Effects of reactive oxygen species scavenger on the protective action of 100% oxygen treatment against sterile inflammation in mice

Ameliorative Effects of some Natural Antioxidants against Blood and Cardiovascular Toxicity of Oral Subchronic Exposure to Silicon Dioxide, Aluminum Oxide, or Zinc Oxide Nanoparticles in Wistar Rats

The present study determines the possible protective role of fig fruit extract with olive oil and date palm fruit extract (FOD) in decreasing the oral subchronic blood and cardiovascular toxicity of SiO₂NPs, Al₂O₃NPs, or ZnONPs. The present study used 80 male Wistar rats (8 groups, n = 10) distributed according to the treatment. The FOD treatments were used at their recommended antioxidant doses. All nanoparticles (NPs) were given orally and daily at doses of 100 mg/kg for 75 days. The oral administration of different NPs alone led to dramatic, oxidative stress, inflammatory markers, blood coagulation, endothelial dysfunction markers, myocardial enzymes, hematological parameters, lipid profile, and histopathological features compared with the control group. The FOD-NP-treated groups recorded significantly ameliorated blood and cardiovascular toxicity hazards compared to the groups administered with the NPs alone. In conclusion, the administration of FOD provides considerable chemopreventive and ameliorative effects against NP toxicity.

Curcumin Alleviates Dextran Sulfate Sodium-induced Colitis in Mice Through Regulating Gut Microbiota

SCOPE

Curcumin is a natural polyphenol compound with multiple pharmacologic activities. The present study aims to explore the potential therapeutic properties of curcumin on intestinal inflammatory diseases, including its anti-inflammatory, anti-oxidant, and anti-apoptotic properties, as well as their associations with altered intestinal microbiome.

METHODS AND RESULTS

DSS, i.e., Dextran Sulfate Sodium, (3%) was administered to C57BL/6J mice in the drinking water daily for 6 days in DSS and curcumin groups. Then mice in curcumin groups were orally administered with 50 or 150 mg/kg curcumin for 7 days. On day 13, mice were sacrificed. Results showed that oral administration with curcumin relieved macroscopic pathological manifestations, e.g. colon length and histological change. Moreover, it enhanced intestinal barrier via increasing expression of tight junction proteins, e.g. occludin, ZO-1, claudin-3; alleviated DSS-induced intestinal apoptosis via suppressing caspase-3 pathway; mitigated intestinal inflammation via inhibiting the MAPK/NFκB/STAT3 pathway. We also noticed that curcumin is beneficial for modulating abundance of some specific bacteria, including Akkermansia, Coprococcus, Roseburia, and Turicibacter, as well as families such as F16, Enterococcaceae, and Aerococcaceae. Most of the altered bacteria by curcumin are highly correlated with colitis-associated parameters.

CONCLUSION

curcumin shows therapeutic potential against colitis. It may be served as alternative medicine or adjuvant therapy in the treatment of colitis. This article is protected by copyright. All rights reserved.

Ginger and 6-gingerol prevent lipopolysaccharide-induced intestinal barrier damage and liver injury in mice

BACKGROUND

Inflammation-related diseases present a significant public health problem. Ginger is a flavoring spice and medicinal herb with anti-inflammatory activity. This study investigated the preventive effects of ginger extract (GE) and its main bioactive component, 6-gingerol (6G), on lipopolysaccharide (LPS)-induced intestinal barrier dysfunction and liver injury in mice.

RESULTS

GE and 6G were orally administered to mice for seven consecutive days before LPS administration. After 24 h, the mice were sacrificed. GE and 6G were found to significantly reverse LPS-induced inflammation in the mouse ileum by modifying the NF-κB pathway. They also alleviated apoptosis in the ileum by downregulating Bax and cytochrome c gene expression and by inhibiting the caspase-3 pathway. Through the aforementioned mechanisms, GE and 6G restored the intestinal barrier by increasing ZO-1 and claudin-1 protein expressions. Gut-derived LPS induced inflammation and apoptosis in the liver; these effects were markedly reversed through GE and 6G treatment. 6G was the most abundant component in GE, as evidenced through liquid chromatography-mass spectrometry, and accounted for >50% of total gingerols and shogaols in GE.

CONCLUSION

The current results support the use of GE and 6G as dietary supplements to protect against gut-derived endotoxemia-associated inflammatory response and disorders. © 2021 Society of Chemical Industry.

Intelligent Tumor Microenvironment-Activated Multifunctional Nanoplatform Coupled with Turn-on and Always-on Fluorescence Probes for Imaging-Guided Cancer Treatment

Intrinsic tumor microenvironment (TME)-related therapeutic resistance and nontumor-specific imaging have limited the application of imaging-guided cancer therapy. Herein, a TME-responsive MnO₂-based nanoplatform coupled with turn-on and always-on fluorescence probes was designed through a facile biomineralization method for imaging-guided photodynamic/chemodynamic/photothermal therapy (PDT/CDT/PTT). After the tumor-targeting delivery of the AuNCs@MnO₂-ICG@AS1411 (AMIT) nanoplatform via aptamer AS1411, the TME-responsive dissociation of MnO₂ generated sufficient O₂ and Mn²⁺ with the consumption of GSH for improving PDT efficacy and Fenton-like reaction-mediated CDT. Simultaneously, the released small-sized ICG and AuNCs facilitated PDT and PTT efficacy via the deep tumor penetration. Moreover, the turn-on fluorescence of AuNCs revealed the real-time TME-responsive MnO₂ degradation process, and the always-on ICG fluorescence enabled the in situ monitoring of the payload distribution in vitro and in vivo. The AMIT NPs also provided magnetic resonance and thermal imaging guidance for the enhanced PDT, CDT, and PTT. Therefore, this all-in-one nanosystem provides a simple and versatile strategy for multiple imaging-guided theranostic applications.

