Figure 3.

The inability of Porphyromonas gingivalis to synthesize sphingolipids (SLs) leads to an enhanced cytokine and chemokine response. PMA-treated human macrophage–like THP-1 cells were directly cultured with P. gingivalis W83 (wild type [WT]; gray bars) or the P. gingivalis W83 SL-null mutant (serine palmitoyl transferase [SPT]; black bars) at a multiplicity of infection of 100. Cell culture supernatant fluids were collected at 2, 6, and 24 h of coculture, and the levels of TNFα, IL-1β, IL-6, IL-10, RANTES, and IL-8 were measured by multiplex immunoassay. Medium alone (M; white bars) served as unchallenged control. Data are presented as mean ± SEM (n = 8 independent experiments). *P < 0.05 and **P < 0.01 versus wild type (WT) P. gingivalis with unpaired t tests. PMA, phorbol 12-myristate 13-acetate.