IKKalpha and IKKbeta function in TNFalpha-stimulated adhesion molecule expression in human aortic smooth muscle cells

IL-1β stimulates a novel, IKKα -dependent, NIK -independent activation of non-canonical NFκB signalling

In this study, we examined the activation of non-canonical nuclear factor Kappa B (NFκB) signalling in U2OS cells, a cellular metastatic bone cancer model. Whilst Lymphotoxin α1β2 (LTα₁β₂) stimulated the expected slow, delayed, sustained activation of serine 866/870 p100 phosphorylation and increased cellular expression of p52 NFκB, we found that canonical agonists, Interleukin-1β (IL-1β) and also Tumour necrosis factor-α (TNFα) generated a rapid transient increase in pp100, which was maximal by 15-30 min. This rapid phosphorylation was also observed in other cells types, such as DU145 and HCAECs suggesting the phenomenon is universal. IKKα deletion using CRISPR/Cas9 revealed an IKKα-dependent mechanism for serine 866/870 and additionally serine 872 p100 phosphorylation for both IL-1β and LTα₁β₂. In contrast, knockdown of IKKβ using siRNA or pharmacological inhibition of IKKβ activity was without effect on p100 phosphorylation. Pre-incubation of cells with the NFκB inducing-kinase (NIK) inhibitor, CW15337, had no effect on IL-1β induced phosphorylation of p100 however, the response to LTα₁β₂ was virtually abolished. Surprisingly IL-1β also stimulated p52 nuclear translocation as early as 60 min, this response and the concomitant p65 translocation was partially reduced by IKKα deletion. Furthermore, p52 nuclear translocation was unaffected by CW15337. In contrast, the response to LTα₁β₂ was essentially abolished by both IKKα deletion and CW15337. Taken together, these finding reveal novel forms of NFκB non-canonical signalling stimulated by ligands that activate the canonical NFκB pathway strongly such as IL-1β.

MiR-146a encapsulated liposomes reduce vascular inflammatory responses through decrease of ICAM-1 expression, macrophage activation, and foam cell formation

Vascular insults can create an inflammatory cascade involving endothelial cell, smooth muscle cell, and macrophage activation which can eventually lead to vascular disease such as atherosclerosis. Several studies have identified microRNA 146a's (miR-146a) anti-inflammatory potential based on its role in regulating the nuclear factor kappa beta (NF-κβ) pathway. Therefore, in this study, we introduced exogenous miR-146a encapsulated by liposomes to lipopolysaccharide (LPS) stimulated vascular cells and macrophages to reduce inflammatory responses. First, the miR-146a encapsulated liposomes showed uniform size (radius 96.4 ± 4.22 nm) and round shape, long term stability (at least two months), high encapsulation efficiency (69.73 ± 0.07%), and were well transfected to human aortic endothelial cells (HAECs), human aortic smooth muscle cells (SMCs), and human differentiated monocytes (U937 cells). In addition, we demonstrated that miR-146a encapsulated liposomes reduced vascular inflammation responses in HAECs and SMCs through inhibition of ICAM-1 expression and decreased monocyte adhesion. In macrophages, miR-146a liposome treatment demonstrated decreased production of proinflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β), as well as reduced oxidized low-density lipoprotein (ox-LDL) uptake and foam cell formation. Thus, based on these results, miR-146a encapsulated liposomes may be promising for reducing vascular inflammation by targeting its multiple associated mediators.

Inhibition of cytokine-mediated JNK signalling by purinergic P2Y11 receptors, a novel protective mechanism in endothelial cells

