Impact of Femoral Ossification on Local and Systemic Cardiovascular Patients' Condition.

BACKGROUND: Vascular calcifications are associated with a high cardiovascular morbi-mortality in the coronary territory. In parallel, femoral arteries are more calcified and develop osteoid metaplasia (OM). This study was conducted to assess the predictive value of OM and local inflammation on the occurrence of mid- and long-term adverse cardiovascular events. METHOD: Between 2008 and 2015, 86 atheromatous samples were harvested during femoral endarterectomy on 81 patients and processed for histomorphological analyses of calcifications and inflammation (monocytes and B cells). Histological findings were compared with the long-term follow-up of patients, including major adverse cardiac event (MACE), major adverse limb event (MALE), and mortality. Frequencies were presented as percentage, and continuous data, as mean and standard deviation. A P-value < 0.05 was considered statistically significant. RESULTS: Median follow-up was 42.4 months (26.9-58.8). Twenty-eight percent of patients underwent a MACE; a MALE occurred in 18 (21%) limbs. Survival rate was 87.2% at 36 months. OM was found in 41 samples (51%), without any significant impact on the occurrence of MACE, MALE, or mortality. Preoperative white blood cell formulae revealed a higher rate of neutrophils associated with MACE (P = 0.04) and MALE (P = 0.0008), correlated with higher B cells counts in plaque samples. CONCLUSIONS: OM is part of femoral calcifications in almost 50% of the cases but does not seem to be an independent predictive variable for MACE or MALE. However, a higher rate of B cell infiltration of the plaque and preoperative neutrophil blood count may be predictive of adverse events during follow-up.

A depleting antibody toward sca-1 mitigates a surge of CD34(+)/c-kit(+) progenitors and reduces vascular restenosis in a murine vascular injury model.

OBJECTIVE: Vascular restenosis remains a major obstacle to long-term success after vascular intervention. Circulating progenitor cells have been implicated in restenosis, and yet it has remained unclear if these cells, particularly nonendothelial progenitors, have an active role in this pathologic process. We hypothesized that circulating CD34(+)/c-kit(+) progenitors would increase after vascular injury, mirrored by changes in the injury signal, stromal cell-derived factor 1α (sdf1α). We further postulated that an antibody-based depletion would mitigate progenitor surge and, in turn, reduce restenosis in a murine model. METHODS: C57BL6 mice underwent wire injury of the femoral artery and were compared with mice with sham surgery and vessel ligation by flow cytometry as well as by sdf1α enzyme-linked immunosorbent assay of peripheral blood. Next, injured C57BL6 mice treated with a depleting antibody toward the progenitor marker sca-1 or with an isotype control were compared in terms of sdf1α as well as enumeration of progenitors. At 28 days, restenosis was quantified between sca-1- and isotype-treated animals. RESULTS: Wire injury generated an increase in sdf1α as well as a surge of CD34(+)/c-kit(+) progenitors relative to nonsurgical controls (P = .005). Treatment with sca-1 antibody ablated the peripheral surge compared with isotype-treated, injured animals (P = .02), and sca progenitor depletion reduced the 28-day intima to media ratio in a statistically significant fashion compared with either nontreated (P = .04) or isotype-treated (P = .036) animals. CONCLUSIONS: Our study has demonstrated that sca-1 antibody reduces both progenitor surge and vascular restenosis after endoluminal vascular injury in a murine model. This suggests that circulating progenitors play an active role in restenotic disease.

Increased Number of Mast Cells in Atherosclerotic Lesions Correlates with the Presence of Myeloid but not Plasmacytoid Dendritic Cells as well as Pro-inflammatory T Cells.

