[Expression of CD8⁺Treg cells in chronic rhinosinusitis and its correlation with eosinophilic infiltration]

Objective: To detect the percentages of CD8⁺Treg cells in the nasal mucosa and peripheral blood of chronic rhinosinusitis (CRS) and to explore their correlation with eosinophilic infiltration. Methods: Thirty-three chronic rhinosinusitis with polyp (CRSwNP), 26 chronic rhinosinusitis without polyp (CRSsNP) and 27 control patients who were collected with the nose mucosal tissue and peripheral blood in the Third Affiliated Hospital of Sun Yat-sen University from March 2017 to October 2018 were selected, including 59 males and 27 females, aging from 18 to 72 years. Hematoxylin and eosin (HE) staining was used to observe the number of eosinophils in the nasal tissues and to classify the CRS into eosinophilic CRS (ECRS) and non-eosinophilic CRS (Non-ECRS). Flow cytometry was used to detect the percentages of CD4⁺ and CD8⁺T cells in lymphocytes of nasal mucosa and peripheral blood. The percentages of CD8⁺Foxp3⁺Treg cells, CD8⁺Foxp3^-IL-10⁺Treg cells, CD8⁺IFN-γ⁺T cells (Tc1), CD8⁺IL-4⁺T cells (Tc2) and CD8⁺IL-17A⁺T cells (Tc17) in lymphocytes of nasal mucosa and peripheral blood were also tested. Besides, the percentages of Foxp3⁺TGF-β⁺Treg cells and Foxp3⁺IL-10⁺Treg cells in CD8⁺T cells were determined. All data were represented by M (IQR). GraphPad 7.0 and SPSS 16.0 were used for illustration and statistical analysis. Results: The percentage of CD8⁺T cells (37.75%(17.35%)) was higher than that of CD4⁺T cells (4.72%(4.29%)) in nasal mucosa (Z=-5.70, P<0.001), while lower (23.60%(9.33%)) than that of CD4⁺T cells (44.05% (10.93%)) in peripheral blood (t=9.72, P<0.001). CRSwNP patients possessed the highest Tc2 (1.82% (1.22%)) and Tc17 (1.93% (2.32%)) percentages than CRSsNP (Tc2: 0.84% (0.79%); Tc17: 0.54% (1.04%)) and control (Tc2: 1.09% (0.92%); Tc17: 0.47% (0.51%), both P<0.05) patients. While, CRSwNP patients possessed the lowest CD8⁺Foxp3⁺Treg cells percentage (0.10% (0.32%)) than CRSsNP (0.43% (1.45%)) and control (0.48% (0.83%), Z value was -2.24, -2.22, respectively, P value was 0.025, 0.027, respectively). The percentages of Foxp3⁺TGF-β⁺Treg cells and Foxp3⁺IL-10⁺Treg cells of CD8⁺T cells in nasal mucosa in CRSwNP were also lower than controls (Z value was 1.46, 0.49, respectively, both P=0.001). Moreover, the percentage of CD8⁺Foxp3^-IL-10⁺Treg cells of CD8⁺T cells was decreased in nasal mucosa of CRSwNP patients (0.14% (0.28%)) when compared with that of CRSsNP (0.89% (0.81%), Z=0.61, P=0.03). ECRS patients had the lower percentages of CD8⁺Foxp3⁺Treg cells (0.07% (0.44%)) and CD8⁺Foxp3^-IL-10⁺Treg cells (0.13% (0.21%)) than Non-ECRS patients (CD8⁺Foxp3⁺Treg cells: 0.53% (0.75%); CD8⁺Foxp3^-IL-10⁺Treg cells: 0.29% (0.76%), t value was 2.14, 2.78, respectively, both P<0.05). The percentage of CD8⁺Foxp3⁺Treg cells and the ratio of CD8⁺Foxp3^-IL-10⁺T per CD8⁺T cells were negatively correlated with the percentage of eosinophils in CRS patients(R² value was 0.56, 0.78, respectively, both P<0.001). There was no significant difference in the distribution of CD8⁺Fxop3⁺Treg cells and CD8⁺Fxop3^-IL-10⁺Treg cells in peripheral blood among different groups. Conclusion: The percentages of CD8⁺Treg cells decrease in CRSwNP patients, especially in ECRS patients, which are opposite to that of Tc2 and Tc17, and negatively correlate with the eosinophils percentage. This indicates that the decrease in the ratio of CD8⁺Treg cell may be associated with the immune-imbalance and eosinophilic infiltration in nasal mucosa of CRS patients.