Inhcer of β-Interferon

Platelet-Derived Extracellular Vesicles Increase Col8a1 Secretion and Vascular Stiffness in Intimal Injury

The arterial mechanical microenvironment, including stiffness, is a crucial pathophysiological feature of vascular remodeling, such as neointimal hyperplasia after carotid endarterectomy and balloon dilatation surgeries. In this study, we examined changes in neointimal stiffness in a Sprague-Dawley rat carotid artery intimal injury model and revealed that extracellular matrix (ECM) secretion and vascular stiffness were increased. Once the endothelial layer is damaged in vivo, activated platelets adhere to the intima and may secrete platelet-derived extracellular vesicles (pEVs) and communicate with vascular smooth muscle cells (VSMCs). In vitro, pEVs stimulated VSMCs to promote collagen secretion and cell adhesion. MRNA sequencing analysis of a carotid artery intimal injury model showed that ECM factors, including col8a1, col8a2, col12a1, and elastin, were upregulated. Subsequently, ingenuity pathway analysis (IPA) was used to examine the possible signaling pathways involved in the formation of ECM, of which the Akt pathway played a central role. In vitro, pEVs activated Akt signaling through the PIP₃ pathway and induced the production of Col8a1. MicroRNA (miR) sequencing of pEVs released from activated platelets revealed that 14 of the top 30 miRs in pEVs targeted PTEN, which could promote the activation of the Akt pathway. Further research showed that the most abundant miR targeting PTEN was miR-92a-3p, which promoted Col8a1 expression. Interestingly, knockdown of Col8a1 expression in vivo abrogated the increase in carotid artery stiffness and simultaneously increased the degree of neointimal hyperplasia. Our results revealed that pEVs may deliver miR-92a-3p to VSMCs to induce the production and secretion of Col8a1 via the PTEN/PIP3/Akt pathway, subsequently increasing vascular stiffness. Therefore, pEVs and key molecules may be potential therapeutic targets for treating neointimal hyperplasia.

A protective role of IRF3 and IRF7 signalling downstream TLRs in the development of vein graft disease via type I interferons

BACKGROUND

Toll like receptors (TLR) play an important role in vein graft disease (VGD). Interferon regulatory factors (IRF) 3 and 7 are the transcriptional regulators of type I interferons (IFN) and type I IFN responsive genes and are downstream factors of TLRs. Relatively little is known with regard to the interplay of IRFs and TLRs in VGD development. The aim of this study was to investigate the role of IRF3 and IRF7 signaling downstream TLRs and the effect of IRF3 and IRF7 in VGD.

METHODS AND RESULTS

In vitro activation of TLR3 induced IRF3 and IRF7 dependent IFNβ expression in bone marrow macrophages and vascular smooth muscle cells. Activation of TLR4 showed to regulate pro-inflammatory cytokines via IRF3. Vein graft surgery was performed in Irf3^-/- , Irf7^-/- and control mice. After 14 days Irf3^-/- vein grafts had an increased vessel wall thickness compared to both control (P = 0.01) and Irf7^-/- (P = 0.02) vein grafts. After 28 days, vessel wall thickness increased in Irf3^-/- (P = 0.0003) and Irf7^-/- (P = 0.04) compared to control vein grafts and also increased in Irf7^-/- compared to Irf3^-/- vein grafts (P = 0.02). Immunohistochemical analysis showed a significant higher influx of macrophages after 14 days in Irf3^-/- vein grafts and after 28 days in Irf7^-/- vein grafts compared to control vein grafts.

CONCLUSIONS

The present study is the first to describe a protective role of both IRF3 and IRF7 in VGD. IRFs regulate VGD downstream TLRs since Irf3^-/- and Irf7^-/- vein grafts show increased vessel wall thickening after respectively 14 and 28 days after surgery.

