Elevated Plasma Levels Of TNF-α Research Articles

Endoplasmic Reticulum Stress Promotes the Expression of TNF-α in THP-1 Cells by Mechanisms Involving ROS/CHOP/HIF-1α and MAPK/NF-κB Pathways.

Obesity and metabolic syndrome involve chronic low-grade inflammation called metabolic inflammation as well as metabolic derangements from increased endotoxin and free fatty acids. It is debated whether the endoplasmic reticulum (ER) stress in monocytic cells can contribute to amplify metabolic inflammation; if so, by which mechanism(s). To test this, metabolic stress was induced in THP-1 cells and primary human monocytes by treatments with lipopolysaccharide (LPS), palmitic acid (PA), or oleic acid (OA), in the presence or absence of the ER stressor thapsigargin (TG). Gene expression of tumor necrosis factor (TNF)-α and markers of ER/oxidative stress were determined by qRT-PCR, TNF-α protein by ELISA, reactive oxygen species (ROS) by DCFH-DA assay, hypoxia-inducible factor 1-alpha (HIF-1α), p38, extracellular signal-regulated kinase (ERK)-1,2, and nuclear factor kappa B (NF-κB) phosphorylation by immunoblotting, and insulin sensitivity by glucose-uptake assay. Regarding clinical analyses, adipose TNF-α was assessed using qRT-PCR/IHC and plasma TNF-α, high-sensitivity C-reactive protein (hs-CRP), malondialdehyde (MDA), and oxidized low-density lipoprotein (OX-LDL) via ELISA. We found that the cooperative interaction between metabolic and ER stresses promoted TNF-α, ROS, CCAAT-enhancer-binding protein homologous protein (CHOP), activating transcription factor 6 (ATF6), superoxide dismutase 2 (SOD2), and nuclear factor erythroid 2-related factor 2 (NRF2) expression (p ≤ 0.0183),. However, glucose uptake was not impaired. TNF-α amplification was dependent on HIF-1α stabilization and p38 MAPK/p65 NF-κB phosphorylation, while the MAPK/NF-κB pathway inhibitors and antioxidants/ROS scavengers such as curcumin, allopurinol, and apocynin attenuated the TNF-α production (p ≤ 0.05). Individuals with obesity displayed increased adipose TNF-α gene/protein expression as well as elevated plasma levels of TNF-α, CRP, MDA, and OX-LDL (p ≤ 0.05). Our findings support a metabolic-ER stress cooperativity model, favoring inflammation by triggering TNF-α production via the ROS/CHOP/HIF-1α and MAPK/NF-κB dependent mechanisms. This study also highlights the therapeutic potential of antioxidants in inflammatory conditions involving metabolic/ER stresses.

The polymorphism rs6918289 located in the downstream region of the TREM2 gene is associated with TNF-\u03b1 levels and IMT-F

Triggering receptor expressed on myeloid cells 2 (TREM2) is known for its anti-inflammatory properties during the immune response, and influences negatively on TNF-α expression levels. Genetic epidemiology studies have identified polymorphisms located in the TREM2 gene associated with neurodegenerative and chronic inflammatory diseases. TREM2 levels have been observed to affect plasma levels of TNF-α and plaque stability in symptomatic and asymptomatic patients with carotid stenosis. In this study, we investigated polymorphisms located in the TREM2 gene region and association with TNF-α levels and the intima media thickness of the femoral artery. The discovery population from the STANISLAS Family Study comprised of 809 individuals, whereas the replication population utilized an independent cohort of French origin (n = 916). Our results suggest that the minor allele (T) of SNP rs6918289 is positively associated with elevated plasma levels of TNF-α in discovery and replication populations (P = 0.0026, SE = 0.04 and P = 0.023, SE = 0.09, respectively), including femoral artery thickness in the discovery cohort (P = 0.026, SE = 0.009). Results indicate that rs6918289 may be considered as a risk factor for inflammatory diseases and could be used in stratified medicine with patients diagnosed with chronic inflammatory-related conditions, such as atherosclerosis.

Early postnatal respiratory viral infection induces structural and neurochemical changes in the neonatal piglet brain.

