α-Lipoic acid attenuates LPS-induced cardiac dysfunction through a PI3K/Akt-dependent mechanism

The Protective Effect of Octanoic Acid on Sepsis: A Review

Sepsis, a systemic inflammation that occurs in response to a bacterial infection, is a significant medical challenge. Research conducted over the past decade has indicated strong associations among a patient's nutritional status, the composition of their gut microbiome, and the risk, severity, and prognosis of sepsis. Octanoic acid (OA) plays a vital role in combating sepsis and has a protective effect on both animal models and human patients. In this discussion, the potential protective mechanisms of OA in sepsis, focusing on its regulation of the inflammatory response, immune system, oxidative stress, gastrointestinal microbiome and barrier function, metabolic disorders and malnutrition, as well as organ dysfunction are explored. A comprehensive understanding of the mechanisms by which OA act may pave the way for new preventive and therapeutic approaches to sepsis.

Probiotic Clostridium butyricum ameliorates cognitive impairment in obesity via the microbiota-gut-brain axis

Obesity is a risk factor for cognitive dysfunction and neurodegenerative disease, including Alzheimer's disease (AD). The gut microbiota-brain axis is altered in obesity and linked to cognitive impairment and neurodegenerative disorders. Here, we targeted obesity-induced cognitive impairment by testing the impact of the probiotic Clostridium butyricum, which has previously shown beneficial effects on gut homeostasis and brain function. Firstly, we characterized and analyzed the gut microbial profiles of participants with obesity and the correlation between gut microbiota and cognitive scores. Then, using an obese mouse model induced by a Western-style diet (high-fat and fiber-deficient diet), the effects of Clostridium butyricum on the microbiota-gut-brain axis and hippocampal cognitive function were evaluated. Finally, fecal microbiota transplantation was performed to assess the functional link between Clostridium butyricum remodeling gut microbiota and hippocampal synaptic protein and cognitive behaviors. Our results showed that participants with obesity had gut microbiota dysbiosis characterized by an increase in phylum Proteobacteria and a decrease in Clostridium butyricum, which were closely associated with cognitive decline. In diet-induced obese mice, oral Clostridium butyricum supplementation significantly alleviated cognitive impairment, attenuated the deficit of hippocampal neurite outgrowth and synaptic ultrastructure, improved hippocampal transcriptome related to synapses and dendrites; a comparison of the effects of Clostridium butyricum in mice against human AD datasets revealed that many of the genes changes in AD were reversed by Clostridium butyricum; concurrently, Clostridium butyricum also prevented gut microbiota dysbiosis, colonic barrier impairment and inflammation, and attenuated endotoxemia. Importantly, fecal microbiota transplantation from donor-obese mice with Clostridium butyricum supplementation facilitated cognitive variables and colonic integrity compared with from donor obese mice, highlighting that Clostridium butyricum's impact on cognitive function is largely due to its ability to remodel gut microbiota. Our findings provide the first insights into the neuroprotective effects of Clostridium butyricum on obesity-associated cognitive impairments and neurodegeneration via the gut microbiota-gut-brain axis.

Beneficial impact of cardiac heavy metal scavenger metallothionein in sepsis-provoked cardiac anomalies dependent upon regulation of endoplasmic reticulum stress and ferroptosis but not autophagy

AIMS

Sepsis represents a profound proinflammatory response with a major contribution from oxidative injury. Here we evaluated possible impact of heavy metal scavenger metallothionein (MT) on endotoxin lipopolysaccharide (LPS)-induced oxidative stress, endoplasmic reticulum (ER) stress, autophagy, and ferroptosis enroute to myocardial injury along with interplay among these stress domains.

MATERIALS AND METHODS

Echocardiographic, cardiomyocyte mechanical and intracellular Ca2+ responses were monitored in myocardia from WT and transgenic mice with cardiac-selective MT overexpression challenged with LPS. Oxidative stress, stress signaling (p38, ERK, JNK), ER stress, autophagy, and ferroptosis were scrutinized.

KEY FINDINGS

RNAseq analysis revealed discrepant patterns in ferroptosis between LPS-exposed and normal murine hearts. LPS insult enlarged LV end systolic dimension, suppressed fractional shortening, ejection fraction, maximal velocity of shortening/relengthening and peak shortening, as well as elongated relengthening along with dampened intracellular Ca2+ release and reuptake. In addition, LPS triggered oxidative stress (lowered glutathione/glutathione disulfide ratio and O2- production), activation of stress cascades (p38, ERK, JNK), ER stress (GRP78, PERK, Gadd153, and IRE1α), inflammation (TNFα and iNOS), unchecked autophagy (LCB3, Beclin-1 and Atg7), ferroptosis (GPx4 and SLC7A11) and interstitial fibrosis. Although MT overexpression itself did not reveal response on cardiac function, it attenuated or mitigated LPS-evoked alterations in echocardiographic, cardiomyocyte contractile and intracellular Ca2+ characteristics, O2- production, TNFα level, ER stress and ferroptosis (without affecting autophagy, elevated AMP/ATP ratio, and iNOS). In vitro evidence revealed beneficial effects of suppression of oxidative stress, ER stress and ferroptosis against LPS-elicited myocardial anomalies.

SIGNIFICANCE

These data strongly support the therapeutic promises of MT and ferroptosis in septic cardiomyopathy.

AR-A014418, a glycogen synthase kinase-3β inhibitor, mitigates lipopolysaccharide-induced inflammation in rat dental pulp stem cells via NLR family pyrin domain containing 3 inflammasome impairment

Background/purpose

Cell pyroptosis and gingival inflammation have been implicated in periodontitis progression. Our previous study revealed that AR-A014418, a pharmacological inhibitor of glycogen synthase kinase-3β (GSK-3β), can enhance the migratory and osteogenic differentiation abilities of rat dental pulp stem cells (rDPSCs). The present study aimed to explore the effect of AR on the inflammation of rDPSCs.

Materials and methods

The primary rDPSCs were isolated and identified by flow cytometry, as well as Oil red O and Alizarin Red S staining. The rDPSCs were cultured and exposed to lipopolysaccharide (LPS) before treating them with different concentrations of AR-A014418. The cell viability was detected using the CCK-8 assay. The generation and secretion of pro-inflammatory cytokines (IL-18, TNF-α, L-1β, and IL-6) were examined by qPCR and ELISA, respectively. To investigate the activation of the NLRP3 inflammasome, the expression levels of pro-caspase 1, cleaved caspase 1, as well as NLRP3 were analyzed by western blotting and immunofluorescence, respectively.

Results

In the rDPSCs, LPS prohibited cell viability and enhanced the generation and secretion of pro-inflammatory cytokines. LPS upregulated NLRP3 and cleaved caspase-1 protein levels and promoted ASC speck formation in the rDPSCs. AR-A014418 administration effectively blocked the LPS-induced inflammation of the rDPSCs in a dose-dependent way. Mechanistically, AR-A014418 significantly restrained the up-regulation of NLRP3 and cleaved caspase-1 in LPS-treated rDPSCs.

Conclusion

Collectively, our findings suggest that AR-A014418 significantly mitigates LPS-induced inflammation of rDPSCs by blocking the activation of the NLRP3 inflammasome.

Nanosystems for oxidative stress regulation in the anti-inflammatory therapy of acute kidney injury

Acute kidney injury (AKI) is a clinical syndrome that results from a rapid decline in renal structure or renal functional impairment with the main pathological feature of sublethal and lethal damage to renal tubular cells. However, many potential therapeutic agents cannot achieve the desired therapeutic effect because of their poor pharmacokinetics and short retention time in the kidneys. With the recent emergence and progress of nanotechnology, nanodrugs with unique physicochemical properties could prolong circulation time, enhance efficient targeted delivery, and elevate the accumulation of therapeutics that can cross the glomerular filtration barrier and indicate comprehensive application prospects in the prevention and treatment of AKI. In this review, various types of nanosystems (such as liposomes, polymeric nanosystems, inorganic nanoparticles and cell-derived extracellular vesicles) are designed and applied to improve the pharmacokinetics of drug formation, which could further relieve the burden on the kidneys caused by the final cumulative dose of drugs in conventional treatments. Moreover, the passive or active targeting effect of nanosystems can also reduce the total therapeutic dose and off-target adverse effects on other organs. Nanodelivery systems for treating AKI that alleviate oxidative stress-induced renal cell damage and regulate the inflammatory kidney microenvironment are summarized.

