Skip to main content

Advertisement

We’d like to understand how you use our websites in order to improve them. Register your interest.

Inhibition of tumour necrosis factor alpha production by activated T cells of rheumatoid arthritis patients by novel anti-folate drugs: an ex vivopilot study

Introduction

The folate antagonist methotrexate (MTX) is the 'anchor-drug' in the treatment of patients with rheumatoid arthritis (RA) [1]. The main target of MTX in intracellular folate metabolism is dihydrofolate reductase (DHFR) but several other targets have been described (e.g. thymidylate synthase [TS] and 5-amino-imidazole-4-carboxamide ribonucleotide [AICAR]). At present the exact mechanism of action of MTX in RA still remains elusive [1]. Despite the potent anti-rheumatic capacity of MTX many patients (at least 50%) become resistant to MTX during long-lasting therapy. However, little is known about the mechanisms of resistance against MTX in RA patients [2].

From the field of oncology, where MTX is used against haematological malignancies, new anti-folate drugs were developed to circumvent MTX resistance [3]. These new folate antagonists have the following characteristics: are better transported through the reduced folate carrier, are retained intracellular more efficiently by polyglutamylation via folylpolyglutamate synthetase, and/or have other targets in the folate pathway besides DHFR (e.g. TS).

Objective

To investigate whether two new-generation anti-folate drugs, PT523 (DHFR-inhibitor) and ZD1694 (TS-inhibitor), have equal or better anti-inflammatory capacity compared with MTX based on their capacity to inhibit tumour necrosis factor alpha (TNF-α) production by activated T cells.

Methods

Whole blood from 11 RA patients and six healthy volunteers was incubated ex vivo with MTX, PT523, ZD1694 and, as a control, the DMARD sulphasalazine (SSZ) after T-cell stimulation with α-CD3/CD28. Inhibition of TNF-α production was measured after 72 hours by ELISA [4].

The IC-50 values (defined as the drug concentration exerting 50% inhibition of TNF-α production) are used as a value for the anti-inflammatory capacity of the drug (Table 1).

Table 1 Characteristics of drugs and mean IC-50 values (± standard deviation)

Results

Both PT523 and D1694 turned out to inhibit TNF-α production by activated T cells much more efficiently than MTX (5–15 times). For comparison, the DMARD SSZ is effective at much higher concentration (μM range). The inhibition of TNF-α production by the anti-folate drugs does not seem to be a result of (apoptotic) cell death of T cells whereas SSZ induces apoptosis of T cells (data not shown).

Conclusion

In an ex vivo setting, two novel anti-folate drugs designed to circumvent MTX resistance proved to be very effective in inhibiting TNF-α production by activated T cells from RA patients and healthy volunteers. Future experiments are designed to evaluate ex vivo anti-folate sensitivity profiles for 'MTX-responders' and 'MTX-non-responders' to investigate whether these novel generation of antifolate drugs can be useful in cases of clinical failure on MTX.

References

  1. 1.

    Kremer JM: Toward a better understanding of methotrexate. Arthritis Rheum. 2004, 50: 1370-1382. 10.1002/art.20278.

    CAS  Article  PubMed  Google Scholar 

  2. 2.

    Jansen G, Scheper RJ, Dijkmans BAC: Multidrug resistance proteins in rheumatoid arthritis, role in disease modifying antirheumatic drug efficacy and inflammatory processes: an overview. Scand J Rheumatol. 2003, 32: 325-339. 10.1080/03009740310004333.

    CAS  Article  PubMed  Google Scholar 

  3. 3.

    Rots MG, Pieters R, Peters GJ, van Zantwijk CH, Mauritz R, Noordhuis P, Willey JC, Hahlen K, Creutzig U, Janka-Schaub G, et al: Circumvention of methotrexate resistance in childhood leukemia subtypes by rationally designed antifolates. Blood. 1999, 94: 3121-3128.

    CAS  PubMed  Google Scholar 

  4. 4.

    Gerards AH, de Lathouder S, de Groot ER, Dijkmans BAC, Aarden LA: Inhibition of cytokine production by methotrexaat. Studies in healthy volunteers and patients with rheumatoid arthritis. Rheumatology. 2003, 42: 1189-1196. 10.1093/rheumatology/keg323.

    CAS  Article  PubMed  Google Scholar 

Download references

Acknowledgement

This study is supported by the Dutch Arthritis Association (Grant NRF-03-I-40).

Author information

Affiliations

Authors

Rights and permissions

Reprints and Permissions

About this article

Cite this article

van der Heijden, J., Gerards, A., Oerlemans, R. et al. Inhibition of tumour necrosis factor alpha production by activated T cells of rheumatoid arthritis patients by novel anti-folate drugs: an ex vivopilot study. Arthritis Res Ther 7, P84 (2005). https://doi.org/10.1186/ar1605

Download citation

Keywords

  • Rheumatoid Arthritis Patient
  • Inhibit Tumour Necrosis Factor
  • AICAR
  • Sulphasalazine
  • Reduce Folate Carrier