Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Fluorescence Imaging of Articular Proteinase Activities and Osteoblast Activity Showed Treatment Response to Anti-Interleukin-1 Antibodies in a Mouse Model of Collagen-Induced Arthritis.

A. J. van de Loo,  Fons, Vermeij,  Eline, J. Arntz,  Onno, Koenders,  Marije, van den Berg,  Wim B.

Objective:

To monitor the response of anti-IL-1ab antibody treatment on collagen-induced arthritis (CIA) using cathepsin- and matrix metalloproteinase (MMP) cleavable near-infrared probes, and a probe of osteoblast activation.

Methods:

CIA was induced in male DBA1/J mice by immunization with bovine collagen-type II. Mice received either anti-IL-1ab sera (200 ml i.v.) or normal rabbit serum as a control at day 21. Ten days later, probes were injected i.v. and 6 hours later mice were imaged using the IVIS Lumina (Caliper Life Sciences). Thereafter, ankle and knee joints were dissected and processed for RNA, histology or X-ray. The ProSense 680 probe (VisEn Medical Inc, Bedford, USA) becomes activated upon enzymatic cleavage by cathepsins (B, K, L, S, D), collagen degrading lysosomal cysteine proteinases. The MMPSense 680, can be activated by different MMPs (2,3,9,13), known to degrade collagen and proteoglycans during arthritis. OsteoSense 680 is a fluorescent biphosphonate that binds to hydroxyapetite, a biomarker for osteoblast activation. Gene expression profiling was done of synovial biopsies from (non)-inflamed knees of untreated mice (MOE430_2 oligonucleotide array, Affymetrix, CA). Ankle joints were X-ray photographed and analyzed using a stereo microscope and scored on a scale ranging from no damage (0) to complete bone destruction (5).

Results:

Inflamed synovia of CIA showed enhanced expression of the extracellular matrix degrading enzymes cathepsin-K (13-fold, osteoclasts specific gene), cathepsin-S (9-fold, specific for monocytes), MMP-13 (50-fold), MMP-3 (22-fold), MMP-14 (9-fold), MMP9 and MMP-2 (4-fold). Genes related to bone destruction as cathepsin K (13-fold), TGFb1 (5-fold), TRAP5 (9-fold) and RANKL (10-fold) were upregulated as were also the osteoblast specific enzymes osteocalcin (10-fold) and periostin (7-fold). The signal of ProSense and MMPSense in both knees and paws correlated with joint inflammation and cartilage destruction, but only the MMPSense and not the ProSense correlated with chondrocyte death, a marker of irreversible cartilage destruction. Anti-IL-1ab antibody treatment alleviated CIA and markedly diminished the ProSense and MMPSense imaging signal. OsteoSense signal was increased during inflammation and was higher in mice showing mild bone loss as measured by X-ray and was significantly lower in the anti-IL-1 treated mice.

Conclusion:

The correlation of both ProSense and MMPSense to inflammation and destruction is in line with the upregulation of Cathepsins and MMP's during CIA, and the connective tissue destructive properties of these enzymes. Interestingly, only the MMPSense signal correlated with chondrocyte death and we speculate that MMPs are directly involved as both MMP9 and 13 have galectin-3 as a substrate, an anti-apoptotic protein in chondrocytes. The OsteoSense signal in CIA showed that new bone formation by osteoblasts occurred under mild bone loss conditions. Imaging of these three probes is a sensitive method to measure joint inflammation, connective tissue destruction and repair, and overall is fluorescence imaging a valuable tool to monitor a treatment response.

To cite this abstract, please use the following information:
A. J. van de Loo, Fons, Vermeij, Eline, J. Arntz, Onno, Koenders, Marije, van den Berg, Wim B.; Fluorescence Imaging of Articular Proteinase Activities and Osteoblast Activity Showed Treatment Response to Anti-Interleukin-1 Antibodies in a Mouse Model of Collagen-Induced Arthritis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1622
DOI: 10.1002/art.29388

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