ROS Plays a Role in the Neonatal Rat Intestinal Barrier Damages Induced by Hyperoxia

BACKGROUND

Hyperoxia treats a subset of critical neonatal illnesses but induces intestinal damage in neonatal pups. In this process, the intestinal flora and mucosal epithelium might be altered by hyperoxia. So the changes of the intestinal flora and mucosal epithelium were studied.

METHODS

Neonatal rats were randomized into the model group that was exposed to hyperoxia and the control group that was maintained under normoxic conditions; then, intestinal lavage fluid and intestinal tissues were harvested. ELISA was used to detect D-lactic acid (D-LA), endotoxin (ET), diamine oxidase (DAO), intestinal fatty acid binding protein (i-FABP), liver-type fatty acid binding protein (L-FABP) and cytokines in the intestinal lavage of neonatal rats during hyperoxia. The intestinal zonula occluden-1 (ZO-1), occlusion protein (Occludin), and closure protein-4 (Claudin-4) of neonatal pups were detected by immunohistochemistry, western blotting, and real-time Polymerase chain reaction (RT-PCR) during hyperoxia. NCM460 cell survival rates were assayed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) during hyperoxia and administration of N-acetyl-L-cysteine (NAC). The expression levels of ZO-1, Occludin, and Claudin-4 in NCM460 cells were detected by immunohistochemistry, western blotting, and RT-PCR during hyperoxia and NAC.

RESULTS

D-LA, ET, L-FABP, i-FABP, DAO, TNF-α, IL-10, and IFN-γ were significantly increased by hyperoxia, while ZO-1, Occludin, and Claudin-4 were clearly decreased in the hyperoxia group compared with the control group. NAC promoted cell survival, which was inhibited by hyperoxia. The cellular expression levels of ZO-1, Occludin, and Claudin-4, which were lowered by hyperoxia, were increased by NAC.

CONCLUSION

Hyperoxia causes injury of the intestinal mucosa, and ROS plays a role in this intestinal damage during hyperoxia.

Systemic Effects Induced by Hyperoxia in a Preclinical Model of Intra-abdominal Sepsis

Supplemental oxygen is a supportive treatment in patients with sepsis to balance tissue oxygen delivery and demand in the tissues. However, hyperoxia may induce some pathological effects. We sought to assess organ damage associated with hyperoxia and its correlation with the production of reactive oxygen species (ROS) in a preclinical model of intra-abdominal sepsis. For this purpose, sepsis was induced in male, Sprague-Dawley rats by cecal ligation and puncture (CLP). We randomly assigned experimental animals to three groups: control (healthy animals), septic (CLP), and sham-septic (surgical intervention without CLP). At 18 h after CLP, septic (n = 39), sham-septic (n = 16), and healthy (n = 24) animals were placed within a sealed Plexiglas cage and randomly distributed into four groups for continuous treatment with 21%, 40%, 60%, or 100% oxygen for 24 h. At the end of the experimental period, we evaluated serum levels of cytokines, organ damage biomarkers, histological examination of brain and lung tissue, and ROS production in each surviving animal. We found that high oxygen concentrations increased IL-6 and biomarkers of organ damage levels in septic animals, although no relevant histopathological lung or brain damage was observed. Healthy rats had an increase in IL-6 and aspartate aminotransferase at high oxygen concentration. IL-6 levels, but not ROS levels, are correlated with markers of organ damage. In our study, the use of high oxygen concentrations in a clinically relevant model of intra-abdominal sepsis was associated with enhanced inflammation and organ damage. These findings were unrelated to ROS release into circulation. Hyperoxia could exacerbate sepsis-induced inflammation, and it could be by itself detrimental. Our study highlights the need of developing safer thresholds for oxygen therapy.

Hepato-renal toxicity of oral sub-chronic exposure to aluminum oxide and/or zinc oxide nanoparticles in rats

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Oral sub-chronic exposure to Aluminum oxide or zinc oxide nanoparticles has hepato-renal toxicity.

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The toxicities of Aluminum oxide and/or zinc oxide NPs mediated through different correlated pathways.

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The pathways including; epigenetic changes, impaired antioxidant systems, induced oxidative stress and disturbed cytokine production.

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Exaggerated hepatic and renal toxicities of combined exposure to both NPs.

