CX3CL1 deficiency ameliorates inflammation, apoptosis and accelerates osteogenic differentiation, mineralization in LPS-treated MC3T3-E1 cells via its receptor CX3CR1.

BACKGROUND: Osteoporosis is a devastating skeletal disease responsible for bone fragility and fracture. CX3C chemokine ligand 1 (CX3CL1) is an inflammatory chemokine which has been identified to possess increased expression in the serum of postmenopausal osteoporotic patients. This paper was to illuminate the impacts of CX3CL1 on inflammation, apoptosis and osteogenic differentiation, mineralization in LPS-treated osteoblasts and investigate the regulatory mechanism. METHODS: The viability of MC3T3-E1 cells exposed to elevating doses of LPS was detected by CCK-8 assay. CX3CL1 and C-X3-C motif chemokine receptor 1 (CX3CR1) expression were detected by RT-qPCR and western blot. CX3CR1 expression was examined again following CX3CL1 depletion. The binding of CX3CL1 with CX3CR1 was testified through Co-IP assay. In MC3T3-E1 cells co-transduced with CX3CL1 interference and CX3CR1 overexpression plasmids following LPS exposure, cell activity and inflammation were separately estimated via CCK-8 assay and RT-qPCR. Apoptosis was measured by TUNEL assay and western blot. Osteoblast differentiation was evaluated by ALP activity assay, RT-qPCR and western blot. Osteoblast mineralization was assessed by ARS staining, RT-qPCR and western blot. Results The experimental data presented that LPS attenuated the viability and enhanced CX3CL1 and CX3CR1 expression in MC3T3-E1 cells in a dose-dependent manner. CX3CR1 interacted with CX3CL1 and was positively modulated by CX3CL1. The suppressive role of CX3CL1 absence in LPS-evoked viability decrease, inflammation and apoptosis in MC3T3-E1 cells was reversed by CX3CR1 elevation. Besides, CX3CR1 reversed the promoted osteoblast differentiation and mineralization imposed by CX3CL1 interference. CONCLUSIONS: CX3CL1 knockdown eased inflammation, apoptosis and promoted osteogenic differentiation, mineralization in MC3T3-E1 cells upon LPS exposure through down-regulating CX3CR1.

Respiratory Syncytial Virus (RSV) G Protein Vaccines With Central Conserved Domain Mutations Induce CX3C-CX3CR1 Blocking Antibodies.

Respiratory syncytial virus (RSV) infection can cause bronchiolitis, pneumonia, morbidity, and some mortality, primarily in infants and the elderly, for which no vaccine is available. The RSV attachment (G) protein contains a central conserved domain (CCD) with a CX3C motif implicated in the induction of protective antibodies, thus vaccine candidates containing the G protein are of interest. This study determined if mutations in the G protein CCD would mediate immunogenicity while inducing G protein CX3C-CX3CR1 blocking antibodies. BALB/c mice were vaccinated with structurally-guided, rationally designed G proteins with CCD mutations. The results show that these G protein immunogens induce a substantial anti-G protein antibody response, and using serum IgG from the vaccinated mice, these antibodies are capable of blocking the RSV G protein CX3C-CX3CR1 binding while not interfering with CX3CL1, fractalkine.

Differential CXC and CX3C Chemokine Expression Profiles in Aqueous Humor of Patients With Specific Endogenous Uveitic Entities.

