Correlation between ILC2 and Th17/Treg ratio in peripheral blood of patients at different stages of Mycobacterium tuberculosis infection / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To study the correlation between type 2 innate lymphocyte (ILC2) and Treg/Th17 ratio in the peripheral blood of patients at different stages of Mycobacterium tuberculosis ( Mtb) infection. Methods:This study recruited 30 individuals with active tuberculosis (ATB group), 26 with treated tuberculosis (RTB group), 22 with latent tuberculosis infection (LTBI group) and 17 negative for tuberculin skin test (TST-negative group). Flow cytometry was used to detect the proportion of ILC2 in CD45 + cells, and that of Th17 and Treg cells in CD4 + T lymphocytes in the peripheral blood of patients in each group. Expression of Foxp3 and RORγt at mRNA level was detected by real-time fluorescence quantitative PCR. Pearson method was used to analyze the correlation between Th17 and Treg, and that between ILC2 and Treg/Th17 ratio in the peripheral blood of patients with ATB and RTB. Results:The proportions of ILC2 in RTB and ATB groups were significantly higher than those of LTBI and TST-negative groups, and the proportion of ILC2 in RTB group was significantly higher than that of ATB group ( P<0.05). The proportion of Th17 in RTB group was lower than that of ATB group ( P<0.05), and the proportions of Th17 in ATB and RTB groups were lower than those of LTBI and TST-negative groups. The proportion of Treg in RTB group was lower than that of ATB group ( P<0.05), and close to that of LTBI group and TST-negative group, but the Treg/Th17 ratios in ATB and RTB groups were higher than those of LTBI and TST-negative groups. There was no significant difference in Treg/Th17 ratio between ATB and RTB groups ( P>0.05). The expression of Foxp3 and RORγt at mRNA level and Foxp3/RORγt ratio changed accordingly. Meanwhile, there was no correlation between Th17 and Treg in ATB or RTB group ( r=0.023, P=0.444; r=0.428, P=0.150). There was a positive correlation between ILC2 and Treg/Th17 ratio in ATB group ( r=0.794, P=0.000), while no correlation was found between ILC2 and Treg/Th17 ratio in RTB group ( r=0.197, P=0.297). Conclusions:In this study, the proportion of ILC2 was increased in the peripheral blood of TB patients, and the proportion of ILC2 in RTB group was higher than that of ATB group. In RTB group, Th17 accounted for a low proportion in the peripheral blood and was involved in inflammatory reactions, while Tregs were not involved in inflammatory reactions, but might have a certain inhibitory effect in patients with ATB. Further studies found that Th17-involved inflammatory reactions were not regulated by Tregs. ILC2 was involved in Treg/Th17 imbalance in ATB patients, but not in RTB patients.