BACKGROUND: Atherosclerosis is an inflammatory disease of the vessel wall promoted by different immune cells and inflammatory mediators. METHODS: In this study, 26 human plaques and 12 control vessels without atherosclerosis were immunohistochemically stained to analyze the emergence of mast cells dependent on plaque morphology and to correlate mast cell occurrence with the emergence of myeloid as well as plasmacytoid dendritic cells. Also, mast cell emergence was correlated with the number of pro-inflammatory T cells. For this, plaques were classified as stable or unstable according to established histological criteria. RESULTS: As expected, atherosclerotic lesions showed significantly higher numbers of tryptase+, chymase+, and cathepsin G+ mast cells compared to control vessels, particularly in lesions with unstable morphology. As a novel finding, we detected significant correlations between mast cells and myeloid dendritic cells (fascin, CD83, r > 0.3, p < 0.01), but not plasmacytoid dendritic cells (CD123, CD304). Also, we observed significant correlations of mast cells and different subgroups of pro-inflammatory T cells (CD3, CD8, CD161, CD25; r > 0.35, p < 0.05). CONCLUSIONS: Overall, the higher number of mast cells in plaques, particularly with unstable morphology, suggests that mast cells might be involved in the progression of atherosclerosis. The correlation of mast cells with other immune cells that are pivotal in atherogenesis, e.g., myeloid dendritic cells and pro-inflammatory T cells, also suggests an interplay leading to plaque destabilization. Therefore, modulating local mast cell function and invasion into the plaque might be a therapeutic tool for plaque stabilization.

Prostaglandin E2 potentiates mesenchymal stem cell-induced IL-10+IFN-γ+CD4+ regulatory T cells to control transplant arteriosclerosis.

Mesenchymal stem cells (MSCs) are known for their immunomodulatory functions. We previously demonstrated that bone marrow-derived MSCs effectively control transplant arteriosclerosis (TA) by enhancing IL-10(+) and IFN-γ(+) cells. The objective of this study is to elucidate the mechanism by which MSCs induce IL-10(+)IFN-γ(+)CD4(+) regulatory T type 1 (T(R)1)-like cells. In an MLR system using porcine PBMCs, MSC-induced IL-10(+)IFN-γ(+)CD4(+) cells, which confer resistance to allogeneic proliferation in an IL-10-dependent manner, resemble T(R)1-like cells. Both cyclooxygenase-derived PGE(2) and IDO help to induce T(R)1-like cells by MSCs. MSCs constitutively secrete PGE(2), which is augmented in allogeneic reactions. However, T(R)1-like cells were deficient in PGE(2) and 4-fold less potent than were MSCs in suppressing MLR. PGE(2) mimetic supplements can enhance the immunosuppressive potency of T(R)1-like cells. In a porcine model of allogeneic femoral arterial transplantation, MSC-induced T(R)1-like cells combined with PGE(2), but not either alone, significantly reduced TA at the end of 6 wk (percentage of luminal area stenosis: T(R)1-like cells + PGE(2): 11 ± 10%; PGE(2) alone: 93 ± 8.7%; T(R)1-like cells alone: 88 ± 2.4% versus untreated 94 ± 0.9%, p < 0.001). These findings indicate that PGE(2) helps MSC-induced IL-10(+)IFN-γ(+)CD4(+) T(R)1-like cells inhibit TA. PGE(2) combined with MSC-induced T(R)1-like cells represents a new approach for achieving immune tolerance.

Porphyromonas gingivalis promotes neointimal formation after arterial injury through toll-like receptor 2 signaling.

We previously demonstrated that Porphyromonas gingivalis infection induces neointimal hyperplasia with an increase in monocyte chemoattractant protein (MCP)-1 after arterial injury in wild-type mice. Toll-like receptor (TLR) 2 is a key receptor for the virulence factors of P. gingivalis. The aim of this study was to assess whether TLR2 plays a role in periodontopathic bacteria-induced neointimal formation after an arterial injury. Wild-type and TLR2-deficient mice were used in this study. The femoral arteries were injured, and P. gingivalis or vehicle was injected subcutaneously once per week. Fourteen days after arterial injury, the murine femoral arteries were obtained for histopathologic and immunohistochemical analyses. The immunoglobulin-G levels of the P. gingivalis-infected groups were significantly increased in comparison with the level in the corresponding noninfected groups in both wild-type and TLR2-deficient mice. TLR2 deficiency negated the P. gingivalis-induced neointimal formation in comparison with the wild-type mice, and reduced the number of positive monocyte chemoattractant protein-1 cells in the neointimal area. These findings demonstrate that P. gingivalis infection can promote neointimal formation after an arterial injury through TLR2 signaling.

