Inflammatory Responses In Vascular Cells Research Articles

Jujuboside B Inhibited High Mobility Group Box Protein 1-Mediated Severe Inflammatory Responses in Human Endothelial Cells and Mice.

High mobility group box protein 1 (HMGB1) is a biomolecule that acts as an alerting signal of late sepsis by accelerating the production of proinflammatory cytokines, and eventually leads to various inflammation-related symptoms. When released into plasma at high concentration, it disrupts precise diagnosis and prognosis and worsens the survival of patients with systemic inflammatory conditions. Jujuboside B (JB) is a natural compound pressed from the seed of Zizyphi Spinosi Semen, which is known for its medical efficacies in treating various conditions such as hyperlipidemia, hypoxia, and platelet aggregation. Nevertheless, the medicinal activity of JB on HMGB1-involved inflammatory response in vascular cells in the human body is still ambiguous. Therefore, we hypothesized that JB could regulate the lipopolysaccharide (LPS)-induced dynamics of HMGB1 and its mediated cascade in inflammatory responses in human umbilical vein endothelial cells (HUVECs). In this experiment, JB and HMGB1 were administered in that order. In vitro and in vivo permeability, and cell viability, adhesion, and excavation of leukocytes, development of cell adhesion molecules, and lastly production of proinflammatory substances were investigated on human endothelial cells and mouse disease models to investigate the efficacy of JB in inflammatory condition. JB substantially blocked the translocation of HMGB1 from HUVECs and controlled HMGB1-induced adhesion and extravasation of the neutrophils through LPS-treated HUVECs. Moreover, JB decreased the formation of HMGB1 receptors and continually prevented HMGB1-induced proinflammatory mechanisms by blocking transcription of nuclear factor-κB and synthesis of tumor necrosis factor-α. In conclusion, JB demonstrated preventive effects against inflammatory pathologies and showed the potential to be a candidate substance for various inflammatory diseases by regulating HMGB1-mediated cellular signaling.

INFLUENCE OF OBESITY ON VASCULAR DYSFUNCTION AFTER TRAUMATIC HEMORRHAGE.

Background: Obesity increases the risk for morbidity and mortality after trauma. These complications are associated with profound vascular damage. Traumatic hemorrhage acutely attenuates vascular responsiveness, but the impact of obesity on this dysfunction is not known. The local inflammatory response in vascular cells is also unknown. We hypothesized that obesity potentiates trauma-induced vascular inflammation and dysfunction. Methods: Male Sprague-Dawley rats (~250 g) were fed normal chow (NC; 13.5% kcal fat, n = 20) or high-fat (HF; 60% kcal fat, n = 20) diets for 6 to 8 weeks. Under anesthesia, hemorrhage was induced by a mesenteric artery laceration, a Grade V splenic injury, and hypotension (MAP = 30-40 mm Hg) for 30 minutes. Vascular responsiveness was assessed ex vivo in isolated mesenteric arteries prehemorrhage and posthemorrhage. Gene expression for IL-1β, and IL-6, prooxidant nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2), and α-adrenergic receptor were assessed in carotid artery endothelial cells (ECs) and non-ECs (media + adventitia). Results: In NC rats, hemorrhage attenuated norepinephrine-induced vasoconstriction and endothelium-dependent vasodilation to acetylcholine. In HF rats, baseline norepinephrine-induced vasoconstriction was attenuated compared with NC, but vasoconstriction and endothelium-dependent vasodilation did not change prehemorrhage to posthemorrhage. Hemorrhage led to elevated IL-1β gene expression in ECs and elevated IL1β, IL-6, NOX2, and α-adrenergic receptor gene expression in the media + adventitia compared with sham. HF rats had greater EC IL-1 β and NOX2 gene expression compared with NC rats. The hemorrhage-induced elevation of IL-1β in the media + adventitia was greatest in HF rats. Conclusion: Traumatic hemorrhage attenuates vascular responsiveness and induces vascular inflammation. The attenuated vascular responsiveness after hemorrhage is absent in obese rats, while the elevated vascular inflammation persists. A HF diet amplifies the arterial inflammation after hemorrhage. Altered vascular responsiveness and vascular inflammation may contribute to worse outcomes in obese trauma patients.

