Sculley and Langley-Evans demonstrated that the bacterium Porphyromona gingivalis, which destroys the connective tissue and bone around the tooth root, causes the release of interleukin 8 (IL-8) and TNFα, leading to an increase in the number and activity of polymorphonuclears (PMNs), which cause the production of ROS as a host response to infection. Here, CXCL8 is linked to infection.