Roberto Sabato

Exhaled NO and iNOS expression in sputum cells of healthy, obese and OSA subjects

Background.  Obstructive sleep apnoea (OSA) is associated with airways inflammation; a key role in this regard seems to be played by nitric oxide (NO). The aim of this study was to measure exhaled NO and expression of its enzyme, the inducible nitric oxide synthase (iNOS) in cells of induced sputum in OSA patients and in obese subjects without sleep apnoea and to correlate these inflammatory markers with severity of OSA.

Characterization of obstructive sleep apnea–hypopnea syndrome (OSA) population by means of cluster analysis

Obstructive sleep apnea–hypopnea syndrome (OSA) is being identified increasingly as an important health issue. It is typified by repeated episodes of upper airway collapse during sleep leading to occasional hypoxaemia, sleep fragmentation and poor sleep quality. OSA is also being considered as an independent risk factor for hypertension, diabetes and cardiovascular diseases, leading to increased multi‐morbidity and mortality. Cluster analysis, a powerful statistical set of techniques, may help in investigating and classifying homogeneous groups of patients with similar OSA characteristics. This study aims to investigate the (possible) different groups of patients in an OSA population, and to analyse the relationships among the main clinical variables in each group to better understand the impact of OSA on patients. Starting from a well‐characterized OSA population of 198 subjects afferent to our sleep centre, we identified three different communities of OSA patients. The first has a very severe disease [apnea–hypopnea index (AHI) = 65.91 ± 22.47] and sleep disorder has a strong impact on daily life: a low level of diurnal partial pressure of oxygen (PaO2) (77.39 ± 11.64 mmHg) and a high prevalence of hypertension (64%); the second, with less severe disease (AHI = 28.88 ± 17.13), in which sleep disorders seem to be less important for diurnal PaO2 and have a minimum impact on comorbidity; and the last with very severe OSA (AHI = 57.26 ± 15.09) but with a low risk of nocturnal hypoxaemia (T90 = 11.58 ± 8.54) and less sleepy (Epworth Sleepiness Scale 10.00 ± 4.77).

The role of obstructive sleep apnea syndrome and obesity in determining leptin in the exhaled breath condensate

Leptin plays a key role in obstructive sleep apnea syndrome (OSAS). Leptin production in human airways has been previously evaluated by measuring leptin concentration in the exhaled breath condensate and in the induced sputum. The aim was to study leptin expression in the cells of induced sputum and in exhaled breath condensate of subjects with OSAS. Moreover, leptin concentrations in the blood were measured in the same groups of subjects. We enrolled four groups of patients: (1) obese patients with OSAS (OO); (2) non-obese patients with OSAS (NOO); (3) obese patients without OSAS (ONO); and (4) non-obese subjects without OSAS (C). Leptin expression was evaluated by immunocytochemistry in the sputum cells of the enrolled subjects. The concentrations of leptin in the exhaled breath condensate and plasma were measured by using a specific enzyme immunoassay. Leptin protein expression and the percentage of macrophages and neutrophils expressing leptin were higher in the induced sputum of OO, NOO and ONO patients than in C. Leptin concentrations in the exhaled breath condensate were significantly higher in OO patients (5.12 (3.8-6.6) ng ml(-1)) than in NOO (4.1 (3.9-5.2) ng ml(-1)) and ONO (4.2 (3.6-5.0) ng ml(-1)) patients. The concentration of leptin in plasma was significantly more elevated in OO (36 (24-65.9) ng ml(-1)) than in NOO (30.2 (12.4-51.4) ng ml(-1)), whereas it was not significantly different in ONO patients. This study showed that leptin in sputum and in the exhaled breath condensate is higher in obese patients with OSAS than in obese subjects without OSAS. Moreover, different mechanisms for determining leptin concentrations in the exhaled breath condensate and the blood are suggested.

