Toll-like receptor 4/nuclear factor-kappa B pathway is involved in myocardial injury in a rat chronic stress model

The role of TLR2 in exercise-induced immunomodulation in normal weight individuals

Toll-like receptors (TLRs) have been targeted for therapeutic drug development for several disorders, including cardiovascular diseases (CVD), and diabetes mellitus. Daily levels physical activity (PA) has been purported to influence the systemic circulation of cytokines, affecting the overall activation of TLRs and influencing the inflammatory milieu. Objective and self-reported daily PA was tracked in 69 normal-weight adults. Freedson's cut-offs categorized daily PA intensity into the 25th lowest, medium, and top percentiles. Monocytic TLR2 expression was quantified by flow cytometry in fresh whole blood. Cross-sectional associations between flow cytometry measured TLR2⁺ subsets and clinical biomarkers were evaluated. PA increased circulation of TLR2⁺ monocytes. TLR2 expression was adversely corelated with reduced diastolic blood pressure (DBP), triglyceride (TG), and matrix metallopeptidase 9 (MMP9) levels. However, regression analysis indicated that only TG levels were independently linked with TLR2⁺ subsets in circulation in active participants. Higher daily levels of physical activity are associated with improved cardiovascular blood markers and elevated circulatory monocytic TLR2⁺ subsets. These findings suggest that TLR2 may play a role in modulating CVD risk factors in individuals leading physically active lifestyles.

Effect of Chlorogenic Acid via Upregulating Resolvin D1 Inhibiting the NF-κB Pathway on Chronic Restraint Stress-Induced Liver Inflammation

Chronic stress can cause chronic inflammatory injury to the liver. Chlorogenic acid (CGA) is known to have a wide range of biological activities and anti-inflammatory effects. Resolvin D1 (RvD1) is a polyunsaturated fatty acid derivative that has inhibitory effects on a variety of inflammatory diseases. However, whether CGA can inhibit liver inflammation in chronic stress through RvD1 remains unclear. In this work, male rats were subjected to restraint stress for 6 h every day and built a chronic stress model for 21 days. CGA (100 mg/kg) was administered intragastrically 1 h before restraint, with intraperitoneal injection of RvD1 inhibitor WRW4 (antagonist of FPR2, 0.1 mg/kg) or WRW4 solution every 2 days for 30 min before CGA administration. CGA reduced hepatic hemorrhage and inflammatory cell infiltration, alleviated hepatic injury, decreased the activation of the NF-κB pathway and the expression of interleukin 1β, interleukin 6, and tumor necrosis factor α in the liver, and increased RvD1 in the serum and liver. The therapeutic effect of CGA was blocked after WRW4 intervention. These results suggest that the protective effects of CGA mediate the NF-κB pathway by upregulating the generation of RvD1. Above all, this research demonstrates the liver protective effect of CGA and provides a potential treatment strategy for chronic inflammatory disease.

Role of TLR4 in physical exercise and cardiovascular diseases

Cardiovascular diseases are a leading cause of death for adults worldwide. Published articles have shown that toll-like receptor 4 (TLR4), a member of the toll-like receptor (TLR) family, is involved in several cardiovascular diseases and can be modulated by physical exercise. TLR4 is the most expressed TLR in cardiac tissue and is an essential mediator of the inflammatory and apoptosis processes in the heart, playing a pivotal role in the development of cardiovascular diseases. Physical exercise is recognized as a non-pharmacological strategy for the prevention and treatment of these diseases. In addition, physical exercise can modulate the TLR4 in the mice heart, and its absence attenuates apoptosis, endoplasmic reticulum stress, and inflammation. However, the relationship between TLR4 and physical exercise-induced cardiac adaptations has barely been explored. Thus, the objective of this brief review was to discuss studies describing how TLR4 influences cardiac responses to physical exercise and present a link between these responses and cardiovascular diseases, showing physical activity improves the cardiac function of individuals with cardiovascular diseases through the TLR4 modulation.