CARDIOMYOCYTE REPROGRAMMING IN ANIMAL MODELS OF SEPTIC SHOCK

ABSTRACT

Cardiomyocyte reprogramming plays a pivotal role in sepsis-induced cardiomyopathy through the induction or overexpression of several factors and enzymes, ultimately leading to the characteristic decrease in cardiac contractility. The initial trigger is the binding of LPS to TLR-2, -3, -4, and -9 and of proinflammatory cytokines, such as TNF, IL-1, and IL-6, to their respective receptors. This induces the nuclear translocation of nuclear factors, such as NF-κB, via activation of MyD88, TRIF, IRAK, and MAPKs. Among the latter, ROS- and estrogen-dependent p38 and ERK 1/2 are proinflammatory, whereas JNK may play antagonistic, anti-inflammatory roles. Nuclear factors induce the synthesis of cytokines, which can amplify the inflammatory signal in a paracrine fashion, and of several effector enzymes, such as NOS-2, NOX-1, and others, which are ultimately responsible for the degradation of cardiomyocyte contractility. In parallel, the downregulation of enzymes involved in oxidative phosphorylation causes metabolic reprogramming, followed by a decrease in ATP production and the release of fragmented mitochondrial DNA, which may augment the process in a positive feedback loop. Other mediators, such as NO, ROS, the enzymes PI3K and Akt, and adrenergic stimulation may play regulatory roles, but not all signaling pathways that mediate cardiac dysfunction of sepsis do that by regulating reprogramming. Transcription may be globally modulated by miRs, which exert protective or amplifying effects. For all these mechanisms, differentiating between modulation of cardiomyocyte reprogramming versus systemic inflammation has been an ongoing but worthwhile experimental challenge.

A bibliometric analysis of sepsis-induced myocardial dysfunction from 2002 to 2022

Background

Sepsis-induced myocardial dysfunction (SIMD) has a significant contribution to sepsis-caused death in critically ill patients. In recent years, the number of published articles related to SIMD has increased rapidly. However, there was no literature that systematically analyzed and evaluated these documents. Thus, we aimed to lay a foundation for researchers to quickly understand the research hotspots, evolution processes and development trends in the SIMD field via a bibliometric analysis.

Methods

Articles related to SIMD were retrieved and extracted from the Web of Science Core Collection on July 19th, 2022. CiteSpace (version 6.1.R2) and VOSviewer (version 1.6.18) were used for performing visual analysis.

Results

A total of 1,076 articles were included. The number of SIMD-related articles published each year has increased significantly. These publications mainly came from 56 countries, led by China and the USA, and 461 institutions, but without stable and close cooperation. As authors, Li Chuanfu published the most articles, while Rudiger Alain had the most co-citations. Shock was the journal with the most studies, and Critical Care Medicine was the most commonly cited journal. All keywords were grouped into six clusters, some of which represented the current and developing research directions of SIMD as the molecular mechanisms.

Conclusion

Research on SIMD is flourishing. It is necessary to strengthen cooperation and exchanges between countries and institutions. The molecular mechanisms of SIMD, especially oxidative stress and regulated cell death, will be critical subjects in the future.

TSLP protects against sepsis-induced liver injury by inducing autophagy via activation of the PI3K/Akt/STAT3 pathway

BACKGROUND

Liver injury is the main factor in multiple organ failure caused by sepsis. Thymic stromal lymphopoietin (TSLP) is derived from epithelial cells and plays an important role in inflammation, allergies and cancer. The role of TSLP in sepsis-induced liver injury (SILI) is unclear. The purpose of this study was to investigate the effect of TSLP on sepsis-induced liver injury and to clarify the mechanism.

METHODS

Wild-type (WT) mice and TSLPR knockout (TSLPR^-/-) mice were subjected to cecal ligation and puncture (CLP) to generate a SILI model. Liver injury was assessed by measuring the levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), histologic liver injury scores, hepatocyte death, and liver inflammatory factors. Signal pathways were explored in vivo to identify possible mechanisms for TSLP in SILI.

RESULTS

The expression of TSLP and TSLPR increased during SILI. Deletion of TSLPR exacerbated liver injury in terms of serum ALT, AST, histologic liver injury scores, and liver inflammatory factors. Compared with controls, administration of exogenous recombinant mouse TSLP reduced liver injury in WT mice during SILI, but failed to reduce liver injury in TSLPR^-/- mice. TSLP induced autophagy in hepatocytes during SILI. Mechanistically, Akt and STAT3 were activated in WT mice during SILI. The opposite results were observed in TSLPR^-/- mice. In addition, the protective effects of TSLP in WT mice were blocked by PI3K inhibitor, LY294002, during SILI.

CONCLUSION

These results suggest that TSLP can improve liver injury caused by sepsis and its specific mechanism may be related to inducing autophagy through the PI3K/Akt/STAT3 signaling pathway.

Near-Infrared Photoacoustic Probe for Reversible Imaging of the ClO-/GSH Redox Cycle In Vivo

Homeostasis of the cellular redox status plays an indispensable role in diverse physiological and pathological processes. Hypochlorite anion (ClO^-) and glutathione (GSH) represent an important redox couple to reflect the redox status in living cells. The current cellular redox probes that detect either ClO^- or GSH alone are not accurate enough to monitor the real redox status. In this work, a reversible photoacoustic (PA) probe, DiOH-BDP, has been synthesized and applied for PA imaging to monitor the ClO^-/GSH couple redox state in an acute liver injury (ALI) model. The near-infrared PA probe DiOH-BDP features significant changes in absorption between 648 and 795 nm during the selective oxidation by ClO^- and the reductive recovery of GSH, which exhibits excellent selectivity and sensitivity toward ClO^- and GSH with the limits of detection of 77.7 nM and 7.2 μM, respectively. Additionally, using PA₇₇₀ as a detection signal allows for the in situ monitoring of the ClO^-/GSH couple, which realizes mapping of the localized redox status of the ALI by the virtue of a PA imaging system. Therefore, the probe provides a potentially technical tool to understand redox imbalance-related pathological formation processes.

RETRACTED: MicroRNA-375-3p in endothelial progenitor cells-derived extracellular vesicles relieves myocardial injury in septic rats via BRD4-mediated PI3K/AKT signaling pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figs. 1E, 4A+F, 5A+B and Supplementary Fig. 1O+P, which appear to have the same eyebrow shaped phenotype as many other publications tabulated here (https://docs.google.com/spreadsheets/d/149EjFXVxpwkBXYJOnOHb6RhAqT4a2llhj9LM60MBffM/edit#gid=0 [docs.google.com]). The journal requested the corresponding author comment on these concerns and provide the raw data. However, the authors were not responsive to the request for comment. Since original data could not be provided, the overall validity of the results could not be confirmed. Therefore, the Editor-in-Chief decided to retract the article.

Glycogen Synthase Kinase 3β Modulates the Inflammatory Response Activated by Bacteria, Viruses, and Parasites

Knowledge of glycogen synthase kinase 3β (GSK3β) activity and the molecules identified that regulate its function in infections caused by pathogenic microorganisms is crucial to understanding how the intensity of the inflammatory response can be controlled in the course of infections. In recent years many reports have described small molecular weight synthetic and natural compounds, proteins, and interference RNA with the potential to regulate the GSK3β activity and reduce the deleterious effects of the inflammatory response. Our goal in this review is to summarize the most recent advances on the role of GSK3β in the inflammatory response caused by bacteria, bacterial virulence factors (i.e. LPS and others), viruses, and parasites and how the regulation of its activity, mainly its inhibition by different type of molecules, modulates the inflammation.