Aluminum oxide nanoparticles (Al₂O₃NPs) and zinc oxide nanoparticles (ZnONPs) have been involved in many industries and they are extensively abundant in many aspects of human life. Consequently, concerns have been raised about their potentially harmful effects. However the toxicities of Al₂O₃NPs and ZnONPs are well documented, the effect of co-exposure to both nanoparticles remains strictly obscure. Therefore, the present study was undertaken to address this issue. Four groups of male Wistar rats (10 rats each) were used; control, Al₂O₃NPs treated, ZnONPs treated and Co-treated groups. Rats were orally administered their respective treatment daily for 75 days. The effects of each nanoparticle alone or in combination were assessed at different levels including; hepatic and renal function, structure, and redox status, nuclear DNA fragmentation, hepatic expression of mitochondrial transcription factor A (mtTFA) gene and peroxisome proliferator-activated receptor gamma-coactivator 1α (PGC-1α), systemic inflammation, and hematologic parameters. The results confirmed the hepatorenal toxicities of each nanoparticle used at the level of all parameters with suppression of the hepatic expression of mtTFA and PGC-1α. The co-exposure to both nanoparticles results in synergistic effects. From these results, we can conclude that co-exposure to aluminum oxide nanoparticles and zinc oxide nanoparticles results in more pronounced hepatorenal toxicities and systemic inflammation.

Effects of Antioxidants in Reducing Accumulation of Fat in Hepatocyte

The progress of the hepatic steatosis (HS), a clinicopathological status, is influenced by cellular oxidative stress, lipogenesis, fatty acid (FA) oxidation, and inflammatory responses. Because antioxidants are gaining attention as potent preventive agents for HS, we aimed to investigate anti-lipogenic effects of the antioxidants vitamin C (VC), N-acetylcysteine (NAC), and astaxanthin (ATX) using hepatocytes. For this, we established an in vitro model using 1 mM oleic acid (OA) and human liver hepatocellular carcinoma (HepG2) cells; 10 μM antioxidants were evaluated for their ability to reduce fat accumulation in hepatocytes. Our results showed that all three antioxidants were effective to reduce fat accumulation for the molecular targets such as reduction in lipid droplets, triglyceride (TG) concentration, reactive oxygen species (ROS) production, and cell apoptosis, as well as in gene expressions of endoplasmic reticulum (ER) stress-related effectors, lipogenesis, and inflammatory cytokines. There were simultaneous increases in diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effect, cell survival, AMPK phosphorylation, NRF2-related gene expression for cellular defense, and FA β-oxidation. However, among these, ATX more effectively inhibited ER stress and lipogenesis at the intracellular level than VC or NAC. Consequently, ATX was also more effective in inhibiting cell death, lipotoxicity, and inflammation. Our result emphasizes that ATX achieved greater lipotoxicity reduction than VC and NAC.

Cascade-amplifying synergistic effects of chemo-photodynamic therapy using ROS-responsive polymeric nanocarriers

The simple integration of chemotherapeutic drugs and photosensitizers (PSs) into the same nanocarriers only achieves a combination of chemo-photodynamic therapy but may not confer synergistic effects. The boosted intracellular release of chemotherapeutic drugs during the photodynamic therapy (PDT) process is necessary to achieve a cascade of amplified synergistic therapeutic effects of chemo-photodynamic therapy. Methods: In this study, we explored an innovative hyperbranched polyphosphate (RHPPE) containing a singlet oxygen (SO)-labile crosslinker to boost drug release during the PDT process. The photosensitizer chlorin e6 (Ce6) and doxorubicin (DOX) were simultaneously loaded into RHPPE nanoparticles (denoted as ^SOHNP_Ce6/DOX). The therapeutic efficacy of ^SOHNP_Ce6/DOX against drug-resistant cancer was evaluated in vitro and in vivo. Results: Under 660-nm light irradiation, ^SOHNP_Ce6/DOX can produce SO, which not only induces PDT against cancer but also cleaves the thioketal linkers to destroy the nanoparticles. Subsequently, boosted DOX release can be achieved, activating a chemotherapy cascade to synergistically destroy the remaining tumor cells after the initial round of PDT. Furthermore, ^SOHNP_Ce6/DOX also efficiently detected the tumor area by photoacoustic/magnetic resonance bimodal imaging. Under the guidance of bimodal imaging, the laser beam was precisely focused on the tumor areas, and subsequently, ^SOHNP_Ce6/DOX realized a cascade of amplified synergistic chemo-photodynamic therapeutic effects. High antitumor efficacy was achieved even in a drug-resistant tumor model. Conclusion: The designed ^SOHNP_Ce6/DOX with great biocompatibility is promising for use as a co-delivery carrier for combined chemo-photodynamic therapy, providing an alternative avenue to achieve a cascade of amplified synergistic effects of chemo-photodynamic therapy for cancer treatment.

Supplemental oxygen therapy does not affect the systemic inflammatory response to acute myocardial infarction

BACKGROUND

Oxygen therapy has been used routinely in normoxemic patients with suspected acute myocardial infarction (AMI) despite limited evidence supporting a beneficial effect. AMI is associated with a systemic inflammation. Here, we hypothesized that the inflammatory response to AMI is potentiated by oxygen therapy.

METHODS

The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) multicentre trial randomized patients with suspected AMI to receive oxygen at 6 L min^-1 for 6-12 h or ambient air. For this prespecified subgroup analysis, we recruited patients with confirmed AMI from two sites for evaluation of inflammatory biomarkers at randomization and 5-7 h later. Ninety-two inflammatory biomarkers were analysed using proximity extension assay technology, to evaluate the effect of oxygen on the systemic inflammatory response to AMI.