Purpose: To determine the levels of the neutrophil chemoattractants CXCL1, CXCL2, CXCL5, CXCL6, and CXCL8, the T helper 1 chemoattractants CXCL9, CXCL10 and CXCL11, the lymphoid chemokines CXCL12 and CXCL13 and the soluble form of the transmembrane chemokines CXCL16 and CX3CL1, in aqueous humor samples from patients with specific uveitic entities. Methods: Aqueous humor samples from patients with active uveitis associated with Behçet's disease (n = 13), sarcoidosis (n = 8), HLA-B27-related inflammation (n = 12), Vogt-Koyanagi-Harada (VKH) disease (n = 12), and healthy controls (n = 9) were assayed with the use of a multiplex assay. Results: All chemoattractant levels were significantly higher in all patients than in the controls. The levels of all neutrophil chemoattractants and CXCL10, CXCL16, and CX3CL1 were significantly higher in nongranulomatous uveitis (Behçet's disease and HLA-B27-associated uveitis) than in granulomatous uveitis (sarcoidosis and VKH disease), whereas the levels of the B cell chemoattractant CXCL13 were significantly higher in granulomatous uveitis than in nongranulomatous uveitis. CXCL13 levels were highest in the patients with VKH disease. CXCL9, CXCL11, and CXCL12 levels did not differ significantly. Conclusions: Inflammation in nongranulomatous uveitis appears to be driven by neutrophils and T helper 1 lymphocytes, whereas B lymphocytes may contribute to the inflammatory process in granulomatous uveitis, particularly in VKH disease.

Mutating the CX3C Motif in the G Protein Should Make a Live Respiratory Syncytial Virus Vaccine Safer and More Effective.

Respiratory syncytial virus (RSV) belongs to the family Paramyxoviridae and is the single most important cause of serious lower respiratory tract infections in young children, yet no highly effective treatment or vaccine is available. Through a CX3C chemokine motif (182CWAIC186) in the G protein, RSV binds to the corresponding chemokine receptor, CX3CR1. Since RSV binding to CX3CR1 contributes to disease pathogenesis, we investigated whether a mutation in the CX3C motif by insertion of an alanine, A186, within the CX3C motif, mutating it to CX4C (182CWAIAC187), which is known to block binding to CX3CR1, might decrease disease. We studied the effect of the CX4C mutation in two strains of RSV (A2 and r19F) in a mouse challenge model. We included RSV r19F because it induces mucus production and airway resistance, two manifestations of RSV infection in humans, in mice. Compared to wild-type (wt) virus, mice infected with CX4C had a 0.7 to 1.2 log10-fold lower virus titer in the lung at 5 days postinfection (p.i.) and had markedly reduced weight loss, pulmonary inflammatory cell infiltration, mucus production, and airway resistance after challenge. This decrease in disease was not dependent on decrease in virus replication but did correspond to a decrease in pulmonary Th2 and inflammatory cytokines. Mice infected with CX4C viruses also had higher antibody titers and a Th1-biased T cell memory response at 75 days p.i. These results suggest that the CX4C mutation in the G protein could improve the safety and efficacy of a live attenuated RSV vaccine.IMPORTANCE RSV binds to the corresponding chemokine receptor, CX3CR1, through a CX3C chemokine motif (182CWAIC186) in the G protein. RSV binding to CX3CR1 contributes to disease pathogenesis; therefore, we investigated whether a mutation in the CX3C motif by insertion of an alanine, A186, within the CX3C motif, mutating it to CX4C (182CWAIAC187), known to block binding to CX3CR1, might decrease disease. The effect of this mutation and treatment with the F(ab')2 form of the anti-RSV G 131-2G monoclonal antibody (MAb) show that mutating the CX3C motif to CX4C blocks much of the disease and immune modulation associated with the G protein and should improve the safety and efficacy of a live attenuated RSV vaccine.

Role of the CX3C chemokine receptor CX3CR1 in the pathogenesis of atherosclerosis after aortic transplantation.

BACKGROUND: The CX3C chemokine receptor CX3CR1 is expressed on monocytes as well as tissue resident cells, such as smooth muscle cells (SMCs). Its role in atherosclerotic tissue remodeling of the aorta after transplantation has not been investigated. METHODS: We here have orthotopically transplanted infrarenal Cx3cr1-/-Apoe-/- and Cx3cr1+/+Apoe-/- aortic segments into Apoe-/-mice, as well as Apoe-/- aortic segments into Cx3cr1-/-Apoe-/- mice. The intimal plaque size and cellular plaque composition of the transplanted aortic segment were analyzed after four weeks of atherogenic diet. RESULTS: Transplantation of Cx3cr-/-Apoe-/- aortic segments into Apoe-/- mice resulted in reduced atherosclerotic plaque formation compared to plaque size in Apoe-/- or Cx3cr1-/-Apoe-/- mice after transplantation of Apoe-/- aortas. This reduction in lesion formation was associated with reduced numbers of lesional SMCs but not macrophages within the transplanted Cx3cr-/- Apoe-/- aortic segment. No differences in frequencies of proliferating and apoptotic cells could be observed. CONCLUSION: These results indicate that CX3CR1 on resident vessel wall cells plays a key role in atherosclerotic plaque formation in transplanted aortic grafts. Targeting of vascular CX3CL1/CX3CR1 may therefore be explored as a therapeutic option in vascular transplantation procedures.

