A novel role of exogenous carbon monoxide on protecting cardiac function and improving survival against sepsis via mitochondrial energetic metabolism pathway

The Emerging Role of Exercise in Alzheimer's Disease: Focus on Mitochondrial Function

Alzheimer's disease (AD) is an age-related neurodegenerative disease characterized by memory impairment and cognitive dysfunction, which eventually leads to the disability and mortality of older adults. Although the precise mechanisms by which age promotes the development of AD remains poorly understood, mitochondrial dysfunction plays a central role in the development of AD. Currently, there is no effective treatment for this debilitating disease. It is well accepted that exercise exerts neuroprotective effects by ameliorating mitochondrial dysfunction in the neurons of AD, which involves multiple mechanisms, including mitochondrial dynamics, biogenesis, mitophagy, transport, and signal transduction. In addition, exercise promotes mitochondria communication with other organelles in AD neurons, which should receive more attentions in the future.

Circulating N-lactoyl-amino acids and N-formyl-methionine reflect mitochondrial dysfunction and predict mortality in septic shock

INTRODUCTION

Sepsis is a highly morbid condition characterized by multi-organ dysfunction resulting from dysregulated inflammation in response to acute infection. Mitochondrial dysfunction may contribute to sepsis pathogenesis, but quantifying mitochondrial dysfunction remains challenging.

OBJECTIVE

To assess the extent to which circulating markers of mitochondrial dysfunction are increased in septic shock, and their relationship to severity and mortality.

METHODS

We performed both full-scan and targeted (known markers of genetic mitochondrial disease) metabolomics on plasma to determine markers of mitochondrial dysfunction which distinguish subjects with septic shock (n = 42) from cardiogenic shock without infection (n = 19), bacteremia without sepsis (n = 18), and ambulatory controls (n = 19) - the latter three being conditions in which mitochondrial function, proxied by peripheral oxygen consumption, is presumed intact.

RESULTS

Nine metabolites were significantly increased in septic shock compared to all three comparator groups. This list includes N-formyl-L-methionine (f-Met), a marker of dysregulated mitochondrial protein translation, and N-lactoyl-phenylalanine (lac-Phe), representative of the N-lactoyl-amino acids (lac-AAs), which are elevated in plasma of patients with monogenic mitochondrial disease. Compared to lactate, the clinical biomarker used to define septic shock, there was greater separation between survivors and non-survivors of septic shock for both f-Met and the lac-AAs measured within 24 h of ICU admission. Additionally, tryptophan was the one metabolite significantly decreased in septic shock compared to all other groups, while its breakdown product kynurenate was one of the 9 significantly increased.

CONCLUSION

Future studies which validate the measurement of lac-AAs and f-Met in conjunction with lactate could define a sepsis subtype characterized by mitochondrial dysfunction.

Therapeutic Strategies Targeting Mitochondrial Dysfunction in Sepsis-induced Cardiomyopathy

Sepsis is an increasingly worldwide problem; it is currently regarded as a complex life-threatening dysfunction of one or more organs as a result of dysregulated host immune response to infections. The heart is one of the most affected organs, as roughly 10% to 70% of sepsis cases are estimated to turn into sepsis-induced cardiomyopathy (SIC). SIC can be defined as a reversible myocardial dysfunction characterized by dilated ventricles, impaired contractility, and decreased ejection fraction. Mitochondria play a critical role in the normal functioning of cardiac tissues as the heart is highly dependent on its production of adenosine triphosphate (ATP), its damage during SIC includes morphology impairment, mitophagy, biogenesis disequilibrium, electron transport chain disturbance, molecular damage from the actions of pro-inflammatory cytokines and many other different impairments that are major contributing factors to the severity of SIC. Although mitochondria-targeted therapies usage is still inadequate in clinical settings, the preclinical study outcomes promise that the implementation of these therapies may effectively treat SIC. This review summarizes the different therapeutic strategies targeting mitochondria structure, quality, and quantity abnormalities for the treatment of SIC.

Carbon monoxide (CO) derived from the CO-releasing molecule CORM-2 reduces peritoneal adhesion formation in a rat model

BACKGROUND

Although low-dose carbon monoxide (CO) administration has been shown to have an anti-fibrotic effect in various fibrotic diseases, its effects on peritoneal adhesion (PA), one of the postoperative complications, are not elucidated. In this study, the effect of CO-releasing tricarbonyldichlororuthenium (II) dimer (CORM-2) administration on the formation of PA and the underlying factors of its potential effect were investigated.

