TLR4 and periodontitis: However, if the primary trigger is circulating LPS, then GFPWT:WT chimeras with periodontitis will develop impaired GI/IR, but the GFPWT:KO chimeras with periodontitis will not, as the liver tissue resident macrophages (primarily Kupffer cells) in these animals do not express TLR4 (Fig 1A and 1B).