Acute immunomodulatory effects of binge alcohol ingestion

Abstract

Background: Blood alcohol is present in a third of trauma patients and has been associated with organ dysfunction. In both human studies and in animal models, it is clear that alcohol intoxication exerts immunomodulatory effects several hours to days after exposure, when blood alcohol is no longer detectable. The early immunomodulatory effects of alcohol while blood alcohol is still elevated are not well understood.

Methods: Human volunteers achieved binge alcohol intoxication after high-dose alcohol consumption. Blood was collected for analysis prior to alcohol ingestion, and 20 min, 2 h, and 5 h after alcohol ingestion. Flow cytometry was performed on isolated peripheral blood mononuclear cells, and cytokine generation in whole blood was measured by enzyme-linked immunosorbent assay (ELISA) after 24-h stimulation with lipopolysaccharide (LPS) and phytohemagglutinin-M (PHA) stimulation.

Results: An early pro-inflammatory state was evident at 20 min when blood alcohol levels were ∼130 mg/dL, which was characterized by an increase in total circulating leukocytes, monocytes, and natural killer cells. During this time, a transient increase in LPS-induced tumor necrosis factor (TNF)-α levels and enhanced LPS sensitivity occurred. At 2 and 5 h post-alcohol binge, an anti-inflammatory state was shown with reduced numbers of circulating monocytes and natural killer cells, attenuated LPS-induced interleukin (IL)-1β levels, and a trend toward increased interleukin (IL)-10 levels.

Conclusions: A single episode of binge alcohol intoxication exerted effects on the immune system that caused an early and transient pro-inflammatory state followed by an anti-inflammatory state.

Keywords: Antigen-presenting cells; Binge drinking; Cytokines; Ethanol; Innate immunity; Peripheral blood mononuclear cells.

Figure 1. Mean BrAC Levels Over Six Hours

Breathalyzer levels from pre-alcohol to six hours post-alcohol ingestion with 20 minute post-alcohol peak and subsequent 30 minute recordings until discharge from General Clinical Research Center when BrAC reached ≤0.03%. Average clearance of 17.8mg/dL/hr.

Figure 2. Change in Monocyte Characteristics Over Time

A) The portion of PBMCs comprised of CD14+ monocytes exhibited a 31.3% drop from pre-alcohol levels at 2 hours post-alcohol intoxication (7.2% at 2 hours vs. 10.3% pre-alcohol, p<0.001*). B) The percent of PBMCs with surface marker profile CD14−/CD11c+, characteristic of monocytes differentiated into dendritic cells, increased 43.2% at 2 hours post-alcohol (11.3% vs. 8.6% pre-alcohol, p=0.006*) and returned to pre-alcohol levels at 5 hours (p=0.43).

Figure 3. Representative Dot Plots Across Time

Representative dot plot from a single subjet. CD14 and CD11c expression are shown in A) PBMC population gated cells and in B) monocyte population gated cells. Both groups demonstrate a decrease in CD14 expression at 2 hours post-alcohol ingestion.

Figure 4. Cytokine Levels After LPS Stimulation (100 ng/mL)

A and B) LPS stimulated pro-inflammaotry (TNF-α and IL-1β) cytokine expression changed over time from pre-alcohol up to 5 hours post-alcohol intoxication. More notably, IL-1β was signficantly decreased by 2 hours (p<0.001*) and 5 hours (p=0.007*) when compared to pre-alcohol levels. C and D) LPS stimulated anti-inflammaotry (IL-10 and IL-1RA) cytokine levels changed over time from pre-alcohol up to 5 hours post-alcohol ingestion. More notably, IL-1RA increased signficiantly by 20 minutes when compared to pre-alcohol levels (p<0.001*) but returned to baseline by 5 hours and IL-10 was overall increased expression by 5 hours. Stimulation of samples occurred at LPS concentration of 100 ng/mL. The stated p-value across time for each cytokine was produced by repeated measures ANOVA.