METHODS AND RESULTS

After the induction of PA, rats were divided into four groups with 8 rats in each group. The rats received either (i) dimethyl sulfoxide:saline solution (1:10) as a vehicle, (ii) 2.5 mg/kg CORM-2, (iii) 5 mg/kg CORM-2, or (iv) inactive (i) CORM (iCORM) intragastrically every day for a duration of 7 days. PA was not induced in rats (n = 8) designated as sham controls. Gross, histological, immunohistochemical and quantitative real-time polymerase chain reaction analyses were performed to evaluate the effectiveness of CORM-2 administration. Gross analysis showed that CORM-2 administration reduced PA formation compared to rats treated with vehicle. Histological and immunohistochemical examinations showed that increased collagen deposition, myofibroblast accumulation, microvessel density, and M1 macrophage count in the peritoneal fibrosis area of vehicle-treated rats decreased following CORM-2 treatments. PCR analyses showed that CORM-2 treatments decreased hypoxia-induced Hif1a, profibrotic Tgfb1, ECM components Col1a1 and Col3a1, collagen degradation suppressor Timp1, fibrinolysis inhibitor Serpine1, and pro-inflammatory Tnf mRNA expressions, while increasing the M2 macrophage marker Arg1 mRNA expression.

CONCLUSIONS

These results suggested that CORM-2 administration reduces PA formation by affecting adhesiogenic processes such as pro-inflammatory response, fibrinolytic system, angiogenesis and fibrogenesis.

Xuebijing injection protects sepsis induced myocardial injury by mediating TLR4/NF-κB/IKKα and JAK2/STAT3 signaling pathways

OBJECTIVE

Compelling evidence has demonstrated that Xuebijing (XBJ) exerted protective effects against SIMI. The aims of this study were to investigate whether TLR4/IKKα-mediated NF-κB and JAK2/STAT3 pathways were involved in XBJ's cardio-protection during sepsis and the mechanisms.

METHODS

In this study, rats were randomly assigned to three groups: Sham group; CLP group; XBJ group. Rats were treated with XBJ or sanitary saline after CLP. Echocardiography, myocardial enzymes and HE were used to detect cardiac function. IL-1β, IL-6 and TNF-α in serum were measured using ELISA kits. Cardiomyocyte apoptosis were tested by TUNEL staining. The protein levels of Bax, Bcl-2, Bcl-xl, Cleaved-Caspase 3, Cleaved-Caspase 9, Cleaved-PARP, TLR4, p-NF-κB, p-IKKα, p-JAK2 and p-STAT3 in the myocardium were assayed by western blotting. And finally, immunofluorescence was used to assess the level of p-JAK2 and p-STAT3 in heart tissue.

RESULTS

The results of echocardiography, myocardial enzyme and HE test showed that XBJ could significantly improve SIMI. The IL-1β, IL-6 and TNF-α levels in the serum were markedly lower in the XBJ group than in the CLP group (p<0.05). TUNEL staining's results showed that XBJ ameliorated CLP-induced cardiomyocyte apoptosis. Meanwhile, XBJ downregulated the protein levels of Bax, Cleaved-Caspase 3, Cleaved-Caspase 9, Cleaved-PARP, TLR4, p-NF-κB, p-IKKα, p-JAK2 and p-STAT3, as well as upregulated the protein levels of Bcl-2, Bcl-xl (p <0.05).

CONCLUSIONS

In here, we observed that XBJ's cardioprotective advantages may be attributable to its ability to suppress inflammation and apoptosis via inhibiting the TLR4/ IKKα-mediated NF-κB and JAK2/STAT3 pathways during sepsis.

Cardioprotective effects of Amentoflavone by suppression of apoptosis and inflammation on an in vitro and vivo model of myocardial ischemia-reperfusion injury

Inflammation modulation is currently considered a promising therapeutic strategy to counteract the burden of cardiovascular disease. Amentoflavone (AME) is a natural biflavone with two apigenin molecules that, possess promising anti-inflammatory, anti-oxidative, and anti-cancer properties. In the present study, we aimed to investigate the effects of AME on myocardial ischemia-reperfusion injury in vivo and in vitro, and to elucidate the underlying mechanism. Our results showed that AME significantly reduced the levels of LDH, CK-MB, IL-6, IL-1β, and TNF-α after hypoxia (H) 12 h/reoxygenation (R) 4 h treatment, and significantly increased the cell survival rate of H9c2 cardiomyocytes induced by H/R and inhibited their apoptosis rate. AME (25, 50, 100 mg·kg^-1·d^-1, i.g.) or a positive control drug diltiazem (DIZ) (16 mg·kg^-1·d^-1, i.g.) was used as pretreatment for 7 days; the myocardial ischemia-reperfusion(I/R) model was established. TTC staining results showed that the infarct volume was significantly reduced after AME and DIZ treatment. Oral administration of AME dose-dependently ameliorated I/R injury-induced increase in pro-inflammatory factors (IL-6, IL-1β, and TNF-α) and levels of LDH and CK-MB. Results of TUNEL and HE staining showed that the I/R model had more induced apoptosis, but could be effectively reduced by pretreatment with AME. After surgery, the heart of the rat was examined via western blotting to detect inflammation-related proteins. Compared with the sham group, the p-AKT in the I/R group was significantly reduced and the content of p-NF-κBp65 was significantly increased. However, these changes could be reversed by AME treatment. DIZ treatment exerted similar beneficial effects in I/R rats as the high dose of AME did. This study highlights the excellent therapeutic potential of AME for managing myocardial ischemia-reperfusion injury.