Actions of Thyroid Hormone Analogues on Chemokines.

The extracellular domain of plasma membrane integrin αvß3 contains a receptor for thyroid hormone (L-thyroxine, T4; 3,5,3'-triiodo-L-thyronine, T3); this receptor also binds tetraiodothyroacetic acid (tetrac), a derivative of T4. Tetrac inhibits the binding of T4 and T3 to the integrin. Fractalkine (CX3CL1) is a chemokine relevant to inflammatory processes in the CNS that are microglia-dependent but also important to normal brain development. Expression of the CX3CL1 gene is downregulated by tetrac, suggesting that T4 and T3 may stimulate fractalkine expression. Independently of its specific receptor (CX3CR1), fractalkine binds to αvß3 at a site proximal to the thyroid hormone-tetrac receptor and changes the physical state of the integrin. Tetrac also affects expression of the genes for other CNS-relevant chemokines, including CCL20, CCL26, CXCL2, CXCL3, and CXCL10. The chemokine products of these genes are important to vascularity of the brain, particularly of the choroid plexus, to inflammatory processes in the CNS and, in certain cases, to neuroprotection. Thyroid hormones are known to contribute to regulation of each of these CNS functions. We propose that actions of thyroid hormone and hormone analogues on chemokine gene expression contribute to regulation of inflammatory processes in brain and of brain blood vessel formation and maintenance.

Respiratory syncytial virus G protein CX3C motif impairs human airway epithelial and immune cell responses.

Respiratory syncytial virus (RSV) is a major cause of severe lower respiratory infection in infants and young children and causes disease in the elderly and persons with compromised cardiac, pulmonary, or immune systems. Despite the high morbidity rates of RSV infection, no highly effective treatment or vaccine is yet available. The RSV G protein is an important contributor to the disease process. A conserved CX3C chemokine-like motif in G likely contributes to the pathogenesis of disease. Through this motif, G protein binds to CX3CR1 present on various immune cells and affects immune responses to RSV, as has been shown in the mouse model of RSV infection. However, very little is known of the role of RSV CX3C-CX3CR1 interactions in human disease. In this study, we use an in vitro model of human RSV infection comprised of human peripheral blood mononuclear cells (PBMCs) separated by a permeable membrane from human airway epithelial cells (A549) infected with RSV with either an intact CX3C motif (CX3C) or a mutated motif (CX4C). We show that the CX4C virus induces higher levels of type I/III interferon (IFN) in A549 cells, increased IFN-α and tumor necrosis factor alpha (TNF-α) production by human plasmacytoid dendritic cells (pDCs) and monocytes, and increased IFN-γ production in effector/memory T cell subpopulations. Treatment of CX3C virus-infected cells with the F(ab')2 form of an anti-G monoclonal antibody (MAb) that blocks binding to CX3CR1 gave results similar to those with the CX4C virus. Our data suggest that the RSV G protein CX3C motif impairs innate and adaptive human immune responses and may be important to vaccine and antiviral drug development.

Nanoparticle vaccines encompassing the respiratory syncytial virus (RSV) G protein CX3C chemokine motif induce robust immunity protecting from challenge and disease.

