Figure 2

Interaction of nucleolin with LVS is involved in binding and infection of human monocyte-like THP-1 cells. A: THP-1 cells were incubated in RPMI, in absence or in presence of 5 μM HB-19 pseudopeptide or 9R control peptide. Opsonized LVS transformed with GFP expressing plasmid (LVS-GFP) were then added for 30 min. THP-1 cells were analyzed by fluorescence microscopy. Fifteen fields containing average of 100 cells were examined to quantify number of bacteria bound on human cells. Data show mean from three independent experiments ± SD values indicated as error bars. * = p < 0.01, indicates significant difference for HB-19-treated group compared to control group with 9R peptide. B: Intracellular replication of LVS. THP-1 cells were incubated with RPMI, 5 μM HB-19 or 9R before addition of opsonized LVS for 30 min. Cells were washed with RPMI containing gentamicin to kill extracellular bacteria and incubated in RPMI-FCS and gentamicin for indicated times. Quantification of intracellular bacteria was performed as described in Methods. Results show mean from three independent experiments, each performed in triplicate ± SD values indicated as error bars. C: THP-1 cells were incubated either with RPMI, 10 μM HB-19 alone or in presence of anti-CR3 Mab, 10 μM 9R or F3, or anti-CR3 Mab. Opsonized LVS were added for 30 min. Cells were washed with RPMI containing gentamicin and incubated in RPMI-FCS and gentamicin for 22 h. Quantification of intracellular bacteria was performed as described in Methods. Results show mean from five independent experiments, each performed in triplicate ± SD values indicated as error bars.