Fig 1.
Customized intermittent hypoxia chamber to establish intermittent hypoxia in a murine model of OSA.
(A) Customized chamber with gas pump, (B) gas exchanger, (C) PC controller of intermittent hypoxia, and (D) nitrogen gas source. The capacities of the nitrogen and oxygen gas pumps were designed to rapidly alter the air composition in the chamber from 21% O2 (room air conditions) to 1% O2 within a minute. This corresponds to a maximum of 30 apnea conditions per hour.
Fig 2.
Experimental timeline to study the effect of nasal exposure of mice to intermittent hypoxia.
Graphical representation of the intermittent hypoxia (IH) protocol. (A) IH protocol was conducted for 28 days during the 7-h light phase. (B) The IH groups were exposed to intermittent hypoxia for 7 h per day. During IH, the fractional inspired O2 was reduced from room air levels to approximately 5% within 2 min, followed by re-oxygenation to room air levels within the subsequent 2-min period.
Fig 3.
The fluctuation of oxygen saturation levels in the intermittent hypoxia mouse model and the control (normoxia).
The data obtained by exposing to intermittent hypoxia and normoxia protocols for 30 minutes. Data are expressed as the mean ± S.E. (C57BL/6N mice, n = 5 per group). N, normoxia group. IH, intermittent hypoxia group.
Fig 4.
Frequency of regulatory T cells and cytokines Th1, Th2, and Th17 measured using flow cytometry in the OSA mouse model.
(A) In the IH group, the distribution of decreased CD4 + CD25 + Foxp3 + regulatory T cells was statistically significant compared to the N group. Data are expressed as the mean ± S.E. (C57BL/6N mice, n = 10 per group). (B) IL-17A and IL-4 were increased significant compared to the N group. Data are expressed as the mean ± S.E. (C57BL/6N mice, n = 8 per group). N, normoxia group. IH, intermittent hypoxia group. The significant difference between groups were indicated by asterisks (*p < 0.05, **p < 0.01, ***p < 0.001, ****p <0.0001).
Fig 5.
Histopathological analysis of nasal tissues and their quantification with western blotting in the OSA mouse model.
(A) There were increase in HIF-1α, p65, phosphor-p65, IL-6 and TNF- α and a significant decrease in Foxp3 in the IH group compared to the N group. Data are expressed as the mean ± S.E. (C57BL/6N mice, n = 4 per group). (B) The expression of HIF-1α, phospho-65, and p65 increased while the expression of Foxp3 was decreased. Data are expressed as the mean ± S.E. (C57BL/6N mice, n = 10 per group). N, normoxia group. IH, Intermittent hypoxia group. The significant difference between groups were indicated by asterisks (*p < 0.05, **p < 0.01, ***p < 0.001, ****p <0.0001).
Fig 6.
Frequency of regulatory T cells and Th1, Th2, and Th17 cytokine measured using flow cytometry in the OSA recovery mouse model.
(A) Expression of CD4 + CD25 + Foxp3 + regulatory T cells did not significantly vary between the N-rest and IH-rest groups. (B) Expression of Th1, Th2, and Th17 cytokine did not significantly vary between the N-rest and IH-rest groups. Data are expressed as the mean ± S.E. (C57BL/6N mice, n = 6 per group). N, normoxia group. IH, intermittent hypoxia group.
Fig 7.
Histopathological analysis of nasal tissues and their quantification with western blotting in the OSA recovery mouse model.
(A) Expression of HIF-1α, p65, phosphor-p65, IL-6 and TNF-α did not significantly vary between the N-rest and IH-rest groups. (B) Expression of HIF-1α, phospho-65, and p65 did not significantly vary between the N-rest and IH-rest groups. Data are expressed as the mean ± S.E. (C57BL/6N mice, n = 5 per group). N, normoxia group. IH, Intermittent hypoxia group. The significant difference between groups were indicated by asterisks (*p < 0.05, **p < 0.01, ***p < 0.001, ****p <0.0001).