NLRX1 knockout aggravates lipopolysaccharide (LPS)-induced heart injury and attenuates the anti-LPS cardioprotective effect of CYP2J2/11,12-EET by enhancing activation of NF-κB and NLRP3 inflammasome

NLRX1 weakens lipopolysaccharide (LPS)-induced NF-κB activation on immune cells. Cytochrome P450 epoxygenase 2J2 (CYP2J2) attenuates LPS-induced cardiac injury by inhibiting NF-κB activation. However, it is still unclear whether NLRX1 could reduce LPS-induced heart damage and whether it is involved in the anti-LPS cardioprotective effect of CYP2J2. In this study, we found that NLRX1 knockout further exacerbated LPS-induced heart injury and up-regulated the proinflammatory cytokines in serum and heart tissue, and weakened the inhibitory effect of CYP2J2 on the harmful effects caused by LPS. We also found that LPS treatment induced ubiquitination of NLRX1 and promoted its binding to IKKα/β in myocardial tissue, which should theoretically inhibit NF-κB activation. However, LPS eventually leads to activation of NF-κB and NLRP3 inflammasome. Under the action of LPS, CYP2J2 further promoted the ubiquitination of NLRX1 and its binding to IKKα/β, impaired NF-κB activation and NLRP3 inflammasome activation. NLRX1 knockout notably aggravated LPS-induced NF-κB activation and NLRP3 inflammasome activation, and attenuated the inhibitory effects of CYP2J2 on NF-κB signal and NLRP3 inflammasome. More, CYP2J2 reduced LPS-induced reactive oxygen species (ROS) production and mitochondrial depolarization in heart cells, thereby inhibiting NLRP3 inflammasome activation. NLRX1 knockdown aggravated mitochondrial depolarization induced by LPS and weakened the protective effect of CYP2J2 on mitochondrial potential, although it had no significant effect on reactive oxygen species production. Together, these findings demonstrated that NLRX1 knockout aggravated LPS-induced heart injury and weakened the anti-LPS cardioprotective effect of CYP2J2 by enhancing activation of NF-κB and NLRP3 inflammasome.

Higher Epoxyeicosatrienoic Acids in Cardiomyocytes-Specific CYP2J2 Transgenic Mice Are Associated with Improved Myocardial Remodeling

Elevated cis-epoxyeicosatrienoic acids (EETs) are known to be cardioprotective during ischemia-reperfusion injury in cardiomyocyte-specific overexpressing cytochrome P450 2J2 (CYP2J2) transgenic (Tr) mice. Using the same Tr mice, we measured changes in cardiac and erythrocyte membranes EETs following myocardial infarction (MI) to determine if they can serve as reporters for cardiac events. Cardiac function was also assessed in Tr vs. wild-type (WT) mice in correlation with EET changes two weeks following MI. Tr mice (N = 25, 16 female, nine male) had significantly higher cardiac cis- and trans-EETs compared to their WT counterparts (N = 25, 18 female, seven male). Total cardiac cis-EETs in Tr mice were positively correlated with total cis-EETs in erythrocyte membrane, but there was no correlation with trans-EETs or in WT mice. Following MI, cis- and trans-EETs were elevated in the erythrocyte membrane and cardiac tissue in Tr mice, accounting for the improved cardiac outcomes observed. Tr mice showed significantly better myocardial remodeling following MI, evidenced by higher % fractional shortening, smaller infarct size, lower reactive oxygen species (ROS) formation, reduced fibrosis and apoptosis, and lower pulmonary edema. A positive correlation between total cardiac cis-EETs and total erythrocyte membrane cis-EETs in a Tr mouse model suggests that erythrocyte cis-EETs may be used as predictive markers for cardiac events. All cis-EET regioisomers displayed similar trends following acute MI; however, the magnitude of change for each regioisomer was markedly different, warranting measurement of each individually.

Alpha-lipoic acid inhibits lung cancer growth via mTOR-mediated autophagy inhibition

Lung cancer is the leading cause of cancer‐related death, and there remains a need for novel therapies for this malignancy. Here, we examined the effects of alpha‐lipoic acid (LA), a drug used for treating human diabetic complications, on lung cancer growth. We report that LA limited lung cancer growth in xenograft mice and reduced lung cancer A549 cell viability. We observed autophagy activation in human lung cancers, and report that LA inactivated autophagy in A549 cells. In addition, LA activated mammalian target of rapamycin (mTOR)/p70S6K signaling. Inhibition of mTOR with rapamycin reversed LA‐induced inactivation of autophagy and abolished LA‐induced suppression of A549 cell viability. Altogether, the data suggest that LA exerts an anti‐lung cancer effect through mTOR‐mediated inhibition of autophagy, and thus LA may have therapeutic potential for lung cancer management.

Resveratrol Protects the Myocardium in Sepsis by Activating the Phosphatidylinositol 3-Kinases (PI3K)/AKT/Mammalian Target of Rapamycin (mTOR) Pathway and Inhibiting the Nuclear Factor-κB (NF-κB) Signaling Pathway

Background

Sepsis combined with myocardial injury is an important cause of septic shock and multiple organ failure. However, the molecular mechanism of sepsis-induced myocardial dysfunction has not yet been thoroughly studied. Resveratrol has been an important research topic due its organ-protection function, but the specific mechanism is unclear. The purpose of this study was to explore the mechanism of organ injury in sepsis and to investigate the molecular mechanism of resveratrol in myocardial protection in sepsis.

Material/Methods

A classical Sprague-Dawley rat model of sepsis peritonitis was constructed for further experiments. The PI3K inhibitor LY294002 and resveratrol were used to intervene in a rat model of cardiomyopathy. HE staining was used to observe pathological changes. Cardiomyocyte apoptosis was detected by TUNEL assay. Western blot analysis was used to detect the level of maker proteins.

Results

The PI3K inhibitors could promote cardiac abnormalities and apoptosis, but resveratrol showed the opposite effect. The upregulation function of the PI3K inhibitor on the expression of NF-κB, IL-6, IL-1β, and TLR4 in LPS rats was not obvious, but the expression of TNF-α in LPS+LY294002 rats was increased by 22.85% compared with that in LPS rats (P<0.05). Compared with the LPS group, the expression of NF-κB, TNF-α, IL-6, IL-1β, and TLR4 in the LPS+resveratrol group was decreased. The expression of p-PI3K, p-AKT, and p-mTOR in LPS+LY294002 was reduced. The expression p-PI3K, p-AKT, and p-mTOR in the myocardium of the LPS+resveratrol group was increased.

Conclusions

Resveratrol can protect the myocardium in sepsis by activating the PI3K/AKT/mTOR signaling pathway and inhibiting the NF-κB signaling pathway and related inflammatory factors.