Carbon monoxide as an emerging pharmacological tool to improve lung and liver transplantation protocols

Carbon monoxide (CO) has long been considered purely as a toxic gas. It binds to hemoglobin at high concentrations and displaces oxygen from its binding site, resulting in carboxyhemoglobin formation, which reduces oxygen-carrying capacity of blood and culminates in tissue hypoxia and its associated complications. Recently, however, CO is quickly moving past its historic notorious tag as a poisonous gas to a physiological signaling molecule with therapeutic potentials in several clinical situations including transplant-induced injury. This review discusses current knowledge of CO gas and CO-releasing molecules (CO-RMs) in preclinical models of lung and liver transplantation, and underlying molecular mechanisms of cyto- and organ protection during organ procurement, preservation, implantation and post-transplant periods. In addition, a discussion of the future of CO in clinical organ transplantation is provided.

Carbon monoxide attenuates LPS-induced myocardial dysfunction in rats by regulating the mitochondrial dynamic equilibrium

Lipopolysaccharide (LPS) induces myocardial dysfunction by damaging the mitochondrial structure in cardiomyocytes. Since low levels of carbon monoxide can confer cytoprotective effects against end-organ damage from endotoxic shock, we tested whether treatment with carbon monoxide-releasing molecule-2 (CORM-2) could ameliorate LPS-induced myocardial dysfunction in rats by maintaining the dynamic equilibrium between the mitochondrial fusion and fission processes. Cardiac function, myocardial histopathology, myocardial enzymes, and changes in myocardial mitochondrial function and mitochondrial fusion-fission protein expression were assessed in rats. The mitochondrial structure and morphology were studied by electron microscopy, and the expression levels of key proteins involved in the mitochondrial dynamics were assessed by Western blot assay. Cardiac dysfunction and increased myocardial enzyme activity together with myocardial pathological damage, mitochondrial dysfunction, and impaired mitochondrial dynamics homeostasis were observed in the LPS-challenged septic rats. However, these observations were reversed by CORM-2, which effectively inhibited cardiac and mitochondrial damage in the LPS-challenged rats and improved the survival rate of the animals. In conclusion, CORM-2 regulates the LPS-induced imbalance of the dynamic mitochondrial fusion and fission processes, thereby effectively ameliorating the LPS-induced myocardial dysfunction and improving the survival of the rats.

Advances in the molecular mechanisms of NLRP3 inflammasome activators and inactivators

NLRP3 inflammasome is an intracellular protein complex that initiates cellular injury via assembly of NLRP3, ASC and caspase-1 in response to microbial infection and sterile stressors. The importance of NLRP3 inflammasome in immunity and human diseases has been well documented. Up to now, targeted inhibition of the assembly of NLRP3 inflammasome complex and of its activation was thought to be therapeutic strategy for associated diseases. Recent studies show that a host of molecules such as NIMA-related kinase 7 (Nek7) and DEAD-box helicase 3 X-linked (DDX3X) and a large number of biological mediators including cytokines, microRNAs, nitric oxide, carbon monoxide, nuclear factor erythroid-2 related factor 2 (Nrf2) and cellular autophagy participate in the activation and inactivation of NLRP3 inflammasome. This review summarizes current understanding of the molecular basis of NLRP3 inflammasome activation and inactivation. This knowledge may lead to development of new therapies directed at NLRP3 inflammasome related diseases.

Carbon monoxide releasing molecule‑2 (CORM‑2)‑liberated CO ameliorates acute pancreatitis

The purpose of the present study was to investigate the effect of carbon monoxide (CO) released from CO‑releasing molecule 2 (CORM‑2) on mice with acute pancreatitis (AP). To perform the investigation, a mouse AP model was established using caerulein. The mice were treated with or without CORM‑2. The survival rate of the mice in the different groups was analyzed, and serum amylase and lipase levels were measured to assess the degree of pancreatic injury. The severity of AP was also evaluated by histological examination, and histopathological scoring of the pancreatic damage was performed. Pancreatic cell apoptosis was analyzed using a terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labelling assay. The function of the lung and liver was also assessed in the present study. Furthermore, the role of CORM‑2 on oxidative stress, intercellular adhesion molecule 1 (ICAM‑1) and vascular cell adhesion molecule 1 (VCAM‑1) expression, pro‑inflammatory cytokine production, and nuclear factor (NF)‑κB activation in the pancreas of AP mice was determined. The results demonstrated that CORM‑2 reduced the mortality, pancreatic damage, and lung and liver injury of AP mice. CORM‑2 administration also reduced systemic and localized inflammatory cell factors. Furthermore, treatment with CORM‑2 inhibited the expression of ICAM‑1 and VCAM‑1, and the activation of NF‑κB and phosphorylated inhibitor of NF‑κB subunit α, in the pancreas of AP mice. These results indicated that CO released from CORM‑2 exerted protective effects on AP mice, and the beneficial effects were likely due to inhibition of NF‑κB pathway activation.

