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Brain capillary endothelial cells are the component of blood brain barrier, and the first line of defense against viruses invading into brain. We demonstrate that treatment of hCMEC/D3 cells, a human brain capillary endothelial cell line, with a Toll-like receptor 3 (TLR3) agonist polyinosinic-polycytidylic acid (poly IC) induces the expression of interferon (IFN)-stimulated gene 60 (ISG60), and this reaction was mediated by IFN-β. Knockdown of ISG60 increased the poly IC-induced expression of IFN-β and an IFN-β-inducible chemokine CXCL10. This indicates that ISG60 constitutes a negative feedback loop in the downstream of TLR3/IFN-β. ISG60 in brain capillary endothelial cells may contribute to prevent excess immune reactions associated with viral infections., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Given the importance of neutrophil recruitment in the pathogenesis of glomerulonephritis (GN), the representative neutrophil chemoattractant C-X-C motif chemokine 1 (CXCL1)/GROα and the adhesion molecule E-selectin in glomerular endothelial cells (GECs) play a pivotal role in the development of GN. Endothelial Toll-like receptor 3 (TLR3) is thought to be involved in the inflammatory response via innate immunity. However, the role of endothelial TLR3 signaling in the expression of neutrophil chemoattractants and adhesion molecules remains to be elucidated. Thus, we aimed to examine this issue., Methods: We treated normal human GECs with polyinosinic-polycytidylic acid (poly IC), an authentic double-stranded RNA, and analyzed the expressions of CXCL1 and E-selectin using quantitative real-time reverse transcription-polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay. To further elucidate the poly IC-induced signaling pathway, we subjected the cells to RNA interference against TLR3, interferon (IFN)-β, nuclear factor (NF)-κB p65, and IFN regulatory factor (IRF) 3. We also used immunofluorescence to examine the endothelial expression of CXCL1 in biopsy specimens from patients with crescentic and non-crescentic purpura nephritis (PN)., Results: We found that the activation of TLR3 induced the endothelial expression of CXCL1 and E-selectin, and that this involved TLR3, -NF-κB, IRF3, and IFN-β. Intense endothelial CXCL1 expression was observed in biopsy specimens from patients with crescentic PN., Conclusion: These findings support a role for glomerular antiviral innate immunity in the pathogenesis of GN. Intervention of glomerular TLR3 signaling may therefore be a suitable therapeutic strategy for treating GN in the future., (© 2018 S. Karger AG, Basel.)

ISG20 is an ribonuclease specific for single-stranded RNA and considered to play a role in innate immunity against virus infections. We herein show that both poly IC, an authentic double-stranded RNA, and IFN-gamma induced ISG20 expression in cultured HUVEC. Poly IC-induced ISG20 expression was inhibited by LY294002, an inhibitor of PI3K, or by RNA interference against IFN regulatory factor three. ISG20 expression was not induced by IFN-beta, loxoribine or CpG oligonucleotide. These results suggest that ISG20 induction by poly IC may not be dependent on the IRF-3-mediated type I IFN induction pathway in HUVEC. ISG20 may be involved in innate immunity against viral infection in vascular endothelial cells.

Galectin-9 is a member of the galectin family, which induces various biological reactions such as chemotaxis of eosinophils and apoptosis of T cells. We previously reported that polyinosinic-polycytidylic acid (poly IC), an authentic double-stranded RNA (dsRNA), induces the expression of galectin-9 in human umbilical vein endothelial cells (HUVECs). In the present study, we addressed the possible involvement of two potential receptors for dsRNA, Toll-like receptor (TLR) 3 and retinoic acid-inducible gene-I (RIG-I), in the expression of galectin-9 in HUVECs. Poly IC-induced galectin-9 expression was almost completely suppressed by RNA interference (RNAi) against TLR3, but not against RIG-I. LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3K), inhibited the induction of galectin-9 by poly IC. RNAi against interferon regulatory factor 3 (IRF3) also inhibited poly IC-induced galectin-9 expression. We conclude that TLR3, PI3K, and IRF3 are involved in the poly IC-induced galectin-9 expression in HUVECs.