Exacerbated Vascular Inflammation Following Traumatic Hemorrhage in Obese Rats

IntroductionObesity increases the risk for morbidity and mortality in trauma patients. These complications are associated with prolonged tissue hypoperfusion, hypercoagulability, and edema that reflect profound vascular damage. Traumatic hemorrhage acutely attenuates vascular responsiveness, but the degree of this dysfunction during the obese state is not known. Traumatic hemorrhage also increases circulating inflammatory cytokines; however, the local inflammatory response in vascular cells is unknown. We hypothesized that obesity potentiates trauma‐induced vascular inflammation and dysfunction.MethodsMale Sprague‐Dawley rats (~250g) fed either normal chow (NC; 13.5% kcal fat, n=20), moderate‐fat (MF; 33% kcal fat, n=20), or high‐fat (HF; 60% kcal fat, n=20) diet for 6‐8 weeks were assigned to a traumatic hemorrhage protocol or sham control. Under anesthesia, hemorrhage was induced by the laceration of a mesenteric artery and a Grade V splenic injury. Hypotension (mean arterial pressure = 30–40 mm Hg) was maintained for 30 minutes. Vasoconstrictor and vasodilator properties were assessed ex vivo in isolated mesenteric arteries pre‐ and post‐ hemorrhage. Carotid arteries collected after hemorrhage or sham control were flushed with trizol to collect endothelial cells (ECs). Gene expression was assessed in ECs and the remaining carotid artery (media + adventitia) cells for pro‐inflammatory interleukin (IL)‐1β, and IL‐6, pro‐oxidant NADPH oxidase 2 (NOX2), and α‐adrenergic receptor.ResultsIn NC rats, hemorrhage attenuated norepinephrine‐induced vasoconstriction and endothelium‐dependent dilation. This was accompanied by elevated IL‐1β expression in carotid artery ECs and elevated IL‐1β, IL‐6, NOX2, and α‐adrenergic receptor expression in the carotid artery media + adventitia post‐hemorrhage versus sham control. In MF and HF rats, norepinephrine‐induced vasoconstriction and endothelium‐dependent dilation did not change pre‐ to post‐hemorrhage. In sham animals, endothelial cell IL‐1β and NOX2 expression were higher in HF compared with NC rats. Similar to NC rats, the MF and HF rats had higher IL‐1β expression in carotid artery ECs, and IL‐1β, IL‐6, NOX2, and α‐adrenergic receptor expression in the carotid artery media + adventitia post‐hemorrhage compared with sham. The hemorrhage‐induced elevation of IL‐1β in carotid artery ECs and media + adventitia was greater in HF rats compared with NC and MF rats.ConclusionOur clinically‐relevant model of traumatic hemorrhage attenuates vascular responsiveness and induces vascular inflammation. The attenuated vascular responsiveness following hemorrhage is absent in MF and HF rats, while the elevated vascular inflammation persists. HF rats have an amplified arterial inflammatory response to hemorrhage, both in ECs and in cells of the media + adventitia. The augmented vascular inflammatory response to hemorrhage in HF rats may explain the worse outcomes in obese trauma patients.