Carbon monoxide releasing molecule‑2 (CORM‑2)‑liberated CO ameliorates acute pancreatitis

The purpose of the present study was to investigate the effect of carbon monoxide (CO) released from CO-releasing molecule 2 (CORM-2) on mice with acute pancreatitis (AP). To perform the investigation, a mouse AP model was established using caerulein. The mice were treated with or without CORM-2. The survival rate of the mice in the different groups was analyzed, and serum amylase and lipase levels were measured to assess the degree of pancreatic injury. The severity of AP was also evaluated by histological examination, and histopathological scoring of the pancreatic damage was performed. Pancreatic cell apoptosis was analyzed using a terminal deoxynucleotidyl-transferase-mediated dUTP nick end labelling assay. The function of the lung and liver was also assessed in the present study. Furthermore, the role of CORM-2 on oxidative stress, intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) expression, pro-inflammatory cytokine production, and nuclear factor (NF)-κB activation in the pancreas of AP mice was determined. The results demonstrated that CORM-2 reduced the mortality, pancreatic damage, and lung and liver injury of AP mice. CORM-2 administration also reduced systemic and localized inflammatory cell factors. Furthermore, treatment with CORM-2 inhibited the expression of ICAM-1 and VCAM-1, and the activation of NF-κB and phosphorylated inhibitor of NF-κB subunit α, in the pancreas of AP mice. These results indicated that CO released from CORM-2 exerted protective effects on AP mice, and the beneficial effects were likely due to inhibition of NF-κB pathway activation.

Salivary Gland Extract from Aedes aegypti Improves Survival in Murine Polymicrobial Sepsis through Oxidative Mechanisms

Sepsis is a systemic disease with life-threatening potential and is characterized by a dysregulated immune response from the host to an infection. The organic dysfunction in sepsis is associated with the production of inflammatory cascades and oxidative stress. Previous studies showed that Aedes aegypti saliva has anti-inflammatory, immunomodulatory, and antioxidant properties. Considering inflammation and the role of oxidative stress in sepsis, we investigated the effect of pretreatment with salivary gland extract (SGE) from Ae. aegypti in the induction of inflammatory and oxidative processes in a murine cecum ligation and puncture (CLP) model. Here, we evaluated animal survival for 16 days, as well as bacterial load, leukocyte migration, and oxidative parameters. We found that the SGE pretreatment improved the survival of septic mice, reduced bacterial load and neutrophil influx, and increased nitric oxide (NO) production in the peritoneal cavity. With regard to oxidative status, SGE increased antioxidant defenses as measured by Trolox equivalent antioxidant capacity (TEAC) and glutathione (GSH), while reducing levels of the oxidative stress marker malondialdehyde (MDA). Altogether, these data suggest that SGE plays a protective role in septic animals, contributing to oxidative and inflammatory balance during sepsis. Therefore, Ae. aegypti SGE is a potential source for new therapeutic molecule(s) in polymicrobial sepsis, and this effect seems to be mediated by the control of inflammation and oxidative damage.

miR-146a Attenuates Sepsis-Induced Myocardial Dysfunction by Suppressing IRAK1 and TRAF6 via Targeting ErbB4 Expression

Myocardial dysfunction is a major manifestation of sepsis and closely associated with the increased mortality. MicroRNA-146 is one of the most important microRNAs identified as a potent negative regulator in innate immune and inflammatory responses induced by lipopolysaccharide (LPS). We aimed to identify the role and potential regulatory mechanism of miR-146a in sepsis-induced cardiac dysfunction with the induction of ErbB4 signaling. H9C2 cells were treated with LPS to induce sepsis, and miR-146a overexpression significantly increased the cell viability, reduced the apoptosis and ROS level, and attenuated the release of proinflammatory cytokines including TNF-α and IL-1β. Levels of ErbB4, p-NF-κB, NF-κB, TRAF6, IRAK1, caspase 3, Bcl-2, and Bax were measured by Western blot. The overexpression of miR-146a significantly increased the ErbB4 expression, decreased the expression of TRAF6, IRAK1, caspase 3, and the phosphorylation level of NF-κB, and also increased the Bcl-2/Bax ratio, suggesting the inhibition of inflammation and apoptosis. The protective effects were all abolished by the use of siErbB4. In conclusion, our results demonstrated that the overexpression of miR-146a mitigates myocardial injury by negatively regulating NF-κB activation and inflammatory cytokine production via targeting ErbB4 in LPS-induced sepsis.

Exogenous carbon monoxide inhibits neutrophil infiltration in LPS-induced sepsis by interfering with FPR1 via p38 MAPK but not GRK2

Excessive neutrophil infiltration in vital organs is life-threatening to patients who suffer from sepsis. We identified a critical role of exogenous carbon monoxide (CO) in the inhibition of neutrophil infiltration during lipopolysaccharide (LPS)-induced sepsis. CO delivered from carbon monoxide-releasing molecule 2 (CORM-2) dramatically increased the survival rate of C57BL/6 mice subjected to LPS in vivo. CORM-2 significantly suppressed neutrophil infiltration in liver and lung as well as markers of inflammatory responses. Affymetrix GeneChip array analysis revealed that the increased expression of chemoattractant receptor formyl peptide receptor 1 (FPR1) may contribute to the excessive neutrophil infiltration. The under agarose migration assay demonstrated that LPS stimulation promoted migration to the ligand of FPR1, N-Formyl-Met-Leu-Phe (fMLP) but that CORM-2 treatment inhibited this promotion. Further studies demonstrated that CORM-2 internalized FPR1 by inhibiting p38 mitogen-activated protein kinase (MAPK) but not G protein-coupled receptor kinase 2 (GRK2), which may explain the inhibitory effect of CORM-2 on LPS-stimulated neutrophils. In summary, our study demonstrates that exogenous CO inhibits sepsis-induced neutrophil infiltration by interfering with FPR1 via p38 MAPK but not GRK2.

