Changes and significance of the ratio of T helper 17 and regulatory T cell in peripheral blood of patients with coal-burning-borne arsenic poisoning

Abstract

Objective To observe the change of T helper 17 (Th17), regulatory T cell (Treg) as a percentage of lymphocytes and the Th17/Treg ratio in peripheral blood of patients with coal-burning-borne arsenic poisoning, and to explore the role of Th17 cells and Treg cells balance in arsenic-induced immune injury. Methods A case-control study was conducted to investigate 149 cases of arsenic poisoning in Yuzhang arsenic poisoning area in the southwestern Guizhou Province, and the age was (50.69 ± 6.14) years old, including 94 males and 55 females. The diagnosis was based on the Diagnosis of Endemic Arsenicosis (WS/T 211-2015), and the cases were divided into mild arsenic poisoning group (39 cases), moderate arsenic poisoning group (54 cases) and severe arsenic poisoning group (56 cases); forty-one residents of non-arsenic exposed villages about 12 km away from the diseased area were collected as control group, the age was (45.76 ± 7.88) years old, including 12 males and 29 females. Hair samples and peripheral blood were collected from the subjects. The content of hair arsenic was detected by inductively coupled plasma mass spectrometry (ICP-MS). The percentages of Th17 cells and Treg cells in peripheral blood lymphocytes were detected by flow cytometry, and changes in the ratio of Th17/Treg in each group were analyzed. Results The hair arsenic contents in control, mild, moderate, and severe arsenic poisoning groups [median (quartile)] were 0.12 (0.08-0.18), 0.20 (0.16-0.33), 0.25 (0.18-0.41), 0.28 (0.21-0.50) μg/g, and the differences were statistically significant between groups (H=52.22, P < 0.01), and the hair arsenic content in each arsenic poisoning group was higher than that of the control group (P < 0.05). The percentages of Th17 cells in peripheral blood lymphocytes of moderate and severe arsenic poisoning groups [(0.42 ± 0.21)%, (0.41 ± 0.23)%] were higher than that of the control group [(0.29 ± 0.16)%, P < 0.05]. The percentages of Treg cells in peripheral blood lymphocytes of mild, moderate and severe arsenic poisoning groups [(0.37 ± 0.18)%, (0.31 ± 0.19)%, (0.27 ± 0.18)%] were lower than that of the control group [(0.71 ± 0.20)%, P < 0.05]; with respect to the mild arsenic poisoning group, the percentage of Treg cells in severe arsenic poisoning group was reduced (P < 0.05). The ratios of Th17/Treg in mild, moderate and severe arsenic poisoning groups (1.17 ± 0.63, 1.56 ± 0.69, 1.83 ± 0.85) were higher than that of the control group (0.43 ± 0.22, P < 0.05); compared with mild arsenic poisoning group, the ratio of Th17/Treg in severe arsenic poisoning group was elevated (P < 0.05). Correlation analysis showed that the hair arsenic content was positively correlated with the percentage of Th17 cells in peripheral blood lymphocytes and the ratio of Th17/Treg (r=0.323, 0.608, P < 0.05), and negatively correlated with the percentage of Treg cells in peripheral blood lymphocytes (r=- 0.486, P < 0.05). Conclusion Coal-burning-borne arsenic poisoning can cause the proportion of Th17 cells in the peripheral blood of patients to increase in lymphocytes, and the proportion of Treg cells in lymphocytes to decrease, which in turn changes the balance of Th17/Treg, resulting in weakened immune tolerance and disorder the regulation of inflammatory response, thus participates in the occurrence and development of arsenic-induced immune damage. Key words: Arsenic poisoning; Coal; T helper 17; Regulatory T cell