Nanoparticle vaccines were produced using layer-by-layer fabrication and incorporating respiratory syncytial virus (RSV) G protein polypeptides comprising the CX3C chemokine motif. BALB/c mice immunized with G protein nanoparticle vaccines produced a neutralizing antibody response that inhibited RSV replication in the lungs following RSV challenge. ELISPOT analysis showed that G nanoparticle vaccinated mice had increased levels of RSV G protein-specific IL-4 and IFN-γ secreting cells compared to controls following RSV challenge. Remarkably, RSV challenge of G protein nanoparticle vaccinated mice resulted in increased RSV M2-specific IL-4 and IFN-γ secreting T cells, and increased M2-specific H-2Kd-tetramer positive CD8(+) T cells in the lungs compared to controls. Cell type analysis showed vaccination was not associated with increased pulmonary eosinophilia following RSV challenge. These results demonstrate that vaccination of mice with the RSV G protein nanoparticle vaccines induces a potent neutralizing antibody response, increased G protein- and M2-specific T cell responses, and a reduction in RSV disease pathogenesis.

Antibodies to the central conserved region of respiratory syncytial virus (RSV) G protein block RSV G protein CX3C-CX3CR1 binding and cross-neutralize RSV A and B strains.

Respiratory syncytial virus (RSV) is a primary cause of severe lower respiratory tract disease in infants, young children, and the elderly worldwide, and despite decades of effort, there remains no safe and effective vaccine. RSV modifies the host immune response during infection by CX3C chemokine mimicry adversely affecting pulmonary leukocyte chemotaxis and CX3CR1+ RSV-specific T-cell responses. In this study we investigated whether immunization of mice with RSV G protein polypeptides from strain A2 could induce antibodies that block G protein-CX3CR1 interactions of both RSV A and B strains. The results show that mice immunized with RSV A2 G polypeptides generate antibodies that block binding of RSV A2 and B1 native G proteins to CX3CR1, and that these antibodies effectively cross-neutralize both A and B strains of RSV. These findings suggest that vaccines that induce RSV G protein-CX3CR1 blocking antibodies may provide a disease intervention strategy in the efforts to develop safe and efficacious RSV vaccines.

In vivo structure/function and expression analysis of the CX3C chemokine fractalkine.

The CX3C chemokine family is composed of only one member, CX3CL1, also known as fractalkine, which in mice is the sole ligand of the G protein-coupled, 7-transmembrane receptor CX3CR1. Unlike classic small peptide chemokines, CX3CL1 is synthesized as a membrane-anchored protein that can promote integrin-independent adhesion. Subsequent cleavage by metalloproteases, either constitutive or induced, can generate shed CX3CL1 entities that potentially have chemoattractive activity. To study the CX3C interface in tissues of live animals, we generated transgenic mice (CX3CL1cherry:CX3CR1gfp), which express red and green fluorescent reporter genes under the respective control of the CX3CL1 and CX3CR1 promoters. Furthermore, we performed a structure/function analysis to differentiate the in vivo functions of membrane-tethered versus shed CX3CL1 moieties by comparing their respective ability to correct established defects in macrophage function and leukocyte survival in CX3CL1-deficient mice. Specifically, expression of CX3CL1(105Δ), an obligatory soluble CX3CL1 isoform, reconstituted the formation of transepithelial dendrites by intestinal macrophages but did not rescue circulating Ly6Clo CX3CR1hi blood monocytes in CX3CR1gfp/gfp mice. Instead, monocyte survival required the full-length membrane-anchored CX3CL1, suggesting differential activities of tethered and shed CX3CL1 entities.

[The viral acceptor antagonist to entrapment ligand H9 in vitro activeness and the function to human acceptor CX3-CR1].

AIM: To clarify the activeness of H9 in vitro and internalization and modulation of the surface chemokine receptor CX3CR1 induced by H9, To discuss the influence of H9 on the chemokine receptor CX3CR1. METHODS: Inhibition by chemotactic peptide on the physiological detection of chemokine induced cell migration activity. Flowcytometry examined the effection of H9 on intracellular calcium. Laser scanning confocal microscopy and flow cytometry were used to determine the quality and quantity of CX3CR1 internalization. RESULTS: H9 was able to block the migration induced by chemokine receptor. In the chemoattraction test, H9 was unable to induce the chemotactic movement, and it does not affect the signal transduction and activeness of cells. It was found that H9 could induce internalization with a maximal rate of 70%, at the concentration of 200 ng/mL. The internalized CX3CR1 molecules could recycled to the cell surface. CONCLUSION: H9 makes human CX3CR1 internalize. After internalizing, the CX3CR1 receptor recirculates the cell surface. It does not affect CX3CR1 physiology function. H9 could be used as a specificity anti-virus peptide.

