TNF-alpha, inefficient by itself, potentiates IL-1beta-induced PGHS-2 expression in human pulmonary microvascular endothelial cells: requirement of NF-kappaB and p38 MAPK pathways

Maternal nano-titanium dioxide inhalation exposure alters placental cyclooxygenase and oxidant balance in a sexually dimorphic manner

The placenta plays a critical role in nutrient-waste exchange between the maternal and fetal circulation, and thus impacts fetal growth and development. We have previously shown that nano-titanium dioxide (nano-TiO2) inhalation exposure during gestation decreased fetal female pup and placenta mass [1], which persists in the following generation [2]. In utero exposed females, once mated, their offspring's placentas had increased capacity for H2O2 production. Generation of oxidants such as hydrogen peroxide (H2O2), have been shown to impact cyclooxygenase activity, specifically metabolites such as prostacyclin (PGI2) or thromboxane (TXA2). Therefore, we hypothesized that maternal nano-TiO2 inhalation exposure during gestation results in alterations in placental production of prostacyclin and thromboxane mediated by enhanced H2O2 production in a sexually dimorphic manner. Pregnant Sprague-Dawley rats were exposed to nano-TiO2 aerosols or filtered air (sham--control) from gestational day (GD) 10-19. Dams were euthanized on GD 20, and fetal serum and placental tissue were collected based on fetal sex. Fetal placental zones (junctional zone (JZ) and labyrinth zone (LZ)) were assessed for xanthine oxidoreductase (XOR) activity, H2O2, and catalase activity, as well as 6-keto-PGF1α and TXB2 levels. Nano-TiO2 exposed fetal female LZ demonstrated significantly greater XOR activity compared to exposed males. Exposed fetal female LZ also demonstrated significantly diminished catalase activity compared to sham-control females. Exposed fetal female LZ had significantly increased abundance of 6-keto-PGF1α compared to sham-control females and increased TXB2 compared to exposed males. In the aggregate these data indicate that maternal nano-TiO2 inhalation exposure has a greater impact on redox homeostasis and PGI2/TXA2 balance in the fetal female LZ. Future studies need to address if treatment with an XO inhibitor during gestation can prevent diminished fetal female growth during maternal nano-TiO2 inhalation exposure.

A network pharmacology approach to reveal the protective mechanism of Salvia miltiorrhiza-Dalbergia odorifera coupled-herbs on coronary heart disease

Salvia miltiorrhiza-Dalbergia odorifera coupled-herbs (SMDOCH) has been used to treat coronary heart disease (CHD) for thousands of years, but its unclear bioactive components and mechanisms greatly limit its clinical application. In this study, for the first time, we used network pharmacology to elucidate the mechanisms of action of SMDOCH on CHD. We collected 270 SMDOCH-related targets from 74 bioactive components and 375 CHD-related targets, with 58 overlapping common targets. Next, we performed enrichment analysis for common-target network and protein-protein interaction (PPI) network. The results showed that SMDOCH affected CHD mainly through 10 significant signaling pathways in three biological processes: 'vascular endothelial function regulation', 'inflammatory response', and 'lipid metabolism'. Six pathways belonged to the 'vascular endothelial function regulation' model, which primarily regulated hormone (renin, angiotensin, oestrogen) activity, and included three key upstream pathways that influence vascular endothelial function, namely KEGG:04933, KEGG:05418, and KEGG:04066. Three pathways, namely KEGG:04668, KEGG:04064, and KEGG:04620, belonged to the 'inflammatory response' model. One pathway (KEGG:04920) belonged to the 'lipid metabolism' model. To some extent, this study revealed the potential bioactive components and pharmacological mechanisms of SMDOCH on CHD, and provided a new direction for the development of new drugs for the treatment of CHD.

