Objective: Granulocytopenia frequently occurs in alcohol abusers with severe bacterial infection, which strongly correlates with poor clinical outcome. Knowledge of the molecular mechanisms underlying the granulopoietic response to bacterial infection remains limited. This study investigated the involvement of stem cell antigen-1 expression by granulocyte lineage-committed progenitors in the granulopoietic response to septicemia and how alcohol affected this response.
Design: : Laboratory investigation.
Setting: University laboratory.
Subjects: Male Balb/c mice.
Interventions: Thirty mins after intraperitoneal injection of alcohol (20% ethanol in saline at 5 g of ethanol/kg) or saline, mice received an intravenous Escherichia coli challenge.
Measurements and main results: E. coli septicemia activated stem cell antigen-1 expression by marrow immature granulocyte differentiation antigen-1 precursors which correlated with an increase in proliferation, granulocyte macrophage colony-forming unit production, and expansion of this granulopoietic precursor cell pool. Acute alcohol treatment suppressed stem cell antigen-1 activation and inhibited the infection-induced increases in proliferation, granulocyte macrophage colony-forming unit production, and expansion the of immature granulocyte differentiation antigen-1 precursor cell population. Consequently, recovery of the marrow mature granulocyte differentiation antigen-1 cell population after E. coli challenge was impaired. Stem cell antigen-1 was induced in sorted granulocyte differentiation antigen-1, stem cell antigen-1' cells by lipopolysaccharide-stimulated C-Jun kinase activation that was also inhibited by alcohol. Furthermore, stem cell antigen-1 knockout mice failed to expand the marrow immature granulocyte differentiation antigen-1 cell pool and demonstrated fewer newly produced granulocytes in the circulation after the E. coli challenge.
Conclusions: Alcohol suppresses the stem cell antigen-1 response in granulocyte lineage-committed precursors and restricts granulocyte production during septicemia, which may serve as a novel mechanism underlying impaired host defense in alcohol abusers.