The Specific Molecular Changes Induced by Diabetic Conditions in Valvular Endothelial Cells and upon Their Interactions with Monocytes Contribute to Endothelial Dysfunction.

Aortic valve disease (AVD) represents a global public health challenge. Research indicates a higher prevalence of diabetes in AVD patients, accelerating disease advancement. Although the specific mechanisms linking diabetes to valve dysfunction remain unclear, alterations of valvular endothelial cells (VECs) homeostasis due to high glucose (HG) or their crosstalk with monocytes play pivotal roles. The aim of this study was to determine the molecular signatures of VECs in HG and upon their interaction with monocytes in normal (NG) or high glucose conditions and to propose novel mechanisms underlying valvular dysfunction in diabetes. VECs and THP-1 monocytes cultured in NG/HG conditions were used. The RNAseq analysis revealed transcriptomic changes in VECs, in processes related to cytoskeleton regulation, focal adhesions, cellular junctions, and cell adhesion. Key molecules were validated by qPCR, Western blot, and immunofluorescence assays. The alterations in cytoskeleton and intercellular junctions impacted VEC function, leading to changes in VECs adherence to extracellular matrix, endothelial permeability, monocyte adhesion, and transmigration. The findings uncover new molecular mechanisms of VEC dysfunction in HG conditions and upon their interaction with monocytes in NG/HG conditions and may help to understand mechanisms of valvular dysfunction in diabetes and to develop novel therapeutic strategies in AVD.

Anti-Inflammatory Neutrophils Reprogram Macrophages toward a Pro-Healing Phenotype with Increased Efferocytosis Capacity.

Following myocardial infarction (MI), blood neutrophils quickly and extensively infiltrate the heart, where they are temporally polarized into pro-inflammatory (N1) and anti-inflammatory (N2) subpopulations. Neutrophil transmigration is rapidly followed by the accrual of macrophages (MACs), which are believed to undergo local phenotypic transformations from pro-inflammatory to pro-healing MACs that mediate inflammation resolution. We hypothesized that N2 neutrophils can reprogram MACs toward a healing phenotype with increased efferocytosis capacity. To examine this, human neutrophils isolated from healthy subjects were polarized in N1 and N2 neutrophils, and their secretome was added to human MACs derived from THP monocytes. The impact of neutrophil factors on macrophages was investigated using qPCR, ELISA, Western blot, immunofluorescence, or an efferocytosis assay. The results show that the MACs exposed to N2 neutrophil secretome exhibited (i) increased expression of the anti-inflammatory molecules CD206, TGF-ß, and IL-10 and the nuclear factors associated with reparatory macrophages (PPARγ, Nur77, and KLF4); (ii) enhanced expression of efferocytosis receptors (MerTK, CD36, CX3CR1, and integrins αv/ß5) and of the bridge molecules Mfage8 and Gas6; and (iii) enhanced efferocytosis. In conclusion, factors released by N2 neutrophils induce a pro-healing phenotype of MACs by upregulating anti-inflammatory molecules and efferocytosis receptors and ensuing the efferocytosis capacity. The data suggest that molecular therapy to foster N2 polarization, which boosts macrophages' pro-healing phenotype, could be a promising strategy to speed up inflammation resolution and tissue repair.

Ficolin-2 amplifies inflammation in macrophage-smooth muscle cell cross-talk and increases monocyte transmigration by mechanisms involving IL-1ß and IL-6.

Ficolin-2, recently identified in atherosclerotic plaques, has been correlated with future acute cardiovascular events, but its role remains unknown. We hypothesize that it could influence plaque vulnerability by interfering in the cross-talk between macrophages (MØ) and smooth muscle cells (SMC). To examine its role and mechanism of action, we exposed an in-vitro co-culture system of SMC and MØ to ficolin-2 (10 µg/mL) and then performed cytokine array, protease array, ELISA, qPCR, Western Blot, and monocyte transmigration assay. Carotid plaque samples from atherosclerotic patients with high plasma levels of ficolin-2 were analyzed by immunofluorescence. We show that ficolin-2: (i) promotes a pro-inflammatory phenotype in SMC following interaction with MØ by elevating the gene expression of MCP-1, upregulating gene and protein expression of IL-6 and TLR4, and by activating ERK/MAPK and NF-KB signaling pathways; (ii) increased IL-1ß, IL-6, and MIP-1ß in MØ beyond the level induced by cellular interaction with SMC; (iii) elevated the secretion of IL-1ß, IL-6, and CCL4 in the conditioned medium; (iv) enhanced monocyte transmigration and (v) in atherosclerotic plaques from patients with high plasma levels of ficolin-2, we observed co-localization of ficolin-2 with SMC marker αSMA and the cytokines IL-1ß and IL-6. These findings shed light on previously unknown mechanisms underlying ficolin-2-dependent pathological inflammation in atherosclerotic plaques.