Reduced silent information regulator 1 signaling exacerbates sepsis-induced myocardial injury and mitigates the protective effect of a liver X receptor agonist

Myocardial injury and dysfunction are critical manifestations of sepsis. Previous studies have reported that liver X receptor (LXR) activation is protective during sepsis. However, whether LXR activation protects against septic heart injury and its underlying mechanisms remain elusive. This study was designed to determine the role of LXR activation in the septic heart with a focus on SIRT1 (silent information regulator 1) signaling. Male cardiac-specific SIRT1 knockout mice (SIRT1-/-) and their wild-type littermates were subjected to sepsis by cecal ligation and puncture (CLP) in the presence or absence of LXR agonist T0901317. The survival rate of mice was recorded during the 7-day period post CLP. Our results demonstrated that SIRT1-/- mice suffered from exacerbated mortality and myocardial injury in comparison with their wild-type littermates. Meanwhile, T0901317 treatment improved mice survival, accompanied by significant ameliorations of myocardial injury and dysfunction in wild-type mice but not in SIRT1-/- mice. Furthermore, the levels of myocardial inflammatory cytokines (TNF-α, IL-6, IL-1β, MCP-1, MPO and HMGB1), oxidative stress (ROS generation, MDA), endoplasmic-reticulum (ER) stress (protein levels of CHOP, GRP78, GRP94, IRE1α, and ATF6), and cardiac apoptosis following CLP were inhibited by T0901317 treatment in wild-type mice but not in SIRT1-/- mice. Mechanistically, T0901317 enhanced SIRT1 signaling and the subsequent deacetylation and activation of antioxidative FoxO1 and anti-ER stress HSF1, as well as the deacetylation and inhibition of pro-inflammatory NF-ΚB and pro-apoptotic P53, thereby alleviating sepsis-induced myocardial injury and dysfunction. Our data support the promise of LXR activation as an effective strategy for relieving heart septic injury.

Preconditioning with carbon monoxide inhalation promotes retinal ganglion cell survival against optic nerve crush via inhibition of the apoptotic pathway

Optic neurodegeneration, in addition to central nervous trauma, initiates impairments to neurons resulting in retinal ganglion cell (RGC) damage. Carbon monoxide (CO) has been observed to elicit neuroprotection in various experimental models. The present study investigated the potential retinal neuroprotection of preconditioning with CO inhalation in a rat model of optic nerve crush (ONC). Adult male Sprague‑Dawley rats were preconditioned with inhaled CO (250 ppm) or air for 1 h prior to ONC. Animals were euthanized at 1 or 2 weeks following surgery. RGC densities were quantified by hematoxylin and eosin (H&E) staining and FluoroGold labeling. Visual function was measured via flash visual evoked potentials (FVEP). Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, and caspase‑9 and caspase‑3 activity in the retinas, were assessed at 2 weeks post‑ONC. The RGC density of CO + crush rats was significantly increased compared with that of the corresponding crush‑only rats at 2 weeks (survival rate, 66.2 vs. 48.2% as demonstrated by H&E staining, P<0.01; and 67.6 vs. 37.6% as demonstrated by FluoroGold labeling, P<0.05). FVEP measures indicated a significantly better‑preserved latency and amplitude of the P1 wave in the CO + crush rats compared with the crush‑only rats. The TUNEL assays demonstrated fewer apoptotic cells in the CO + crush group compared with the crush‑only group, accompanied by the suppression of caspase‑9 and caspase‑3 activity. The results of the present study suggested that inhaled CO preconditioning may be neuroprotective against ONC insult via inhibition of neuronal apoptosis.

Eff ects of hemin, a heme oxygenase-1 inducer in L-arginine-induced acute pancreatitis and associated lung injury in adult male albino rats

Objective. The aim of the current study was to assess the protective outcome of hemin, a heme oxygenase-1 (HO-1) inducer on L-arginine-induced acute pancreatitis in rats. Acute pancreatitis (AP) is considered to be a critical inflammatory disorder with a major impact on the patient health. Various theories have been recommended regarding the pathophysiology of AP and associated pulmonary complications.

Methods. Twenty-four adult male albino rats were randomly divided into four groups: control group, acute pancreatitis (AP), hemin pre-treated AP group, and hemin post-treated AP group.

