Membrane CD14, but not soluble CD14, is used by exoenzyme S from P. aeruginosa to signal proinflammatory cytokine production.

Recognition of TLR agonists involves a complex interplay among a variety of serum and cell membrane molecules, including mCD14 and sCD14 that is not fully understood. TLR activation results in downstream signaling that induces inflammatory cytokine production in response to pathogenic molecules, such as ExoS, which is a TLR2 and TLR4 agonist produced by the opportunistic pathogen Pseudomonas aeruginosa. We reasoned that responses to ExoS, a protein, might differ from canonical TLR agonists such as LPS.