A clinicopathologic study of immunoglobulin G4-related disease of the femoral and popliteal arteries in the spectrum of immunoglobulin G4-related periarteritis.

BACKGROUND: Immunoglobulin (Ig) G4-related disease has recently been recognized to occur in the cardiovascular system in the aorta and main branching arteries, often manifesting as aneurysms and arteritis/periarteritis. Peripheral arteries (the femoral and popliteal arteries) are frequent sites of arteriosclerosis obliterans (ASO) and occasionally show aneurysms or arteritis. This study re-examined peripheral arterial lesions from the standpoint of IgG4-related disease. METHODS: The study comprised 104 patients who underwent surgical treatment of peripheral arterial lesions, including 30 patients with peripheral arterial aneurysms (PAAs) and 74 with ASO. IgG4-related disease was identified on the basis of diffuse infiltration of numerous IgG4-positive plasmacytes as revealed by immunohistochemical examination. Clinicopathologic features were compared between IgG4-related and IgG4-unrelated lesions. RESULTS: IgG4-related disease was found in four of the 30 patients with PAAs (13.3%; two in the deep femoral artery, two in the popliteal artery) but not in any patients with ASO. IgG4-related PAA displayed clinicopathologic features resembling those of other IgG4-related diseases and a characteristic saccular appearance (P = .002). CONCLUSIONS: IgG4-related disease was detected in PAA patients but not in ASO patients. IgG4-related disease thus represents one potential etiology of aneurysm in the peripheral arteries.

High-mobility-group box protein 1A box reduces development of sodium laurate-induced thromboangiitis obliterans in rats.

OBJECTIVE: High-mobility-group box protein 1 (HMGB1), as a late mediator of inflammation, plays a key role in inflammatory responses by inducing and extending the production of proinflammatory cytokines. The effect of HGMB1 in the inflammatory disease thromboangiitis obliterans (TAO) is unknown. We aimed to investigate the role of HMGB1 in sodium laurate-induced TAO in rats. METHODS: Male Wistar rats were randomly divided into five groups (n=8 each) for treatment: normal, sham-operated, TAO model, and low-dose (15 mg/kg) or high-dose (30 mg/kg) recombinant A box (rA box) infection (administered intraperitoneally once daily for 15 days). The TAO model was induced by sodium laurate and graded by gross appearance on day 15 after femoral artery injection. Histologic changes were measured by histopathology in rat femoral arteries. Plasma levels of HMGB1, thromboxane B2, 6-keto-prostaglandin F1-α, and blood cell counts and blood coagulation levels were measured. Expression of HMGB1, receptor for advanced glycation end-products (RAGE), interleukin-6, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 was assessed by immunohistochemistry and immunofluorescence, Western blot analysis, and quantitative reverse-transcription polymerase chain reaction. RESULTS: The typical signs and symptoms of TAO were observed on day 15 after sodium laurate injection. The expression of HMGB1, RAGE, interleukin-6, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 was markedly increased in rat femoral arteries. Plasma levels of HMGB1 and thromboxane B2 were elevated, but the level of 6-keto-prostaglandin F1-α was decreased. Blood was in a hypercoagulable state, and prothrombin, thrombin, and activated partial thromboplastin times were all significantly shortened, whereas fibrinogen level was increased in TAO rats compared with sham-operated rats. These effects were terminated by the HMGB1 antagonist rA box. CONCLUSIONS: HMGB1 is involved in the inflammatory state in a model of TAO induced by sodium laurate in rats, probably via its receptor RAGE. As the antagonist of HMGB1, rA box can attenuate the development of TAO, which may be a potential therapeutic target for the treatment of TAO.

Macrophage subtypes in symptomatic carotid artery and femoral artery plaques.