Progerin-Induced Impairment in Wound Healing and Proliferation in Vascular Endothelial Cells

Progerin as a mutated isoform of lamin A protein was first known to induce premature atherosclerosis progression in patients with Hutchinson-Gilford progeria syndrome (HGPS), and its role in provoking an inflammatory response in vascular cells and accelerating cell senescence has been investigated recently. However, how progerin triggers endothelial dysfunction that often occurs at the early stage of atherosclerosis in a mechanical environment has not been studied intensively. Here, we generated a stable endothelial cell line that expressed progerin and examined its effects on endothelial wound repair under laminar flow. We found decreased wound healing rate in progerin-expressing ECs under higher shear stress compared with those under low shear. Furthermore, the decreased wound recovery could be due to reduced number of cells at late mitosis, suggesting potential interference by progerin with endothelial proliferation. These findings provided insights into how progerin affects endothelial mechanotransduction and may contribute to the disruption of endothelial integrity in HGPS vasculature, as we continue to examine the mechanistic effect of progerin in shear-induced endothelial functions.

C1q/TNF-related protein 1 promotes endothelial barrier dysfunction under disturbed flow

Endothelial hyper-permeability is a major determinant factor that contributes to the accelerated development of atherosclerotic lesions at hemodynamically disturbed sites. Previously, we showed that C1q/TNF related protein (CTRP) 1 promotes endothelium-leukocyte interactions and inflammatory responses in vascular cells. Here, we sought to investigate the role of CTRP1 in modulation of endothelial permeability under disturbed flow condition. By using en face staining of mouse aorta, we found CTRP1 expression was significantly increased in vascular endothelial cells under disturbed flow as compared to steady laminar flow. Vascular permeability to Evans blue dye was notably enhanced in CTRP1 knockin mice as compared to wild type animals, whereas aortic hyper-permeability at disturbed sites was remarkably restored after deletion of CTRP1. In cultured endothelial cells, treatment of CTRP1 led to increased permeability to fluorescent-labelled dextran and apparent formation of paracellular holes as observed after disturbed flow exposure, which was evidently reduced in the presence of a CTRP1-specific neutralizing antibody. Mechanistically, we found activation of VEGFR2 by CTRP1 might be involved in vascular hyper-permeability under disturbed flow condition. Taken together, this study suggests that CTRP1 is a mechano-sensitive proinflammatory factor that mediates disturbed flow-induced vascular barrier dysfunction. Inhibition of CTRP1 may inhibit the pathogenesis of atherosclerosis at early stage.

Protein Inhibitor of Activated STAT3 Suppresses Oxidized LDL-induced Cell Responses during Atherosclerosis in Apolipoprotein E-deficient Mice

Atherosclerosis is a serious public health concern. Excessive inflammatory responses of vascular cells are considered a pivotal pathogenesis mechanism underlying atherosclerosis development. It is known that Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signalling plays an important role in atherosclerosis progression. Protein inhibitor of activated STAT3 (PIAS3) is the key negative regulator of JAK/STAT3 signalling. However, its effect on atherogenesis is unknown. Here, we observed that PIAS3 levels are reduced in atherosclerotic lesions and that PIAS3 expression decreases in conjunction with increases in interleukin-6 expression and atherosclerosis severity. Oxidized low-density lipoprotein (ox-LDL), an atherogenic stimulus, reduced PIAS3 expression, an effect that may be attributed to nitric oxide synthesis upregulation. In turn, PIAS3 overexpression effectively suppressed ox-LDL-induced inflammation, lipid accumulation and vascular smooth muscle cell proliferation. These results indicate that PIAS3 is a critical repressor of atherosclerosis progression. The findings of this study have contributed to our understanding on the pathogenesis of atherosclerosis and have provided us with a potential target through which we can inhibit atherosclerosis-related cellular responses.

Virtual screening of RAGE inhibitors using molecular docking.

Advanced Glycation End products (AGEs) interaction with Receptor for AGEs (RAGE) activates downstream signaling and evokes inflammatory responses in vascular cells. Therefore, it is of interest to design a novel series of molecules with a library of 352 compounds based on natural Isoflavone and Argpyrimidine moities. The compounds screened against the optimized structure of RAGE (PDB code: 3CJJ) using MolDock aided with molecular docking algorithm. This exercise identified compound number 62 with appreciable ADME properties having no toxicity and pharmacophore features. Therefore, compound 62 identified as a RAGE inhibitor is proposed for further validation in the context of Diabetic Retinopathy (DR) and vascular complications.