Results. Administration of hemin before induction of AP significantly attenuated the L-arginine- induced pancreatitis and associated pulmonary complications characterized by the increasing serum levels of amylase, lipase, tumor necrosis factor-α, nitric oxide, and histo-architectural changes in pancreas and lungs as compared to control group. Additionally, pre-treatment with hemin significantly compensated the deficits in total antioxidant capacities and lowered the elevated malondialdehyde levels observed with AP. On the other hand, post-hemin administration did not show any protection against L-arginine-induced AP.

Conclusions. The current study indicates that the induction of HO-1 by hemin pre-treatment significantly ameliorated the L-arginine-induced pancreatitis and associated pulmonary complications may be due to its anti-inflammatory and antioxidant properties.

The relationship between ambient carbon monoxide and heart rate variability-a systematic world review-2015

The objective of this report is to systematically review the literature pertaining to the evidence of the relationship between environmental carbon monoxide (CO) and heart rate variability (HRV). For this purpose, reports published in English scientific journals were critically reviewed by the authors employing PRISMA guidelines. Fifteen studies performed in China, Finland, Israel, Mexico, Taiwan, and the USA were identified as eligible to be included in the review. Out of these, 10 studies found a significant relationship between CO and HRV. However, while a proportion of these studies found an increase in parasympathetic tone, other studies found an increase in sympathetic tone. Methodological differences across these studies, including population understudy, sample size, measurement techniques, and accounting for intervening variables do not pave the way for a consensual conclusion. In conclusion, the lack of consistent results on the relationship between CO and HRV as reflected by the present review calls for more research employing appropriate indoor and outdoor ecological designs that account for possible interaction effects and individual differences. Involvement of olfactory receptors is suggested as a possible underlying mechanism for both short response latencies as well as for the diversity between individuals and samples investigated.

Carbon Monoxide Improves Neurologic Outcomes by Mitochondrial Biogenesis after Global Cerebral Ischemia Induced by Cardiac Arrest in Rats

Mitochondrial dysfunction contributes to brain injury following global cerebral ischemia after cardiac arrest. Carbon monoxide treatment has shown potent cytoprotective effects in ischemia/reperfusion injury. This study aimed to investigate the effects of carbon monoxide-releasing molecules on brain mitochondrial dysfunction and brain injury following resuscitation after cardiac arrest in rats. A rat model of cardiac arrest was established by asphyxia. The animals were randomly divided into the following 3 groups: cardiac arrest and resuscitation group, cardiac arrest and resuscitation plus carbon monoxide intervention group, and sham control group (no cardiac arrest). After the return of spontaneous circulation, neurologic deficit scores (NDS) and S-100B levels were significantly decreased at 24, 48, and 72 h, but carbon monoxide treatment improved the NDS and S-100B levels at 24 h and the 3-day survival rates of the rats. This treatment also decreased the number of damaged neurons in the hippocampus CA1 area and increased the brain mitochondrial activity. In addition, it increased mitochondrial biogenesis by increasing the expression of biogenesis factors including peroxisome proliferator-activated receptor-γ coactivator-1α, nuclear respiratory factor-1, nuclear respiratory factor-2 and mitochondrial transcription factor A. Thus, this study showed that carbon monoxide treatment alleviated brain injury after cardiac arrest in rats by increased brain mitochondrial biogenesis.

Carbon monoxide improves neuronal differentiation and yield by increasing the functioning and number of mitochondria

The process of cell differentiation goes hand-in-hand with metabolic adaptations, which are needed to provide energy and new metabolites. Carbon monoxide (CO) is an endogenous cytoprotective molecule able to inhibit cell death and improve mitochondrial metabolism. Neuronal differentiation processes were studied using the NT2 cell line, which is derived from human testicular embryonic teratocarcinoma and differentiates into post-mitotic neurons upon retinoic acid treatment. CO-releasing molecule A1 (CORM-A1) was used do deliver CO into cell culture. CO treatment improved NT2 neuronal differentiation and yield, since there were more neurons and the total cell number increased following the differentiation process. CO supplementation enhanced the mitochondrial population in post-mitotic neurons derived from NT2 cells, as indicated by an increase in mitochondrial DNA. CO treatment during neuronal differentiation increased the extent of the classical metabolic change that occurs during neuronal differentiation, from glycolytic to more oxidative metabolism, by decreasing the ratio of lactate production and glucose consumption. The expression of pyruvate and lactate dehydrogenases was higher, indicating an augmented oxidative metabolism. Moreover, these findings were corroborated by an increased percentage of (13) C incorporation from [U-(13) C]glucose into the tricarboxylic acid cycle metabolites malate and citrate, and also glutamate and aspartate in CO-treated cells. Finally, under low levels of oxygen (5%), which enhances glycolytic metabolism, some of the enhancing effects of CO on mitochondria were not observed. In conclusion, our data show that CO improves neuronal and mitochondrial yield by stimulation of tricarboxylic acid cycle activity, and thus oxidative metabolism of NT2 cells during the process of neuronal differentiation. The process of cell differentiation is coupled with metabolic adaptations. Carbon monoxide (CO) is an endogenous cytoprotective gasotransmitter able to prevent cell death and improve mitochondrial metabolism. Herein CO supplementation improved neuronal differentiation yield, by enhancing mitochondrial population and promoting the classical metabolic change that occurs during neuronal differentiation, from glycolytic to oxidative metabolism.

