-induced signaling is complex but appears to be distinct between LPS- and LTA-mediated responses.

Interkingdom signaling induces Streptococcus pneumoniae biofilm dispersion and transition from asymptomatic colonization to disease.

UNLABELLED: Streptococcus pneumoniae is a common human nasopharyngeal commensal colonizing 10% to 40% of healthy individuals, depending on age. Despite a low invasive disease rate, widespread carriage ensures that infection occurs often enough to make S. pneumoniae a leading bacterial cause of respiratory disease worldwide. However, the mechanisms behind transition from asymptomatic colonization to dissemination and disease in otherwise sterile sites remain poorly understood but are epidemiologically strongly linked to infection with respiratory viruses. In this report, we show that infection with influenza A virus and treatment with the resulting host signals (febrile-range temperatures, norepinephrine, extracytoplasmic ATP, and increased nutrient availability) induce the release of bacteria from biofilms in a newly developed biofilm model on live epithelial cells both in vitro and during in vivo colonization. These dispersed bacteria have distinct phenotypic properties different from those of both biofilm and broth-grown, planktonic bacteria, with the dispersed population showing differential virulence gene expression characteristics resulting in a significantly increased ability to disseminate and cause infection of otherwise sterile sites, such as the middle ear, lungs, and bloodstream. The results offer novel and important insights into the role of interkingdom signaling between microbe and host during biofilm dispersion and transition to acute disease. IMPORTANCE: This report addresses the mechanisms involved in transition from pneumococcal asymptomatic colonization to disease. In this study, we determined that changes in the nasopharyngeal environment result in the release of bacteria from colonizing biofilms with a gene expression and virulence phenotype different not only from that of colonizing biofilm bacteria but also from that of the broth-grown planktonic bacteria commonly used for pathogenesis studies. The work importantly also identifies specific host factors responsible for the release of bacteria and their changed phenotype. We show that these interkingdom signals are recognized by bacteria and are induced by influenza virus infection, which is epidemiologically strongly associated with transition to secondary pneumococcal disease. As virus infection is a common inducer of transition to disease among species occupying the nasopharynx, the results of this study may provide a basis for better understanding of the signals involved in the transition from colonization to disease in the human nasopharynx.

Monocyte- and macrophage-targeted NADPH oxidase mediates antifungal host defense and regulation of acute inflammation in mice.

Chronic granulomatous disease, an inherited disorder of the NADPH oxidase in which phagocytes are defective in the generation of superoxide anion and downstream reactive oxidant species, is characterized by severe bacterial and fungal infections and excessive inflammation. Although NADPH oxidase isoforms exist in several lineages, reactive oxidant generation is greatest in neutrophils, where NADPH oxidase has been deemed vital for pathogen killing. In contrast, the function and importance of NADPH oxidase in macrophages are less clear. Therefore, we evaluated susceptibility to pulmonary aspergillosis in globally NADPH oxidase-deficient mice versus transgenic mice with monocyte/macrophage-targeted NADPH oxidase activity. We found that the lethal inoculum was >100-fold greater in transgenic versus globally NADPH oxidase-deficient mice. Consistent with these in vivo results, NADPH oxidase in mouse alveolar macrophages limited germination of phagocytosed Aspergillus fumigatus spores. Finally, globally NADPH oxidase-deficient mice developed exuberant neutrophilic lung inflammation and proinflammatory cytokine responses to zymosan, a fungal cell wall-derived product composed principally of particulate ß-glucans, whereas inflammation in transgenic and wild-type mice was mild and transient. Taken together, our studies identify a central role for monocyte/macrophage NADPH oxidase in controlling fungal infection and in limiting acute lung inflammation.

Role of pulmonary artery reactivity and nitric oxide in injury and inflammation following lung contusion.

