Sleep deprivation attenuates inflammatory responses and ischemic cell death

Abstract

Although the biological function of sleep remains uncertain, the consequences of sleep deprivation are well-described and are reported to be detrimental to cognitive function and affective well-being. Sleep deprivation also is strongly associated with elevated risk factors for cardiovascular disease. We used a mouse model of cardiac arrest/cardiopulmonary resuscitation to test the hypothesis that acute sleep deprivation would exacerbate neuroinflammation and neurodegeneration after global ischemia. The resulting data led to a rejection of our hypothesis that sleep deprivation is necessarily detrimental. Indeed, acute sleep deprivation (ASD) was associated with a reduction in ischemia-induced interleukin 1beta (IL-1beta) gene expression and attenuation of neuronal damage in the hippocampus. Further, sleep deprivation increased gene expression of two anti-inflammatory cytokines, IL-6 and IL-10 that are associated with improved ischemic outcome. To determine whether the anti-inflammatory properties of ASD were specific to ischemia, mice were treated systemically with lipopolysaccharide (LPS), a potent inflammogen. Acute sleep deprivation attenuated the central and peripheral increase in tumor necrosis factor-alpha (TNFalpha) and increased IL-10 expression. Together, the ischemia and LPS data suggest that, ASD produces an anti-inflammatory bias that could be exploited to improve medical procedures that are compromised by inflammation.

Figure 1. Timeline of experimental procedures

Timeline of experimental events in the cardiac arrest (A) and LPS (B) studies.

Figure 2. Sleep deprivation does not alter cardiac arrest-induced mortality

Normothermic cardiac arrest induced significant mortality but this effect was not altered by prior sleep deprivation.

Figure 3. Cell death and inflammatory responses are inhibited by prior sleep deprivation

Representative Fluoro-Jade C stained sections of the CA1 field of the hippocampus following CA/CPR in A) standard housed hypothermic mice, B) ASD hypothermic mice, C) standard housed normothermic animals and D) ASD normothermic animals; scale bar = 200μm. E) Fluoro-Jade positive cells in the CA1 field and F) summed across the whole hippocampal formation. The cell death data are displayed in the figure are untransformed but statistical testing was conducted on log-transformed data. RT-PCR analyses of hippocampal mRNA 24 hours post reperfusion of the cytokines G) interleukin-1β (IL-1β), H )tumor necrosis factor alpha (TNFα), I) interleukin-6 (IL-6) and J) interleukin 10 (IL-10). + Significantly different from hypothermic mice in the same sleep condition. * Significantly different from standard housed mice. Differences were considered significant if p<0.05. ASD, acute sleep deprivation. All data are presented as means ( ± SEM). N=6–7 animal/group for histology and 5–6/group for mRNA analysis.

Figure 4. Acute sleep deprivation antagonizes LPS induced cytokine expression in the CNS

RT-PCR analysis of forebrain homogenates 4 hours after lipopolysaccharide (LPS; 400μg/kg) or vehicle treatment administration A) interleukin-1β (IL-1β), B) tumor necrosis factor alpha (TNFα), C) interleukin-6 (I-6) and D) interleukin 10 (IL-10). All gene expression data are presented after relativization to 18s rRNA expression. Differences were considered significant if p<0.05. ASD, acute sleep deprivation. All data are presented as means (± SEM). N=5–6/group.

Figure 5. Acute sleep deprivation abrogates LPS induced cytokine production in the periphery

RT-PCR analysis of spleen homogenates four hours after LPS (400μg/kg) or vehicle administration on A) interleukin-1β (IL-1β), B) tumor necrosis factor α (TNFα) and C) interleukin-6 (IL-6). TNFα protein concentrations measured by ELISA in D) splenic lysates and E) peripheral blood. F) circulating corticosterone concentrations at the four hour post-LPS time point + Significantly different from hypothermic mice in the same sleep condition. * Significantly different from standard housed mice. Differences were considered significant if p<0.05. ASD, acute sleep deprivation. All data are presented as means (± SEM). N=5–6/group.

Figure 6. Glucocorticoid receptor antagonism during sleep deprivation does not alter ASD-induced derangement of central and peripheral inflammatory responses

Mice treated with RU-486 every 12 hours during the sleep deprivation period and then injected with either LPS (400μg/kg) or vehicle and tissue collected A) forebrain tumor necrosis factor α gene expression, B) splenic tumor necrosis factor α protein concentrations measured by ELISA and C) circulating corticosterone concentrations. N=5–6/group.