Autophagy Enhancing Contributes to the Organ Protective Effect of Alpha-Lipoic Acid in Septic Rats

Alpha-lipoic acid (ALA) reportedly has protective effects against sepsis, which is a leading cause of mortality worldwide and is associated with multiple organ dysfunction. The present study aimed to investigate further the possible action mechanisms of ALA. Male Sprague-Dawley rats were subjected to cecal ligation and puncture (CLP) in order to establish a sepsis model. The rats received an oral gavage of 200 mg/kg ALA or saline immediately after surgery. The heart rate (HR), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP) and maximum rising and lowering rates of left ventricular pressure (±dp/dt) were examined for assessing the cardiac function. Blood urea nitrogen (BUN) and serum creatinine levels were assessed for evaluating renal function. Neutrophil gelatinase-associated lipocalin (NAGL) was examined for reflecting acute renal injury. Histopathological alterations of the small intestine were examined by hematoxylin-eosin staining. The ultrastructure of the small intestine and kidney was observed under electron microscopy. The levels of autophagy- and inflammation-associated proteins were determined via western blot analysis. The binding of nuclear factor-kappa B (NF-κB) to DNA was tested via an electrophoretic mobility shift assay. Cell apoptosis was examined using TUNEL staining. ALA treatment improved the survival rate, restored the loss of body weight and pro-inflammatory cytokines production in the serum of CLP-induced septic rats. ALA improved the cardiac and renal functions, downregulated the expression levels of interleukin-1β, tumor necrosis factor-α, and inducible nitric oxide synthase in the myocardium and small intestine of septic rats. ALA treatment also inactivated the NF-κB signaling pathway in the small intestine. An examination of autophagy showed that ALA increased the LC3II/I ratio, upregulated Atg5, Atg7, and beclin-1 and downregulated p62 protein levels in the myocardium, kidney, and small intestine of septic rats, and further promoted autophagosome accumulation in the kidney and small intestine. In addition, ALA could also reduce cell apoptosis in myocardium, kidney and small intestine tissues. These effects can be completely or party inhibited by 3-MA. Our findings suggest that autophagy enhancing may contribute to the organ protective effect of ALA in septic rats.

The effect of alpha-lipoic acid on expression of VCAM-1 in type 2 diabetic rat

Macrovascular diabetes complications are generally caused by a process called atherosclerosis. Evidences suggest that to initiate atherosclerosis, oxidated low-density lipoprotein (oxLDL) has to promote the expression of adhesion molecule. Several studies have evidenced the relevance of oxidative stress and atherosclerosis. However, the protective effect of alpha-lipoic acid (ALA) at atherosclerosis still needs to be explored. This study is aimed at investigating the concentration of plasma oxLDL and the expression of adhesion molecule of type 2 diabetes mellitus (DM) using rat model. Eighteen male rats were segregated into three groups labeled as control group, DM group and DM+ALA group. Type 2 diabetes was induced by intraperitoneal injection of streptozotocin (50 mg/kg) followed by nicotinamide (110 mg/kg). ALA was administered at a dose of 60 mg/kg body weight/day throughout the feeding period of 3 weeks. Plasma oxLDL concentration was measured by enzyme-linked immunosorbent assays and expression of vascular cell adhesion molecule-1 (VCAM-1) was measured by immunohistochemistry. Expression of abdominal aortic adhesion molecule was assessed by calculation with Adobe Photoshop CS3. Analysis of variance test was used to compare the concentration of plasma oxLDL and expression of adhesion molecule. A P-value of 0.05 was considered statistically significant. Plasma oxLDL was lower in diabetic rat+ALA compared with the diabetic rat. Percentage of area VCAM-1 in DM+ALA group was lower than DM group. There were no significant differences between groups in intensity of VCAM-1. In conclusion, ALA showed protective effects against early atherosclerosis in diabetic rats.

Tid1-S attenuates LPS-induced cardiac hypertrophy and apoptosis through ER-a mediated modulation of p-PI3K/p-Akt signaling cascade

Myocardial dysfunction is clinically relevant? repercussion that follows sepsis. Tid 1 protein has been implicated in many biological process. However, the role of Tid 1 in lipopolysaccharide (LPS)-induced cardiomyocyte hypertrophy and apoptosis remains elusive. In the current research endeavor, we have elucidated the role of Tid1-S on LPS-induced cardiac hypertrophy and apoptosis. Interestingly, we found that overexpression of Tid1-S suppressed TLR-4, NFATc3, and BNP protein expression which eventually led to inhibition of LPS-induced cardiac hypertrophy. Moreover, Tid1-S overexpression attenuated cellular apoptosis and activated survival proteins p-PI3K and p^ser473 Akt. Besides this, Tid1-S overexpression enhanced ER-a protein expression. Collectively, our data suggest that Tid1-S plausibly enhance ER-a protein and further activate p-PI3K and p ^ser473 Akt survival protein expression; which thereby led to attenuation of LPS-induced apoptosis in cardiomyoblast cells. Interestingly, our data suggest that Tid1-S is involved in attenuation of cardiomyoblast cells damages induced by LPS.

The Immunomodulatory Effect of Alpha-Lipoic Acid in Autoimmune Diseases

Αlpha-lipoic acid is a naturally occurring antioxidant in human body and has been widely used as an antioxidant clinically. Accumulating evidences suggested that α-lipoic acid might have immunomodulatory effects on both adaptive and innate immune systems. This review focuses on the evidences and potential targets involved in the immunomodulatory effects of α-lipoic acid. It highlights the fact that α-lipoic acid may have beneficial effects in autoimmune diseases once the immunomodulatory effects can be confirmed by further investigation.

Phenylephrine Attenuated Sepsis-Induced Cardiac Inflammation and Mitochondrial Injury Through an Effect on the PI3K/Akt Signaling Pathway

OBJECTIVE

To investigate whether phenylephrine (PE) inhibits sepsis-induced cardiac dysfunction, cardiac inflammation, and mitochondrial injury through the PI3K/Akt signaling pathway.

METHODS

A rat model of sepsis was established by cecal ligation and puncture. PE and/or wortmannin (a PI3K inhibitor) were administered to investigate the role of PI3K/Akt signaling in mediating the effects of PE on inhibiting sepsis-induced cardiac dysfunction, cardiac inflammation, and mitochondrial injury. Hematoxylin-eosin staining, echocardiography, and Langendorff system were used to examine the myocardial injury and function. The concentrations of TNF-α and IL-6 were analyzed by enzyme-linked immunosorbent assay. Intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), myeloperoxidase, mitochondria-related fusion/fission proteins, and PI3K/Akt signaling pathway-associated proteins were analyzed by Western blotting.

RESULTS

PE improved the cardiac function and survival in septic rats. PE decreased TNF-α, IL-6, ICAM-1, VCAM-1, and myeloperoxidase contents in the myocardium of septic rats. Meanwhile, PE increased the fusion-related proteins and decreased the fission-related proteins in the myocardial mitochondria of septic rats. On the other hand, PE activated the PI3K/Akt signaling pathway in the cecal ligation and puncture-treated rats, and all the protective effects of PE were abolished by wortmannin.

CONCLUSIONS

PE attenuated sepsis-induced cardiac dysfunction, cardiac inflammation, and mitochondrial injury through the PI3K/Akt signaling pathway.

Nitrite administration improves sepsis-induced myocardial and mitochondrial dysfunction by modulating stress signal responses

PURPOSE

A specific therapeutic strategy in sepsis-induced myocardial dysfunction remains to be determined. Nitrite may have cardioprotective effects against sepsis-induced myocardial dysfunction. This study investigated the cardioprotective effects of nitrite on myocardial function, mitochondrial bioenergetics, and its underlying molecular mechanisms in severe septic rats.

METHODS

Sepsis was induced in male Wistar rats by cecal ligation and puncture (CLP). After CLP, we administered normal saline (NS group) or nitrite (nitrite group) subcutaneously. We administered nitrite at different doses (0.1-10 mg/kg) to ascertain the most effective dose and examined cardiac function in an isolated heart experiment 8 h after CLP. We investigated mitochondrial bioenergetics and molecular mechanisms underlying the administration of nitrite in vitro.

RESULTS

In isolated heart experiments, the left ventricular developed pressure (96 ± 5 mmHg) at a moderate nitrite dose (1.0 mg/kg) was significantly higher than that in the NS group (75 ± 4 mmHg, P < 0.05). Mitochondrial oxidative phosphorylation in the nitrite group was significantly higher than that in the NS group (P < 0.01). Immunoblotting revealed that nitrite significantly increased the phosphorylation of Akt (P < 0.05) and reduced the nuclear translocation of NF-κB (P < 0.05) compared with the NS group. Nitrite was also shown to improve the rate of survival in severe septic rats (P < 0.001).