OBJECTIVE: To compare differences in macrophage heterogeneity and morphological composition between atherosclerotic plaques obtained from recently symptomatic patients with carotid artery disease and femoral plaques from patients with severe limb ischemia. DESIGN: Experimental study. METHODS: Plaques were obtained from 32 patients undergoing carotid endarterectomy and 25 patients undergoing common femoral endarterectomy or lower limb bypass. Macrophages and T cell numbers were detected in plaque sections by immunohistochemistry and anti CD68 and CD3 antibodies. Dual staining for CD68 and M1- and M2-macrophage markers and morphometric analysis of hematoxylin and eosin stained plaque sections was performed. RESULTS: Carotid plaques had significantly increased percentage areas of confluent lipid and leukocytic infiltrates. In contrast, areas of fibroconnective tissue were significantly greater in femoral plaques and percentage areas of confluent calcification and collagen were elevated. Carotid artery plaques had greater numbers per plaque area of macrophages and T cells consistent with a more inflammatory phenotype. Proportions displaying M1-activation markers were significantly increased in the carotid compared to femoral plaques whereas femoral plaques displayed a greater proportion of M2-macrophages. CONCLUSION: Plaques from patients with recently symptomatic carotid disease have a predominance of M1-macrophages and higher lipid content than femoral plaques, consistent with a more unstable plaque.

Evaluation of the humoral and cellular immune responses after implantation of a PTFE vascular prosthesis.

INTRODUCTION: The experiment was designed in order to determine the immunological processes that occur during the healing in synthetic vascular grafts, especially to establish the differences in the location of the complement system proteins between the proximal and distal anastomosis and the differences in the arrangement of inflammatory cells in those anastomoses. The understanding of those processes will provide a true basis for determining risk factors for complications after arterial repair procedures. MATERIAL/METHODS: The experiment was carried out on 16 dogs that underwent implantation of unilateral aorto-femoral bypass with expanded polytetrafluoroethylene (ePTFE). After 6 months all animals were euthanized to dissect the vascular grafts. Immunohistochemical assays and electron microscopic examinations were performed. RESULTS: Immunohistochemical findings in the structure of neointima between anastomoses of vascular prostheses demonstrated significant differences between humoral and cellular responses. The area of proximal anastomosis revealed the presence of fibroblasts, but no macrophages were detected. The histological structure of the proximal anastomosis indicates that inflammatory processes were ended during the prosthesis healing. The immunological response obtained in the distal anastomosis corresponded to the chronic inflammatory reaction with the presence of macrophages, myofibroblasts and deposits of complement C3. DISCUSSION: The identification of differences in the presence of macrophages and myofibroblasts and the presence of the C3 component between the anastomoses is the original achievement of the present study. In the available literature, no such significant differences have been shown so far in the humoral and cellular immune response caused by the presence of an artificial vessel in the arterial system.

Low molecular weight (LMW) heparin inhibits injury-induced femoral artery remodeling in mouse via upregulating CD44 expression.

OBJECTIVE: The mechanism of postangioplasty restenosis remains poorly understood. Low molecular weight (LMW) heparin has been shown to inhibit the proliferation of vascular smooth muscle cells (VSMCs), which is the principal characteristic of restenosis. Studies have shown that LMW heparin could bind to CD44. We hypothesized that LMW heparin might modulate CD44 expression thereby decreasing vascular remodeling. METHODS: Vascular remodeling was induced in CD44(+/+) and CD44(-/-) mice and treated with LMW heparin. The arteries were harvested for histologic assessment and determination of CD44 expression. Bone marrow transplantation was introduced to further explore the role and functional sites of CD44. Effects of LMW heparin on growth capacity, CD44 expression were further studied using the cultured mouse VSMCs. RESULTS: Transluminal injury induced remarkable remodeling in mouse femoral artery (sham wall thickness percentage [WT%]: 3.4 ± 1.2% vs injury WT%: 31.8 ± 4.7%; P < .001). LMW heparin reduced the remodeling significantly (WT%: 17.8 ± 3.5%, P < .005). CD44(-/-) mice demonstrated considerably thicker arterial wall remodeling (WT%: 46.2 ± 7.6%, P = .0035), and CD44-chimeric mice exhibited equal contributions of the local and circulating CD44 signal to the neointima formation. LMW heparin markedly upregulated CD44 expression in the injured femoral arteries. In vitro, LMW heparin decreased mouse VSMC growth capacity and upregulated its CD44 expression simultaneously in a dose-dependent and time-dependent manner, which could be partially blocked by CD44 inhibitor. CONCLUSIONS: LMW heparin inhibits injury-induced femoral artery remodeling, at least partially, by upregulating CD44 expression.