RESULTS

Plasma from 144 AMI patients was analysed whereof 76 (53%) were randomized to oxygen and 68 (47%) to air. Eight biomarkers showed a significant increase, whereas 13 were decreased 5-7 h after randomization. The inflammatory response did not differ between the two treatment groups neither did plasma troponin T levels. After adjustment for increase in troponin T over time, age and sex, the release of inflammation-related biomarkers was still similar in the groups.

CONCLUSIONS

In a randomized controlled setting of normoxemic patients with AMI, the use of supplemental oxygen did not have any significant impact on the early release of systemic inflammatory markers.

Dexmedetomidine and Magnesium Sulfate: A Good Combination Treatment for Acute Lung Injury?

Objectives: In this study, we aimed to investigate the therapeutic effects of magnesium sulfate (MgSO₄) and dexmedetomidine (dex) in a model of acute lung injury (ALI). We determined whether concomitant administration decreased the inflammatory effects of hydrochloric acid (HCl)-induced ALI in a synergistic manner. Materials and Methods: In this study, 42 Sprague-Dawley rats were randomized into six groups: Group S (saline), Group SV (saline + mechanical ventilation), Group HCl (HCl), Group Dex (Dex), Group Mag (MgSO₄), and Group DM (Dex + MgSO₄). All groups except Group S were mechanically ventilated prior to HCl-induced ALI. Saline or HCl was administered via tracheostomy. Prior to treatment, HCl was administered to Group HCl, Group Dex, Group Mag, and Group DM to induce ALI. Dex and MgSO₄ were administered intraperitoneally. The rats were monitored for 4 h after treatment to measure oxidative stress parameters in blood, and prolidase enzyme activity. Lung tissue damage were determined via histopathology. Results: A significant increase in heart rate and rapid desaturation was observed in HCl-administered groups. Treatment administration decreased the pulse values. Increased saturation values and decreased oxidative stress indices were observed in groups that were subsequently administered​ Dex and MgSO₄. Serum prolidase activity increased significantly in Group HCl. Severe pathological findings were detected following HCl-induced ALI. Group Mag showed greater improvement in the pathology of HCl-induced ALI than did Group Dex. Administration of both Dex and MgSO₄ did not improve the pathological scores. Conclusions: The antioxidant and anti-inflammatory effects of Dex and MgSO₄ ameliorated the detrimental effects of HCI-induced ALI. However, adverse effects on hemodynamics and lung damage were observed when the two drugs were administered together.

Lactobacillus reuteri ZJ617 maintains intestinal integrity via regulating tight junction, autophagy and apoptosis in mice challenged with lipopolysaccharide

Live probiotics are effective in reducing gut permeability and inflammation. We have previously reported that Lactobacillus reuteri ZJ617 (ZJ617) with high adhesive and Lactobacillus rhamnosus GG (LGG) can ameliorate intestine inflammation induced by lipopolysaccharide (LPS). The present study was aimed at elucidating the roles of ZJ617 and LGG in alleviating the LPS-induced barrier dysfunction of ileum in mice. Six C57BL/6 mice per group were orally inoculated with ZJ617 or LGG for one week (1× 10⁸ CFU/mouse) and intraperitoneally injected with LPS (10 mg/kg body weight) for 24 h. The results demonstrated that pretreatment with ZJ617 and LGG attenuated LPS-induced increase in intestinal permeability. The probiotics supplementation suppressed LPS-induced oxidative stress. Both ZJ617 and LGG strongly reversed the decline of occludin and claudin-3 expression induced by LPS challenge. ZJ617 relieved LPS-induced apoptosis by decreasing caspase-3 activity. Noticeably, ratio of microtubule-associated light chain 3 (LC3)-II/LC3-I and LC3 activity were elevated by LPS stimulation, whereas such increases were obviously attenuated by both of the probiotics treatment. Moreover, phosphorylated mammalian target of rapamycin (p-mTOR) was significantly inhibited by LPS, whereas complementation of ZJ617 and LGG markedly increased the expression of p-mTOR. Collectively, our results indicated that ZJ617 could protect LPS-induced intestinal barrier dysfunction via enhancing antioxidant activities and tight junction and attenuating apoptosis and autophagy via mTOR signaling pathway. These findings could serve as systematic mechanisms through which probiotics promote and maintain gut homeostasis.

Effects of Hyperoxia and Mild Therapeutic Hypothermia During Resuscitation From Porcine Hemorrhagic Shock

OBJECTIVE

Hemorrhagic shock-induced tissue hypoxia induces hyperinflammation, ultimately causing multiple organ failure. Hyperoxia and hypothermia can attenuate tissue hypoxia due to increased oxygen supply and decreased demand, respectively. Therefore, we tested the hypothesis whether mild therapeutic hypothermia and hyperoxia would attenuate postshock hyperinflammation and thereby organ dysfunction.

DESIGN

Prospective, controlled, randomized study.

SETTING

University animal research laboratory.

SUBJECTS

Thirty-six Bretoncelles-Meishan-Willebrand pigs of either gender.