Ethyl pyruvate protects against sepsis by regulating energy metabolism

Background

Ethyl pyruvate (EP) is a derivative of pyruvic acid that has been demonstrated to be a potential scavenger of reactive oxygen species as well as an anti-inflammatory agent. In this study, we investigated the protective effects of EP and its role in regulating the energy metabolism in the livers of cecal-ligation-and-puncture-induced septic mice.

Methods

The animals were treated intraperitoneally with 0.2 mL of Ringer’s lactate solution or an equivalent volume of Ringer’s lactate solution containing EP immediately after cecal ligation and puncture. Each mouse in the Sham group was only subjected to a laparotomy. At 30-, 60-, 180-, and 360-minute time points, we measured the histopathological alterations of the intestines, and the plasma levels of interleukin (IL)-1β, IL-6, IL-10, and tumor necrosis factor-α, and the total antioxidative capacity, malondialdehyde content, and lactate and lactate/pyruvate levels in livers. Furthermore, we detected the levels of adenosine triphosphate, total adenylate, and energy charge in the livers.

Results

Our results demonstrated that the administration of EP significantly improved the survival rate and reduced intestinal histological alterations. EP inhibited the plasma levels of IL-1β, IL-6, and tumor necrosis factor-α and increased the IL-10 level. EP significantly inhibited the elevation of the malondialdehyde, lactate, and lactate/pyruvate levels and enhanced the total antioxidative capacity levels in the liver tissues. The downregulation of the adenosine triphosphate, total adenylate, and energy charge levels in the liver tissues was reversed in the septic mice treated with EP.

Conclusion

The results suggest that EP administration effectively modulates the energy metabolism, which may be an important component in treatment of sepsis.

Low-dose carbon monoxide inhalation protects neuronal cells from apoptosis after optic nerve crush

Glaucomatous optic neuropathy, including axonal degeneration and apoptotic death of retinal ganglion cells (RGCs), eventually leads to irreversible visual impairment. Carbon monoxide (CO) acts as a therapeutic agent against neural injury via its anti-apoptotic effect. Here we hypothesized that low-dose CO inhalation can protect RGCs in a rat model of optic nerve crush (ONC). ONC was performed on adult male Sprague Dawley rats to imitate glaucomatous optic damage. Low-dose CO (250 ppm) or air was inhaled for 1 h immediately after ONC, and all the tests were carried out 2 weeks later. Flash visual evoked potentials (FVEP) and pupil light relax (PLR) were recorded for the assessment of visual function. RGC density was evaluated by hematoxylin and eosin staining and Fluorogold labeling. Retinal apoptotic process was assessed by TUNEL staining and caspase-3 activity measurement. Low-dose CO treatment significantly ameliorated the abnormalities of FVEP and PLR induced by ONC. As expected, the RGC density was increased remarkably by CO inhalation after the glaucomatous optic nerve insult. Moreover, CO treatment after ONC significantly decreased the number of TUNEL-positive cells in ganglion cell layer and attenuated the retinal caspase-3 activity. Low-dose CO inhalation protects RGCs from optic nerve injury via inhibiting caspase-3 dependent apoptosis.

Exogenous Carbon Monoxide Decreases Sepsis-Induced Acute Kidney Injury and Inhibits NLRP3 Inflammasome Activation in Rats

Carbon monoxide (CO) has shown various physiological effects including anti-inflammatory activity in several diseases, whereas the therapeutic efficacy of CO on sepsis-induced acute kidney injury (AKI) has not been reported as of yet. The purpose of the present study was to explore the effects of exogenous CO on sepsis-induced AKI and nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome activation in rats. Male rats were subjected to cecal ligation and puncture (CLP) to induce sepsis and AKI. Exogenous CO delivered from CO-releasing molecule 2 (CORM-2) was used intraperitoneally as intervention after CLP surgery. Therapeutic effects of CORM-2 on sepsis-induced AKI were assessed by measuring serum creatinine (Scr) and blood urea nitrogen (BUN), kidney histology scores, apoptotic cell scores, oxidative stress, levels of cytokines TNF-α and IL-1β, and NLRP3 inflammasome expression. CORM-2 treatment protected against the sepsis-induced AKI as evidenced by reducing serum Scr/BUN levels, apoptotic cells scores, increasing survival rates, and decreasing renal histology scores. Furthermore, treatment with CORM-2 significantly reduced TNF-α and IL-1β levels and oxidative stress. Moreover, CORM-2 treatment significantly decreased NLRP3 inflammasome protein expressions. Our study provided evidence that CORM-2 treatment protected against sepsis-induced AKI and inhibited NLRP3 inflammasome activation, and suggested that CORM-2 could be a potential therapeutic candidate for treating sepsis-induced AKI.