Differential Effects of IFN-β on the Survival and Growth of Human Vascular Smooth Muscle and Endothelial Cells

It has been documented that interferon (IFN)-β is effective against the genesis of atherosclerosis or hyperplastic arterial disease in animal model. The main mechanism of the efficacy was antiproliferative action on the growth of vascular smooth muscle cells (SMC). To understand more about the mechanisms that are responsible for the efficacy, we examined minutely the effects of IFN-β on the apoptosis and growth of vascular SMC and endothelial cells (EC). IFN-β enhanced SMC apoptosis in serum starved medium. Conversely, EC apoptosis induced by serum and growth factor deprivation was inhibited by IFN-β. The induction of SMC apoptosis and anti-apoptotic effect on EC linked to the expression of pro-apoptotic bax mRNA and caspase-3 activities. Anti-apoptotic bcl-2 mRNA was also up-regulated in EC. IFN-β inhibited SMC growth in a dose dependent manner. However, the growth of EC was rather enhanced by a low dose of IFNs. The antiproliferative effect on SMC associated with the activation of p21 and increase of G0/G1 arrested cells. The growth stimulation on EC was considered to link with increase of S and G2/M phase cells. SMC produced IFN-β in response to various stimulants. However, IFN-β was not induced in EC. These suggested that endogenous IFN-β from SMC may act on EC and affect to EC functions. In this study, it was clarified that IFN-β enhances SMC apoptosis and inhibits the EC apoptosis, and stimulates the EC growth. These effects were considered to contribute to a cure against hyperplastic arterial diseases as the mechanisms in the efficacy of IFN-β.

A20 regulates atherogenic interferon (IFN)-γ signaling in vascular cells by modulating basal IFNβ levels

IFNγ signaling in endothelial (EC) and smooth muscle cells (SMC) is a key culprit of pathologic vascular remodeling. The impact of NF-κB inhibitory protein A20 on IFNγ signaling in vascular cells remains unknown. In gain- and loss-of-function studies, A20 inversely regulated expression of IFNγ-induced atherogenic genes in human EC and SMC by modulating STAT1 transcription. In vivo, inadequate A20 expression in A20 heterozygote mice aggravated intimal hyperplasia following partial carotid artery ligation. This outcome uniquely associated with increased levels of Stat1 and super-induction of Ifnγ-dependent genes. Transcriptome analysis of the aortic media from A20 heterozygote versus wild-type mice revealed increased basal Ifnβ signaling as the likely cause for higher Stat1 transcription. We confirmed higher basal IFNβ levels in A20-silenced human SMC and showed that neutralization or knockdown of IFNβ abrogates heightened STAT1 levels in these cells. Upstream of IFNβ, A20-silenced EC and SMC demonstrated higher levels of phosphorylated/activated TANK-binding kinase-1 (TBK1), a regulator of IFNβ transcription. This suggested that A20 knockdown increased STAT1 transcription by enhancing TBK1 activation and subsequently basal IFNβ levels. Altogether, these results uncover A20 as a key physiologic regulator of atherogenic IFNγ/STAT1 signaling. This novel function of A20 added to its ability to inhibit nuclear factor-κB (NF-κB) activation solidifies its promise as an ideal therapeutic candidate for treatment and prevention of vascular diseases. In light of recently discovered A20/TNFAIP3 (TNFα-induced protein 3) single nucleotide polymorphisms that impart lower A20 expression or function, these results also qualify A20 as a reliable clinical biomarker for vascular risk assessment.

Interferon regulatory factor 3 protects against adverse neo-intima formation

AIMS

Vascular smooth muscle cell (VSMC) proliferation is central to the pathophysiology of neo-intima formation. Interferon regulatory factor 3 (IRF3) inhibits the growth of cancer cells and fibroblasts. However, the role of IRF3 in vascular neo-intima formation is unknown. We evaluated the protective role of IRF3 against neo-intima formation in mice and the underlying mechanisms.

METHODS AND RESULTS

IRF3 expression was down-regulated in VSMCs after carotid wire injury in vivo, and in SMCs after platelet-derived growth factor (PDGF)-BB challenge in vitro. Global knockout of IRF3 (IRF3-KO) led to accelerated neo-intima formation and proliferation of VSMCs, whereas the opposite was seen in SMC-specific IRF3 transgenic mice. Mechanistically, we identified IRF3 as a novel regulator of peroxisome proliferator-activated receptor γ (PPARγ), a negative regulator of SMC proliferation after vascular injury. Binding of IRF3 to the AB domain of PPARγ in the nucleus of SMCs facilitated PPARγ transactivation, resulting in decreased proliferation cell nuclear antigen expression and suppressed proliferation. Overexpression of wild-type, but not truncated, IRF3 with a mutated IRF association domain (IAD) retained the ability to exert anti-proliferative effect.

