B. canis infects and replicates in canine trophoblasts without inducing cytotoxicity, but inducing proinflammatory chemokines.
Trophoblasts isolated from 6 term placentas (1x105cells) were infected with B. canis at MOI 250 for up to 48 h. (A) After addition of antibiotics to kill extracellular bacteria, cells were lysed at 2, 24 and 48h to enumerate CFU counts. (B) Culture supernatants from trophoblasts uninfected and infected with B. canis were harvested at 24 and 48 h p.i. to measure lactate dehydrogenase (LDH) activity. Values in A and B are means ± SD of duplicate measurements from three independent experiments. Asterisks indicate significant differences between 24 and 48h p.i (** p<0.01, Mann-Whitney test). (C) Culture supernatants were harvested at 24 and 48 h p.i. to measure IL-8 and RANTES (CCL5) secretion. Culture supernatants from uninfected trophoblasts cultured in parallel under the same conditions were harvested as controls. Values are means ± SD of duplicate measurements from three independent experiments. Asterisks indicate significant differences as compared to uninfected (control) cells (* p<0.05; ** p<0.01, Student᾽s t test).