MCP-1 binds to oxidized LDL and is carried by lipoprotein(a) in human plasma

Lipoprotein oxidation plays an important role in pathogenesis of atherosclerosis. Oxidized low density lipoprotein (OxLDL) induces profound inflammatory responses in vascular cells, such as production of monocyte chemoattractant protein-1 (MCP-1) [chemokine (C-C motif) ligand 2], a key chemokine in the initiation and progression of vascular inflammation. Here we demonstrate that OxLDL also binds MCP-1 and that the OxLDL-bound MCP-1 retains its ability to recruit monocytes. A human MCP-1 mutant in which basic amino acids Arg-18 and Lys-19 were replaced with Ala did not bind to OxLDL. The MCP-1 binding to OxLDL was inhibited by the monoclonal antibody E06, which binds oxidized phospholipids (OxPLs) in OxLDL. Because OxPLs are carried by lipoprotein(a) [Lp(a)] in human plasma, we tested to determine whether Lp(a) binds MCP-1. Recombinant wild-type but not mutant MCP-1 added to human plasma bound to Lp(a), and its binding was inhibited by E06. Lp(a) captured from human plasma contained MCP-1 and the Lp(a)-associated endogenous MCP-1 induced monocyte migration. These results demonstrate that OxLDL and Lp(a) bind MCP-1 in vitro and in vivo and that OxPLs are major determinants of the MCP-1 binding. The association of MCP-1 with OxLDL and Lp(a) may play a role in modulating monocyte trafficking during atherogenesis.

Antisense inhibition of apoB synthesis with mipomersen reduces plasma apoC-III and apoC-III-containing lipoproteins

Mipomersen, an antisense oligonucleotide that reduces hepatic production of apoB, has been shown in phase 2 studies to decrease plasma apoB, LDL cholesterol (LDL-C), and triglycerides. ApoC-III inhibits VLDL and LDL clearance, and it stimulates inflammatory responses in vascular cells. Concentrations of VLDL or LDL with apoC-III independently predict cardiovascular disease. We performed an exploratory posthoc analysis on a subset of hypercholesterolemic subjects obtained from a randomized controlled dose-ranging phase 2 study of mipomersen receiving 100, 200, or 300 mg/wk, or placebo for 13 wk (n = 8 each). ApoC-III-containing lipoproteins were isolated by immuno-affinity chromatography and ultracentrifugation. Mipomersen 200 and 300 mg/wk reduced total apoC-III from baseline by 6 mg/dl (38-42%) compared with placebo group (P < 0.01), and it reduced apoC-III in both apoB lipoproteins and HDL. Mipomersen 100, 200, and 300 mg doses reduced apoB concentration of LDL with apoC-III (27%, 38%, and 46%; P < 0.05). Mipomersen reduced apoC-III concentration in HDL. The drug had no effect on apoE concentration in total plasma and in apoB lipoproteins. In summary, antisense inhibition of apoB synthesis reduced plasma concentrations of apoC-III and apoC-III-containing lipoproteins. Lower concentrations of apoC-III and LDL with apoC-III are associated with reduced risk of coronary heart disease (CHD) in epidemiologic studies independent of traditional risk factors.