Infections that cause inflammation during the postnatal period are common, yet little is known about their impact on brain development in gyrencephalic species. To address this issue, we investigated brain development in domestic piglets which have brain growth and morphology similar to human infants, after experimentally infecting them with porcine reproductive and respiratory syndrome virus (PRRSV) to induce an interstitial pneumonia Piglets were inoculated with PRRSV on postnatal day (PD) 7 and magnetic resonance imaging (MRI) was used to assess brain macrostructure (voxel-based morphometry), microstructure (diffusion tensor imaging) and neurochemistry (MR-spectroscopy) at PD 29 or 30. PRRSV piglets exhibited signs of infection throughout the post-inoculation period and had elevated plasma levels of TNFα at the end of the study. PRRSV infection increased the volume of several components of the ventricular system including the cerebral aqueduct, fourth ventricle, and the lateral ventricles. Group comparisons between control and PRRSV piglets defined 8 areas where PRRSV piglets had less gray matter volume; 5 areas where PRRSV piglets had less white matter volume; and 4 relatively small areas where PRRSV piglets had more white matter. Of particular interest was a bilateral reduction in gray and white matter in the primary visual cortex. PRRSV piglets tended to have reduced fractional anisotropy in the corpus callosum. Additionally, N-acetylaspartate, creatine, and myo-inositol were decreased in the hippocampus of PRRSV piglets suggesting disrupted neuronal and glial health and energy imbalances. These findings show in a gyrencephalic species that early-life infection can affect brain growth and development.

Hepatic Mrp4 induction following acetaminophen exposure is dependent on Kupffer cell function

During acetaminophen (APAP) hepatotoxicity, increased expression of multidrug resistance-associated proteins 2, 3, and 4 (Mrp2-4) occurs. Mrp4 is the most significantly upregulated transporter in mouse liver following APAP treatment. Although the expression profiles of liver transporters following APAP hepatotoxicity are well characterized, the regulatory mechanisms contributing to these changes remain unknown. We hypothesized that Kupffer cell-derived mediators participate in the regulation of hepatic transporters during APAP toxicity. To investigate this, C57BL/6J mice were pretreated with clodronate liposomes (0.1 ml iv) to deplete Kupffer cells and then challenged with APAP (500 mg/kg ip). Liver injury was assessed by plasma alanine aminotransferase and hepatic transporter protein expression was determined by Western blot and immunohistochemistry. Depletion of Kupffer cells by liposomal clodronate increased susceptibility to APAP hepatotoxicity. Although increased expression of several efflux transporters was observed after APAP exposure, only Mrp4 was found to be differentially regulated following Kupffer cell depletion. At 48 and 72 h after APAP dosing, Mrp4 levels were increased by 10- and 33-fold, respectively, in mice receiving empty liposomes. Immunohistochemistry revealed Mrp4 staining confined to centrilobular hepatocytes. Remarkably, Kupffer cell depletion completely prevented Mrp4 induction by APAP. Elevated plasma levels of TNF-alpha and IL-1beta were also prevented by Kupffer cell depletion. These findings show that Kupffer cells protect the liver from APAP toxicity and that Kupffer cell mediators released in response to APAP are likely responsible for the induction of Mrp4.

Anti-inflammatory and lysosomal stability actions of Cleome gynandra L. studied in adjuvant induced arthritic rats

The present study was aimed to assess the anti-arthritic nature of Cleome gynandra L. (Cat’s whiskers) against Freund’s complete adjuvant induced arthritis in rats. The ethanolic extract of C. gynandra was administered orally at a dose of 150 mg/kg body weight for 30 days to the experimental rats after the induction of adjuvant arthritis. The anti-inflammatory activity of C. gynandra leaves was assessed by paw volume measurement, and its capacity to stabilize lysosomal enzyme activities in the plasma and liver of control and experimental rats. The activity of pathophysiological enzymes such as AST, ALT, ALP, cathepsin-D, β-glucuronidase, N-acetyl-β-glucosaminidase LDH and the levels of glycoproteins were also estimated in plasma and liver. The increased levels of both lysosomal enzymes and protein-bound carbohydrates in arthritic rats were significantly suppressed to near normal level by the administration of C. gynandra extract. Further, the significantly elevated plasma levels of TNF-α found in arthritic rats were found to be significantly restored back to near normal levels by the extract in experimental animals. The membrane stabilizing activity of the extract was further evidenced by histological observations made on the limb tissue. Recently, we have reported the presence of many biologically active phyto chemicals such as triterpenes, tannins, anthroquinones, flavonoids, saponins, steroids, resins, lectins, glycosides, sugars, phenolic compounds, and alkaloids in the extract of C. gynandra and these compounds might be responsible for the anti-arthritic properties observed in the present study. The possible mechanism of action of the C. gynandra extract may be through its stabilizing action on lysosomal membranes and there by preventing the spread of inflammation.