Mutations in the parkin gene are related with early-onset Parkinson's disease. Parkin is identified as an E3-ligase that combines target proteins with ubiquitin. alpha-Synuclein and synphilin-1 are substrates for E3-ligase activity of parkin and considered to be involved in the pathogenesis of Parkinson's disease. We previously demonstrated both alpha-synuclein and synphilin-1 are expressed in vascular endothelial cells (VEC). In the present study, we addressed possible expression of parkin in VEC. Parkin immunoreactivity was detected in vascular endothelial cells in postmortem human brain. Expressions of parkin mRNA and protein in human umbilical vein endothelial cells (HUVEC) were demonstrated by reverse-transcription polymerase-chain reaction (RT-PCR) and western blotting. Expression of parkin in HUVEC was not altered with tunicamycin treatment, which exerts unfolded protein stress on cells. We conclude that parkin is expressed in VEC, and that unfolded protein stress may not regulate its expression.

Epithelial neutrophil-activating peptide-78 (ENA-78) is a member of CXC chemokines. It is produced by endothelial cells stimulated with interleukin-1 (IL-1), along with other CXC chemokines such as IL-8 and growth-related oncogene protein-alpha (GRO-alpha). IL-1-induced ENA-78 production by endothelial cells may be important for the regulation of neutrophil activation. 15-Deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) is a natural ligand for peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and affects the expression of various genes. We examined the effect of 15d-PGJ(2) on the expression of ENA-78 in cultured endothelial cells stimulated with IL-1beta. 15d-PGJ(2) inhibited the IL-1beta-induced expression of ENA-78, but not the expression of IL-8 or GRO-alpha in response to IL-1. Ciglitazone, another agonist for PPAR-gamma, had no effect on the expression of ENA-78, suggesting that 15d-PGJ(2) may inhibit the expression of ENA-78 in a PPAR-gamma-independent manner. 15d-PGJ(2) may modulate inflammatory reactions by regulating the balance of CXC chemokines in endothelial cells.

CX3CL1/fractalkine is a chemokine with a unique CX3C motif. Hypoxia mediates the expression of various genes, such as vascular endothelial growth factor (VEGF), cyclooxygenase-2, and plasminogen-activator inhibitor-1, in vascular endothelial cells. We studied the effect of hypoxia on the expression of fractalkine induced by interferon-gamma (IFN-gamma) in endothelial cells. Human umbilical vein endothelial cells were cultured, and the stimulation of the cells with IFN-gamma was found to induce the expression of fractalkine. Hypoxia inhibited the expression of fractalkine mRNA and protein by IFN-gamma, and this effect was observed with concomitant increase in VEGF expression. Desferrioxamine, an iron chelator that mimics hypoxia in vitro, also inhibited the fractalkine production induced by IFN-gamma. Hypoxia did not affect the degradation of fractalkine mRNA. The inhibition of fractalkine expression by hypoxia was reversed on returning the cultures to reoxygenation condition. Inhibition of IFN-induced fractalkine expression by hypoxia was not affected by the presence of a radical scavenger, N-acetyl-L-cysteine, and the involvement of reactive oxygen species may be excluded. Inhibition of fractalkine expression by hypoxia may be involved in the pathophysiology of ischemic diseases.

Granulocyte-macrophage colony-stimulating factor (GM-CSF), one of major hematopoietic growth factors, activates mature leukocytes. GM-CSF is produced by endothelial cells stimulated with lipopolysaccharide (LPS), and the LPS-induced GM-CSF production may play an important role in the activation of neutrophils on the endothelial surface. 15-Deoxy-delta 12,14-prostaglandin J2 (15d-PGJ2) is a ligand for peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and modulates inflammatory reactions by regulating the expression of various genes. We studied the effect of 15d-PGJ2 on the LPS-induced GM-CSF expression in endothelial cells. Human umbilical vein endothelial cells (HUVEC) were cultured and the expressions of GM-CSF mRNA and protein were analyzed by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. 15d-PGJ2 inhibited the LPS-induced GM-CSF expression in a concentration-dependent manner; but ciglitazone, another agonist for PPAR-gamma, had no effect. This suggests that 15d-PGJ2 inhibits GM-CSF expression through a mechanism unrelated to PPAR-gamma. 15d-PGJ2 induced, by itself, the expression of interleukin-8, a potent proinflammatory chemokine, in HUVEC. 15d-PGJ2 may regulate inflammatory reactions by controlling the balance of various cytokines.