Previous research from our laboratory has demonstrated a novel phenomenon whereby GPCRs play a role in inhibiting cytokine-mediated c-Jun N-terminal kinase (JNK) signalling. So far this novel phenomenon seems to have been vastly overlooked, with little research in the area. Therefore, in this study we explored this further; by assessing the potential of P2YRs to mediate inhibition of cytokine-mediated JNK signalling and related functional outcomes in human endothelial cells. We utilised primary endothelial cells, and employed the use of endogenous activators of P2YRs and well characterised pharmacological inhibitors, to assess signalling parameters mediated by P2YRs, Interleukin-1β (IL-1β), TNFα and JNK. Activation of P2YRs with adenosine tri-phosphate (ATP) resulted in a time- and concentration-dependent inhibition of IL-1β-mediated phosphorylation of JNK and associated kinase activity. The effect was specific for cytokine-mediated JNK signalling, as ATP was without effect on JNK induced by other non-specific activators (e.g. sorbitol, anisomycin), nor effective against other MAPK pathways such as p38 and the canonical NFκB cascade. Pharmacological studies demonstrated a role for the P2Y₁₁ receptor in mediating this effect, but not the P2Y₁ nor the adenosine receptors (A1, A2A, A2B & A3). The novel Gα_q/11 inhibitor YM254890 and a protein kinase A (PKA) inhibitor H89 both partially reversed ATP-mediated inhibition of IL-1β-stimulated JNK indicating involvement of both Gα_q/11 and Gα_s mediated pathways. ATP also partially reversed IL-1β-mediated induction of cyclo‑oxygenase-2 (COX-2) and E-selectin. Collectively, these studies indicate the potential for activation of purinergic receptors to protect the endothelium from inflammatory driven JNK activation and may be a new target for inflammatory disease therapy.

Inhibitory Kappa B Kinase α (IKKα) Inhibitors That Recapitulate Their Selectivity in Cells against Isoform-Related Biomarkers

IKKβ plays a central role in the canonical NF-kB pathway, which has been extensively characterized. The role of IKKα in the noncanonical NF-kB pathway, and indeed in the canonical pathway as a complex with IKKβ, is less well understood. One major reason for this is the absence of chemical tools designed as selective inhibitors for IKKα over IKKβ. Herein, we report for the first time a series of novel, potent, and selective inhibitors of IKKα. We demonstrate effective target engagement and selectivity with IKKα in U2OS cells through inhibition of IKKα-driven p100 phosphorylation in the noncanonical NF-kB pathway without affecting IKKβ-dependent IKappa-Bα loss in the canonical pathway. These compounds represent the first chemical tools that can be used to further characterize the role of IKKα in cellular signaling, to dissect this from IKKβ and to validate it in its own right as a target in inflammatory diseases.

Cordycepin inhibits vascular adhesion molecule expression in TNF-α-stimulated vascular muscle cells

Atherosclerosis is a chronic inflammatory disease, which is associated with the increased expression of adhesion molecules in vascular smooth muscle cells (VSMCs). Cordycepin is one of the major bioactive components of Ophiocordyceps sinensis that has been demonstrated to exert anti-atherogenic activity; however, its molecular mechanisms are poorly understood. The aim of the present study was to examine the in vitro effects of cordycepin on the tumor necrosis factor (TNF)-α-induced suppression of adhesion molecule expression. The results of the present study demonstrated that cordycepin markedly inhibited the expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) in TNF-α-stimulated human aortic vascular smooth muscle cells (HA-VSMCs). Cordycepin significantly inhibited the TNF-α-induced mitogen-activated protein kinase (MAPK) and protein kinase B (Akt) activation (P<0.05), markedly inhibited the TNF-α-induced expression level of nuclear factor (NF)-κB p65 and markedly prevented the TNF-α-associated degradation of IκBα in HA-VSMCs. The results of the present study suggest that cordycepin inhibits the expression of VCAM-1 and ICAM-1 in TNF-α-stimulated HA-VSMCs via downregulating the MAPK/Akt/NF-κB signaling pathway. Therefore, cordycepin may have a potential therapeutic application for preventing the advancement of atherosclerotic lesions.