Chronic Dexamethasone exposure activates the TLR4-Mediated inflammation pathway and induces epithelial apoptosis in the goat colon

Chronic stress has a profound effect on health in both animals and humans. Dexamethasone (Dex), a synthetic glucocorticoid, is used to induce chronic stress in many studies. The impact of chronic stress on epithelial cells of hindgut of ruminants is still unknown. In this study, we investigated the effect of chronic stress induced by long term injection of low dosage of Dex on the colonic epithelium of goats. The results showed that Dex exposure increased the number of TUNEL-positive cells, upregulated caspase-3 and caspase-8 enzyme activity, but decreased protein expression of cell proliferation markers proliferating cell nuclear antigen (PCNA) and Cyclin D2(CCND2). It also activated TLR-4 and NF-κB pathway and increased the transcription levels of vital inflammatory cytokines such as interleukin-10 (IL-10), interleukin-1β (IL-1β), and inducible nitric oxide synthase 2 (iNOS2). Chronic stress down-regulated the methylation level of total DNA, suggesting a mechanism for the transcriptional activation of genes, such as claudin-1, claudin-4, ZO-1, and cell cycle-related genes. Taken together, long-term injection of a low dosage of Dex caused damage to the colon epithelium accompanied with the inhibition of cell proliferation and the activation of cell apoptosis and inflammation. However, a general up-regulation of genes expression induced by Dex is due to a lower level of genomic DNA methylation.

Role of cytokines and inflammation in heart function during health and disease

By virtue of their actions on NF-κB, an inflammatory nuclear transcription factor, various cytokines have been documented to play important regulatory roles in determining cardiac function under both physiological and pathophysiological conditions. Several cytokines including TNF-α, TGF-β, and different interleukins such as IL-1 IL-4, IL-6, IL-8, and IL-18 are involved in the development of various inflammatory cardiac pathologies, namely ischemic heart disease, myocardial infarction, heart failure, and cardiomyopathies. In ischemia-related pathologies, most of the cytokines are released into the circulation and serve as biological markers of inflammation. Furthermore, there is an evidence of their direct role in the pathogenesis of ischemic injury, suggesting cytokines as potential targets for the development of some anti-ischemic therapies. On the other hand, certain cytokines such as IL-2, IL-4, IL-6, IL-8, and IL-10 are involved in the post-ischemic tissue repair and thus are considered to exert beneficial effects on cardiac function. Conflicting reports regarding the role of some cytokines in inducing cardiac dysfunction in heart failure and different types of cardiomyopathies seem to be due to differences in the nature, duration, and degree of heart disease as well as the concentrations of some cytokines in the circulation. In spite of extensive research work in this field of investigation, no satisfactory anti-cytokine therapy for improving cardiac function in any type of heart disease is available in the literature.

Grape seed extract and chromium nicotinate reduce impacts of heat stress in Simmental × Qinchuan steers

To assess the impacts of grape seed extract (GSE) fed with or without chromium nicotinate (CN) on beef steers under heat stress conditions, 40 Simmental × Qinchuan steers (400 ± 10 days old; 410 ± 8.0 kg) were randomly assigned to one of four diets (n = 10 per group): basal diet (CON group); basal diet + 33 mg/day CN (CN group); basal diet + 65 mg/kg DM GSE (GSE group); and basal diet + 33 mg/day CN + 65 mg/kg DM GSE (CN + GSE group). This study was conducted in summer and the steers were housed in outdoor shaded pens (10 steers/pen) and fed individually. The experiment lasted for 35 days, the first 7 days for diet and housing condition adaptation. The amount of feed intake was recorded daily; individual bodyweight was recorded on Days 8, 22, and 36. On Day 36 before feeding, six steers per group were slaughtered for collection of blood and tissue samples. Average daily liveweight gain and dry matter intake of steers were increased by the GSE, CN, and CN + GSE treatments (P < 0.05). Dietary treatments increased the activities of glutathione peroxidase and total superoxide dismutase in plasma (P < 0.05) and plasma concentration of interleukin 10 on Days 22 and 36 (P < 0.05), whereas decreased plasma concentration of tumour necrosis factor-α on Day 22 (P < 0.05). Overall, supplementation of GSE alone or with CN had positive effects on the growth performance of steers under heat stress conditions.

The Effects of Chronic Administration of Cisplatin on Oxidative Stress in the Isolated Rat Heart

Taken into consideration that molecular and cellular mechanisms involved in cardiotoxicity are still not clear the aim of this study was to compare the production of oxidative stress parameters in the isolated rat heart between animals chronically treated with cisplatin and saline. The hearts of male Wistar albino rats (n = 24, 12 per group, age 8 weeks, body mass 250±50 g) were excised and perfused according to the Langendorff technique at gradually increased coronary perfusion pressures (40-120 cm H2O). We followed the production of superoxide anion radicals, hydrogen peroxide, and nitrites and also index of lipid peroxidation during the changes of coronary perfusion pressure (CPP) (from 40 to 120 cm H2O) in coronary venous effluent. Modifications CPP were performed in order to determined if oxidative stress is involved in coronary endothelium response in conditions of hypoxia (lower than 60 cm H2O) and hyperoxia (higher than 80 cm H2O).

