c-Jun N-terminal kinases inhibitor suppresses the TNF-alpha induced MCP-1 expression in human umbilical vein endothelial cells

Disruption of Lipid Raft Function Increases Expression and Secretion of Monocyte Chemoattractant Protein-1 in 3T3-L1 Adipocytes

The adipocyte is unique in its capacity to store lipids. In addition to triglycerides, the adipocyte stores a significant amount of cholesterol. Moreover, obese adipocytes are characterized by a redistribution of cholesterol with depleted cholesterol in the plasma membrane, suggesting that cholesterol perturbation may play a role in adipocyte dysfunction. We used methyl-β-cyclodextrin (MβCD), a molecule with high affinity for cholesterol, to rapidly deplete cholesterol level in differentiated 3T3-L1 adipocytes. We tested whether this perturbation altered adipocyte secretion of monocyte chemoattractant protein-1 (MCP-1), a chemokine that is elevated in obesity and is linked to obesity-associated chronic diseases. Depletion of cholesterol by MβCD increased MCP-1 secretion as well as the mRNA and protein levels, suggesting perturbation at biosynthesis and secretion. Pharmacological inhibition revealed that NF-κB, but not MEK, p38 and JNK, was involved in MβCD-stimulated MCP-1 biosynthesis and secretion in adipocytes. Finally, another cholesterol-binding drug, filipin, also induced MCP-1 secretion without altering membrane cholesterol level. Interestingly, both MβCD and filipin disturbed the integrity of lipid rafts, the membrane microdomains enriched in cholesterol. Thus, the depletion of membrane cholesterol in obese adipocytes may result in dysfunction of lipid rafts, leading to the elevation of proinflammatory signaling and MCP-1 secretion in adipocytes.

Antagonistic effects of endostatin-vascular endothelial growth inhibitor chimeric recombinant adenovirus on homocysteine-induced vascular endothelial cells injury in vitro and in vivo

BACKGROUND

The study is inclined to investigate the antagonistic effects of endostatin-vascular endothelial growth inhibitor chimeric recombinant adenovirus (Ad-hENDO-VEGI) on homocysteine (Hcy)-induced vascular endothelial cells (VECs) injury in vitro and in vivo.

METHODS

Human VECs cell line ECV304 was selected and infected with Ad-hENDO-VEGI. The LDH leakage, SOD activity, and MDA levels were measured by the automatic biochemical analyzer. Cell survival rate was counted by Trypanblau dying. The TNF-α and MCP-1 protein expressions were detected by ELISA assay. The protein expressions of fusion protein of Ad-hENDO-VEGI, nuclear factor kappa B p65 (NF-kappa B p65), and NF-kappa B inhibitor alpha (I-kappa B-α) were detected by Western blotting. A rat model of hyper-homocysteinemia was constructed. Thirty-six Wistar rats were randomly divided into 3 groups: the control group, the model group, and the Ad-hENDO-VEGI group. Serum Hcy levels in rats were measured with enzymatic cycling method. Endothelial vasodilation function was evaluated with the treatment of sodium nitroprusside and acetylcholine.

RESULTS

After Ad-hENDO-VEGI infection, high expressions (41 kD) of fusion proteins in ECV304 cells were observed. The injury severity of Hcy on ECV304 cells had a dose-dependent manner, and the injury reached a steady stage at 1.0 mmol/L. Thus, 1.0 mmol/L Hcy was selected for further experiments. With an increase of Ad-hENDO-VEGI in ECV304 cells after Hcy treatment, LDH leakage, MDA, TNF-α, MCP-1, and nuclear NF-kappa B p65 protein expression were gradually decreased, and cell survival rate, SOD activity, and I-kappa B-α protein expression were gradually increased. Compared with the control group, the model group had a higher Hcy level and attenuated vasodilator response. The Ad-hENDO-VEGI group exhibited a lower Hcy level and enhanced vasodilator response than the model group.

CONCLUSION

These results indicated that Ad-hENDO-VEGI could down-regulate NF-kappa B p65 expression and suppress inflammatory response, thereby alleviating Hcy-induced VECs injury.

Neuropharmacologic Approaches to Restore the Brain's Microenvironment

Maintaining the central nervous system microenvironment after injury, infection, inflammatory and degenerative diseases is contingent upon adequate control of glial homeostatic functions. Disease is caused by microbial, environmental and endogenous factors that compromise ongoing nervous system functions. The final result is neuronal injury, dropout and nerve connection loss, and these underlie the pathobiology of Alzheimer's and Parkinson's disease, amyotrophic lateral sclerosis, stroke, and bacterial, parasitic and viral infections. However, what promotes disease are homeostatic changes in the brain's microenvironment affected by innate glial immune pro-inflammatory and adaptive immune responses. These events disturb the brain's metabolic activities and communication abilities. How the process affects the brain's regulatory functions that can be harnessed for therapeutic gain is the subject at hand. Specific examples are provided that serve to modulate inflammation and improve disease outcomes specifically for HIV-associated neurocognitive disorders.