Dietary choline regulates antibacterial activity, inflammatory response and barrier function in the gills of grass carp (Ctenopharyngodon idella)

An 8-week feeding trial was conducted to determine the effects of graded levels of choline (197-1795 mg/kg) on antibacterial properties, inflammatory status and barrier function in the gills of grass carp. The results showed that optimal dietary choline supplementation significantly improved lysozyme and acid phosphatase activities, complement component 3 (C3) content, and the liver expressed antimicrobial peptide 2 and Hepcidin mRNA levels in the gills of fish (P < 0.05). In addition, appropriate dietary choline significantly decreased the oxidative damage, which might be partly due to increase copper, zinc superoxide dismutase (Cu/Zn-SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR) activities and increased glutathione content in the gills of fish (P < 0.05). Moreover, appropriate dietary choline significantly up-regulated the mRNA levels of interleukin 10 and transforming growth factor β1, Zonula occludens 1, Occludin, Claudin-b, c, 3 and 12, inhibitor of κBα, target of rapamycin, Cu/Zn-SOD, CAT, GR, GPx, GST and NF-E2-related factor 2 in the gills of fish (P < 0.05). Conversely, appropriate dietary choline significantly down-regulated the mRNA levels of pro-inflammatory cytokines, tumor necrosis factor α, interleukin 8, interferon γ, interleukin 1β, and related signaling factors, nuclear factor kappa B p65, IκB kinase β, IκB kinase γ, myosin light chain kinase and Kelch-like-ECH-associated protein 1a (Keap1a) in the gills of fish (P < 0.05). However, choline did not have a significant effect on the mRNA levels of IκB kinase α, Claudin-15 and Keap1b in the gills of fish. Collectively, appropriate dietary choline levels improved gill antibacterial properties and relative gene expression levels of tight junction proteins, and decreased inflammatory status, as well as up-regulated the mRNA levels of related signaling molecules in the gills of fish. Based on gill C3 content and AHR activity, the dietary choline requirements for young grass carp (266.5-787.1 g) were estimated to be 1191.0 and 1555.0 mg/kg diet, respectively.

Effects of total flavonoids from Dracocephalum moldavica on the proliferation, migration, and adhesion molecule expression of rat vascular smooth muscle cells induced by TNF-α

CONTEXT

Dracocephalum moldavica Linn (Labiatae) is one of the ethnomedicinal drugs of Uygur in Xinjiang, China. This herb is mainly used in treating cardiovascular diseases, such as atherosclerosis. However, the mechanism of pharmacological activity of D. moldavica has been poorly studied.

OBJECTIVE

To explore the pharmacological mechanism of D. moldavica in treating atherosclerosis by investigating the effects of total flavonoids from the aerial portion of D. moldavica on rat vascular smooth muscle cells (VSMCs).

MATERIALS AND METHODS

The proliferation and migration of VSMCs were evaluated via a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and transwell chamber experiment, respectively. The expression of proliferating cell nuclear antigen (PCNA), nuclear factor κB p65 (NF-κB p65), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) of VSMCs was determined using immunohistochemistry staining and quantitative real-time PCR (qRT-PCR).

RESULTS

Total flavonoids (IC(50) = 145.63 μg/mL) significantly inhibited tumor necrosis factor-α (TNF-α) induced VSMC proliferation at concentrations of 25, 50, and 100 μg/mL. Treatment with 50 and 100 μg/mL of total flavonoids also significantly inhibited TNF-α-induced VSMC migration, whereas 25 μg/mL of total flavonoids did not elicit any significant inhibitory effect. In addition, the effects of total flavonoids on inflammatory molecule expression of cells were tested by immunohistochemistry staining, showing that TNF-α-induced expression of PCNA, NF-κB p65, ICAM-1, and VCAM-1 in VSMCs was dose-dependently suppressed by total flavonoids. Furthermore, qRT-PCR data confirmed the inhibition of mRNA expressions of these inflammatory molecules.

DISCUSSION AND CONCLUSION

These data suggest that total flavonoids from D. moldavica exhibit anti-inflammatory activities, which is probably one of the underlying mechanisms of D. moldavica for clinical treatment of atherosclerosis.