3D Matrices for Enhanced Encapsulation and Controlled Release of Anti-Inflammatory Bioactive Compounds in Wound Healing.

Current trends in the development of wound dressings are oriented towards the use of biopolymer-based materials, due to their unique properties such as non-toxicity, hydrophilicity, biocompatibility and biodegradability, properties that have advantageous therapeutic characteristics. In this regard, the present study aims to develop hydrogels based on cellulose and dextran (CD) and to reveal their anti-inflammatory performance. This purpose is achieved by incorporating plant bioactive polyphenols (PFs) in CD hydrogels. The assessments include establishing the structural characteristics using attenuated total reflection Fourier transformed infrared (ATR-FTIR) spectroscopy, the morphology by scanning electron microscopy (SEM), the swelling degree of hydrogels, the PFs incorporation/release kinetics and the hydrogels' cytotoxicity, together with evaluation of the anti-inflammatory properties of PFs-loaded hydrogels. The results show that the presence of dextran has a positive impact on the hydrogel's structure by decreasing the pore size at the same time as increasing the uniformity and interconnectivity of the pores. In addition, there is an increased degree of swelling and of the encapsulation capacity of PFs, with the increase of the dextran content in hydrogels. The kinetics of PFs released by hydrogels was studied according to the Korsmeyer-Peppas model, and it was observed that the transport mechanisms depend on hydrogels' composition and morphology. Furthermore, CD hydrogels have been shown to promote cell proliferation without cytotoxicity, by successfully culturing fibroblasts and endothelial cells on CD hydrogels (over 80% viability). The anti-inflammatory tests performed in the presence of lipopolysaccharides demonstrate the anti-inflammatory properties of the PFs-loaded hydrogels. All these results provide conclusive evidence on the acceleration of wound healing by inhibiting the inflammation process and support the use of these hydrogels encapsulated with PFs in wound healing applications.

Parathyroid Hormone Induces Human Valvular Endothelial Cells Dysfunction That Impacts the Osteogenic Phenotype of Valvular Interstitial Cells.

Parathyroid hormone (PTH) is a key regulator of calcium, phosphate and vitamin D metabolism. Although it has been reported that aortic valve calcification was positively associated with PTH, the pathophysiological mechanisms and the direct effects of PTH on human valvular cells remain unclear. Here we investigated if PTH induces human valvular endothelial cells (VEC) dysfunction that in turn could impact the switch of valvular interstitial cells (VIC) to an osteoblastic phenotype. Human VEC exposed to PTH were analyzed by qPCR, western blot, Seahorse, ELISA and immunofluorescence. Our results showed that exposure of VEC to PTH affects VEC metabolism and functions, modifications that were accompanied by the activation of p38MAPK and ERK1/2 signaling pathways and by an increased expression of osteogenic molecules (BMP-2, BSP, osteocalcin and Runx2). The impact of dysfunctional VEC on VIC was investigated by exposure of VIC to VEC secretome, and the results showed that VIC upregulate molecules associated with osteogenesis (BMP-2/4, osteocalcin and TGF-ß1) and downregulate collagen I and III. In summary, our data show that PTH induces VEC dysfunction, which further stimulates VIC to differentiate into a pro-osteogenic pathological phenotype related to the calcification process. These findings shed light on the mechanisms by which PTH participates in valve calcification pathology and suggests that PTH and the treatment of hyperparathyroidism represent a therapeutic strategy to reduce valvular calcification.

High Glucose Induced Changes in Human VEC Phenotype in a 3D Hydrogel Derived From Cell-Free Native Aortic Root.