A β1/2 adrenergic receptor-sensitive intracellular signaling pathway modulates CCL2 production in cultured spinal astrocytes

The phosphorylation of c-jun N-terminal kinase (JNK) and the subsequent production of C-C chemokine CCL2 (monocyte chemoattractant protein; MCP-1) in spinal astrocytes contribute to the initiation of neurological disorders including chronic pain. Astrocytes express neurotransmitter receptors which could be targeted to ameliorate neurological disorders. In the current study, the involvement of the β-adrenergic system in the regulation of JNK activity and CCL2 production after stimulation with tumor necrosis factor (TNF)-α, one of many initiators of neuroinflammation, was elucidated. Treatment of cultured spinal astrocytes with isoproterenol (a β-adrenergic receptor agonist; 1 µM) reduced both TNF-α-induced JNK1 phosphorylation, as observed by Western blotting, and the subsequent increase of both CCL2 mRNA expression and CCL2 production, which were measured by real time-PCR and ELISA, respectively. The effects of isoproterenol were completely blocked by pretreatment with either propranolol (a β-adrenoceptor antagonist) or H89 (a protein kinase A [PKA] inhibitor). The current study revealed that the regulation of glycogen synthase kinase-3β (GSK-3β) activity is a crucial factor in the inhibitory action of isoproterenol. The TNF-α-induced JNK1 phosphorylation was significantly blocked by treatment with GSK-3β inhibitors (either LiCl or TWS119), and stimulation of β-adrenergic receptors induced the inhibition of GSK-3β through the phosphorylation of Ser(9) . Moreover, treatment with isoproterenol markedly suppressed the TNF-α-induced increase of CCL2 mRNA expression and CCL2 production through a β-adrenergic receptor-PKA pathway mediated by GSK-3β regulation. Thus, activation of β1/2 adrenergic receptors expressed in spinal astrocytes could be a novel method of moderating neurological disorders with endogenous catecholamines or selective agonists.

The JNK inhibitor XG-102 protects against TNBS-induced colitis

The c-Jun N-terminal kinase (JNK)-inhibiting peptide D-JNKI-1, syn. XG-102 was tested for its therapeutic potential in acute inflammatory bowel disease (IBD) in mice. Rectal instillation of the chemical irritant trinitrobenzene sulfonic acid (TNBS) provoked a dramatic acute inflammation in the colon of 7–9 weeks old mice. Coincident subcutaneous application of 100 µg/kg XG-102 significantly reduced the loss of body weight, rectal bleeding and diarrhoea. After 72 h, the end of the study, the colon was removed and immuno-histochemically analysed. XG-102 significantly reduced (i) pathological changes such as ulceration or crypt deformation, (ii) immune cell pathology such as infiltration and presence of CD3- and CD68-positive cells, (iii) the production of tumor necrosis factor (TNF)-α in colon tissue cultures from TNBS-treated mice, (iv) expression of Bim, Bax, FasL, p53, and activation of caspase 3, (v) complexation of JNK2 and Bim, and (vi) expression and activation of the JNK substrate and transcription factor c-Jun. A single application of subcutaneous XG-102 was at least as effective or even better depending on the outcome parameter as the daily oral application of sulfasalazine used for treatment of IBD.

The successful and substantial reduction of the severe, TNBS-evoked intestinal damages and clinical symptoms render the JNK-inhibiting peptide XG-102 a powerful therapeutic principle of IBD.

Rebuilding synaptic architecture in HIV-1 associated neurocognitive disease: a therapeutic strategy based on modulation of mixed lineage kinase

Work from our laboratories has validated mixed lineage kinase type 3 (MLK3) as an enzyme pathologically activated in the CNS by human immunodeficiency virus 1 (HIV-1) neurotoxins. In this review, we discuss MLK3 activation in the context of the neuropathogenesis of HIV-1 associated neurocognitive deficits (HAND). We use findings from the literature to substantiate the neuropathologic relevance of MLK3 to neurodegenerative disease, with an emphasis on Parkinson's disease that shares a number of important phenotypic and neuropathologic characteristics with HAND. We discuss signal transduction pathways downstream from MLK3 activation, with an emphasis on their involvement in microglia and neurons in preclinical models of HAND. Finally, we make a case for pharmacologic intervention targeted at inhibition of MLK3 as a strategy to reverse HAND, in light of the fact that combination antiretroviral therapy, despite successfully managing systemic infection of HIV-1, has been largely unsuccessful in eradicating HAND.