Mild Hypothermia Attenuates Intercellular Adhesion Molecule-1 Induction via Activation of Extracellular Signal-Regulated Kinase-1/2 in a Focal Cerebral Ischemia Model

Intercellular adhesion molecule-1 (ICAM-1) in cerebral vascular endothelium induced by ischemic insult triggers leukocyte infiltration and inflammatory reaction. We investigated the mechanism of hypothermic suppression of ICAM-1 in a model of focal cerebral ischemia. Rats underwent 2 hours of middle cerebral artery occlusion and were kept at 37°C or 33°C during occlusion and rewarmed to normal temperature immediately after reperfusion. Under hypothermic condition, robust activation of extracellular signal-regulated kinase-1/2 (ERK1/2) was observed in vascular endothelium of ischemic brain. Hypothermic suppression of ICAM-1 was reversed by ERK1/2 inhibition. Phosphorylation of signal transducer and activator of transcription 3 (STAT3) in ischemic vessel was attenuated by hypothermia. STAT3 inhibitor suppressed ICAM-1 production induced by stroke. ERK1/2 inhibition enhanced phosphorylation and DNA binding activity of STAT3 in hypothermic condition. In this study, we demonstrated that hypothermic suppression of ICAM-1 induction is mediated by enhanced ERK1/2 activation and subsequent attenuation of STAT3 action.

Over-expression of mitogen-activated protein kinase phosphatase-2 enhances adhesion molecule expression and protects against apoptosis in human endothelial cells

BACKGROUND AND PURPOSE

We assessed the effects of over-expressing the dual-specific phosphatase, mitogen-activated protein (MAP) kinase phosphatase-2 (MKP-2), in human umbilical vein endothelial cells (HUVECs) on inflammatory protein expression and apoptosis, two key features of endothelial dysfunction in disease.

EXPERIMENTAL APPROACHES

We infected HUVECs for 40 h with an adenoviral version of MKP-2 (Adv.MKP-2). Tumour necrosis factor (TNF)-α-stimulated phosphorylation of MAP kinase and protein expression was measured by Western blotting. Cellular apoptosis was assayed by FACS.

KEY RESULTS

Infection with Adv.MKP-2 selectively abolished TNF-α-mediated c-Jun-N-terminal kinase (JNK) activation and had little effect upon extracellular signal-regulated kinase or p38 MAP kinase. Adv.MKP-2 abolished COX-2 expression, while induction of the endothelial cell adhesion molecules, intercellular adhesion molecule (ICAM) and vascular cell adhesion molecule (VCAM), two NFκB-dependent proteins, was not affected. However, when ICAM and VCAM expression was partly reduced by blockade of the NFκB pathway, Adv.MKP-2 was able to reverse this inhibition. This correlated with enhanced TNF-α-induced loss of the inhibitor of κB (IκB)α loss, a marker of NFκB activation. TNF-α in combination with NFκB blockade also increased HUVEC apoptosis; this was significantly reversed by Adv.MKP-2. Protein markers of cellular damage and apoptosis, H2AX phosphorylation and caspase-3 cleavage, were also reversed by MKP-2 over-expression.

CONCLUSIONS AND IMPLICATIONS

Over-expression of MKP-2 had different effects upon the expression of inflammatory proteins due to a reciprocal effect upon JNK and NFκB signalling, and also prevented TNF-α-mediated endothelial cell death. These properties may make Adv.MKP-2 a potentially useful future therapy in cardiovascular diseases where endothelial dysfunction is a feature.

Differential modulation of TLR3- and TLR4-mediated dendritic cell maturation and function by progesterone

The role of progesterone in modulating dendritic cell (DC) function following stimulation of different TLRs is relatively unknown. We compared the ability of progesterone to modulate murine bone marrow-derived DC cytokine production (IL-6 and IL-12) and costimulatory molecule expression (CD40, CD80, and CD86) induced by either TLR3 or TLR4 ligation and determined whether activity was via the progesterone receptor (PR) or glucocorticoid receptor (GR) by comparative studies with the PR-specific agonist norgestrel and the GR agonist dexamethasone. Progesterone was found to downregulate, albeit with different sensitivities, both TLR3- and TLR4-induced IL-6 production entirely via the GR, but IL-12p40 production via either the GR or PR. Of particular significance was that progesterone was able to significantly inhibit TLR3- but not TLR4-induced CD40 expression in bone marrow-derived DCs. Stimulation of the PR (with progesterone and norgestrel) by pretreatment of DCs was found to sustain IFN regulatory factor-3 phosphorylation following TLR3 ligation, but not TLR4 ligation. Overall, these studies demonstrate that progesterone can differentially regulate the signaling pathways employed by TLR3 and TLR4 agonists to affect costimulatory molecule expression and cytokine production.