Background: Valvular endothelial cells (VEC) have key roles in maintaining valvular integrity and homeostasis, and dysfunctional VEC are the initiators and major contributors to aortic valve disease in diabetes. Previous studies have shown that HG stimulated an inflammatory phenotype in VEC. Inflammation was shown to induce endothelial to mesenchymal transition (EndMT), a process extensively involved in many pathologies, including calcification of the aortic valve. However, the effect of HG on EndMT in VEC is not known. In addition, there is evidence that endothelin (ET) is a proinflammatory agent in early diabetes and was detected in aortic stenosis, but it is not known whether HG induces ET and endothelin receptors and whether endothelin modulates HG-dependent inflammation in VEC. This study aims to evaluate HG effects on EndMT, on endothelin and endothelin receptors induction in VEC and their role in HG induced VEC inflammation. Methods and Results: We developed a new 3D model of the aortic valve consisting of a hydrogel derived from a decellularized extracellular cell matrix obtained from porcine aortic root and human valvular cells. VEC were cultured on the hydrogel surface and VIC within the hydrogel, and the resulted 3D construct was exposed to high glucose (HG) conditions. VEC from the 3D construct exposed to HG exhibited: attenuated intercellular junctions and an abundance of intermediate filaments (ultrastructural analysis), decreased expression of endothelial markers CD31 and VE-cadherin and increased expression of the mesenchymal markers α-SMA and vimentin (qPCR and immunocytochemistry), increased expression of inflammatory molecules ET-1 and its receptors ET-A and ET-B, ICAM-1, VCAM-1 (qPCR and Immunocytochemistry) and augmented adhesiveness. Blockade of ET-1 receptors, ET-A and ET-B reduced secretion of inflammatory biomarkers IL-1ß and MCP-1 (ELISA assay). Conclusions: This study demonstrates that HG induces EndMT in VEC and indicates endothelin as a possible target to reduce HG-induced inflammation in VEC.

Transcriptional Profiling and Functional Analysis of N1/N2 Neutrophils Reveal an Immunomodulatory Effect of S100A9-Blockade on the Pro-Inflammatory N1 Subpopulation.

Neutrophils have been classically viewed as a homogenous population. Recently, neutrophils were phenotypically classified into pro-inflammatory N1 and anti-inflammatory N2 sub-populations, but the functional differences between the two subtypes are not completely understood. We aimed to investigate the phenotypic and functional differences between N1 and N2 neutrophils, and to identify the potential contribution of the S100A9 alarmin in neutrophil polarization. We describe distinct transcriptomic profiles and functional differences between N1 and N2 neutrophils. Compared to N2, the N1 neutrophils exhibited: i) higher levels of ROS and oxidative burst, ii) increased activity of MPO and MMP-9, and iii) enhanced chemotactic response. N1 neutrophils were also characterized by elevated expression of NADPH oxidase subunits, as well as activation of the signaling molecules ERK and the p65 subunit of NF-kB. Moreover, we found that the S100A9 alarmin promotes the chemotactic and enzymatic activity of N1 neutrophils. S100A9 inhibition with a specific small-molecule blocker, reduced CCL2, CCL3 and CCL5 chemokine expression and decreased MPO and MMP-9 activity, by interfering with the NF-kB signaling pathway. Together, these findings reveal that N1 neutrophils are pro-inflammatory effectors of the innate immune response. Pharmacological blockade of S100A9 dampens the function of the pro-inflammatory N1 phenotype, promoting the alarmin as a novel target for therapeutic intervention in inflammatory diseases.

Chronic High Glucose Concentration Induces Inflammatory and Remodeling Changes in Valvular Endothelial Cells and Valvular Interstitial Cells in a Gelatin Methacrylate 3D Model of the Human Aortic Valve.

Calcific aortic valve disease (CAVD), a degenerative disease characterized by inflammation, fibrosis and calcification, is accelerated in diabetes. Hyperglycemia contributes to this process by mechanisms that still need to be uncovered. We have recently developed a 3D model of the human aortic valve based on gelatin methacrylate and revealed that high glucose (HG) induced osteogenic molecules and increased calcium deposits in a pro-osteogenic environment. To further understand the events leading to calcification in diabetic conditions in CAVD, we analyzed here the inflammatory and remodeling mechanisms induced by HG in our 3D model. We exposed valvular endothelial cells (VEC) and interstitial cells (VIC) to normal glucose (NG) or HG for 7 and 14 days, then we isolated and separated the cells by anti-CD31 immunomagnetic beads. The changes induced by HG in the 3D model were investigated by real-time polymerase chain reaction (RT-PCR), Western blot, enzyme-linked immunosorbent assay (ELISA) and immunofluorescence. Our results showed that HG induced expression of different cytokines, cell adhesion molecules and matrix metalloproteinases in VEC and VIC. In addition, protein kinase C was increased in VEC and VIC, indicating molecular mechanisms associated with HG induced inflammation and remodeling in both valvular cells. These findings may indicate new biomarkers and targets for therapy in diabetes associated with CAVD.

