Prolonged experimental sleep disturbance affects the inflammatory resolution pathways in healthy humans

Acute partial sleep restriction does not impact arterial function in young and healthy humans

Habitual short sleep durations are associated with several cardiovascular diseases. Experimental research generally supports these findings as metrics of arterial function are impaired after complete deprivation of sleep and after longer periods of partial sleep restriction. The acute influence of a single instance of partial sleep restriction (PSR), however, has not been defined. We evaluated arterial structure and function among 32 university-aged participants on two occasions: once after normal habitual sleep (NS), and again the morning after an acute partial sleep restriction (PSR) intervention involving only 3 h of sleep for a single night. Endothelial function was measured using ultrasonography at the brachial artery via flow-mediated dilatation (FMD), and a ramp peak oxygen uptake test was used to evaluate cardiorespiratory fitness. Blood samples were collected from a subset of participants to investigate the influence of circulatory factors on cellular mechanisms implicated in endothelial function. Sleep duration was lower after a night of PSR compared to NS (P < 0.001); however, there were no appreciable differences in any haemodynamic outcome between conditions. FMD was not different between NS and PSR (NS: 6.5 ± 2.9%; PSR: 6.3 ± 2.9%; P = 0.668), and cardiorespiratory fitness did not moderate the haemodynamic response to PSR (all P > 0.05). Ex vivo cell culture results aligned with in vivo data, showing that acute PSR does not alter intracellular processes involved in endothelial function. No differences in arterial structure or function were observed between NS and acute PSR in healthy and young participants, and cardiorespiratory fitness does not modulate the arterial response to acute sleep restriction.

Effects of low-dose acetylsalicylic acid on the inflammatory response to experimental sleep restriction in healthy humans

BACKGROUND

Sleep deficiencies, such as manifested in short sleep duration or insomnia symptoms, are known to increase the risk for multiple disease conditions involving immunopathology. Inflammation is hypothesized to be a mechanism through which deficient sleep acts as a risk factor for these conditions. Thus, one potential way to mitigate negative health consequences associated with deficient sleep is to target inflammation. Few interventional sleep studies investigated whether improving sleep affects inflammatory processes, but results suggest that complementary approaches may be necessary to target inflammation associated with sleep deficiencies. We investigated whether targeting inflammation through low-dose acetylsalicylic acid (ASA, i.e., aspirin) is able to blunt the inflammatory response to experimental sleep restriction.

METHODS

46 healthy participants (19F/27M, age range 19-63 years) were studied in a double-blind randomized placebo-controlled crossover trial with three protocols each consisting of a 14-day at-home monitoring phase followed by an 11-day (10-night) in-laboratory stay (sleep restriction/ASA, sleep restriction/placebo, control sleep/placebo). In the sleep restriction/ASA condition, participants took low-dose ASA (81 mg/day) daily in the evening (22:00) during the at-home phase and the subsequent in-laboratory stay. In the sleep restriction/placebo and control sleep/placebo conditions, participants took placebo daily. Each in-laboratory stay started with 2 nights with a sleep opportunity of 8 h/night (23:00-07:00) for adaptation and baseline measurements. Under the two sleep restriction conditions, participants were exposed to 5 nights of sleep restricted to a sleep opportunity of 4 h/night (03:00-07:00) followed by 3 nights of recovery sleep with a sleep opportunity of 8 h/night. Under the control sleep condition, participants had a sleep opportunity of 8 h/night throughout the in-laboratory stay. During each in-laboratory stay, participants had 3 days of intensive monitoring (at baseline, 5th day of sleep restriction/control sleep, and 2nd day of recovery sleep). Variables, including pro-inflammatory immune cell function, C-reactive protein (CRP), and actigraphy-estimated measures of sleep, were analyzed using generalized linear mixed models.

RESULTS

Low-dose ASA administration reduced the interleukin (IL)-6 expression in LPS-stimulated monocytes (p<0.05 for condition*day) and reduced serum CRP levels (p<0.01 for condition) after 5 nights of sleep restriction compared to placebo administration in the sleep restriction condition. Low-dose ASA also reduced the amount of cyclooxygenase (COX)-1/COX-2 double positive cells among LPS-stimulated monocytes after 2 nights of recovery sleep following 5 nights of sleep restriction compared to placebo (p<0.05 for condition). Low-dose ASA further decreased wake after sleep onset (WASO) and increased sleep efficiency (SE) during the first 2 nights of recovery sleep (p<0.001 for condition and condition*day). Baseline comparisons revealed no differences between conditions for all of the investigated variables (p>0.05 for condition).

CONCLUSION

This study shows that inflammatory responses to sleep restriction can be reduced by preemptive administration of low-dose ASA. This finding may open new therapeutic approaches to prevent or control inflammation and its consequences in those experiencing sleep deficiencies.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03377543.

Lipid mediators in neutrophil biology: inflammation, resolution and beyond

PURPOSE OF REVIEW

Acute inflammation is the body's first defense in response to pathogens or injury. Failure to efficiently resolve the inflammatory insult can severely affect tissue homeostasis, leading to chronic inflammation. Neutrophils play a pivotal role in eradicating infectious pathogens, orchestrating the initiation and resolution of acute inflammation, and maintaining physiological functions. The resolution of inflammation is a highly orchestrated biochemical process, partially modulated by a novel class of endogenous lipid mediators known as specialized pro-resolving mediators (SPMs). SPMs mediate their potent bioactions via activating specific cell-surface G protein-coupled receptors (GPCR).

RECENT FINDINGS

This review focuses on recent advances in understanding the multifaceted functions of SPMs, detailing their roles in expediting neutrophil apoptosis, promoting clearance by macrophages, regulating their excessive infiltration at inflammation sites, orchestrating bone marrow deployment, also enhances neutrophil phagocytosis and tissue repair mechanisms under both physiological and pathological conditions. We also focus on the novel role of SPMs in regulating bone marrow neutrophil functions, differentiation, and highlight open questions about SPMs' functions in neutrophil heterogeneity.

SUMMARY

SPMs play a pivotal role in mitigating excessive neutrophil infiltration and hyperactivity within pathological milieus, notably in conditions such as sepsis, cardiovascular disease, ischemic events, and cancer. This significant function highlights SPMs as promising therapeutic agents in the management of both acute and chronic inflammatory disorders.

Specialized pro-resolving mediators in vascular inflammation and atherosclerotic cardiovascular disease

Timely resolution of the acute inflammatory response (or inflammation resolution) is an active, highly coordinated process that is essential to optimal health. Inflammation resolution is regulated by specific endogenous signalling molecules that function as 'stop signals' to terminate the inflammatory response when it is no longer needed; to actively promote healing, regeneration and tissue repair; and to limit pain. Specialized pro-resolving mediators are a superfamily of signalling molecules that initiate anti-inflammatory and pro-resolving actions. Without an effective and timely resolution response, inflammation can become chronic, a pathological state that is associated with many widely occurring human diseases, including atherosclerotic cardiovascular disease. Uncovering the mechanisms of inflammation resolution failure in cardiovascular diseases and identifying useful biomarkers for non-resolving inflammation are unmet needs. In this Review, we discuss the accumulating evidence that supports the role of non-resolving inflammation in atherosclerosis and the use of specialized pro-resolving mediators as therapeutic tools for the treatment of atherosclerotic cardiovascular disease. We highlight open questions about therapeutic strategies and mechanisms of disease to provide a framework for future studies on the prevention and treatment of atherosclerosis.