Neuropatogénesis inducida por el virus del sida: estrategias terapéuticas frente a la neurodegeneración inducida por la glucoproteína gp120/Tat en el sistema nervioso central / Summary. Neuroinflammation is a key process in the neuropathogenesis of AIDS virus since as a result of the aberrant in the central nervous system

La neuroinflamación constituye un proceso clave en la neuropatogénesis del virus del sida como consecuencia de la activación aberrante de receptores de quimiocinas (CXCR4, CX3CR1 y CCR5), ya que la liberación de citocinas proinflamatorias por las células infectadas amplifica la neurotoxicidad microglial y genera lipoperóxidos y especies reactivas de oxígeno que, en última instancia, dañan la neurona. Por otro lado, la neurotoxina Tat induce alteraciones dendríticas por interacción con el receptor LRP (receptor de lipoproteínas de baja densidad) e induce una excesiva estimulación de los receptores de N-metil D-aspartato. Además, la interacción aberrante de la glucoproteína gp120 con el receptor CXCR4 induce apoptosis dependiente de caspasa 3 (también libera ceramida) y activa las proteínas apoptóticas p53 y retinoblastoma como mecanismos neurotóxicos asociados a la disfunción neural en el virus de la inmunodeficiencia humana 1 (VIH-1). Asimismo, la gliosis/activación microglial y la liberación de factores virales por los monocitos infectados, y el incremento de determinadas quimiocinas en el líquido cefalorraquídeo (MCP-1 y fractalcina, entre otras), contribuyen a la neuropatogénesis del VIH-1. Por otro lado, se han detectado depósitos de alfa-sinucleína y de beta-amiloide en cerebros post mortem de seropositivos de edad avanzada. Además, se han descrito varios marcadores sistémicos relacionados con los efectos degenerativos del virus y de sus neurotoxinas en el sistema nervioso central, tales como osteopontina, CD163 y fractalcina, entre otros. Por último, se han realizado ensayos clínicos basados en estrategias protectoras relacionadas con la inhibición de proteínas apoptóticas (inhibidores de GSK-3 beta), con inhibidores de la activación microglial (minociclina), antioxidantes (selegilina) o factores tróficos (IGF-1, hormona del crecimiento o eritropoyetina), que muestran efectos beneficiosos como tratamientos complementarios a la terapia antirretroviral (AU)

Neuroinflammation is a key process in the neuropathogenesis of AIDS virus since as a result of the aberrant activation of the chemokine receptors (CXCR4, CX3CR1 and CR5) produces proinflammatory cytokine release by infected cells, increases microglial neurotoxicity and generates lipoperoxides and reactive oxygen species (ROS) that eventually damage the neuron. Moreover, the neurotoxin Tat produces dendritic loss by interacting with the low-density lipoprotein receptor (LRP) and also overstimulates N-methyl D-aspartate receptors (NMDA). Furthermore, the aberrant interaction of glycoprotein gp120 with the CXCR4 chemokine receptor causes caspase-3-dependent apoptosis (ceramide is also released) activating apoptotic proteins (p53 and retinoblastoma), which are part of the neurotoxic mechanisms associated to neuronal dysfunction in neuroAIDS. Similarly, gliosis/microglial activation and the release of neurotoxic factors by infected monocytes with elevated amounts of certain chemokines in the cerebrospinal fluid (MCP-1 and fractalkine, among others) contribute to the neuropathogenesis of HIV-1. Alpha-synuclein and beta amyloid deposits have also been detected in post mortem brains of seropositives patients. In addition, there are studies have detected several systemic markers related with the degenerative effects of the virus and its neurotoxins on the central nervous system; such as osteopontin, CD163 and fractalkine, among others. Lastly, clinical trials have been conducted using protective strategies related that attempt to inhibit apoptotic proteins (GSK-3 beta), microglial activation inhibitors (minocycline), antioxidants (selegiline) or trophic factors (IGF-1, growth hormone or erythropoietin). These trials have shown that their treatments are beneficial and complementary to treat complications of HIV/AIDS (AU)

Vaccination to induce antibodies blocking the CX3C-CX3CR1 interaction of respiratory syncytial virus G protein reduces pulmonary inflammation and virus replication in mice.