Publisher Correction: Regulation of cellular sterol homeostasis by the oxygen responsive noncoding RNA lincNORS.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Regulation of cellular sterol homeostasis by the oxygen responsive noncoding RNA lincNORS.

We hereby provide the initial portrait of lincNORS, a spliced lincRNA generated by the MIR193BHG locus, entirely distinct from the previously described miR-193b-365a tandem. While inducible by low O2 in a variety of cells and associated with hypoxia in vivo, our studies show that lincNORS is subject to multiple regulatory inputs, including estrogen signals. Biochemically, this lincRNA fine-tunes cellular sterol/steroid biosynthesis by repressing the expression of multiple pathway components. Mechanistically, the function of lincNORS requires the presence of RALY, an RNA-binding protein recently found to be implicated in cholesterol homeostasis. We also noticed the proximity between this locus and naturally occurring genetic variations highly significant for sterol/steroid-related phenotypes, in particular the age of sexual maturation. An integrative analysis of these variants provided a more formal link between these phenotypes and lincNORS, further strengthening the case for its biological relevance.

Molecular mechanisms involved in high glucose-induced valve calcification in a 3D valve model with human valvular cells.

Calcific aortic valve disease (CAVD)-the most common valvular heart disease-is accelerated in diabetes and has no pharmacotherapy. Although it is known that early CAVD is associated with inflammation and osteogenesis, the molecular mechanisms involved in diabetes-associated CAVD still need to be uncovered. In this context, we have developed a 3D construct based on gelatin populated with human valvular endothelial cells (VEC) and valvular interstitial cells (VIC) and evaluated the effect of high glucose (HG) concentration on osteogenic molecules expression and on calcification mechanisms. First, we characterized the 3D model and assessed VIC remodelling properties at different time-points. Then, we exposed it to normal glucose (NG) or high glucose (HG) for 7, 14 and 21 days after which the cells were isolated, separated and investigated individually. Our results showed that encapsulated VIC actively remodel the hydrogel, as demonstrated by an increased expression of extracellular matrix (ECM) proteins and matrix metalloproteinases (MMPs). Moreover, exposure of the construct to HG triggered bone morphogenetic protein (BMP) and TGF-ß signalling pathways, up-regulating expression of osteogenic molecules-BMP-2/-4, osteocalcin, osteopontin, SMADs and Runt-related transcription factor (Runx-2)-and increased calcium deposits in an osteogenic environment. These findings underline the potential of the developed 3D model as a suitable system to investigate the mechanisms of human CAVD and may help to better understand the calcification mechanisms in CAVD associated to diabetes.

The expression of MMP-1 and MMP-9 is up-regulated by smooth muscle cells after their cross-talk with macrophages in high glucose conditions.

Patients with diabetes mellitus have an increased risk of myocardial infarction and coronary artery disease-related death, exhibiting highly vulnerable plaques. Many studies have highlighted the major role of macrophages (MAC) and smooth muscle cells (SMC) and the essential part of metalloproteases (MMPs) in atherosclerotic plaque vulnerability. We hypothesize that in diabetes, the interplay between MAC and SMC in high glucose conditions may modify the expression of MMPs involved in plaque vulnerability. The SMC-MAC cross-talk was achieved using trans-well chambers, where human SMC were grown at the bottom and human MAC in the upper chamber in normal (NG) or high (HG) glucose concentration. After cross-talk, the conditioned media and cells were isolated and investigated for the expression of MMPs, MCP-1 and signalling molecules. We found that upon cross-talk with MAC in HG, SMC exhibit: (i) augmented expression of MMP-1 and MMP-9; (ii) significant increase in the enzymatic activity of MMP-9; (iii) higher levels of soluble MCP-1 chemokine which is functionally active and involved in MMPs up-regulation; (iv) activated PKCα signalling pathway which, together with NF-kB are responsible for MMP-1 and MMP-9 up-regulation, and (v) impaired function of collagen assembly. Taken together, our data indicate that MCP-1 released by cell cross-talk in diabetic conditions binds to CCR2 and triggers MMP-1 and MMP-9 over-expression and activity, features that could explain the high vulnerability of atherosclerotic plaque found at diabetic patients.