Interleukin-1beta up-regulates RGS4 through the canonical IKK2/IkappaBalpha/NF-kappaB pathway in rabbit colonic smooth muscle

Initial Ca2+-dependent contraction of the intestinal smooth muscle mediated by G(q)-coupled receptors is attenuated by RGS4 (regulator of G-protein signalling 4). Treatment of colonic muscle cells with IL-1beta (interleukin-1beta) inhibits acetylcholine-stimulated initial contraction through increasing the expression of RGS4. NF-kappaB (nuclear factor kappaB) signalling is the dominant pathway activated by IL-1beta. In the present study we show that RGS4 is a new target gene regulated by IL-1beta/NF-kappaB signalling. Exposure of cultured rabbit colonic muscle cells to IL-1beta induced a rapid increase in RGS4 mRNA expression, which was abolished by pretreatment with a transcription inhibitor, actinomycin D, implying a transcription-dependent mechanism. Existence of the canonical IKK2 [IkappaB (inhibitor of NF-kappaB) kinase 2]/IkappaBalpha pathway of NF-kappaB activation induced by IL-1beta in rabbit colonic muscle cells was validated with multiple approaches, including the induction of reporter luciferase activity and endogenous NF-kappaB-target gene expression, NF-kappaB-DNA binding activity, p65 nuclear translocation, IkappaBalpha degradation and the phosphorylation of IKK2 at Ser(177/181) and p65 at Ser(536). RGS4 up-regulation by IL-1beta was blocked by selective inhibitors of IKK2, IkappaBalpha or NF-kappaB activation, by effective siRNA (small interfering RNA) of IKK2, and in cells expressing either the kinase-inactive IKK2 mutant (K44A) or the phosphorylation-deficient IkappaBalpha mutant (S32A/S36A). An IKK2-specific inhibitor or effective siRNA prevented IL-1beta-induced inhibition of acetylcholine-stimulated PLC-beta (phopsholipase C-beta) activation. These results suggest that the canonical IKK2/IkappaBalpha pathway of NF-kappaB activation mediates the up-regulation of RGS4 expression in response to IL-1beta and contributes to the inhibitory effect of IL-1beta on acetylcholine-stimulated PLC-beta-dependent initial contraction in rabbit colonic smooth muscle.

Soluble form of vascular cell adhesion molecule 1 induces migration and proliferation of vascular smooth muscle cells

BACKGROUND

Serum levels of soluble vascular cell adhesion molecule 1 (sVCAM-1) shed from its membrane-bound form are elevated in hypertension. This study clarified the effects of sVCAM-1 on vascular responses in rat aortic smooth muscle cells (RASMCs).

METHODS

Boyden chamber, 5-bromo-2'-deoxyuridine incorporation and ex vivo aortic ring assays for migration and proliferation, and Western blot for the kinase activity were used.

RESULTS

Spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) rats were compared functionally. sVCAM-1 increased RASMC migration and proliferation, which were greater in SHR compared with WKY rats. RASMCs expressed the very late antigen 4alpha receptor integrin with no difference between SHR and WKY rats. Inhibitors of phosphoinositide kinase 3 (PI3K) and spleen tyrosine kinase (Syk) and small interference RNA-Syk abolished the sVCAM-1-induced migration, proliferation and phosphorylation of focal adhesion kinase. The phosphorylation of Syk was significantly greater in RASMCs from SHR than from WKY rats. sVCAM-1 increased aortic sprout outgrowth, which was inhibited by inhibitors of PI3K and Syk.

CONCLUSIONS

This study suggests that sVCAM-1 promotes the RASMC migration and proliferation via the focal adhesion kinase pathway regulated by Syk and PI3K, and the altered sVCAM-1-induced responses during hypertension are closely associated with the increments in intracellular signal transmission.