Endothelial TNF-α induction by Hsp60 secreted from THP-1 monocytes exposed to hyperglycaemic conditions

A non-resolving inflammation of the endothelium is recognised to be an important process leading to atherosclerosis. In diabetes, this process is thought to account for a significant number of cardiovascular disease-associated death and disability. However, the molecular mechanisms by which diabetes contributes to endothelial inflammation remain to be established. Whilst there is some evidence linking hyperglycaemia-induced reactive oxygen species (ROS) formation by the mitochondrial electron-transport chain to oxidative stress, cellular injury and apoptosis in the endothelium, a clear link to endothelium inflammation has not yet been established. The mitochondrial molecular stress protein Hsp60 is known to be secreted from mammalian cells and is capable of activating pro-inflammatory mediators on target cells expressing Toll-like receptors (TLRs). Hsp60 is also known to be elevated in serum of diabetes patients and has been shown to be upregulated by hyperglycaemic growth conditions in cultured human HeLa cells. This study shows that Hsp60 induced in human acute monocyte leukaemia cell line (THP-1) cells grown under hyperglycaemic conditions (25 mM glucose) was able to be secreted into growth media. Furthermore, the secretion of Hsp60 from THP-1 cells was able to be inhibited by 5,5-(N-N-dimethyl)-amiloride hydrochloride (DMA), an exosomal inhibitor. Interestingly, the conditioned media obtained from THP-1 cells grown in the presence of 25 mM glucose was able to induce the secretion of TNF-α in human vascular endothelium cell line (HUVEC). When conditioned media was immuno-depleted of Hsp60, there was a significant reduction in the release of TNF-α from the HUVEC cells. This suggests that a potential link may exist between hyperglycaemia-induced expression of Hsp60 in monocyte cells and vascular inflammation. Circulating levels of Hsp60 due to mitochondrial stress in diabetes patients could therefore be an important modulator of inflammation in endothelial cells and thus contribute to the increased incidences of atherosclerosis in diabetes mellitus.

The effects of exercise and conjugated linoleic acid intake on IGF-1 and pro-inflammatory cytokines in atrophied skeletal muscle of rats

BACKGROUND

Conjugated linoleic acid (CLA) can be proposed as an effective nutrient for skeletal muscle atrophy. However, the research related to this is still insufficient. This study was carried out to analyze the mRNA expression of IGF-1 and cytokines in atrophied skeletal muscle of rats.

METHODS

Forty-two rats were randomly divided into seven groups, each group containing six rats. Sham-Pre and USN-Pre groups underwent a sham operation and a unilateral sciatic nerve (USN) cut, and were sacrificed 1 week later. Other groups had 4 weeks of treatment exercise and CLA intake, and then their blood, liver, and skeletal muscles were sampled after sacrifice.

RESULTS

Among the treatment groups, the group treated with both exercise and CLA (USN-EC) showed the lowest body weight. Groups with the sciatic nerve cut showed significantly (p < 0.05) lower muscle weight than groups with the sham operation. However, exercise and CLA intake had no effect on muscle weight. Regarding IGF-1 mRNA, the USN-EC group showed significantly higher expressions in the red muscle of the gastrocnemius and liver than the Sham-Pre and USN-CLA groups. Regarding TNF-α pro-inflammatory cytokine, there was no particular trend; however, the expression of IL-1β mRNA increased in the white muscle of the gastrocnemius muscle and tibialis anterior muscle after sciatic nerve cut, but showed a decrease with exercise and CLA treatment. Particularly in the gastrocnemius white muscle, the group treated with both exercise and CLA showed a significant decrease as compared to groups without treatment after sciatic nerve cut so that positive effects can be expected.

CONCLUSION

It is thought that combining treadmill training with CLA partially influences pro-inflammatory cytokines, so that this can act positively on improving skeletal muscle atrophy caused by sciatic nerve cut.

Inflammatory responses in primary muscle cell cultures in Atlantic salmon (Salmo salar)

BACKGROUND

The relationship between fish health and muscle growth is critical for continued expansion of the aquaculture industry. The effect of immune stimulation on the expression of genes related to the energy balance of fish is poorly understood. In mammals immune stimulation results in major transcriptional changes in muscle, potentially to allow a reallocation of amino acids for use in the immune response and energy homeostasis. The aim of this study was to investigate the effects of immune stimulation on fish muscle gene expression.

RESULTS

Atlantic salmon (Salmo salar) primary muscle cell cultures were stimulated with recombinant (r)IL-1β, a major proinflammatory cytokine, for 24 h in order to simulate an acute immune response. The transcriptomic response was determined by RNA hybridization to a 4 × 44 K Agilent Atlantic salmon microarray platform. The rIL-1β stimulation induced the expression of genes related to both the innate and adaptive immune systems. In addition there were highly significant changes in the expression of genes related to regulation of the cell cycle, growth/structural proteins, proteolysis and lipid metabolism. Of interest were a number of IGF binding proteins that were differentially expressed, which may demonstrate cross talk between the growth and immune systems.

