R-spondin 1 protects against inflammatory bone damage during murine arthritis by modulating the Wnt pathway.
OBJECTIVE
During the course of different musculoskeletal diseases, joints are progressively damaged by inflammatory, infectious, or mechanical stressors, leading to joint destruction and disability. While effective strategies to inhibit joint inflammation, such as targeted cytokine-blocking therapy, have been developed during the last decade, the molecular mechanisms of joint damage are still poorly understood. This study was undertaken to investigate the role of the Wnt pathway modulator R-Spondin 1 (RSpo1) in protecting bone and cartilage in a mouse model of arthritis.


METHODS
Tumor necrosis factor alpha (TNFalpha)-transgenic mice were treated with vehicle or Rspo1. Mice were evaluated for signs of arthritis, and histologic analysis of the hind paws was performed. Moreover, we determined the effect of Rspo1 on Wnt signaling activity and osteoprotegerin (OPG) expression in murine primary osteoblasts.


RESULTS
The secreted Wnt pathway modulator RSpo1 was highly effective in preserving the structural integrity of joints in a TNFalpha-transgenic mouse model of arthritis by protecting bone and cartilage from inflammation-related damage. RSpo1 antagonized the Wnt inhibitor Dkk-1 and modulated Wnt signaling in mouse mesenchymal cells. In osteoblasts, RSpo1 induced differentiation and expression of OPG, thereby inhibiting osteoclastogenesis in vitro. In vivo, RSpo1 promoted osteoblast differentiation and bone formation while blocking osteoclast development, thereby contributing to the integrity of joints during inflammatory arthritis.


CONCLUSIONS
Our results demonstrate the therapeutic potential of RSpo1 as an anabolic agent for the preservation of joint architecture.
Krönke
Gerhard
G
University of Erlangen-Nuremberg, Erlangen, Germany.
Uderhardt
Stefan
S
Kim
Kyung-Ah
KA
Stock
Michael
M
Scholtysek
Carina
C
Zaiss
Mario M
MM
Surmann-Schmitt
Cordula
C
Luther
Julia
J
Katzenbeisser
Julia
J
David
Jean-Pierre
JP
Abdollahi-Roodsaz
Shahla
S
Tran
Karolyn
K
Bright
Jessica M
JM
Binnerts
Minke E
ME
Akhmetshina
Alfiya
A
Böhm
Christina
C
Distler
Jörg H
JH
Joosten
Leo A B
LA
Schett
Georg
G
Abo
Arie
A
D000818:Animals; D001169:Arthritis, Experimental / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D015153:Blotting, Western; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D002356:Cartilage / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D005455:Fluorescent Antibody Technique; D017403:In Situ Hybridization; D007249:Inflammation / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D019699:Thrombospondins / Q000378:metabolism* / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D051153:Wnt Proteins / Q000378:metabolism*
C518903:RSPO1 protein, mouse; D019699:Thrombospondins; D014409:Tumor Necrosis Factor-alpha; D051153:Wnt Proteins