Novel role of the CXC chemokine receptor 3 in inflammatory response to arterial injury: involvement of mTORC1.

Atherosclerosis, restenosis, and posttransplant graft atherosclerosis are characterized by endothelial damage, infiltration of inflammatory cells, and proliferation of smooth muscle cells. The CXCR3-activating chemokines interferon-gamma inducible protein 10 (IP10) and MIG (monokine induced by interferon-gamma) have been implicated in vascular repair and remodeling. The underlying molecular mechanisms, however, remain elusive. Here, we show that wire-mediated arterial injury induced local and systemic expression of IP10 and MIG, resulting in enhanced recruitment of CXCR3(+) leukocytes and hematopoietic progenitor cells. This was accompanied by profound activation of mammalian target of rapamycin complex (mTORC)1, increased reactive oxygen species production, apoptosis, and intimal hyperplasia. Genetic and pharmacological inactivation of CXCR3 signaling not only suppressed recruitment of inflammatory cells but also abolished mTORC1 activation, reduced reactive oxygen species generation, and blocked apoptosis of vascular cells, resulting in significant reduction of intimal hyperplasia in vivo. In vitro, stimulation of T cells with IP10 directly activated mTORC1 and induced generation of reactive oxygen species and apoptosis in an mTORC1-dependent manner. These results strongly indicate that CXCR3-dependent activation of mTORC1 directly links stimulation of the Th1 immune system with the proliferative response of intimal cells in vascular remodeling.

Role of hypoxia-inducible factor 1alpha in T cells as a negative regulator in development of vascular remodeling.

BACKGROUND AND PURPOSE: Recent studies have shown that the cellular immune response in the development of vascular remodeling modulates the resulting pathological alterations. We show that hypoxia-inducible factor 1 (Hif-1) (specifically expressed in T cells) is involved in the immune response to vascular remodeling that accompanies arteriosclerosis. METHODS AND RESULTS: To study the role of T cells in the development of vascular remodeling, femoral arterial injury induced by an external vascular polyethylene cuff was examined in mice lacking Hif-1 (specifically in T cells). We found that cuff placement caused prominent neointimal hyperplasia of the femoral artery in Hif-1- (T-cell)-deficient mice compared with that in control mice and that infiltration of inflammatory cells at the adventitia was markedly increased in the mutant mice. Studies to clarify the mechanism of augmented vascular remodeling in the mutant mice showed enhanced production of cytokines by activated T cells and augmented antibody production in response to a T-dependent antigen in the mutant mice. CONCLUSIONS: The results of this study revealed that Hif-1alpha in T cells plays a crucial role in vascular inflammation and remodeling in response to cuff injury as a negative regulator of T cell-mediated immune response. Potential new therapeutic strategies that target Hif-1alpha are described.

The intrinsic complement regulator decay-accelerating factor modulates the biological response to vascular injury.

OBJECTIVE: To investigate whether the presence of decay-accelerating factor (or CD55), an intrinsic complement regulator, protects against the development of vascular disease, given that complement activation can affect leukocytes and platelets. METHODS AND RESULTS: Leukocyte-platelet complexes are critical for the initiation and progression of atherosclerosis and restenosis; however, the mechanism by which these processes promote vascular injury is incompletely defined. We performed femoral artery wire injury in Daf1(-/-) mice and their wild-type controls. Leukocyte accumulation, cellular proliferation, and neointimal thickening were enhanced in Daf1(-/-) mice versus wild-type mice. Deficiency of either the C3a or the C5a receptor, respectively, reversed the increased vascular inflammation, cellular proliferation, and neointimal formation in Daf1(-/-) mice. CONCLUSIONS: Decay-accelerating factor control of C3a and C5a generation and prevention of the binding of these activation fragments to the C3a and C5a receptors are critical for the biological response to vascular injury. Targeting the C3a and C5a receptors may be useful for the prevention of neointimal hyperplasia.

