Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


In Vivo Profiling of the Disease-Inducible Promoters Serum Amyloid A3 and S100 Calcium Binding Protein A8 for Personalized Gene Therapy in Arthritis.

Vermeij,  Eline A., Arntz,  Onno J., van Lent,  Peter L.E.M., van den Berg,  Wim B., van de Loo,  Fons A.J.

Background/Purpose:

Local intra-articular gene therapy for arthritis, with the use of disease-inducible promoters, represents a promising alternative for coping with side effects of the conventional treatments. These disease-inducible promoters react to transcription factors that are released during inflammation and therefore only produce a reporter (luciferase) or therapeutic protein when necessary. Previously, we developed lentiviral based disease-inducible promoter reporters with a computational approach by selecting suitable promoters from endogenous genes differentially regulated in inflamed synovium of collagen-induced arthritis mice (Geurts et al., 2009). Two of those promoters are the Saa3 and S100a8. Saa3 stands for Serum Amyloid A3, which is an acute phase protein released during inflammation. S100a8 is a member of the alarmins, which induces signaling cascades and triggers the immune system. We have elucidated the kinetics of these two promoters in an acute arthritis model to validate the use of these promoters in gene therapy.

Methods:

The kinetics of the two promoter reporter constructs were evaluated in-vivo by bioluminescent imaging in the streptococcal cell wall (SCW)–induced arthritis model. An acute joint inflammation was induced 4 days after lentivirus injection by intra-articular injection of S. pyogenes. At pre-defined time points after SCW injection, mice were injected with luciferin. The luciferin is converted into visible light by the luciferase that is produced under control of one of the promoters. Using a sensitive CCD camera (IVIS Lumina, Caliper Life Sciences, USA) the visible light was detected and luciferase activity was quantified. Neutrophil elastase activity (neutrophil influx) and cathepsin activity (macrophage activity) at day 1 and 4 after SCW injection was measured in vivo by using an activatable fluorescent probe (PerkinElmer Inc., USA). Histological sections of the knee joints were made and scored for cell influx and synovitis. qPCR was performed on synovial tissue to measure endogenous gene expression of the Saa3 and S100a8 genes.

Results:

The Saa3 promoter was strongly upregulated (120 fold) at day one of SCW arthritis, and subsided afterwards, following the course of neutrophil exudation as shown by both histology and fluorescent in vivo imaging (neutrophil elastase activity was 5 times higher at day 1 compared to day 4). The endogenous synovial Saa3 gene expression showed the same profile. The S100a8 promoter peaked (20 fold) at day 4 of SCW arthritis, following the course of synovitis (inflammation of the synovium) and cathepsin activity. However, the S100a8 promoter activity did not follow the endogenous S100a8 gene expression, which also peaked at day 1 probably due to the infiltration of S100a8 expressing neutrophils, which are not targeted by the lentivirus.

Conclusion:

This study showed that the Saa3 promoter is a suitable promoter for gene therapy targeting the acute joint inflammatory process, whereas the S100a8 promoter is a good candidate for gene therapy in immunologically mediated joint inflammation where macrophages play a more dominant role.

To cite this abstract, please use the following information:
Vermeij, Eline A., Arntz, Onno J., van Lent, Peter L.E.M., van den Berg, Wim B., van de Loo, Fons A.J.; In Vivo Profiling of the Disease-Inducible Promoters Serum Amyloid A3 and S100 Calcium Binding Protein A8 for Personalized Gene Therapy in Arthritis. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :205
DOI:

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