CONCLUSIONS

Our results showed that a moderate nitrite dose improved septic myocardial dysfunction at organ, cellular, and molecular levels via modulation of stress signal responses, which resulted in an improvement in survival.

Neuroglobin Protects Rats from Sepsis-Associated Encephalopathy via a PI3K/Akt/Bax-Dependent Mechanism

Sepsis-associated encephalopathy (SAE) is a common complication of sepsis, and has no generally accepted treatment due to its complicated pathophysiology. Previously, we demonstrated the protective role of neuroglobin (Ngb) in SAE rats, but the exact mechanism has not been determined. To investigate the potential neuroprotective roles and mechanisms of Ngb, Sprague-Dawley rats were used. Overexpression of Ngb via intracerebroventricular injection with Ngb plasmids attenuated brain damage assessed by hematoxylin and eosin (HE) staining and neurological dysfunction assessed by Morris water maze test. Western blot analysis also showed that the phosphorylation of Akt increased and the protein level of Bax decreased. Furthermore, the protective effect can be abolished by PI3K/Akt pathway inhibitor LY294002. Our results demonstrate that Ngb can protect rats from SAE via a PI3K/Akt/Bax-dependent mechanism.

Interleukin-18 gene deletion protects against sepsis-induced cardiac dysfunction by inhibiting PP2A activity

BACKGROUND

Interleukin-18 (IL-18) neutralization protects against lipopolysaccharide (LPS)-induced injuries, including myocardial dysfunction. However, the mechanism is yet to be fully elucidated. The aim of the present study was to determine whether IL-18 gene deletion prevents sepsis-induced cardiac dysfunction and to elucidate the potential mechanisms underlying IL-18-mediated cardiotoxicity by LPS.

METHODS AND RESULTS

Ten-week-old male wild-type (WT) and IL-18 knockout (IL-18 KO) mice were intraperitoneally administered LPS. Serial echocardiography showed better systolic pump function and less left ventricular (LV) dilatation in LPS-treated IL-18 KO mice compared with those in LPS-treated WT mice. LPS treatment significantly decreased the levels of phospholamban (PLN) and Akt phosphorylation in WT mice compared with those in saline-treated WT mice, while the LPS-induced decrease in the phosphorylation levels was attenuated in IL-18 KO mice compared with that in WT mice. IL-18 gene deletion also attenuated an LPS-induced increase of type 2 protein phosphatase 2A (PP2A) activity, a molecule that dephosphorylates PLN and Akt. There was no difference in type 1 protein phosphatase (PP1) activity. To address whether IL-18 affects PLN and Akt phosphorylation via PP2A activation in cardiomyocytes, rat neonatal cardiac myocytes were cultured and stimulated using 100ng/ml of recombinant rat IL-18. Exogenous IL-18 decreased the level of PLN and Akt phosphorylation in cardiomyocytes. PP2A activity but not PP1 activity was increased by IL-18 stimulation in cardiomyocytes.

CONCLUSIONS

IL-18 plays a pivotal role in advancing sepsis-induced cardiac dysfunction, and the mechanisms underlying IL-18-mediated cardiotoxicity potentially involve the regulation of PLN and Akt phosphorylation through PP2A activity.

Downregulation of PI3K-γ in a mouse model of sepsis-induced myocardial dysfunction

A key component during sepsis is the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway, of which the PI3K-γ isoform is a major regulator in many inflammatory responses. However, the role of PI3K-γ in the development of sepsis-induced myocardial dysfunction (SIMD) is unknown. In this study, we established a model of SIMD induced by lipopolysaccharide (LPS), subsequently used the selective inhibitor LY294002 and AS605240 to block the effect of PI3K and PI3K-γ, respectively. Cardiac function was evaluated by echocardiography, hearts were obtained for histological and protein expression examinations. ELISA was used to measure the serum levels of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), cardiac troponin I (cTnI) and heart-type fatty acid binding protein (H-FABP). LPS-treated mice showed an increase to cardiac inflammation, myocardial damage and production of TNF-α, IL-6, NF-κB, cTnI and H-FABP. Administration of AS605240 to LPS-treated mice reduced some patho-physiological characteristics of SIMD and reduced TNF-α, IL-6, cTnI and H-FABP production. However, administration of LY294002 did not improve those same conditions. The results showed that PI3K-γ is likely a crucial element in SIMD by regulating the PI3K/Akt pathway, and become a new marker of myocardial injury. Inhibition of PI3K-γ might be a potential therapeutic target in SIMD.

Excavatolide B Modulates the Electrophysiological Characteristics and Calcium Homeostasis of Atrial Myocytes

Severe bacterial infections caused by sepsis always result in profound physiological changes, including fever, hypotension, arrhythmia, necrosis of tissue, systemic multi-organ dysfunction, and finally death. The lipopolysaccharide (LPS) provokes an inflammatory response under sepsis, which may increase propensity to arrhythmogenesis. Excavatolide B (EXCB) possesses potent anti-inflammatory effects. However, it is not clear whether EXCB could modulate the electrophysiological characteristics and calcium homeostasis of atrial myocytes. This study investigated the effects of EXCB on the atrial myocytes exposed to lipopolysaccharide. A whole-cell patch clamp and indo-1 fluorimetric ratio technique was employed to record the action potential (AP), ionic currents, and intracellular calcium ([Ca²⁺]_i) in single, isolated rabbit left atrial (LA) cardiomyocytes, with and without LPS (1 μg/mL) and LPS + EXCB administration (10 μM) for 6 ± 1 h, in order to investigate the role of EXCB on atrial electrophysiology. In the presence of LPS, EXCB-treated LA myocytes (n = 13) had a longer AP duration at 20% (29 ± 2 vs. 20 ± 2 ms, p < 0.05), 50% (52 ± 4 vs. 40 ± 3 ms, p < 0.05), and 90% (85 ± 5 vs. 68 ± 3 ms, p < 0.05), compared to the LPS-treated cells (n = 12). LPS-treated LA myocytes showed a higher late sodium current, Na⁺/Ca²⁺ exchanger current, transient outward current, and delayed rectifier potassium current, but a lower l-type Ca²⁺ current, than the control LA myocytes. Treatment with EXCB reversed the LPS-induced alterations of the ionic currents. LPS-treated, EXCB-treated, and control LA myocytes exhibited similar Na⁺ currents. In addition, the LPS-treated LA myocytes exhibited a lower [Ca²⁺]_i content and higher sarcoplasmic reticulum calcium content, than the controls. EXCB reversed the LPS-induced calcium alterations. In conclusion, EXCB modulates LPS-induced LA electrophysiological characteristics and calcium homeostasis, which may contribute to attenuating LPS-induced arrhythmogenesis.

Kolaviron, a biflavonoid of Garcinia kola seed mitigates ischemic/reperfusion injury by modulation of pro-survival and apoptotic signaling pathways

Objective:

The study was designed to investigate the ameliorative effect of Kolaviron (KV) on ischemic/reperfusion injury in experimental animal models.

Materials and Methods:

Male Wistar rats were randomly divided into two groups: Group 1 received corn oil as a vehicle and rats in Group 2 were administered KV at 200 mg/kg for 4 weeks. The rats were fed with rat standard chow pellet and water administered ad libitum. After 4 weeks of KV administration, hearts were excised and mounted on the working heart perfusion system. Western blot analysis for protein expression was carried out on frozen heart samples.

Results:

There was significant (P < 0.05) reduction in the activity of catalase, superoxide dismutase, and glutathione peroxidase with concomitant reduction in oxygen radical absorbance capacity in ischemic rat heart of control compared to group pre-treated with KV, respectively. Similarly, intracellular reactive oxygen species and malondialdehyde were significantly elevated in control compared to KV pre-treated rats. KV significantly increased total Akt/protein kinase B (PKB), phosphorylated Akt/PKB at serine 473 and also caused a significant reduction in p38 mitogen-activated protein kinase, Caspase 3, and cleaved poly adenosine diphosphate ribose polymerase.

