Impaired Bactericidal Activity and Host Resistance toListeria monocytogenesandBorrelia burgdorferiin Rats Administered an Acute Oral Regimen of Ethanol

Abstract

A rat model was used to examine how ethanol ingestion may interfere with antimicrobial immunity both in vitro and in vivo. Nonimmune Long-Evans rats were given a short-course treatment orally with excessive amounts of ethanol. Their spleens were removed at the time of sacrifice, and separate spleen cell suspensions were prepared and tested in vitro for their ability to kill two bacterial pathogens, Listeria monocytogenes and Borrelia burgdorferi. After the bacteria were mixed separately with various concentrations of spleen cells, it was found that spleen cells from the ethanol-treated rats killed fewer bacteria than matching pair-fed controls, based on counts of the number of cultured CFU (for Listeria) or based on microscopic examination (for Borrelia). For the in vivo studies, ethanol-treated and control rats were infected intraperitoneally with Listeria, and then, 1 to 3 days later, they were assessed for systemic infection based on the numbers of organisms present in their livers and spleens. Numbers of bacterial CFU for both organs were significantly higher in the group fed ethanol for the first 2 days after listerial challenge. These results support the concept that acute exposure to high levels of ethanol can impair host defense mechanisms, especially those expressed at the cellular level, which could lead to increased susceptibility to certain types of infections.

Chronic ethanol induces inhibition of antigen-specific CD8+ but not CD4+ immunodominant T cell responses followingListeria monocytogenesinoculation

“…The early CD8 ϩ T cell response to LM has been shown to be critical for development of sterilizing immunity [30]. Previous studies with virulent LM in ethanol-administered mice and rats consistently have shown increased numbers of bacteria in different organs and the inability to clear the infection compared with controls [7,10,[31][32][33]. In the current work, for evaluation of CD8 ϩ T cell responses, we have used an attenuated strain of LM, DPL 1942, which is unable to nucleate cellular actin (⌬actA) and is cleared within 2 days by waterand ethanol-administered mice.…”