Respiratory syncytial virus (RSV) infection causes substantial morbidity and some deaths in the young and elderly worldwide. There is no safe and effective vaccine available, although it is possible to reduce the hospitalization rate for high-risk children by anti-RSV antibody prophylaxis. RSV has been shown to modify the immune response to infection, a feature linked in part to RSV G protein CX3C chemokine mimicry. This study determined if vaccination with G protein polypeptides or peptides spanning the central conserved region of the G protein could induce antibodies that blocked G protein CX3C-CX3CR1 interaction and disease pathogenesis mediated by RSV infection. The results show that mice vaccinated with G protein peptides or polypeptides containing the CX3C motif generate antibodies that inhibit G protein CX3C-CX3CR1 binding and chemotaxis, reduce lung virus titers, and prevent body weight loss and pulmonary inflammation. The results suggest that RSV vaccines that induce antibodies that block G protein CX3C-CX3CR1 interaction may offer a new, safe, and efficacious RSV vaccine strategy.

Role of CX3C-chemokine CX3C-L/fractalkine expression in a model of slowly progressive renal failure.

BACKGROUND: The chemokine/chemokine receptor pair CX(3)C-L/CX(3)C-R is suspected to play a role in renal fibrogenesis. The aim of this study was to investigate their function in an animal model of slowly progressive chronic renal failure. METHODS: Functional data were analysed in folic acid nephropathy (FAN) at different time points (up to day 142 after induction). Immunostaining for CX(3)C-L, CD3, S100A4, collagen type I, fibronectin, alpha-smooth muscle actin, Tamm-horsfall protein, aquaporin 1 and 2 as well as quantitative real-time PCR (qRT-PCR) for CX(3)C-L, CX(3)C-R and fibroblast-specific protein 1 (FSP-1) were performed. Additionally, regulatory mechanisms and functional activity of CX(3)C-L in murine proximal and distal tubular epithelial cells as well as in fibroblasts were investigated. RESULTS: CX(3)C-L/GAPDH ratio was upregulated in FAN 3.4-fold at day 7 further increasing up to 7.1-fold at day 106. The expression of mRNA CX(3)C-L correlated well with CX(3)C-R (R(2) = 0.96), the number of infiltrating CD3+ cells (R(2) = 0.60) and the degree of tubulointerstitial fibrosis (R(2) = 0.56) and moderately with FSP-1 (R(2) = 0.33). Interleukin-1beta, tumour necrosis factor-alpha, transforming growth factor-beta as well as the reactive oxygen species (ROS) H(2)O(2) were identified by qRT-PCR as inductors of CX(3)C-L/fractalkine (FKN) in tubular epithelial cells. Functionally, CX(3)C-L/FKN chemoattracts peripheral blood mononuclear cells, activates several aspects of fibrogenesis and induces the mitogen-activated protein kinases in renal fibroblasts. CONCLUSIONS: In FAN, there is a good correlation between the expression of CX(3)C-L with markers of interstitial inflammation and fibrosis which may result from upregulation by pro-inflammatory and pro-fibrotic cytokines as well as by ROS in tubular epithelial cells. The FKN system may promote renal inflammation and renal fibrogenesis.

Inflammation, growth factors, and pulmonary vascular remodeling.