INTERVENTIONS

After 4 hours of hemorrhagic shock (removal of 30% of the blood volume, subsequent titration of mean arterial pressure at 35 mm Hg), anesthetized and instrumented pigs were randomly assigned to "control" (standard resuscitation: retransfusion of shed blood, fluid resuscitation, norepinephrine titrated to maintain mean arterial pressure at preshock values, mechanical ventilation titrated to maintain arterial oxygen saturation > 90%), "hyperoxia" (standard resuscitation, but FIO2, 1.0), "hypothermia" (standard resuscitation, but core temperature 34°C), or "combi" (hyperoxia plus hypothermia) (n = 9 each).

MEASUREMENTS AND MAIN RESULTS

Before, immediately at the end of and 12 and 22 hours after hemorrhagic shock, we measured hemodynamics, blood gases, acid-base status, metabolism, organ function, cytokine production, and coagulation. Postmortem kidney specimen were taken for histological evaluation, immunohistochemistry (nitrotyrosine, cystathionine γ-lyase, activated caspase-3, and extravascular albumin), and immunoblotting (nuclear factor-κB, hypoxia-inducible factor-1α, heme oxygenase-1, inducible nitric oxide synthase, B-cell lymphoma-extra large, and protein expression of the endogenous nuclear factor-κB inhibitor). Although hyperoxia alone attenuated the postshock hyperinflammation and thereby tended to improve visceral organ function, hypothermia and combi treatment had no beneficial effect.

CONCLUSIONS

During resuscitation from near-lethal hemorrhagic shock, hyperoxia attenuated hyperinflammation, and thereby showed a favorable trend toward improved organ function. The lacking efficacy of hypothermia was most likely due to more pronounced barrier dysfunction with vascular leakage-induced circulatory failure.

Combination therapy of molecular hydrogen and hyperoxia improves survival rate and organ damage in a zymosan-induced generalized inflammation model

Multiple organ dysfunction syndrome (MODS) is a leading cause of mortality in critically ill patients. Hyperoxia treatment may be beneficial to critically ill patients. However, the clinical use of hyperoxia is hindered as it may exacerbate organ injury by increasing reactive oxygen species (ROS). Hydrogen gas (H₂) exerts a therapeutic antioxidative effect by selectively reducing ROS. Combination therapy of H₂ and hyperoxia has previously been shown to significantly improve survival rate and organ damage extent in mice with polymicrobial sepsis. The aim of the present study was to investigate whether combination therapy with H₂ and hyperoxia could improve survival rate and organ damage in a zymosan (ZY)-induced generalized inflammation model. The results showed that the inhalation of H₂ (2%) or hyperoxia (98%) alone improved the 14-day survival rate of ZY-challenged mice from 20 to 70 or 60%, respectively. However, combination therapy with H₂ and hyperoxia could increase the 14-day survival rate of ZY-challenged mice to 100%. Furthermore, ZY-challenged mice showed significant multiple organ damage characterized by increased serum levels of aspartate transaminase, alanine transaminase, blood urea nitrogen and creatinine, as well as lung, liver and kidney histopathological scores at 24 h after ZY injection. These symptoms where attenuated by H₂ or hyperoxia alone; however, combination therapy with H₂ and hyperoxia had a more marked beneficial effect against lung, liver and kidney damage in ZY-challenged mice. In addition, the beneficial effects of this combination therapy on ZY-induced organ damage were associated with decreased serum levels of the oxidative product 8-iso-prostaglandin F2α, increased activity of superoxide dismutase and reduced levels of the proinflammatory cytokines high-mobility group box 1 and tumor necrosis factor-α. In conclusion, combination therapy with H₂ and hyperoxia provides enhanced therapeutic efficacy against multiple organ damage in a ZY-induced generalized inflammation model, suggesting the potential applicability of H₂ and hyperoxia in the therapy of conditions associated with inflammation-related MODS.

Combined effects of aging and inflammation on renin-angiotensin system mediate mitochondrial dysfunction and phenotypic changes in cardiomyopathies

Although the effects of aging and inflammation on the health of the cardiac muscle are well documented, the combined effects of aging and chronic inflammation on cardiac muscle are largely unknown. The renin-angiotensin system (RAS) has been linked independently to both aging and inflammation, but is understudied in the context of their collective effect. Thus, we investigated localized cardiac angiotensin II type I and type II receptors (AT₁R, AT₂R), downstream effectors, and phenotypic outcomes using mouse models of the combination of aging and inflammation and compared it to a model of aging and a model of inflammation. We show molecular distinction in the combined effect of aging and inflammation as compared to each independently. The combination maintained an increased AT₁R:AT₂R and expression of Nox2 and exhibited the lowest activity of antioxidants. Despite signaling pathway differences, the combined effect shared phenotypic similarities with aging including oxidative damage, fibrosis, and hypertrophy. These phenotypic similarities have dubbed inflammatory conditions as premature aging, but they are, in fact, molecularly distinct. Moreover, treatment with an AT₁R blocker, losartan, selectively reversed the signaling changes and ameliorated adverse phenotypic effects in the combination of aging and inflammation as well as each independently.

