Extract of Clinopodium bolivianum protects against E. coli invasion of uroepithelial cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Clinopodium bolivianum is a South American plant with anti-inflammatory and anti-infective activities. The increasing antibiotic resistance urges for alternative therapy. Based on its use in traditional medicine, we investigated the effect of C. bolivianum on the ability to defend bladder epithelial cells from E. coli infection.

MATERIALS AND METHODS: The extract was analyzed by LC-MS. Bladder epithelial cell lines T24 and 5637 and uropathogenic E. coli No. 12, its isogenic mutant WE16 csgBA bscA::Cm and CFT073 were used to investigate the effect of C. bolivianum on uroepithelial infection. Bacterial adherence and invasion to cells treated with C. bolivianum were analyzed. Expression of uroplakin 1a, β1 integrin, caveolin-1, IL-8 and antimicrobial peptides in response to C. bolivianum treatment was assessed using RT-PCR. Protein expression was confirmed by Western blot analysis or ELISA. The antimicrobial effects of C. bolivianum on bacteria and fungus were investigated using minimum inhibitory concentration. Furthermore, the formation of biofilm was investigated with crystal violet assay.

RESULTS: C. bolivianum extract consisted of more than 70 different types of phytochemicals including sugars and phenolic compounds. The extract decreased the uroplakin 1a expression and E. coli adhesion and invasion of uroepithelial cells while up-regulated caveolin-1. In uninfected C. bolivianum treated cells, IL-8 was lower than in non-treated cells. In infected cells, however, no difference was observed between treated and non-treated cells. Further, C. bolivianum treatment reduced uropathogenic E. coli (UPEC) biofilms but did not inhibit bacterial growth.

CONCLUSIONS: Our results show that C. bolivianum has a protective role on bladder epithelial cells against UPEC infection by decreasing the bacterial adhesion, invasion and biofilm formation.