CONCLUSIONS

IRF3 inhibits VSMC proliferation and neo-intima formation after vascular injury through PPARγ activation.

Interferon-beta attenuates angiotensin II-accelerated atherosclerosis and vascular remodeling in apolipoprotein E deficient mice

Atherosclerotic vascular disease is an inflammatory disease. Interferon-beta (IFN-beta) is an important immune modulator. However, the role of IFN-beta in atherosclerotic vascular disease is still not clear. The present study is designed to determine the effects of IFN-beta on atherosclerosis, abdominal aortic aneurysm (AAA) formation and proliferative vascular remodeling in apolipoprotein E (apoE) deficient mice. Six-month-old male apoE deficient mice fed a normal chow underwent ligation of the common left carotid artery, and were randomly assigned to receive either vehicle or angiotensin II (Ang II, 1.4 mg/kg daily) via a subcutaneously implanted osmotic infusion pump. The animals were further assigned to groups that were subjected to subcutaneous injection of vehicle or murine IFN-beta (10 MIU/kg, daily). Ang II increased atherosclerotic area in the non-ligated carotid artery and aortic arch, induced AAA, and exacerbated ligation-induced adventitial proliferation and neointimal hyperplasia characterized by smooth muscle cell (SMC) proliferation and macrophage infiltration in the ligated carotid artery. Co-treatment with IFN-beta, had no effects by itself, significantly attenuated Ang II-accelerated increase in the areas of neointima, adventitia, SMC and macrophage in the ligated carotid artery and suppressed Ang II-exacerbated atherosclerosis, but did not affect Ang II-induced AAA formation. These data indicate that IFN-beta can play a prominent anti-atherosclerosis, anti-inflammation, and anti-proliferation role of vasculoprotection.

Applied gene therapy in preclinical models of vascular injury

Atherosclerosis remains the major cause of morbidity and mortality in Western countries. Atherothrombotic complications, including vascular occlusions and severe narrowing of nutrient blood vessels in the cerebral, coronary, or peripheral circulation, usually require invasive revascularization strategies. As molecular mediators contributing to these complications are being identified in more representative experimental injury models, and as gene transfer platforms and vectors acquire improved safety and efficacy profiles, there is ground for cautious optimism that gene-based interventions will likely reduce the clinical burden of these diseases. Increased generation of reactive oxygen species in diseased atherosclerotic vessels has been implicated in vasospasm, exaggerated neointima formation, and enhanced thrombosis. Ex vivo pressurized vascular gene transfer in venous bypass grafts using antisense oligonucleotides directed against cell-cycle control genes can modify the venous graft's phenotype and confer clinical benefit with improved long-term graft survival. Alternatively, percutaneous intra-arterial gene transfer is feasible, but at relatively low transgene expression levels. Although this may suffice in the case of secreted gene products with marked paracrine or bystander effects, including nitric oxide synthase and heme oxygenase-1, drug- and gene-eluting stents may provide the preferred future vehicle for well-controlled, quantifiable, and safe vascular gene transfer. Continued efforts to improve gene transfer technology in diseased human vessels and to increase our understanding of molecular targets are required before the full therapeutic potential of vascular gene therapy can be realized.

Influence of Class I interferons on performance of vascular cells on stent material in vitro

PURPOSE

Numerous reports suggest that Class 1 interferons (IFNs), particularly IFN-gamma, inhibit migration and proliferation of different types of human cells. The objective of the present study was to determine the effect of Class I IFNs on viability and growth characteristics of human aortic endothelial cells (ECs), smooth muscle cells (SMC) and fibroblasts (FBs) in vitro.

METHODS

Stainless-steel (316-l) disks were coated with fibrin meshwork containing IFN-gamma or IFN-alpha. The discs and IFN embedded meshwork were incubated with human EC, SMC and FB, and then cultured, whereas control cells were seeded onto uncoated surfaces or plain fibrin meshwork. Concentrations of recombinant IFN varied from 5 to 20 ng/cm(2). Assessment of effect on cell viability, growth and attachment was performed utilizing Alamar Blue (AB) assay. Cell morphology was assessed by scanning electron microscopy (SEM).