Inflammatory processes are prominent in various types of human and experimental pulmonary hypertension (PH) and are increasingly recognized as major pathogenic components of pulmonary vascular remodeling. Macrophages, T and B lymphocytes, and dendritic cells are present in the vascular lesions of PH, whether in idiopathic pulmonary arterial hypertension (PAH) or PAH related to more classical forms of inflammatory syndromes such as connective tissue diseases, human immunodeficiency virus (HIV), or other viral etiologies. Similarly, the presence of circulating chemokines and cytokines, viral protein components (e.g., HIV-1 Nef), and increased expression of growth (such as vascular endothelial growth factor and platelet-derived growth factor) and transcriptional (e.g., nuclear factor of activated T cells or NFAT) factors in these patients are thought to contribute directly to further recruitment of inflammatory cells and proliferation of smooth muscle and endothelial cells. Other processes, such as mitochondrial and ion channel dysregulation, seem to convey a state of cellular resistance to apoptosis; this has recently emerged as a necessary event in the pathogenesis of pulmonary vascular remodeling. Thus, the recognition of complex inflammatory disturbances in the vascular remodeling process offers potential specific targets for therapy and has recently led to clinical trials investigating, for example, the use of tyrosine kinase inhibitors. This paper provides an overview of specific inflammatory pathways involving cells, chemokines and cytokines, cellular dysfunctions, growth factors, and viral proteins, highlighting their potential role in pulmonary vascular remodeling and the possibility of future targeted therapy.

The roles of chemokines in leukocyte recruitment and fibrosis in systemic sclerosis.

Systemic sclerosis (SSc, scleroderma) is an autoimmune disease characterized by excessive extracellular matrix deposition and vascular injury in the skin and other visceral organs. Although the pathogenesis remains unclear, interactions among leukocytes, endothelial cells, and fibroblasts are likely to be central to the pathogenesis of the disease. Chemokines mediate the leukocyte chemotaxis and migration through endothelia into the organ tissues, leading to the interaction between leukocytes and fibroblasts. While amounts of literatures reported chemokine abnormalities in SSc, which might explain the altered accumulation of effector leukocyte subsets in the affected tissues. Among various chemokines, monocyte chemoattractant protein-1 (MCP-1/CCL2) likely has the most critical role for tissue fibrosis in SSc. Although therapeutic effect for targeting MCP-1 has been demonstrated in mouse models of SSc or fibrotic disorders, it is unknown whether this strategy is effective in human clinical trials. Here recent data will be reviewed on the pathogenic role of chemokines and their receptors in SSc.

Effects of in vitro exposure to hay dust on expression of interleukin-17, -23, -8, and -1beta and chemokine (C-X-C motif) ligand 2 by pulmonary mononuclear cells isolated from horses chronically affected with recurrent airway disease.

OBJECTIVE: To examine effects of in vitro exposure to solutions of hay dust, lipopolysaccharide (LPS), or beta-glucan on cytokine expression in pulmonary mononuclear cells isolated from healthy horses and horses with recurrent airway obstruction (RAO). ANIMALS: 8 RAO-affected and 7 control horses (experiment 1) and 6 of the RAO-affected and 5 of the control horses (experiment 2). PROCEDURES: Bronchoalveolar lavage cells were isolated from horses that had been stabled and fed dusty hay for 14 days. Pulmonary mononuclear cells were incubated for 24 (experiment 1) or 6 (experiment 2) hours with PBS solution or solutions of hay dust, beta-glucan, or LPS. Gene expression of interleukin (IL)-17, IL-23(p19 and p40 subunits), IL-8, IL-1beta, and chemokine (C-X-C motif) ligand 2 (CXCL2) was measured with a kinetic PCR assay. RESULTS: Treatment with the highest concentration of hay dust solution for 6 or 24 hours increased expression of IL-23(p19 and p40), IL-8, and IL-1beta in cells from both groups of horses and increased early expression of IL-17 and CXCL2 in RAO-affected horses. Lipopolysaccharide upregulated early expression of IL-23(p40) and IL-8 in cells from both groups of horses but only late expression of these cytokines in cells from RAO-affected horses. Treatment with beta-glucan failed to increase cytokine expression at 6 or 24 hours. CONCLUSIONS AND CLINICAL RELEVANCE: Cells from RAO-affected horses were not more responsive to the ligands tested than were cells from control horses, which suggests a minimal role of mononuclear cells in propagation of airway neutrophilia in horses with chronic RAO.