Based on the results of this research we can conclude that with enhancement of CPP the values of oxidative stress statistically increased. However, this increment is more prominent in control group as a result of preserved endothelium and its more powerful response to hyperoxia. On the other hand, damaged endothelium of cisplatin-treated animals had weaker response to hyperoxia, and also lower antioxidant capacity.

The Effects of Chronic Administration of Cisplatin on Oxidative Stress in the Isolated Rat Heart

Taken into consideration that molecular and cellular mechanisms involved in cardiotoxicity are still not clear the aim of this study was to compare the production of oxidative stress parameters in the isolated rat heart between animals chronically treated with cisplatin and saline. Th e hearts of male Wistar albino rats (n = 24, 12 per group, age 8 weeks, body mass 250±50 g) were excised and perfused according to the Langendorff technique at gradually increased coronary perfusion pressures (40-120 cmH2O). We followed the production of superoxide anion radicals, hydrogen peroxide, and nitrites and also index of lipid peroxidation during the changes of coronary perfusion pressure (CPP) (from 40 to 120 cm H2O) in coronary venous effluent. Modifications CPP were performed in order to determined if oxidative stress is involved in coronary endothelium response in conditions of hypoxia (lower than 60 cm H2O) and hyperoxia (higher than 80 cm H2O). Based on the results of this research we can conclude that with enhancement of CPP the values of oxidative stress statistically increased. However, this increment is more prominent in control group as a result of preserved endothelium and its more powerful response to hyperoxia. On the other hand, damaged endothelium of cisplatin-treated animals had weaker response to hyperoxia, and also lower antioxidant capacity.

Dexmedetomidine Protects Cardiomyocytes against Hypoxia/Reoxygenation Injury by Suppressing TLR4-MyD88-NF-κB Signaling

OBJECTIVE

We previously reported that dexmedetomidine (DEX) offers cardioprotection against ischemia/reperfusion injury in rats. Here, we evaluated the role of toll-like receptors 4- (TLR4-) myeloid differentiation primary response 88- (MyD88-) nuclear factor-kappa B (NF-κB) signaling in DEX-mediated protection of cardiomyocytes using in vitro models of hypoxia/reoxygenation (H/R).

METHODS

The experiments were carried out in H9C2 cells and in primary neonatal rat cardiomyocytes. Cells pretreated with vehicle or DEX were exposed to hypoxia for 1 h followed by reoxygenation for 12 h. We analyzed cell viability and lactate dehydrogenase (LDH) activity and measured tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β mRNA levels, TLR4, MyD88, and nuclear NF-κB p65 protein expression and NF-κB p65 nuclear localization. TLR4 knock-down by TLR4 siRNA transfection and overexpression by TLR4 DNA transfection were used to further confirm our findings.

RESULTS

DEX protected against H/R-induced cell damage and inflammation, as evidenced by increased cell survival rates, decreased LDH activity, and decreased TNF-α, IL-6, and IL-1β mRNA levels, as well as TLR4 and NF-κB protein expression. TLR4 knock-down partially prevented cell damage following H/R injury, while overexpression of TLR4 abolished the DEX-mediated protective effects.

CONCLUSIONS

DEX pretreatment protects rat cardiomyocytes against H/R injury. This effect is partly mediated by TLR4 suppression via TLR4-MyD88-NF-κB signaling.

Taurine protects cisplatin induced cardiotoxicity by modulating inflammatory and endoplasmic reticulum stress responses