Involvement of Toll-like receptor 4 in acetaminophen hepatotoxicity

The objective of this study was to determine whether Toll-like receptor 4 (TLR4) has a role in alcohol-mediated acetaminophen (APAP) hepatotoxicity. TLR4 is involved in the inflammatory response to endotoxin. Others have found that ethanol-mediated liver disease is decreased in C3H/HeJ mice, which have a mutated TLR4 resulting in a decreased response to endotoxin compared with endotoxin-responsive mice. In the present study, short-term (1 wk) pretreatment with ethanol plus isopentanol, the predominant alcohols in alcoholic beverages, caused no histologically observed liver damage in either C3H/HeJ mice or endotoxin-responsive C3H/HeN mice, despite an increase in nitrotyrosine levels in the livers of C3H/HeN mice. In C3H/HeN mice pretreated with the alcohols, subsequent exposure to APAP caused a transient decrease in liver nitrotyrosine formation, possibly due to competitive interaction of peroxynitrite with APAP producing 3-nitroacetaminophen. Treatment with APAP alone resulted in steatosis in addition to congestion and necrosis in both C3H/HeN and C3H/HeJ mice, but the effects were more severe in endotoxin-responsive C3H/HeN mice. In alcohol-pretreated endotoxin-responsive C3H/HeN mice, subsequent exposure to APAP resulted in further increases in liver damage, including severe steatosis, associated with elevated plasma levels of TNF-alpha. In contrast, alcohol pretreatment of C3H/HeJ mice caused little to no increase in APAP hepatotoxicity and no increase in plasma TNF-alpha. Portal blood endotoxin levels were very low and were not detectably elevated by any of the treatments. In conclusion, this study implicates a role of TLR4 in APAP-mediated hepatotoxicity.

CD14 gene −260 C/T polymorphism is associated with chronic heart failure

Background Patients with chronic heart failure (CHF) show inflammatory changes and elevated plasma levels of TNFα and endotoxins. However, the role of the CD14 C(− 260)T polymorphism in patients with CHF is unclear. Therefore, we sought to determine whether the C = > T promoter polymorphism (position − 260) of the CD 14 gene is associated with a higher risk for the development of CHF. Methods We studied 100 patients with CHF (mean age 62 ± 3 years, LVEF 28 ± 8%) and 100 healthy controls (59 ± 10 years, p = NS; LVEF 60 ± 4%, p < 0.05). CD14 genotyping was performed using a PCR-RFLP technique. Results Among CHF patients, the frequency of the T allele was lower (38% vs. 48%, p < 0.05) and the frequency of the C allele higher (62 % vs. 52 %, p < 0.05) than among controls. The distribution of CD14 genotypes in healthy controls was as follows: CC 32%, CT 40%, and TT 28%. Among CHF patients, the TT genotype was significantly underrepresented compared to controls: CC 38%, CT 48%, and TT 14% ( p < 0.05). Conclusions The C − 260T polymorphism of CD14 seems to influence the susceptibility for the development of CHF. The T allele is less frequent among CHF patients than among controls. The TT genotype could be a new genetic protective factor against the development of CHF.

