Variants in CXCR4 associate with juvenile idiopathic arthritis susceptibility.

Background: Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease among children, the etiology of which involves a strong genetic component, but much of the underlying genetic determinants still remain unknown. Our aim was to identify novel genetic variants that predispose to JIA.

Methods: We performed a genome-wide association study (GWAS) and replication in a total of 1166 JIA cases and 9500 unrelated controls of European ancestry.

REDD1 Is Essential for Optimal T Cell Proliferation and Survival.

REDD1 is a highly conserved stress response protein that is upregulated following many types of cellular stress, including hypoxia, DNA damage, energy stress, ER stress, and nutrient deprivation. Recently, REDD1 was shown to be involved in dexamethasone induced autophagy in murine thymocytes. However, we know little of REDD1's function in mature T cells.

Importance of evaluating cell cholesterol influx with efflux in determining the impact of human serum on cholesterol metabolism and atherosclerosis.

Objective: Cholesterol efflux relates to cardiovascular disease but cannot predict cellular cholesterol mass changes. We asked whether influx and net flux assays provide additional insights.

Approach And Results: Adapt a bidirectional flux assay to cells where efflux has clinical correlates and examine the association of influx, efflux, and net flux to serum triglycerides (TGs).

Myeloid dendritic cells from B6.NZM Sle1/Sle2/Sle3 lupus-prone mice express an IFN signature that precedes disease onset.

Patients with systemic lupus erythematosus show an overexpression of type I IFN-responsive genes that is referred to as "IFN signature." We found that B6.NZMSle1/Sle2/Sle3 (Sle1,2,3) lupus-prone mice also express an IFN signature compared with non-autoimmune C57BL/6 mice.

HIV-1 Vif promotes the G₁- to S-phase cell-cycle transition.

HIV-1 depends on host-cell resources for replication, access to which may be limited to a particular phase of the cell cycle. The HIV-encoded proteins Vpr (viral protein R) and Vif (viral infectivity factor) arrest cells in the G₂ phase; however, alteration of other cell-cycle phases has not been reported. We show that Vif drives cells out of G₁ and into the S phase.

The HIV-1 Vif protein mediates degradation of Vpr and reduces Vpr-induced cell cycle arrest.

Prior work has implicated viral protein R (Vpr) in the arrest of human immunodeficiency virus type 1 (HIV-1)-infected cells in the G2 phase of the cell cycle, associated with increased viral replication and host cell apoptosis. We and others have recently shown that virion infectivity factor (Vif ) also plays a role in the G2 arrest of HIV-1-infected cells. Here, we demonstrate that, paradoxically, at early time points postinfection, Vif expression blocks Vpr-mediated G2 arrest, while deletion of Vif from the HIV-1 genome leads to a marked increase in G2 arrest of infected CD4 T-cells.

IL-4 suppresses dendritic cell response to type I interferons.

Cytokines play an important role in modulating the development and function of dendritic cells (DCs). Type I IFNs activate DCs and drive anti-viral responses, whereas IL-4 is the prototype of a Th2 cytokine. Evidence suggests that type I IFNs and IL-4 influence each other to modulate DC functions.

Complement receptor 3 ligation of dendritic cells suppresses their stimulatory capacity.

To activate T cells effectively, dendritic cells (DCs) must provide three separate signals, MHC-Ag, costimulatory molecules (such as CD80 and CD86), and proinflammatory cytokines (such as IL-12). These three signals are up-regulated in the presence of "danger signals" such as LPS or viral nucleic acids. Evidence suggests that DCs providing only the first two of these signals cannot successfully stimulate T cells.

The Vif accessory protein alters the cell cycle of human immunodeficiency virus type 1 infected cells.

The viral infectivity factor gene (vif) of HIV-1 increases the infectivity of viral particles by inactivation of cellular anti-viral factors, and supports productive viral replication in primary human CD4 T cells and in certain non-permissive T cell lines. Here, we demonstrate that Vif also contributes to the arrest of HIV-1 infected cells in the G(2) phase of the cell cycle. Viruses deleted in Vif or Vpr induce less cell cycle arrest than wild-type virus, while cells infected with HIV-1 deleted in both Vif and Vpr have a cell cycle profile equivalent to that of uninfected cells.

Effective gene suppression using small interfering RNA in hard-to-transfect human T cells.

RNA interference (RNAi) is an evolutionarily conserved cellular defense mechanism that protects cells from hostile genes and regulates the function of normal genes during growth and development. In this study, we established proof of principle of small interfering RNA (siRNA) silencing in hard-to-transfect human T cell lines and primary human CD4 T cells. We used public and in-house programs to design four siRNAs each for GFP, for our novel cellular gene HALP, and for their corresponding scrambled siRNA controls.

Abnormal costimulatory phenotype and function of dendritic cells before and after the onset of severe murine lupus.

We analyzed the activation and function of dendritic cells (DCs) in the spleens of diseased, lupus-prone NZM2410 and NZB-W/F1 mice and age-matched BALB/c and C57BL/6 control mice. Lupus DCs showed an altered ex vivo costimulatory profile, with a significant increase in the expression of CD40, decreased expression of CD80 and CD54, and normal expression of CD86. DCs from young lupus-prone NZM2410 mice, before the development of the disease, expressed normal levels of CD80 and CD86 but already overexpressed CD40.

Ligation of CD28 by its natural ligand CD86 in the absence of TCR stimulation induces lipid raft polarization in human CD4 T cells.

Stimulation of resting CD4 T cells with anti-CD3/CD28-coated beads leads to rapid polarization of lipid rafts (LRs). It has been postulated that a major role of costimulation is to facilitate LR aggregation. CD86 is up-regulated or expressed aberrantly on immune cells in a wide array of autoimmune and infectious diseases.

Chronic GVH prevents anergy in bone marrow self-reactive B cells: a selective increase in post-endoplasmic reticulum processing and trafficking to the cell surface of autoreactive IgM receptors.

B cell autoreactivity is a component of chronic graft versus host (GVH) disease in humans and mice. Chronic GVH driven by I-A disparity results in loss of B cell tolerance in Ig/sHEL tolerant mice. In these mice, B cell anergy is characterized by down-modulation of sIgM mediated by intracellular retention in the endoplasmic reticulum (ER) and/or a block in post-ER processing of IgM receptors.