Regulatory T cells control the transition from acute into chronic inflammation in glucose-6-phosphate isomerase-induced arthritis

• Published in: Annals of the rheumatic diseases Vol. 69; no. 8; p. 1511
• Main Authors: Frey, Oliver, Reichel, Andreas, Bonhagen, Kerstin, Morawietz, Lars, Rauchhaus, Una, Kamradt, Thomas
• Format: Journal Article
• Language: English
• Published: England 01-08-2010
• Subjects: Acute Disease; Animals; Arthritis, Experimental - chemically induced; Arthritis, Experimental - immunology; Arthritis, Experimental - pathology; CD4-Positive T-Lymphocytes - immunology; Chronic Disease; Disease Progression; Glucose-6-Phosphate Isomerase - immunology; Immunization; Immunoglobulin G - biosynthesis; Interleukin-2 Receptor alpha Subunit - immunology; Mice; Mice, Inbred DBA; T-Lymphocytes, Regulatory - immunology
• ISSN: 1468-2060
• DOI: 10.1136/ard.2009.123422

Glucose-6-phosphate isomerase (G6PI)-induced arthritis is a spontaneously remitting experimental arthritis model. It was hypothesised that regulatory T cells (Tregs) are involved in remission and their role in G6PI-induced arthritis was investigated.
Tregs were depleted by injection of anti-CD25 before immunisation of DBA/1 mice with G6PI. The severity of arthritis was assessed clinically and histologically and the number and function of G6PI-specific T helper (Th) cells were determined by flow cytometry. Th cells and monocytes/macrophages were depleted using anti-CD4 or clodronate-containing liposomes.
Injection of anti-CD25 depleted Tregs transiently. Normal numbers of Tregs were restored 5 weeks after G6PI immunisation. Whereas arthritis started to resolve in control mice 3 weeks after immunisation with G6PI, severe arthritis was still present in the anti-CD25-treated mice 12 weeks after immunisation. The most striking ex vivo correlate of non-remitting arthritis was a strong increase in G6PI-specific Th cells 3 days after G6PI immunisation. This difference between treated and control mice declined at later time points. Depletion of CD4 cells ameliorated arthritis in controls but not in anti-CD25-treated mice. In contrast, clodronate-containing liposomes were an effective treatment in both groups.
Tregs control the transition from acute self-limiting to non-remitting destructive G6PI-induced arthritis already in the preclinical disease stage. Once established, non-remitting destructive arthritis is not controlled by restoration of normal Treg numbers. These findings question the rationale of therapeutic approaches augmenting Treg number or function in established arthritis.