Cardiovascular effects of hyperoxia during and after cardiac surgery

During and after cardiac surgery with cardiopulmonary bypass, high concentrations of oxygen are routinely administered, with the intention of preventing cellular hypoxia. We systematically reviewed the literature addressing the effects of arterial hyperoxia. Extensive evidence from pre-clinical experiments and clinical studies in other patient groups suggests predominant harm, caused by oxidative stress, vasoconstriction, perfusion heterogeneity and myocardial injury. Whether these alterations are temporary and benign, or actually affect clinical outcome, remains to be demonstrated. In nine clinical cardiac surgical studies in low-risk patients, higher oxygen targets tended to compromise cardiovascular function, but did not affect clinical outcome. No data about potential beneficial effects of hyperoxia, such as reduction of gas micro-emboli or post-cardiac surgery infections, were reported. Current evidence is insufficient to specify optimal oxygen targets. Nevertheless, the safety of supraphysiological oxygen suppletion is unproven. Randomised studies with a variety of oxygen targets and inclusion of high-risk patients are needed to identify optimal oxygen targets during and after cardiac surgery.

Bench-to-bedside review: the effects of hyperoxia during critical illness

Oxygen administration is uniformly used in emergency and intensive care medicine and has life-saving potential in critical conditions. However, excessive oxygenation also has deleterious properties in various pathophysiological processes and consequently both clinical and translational studies investigating hyperoxia during critical illness have gained increasing interest. Reactive oxygen species are notorious by-products of hyperoxia and play a pivotal role in cell signaling pathways. The effects are diverse, but when the homeostatic balance is disturbed, reactive oxygen species typically conserve a vicious cycle of tissue injury, characterized by cell damage, cell death, and inflammation. The most prominent symptoms in the abundantly exposed lungs include tracheobronchitis, pulmonary edema, and respiratory failure. In addition, absorptive atelectasis results as a physiological phenomenon with increasing levels of inspiratory oxygen. Hyperoxia-induced vasoconstriction can be beneficial during vasodilatory shock, but hemodynamic changes may also impose risk when organ perfusion is impaired. In this context, oxygen may be recognized as a multifaceted agent, a modifiable risk factor, and a feasible target for intervention. Although most clinical outcomes are still under extensive investigation, careful titration of oxygen supply is warranted in order to secure adequate tissue oxygenation while preventing hyperoxic harm.

Multiple system organ response induced by hyperoxia in a clinically relevant animal model of sepsis

Oxygen therapy is currently used as a supportive treatment in septic patients to improve tissue oxygenation. However, oxygen can exert deleterious effects on the inflammatory response triggered by infection. We postulated that the use of high oxygen concentrations may be partially responsible for the worsening of sepsis-induced multiple system organ dysfunction in an experimental clinically relevant model of sepsis. We used Sprague-Dawley rats. Sepsis was induced by cecal ligation and puncture. Sham-septic controls (n = 16) and septic animals (n = 32) were randomly assigned to four groups and placed in a sealed Plexiglas cage continuously flushed for 24 h with medical air (group 1), 40% oxygen (group 2), 60% oxygen (group 3), or 100% oxygen (group 4). We examined the effects of these oxygen concentrations on the spread of infection in blood, urine, peritoneal fluid, bronchoalveolar lavage, and meninges; serum levels of inflammatory biomarkers and reactive oxygen species production; and hematological parameters in all experimental groups. In cecal ligation and puncture animals, the use of higher oxygen concentrations was associated with a greater number of infected biological samples (P < 0.0001), higher serum levels of interleukin-6 (P < 0.0001), interleukin-10 (P = 0.033), and tumor necrosis factor-α (P = 0.034), a marked decrease in platelet counts (P < 0.001), and a marked elevation of reactive oxygen species serum levels (P = 0.0006) after 24 h of oxygen exposure. Oxygen therapy greatly influences the progression and clinical manifestation of multiple system organ dysfunction in experimental sepsis. If these results are extrapolated to humans, they suggest that oxygen therapy should be carefully managed in septic patients to minimize its deleterious effects.

Toll-like receptor 6 mediated inflammatory and functional responses of zinc oxide nanoparticles primed macrophages

Macrophages are among the most sensitive immune cells because of their phagocytic activity and are prone to become dysfunctional or not able to perform properly if nanoparticle load increases. We have previously reported that zinc oxide nanoparticles (ZNPs) induce inflammatory responses in macrophages that contribute to their death. Recognition of ZNPs by pattern recognition receptors such as toll-like receptors (TLRs) might be a factor in the initiation of these responses in macrophages. Therefore, in this study we explored the role played by TLR6 and mitogen-activated protein kinase (MAPKs) pathways in the inflammatory responses of macrophages during ZNPs exposure. ZNPs-activated macrophages showed enhanced expression of activation and maturation markers (CD1d, MHC-II, CD86 and CD71). Among various TLRs screened, TLR6 emerged as the most potent activator for ZNPs-induced inflammatory responses. Downstream signalling proteins myeloid differentiation 88, interleukin-1 receptor associated kinase and tumour necrosis factor receptor-associated factor were also enhanced. On inhibiting MAPKs pathways individually, the inflammatory responses such as interleukin-1β, interleukin-6, tumour necrosis factor-α, cyclooxygenase-2 and inducible nitric oxide synthase were suppressed. TLR6 silencing significantly inhibited the pro-inflammatory cytokine levels, reactive nitrogen species generation and inducible nitric oxide synthase expression. Also, inhibition of MAPKs in the absence of TLR6 signalling validated the link between TLR6 and MAPKs in ZNPs-induced inflammatory responses. TLR6 was found to be co-localized with autophagosomes. Macrophages lacking TLR6 inhibited the autophagosome marker protein-microtubule-associated protein1 light chain 3-isoform II formation and phagocytosis. These results demonstrate that inflammatory responses caused by ZNPs-activated macrophages strongly depend on TLR6-mediated MAPK signalling.