Lipopolysaccharide-induced inflammation in monocytes/macrophages is blocked by liposomal delivery of Gi-protein inhibitor.

BACKGROUND: Lipopolysaccharide (LPS) is widely recognized as a potent activator of monocytes/macrophages, and its effects include an altered production of key mediators, such as inflammatory cytokines and chemokines. The involvement of Gi protein in mediating LPS effects has been demonstrated in murine macrophages and various cell types of human origin. PURPOSE: The aim of the present work was to evaluate the potential of a Gi-protein inhibitor encapsulated in liposomes in reducing the inflammatory effects induced by LPS in monocytes/macrophages. MATERIALS AND METHODS: Guanosine 5'-O-(2-thiodiphosphate) (GOT), a guanosine diphosphate analog that completely inhibits G-protein activation by guanosine triphosphate and its analogs, was encapsulated into liposomes and tested for anti-inflammatory effects in LPS-activated THP1 monocytes or THP1-derived macrophages. The viability of monocytes/macrophages after incubation with different concentrations of free GOT or liposome-encapsulated GOT was assessed by MTT assay. MAPK activation and production of IL1ß, TNFα, IL6, and MCP1 were assessed in LPS-activated monocytes/macrophages in the presence or absence of free or encapsulated GOT. In addition, the effect of free or liposome-encapsulated GOT on LPS-stimulated monocyte adhesion to activated endothelium and on monocyte chemotaxis was evaluated. RESULTS: We report here that GOT-loaded liposomes inhibited activation of MAPK and blocked the production of the cytokines IL1ß, TNFα, IL6, and MCP1 induced by LPS in monocytes and macrophages. Moreover, GOT encapsulated in liposomes reduced monocyte adhesion and chemotaxis. All demonstrated events were in contrast with free GOT, which showed reduced or no effect on monocyte/macrophage activation with LPS. CONCLUSION: This study demonstrates the potential of liposomal GOT in blocking LPS proinflammatory effects in monocytes/macrophages.

P-Selectin Targeted Dexamethasone-Loaded Lipid Nanoemulsions: A Novel Therapy to Reduce Vascular Inflammation.

Inflammation is a common process associated with numerous vascular pathologies. We hypothesized that targeting the inflamed endothelium by coupling a peptide with high affinity for P-selectin to the surface of dexamethasone-loaded lipid nanoemulsions will highly increase their specific binding to activated endothelial cells (EC) and reduce the cell activation. We developed and characterized dexamethasone-loaded lipid nanoemulsions directed towards P-selectin (PLN-Dex) and monitored their anti-inflammatory effects in vitro using cultured EC (EA.hy926 cells) and in vivo using a mouse model of acute inflammation [lipopolysaccharides (LPS) intravenously administered in C57BL/6 mice]. We found that PLN-Dex bound specifically to the surface of activated EC are efficiently internalized by EC and reduced the expression of proinflammatory genes, thus preventing the monocyte adhesion and transmigration to/through activated EC. Given intravenously in mice with acute inflammation, PLN-Dex accumulated at a significant high level in the lungs (compared to nontargeted nanoemulsions) and significantly reduced mRNA expression level of key proinflammatory cytokines such as IL-1ß, IL-6, and MCP-1. In conclusion, the newly developed nanoformulation, PLN-Dex, is functional in vitro and in vivo, reducing selectively the endothelium activation and the consequent monocyte infiltration and diminishing significantly the lungs' inflammation, in a mouse model of acute inflammation.

Amendment of the cytokine profile in macrophages subsequent to their interaction with smooth muscle cells: Differential modulation by fractalkine and resistin.