The mechanisms contributing to hypoxia in lung contusion (LC) remain unclear and not temporally associated with the peak onset of acute inflammation. We investigated the role of oxidative stress in alteration of pulmonary arterial (PA) reactivity following LC. In addition, the role of antioxidants in reversing this process was examined. PaO2 and PA reactivity were measured in rats subjected to bilateral LC. Rings were pretreated with a nitric oxide synthase (NOS) inhibitor, L-nitro arginine (10(-3) M), or PEG-superoxide dismutase (SOD) and PEG-catalase (CAT), or both (L-nitro arginine + SOD/CAT). Rings were constricted with norepinephrine and relaxed with an NOS agonist (A23187) or NO donor (SNAP [S-nitrosyl amino penicillamine]). Immunochemical and mass spectrometric quantification for nitrotyrosine was performed. Rats were hypoxemic at 4 h after contusion compared with controls, but recovered by 24 h (PaO(2)/FIO(2) ratio: baseline, 443 ± 28; 4 h, 288 ± 46; and 24 h, 417 ± 23). Pulmonary arterial constriction to NOS inhibition and relaxation to A23187 were impaired 4 h after LC. Pulmonary arterial relaxation to SNAP was decreased at 4 and 24 h after LC. These alterations in PA reactivity were reversed by SOD/CAT pretreatment. SOD1 and 2 mRNA were upregulated, and soluble guanylyl cyclase mRNA was downregulated 24 h after LC. Immunohistochemistry and mass spectrometry revealed that levels of 3-nitrotyrosine were increased markedly at 4 h following LC consistent with superoxide generation and formation of peroxynitrite. Collectively, these data suggest that consumption of NO due to excess superoxide resulting in peroxynitrite formation leads to diminished vascular reactivity following LC.

NADPH oxidase and Nrf2 regulate gastric aspiration-induced inflammation and acute lung injury.

Recruitment of neutrophils and release of reactive oxygen species are considered to be major pathogenic components driving acute lung injury (ALI). However, NADPH oxidase, the major source of reactive oxygen species in activated phagocytes, can paradoxically limit inflammation and injury. We hypothesized that NADPH oxidase protects against ALI by limiting neutrophilic inflammation and activating Nrf2, a transcriptional factor that induces antioxidative and cytoprotective pathways. Our objective was to delineate the roles of NADPH oxidase and Nrf2 in modulating acute lung inflammation and injury in clinically relevant models of acute gastric aspiration injury, a major cause of ALI. Acid aspiration caused increased ALI (as assessed by bronchoalveolar lavage fluid albumin concentration) in both NADPH oxidase-deficient mice and Nrf2(-/-) mice compared with wild-type mice. NADPH oxidase reduced airway neutrophil accumulation, but Nrf2 decreased ALI without affecting neutrophil recovery. Acid injury resulted in a 120-fold increase in mitochondrial DNA, a proinflammatory and injurious product of cellular necrosis, in cell-free bronchoalveolar lavage fluid. Pharmacologic activation of Nrf2 by the triterpenoid 1-[2-cyano-3-,12-dioxooleana-1,9 (11)-dien-28-oyl]imidazole limited aspiration-induced ALI in wild-type mice and reduced endothelial cell injury caused by mitochondrial extract-primed human neutrophils, leading to the conclusion that NADPH oxidase and Nrf2 have coordinated, but distinct, functions in modulating inflammation and injury. These results also point to Nrf2 as a therapeutic target to limit ALI by attenuating neutrophil-induced cellular injury.

Effect of high advanced glycation end-product diet on pulmonary inflammatory response and pulmonary function following gastric aspiration.