RESULTS

We have now shown inhibitory capacity of IFN-gamma on all three types of unstimulated cells. The growth-inhibitory effect was maximal with SMC, while it was minimal with FB and EC. IFN-gamma abrogated mitogenic responses of SMC but not EC and partially FB to VEGF and FGF stimulation. IFN-alpha was able to inhibit EC growth and, to a lesser extent, FB, and did influence growth rates of SMC. Biochemical analysis of lactate dehydrogenase activity suggested that IFN was not toxic to vascular cells. We also measured the expression of cell adhesive molecules: P- and E-selections, PECAM and ICAM-1. These molecules were upregulated by IFN in EC. Media derived from quiescent human SMC displayed low immunoreactive elastase activity, while conditional media after IFN-gamma treatment but not IFN-alpha treatment had approximately a threefold greater activity.

CONCLUSION

These data suggest that IFN-gamma significantly inhibits SMC growth in the absence of significant endothelial toxicity and is dose-dependent; however, animal experiments are needed to further explore the antirestenotic effects of IFNs.

Interferon-beta induction by Chlamydia pneumoniae in human smooth muscle cells

Clinical studies have suggested a causal or contributory role of Chlamydia pneumoniae infection in asthma and atherosclerosis. The activation of synthetic functions of smooth muscle cells (SMC) including the production of cytokines and growth factors plays a major role in the formation of fibrous atherosclerotic plaques as well as in structural remodelling of the airway wall in chronic asthma. In this study we demonstrated that C. pneumoniae induced the production of low levels of interferon (IFN)-beta in bronchial and vascular SMC when infected cells were treated with tumour necrosis factor-alpha (TNF-alpha). IFN-beta production was analysed by reverse transcription-PCR and enzyme-linked immunosorbent assay. The upregulation of IFN-beta was paralleled by an increase in mRNA levels of interferon regulatory factor-1 and interferon-stimulated gene factor 3gamma, two transcription factors activating the expression of the IFN-beta gene. In addition, C. pneumoniae infection enhanced the mRNA level of indoleamine 2,3-dioxygenase, an IFN-inducible factor mediating the restriction of intracellular chlamydial growth, in TNF-alpha-stimulated SMC. C. pneumoniae-induced IFN-beta production by SMC may modulate inflammation and tissue remodelling during respiratory and vascular infection.

Folate supplementation inhibits intimal hyperplasia induced by a high-homocysteine diet in a rat carotid endarterectomy model

OBJECTIVE

Hyperhomocysteinemia has been implicated as a causative factor in intimal hyperplasia development. The addition of dietary folate in a hyperhomocysteinemia, carotid endarterectomy rat model is postulated to decrease plasma homocysteine levels and, in turn, reduce post-carotid endarterectomy intimal hyperplasia.

METHODS

Each rat was fed one of six diets: (1) lab chow with no folate (n = 7), (2) lab chow with 10 mg/kg folate added (n = 3), (3) lab chow with 25 mg/kg folate added (n = 3), (4) a homocysteine diet with no folate (n = 7), (5) a homocysteine diet with 10 mg/kg folate added (n = 5), or (6) homocysteine diet with 25 mg/kg folate added (n = 5). Each rat then underwent an open carotid endarterectomy. In 2 weeks, intimal hyperplasia in the carotid artery was measured. Plasma homocysteine and folate levels were measured.

RESULTS

Plasma folate levels rose with folate administration. Plasma homocysteine in the lab chow group was 5.4 +/- 0.5 micromol/L and did not change with the addition of folate. In the homocysteine diet group, plasma homocysteine rose 10-fold over the lab chow group (51.9 +/- 6.5 vs 5.4 +/- 0.5, micromol/L, P <.0001). In the group fed a homocysteine diet with 10 mg/kg folate added, a significant decrease in plasma homocysteine was observed (17.5 +/- 8.5 vs 51.9 +/- 6.5, micromol/L, P =.0003). In the group fed a homocysteine diet with 25 mg/kg folate added, plasma homocysteine levels were further reduced to levels seen in the lab chow group (12.6 +/- 2.6 vs 5.4 +/- 0.5, micromol/L, P = not significant). The relationship between plasma folate and homocysteine was inverse (R = 0.39, P =.0036). Luminal stenosis due to intimal hyperplasia was minimal in lab chow groups and unaffected by folate. The homocysteine diet group demonstrated post-carotid endarterectomy luminal stenosis due to intimal hyperplasia (60.9% +/- 9.2%). In the group fed a homocysteine diet with 10 mg/kg folate added, intimal hyperplasia was reduced, compared with the homocysteine diet group (32.6% +/- 7.4% vs 60.9% +/- 9.2%, P =.009). In the group fed a homocysteine diet with 25 mg/kg folate added, intimal hyperplasia was reduced to lab chow group levels (10.8% +/- 0.8% vs 4.8% +/- 1.0%, P = not significant) and was reduced, compared with the group fed a homocysteine diet with 10 mg/kg folate added.

