FIG 4.

Synergistic effect of Chlamydia pneumoniae with CNTs on IL-1β secretion from macrophages requires uptake of bacteria into cells but not lysosomal maturation. (A) Cells stimulated with or without C. pneumoniae in the presence or absence of CNTs were incubated with either 2 μM cytochalasin D (an actin polymerization inhibitor) or 50 nM bafilomysin A1 (a vacuolar H-ATPase inhibitor) for 24 h, and then IL-1β secretion from macrophages was detected. Results are representative of three independent experiments. (B) A representative transmission electron microscopy image reveals uptake of C. pneumoniae with CNTs into a macrophage. The inset is enlarged in the right panel. Arrows, CNTs; arrowhead, C. pneumoniae. N, nucleus; sup, desalinized culture supernatants of THP-1 cells; cell, the remaining cells; CD, cytochalasin D; BAF, bafilomycin A1; Cpn, C. pneumoniae; CNT, carbon nanotube; DMSO, dimethyl sulfoxide; IL-1β, interleukin-1β.