leukotriene-b4 and Sleep-Apnea--Obstructive

There is increasing evidence that inflammation plays an important role in the development of cardiovascular complications in patients with obstructive sleep apnoea (OSA). No previous works have studied levels of soluble tumour necrosis factor-alpha receptor (sTNFR)-1 in patients with OSA. The aims of the present study were to examine serum levels of sTNFR-1 and the effect of nasal continuous positive airway pressure (CPAP) in patients with OSA. A prospective, randomised, placebo-controlled crossover study was performed. In total, 30 consecutive newly diagnosed OSA patients (apnoea/hypopnoea index 43.8+/-27.0 events x h(-1)) and 15 healthy obese patients were selected. Urinary levels of norepinephrine and epinephrine, as well as plasma sTNFR-1, tumour necrosis factor (TNF)-alpha, interleukin (IL)-6 and leukotriene (LT)B(4) levels were obtained at baseline and after 3 months of CPAP or sham CPAP. Nocturnal urinary levels of norepinephrine, epinephrine and sTNFR-1 (1,053+/-269 versus 820+/-166 pg x mL(-1)) were significantly higher in OSA patients. There were no significant differences in plasma levels of IL-6, LTB(4), or TNF-alpha between the two study groups. There were no significant differences in blood pressure, urinary catecholamine levels, or plasma IL-6, LTB(4) and TNF-alpha levels after both treatment modalities. However, after 3 months of effective CPAP usage, sTNFR-1 levels were significantly reduced (1,053+/-269 versus 899+/-254 pg x mL(-1)). Obstructive sleep apnoea patients have higher levels of soluble tumour necrosis factor-alpha receptor 1 than individuals without OSA; soluble tumour necrosis factor-alpha receptor 1 levels are lowered by continuous positive airway pressure therapy. These findings further corroborate a potential role of inflammation in the natural history of obstructive sleep apnoea.

Topics: Adult; Continuous Positive Airway Pressure; Cross-Over Studies; Double-Blind Method; Epinephrine; Humans; Interleukin-6; Leukotriene B4; Male; Middle Aged; Norepinephrine; Placebos; Prospective Studies; Receptors, Tumor Necrosis Factor, Type I; Sleep Apnea, Obstructive; Tumor Necrosis Factor-alpha

Leukotriene B(4) (LTB(4)) production increases in obstructive sleep apnea syndrome (OSA) and is linked to early vascular remodeling, the mechanism of which is unknown. The objective of this study was to to determine the molecular mechanisms of LTB(4) pathway activation in polymorphonuclear cells (PMNs) and early vascular remodeling in OSA and the specific contribution of intermittent hypoxia (IH). PMNs were isolated from 120 OSA patients and 33 healthy subjects and used for measurements of LTB(4) production, determination of mRNA and protein expression levels, or exposed for four cycles of in vitro IH. PMNs derived from OSA patients exhibited increased LTB(4) production, for which apnea-hypopnea index was an independent predictor (P=0.042). 5-Lipoxygenase-activating protein (FLAP) mRNA and protein increased significantly in PMNs from OSA patients versus controls and were associated with carotid luminal diameter and intima-media thickness. LTB(4) (10 ng/ml) increased IL-6 (P=0.006) and MCP-1 (P=0.002) production in OSA patient monocytes. In vitro exposure of PMNs from controls to IH enhanced FLAP mRNA levels (P= 0.027) and induced a 2.7-fold increase (P=0.028) in LTB(4) secretion compared with PMNs exposed to normoxia. In conclusion, upregulation of FLAP in PMNs in response to IH may participate in early vascular remodeling in OSA patients, suggesting FLAP as a potential therapeutic target for the cardiovascular morbidity associated with OSA.

Topics: 5-Lipoxygenase-Activating Proteins; Adult; Aged; Atherosclerosis; Blood Vessels; Case-Control Studies; Cell Hypoxia; Cohort Studies; Female; Gene Expression Regulation; Humans; Leukotriene B4; Male; Middle Aged; Monocytes; Neutrophils; Paracrine Communication; RNA, Messenger; Sleep Apnea, Obstructive

Severity of oxygen desaturation is predictive of early atherosclerosis in obstructive sleep apnoea (OSA). Leukotriene (LT)B(4) is a lipid mediator involved in atherogenesis. In 40 non-obese OSA patients, free of a cardiovascular history, and 20 healthy volunteers, the following were evaluated: 1) LTB(4) production by polymorphonuclear leukocytes (PMNs) stimulated with A23187; and 2) the relationships between LTB(4) production and both OSA severity and infraclinical atherosclerosis markers. The effect of continuous positive airway pressure (CPAP) on LTB(4) production was also studied. An overnight sleep study was followed by first-morning blood sampling. Isolated PMNs were stimulated with A23187 in order to induce LTB(4) production, which was measured by liquid chromatography-tandem mass spectrometry. Carotid intima-media thickness (IMT) and luminal diameter were measured in subset groups of 28 OSA patients and 11 controls. LTB(4) production was increased in OSA patients compared with controls. LTB(4) levels correlated with the mean and minimal arterial oxygen saturation (S(a,O(2))). LTB(4) production correlated with luminal diameter data in patients with a mean S(a,O(2)) of < or = 94% but not with IMT. Lastly, CPAP significantly reduced LTB(4) production by 50%. Leukotriene B(4) production is increased in obstructive sleep apnoea in relation to oxygen desaturation. Leukotriene B(4) could promote early vascular remodelling in moderate-to-severe hypoxic obstructive sleep apnoea patients.

Topics: Adult; Blood Gas Analysis; Case-Control Studies; Continuous Positive Airway Pressure; Female; Humans; Hypoxia; Leukotriene B4; Male; Neutrophils; Polysomnography; Sleep Apnea, Obstructive