Myeloid-related protein-8/14 is critical for the biological response to vascular injury.

BACKGROUND: Myeloid-related protein (MRP)-8 (S100A8) and MRP-14 (S100A9) are members of the S100 family of calcium-modulated proteins that regulate myeloid cell function and control inflammation, in part, through activation of Toll-like receptor-4 and the receptor for advanced glycation end products. A transcriptional profiling approach in patients with acute coronary syndromes identified MRP-14 as a novel predictor of myocardial infarction. Further studies demonstrated that elevated plasma levels of MRP-8/14 heterodimer predict increased risk of first and recurrent cardiovascular events. Beyond its serving as a risk marker, whether MRP-8/14 participates directly in vascular inflammation and disease remains unclear. METHODS AND RESULTS: We evaluated vascular inflammation in wild-type and MRP-14-deficient (MRP-14(-/-)) mice that lack MRP-8/14 complexes with experimental arterial injury, vasculitis, or atherosclerosis. After femoral artery wire injury, MRP-14(-/-) mice had significant reductions in leukocyte accumulation, cellular proliferation, and neointimal formation compared with wild-type mice. In a cytokine-induced local Shwartzman-like reaction that produces thrombohemorrhagic vasculitis, MRP-14(-/-) mice had significant reductions in neutrophil accumulation, lesion severity, and hemorrhagic area. In response to high-fat feeding, mice doubly deficient in apolipoprotein E and MRP-8/14 complexes had attenuation in atherosclerotic lesion area and in macrophage accumulation in plaques compared with mice deficient in apolipoprotein E alone. CONCLUSIONS: This study demonstrates that MRP-8/14 broadly regulates vascular inflammation and contributes to the biological response to vascular injury by promoting leukocyte recruitment.

Effect of hirulog-like peptide on balloon catheter injury-induced neointimal formation in femoral arteries of minipigs and relationship with inflammatory mediators.

Vascular intervention-induced neointimal formation is a major drawback for managing atherosclerotic cardiovascular diseases using invasive vascular procedures. Our previous studies demonstrated that hirulog-like peptide (HLP) reduced balloon catheter dilation-induced neointimal formation or restenosis in carotid arteries of rats or atherosclerotic rabbits with less interruption in coagulation or bleeding than heparin or hirulog-1. The present study examined the effect of HLP on balloon catheter injury-induced neointimal formation in femoral arteries of minipigs. Intravenous infusion of HLP (1.6 mg/kg/h for 4 h started 0.5 h before the intervention) or unfractured heparin (50 U/kg/h for 4 h) significantly reduced neointimal formation in femoral arteries 4 weeks after intervention compared with the vehicle. Heparin, but not HLP, significantly prolonged activated partial thromboplastin time. HLP or heparin significantly reduced vascular intervention-induced increases in C-reactive protein, P-selectin and interleukin-6 in serum. HLP, but not heparin, normalized vascular injury-induced increase in P-selectin in platelets. The results of the present study suggest that HLP is an effective agent for preventing balloon catheter injury-induced neointimal formation in femoral arteries of minipigs. The beneficial effects of HLP on vascular injury-induced neointimal formation may partially result from its inhibition on inflammatory mediators.

Deficiency of tumour necrosis factor-alpha and interferon-gamma in bone marrow cells synergistically inhibits neointimal formation following vascular injury.