Reduced glucocorticoid sensitivity of monocyte interleukin-6 release in male employees with high plasma levels of tumor necrosis factor-α

Cytokine production by monocytes plays a key role in atherosclerosis. In vitro, preincubation of whole blood with tumor necrosis factor (TNF)-α regulates interleukin (IL)-6 release from monocytes stimulated with lipopolysaccharide (LPS). We investigated whether plasma levels of TNF-α would also relate to LPS-stimulated monocyte IL-6 production and the inhibitory effect of a glucocorticoid on this process. 224 middle-aged men were assigned to three groups according to tertiles of plasma levels of TNF-α. Subjects in the highest tertile (high TNF-α, n = 75) were compared to those in the lowest (low TNF-α, n = 74) and medium tertile (medium TNF-α, n = 75), respectively. In vitro monocyte IL-6 release following lipopolysaccharide (LPS)-stimulation was assessed with and without coincubation with incremental doses of dexamethasone. Monocyte glucocorticoid sensitivity was defined as the dexamethasone concentration inhibiting IL-6 release by 50%. Subjects with high TNF-α showed more IL-6 release after LPS-stimulation than those with low TNF-α (p = .011). Monocyte glucocorticoid sensitivity was lower in subjects with high levels of TNF-α than in subjects with low (p = .014) and with medium (p = .044) levels of TNF-α. Results held significance when a set of classic cardiovascular risk factors was controlled for. Our findings suggest that elevated plasma levels of TNF-α might enhance LPS-stimulated IL-6 release from circulating monocytes. Such a mechanism might contribute to exaggerated monocyte cytokine release in vivo to any LPS-like danger signal such as related to an infection or cellular stress thereby promoting atherosclerosis.

Expression of proinflammatory cytokines in the failing human heart: comparison of recent-onset and end-stage congestive heart failure

Background: Plasma levels of proinflammatory cytokines, including tumor necrosis factor (TNF)-α and interleukin (IL)-6, are elevated in patients with congestive heart failure (CHF). Recent studies suggest that the failing human heart is a source of proinflammatory cytokines in the end-stage failing heart. However, the relevance of plasma levels to those of the myocardium remains undefined. We sought to compare cytokine expression in early and end-stage CHF, and to evaluate the correlation of tissue expression to plasma levels. Methods Two patient populations were studied: patients with recent-onset CHF, all with symptoms less than 6 months ( n = 17, duration of symptoms 2.1 ± 1.6 months, range of New York Heart Association (NYHA) 1 to 3), and end-stage heart-failure patients ( n = 7) who underwent left-ventricular assist-device (LVAD) implantation (Duration of symptoms 47.1 ± 28.0 months, all NYHA class 4). Plasma levels of TNF-α and IL-6 proteins were evaluated by an Enzyme-Linked Immuno-Sorbent Assay (ELISA), while myocardial levels of cytokine transcripts were assessed by ribonuclease (Rnase) protection assay. Results In patients with end-stage heart failure, TNF-α and IL-6 were increased in the plasma as well as in the myocardium (plasma: TNF- α = 7.7 ± 2.3 pg/ml, IL-6 = 45.0 ± 47.1 pg/ml; myocardium: TNF-α = 0.31 ± 0.15% of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) expression, IL-6 = 1.56 ± 1.54% ). In contrast, despite elevated plasma levels of TNF-α and IL-6, the myocardium of patients with the recent onset of symptoms demonstrated minimal expression of TNF-α and IL-6 messenger ribonucleic acid (mRNA) (plasma: TNF-α = 4.3 ± 1.7 pg/ml, IL-6 = 3.3 ± 1.8 pg/ml; myocardium: TNF-α = 0.13 ± 0.04%, IL-6 = 0.02 ± 0.04%). Plasma levels of TNF-α were significantly correlated with those in the myocardium when both populations were combined. ( r = 0.69, p < 0.001) Conclusions Cytokines are expressed in the myocardium in end-stage heart failure to a much greater degree than in patients with the recent-onset of symptoms. This suggests that induction of cytokines in the myocardium is a relatively late event in the pathogenesis of CHF. Furthermore, plasma levels of TNF-α correlates with mRNA expression in the myocardium and thus may serve as an appropriate marker of myocardial cytokine activation. Whether the production of cytokines in the failing human heart precedes the elevation of cytokines in the plasma remains undefined. Therefore, we studied expression of TNF-α and IL-6 in the myocardium as well as in the plasma in patients with early and end-stage CHF. The results have demonstrated that cytokines are expressed in the myocardium in end-stage heart failure to a much greater degree than in patients with the recent onset of symptoms. This suggests that induction of cytokines in the myocardium is a relatively late event in the pathogenesis of CHF.