Decreased Neutrophil Apoptosis in Quiescent ANCA-Associated Systemic Vasculitis

Background: ANCA-Associated Systemic Vasculitis (AASV) is characterized by leukocytoclasis, accumulation of unscavenged apoptotic and necrotic neutrophils in perivascular tissues. Dysregulation of neutrophil cell death may contribute directly to the pathogenesis of AASV. less thanbrgreater than less thanbrgreater thanMethods: Neutrophils from Healthy Blood Donors (HBD), patients with AASV most in complete remission, Polycythemia Vera (PV), Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA) and renal transplant recipients (TP) were incubated in vitro, and the rate of spontaneous apoptosis was measured by FACS. Plasma levels of cytokines and sFAS were measured with cytometric bead array and ELISA. Expression of pro/anti-apoptotic factors, transcription factors C/EBP-alpha, C/EBP-beta and PU.1 and inhibitors of survival/JAK2-pathway were measured by real-time-PCR. less thanbrgreater than less thanbrgreater thanResults: AASV, PV and RA neutrophils had a significantly lower rate of apoptosis compared to HBD neutrophils (AASV 50 +/- 14% vs. HBD 64 +/- 11%, p andlt; 0.0001). In RA but not in AASV and PV, low apoptosis rate correlated with increased plasma levels of GM-CSF and high mRNA levels of anti-apoptotic factors Bcl-2A1 and Mcl-1. AASV patients had normal levels of G-CSF, GM-CSF and IL-3. Both C/EBP-alpha, C/EBP-beta were significantly higher in neutrophils from AASV patients than HBD. Levels of sFAS were significantly higher in AASV compared to HBD. less thanbrgreater than less thanbrgreater thanConclusion: Neutrophil apoptosis rates in vitro are decreased in AASV, RA and PV but mechanisms seem to differ. Increased mRNA levels of granulopoiesis-associated transcription factors and increased levels of sFAS in plasma were observed in AASV. Additional studies are required to define the mechanisms behind the decreased apoptosis rates, and possible connections with accumulation of dying neutrophils in regions of vascular lesions in AASV patients.Funding Agencies|Swedish Research Council|71X-15152|Crafoord Foundation||</p

Fas-Mediated Apoptosis Regulates the Composition of Peripheral αβ T Cell Repertoire by Constitutively Purging Out Double Negative T Cells

BACKGROUND: The Fas pathway is a major regulator of T cell homeostasis, however, the T cell population that is controlled by the Fas pathway in vivo is poorly defined. Although CD4 and CD8 single positive (SP) T cells are the two major T cell subsets in the periphery of wild type mice, the repertoire of mice bearing loss-of-function mutation in either Fas (lpr mice) or Fas ligand (gld mice) is predominated by CD4(-)CD8(-) double negative alphabeta T cells that also express B220 and generally referred to as B220+DN T cells. Despite extensive analysis, the basis of B220+DN T cell lymphoproliferation remains poorly understood. In this study we re-examined the issue of why T cell lymphoproliferation caused by gld mutation is predominated by B220+DN T cells. METHODOLOGY AND PRINCIPAL FINDINGS: We combined the following approaches to study this question: Gene transcript profiling, BrdU labeling, and apoptosis assays. Our results show that B220+DN T cells are proliferating and dying at exceptionally high rates than SP T cells in the steady state. The high proliferation rate is restricted to B220+DN T cells found in the gut epithelium whereas the high apoptosis rate occurred both in the gut epithelium and periphery. However, only in the periphery, apoptosis of B220+DN T cell is Fas-dependent. When the Fas pathway is genetically impaired, apoptosis of peripheral B220+DN T cells was reduced to a baseline level similar to that of SP T cells. Under these conditions of normalized apoptosis, B220+DN T cells progressively accumulate in the periphery, eventually resulting in B220+DN T cell lymphoproliferation. CONCLUSIONS/SIGNIFICANCE: The Fas pathway plays a critical role in regulating the tissue distribution of DN T cells through targeting and elimination of DN T cells from the periphery in the steady state. The results provide new insight into pathogenesis of DN T cell lymphoproliferation

Structure/property relationships in polystyrene-polyisobutylene-polystyrene block copolymers

Structure/property relationships of polystyrene-polyisobutylene-polystyrene (PS-PIB-PS) triblock copolymer made by different processes were studied using dynamic mechanical analysis (DMA). The PS-PIB-PS films were composed of approximately 30% polystyrene end-blocks. Small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) confirm that a self-assembled, segregated cylindrical morphology forms in the copolymer. DMA was used as a tool to investigate the structure-property relationships in these polymers. Modified PS-PIB-PS copolymers were also characterized. Modifications of the copolymers were carried out by conversion of approximately 20 mol% of the polystyrene end-blocks to styrene sulfonic acid. The modified copolymers exhibited distinctly different thermal characteristics than the unmodified copolymers, which were most notable in the storage modulus and tan delta data. The presence of sulfonic acid groups disrupted the morphology and solvent sorption characteristics of the copolymers. Dynamic mechanical behavior is discussed as it relates to the morphology of the PS-PIB-PS copolymers formed via different processing methods and chemical modification. (C) 2001 Elsevier Science B.V. All rights reserved

Barbed displacement: walls to the disciplined migrant

International audienc

Identification of systemically expanded activated T cell clones in MRL/lpr and NZB/W F1 lupus model mice

CD4(+) T lymphocytes play an important role in the pathogenesis of systemic lupus erythematosus (SLE). To characterize the clonal expansion of CD4(+) T cells in murine lupus models, we analysed the T cell clonality in various organs of young and nephritic MRL/lpr and NZB/W F1 mice using reverse transcription–polymerase chain reaction (RT-PCR) and subsequent single-strand conformation polymorphism (SSCP) analysis. We demonstrated that some identical T cell clonotypes expanded and accumulated in different organs (the bilateral kidneys, brain, lung and intestine) in nephritic diseased mice, and that a number of these identical clonotypes were CD4(+) T cells. In contrast, young mice exhibited little accumulation of common clones in different organs. The T cell receptor (TCR) Vβ usage of these identical clonotypes was limited to Vβ2, 6, 8·1, 10, 16 and 18 in MRL/lpr mice and to Vβ6 and 7 in NZB/W F1 mice. Furthermore, some conserved amino acid motifs such as I, D or E and G were observed in CDR3 loops of TCRβ chains from these identical CD4(+) clonotypes. The existence of systemically expanding CD4(+) T cell clones in the central nervous system (CNS) suggests the involvement of the systemic autoimmunity in CNS lesions of lupus. FACS-sorted CD4(+)CD69(+) cells from the kidney displayed expanded clonotypes identical to those obtained from the whole kidney and other organs from the same individual. These findings suggest that activated and clonally expanded CD4(+) T cells accumulate in different tissues of nephritic lupus mice, and these clonotypes might recognize restricted T cell epitopes on autoantigens involved in specific immune responses of SLE, thus playing a pathogenic role in these lupus mice