How does alcohol consumption affect the immune system?

Innate versus adaptive immunity
Alcohol and the microbiome
How alcohol affects the innate immune system. Effects of alcohol on adaptive immunity
Alcohol consumption and infection
references
in-depth reading


Although alcohol consumption is commonly associated with liver damage, moderate and chronic alcohol use can greatly affect the immune system, thus limiting the body’s ability to adequately protect itself from infection and disease.

Image Credit: New Africa / Shutterstock.com

Innate versus adaptive immunity

The immune system is typically categorized into innate and adaptive immune response systems, both of which are essential components of the body’s defense against pathogens.

Although the innate immune response is immediate, it is not specific to any particular pathogen. Some of the most prominent contributors to the innate immune response include natural killer (NK) cells, neutrophils, monocytes, macrophages, and dendritic cells (DCs).

These cells are able to recognize pathogen-associated molecular patterns (PAMPs) and pathogen recognition receptors (PRRs), which subsequently allow these cells to ingest pathogenic microorganisms. Notably, innate immune cells secrete various cytokines and chemokines that ultimately trigger an inflammatory response.

The adaptive immune system can be further divided into cellular immunity and humoral immunity. While T cells are primarily involved in cellular immunity, B cells play a major role in humoral immunity.

Alcohol and the microbiome

The first point of contact with alcohol after consumption is in the gastrointestinal (GI) tract before it is absorbed into the bloodstream. Here, alcohol can damage the epithelial cells, T cells, and neutrophils of the gastrointestinal tract, all of which can alter gut barrier function and allow intestinal microorganisms to leak into the circulation.

Within the digestive system, exposure to alcohol can also alter the number and abundance of microorganisms present within the microbiome, all of which play an important role in normal digestive function. In addition to its adverse effects on the functioning of the digestive system, the effect of alcohol on the gut microbiome can also alter the maturation and function of the immune system.

How does alcohol affect the innate immune system?

Several studies demonstrated a dose-dependent effect of alcohol in preventing both monocytes and macrophages from binding to bacterial cell wall lipopolysaccharide (LPS).

Monocytes express lead-like receptor (TLR) 4, the PRR that is often responsible for LPS recognition on the surface of Gram-negative bacteria. After binding to LPS, monocytes are activated and mature into macrophage cells that travel to the site of injury to secrete cytokines important for the inflammatory response.

Each of these events is mediated by activation of nuclear factor kappa B (NFκB), which can be inhibited by alcohol consumption and thus block the production of pro-inflammatory cytokines. in vivo Studies have confirmed that excessive intake of alcoholic beverages with a blood alcohol concentration (BAC) of approximately 0.4% can reduce the production of various inflammatory cytokines including interleukin-6 (IL-6), IL-10 and IL-12.

Image Credit: Juan Gaertner / Shutterstock.com

Image Credit: Juan Gaertner / Shutterstock.com

In addition to laboratory studies confirming the effect of alcohol consumption on the innate immune system, several studies have looked at how excessive drinking can alter plasma cytokine levels. To this end, one study analyzed the levels of IL-10, IL-6, IL-18, and tumor necrosis factor-α (TNF-α) in 25 untreated subjects seeking heavy alcohol abusers after they had consumed an alcoholic beverage. The researchers reported a significant decrease in TNF-α levels three and six hours after drinking alcohol.

Effects of alcohol on adaptive immunity

Alcohol’s effects on both humoral and humoral immunity have been documented since the early 1960s, when researchers found that alcohol use significantly reduced CD4 and CD8 T-cell counts. In the 1990s, researchers confirmed this finding and added that heavy drinkers who drank between 90 and 249 alcoholic drinks per month had significantly lower B-cell counts compared to both moderate alcohol drinkers who had between 30 and 89 drinks per month. And the light drinkers. who consumed less than ten cups each month.

Although most research has focused on the effects of heavy alcohol consumption on the immune system, many studies have also confirmed that even moderate consumption can have significant effects on the immune system. For example, one study found that women who consumed 330ml of beer for 30 days showed a significant increase in leukocytes, mature CD3.+ T cells, neutrophils, and basophils. In contrast, men who consumed a similar moderate amount of beer for the same period showed a significant increase in basophils alone.

Alcohol consumption has been shown to alter immunoglobulin (Ig) levels. To this end, heavy drinkers have been shown to show increased levels of both IgA and IgM as compared to moderate and light drinkers.

Alcohol consumption and infection

Alcohol’s ability to alter innate and adaptive immune defenses inevitably affects how the immune system of even moderate drinkers responds to infection. Indeed, alcohol use has been shown to increase the susceptibility of alcoholic drinkers to bacterial and viral infections, as well as promoting the development of several chronic viral infections, including human immunodeficiency virus (HIV) and hepatitis C.

How does alcohol affect your immune system? – BBC

Several studies have also shown that the lungs are highly susceptible to the effects of alcohol. For example, alcohol can reduce the ability of respiratory epithelium cells to remove mucus from the lungs, which can directly damage lung tissue and impair the proper functioning of the lungs over time. Although this chronic impairment of lung function may not cause any immediate symptoms, these effects can appear when a severe respiratory infection occurs.

references

  • Sarkar, D., Jung, M. K., & Wang, H. J. (2015). Alcohol and the immune system. Alcohol Research 37(2); 153-155. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4590612/.
  • Lee, MR, Abshire, KM, Varukhnik, M., et al. (2021). Effect of oral alcohol intake on plasma cytokine concentrations in heavy drinkers. Drug and alcohol addiction 225. doi: 10.1016/j.drugalcdep.2021.108771.
  • Understanding alcohol and the immune system during COVID-19 [Online]. Available from: https://adf.org.au/insights/alcohol-immune-system-covid-19/.

Further Reading

 

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