Roflumilast inhibits the release of chemokines and TNF-α from human lung macrophages stimulated with lipopolysaccharide.

BACKGROUND AND PURPOSE: Lung macrophages are critically involved in respiratory diseases. This study assessed the effects of the PDE4 inhibitor roflumilast and its active metabolite, roflumilast N-oxide on the release of a range of chemokines (CCL2, 3, 4, CXCL1, 8, 10) and of TNF-α, from human lung macrophages, stimulated with bacterial lipopolysaccharide LPS. EXPERIMENTAL APPROACH: Lung macrophages isolated from resected human lungs were incubated with roflumilast, roflumilast N-oxide, PGE(2), the COX inhibitor indomethacin, the COX-2 inhibitor NS-398 or vehicle and stimulated with LPS (24 h). Chemokines, TNF-α, PGE(2) and 6-keto PGF(1α) were measured in culture supernatants by immunoassay. COX-2 mRNA expression was assessed with RT-qPCR. PDE activities were determined in macrophage homogenates. KEY RESULTS: Expression of PDE4 in lung macrophages was increased after incubation with LPS. Roflumilast and roflumilast N-oxide concentration-dependently reduced the LPS-stimulated release of CCL2, CCL3, CCL4, CXCL10 and TNF-α from human lung macrophages, whereas that of CXCL1 or CXCL8 was not altered. This reduction by the PDE4 inhibitors was further accentuated by exogenous PGE(2) (10 nM) but abolished in the presence of indomethacin or NS-398. Conversely, addition of PGE(2) (10 nM), in the presence of indomethacin restored inhibition by roflumilast. LPS also increased PGE(2) and 6-keto PGF(1α) release from lung macrophages which was associated with an up-regulation of COX-2 mRNA. CONCLUSIONS AND IMPLICATIONS: Roflumilast and roflumilast N-oxide reduced LPS-induced release of CCL2, 3, 4, CXCL10 and TNF-α in human lung macrophages.

Identification of a sleep bruxism subgroup with a higher risk of pain.

Sleep bruxism research diagnostic criteria (SB-RDC) have been applied since 1996. This study was performed to validate these criteria and to challenge the hypothesis that pain is associated with lower frequencies of orofacial activities. Polygraphic recordings were made of 100 individuals presenting with a clinical diagnosis of sleep bruxism and 43 control individuals. TwoStep Cluster analyses (SPSS) were performed with sleep bruxism variables to reveal groupings among sleep bruxers and control individuals. Participants completed questionnaires during screening, diagnosis, and recording sessions. Cluster analysis identified three subgroups of sleep bruxers. Interestingly, 45 of the 46 sleep bruxers with values below SB-RDC were classified in the low-frequency cluster. These individuals were more likely to complain of pain and fatigue of masticatory muscles than were the higher-frequency sleep bruxers (odds ratios > 3.9, p < 0.01). Sleep bruxers were distributed among three heterogeneous groups. Sleep bruxers with low frequencies of orofacial activities were more at risk of reporting pain.

Quantitative polygraphic controlled study on efficacy and safety of oral splint devices in tooth-grinding subjects.

The efficacy of occlusal splints in diminishing muscle activity and tooth-grinding damage remains controversial. The objective of this study was to compare the efficacy and safety of an occlusal splint (OS) vs. a palatal control device (PCD). Nine subjects with sleep bruxism (SB) participated in this randomized study. Sleep laboratory recordings were made on the second night to establish baseline data. Patients then wore each of the splints in the sleep laboratory for recording nights three and four, two weeks apart, according to a crossover design. A statistically significant reduction in the number of SB episodes per hour (decrease of 41%, p = 0.05) and SB bursts per hour (decrease of 40%, p < 0.05) was observed with the two devices. Both oral devices also showed 50% fewer episodes with grinding noise (p = 0.06). No difference was observed between the devices. Moreover, no changes in respiratory variables were observed. Both devices reduced muscle activity associated with SB.

Association between sleep bruxism, swallowing-related laryngeal movement, and sleep positions.