CONCLUSION

The use of folate in this hyperhomocysteinemia carotid endarterectomy model and the resultant attenuation of plasma homocysteine elevation and intimal hyperplasia development lend strong support to homocysteine being an independent etiologic factor in post-carotid endarterectomy intimal hyperplasia.

COP-1, a member of the CCN family, is a heparin-induced growth arrest specific gene in vascular smooth muscle cells

Vascular smooth muscle cell (VSMC) hyperplasia is responsible for the failure of 15-30% of vascular surgical procedures such as coronary artery bypass grafts and angioplasties. We and others have shown that heparin suppresses VSMC proliferation in vivo and in cell culture. We hypothesize that heparin inhibits VSMC proliferation by binding to cell surface receptors, resulting in selective modulation of mitogenic signal transduction pathways and altered transcription of a specific subset of growth regulatory genes. To test this idea, we used subtractive hybridization to identify differentially expressed mRNAs in heparin-treated and untreated VSMC. We identified a heparin induced mRNA identical to Cop-1, a member of the CCN family of proteins which are secreted, cysteine-rich modular proteins involved in growth regulation and migration. Cop-1 from smooth muscle cells appears to have a different expression pattern and possibly different functions than Cop-1 from other cells. Cop-1 mRNA is expressed at high levels in quiescent VSMC and at low levels in proliferating VSMC, an expression pattern highly characteristic of growth arrest specific genes. Cop-1 mRNA is expressed at high levels in heparin treated VSMC and COP-1 protein is secreted into culture medium. In tissues, Cop-1 expression is observed in the uninjured rat aorta suggesting a possible role for Cop-1 in vivo. We found PDGF, but not EGF, inhibits the expression of Cop-1 in VSMC. Neither TGF-beta nor interferon-beta, two inhibitors of VSMC proliferation, were able to induce Cop-1 expression. In addition, heparin does not induce Cop-1 mRNA in endothelial cells and VSMC resistant to the antiproliferative effect of heparin. Conditioned medium from cells over-expressing COP-1 protein inhibits VSMC proliferation in culture. Together, our data indicate that COP-1 may play a role in the antiproliferative mechanism of action of heparin.

Restenosis and gene therapy

Atherosclerosis is one of the main causes of mortality and morbidity in westernised countries. Treatment of symptomatic atherosclerosis by angioplasty involves major vascular responses such as neointima formation and constrictive vascular remodelling leading to restenosis. Stent placement prevents vasoconstriction but is associated with in-stent neointima formation. Therefore, stent placement requires adjunctive therapy. In this review we discuss the potential of local gene therapy for restenosis. More particularly, we focus on strategies to inhibit smooth muscle cell (SMC) proliferation and migration, prevent thrombosis, decrease oxidative stress in the arterial wall and enhance re-endothelialisation associated with adaptive remodelling. The potential of different vector systems and devices for local gene transfer in the arterial wall is discussed.

Novel approaches for the prevention of restenosis

Restenosis, the re-narrowing of the lumen of the coronary artery, in the months following a successful percutaneous balloon angioplasty or stenting, remains the main limitation to percutaneous coronary revascularisation. Serial intravascular ultrasound studies have shown that restenosis after conventional balloon angioplasty represents a complex interplay between elastic recoil, smooth muscle proliferation and vascular remodelling, while restenosis after stent deployment is due almost entirely to smooth muscle hyperplasia and matrix proliferation. Despite intensive investigation in animal models and in clinical trials, most pharmacological agents have been found to be ineffective in preventing restenosis after percutaneous balloon angioplasty or stenting. Although studies frequently report success in the suppression of neointimal proliferation in animal models of balloon vascular injury, few of them have been successful in clinical trials. Lately, the advent of endovascular radiation, new antiproliferative agents, recombinant DNA, growth factor regulators and novel local drug delivery systems have shown promising results. In the past five years, intracoronary radiation with gamma- and beta-emitting sources has been evaluated intensively with very encouraging results. This is the first potent non-pharmacological approach that has been successful in a large number of patients in controlling excessive tissue proliferation. It is very likely that a combination of stents and pharmacological and/or non-pharmacological inhibition of neointimal hyperplasia will likely result in further reductions in the incidence if restenosis. The continued attractiveness of percutaneous coronary revascularisation, as an alternative to medical treatment or bypass surgery for patients with coronary artery disease, will depend upon our ability to control the restenotic process. Due to the vast literature on the subject, this review will focus mainly on clinical trials that show the most promise and will highlight those that warrant further investigation.