Objective: C‐C motif chemokine ligand 2 (CCL2) is a potent chemokine that plays an important role in host defense and inflammatory diseases in the central nervous system. Toll‐like receptor 3 (TLR3) is a pattern recognition receptor that recognizes viral double‐stranded RNAs. In the present study, we examined whether a TLR3 agonist induces CCL2 expression in brain microvascular endothelial cells, and investigated the mechanism underlying upregulation of CCL2 expression through TLR3 signaling. Methods: A human brain microvascular endothelial cell line, human cerebral microvascular endothelial cell (hCMEC)/D3 was treated with a TLR3 agonist, polyinosinic‐polycytidylic acid (poly IC). The mRNA and protein expression of CCL2 were evaluated using real‐time reverse transcription polymerase chain reaction and enzyme‐linked immunosorbent assay, respectively. The role of TLR3 and nuclear factor‐κB (NF‐κB) were examined with RNA interference. We also examined the effect of pretreatment with an NF‐κB inhibitor, SN50, an interferon regulatory factor 3 inhibitor MR67307 and human type I interferon neutralizing antibody mixture on poly IC‐induced CCL2 expression. Results: Expression of CCL2 was induced by poly IC. Poly IC‐induced CCL2 expression was decreased by knockdown of TLR3 or NF‐κB p65 and by pretreatment with SN50. Neither MR67307 nor human type I interferon neutralizing antibody mixture affected the CCL2 expression induced by poly IC. Conclusions: CCL2 expression was induced by poly IC through TLR3 signaling, and NF‐κB is involved in this reaction. CCL2 produced by human brain endothelial cells might induce the infiltration of monocytes followed by immune and inflammatory reactions in the brain, and could be involved in the pathogenesis of viral encephalitis. [ABSTRACT FROM AUTHOR]

Background/Aims: Dysregulation of interleukin-6 (IL-6) production in residual renal cells may play a pivotal role in the development of glomerulonephritis (GN). Given that Toll-like receptor 3 (TLR3) signaling has been implicated in the pathogenesis of some forms of GN, we examined activated TLR3-mediated IL-6 signaling in cultured normal human glomerular endothelial cells (GECs). Methods: We treated GECs with polyinosinic-polycytidylic acid (poly IC), an authentic double-stranded RNA, and analyzed the expression of IL-6 and the cytosolic viral RNA sensors retinoic acid-inducible gene-I (RIG-I) and melanoma differentiation associated gene 5 (MDA5) using reverse transcription quantitative real-time polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assays. To further elucidate the effects of poly IC on this signaling pathway, we subjected the cells to small interfering RNA (siRNA) against TLR3, interferon (IFN)-β, RIG-I, and MDA5. Results: We found that poly IC induced the expression of RIG-I, MDA5 and IL-6 via TLR3/IFN-β signaling in GECs. siRNA experiments revealed that both MDA5 and RIG-I were involved in the poly IC-induced expression of IL-6, with MDA5 being upstream of RIG-I. Conclusion : Interestingly, cytosolic sensors of viral RNA were found to be involved in IL-6 production via TLR3 signaling in GECs. Regional activation of TLR3/IFN-β/ MDA5/RIG-I/IL-6 axis due to viral and "pseudoviral" infections is involved in innate immunity and inflammatory reactions in GECs. We believe this signaling pathway also plays a pivotal role in the development of some forms of GN. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Brain microvascular endothelial cells (BMEC) are the major component of the blood–brain barrier, and play a critical role in protecting the brain from pathogens. Although Toll‐like receptor 3 (TLR3) is known as an important pattern‐recognition receptor against viral double‐stranded RNA, the downstream reactions of TLR3 in human BMEC are not fully characterized. The purpose of the present study was to investigate the role of TLR3 signaling in the expression of retinoic acid‐inducible gene‐I (RIG‐I), melanoma differentiation‐associated gene 5 (MDA5) and C‐X‐C motif chemokine ligand 10 (CXCL10) in human BMEC. Methods: The hCMEC/D3 cells, a human BMEC cell line, were cultured and stimulated with polyinosinic‐polycytidylic acid, a synthetic TLR3 agonist. Quantitative real‐time reverse transcription polymerase chain reaction, western blotting and enzyme‐linked immunosorbent assay were used to examine the expression of interferon‐β, RIG‐I and CXCL10. RNA interference against TLR3, interferon‐β, RIG‐I or MDA5 was also carried out. Results: Expression of RIG‐I, MDA5 and CXCL10 were induced by polyinosinic‐polycytidylic acid, and this was inhibited by knockdown of either TLR3 or interferon‐β. Knockdown of RIG‐I or MDA5 did not affect the CXCL10 expression in the early phase (4 h), but decreased the CXCL10 induction in the late phase (8 or 24 h). Conclusions: RIG‐I, MDA5 and CXCL10 are induced through TLR3 activation in hCMEC/D3 cells, and RIG‐I and MDA5 might function to enhance and/or prolong the reactions mediated by CXCL10. These molecules might play a distinct role in innate immune reactions against double‐stranded RNA viruses in human BMEC. [ABSTRACT FROM AUTHOR]

