Unilateral dynamic balance assessment: The test-retest reliability of the OptoJump next drift protocol.

Background: The OptoJump Next Drift Protocol is a test designed to assess unilateral dynamic balance. Participants are required to perform a series of unilateral jumps from which left/right and forward/back displacement (Drift) is calculated.

Objectives: This investigation set out to establish the test-retest reliability of the OptoJump Next Drift Protocol.

Changes in peripheral HCN2 channels during persistent inflammation.

Nociceptor sensitization following nerve injury or inflammation leads to chronic pain. An increase in the nociceptor hyperpolarization-activated current, I, is observed in many models of pathological pain. Pharmacological blockade of I prevents the mechanical and thermal hypersensitivity that occurs during pathological pain.

LFA-1 activates focal adhesion kinases FAK1/PYK2 to generate LAT-GRB2-SKAP1 complexes that terminate T-cell conjugate formation.

Lymphocyte function-associated antigen 1 (LFA-1) affinity and avidity changes have been assumed to mediate adhesion to intercellular adhesion molecule-1 for T-cell conjugation to dendritic cells (DC). Although the T-cell receptor (TCR) and LFA-1 can generate intracellular signals, the immune cell adaptor protein linker for the activation of T cells (LAT) couples the TCR to downstream events. Here, we show that LFA-1 can mediate both adhesion and de-adhesion, dependent on receptor clustering.

T-cell immune adaptor SKAP1 regulates the induction of collagen-induced arthritis in mice.

SKAP1 is an immune cell adaptor that couples the T-cell receptor with the 'inside-out' signalling pathway for LFA-1 mediated adhesion in T-cells. A connection of SKAP1 to the regulation of an autoimmune disorder has not previously been reported. In this study, we show that Skap1-deficient (skap1-/-) mice are highly resistant to the induction of collagen-induced arthritis (CIA), both in terms of incidence or severity.

The chemokine CXCL12 generates costimulatory signals in T cells to enhance phosphorylation and clustering of the adaptor protein SLP-76.

The CXC chemokine CXCL12 mediates the chemoattraction of T cells and enhances the stimulation of T cells through the T cell receptor (TCR). The adaptor SLP-76 [Src homology 2 (SH2) domain-containing leukocyte protein of 76 kD] has two key tyrosine residues, Tyr(113) and Tyr(128), that mediate signaling downstream of the TCR. We investigated the effect of CXCL12 on SLP-76 phosphorylation and the TCR-dependent formation of SLP-76 microclusters.

SKAP1 protein PH domain determines RapL membrane localization and Rap1 protein complex formation for T cell receptor (TCR) activation of LFA-1.

Although essential for T cell function, the identity of the T cell receptor (TCR) "inside-out" pathway for the activation of lymphocyte function-associated antigen 1 (LFA-1) is unclear. SKAP1 (SKAP-55) is the upstream regulator needed for TCR-induced RapL-Rap1 complex formation and LFA-1 activation. In this paper, we show that SKAP1 is needed for RapL binding to membranes in a manner dependent on the PH domain of SKAP1 and the PI3K pathway.

T cell receptor "inside-out" pathway via signaling module SKAP1-RapL regulates T cell motility and interactions in lymph nodes.

Although essential for T cell function, the identity of the T cell receptor "inside-out" pathway for lymphocyte function-associated antigen 1 (LFA-1) adhesion has proved elusive. Here, we define the "inside-out" pathway mediated by N-terminal SKAP1 (SKAP-55) domain binding to the C-terminal SARAH domain of RapL. TcR induced Rap1-RapL complex formation and LFA-1 binding failed to occur in Skap1(-/-) primary T cells.

Adaptor SKAP-55 binds p21 activating exchange factor RasGRP1 and negatively regulates the p21-ERK pathway in T-cells.

While the adaptor SKAP-55 mediates LFA-1 adhesion on T-cells, it is not known whether the adaptor regulates other aspects of signaling. SKAP-55 could potentially act as a node to coordinate the modulation of adhesion with downstream signaling. In this regard, the GTPase p21(ras) and the extracellular signal-regulated kinase (ERK) pathway play central roles in T-cell function.

CTLA-4 disrupts ZAP70 microcluster formation with reduced T cell/APC dwell times and calcium mobilization.

CTLA-4 is a co-receptor that modulates the threshold of T cell activation and autoimmunity. We previously showed that CTLA-4 reverses the TCR-mediated stop signal needed for T cell/APC interactions [Schneider et al., Science 2006, 313: 1972].

OX40 (CD134) blockade inhibits the co-stimulatory cascade and promotes heart allograft survival.

Background: CD134 (OX40) is a member of the tumor necrosis factor receptor superfamily that is expressed as a late event in T-cell activation and contributes to the generation of immunologic memory. CD134 blockade effectively ameliorates inflammation in models of autoimmune disease, but its role in transplantation has been less well studied.

Methods: The authors used an OX40-immunoglobulin (Ig) fusion protein to examine the contribution of this co-stimulatory molecule to the in vitro alloimmune response and studied the ability of CD134 blockade to prevent cardiac allograft rejection in mouse models of heart transplantation using strains representing both major histocompatibility complex (MHC) (BALB/c to CBA/Ca) and minor histocompatibility complex (mHC) (B10.

K3-mediated evasion of CD8(+) T cells aids amplification of a latent gamma-herpesvirus.

The murine gamma-herpesvirus-68 (MHV-68) K3 protein, like that of the Kaposi's sarcoma associated herpesvirus, down-regulates major histocompatibility complex (MHC) class I expression. However, how this contributes to viral replication in vivo is unclear. After intranasal MHV-68 infection, K3 was transcribed both during acute lytic infection in the lung and during latency establishment in lymphoid tissue.

Targeting IL-15 as a therapeutic strategy in organ transplant rejection.

Much effort is currently directed towards generating and evaluating agents that target the individual components of the alloimmune response, with a view to promoting allograft survival accompanied by minimum side effects. Recently, there has been considerable interest in inhibiting individual cytokine/receptor interactions since they are key elements in pathways for differentiation of immune effector cells. This article examines the utility of targeting interactions of interleukin (IL)-15 with its receptor as a strategy for disabling the T-cell activation events following recognition of foreign major and minor histocompatibility antigens.

Selective blockade of IL-15 by soluble IL-15 receptor alpha-chain enhances cardiac allograft survival.

IL-15 is a T cell growth factor that shares many functional similarities with IL-2 and has recently been shown to be present in tissue and organ allografts, leading to speculation that IL-15 may contribute to graft rejection. Here, we report on the in vivo use of an IL-15 antagonist, a soluble fragment of the murine IL-15R alpha-chain, to investigate the contribution of IL-15 to the rejection of fully vascularized cardiac allografts in a mouse experimental model. Administration of soluble fragment of the murine IL-15R alpha-chain (sIL-15Ralpha) to CBA/Ca (H-2k) recipients for 10 days completely prevented rejection of minor histocompatibility complex-mismatched B10.