Biliary tract external drainage increases the expression levels of heme oxygenase-1 in rat livers

Background

Heme oxygenase-1 (HO-1) protects cells by anti-oxidation, maintaining normal microcirculation and anti-inflammatory under stress. This study investigated the effects of biliary tract external drainage (BTED) on the expression levels of HO-1 in rat livers.

Methods

Biliary tract external drainage was performed by inserting a cannula into the bile duct. Sixty Sprague–Dawley rats were randomized to the following groups: sham 1 h group; BTED 1 h group; bile duct ligation (BDL) 1 h group; sham 6 h group and BTED 6 h group. The expression levels of HO-1 mRNA were analyzed using real-time RT-PCR. The expression levels of HO-1 were analyzed using immunohistochemistry.

Results

The expression levels of HO-1 mRNA in the liver of the BTED group increased significantly compared with the sham group 1 and 6 h after surgery (p < 0.05).The expression levels of HO-1 in the BTED group increased significantly compared with the sham group 1 and 6 h after surgery. The expression levels of HO-1 mRNA in the liver in the BDL group decreased significantly compared with the sham group 1 h after surgery (p < 0.05).The expression levels of HO-1 in the BDL group decreased significantly compared with the sham group at this time.

Conclusion

Biliary tract external drainages increase the expression levels of HO-1 in the liver.

Regulation of mitochondrial biogenesis and its intersection with inflammatory responses

SIGNIFICANCE

Mitochondria play a vital role in cellular homeostasis and are susceptible to damage from inflammatory mediators released by the host defense. Cellular recovery depends, in part, on mitochondrial quality control programs, including mitochondrial biogenesis.

RECENT ADVANCES

Early-phase inflammatory mediator proteins interact with PRRs to activate NF-κB-, MAPK-, and PKB/Akt-dependent pathways, resulting in increased expression or activity of coactivators and transcription factors (e.g., PGC-1α, NRF-1, NRF-2, and Nfe2l2) that regulate mitochondrial biogenesis. Inflammatory upregulation of NOS2-induced NO causes mitochondrial dysfunction, but NO is also a signaling molecule upregulating mitochondrial biogenesis via PGC-1α, participating in Nfe2l2-mediated antioxidant gene expression and modulating inflammation. NO and reactive oxygen species generated by the host inflammatory response induce the redox-sensitive HO-1/CO system, causing simultaneous induction of mitochondrial biogenesis and antioxidant gene expression.

CRITICAL ISSUES

Recent evidence suggests that mitochondrial biogenesis and mitophagy are coupled through redox pathways; for instance, parkin, which regulates mitophagy in chronic inflammation, may also modulate mitochondrial biogenesis and is upregulated through NF-κB. Further research on parkin in acute inflammation is ongoing. This highlights certain common features of the host response to acute and chronic inflammation, but caution is warranted in extrapolating findings across inflammatory conditions.

FUTURE DIRECTIONS

Inflammatory mitochondrial dysfunction and oxidative stress initiate further inflammatory responses through DAMP/PRR interactions and by inflammasome activation, stimulating mitophagy. A deeper understanding of mitochondrial quality control programs' impact on intracellular inflammatory signaling will improve our approach to the restoration of mitochondrial homeostasis in the resolution of acute inflammation.

Exogenous carbon monoxide suppresses Escherichia coli vitality and improves survival in an Escherichia coli-induced murine sepsis model

AIM

Endogenous carbon monoxide (CO) has been shown to modulate inflammation and inhibit cytokine production both in vivo and in vitro. The aim of this study was to examine whether exogenous carbon monoxide could suppress the vitality of Escherichia coli (E coli) and improve the survival rate in an E coli-induced murine sepsis model.

METHODS

ICR mice were infected with E coli, and immediately injected intravenously with carbon monoxide releasing molecule-2 (CORM-2, 8 mg/kg) or inactive CORM-2 (8 mg/kg). The survival rate was monitored 6 times daily for up to 36 h. The blood samples, liver and lung tissues were collected at 6 h after the infection. Bacteria in peritoneal lavage fluid, blood and tissues were enumerated following culture. Tissue iNOS mRNA expression was detected using RT-PCR. NF-κB expression was detected with Western blotting.

RESULTS

Addition of CORM-2 (200 and 400 μmol/L) into culture medium concentration-dependently suppressed the growth of E coli and decreased the colony numbers, but inactive CORM-2 had no effect. Treatment of the infected mice with CORM-2 significantly increased the survival rate to 55%, while all the infected mice treated with inactive CORM-2 died within 36 h. E coli infection caused severe pathological changes in liver and lungs, and significantly increased serum transaminases, lipopolysaccharide, TNF-α and IL-1β levels, as well as myeloperoxidase activity, TNF-α and IL-1β levels in the major organs. Meanwhile, E coli infection significantly increased the number of colonies and the expression of iNOS mRNA and NF-κB in the major organs. All these abnormalities were significantly attenuated by CORM-2 treatment, while inactive CORM-2 was ineffective.

CONCLUSION

In addition directly suppressing E coli, CORM-2 protects the liver and lungs against E coli-induced sepsis in mice, thus improving their survival.