Objective Brain microvascular endothelial cells are one of the cell types that form the blood-brain barrier, and play an important role in the defense system of the brain. Toll-like receptor 3 ( TLR3) is a pattern-recognition receptor against double-stranded RNA, and TLR3 signaling is important in antiviral innate immune reactions. However, TLR3 signaling in brain microvascular endothelial cells is not well understood. We aimed to investigate the role of TLR3 signaling in chemokine CCL5 production in human brain microvascular endothelial cells. Methods The hCMEC/D3 human brain microvascular endothelial cells were cultured, and treated with an authentic TLR3 agonist polyinosinic : polycytidylic acid. The expression of CCL5 was examined using quantitative real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay. Involvement of TLR3, interferon ( IFN)-β, or IFN-λ1, IFN-regulatory factor 3 or nuclear factor-κB p65 in this reaction was examined using RNA interference. Translocation of p65 into the nucleus was examined using immunofluorescence staining. Results Treatment of cells with polyinosinic : polycytidylic acid induced the expression of CCL5, IFN-β and IFN-λ1, and also the translocation of p65 into the nucleus. Knockdown of TLR3, IFN-regulatory factor 3 or p65 inhibited the induction of these molecules, while knockdown of neither IFN-β nor IFN-λ1 affected the expression of CCL5. Conclusions TLR3 activation by polyinosinic : polycytidylic acid induces the expression of CCL5 in cultured hCMEC/D3 cells, and IFN-regulatory factor 3 and p65 are involved in this reaction. CCL5 induced by TLR3 signaling in brain microvascular endothelial cells might contribute to antiviral protective reactions and/or detrimental responses associated with viral infection in the brain. [ABSTRACT FROM AUTHOR]

Background: Galectin-9 is involved in chemotaxis and adhesion of eosinophils, and is induced in vascular endothelial cells by interferon-γ (IFN-γ). 15-Deoxy-Δ[sup 12,14] -prostaglandin J[sub 2] (15d-PGJ[sub 2] ) is a ligand for peroxisome proliferator-activated receptor-γ (PPAR-γ), and known to modulate the expression of various genes. Methods: We have studied the effect of 15d-PGJ[sub 2] on the IFN-γ-induced galectin-9 expression in human umbilical vein endothelial cells (HUVEC) in culture. Results: 15d-PGJ[sub 2] inhibited the IFN-γ-induced galectin-9 expression in a PPAR-γ-independent manner, and also inhibited the adhesion of EoL-1 cells to an HUVEC monolayer treated with IFN-γ. 15d-PGJ[sub 2] partially inhibited IFN-γ-induced phosphorylation of STAT-1 in HUVEC. Conclusions: 15d-PGJ[sub 2] may regulate inflammatory reactions through the inhibition of galectin-9 expression.Copyright © 2003 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Summary Peroxisome proliferator-activated receptor-γ (PPAR-γ)is a member of nuclear hormone receptor superfamily, and is knownto play a role in various biological processes including inflammatoryresponses and adipocyte differentiation. CX3CL1/fractalkineis a potent agonist for chemotaxis and adhesion of monocytes and lymphocytes.Endothelial cells produce fractalkine when stimulated with cytokinessuch as interleukin-1 (IL-1), tumour necrosis factor-α andinterferon-γ (IFN-γ). We herein report that 15-deoxy-n12,14 -prostaglandinJ2 (15d-PGJ2 ), a PPAR-γ agonist,inhibits the expression of fractalkine induced by IFN-γ orIL-1β in human endothelial cells. Agonist for PPAR-α (WY14643)or PPAR-γ (ciglitazone) did not inhibit the cytokine-inducedfractalkine expression, and the effect of 15d-PGJ2 maybe independent of PPAR. 15-Deoxy- D12,14 prostaglandinJ2 also inhibited the adhesion of blood mononuclear cellsto endothelial monolayers treated with IFN-γ or IL-1β.The data suggest that 15d-PGJ2 regulates inflammatoryreactions, at least in part, through the inhibition of fractalkineexpression and leucocyte traffic through the endothelium. [ABSTRACT FROM AUTHOR]

