Levels and function of regulatory T cells in patients with polymorphic light eruption: relation to photohardening
Summary Background We hypothesized that regulatory T cells (Tregs) are involved in the immunological abnormalities seen in patients with polymorphic light eruption (PLE). Objectives To investigate the number and suppressive function of peripheral Tregs in patients with PLE compared with healthy cont...
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Published in | British journal of dermatology (1951) Vol. 173; no. 2; pp. 519 - 526 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
England
Blackwell Publishing Ltd
01.08.2015
Oxford University Press John Wiley and Sons Inc |
Subjects | |
Online Access | Get full text |
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Summary: | Summary
Background
We hypothesized that regulatory T cells (Tregs) are involved in the immunological abnormalities seen in patients with polymorphic light eruption (PLE).
Objectives
To investigate the number and suppressive function of peripheral Tregs in patients with PLE compared with healthy controls.
Methods
Blood sampling was done in 30 patients with PLE [seeking or not seeking 311‐nm ultraviolet (UV)B photohardening] as well as 19 healthy controls at two time points: TP1, March to June (before phototherapy); and TP2, May to August (after phototherapy). We compared the number of CD4+CD25highCD127−FoxP3+ Tregs by flow cytometry and their function by assessing FoxP3 mRNA levels and effector T cell/Treg suppression assays.
Results
Tregs isolated from healthy controls significantly suppressed the proliferation of effector T cells at TP1 by 68% (P = 0·0156). In contrast, Tregs from patients with PLE entirely lacked the capacity to suppress effector T‐cell proliferation at that time point. The medical photohardening seen in 23 patients with PLE resulted in a significant increase in the median percentage of circulating Tregs [both as a proportion of all lymphocytes; 65 6% increase (P = 0·0049), and as a proportion of CD4+ T cells; 32.5% increase (P = 0·0049)]. This was accompanied by an increase in the expression of FoxP3 mRNA (P = 0·0083) and relative immunosuppressive function of Tregs (P = 0·083) comparing the two time points in representative subsets of patients with healthy controls tested. Seven patients with PLE not receiving 311‐nm UVB also exhibited an increase in the number of Tregs but this was not statistically significant. No significant differences in Treg numbers were observed in healthy subjects between the two time points.
Conclusions
An impaired Treg function is likely to play a role in PLE pathogenesis. A UV‐induced increase in the number of Tregs (either naturally or therapeutically) may be a compensatory mechanism by which the immune system counteracts the susceptibility to PLE.
What's already known about this topic?
Patients with polymorphic light eruption (PLE) display immunological abnormalities.
Previous studies have shown that they are resistant to the immune suppressive effects of sunlight.
What does this study add?
We found that the number and suppressive function of regulatory T cells (Tregs) are crucial in the pathogenesis of PLE.
An increase in Treg levels (after photohardening) might be a compensatory mechanism by which the immune system intends to counteract the susceptibility to PLE formation. |
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Bibliography: | ArticleID:BJD13930 FWF Austrian Science Fund - No. KLI 132-B00 Österreichische Nationalbank Anniversary Fund Medical University of Graz istex:ACA46C1A0FB55380DB400987F5682BB73BA43282 ark:/67375/WNG-B9L162HW-Z Fig S1. Flow diagram showing numbers of patients with polymorphic light eruption and healthy controls at each stage of the study.Fig S2. Peripheral blood mononuclear cells of patients and healthy controls were stained with antibodies for CD4, CD127, CD25 and FoxP3.Table S1. Characteristics of PLE patients.Table S2. Median percentages of CD4+CD25highCD127-FoxP3+ Tregs in PLE patients and healthy controls, as assessed by flow cytometry. Conflicts of interest Funding sources This work was supported by the Österreichische Nationalbank Anniversary Fund project no. 13279 and Austrian Science Fund (FWF): project number KLI 132‐B00. N.S. and E.R. were supported through the PhD programme of the Medical University of Graz, Graz, Austria. None declared. ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 N.S. and A.G.‐W. contributed equally to this work. |
ISSN: | 0007-0963 1365-2133 |
DOI: | 10.1111/bjd.13930 |