Oxidative stress, ER stress, inflammation, and apoptosis results in the pathogenesis of cisplatin-induced cardiotoxicity. The present study was designed to investigate the signaling mechanisms involved in the ameliorating effect of taurine, a conditionally essential amino acid, against cisplatin-mediated cardiac ER stress dependent apoptotic death and inflammation. Mice were simultaneously treated with taurine (150 mg kg-1 body wt, i.p.) and cisplatin (10 mg kg-1 body wt, i.p.) for a week. Cisplatin exposure significantly altered serum creatine kinase and troponin T levels. In addition, histological studies revealed disintegration in the normal radiation pattern of cardiac muscle fibers. However, taurine administration could abate such adverse effects of cisplatin. Taurine administration significantly mitigated the reactive oxygen species production, alleviated the overexpression of nuclear factor-κB (NF-κB), and inhibited the elevation of proinflammatoy cytokines, adhesion molecules, and chemokines. Cisplatin exposure resulted in the unfolded protein response (UPR)-regulated CCAAT/enhancer binding protein (CHOP) up-regulation, induction of GRP78: a marker of ER stress and eIF2α signaling. Increase in calpain-1 expression level, activation of caspase-12 and caspase-3, cleavage of the PARP protein as well as the inhibition of antiapoptotic protein Bcl-2 were reflected on cisplatin-triggered apoptosis. Taurine could, however, combat against such cisplatin induced cardiac-abnormalities. The above mentioned findings suggest that taurine plays a beneficial role in providing protection against cisplatin-induced cardiac damage by modulating inflammatory responses and ER stress. © 2016 BioFactors, 42(6):647-664, 2016.

Inhibitory Effect of TLR4 Gene Silencing on Intimal Hyperplasia of Vein Grafting

PURPOSE

The present study aimed to explore the regulating effect of Toll-like receptor 4 (TLR4) on intimal hyperplasia in rat vein grafts.

METHODS

Rat models of external jugular vein carotid artery bypass grafting were established. Afterward, TLR4 small interfering RNA (siRNA) recombinant plasmids were constructed, which were transfected into rat vein graft bypass to study the effect of TLR4 silencing on intimal hyperplasia and to explore the underlying mechanisms. Real-time polymerase chain reaction and Western blot were used to detect the expression levels of TLR4 and inflammatory factors in TLR4 siRNA-transfected vein graft bypass. The intimal thickness was evaluated using hematoxylin-eosin staining.

RESULTS

Compared with the scramble siRNA group, the intimal thickness of vein grafting was decreased significantly, while the inflammatory factors including interleukin (IL) 1β, IL-6, and tumor necrosis factor α in grafted vein were dramatically downregulated in the TLR4 siRNA group.

CONCLUSION

These results showed that local silencing of TLR4 in the vein grafts could inhibit intimal hyperplasia by downregulating the expression of inflammatory factors in the vein grafts, suggesting that TLR4 can be used as a new target for therapy of vascular intimal hyperplasia.

Role of S100A1 in hypoxia-induced inflammatory response in cardiomyocytes via TLR4/ROS/NF-κB pathway

Objectives

S100A1 plays a crucial role in hypoxia-induced inflammatory response in cardiomyocytes. However, the role of S100A1 in hypoxia-induced inflammatory response in cardiomyocytes is still unknown.

Methods

enzyme-linked immunosorbent assay (ELISA) was performed for the determination of inflammatory cytokines. Immunocytochemistry and immunofluorescence, Western blot analysis and Real-time polymerase chain reaction (RT-PCR) were conducted to assess protein or mRNA expressions. Fluorogenic probe dihydroethidium (DHE) was used to evaluate the generation of reactive oxygen species (ROS) while Hoechst 33342 staining for apoptosis. Small interfering RNA (siRNA) for S100A1 was used to evaluate the role of S100A1.

Key findings

The levels of ROS and inflammatory cytokine including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-8 in H9c2 cells were increased remarkably by hypoxia. However, IL-37 protein or mRNA levels were decreased significantly. Both Toll-like receptor 4 (TLR4) inhibitor Ethyl (6R)-6-[N-(2-Chloro-4fluorophenyl)sulfamoyl]cyclohex-1-ene-1-carboxylate (TAK-242) treatment or siRNA S100A1 downregulated TLR4 expression and inflammatory cytokine level and mRNA in H9c2 cells, as well as weakening ROS and phospho-p65 Nuclear factor (NF)-κB levels. Further, S100A1 treatment significantly reduced TNF-α protein or mRNA level whereas enhanced IL-37 protein or mRNA level, and could attenuate ROS and phospho-p65 NF-κB levels.

Conclusions

Our results demonstrate that S100A1 can regulate the inflammatory response and oxidative stress in H9C2 cells via TLR4/ROS/NF-κB pathway. These findings provide an interesting strategy for protecting cardiomyocytes from hypoxia-induced inflammatory response.