Conclusion:

Taken together, KV offered significant cardioprotection via free radical scavenging activity and upregulation of pro-survival pathway.

Cardiac dysfunction, mitochondrial architecture, energy production, and inflammatory pathways: Interrelated aspects in endotoxemia and sepsis

Septic patients with myocardial dysfunction have a 3-fold increase in mortality compared with patients without cardiovascular impairment, and usually show myocarditis, disruption of the contractile apparatus, increased amounts of interstitial collagen, and damaged mitochondria. The presence of nitric oxide and cytokines in cardiac tissue constitute the molecular markers and the intracellular messengers of inflammatory conditions in the heart due to the onset of sepsis and endotoxemia, derived from the nuclear factor-κB pathway activation and proinflammatory gene transcription. Sepsis occurs with an exacerbated inflammatory response that damages tissue mitochondria and impaired bioenergetic processes. The heart consumes 20-30 times its own weight in adenosine triphosphate every day, and 90% of this molecule is derived from mitochondrial oxidative phosphorylation. Cardiac energy management is comprised in sepsis and endotoxemia; both a deficit in energy production and alterations in the source of energy substrates are believed to be involved in impaired cardiac function. Although several hypotheses try to explain the molecular mechanisms underlying the complex condition of sepsis and endotoxemia, the current view is that these syndromes are the result of an intricate balance between prevailing levels of mitochondrial stress, biogenesis/autophagy signaling and mitochondria quality control processes, rather on a single factor. The aim of this review is to discuss current hypothesis of cardiac dysfunction related to energy metabolism and mitochondrial function in experimental models of sepsis and endotoxemia, and to introduce the importance of lipids (mainly cardiolipin) in the mechanism of cardiac energy mismanagement in these inflammatory conditions.

α-Lipoic Acids Promote the Protein Synthesis of C2C12 Myotubes by the TLR2/PI3K Signaling Pathway

Skeletal muscle protein turnover is regulated by endocrine hormones, nutrients, and inflammation. α-Lipoic acid (ALA) plays an important role in energy homeostasis. Therefore, the aim of this study was to investigate the effects of ALA on protein synthesis in skeletal muscles and reveal the underlying mechanism. ALA (25 μM) significantly increased the protein synthesis and phosphorylation of Akt, mTOR, and S6 in C2C12 myotubes with attenuated phosphorylation of AMPK, Ikkα/β, and eIF2α. Intraperitoneal injection of 50 mg/kg ALA also produced the same results in mouse gastrocnemius. Both the PI3K (LY294002) and mTOR (rapamycin) inhibitors abolished the effects of ALA on protein synthesis in the C2C12 myotubes. However, AICAR (AMPK agonist) failed to block the activation of mTOR and S6 by ALA. ALA increased TLR2 and MyD88 mRNA expression in the C2C12 myotubes. TLR2 knockdown by siRNA almost eliminated the effects of ALA on protein synthesis and the Akt/mTOR pathway in the C2C12 myotubes. Immunoprecipitation data showed that ALA enhanced the p85 subunit of PI3K binding to MyD88. These findings indicate that ALA induces protein synthesis and the PI3K/Akt signaling pathway by TLR2.

In Search of a Cure for Sepsis: Taming the Monster in Critical Care Medicine

In spite of over half a century of research, sepsis still constitutes a major problem in health care delivery. Although advances in research have significantly increased our knowledge of the pathogenesis of sepsis and resulted in better prognosis and improved survival outcome, sepsis still remains a major challenge in modern medicine with an increase in occurrence predicted and a huge socioeconomic burden. It is generally accepted that sepsis is due to an initial hyperinflammatory response. However, numerous efforts aimed at targeting the proinflammatory cytokine network have been largely unsuccessful and the search for novel potential therapeutic targets continues. Recent studies provide compelling evidence that dysregulated anti-inflammatory responses may also contribute to sepsis mortality. Our previous studies on the role of regulatory T cells and phosphoinositide 3-kinases in sepsis highlight immunological approaches that could be explored for sepsis therapy. In this article, we review the current and emerging concepts in sepsis, highlight novel potential therapeutic targets and immunological approaches for sepsis treatment and propose a biphasic treatment approach for management of the condition.

Alpha-lipoic acid prevents endotoxic shock and multiple organ dysfunction syndrome induced by endotoxemia in rats

Alpha-lipoic acid (ALA), a naturally occurring disulfide derivative of octanoic acid, serves as a strong antioxidant and has been reported to possess anti-inflammatory effects. The aim of the present study is to investigate the preventive and therapeutic effects of ALA on multiple organ dysfunction syndrome (MODS) caused by endotoxemia in rats. Male Wistar rats were intravenously infused with lipopolysaccharide (LPS) (10 mg/kg) to induce endotoxemia. Alpha-lipoic acid 10, 20, or 40 mg/kg was administered intravenously 60 min before (pretreatment) LPS challenge, and ALA 40 mg/kg was administered intravenously 30 min after (posttreatment) LPS challenge. Pretreatment and posttreatment with ALA significantly improved the deleterious hemodynamic changes 8 h after LPS challenge, including hypotension and bradycardia. Alpha-lipoic acid reduced the plasma levels of glutamic pyruvic transaminase, blood urea nitrogen, lactate dehydrogenase, tumor necrosis factor-α, nitric oxide metabolites, and thrombin-antithrombin complex, which increased markedly after LPS challenge. The induction of inducible nitric oxide synthase both in the liver and the lung and vascular superoxide anion production were also significantly suppressed by ALA. Moreover, ALA significantly attenuated LPS-induced caspase-3 activation in cardiomyocytes and improved survival rate. In conclusion, ALA effectively attenuated LPS-induced acute inflammatory response and improved MODS. The antioxidant and anti-inflammatory effects of ALA may contribute to these beneficial effects. Alpha-lipoic acid might be considered as a novel therapeutic strategy in the prevention of sepsis-induced MODS and inflammatory vascular diseases.

Protective effects of ginsenoside Re on lipopolysaccharide-induced cardiac dysfunction in mice

Ginsenoside Re protected against lipopolysaccharide-induced cardiac dysfunction in miceviaERs and PI3K/AKT mediated NFκB inhibition.

Melatonin attenuates sepsis-induced cardiac dysfunction via a PI3K/Akt-dependent mechanism

Myocardial dysfunction is an important manifestation of sepsis. Previous studies suggest that melatonin is protective against sepsis. In addition, activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway has been reported to be beneficial in sepsis. However, the role of PI3K/Akt signaling in the protective effect of melatonin against sepsis-induced myocardial dysfunction remains unclear. Here, LY294002, a PI3K inhibitor, was used to investigate the role of PI3K/Akt signaling in mediating the effects of melatonin on sepsis-induced myocardial injury. Cecal ligation and puncture (CLP) surgery was used to establish a rat model of sepsis. Melatonin was administrated to rats intraperitoneally (30 mg/kg). The survival rate, measures of myocardial injury and cardiac performance, serum lactate dehydrogenase level, inflammatory cytokine levels, oxidative stress level, and the extent of myocardial apoptosis were assessed. The results suggest that melatonin administration after CLP surgery improved survival rates and cardiac function, attenuated myocardial injury and apoptosis, and decreased the serum lactate dehydrogenase level. Melatonin decreased the production of the inflammatory cytokines TNF-α, IL-1β, and HMGB1, increased anti-oxidant enzyme activity, and decreased the expression of markers of oxidative damage. Levels of phosphorylated Akt (p-Akt), unphosphorylated Akt (Akt), Bcl-2, and Bax were measured by Western blot. Melatonin increased p-Akt levels, which suggests Akt pathway activation. Melatonin induced higher Bcl-2 expression and lower Bax expression, suggesting inhibition of apoptosis. All protective effects of melatonin were abolished by LY294002, the PI3K inhibitor. In conclusion, our results demonstrate that melatonin mitigates myocardial injury in sepsis via PI3K/Akt signaling activation.

