CXCL8 and periodontitis: Therefore, while microbial plaque is the primary etiology and initiates the host immune response, which induces the signs of periodontitis [5], the major component of the outer membrane of Gram-negative bacteria, Porphyromonas gingivalis, lipopolysaccharide (LPS), initiates the production of various cytokines such as interleukin-8 (IL-8) and TNF-α [6] which infiltrate gingival connective tissue and elicit a local inflammatory response.