TLR4/NF-κB signaling contributes to chronic unpredictable mild stress-induced atherosclerosis in ApoE-/- mice

Objective

Chronic stress is an important risk factor for atherosclerotic diseases. Our previous studies have shown that chronic unpredictable mild stress (CUMS) accelerates atherosclerosis and up-regulates TLR4/NF-κB expression in apoE^-/- mice. However, TLR4/NF-κB signaling whether directly contributes to the development of atherosclerosis in CUMS mice is unclear. We hypothesized that the interference of TLR4/NF-κB can ameliorate CUMS-induced inflammation and atherosclerosis in apoE^-/- mice.

Methods

ApoE^-/- mice were exposed to 12 weeks CUMS. Ad-siRNA TLR4 was given by tail vein injection (10 μl/mouse, every 5 days), and PDTC (an inhibitor of NF-κB) was given by intraperitoneal injection (60 mg/kg, once a day). Plasma corticosterone concentrations were determined by solid-phase ¹²⁵I radioimmunoassay. Atherosclerosis lesions in aortic sinuses were evaluated and quantified by IMAGEPRO PLUS. Western blotting was used to detect the expression of TLR4, NF-κB, and IL-1β in aortas of the mice. Plasma lipid profiles, IL-1β, TNF-α, and MCP-1 were measured by ELISA.

Results

Our results indicated that CUMS apoE^-/- mice treatment with siRNA TLR4 significantly decreased atherosclerosis and down-regulated TLR4, NF-κB, and inflammatory cytokines. PDTC also remarkably reduced atherosclerosis and the levels of IL-1β, TNF-α and MCP-1 in plasma. However, Treatment with siRNA TLR4 or PDTC had no effect on plasma corticosterone levels, and lipid profiles.

Conclusions

TLR4/NF-κB pathway may participate in CUMS-induced atherosclerosis through activation of proinflammatory cytokines in apoE^-/- mice. Our data may provide a new potential therapeutic target for prevention of CUMS -induced atherosclerosis.

Toll-like receptor 4 mediates the inflammatory responses and matrix protein remodeling in remote non-ischemic myocardium in a mouse model of myocardial ischemia and reperfusion

The signaling mechanism that mediates inflammatory responses in remote non-ischemic myocardium following regional ischemia/reperfusion (I/R) remains incompletely understood. Myocardial Toll-like receptor 4 (TLR4) can be activated by multiple proteins released from injured cells and plays a role in myocardial inflammation and injury expansion. We tested the hypothesis that TLR4 occupies an important role in mediating the inflammatory responses and matrix protein remodeling in the remote non-ischemic myocardium following regional I/R injury. Methods and results: TLR4-defective (C3H/HeJ) and TLR4-competent (C3H/HeN) mice were subjected to coronary artery ligation (30 min) and reperfusion for 1, 3, 7 or 14 days. In TLR4-competent mice, levels of monocyte chemoattractant protein -1 (MCP-1), keratinocyte chemoattractant (KC), intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) were elevated in the remote non-ischemic myocardium at day 1, 3, and 7 of reperfusion. Levels of collagen I, collagen IV, matrix metalloproteinase (MMP) 2 and MMP 9 were increased in the remote non-ischemic myocardium at day 7 and 14 of reperfusion. MMP 2 and MMP 9 activities were also increased. TLR4 deficiency resulted in a moderate reduction in myocardial infarct size. However, it markedly downgraded the changes in the levels of chemokines, adhesion molecules and matrix proteins in the remote non-ischemic myocardium. Further, left ventricular function at day 14 was significantly improved in TLR4-defective mice. In conclusion, TLR4 mediates the inflammatory responses and matrix protein remodeling in the remote non-ischemic myocardium following regional myocardial I/R injury and contributes to the mechanism of adverse cardiac remodeling.

The Man I Once Knew

Grief, although traditionally conceptualized as a bereavement-related reaction, is also experienced by significant others in response to the profound cognitive and personality changes associated with a traumatic brain injury (TBI) in a loved one. Grief associated with the death of a loved one is related to increases in proinflammatory cytokines, yet it is not clear whether this is the case for grief experienced by individuals caring for a significant other with TBI. The purpose of this cross-sectional, exploratory study was to examine grief and its association with a proinflammatory cytokine, tumor necrosis factor α (TNF-α), in wives/partners caring for veterans with TBI. Participants completed written measures of grief, perceived stress, and depressive symptoms and provided morning saliva samples for TNF-α analysis. Participants reported levels of grief comparable to those reported in studies evaluating individuals grieving the death of a loved one. Path analysis revealed that grief was not associated with TNF-α; however, participants reporting high levels of blame/anger, a subscale of the grief scale, had higher levels of TNF-α. In addition, both grief and blame/anger were related to increased perceived stress and depressive symptoms; however, path analysis demonstrated that perceived stress and depressive symptoms did not mediate the influence of blame/anger on TNF-α. These findings suggest that blame/anger associated with grief may be related to the elevations in TNF-α exhibited by individuals caring for a loved one with TBI.