Vaspin can not inhibit TNF-alpha-induced inflammation of human umbilical vein endothelial cells

Visceral adipose tissue-derived serine protease inhibitor (vaspin) has been recently identified as an adipocytokine in a rat model of type 2 diabetes. Adipocytokines may directly influence the function of endothelial cells (ECs) and modulate inflammatory states. We therefore assessed the effects of vaspin on basal and TNF-alpha-stimulated human umbilical vein ECs. Vaspin (10-100 ng/ml, 24 hr) had no effects on both basal ECs morphology and TNF-alpha-induced (10 ng/ml, 24 hr) morphological damages. Vaspin did not inhibit the TNF-alpha (20 min) activation of JNK, p38 and NF-kappaB, but only slightly inhibited Akt. Furthermore, vaspin did not decrease the TNF-alpha (24 hr) induction of vascular cell adhesion molecule-1, intercellular adhesion molecule-1, endothelial selectin, and cyclooxygenase-2 protein expression as well as monocyte chemotactic protein-1, tissue factor, and plasmogen activator inhibitor-1 mRNA expression. The present results indicate that vaspin has no effects on normal ECs, and can not prevent TNF-alpha-induced inflammatory injury.

Generation of Site-Specific Retargeting Platform Cell Lines for Drug Discovery Using phiC31 and R4 Integrases

One of the challenges in developing cell lines for high-throughput screening in drug discovery is the labor- and time-intensive process required to create stable clonal cell lines that express specific reporters or drug targets. The authors report here the generation of a site-specific retargeting platform in 3 different cell lines: adherent HEK293, suspension CHO-S, and a human embryonic cell line (BGO1V). These platform cell lines were generated by using a combination of 2 site-specific integrases to develop a system that allows one to efficiently target a gene of interest to a specific locus and generates rapid production of homogeneous cell pools that stably express the gene of interest. The phiC31 integrase was used to create a platform line by placing a target site for the R4 integrase into a pseudo attP site, and then the R4 integrase was used to place a gene of interest into specific R4 target site. The authors demonstrate the successful and rapid retargeting of a G-protein-coupled receptor (cholecystokinin receptor A, CCKAR), an ion channel (the transient receptor potential cation channel, subfamily M, member 8, TRPM8), and a GFP-c-Jun(1-79) fusion protein into the specific loci in these cell lines and show that these retargeted cell lines exhibit functional and pharmacological responses consistent with those reported in the literature.

Inflammatory cytokines stimulate the chemokines CCL2/MCP-1 and CCL7/MCP-3 through NFkB and MAPK dependent pathways in rat astrocytes [corrected]

The chemokines CCL2 and CCL7 are upregulated in the brain during several neurodegenerative and acute diseases associated with infiltration of peripheral leukocytes. Astrocytes can respond to inflammatory cytokines like IL-1beta and TNF-alpha by producing chemokines. This study aims to test the ability of IL-1beta and TNF-alpha to stimulate CCL2 and CCL7 protein production in rat astrocyte cultures, and to elucidate signaling pathways involved in the cytokine-stimulated chemokine upregulation. Astrocytes were stimulated with IL-1beta or TNF-alpha, and CCL2 and CCL7 levels determined by ELISA. Our results show that IL-1beta and TNF-alpha each stimulate production of the chemokines CCL2 and CCL7 in astrocytes in a concentration- and time-dependent manner, with CCL2 showing a more rapid and robust response to the cytokine treatment than CCL7. As a first step to determine the signaling pathways involved in CCL2 and CCL7 upregulation, we stimulated astrocytes with IL-1beta or TNF-alpha in the presence of selective inhibitors of MAPK pathways (SB203580 and SB202190 for p38, SP600125 for JNK, and U0126 for ERK) or NFkappaB pathways (MG-132 and SC-514). We found that NFkappaB pathways are important for the cytokine-stimulated CCL2 and CCL7 production, whereas MAPK pathways involving p38 and JNK, but not ERK, may also contribute but to a lesser extent. These data document for the first time that CCL7 protein production can be stimulated in astrocytes by cytokines, and that the upregulation may involve NFkappaB- and p38/JNK-regulated pathways. In addition, our results suggest that CCL2 and CCL7 share similarities in the signaling pathways necessary for their upregulation.