H₂O₂ induces delayed hyperexcitability in nucleus tractus solitarii neurons

Hydrogen peroxide (H₂O₂) is a stable reactive oxygen species and potent neuromodulator of cellular and synaptic activity. Centrally, endogenous H₂O₂ is elevated during bouts of hypoxia-reoxygenation, a variety of disease states, and aging. The nucleus tractus solitarii (nTS) is the central termination site of visceral afferents for homeostatic reflexes and contributes to reflex alterations during these conditions. We determined the extent to which H₂O₂ modulates synaptic and membrane properties in nTS neurons in rat brainstem slices. Stimulation of the tractus solitarii (which contains the sensory afferent fibers) evoked synaptic currents that were not altered by 10-500 μM H₂O₂. However, 500 μM H₂O₂ modulated several intrinsic membrane properties of nTS neurons, including a decrease in input resistance (R(i)), hyperpolarization of resting membrane potential (RMP) and action potential (AP) threshold (THR), and an initial reduction in AP discharge to depolarizing current. H₂O₂ increased conductance of barium-sensitive potassium currents, and block of these currents ablated H₂O₂-induced changes in RMP, Ri and AP discharge. Following washout of H₂O₂ AP discharge was enhanced due to depolarization of RMP and a partially maintained hyperpolarization of THR. Hyperexcitability persisted with repeated H₂O₂ exposure. H₂O₂ effects on RMP and THR were ablated by intracellular administration of the antioxidant catalase, which was immunohistochemically identified in neurons throughout the nTS. Thus, H₂O₂ initially reduces excitability of nTS neurons that is followed by sustained hyperexcitability, which may play a profound role in cardiorespiratory reflexes.

Mechanism of uptake of ZnO nanoparticles and inflammatory responses in macrophages require PI3K mediated MAPKs signaling

The inflammatory responses after exposure to zinc oxide nanoparticles (ZNPs) are known, however, the molecular mechanisms and direct consequences of particle uptake are still unclear. Dose and time-dependent increase in the uptake of ZNPs by macrophages has been observed by flow cytometry. Macrophages treated with ZNPs showed a significantly enhanced phagocytic activity. Inhibition of different internalization receptors caused a reduction in uptake of ZNPs in macrophages. The strongest inhibition in internalization was observed by blocking clathrin, caveolae and scavenger receptor mediated endocytic pathways. However, FcR and complement receptor-mediated phagocytic pathways also contributed significantly to control. Further, exposure of primary macrophages to ZNPs (2.5 μg/ml) caused (i) significant enhancement of Ras, PI3K, (ii) enhanced phosphorylation and subsequent activation of its downstream signaling pathways via ERK1/2, p38 and JNK MAPKs (iii) overexpression of c-Jun, c-Fos and NF-κB. Our results demonstrate that ZNPs induce the generation of reactive nitrogen species and overexpression of Cox-2, iNOS, pro-inflammatory cytokines (IL-6, IFN-γ, TNF-α, IL-17 and regulatory cytokine IL-10) and MAPKs which were found to be inhibited after blocking internalization of ZNPs through caveolae receptor pathway. These results indicate that ZNPs are internalized through caveolae pathway and the inflammatory responses involve PI3K mediated MAPKs signaling cascade.

β2-adrenergic receptor antagonist butoxamine partly abolishes the protection of 100% oxygen treatment against zymosan-induced generalized inflammation in mice

We have demonstrated that 100% oxygen inhalation is beneficial to zymosan-induced generalized inflammation, and reactive oxygen species may be involved in the protection of oxygen treatment. Other investigators suggest that reactive oxygen species may modulate the sympathetic nervous system activity and β2-adrenergic receptor (β2AR)-mediated pathway. Moreover, studies have demonstrated that β2AR agonists are beneficial to sepsis. Therefore, we assessed the effects of β2AR antagonist butoxamine on the protection of oxygen treatment against zymosan-induced generalized inflammation in mice. Mice were given oxygen treatment by exposure to 100% oxygen for 3 h starting at 4 and 12 h after zymosan injection, respectively. In the mortality study, survival was monitored for 7 days after zymosan injection in mice. At 24 h after zymosan injection, mice were killed, and blood sample and organs were harvested for analysis. We observed that 100% oxygen treatment prevented the abnormal changes in organ histopathology, lactate dehydrogenase and C-reactive protein in serum, inflammatory cytokines in serum and tissue, and arterial blood gas analysis and improved the survival rate in zymosan-challenged mice. We found that pretreatment with β2AR antagonist butoxamine partly abolished the protection of 100% oxygen inhalation. We also showed that zymosan induced the increase in serum 3'-5'-cyclic adenosine monophosphate (cAMP) and the decrease in tissue cAMP. However, oxygen treatment increased the cAMP levels in both serum and tissue, which were partly abolished by pretreatment with butoxamine. Thus, 100% oxygen inhalation may protect against zymosan-induced generalized inflammation in mice partly through activation of β2AR pathway and subsequently enhance cAMP levels in both serum and tissue.

