Peripheral whole blood FOXP3 TSDR methylation: a potential marker in severity assessment of autoimmune diseases and chronic infections

Abstract

Immune dysregulation is a cardinal feature of autoimmune diseases and chronic microbial infections. In particular, regulatory T cells are downregulated in autoimmune diseases while upregulated in chronic microbial infections. FOXP3 is the master regulator of Treg development. Treg-specific demethylated region (TSDR) is a highly conserved locus on the FOXP3 gene that is fully demethylated in natural Tregs but methylated in effector T cells. In our study, we used high resolution melt-polymerase chain reaction (HRM-PCR) to determine the FOXP3 TSDR methylation status in autoimmune diseases and chronic microbial infections. We found that FOXP3 TSDR to have the highest mean melting temperature (highly methylated) in active SLE patients compared to all the other groups (p < 0.001). The psoriasis group also had a significantly high mean melting temperature (78.62 ± 0.20) when compared with the inactive SLE group (78.49 ± 0.29, p < 0.05) and control group (78.44 ± 0.25, p < 0.01). There was no significant difference in melting temperature between inactive SLE and healthy controls. Disease activity in SLE was directly associated with methylation of the FOXP3 TSDR. On the other hand, patients with chronic microbial infections had significantly lower FOXP3 TSDR mean melting temperature (demethylated) when compared with healthy controls (78.28 ± 0.21 vs 78.44 ± 0.25, p < 0.05). Our results suggest that the use of HRM-PCR to detect FOXP3 TSDR methylation status is a reliable and easy method to predict natural regulatory T cell levels in peripheral blood in different disease conditions. Determining FOXP3 TSDR methylation status can be a useful tool in diagnosis, and monitoring the severity of autoimmune diseases and chronic microbial infections.

• Autoimmune diseases
• chronic microbial infections
• FOXP3 TSDR
• HRM-PCR
• psoriasis
• regulatory T cells
• systemic lupus erythematosus

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 81210308042, No. 81220108017 and No. 30972745), the National Basic Research Program of China (973 Plan) (2009CB825605), the programs of Science-Technology Commission of Hunan province (2011FJ2007, 2011TP4019-7, 2012WK3046 and 2012TT2015), the Fundamental Research Funds for the Central Universities and the National Key Clinical Specialty Construction Project of National health and Family Planning Commission of the People’s Republic of China.

Declaration of interest

The authors declare that they have no competing interests. ON designed, executed and analyzed experiments and wrote the manuscript. GL and MZ assisted with experiments design. XY and YY assisted with sample collection. HY assisted with figure drawing. SY, TMC, and YL edited the manuscript. QL conceived and designed the study, and had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. All authors have approved the final version to be published.