Effects of Lycium barbarum polysaccharides on oxidative stress in hyperlipidemic mice following chronic composite psychological stress intervention

Chronic composite psychological stress intervention is the accumulation of factors which may induce psychological stress, including food deprivation, water deprivation and swimming in cold water. Approximately 40% of cases of atherosclerosis are associated with chronic composite psychological stress. The aim of the present study was to explore the effects of Lycium barbarum polysaccharides (LBP) on blood lipid levels and oxidative stress in hyperlipidemic mice, following chronic composite psychological stress. A hyperlipidemic mouse model was generated, and the mice were subjected to chronic composite psychological stress and treated with LBP for 30 days. After 30 days the triglyceride (TG) and total cholesterol (TC) levels were measured in the serum, and the mRNA expression levels of cholesterol 7α‑hydroxylase (CYP7A1) were determined in the liver, in order to observe any changes to lipid metabolism. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were measured in the liver to evaluate the effects of LBP on oxidative stress. The blood serum levels of interleukin‑6 (IL‑6) and heat shock protein 70 (HSP‑70) were measured to evaluate the extent of the aortic inflammatory response, and to determine the protective effects of LBP. The levels of TG, TC, MDA and IL‑6 were significantly higher in the mice subjected to chronic composite psychological stress (HS), as compared with the mice treated with LBP alone (HL), or treated with LBP and subjected to stress (HLS). In addition, SOD and HSP‑70 levels, and the mRNA expression levels of CYP7A1 were significantly lower in the HS group, as compared with that in the HL and HLS groups. These results suggest that chronic composite psychological stress may promote the occurrence and development of atherosclerosis, by inducing the aortic inflammatory response and lipid peroxidation. Furthermore, treatment with LBP significantly inhibited oxidative stress and the aortic inflammatory response.

N-acetylcysteine reduces oxidative stress, nuclear factor‑κB activity and cardiomyocyte apoptosis in heart failure

The roles of oxidative stress on nuclear factor (NF)‑κB activity and cardiomyocyte apoptosis during heart failure were examined using the antioxidant N‑acetylcysteine (NAC). Heart failure was established in Japanese white rabbits with intravenous injections of doxorubicin, with ten rabbits serving as a control group. Of the rabbits with heart failure, 12 were not treated (HF group) and 13 received NAC (NAC group). Cardiac function was assessed using echocardiography and hemodynamic analysis. Myocardial cell apoptosis, apoptosis‑related protein expression, NF‑κBp65 expression and activity, total anti‑oxidative capacity (tAOC), 8‑iso‑prostaglandin F2α (8‑iso‑PGF2α) expression and glutathione (GSH) expression levels were determined. In the HF group, reduced tAOC, GSH levels and Bcl‑2/Bax ratios as well as increased 8‑iso‑PGF2α levels and apoptosis were observed (all P<0.05), which were effects that were attenuated by the treatment with NAC. NF‑κBp65 and iNOS levels were significantly higher and the P‑IκB‑α levels were significantly lower in the HF group; expression of all three proteins returned to pre‑HF levels following treatment with NAC. Myocardial cell apoptosis was positively correlated with left ventricular end-diastolic pressure (LVEDP), NF‑κBp65 expression and 8‑iso‑PGF2α levels, but negatively correlated with the maximal and minimal rates of increase in left ventricular pressure (+dp/dtmax and ‑dp/dtmin, respectively) and the Bcl‑2/Bax ratio (all P<0.001). The 8‑iso‑PGF2α levels were positively correlated with LVEDP and negatively correlated with +dp/dtmax and ‑dp/dtmin (all P<0.001). The present study demonstrated that NAC increased the antioxidant capacity, decreased the NF‑κB activation and reduced myocardial cell apoptosis in an in vivo heart failure model.