In atherosclerotic plaques, macrophages (MAC) and smooth muscle cells (SMC) frequently reside in close proximity and resistin (Rs) and fractalkine (Fk) are present at increased levels, resistin being associated with CD68 macrophages and fractalkine predominantly associated with intimal SMC; however, their role in this location is not clear, yet. The objective of this study was to determine whether the cross-talk between MAC-SMC induces changes in MAC cytokine phenotype and if Fk and Rs have a role in the process. To this purpose, macrophages (THP-1 monocytes differentiated with phorbol myristate acetate) were interacted with SMC cultured on the membrane inserts in the presence or absence of Rs or Fk. After 24h, MAC were removed from the co-culture and the gene and protein expression of 57 cytokines was assessed by QPCR and Proteome Profiler™ Array. Fk secreted in the culture medium following MAC-SMC interaction was determined (ELISA assay) and the role of Fk in MAC cytokine gene expression was assessed by silencing the Fk receptor in both cell types. The results showed that subsequent to the interaction with SMC, MAC exhibit: (1) a general increased expression of chemokines (the highest fold increase: VCC-1 and GRO-α) and of some interleukins, such as interleukins IL-5 (∼8-fold) and IL-6; (2) an increased Fk expression that in turn induces expression of: CXCL17, CCL19, CCL2, CXCL10, CXCL12, CXCL4, CXCL7, CCL4, CCL18, CXCL16, CXCL1 and IL-27; (3) in the presence of Rs, a predominant increased expression of interleukins (the highest fold increase: IL-6, IL-27, IL-23 and IL-5) and an augmented expression of some chemokines such as MIP-1ß, GRO-α and CCL1. In addition, the secretome collected from the SMC-MAC co-culture increased human monocytes chemotaxis. DAVID analysis of the data revealed that the switch of MAC to a pro-inflammatory phenotype, prime the cells to intervene in the immune response, chemotaxis and inflammatory response. In conclusion, MAC cytokines expression is considerable augmented upon their interaction with SMC and Fk and Rs have distinct immunomodulatory roles: Fk predominantly increases the pro-angiogenic and inflammatory chemokines expression and Rs mostly the pro-inflammatory interleukins with consequences on monocyte chemotaxis. The novel data could help to develop targeted nanotherapies to reduce leukocyte chemotaxis and the ensuing inflammatory process associated with atherosclerosis.

Conjugation of curcumin-loaded lipid nanoemulsions with cell-penetrating peptides increases their cellular uptake and enhances the anti-inflammatory effects in endothelial cells.

OBJECTIVES: To prepare and characterize in vitro and in vivo lipid nanoemulsions (LN) loaded with curcumin (Cm) and functionalized with a cell-penetrating peptide. METHODS: Curcumin-loaded lipid nanoemulsions (CmLN) functionalized with a nona-arginine peptide (R9-CmLN) have been obtained, characterized and optimized for size, entrapment efficiency and in vitro Cm release. The interaction of R9-CmLN with human endothelial cells (HEC) was investigated using cultured EA.hy926 cells, and in vivo biodistribution studies were performed using C57BL6 mice. KEY FINDINGS: When used in therapeutically relevant concentration, R9-CmLN have low haemolytic activity, low cytotoxicity on HEC, and show anti-inflammatory effects by reducing the monocytes adhesion to TNF-α activated HEC. Moreover, HEC uptake and internalization of R9-CmLN was significantly higher compared to the non-functionalized CmLN. In vivo biodistribution studies in mice revealed a higher accumulation of R9-CmLN in the liver and the lungs compared to CmLN and the body clearance of the both nanoformulations after 72 h. CONCLUSIONS: Cell-penetrating peptides-functionalized CmLN have superior characteristics compared to their non-functionalized counterparts: are more efficiently internalized by the cells, produces anti-inflammatory effects in HEC and when administrated intravenously in mice exhibit increased accumulation in the liver and the lungs, suggesting their potential therapeutic applications in different inflammatory pathologies localized in the liver or the lungs.

VCAM-1 directed target-sensitive liposomes carrying CCR2 antagonists bind to activated endothelium and reduce adhesion and transmigration of monocytes.

Chemokines are critically involved in the development of chronic inflammatory-associated diseases such as atherosclerosis. We hypothesized that targeted delivery of compounds to the surface of activated endothelial cells (EC) interferes with chemokine/receptor interaction and thereby efficiently blocks inflammation. We developed PEGylated target-sensitive liposomes (TSL) encapsulating a CCR2 antagonist (Teijin compound 1) coupled with a specific peptide recognized by endothelial VCAM-1 (Vp-TSL-Tj). TSL were characterized for size (by dynamic light scattering), the amount of peptide coupled at the liposomal surface and Teijin release (by HPLC). We report that Vp-TSL-Tj binds specifically to activated EC in vitro and in situ, release the entrapped Teijin and prevent the transmigration of monocytes through activated EC. This is the first evidence that nanocarriers which transport and release chemokine inhibitors at specific pathological sites can reduce chemokine-dependent inflammatory processes.

Molecular and functional interactions among monocytes/macrophages and smooth muscle cells and their relevance for atherosclerosis.