Summary Interleukin-6 (IL-6) is a multifunctional cytokine that plays an important role in inflammatory reactions. We have addressed the possible regulation of IL-6 expression by the ubiquitin-protease system in human umbilical vein endothelial cells. Cultured endothelial cells were treated with MG-132, a protease inhibitor, and the levels of IL-6 mRNA and protein were measured by reverse transcription-PCR and ELISA. MG-132 increased the expression of IL-6 mRNA and protein; and this effect was abolished by the pretreatment of the cells with U0126, an inhibitor of MAP or ERK kinases (MEK1/2). MG-132 treatment was also found to enhance the level of phosphorylated MEK1/2. Treatment of the cells with actinomycin D inhibited IL-6 expression in response to MG-132, suggesting the transcriptional upregulation of IL-6 under proteasomal inhibition. We conclude that a protease inhibitor MG-132 upregulates IL-6 expression in vascular endothelial cells, at least in part, through the activation of MEK1/2. [ABSTRACT FROM AUTHOR]

Abstract: Retinoic acid-inducible gene-I (RIG-I) is a member of the DExH box protein family and designated as a putative RNA helicase. RIG-I is implicated in host defense and inflammatory reactions by regulating the expression of various genes. RIG-I is expressed in endothelial cells and upregulated with lipopolysaccharide (LPS). Peroxisome proliferator-activated receptor-γ (PPAR-γ) is a nuclear hormone receptor and regulates gene expressions in response to its specific ligands. In the present study, we examined the effect of PPAR-γ ligands on the LPS-induced RIG-I expression in cultured human umbilical vein endothelial cells (HUVEC). 15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), a metabolite of PGD2, is a natural ligand for PPAR-γ and known to modulate inflammatory reactions by regulating the expression of various genes in PPAR-γ-dependent and -independent manners. LPS-induced RIG-I expression in HUVEC was inhibited by pretreatment of the cells with 15d-PGJ2 in time-and concentration-dependent manners. However, ciglitazone and bisphenol A diglycide ether, authentic and specific ligands for PPAR-γ, did not affect the RIG-I expression. These results suggest that 15d-PGJ2 inhibits LPS-induced RIG-I expression through a mechanism independent on PPAR-γ. 15d-PGJ2 may regulate inflammatory reactions, at least in part, by inhibiting the expression of RIG-I. [Copyright &y& Elsevier]

Growth related oncogene protein-α (GRO-α) is a member of C-X-C chemokine and plays an important role in inflammatory responses. Expression of GRO gene family is regulated by a number of factors at both transcriptional and posttranscriptional levels. In the present study, we have addressed the possible regulation of GRO-α expression by ubiquitin–proteasome system. Cultures of human umbilical vein endothelial cells were treated with a proteasome inhibitor, MG132, and the levels of GRO-α mRNA were analyzed by reverse transcription-polymerase chain reaction or northern blotting. Levels of GRO-α protein in the cell-conditioned medium were determined by enzyme-linked immunosorbent assay. MG132 alone increased the levels of GRO-α mRNA and protein; however, it did not affect the GRO-α mRNA induced by lipopolysaccharide (LPS) and inhibited the LPS-induced decrease in IκB levels. Other proteasome inhibitors, MG115 and lactacystin, also induced the expression of GRO-α mRNA. MG132 induced the phosphorylation of p38 MAPK, MEK and JNK. Pretreatment of the cells with SB203580, an inhibitor of p38 MAPK, suppressed the MG132-induced GRO-α expression, but pretreatment of the cells with U0126, PD98059 or SP600125, inhibitors of MEK1/2 or JNK, did not influence the effect of MG132. We conclude that MG132 upregulates GRO-α expression in vascular endothelial cells, at least in part, through the activation of p38 MAPK. [Copyright &y& Elsevier]