It is not clear why some patients with aspiration advance to acute lung injury or acute respiratory distress syndrome, whereas others do not. The Western diet is high in advanced glycation end-products (AGEs), which have been found to be proinflammatory. We hypothesize that dietary AGEs exaggerate the pulmonary inflammatory response following gastric aspiration. CD-1 mice were randomized to receive either a low-AGE (LAGE) or a high-AGE (HAGE) diet for 4 weeks. Five hours after intratracheal instillation of acidified small gastric particles, pulmonary function was determined. Polymorphonuclear neutrophil counts, albumin, cytokine/chemokine, and tumor necrosis factor soluble receptor II concentrations in the bronchoalveolar lavage and lung myeloperoxidase activity were measured. Compared with LAGE-fed animals, those fed a HAGE diet had increased lung tissue resistance (P = 0.017), bronchoalveolar lavage albumin concentration (P < 0.05), pulmonary polymorphonuclear neutrophil counts (P = 0.0045), and lung myeloperoxidase activity (P = 0.002) following aspiration. In addition, the plasma levels of tumor necrosis factor soluble receptor II were significantly elevated (P < 0.05), whereas paradoxically levels of keratinocyte chemoattractant and monocyte chemoattractant protein 1 were decreased in mice with HAGE diet. In conclusion, a diet high in AGEs exacerbates acute lung injury following gastric aspiration as evidenced by increases in neutrophil infiltration, airway albumin leakage, and decreased pulmonary compliance. This is the first evidence implicating exacerbation of acute inflammatory lung injury by dietary AGEs. Targeting AGEs in the circulatory system may offer a therapeutic strategy for limiting lung injury following gastric aspiration.

Increasing TNF levels solely in the rat hippocampus produces persistent pain-like symptoms.

The manifestation of chronic, neuropathic pain includes elevated levels of the cytokine tumor necrosis factor-alpha (TNF). Previously, we have shown that the hippocampus, an area of the brain most notable for its role in learning and memory formation, plays a fundamental role in pain sensation. Using an animal model of peripheral neuropathic pain, we have demonstrated that intracerebroventricular infusion of a TNF antibody adjacent to the hippocampus completely alleviated pain. Furthermore, intracerebroventricular infusion of rTNF adjacent to the hippocampus induced pain behavior in naïve animals similar to that expressed during a model of neuropathic pain. These data support our premise that enhanced production of hippocampal-TNF is integral in pain sensation. In the present study, TNF gene expression was induced exclusively in the hippocampus, eliciting increased local bioactive TNF levels, and animals were assessed for pain behaviors. Male Sprague-Dawley rats received stereotaxic injection of gold nanorod (GNR)-complexed cDNA (control or TNF) plasmids (nanoplasmidexes), and pain responses (i.e., thermal hyperalgesia and mechanical allodynia) were measured. Animals receiving hippocampal microinjection of TNF nanoplasmidexes developed thermal hyperalgesia bilaterally. Sensitivity to mechanical stimulation also developed bilaterally in the rat hind paws. In support of these behavioral findings, immunoreactive staining for TNF, bioactive levels of TNF, and levels of TNF mRNA per polymerase chain reaction analysis were assessed in several brain regions and found to be increased only in the hippocampus. These findings indicate that the specific elevation of TNF in the hippocampus is not a consequence of pain, but in fact induces these behaviors/symptoms.

The receptor for advanced glycation end products and acute lung injury/acute respiratory distress syndrome.

The receptor for advanced glycation end products (RAGE) is a pattern-recognition receptor and evolutionary member of the immunoglobulin superfamily that is involved in the host response to infection, injury, and inflammation. It exists in two forms: membrane-bound and soluble forms (sRAGE). RAGE recognizes a variety of ligands and, via a receptor-driven signaling cascade, activates the transcription factor NF-κB, leading to the expression of proinflammatory cytokines. The soluble form, sRAGE, is a decoy receptor and competitively inhibits membrane RAGE activation. RAGE is constitutively expressed abundantly in the lung under basal conditions. This expression is enhanced during inflammatory states such as with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). This review summarizes the characteristics of RAGE, RAGE isoforms, RAGE ligands, and signaling pathways in the pathogenesis of ALI and ARDS. Additionally, the review explores the potential of RAGE as an important therapeutic target in ALI/ARDS.