Synergistic effects of Lactiplantibacillus plantarum GUANKE and Tryptophan on alleviating lung injury through the AHR/STAT3/IL-10 pathway in influenza infection mice.

Influenza is an acute viral respiratory infection that causes severe morbidity and mortality. Some trials have shown that Lactiplantibacillus plantarum strains and its metabolites can prevent respiratory infections. Tryptophan (Trp) is a commonly used dietary supplement with well-documented health benefits. The objective of this study was to investigate the combined antiviral effect of L. plantarum GUANKE (GUANKE) and Trp. We found that combined supplementation of GUANKE and Trp could more significantly improve lung pathological injury by regulating the levels of cytokines and restoring epithelial barrier function compared to either alone. In the in vitro experiments, we confirmed that GUANKE could metabolize Trp to produce more beneficial metabolite indole-3-lactic acid (ILA), which activates the AHR/STAT3/IL-10 pathway. Moreover, further mechanistic study indicated that the AHR/STAT3/IL-10 protein interactions were promoted by ILA in TNF-α-treated lung epithelial cells A549. This study presents a novel perspective on the synergistic effects of dietary supplement Trp combined with the probiotic GUANKE in alleviating influenza infection.