Lipoic acid protects dopaminergic neurons in LPS-induced Parkinson's disease model

Parkinson's disease (PD) is a chronic neurodegenerative disease of the central nervous system (CNS), characterized by a loss of dopaminergic neurons, which is thought to be caused by both genetic and environmental factors. Recent findings suggest that neuroinflammation may be a pathogenic factor in the onset and progression of sporadic PD. Here we explore the potential therapeutic effect of lipoic acid (LA) on a lipolysaccharide (LPS)-induced inflammatory PD model. Our results for the first time showed that LA administration improved motor dysfunction, protected dopaminergic neurons loss, and decreased α-synuclein accumulation in the substantia nigra (SN) area of brain. Further, LA inhibited the activation of nuclear factor-κB (NF-κB) and expression of pro-inflammatory molecules in M1 microglia. Taken together, these results suggest that LA may exert a profound neuroprotective effect and is thus a promising anti-neuroinflammatory and anti-oxidative agent for halting the progression of PD. Interventions aimed at either blocking microglia-derived inflammatory mediators or modulating the polarization of microglia may be potentially useful therapies that are worth further investigation.

Lipopolysaccharide directly stimulates Th17 differentiation in vitro modulating phosphorylation of RelB and NF-κB1

Toll-like receptors (TLRs) recognize a wide range of pathogen-associated molecular patterns (PAMP) and are preferentially expressed in innate immune cells. TLR-mediated activation of these cells activates the adaptive immune system. However, it has become clear that TLRs are not only expressed but also functionally active in CD4 T cells. The intestines are continuously exposed to TLR ligands, including lipopolysaccharide (LPS), a TLR4 ligand, and TLR4 is expressed higher in Th17 cells than Th1 and Th2 cells. In addition, development of Th17 cells in the gut mucosa is more dependent on gut microbiota than Th1, Th2, and Treg. Thus, we examined whether LPS directly regulates Th17 differentiation. LPS directly stimulated Th17 differentiation in vitro. In Th17 cells, LPS increased phosphorylation of NF-κB1, resulting in an increase of p50, the processed form of NF-κB1, whereas it decreased phosphorylation of RelB, leading to the up-regulation of RelB. Subcutaneous injection of LPS increased the frequency of IL-17 producing cells in inguinal lymph nodes, worsening experimental autoimmune encephalomyelitis (EAE). Additionally, expression of TLR1, TLR2, TLR4, and TLR5 was reduced upon T cell activation and LPS showed modest effect on TLR4 expression. These findings provide the first evidence that TLR4 activation directly regulate Th17 differentiation.

Significant in vivo anti-inflammatory activity of Pytren4Q-Mn a superoxide dismutase 2 (SOD2) mimetic scorpiand-like Mn (II) complex

Background

The clinical use of purified SOD enzymes has strong limitations due to their large molecular size, high production cost and immunogenicity. These limitations could be compensated by using instead synthetic SOD mimetic compounds of low molecular weight.

Background/Methodology

We have recently reported that two SOD mimetic compounds, the Mn^II complexes of the polyamines Pytren2Q and Pytren4Q, displayed high antioxidant activity in bacteria and yeast. Since frequently molecules with antioxidant properties or free-radical scavengers also have anti-inflammatory properties we have assessed the anti-inflammatory potential of Pytren2Q and Pytren4Q Mn^II complexes, in cultured macrophages and in a murine model of inflammation, by measuring the degree of protection they could provide against the cellular injury produced by lipopolisacharide, a bacterial endotoxin.

Principal Findings

In this report we show that the Mn^II complex of Pytren4Q but not that of Pytren2Q effectively protected human cultured THP-1 macrophages and whole mice from the inflammatory effects produced by LPS. These results obtained with two molecules that are isomers highlight the importance of gathering experimental data from animal models of disease in assessing the potential of candidate molecules.

Conclusion/Significance

The effective anti-inflammatory activity of the Mn^II complex of Pytren4Q in addition to its low toxicity, water solubility and ease of production would suggest it is worth taking into consideration for future pharmacological studies.

α-Lipoic acid protected cardiomyoblasts from the injury induced by sodium nitroprusside through ROS-mediated Akt/Gsk-3β activation

It has been long noted that cardiac cell apoptosis provoked by excessive production of nitric oxide (NO) plays important roles in the pathogenesis of variant cardiac diseases. Attenuation of NO-induced injury would be an alternative therapeutic approach for the development of cardiac disorders. This study investigated the effects of α-lipoic acid (LA) on the injury induced by sodium nitroprusside (SNP), a widely used NO donor, in rat cardiomyoblast H9c2 cells. SNP challenge significantly decreased cell viability and increased apoptosis, as evidenced by morphological abnormalities, nuclear condensation and decline of mitochondrial potential (ΔΨm). These changes induced by SNP were significantly attenuated by LA pretreatment. Furthermore, LA pretreatment prevented the SNP-triggered suppression of Akt and Gsk-3β activation. Blockade of Akt activation with triciribin (API) completely abolished the cytoprotection of LA against SNP challenge. In addition, LA moderately increased intracellular ROS production. Interestingly, inhibition of ROS with N-acetylcysteine abrogated Akt/Gsk-3β activation and the LA-induced cytoprotection following SNP stimulation. Taken together, the results indicate that LA protected the SNP-induced injury in cardiac H9c2 cells through, at least in part, the activation of Akt/Gsk-3β signaling in a ROS-dependent mechanism.

Alpha-lipoic acid enhances DMSO-induced cardiomyogenic differentiation of P19 cells

Alpha-lipoic acid (α-LA) is a potent antioxidant that acts as an essential cofactor in mitochondrial dehydrogenase reactions. α-LA has been shown to possess anti-inflammatory and cytoprotective properties, and is used to improve symptoms of diabetic neuropathy. However, the role of α-LA in stem cell differentiation and the underlying molecular mechanisms remain unknown. In the present study, we showed that α-LA significantly promoted dimethyl sulfoxide (DMSO)-induced cardiomyogenic differentiation of mouse embryonic carcinoma P19 cells. α-LA dose dependently increased beating embryonic body (EB) percentages of DMSO-differentiated P19 cells. The expressions of cardiac specific genes TNNT2, Nkx2.5, GATA4, MEF2C, and MLC2V and cardiac isoform of troponin T (cTnT)-positively stained cell population were significantly up-regulated by the addition of α-LA. We also demonstrated that the differentiation time after EB formation was critical for α-LA to take effect. Interestingly, without DMSO treatment, α-LA did not stimulate the cardiomyogenic differentiation of P19 cells. Further investigation indicated that collagen synthesis-enhancing activity, instead of the antioxidative property, plays a significant role in the cardiomyogenic differentiation-promoting function of α-LA. These findings highlight the potential use of α-LA for regenerative therapies in heart diseases.

Role of α-lipoic acid in LPS/d-GalN induced fulminant hepatic failure in mice: studies on oxidative stress, inflammation and apoptosis

This study investigated the protective effect of α-lipoic acid (LA) on lipopolysaccharide (LPS)/d-galactosamine (d-GalN)-induced fulminant hepatic failure in mice. First, we found that LA markedly reduced LPS/d-GalN-induced increases in serum ALT and AST activities, which were supplemented with histopathological examination, suggested that LA has a protective effect on this model of hepatic damage. Livers challenged with LPS/d-GalN exhibited extensive areas of vacuolization with the disappearance of nuclei and the loss of hepatic architecture. On the contrary, these pathological alterations were ameliorated by LA treatment. Next, we found that ROS and TBARS levels were increased in LPS/d-GalN treated liver homogenates, which were attenuated by LA administration. Consistently, decreases in hepatic CAT and GPx activities were observed in LPS/d-GalN group and were significantly restored by LA administration. Moreover, pretreatment with LA markedly reduced LPS/d-GalN-induced iNOS, COX-2, TNF-α, NF-κB, IL-1β and IL-6 expressions. Furthermore, our data showed that TUNEL-positive cells increased in LPS/d-GalN-treated mice liver which was counteracted by LA administration. LPS/d-GalN induced apoptosis of hepatocytes, as estimated by caspase 3, caspase 8 and caspase 9 activations. Also, the increasing of Bax and the decreasing of Bcl-2 expressions also supported LPS/d-GalN induced apoptosis. Interestingly, LA marked relieved these apoptotic features. Taking together, our results indicated that LA plays an important role on LPS/d-GalN-induced fulminant hepatic failure through its antioxidant, anti-inflammatory and anti-apoptotic activities.