Aging Enhances the Basal Production of IL-6 and CCL2 in Vascular Smooth Muscle Cells

Increased circulating cytokine levels are a prominent feature of aging that may contribute to atherosclerosis. However, the role vascular cells play in chronic inflammation induced by aging is not clear. Here, we examined the role of aging on inflammatory responses of vascular cells. In an ex vivo culture system, we examined the inflammatory response of aortas from young (2-4 months) and aged (16-18 months) mice under nonstimulatory conditions. We found that basal levels of interleukin-6 were increased in aged aortas. Aged aortic vascular smooth muscle cells (VSMC) exhibited a higher basal secretion of interleukin-6 than young VSMC. Gene and protein expression analysis revealed that aged VSMC exhibited upregulation of chemokines (eg, CCL2), adhesion molecules (eg, intracellular adhesion molecule 1), and innate immune receptors (eg, Toll-like receptor [TLR] 4), which all contribute to atherosclerosis. Using VSMC from aged TL4(-/-) and Myd88(-/-) mice, we demonstrate that signaling via TLR4 and its signal adaptor, MyD88, are in part responsible for the age-elevated basal interleukin-6 response. Aging induces a proinflammatory phenotype in VSMC due in part to increased signaling of TLR4 and MyD88. Our results provide a potential explanation as to why aging leads to chronic inflammation and enhanced atherosclerosis.

Zinc induces chemokine and inflammatory cytokine release from human promonocytes

Our previous studies found that zinc oxide (ZnO) particles induced expression of intercellular adhesion molecule-1 (ICAM-1) protein in vascular endothelial cells via NF-κB and that zinc ions dissolved from ZnO particles might play the major role in the process. This study aimed to determine if zinc ions could cause inflammatory responses in a human promonocytic leukemia cell line HL-CZ. Conditioned media from the zinc-treated HL-CZ cells induced ICAM-1 protein expression in human umbilical vein endothelial cells (HUVEC). Zinc treatment induced chemokine and inflammatory cytokine release from HL-CZ cells. Inhibition of NFκB activity by over-expression of IκBα in HL-CZ cells did not block the conditioned medium-induced ICAM-1 protein expression in HUVEC cells. Zinc treatment induced activation of multiple immune response-related transcription factors in HL-CZ cells. These results clearly show that zinc ions induce chemokine and inflammatory cytokine release from human promonocytes, accompanied with activation of multiple immune response-related transcription factors. Our in vitro evidence in the zinc-induced inflammatory responses of vascular cells provides a critical linkage between zinc exposure and pathogenesis of those inflammatory vascular diseases.

Th17 response promotes angiotensin II-induced atherosclerosis

Vascular wall chronic inflammation plays a critical role in the development and progression of cardiovascular diseases such as atherosclerosis and hypertension. Circulating and tissue angiotensin II can induce potent inflammatory responses in vascular cells and promotes atherosclerosis, whereas the underlying mechanisms remain uncertain. Several data indicated that the upregulation of Th17 response has been found in the local atherosclerotic lesions and circulating lymphocytes in atherosclerosis prone models and the onset of acute coronary syndrome. Evidence from animal models shown that angiotensin II not only induced the Th1 response, but also amplified Th17 response. In addition, angiotensin II-induced hypertension and vascular dysfunction were abolished by blocking Th17/IL-17 effects. Therefore, we hypothesized that Th17 response may play an important role in angiotensin II-induced atherosclerosis.

Tissue Factor–Factor VIIa complex induces cytokine expression in coronary artery smooth muscle cells

Objective Within atherosclerotic lesions Tissue Factor (TF)–Factor VIIa (FVIIa) not only contributes to thrombotic events but also alters vascular remodeling through enhancement of migration. Moreover, the TF–FVIIa–FXa complex activates protease-activated receptors (PAR). TF/FVIIa/PAR-2 signaling has also been shown to promote proliferation and metastasis of tumor cells. Since coagulation factors promote inflammation which plays a major role during atherosclerosis as well as tumor metastasis this study sought to investigate the effects of FVIIa on the inflammatory response in vascular cells. Methods/results FVIIa induces interleukin-8 (IL-8) and IL-6 in primary smooth muscle cells (SMC), which was correlated to the expression of TF and PAR-2 as shown by immunoassay and qRT-PCR. The effect was dose-dependent and required TF, the proteolytic activity of FVIIa and PAR-2. Secondary effects of downstream coagulation factors were excluded. No proinflammatory FVIIa effect was observed in endothelial cells (EC) and mononuclear cells (MNC), expressing either TF or PAR-2. In atherosclerotic lesions mRNA expression of PAR-1, PAR-2 and IL-8 was elevated compared to healthy vessels indicating a role for PAR-1 and PAR-2 signaling in atherosclerosis. Conclusion In addition to the procoagulant and promigratory role of the TF–FVIIa complex we identify a proinflammatory role of FVIIa in human SMC dependent on expression of TF and PAR-2 that provides yet another link between coagulation and inflammation.

