Study objectives: Tumor necrosis factor (TNF)-alpha is involved in the pathogenesis of atherosclerosis. In the present study, we examined TNF-alpha production by monocytes, serum levels of TNF-alpha, and the effects of nasal continuous positive airway pressure (nCPAP) in patients with obstructive sleep apnea syndrome (OSAS).
Design: Prospective observational study.
Setting: University hospital.
Subjects: Twenty-four patients with OSAS, 15 obese control subjects, and 12 healthy subjects.
Measurements and results: After polysomnography, venous blood was collected at 5 am. Spontaneous production of TNF-alpha by monocytes for 24 h and serum levels of TNF-alpha were investigated. In addition, patients with moderate-to-severe OSAS were treated with nCPAP for 1 month, and spontaneous production of TNF-alpha by monocytes and serum levels of TNF-alpha were also measured. Spontaneous production of TNF-alpha by monocytes was significantly higher in patients with moderate-to-severe OSAS than in patients with mild OSAS (p < 0.0001), obese control subjects (p < 0.0001), or healthy subjects (p < 0.0001). Serum levels of TNF-alpha were also significantly higher in patients with moderate-to-severe OSAS than in patients with mild OSAS (p < 0.03), obese control subjects (p < 0.0005), or healthy subjects (p < 0.0001). Duration of hypoxia during total sleep time was independently associated with spontaneous production of TNF-alpha by monocytes in patients with OSAS and healthy and obese control subjects. nCPAP significantly decreased spontaneous production of TNF-alpha by monocytes (p < 0.03) and serum levels of TNF-alpha (p < 0.05) in patients with moderate-to-severe OSAS.
Conclusions: Spontaneous production of TNF-alpha by monocytes and serum levels of TNF-alpha are elevated in patients with moderate-to-severe OSAS but are decreased by nCPAP.