However, the pre-treatment of cells with specific metabolites prior to LF82 infection reversed this, with l-tryptophan (2.57-fold, P=0.0028), butyrate (3.10-fold, P=0.0007), TMA (2.42-fold, P=0.0067), UDCA (2.19-fold, P=0.0001) and benzoate (2.55-fold, P=0.0027), each significantly increasing ZO-1 levels compared to infected cells without pre-treatment (Fig. 1b). This evidence concerns the gene TJP1 and infection.