Probiotic Bifidobacterium longum subsp. longum Protects against Cigarette Smoke-Induced Inflammation in Mice

Abstract

<i>Bifidobacterium</i> are prominent gut commensals that produce the short-chain fatty acid (SCFA) acetate, and they are often used as probiotics. Connections between the gut and the lung, termed the gut-lung axis, are regulated by the microbiome. The gut-lung axis is increasingly implicated in cigarette smoke-induced diseases, and cigarette smoke exposure has been associated with depletion of <i>Bifidobacterium</i> species. In this study, we assessed the impact of acetate-producing <i>Bifidobacterium longum</i> subsp. <i>longum</i> (WT) and a mutant strain with an impaired acetate production capacity (MUT) on cigarette smoke-induced inflammation. The mice were treated with WT or MUT <i>B. longum</i> subsp. <i>longum</i> and exposed to cigarette smoke for 8 weeks before assessments of lung inflammation, lung tissue gene expression and cecal SCFAs were performed. Both strains of <i>B. longum</i> subsp. <i>longum</i> reduced lung inflammation, inflammatory cytokine expression and adhesion factor expression and alleviated cigarette smoke-induced depletion in caecum butyrate. Thus, the probiotic administration of <i>B. longum</i> subsp. <i>longum,</i> irrespective of its acetate-producing capacity, alleviated cigarette smoke-induced inflammation and the depletion of cecal butyrate levels.