CONCLUSION

We show rIL-1β modulates the expression of not only immune related genes, but also that of genes involved in processes related to growth and metabolism. Co-stimulation of muscle cells with both rIGF-I and rIL-1β demonstrates cross talk between these pathways providing potential avenues for further research. This study highlights the potential negative effects of inflammation on muscle protein deposition and growth in fish and extends our understanding of energy allocation in ectothermic animals.

Role of src-suppressed C kinase substrate in rat pulmonary microvascular endothelial hyperpermeability stimulated by inflammatory cytokines

OBJECTIVE

The aim of the study was to investigate the role of src-suppressed C kinase substrate (SSeCKS) in the modulation of rat pulmonary microvascular endothelial cells (RPMVEC) permeability elicited by interleukin (IL)-1β and tumor necrosis factor (TNF)-α.

METHODS

The gene expression of SSeCKS was analyzed by reverse transcription-polymerase chain reaction. Immunoblotting was used to determine the SSeCKS protein expression and the activation of the protein kinase C (PKC) signaling pathway. A RPMVEC monolayer was constructed to determine changes of transendothelial electrical resistance (TER) and FITC-dextran flux (P (d)) across the monolayer. SSeCKS-specific small interfering RNA was transfected into RPMVEC.

RESULTS

IL-1β and TNF-α activated the PKC signaling pathway in RPMVEC, and up-regulated the gene and protein expression of SSeCKS. Depletion of endogenous SSeCKS in RPMVEC significantly attenuated cytokine-induced decrease in TER and increase in P (d), but not to the basal levels. PKC inhibitors also significantly decreased cytokine-induced hyperpermeability and SSeCKS expression.

CONCLUSIONS

SSeCKS is involved in the endothelial hyperpermeability induced by IL-1β and TNF-α in inflammatory process.

2-Chlorohexadecanal and 2-chlorohexadecanoic acid induce COX-2 expression in human coronary artery endothelial cells

2-Chlorohexadecanal (2-ClHDA), a 16-carbon chain chlorinated fatty aldehyde that is produced by reactive chlorinating species attack of plasmalogens, is elevated in atherosclerotic plaques, infarcted myocardium, and activated leukocytes. We tested the hypothesis that 2-ClHDA and its metabolites, 2-chlorohexadecanoic acid (2-ClHA) and 2-chlorohexadecanol (2-ClHOH), induce COX-2 expression in human coronary artery endothelial cells (HCAEC). COX-2 protein expression increased in response to 2-ClHDA treatments at 8 and 20 h. 2-ClHA also increased COX-2 expression following an 8 h treatment. Quantitative PCR showed that 2-ClHDA treatment increased COX-2 mRNA over 8 h, while 2-ClHA treatment led to a modest increase by 1 h and those levels remained constant over 8 h. 2-ClHDA led to a significant increase in 6-keto-PGF(1alpha) release (a measure of PGI(2) release) by HCAEC. These data suggest that 2-ClHDA and its metabolite 2-ClHA, which are produced during leukocyte activation, may alter vascular endothelial cell function by upregulation of COX-2 expression.

HIV-1 Tat protein-induced VCAM-1 expression in human pulmonary artery endothelial cells and its signaling

Expression of cell adhesion molecule in endothelial cells upon activation by human immunodeficiency virus (HIV) infection is associated with the development of atherosclerotic vasculopathy. We postulated that induction of vascular cell adhesion molecule-1 (VCAM-1) by HIV-1 Tat protein in endothelial cells might represent an early event that could culminate in inflammatory cell recruitment and vascular injury. We determined the role of HIV-1 Tat protein in VCAM-1 expression in human pulmonary artery endothelial cells (HPAEC). HIV-1 Tat protein treatment significantly increased cell-surface expression of VCAM-1 in HPAEC. Consistently, mRNA expression of VCAM-1 was also increased by HIV-1 Tat protein as measured by RT-PCR. HIV-1 Tat protein-induced VCAM-1 expression was abolished by the NF-kappaB inhibitor pyrrolidine dithiocarbamate (PDTC) and the p38 MAPK inhibitor SB-203580. Furthermore, HIV-1 Tat protein enhanced DNA binding activity of NF-kappaB, facilitated nuclear translocation of NF-kappaB subunit p65, and increased production of reactive oxygen species (ROS). Similarly to VCAM-1 expression, HIV-1 Tat protein-induced NF-kappaB activation and ROS generation were abrogated by PDTC and SB-203580. These data indicate that HIV-1 Tat protein is able to induce VCAM-1 expression in HPAEC, which may represent a pivotal early molecular event in HIV-induced vascular/pulmonary injury. These data also suggest that the molecular mechanism underlying the HIV-1 Tat protein-induced VCAM-1 expression may involve ROS generation, p38 MAPK activation, and NF-kappaB translocation, which are the characteristics of pulmonary endothelial cell activation.