Increased CD74 expression in human atherosclerotic plaques: contribution to inflammatory responses in vascular cells

The purpose of this study was to analyse the expression of CD74 in human atherosclerotic plaques and peripheral blood mononuclear cells (PBMC) as well as its potential participation in proinflammatory responses in cultured human vascular smooth muscle cells (VSMC). CD74 expression was analysed in human atherosclerotic plaques (immunohistochemistry), PBMC (real-time PCR), and human aortic VSMC (real-time PCR and western blotting). Nuclear factor-kappaB (NF-kappaB) activation was assessed by southwestern histochemistry and electrophoretic mobility shift assay. Monocyte chemoattractant protein-1 (MCP-1) levels were studied by both real-time PCR and enzyme-linked immunosorbent assay. CD74 immunostaining was increased in the inflammatory vs. the fibrous region of atherosclerotic plaques (n = 70, 18.2 +/- 1.3 vs. 7.8 +/- 0.6% positive staining/mm2, P < 0.001). CD74 colocalized with the transcription factor NF-kappaB in both VSMC and macrophages. In cultured VSMC, CD74 expression was induced by interferon gamma (IFNgamma). Incubation with an agonistic anti-CD74 antibody or with IFNgamma elicited MCP-1 expression, which was prevented by AKT and gamma-secretase inhibitors. Moreover, CD74 small-interfering RNA decreased NF-kappaB activation and MCP-1 production induced by IFNgamma in VSMC. Finally, CD74 mRNA levels in PBMC from patients with carotid stenosis were higher than in healthy subjects (n = 20, 3 +/- 0.5 vs. 2 +/- 0.5 AU, P < 0.001). Additionally, a linear trend between CD74 mRNA expression tertiles and intima-media thickness (IMT) was observed in PBMC from asymptomatic subjects (n = 185, P < 0.001). CD74 levels are increased in plaques and PBMC from patients with carotid stenosis and are associated with IMT in subjects free from clinical cardiovascular diseases. CD74 could be a novel therapeutic target to decrease the inflammatory response in atherosclerosis.

Bradykinin regulates calpain and proinflammatory signaling through TRPM7-sensitive pathways in vascular smooth muscle cells

Transient receptor potential melastatin-7 (TRPM7) channels have recently been identified to be regulated by vasoactive agents acting through G protein-coupled receptors in vascular smooth muscle cells (VSMC). However, downstream targets and functional responses remain unclear. We investigated the subcellular localization of TRPM7 in VSMCs and questioned the role of TRPM7 in proinflammatory signaling by bradykinin. VSMCs from Wistar-Kyoto rats were studied. Cell fractionation by sucrose gradient and differential centrifugation demonstrated that in bradykinin-stimulated cells, TRPM7 localized in fractions corresponding to caveolae. Immunofluorescence confocal microscopy revealed that TRPM7 distributes along the cell membrane, that it has a reticular-type intracellular distribution, and that it colocalizes with flotillin-2, a marker of lipid rafts. Bradykinin increased expression of calpain, a TRPM7 target, and stimulated its cytosol/membrane translocation, an effect blocked by 2-APB (TRPM7 inhibitor) and U-73122 (phospholipase C inhibitor), but not by chelerythrine (PKC inhibitor). Expression of proinflammatory mediators VCAM-1 and cyclooxygenase-2 (COX-2) was time-dependently increased by bradykinin. This effect was blocked by Hoe-140 (B2 receptor blocker) and 2-APB. Our data demonstrate that in bradykinin-stimulated VSMCs: 1) TRPM7 is upregulated, 2) TRPM7 associates with cholesterol-rich microdomains, and 3) calpain and proinflammatory mediators VCAM-1 and COX2 are regulated, in part, via TRPM7- and phospholipase C-dependent pathways through B2 receptors. These findings identify a novel signaling pathway for bradykinin, which involves TRPM7. Such phenomena may play a role in bradykinin/B2 receptor-mediated inflammatory responses in vascular cells.

