INFECTION WITH BRUCELLA ABORTUS AND TO FACTORS PRODUCED BY BRUCELLA-INFECTED MONOCYTES.

FERNANDEZ ANDREA; FERRERO MC; HIELPOS SOLEDAD; DELPINO M. VICTORIA; FOSSATI CARLOS A; BALDI PABLO C

Congreso; LXI Reunión Anual de la Sociedad Argentina de Inmunología; 2013

Brucella is well known to produce abortion in humans and animals, presumably by inducing a proinflammatory response that affects fetus viability. In this work we evaluated the cytokine and matrix metalloproteinase (MMP) response of human trophoblasts to Brucella infection. Swan-71, a human trophoblastic cell line, was infected with B. abortus at multiplicities of infection (MOI) from 50 to 500. After treatment with gentamicin, cells were lysed at different times post-infection (p.i.) and lysates were plated onto bacteriological agar. For each time point, intracellular CFU increased with increasing MOI. In addition, CFU counts increased between 2 and 24 h p.i., indicating the capacity of Brucella to replicate in trophoblasts. This finding was confirmed by confocal microscopy using DsRed-labeled Brucella. A significant increase of TNF-α (p<0.05) levels was detected in supernatants from infected cells (MOI 100 and 500), whereas IL-8, MCP-1 and IL-10 did not increase. MMP-9 activity as detected by zymography was unchanged except for a decrease at MOI 500 (p<0.05). To verify the capacity of trophoblasts to respond to PAMPs, Swan-71 were stimulated with different TLRs agonists. An increase of IL-8 was detected after stimulation with Pam3Cys and flagellin (p<0.01), with no change in IL-10 and TNF-α. No response to E. coli LPS was detected. To evaluate the interaction of trophoblasts and monocytes during infection (a feasible situation in the maternal-fetus interface), Swan-71 were stimulated with supernatants from Brucella-infected THP-1 cells (a monocytic cell line), detecting an increase in IL-8, MCP-1 (p<0.001) and MMP-9 (p<0.05) but no change in IL-10 and TNF-α. These findings suggest that Swan-71 cells produce TNF-α upon Brucella infection and secrete chemokines and MMP-9 upon interaction with Brucella-infected monocytes. The resulting inflammatory environment, together with modifications in MMPs levels, may affect embryo implantation and lead to abortion.