Systemic and Central Nervous System Vasculitides

The vasculitides are a collection of diseases sharing the central feature of tissue injury due to inflammation of blood vessels. Although some occur frequently, many are encountered uncommonly or rarely. Nonetheless, because peripheral or central nervous system abnormalities may be a prominent part of these disorders, neurologists should know or be able to refer to studies on the classification, pathophysiology, treatments, and long-term complications of vasculitis. Two central issues that confront us now are 1) improving the accuracy of diagnosis, including identifying any underlying infectious causes, and 2) limiting the long-term damage from both the disease and its therapies.

Inducible nitric oxide synthase knockout mouse macrophages disclose prooxidant effect of interferon-gamma on low-density lipoprotein oxidation

To test our hypothesis that interferon-gamma (IFN-gamma) has a direct prooxidant effect on macrophage-mediated LDL oxidation behind its antioxidant effect via induction of inducible nitric oxide synthase (iNOS), we incubated LDL with wild-type (iNOS(+/+)) or iNOS knockout mouse (iNOS(-/-)) macrophages preincubated with IFN-gamma or IFN-gamma plus lipopolysaccharide (IFN-gamma/LPS) for 24 h. LDL oxidation was measured in terms of formation of thiobarbituric acid reactive substances (TBARS) and electrophoretic mobility. Thiol production, nitrite production, and superoxide production from macrophages were measured by using Ellman's assay, the Griess reagent, and the SOD-inhibitable cytochrome c reduction method, respectively. IFN-gamma alone or combined with LPS induced iNOS expression and increased nitrite production in iNOS(+/+) macrophages, but not in iNOS(-/-) macrophages. TBARS formation from LDL was suppressed in IFN-gamma- and IFN-gamma/LPS-treated iNOS(+/+) macrophages but was increased in IFN-gamma-treated iNOS(-/-) macrophages. In the presence of N(G)-monomethyl-l-arginine (l-NMMA), a NOS inhibitor, the suppressive effect of IFN-gamma and IFN-gamma/LPS was abolished and TBARS formation was even increased to a level above that of untreated iNOS(+/+) macrophage. NOC 18, an NO donor, dose dependently inhibited macrophage-mediated LDL oxidation. IFN-gamma increased superoxide and thiol productions in both types of macrophages. We conclude that IFN-gamma promotes macrophage-mediated LDL oxidation by stimulating superoxide and thiol production under conditions where iNOS-catalyzed NO release is restricted.

Expression of canine interferon-beta by a recombinant vaccinia virus

A recombinant vaccinia virus expressing canine interferon (IFN)-beta was constructed (vv/cIFN-beta). In rabbit kidney (RK13) and canine A72 cells infected with vv/cIFN-beta, the recombinant canine IFN-beta was detected in both cell extracts and supernatants, and the IFN activities of the culture supernatants were also detected. Inhibition of N-linked glycosylation by tunicamycin treatment indicated that the recombinant canine IFN-beta was modified by N-linked glycosylation in a different way between RK13 and A72 cells, and that N-linked glycosylation is essential for its secretion. The growth of vv/cIFN-beta at a low multiplicity of infection was inhibited by antiviral activity of canine IFN-beta, indicating that this recombinant virus could be used as a suicide viral vector.