Homocysteine stimulates NADPH oxidase-mediated superoxide production leading to endothelial dysfunction in rats

Elevation of blood homocysteine (Hcy) levels (hyperhomocysteinemia) is a risk factor for cardiovascular disorders. We previously reported that oxidative stress contributed to Hcy-induced inflammatory response in vascular cells. In this study, we investigated whether NADPH oxidase was involved in Hcy-induced superoxide anion accumulation in the aorta, which leads to endothelial dysfunction during hyperhomocysteinemia. Hyperhomocysteinemia was induced in rats fed a high-methionine diet. NADPH oxidase activity and the levels of superoxide and peroxynitrite were markedly increased in aortas isolated from hyperhomocysteinemic rats. Expression of the NADPH oxidase subunit p22 phox increased significantly in these aortas. Administration of an NADPH oxidase inhibitor (apocynin) not only attenuated aortic superoxide and peroxynitrite to control levels but also restored endothelium-dependent relaxation in the aortas of hyperhomocysteinemic rats. Transfection of human endothelial cells or vascular smooth muscle cells with p22 phox siRNA to inhibit NADPH oxidase activation effectively abolished Hcy-induced superoxide anion production, thus indicating the direct involvement of NADPH oxidase in elevated superoxide generation in vascular cells. Taken together, these results suggest that Hcy-stimulated superoxide anion production in the vascular wall is mediated through the activation of NADPH oxidase, which leads to endothelial dysfunction during hyperhomocysteinemia.

Nitrated Fatty Acids: Endogenous Anti-inflammatory Signaling Mediators

Nitroalkene derivatives of linoleic acid (LNO2) and oleic acid (OA-NO2) are present; however, their biological functions remain to be fully defined. Herein, we report that LNO2 and OA-NO2 inhibit lipopolysaccharide-induced secretion of proinflammatory cytokines in macrophages independent of nitric oxide formation, peroxisome proliferator-activated receptor-gamma activation, or induction of heme oxygenase-1 expression. The electrophilic nature of fatty acid nitroalkene derivatives resulted in alkylation of recombinant NF-kappaB p65 protein in vitro and a similar reaction with p65 in intact macrophages. The nitroalkylation of p65 by fatty acid nitroalkene derivatives inhibited DNA binding activity and repressed NF-kappaB-dependent target gene expression. Moreover, nitroalkenes inhibited endothelial tumor necrosis factor-alpha-induced vascular cell adhesion molecule 1 expression and monocyte rolling and adhesion. These observations indicate that nitroalkenes such as LNO2 and OA-NO2, derived from reactions of unsaturated fatty acids and oxides of nitrogen, are a class of endogenous anti-inflammatory mediators.

