Treatment with TUG891, a free fatty acid receptor 4 agonist, restores adipose tissue metabolic dysfunction following chronic sleep fragmentation in mice.

BACKGROUND: Sleep fragmentation (SF), a frequent occurrence in multiple sleep and other diseases leads to increased food intake and insulin resistance via increased macrophage activation and inflammation in visceral white adipose tissue (VWAT). Free fatty acid receptor 4 (FFA4) is reduced in pediatric sleep apnea patients and FFA4 agonists have been proposed in the treatment of obesity and metabolic dysfunction. METHODS: Male mice were subjected to SF exposures for 6 weeks, and treated during the last 2 weeks with either TUG891, a potent and selective FFA4 agonist, or vehicle (Veh). Glucose and insulin tolerance tests and VWAT insulin sensitivity tests were conducted (phosphorylated Akt/total Akt), along with flow cytometric assessments of VWAT macrophage polarity, and T-cell lymphocyte subsets. RESULTS: SF-TUG891 mice showed reduction in food consumption, weight gain and VWAT mass. Furthermore, TUG891 treatment ameliorated glucose tolerance test and insulin tolerance test responses and increased VWAT p-Akt/Akt responses to insulin. Increases in M1/M2 macrophages and decreased Treg counts in VWAT associated with SF were markedly improved by TUG891, and VWAT macrophages from TUG891-treated mice had markedly attenuated insulin resistance effects on naïve cultured adipocytes. CONCLUSIONS: Treatment with an FFA4 agonist reverses SF-induced food intake increases and gains in body weight, and significantly attenuates VWAT inflammation and insulin resistance. Thus, interventional dietary or pharmaceutical strategies aimed at increasing FFA4 activity may serve as potentially useful adjunctive therapies for sleep disorders accompanied by metabolic morbidity.

Effect of resveratrol on visceral white adipose tissue inflammation and insulin sensitivity in a mouse model of sleep apnea.

BACKGROUND: Sleep fragmentation (SF) increases food intake and the risk of obesity, and recruits macrophages to visceral white adipose tissue (VWAT) promoting tissue inflammation and insulin resistance. Administration of resveratrol (Resv) has been associated with significant improvements in high-fat diet-induced obesity, inflammation and insulin resistance. METHODS: Male mice were subjected to SF or sleep control conditions for 8 weeks, and treated with either Resv or vehicle (Veh). Fasting plasma levels of glucose, insulin and leptin were obtained and VWAT insulin sensitivity tests were performed (phosphorylated AKT/total AKT), along with flow-cytometric assessments for VWAT macrophages (M1 and M2) and T-cell lymphocytes (CD4+, CD8+ and T regulatory cell (Treg)). RESULTS: SF-Veh and SF-Resv mice showed increased food consumption and weight gain. However, although SF-Veh mice exhibited increased fasting insulin and leptin levels, and reduced VWAT p-AKT/AKT responses to insulin, such alterations were abrogated in SF-Resv-treated mice. Increases in M1, reduced M2 counts and increased tumor necrosis factor-α release emerged in SF-Veh macrophages compared with all other three groups. Similarly, increased CD8+ and reduced Treg lymphocyte counts were apparent in SF-Veh. CONCLUSIONS: Resveratrol does not reverse the SF-induced increases in food intake and weight gain, but markedly attenuates VWAT inflammation and insulin resistance, thereby providing a potentially useful adjunctive therapy in the context of sleep disorders manifesting metabolic morbidity.

Upper airway collapse and reopening induce inflammation in a sleep apnoea model.

The upper airway of obstructive sleep apnoea patients is subjected to recurrent negative pressure swings promoting its collapse and reopening. The aim of the present study was to ascertain whether this mechanical stress induces upper airway inflammation in a rat model. The upper airway of Sprague-Dawley rats was subjected to a periodic pattern of recurrent negative (-40 cmH2O, 1 s) and positive (4 cmH2O, 2 s) pressures inducing collapse and reopening for 5 h. Rats that were instrumented but not subjected to negative pressure swings were used as controls. The gene expression of the pro-inflammatory biomarkers macrophage inflammatory protein (MIP)-2, tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and P-selectin in the soft palate and larynx tissues was assessed by real-time PCR. A marked overexpression of MIP-2, TNF-alpha, IL-1beta and P-selectin (approximately 40-, 24-, 47- and 7-fold greater than controls, respectively) was observed in the larynx tissue; similar results were found in the soft palate tissue (approximately 14-, 7-, 35- and 11-fold greater than controls, respectively). Recurrent upper airway collapse and reopening mimicking those experienced by obstructive sleep apnoea patients triggered an early local inflammatory process. These results could explain the inflammation observed in the upper airway of obstructive sleep apnoea patients.

Early effects of continuous positive airway pressure in a rodent model of allergic rhinitis.

BACKGROUND: Continuous positive airway pressure (CPAP) is the most commonly used treatment in obstructive sleep apnea. In a previous rat model study, we demonstrated that nasal CPAP induces early rhinitis expressed by nasal neutrophil extravasation. Here we hypothesized that nasal CPAP would worsen nasal inflammation on a previously inflamed mucosa. The objective of this study was to evaluate the early nasal CPAP effects of allergic rhinitis (AR) in a rodent model. METHODS: Twenty Sprague-Dawley rats were sensitized with intraperitoneal ovalbumin (OVA). Nasal inflammation was induced by the administration of intranasal OVA during consecutive days. The same procedure was performed in 20 control rats treated with saline solution. The allergic (AR) and non-allergic (NAR) rats were then randomized to nasal CPAP at 10 cm H2O for five hours or to sham CPAP. The degree of nasal inflammation was assessed by evaluating the percentage of neutrophils, eosinophils, basophils, and lymphocytes in the nasal mucosa. An unpaired Mann-Whitney test was used to analyze differences between groups. RESULTS: The greatest inflammation was observed in the group of AR without CPAP (1.24% ± 0.94%), followed by NAR with CPAP (0.64% ± 0.30%), AR with CPAP (0.64% ± 0.40%), and NAR without CPAP (0.21% ± 0.29%). CONCLUSIONS: Administration of nasal CPAP or allergy sensitization can produce, individually, neutrophil extravasation on the nasal mucosa of a rat model. The application of both stimuli is not responsible for increased inflammation. Therefore, this study suggests that rhinitis is not a major limitation for CPAP administration.

Cross-reactivity between antigens of Anisakis simplex s.l. and other ascarid nematodes.

A study of the cross-reactivity among somatic and excretory-secretory antigens of the third stage larvae of Anisakis simplex s.l. and somatic antigens of other ascarid nematodes (Ascaris lumbricoides, A. suum, Toxocara canis, Anisakis physeteris, Hysterothylacium aduncum and H. fabri) was carried out by immunoblotting. It was revealed a high degree of cross-reactivity among ascarids in the 30 and > 212 kDa range by using sera against somatic and excretory-secretory antigens of A. simplex s.l. It has been revealed also specific components of the Anisakis genus (< 7.2, 9, 19 and 25 kDa) that will be interesting in diagnosis.