Relationship of redundant Th17 cells and IL-17A, but not IL-17 F, with the severity of obstructive sleep apnoea/hypopnoea syndrome (OSAHS)

Abstract

Background: The pathogenesis of obstructive sleep apnoea/hypopnoea syndrome (OSAHS), a highly prevalent disease, is not completely understood. The purpose of this study was to investigate the contributions of Th17 cells and the Th17-associated cytokines IL-17A and IL-17 F to OSAHS.

Methods: 46 male patients with a clinical suspicion of OSAHS were enrolled and divided into four groups based on their polysomnography results: controls and mild, moderate, and severe OSAHS. The serum levels of IL-17A and IL-17 F were determined by enzyme linked immunosorbent assay (ELISA), pulmonary arterial pressure (PAP) was determined by echocardiography, and Th17 cell frequencies in peripheral blood were measured by flow cytometry.

Results: Serum IL-17A levels in the severe group were elevated (median value: control group 0.89 pg/ml, mild OSAHS 1.02 pg/ml, moderate OSAHS 1.18 pg/ml, and severe OSAHS 1.62 pg/ml; p < 0.05) and positively correlated with AHI (r = 0.52, p < 0.05) but negatively related to the mean O2 saturation and lowest O2 saturation (r = -0.349, p < 0.05; and r = -0.336, p < 0.05, respectively). Although the frequencies of Th17 cells in the OSAHS groups were higher than that in the control group, these differences were not significant (p = 0.275). Pulmonary arterial hypertension was not present in our patients as the median PAP of the normal control and the mild, moderate, and severe OSAHS groups were 26, 27.5, 24.5, and 25.5 mmHg, respectively (p = 0.676).

Conclusion: IL-17A may be involved in the pathogenesis of OSAHS and may represent a target for therapeutic intervention.

Figure 1

Serum level of IL-17A and IL-17 F were assessed by ELISA. The data are presented as median (minimum, maximum). * p < 0.05 versus control group; # p < 0.05 versus mild OSAHS group.

Figure 2

The relationship between AHI and IL-17A level. There was a significant positive relationship between AHI and the IL-17A level (r = 0.520, p < 0.01).

Figure 3

The relationship between LSaO₂ and IL-17A level. There was a significant negative relationship between LSaO₂ and the IL-17A level (r = −0.336, p < 0.05).

Figure 4

The relationship between MSaO₂ and the IL-17A level. There was a significant negative relationship between MSaO₂ and IL-17A level (r = −0.349, p < 0.05).

Figure 5

The percentage of CD4⁺IL-17⁺ cells. Single-cell suspensions prepared from the peripheral blood of 17 patients were double-stained with FITC-conjugated anti-CD4 and PE-conjugated anti-IL-17 and were analysed by flow cytometry.