Anti-atherogenic properties of fibrates may be largely due to their anti-inflammatory effects

Current understanding of the pathophysiology of atherosclerosis has undergone a remarkable evolution. Compelling evidence has evolved at both the basic science and clinical level for the importance of inflammation in the pathogenesis of atherosclerosis and its complications. Recent research has shown that both systemic and local inflammation plays a central role in all phases of the atherosclerotic process. Inflammatory cells dominate early atherosclerotic lesions, inflammatory cytokines accelerate progression of the lesions, and activation of inflammation can elicit acute coronary syndromes. Robust clinical studies have affirmed that fibrates are anti-atherogenic and can improve the cardiovascular risk profile. Fibrates not only modulate the serum concentrations of triglyceride and cholesterol, but also inhibit systemic inflammatory statue and inflammatory response in vascular cells. Fibrates act anti-inflammatory effects in monocyte/macrophage, T lymphocyte, endothelial cells, vascular smooth muscle cells and adipocytes. Since atherosclerosis is now regarded as an inflammatory disease and those inflammatory cells play critical important roles in the initiation and development of atherosclerosis, we hypothesize that anti-atherogenic properties of fibrates may be largely due to their anti-inflammatory effects.

Alzheimer's β-amyloid peptides induce inflammatory cascade in human vascular cells: the roles of cytokines and CD40

Accumulating evidence suggests that β-amyloid (Aβ)-induced inflammatory reactions may partially drive the pathogenesis of Alzheimer's disease (AD). Recent data also implicate similar inflammatory processes in cerebral amyloid angiopathy (CAA). To evaluate the roles of Aβ in the inflammatory processes in vascular tissues, we have tested the ability of Aβ to trigger inflammatory responses in cultured human vascular cells. We found that stimulation with Aβ dose-dependently increased the expression of CD40, and secretion of interferon-γ (IFN-γ) and interleukin-1β (IL-1β) in endothelial cells. Aβ also induced expression of IFN-γ receptor (IFN-γR) both in endothelial and smooth muscle cells. Characterization of the Aβ-induced inflammatory responses in the vascular cells showed that the ligation of CD40 further increased cytokine production and/or the expression of IFN-γR. Moreover, IL-1β and IFN-γ synergistically increased the Aβ-induced expression of CD40 and IFN-γR. We have recently found that Aβ induces expression of adhesion molecules, and that cytokine production and interaction of CD40–CD40 ligand (CD40L) further increase the Aβ-induced expression of adhesion molecules in these same cells. These results suggest that Aβ can function as an inflammatory stimulator to activate vascular cells and induces an auto-amplified inflammatory molecular cascade, through interactions among adhesion molecules, CD40–CD40L and cytokines. Additionally, Aβ 1–42, the more pathologic form of Aβ, induces much stronger effects in endothelial cells than in smooth muscle cells, while the reverse is true for Aβ 1–40. Collectively, these findings support the hypothesis that the Aβ-induced inflammatory responses in vascular cells may play a significant role in the pathogenesis of CAA and AD.

Minimally modified low density lipoprotein is biologically active in vivo in mice.

Minimally modified low density lipoprotein (MM-LDL), derived by mild iron oxidation or prolonged storage at 4 degrees C, has been shown to induce certain inflammatory responses in vascular cells in tissue culture. These include induction of monocyte (but not neutrophil) adherence to endothelial cells (EC), induction of EC production of colony stimulating factors (CSF), and induction of EC and smooth muscle cell production of monocyte chemotactic protein (MCP-1). To test for biologic activity in vivo, microgram quantities of MM-LDL were injected into mice, sera were assayed for CSF activity, and tissues were subjected to Northern analysis. After injection of MM-LDL, CSF activity increased approximately 7-26-fold but remained near control levels after injection of native LDL. Essentially all of the induced CSF activity was due to macrophage CSF as judged by antibody inhibition. Injection of MM-LDL into a mouse strain (C3H/HeJ) that is resistant to bacterial LPS gave similar results, indicating that the induction of CSF was not due to contaminating LPS and suggesting that there are differences in the pathways by which LPS and MM-LDL trigger cytokine production. In addition, after injection of MM-LDL, mRNA for JE, the mouse homologue of MCP-1, was markedly induced in various tissues, but was not induced after injection of native LDL. We conclude, therefore, that MM-LDL is biologically active in vivo and may contribute to the early stages of atherosclerosis by acting as an inflammatory agent.