Macrophages, smooth muscle cells (SMCs), and their interactions have key roles in the pathogenesis of atherosclerotic vascular diseases. In atheroma development, the phenotype of macrophages and SMCs change, which may influence the disease progression. Accumulating data on the phenotypes exhibited by these cells within atherosclerotic lesions raise many questions regarding the mechanisms and factors that might control the transition of cell phenotype. SMCs often reside in vascular lesions in close proximity to macrophage clusters and are most likely influenced by factors released from these proinflammatory phagocytes. Moreover, macrophages may be influenced by direct contact with SMCs or soluble factors released by these cells. Macrophages may promote activation and induce proatherogenic functions of SMCs, and SMCs may modulate macrophage phenotype. Addressing the mechanisms involved in SMC-macrophage crosstalk that lead to phenotypic modulation of both cell types may provide new insight into atherogenesis and new targets for therapies of various vascular diseases.

Functional analysis of the fractalkine gene promoter in human aortic smooth muscle cells exposed to proinflammatory conditions.

Fractalkine (Fk) and its receptor CX3C receptor 1 contribute effectively to the atherosclerotic process, mediating the recruitment of leukocytes and promoting the interactions between monocytes/macrophages and smooth muscle cells (SMCs). As Fk expression is significantly increased in SMCs during atherogenesis, we aimed to uncover the detailed molecular mechanisms of transcriptional regulation of the Fk gene. For this purpose, we cloned and characterized the human Fk promoter, and studied the specific roles of different transcription factors in its regulation in human aortic SMCs activated by interferon-γ. In silico analysis of the Fk promoter indicated the presence of binding sites for various inflammatory modulators, such as nuclear factor-κB (NF-κB), signal transducer and activator of transcription (STAT)1/STAT3, and activator protein-1. Using a luciferase reporter plasmid, we identified a 2046-bp region spanning the transcriptional start point of the Fk gene, which has strong constitutive promoter activity in SMCs. The effects of interferon-γ on both Fk reporter activity and endogenous transcription were abolished by silencing NF-κB, STAT1, and STAT3. Transient overexpression of p65/NF-κB and STAT1/STAT3 increased Fk promoter activity, whereas c-Jun/activator protein-1 overexpression had no effect. The results obtained with chromatin immunoprecipitation assays revealed the existence of physical interactions of p65 and STAT1/STAT3 with the predicted elements of the Fk promoter. Moreover, Fk-promoted monocyte chemotaxis was dependent on the janus kinase-STAT pathway. Investigation of the detailed molecular mechanisms by cloning and characterizing potential transcriptional response elements has identified the Fk regulatory mechanism in activated human SMCs.

Subendothelial resistin enhances monocyte transmigration in a co-culture of human endothelial and smooth muscle cells by mechanisms involving fractalkine, MCP-1 and activation of TLR4 and Gi/o proteins signaling.

The cytokine resistin and the chemokine fractalkine (FKN) were found at increased levels in human atherosclerotic plaque, in the subendothelium, but their role in this location still needs to be characterized. Recently, high local resistin in the arterial vessel wall was shown to contribute to an enhanced accumulation of macrophages by mechanisms that need to be clarified. Our recent data showed that resistin activated smooth muscle cells (SMC) by up-regulating FKN and MCP-1 expression and monocyte chemotaxis by activating toll-like receptor 4 (TLR4) and Gi/o proteins. Since in the vessel wall both endothelial cells (EC) and SMC respond to cytokines and promote atherosclerosis, we questioned whether subendothelial resistin (sR) has a role in vascular cells cross-talk leading to enhanced monocyte transmigration and we investigated the mechanisms involved. To this purpose we used an in vitro system of co-cultured SMC and EC activated by sR and we analyzed monocyte transmigration. Our results indicated that: (1) sR enhanced monocyte transmigration in EC/SMC system compared to EC cultured alone; (2) sR activated TLR4 and Gi/o signaling in EC/SMC system and induced the secretion of more FKN and MCP-1 compared to EC cultured alone and used both chemokines to specifically recruit monocytes by CX3CR1 and CCR2 receptors. Moreover, FKN produced by resistin in EC/SMC system, by acting on CX3CR1 on EC/SMC specifically contributes to MCP-1 secretion in the system and to the enhanced monocyte transmigration. Our study indicates new possible targets for therapy to reduce resistin-dependent enhanced macrophage infiltration in the atherosclerotic arterial wall.