Conjugated linoleic acid preserves gastrocnemius muscle mass in mice bearing the colon-26 adenocarcinoma

Cancer cachexia is a syndrome of weight loss, muscle wasting, fatigue, and anorexia that occurs in patients with advanced or recurrent solid tumor disease. Tumor necrosis factor-alpha (TNFalpha) and prostaglandin E2 (PGE2) have been implicated in the biology of cachexia and serve as possible targets for treatment of this condition. Conjugated linoleic acid (CLA) is a polyunsaturated fatty acid that alters the synthesis of PGE2 and reduces the negative effects of TNF on body weight of healthy mice. We hypothesized that a diet supplemented with .5% CLA might reduce muscle wasting in mice bearing the colon-26 adenocarcinoma, an animal model of cancer cachexia. CLA preserved gastrocnemius muscle mass and reduced TNF receptors in muscle of tumor-bearing mice. These data suggest that CLA may preserve muscle mass by reducing the catabolic effects of TNF on skeletal muscle.

Indomethacin preserves muscle mass and reduces levels of E3 ligases and TNF receptor type 1 in the gastrocnemius muscle of tumor-bearing mice

Tumor-induced skeletal muscle wasting involves tumor necrosis factor (TNF) and the ubiquitin-proteasome pathway of muscle protein degradation. In this study, growth of the colon-26 adenocarcinoma in mice was associated with diminished gastrocnemius muscle mass and increased muscle levels of actin, ubiquitin-conjugated proteins, free ubiquitin, E3 ubiquitin ligases, and the type 1 TNF receptor (TNFR1). Indomethacin at 1 or 5 mg/kg/day reduced tumor growth and muscle levels of TNFR1. However, only the 5 mg dose of indomethacin reduced muscle wasting and muscle levels of the E3 ligases and actin. These data suggest that the beneficial effects of indomethacin in the treatment of tumor-induced skeletal muscle wasting may involve inhibition of TNF- and ubiquitin-mediated pathways of muscle protein degradation. These data also demonstrate that E3 ligases, which are involved in disuse atrophy, also are associated with tumor-induced skeletal muscle wasting.

Prostacyclin release and receptor activation: differential control of human pulmonary venous and arterial tone

1. In human pulmonary vascular preparations, precontracted arteries were more sensitive to the relaxant effect of acetylcholine (ACh) than veins (pD(2) values: 7.25+/-0.08 (n=23) and 5.92+/-0.09 (n=25), respectively). Therefore, the role of prostacyclin (PGI(2)) was explored to examine whether this mediator may be responsible for the difference in relaxation. 2. In the presence of the cyclooxygenase (COX) inhibitor, indomethacin (INDO), the ACh relaxations were reduced in arteries but not in veins. On the contrary, an inhibitor (l-NOARG) of the nitric oxide synthase blocked preferentially the relaxation in veins. 3. A greater release of 6-keto-PGF(1alpha), the stable metabolite of PGI(2), was observed in arterial preparations than in venous preparations when stimulated with either ACh or arachidonic acid (AA). 4. Exogenous PGI(2) produced a reduced relaxant effect in the precontracted vein when compared with the artery. In the presence of the EP(1)-receptor antagonist AH6809, the PGI(2) relaxation of veins was similar to arteries. 5. In veins, AA (0.1 mm) produced a biphasic response, namely, a contraction peak (0.4-0.5 g) followed by a relaxation. These contractions in venous preparations were abolished either in the absence of endothelium or in the presence of INDO or an EP(1)-receptor antagonist (AH6809, SC19220). In the arterial preparations AA induced only relaxations. 6. In both vascular preparations, COX-1 but not the COX-2 protein was detected in microsomal preparations derived from homogenized tissues or freshly isolated endothelial cells. 7. The differential vasorelaxations induced by ACh may be explained, in part, by a more pronounced production and release of PGI(2) in human pulmonary arteries than in the veins. In addition, while PGI(2) induced relaxation by activation of IP-receptors in both types of vessels, a PGI(2) constrictor effect was responsible for masking the relaxation in the veins by activation of the EP(1)-receptor.

