<i>Lupinus mutabilis</i> Edible Beans Protect against Bacterial Infection in Uroepithelial Cells

Abstract

<i>Lupinus mutabilis</i> is a South American herb with edible beans, known to reduce serum glucose levels in diabetic patients. Furthermore, <i>L. mutabilis</i> contains phytochemicals known to decrease bacterial load. Based on the increased urinary tract infections experienced among patients with diabetes, we investigated the effect of <i>L. mutabilis</i> on bladder epithelial cells in the protection of <i>E. coli</i> infection during normal and high glucose concentrations. We did not observe any direct antibacterial effect by <i>L. mutabilis</i> extract. Instead we observed an influence on the host cells, with indirect impact on bacteria and their possibility of causing infection. <i>L. mutabilis</i> extract decreased adhesion to bladder epithelial cells of uropathogenic bacteria, including drug-resistant strains. Moreover, uroplakin1a, involved in adhesion, was downregulated while the antimicrobial peptide RNase 7 was upregulated in <i>L. mutabilis</i> treated cells irrespectively of glucose concentration. This supports an early effect fighting bacteria. Additionally, <i>L. mutabilis</i> prevented bacterial biofilm formation, which is used by bacteria to evade the immune system and antibiotics. In summary, <i>L. mutabilis</i> protects against bacterial infection in uroepithelial cells by preventing adhesion through alteration of the cell surface, increasing antimicrobial peptide expression, and reducing biofilm formation. Together, this promotes bacterial clearance, suggesting that <i>L. mutabilis</i> as extract or as a dietary item can contribute to the prevention of urinary tract infections, which is of importance in an era of increasing antibiotic resistance.