Identification of Sphingomyelinase on the Surface of Chlamydia pneumoniae: Possible Role in the Entry into Its Host Cells
Figure 5
Impact of a pretreatment of the host cells by exogenous SMase on the entry and growth of C. pneumoniae. (a) HL cells were incubated for 30 min at 37°C with either 20 or 50 mU/mL of S. aureus SMase, as indicated, either before (black bars) or after (white bars) their inoculation with C. pneumoniae (0.1 × 106 IFUs). Growth of C. pneumoniae was detected at 48 hours postinoculation. (b) Internalization of C. pneumoniae by HL cells pretreated with SMase (20 or 50 mU/mL, final concentration), followed by inoculation with metabolically labelled bacteria. Radioactivity in cells was measured after inoculation and trypsin treatment. Heparin (500 μg/mL) inhibits attachment of bacteria to the host cells and was employed as a negative control. The error bars indicate standard deviations from triplicate wells. Student’s t-test gave values of ** and *** for the difference between the cells treated with SMase and controls in DMEM.
