Inhibition Of Spermidine/Spermine N1-Acetyltransferase Activity – a New Therapeutical Concept In Rheumatoid Arthritis

Emmanuel Karouzakis¹, Astrid Jungel¹, Beat A. Michel², Renate E. Gay³, Steffen Gay¹ and Michel Neidhart⁴, ¹Center of Experimental Rheumatology, University Hospital Zurich and Zurich Center of Integrative Human Physiology (ZIHP), Zurich, Switzerland, ²Department of Rheumatology, University Hospital Zurich, Zurich, Switzerland, ³Center of Experimental Rheumatology, Zurich University Hospital, Zurich, Switzerland, ⁴Center of Experimental Rheumatology, University Hospital Zurich, Zurich, Switzerland

Meeting: 2013 ACR/ARHP Annual Meeting

Keywords: Epigenetics, rheumatoid arthritis, synovial fluid, synovium and synovial cells

Session Information

Title: Rheumatoid Arthritis Treatment - Small Molecules, Biologics and Gene Therapy II

Session Type: Abstract Submissions (ACR)

Background/Purpose:

Spermine/spermidine N1-acetyltransferase (SSAT1) and polyamine modulating factor 1 (PMF1) are increased in rheumatoid arthritis synovial fibroblasts (RASF). Since PMF1 regulates the expression of SSAT1, we hypothesized that changes in PMF1 promoter DNA methylation favor the expression of SSAT1 that causes an excessive consumption of S-adenosylmethionine (SAM) in RASF. The second objective was to decrease the activity of SSAT1 and to evaluate the effect of this treatment – alone or in combination with a supplement of SAM on DNA methylation and behavior of RASF.

Methods:

Synovial fibroblasts were isolated from patients with RA or osteoarthritis (OA). Promoter methylation of PMF1 was determined by pyrosequencing. The fibroblasts were treated for 2 weeks with 40 mM diminazene aceturate (DA), an inhibitor of SSAT1. DNA 5-methylcytosine content, SSAT1, adenosylmethionine decarboxylase (AMD), PMF1, DNA methyltransferase 1 (DNMT-1), CXCL12, integrin b1 and CD44 were measured by flow cytometry. Cell adhesion to fibronectin was tested. Levels of matrix metalloproteinases (MMP-1 and -3) were measured in cell culture supernatant. The SCID-mouse model of RA allowed monitoring the invasiveness of RASF.

Results:

Compared with OASF (n = 6), RASF (n= 12) expressed more SSAT1, AMD and PMF1: 240+57%, 169+38% and 196+20%. However, PMF1 promoter methylation was unchanged. DA, like siRNA against SSAT1, decreased the expression of AMD in RASF (by 33±5%; p<0.001). DA increased the DNA 5-methylcytosine content (by 150±12%; p<0.05), increased the expression of DNMT-1 (303±70%; p<0.001), decreased the expression of activation markers (CXCL12: 42±7%; Integrin β1: 29±2%, p<0.001) and MMP1 (9±2%, p<0.05) and altered the adhesion of RASF to fibronectin (Control: 100±17, DA: 72±13%; p<0.001). DA was more efficient in RASF with higher levels of SSAT1. The combination of DA plus SAM increased most efficiently DNMT-1 (523±110%; p<0.001), than DA or SAM alone. In addition, it further decreased CXCL12 and integrin b1 expression, as well as MMP-1 levels (by 48±5%, 58±5% and 24±6%; p<0.001), but not of MMP-3. Most interestingly, the combination DA and SAM reduced the invasiveness of RASF in the SCID mouse model of RA by 70%.

Conclusion:

The use of DA alone or in combination with SAM / L-methionine might introduce a new therapeutic concept in RA.

Disclosure:

E. Karouzakis,

Novartis foundation, IMI-BTCure,IAR,EURO-TEAM,

A. Jungel,

IMI-BTCure,IAR,

B. A. Michel,
None;

R. E. Gay,

EURO-TEAM, IMI BTCure, IAR Epalinges,

S. Gay,

EURO-TEAM, IMI BTCure, IAR Epalinges,

M. Neidhart,

Novartis foundation, IMI-BTCure, EURO-TEAM, IAR,

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