Plasma cytokine levels in patients with chronic alcohol overconsumption: Relations to gut microbiota markers and clinical correlates.

ABSTRACT

BACKGROUND: Alcohol-related morbidity may involve changes in the gut microbiota and immune dysregulation. We have previously demonstrated alterations in gut microbiota composition and functions in patients with alcohol overconsumption, and now aimed to investigate possible associations between cytokine levels, gut microbiota, and clinical symptoms. METHODS: We included hospital inpatients with a history of chronic alcohol overconsumption. For comparison, we included control patients with a low alcohol intake. Cytokine levels (TGF-ß1, TNF-α, IL-10, IL-8, IL-6, IFN-γ, MCP-1, IL-1RA, IL-1ß, and IL-17) were determined using a customized V-plex assay. We then examined associations of cytokine levels with the abundance of Proteobacteria and Faecalibacterium, percentage of the short-chain fatty acid butyrate, psychiatric symptoms (Hospital Anxiety and Depression Scale), and biochemical liver variables. RESULTS: We included 28 patients with alcohol overconsumption (79% men), and 25 control patients (72% men). Patients with alcohol overconsumption had higher levels of IL-6 (p = 0.002), IFN-γ (p = 0.018), and MCP-1 (p = 0.006), and lower levels of TGF-ß1 (p = 0.017) compared with control patients. Inverse correlations were found between Proteobacteria abundance and TNF-α (Rs = -0.55, p = 0.02) and IL-8 (Rs = -0.58, p = 0.014), and between Faecalibacterium and MCP-1 levels (Rs = -0.56, p = 0.02) in the control patients, but not in patients with alcohol overconsumption. Patients with alcohol overconsumption reported more psychiatric symptoms, and these symptoms were inversely correlated with IL-10 levels. There were positive correlations between several of the assessed cytokines and biochemical liver variables, and negative correlations between cytokine levels and albumin. CONCLUSION: Patients with alcohol overconsumption had a cytokine profile suggestive of increased systemic inflammatory activity, with higher levels of pro-inflammatory cytokines (IL-6, IFN-γ, and MCP-1) and lower levels of anti-inflammatory cytokines (TGF-ß1). The findings may represent a link between alcohol use and alcohol-related morbidity.