IL6 and infection: In addition to our published studies which had already demonstrated that P. gingivalis infection does not induce neither apoptosis nor necrosis in primary GECs and the cells are viable at least up to 120 h post-infection [1,3,35,37,40,63,68], we further confirmed that the marked decrease in IL-6 production after 6 h post-infection is not due to GEC cell death (Figure S3).