Indomethacin and ibuprofen preserve gastrocnemius muscle mass in mice bearing the colon-26 adenocarcinoma

Skeletal muscle wasting is a prominent feature of cancer cachexia and involves decreased muscle protein synthesis and increased activity of the ubiquitin-proteasome pathway of protein degradation. We report that both indomethacin and ibuprofen improved body weight and weight of the gastrocnemius muscle in tumor-bearing mice. Ibuprofen increased the soluble protein content of the muscle without affecting muscle levels of phosphorylated p70 S6 kinase, a ribosomal kinase involved in protein synthesis. Paradoxically, indomethacin increased levels of ubiquitin-conjugated proteins. Further study is needed to understand the mechanism of action by which indomethacin and ibuprofen preserve body weight and muscle mass in the tumor-bearing mice. The data suggest that ibuprofen may have beneficial effects in the treatment of cancer cachexia.

Post-transcriptional regulation of gene expression by mitogen-activated protein kinase p38

The mitogen-activated protein kinase p38 pathway was originally identified as a signalling cascade activated by pro-inflammatory stimuli and cellular stresses, and playing a critical role in the translational regulation of pro-inflammatory cytokine synthesis. In almost a decade since this discovery, a great deal has been learned about the role of the p38 pathway in the post-transcriptional regulation of pro-inflammatory gene expression. However, important questions remain to be answered concerning the specificity and mechanism or mechanisms of action of p38. This review describes recent progress and remaining puzzles in the field of post-transcriptional regulation by p38.

Inhibition by eicosapentaenoic acid of IL-1beta-induced PGHS-2 expression in human microvascular endothelial cells: involvement of lipoxygenase-derived metabolites and p38 MAPK pathway

Prostaglandin H synthase 2 (PGHS-2), a highly inducible isoenzyme, is responsible for overproduction of the prostaglandins (PGs) in inflammatory sites. We established that among fish oil polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA), but not docosahexaenoic acid (DHA), greatly decreased interleukin-1beta (IL-1beta)-induced PGHS-2 expression in human pulmonary microvascular endothelial cells (HPMECs). Lipoxygenase products 12 (S)-hydroperoxyeicosapentaenoic acid ((S)-HpEPE), 15 (S)-HpEPE and leukotriene (LT) D5 reproduced similar inhibitory effect, suggesting that they may be the intermediate metabolites responsible for PGHS-2 down-regulation by EPA. Accordingly, the EPA effect is prevented by nordihydroguaiaretic acid (NDGA) and by REV 5901, nonspecific and specific 5-lipoxygenase inhibitors, respectively. Besides, inhibition of cyclooxygenase activity by ibuprofen, indomethacin or aspirin was not able to prevent this effect. Moreover, cyclooxygenase metabolites of EPA (PGs D3, E3 and I3) markedly potentiate IL-1beta-induced PGHS-2 expression, probably by increasing intracellular cAMP levels. Peroxisome proliferator-activated receptors (PPARs) are known to be activated by fatty acids (FAs) such as EPA. We found here that HPMECs express only weak amounts of PPARalpha and PPARgamma whose activation by synthetic agonists, Wy-14,643 and ciglitazone, does not cause any inhibition of IL-1beta-induced PGHS-2 expression. This finding ruled out the involvement of PPARs in the EPA inhibitory effect. In addition, we established that EPA, which failed to inhibit nuclear factor-kappaB (NF-kappaB) activation, suppressed p38 mitogen-activated protein kinase (MAPK) phosphorylation in stimulated HPMECs. Our data demonstrate that EPA, unlike DHA, down-regulates PGHS-2 expression in HPMECs probably through its 5-lipoxygenase-dependent metabolites and advocates a beneficial role for this FA in limiting inflammatory response.