Nuclear translocation of p65 NF-kappaB is sufficient for VCAM-1, but not ICAM-1, expression in TNF-stimulated smooth muscle cells: Differential requirement for PARP-1 expression and interaction

Although nuclear translocation of NF-kappaB and subsequent binding to promoters of ICAM-1 and VCAM-1 have been shown to be decisive for their expression, a number of discrepancies in the expression patterns of these adhesion molecules have been reported in both cell culture systems and disease settings, including atherosclerosis, asthma, and autoimmune diseases. Here we show that while p65 NF-kappaB nuclear translocation in TNF-treated smooth muscle cells (SMCs) was sufficient for the expression of VCAM-1, expression of ICAM-1 showed a critical requirement for PARP-1. I-kappaBalpha phosphorylation and subsequent degradation were virtually identical in both TNF-treated wild-type and PARP-1-/- SMCs. VCAM-1 expression in TNF-treated PARP-1-/- SMCs was completely inhibited by the NF-kappaB inhibitor, pyrrolidine dithiocarbamate, confirming that VCAM-1 expression was indeed NF-kappaB-dependent. The expression of both VCAM-1 and ICAM-1 was associated with a transient interaction between PARP-1 and p65 NF-kappaB when examined in the fibroblastic cell line, COS-7, and in the airway epithelial cell line, A549. Such interactions were confirmed using florescence resonance energy transfer analysis. Protein acetylation activity, mediated by p300/CBP, was required for both VCAM-1 and ICAM-1 expression in TNF-treated SMCs; however, the interaction of PARP-1 with p300/CBP was dispensable for VCAM-1 expression. These findings indicate that p65 NF-kappaB nuclear translocation may be sufficient for certain genes (e.g., VCAM-1) while insufficient for others (e.g., ICAM-1), thus providing a novel insight into the role of NF-kappaB in driving target gene expression. Furthermore, the data suggest a differential requirement for PARP-1 expression in inflammatory processes.

Atherogenic Lipids Induce Adhesion of Human Coronary Artery Smooth Muscle Cells to Macrophages by Up-regulating Chemokine CX3CL1 on Smooth Muscle Cells in a TNFα-NFκB-dependent Manner

Recent genetic evidence has implicated the adhesive chemokine CX3CL1 and its leukocyte receptor CX3CR1 in atherosclerosis. We previously proposed a mechanism involving foam cell anchorage to vascular smooth muscle cells because: 1) CX3CL1 and CX3CR1 are expressed by both cell types in mouse and human atherosclerotic lesions; 2) foam cells are reduced in lesions in cx3cr1(-/-)apoE(-/-) mice; and 3) proatherogenic lipids (oxidized low density lipoprotein [oxLDL] and oxidized linoleic acid derivatives) induce adhesion of primary human macrophages to primary human coronary artery smooth muscle cells (CASMCs) in vitro in a macrophage CX3CR1-dependent manner. Here we analyze this concept further by testing whether atherogenic lipids regulate expression and function of CX3CL1 and CX3CR1 on CASMCs. We found that both oxLDL and oxidized linoleic acid derivatives indirectly up-regulated CASMC CX3CL1 at both the protein and mRNA levels through an autocrine feedback loop involving tumor necrosis factor alpha production and NF-kappaB signaling. Oxidized lipids also up-regulated CASMC CX3CR1 but through a different mechanism. Oxidized lipid stimulation also increased adhesion of macrophages to CASMCs when CASMCs were stimulated prior to assay, and a synergistic pro-adhesive effect was observed when both cell types were prestimulated. Selective inhibition with a CX3CL1-specific blocking antibody indicated that adhesion was strongly CASMC CX3CL1-dependent. These findings support the hypothesis that CX3CR1 and CX3CL1 mediate heterotypic anchorage of foam cells to CASMCs in the context of atherosclerosis and suggest that this chemokine/chemokine receptor pair may be considered as a pro-inflammatory target for therapeutic intervention in atherosclerotic cardiovascular disease.