ABSTRACT
ObjectiveTo investigate the changes of T helper 9 (Th9) cells, interleukin-9 (IL-9), and related transcription factors in previously untreated patients with chronic hepatitis C, as well as their association with clinical indices. MethodsA total of 29 previously untreated patients with chronic hepatitis C who attended Hainan Provincial People’s Hospital from December 2018 to July 2019 were enrolled, and 15 healthy individuals were enrolled as healthy controls. The patients with chronic hepatitis C received sofosbuvir/velpatasvir antiviral therapy for 12 weeks, and then plasma and peripheral mononuclear cells (PBMCs) were isolated. Flow cytometry was used to measure the percentage of CD3+CD4+IL-9+ Th9 cells in PBMCs; ELISA was used to measure the plasma level of IL-9; quantitative real-time PCR was used to measure the relative mRNA expression of IL-9 and the transcription factors PU.1 and Foxo1 in PBMCs. The t-test or the paired t-test was used for comparison between two groups, and a Pearson correlation analysis was used to investigate correlation. ResultsCompared with the healthy controls, the previously untreated chronic hepatitis C patients had significantly lower percentage of peripheral Th9 cells (0.92%±0.14% vs 1.14%±0.21%, t=4.31, P＜0.001) and plasma IL-9 level (248.2±66.97 pg/ml vs 309.02±88.48 pg/ml, t=2.63, P=0.012). The previously untreated chronic hepatitis C patients had significantly lower relative mRNA expression of IL-9 and PU.1 than the healthy controls (t=20.67 and 23.21, both P＜0.001), while there was no significant difference in the relative mRNA expression of Foxo1 between the previously untreated chronic hepatitis C patients and the healthy controls (P＞0.05). In the previously untreated chronic hepatitis C patients, the percentage of peripheral Th9 cells, IL-9 level, and mRNA expression of IL-9 and PU.1 were negatively correlated with HCV RNA (r=-0.46, -0.38, -0.52, and -0.41, all P＜0.05), but they were not correlated with the level of alanine aminotransferase (all P＞0.05). Sofosbuvir/velpatasvir antiviral therapy achieved virologic response in 29 chronic hepatitis C patients, and the percentage of peripheral Th9 cells and the mRNA expression of PU.1 after antiviral therapy were significantly higher than those at baseline (t=2.20 and 6.52, both P＜0.05), while there were no significant changes in the plasma level of IL-9 and the relative mRNA expression of IL-9 from baseline to after treatment (both P＞0.05). ConclusionChronic hepatitis C virus infection may suppress the activation of Th9 cells, suggesting that Th9 cells might be involved in the chronicity of hepatitis C virus infection.