STUDY OBJECTIVE: To describe the relationships of sleep bruxism to swallowing and sleep positions. DESIGN: Controlled descriptive study. SETTING: Polysomnography and audio-video recordings were done in a hospital sleep laboratory. PARTICIPANTS: Nine patients with sleep bruxism and 7 normal subjects were matched for age and sex. INTERVENTIONS: n/a. MEASUREMENTS AND RESULTS: During sleep, patients with sleep bruxism showed a higher frequency of rhythmic masticatory muscle activity episodes (6.8 +/- 1.0 [SEM]/h) than did normals (0.5 +/- 0.1/h, p < 0.01). Swallowing-related laryngeal movements occurred more frequently in sleep of patients with sleep bruxism (6.8 +/- 0.8/h) than in normals (3.7 +/- 0.3/h, p < 0.01). In both groups, during sleep, close to 60% of rhythmic masticatory muscle activity episodes were associated with swallowing. In sleep bruxism patients, 68% of swallowing events occurred during rhythmic masticatory muscle activity episodes, while only 10% of swallowing events were associated with rhythmic masticatory muscle activity in normal subjects. Sleep bruxism patients and normals spent 95.5% and 87.3% of sleeping time in the supine and lateral decubitus positions, respectively. In both groups, up to 96% of rhythmic masticatory muscle activity and swallowing were observed in the supine and lateral decubitus position. In sleep bruxism patients, although sleeping time did not differ between the 2 sleeping body positions, 74% of rhythmic masticatory muscle activity and swallowing events were scored in the supine position compared to 23% in the lateral decubitus position. CONCLUSIONS: During sleep, rhythmic masticatory muscle activity is often associated with swallowing. In sleep bruxism patients, most of these oromotor events are observed in the supine position. The physiologic link between rhythmic masticatory muscle activity and swallowing and the clinical relevance of sleep position in sleep bruxism management need to be investigated.

Evidence that experimentally induced sleep bruxism is a consequence of transient arousal.

Spontaneous rhythmic masticatory muscle activity (RMMA) during sleep occurs more frequently following spontaneous transient micro-arousal in patients with sleep bruxism (SB) and normal controls. Here, we tested the hypothesis that an experimental arousal would be followed by an increase in RMMA. We identified RMMA on polygraphic recordings taken before and after sensory stimulation to induce experimental arousal in eight SB patients and eight matched normal subjects. The rate of experimental arousal and the level of resting electromyographic activity in masseter and suprahyoid muscles during sleep did not differ between the groups. In both, muscle tone and heart rate increased during the experimental arousal. Although post-arousal RMMA occurred in all SB patients, it was seen in only one normal subject. Moreover, tooth-grinding occurred during 71% of the evoked RMMA in SB patients. These results support the hypothesis that SB is an exaggerated form of oromotor activity associated with sleep micro-arousal.

Lower number of K-complexes and K-alphas in sleep bruxism: a controlled quantitative study.

OBJECTIVES: Although patients with sleep bruxism (SB) show a higher incidence of rhythmic masticatory muscle activity (RMMA) during sleep than matched normal controls, they are good sleepers. Sleep macrostructure (e.g. total sleep time, sleep latency, number of awakenings or sleep stage shifts and sleep stage duration) is similar between groups. Differences in sleep microstructure between SB patients and normals have been investigated only in few studies. The aim of the present study was to quantify number of microarousals, K-complexes, K-alphas, EEG spindles, and the density of slow wave activity, in both groups, in order to better understand the pathophysiology of SB. METHODS: Ten normal sleepers were matched for age and gender with 10 patients who exhibited frequent tooth-grinding during sleep. Using quantitative polysomnographic measures, we compared the above-mentioned sleep variables in both groups. Data are presented as indices for total sleep and for consecutive non-rapid eye movement (non-REM) episodes over non-REM to rapid eye movement (REM) cycles and per hour of sleep. RESULTS: SB patients showed 6 times more RMMA episodes per hour of sleep than normals (P<0.001), with a higher frequency in the second and third non-REM to REM cycles. SB patients presented 42.7% fewer K-complexes per hour of stage 2 sleep, but only normals showed a decline from the first to fourth non-REM episode. Only 24% of SB-RMMA episodes were associated with K-complexes in 60 s. The number of K-alphas was 61% lower in SB patients, no change across non-REM episodes was noted. While no difference in electroencephalographic (EEG) spindles or slow wave activity (SWA) was observed between groups, EEG spindles increased and SWA decreased linearly over consecutive non-REM to REM cycles. CONCLUSIONS: According to our observations, good sleep in SB patients is characterized by a low incidence of K-complexes or K-alphas and by the absence of any difference in other sleep microstructure variables or SWA.

Variability in sleep bruxism activity over time.

Sleep bruxism (SB) is an oral activity associated with jaw movements and tooth grinding. Sleep bruxism is believed to be highly variable over time, with subjects showing no activity on some nights and intense activity on others. Assessment of SB variability in individual patients is necessary for clinical trials designed to estimate the efficacy of SB management strategies. The present study analysed SB night-to-night variability over time in nine moderate to severe SB patients. Excluding the first night for habituation, a total of 37 nights were analysed, with a range of 2-8 nights per subject. The interval between the first and the last recording was between 2 months and 7.5 years. The outcomes were the number of SB episodes per hour, number of SB bursts per hour and number of SB episodes with grinding noise. The within subject variability of the three SB oromotor outcomes was evaluated using standard deviation (SD) and coefficient of variation. To verify the diagnosis of subjects over time, the values of the oromotor outcomes were compared with a standard research diagnostic cut-off: (1) Number of SB episodes per hour >4, (2) Number of SB bursts per hour >25, (3) Number of SB episodes with noise per night >1 (Lavigne et al. 1996). The mean coefficient of variation for the nine subjects was 25.3% for SB episodes per hour, 30.4% for SB bursts per hour and 53.5% for episodes with noise. Linear regression showed that the number of SB episodes per hour of stages 1 and 2 explains a large proportion of the variability. The SB diagnosis remained constant over time for every subject: 35 nights over 37 respected criteria 1 and 2, while grinding was present every night. These results indicate that while the SB diagnostic remains relatively constant over time in moderate to severe sleep bruxers, individual variability could be important in some SB patients.