Granulocyte-macrophage colony-stimulating factor (GM-CSF), one of major hematopoietic growth factors, activates mature leukocytes. GM-CSF is produced by endothelial cells stimulated with lipopolysaccharide (LPS), and the LPS-induced GM-CSF production may play an important role in the activation of neutrophils on the endothelial surface. 15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) is a ligand for peroxisome proliferator-activated receptor-γ (PPAR-γ) and modulates inflammatory reactions by regulating the expression of various genes. We studied the effect of 15d-PGJ2 on the LPS-induced GM-CSF expression in endothelial cells. Human umbilical vein endothelial cells (HUVEC) were cultured and the expressions of GM-CSF mRNA and protein were analyzed by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. 15d-PGJ2 inhibited the LPS-induced GM-CSF expression in a concentration-dependent manner; but ciglitazone, another agonist for PPAR-γ, had no effect. This suggests that 15d-PGJ2 inhibits GM-CSF expression through a mechanism unrelated to PPAR-γ. 15d-PGJ2 induced, by itself, the expression of interleukin-8, a potent proinflammatory chemokine, in HUVEC. 15d-PGJ2 may regulate inflammatory reactions by controlling the balance of various cytokines. [Copyright &y& Elsevier]

α-Synuclein was originally identified as the precursor of non-amyloid β component of Alzheimer''s disease amyloid (NAC). NAC is detected in cerebral amyloid angiopathy; and we studied whether cerebral vascular cells express α-synuclein. Immunohistochemical studies of normal human cerebral tissues revealed the expression of α-synuclein in vascular endothelial and smooth muscle cells. Also cultures of human umbilical vein endothelial cells and umbilical artery smooth muscle cells were found, by reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis, to constitutively express α-synuclein mRNA. Western blot analysis disclosed the presence of α-synuclein protein in lysates of these cells. We conclude that vascular cells express α-synuclein, and it may play some role in the physiology of the vascular wall. [Copyright &y& Elsevier]

The non-amyloid β component of Alzheimer''s disease amyloid (NAC) is detected in cerebral amyloid angiopathy; and the precursor of NAC is now known to be identical to α-synuclein (α-S), a major component of Lewy bodies in Parkinson''s disease. We studied if cerebral vascular cells express α-S. Immunohistochemical studies of human cerebral tissues from control and cerebral amyloid angiopathy patients revealed the expression of α-S in vascular endothelial and smooth muscle cells. Then we studied the expression of α-S in vitro using cultures of vascular cells. Cultures of human umbilical vein endothelial cells and umbilical artery smooth muscle cells were found to constitutively express α-S messenger RNA and protein. α-S is normally expressed in vascular cells and may play some physiological role in the vascular wall. [Copyright &y& Elsevier]

Bacterial lipopolysaccharides (LPS) induce expression of multiple genes in endothelial cells, which are critical cellular effectors in various pathologic syndromes. Using subtractive hybridization to identify genes that are differentially induced in human endothelial cells treated with LPS, we found that retinoic acid-inducible gene I (RIG-I) is induced in endothelial cells stimulated with LPS. RIG-I encodes a protein belonging to the DExH-box family which has diverse roles in regulation of gene expression and cellular functions. Cyclooxygenase-2 (COX-2) is also induced in endothelial cells by LPS. Overexpression of RIG-I selectively upregulated expression of COX-2 and also induced COX-2 promoter activity. RIG-I is an inducible gene in stimulated endothelial cells that may have important roles in vascular pathology by virtue of its ability to regulate expression of the COX-2 gene product. [Copyright &y& Elsevier]