Project

Back to overview

Role of calcium signaling during inflammation and joint destruction in arthritis.

Applicant Waldburger Jean-Marc
Number 122477
Funding scheme Project funding
Research institution Département de Pathologie et Immunologie Faculté de Médecine / CMU Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Immunology, Immunopathology
Start/End 01.12.2008 - 30.11.2013
Approved amount 288'000.00
Show all

Keywords (10)

inflammation; arthritis; signaling pathways; calcium dependent kinases; calcium channels; rheumatoid arthritis; calcium signaling; kinases; cytokines; inflammation.

Lay Summary (French)

Lead
Lay summary
La polyarthrite rhumatoïde est une des maladies autoimmunes les plus fréquentes, touchant environ un pourcent de la population. Cette pathologie provoque une inflammation symétrique des articulations, qui peut évoluer vers une destruction du cartilage et une perte de la fonction articulaire en l'absence de traitement. Dans la polyarthrite, le système immunitaire active de façon aberrante des lymphocytes T et B, qui par le biais de cytokines inflammatoires, d'autoanticorps circulants et de molécules de contact vont engendrer une inflammation locale. Ces agents extracellulaires relaient l'information vers l'intérieur des cellules par des signaux de transduction, qui vont à leur tour activer davantage de gènes inflammatoires et notamment stimuler la sécrétion d'enzymes qui dégradent le cartilage et l'os dans un cercle vicieux. Une partie de ces mécanismes de signalisation sont dépendants de l'élévation de messagers intracellulaires et notamment des ions calciques. Le but de ce projet est d'étudier quels sont les mécanismes dépendant des signaux calciques dans l'inflammation articulaire. L'identification des enzymes et des molécules impliquées pourraient permettre de tester de nouveaux moyens d'inhiber l'inflammation dans la polyarthrite.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
STIM1 juxtaposes ER to phagosomes, generating Ca²⁺ hotspots that boost phagocytosis.
Nunes Paula, Cornut Daniela, Bochet Vanessa, Hasler Udo, Oh-Hora Masatsugu, Waldburger Jean-Marc, Demaurex Nicolas (2012), STIM1 juxtaposes ER to phagosomes, generating Ca²⁺ hotspots that boost phagocytosis., in Current biology : CB, 22(21), 1990-7.

Abstract

BackgroundIn rheumatoid arthritis (RA) an inflammatory response affects primarily the joints, leading to pain, articular destruction and invalidity. Complete disease remission can be difficult to achieve, resulting in irreversible joint damage. Intracellular signaling pathways contribute to RA pathogenesis and represent potential therapeutic targets. Bone resorption by osteoclasts requires the calcium dependent kinase CamKIV. TNF and IL-6 secretion after IgE engagement of mast cells requires calcium flux. Cytokines such as TNF and IL-1 induces calcium flux in fibroblasts-like synoviocytes (FLS) and chondrocytes. Our preliminary data suggest that unexpectedly, signaling pathways dependent on extracellular calcium contribute to the production of the inflammatory cytokine IL-6 and the metalloproteinase MMP-3 by synoviocytes in vitro. Collectively, these observations suggest that calcium dependent pathways contribute to inflammation and bone destruction in arthritis.Working hypothesisWe hypothesize that calcium dependent signaling pathways are required for the production of cytokines and proteinases involved in arthritis. We expect that if we can discover signaling pathway common to independent cell lineages such as FLS and mast cells, then blocking these mechanisms will be effective in vivo in arthritis models. Activation of mast cell in the synovium is thought to be a triggering event in response to toll-like receptor engagement, cytokine responses such as IL-1 or IL-33, or immune complexes. FLS are important mediators of joint destruction and amplify local inflammation by secreting proteinases, cytokines and chemokines. We will study if the calcium dependent molecules that are important in the production of IL-6 and MMP-3 in FLS also regulate the release IL-6 and TNF in mast cells. The relevance of the findings in these two cell types known to be involved in arthritis will be examined in vivo.Specific aims1. Determine the expression and relative contribution of the calcineurin phosphatase, protein kinase C and calmodulin kinase pathways in FLS and mast cells. We will examine the expression of the different isoforms of these enzymes. Using selective inhibitors and siRNA knockdown approaches we will define their role in metalloproteinase production (FLS) and cytokine expression (FLS and mast cells). The role of key transcription factors will be examined.2. Determine the contribution of cytoplasmic calcium influx during inflammation. We will use chemical inhibitors to block specific calcium channels and examine their effect on cytokine and MMPs production in stimulated FLS and mast cells. We will check if FLS and mast cells express the corresponding channels and confirm their function by genetic inactivation.3. Determine the role of calcium signaling pathways during arthritis in vivo. The relative expression of calcium dependent kinases and their activated phospho-forms will be determined during a time course of experimental arthritis. Therapeutic intervention in animal models will test if calcium dependent pathways can suppress inflammation and joint destruction during arthritis.Experimental designIn vitro studies will be performed using primary cultures of FLS and mast cells. mRNA studies will be performed by quantitative PCR, cytokines levels will be measured by ELISA and intracellular proteins by Western blot. Functional studies will be perfomed using inhibitors, siRNA mediated knockdown and knockout cells. The role of transcription factors will be examined by reporter assays and electromobility shift assays. In vivo studies will be performed in the antigen-induced arthritis model.Expected value of the proposed projectBy studying which calcium dependent pathways contribute to inflammation in two different cell types, we expect to discover important common mediators of arthritis. This could lead to novel therapeutic approaches. The hypotheses generated by this project will require follow up studies to examine the presence and the role of these pathways in human articular diseases.
-