AIMS: Neointimal formation after percutaneous coronary intervention (PCI), termed restenosis, limits therapeutic revascularization. Since it is now known that vascular injury involves an inflammatory response, we examined the role of tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in the neointimal formation after injury. METHODS AND RESULTS: Control (BALB/c), TNF-alpha-deficient (Tnf(-/-)), IFN-gamma-deficient (Ifng(-/-)), or double-deficient (Tnf(-/-)Ifng(-/-)) mice were subjected to wire-mediated vascular injury of the right femoral artery. Neointimal formation after injury was significantly reduced after the injury in the Tnf(-/-)Ifng(-/-) mice, compared to that in the control, Tnf(-/-), and Ifng(-/-) mice. Immunohistochemical analysis showed that TNF-alpha and IFN-gamma were expressed in neointimal lesions in the control mice, but not in mice with deficiency of the corresponding cytokine. No significant difference in re-endothelialization was observed among these groups. The number of proliferating cell nuclear antigen in the neointimal lesions was significantly decreased in the Tnf(-/-)Ifng(-/-) mice. Bone marrow transplantation experiments revealed that deficiency of TNF-alpha and IFN-gamma specifically in bone marrow cells significantly inhibited neointimal formation after vascular injury. CONCLUSION: The absence of TNF-alpha and IFN-gamma in bone marrow cells synergistically inhibits neointimal formation following vascular injury, and thus, may provide new insights into the mechanisms underlying restenosis after PCI.

Peripheral arterial occlusive disease: global gene expression analyses suggest a major role for immune and inflammatory responses.

BACKGROUND: Peripheral arterial disease (PAD), a major manifestation of atherosclerosis, is associated with significant cardiovascular morbidity, limb loss and death. However, mechanisms underlying the genesis and progression of the disease are far from clear. Genome-wide gene expression profiling of clinical samples may represent an effective approach to gain relevant information. RESULTS: After histological classification, a total of 30 femoral artery samples, including 11 intermediate lesions, 14 advanced lesions and 5 normal femoral arteries, were profiled using Affymetrix microarray platform. Following real-time RT-PCR validation, different algorithms of gene selection and clustering were applied to identify differentially expressed genes. Under a stringent cutoff, i.e., a false discovery rate (FDR) <0.5%, we found 366 genes were differentially regulated in intermediate lesions and 447 in advanced lesions. Of these, 116 genes were overlapped between intermediate and advanced lesions, including 68 up-regulated genes and 48 down-regulated ones. In these differentially regulated genes, immune/inflammatory genes were significantly up-regulated in different stages of PAD, (85/230 in intermediate lesions, 37/172 in advanced lesions). Through literature mining and pathway analysis using different databases such as Gene Ontology (GO), and the Kyoto Encyclopedia of Gene and Genomics (KEGG), genes involved in immune/inflammatory responses were significantly enriched in up-regulated genes at different stages of PAD(p < 0.05), revealing a significant correlation between immune/inflammatory responses and disease progression. Moreover, immune-related pathways such as Toll-like receptor signaling and natural killer cell mediated cytotoxicity were particularly enriched in intermediate and advanced lesions (P < 0.05), highlighting their pathogenic significance during disease progression. CONCLUSION: Lines of evidence revealed in this study not only support previous hypotheses, primarily based on studies of animal models and other types of arterial disease, that inflammatory responses may influence the development of PAD, but also permit the recognition of a wide spectrum of immune/inflammatory genes that can serve as signatures for disease progression in PAD. Further studies of these signature molecules may eventually allow us to develop more sophisticated protocols for pharmaceutical interventions.

Higher expression of Bax in regulatory T cells increases vascular inflammation.

This study is to examine our hypothesis that CD4+CD25(high)Foxp3+ regulatory T cells (Tregs) have an interleukin-2 (IL-2) withdrawal-triggered apoptosis pathway, and modulation of Treg apoptosis pathway affects development of vascular inflammation. We found that pro-apoptotic protein Bax upregulation in Tregs is induced by IL-2 withdrawal. Treg apoptosis induced by IL-2 withdrawal is inhibited by a Bax inhibitor, suggesting that highly expressed Bax is functional. To define the role of upregulated Bax in Treg apoptosis, we established a Tregs-specific Bax transgenic mouse model. Enforced expression of Bax in Tregs promotes Treg apoptosis triggered by IL-2 withdrawal and other apoptosis stimuli, suggesting pro-apoptotic role of highly expressed Bax in wild-type Tregs. Finally, higher expression of Bax in Tregs decreases the striking threshold of vascular inflammation due to the failure of suppression of inflammatory cells resulting from Treg apoptosis. These results have demonstrated the proof of principle that the modulation of Tregs apoptosis/survival could be used as a new therapeutic approach for inflammatory cardiovascular diseases.