Liver X receptor activation protects against inflammation and enhances autophagy in myocardium of neonatal mouse challenged by lipopolysaccharides

Liver X receptors (LXRs) has been emerged as negative regulators of cardiomyocytic inflammation. The cellular process of autophagy is believed to play a protective role in myocardium during the inflammatory status. In this study, we investigated the role of LXRs agonist TO901317 (TO) on lipopolysaccharides (LPS)-induced myocardial inflammation and autophagy. The results showed that TO pretreatment significantly reduced the LPS-induced infiltration of inflammatory cells, elevation of NF-κB protein, TNF-α, and IL-6 mRNA levels in the myocardium. Moreover, LPS stimulated autophagy in neonatal mice heart, and this effect was further enhanced by TO pretreatment as evidenced by increased LC3-II/GAPDH ratio increment. Furthermore, TUNEL assay revealed LPS stimulation also increased the number of apoptotic cells in the myocardium, and the increment was inhibited by TO pretreatment. Our findings suggested that attenuation of inflammation and apoptosis, and enhancement of autophagy by TO may contribute to the protection of myocardium under inflammatory condition.

Ablation of Akt2 protects against lipopolysaccharide-induced cardiac dysfunction: role of Akt ubiquitination E3 ligase TRAF6

Lipopolysaccharide (LPS), an essential component of the outer membrane of Gram-negative bacteria, plays a pivotal role in myocardial anomalies in sepsis. Recent evidence has depicted a role of Akt in LPS-induced cardiac sequelae although little information is available with regard to the contribution of Akt isoforms in the endotoxin-induced cardiac dysfunction. This study examined the effect of Akt2 knockout on LPS-induced myocardial contractile dysfunction and the underlying mechanism(s) with a focus on TNF receptor-associated factor 6 (TRAF6). Echocardiographic properties and cardiomyocyte contractile function [peak shortening (PS), maximal velocity of shortening/relengthening, time-to-PS, time-to-90% relengthening] were examined in wild-type and Akt2 knockout mice following LPS challenge (4mg/kg, 4h). LPS challenge enlarged LV end systolic diameter, reduced fractional shortening and cardiomyocyte contractile capacity, prolonged TR90, promoted apoptosis, upregulated caspase-3/-12, ubiquitin, and the ubiquitination E3 ligase TRAF6 as well as decreased mitochondrial membrane potential without affecting the levels of TNF-α, toll-like receptor 4 and the mitochondrial protein ALDH2. Although Akt2 knockout failed to affect myocardial function, apoptosis, and ubiquitination, it significantly attenuated or mitigated LPS-induced changes in cardiac contractile and mitochondrial function, apoptosis and ubiquitination but not TRAF6. LPS facilitated ubiquitination, phosphorylation of Akt, GSK3β and p38, the effect of which with the exception of p38 was ablated by Akt2 knockout. TRAF6 inhibitory peptide or RNA silencing significantly attenuated LPS-induced Akt2 ubiquitination, cardiac contractile anomalies and apoptosis. These data collectively suggested that TRAF6 may play a pivotal role in mediating LPS-induced cardiac injury via Akt2 ubiquitination.

Alpha-lipoic acid attenuates lipopolysaccharide-induced kidney injury

BACKGROUND

Kidney is one of the major target organs in sepsis, while effective prevention of septic acute kidney injury has not yet been established. α-Lipoic acid (LA) has been known to exert beneficial effects against lipopolysaccharide (LPS)-induced damages in various organs such as heart, lung, and liver. We investigated the protective effect of LA on LPS-induced kidney injury.

METHODS

Two groups of rats were treated with LPS (20 mg/kg, i.p.), one of which being co-treated with LA (50 mg/kg), while the control group was treated with vehicle alone. Human renal proximal tubular epithelial cells (HK-2 cells) were cultured with or without LPS (10 μg/ml) in the presence or absence of LA (100 μg/ml) for 3 h prior to LPS treatment.

RESULTS

Serum creatinine level was increased in LPS-treated rats, which was attenuated by LA co-treatment. LPS treatment induced cleaved caspase-3 expression in the kidney, which was counteracted by LA. Terminal deoxynucleotidyl transferase dUTP nick-end labeling-positive cells increased in the kidneys of LPS-treated rats compared with controls, which was counteracted by LA treatment. Protein expression of inducible nitric oxide synthase and cyclooxygenase-2 detected by immunoblotting and/or immunohistochemical staining, along with mRNA levels of pro-inflammatory cytokines detected by real-time polymerase chain reaction, was increased in the kidney with LPS administration, which was ameliorated with LA treatment. LA also protected LPS-induced tubular dysfunction, preserving type 3 Na(+)/H(+) exchanger and aquaporin 2 expressions in the kidney. Suppression of LPS-induced expression of cleaved caspase-3 by LA was also observed in HK-2 cells. Increased protein expression of phospho-extracellular signal-regulated kinases 1/2 and c-Jun N-terminal kinases by LPS treatment was attenuated by LA pretreatment, while p38 was not affected by either LPS or LA treatment. MitoTracker Red demonstrated LA prevented LPS-induced increment of mitochondrial oxidative stress, where concurrent 4',6-diamidino-2-phenylindole staining also revealed marked fragmentation and condensation of nuclei in HK-2 cells treated with LPS, which was prevented by LA.

CONCLUSION

LA treatment attenuates LPS-induced kidney injury, such as renal tubular dysfunction, by suppression of apoptosis, and inflammation.

Notch1 cardioprotection in myocardial ischemia/reperfusion involves reduction of oxidative/nitrative stress

Oxidative/nitrative stress plays an important role in myocardial ischemia/reperfusion (MI/R) injury. Notch1 participates in the regulation of cardiogenesis and cardiac response to hypertrophic stress, but the function of Notch1 signaling in MI/R has not been explored. This study aims to determine the role of Notch1 in MI/R, and investigate whether Notch1 confers cardioprotection. Notch1 specific small interfering RNA (siRNA, 20 μg) or Jagged1 (a Notch ligand, 12 μg) was delivered through intramyocardial injection. 48 h after injection, mice were subjected to 30 min of myocardial ischemia followed by 3 h (for cell apoptosis and oxidative/nitrative stress), 24 h (for infarct size and cardiac function), or 2 weeks (for cardiac fibrosis and function) of reperfusion. Cardiac-specific Notch1 knockdown resulted in significantly aggravated I/R injury, as evidenced by enlarged infarct size, depressed cardiac function, increased myocardial apoptosis and cardiac fibrosis. Downregulation of Notch1 increased expression of inducible NO synthase (iNOS) and gp(91phox), enhanced the production of NO metabolites and superoxide, as well as their cytotoxic reaction product peroxynitrite. Moreover, Notch1 blockade also reduced phosphorylation of endothelial NO synthase (eNOS) and Akt, and increased expression of PTEN, a key phosphatase involved in the regulation of Akt phosphorylation. In addition, activation of Notch1 by Jagged1 or administration of peroxynitrite scavenger reduced production of peroxynitrite and attenuated MI/R injury. These data indicate that Notch1 signaling protects against MI/R injury partly though PTEN/Akt mediated anti-oxidative and anti-nitrative effects.