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The chemokine receptor CCR4 has emerged as a skin-homing molecule important for the migration of T cells from the blood to the dermis. From our previous data on psoriasis patients, CCR4+ memory T cells emerged as a putative recirculating population between skin and blood. Here we focused our attention on the expression of CCR4 and skin-tropic molecules in the different stages of memory T cell differentiation. We analyzed the chemokine receptor profile in CD8+ and CD4+ CD45RA−CCR7+ (TCM) and CD45RA−CCR7− (TEM) cells. Subpopulations were further divided on the basis of CD62L expression, and the distribution among the subsets of the skin-homing molecule CLA (Cutaneous Lymphocyte Antigen) was evaluated. The characterization was performed on peripheral blood mononuclear cells isolated from 21 healthy subjects and 24 psoriasis patients. The results indicate that (i) the skin-homing CCR4 marker is mainly expressed in TCM cells, (ii) CCR4+ TCM cells also express high level of CLA and that (iii) the more differentiated phenotype TEM expresses CXCR3 and CCR5 but lower level of CCR4 and CLA. This indicates that progressive stages of memory T cell differentiation have profoundly different chemokine receptor patterns, with CD8+ TCM displaying a marked skin-tropic phenotype CLA+CCR4+. Differential skin-tropic phenotype between TCM and TEM cells was observed in both healthy subjects and psoriasis patients. However, patients showed an expanded circulating population of CD8+ TCM cells with phenotype CCR4+CXCR3+ that could play a role in the pathophysiology of psoriasis and possibly in disease recurrence.

The aim of this study is to identify subsets of T cells differentially represented in the circulation of patients with psoriatic arthritis and to evaluate the possibility that they can recirculate between peripheral blood and the inflamed joints. We analyzed the phenotype and cytokine expression in circulating CD8+ and CD4+ T cells in 69 subjects: 28 with cutaneous psoriasis, 15 patients with psoriatic arthritis, and 26 healthy subjects. In the circulation, the percentage of each subset was compared among the groups and correlation was calculated with the serum concentration of C-reactive protein. To investigate the migration of T cells towards the inflamed joints, we performed a transwell migration assay towards patient serum and synovial fluid. In selected patients we analyzed in parallel T cells from peripheral blood and from synovial fluid. In the circulation, we found increased percentage of CD8+ CCR6+ T cell effectors expressing CD69 and of IL-17-producing T cells in patients with psoriatic arthritis. CD8+ effector/effector memory T cells showed increased migration towards synovial fluid. Finally, in synovial fluid we found accumulation of CXCR3+ CD8+ T cells and CD69+ cells. CD4+ T cells in the two compartments shared many similarities with CD8+ T cells. The results indicate a role for memory T cell effectors in systemic and joint manifestations of psoriatic arthritis.

Blood to skin recirculation could play a role in the pathogenesis of psoriasis. To investigate this possibility we dissected the phenotype of circulating T cells in psoriasis patients, calculated the correlation the clinical parameters of the disease and performed a parallel bioinformatics analysis of gene expression data in psoriatic skin. We found that circulating CCR6+ CD4+ TEM and TEFF cells significantly correlated with systemic inflammation. Conversely, the percentage of CXCR3+ CD4+ TEM cells negatively correlated with the severity of the cutaneous disease. Importantly CLA+ CD4+ TCM cells expressing CCR6+ or CCR4+ CXCR3+ negatively correlated with psoriasis severity suggesting recruitment to the skin compartment. This assumption was reinforced by gene expression data showing marked increase of CCR7 and CLA-encoding gene SELPLG expression in psoriatic skin and strong association of their expression. The data enlightens a role for CD4+ T cells trafficking between blood and skin in cutaneous and systemic manifestations of psoriasis.

Recent results have identified critical components of the T cell response involved in the initiation and amplification phases of psoriasis. However the link between T cell responses arising in the skin and the systemic inflammation associated with severe psoriasis is largely unknown. We hypothesized that specific subsets of memory T cells recirculating from the skin could play a role. We therefore dissected the circulating memory T cell compartment in patients by analyzing the TCM, TEM and Teff phenotype, the pattern of CCR4 and CCR5 chemokine receptor expression and the expression of the tissue homing molecule CD103. For each subset we calculated the correlation with the Psoriasis Area and Severity Index (PASI) and with the extent of systemic inflammation measured as serum level of the prototypic short pentraxin, C reactive protein (CRP). Validation was performed by comparison with gene expression data in psoriatic plaques. We found that circulating CD103+CCR4+CCR5+ and CCR4+CCR6- CD8+ Teff cells, were highly correlated with CRP levels as well as with the validated index PASI, reflecting a link between skin involvement and systemic inflammation in patients with severe psoriasis. In addition we observed a contraction of circulating CCR5+ T cells in psoriasis patients, with a highly significant inverse correlation between CCR5+CD4 T cells and the PASI score. Increased expression of CCR5 and CCL5 genes in psoriatic skin lesions was consistent with an accumulation of CCR5+ cells in psoriatic plaques indicating a role for CCR5/CCL5 axis in disease pathogenesis.