Toll-like 4 receptor inhibitor TAK-242 decreases neuroinflammation in rat brain frontal cortex after stress

Background

The innate immune response is the first line of defence against invading microorganisms and it is also activated in different neurologic/neurodegenerative pathological scenarios. As a result, the family of the innate immune toll-like receptors (TLRs) and, in particular, the genetic/pharmacological manipulation of the TLR-4 signalling pathway emerges as a potential therapeutic strategy. Growing evidence relates stress exposure with altered immune responses, but the precise role of TLR-4 remains partly unknown.

Methods

The present study aimed to elucidate whether the elements of the TLR-4 signalling pathway are activated after acute stress exposure in rat brain frontal cortex and its role in the regulation of the stress-induced neuroinflammatory response, by means of its pharmacological modulation with the intravenous administration of the TLR-4 specific inhibitor TAK-242. Considering that TLR-4 responds predominantly to lipopolysaccharide from gram-negative bacteria, we checked whether increased intestinal permeability and a resultant bacterial translocation is a potential regulatory mechanism of stress-induced TLR-4 activation.

Results

Acute restraint stress exposure upregulates TLR-4 expression both at the mRNA and protein level. Stress-induced TLR-4 upregulation is prevented by the protocol of antibiotic intestinal decontamination made to reduce indigenous gastrointestinal microflora, suggesting a role for bacterial translocation on TLR-4 signalling pathway activation. TAK-242 pre-stress administration prevents the accumulation of potentially deleterious inflammatory and oxidative/nitrosative mediators in the brain frontal cortex of rats.

Conclusions

The use of TAK-242 or other TLR-4 signalling pathway inhibitory compounds could be considered as a potential therapeutic adjuvant strategy to constrain the inflammatory process taking place after stress exposure and in stress-related neuropsychiatric diseases.

Stress-Derived Corticotropin Releasing Factor Breaches Epithelial Endotoxin Tolerance

BACKGROUND AND AIMS

Loss of the endotoxin tolerance of intestinal epithelium contributes to a number of intestinal diseases. The etiology is not clear. Psychological stress is proposed to compromise the intestinal barrier function. The present study aims to elucidate the role of the stress-derived corticotropin releasing factor (CRF) in breaching the established intestinal epithelial endotoxin tolerance.

METHODS

Epithelial cells of HT-29, T84 and MDCK were exposed to lipopolysaccharide to induce the endotoxin tolerance; the cells were then stimulated with CRF. The epithelial barrier function was determined using as indicators of the endotoxin tolerant status. A water-avoid stress mouse model was employed to test the role of CRF in breaching the established endotoxin tolerance in the intestine.

RESULTS

The established endotoxin tolerance in the epithelial cell monolayers was broken down by a sequent exposure to CRF and LPS manifesting a marked drop of the transepithelial resistance (TER) and an increase in the permeability to a macromolecular tracer, horseradish peroxidase (HRP). The exposure to CRF also increased the expression of Cldn2 in the epithelial cells, which could be mimicked by over expression of TLR4 in epithelial cells. Over expression of Cldn2 resulted in low TER in epithelial monolayers and high permeability to HRP. After treating mice with the 10-day chronic stress, the intestinal epithelial barrier function was markedly compromised, which could be prevented by blocking either CRF, or TLR4, or Cldn2.

CONCLUSIONS

Psychological stress-derived CRF can breach the established endotoxin tolerance in the intestinal mucosa.

TLR4 antagonist reduces early-stage atherosclerosis in diabetic apolipoprotein E-deficient mice

Although it has been reported that deficiency of toll-like receptor 4 (TLR4) is associated with reduced atherosclerosis in atherosclerosis-prone mice and attenuated pro-inflammatory state in diabetic mice, it remains undetermined whether treatment with a TLR4 antagonist reduces atherosclerosis in nondiabetic or diabetic mice that have TLR4 expression. In this study, we determined the effect of Rhodobacter sphaeroides lipopolysaccharide (Rs-LPS), an established TLR4 antagonist, on early-stage atherosclerosis in nondiabetic and streptozotocin-induced diabetic apolipoprotein E-deficient (Apoe(-/-)) mice. Analysis of atherosclerotic lesions of both en face aortas and cross sections of aortic roots showed that administration of Rs-LPS in 14-week-old diabetic Apoe(-/-) mice for 10 weeks significantly reduced atherosclerotic lesions. Although atherosclerotic lesions in nondiabetic Apoe(-/-) mice appeared to be decreased by Rs-LPS treatment, the difference was not statistically significant. Metabolic study showed that Rs-LPS significantly lowered serum levels of cholesterol and triglycerides in nondiabetic mice but not in diabetic mice. Furthermore, immunohistochemistry studies showed that Rs-LPS inhibited the expression of interleukin 6 and matrix metalloproteinase-9 and reduced the content of monocytes and macrophages in atherosclerotic plaques. Taken together, this study demonstrated for the first time that TLR4 antagonist inhibited vascular inflammation and atherogenesis in diabetic Apoe(-/-) mice and lowered serum cholesterol and triglyceride levels in nondiabetic Apoe(-/-) mice.

