High Mobility Group Nucleosomal Binding Domain 2 Protein Protects Bladder Epithelial Cells from Klebsiella pneumoniae Invasion

Due to the predominance of multiple-antibiotic-resistant Klebsiella pneumoniae strains, the search for new approaches for the prevention of K. pneumoniae infections is now under intensive investigation. The objective of the present study was to investigate the effects of high mobility group nucleosomal binding domain 2 (HMGN2) protein, which acts on the bladder epithelial cells T 24, on the invasion of K. pneumoniae 03183 and explore its possible mechanisms. Pretreatment with HMGN2 significantly reduced K. pneumoniae 03183 uptake by T 24 cells. In T 24 cells, there were no detectable cytotoxic effects of HMGN2 at any concentration between 32 and 256 μg/ml after 2 h incubation. HMGN2 exhibited no appreciable antibacterial activity against K. pneumoniae 03183. Fluorescence microscopy and flow cytometry analysis revealed that HMGN2 blocked K. pneumoniae 03183-induced actin polymerization. K. pneumoniae 03183-induced phosphorylation of extracellular signal-regulated kinase (ERK) and cofilin were prevented by pretreatment with HMGN2. These results indicated that pretreatment with HMGN2 inhibited cofilin phosphorylation and then induced actin disruption which may block ERK phosphorylation. These changes led to inhibition of K. pneumoniae 03183 invasion of T 24 bladder epithelial cells.