1. Översiktlig projektbeskrivning

Engelsk titel

Resistin and insulin/insulin-like growth factor signaling in rheumatoid arthritis

Sammanfattning av projektet

We have shown that human resistin has pro-inflammatory properties activating NFkB pathway. Its murine counterpart regulates glucose metabolism being associated with insulin resistance. The aim: to examine a possible cross-talk between resistin and insulin/insulin growth factor (IGF) signaling in rheumatoid arthritis (RA).
Methodological approaches: 1) Insulin/IGF-1 pathway will be characterized in blood and synovial fluid of RA patients and analysed in relation to resistin levels; 2) Insulin/IGF-1 signaling will be evaluated in human synovial tissues transplanted to SCID mice through abrogation of resistin expression in vivo using siRNA technique; 3) Resistin-induced effects on RA synovial fibroblasts will be studied in vitro with respect to IGF-1 receptor signaling.
Our preliminary results show that resistin and IGF-1R are differently expressed in RA synovia. Levels of IGF-1 are significantly reduced in synovial fluid of RA patients being inversely related to resistin and most pronounced in combination with systemic inflammation. Abrogation of resistin expression in vivo using siRNA reduced cellularity of implanted RA synovia and phosphorylation of Akt, which was followed by modulation of GSK-3b, PTPN and PTEN. In MRC-5 fibroblasts, resistin induced expression of IRS-1 and iNOS.
Significance: Invasive growth of inflamed synovia is considered a major reason of progressive joint destruction in rheumatoid arthritis. This project is aimed to explore the role of resistin as a potential link between inflammatory and growth-factor dependent pathways, and to evaluate it as a new potential therapeutic option in rheumatiod arthritis.

Typ av projekt

Forskningsprojekt

MeSH-termer för att beskriva ämnesområdet

Inlagda MeSH-termer

Arthritis

Resistin

A 12-kDa cysteine-rich polypeptide hormone secreted by FAT CELLS in the ADIPOSE TISSUE. It is the founding member of the resistin-like molecule (RELM) hormone family. Resistin suppresses the ability of INSULIN to stimulate cellular GLUCOSE uptake.

Projektets delaktighet i utbildning

Avhandling
D-uppsats / Magisterexamen
C-uppsats / Kandidatexamen
ST-läkarutbildning
Annan utbildning
Ej del i utbildning

3. Processen och projektets redovisning

Pågående aktiviteter

Planering och förberedelse före datainsamling
Datainsamling pågår
Analys av insamlade data pågår
Författande av skriftlig redovisning / publikation pågår
En eller flera publikationer från projektet är publicerade
Slutfört och inget mer görs inom ramen för detta projekt

Projektstart (när planeringen påbörjas och börjar dokumenteras skriftligt)

2009-01-01

Datum för påbörjande av datainsamling

2009-07-15

Publikationer från detta projekt

1. Resistin is stored in neutrophil granules being released upon challenge with inflammatory stimuli.

   Boström Elisabeth A, Tarkowski Andrej, Bokarewa Maria.

   Biochim Biophys Acta 2009:1793(12):1894-900.

   [Links: PMID: 19770005 | DOI länk][Source: PubMed®]
2. Resistin competes with lipopolysaccharide for binding to Toll-like receptor 4.

   Tarkowski Andrej, Bjersing Jan, Shestakov Andrey, Bokarewa Maria I.

   J Cell Mol Med. 2009

   [Links: PMID: 19754671 | DOI länk][Source: PubMed®]

Tillämpning av resultat - tidsaspekt (projektledarens bedömning)

Resultaten kommer sannolikt att tillämpas inom 5 år från projektslut.

Tillämpning av resultat - genomslag (projektledarens bedömning)

Internationellt (i flera länder)

Tillämpning av resultat - beskrivning

Boström EA, Svensson M, Andersson S, Ekwall-Hultgård AK, Eisler T, Dahlberg LE, Smith U, Bokarewa MI. 2011. Resistin and insulin/insulin-like growth factor signaling in rheumatoid arthritis. Arthritis&Rheum 63:2894-904.