This paper combines social movement and organizational theory to explore boundary definition in civic organizational fields. Drawing upon evidence from two British cities, and applying network analysis to relations between organizations interested in environmental and ethnicity and migration issues, we show that identities shape network patterns more consistently than interest in specific issues. While this finding supports previous insights from organizational and social movement research on the relation between identities and fields, we go beyond them, in showing that the role of identities is pivotal regardless of the nature of local political opportunity structures and cultures. We conclude by discussing possible strategies for exploring the link between organizational and social movement fields., SCOPUS: ar.j, info:eu-repo/semantics/published

This paper combines social movement and organizational theory to explore boundary definition in civic organizational fields. Drawing upon evidence from two British cities, and applying network analysis to relations between organizations interested in environmental and ethnicity and migration issues, we show that identities shape network patterns more consistently than interest in specific issues. While this finding supports previous insights from organizational and social movement research on the relation between identities and fields, we go beyond them, in showing that the role of identities is pivotal regardless of the nature of local political opportunity structures and cultures. We conclude by discussing possible strategies for exploring the link between organizational and social movement fields., SCOPUS: ar.j, info:eu-repo/semantics/published

info:eu-repo/semantics/published

info:eu-repo/semantics/published

Different European nation-states use the most diverse statistical constructions of foreign origin or ethnic minority populations. Several countries traditionally even shun from producing such data. This makes international comparison a very difficult endeavour. Anyone wanting to perform comparative research on immigrants or (immigrant origin) ethnic minorities in Europe is unavoidably confronted with the most diverse types of national statistical data and has to opt for ad hoc solutions. Attempts at international comparison can thus be very tricky due to data characteristics. It is important that researchers are aware of these problems and do not simply accept data (especially in comparisons) at face value. In this article we embark on a comparative explorative study of the way in which immigrant background and immigration related ethnicity is taken stock of by national statistical institutes in a set of European nation-states., info:eu-repo/semantics/published

Different European nation-states use the most diverse statistical constructions of foreign origin or ethnic minority populations. Several countries traditionally even shun from producing such data. This makes international comparison a very difficult endeavour. Anyone wanting to perform comparative research on immigrants or (immigrant origin) ethnic minorities in Europe is unavoidably confronted with the most diverse types of national statistical data and has to opt for ad hoc solutions. Attempts at international comparison can thus be very tricky due to data characteristics. It is important that researchers are aware of these problems and do not simply accept data (especially in comparisons) at face value. In this article we embark on a comparative explorative study of the way in which immigrant background and immigration related ethnicity is taken stock of by national statistical institutes in a set of European nation-states., info:eu-repo/semantics/published

The authors present a new methodology for estimating the concentration of sea water optically active constituents from remotely sensed hyperspectral data, based on generalized radial basis function neural networks (GRBF-NNs). This family of NNs is particularly suited to approximate relationships like those between hyperspectral reflectance data and the concentrations of optically active constituents of the water body, which are highly nonlinear, especially in case II waters. Three main water constituents are taken into account: phytoplankton, nonchlorophyllous particles, and yellow substance. Each parameter is estimated by means of a specific multi-input single-output GRBF-NN. The authors adopt a recently proposed network learning strategy based on the combined use of the regression tree procedure and forward selection. The effectiveness of this approach, which is completely general and can be easily applied to any hyperspectral sensor, is proved using data simulated with an ocean color model over the channels of the medium resolution imaging spectrometer (MERIS), the new generation ESA sensor to be launched in 2001. The authors define the estimation algorithms over waters of cases I, II, and I+II and compare their performance with that of classical band-ratio, single-band, and multilinear algorithms. Generally, the GRBF-NN algorithms outperform the classical ones, except for the multilinear over case I waters. A particular improvement Is over case II waters, where the mean square error (MSE) can be reduced by one or two orders of magnitude over the error of multilinear and band-ratio algorithms, respectively

The authors present a new methodology for estimating the concentration of sea water optically active constituents from remotely sensed hyperspectral data, based on generalized radial basis function neural networks (GRBF-NNs). This family of NNs is particularly suited to approximate relationships like those between hyperspectral reflectance data and the concentrations of optically active constituents of the water body, which are highly nonlinear, especially in case II waters. Three main water constituents are taken into account: phytoplankton, nonchlorophyllous particles, and yellow substance. Each parameter is estimated by means of a specific multi-input single-output GRBF-NN. The authors adopt a recently proposed network learning strategy based on the combined use of the regression tree procedure and forward selection. The effectiveness of this approach, which is completely general and can be easily applied to any hyperspectral sensor, is proved using data simulated with an ocean color model over the channels of the medium resolution imaging spectrometer (MERIS), the new generation ESA sensor to be launched in 2001. The authors define the estimation algorithms over waters of cases I, II, and I+II and compare their performance with that of classical band-ratio, single-band, and multilinear algorithms. Generally, the GRBF-NN algorithms outperform the classical ones, except for the multilinear over case I waters. A particular improvement Is over case II waters, where the mean square error (MSE) can be reduced by one or two orders of magnitude over the error of multilinear and band-ratio algorithms, respectively

The OMEGA Project (Observing and Modelling of Eddy Scale Geostrophic and Ageostrophic circulation) was funded by the European Commission in the framework of the MAST Programme (MAS3-CT95-0001). [...]

This article uses empirical evidence on networks of voluntary organizations mobilizing on ethnic minority, environmental, and social exclusion issues in two British cities, to differentiate between social movement processes and other, cognate collective action dynamics. Social movement processes are identified as the building and reproducing of dense informal networks between a multiplicity of actors, sharing a collective identity, and engaged in social and/or political conflict. They are contrasted to coalitional processes, where alliances to achieve specific goals are not backed by significant identity links, and organizational processes, where collective action takes place mostly in reference to specific organizations rather than broader, looser networks.

This article uses empirical evidence on networks of voluntary organizations mobilizing on ethnic minority, environmental, and social exclusion issues in two British cities, to differentiate between social movement processes and other, cognate collective action dynamics. Social movement processes are identified as the building and reproducing of dense informal networks between a multiplicity of actors, sharing a collective identity, and engaged in social and/or political conflict. They are contrasted to coalitional processes, where alliances to achieve specific goals are not backed by significant identity links, and organizational processes, where collective action takes place mostly in reference to specific organizations rather than broader, looser networks.