Cell-based gene transfer to the pulmonary vasculature: Endothelial nitric oxide synthase overexpression inhibits monocrotaline-induced pulmonary hypertension

To circumvent the problems of in vivo transfection and avoid the use of viral vectors or proteins, we sought to establish whether smooth-muscle cells (SMCs) transfected ex vivo could be delivered via the systemic venous circulation into the pulmonary bed to achieve local transgene expression in the lung. Primary cultures of pulmonary artery SMCs from Fisher 344 rats were labeled with a fluorescent, membrane-impermeable dye chloromethyl trimethyl rhodamine or transfected with the beta-galactosidase (betaGal) reporter gene under the control of the cytomegalovirus (CMV) enhancer/promoter (pCMV-beta). Transfected or labeled SMCs (5 x 10(5) cells/animal) were delivered to syngeneic recipient rats by injection into the jugular vein; the animals were killed at intervals between 15 min and 2 wk; and the lungs, spleens, kidneys, and skeletal muscle were excised and examined. At 15 min after transplantation, injected cells were detected mainly in the lumen of small pulmonary arteries and arterioles, often in groups of three or more cells. After 24 h, labeled SMCs were found incorporated into the vascular wall of pulmonary arterioles, and transgene expression persisted in situ for 14 d with no evidence of immune response. Using simple geometric assumptions, it was calculated that approximately 57 +/- 5% of the labeled cells reintroduced into the venous circulation could be identified in the lungs after 15 min, 34 +/- 7% at 48 h, 16 +/- 3% at 1 wk, and 15 +/- 5% at 2 wk. Similar results were observed using cells transfected with the reporter gene betaGal. To determine whether this method of gene transfer could prove effective in inhibiting the development of pulmonary vascular disease, pulmonary artery SMCs were transfected with either the full-length coding sequence of endothelial nitric oxide synthase (NOS) under the control of the CMV enhancer/promoter or with the control vector (pcDNA3.1) and injected simultaneously with the pulmonary endothelial toxin monocrotaline. At 28 d after injection the right ventricular systolic pressure was significantly decreased from 50 +/- 4 mm Hg in animals injected with the null-transfected cells to 33 +/- 3 mm Hg in animals injected with the NOS-transfected cells (P < 0.01). These results suggest that a cell-based strategy of ex vivo transfection may provide an effective nonviral approach for the selective delivery of foreign transgenes to pulmonary microvessels in the treatment of pulmonary vascular disease.

Interferon gamma up-regulates a novel protein in vascular smooth muscle cells

PURPOSE

By means of the technique of messenger RNA (mRNA) differential display, we previously isolated a partial DNA clone found to be down-regulated at the polytetrafluoroethylene (PTFE) hyperplastic arterial anastomosis compared with the normal artery. The partial DNA gene sequence was found to be homologous with interferon gamma up-regulated protein (IGUP) first found in human psoriatic keratinocytes. We cloned the entire IGUP gene from human vascular smooth muscle cells (VSMCs) to determine its regulation by gamma interferon (gamma-IFN) and other cytokines in cultured human VSMCs.

METHODS

By means of polymerase chain reaction, the IGUP gene was amplified from a QUICK-Clone complementary DNA human aorta kit using 5' and 3' oligonucleotide primers to the known IGUP sequence. Immunohistocytochemistry studies compared normal artery and distal anastomotic IH. Human VSMCs were stimulated with 1000 U/mL of gamma-IFN, 5 ng/mL of platelet-derived growth factor BB (PDGF-BB), 3. 2 ng/mL basic fibroblast growth factor, 3.3 ng/mL transforming growth factor beta(TGF-beta), 10 ng/mL of vascular endothelial growth factor, and 10% fetal bovine serum (FBS) for zero, 24, 48 and 72 hours. Western blot analysis of lysates of the stimulated VSMCs was performed to determine up-regulation of IGUP.

RESULTS

DNA sequencing confirmed the cloning of the entire coding region of the IGUP gene with 100% homology to the known IGUP DNA sequence. There was strong expression of IGUP in quiescent VSMCs and marked reduction of expression of IGUP in proliferating smooth muscle cells. gamma-IFN was the only cytokine, of the cytokines evaluated, to up-regulate production of IGUP in VSMCs.

CONCLUSION

IGUP is a novel protein in VSMCs found to be down-regulated in areas of anastomotic IH, as compared with a normal artery. We have now shown IGUP to be up-regulated only by gamma-IFN in human VSMCs. IGUP may, therefore, be the intermediary for the known gamma-IFN inhibition of human VSMC proliferation.