MCP-1 deficiency causes altered inflammation with impaired skeletal muscle regeneration.

We examined the role of MCP-1, a potent chemotactic and activating factor for macrophages, in perfusion, inflammation, and skeletal muscle regeneration post-ischemic injury. MCP-1-/- or C57Bl/6J control mice [wild-type (WT)] underwent femoral artery excision (FAE). Muscles were collected for histology, assessment of tissue chemokines, and activity measurements of lactate dehydrogenase (LDH) and myeloperoxidase. In MCP-1-/- mice, restoration of perfusion was delayed, and LDH and fiber size, indicators of muscle regeneration, were decreased. Altered inflammation was observed with increased neutrophil accumulation in MCP-1-/- versus WT mice at Days 1 and 3 (P< or =0.003), whereas fewer macrophages were present in MCP-1-/- mice at Day 3. As necrotic tissue was removed in WT mice, macrophages decreased (Day 7). In contrast, macrophage accumulation in MCP-1-/- was increased in association with residual necrotic tissue and impaired muscle regeneration. Consistent with altered inflammation, neutrophil chemotactic factors (keratinocyte-derived chemokine and macrophage inflammatory protein-2) were increased at Day 1 post-FAE. The macrophage chemotactic factor MCP-5 was increased significantly in WT mice at Day 3 compared with MCP-1-/- mice. However, at post-FAE Day 7, MCP-5 was significantly elevated in MCP-1-/- mice versus WT mice. Addition of exogenous MCP-1 did not induce proliferation in murine myoblasts (C2C12 cells) in vitro. MCP-1 is essential for reperfusion and the successful completion of normal skeletal muscle regeneration after ischemic tissue injury. Impaired muscle regeneration in MCP-1-/- mice suggests an important role for macrophages and MCP-1 in tissue reparative processes.

BLTR1 in Monocytes Emerges as a Therapeutic Target For Vascular Inflammation With a Subsequent Intimal Hyperplasia in a Murine Wire-Injured Femoral Artery.

Given the importance of high-mobility group box 1 (HMGB1) and 5-lipoxygenase (5-LO) signaling in vascular inflammation, we investigated the role of leukotriene signaling in monocytes on monocyte-to-macrophage differentiation (MMD) induced by HMGB1, and on vascular inflammation and subsequent intimal hyperplasia in a mouse model of wire-injured femoral artery. In cultured primary bone marrow-derived cells (BMDCs) stimulated with HMGB1, the number of cells with macrophage-like morphology was markedly increased in association with an increased expression of CD11b/Mac-1, which were attenuated in cells pre-treated with Zileuton, a 5-LO inhibitor as well as in 5-LO-deficient BMDCs. Of various leukotriene receptor inhibitors examined, which included leukotriene B4 receptors (BLTRs) and cysteinyl leukotriene receptors (cysLTRs), the BLTR1 inhibitor (U75302) exclusively suppressed MMD induction by HMGB1. The importance of BLTR1 in HMGB1-induced MMD was also observed in BMDCs isolated from BLTR1-deficient mice and BMDCs transfected with BLTR1 siRNA. Although leukotriene B4 (LTB4) had minimal direct effects on MMD in control and 5-LO-deficient BMDCs, MMD attenuation by HMGB1 in 5-LO-deficient BMDCs was significantly reversed by exogenous LTB4, but not in BLTR1-deficient BMDCs, suggesting that LTB4/BLTR1-mediated priming of monocytes is a prerequisite of HMGB1-induced MMD. In vivo, both macrophage infiltration and intimal hyperplasia in our wire-injured femoral artery were markedly attenuated in BLTR1-deficient mice as compared with wild-type controls, but these effects were reversed in BLTR1-deficient mice transplanted with monocytes from control mice. These results suggest that BLTR1 in monocytes is a pivotal player in MMD with subsequent macrophage infiltration into neointima, leading to vascular remodeling after vascular injury.