Academisch Medisch Centrum Universiteit van Amsterdam

Groupmembers

Kris Reedquist, PhD – Group Leader
Joana Abreu, PhD student
Alek Grabiek, PhD student
Daphne de Launay, PhD student
Jeroen Ludikhuize, PhD student
Dion Groot, technician
Marjolein Sanders, technician

Research

Research in our group focuses on the identification of key intracellular signalling pathways which mediate the switch from acute to chronic inflammation, and perpetuate established inflammation, in complex autoimmune diseases such as rheumatoid arthritis (RA). These studies provide a fundamental understanding of the pathophysiological mechanisms of chronic inflammation, identify new targets in the treatment of RA and other autoimmune diseases, and apply a translational pre-clinical and clinical approaches to understanding the efficacy (or lack of efficacy) of novel and established therapeutic compounds in RA.

Much of our work is centered around the regulation and function of Ras superfamily small GTPase signalling pathways in immune and stromal cells in the RA synovium. Specific research questions that we are currently exploring include:

-       How does the small GTPase Rap1 regulate qualitative T cell immune responses?
-       What are the molecular mechanisms underlying the acquisition of the semi-transformed invasive phenotype of stromal cells in the synovium of arthritis patients?
-       How are proliferative and survival signals integrated with inflammatory signals in the RA synovium to perpetuate cellular hyperplasia and promote joint destruction?
-       Research theme: understanding how coordinated activation of Ras superfamily GTPases and their downstream intracellular signaling targets regulates acute and chronic immune responses.

Goal of our research is the translation of our findings into novel therapeutic strategies for manipulating immune responses in chronic inflammatory diseases (such as rheumatoid arthritis - RA), cancer, and transplantation medicine.

Research Line 1:  Regulation of qualitative T cell responses by Rap1.  We have identified three distinct signaling pathways in T cells regulated by the Ras-related GTPase Rap1: regulation of integrin activation, reactive oxygen species (ROS) production, and cytokine secretion.  In RA synovial tissue, chronic inactivation of Rap1 is responsible for oxidative stress in T cells, thought to contribute to pathological T cell behavior in RA.  CTLA4-Ig therapy in RA is associated with restoration of Rap1 function and alleviation of T cell oxidative stress.  Ongoing work is detmining the contribution of distinct Rap1 signaling pathways to T cell function in RA (and normal) T cells.  Through LNA knockdown of differentially expressed Rap1 regulatory proteins, identification of extracellular (CD28 and TNF/TNFR family) signaling proteins in distinct T cell compartments, and analysis of genetically modified mice, we are manipulating Rap1 function to modify qualitative T cell responses in animal models of arthritis, influenza, and melanoma, and material derived from RA and melanoma patients.

Research Line 2:  Ras signaling pathways in RA synovial tissue.  Because Ras GTPases play a pivotal role in cellular activation, proliferation, and survival, and because stromal fibroblast-like synoviocytes (FLS) display many properties consistent with (Ras-) transformed cells, we are assessing the potential contributions of Ras signaling pathways to inflammation and joint destruction in RA.  We have found that a specific activator of H-Ras, RasGRF1, is overexpressed in RA, and may contribute to enhanced production of joint-destroying matrix metalloproteinases.  Ongoing efforts will identify the distinct contributions of Ras homologs in murine models of arthritis, using knockout mice and pharmacological LNA silencing of Ras homolog expression.

Research Line 3: We have found that the PI3-kinase/PKB/FoxO transcription factor pathway, a selective target of H-Ras, is selectively activated in RA compared to inflammatory osteoarthritis.  This pathway contributes to inflammatory NF-kappaB activation and joint erosion in RA, and in vitro, contributes to macrophage and FLS survival.  We are currently determining how PI3-kinase pathways functionally interact with pro-inflammatory signaling pathways to regulate cellular activation and survival in chronic inflammatory diseases.

