Frequency of CD4⁺ and CD8⁺ T cells in Iranian chronic rhinosinusitis patients

Chronic Rhinosinusitis (CRS) is a persistent inflammatory disease affecting paranasal sinuses. CRS is categorized into two distinct subgroups defined as CRS with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). Although several immune cells are involved in the CRS pathogenesis, the role of T cells is not fully understood. The objective of the present study was to evaluate the frequency of CD4⁺ and CD8⁺ T cells and macrophages in the sinonasal mucosa of CRS patients, as well as to investigate the specific transcription factors for Th1, Th2, Th17, and Treg cells.

In this study, 15 healthy controls, 12 CRSsNP, and 23 CRSwNP patients participated. CD4⁺, CD8⁺, and CD68⁺ cells were investigated in the sinonasal tissues using immunohistochemistry. The expression of transcription factors related to Th subsets (T-bet, GATA3, Ror-γt, and FoxP3) was evaluated using real-time PCR. Furthermore, CRSwNP patients were defined as eosinophilic when eosinophils consisted of more than 10% of total inflammatory cells. The Kruskal-Wallis, Mann-Whitney, and Spearman tests were used in statistical analyses.

The median (range) age of the studied groups was: 32 (14-67) for CRSwNP, 28 (10-43) for CRSsNP, and 27 (17-44) for controls. The number of eosinophils in CRSwNP patients was higher than two other groups, whereas neutrophils were elevated in both CRSwNP and CRSsNP groups in comparison to controls. The frequency of CD4⁺ and CD8⁺ T cells, macrophages, and total inflammatory cells were significantly increased in CRSwNP and CRSsNP patients compared with controls. The mRNA expression of GATA3 was increased in CRSwNP patients while mRNA expression of Ror-γt was elevated in CRSsNP patients. No significant difference was observed in T-bet mRNA expression among three groups. Both CRSwNP and CRSsNP patients showed decreased FoxP3 mRNA expression in comparison to controls.

The frequency of CD4⁺ and CD8⁺ T cells was elevated in CRS patients. In addition, we demonstrated Th2 dominance in CRSwNP patients and Th17 dominance in CRSsNP patients, implicating different mechanisms may underlie the disease. Better CRS classification and targeted therapeutic strategies may be achievable by determining the pattern of infiltrating inflammatory cells. Therefore, further experimental investigations on T cells are needed.