Intracellular Invasion and Killing Assay to Investigate the Effects of Binge Alcohol Toxicity in Murine Alveolar Macrophages

Abstract

Alcohol consumption has diverse and well-documented effects on the human immune system and its ability to defend against infective agents. While pulmonary related infections can occur in healthy humans, binge alcohol use is recognized as a major health risk factor (Nelson et al., 1991). Although binge alcohol consumption has been considered as a risk factor for the development of pulmonary infections, no experimental studies have investigated the outcomes of a single binge alcohol exposure during infection. A key assay to assess the effects of a single binge alcohol exposure on the interactions between bacteria and alveolar macrophage is a binge alcohol intracellular invasion and killing assay. MH-S alveolar macrophages (AMs) are exposed to a single binge alcohol dose prior to infection for 3 h. The macrophage monolayer is then infected to allow for engulfment, followed by removal of extracellular bacteria to assess the intracellular killing capacity of infected macrophages over time. We have utilized this assay to demonstrate that low alcohol exposure significantly suppressed the uptake and killing of less virulent Burkholderia thailandensis (B. thailandensis) by AMs. More recently we found that activated AMs with interferon (IFN)-γ incubated in alcohol (0.08%) for 3 h prior to infection showed significantly lower bacterial uptake at 2 and 8 h post infection, which lead to B. thailandensis survival and a ~2.5-fold replication increase compared to controls (Jimenez et al., 2017). These results provide insights into binge alcohol consumption, a culturally prevalent risk factor, as a predisposing factor for pulmonary bacterial infections. This assay can be adapted to other bacterial species and host cell types to assess tissue specific effects of alcohol during infection.