Elucidating molecular networks that either affect or respond to plasma cortisol concentration in target tissues of liver and muscle

Cortisol is a steroid hormone with important roles in regulating immune and metabolic functions and organismal responses to external stimuli are mediated by the glucocorticoid system. Dysregulation of the afferent and efferent axis of glucocorticoid signaling have adverse effects on growth, health status, and well-being. Glucocorticoid secretion and signaling show large interindividual variation that has a considerable genetic component; however, little is known about the underlying genetic variants. Here, we used trait-correlated expression analysis, screening for expression quantitative trait loci (eQTL), genome-wide association (GWA) studies, and causality modeling to identify candidate genes in porcine liver and muscle that affect or respond to plasma cortisol levels. Through trait-correlated expression, we characterized transcript activities in many biological functions in liver and muscle. Candidates from the list of trait-correlated expressed genes were narrowed using only those genes with an eQTL, and these were further prioritized by determining whether their expression was predicted to be related to variation in plasma cortisol levels. Using network edge orienting (NEO), a causality modeling algorithm, 26 of 990 candidates in liver were predicted to affect and 70 to respond to plasma cortisol levels. Of 593 candidates in muscle that were correlated with cortisol levels and were regulated by eQTL, 2 and 25 were predicted as effective and responsive, respectively, to plasma cortisol levels. Comprehensive data integration has helped to elucidate the complex molecular networks contributing to cortisol levels and thus its subsequent metabolic effects. The discrimination of up- and downstream effects of transcripts affecting or responding to plasma cortisol concentrations improves the understanding of the biology of complex traits related to growth, health, and well-being.

Therapeutic role of toll-like receptor modification in cardiovascular dysfunction

Toll-like receptors (TLR) are key pattern recognition receptors in the innate immune system. The TLR-mediated immune response against pathogens is usually protective however inappropriate TLR activation may lead to excessive tissue damage. It is well recognised that TLRs respond to a variety of endogenous as well as exogenous ligands. By responding to endogenous ligands that are exposed during cellular damage, TLRs have been implicated in a range of pathological conditions associated with cardiovascular dysfunction. Increasing knowledge on the mechanisms involved in TLR signalling has encouraged the exploration of therapeutic pharmacological modulation of TLR activation in conditions such as atherosclerosis, ischaemic heart disease, heart failure and ischaemic reperfusion injury. The aim of this review is to explore the translational potentials of TLR modification in cardiovascular dysfunction, where these agents have been studied.

Myocardial ischemia reperfusion injury: from basic science to clinical bedside

Myocardial ischemia reperfusion injury contributes to adverse cardiovascular outcomes after myocardial ischemia, cardiac surgery or circulatory arrest. Primarily, no blood flow to the heart causes an imbalance between oxygen demand and supply, named ischemia (from the Greek isch, restriction; and haema, blood), resulting in damage or dysfunction of the cardiac tissue. Instinctively, early and fast restoration of blood flow has been established to be the treatment of choice to prevent further tissue injury. Indeed, the use of thrombolytic therapy or primary percutaneous coronary intervention is the most effective strategy for reducing the size of a myocardial infarct and improving the clinical outcome. Unfortunately, restoring blood flow to the ischemic myocardium, named reperfusion, can also induce injury. This phenomenon was therefore termed myocardial ischemia reperfusion injury. Subsequent studies in animal models of acute myocardial infarction suggest that myocardial ischemia reperfusion injury accounts for up to 50% of the final size of a myocardial infarct. Consequently, many researchers aim to understand the underlying molecular mechanism of myocardial ischemia reperfusion injury to find therapeutic strategies ultimately reducing the final infarct size. Despite the identification of numerous therapeutic strategies at the bench, many of them are just in the process of being translated to bedside. The current review discusses the most striking basic science findings made during the past decades that are currently under clinical evaluation, with the ultimate goal to treat patients who are suffering from myocardial ischemia reperfusion-associated tissue injury.