An oxidized lipid-peroxisome proliferator-activated receptor gamma-chemokine pathway in the regulation of macrophage-vascular smooth muscle cell adhesion.

Recent genetic studies have implicated pro-inflammatory chemokines and chemokine receptors in atherogenesis. Studies at the molecular and cellular levels have suggested specific atherogenic mechanisms for two chemokine-chemokine receptor pairs, CCL2-CCR2 and CX3CL1-CX3CR1, involving differential receptor regulation by the transcription factor peroxisome proliferator-activated receptor gamma. This pathway is triggered by oxidized proatherogenic lipids, such as oxidized low-density lipoprotein and linoleic acid derivatives, which promote differentiation of CCR2(hi)CX3CR1(lo) human monocytes to CCR2(lo)CX3CR1(hi) macrophages that adhere to coronary artery smooth muscle cells in a CX3CR1- and peroxisome proliferator-activated receptor gamma-dependent manner. Switching CX3CR1 on and CCR2 off in vivo may result in cessation of CCR2-dependent migration and activation of CX3CR1-dependent retention that together may promote foam cell accumulation in the vessel wall.

Interleukin-15 inhibits smooth muscle cell proliferation and hyaluronan production in rat ductus arteriosus.

Neointimal cushion formation (NCF) is an important vascular remodeling for anatomical closure of the ductus arteriosus (DA). Inflammatory responses to vascular injury or atherosclerosis are known to be associated with the pathogenesis of NCF. We found that the expression of interleukin (IL)-15 mRNA was significantly higher in rat DA than in the aorta. IL-15 immunoreactivity was detected predominantly in the internal elastic laminae (IEL) and to a lesser extent in smooth muscle cells (SMCs) in rat DA. Prostaglandin E (PGE) increased the expression of IL-15 mRNA in cultured DA SMCs. IL-15 significantly attenuated the platelet-derived growth factor (PDGF)-BB-mediated SMC proliferation, but did not change SMC migration. IL-15 significantly attenuated PGE1-induced hyaluronic acid (HA) production in a dose-dependent manner, which is a potent stimulator of NCF. Accordingly, IL-15 might have an inhibitory effect on the physiologic vascular remodeling processes in closing the DA.

Fractalkine is a novel chemoattractant for rheumatoid arthritis fibroblast-like synoviocyte signaling through MAP kinases and Akt.

OBJECTIVE: Fibroblast-like synoviocytes (FLS) are a major constituent of the hyperplastic synovial pannus that aggressively invades cartilage and bone during the course of rheumatoid arthritis (RA). Fractalkine (FKN/CX(3)CL1) expression is up-regulated in RA synovium and RA synovial fluid. While RA FLS express the FKN receptor, CX(3)CR1, the pathophysiologic relevance of FKN stimulation of RA FLS is not understood. This study was undertaken to better characterize the relationship between FKN and the RA FLS that both produce it and express its receptor. METHODS: RA FLS were subjected to chemotaxis and proliferation assays, Western blotting, enzyme-linked immunosorbent assays, and filamentous actin staining to characterize the relationship between FKN and RA FLS. RESULTS: FKN secretion by RA FLS was regulated mainly by tumor necrosis factor alpha. Stimulation of RA FLS with FKN led to significant cytoskeletal rearrangement but no proliferation. Chemotaxis assays revealed that FKN was a novel chemoattractant for RA FLS. Stimulation of RA FLS with FKN resulted in activation of MAP kinases and Akt. JNK, ERK-1/2, and Akt (at both Ser-473 and Thr-308) were each up-regulated in a time-dependent manner. Inhibition of ERK-1/2-mediated signaling, but not JNK or Akt, significantly repressed FKN-induced RA FLS migration. CONCLUSION: These findings indicate a novel role of FKN in regulating RA FLS cytoskeletal structure and migration. FKN specifically induces RA FLS phosphorylation of the MAP kinases JNK and ERK-1/2, as well as full activation of Akt.