Peripheral blood CD4+ T cell populations by CD25 and Foxp3 expression as a potential biomarker: reflecting inflammatory activity in chronic obstructive pulmonary disease

Zhao-Ji Meng,* Jiang-Hua Wu,* Mei Zhou, Sheng-Wen Sun, Shuai-Ying Miao, Hong-Li Han, Long Chen, Xian-Zhi XiongDepartment of Respiratory and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, People’s Republic of China*These authors contributed equally to this workBackground: The temporally dynamic changes of CD25 and Foxp3 expression in CD4+ T cells are initiated by T cell receptor (TCR) signals strength or frequency. There is a deficiency of peripheral markers for assessing COPD activity, and the current study was conducted to explore whether peripheral CD4+ T cell populations based on CD25 and Foxp3 expression could serve as an indicator for COPD inflammatory activity.Methods: The distribution and phenotypic characteristics of CD4+CD25±Foxp3± T cells from peripheral blood in different populations were determined by flow cytometry. The model for the differentiation of CD4+ T cells populations by CD25 and Foxp3 expression was explored in vitro.Results: The frequencies of peripheral CD4+CD25+Foxp3− T cells and CD4+CD25+Foxp3+ T cells were increased in AECOPD patients, whereas the frequency of CD4+CD25−Foxp3+ T cells was increased in SCOPD patients without receiving systemic treatment. Phenotypic analysis revealed that CD4+CD25+Foxp3− T cells, CD4+CD25+Foxp3+ T cells and CD4+CD25−Foxp3+ T cells had received antigenic stimulation and resembled central memory or effector memory T cells. The differentiation of CD4+ T cells populations by CD25 and Foxp3 expression was dictated by TCR signals. The paired study indicated that the frequencies of CD4+CD25+Foxp3− T cells, CD4+CD25+Foxp3+ T cells and CD4+CD25− Foxp3+ T cells were decreased while the frequency of CD4+CD25−Foxp3− T cells were increased in the same patients from AECOPD to convalescence.Conclusions: Collectively, we propose that the dynamic changes of CD4+ T cell populations by CD25 and Foxp3 expression could function as potential biomarkers for reflecting inflammatory activity in COPD.Keywords: COPD, CD4+ T cell subsets, inflammation, peripheral biomarkers