GSE131382
Impact of Orthosiphon stamineus aqueous leave extract on global gene expression of uropathogenic Escherichia coli
Specific recognition and bacterial adhesion to host cells by uropathogenic E. coli (UPEC) are the first steps towards infection of epithelial tissue of the human urogenital system. Therefore, targeting of UPEC virulence factors, relevant for adhesion, is a promising approach for prevention of recurrent urinary tract infections (UTI). A fully characterized plant-derived aqueous extract from the leaves of Orthosiphon stamineus (OWE), a plant traditionally used in clinical practice in Europe and Asia for UTI, has been shown to exert strong antiadhesive effects under in vitro and in vivo conditions. For improved understanding of the underlying mechanisms transcriptome analysis of OWE-treated UPEC strain UTI89 by Illumina sequencing and cross-validation of these data by qPCR indicated significant down-regulation of bacterial adhesins (curli, type 1-, F1C- and P fimbriae) and of the chaperone-mediated protein folding/unfolding and pilus assembly process; in contrast flagellar and motility-related genes  were upregulated. We conclude that OWE transforms the sessile lifestyle of bacteria into a motile one and therefore disables bacterial attachment to the host cell. Additionally, the extract inhibited gene expression of multiple iron acquisition systems (Ent, Fep, Feo, Fhu, Chu, Sit, Ybt) concomitant with an upregulated expression of the ferric uptake regulator (Fur) repressor. The present study explains the antiadhesive and antiinfective effect of the plant extract by pinpointing specific biochemical and molecular targets. Overall design: Examination of the transcriptome of uropathogenic E. coli after 2 h incubation time with OWE in pooled human urine (one replicate) in comparison to 2 h incubation in pooled human urine (one replicate).