Publications

-       Vergunst CE, Gerlag DM, Dinant H Schulz L, Vinkenoog M, Smeets TJM, Sanders ME, Reedquist KA, and Tak PP (2007). Evidence that blocking the receptor for C5a in patients with rheumatoid arthritis does not result in clinical improvement of the disease. Results of a double-blind, placebo-controlled clinical trial with an orally administered C5a-receptor antagonist. Rheumatology (Oxford) (in press).
-       Ludikhuize J, de Launay D, Groot D, Smeets TJM, Vinkenoog M, Tas SW, Tak PP, and Reedquist KA (2007). Inhibition of FoxO family transcription factors in rheumatoid arthritis synovial tissue. Arthritis Rheum. 56:2180-2191.
-       Reedquist KA, Ludkihuize J, and Tak PP (2006). Phosphoinositide 3-kinase signaling and FoxO transcription factors in rheumatoid arthritis. Biochem. Soc. Trans. 34:727-730.
-       Remans PHJ, Wijbrandts CA, Sanders ME, Toes RE, Breeveld FC, Tak PP, van Laar JM, and Reedquist KA (2006). CTLA4Ig suppresses rheumatoid arthritis T cell reactive oxygen species production by preventing inactivation of Rap1: inflammatory cytokines and synovial adherent cells synergistically induce oxidative stress in rheumatoid arthritis T cells through modulation of Ras family GTPase activity. Arthritis Rheum. 54:3135-3147.
-       Remans PH, van Oosterhout M, Smeets TJ, Sanders M, Frederiks WM, Reedquist KA, Tak PP, Breedveld FC, and van Laar JM (2005). Intracellular free radical production in T lymphocytes from patients with rheumatoid arthritis. Arthritis Rheum. 52:2003-2009.
-       Tas SW, Remans PH, Reedquist KA, and PP Tak (2005). Signal transduction pathways and transcription factors as therapeutic targets in chronic inflammatory disease: towards innovative antirheumatic therapy. Curr. Pharm. Des. 11:581-611.
-       Arens R, Nolte MA, Tesselaar K, Heemskerk B, Reedquist KA, van Lier RA, and MH van Oers (2004). Signaling through CD70 regulates B cell activation and IgG production. J. Immunol. 173:3901-3908.
-       Remans PHJ, Gringhuis SI, van Laar JM, Sander ME, Papendrecht-van der Voort EAM, Zwartkruis FJT, Nivine-Levarht EW, Rosas M, Coffer PJ, Breedveld FC, Bos JL, Tak PP, Verweij CL, and KA Reedquist (2004). Rap1 signaling is required for suppression of Ras-generated reactive oxygen species and protection against oxidative stress in human T lymphocytes. J. Immunol. 173:920-931.
-       van Holten J, Reedquist K, Sattonet-Roche P, Smeets TJM, Plater-Zyberk C, Vervoordeldonk MJ, and PP Tak (2004). Treatment with recombinant interferon-beta reduces inflammation and slows cartilage destruction in the collagen-induced arthritis model of rheumatoid arthritis. Arthritis Res. Ther. 6:R239-249.
-       de Bruyn, KMT, Rangarajan S, Reedquist KA, Figdor CG, and JL Bos (2002). The small GTPase Rap1 is required for Mn2+- and antibody-induced LFA-1- and VLA-4-mediated cell adhesion. J. Biol. Chem. 277:29468-29476.
-       Bos JL, de Rooij J, and KA Reedquist (2001). Rap1 signalling: adhering to new models. Nat. Rev. Mol. Cell. Biol. 2:369-377.
-       Amsen D, Kruisbeek A, Bos JL, and K Reedquist (2000). Activation of the Ras-related GTPase Rap1 by thymocyte T cell receptor engagement and during selection. Eur. J. Immunol. 30:2832-2841.
-       Lu L, Anneren C, Reedquist KA, Bos JL, and M Welsh (2000). NGF-dependent neurite outgrowth in PC12 cells overexpressing the Src homology 2-domain protein SHB requires activation of the Rap1 pathway. Exp. Cancer Res. 259:370-377.
-       Anneren C, Reedquist KA, Bos JL, and M Welsh (2000). Gtk, a Src-related tyrosin kinase, induces NGF-independent outgrowth in PC12 cells through activation of the Rap1 pathway: a relationship to SHB tyrosine phosphorylation and elevated levels of focal adhesion kinase. J. Biol. Chem. 275:29153-29161.
-       Reedquist KA, Ros E, Koop EA, Wolthuis RM, Zwartkruis FJ, van Kooyk Y, Salmon M, Buckley CD, and JL Bos (2000). The small GTPase, Rap1, mediates CD31-induced integrin adhesion. J. Cell Biol. 148:1151-1158.

Grants financing the research

The work of our group is funded by the Dutch Arthritis Association.