Mitochondrial DNA alteration in obstructive sleep apnea

BackgroundObstructive Sleep Apnea (OSAS) is a disease associated with the increase of cardiovascular risk and it is characterized by repeated episodes of Intermittent Hypoxia (IH) which inducing oxidative stress and systemic inflammation. Mitochondria are cell organelles involved in the respiratory that have their own DNA (MtDNA). The aim of this study was to investigate if the increase of oxidative stress in OSAS patients can induce also MtDNA alterations.Methods46 OSAS patients (age 59.27 ± 11.38; BMI 30.84 ± 3.64; AHI 36.63 ± 24.18) were compared with 36 control subjects (age 54.42 ± 6.63; BMI 29.06 ± 4.7; AHI 3.8 ± 1.10). In blood cells Content of MtDNA and nuclear DNA (nDNA) was measured in OSAS patients by Real Time PCR. The ratio between MtDNA/nDNA was then calculated. Presence of oxidative stress was evaluated by levels of Reactive Oxygen Metabolites (ROMs), measured by diacron reactive oxygen metabolite test (d-ROM test).ResultsMtDNA/nDNA was higher in patients with OSAS than in the control group (150.94 ± 49.14 vs 128.96 ± 45.8; p = 0.04), the levels of ROMs were also higher in OSAS subjects (329.71 ± 70.17 vs 226 ± 36.76; p = 0.04) and they were positively correlated with MtDNA/nDNA (R = 0.5, p < 0.01).ConclusionsIn OSAS patients there is a Mitochondrial DNA damage induced by the increase of oxidative stress. Intermittent hypoxia seems to be the main mechanism which leads to this process.

Effect of CPAP-therapy on bronchial and nasal inflammation in patients affected by obstructive sleep apnea syndrome*

BACKGROUND Obstructive sleep apnea syndrome (OSAS) has been shown to be associated to upper and lower airways inflammation. Continuous positive airway pressure (CPAP) is the elective treatment of OSAS. The aim of the present study was to assess the effect of CPAP-therapy on airway and nasal inflammation. METHODS In 13 non-smoking subjects affected by untreated OSAS and in 11 non-smoking normal volunteers, airway inflammation was detected by analyses of the induced sputum. In the OSAS group measurements were repeated after 1, 10 and 60 days of the appropriate CPAP treatment. In addition, in 12 subjects of the OSAS group, nasal inflammation was detected by the analysis of induced nasal secretions at baseline, and after 1, 10 and 60 days of CPAP treatment. RESULTS OSAS patients, compared to normal controls, showed at baseline a higher percentage of neutrophils and a lower percentage of macrophages in the induced sputum. One, 10 and 60 days of appropriate CPAP-therapy did not change the cellular profile of the induced sputum. In addition, in the OSAS patients, the high neutrophilic nasal inflammation present under baseline conditions was not significantly modified by CPAP-therapy. Finally, no patients developed airway hyper-responsiveness after CPAP therapy. CONCLUSIONS In OSAS subjects, the appropriate CPAP-therapy, while correcting the oxygen desaturation, does not modify the bronchial and nasal inflammatory profile.

Airway cell patterns in patients suffering from COPD and OSAS (Overlap Syndrome).

BACKGROUND Obstructive sleep apnea syndrome (OSAS) and chronic obstructive pulmonary disease (COPD) are two diseases that often coexist within an individual. This coexistence is known as Overlap Syndrome (OS). Both diseases are characterized by local and systemic inflammations, but no studies to date have investigated local airway inflammation in patients suffering from Overlap Syndrome. METHODS We performed a Berlin Questionnaire to evaluate the presence of the principal OSAS symptoms, a pulmonary function test, and then a nocturnal oximetry and polysomnography in 72 patients that were divided into five groups: OS (n = 18), COPD (n = 15), OSAS (n = 16), 12 obese without OSAS or COPD, and one control group of 11 normal subjects. All patients underwent sputum induction and the analysis of cell patterns were evaluated in all groups. The relationship with the degree of obesity, airway obstruction and OSAS severity was also evaluated. RESULTS The percentage of neutrophils in induced sputum was higher in OS (74.33% ± 14.8), COPD (63.33% ± 13.22) and OSAS (60.69% ± 17.6) subjects compared with control groups of obese (43.5% ± 17.49) and normal weight (32.04% ± 12.26). No difference was found among Overlap, COPD, and OSAS patients (p = 0.56). A negative correlation was found between PaO(2) and percentage of airway neutrophils (r = -0.29, p < 0.05); similarly, no correlations arose between BMI, FEV(1) or ODI. CONCLUSION Patients suffering from Overlap Syndrome present a high percentage of neutrophils in induced sputum like patients affected by COPD or OSAS alone. Our result suggests that airway inflammations is always involved in all of these diseases, even though probably sustained by different mechanisms.

Prevalence of comorbidities in patients with obstructive sleep apnea syndrome, overlap syndrome and obesity hypoventilation syndrome

Sleep‐disordered breathing causes a burden to the sufferer, the health care system and the society. Most studies have focused on obstructive sleep apnea (OSA); however, the prevalence of comorbidities in patients affected by overlap syndrome (OS) and obesity hypoventilation syndrome (OHS) has not been carefully evaluated.