Activation of cholinergic anti-inflammatory pathway contributes to the protective effects of 100% oxygen inhalation on zymosan-induced generalized inflammation in mice

BACKGROUND

The 100% oxygen inhalation has been demonstrated to have a protective effect on mice with zymosan-induced generalized inflammation. However, the underlying mechanism is largely unknown. The present study was designed to explore the role of the cholinergic anti-inflammatory pathway in this animal model.

METHODS

Oxygen inhalation was given to mice at 4 and 12 h after zymosan injection. One group of mice underwent vagotomy 7 d before zymosan injection. The other two groups of mice either received nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine, or α7 nicotinic acetylcholine receptor (α7nAChR) antagonist methyllycaconitine 30 min before oxygen was given.

RESULTS

The 100% oxygen treatment significantly decreased the serum level of TNF-α and increased the serum level of IL-10. The pathologic changes of the heart, lung, liver, and kidney were attenuated, as well as the dysfunction of liver and kidney. The 7-d survival rate of zymosan-challenged mice was also improved. Conversely, all these protective effects caused by pure oxygen treatment were abolished in those animals that received anti-cholinergic treatments.

CONCLUSIONS

The cholinergic anti-inflammatory pathway may be involved in the 100% oxygen protective mechanism against zymosan-induced generalized inflammation in mice.

Hydrogen gas improves survival rate and organ damage in zymosan-induced generalized inflammation model

Sepsis/multiple organ dysfunction syndrome is the leading cause of death in critically ill patients. Recently, it has been suggested that hydrogen gas (H2) exerts a therapeutic antioxidant activity by selectively reducing hydroxyl radical (•OH, the most cytotoxic reactive oxygen species). We have found that H2 inhalation significantly improved the survival rate and organ damage of septic mice with moderate or severe cecal ligation and puncture. In the present study, we investigated the effects of 2% H2 treatment on survival rate and organ damage in zymosan (ZY)-induced generalized inflammation model. Here, we found that 2% H2 inhalation for 60 min starting at 1 and 6 h after ZY injection, respectively, significantly improved the 14-day survival rate of ZY-challenged mice from 10% to 70%. Furthermore, ZY-challenged mice showed significant multiple organ damage characterized by the increase in serum biochemical parameters (aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, and creatinine), as well as lung, liver, and kidney histopathological scores at 24 h after ZY injection, which was significantly attenuated by 2% H2 treatment. In addition, we found that the beneficial effects of H2 treatment on ZY-induced organ damage were associated with the decreased levels of oxidative product, increased activities of antioxidant enzyme, and reduced levels of early and late proinflammatory cytokines in serum and tissues. In conclusion, this study provides evidence that H2 treatment protects against multiple organ damages in ZY-induced generalized inflammation model, suggesting the potential use of H2 as a therapeutic agent in the therapy of conditions associated with inflammation-related multiple organ dysfunction syndrome.

Hyperoxia may be beneficial

The current practice of mechanical ventilation comprises the use of the least inspiratory O2 fraction associated with an arterial O2 tension of 55 to 80 mm Hg or an arterial hemoglobin O2 saturation of 88% to 95%. Early goal-directed therapy for septic shock, however, attempts to balance O2 delivery and demand by optimizing cardiac function and hemoglobin concentration, without making use of hyperoxia. Clearly, it has been well-established for more than a century that long-term exposure to pure O2 results in pulmonary and, under hyperbaric conditions, central nervous O2 toxicity. Nevertheless, several arguments support the use of ventilation with 100% O2 as a supportive measure during the first 12 to 24 hrs of septic shock. In contrast to patients without lung disease undergoing anesthesia, ventilation with 100% O2 does not worsen intrapulmonary shunt under conditions of hyperinflammation, particularly when low tidal volume-high positive end-expiratory pressure ventilation is used. In healthy volunteers and experimental animals, exposure to hyperoxia may cause pulmonary inflammation, enhanced oxidative stress, and tissue apoptosis. This, however, requires long-term exposure or injurious tidal volumes. In contrast, within the timeframe of a perioperative administration, direct O2 toxicity only plays a negligible role. Pure O2 ventilation induces peripheral vasoconstriction and thus may counteract shock-induced hypotension and reduce vasopressor requirements. Furthermore, in experimental animals, a redistribution of cardiac output toward the kidney and the hepato-splanchnic organs was observed. Hyperoxia not only reverses the anesthesia-related impairment of the host defense but also is an antibiotic. In fact, perioperative hyperoxia significantly reduced wound infections, and this effect was directly related to the tissue O2 tension. Therefore, we advocate mechanical ventilation with 100% O2 during the first 12 to 24 hrs of septic shock. However, controlled clinical trials are mandatory to test the safety and efficacy of this approach.