Boström EA, Ekstedt M, Kechagias S, Sjöwall C, Bokarewa MI, Almer S. 2011. Resistin is elevated in autoimmune diseases of the gastrointestinal tract reflecting ANA positivity. Scand J Immunol 74:463-70.

4. Detaljerad projektbeskrivning

Bakgrundsbeskrivning

Rheumatoid arthritis (RA) is an inflammatory joint disease morphologically characterized by leukocyte infiltration of synovial tissues followed by hyperplasia and pannus formation invasively growing into cartilage and subchondral bone. Growth factors supporting hyperplasia of invasively growing synovia are active participants in the pathogenesis of RA, which makes them potential targets for anti-rheumatic treatment1,2.

Insulin and insulin growth factors (IGFs) are polypeptide hormones with high sequence similarity. Insulin has extensive metabolic and mitogenic effects regulating utilization of carbohydrates while IGF-1 is an important growth factor involved in cell growth, differentiation and cell survival being one of the most potent activators of Akt phosphorylation2. Insulin and IGF-1 have synergistic effects mediated through hybrid receptors formed by post-translational assembly of IR isoforms and IGF-1R. Expression of IGFs in RA synovium is previously reported3 and shown to contribute to the proliferation of fibroblasts and possibly in repair mechanisms following joint injury.

Resistin, a 12,5 kDa peptide has been originally described as a modulator of insulin sensitivity in rodents4, while such role in humans is still under debate5. We have recently shown elevated resistin levels in RA serving pro-inflammatory properties by activating NF-kB dependant cytokine cascade6,7,8. Due to the observed functional differences between human resistin and its murine counterpart, no good experimental mouse model of arthritis has been available for in vivo studies. In this project we develop transplantation model of human synovial tissue engrafted onto mice with severe combined immunodeficiency (SCID)9 giving the possibility to modulate the tissue by direct interaction.

Syfte

1)To characterize insulin/IGF-1 signaling pathway in relation to resistin in blood and synovial fluid of RA patients.
2)To evaluate the changes in insulin/IGF-1 signaling through abrogation of resistin expression in human synovial tissues transplanted to SCID mice.
3)To study resistin-induced effects on rheumatoid synovial fibroblasts with respect to IGF-1 receptor signaling.
4)To study the effect of selective IGF-1R inhibition of the development of arthritis in mice experimental models.

Resultat

1.Reduction of IGF signaling in RA synovia. Levels of IGF-1, IGFBP3 and resistin were measured in paired samples of blood and synovial fluid obtained from patients with RA (n=60) as well as in synovial fluids of patients with osteoarthritis (OA, n=19). Synovial levels of IGF-1 were significantly lower in RA patients (ng/ml, 2.0±6.36) compared to OA (ng/ml, 12.3±5.14, p=0.0001). Most pronounced decrease of IGF-1 was observed in blood and synovial fluid of RA patients with systemic inflammation (CRP>30 mg/L, mean 60±46, Figure 1).
2)Abrogation of resistin expression in human synovia led to inhibition of Akt activity. Human synovia of RA patients was transplanted to the back of SCID mice lacking T and B lymphocytes. Resistin expression was suppressed by injections of resistin-targeting siRNA. Significant inhibition of resistin expression was achieved with siRNA compared to non-targeting (mock) RNA (Figure 2). Simultaneously, siRNA treated synovia had decreased levels of functionally active (phosphorylated) Akt.
3) Effect of resistin on the expression and phosphorylation of IGF-1R as well as IR was studied using human fibroblast cell line MRC-5. Preliminary results show that resistin induces phosphorylation of IGF-1R and expression of adaptor molecule IRS-1, and phosphorylation of Akt. Activation of iNOS is noted among distant effects of resistin stimulation of MRC-5.

Slutsats

Invasive growth of inflamed synovia is considered a major reason of progressive joint destruction in rheumatoid arthritis. Our findings indicate that resistin has a regulatory role linking inflammatory and growth factor-dependent pathways. Thus, targeting resistin opens a new potential therapeutic option in rheumatiod arthritis.