A controlled daytime challenge of motor performance and vigilance in sleep bruxers.

Many etiological factors have been suggested for sleep bruxism. Among these, elevated mental and physical alertness has been proposed to characterize sleep bruxers. The present study tests the hypothesis that, during the day-time, sleep bruxers are more vigilant and more prone to react to a motor command than are control subjects. Seven sleep bruxers, diagnosed polysomnographically according to validated research criteria, were matched for age and gender to seven control subjects. A simple reaction time task was selected to assess daytime vigilance and motor responsiveness. The following physiological measures were recorded: reaction time, error rate, electroencephalography, electrocardiography, electromyography, and video detection of body movements. Analysis of these variables showed no differences between groups. During the test, bruxers and controls showed a parallel decrease in EEG vigilance and heart rate over time. Frequency of orofacial and body movements was the same in both groups, and no clenching activity was observed during the experimental test. Subjects' visual analog scale ratings revealed that both controls and bruxers were more competitive after the test than before, and bruxers were slightly more anxious than controls before and after the test. Together, the results indicate that sleep bruxers are neither more vigilant nor more prone to react to a motor command during the daytime than are control subjects.

Evidence against a humoral control mechanism in adrenal catecholamine secretion during insulin-induced hypoglycemia.

The present study tested the hypothesis that a humoral control mechanism is involved in the enhanced adrenal catecholamine secretion during insulin-induced hypoglycemia. The experiments were carried out in anesthetized dogs in which neuronal and humoral components were simultaneously determined by measuring catecholamine output from the right innervated and the left acutely denervated adrenal gland, respectively. Different levels of hypoglycemia were induced by intravenous injection of insulin with doses of 0.075 (n = 6), 0.150 (n = 6), and 0.300 IU/kg (n = 6) in three separate groups of dogs. Catecholamine output in the right innervated gland increased dose dependently (P less than 0.05), reaching a maximum level 45 min after insulin administration. By contrast, catecholamine output from the left denervated adrenal gland remained unchanged at all doses tested. In sham-denervated animals (n = 7), catecholamine output from the left adrenal gland increased to a magnitude similar to that observed in the right innervated gland after insulin administration. Plasma glucose concentration significantly decreased in a dose-dependent manner, reaching a nadir 30 min after insulin administration. Maximum decreases in plasma glucose concentration could be strongly correlated with maximum increases in catecholamine output from the right innervated adrenal gland (r = -0.66, n = 18, P = 0.011), but not with those from the left denervated gland (r = -0.32, n = 18, P = 0.455). The present results do not support the functional existence of a humoral mechanism permitting the release of adrenal catecholamines during insulin-induced hypoglycemia.

Correlation between endogenous noradrenaline and glucose released from the liver upon hepatic sympathetic nerve stimulation in anesthetized dogs.

The metabolic role of neurally released noradrenaline (NA) was studied in the liver of anesthetized dogs. Sustained stimulation with various frequencies was directly applied on the anterior plexus of hepatic nerves. Stimulation-induced changes in plasma concentrations of endogenous catecholamines in hepatic venous blood were determined in correlation with concomitant changes in those of glucose (GL). Mean basal values for hepatic venous NA, adrenaline, dopamine, and GL were 0.062, 0.022, 0.032 ng/mL, and 97.9 mg%, respectively. Among these catecholamines, NA was the only one being released significantly during stimulation. While hepatic venous NA increased rapidly during stimulation, being maximum within 3 min, hepatic venous GL increased gradually, reaching a maximum value 5 min after the onset of stimulation. A highly significant correlation (r = 0.90, P less than 0.001) was found between changes in hepatic venous NA and GL concentrations observed during stimulation at various frequencies (2-16 Hz). However, hepatic vasoconstricting responses to stimulation were not correlated with increased hepatic venous GL. An alpha-blockade with phentolamine (2 mg/kg, iv) resulted in diminished release of GL by approximately 50% (P less than 0.05) and reduced hepatic arterial vasoconstriction by approximately 47% (P less than 0.01) upon stimulation (8 Hz, 5 min), even though NA release was markedly enhanced. We conclude that in the dog, NA is the sole catecholamine released within the liver in response to direct hepatic nerve stimulation, and NA thus released mediates the hepatic glycogenolysis via alpha-adrenoceptors.